Patent Application
20130027400
This application claims priority to and the benefit of Korean Patent Application No. 10-2011-0074658 filed in the Korean Intellectual Property Office on Jul. 27, 2011, the entire contents of which are incorporated by reference herein.
1. Field of the Invention
A display device and a method of driving the same are provided.
2. Description of the Related Art
In general, in a 3D image display technology, stereoscopic perception of an object is represented by using a binocular parallax as the largest factor for recognizing the stereoscopic perception in a near distance. When different 2D images are reflected in a left eye and a right eye, respectively, and the image reflected in the left eye (hereinafter, referred to as a “left eye image”) and the image reflected in the right eye (hereinafter, referred to as a “right eye image”) are transferred to the brain, the left eye image and the right eye image are combined in the brain to be recognized as the 3D image having a perceived depth.
A three dimensional image display device uses the binocular parallax and includes a stereoscopic method using glasses such as shutter glasses, polarized glasses, or the like and an autostereoscopic method in which a lenticular lens and a parallax barrier, or the like are disposed in a display device without using glasses.
In the shutter glasses type, the left eye image and the right eye image are divided to be alternately displayed in the three dimensional image display device and a left eye shutter and a right eye shutter of the shutter glasses are selectively opened and closed, thereby expressing the 3D image.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
An exemplary embodiment of the inventive concept provides a display device including a display panel configured to display an original image at a first time and a converted image based on the original image at a second time (e.g., the next instant) The average value of the luminance of a first pixel of the original image (at the first time) and the luminance of the first pixel of the converted image (at the second time) is substantially the same as the average value of the luminance of a second pixel of the original image (at the first time) and the luminance of the second pixel of the converted image (at the second time).
Luminances of all the pixels in a merged image viewed when the eyes and/or brain of the viewer merges the original image and the converted image may be substantially the same as each other.
The display device may generate a shutter control signal controlling a left eye shutter and a right eye shutter. The shutter control signal may open at least one of the left eye shutter and the right eye shutter at the first time while the original image is displayed. The shutter control signal may close both the left eye shutter and the right eye shutter at the second time when the converted image is displayed.
The display device may be synchronized to a shutter member including the left eye shutter and the right eye shutter based on security information including an identification code or a password.
The gray values of the converted image may be determined based on transformation and inverse transformation of tristimulus values for the gray value.
The gray values of the converted image may be determined based on normalization, linearization, de-linearization, and inverse normalization.
The converted image may be displayed based on a security control signal activating a security mode.
When the security control signal is 1, the gray values of the converted image may be determined based on a security mode look-up table and when the security control signal is 0, the gray values of the original image may be modified based on a normal mode look-up table.
The display device may further include a frame memory storing the original image. When the security control signal is 1, the original image may be converted into the converted image frame by frame by using the frame memory and when the security control signal is 0, the gray values of the original image may be modified based on a normal mode look-up table.
The display device may further include a graphic processor converting the original image into the converted image. When the security control signal is 1, the converted image may be generated by the graphic processor and when the security control signal is 0, the original image may be modified by the graphic processor.
The converted image may be processed into a mosaic by adding a random noise block by a block.
The original image may be horizontally or vertically interlaced by using black or white and the converted image may be horizontally or vertically interlaced by using white or black.
The gray values of the original image may be clipped into a predetermined clipped gray range.
Another exemplary embodiment of the inventive concept provides a driving method of a display device, including displaying an original image at a first time and a converted image based on the original image at a second time The average value of luminance of a first pixel of the original image and the luminance of the first pixel of the converted image is substantially the same as the average value of luminance of a second pixel of the original image and the luminance of the second pixel of the converted image.
The driving method may further include processing the converted image in mosaic by adding a random noise to the converted image block by block.
The driving method may further include interlacing the original image horizontally or vertically by using black or white and interlacing the converted image horizontally or vertically by using white or black.
The driving method may further include clipping the original image into a predetermined clipped gray range.
The inventive concept will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the inventive concept are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the inventive concept. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. Further, a detailed description of the related art that has been widely known is omitted.
In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” or “connected” to another element, it may be directly on or connected the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.
A display panel 100 in the display device may be implemented as a liquid crystal display (LCD), an organic light emitting diode display, a plasma display device, an electrophoretic display, an SED, or the like. Hereinafter, it is assumed that the display panel 100 is the liquid crystal display.
The LCD display panel 100 includes an upper substrate, a lower substrate, and a liquid crystal layer between the upper substrate and the lower substrate. The alignment direction of the liquid crystal molecules in the liquid crystal layer is changed by an electric field generated between two electrodes. The amount of light transmitted through the liquid crystal layer depends upon the alignment direction of the liquid crystal molecules such that the display panel 100 displays images by controlling the transmission amount of light.
The lower substrate includes gate lines GL1 to GLn, data lines DL1 to DLm, a plurality of pixels disposed at the intersections of the gate lines and data lines. A pixel includes a liquid crystal capacitor, a pixel electrode of the liquid crystal capacitor, and a thin film transistor 105 connected thereto. The thin film transistor 105 controls voltages applied to the pixel electrode based on a signal applied to the gate lines GL1 to GLn and the data lines DL1 to DLm. The pixel electrode may be a transflective pixel electrode having a transmissive region and a reflective region. A pixel may further include a storage capacitance capacitor 107 and the storage capacitance capacitor 107 maintains the voltage applied to the pixel electrode for a predetermined time. For example, one pixel 103 may include the thin film transistor 105, the storage capacitance capacitor 107, and a liquid crystal capacitance capacitor 109.
The upper substrate facing the lower substrate may include a black matrix, a color filter, and a common electrode. In alternative implementations, at least one of the black matrix, the color filter, and the common electrode formed in the upper substrate may be disposed on the lower substrate. When both the common electrode and the pixel electrode are disposed on the lower substrate, at least one of the common electrode and the pixel electrode may be formed in linear electrode form.
The liquid crystal layer may include a twisted nematic (TN) mode liquid crystal, a vertically aligned (VA) mode liquid crystal, and an electrically controlled birefringence (ECB) mode liquid crystal, or the like.
A polarizer is attached to at least one of the outer surface of the upper substrate and the outer surface of the lower substrate. Further, a compensation film is further formed between the substrate and the polarizer.
A backlight unit 200 includes at least one light source and an example of the light source is a fluorescent lamp such as a cold cathode fluorescent lamp (CCFL), an LED, or the like. In addition, the backlight unit 200 may further include a reflector, a light guide, a luminance improving film, and the like.
Referring to
The stereo controller 400 transmits a 3D sync signal 3D_sync to the shutter member 300 and to the frame conversion controller 330. The shutter member 300 may be electrically connected with the stereo controller 400. The shutter member 300 may receive the 3D sync signal 3D_sync by a wireless infrared communication. The shutter member 300 may be operated in response to the 3D sync signal 3D_sync or a modified 3D sync signal. The 3D sync signal 3D_sync may include all signals capable of opening or closing a left eye shutter or a right eye shutter. The frame conversion controller 330 transmits control signals PCS and BIC to the image signal processor 160 and the data driver.
The stereo controller 400 transmits a display data DATA, a 3D enable signal 3D_En, and control signals CONT1 to the image signal processor 160. The image signal processor 160 transmits various kinds of display data DATA′ and various kinds of control signals CONT2, CONT3, and CONT4 to the display panel 100 through the gate driver 120, the data driver 140, and the gamma voltage generator 190 in order to display images on the display panel 100. The display data DATA in the display device may include left eye image data, and right eye image data.
The stereo controller 400, the image signal processor 160, or the luminance controller 210 may perform a spatial filter and a temporal filter.
Referring to
The shutters of the shutter glasses 30 may be implemented by a technology such as a liquid crystal display, an organic light emitting diode display, an electrophoretic display, and the like, but is not particularly limited thereto. For example, the shutter may include two transparent conductive layers and a liquid crystal layer disposed therebetween. A polarization film may be disposed on the surface of the conductive layer. The molecules of the liquid crystal material are rotated by the voltage applied between the two transparent conductive layers and the shutter may be OPEN or CLOSED by the rotation of the liquid crystal material.
For example, while left eye images 101 and 102 are displayed on the display panel 100, the left eye shutter 31 of the shutter glasses 30 is OPEN so as to transmit the light, and the right eye shutter 32 is CLOSED so as to block the light. At a different time, while the right eye images 101′ and 102′ are displayed on the display panel 100, the right eye shutter 32′ of the shutter glasses 30 is OPEN so as to transmit the light, and the left eye shutter 31′ is CLOSED so as to block the light. Accordingly, the left eye image is viewed by only the left eye for a predetermined time and thereafter, the right eye image is viewed by only the right eye for a predetermined time, such that 3D images having depth perception are recognized by a difference between the left eye image and the right eye image.
The exemplary image viewed by the left eye includes a rectangle 101 and a triangle 102 spaced apart from each other by a distance of a. The image viewed by the right eye includes a rectangle 101′ and a triangle 102′ spaced apart from each other by a distance of β . Herein, α and β have different values and as a result, the perceived distance between the triangle to the rectangle may be different for each eye and the depth of the triangle disposed behind the rectangle may be perceived. By controlling the distances α and β between the triangle and the rectangle, the perceived distance that the triangle and the rectangle are separated from each other (and depth perception) may be controlled.
An image having a predetermined gray value may be displayed as the left eye images 101 and 102 and the right eye images 101′ and 102′. For example, a black image, a white image, a gray image, or the like may be displayed. When the image having a predetermined gray value is inserted on the overall screen of the display device, a crosstalk effect between the left eye images 101 and 102 and the right eye images 101′ and 102′ may be reduced.
Referring to
For example, the display panel 100 may display the left eye images 101 and 102 as described below. The gate-on voltage is applied to the gate line and the data voltage is applied to the pixel electrode through the thin film transistor connected to the corresponding gate line. The applied data voltage is a data voltage (hereinafter, referred to as “left eye data voltage”) for expressing the left eye images 101 and 102 and the applied left eye data voltage is maintained for a predetermined time after the gate-off voltage is applied to the gate line by the storage capacitance capacitor. Similarly, data voltage (hereinafter, referred to as “right eye data voltage”) for expressing the right eye images 101′ and 102′ is applied to the pixel electrode and the applied right eye data voltage may be maintained for a predetermined time by the storage capacitance capacitor.
When images having two colors in a complementary color relationship are displayed on the display device sequentially for a very short time, it may be difficult for a user without the shutter member to recognize the images having two colors as an image having a single color. The complementary color relationship means that two colors overlap each other to make white. For example, when one color is data 8bits and the two colors are in the complementary color relationship if the sum of gray values of two colors is 255. For example, a color having a gray value of 0 and a color having a gray value of 255 are in the complementary color relationship. And, for another example, a color having a gray value of 192 and a color having a gray value of 63 are in the complementary color relationship.
When an original image is inputted and the original image and a converted image having a complementary color relationship with the original image are alternately displayed on the display device for a very short time, it may be difficult for a user without the shutter member to recognize the original image and the converted image as an image having a single color.
For example, referring to
Accordingly, the gray values of the converted image are determined so that the luminance averages in the original image and the converted image are substantially the same as each other, such that the original image and the converted image may be recognized as one image without appearing as a blurred object to the user without the shutter member and a security function and a privacy protection function of the display device may be improved. The original image and the converted image which are viewed by a user without the shutter member are called a merged image. Luminances of all pixels in the merged image may be all the same as each other. The original image may be a password input screen requiring the security such as a safe and the like. The merged image is a different image from the original image and an image in which it is difficult for the user without the shutter member to guess the original image from. For example, the merged image may be an image with a geometric pattern, or text.
For example, referring to
The gray values of the converted image may be determined by the image conversion process of
If the gray values of the original image are inputted, data of the original image is normalized by the following Equation 1.
In the Equation 1, RN is a gray value of the original image.
The normalized image is linearized by the following Equation 2.
In the Equation 2, R′ is data of the normalized image.
The linearized image is transformed by the following Equation 3 to calculate the tristimulus values.
In the Equation 3, R, G, and B are data of the linearized image and a color temperature is 6500 K.
The tristimulus values of the original image are transformed by the following Equation 4 to calculate the tristimulus values of the converted image.
In the Equation 4, X0, Y0, and Z0 are target tristiumlus values and tristiumlus values for a single-color image recognized by the user without the shutter member.
The tristiumlus values of the converted image are calculated as gray values of the converted image by inverse transformation of the following Equation 5, de-linearization of the following Equation 6, and inverse normalization of the following Equation 7.
By measuring luminance corresponding to the gray values of the converted image through an experiment, the gray values of the converted image corresponding to the gray values of the original image may be determined so that the luminance averages in the original image and the converted image are substantially the same as each other. For example, a look-up table LUT like the following Table 1 may be used.
Look-up tables for red, green and blue may be the same as each other. The gray values which are not included in the look-up table may be calculated by a method such as an interpolation and the like. For example, when the gray values of R of the original image is 161, the gray value of G thereof is 156, and the gray value of B thereof is 75, the gray value of R of the converted image may be 201, the gray value of G thereof may be 208, and the gray value of B thereof may be 239. In this case, the original image and the converted image displayed in turn by a period of 1/120 second are recognized as the single-color image by the user without the shutter member, but only the original image is recognized by the user with the shutter member because luminances of the pixels in the merged image are the same as each other.
In another example the converted image is in the complementary color relationship with the original image, the gray value of R of the converted image is 94, the gray value of G thereof is 99, and the gray value of B thereof is 180. In this case, it is difficult for the user without the shutter member to recognize the original image and the converted image which are displayed by the unit of 1/120 second in turn as a single-color image because luminances of the pixels in the merged image are not the same as each other.
Referring to
Referring to
Referring to
Referring to
By adding a random noise to the converted image block by block, the converted image is processed as a mosaic and the user without the shutter member views the merged image of the converted image processed as a mosaic and the original image and it is more difficult for the user without the shutter member to guess the original image as compared with the converted image which is not processed as a mosaic. The converted image may be an image which is in the complementary color relationship with the original image and an image in which luminances of the pixels are substantially the same as each other in the merged image. For example, when the size of the block is 16×16, the random noise of a first pixel block is 4, and the random noise of a second pixel block is −7, 4 may be added to the gray values of the 256 pixels of the first pixel block in the converted image, respectively and −7 may be added to the gray values of the 256 pixels of the second pixel block in the converted image, respectively. The size and the sign of the random noise may be randomly determined.
For example, referring to
By horizontally or vertically interlacing the original image and the converted image by using black and white, it is more difficult for the user without the shutter member to guess the original image as compared with the case where the original image and the converted image are not interlaced. The converted image may be an image which is in the complementary color relationship with the original image and an image in which luminances of the pixels in the merged image are substantially the same as each other. The converted image may be processed as a mosaic by using the random noise. For example, referring to
By clipping the original image into a predetermined gray range, (remapping the gray values of the original image into a predetermined clipped gray range) it is more difficult for the user without the shutter member to guess the original image as compared with the original image which is not clipped. Since a phenomenon in which the boundary of the object is shown in the merged image recognized by the user without the shutter member largely occurs in a low gray near to black and a high gray near to white, neither a low gray nor a high gray is displayed on the clipped original image. For example, when the gray is 0 to 255, a predetermined clipped gray range may be 100 to 192.
Referring to
Referring to
An image stored in the frame memory 310 is converted by the security mode look-up table 640 and the converted image may be an image in which luminances of the pixels in the merged image are substantially the same as each other. An image displayed from the security mode look-up table 640 is inputted to a random noise generator 645 to be processed into a mosaic by using the random noise. An image output from the random noise generator 645 is inputted to an input terminal IN2 of the multiplexer 664 through the frame clock delay (for example at 60 Hz). The random noise generator 645 may be omitted.
The multiplexer 664 sequentially outputs two images inputted to its two input terminals IN1 and IN2 controlled by timing unit such as the even/odd counter 662. The even/odd frame decider 661, the even/odd counter 662, the gray insertion unit 663, and the multiplexer 664 may be omitted and in that case, the non-interlaced original image and the converted image are displayed.
The image output from the multiplexer 664 is modified by a dynamic capacitance compensation (DCC) 671, a comparing unit 672, and the frame memory 310. The DCC 671 corrects an image of a current frame based on images stored in the frame memory 310 such as an image of a previous frame and an image of a next frame. For example, the DCC 671 may perform the overshoot driving or the undershoot driving. The image displayed from the multiplexer 664 is compressed before being inputted to the DCC 671 to be stored in the frame memory 310 as data of the current frame and the stored image data is converted by the security mode look-up table 640 and the random noise generator 645.
According to exemplary embodiments of the inventive concept, a security function and a privacy protection function of a display device may be implemented.
While this inventive concept has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the inventive concept is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2011-0074658 | Jul 2011 | KR | national |
