Patent Application
20090109135
The present application claims priority from Japanese application JP 2007-281271 filed on Oct. 30, 2007, the content of which is hereby incorporated by reference into this application.
1. Field of the Invention
The present invention relates to a display apparatus, and more specifically, to a display apparatus which realizes a reduction of moving image blurring that occurs when a moving image is displayed by employing a simple circuit, while a display quality of a still image is not deteriorated.
2. Description of the Related Art
Display apparatuses (hereinafter, also referred to as “displays”) are mainly classified to impulse response type displays and hold response type displays when those display apparatuses are classified in view of, especially, displaying of moving images. The above-mentioned impulse response display is such a type of display in which a luminance response is lowered immediately after scanning, which is similar to afterglow characteristics represented in CRTs. In contrast to the impulse response type display, the above-mentioned hold response type display is such a type of display in which luminance produced based upon display data is continuously held until the next scanning, which is similar to display characteristics of liquid crystal displays (LCDs).
As features of the hold response type display, when a still image is displayed, a superior display quality without flickering can be achieved. However, when a moving image is displayed, so-called “moving image blurring” may occur, namely, a circumferential portion of a moving object is blurred, and hence a display quality of the moving image is considerably deteriorated. The moving image blurring is caused by a so-called “retina afterimage”. That is, when a line of sight (LOS) of a viewer is moved in connection with movement of an object, the viewer interpolates display images before and after the movement with respect to a displayed image with the held luminance. As a result, even if a response speed of a hold response type display is improved in higher degrees, it is known that the moving image blurring cannot be completely solved. In order to solve this problem, a method described below is known as an effective solving method. That is, a displayed image is updated at shorter frequency, or a black screen is inserted so as to once cancel a retina afterimage, whereby a hold response type display is approximated to an impulse response type display.
On the other hand, a television receiver has been typically proposed as a display apparatus which is required to display moving images. Scanning frequencies of the television receiver have been standardized. For example, in an NTSC signal, an interlaced scanning frequency of 60 Hz is selected, whereas in a PAL signal, a sequential scanning frequency of 50 Hz is selected. When a frame frequency of a displayed image is selected to be 60 Hz to 50 Hz based upon this frequency, since the frequency is not so high, the moving image blurring may occur.
As means for improving the above-mentioned moving image blurring, JP 2005-6275 A discloses a technology for updating images at the above-mentioned shorter frequency. JP 2005-6275 A discloses a method of increasing a scanning frequency, and increasing updating speed of an image by producing display data of an interpolated frame based upon the display data between frames (hereinafter, abbreviated as “interpolated frame producing method”). Further, as a technical idea for inserting a black frame, JP 2003-280599 A discloses a technology of inserting black display data between the display data.
However, in the method disclosed in JP 2005-6275 A, display data which is not originally present is produced. If more precise data is to be produced, then the circuit scale is increased. Conversely, if the circuit scale is reduced, then a mistake in producing the interpolated frame may occur. Thus, there may be a risk that the display quality is considerably lowered.
On the other hand, in the method disclosed in JP 2003-280599 A, since there is a luminance difference between the black frame and the video frame, if the frequency is low, then the flickering maybe observed. As a result, this conventional method is difficult to be applied to television receivers operated in the PAL system.
As another solving method, JP 2006-259689 A discloses a method for reducing the moving image blurring by employing a simple circuit. That is, JP 2006-259689 A describes such an image display method in which, while a frame frequency of input image signal is multiplied by an integer, a new image signal is produced in the increased frames, and then, an image is displayed by employing the input image signal and the produced image signal. The above-mentioned conventional image display method includes: linear-summing continuous input image signals so as to produce a primary intermediate image signal; filtering the primary intermediate image signal by a low-pass filter so as to produce a secondary intermediate image signal; extracting only a secondary intermediate image signal which corresponds to a varied region of the continuous input image signals so as to produce a tertiary intermediate image signal; extracting only an image signal located in a non-varied region of the continuous input image signals so as to produce a common image signal; and synthesizing the tertiary intermediate image signal with the common image signal so as to produce a produced image signal.
The conventional image display method disclosed in JP 2006-259689 A may be realized by employing the simpler circuit, as compared with the conventional interpolated frame producing method disclosed in JP 2005-6275 A, but this image display method has the following problems.
As a first problem, it is assumed that video data of increased frames is determined in accordance with an averaged value between frames. However, the produced video data is not always the optimum video data, depending upon the cut-off frequency of the low-pass filter. In addition, generally speaking, response times of a display apparatus employing liquid display elements are selected to be milliseconds, and the response times vary according to tone level. As a consequence, there may be a risk that stable reducing effects may not be achieved with respect to the moving image blurring.
As a second problem, the tertiary intermediate image signal is synthesized with the common image signal. However, the synthesized image portion does not always have continuities, but the synthesized image may contain the high frequency component. When this high frequency component is moved, this moved image portion may be visually recognized as a blurred image portion. As a consequence, there may be a risk that the satisfactory reducing effects cannot be achieved with respect to the moving image blurring.
As a third problem, the display apparatus alternately displays the produced image signal and the input image signal. In this case, with respect to the produced image, the averaging process is performed along the temporal direction, and the low-pass filtering process is performed along the spatial direction. However, since no data conversion is carried out with respect to the input image signal, there may be a risk that the satisfactory reducing effects cannot be achieved with respect to the moving image blurring.
The present invention has been made in view of the above-mentioned problems, and therefore has an object to provide a display apparatus capable of reducing moving image blurring with a higher effect by employing a simple circuit.
In order to clarify the inventive idea of the present invention, a time period during which display data for one screen is transferred from an external system is defined as one input frame period, whereas another time period during which display data for one screen of a matrix type display is rewritten is defined as one rendering frame period. In the case of JP 2006-259689 A described above, one input frame period is constituted by two rendering frame periods.
The display apparatus of the present invention includes a memory for storing display data for at least one input frame. The display data is read from the memory at a speed which is “n” times higher than an input frame frequency, while symbol “n” is an integer equal to or higher than 1, and then, display data for two frames are produced which are synchronized with each other. When n=1, display data of a current frame need not be read from the memory. Further, since display data of a preceding frame is utilized as comparison data in order to check a change, all bits contained in the display data of the preceding frame are not required. Note that one case of n=2 is exemplified in a first embodiment of the present invention, and another case of n=1 is exemplified in a second embodiment.
In the display apparatus of the present invention, both converting display data for two frames in such a manner that a change in display data of proximate pixels thereof along a temporal direction is emphasized based upon the above-mentioned change along the temporal direction, and converting the display data in such a manner that a change in the display data of the proximate pixels thereof along a spatial direction is emphasized based upon the above-mentioned change in the spatial direction are performed within one rendering frame period. Any of those two steps may be carried out first. The first embodiment exemplifies such an example that the emphasizing step along the temporal direction is carried out first, and the emphasizing step along the spatial direction is carried out next. A third embodiment exemplifies such an example that the emphasizing step along the spatial direction is carried out first, and the emphasizing step along the temporal direction is carried out next.
In a next (m−1) rendering frame period, converting the display data in such a manner that a change in the display data of the proximate pixels along the temporal direction is deemphasized based upon the change along the temporal direction, and converting the display data in such a manner that a change in the display data of the proximate pixels along the spatial direction is deemphasized based upon the change along the spatial direction are carried out within the above-mentioned (m−1) rendering frame period.
On the other hand, in such a case where display data is not changed between input frames, the input display data is utilized as data for rendering without being converted. A cycle period during which the same calculations are performed constitutes “m” rendering frame periods. Since moving image blurring occurs dominantly in one rendering frame period, it is preferable to set that the frequency thereof is selected to be 50 Hz through 60 Hz or higher, which correspond to the normal one rendering frame period. In the case where the cycle period becomes further long, there is a possibility that a difference between an emphasized frame and a deemphasized frame may be visually recognized as a judder. As a result, it is desirable that the repetition frequency is selected to be equal to or higher than 24 Hz, which has been employing in movies and the like, because, at this repetition frequency, the above-mentioned possibility that the difference is visually recognized as the judder (vibration of image) may be neglected in human vision.
When the above-mentioned inventive idea of the present invention is applied, since none of display data for a still image portion is converted, image qualities similar to those of the conventional method can be maintained. With respect to a moving image portion, contour portions of one rendering frame along the temporal direction and the spatial direction are visually recognized within one rendering frame among (m×n) rendering frames. As a result, the moving image blurring may be reduced, and hence the moving image can be displayed with higher image quality.
These and other features, objects and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings wherein:
A basic idea of a display apparatus according to the present invention is given as follows. That is, assuming now that a current frame is a frame “M”, a change in display data along a temporal direction is emphasized and deemphasized based upon input display data of a frame “M−1” (namely, the frame preceding the current frame “M”) and input display data of the current frame “M”, and further, a change in display data along a spatial direction is emphasized and deemphasized. Specifically, images displayed in pixels changed in their video contents between now and preceding input frame and vicinal pixels thereof are emphasized along both the temporal direction and the spatial direction within one rendering frame period and are deemphasized along both the temporal direction and the spatial direction within one preceding rendering frame period therewith. A total of the rendering frame periods falls within one input frame period.
Referring now to
It is also assumed that the above-mentioned control signals 104 to 107 are produced based upon the input control signal 102 in the control signal producing circuit 103. Further, reference numeral 108 denotes a frame doubler; 109, current frame display data; and 110, preceding frame display data. In the frame doubler 108, the input display data 101 is written based upon the memory control signal 106, and also, the input display data 101 is read two times at a double speed with respect to a time period (frame period) from a display region head of a certain screen of this input display data to a display region head of a subsequent screen thereof.
In this case, it is assumed that, with respect to one input frame period, a time period during which an image of the input frame is displayed based upon a first half of read data is referred to as “first half field”, whereas another time period during which an image of the input frame is displayed based upon a second half of read data is referred to as “second half field” hereinafter. Further, it is assumed that the current frame display data 109 and the proceeding frame display data 110 have a phase difference of one frame. Reference numeral 111 denotes a calculation parameter storing unit, and reference numeral 112 denotes a calculation parameter. In the calculation parameter storing unit 111, calculation parameters stored there into are read based upon the calculation control signal 107. Reference numeral 113 denotes a calculating circuit, and reference numeral 114 denotes time/space conversion display data. Reference numeral 115 denotes a column electrode driving circuit; 116, a column electrode drive signal; 117, a row electrode driving circuit; and 118, a row electrode drive signal. Reference numeral 119 denotes a matrix type display constituted by display elements along the row direction and the column direction.
In the temporal direction calculation parameter 205, it is assumed that a symbol “ODO(i, j)” denotes a temporal direction data calculation parameter in the first half field, and a symbol “ODE(i,j)” denotes a temporal direction data calculation parameter in the second half field. In the temporal direction conversion data 208, it is so indicated that a data portion “DTO(n)” is temporal direction conversion data in the first half field in the “n”th frame, and a data portion “DTE(n)” is temporal direction conversion data in the second half field in the “n”th frame.
In the spatial direction calculation parameter 209, it is so indicated that a symbol “CVO(d,i,j)” denotes a spatial direction calculation parameter in the first half field, and a symbol “CVE(d,i,j)” denotes a spatial direction calculation parameter in the second half field. In the time/space conversion display data 114, it is so indicated that a data portion “DSO(n)” is time/space conversion display data in the first half field in the “n”th frame, and a data portion “DSE(n)” is time/space conversion display data in the second half field in the “n”th frame.
Referring now to
The relationship among the input display data 101, the current frame display data 109, and the preceding frame display data 110 is given as illustrated in
Both the current frame display data 109 and the preceding frame display data 110, which have the above-mentioned timing, are transferred to the calculating circuit 113. The calculating circuit 113 has configuration as illustrated in
There are some cases where display data is not present, depending upon the values of “m” and “n”. In such a case, display data with respect to the existing display screen edge portion, namely, m=1 or “M”, otherwise n=1 or “N” may be applied. Similarly, the preceding frame display data 110 is processed by the frame analysis range deriving circuit 202, and hence display data constructed of 2×I rows 2×J columns: DP(m−I, n−J) to DP(m+I, n+J) is output by the preceding frame analysis range deriving circuit 202 with respect to the preceding frame display data “DP(m, n)” of the “m”th row and “n”th column. In this case, when I=1 and J=1 are given, a relationship between the display data (current frame) DN(m−I, n−J) to DN(m+I, n+J), and the display data (preceding frame) DP(m−I, n−J) to DP(m+I, n+J) is represented in
With respect to the current frame display data 109 and the preceding frame display data 110 produced in the above-mentioned manner, data conversion is performed by the temporal direction data converting circuit 206. An algorithm of the temporal direction data converting circuit 206 is defined by a flow chart of
As a result of the data comparison, when the current frame display data DN(m+i, n+j) is coincident with the preceding frame display data DP(m+i, n+j), in correspondence with the display data of the “m”th row and “n”th column, as time axis conversion data: DT(m+i, n+j) of a “+i”th row and “+j”th column from the display position thereof, the current frame display data: DN(m+i, n+j) of the relevant position is substituted, and a temporal direction data coincident flag: FLAG holds the logic level thereof. On the other hand, when the preceding frame display data DP(m+i, n+j) is not made coincident with the current frame display data DN(m+i, n+j), the temporal direction data coincident flag “FLAG” is set to a logic level “1”, and a data conversion is carried out by the temporal direction data converting circuit 206 in accordance with data amounts of both the current and preceding frame display data, and a value of the temporal direction calculation parameter 205. The temporal direction calculation parameter has different values, depending upon the first half field or the second half field.
For the sake of easier understanding, processings executed in the flow chart of
This expresses that the display data conversion is finally carried out with respect to the display data of the “m”th row and “n”th column, based upon the current frame display data of the “+i”th row and “+j”th column: DN(m+i, n+j) from the display position thereof, and the preceding frame display data: DP(m+i, n+j). More specifically, as an example of a case where i=0 and j=0, a table configuration indicated in
Further, although
As illustrated in
The above-mentioned operations are carried out with respect to a range defined by 2I×2J. As a result of the above-mentioned calculations, the temporal direction conversion data 208 constructed of the range defined by 2I×2J, and the temporal direction data coincident flag 207 are produced in order to produce display data of the “m”th row and “n”th column. As a result of the above-mentioned calculations, within the analysis range, if all pieces of display data are coincident with each other in both the preceding frame and the current frame, the temporal direction data coincident flag 207 becomes a logic level “0”, whereas if all pieces of display data are not coincident with each other in both the preceding frame and the current frame, the temporal direction data coincident flag 207 becomes a logic level “1”.
The temporal direction data coincident flag 207 and the temporal direction conversion data 208, which have been produced in accordance with the above-mentioned operations, are transferred to the spatial direction data converting circuit 210 so as to perform a data conversion based upon the spatial direction calculation parameter 209, thereby producing the temporal/spatial conversion display data 114.
The above-mentioned conversion algorithm is illustrated as a flow chart of
On the other hand, when the temporal direction data coincident flag 207 is the logic level “1”, a convolution operation is performed between a conversion parameter: CVO(DTO(m, n), i, j) made of a matrix structure (2×I rows 2×J columns) when the first half field is selected, and temporal direction data conversion data : DTO(m−i, n−j) of the first half field, made of the same matrix structure (2×I rows 2×J columns), thereby producing temporal/spatial conversion display data: DS(m, n). In this case, the conversion parameter CVO(DTO(m, n), i, j) corresponds to a value determined based upon temporal direction data conversion data DTO(m, n) of an analysis pixel, and a positional relationship “i” and “j” of this analysis pixel. More specifically, the conversion parameter CVO(DTO(m, n), i, j) constitutes a table as illustrated in
Similarly, when the second half field is selected, a convolution operation is carried out between a conversion parameter: CVE(DTE(m, n), i, j) and a temporal direction data conversion data DTE(m−i, n−j) of the second half field, thereby producing temporal/spatial conversion display data: DS(m, n). In this case, similar to the case of the first half field, the conversion parameter CVE(DTE(m, n), i, j) is constituted by such a table determined by “DTE(m, n)”, “i”, and “j”. More specifically, the conversion parameter CVE(DTE(m, n), i, j) is given as such a table illustrated in
The temporal/spatial conversion display data 114 produced in accordance with the above-mentioned operations is transferred to the matrix type display 119, and thus, the matrix type display 119 performs a data display operation based upon the above-mentioned temporal/spatial direction conversion display data “DS (m, n)” converted from the input display data “DN(m, n)” with respect to the display data of the “m”th row and “n”th column.
The above-mentioned data conversion is summarized as follows. As illustrated in
As a result of the above-mentioned operations, if there is no change in the display data of the proximate pixels between frames, the temporal/spatial direction conversion data 114 becomes equal to the input display data 101. As a consequence, when the still image is displayed, the display quality of the still image equivalent to the conventional display quality can be maintained. To the contrary, a case where video display data is changed between frames is illustrated in
The resultant influences on the displays are indicated in
In contrast to the above-mentioned region, in a region (c) illustrated in
It should be noted that although the range for calculating the temporal direction data coincident flag 207 has been set equal to the data conversion range for one pixel in the spatial direction data converting circuit 210 corresponding to the subsequent step in the first embodiment, the present invention is not limited to the above-mentioned calculation range. For instance, the present invention may alternatively employ a method for calculating the temporal direction data coincident flag 207 by only comparing the current frame display data 203 with the preceding frame display data 204 in the relevant pixel, or a range between those display data 203 and 204. In this alternative case, a range where the input display data 101 is different from the temporal/spatial conversion display data 114 becomes such a different data example as illustrated in
As previously described, according to the first embodiment, while the display quality as to the still image is not deteriorated, the moving image blurring that occurs when the moving image is displayed can be lowered by employing the simple circuit configuration of the display apparatus.
Next, a description is made of a second embodiment of the present invention with reference to
The input display data 101 input from an external system is processed so as to perform a data writing operation and a data reading operation in response to a memory control signal 1101. The memory control signal 1101 is produced in a control signal producing circuit 103 based upon a control signal 102 which is also input from the external system. In the first embodiment, the data is read at the speed two times higher than the writing speed by employing the frame doubler 108. In the second embodiment, as illustrated in
Similarly, in accordance with the second embodiment, the moving image blurring that occurs in displaying of the moving image can be lowered by employing the simple circuit arrangement without deteriorating the display quality of the still image.
As a third embodiment of the present invention, another example of a case where a calculating method different from that of the first embodiment is employed is described with reference to
With reference to the above-mentioned drawings, a description is made of the configuration and operations of the display apparatus according to the third embodiment. First, current frame display data 109 is processed by a current frame analysis range deriving circuit 201 so as to produce current frame derive data 203, and preceding frame display data 110 is processed by a preceding frame analysis range deriving circuit 202 so as to produce preceding frame derive data 204. The above-mentioned operations are identical to those of the first embodiment.
Next, the current frame derive data 203 and the preceding frame derive data 204 are processed by the current spatial direction data converting circuit 1301 and the preceding spatial direction data converting circuit 1303 so as to produce the current spatial direction conversion display data 1302 and the preceding spatial direction conversion data 1304, respectively, based upon conversion parameters which are different from each other for every field. Since algorithms and the conversion parameters of the current spatial direction data converting circuit 1301 and the current spatial direction conversion display data 1302 are equivalent to each other, when display data are not changed between frames, outputs thereof become equal to each other.
The temporal direction data converting circuit 1305 performs conversion of the temporal directions among the current spatial direction conversion data 1302 and the preceding spatial direction conversion data 1304 which have been produced in the above-mentioned manner and the current frame display data 109 so as to produce the spatial/temporal direction conversion data 1306. In this case, when the current spatial direction conversion data 1302 is coincident with the preceding spatial direction conversion data 1304, the spatial/temporal direction conversion data 1306 outputs the current frame display data 109. To the contrary, when the current spatial direction conversion data 1302 is not coincident with the preceding spatial direction conversion data 1304, between the current spatial direction conversion data 1302 and the preceding spatial direction conversion data 1304 based upon the algorithm of the temporal direction data converting circuit 210, which is described in the first embodiment, the spatial/temporal direction conversion data 1306 produces spatial/temporal direction conversion data 1306. Then, the produced spatial/temporal direction conversion data 1306 is transferred to the matrix type display 119 so as to be displayed.
The conceptional idea described above is illustrated in
As in the first embodiment, in the operations of the third embodiment described above, the moving image performance when the video is moved between the frames can be improved while maintaining the display quality equivalent to that of the input image when the still image is displayed.
When the present invention is applied, in a matrix type display apparatus having a display characteristic as that of a liquid crystal display apparatus, moving image blurring that occurs when a moving image is displayed can be reduced while maintaining a display quality of a still image. As a consequence, the present invention can be similarly applied to a television receiver equipped with a liquid crystal display panel, a display monitor provided in a personal computer, and further a cellular telephone, a game machine, or the like. In addition, the present invention can be applied not only to a hold type display such as an organic electroluminescence (EL) display in which an organic EL element is used for a light emitting device of a pixel portion, and a liquid crystal on silicon (LCOS) display in which a control element of a pixel portion is used under a reflection layer, but also to a plasma display panel (PDP) or the like.
While we have shown and described several embodiments in accordance with our invention, it should be understood that disclosed embodiments are susceptible of changes and modifications without departing from the scope of the invention. Therefore, we do not intend to be bound by the details shown and described herein but intend to cover all such changes and modifications within the ambit of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-281271 | Oct 2007 | JP | national |
