Patent Application
20150325163
The present invention relates to an image display device, and particularly to an image display device capable of causing a background to be seen through and a driving method therefor.
In recent years, image display apparatuses capable of performing image display and causing backgrounds to be seen through have been developed. For example, Japanese Unexamined Patent Application Publication No. 5-191726 discloses a realistic-display apparatus that performs display in which an image is combined with a background.
PTL 1: Japanese Unexamined Patent Application Publication No. 5-191726
PTL 2: Japanese Unexamined Patent Application Publication No. 2008-34372
PTL 3: Japanese Unexamined Patent Application Publication No. 2006-106614
The PDLC panel can diffuse or transmit light, but may not shield light. Accordingly, black display may not be performed in the realistic-display apparatus 200 using only the PDLC panel as a panel (screen) contributing to the image display. In the realistic-display apparatus 200, the projector 201 not only functions as a light source unit but also forms an image. Accordingly, in the realistic-display apparatus 200, a position at which the projector 201 is installed is restricted to a relatively narrow range so as to appropriately set a focal distance or the like of light radiated from the projector 201.
Accordingly, an object of the present invention is to provide an image display device capable of causing a background to be seen through and realizing black display while alleviating restriction on a position at which a light source unit is installed, and a driving method therefor.
According to a first aspect of the invention, there is provided an image display device that displays an image by dividing one frame period of a supplied input signal into a plurality of sub-frame periods and switching a display color for each sub-frame period. The image display device includes: a first display panel that includes a plurality of first display elements disposed in a matrix form; and a light radiation unit that is able to radiate light of a plurality of colors to the first display panel. The light radiation unit includes a light source unit and a second display panel which is able to switch between a diffusion state in which incident light is diffused and a transmission state in which incident light is transmitted. The second display panel is in the diffusion state and diffuses light emitted by the light source unit when the image is displayed. The first display panel displays the image by controlling transmittance of the light diffused by the second display panel.
According to a second aspect of the invention, in the first aspect, the light source unit may further include a first light source unit for the second display panel. The first light source unit for the second display panel includes light-emitting elements of the plurality of colors and radiates light to the second display panel.
According to a third aspect of the invention, in the second aspect, the first light source unit for the second display panel may radiate light to one main surface of the second display panel.
According to a fourth aspect of the invention, in the third aspect, the light source unit may further include a second light source unit for the second display panel. The second light source unit for the second display panel includes light-emitting elements of the plurality of colors and radiates light to the second display panel. The first light source unit for the second display panel and the second light source unit for the second display panel may radiate light to both main surfaces of the second display panel, respectively.
According to a fifth aspect of the invention, in the second aspect, the first light source unit for the second display panel may have enough directivity to radiate light to a part of the second display panel.
According to a sixth aspect of the invention, in any one of the first to fifth aspects, the light radiation unit may further include a first light guide plate guiding incident light, and the light source unit may include a light source unit for a light guide plate. The light source unit for a light guide plate includes light-emitting elements of the plurality of colors and radiating light to the first light guide plate.
According to a seventh aspect of the invention, in the sixth aspect, the first light guide plate and the second display panel may be disposed in order on a side of the first display panel.
According to an eighth aspect of the invention, in the sixth aspect, the second display panel and the first light guide plate may be disposed in order on a side of the first display panel.
According to a ninth aspect of the invention, in the sixth aspect, the light radiation unit may further include a second light guide plate guiding incident light, the light source unit for the light guide plate may radiate light to the first light guide plate and the second light guide plate, and the first light guide plate, the second display panel, and the second light guide plate may be disposed in order on a side of the first display panel.
According to a tenth aspect of the invention, in the sixth aspect, the first light guide plate may be configured to be formed by a plurality of blocks, and the light source unit for the light guide plate may radiate light to each block.
According to an eleventh aspect of the invention, in the first aspect, the second display panel may include a plurality of second display elements each of which is switchable between the diffusion state and the transmission state.
According to a twelfth aspect of the invention, in the eleventh aspect, when the image is displayed, each of the second display elements in correspondence to one of the plurality of first display elements may be in the diffusion state in synchronization with the corresponding first display element.
According to a thirteenth aspect of the invention, in the first aspect, the image display device may further include: a first display driving unit that drives the first display panel; a second display driving unit that drives the second display panel; a light source driving unit that drives the light source unit; and a signal processing unit that controls each of the first display driving unit, the second display driving unit, and the light source driving unit based on the input signal.
According to a fourteenth aspect of the invention, in the thirteenth aspect, the signal processing unit may include a field sequential processing unit that generates field sequential image data for displaying an image for each sub-frame period based on the input signal, an image control unit that generates first display data for controlling the first display driving unit, second display data for controlling the second display driving unit, and light source data for controlling the light source driving unit, based on display image position designation data for designating a display position of the image to be displayed and the field sequential image data, which are obtained based on the input signal, a first display control unit that controls the first display driving unit based on the first display data, a second display control unit that controls the second display driving unit based on the second display data, and a light source control unit that controls the light source driving unit based on the light source data.
According to a fifteenth aspect of the invention, in the fourteenth aspect, the input signal may include the display image position designation data and image data indicating the image to be displayed, and the signal processing unit may further include a signal separation control unit that separates the input signal into the display image position designation data and the image data and supplies the display image position designation data and the image data to the image control unit and the field sequential processing unit, respectively.
According to a sixteenth aspect of the invention, in the fourteenth aspect, the field sequential processing unit may further generate the display image position designation data based on the input signal.
According to a seventeenth aspect of the invention, in the thirteenth aspect, the signal processing unit may interpolate an image to be displayed for each of continuous frame periods using the sub-frame period.
According to an eighteenth aspect of the invention, in the thirteenth aspect, the first display panel may include a display area for displaying the image of a desired color when color data is supplied for each sub-frame period, and the signal processing unit may generate the color data based on the input signal for each sub-frame period, obtain a light source light-up time designating a light-up time of the light-emitting element of a color indicated by the color data and a light source driving timing control signal for controlling at least one of a light-up start time of the light-emitting element of the color and a scanning start time at which the color data is supplied to the display area, and control the light source light-up time and the light source driving timing control signal in correspondence to a period in which the color data necessary to display the image of the desired color is supplied to the display area.
According to a nineteenth aspect of the invention, in the eighteenth aspect, the first display panel may further include a non-display area in which color data is supplied for each sub-frame period and the image is not displayed, and the color data supplied to the non-display area may be same color data for each pixel of the non-display area.
According to a twentieth aspect of the invention, in the nineteenth aspect, the signal processing unit may include a field sequential processing unit that generates field sequential image data for displaying an image for each sub-frame period based on the input signal, an image control unit that generates first display data for controlling the first display driving unit, second display data for controlling the second display driving unit, and light source data for controlling the light source driving unit and including the light-source light-up time, based on display image position designation data for designating a display position of the image to be displayed and the field sequential image data, which are obtained based on the input signal, a first display control unit that controls the first display driving unit based on the first display data, a second display control unit that controls the second display driving unit based on the second display data, and a light source control unit that controls the light source driving unit based on the light source driving timing control signal and the light source data.
According to a twenty first aspect of the invention, there is provided a driving method for an image display device that includes a first display panel including a plurality of first display elements disposed in a matrix form and a light radiation unit able to radiate light of a plurality of colors to the first display panel and including a second display panel, and that displays an image by dividing one frame period of a supplied input signal into a plurality of sub-frame periods and switching a display color for each sub-frame period. The driving method includes: a step of switching a state of the second display panel between a diffusion state in which incident light is diffused and a transmission state in which incident light is transmitted; and a step of causing the first display panel to control transmittance of light diffused by the second display panel and to display the image. The light radiation unit further includes a light source unit. The step of switching the state of the second display panel includes a step of switching the state of the second display panel to the diffusion state when the image is displayed and diffusing light emitted by the light source unit.
According to the first aspect of the invention, in the image display device of the field sequential (hereinafter appropriately abbreviated as “FS”) scheme, the image display is performed by diffusing light emitted by the light source unit by the second display panel being in the diffusion state and controlling the transmittance of the diffused light by the first display panel. Therefore, the black display can be performed by shielding the diffused light by the first display panel. Since an image to be displayed is formed by the first display panel rather than the light source unit, it is possible to alleviate the restriction on the installation position of the light source unit (a projector in Japanese Unexamined Patent Application Publication No. 5-191726). When the second display panel is in the transmission state, the background light can be transmitted. By adopting the FS scheme, it is possible to perform color image display with high resolution and high light use efficiency.
According to the second aspect of the invention, the image display can be performed by radiating light from the first light source unit for the second display panel to the second display panel and controlling the transmittance of the diffused light by the first display panel.
According to the third aspect of the invention, by radiating light to one main surface of the second display panel, it is possible to obtain the same advantageous effect as that of the second aspect of the invention.
According to the fourth aspect of the invention, since light is radiated to both main surfaces of the second display panel, it is possible to improve the luminance of the display image.
According to the fifth aspect of the invention, it is possible to allow light to be radiated to the spot to be in the diffusion state and allow light not to be radiated to the spot to be in the transmission state in the second display panel. Therefore, the spot in which the image display is performed and the spot in which the background is seen through can be allowed to appropriately coexist in one screen.
According to the sixth aspect of the invention, the image display is performed by radiating light emitted by the light source unit for the light guide plate to the second display panel via the first light guide plate and controlling the transmittance of the diffused light by the first display panel. When the first light source unit for the second display panel, the light source unit for the light guide plate, and the first light guide plate are used, it is possible to improve the luminance of the display image. When the first and second light source units for the second display panel, the light source unit for the light guide plate, and the first light guide plate are used, it is possible to further improve the luminance of the display image.
According to the seventh aspect of the invention, by disposing the first light guide plate and the second display panel in order on the side of the first display panel, it is possible to obtain the same advantageous effect as that of the sixth aspect of the invention.
According to the eighth aspect of the invention, by disposing the second display panel and the first light guide plate in order on the side of the first display panel, it is possible to obtain the same advantageous effect as that of the sixth aspect of the invention.
According to the ninth aspect of the invention, by disposing the first light guide plate, the second display panel, and the second light guide plate in order, it is possible to obtain the same advantageous effect as that of the sixth aspect of the invention. Since light emitted from each of the first and second light guide plates is diffused by the second display panel and is radiated to the first display panel, it is possible to improve the luminance of the display image.
According to the tenth aspect of the invention, since the first light guide plate formed by the blocks is used, it is possible to allow light to be radiated to the spot to be in the diffusion state and to allow light not to be radiated to the spot to be in the transmission state in the second display panel. Therefore, the spot in which the image display is performed and the spot in which the background is seen through can be allowed to appropriately coexist in one screen.
According to the eleventh aspect of the invention, the second display panel includes the plurality of second display elements and each second display element can be switched between the diffusion state and the transmission state. Therefore, the spot to be in the diffusion state and the spot to be in the transmission state can be set in the second display panel to be suitable for the display position of the image. Thus, it is possible to simultaneously perform the image display and the background transmission.
According to the twelfth aspect of the invention, since the second display element is set to the diffusion state in synchronization with the first display element, the spot to be in the diffusion state and the spot to be in the transmission state in the second display panel are set to follow the image displayed on the first display panel. Therefore, in moving-image display or the like, the diffused light from the second display panel is reliably radiated to the first display panel. Thus, it is possible to improve image quality, for example, when the moving image is displayed.
According to the thirteenth aspect of the invention, by using the signal processing unit, the first display driving unit, the second display driving unit, and the light source driving unit controlled by the signal processing unit, it is possible to reliably drive the first display panel, the second display panel, and the light source unit.
According to the fourteenth aspect of the invention, by using the signal processing unit including the FS processing unit, the image control unit, the first display control unit, the second display control unit, and the light source control unit, it is possible to reliably perform driving of the FS scheme.
According to the fifteenth aspect of the invention, since the display image position designation data is included in the input signal, it is possible to reliably reflect a display position of the image intended in a generation source of the input signal.
According to the sixteenth aspect of the invention, since the display image position designation data is generated by the FS processing unit, it is possible to set the display position of the image in real time, for example, or set the display position of the image to a position determined in advance.
According to the seventeenth aspect of the invention, since the frame interpolation is performed using the sub-frame period, smooth display of a moving image can be performed.
According to the eighteenth aspect of the invention, the light source light-up time and the light source driving timing control signal are controlled in correspondence to a period in which the color data necessary to display an image of a desired color is supplied to the display area. Therefore, the display area in which the image of the desired color is displayed and occurrence of color irregularity is suppressed can be set to a desired position of the first display panel.
According to the nineteenth aspect of the invention, the color data supplied to the non-display area is the same data for each color and for each pixel of the non-display area. Therefore, the non-display area becomes an area in which occurrence of the color irregularity is suppressed.
According to the twentieth aspect of the invention, by using the signal processing unit including the FS processing unit, the image control unit, the first display control unit, the second display control unit, and the light source control unit, it is possible to reliably perform the driving of the FS scheme.
According to the twenty first aspect of the invention, in the driving method for the image display device, it is possible to obtain the same advantageous effects as those of the first aspect of the invention.
Hereinafter, first to fourth embodiments of the invention will be described with reference to the appended drawings.
The image display device 1 displays an image on the CF-less liquid crystal panel 50 in conformity to a field sequential scheme (FS scheme). In conformity to the FS scheme, light-emitting elements such as light emitting diodes (LEDs) or cathode fluorescent lamps (CCFLs) of red (R), green (G), and blue (B) which form backlight light are switched sequentially. In the FS scheme, a transmission state is controlled by sequentially supplying color data corresponding to the colors of light of the light-emitting elements to a liquid crystal panel in synchronization with the sequential switching of the light-emitting elements, so that additive color mixing is performed for retinae of an observer. According to the FS scheme, since color display can be performed without forming a plurality of sub-pixels in one pixel, a high resolution can be realized. Since light from the light-emitting elements can be used without change, it is unnecessary to form the CF in each pixel (that is, a CF-less configuration is realized), and thus light use efficiency of each light-emitting element is improved.
The signal processing circuit 10 receives an input signal IN from the outside and controls the CF-less liquid crystal display element driving circuit 20, the PDLC display element driving circuit 30, and the light source driving circuit 40 based on the input signal IN. More specifically, the signal processing circuit 10 supplies a CF-less liquid crystal display element signal CS for controlling the CF-less liquid crystal display element driving circuit 20 to the CF-less liquid crystal display element driving circuit 20, supplies a PDLC display element signal PS for controlling the PDLC display element driving circuit 30 to the PDLC display element driving circuit 30, and supplies a light source signal LS for controlling the light source driving circuit 40 to the light source driving circuit 40.
The CF-less liquid crystal display element driving circuit 20 drives the CF-less liquid crystal panel 50 based on the received CF-less liquid crystal display element signal CS. The PDLC display element driving circuit 30 drives the PDLC panel 60 based on the received PDLC display element signal PS. The light source driving circuit 40 drives the first PDLC light source unit 70a based on the received light source signal LS.
The PDLC panel 60 may be configured to be switchable to an intermediate state in which incident light is diffused and transmitted in addition to the diffusion state and the transmission state. In other words, the PDLC panel 60 may be configured to be switched between the diffusion state in which diffusivity is relatively high, the transmission state in which diffusivity is relatively low, and the intermediate state in which diffusivity is a value between the value at the time of the diffusion state and the value at the time of the transmission state. Here, the “diffusivity” in the present specification refers to a value indicating how much incident light is diffused. The larger the value of the diffusivity is, the larger the degree of diffusion is. The diffusivity of the PDLC panel 60 is controlled with an application voltage. For example, the larger the application voltage is, the smaller the diffusivity is. The larger the diffusivity of the PDLC panel 60 is, the larger the application voltage is. A plurality of kinds of intermediate states may be set. Use of the intermediate state of the PDLC panel 60 will be described below.
Here, the light source 71 is not limited to the case in which one red light-emitting element 71r, one green light-emitting element 71g, and one blue light-emitting element 71b are included. For example, the light source 71 may include two red light-emitting elements 71r, two green light-emitting elements 71g, and one blue light-emitting element 71b in some cases. Alternatively, the light source 71 may include one red light-emitting element 71r, two green light-emitting elements 71g, and one blue light-emitting element 71b in some cases. The number of light sources 71 is not limited to the plurality. The number of light sources 71 may be one. The color of light emitted by one white LED may be switched using fluorescents or CFs emitting red, green, and blue light.
The CF-less liquid crystal panel 50 displays an image by controlling the transmittance of light radiated from the light radiation unit 90 formed by the PDLC panel 60 and the first PDLC light source unit 70a. The radiation of light toward the CF-less liquid crystal panel 50 will be described in detail below.
In the embodiment, an input signal IN includes display image position designation data Da designating the display position of an image to be displayed and image data ID indicating the image to be displayed. The signal separation control unit 11 receives the input signal IN and separates the input signal IN into the display image position designation data Da and the image data ID. The signal separation control unit 11 supplies the display image position designation data Da to the image control unit 14 and supplies the image data ID to the FS processing unit 12.
The FS processing unit 12 generates a field sequential image data (FS image data) FID for displaying an image for each sub-frame period based on the received image data ID and supplies the generated FS image data FID to the image control unit 14. More specifically, for example, when the FS processing unit 12 receives the image data ID with a frame rate of 60 fps, the FS processing unit 12 converts the image data ID into image data ID with a frame rate of 240 fps (performs frame rate conversion). Then, based on the image data ID with the frame rate of 240 fps, the FS processing unit 12 generates red, green, and blue FS image data FID of a frame rate of 240 fps. Hereinafter, an image indicated by the image data ID is referred to as a “frame image” and an image indicated by the FS image data FID is referred to as a “sub-frame image” in some cases. The frame rate after the above-described frame rate conversion is not limited to 240 fps. When a response speed of each display element can be handled, the frame rate is preferably higher.
When the FS processing unit 12 generates the FS image data FID, the FS processing unit 12 uses information retained by the memory 13. The information retained by the memory 13 specifically indicates a focal distance of the first PDLC light source unit 70a (the light source unit 100) and the diffusivity of each PDLC display element 61. Thus, the FS image data FID includes data according to the number of divisions of an area (hereinafter referred to as a “division area”) in which the state of the PDLC panel 60 is independently controlled, and expansion of light from each division area, and the like. Hereinafter, an area of the CF-less liquid crystal panel 50 corresponding to (more specifically facing) the division area of the PDLC panel 60 is also referred to as a “division area” in some cases. A register which sets information regarding a focal distance of the first PDLC light source unit 70a (the light source unit 100), a diffused amount of light radiated to each PDLC display element 61, and the like may be installed instead of the memory 13 or along with the memory 13.
Based on the display image position designation data Da and the FS image data FID, the image control unit 14 generates CF-less liquid crystal data CD for controlling the CF-less liquid crystal display element signal control unit 16, PDLC data PD for controlling the PDLC display element signal control unit 17, light source data LD for controlling the light source signal control unit 18, and a driving timing control signal DT for adjusting timings by synchronizing output signals of the CF-less liquid crystal display element signal control unit 16, the PDLC display element signal control unit 17, and the light source signal control unit 18. In other words, the driving timing control signal DT is a signal controlling an operation start time of each panel or unit (hereinafter referred to as “each module”) of the CF-less liquid crystal panel 50, the PDLC panel 60, and the first PDLC light source unit 70a to synchronize the CF-less liquid crystal panel 50, the PDLC panel 60, and the first PDLC light source unit 70a. The image control unit 14 supplies the driving timing control signal DT, the CF-less liquid crystal data CD, the PDLC data PD, and the light source data LD to the timing designation control unit 15, the CF-less liquid crystal display element signal control unit 16, the PDLC display element signal control unit 17, and the light source signal control unit 18, respectively. The detailed configuration of the image control unit 14 will be described below.
The timing designation control unit 15 receives the driving timing control signal DT generated by the image control unit 14 and generates a CF-less liquid crystal timing designation signal CT designating a driving timing of each CF-less liquid crystal display element 51, a PDLC timing designation signal PT designating a driving timing of each PDLC display element 61, and a light source timing designation signal LT designating a driving timing of each light source 71 based on the driving timing control signal DT. The timing designation control unit 15 can use the memory 13 or the register (not illustrated) installed outside the timing designation control unit 15, for example, when the timing designation control unit 15 generates the CF-less liquid crystal timing designation signal CT, the PDLC timing designation signal PT, and the light source timing designation signal LT. The timing designation control unit 15 supplies the generated CF-less liquid crystal timing designation signal CT, PDLC timing designation signal PT, and light source timing designation signal LT to the CF-less liquid crystal display element signal control unit 16, the PDLC display element signal control unit 17, and the light source signal control unit 18, respectively.
The CF-less liquid crystal display element signal control unit 16 generates a CF-less liquid crystal display element signal CS based on the received CF-less liquid crystal data CD and CF-less liquid timing designation signal CT and supplies the CF-less liquid crystal display element signal CS to the CF-less liquid crystal display element driving circuit 20.
The PDLC display element signal control unit 17 generates a PDLC display element signal PS based on the received PDLC data PD and PDLC timing designation signal PT and supplies the PDLC display element signal PS to the PDLC display element driving circuit 30.
The light source signal control unit 18 generates a light source signal LS based on the received light source data LD and light source timing designation signal LT and supplies the light source signal LS to the light source driving circuit 40.
The display image data generation unit 141 receives the display image position designation data Da and the FS image data FID and generates the CF-less liquid crystal data CD as display image data corresponding to a display image based on the display image position designation data Da and the FS image data FID. The CF-less liquid crystal display element signal control unit 16 can set transmittance of each CF-less liquid crystal display element 51 in the CF-less liquid crystal panel 50 based on the CF-less liquid crystal data CD.
The white data generation unit 142 receives the display image position designation data Da and generates the PDLC data PD as white data for causing a part or the entirety of the PDLC panel 60 to be white (diffusion state) based on the display image position designation data Da. Based on the PDLC data PD, the PDLC display element signal control unit 17 can set the state of the PDLC panel 60 according to the position of the display image. More specifically, the PDLC panel 60 is in the diffusion state at a position corresponding to the display image. However, the state of the entire PDLC panel 60 may be set uniformly. In this case, it is unnecessary to supply the display image position designation data Da to the white data generation unit 142 and it is unnecessary to supply the PDLC timing designation signal PT to the PDLC display element signal control unit 17.
The light source data generation unit 143 receives the display image position designation data Da and the FS image data FID and generates the light source data LD based on the display image position designation data Da and the FS image data FID. The light source signal control unit 18 can set a light-up time or the like of the light-emitting element of each color based on the light source data LD. When the first PDLC light source unit 70a has enough directivity to radiate light to a part of the PDLC panel 60, the light source signal control unit 18 controls the light source driving circuit 40 such that the first PDLC light source unit 70a individually radiate light-source light to each division area of the PCLC panel 60. The light source signal control unit 18 may designate the light-emitting elements to light up according to the position of the display image based on the light source data LD. When the light source signal control unit 18 may not necessarily designate the light-emitting elements to light up according the position of the display image, the light source data generation unit 143 may not be supplied with the display image position designation data Da.
The timing processing unit 144 receives the display image position designation data Da and the FS image data FID and generates the driving timing control signal DT based on the display image position designation data Da and the FS image data FID. More specifically, the timing processing unit 144 generates the driving timing control signal DT based on a desired relation which is a relation between scanning driving start times of the CF-less liquid crystal panel 50 and the PDLC panel 60 and the light-up start time of the light-emitting elements and which can be obtained from the display image position designation data Da and the FS image data FID.
First, a case (the time of image display) in which the pixels of interest form an image will be described. In this case, no voltage is applied to the PDLC display elements 61 and the PDLC display elements 61 are in the diffusion state. At this time, the first PDLC light source unit 70a radiates the light-source light to a division area (hereinafter referred to as a “division area of interest”: a division area of the CF-less liquid crystal panel 50 including the pixel of interest is also likewise referred to as a “division area of interest”) of the PDLC panel 60 including the pixel of interest. Therefore, the light-source light incident on the PDLC display elements 61 is diffused and a substantially vertical component (hereinafter referred to as a “front-surface-direction vertical component”) oriented toward the CF-less liquid crystal display elements 51 in the diffused light-source light is emitted to the CF-less liquid crystal display elements 51. Further, light from the rear surface of the PDLC display elements 61 (the image display device 1), i.e., light (hereinafter referred to as “background light”) indicating a background including the exhibition object 110, is also incident on the PDLC display elements 61. As described above, since the PDLC display elements 61 are in the diffusion state, the background light incident on the PDLC display elements 61 is diffused and the front-surface-direction vertical component of the diffused background light is emitted to the CF-less liquid crystal display elements 51.
In this way, at the time of the image display, the light radiation unit 90 formed by the PDLC panel 60 and the first PDLC light source unit 70a radiates the diffused light-source light and light formed by the front-surface-direction vertical component of the background light to the CF-less liquid crystal panel 50 (the CF-less liquid crystal display elements 51). Since the PDLC panel 60 diffuses the background light at the time of the image display, the background light arriving at the CF-less liquid crystal panel 50 has only the front-surface-direction vertical component after the diffusion. Therefore, an influence of the background light on the display image is sufficiently suppressed.
Next, a case (the time of non-image display) in which the pixels of interest do not form an image will be described. Here, when no image is displayed, there are two kinds of cases, i.e., a case (hereinafter referred to as “the time of entire surface non-display”) in which no image is displayed on the entire surface of the CF-less liquid crystal panel 50 and a case (hereinafter referred to as “the time of partial non-display”) in which the pixel of interest does not form an image, but a pixel forming an image is present besides. Of the time of the entire surface non-display and the time of the partial non-display, the time of entire surface non-display will be first described. In the embodiment, in a portion in which no image is displayed, relatively high transmittance is assumed to be set in the CF-less liquid crystal display elements 51 in order that the background can be seen through. When the background may not necessarily be seen through, the transmittance of the CF-less liquid crystal display elements 51 may also be set to a relatively low value (that is, black display) in the portion in which no image is displayed. In the portion in which no image is displayed, the PDLC display elements 61 may be in the diffusion state or the intermediate state. In this way, it is possible to adjust the degree of the background to be seen through. For example, the background may be slightly seen through. Even in a portion in which an image is displayed, the background may be seen through slightly within a range in which image quality does not deteriorate by setting the PDLC display elements 61 such that the PDLC display elements 61 be in the intermediate state. Thus, when the intermediate state of the PDLC display element 61 (the PDLC panel 60) is used, various kinds of display can be realized.
At the time of entire surface non-display, a voltage is applied to the PDLC display elements 61, and thus these PDLC display elements 61 be in the transmission state. The light-source light is not emitted from the first PDLC light source unit 70a to any division area of the PDLC panel 60. Therefore, only the background light transmitted through the PDLC display elements 61 is radiated to the CF-less liquid crystal display elements 51. In this way, the background is seen through.
At the time of the partial non-display, the PDLC display elements 61 be in the transmission state as in the time of entire surface non-display. Unlike the time of entire surface non-display, on the other hand, the light-source light is not emitted to the division area of interest from the first PDLC light source unit 70a and the light-source light is emitted from the first PDLC light source unit 70a to the other division areas. Thus, the background light transmitted through the PDLC display elements 61 is radiated to the CF-less liquid crystal display elements 51 of the division area in which no image display is performed, and the diffused light-source light and light with the front-surface-direction vertical component are emitted to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, it is possible to simultaneously perform the image display and the background transmission, and a spot in which the image display is performed and a spot in which the background transmission is performed can be allowed to appropriately coexist in one screen. However, when the first PDLC light source unit 70a does not have enough directivity to radiate light to a part of the PDLC panel 60, the light-source light is not radiated for each division area. For example, the light-source light is radiated to the entire surface of the PDLC panel 60.
Next, an operation of displaying a color image in the embodiment will be described. Hereinafter, a case in which a read image is mainly displayed in driving of an FS scheme (hereinafter referred to as “FS driving”) of sequentially displaying red, green, and blue images will be exemplified. However, the invention is not limited thereto. In the FS driving, images with any color of a plurality of colors may be displayed sequentially, for example, images of red, green, green, and blue colors may be displayed sequentially. The invention is applied even to a case in which images with any two colors or all colors among three red, green, and blue colors are displayed. The invention is also likewise applied not only to the FS driving of displaying red, green, and blue images in order and displaying color images but also to other FS driving such as FS driving of sequentially displaying, for example, cyan (C), magenta (M), and yellow (Y) images or FS driving in which color states coexist in a screen in combination with local dimming driving.
When full-color display is not necessary, images may be displayed in the order of white, white, white, and white colors, the order of red, red, red, and red colors, or the like. In this case, the light sources 71 may not necessarily have a plurality of colors. In this case, one frame period may not necessarily be divided into a plurality of sub-frame periods. In such a configuration, it is possible to improve power efficiency of the first PDLC light source unit 70a.
Here, the “red image” in the present specification will be defined. The “red image” refers to a red image with the maximum luminance. In the FS driving in which one frame is formed by three red, green, and blue sub-frames, an image when data with the maximum transmission amount of red light is supplied as red data and data with the minimum transmission amount of green and blue light is supplied as the blue and green data to the CF-less liquid crystal panel 50 is referred to as the “red image.” Hereinafter, data with the maximum transmission amount of each color light is referred to as “transmission data” and data with the minimum transmission amount of each color light is referred to as “shielding data.”
For a first sub-frame period, as shown in Section A of
For a second sub-frame period, as shown in Section A of
For a third sub-frame period, as shown in Section A of
In this way, the red image is displayed on the screen. The timing of each scanning driving and the light-up timing of each light-emitting element indicated herein are not particularly limited. As shown in section C of
According to the embodiment, in the image display device 1 of the FS scheme, the image display is performed by diffusing the light-source light emitted from the light source unit 100 (first PDLC light source unit 70a) by the PDLC panel 60 in the diffusion state and controlling the transmittance of the diffused light (more specifically, the front-surface-direction vertical component of the diffused light) by the CF-less liquid crystal panel 50. Therefore, by shielding the diffused light by the CF-less liquid crystal panel 50, it is possible to realize the black display. Since an image to be displayed is formed by the CF-less liquid crystal panel 50 rather than the light source unit 100, it is possible to alleviate the restriction on the installation position of the light source unit 100. When the PDLC panel 60 is in the transmission state, the background light can be transmitted. By adopting the FS scheme, it is possible to perform color image display with high resolution and high use efficiency of light.
According to the embodiment, the PDLC panel 60 includes the plurality of PDLC display elements 61 and each PDLC display element 61 can be switched between the diffusion state and the transmission state. Therefore, in the PDLC panel 60, the spot to be in the diffusion state and the spot to be in the diffusion state can be set to be suitable for the display position of the image. Thus, it is possible to simultaneously perform the image display and the background transmission.
According to the embodiment, the light-source light can be radiated to the spot to be in the diffusion state in the PDLC panel 60 and the light-source light may not be radiated to the spot to be in the transmission state. Therefore, the spot in which the image display is performed and the spot in which the background transmission is performed can be allowed to appropriately coexist in one screen.
According to the embodiment, since the PDLC display element 61 is set to the diffusion state in synchronization with the CF-less liquid crystal display element 51, the spot to be in the diffusion state and the spot to be in the transmission state in the PDLC panel 60 are set to follow the image displayed on the CF-less liquid crystal panel 50. Therefore, for example, in display of a moving image, the diffused light from the PDLC panel 60 is reliably radiated to the CF-less liquid crystal panel 50. Thus, it is possible to improve image quality at the time of display of a moving image.
According to the embodiment, by using the intermediate state of the PDLC display element 61 (the PDLC panel 60), it is possible to perform various kinds of display.
According to the embodiment, by using the signal processing circuit 10 including the FS processing unit 12, the image control unit 14, the CF-less liquid crystal display element signal control unit 16, the PDLC display element signal control unit 17, and the light source signal control unit 18, it is possible to reliably perform the FS driving.
According to the embodiment, since the display image position designation data Da is included in the input signal IN, the intended display position of the image can be reliably reflected in the generation source of the input signal IN.
According to the embodiment, by using the CF-less liquid crystal timing designation signal CT, the PDLC timing designation signal PT, and the light source timing designation signal LT generated based on the driving timing control signal DT, it is possible to reliably control the driving of each CF-less liquid crystal display element 51, each PDLC display element 61, and each light source 71. By separating the timing designation control unit 15 from the image control unit 14 and using the memory 13, the register, or the like, it is easy to individually adjust an operation start time of each module, as necessary.
According to the embodiment, by radiating the light-source light to the rear surface of the PDLC panel 60, the light-source light of the first PDLC light source unit 70a is efficiently used when a diffusion effect in a transmission direction (which refers to a direction in which the incident light is transmitted) of the PDLC panel 60 is higher than a diffusion effect in a reflection direction (which refers to a direction in which the incident light is reflected). More specifically, the front-surface-direction vertical component of the diffused light-source light increases. Therefore, it is possible to improve the luminance of the display image.
According to the embodiment, as described above, when the first PDLC light source unit 70a has enough directivity to radiate light to a part of the PDLC panel 60, the first PDLC light source unit 70a can radiate the light-source light to each division area. Therefore, it is possible to perform so-called area active-driving (also called local dimming driving) of adjusting light intensity of the light-source light for each division area. Through such area active-driving, as in the FS driving, it is possible to suppress so-called color breakup which easily occurs when a screen of another color component is switched at a high speed. Since the light-source light can be emitted from the first PDLC light source unit 70a in accordance with the scanning directions of the CF-less liquid crystal panel 50 and the PDLC panel 60, it is possible to suppress the above-described color irregularity further than when the light-source light is uniformly emitted to the entire surface of the PDLC panel 60. At this time, the scanning of the light-source light may not necessarily be tuned in accordance with the scanning direction of the PDLC panel 60. By tuning the scanning of the light-source light in accordance with the scanning direction of the CF-less liquid crystal panel 50, it is possible to suppress the foregoing color irregularity.
In the above description, the mode in which the light-up state and the light-off state are controlled for each color has been exemplified as the example in which each light source 71 controls light intensity for each color, but the invention is not limited thereto. For example, each light source 71 may control the light-up state and the light-off state for each color and control light intensity of the light-up state for each color. Thus, it is possible to adjust white balance in a portion in which the image is displayed. Further, it is possible to lessen (or zero) light intensity of a color unnecessary in the image.
The FS processing unit 12 can simultaneously perform, for example, a process (generating the FS image data FID or the like) of performing the FS driving and a process (hereinafter referred to as a “first process”) of determining the display position of an image in real time through a frame interpolation process or the like and designating a position on the screen at which the background light is not allowed to be transmitted. For example, the FS processing unit 12 can simultaneously perform the process of performing the FS driving and a process (hereinafter referred to as a “second process”) of setting the display position of an image using the memory 13, the register (not illustrated), or the like installed outside the FS processing unit 12 and designating a position in the screen at which the background light is not allowed to be transmitted. In this case, the memory 13 retains information regarding the display position of the image.
An example of the first process is a process of determining that a given pixel (hereinafter referred to as a “corresponding pixel”) is a non-display position of the image when data (that is, data desired to be transmitted or of which color display is not necessary) of which three primary color signal values included in the input signal IN (image data ID) are mutually identical is output and the data in a constant range of the corresponding pixel is the data of which three primary color signal values are mutually identical as in the corresponding pixel. In the first process, the display position of the image can be set in real time without including the display image position designation data Da in the input signal IN and the state of each PDLC display element 61 can be set according to the display position. When data of which the three primary color signal values included in the input signal IN are mutually similar is output and each piece of data in the constant range of the corresponding pixel is data of which the three primary color signal values are mutually similar as in the corresponding pixel, the corresponding pixel may be determined to be located at the non-display position of the image.
As the foregoing second process, for example, by designating a predetermined region in the screen as a region in which the background is not allowed to be seen through, the image can be displayed in the predetermined region which is determined in advance and the state of each PDLC display element 61 can be set according to the position of the predetermined region without including the display image position designation data Da in the input signal IN.
When the FS image data FID is generated based on the image data ID included in the input signal IN, the FS processing unit 12 performs frame interpolation using the sub-frame periods. For example, the FS processing unit 12 sets the second sub-frame image (a sub-frame image including the display spot 92g) and the third sub-frame image (a sub-frame image including the display spot 92b) of an N-th frame as frame interpolation images. Therefore, as shown in Section B of
According to the modification example, since the frame interpolation is performed using the sub-frame periods, it is possible to smoothly display a moving image.
In the embodiment, by radiating the light-source light to the front surface of the PDLC panel 60, it is possible to obtain the same advantageous effects as those of the foregoing first embodiment. When the diffusion effect in the reflection direction of the PDLC panel 60 is higher than the diffusion effect in the transmission direction, the light-source light of the first PDLC light source unit 70a is efficiently used for the image display. More specifically, the front-surface-direction vertical component of the diffused light-source light increases. Therefore, it is possible to improve the luminance of the display image.
In the modification example, since the light-source light is radiated to the rear and front surfaces of the PDLC panel 60, it is possible to improve the luminance of the display image irrespective of a magnitude relation between the diffusion effect in the reflection direction of the PDLC panel 60 and the diffusion effect in the transmission direction.
In a second embodiment of the invention, a light guide plate is used. Of the constituent elements of the embodiment, the same constituent elements as those of the foregoing first embodiment are denoted by the same reference numerals and the description thereof will be appropriately omitted.
In the embodiment, the first light guide plate 83a is configured to be formed by a plurality (in
At the time of the image display, no voltage is applied to the PDLC display elements 61 and the PDLC display elements 61 are in the diffusion state. At this time, the light-source light emitted by the light source unit 81 for the light guide plate is guided by the first light guide plate 83a and is emitted to each division area of interest of the CF-less liquid crystal panel 50 and the PDLC panel 60. More specifically, the light-source light is emitted from the light source unit 81 for the light guide plate to the block (hereinafter referred to as a “block of interest”) corresponding to the division area of interest and the light-source light guided by the block of interest is emitted to each division area of interest of the CF-less liquid crystal panel 50 and the PDLC panel 60. Therefore, the light-source light incident on the PDLC display elements 61 is diffused and the front-surface-direction vertical component of the diffused light-source light is transmitted through the first light guide plate 83a to be emitted to the CF-less liquid crystal display elements 51. The background light is also incident on the PDLC display elements 61. As described above, since the PDLC display elements 61 are in the diffusion state, the background light incident on the PDLC display elements 61 is diffused and the front-surface-direction vertical component of the diffused background light is transmitted through the first light guide plate 83a to be emitted to the CF-less liquid crystal display elements 51. Hereinafter, the light-source light emitted to the rear surface side of the first light guide plate 83a is referred to as “source light of rear surface emitted light” and the light-source light emitted to the front surface side of the first light guide plate 83a is referred to as “source light of front surface emitted light” to facilitate the description thereof.
In this way, at the time of the image display, the light radiation unit 90 formed by the PDLC panel 60 and the backlight unit 80 radiates light formed by the source light of the front surface emitted light, the front-surface-direction vertical component of the diffused source light of the rear surface emitted light, and the front-surface-direction vertical component of the diffused background light to the CF-less liquid crystal panel 50 (the CF-less liquid crystal display elements 51). At the time of the image display, since the PDLC panel 60 diffuses the background light, the background light arriving at the CF-less liquid crystal panel 50 has only the front-surface-direction vertical component after the diffusion. Therefore, an influence of the background light on the display image is sufficiently suppressed.
At the time of the entire surface non-display, a voltage is applied to the PDLC display elements 61 and the PDLC display elements 61 are in the transmission state. The light-source light is not emitted from the light source unit 81 for the light guide plate to any block of the first light guide plate 83a. Therefore, only the background light transmitted through the PDLC display elements 61 and the first light guide plate 83a is radiated to the CF-less liquid crystal display elements 51. Thus, the background is seen through.
At the time of the partial non-display, the PDLC display elements 61 are in the transmission state, as in the time of the entire surface non-display. Unlike the time of the entire surface non-display, on the other hand, the light-source light is not emitted from the light source unit 81 for the light guide plate to the blocks of interest and the light-source light is emitted from the light source unit 81 for the light guide plate to the other blocks. In this way, the background light transmitted through the PDLC display elements 61 and the first light guide plate 83a is radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is not performed. Light formed by the source light of the front surface emitted light, the front-surface-direction vertical component of the diffused source light of the rear surface emitted light, and the front-surface-direction vertical component of the diffused background light is radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, the image display and the background transmission can be simultaneously performed and the spot in which the image display is performed and the spot in which the background transmission is performed can be allowed to appropriately coexist in one screen.
Incidentally, light guide plates can broadly be classified into two kinds of front-light light guide plates and backlight light guide plates. Even in the two kinds of light guide plates, the light-source light is emitted to both of the front and rear surface sides. Therefore, the first light guide plate 83a adopted in the above-described configuration may be either of the front-light light guide plate and the backlight light guide plate. In the front-light light guide plate, the source light of the rear surface emitted light is greater and the source light of the front surface emitted light is smaller than the backlight light guide plate. The configuration of the front-light light guide plate is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2006-106614.
According to the embodiment, the light-source light emitted by the light source unit 81 for the light guide plate is radiated to the PDLC panel 60 via the first light guide plate 83a. By controlling the transmittance of the diffused light by the CF-less liquid crystal panel 50, the image display is performed. Thus, it is possible to obtain the same advantageous effects as those of the foregoing first embodiment.
According to the embodiment, since the first light guide plate 83a formed by the blocks is used, the light-source light can be allowed to be radiated to the spot in the diffusion state in the PDLC panel 60 and not to be radiated to the spot in the transmission state. Therefore, the spot in which the image display is performed and the spot in which the background is seen through can be allowed to appropriately coexist in one screen. Since the light-source light can be radiated to each division area by the first light guide plate 83a formed by the blocks, the area active-driving can be performed as in the foregoing first embodiment. Through the area active-driving, as in the FS driving, it is possible to suppress so-called color breakup which easily occurs when a screen of another color component is switched at a high speed. Since the light-source light can be emitted from the block in accordance with the scanning directions of the CF-less liquid crystal panel 50 and the PDLC panel 60, it is possible to suppress the above-described color irregularity further than when the light-source light is uniformly emitted to the entire surface of the PDLC panel 60. At this time, the scanning of the light-source light may not necessarily be tuned with the scanning direction of the PDLC panel 60. By tuning the scanning of the light-source light with the scanning direction of the CF-less liquid crystal panel 50, it is possible to suppress the foregoing color irregularity.
According to the embodiment, when the diffusion effect in the reflection direction of the PDLC panel 60 is higher than the diffusion effect in the transmission direction, the source light of the rear surface emitted light of the first light guide plate 83a can be efficiently used for the image display by disposing the first light guide plate 83a and the PDLC panel 60 in order on the side of the CF-less liquid crystal panel 50. More specifically, the front-surface-direction vertical component of the diffused source light of the rear surface emitted light increases. Therefore, it is possible to improve the luminance of the display image. Further, since the front-surface-direction vertical component of the diffused background light decreases, it is possible to sufficiently suppress the influence of the background light on the display image.
In this way, at the time of the image display, the light radiation unit 90 formed by the PDLC panel 60 and the backlight unit 80 radiates light formed by the front-surface-direction vertical component of the diffused source light of the front surface emitted light and the front-surface-direction vertical component of the diffused background light to the CF-less liquid crystal panel 50 (the CF-less liquid crystal display elements 51). At the time of the image display, since the PDLC panel 60 diffuses the background light, the background light arriving at the CF-less liquid crystal panel 50 has only the front-surface-direction vertical component after the diffusion. Therefore, an influence of the background light on the display image is sufficiently suppressed.
At the time of the entire surface non-display, a voltage is applied to the PDLC display elements 61 and the PDLC display elements 61 are in the transmission state. The light-source light is not emitted from the light source unit 81 for the light guide plate to any block of the first light guide plate 83a. Therefore, only the background light transmitted through the PDLC display elements 61 and the first light guide plate 83a is radiated to the CF-less liquid crystal display elements 51. Thus, the background is seen through.
At the time of the partial non-display, the PDLC display elements 61 are in the transmission state, as in the time of the entire surface non-display. Unlike the time of the entire surface non-display, on the other hand, the light-source light is not emitted from the light source unit 81 for the light guide plate to the blocks of interest and the light-source light is emitted from the light source unit 81 for the light guide plate to the other blocks. In this way, the background light transmitted through the PDLC display elements 61 and the first light guide plate 83a are radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is not performed. Light formed by the front-surface-direction vertical component of the diffused source light of the front surface emitted light and the front-surface-direction vertical component of the diffused background light is radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, as in the foregoing second embodiment, the image display and the background transmission can be simultaneously performed and the spot in which the image display is performed and the spot in which the background is seen through can be allowed to appropriately coexist in one screen.
In the modification example, by disposing the PDLC panel 60 and the first light guide plate 83a in order on the side of the CF-less liquid crystal panel 50, it is possible to obtain the same advantageous effects as those of the foregoing second embodiment. When the diffusion effect in the transmission direction of the PDLC panel 60 is higher than the diffusion effect in the reflection direction, the source light of the front surface emitted light of the first light guide plate 83a is efficiently used for the image display. More specifically, the front-surface-direction vertical component of the source light of the front surface emitted light increases. Therefore, it is possible to improve the luminance of the display image. In the modification example, when the backlight light guide plate in which the source light of the front surface emitted light is more than the source light of the rear surface emitted light is adopted as the foregoing first light guide plate 83a, it is possible to further improve the luminance of the display image.
In this way, at the time of the image display, the light radiation unit 90 formed by the PDLC panel 60 and the backlight unit 80 radiates light formed by the source light of the front surface emitted light of the first light guide plate 83a, the front-surface-direction vertical components of the diffused source light of the rear surface emitted light of the first light guide plate 83a and the source light of the front surface emitted light of the second light guide plate 83b, and the front-surface-direction vertical component of the diffused background light to the CF-less liquid crystal panel 50 (the CF-less liquid crystal display elements 51). At the time of the image display, since the PDLC panel 60 diffuses the background light, the background light arriving at the CF-less liquid crystal panel 50 has only the front-surface-direction vertical component after the diffusion. Therefore, an influence of the background light on the display image is sufficiently suppressed.
At the time of the entire surface non-display, a voltage is applied to the PDLC display elements 61 and the PDLC display elements 61 are in the transmission state. The light-source light is not emitted from the light source unit 81 for the light guide plate to any block of the first light guide plate 83a or any block of the second light guide plate 83b. Therefore, only the background light transmitted through second light guide plate 83b, the PDLC display elements 61, and the first light guide plate 83a is radiated to the CF-less liquid crystal display elements 51. Thus, the background is seen through.
At the time of the partial non-display, the PDLC display elements 61 are in the transmission state, as in the time of the entire surface non-display. Unlike the time of the entire surface non-display, on the other hand, the light-source light is not emitted from the light source unit 81 for the light guide plate to the blocks of interest of the first and second light guide plates 83a and 83b and the light-source light is emitted from the light source unit 81 for the light guide plate to the other blocks of the first and second light guide plates 83a and 83b. In this way, the background light transmitted through the second light guide plate 83b, the PDLC display elements 61, and the first light guide plate 83a is radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is not performed. Light formed by the source light of the front surface emitted light of the first light guide plate 83a, the front-surface-direction vertical components of the diffused source light of the rear surface emitted light of the first light guide plate 83a and the source light of the front surface emitted light of the second light guide plate 83b, and the front-surface-direction vertical component of the diffused background light is radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, the image display and the background transmission can be simultaneously performed and the spot in which the image display is performed and the spot in which the background is seen through can be allowed to appropriately coexist in one screen.
In the modification example, by disposing the first light guide plate 83a, the PDLC panel 60, and the second light guide plate 83b in order on the side of the CF-less liquid crystal panel 50, it is possible to obtain the same advantageous effects as those of the foregoing second embodiment. In the modification example, the source light of the rear surface emitted light and the source light of the front surface emitted light respectively emitted from the first and second light guide plates 83a and 83b are diffused in the PDLC panel 60, and the front-surface-direction vertical components thereof are radiated to the CF-less liquid crystal panel 50. Therefore, it is possible to improve the luminance of the display image irrespective of a magnitude relation between the diffusion effect in the reflection direction of the PDLC panel 60 and the diffusion effect in the transmission direction.
In the embodiment, by using the first PDLC light source unit 70a together in the configuration of the foregoing second embodiment, the front-surface-direction vertical component of the diffused light-source light of the first PDLC light source unit 70a is added to the light radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, it is possible to improve the luminance of the display image.
In the modification example, by using the first PDLC light source unit 70a together in the configuration of the first modification example of the foregoing second embodiment, the front-surface-direction vertical component of the diffused light-source light of the first PDLC light source unit 70a is added to the light radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, it is possible to improve the luminance of the display image.
In the modification example, by using the first PDLC light source unit 70a together in the configuration of the second modification example of the foregoing second embodiment, the front-surface-direction vertical component of the diffused light-source light of the first PDLC light source unit 70a is added to the light radiated to the CF-less liquid crystal display elements 51 of the division area in which the image display is performed. Therefore, it is possible to improve the luminance of the display image.
In a fourth embodiment of the invention, the above-described color irregularity is resolved which occurs when the scanning driving of the light source is not performed in accordance with the scanning direction of the CF-less liquid crystal panel 50. Here, the color irregularity will be further described. In the description of the factors relevant to the color irregularity in the embodiment, note that the factors are omitted in some cases to facilitate the description of the driving of the PDLC panel 60.
Since an operation in each sub-frame period is the same as the operation described above, the description thereof will be omitted herein. As shown in Section B of
The display start line designation data Dal is data for designating a start position (hereinafter referred to as a “display start line” and denoted by reference numeral Xa) of a display area in which an image with no color irregularity and a desired color is displayed on a screen by adjusting at least one of a light-up time of the light-emitting element of each color, a scanning driving start time of the CF-less liquid crystal display elements 51, and a light-up time of the light-emitting element of each color. The non-display start line designation data Dn is data for designating a start position (hereinafter referred to as a “non-display start line” and denoted by a reference numeral Xn) of a non-display area in which the image with the desired color is not displayed on the screen by allowing the color data to be the same for each sub-frame period or each pixel.
The signal separation control unit 11 separates the input signal IN into the image data ID, the display image position designation data Da, the display start line designation data Dal, the non-display start line designation data Dn, and the response time data Dti, supplies the image data ID to the FS processing unit 12, and supplies the display image position designation data Da, the display start line designation data Dal, the non-display start line designation data Dn, and the response time data Dti to the image control unit 14.
The image control unit 14 generates CF-less liquid crystal data CD, PDLC data PD, light source data LD, and a driving timing control signal DT based on the display image position designation data Da, the display start line designation data Dal, the non-display start line designation data Dn, the response time data Dti, and the FS image data FID.
An operation of the light source data generation unit 143 in the embodiment will be further described. The light source data generation unit 143 obtains a maximum light source light-up time Tbm which is a time at which the light-emitting element of each color lights up so that the luminance becomes the maximum in the state of no color irregularity by expression (1), (2), or (3) below by using at least the display start line designation data Dal, the non-display start line designation data Dn, and the response time data Dti:
Tbm=T−Tl−[T*(Xn−Xa)]/X (1);
Tbm=T (2); and
Tbm=T−Tl−[T*(X+Xn−Xa)]/X (3),
where T indicates one sub-frame period and X indicates the total number of lines (total number of scanning lines) of the CF-less liquid crystal panel 50.
Whether calculation is performed using one of expressions (1) to (3) above is determined by a magnitude relation between a display start line Xa and a non-display start line Xn. Specifically, when Xa<Xn, expression (1) is used. When Xa=Xn, expression (2) is used. When Xa Xn, expression (3) is used. A light source light-up time Tb which is a period in which the light-emitting elements light up can be changed between the maximum light source light-up time Tbm and 0. In order to obtain higher luminance, the light source light-up time Tb is preferably set to a value closer to the maximum light source light-up time Tbm. The light source data LD output by the light source data generation unit 143 includes the light source light-up time Tb. The light source data LD may include the maximum light source light-up time Tbm instead of the light source light-up time Tb. The light source data generation unit 143 supplies the light source light-up time data Dtb indicating the light source light-up time Tb to the timing processing unit 144.
Next, an operation of the timing processing unit 144 in the embodiment will be further described. The timing processing unit 144 obtains a light-up driving adjustment time Td which is a time for determining how much quickly or how much lately the light-emitting element of each color lights up from the scanning driving start time of the CF-less liquid crystal display element 51 by equation (4) below by using at least the display start line designation data Dal and the light source light-up time data Dtb. In other words, the light-up driving adjustment time Td is a time for adjusting the light-up start time of the light-emitting element of each color.
Td=T−Tb+(T*Xa/X) (4)
The timing processing unit 144 generates and outputs the driving timing control signal DT based on the light-up driving adjustment time Td obtained by expression (4). The start time of the scanning driving of the CF-less liquid crystal display elements 51 may be adjusted instead of adjusting the light-up start time of the light-emitting element of each color. Further, both of the light-up start time of the light-emitting element of each color and the start time of the scanning driving of the CF-less liquid crystal display element 51 may be adjusted. For the maximum light source light-up time Tbm and the light-up driving adjustment time Td indicated in expressions (1) to (4) above, a case in which the maximum luminance is displayed in a state of no color irregularity is assumed. However, when the color irregularity is allowed slightly, each of the maximum light source light-up time Tbm and the light-up driving adjustment time Td may be increased or decreased by an allowable amount. In the embodiment, the driving timing control signal DT corresponds to a light source driving timing control signal.
By lighting up the light-emitting elements of the respective colors of the first PDLC light source unit 70a and/or the backlight unit 80 in order in synchronization with the driving of the CF-less liquid crystal panel 50 under the above-described setting, it is possible to form a display area in which an image with no color irregularity is displayed at a desired position on the screen.
As shown Section B of
The scanning driving starts from a start time of each of first to third sub-frame periods. For the first sub-frame period, the transmission data is supplied as the red data to the second to fifth lines through the scanning driving and the transmission data is also supplied as the red data to the zeroth and first lines and the sixth and seventh lines. For the second sub-frame period, the shielding data is supplied as the green data to the second to fifth lines and the transmission data is supplied as the green data to the zeroth and first lines and the sixth and seventh lines. For the third sub-frame period, the shielding data is supplied as the blue data to the second to fifth lines and the transmission data is supplied as the blue data to the zeroth and first lines and the sixth and seventh lines.
For each of the first to third sub-frame periods, the light-emitting elements of the corresponding color light up at a time delayed by the light-up driving adjustment time Td than the scanning driving start time of the corresponding color data and light off after the light source light-up time Tb has passed. Therefore, the red light-emitting elements 71r (82r) light up for the second half of the first sub-frame period to the first half of the second sub-frame period. The green light-emitting elements 71g (82g) light up for the second half of the second sub-frame period to the first half of the third sub-frame period. The blue light-emitting elements 71b (82b) light up for the second half of the third sub-frame period to the first half of the first sub-frame period of the subsequent frame period.
The red light is transmitted through the second to fifth lines to which the transmission data is supplied as the red data and is transmitted through the zeroth and first lines and the sixth and seventh lines to which the transmission data is supplied as the red data. However, the green light and the blue light are shielded so that a transmission amount is the minimum in the second to fifth lines and are transmitted through the zeroth and first lines and the sixth and seventh lines at the maximum. As a result, since only the red line is transmitted in the second to fifth lines, an image according to the red data is displayed. On the other hand, in the zeroth and first lines and the sixth and seventh lines, the light of each color is transmitted by the same amount of light, i.e., for the same time. Thus, the zeroth and first lines and the sixth and seventh lines become the non-display area through which the background color is transmitted at the maximum. In this way, the display area in which the red image is displayed is formed in the middle of the screen and the non-display areas in the state in which the background color is transmitted at the maximum are formed with the display area interposed between the upper and lower sides. When the number of pixels of the PDLC panel 60 is set to be one and the entire PDLC panel 60 is in the diffusion state at the time of the image display, white display is realized in the non-display areas.
In the embodiment, the light source light-up time and the driving timing control signal DT are controlled in correspondence to a period in which the color data necessary to display an image of a desired color is supplied to the display area. Therefore, the display area in which the image of the desired color and occurrence of the color irregularity is suppressed can be set at a desired position of the CF-less liquid crystal panel 50.
In the embodiment, the color data supplied to the non-display areas for each sub-frame period becomes the same data for each pixel of the non-display area. Therefore, the non-display area becomes an area in which occurrence of the color irregularity is suppressed. When the number of pixels of the PDLC panel 60 is set to be plural, for example, a background can be displayed in the non-display area.
Not only the configuration of the foregoing first embodiment but also the configuration of the first modification example of the foregoing first embodiment may be adopted as the configuration of the signal processing circuit 10 according to the embodiment. For the disposition of the CF-less liquid crystal panel 50 and the light radiation unit 90 in the embodiment, any of the foregoing first to third embodiments and the modification examples thereof may be adopted. In the embodiment, the frame interpolation process of the second modification example of the foregoing first embodiment may be performed.
The scanning driving starts from the start time of each of the first to third sub-frame periods. For the first sub-frame period, the transmission data is supplied as the red data to the second to fifth lines and the sixth and seventh lines through the scanning driving. For the second sub-frame period, the transmission data which is the red data to be supplied to the zeroth and first lines is supplied by delaying the transmission data by one sub-frame period. For the second sub-frame period, the transmission data is supplied as green data to the second to fifth lines and the shielding data is supplied as the green data to the sixth and seventh lines. For the third sub-frame period, the shielding data which is the green data to be supplied to the zeroth and first lines is supplied by delaying the shielding data by one sub-frame period. For the third sub-frame period, the transmission data is supplied as the blue data to the second to fifth lines and the shielding data is supplied as the blue data to the sixth and seventh lines. The shielding data which is the blue data to be supplied to the zeroth and first lines is supplied for the first sub-frame period of the subsequent frame period.
For each of the first to third sub-frame periods, the light-emitting elements of the corresponding color light up at a time delayed by the light-up driving adjustment time Td than the scanning driving start time of the corresponding color data and light off after the light source light-up time Tb has passed. Therefore, the red light-emitting elements 71r (82r) light up at a time delayed by the light-up driving adjustment time Td from the start time of the first sub-frame period. The green light-emitting elements 71g (82g) light up at a time delayed by the light-up driving adjustment time Td from the start time of the second sub-frame period. The blue light-emitting elements 71b (82b) light up at a time delayed by the light-up driving adjustment time Td from the start time of the third sub-frame period.
The red light is transmitted through the zeroth and first lines and the sixth and seventh lines to which the transmission data is supplied as the red data and is transmitted through the second to fifth lines to which the transmission data is supplied as the red data. However, the green light and the blue light are shielded so that a transmission amount is the minimum in the zeroth and first lines and the sixth and seventh lines and are transmitted through the second to fifth lines at the maximum. As a result, since only the red light is transmitted in the zeroth and first lines and the sixth and seventh lines, an image according to the red data is displayed. On the other hand, in the second to fifth lines, the light of each color is transmitted by the same amount of light, i.e., for the same time. Thus, the second to fifth lines become the non-display area through which the background color is transmitted at the maximum. In this way, the non-display area in the state in which the background color is transmitted at the maximum are formed in the middle of the screen and the display areas in which the red image is displayed are formed with the non-display area interposed between the upper and lower sides.
The scanning driving starts from the start time of each of the first to third sub-frame periods. For the first sub-frame period, the transmission data is supplied as the red data to the zeroth to fifth lines and the sixth and seventh lines through the scanning driving. For the second sub-frame period, the shielding data is supplied as the green data to the zeroth to fifth lines and the transmission data is supplied as the green data to the sixth and seventh lines. For the third sub-frame period, the shielding data is supplied as the blue data to the zeroth to fifth lines and the transmission data is supplied as the blue data to the sixth and seventh lines.
For each of the first to third sub-frame periods, the light-emitting elements of the corresponding color light up at a time delayed by the light-up driving adjustment time Td than the scanning driving start time of the corresponding color data and light off after the light source light-up time Tb has passed. Therefore, the red light-emitting elements 71r (82r) light up from the second half of the first sub-frame period to the end time thereof. The green light-emitting elements 71g (82g) light up from the second half of the second sub-frame period to the end time thereof. The blue light-emitting elements 71b (82b) light up from the second half of the third sub-frame period to the end time thereof.
The red light is transmitted through the zeroth to fifth lines to which the transmission data is supplied as the red data and is transmitted through the sixth and seventh lines to which the transmission data is supplied as the red data. However, the green light and the blue light are shielded so that a transmission amount is the minimum in the zeroth to fifth lines and are transmitted through the sixth and seventh lines at the maximum. As a result, since only the red line is transmitted in the zeroth to fifth lines, an image according to the red data is displayed. On the other hand, in the sixth and seventh lines, the light of each color is transmitted by the same amount of light, i.e., for the same time. Thus, the sixth and seventh lines become the non-display areas through which the background color is transmitted at the maximum. In this way, the display area in which the red image is displayed is formed in the upper portion of the screen and the non-display area in the state in which the background color is transmitted at the maximum is formed in the lower portion of the screen.
The scanning driving starts from the start time of each of the first to third sub-frame periods. For the first sub-frame period, the transmission data is supplied as the red data to the zeroth to fifth lines and the sixth and seventh lines through the scanning driving. For the second sub-frame period, the transmission data is supplied as the green data to the zeroth to fifth lines and the shielding data is supplied as the green data to the sixth and seventh lines. For the third sub-frame period, the transmission data is supplied as the blue data to the zeroth to fifth lines and the shielding data is supplied as the blue data to the sixth and seventh lines.
For each of the first to third sub-frame periods, the light-emitting elements of the corresponding color light up at a time delayed by the light-up driving adjustment time Td than the scanning driving start time of the corresponding color data and light off after the light source light-up time Tb has passed. Therefore, the red light-emitting elements 71r (82r) light up from the start time of the second sub-frame period and light off before the end time thereof. The green light-emitting elements 71g (82g) light up from the start time of the third sub-frame period and light off before the end time thereof. The blue light-emitting elements 71b (82b) light up from the start time of the first sub-frame period of the subsequent frame period and light off before the end time thereof.
The red light is transmitted through the zeroth to fifth lines to which the transmission data is supplied as the red data and is transmitted through the sixth and seventh lines to which the transmission data is supplied as the red data. However, the green light and the blue light are shielded so that a transmission amount is the minimum in the sixth and seventh lines and are transmitted through the zeroth to fifth lines at the maximum. As a result, since only the red light is transmitted in the sixth and seventh lines, an image according to the red data is displayed. On the other hand, in the zeroth to fifth lines, the light of each color is transmitted by the same amount of light, i.e., for the same time. Thus, the zeroth to fifth lines become the non-display areas through which the background color is transmitted at the maximum. In this way, the non-display area in the state in which the background color is transmitted at the maximum is formed in the upper portion of the screen and the display area in which the red image is displayed is formed in the lower portion of the screen.
The invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the invention without departing from the gist of the invention. For example, any of other display apparatuses capable of switching transmission display and shielding display may be used instead of the CF-less liquid crystal panel 50. Examples of the other display apparatuses capable of switching transmission display and shielding display include a display apparatus using an electrowetting principle, a display apparatus using an electrochromic compound, a display apparatus using electrophoretic bodies, a display apparatus using a digital micromirror device (DMD), and a display apparatus using a microshutter. In the other display apparatuses capable of switching transmission display and shielding display other than the CF-less liquid crystal panel 50, the “shielding display” includes a case in which light is diffused only on the side of a light source (the side of a light guide plate when the light guide plate is used).
Any of other display apparatuses capable of switching transmission display and diffusion display may be used instead of the PDLC panel 60. Examples of the other display apparatuses capable of switching transmission display and diffusion display include a display apparatus using an electrowetting principle, a display apparatus using an electrochromic compound, a display apparatus using electrophoretic bodies, a display apparatus using a digital micromirror device (DMD), and a display apparatus using a microshutter. In the other display apparatuses capable of switching transmission display and diffusion display other than the PDLC panel 60, the “diffusion display” includes a case in which light is diffused only on a side at which radiated light (also including background light) arrives. A display apparatus capable of switching transmission display and diffusion display of light with color (including a case in which light is diffused on a side at which radiated light (also including a background light, as described above) arrives) may be used instead of the PDLC panel 60. In this case, the light source unit 100 may not be necessarily be configured to emit light of a plurality of colors and may be configured to emit white light. Even in this case, the entire light radiation unit 90 can radiate the light of the plurality of colors to the CF-less liquid crystal panel 50.
In the foregoing first embodiment and the first modification example thereof, the CF-less liquid crystal timing designation signal CT, the PDLC timing designation signal PT, and the light source timing designation signal LT generated by the timing designation control unit 15 based on the driving timing control signal DT has been supplied to each of the CF-less liquid crystal display element signal control unit 16, the PDLC display element signal control unit 17, and the light source signal control unit 18 in the above description, but the invention is not limited thereto. The timing designation control unit 15 may not be provided and the image control unit 14 may be configured to supply the driving timing control signal DT to the CF-less liquid crystal display element signal control unit 16, the PDLC display element signal control unit 17, and the light source signal control unit 18.
In the first and third embodiments and each modification example thereof, a mechanism (for example, a box for which each panel or the like is disposed on its front and rear surfaces and in which the exhibition object 110 is disposed inside) diffusing the light-source light may be adopted to improve the use efficiency of the light-source light of the first and second PDLC light source units 70a and 70b.
In the foregoing second and third embodiments, the area active-driving has been performed using the light guide plate formed by the blocks in the above description, but the invention is not limited thereto. The area active-driving may be performed using a normal light guide plate not configured by blocks as in
In the foregoing third embodiment and each modification example thereof, as in the third modification example of the foregoing first embodiment, the first PDLC light source unit 70a may radiate the light-source light to the front surface of the PDLC panel 60. In the foregoing third embodiment and each modification example thereof, as in the fourth modification example of the foregoing first embodiment, the light-source light may be radiated to the front and rear surfaces of the PDLC panel 60 using the first and second PDLC light source units 70a and 70b. Thus, it is possible to further improve the luminance of the display image.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-163601 | Jul 2012 | JP | national |
| 2012-222923 | Oct 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/069356 | 7/17/2013 | WO | 00 |
