JP2011107214A - Display controller, display device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display controller which can make the effect of side images uniform for an observer. <P>SOLUTION: An LCD controller 21 which controls liquid display elements to display images to be displayed on a display screen by spatial luminance modulation; includes a memory 30 for main image for obtaining image data of the main image, a memory 31 for side images for obtaining image data of the side images, and an image synthesizing part 39 modulating the image data of the main image based on nonlinear correspondence relation of the luminance for the axial direction parallel with slope lines on the display screen and the luminance for the direction outside axis with respect to the luminance from the liquid crystal elements and the image data of the side images and turning the modulated image data into image data of the images to be displayed. The image synthesizing part 39 changes degree of modulation for pixel in accordance with pixel positions when a pixel to be modulated is output into the liquid crystal display elements as the image to be displayed when modulating a data value of each pixel of the main image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display control device, a display device, and an electronic apparatus that control a liquid crystal display element to display a display image by spatial luminance modulation.

  Conventionally, a liquid crystal display (LCD) has been widely used as a display for portable information devices such as mobile phones and PDAs (Personal Digital Assistants). LCDs have been considered to have a narrow viewing angle compared to CRTs (Cathode Ray Tubes), plasma displays, and the like, but with the recent advances in LCD technology, viewing angles have been widened.

  However, when the portable information device is used in a crowded situation such as in a train or a bus, the content displayed on the display screen of the portable information device may be peeped by the surrounding people. In particular, when creating and browsing an electronic mail, it is not preferable in terms of privacy that the contents are peeped by people around.

  In response to this problem, an LCD capable of controlling the viewing angle has been proposed (see, for example, Patent Document 1). In such an LCD, it is possible to switch from one of a normal wide viewing angle mode (public mode) and a narrow viewing angle mode (private mode) having a narrow viewing angle to the other. The narrow viewing angle mode is a mode in which a normal display image can be visually recognized from directly in front of the display screen where the user is present, and a plain image or another image can be viewed from an oblique direction.

  In the display device described in Patent Document 1, the liquid crystal display panel has a linear data value / luminance response in a narrow viewing angle range, and a non-linear data value / luminance response in a narrow viewing angle range. Utilizing having.

  Specifically, adjacent data values in the original image are corrected (modulated) by adding one divided value and subtracting the divided value by the other. The corrected image is viewed as an image equivalent to the original image because the human eye performs spatial averaging when the display screen is viewed on an axis parallel to the normal line of the display screen. When the display screen is viewed off-axis, the element of the division value is added. When the division value changes at a rate proportional to the masking image in the corrected image, both the original image and the masking image are visible off-axis, that is, in an oblique direction with respect to the display screen. If the masking image has a disturbing pattern such as a plaid pattern or a company logo, the original image is substantially hidden from off-axis observers. Thereby, the private mode is realized, and the observer on the axis can see the original image without being looked into. In the present specification, the masking image that is viewed only by an off-axis observer is referred to as a side image. The original image is referred to as a main image with respect to the side image.

JP 2007-017988 A (published on January 25, 2007)

  However, the conventional technique of Patent Document 1 causes the following problems.

  As described above, the main image (contents equivalent to the original image) is visually recognized when observed on an axis parallel to the normal line of the display screen. Therefore, if the line of sight connecting the observer's viewpoint and the observation location on the display screen is angled from an axis parallel to the normal, the side image (masking image) is visually recognized with a density corresponding to the angle. . This angle is referred to herein as the viewing angle.

  It is inconvenient for the on-axis observer and the off-axis observer that the side image (masking image) is visually recognized with a non-uniform density on one display screen according to the viewing angle. Such inconvenience, that is, the difference in darkness, becomes more prominent because the larger the area of the display screen, the larger the viewing angle.

  The present invention has been made in view of the above problems, and an object thereof is to realize a display control device, a display device, and an electronic apparatus that make the effect of a side image uniform for an observer.

  The display control device of the present invention is a display control device that controls a liquid crystal display element so as to display a display image on a display screen by spatial luminance modulation, and obtains main image image data from the outside. A side image acquisition unit that acquires image data of a side image from the outside, and a luminance with respect to an axial direction parallel to a normal line of the display screen and a luminance with respect to an off-axis direction with respect to the luminance from the liquid crystal display element An image synthesizing unit that modulates the image data of the main image based on the nonlinear correspondence and the image data of the side image, and uses the modulated image data as image data of the display image; When the combining unit modulates the data value of each pixel of the main image, the pixel position when the modulation target pixel is output to the liquid crystal display element as the display image In response, it is characterized by changing the degree of modulation for the pixel.

  According to the above configuration, the image composition unit, with respect to the luminance from the liquid crystal display element, the non-linear correspondence between the luminance with respect to the axial direction parallel to the normal line of the display screen and the luminance with respect to the off-axis direction, and the image of the side image Based on the data, the image data of the main image is modulated, and the modulated image data is used as the image data of the display image. Specifically, the data value of each pixel of the main image is modulated. When the display image is displayed on the liquid crystal display element, an observer located in a region on the axis from the liquid crystal display element (hereinafter referred to as “on-axis observer”) visually recognizes the main image, and An observer located in an off-axis region from the liquid crystal display element (hereinafter referred to as “off-axis observer”) views an image obtained by combining the main image and the side image. As a result, since the main image is disturbed by the side image and is difficult for the off-axis observer to see, the main image is actually only visible to the on-axis observer.

  Further, when the data composition unit modulates the data value of each pixel of the main image, the pixel is changed according to the pixel position when the modulation target pixel is output as the display image to the liquid crystal display element. Change the degree of modulation for.

  Thereby, even if the line-of-sight angle is largely generated due to the difference in the observation position of the display screen, the degree of modulation with respect to the pixel is adjusted in consideration of the pixel position. It is possible to make uniform for the same on-axis observer or off-axis observer.

  Furthermore, the display control apparatus of the present invention provides the liquid crystal display element showing a relationship between the data value of the pixel of the main image input to the liquid crystal display element and the luminance rate of the pixel output from the liquid crystal display element. A modulation table storage that holds an image data modulation table that stores the degree of modulation when the image composition unit modulates the data value of the pixel of the main image based on the gamma characteristic in association with the data value of the pixel The modulation table storage unit includes at least a first image data modulation table based on gamma characteristics when the display screen is observed from an axial direction parallel to a normal line of the display screen, and the axial direction. Holds a second image data modulation table based on gamma characteristics when observed from different directions, and the image composition unit is configured to store pixel positions of pixels to be modulated. Correspondingly selected, in accordance with at least one of the first image data modulation table and the second image data modulation table may determine the degree of modulation for the pixel.

  According to the above configuration, the image composition unit can change the degree of modulation according to the pixel position of the modulation target pixel by using at least the following two types of image data modulation tables properly or in combination. it can.

  That is, the first is a first image data modulation table created on the basis of the gamma characteristic of the liquid crystal display element when the observer sees the vicinity of the center of the display screen from the front, and the second is the observer. 5 is a second image data modulation table created based on the gamma characteristic of the liquid crystal display element when viewed from an oblique direction.

  In this way, a plurality of image data modulation tables having different line-of-sight angles are held in the own apparatus, and pixels that are referred to when determining the degree of modulation in accordance with the pixel position on the display screen are properly used. The degree of modulation of the pixel can be changed according to the position. When the degree of modulation is changed, the density of the side image when the side image is observed from a certain angle can be changed.

  As a result, the non-uniformity of the effect of the side image based on the line-of-sight angle caused by the difference in the observation location (pixel position) on the display screen is eliminated, and the darkness of the side image on the entire display screen is reduced for one observer. It can be made uniform.

  An area information storage unit that stores area information in which a coordinate system of the display screen is associated with a map obtained by dividing the display screen into a plurality of areas; and the plurality of pixel positions of the modulation target pixels are divided The area determination unit that determines which one of the areas belongs to, and at what ratio each of the first image data modulation table and the second image data modulation table is employed for each of the plurality of divided areas A distribution ratio storage unit that stores a distribution ratio indicating the distribution ratio selection unit that selects the distribution ratio corresponding to the region determined by the region determination unit from the distribution ratio storage unit, the image composition unit, According to the first image data modulation table and the second image data modulation table weighted based on the distribution ratio selected by the distribution ratio selection unit, It may determine a degree of modulation for the element.

  According to the above configuration, when determining the degree of modulation with reference to a plurality of tables, the image composition unit sets the ratio of adoption of each table to be referred to as the distribution ratio according to the pixel position of the display screen. So changing.

  As a result, the degree of modulation can be adjusted more finely according to the pixel position of the display screen, and therefore, the uniformity of the side image can be realized with higher quality.

  Further, the area information storage unit stores area information for at least dividing the first area closest to the center of the display screen and the second area closest to the end of the display screen, and the distribution ratio storage The unit stores a distribution ratio in which the ratio of the first image data modulation table is maximized in association with the first area, and the ratio of the second image data modulation table is associated with the second area. The largest distribution ratio may be stored.

  According to the above configuration, the image compositing unit, for pixels near the center of the display screen, mainly when the on-axis observer sees the center from the frontal viewpoint based on the first image data modulation table. In addition, the modulation can be performed so that only the main image is visible without the side image being seen. On the other hand, for the pixels at the end of the display screen, the side image cannot be seen mainly when the on-axis observer sees the end obliquely from the same viewpoint based on the second image data modulation table. It can be modulated so that only the main image is visible.

  In this way, by changing the ratio of adoption of the various tables referred to when determining the degree of modulation according to the position of the display screen (as the viewing angle increases away from the center), the on-axis observer can be changed. On the other hand, the effect of the side image can be made zero.

  Alternatively, the area information storage unit stores area information that at least separates the left and right side edges of the display screen as a first area and the other side edge as a second area, and the distribution ratio storage unit The distribution ratio in which the ratio of the first image data modulation table is maximized is stored in association with the first area, and the ratio of the second image data modulation table is maximized in association with the second area. May be stored.

  According to the above configuration, the image composition unit modulates the data value of the pixel mainly on the other side from the left or right side edge of the display screen based on the first image data modulation table. For the edge, the data value of the pixel is mainly modulated based on the second image data modulation table.

  Changing the degree of modulation between the side edge closer to the off-axis observer (the line of sight angle becomes smaller) and the far side edge (the line of sight angle becomes larger) absorbs the difference in the line of sight. As a result, the darkness of the side image seen from the off-axis observer can be adjusted to be uniform.

  As described above, the ratio of the adoption of the various tables referred to when determining the degree of modulation is changed according to the position of the display screen (as the line-of-sight angle increases). The effect of the image can be made uniform.

  Furthermore, the image composition unit is configured to receive the distribution ratio received from the distribution ratio selection unit according to the distance from the boundary line between the pixel position of the modulation target pixel and the adjacent area in the area information, and the adjacent position. You may employ | adopt the said 1st image data modulation table and the said 2nd image data modulation table by the ratio calculated | required by the weighted average with the distribution ratio corresponding to an area | region.

  With the above configuration, since a plurality of image data modulation tables are referred to after interpolating the distribution ratio in the vicinity of the boundary of each region, the degree of modulation is shifted more gently in the vicinity of the boundary to increase the density of the side image. It becomes possible to maintain higher quality and uniformity.

  A display device including the above-described display control device and a liquid crystal display element controlled by the display control device also falls within the scope of the present invention. Further, an electronic device including the display device also falls within the scope of the present invention.

  In order to solve the above problems, a display control apparatus of the present invention is a display control apparatus that controls a liquid crystal display element so as to display a display image on a display screen by spatial luminance modulation. A main image acquisition unit that acquires image data, a side image acquisition unit that acquires image data of a side image from the outside, and a luminance with respect to an axial direction parallel to a normal line of the display screen with respect to the luminance from the liquid crystal display element An image that modulates the image data of the main image based on a non-linear correspondence relationship with the luminance with respect to the off-axis direction and the image data of the side image, and uses the modulated image data as image data of the display image And a synthesizing unit, and when the image synthesizing unit modulates the data value of each pixel of the main image, the modulation target pixel is the liquid crystal display element as the display image. In accordance with the pixel position when the output is characterized by changing the degree of modulation for the pixel.

  Thereby, there is an effect that the effect of the side image for the observer can be made uniform.

It is a block diagram which shows the principal part structure of the LCD controller in the electronic device which is one Embodiment of this invention. It is a block diagram which shows schematic structure of the said electronic device. It is a figure which shows the brightness | luminance of an adjacent pixel. It is a graph which shows the responsiveness of the brightness | luminance with respect to a gradation value. It is a graph which shows the correspondence of the gradation value of the main image in the said electronic device, and the gradation value of the image for a display. It is a figure which shows the image of the front view in the said electronic device, and the image of a side view. (A) is a LCD module, the on-axis viewer V _on observing the display surface S, is a view from above of the observer. (B) includes the LCD module, the on-axis viewer V _on observing the display surface S, it is a view seen from the side of the observer. It is a figure which shows an example of the image of a front view when the effect of a side image is non-uniform | heterogenous. It is a figure which shows an example of the image data modulation table as a division | segmentation parameter memorize | stored in the division | segmentation parameter memory | storage part of the LCD controller in embodiment of this invention. It is a figure which shows the other example of the image data modulation table as a division parameter memorize | stored in the division parameter memory | storage part of an LCD controller. It is a figure which shows an example of area | region information memorize | stored in the area | region information storage part of an LCD controller. (A) And (b) is a figure which shows the specific example of the allocation ratio table memorize | stored in the allocation ratio memory | storage part of an LCD controller. It is a block diagram for demonstrating operation | movement of the image composition part of an LCD controller. It is a figure which shows the other example of area | region information memorize | stored in the area | region information storage part of an LCD controller. It is a figure which shows the example by which the area | region information memorize | stored in the said area | region information storage part was updated. It is the figure which looked at the LCD module and the off-axis observer V _off which observes (views) the display surface S from the right of the _on- axis observer V _on . It is a figure which shows an example of the area | region information which the area | region information storage part of the LCD controller in other embodiment of this invention memorize | stores. (A) And (b) is a figure which shows an example of the distribution ratio table memorize | stored in the distribution ratio memory | storage part of the LCD controller which concerns on other embodiment.

Embodiment 1
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 2 shows a schematic configuration of the electronic apparatus of the present embodiment. Examples of the electronic device 10 include portable electronic devices such as a notebook computer, an electronic notebook, a mobile phone, an electronic dictionary, and a portable communication terminal. The present invention includes an LCD (Liquid Crystal Display) unit (liquid crystal display). The present invention can be applied to any electronic device provided with a device. In particular, the present invention can be suitably used for an electronic device including an LCD unit having a relatively large display screen such as a television or a desktop personal computer.

  As shown in FIG. 2, the electronic device 10 includes a CPU (main control device) 11, a bus 12, a memory (main control device) 13, and an LCD unit (display device) 14.

  The CPU 11 performs various operations by executing a program stored in a storage element such as a RAM (Random Access Memory) or a flash memory, for example, and performs comprehensive control of various units in the electronic apparatus 10. 12 is performed. In the present embodiment, the CPU 11 transmits image data of the main image and the side image, various instructions, and the like to the LCD unit 14 via the bus 12. Here, the side image refers to an image superimposed on the main image in order to disturb the main image for the purpose of preventing peeping.

  The bus 12 is a common signal line for transmitting and receiving data between various components in the electronic device 10. The memory 13 stores various data and programs. As an example of the memory 13, a ROM (Read Only Memory) that is a read-only semiconductor memory that stores fixed data such as a program necessary for the operation of the CPU 11, data used for calculation, calculation results, and the like are temporarily stored. RAM as a so-called working memory stored in the memory.

  The LCD unit 14 receives image data from the CPU 11 or the memory 13 via the bus 12 and displays an image based on the received image data. The LCD unit 14 includes an LCD module 22 and an LCD controller (display control device) 21.

  The LCD module 22 is a functional unit that displays an image such as a character, a symbol, or a graphic on a display element based on image data of a display image, and is a matrix type LCD element (liquid crystal display) in which display pixels are arranged in a matrix. Element) and a drive circuit for driving the LCD element. The LCD element displays an image by spatial luminance modulation that spatially modulates the luminance of incident light from a light source. The image includes a still image and a moving image.

  The LCD controller 21 controls the LCD module 22. Specifically, the LCD controller 21 transmits image data of the display image to the LCD module 22 and transmits a plurality of control signals for controlling the display of the LCD module 22. Examples of the control signal include a vertical synchronization signal, a horizontal synchronization signal, and a transfer clock signal for transferring image data of a display image to each display pixel of the LCD element.

In the present embodiment, the _on- axis observation located in a region (hereinafter, referred to as “region on the axis”) A _on existing from the display screen of the LCD element of the LCD module 22 in the normal direction of the display screen. The person V _on visually recognizes the main image. On the other hand, an off-axis observer V _off located in an area where the display screen can be visually recognized and other than the area on the axis (hereinafter, this area is referred to as “ _off- axis area”) A _off . An image obtained by synthesizing the main image and the side image is visually recognized. This principle will be described below.

  In general, as the observer moves away from the display element, it becomes difficult to discriminate between adjacent pixels in the display element, and finally it becomes impossible to discriminate. At this time, the observer perceives the average value (average luminance) of luminance in the adjacent pixels.

From this, it can be said that it is shown in FIG. FIG. 3 shows the luminance of adjacent pixels. First, as shown in FIG. (A), the brightness between pixels _p 1 · _{p 2} of adjacent equal to _{I 0.} Next, as shown in FIG. 4B, one pixel p ₁ is changed to a luminance obtained by subtracting a certain luminance I ₁ from the original luminance I ₀ , and the other pixel p ₂ is changed to the original luminance I _2. The brightness is changed to a brightness obtained by adding a certain brightness I ₁ to I ₀ . In this case, the observer, when between the pixels _p 1 · _{p 2} to the adjacent can not be determined, as shown in FIG. (C), region _{p 12} of the pixel _p 1 · _{p 2} to the adjacent pixel The average luminance of the luminance of p ₁ (I ₀ −I ₁ ) and the luminance of the pixel p ₂ (I ₀ + I ₁ ), that is, the original luminance I ₀ is perceived.

  That is, if the observer moves away from the display element to such an extent that adjacent pixels cannot be distinguished even if the luminance of the adjacent pixels is changed as shown in FIG. The original luminance as in a) will be perceived.

  By the way, a normal display element does not respond proportionally to an input gradation value (for example, 0 to 255 when the image data is 8-bit data), and the output luminance is a constant power of the gradation value ( proportional response). For this reason, in a normal display unit, gamma correction is performed, and the output luminance responds in proportion to the input gradation value.

FIG. 4 is a graph showing the responsiveness of the luminance with respect to the gradation value. The gradation value and the luminance after gamma correction are proportional and have linearity as shown in FIG. In this case, assuming that the luminance corresponding to the gradation value (original value) D ₀ is I ₀ , the gradation value (D ₀ + D ₁ ) and the level obtained by adding and subtracting the divided value D ₁ from the original value D ₀ respectively. The luminance corresponding to the tone value (D ₀ -D ₁ ) is luminance (I ₀ + I ₁ ) and luminance (I ₀ -I ₁ ), respectively. Therefore, the average luminance is I ₀ , which is the same as the luminance I ₀ corresponding to the original value D ₀ .

  However, in the case of the LCD element, the light passing in the on-axis direction and the light passing in the off-axis direction not only have different optical path lengths through the liquid crystal, but also the liquid crystal molecules in the traveling direction of the light. The birefringence due to the difference in inclination is different. For this reason, with respect to the light passing in the on-axis direction, even if the gamma correction is performed so that the responsiveness of the luminance with respect to the gradation value is linear as shown in FIG. For light passing in the direction of, the response is nonlinear.

FIG. 4B shows a case where the response is nonlinear. Referring to (b) of the figure, in this case, the luminance I ₂ corresponding to the gradation value (original value) D ₀ is the gradation value (D ₀ + D _{1) obtained} by adding the divided value D ₁ from the original value D _0. ) And the luminance corresponding to the gradation value (D ₀ -D ₁ ) obtained by subtracting the divided value D ₁ from the original value D ₀ is different from the average luminance I ₃ .

Therefore, the gradation value is modulated so that _{one of} the adjacent pixels adds the divided value D ₁ from the original value D ₀ to the main image and the other subtracts the divided value D ₁ from the original value D _0. Let us consider a case in which the processed image is displayed on the LCD element. In this case, the on-axis observer views an image equivalent to the main image (average luminance I ₃ ), but the off-axis observer is modulated with respect to the main image in accordance with the division value D _1. The image (luminance I ₂ ) is visually recognized. Thus, in this embodiment, the divided value D ₁ of the said adjacent pixels of the main image, is associated with the gradation value of the corresponding pixel of the side image. Thereby, the off-axis observer visually recognizes the image in which the side image is combined with the main image.

By the way, referring to FIG. 4B, it can be understood that the difference between the luminance I ₂ and the average luminance I ₃ increases as the division value D ₁ increases. In the case of the present embodiment, if the difference between the luminance I ₂ and the average luminance I ₃ is large, the off-axis observer sees the side image more clearly, which is desirable from the viewpoint of preventing peeping of the main image. Accordingly, the divided value D ₁ is larger is preferable.

On the other hand, since the gradation value needs to be 0 or more, the gradation value (D ₀ -D ₁ ) obtained by subtracting the division value D ₁ from the original value D ₀ also needs to be 0 or more. For this reason, it is desirable to set the division value D ₁ such that the gradation value (D ₀ -D ₁ ) is 0 or a positive number close to 0. Further, the gradation value (D ₀ + D ₁ ) obtained by adding the division value D ₁ from the original value D ₀ needs to be equal to or less than the maximum value of the gradation values. For this reason, the main image needs to be compressed in the range of usable gradation values.

5, the tone value of the main image in the present embodiment, a graph showing a relationship between a gradation value of the display image is satisfying the above condition relates divided value D _1. FIG. 5 shows an example in which the side image has two gradations (0 or 255). Here, when the gradation value is 0, the side image has the highest degree of disturbance to the main image (maximum disturbance), and when the gradation value is 255, the side image does not disturb the main image (no disturbance). To do. Further, in the example of FIG. 5, the solid line and the broken line are expressed as straight lines, but in reality, they are often curved lines.

The solid line in FIG. 5 indicates the case where the gradation value of the side image is 255 (no disturbance). In this case, the gradation value of the display image is the compressed original value D ₀ ′ of the main image. Further, the broken line in FIG. 5 indicates a case where the gradation value of the side image is 0 (maximum disturbance). In this case, one of the gradation values of adjacent pixels in the display image is a gradation value (D ₀ ′ + D ₁ ) obtained by adding the division value D ₁ from the compressed original value D ₀ ′ of the main image. The other is the gradation value (D ₀ ′ −D ₁ ) obtained by subtracting the division value D ₁ from the compressed original value D ₀ ′ of the main image. When the side image has multiple gradations, a graph similar to the two broken lines in FIG. 5 is described between the solid line and the two broken lines in FIG. 5 according to the gradation value of the side image. become.

Thus, LCD controller 21 of the present embodiment, as shown in FIG. 5, the correspondence between the gradation value of the main image and the divided value D ₁ is stored as the partition parameter, the tone value of the main image, Modulation is performed based on the gradation value of the side image and the division parameter, and this is transmitted to the LCD module 22 as the gradation value of the display image. Accordingly, the on-axis observer visually recognizes the same image as the main image, while the off-axis observer visually recognizes an image in which the side image is combined with the main image. As a result, since the main image is disturbed by the side image and is difficult for the off-axis observer to view, the main image can be viewed only by the on-axis observer.

  FIG. 6 is a diagram illustrating a phenomenon in which the main image is disturbed by the side image when viewed from the off-axis observer. As described above, only the main image (the scenery of the station in the example of FIG. 6) is visually recognized by the on-axis observer viewing the display screen from the front. On the other hand, an off-axis observer viewing the display screen from the side views the image in which the side image (check pattern in the example of FIG. 6) is combined with the main image.

  In the example shown in FIG. 6, the check pattern of the side image is synthesized on the entire surface of the main image. That is, all areas on the main image are the targets of modulation. An area on the main image to be modulated is referred to as a modulation area. As in the example illustrated in FIG. 6, not all areas of the main image need be modulation areas. For example, by setting only a specific area as the modulation area, the off-axis observer can visually recognize the shape of the specific area. By making the modulation area a shape with a high degree of attention, it is possible to prevent the main image from being peeped from an off-axis observer.

[Non-uniformity of side image effect based on gaze angle]
Next, an example in which the effect of the side image becomes non-uniform will be described based on FIGS. 7A, 7B, and 8. FIG.

FIG. 7A is a view of the LCD module 22 and the on-axis observer V _on observing the display surface S as viewed from above the observer. FIG. 7B is a diagram of the LCD module 22 and the on-axis observer V _on observing the display surface S as viewed from the side of the observer.

If it demonstrates based on Fig.7 (a) and (b), a line-of-sight angle will be defined as follows. That is, in the present specification, an arbitrary observation location on the display surface S from the viewpoint Vp of the _on- axis observer Von from the viewpoint Vp extending in the normal direction to the display surface S and the viewpoint Vp at the same position. An angle θ formed by the line of sight VLo extending with respect to o is referred to as a “line of sight angle”.

  As described above, the main image (content equivalent to the original image) is visually recognized when observed on an axis parallel to the normal line of the display surface S.

Therefore, for example, if the line of sight from the viewpoint Vp of the _on- axis observer V _on to the center of the display screen is an axis parallel to the normal line (reference line of sight VLs), the display surface S is viewed from the same viewpoint Vp. A certain line-of-sight angle θ is generated between the line of sight (line of sight VLo) toward the end (observation point o) and the reference line of sight VLs. In this way, when a line-of-sight angle is generated in the same manner as when an off-axis observer observes the display surface S, a side image is also obtained from the _on- axis observer V _on depending on the position of the observation location on the display surface S. (Masking image) is partially visible. Specifically, from the viewpoint Vp, as shown in FIG. 8, the viewing angle increases toward the end of the display surface S, and accordingly, the side image looks darker.

  In this case, the visibility of the main image by the observer on the axis is lowered although the purpose is to prevent peeping by the observer off the axis. For the observer on the axis, it is desirable that the side image (masking image) is not displayed no matter which part of the display screen is observed. That is, it is desirable that the effect of the side image is uniformly zero.

  The LCD controller 21 according to the present embodiment can make the side image effect uniform for the on-axis observer. Below, the detail of the LCD controller 21 as a display control apparatus of this invention which makes the effect of a side image uniform is demonstrated.

[Configuration of display control device]
FIG. 1 is a block diagram showing a schematic configuration related to creating a display image using a main image and a side image in the LCD controller 21 of the present invention. As shown in FIG. 1, the LCD controller 21 includes at least a main image memory 30, a side image memory 31, a division parameter storage unit 38, and an image composition unit 39, and further includes an area information storage unit 44, A position information processing unit 45, an area determination unit 46, a distribution ratio storage unit 47, and a distribution ratio selection unit 48 are provided. In addition, the LCD controller 21 includes a color arrangement pattern storage unit 34, a color switching unit 35, an enlargement / reduction rate storage unit 36, an image enlargement / reduction unit 37, a rotation / inversion information storage unit 40, and a rotation / inversion unit for processing a side image. 41 may be provided.

  The main image memory 30 is a frame buffer that acquires and stores image data of the main image M from the CPU 11 or the memory 13. The image data of the main image M stored in the main image memory 30 is transmitted to the image composition unit 39 at a predetermined timing.

  The side image memory 31 acquires and stores the image data of the side image S from the CPU 11 or the memory 13. In the present embodiment, in order to save memory capacity, the capacity of the side image memory 31 is set to a quarter of that of the main image memory 30, and the side image S is stored in a size of a quarter of the main image M. It is supposed to be. Therefore, when the side image S is combined with the main image M, the image enlargement / reduction unit 37 enlarges the side image S by two times in the vertical and horizontal directions. The configuration of the LCD controller 21 is not limited to this.

  The color arrangement pattern storage unit 34 stores data of a plurality of color arrangement patterns. The color switching unit 35 uses the plurality of color arrangement patterns in the color arrangement pattern storage unit 34 to switch the color arrangement pattern of the side image at a predetermined timing. By changing the color arrangement pattern of the side image, the side image can be animated.

  Specifically, the color switching unit 35 first selects a certain color arrangement pattern from a plurality of color arrangement patterns in the color arrangement pattern storage unit 34. Next, the color switching unit 35 changes the color information of the image data of the side image from the side image memory 31 based on the selected color arrangement pattern data, and rotates the image data of the changed side image. Transmit to the reversing unit 41. Then, at a predetermined timing, the color switching unit 35 selects a color arrangement pattern different from the certain color arrangement pattern from the plurality of color arrangement patterns in the color arrangement pattern storage unit 34, and repeats the above operation.

  The rotation / inversion information storage unit 40 stores information on the rotation angle and information on the inversion direction such as left / right inversion and up / down inversion. Further, the rotation / reversal unit 41 rotates the side image at a predetermined timing based on the rotation angle information in the rotation / reversal information storage unit 40, or based on the reverse direction information in the rotation / reversal information storage unit 40. The side image is inverted at a predetermined timing. The side image can be animated by rotating or inverting the side image.

  Specifically, the rotation / inversion unit 41 rotates the image data of the side image from the color switching unit 35 based on the rotation angle information in the rotation / inversion information storage unit 40, and the image of the rotated side image Data is transmitted to the image enlargement / reduction unit 37 and the above operation is repeated. Alternatively, the rotation / inversion unit 41 inverts the image data of the side image from the color switching unit 35 based on the information of the inversion direction in the rotation / inversion information storage unit 40, and converts the image data of the inverted side image to the image It transmits to the expansion / contraction part 37 and repeats the said operation | movement.

  The enlargement / reduction ratio storage unit 36 stores a plurality of enlargement / reduction ratios which are enlargement ratios or reduction ratios of image sizes. The image enlargement / reduction unit 37 uses the plurality of enlargement / reduction rates in the enlargement / reduction rate storage unit 36 to enlarge or reduce the image size of the side image at a predetermined timing. By increasing or reducing the image size of the side image, the side image can be converted to a moving image.

  Specifically, the image enlargement / reduction unit 37 first selects a certain enlargement / reduction rate from a plurality of enlargement / reduction rates in the enlargement / reduction rate storage unit 36. Next, the image enlargement / reduction unit 37 changes the image data of the side image from the rotation / inversion unit 41 so as to become the image data of the side image enlarged or reduced at the certain enlargement / reduction ratio, and the changed side image The image data of the image is transmitted to the image composition unit 39. Then, at a predetermined timing, the image enlargement / reduction unit 37 selects an enlargement / reduction rate different from the certain enlargement / reduction rate from a plurality of enlargement / reduction rates in the enlargement / reduction rate storage unit 36, and repeats the above operation.

  The division parameter storage unit 38 stores the above-described division parameters. The image composition unit 39 modulates the image data of the main image from the main image memory 30 based on the image data of the side image from the image enlargement / reduction unit 37 and the division parameter in the division parameter storage unit 38. It is. The image composition unit 39 transmits the modulated image data to the LCD module 22 as image data of the display image.

  When the modulated image data is displayed on the LCD module 22, only the main image M is visually recognized on the axis, and the side image S superimposed on the main image M is visually recognized from the outside of the axis (FIG. 6).

  In the present embodiment, the division parameter storage unit 38 stores a plurality of types of division parameters as shown in FIGS. 9 and 10. As shown in FIGS. 9 and 10, in this embodiment, the division parameter is realized by an “image data modulation table” that can specify the luminance rate to be output based on the gradation value of the main image. Yes. The image composition unit 39 refers to the image data modulation table in order to modulate the gradation value of the main image M. Hereinafter, the image data modulation table is simply referred to as a lookup table (LUT).

  In the LUT shown in FIG. 9, the solid line indicates the front view gamma characteristic of the LCD module 22 when the observer views the display surface from the front (that is, when the display surface is observed at a viewing angle of 0 degree). In the LUT shown in FIG. 10, the solid line indicates the LCD module 22 when the observer views the display surface from an oblique direction (that is, when the display surface is observed with a viewing angle of 0 degrees or more (for example, 30 degrees)). An oblique gamma characteristic is shown.

  Here, the LUT created in advance based on the gamma characteristic of the front view as shown in FIG. 9 is particularly referred to as a front LUT (first image data modulation table), and the oblique direction gamma as shown in FIG. An LUT created in advance based on the characteristics is particularly referred to as an oblique LUT (second image data modulation table), and the two may be distinguished. This solid line is given as an example for explaining the present invention, and should not be fixedly understood as the front view gamma characteristic / diagonal direction gamma characteristic of the LCD module 22 of the present invention.

By referring to the LUT as the division parameter, the image composition unit 39 can specify the luminance rate to be realized for each pixel in the modulation area of the main image M based on the gradation value of the pixel. . Then, it outputs the image data of the to achieve a particular luminance ratio by modulating the tone values of the pixels (the divided value D ₁ addition or subtraction with) the display image on the LCD module 22.

  More specifically, the image composition unit 39, based on the gradation value (Input Main Image Data Value) of the main image, the luminance ratio to be realized, that is, two luminance ratios divided and output to the LCD module 22 (Normalized Output Luminance) is specified based on the dashed curve. When the observer averages and visually recognizes each pixel having these two luminance rates, the average luminance rate matches the luminance rate corresponding to the gradation value of the main image on the solid line. That is, the two broken lines are determined so as to coincide with the gamma characteristic of the solid line when averaged. The image composition unit 39 modulates the gradation value of the main image M so as to realize each of the two specified luminance rates.

  Here, in the LCD controller 21 of the present invention, the division parameter storage unit 38 stores a plurality of LUTs. Specifically, the front LUT shown in FIG. 9 and the oblique LUT shown in FIG. 10 are stored. The image composition unit 39 modulates the gradation value of the main image by using a plurality of LUTs stored in the division parameter storage unit 38 according to which position on the display surface S the modulation area corresponds to. Is possible.

  Thereby, the nonuniformity of the effect of the side image due to the occurrence of the line-of-sight angle on one display screen can be eliminated. For example, even when an on-axis observer observes the edge of the display screen, the side image can be prevented from being visually recognized in the same manner as when the center is observed.

  Further, in the present embodiment, by referring to the front LUT and the diagonal LUT with weighting with a predetermined distribution, it is possible to adjust the density of the side image depending on the line-of-sight angle more finely. . In order for the image composition unit 39 to perform modulation of the main image based on a plurality of LUTs, the LCD controller 21 includes an area information storage unit 44, a position information processing unit 45, an area determination unit 46, a distribution ratio storage unit 47, and a distribution ratio. A selection unit 48 is provided.

  The area information storage unit 44 stores area information in which the coordinate system of the display screen of the LCD module 22 is associated with a map for dividing the display screen into a plurality of areas.

  FIG. 11 is a diagram illustrating an example of area information stored in the area information storage unit 44. As shown in FIG. 11, the area information is obtained by associating a coordinate system of the display screen of the LCD module 22 with a map concentrically divided into seven areas A to G. Each region is appropriately determined according to the size of the line-of-sight angle. In the example shown in FIG. 11, when the observer's viewpoint Vp is at the center of the display surface S, on the display surface S, The regions where the line-of-sight angles are approximately 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, and 30 degrees are distinguished from each other by adding symbols A to G. Note that the number of regions may be less or more than seven. The shape of the region is not particularly limited to a concentric circle, and may be an ellipse, a square, a rectangle, or the like.

  In the example shown in FIG. 11, the display screen of the LCD module 22 is a horizontally long rectangle, and the upper left end of the display screen is defined at a predetermined position on the map as the origin of the coordinate system. By referring to this, the region determination unit 46 can determine to which region the drawing target pixel belongs.

  The position information processing unit 45 specifies a drawing target pixel on the LCD module 22. Specifically, the position information processing unit 45 acquires the current drawing position (X and Y coordinates of the drawing target pixel) known by the LCD controller 21 itself, and uses the acquired X and Y coordinates of the drawing target pixel. The information is transmitted to the area determination unit 46 and the image composition unit 39.

  The region determination unit 46 determines which region on the map the drawing target pixel specified by the position information processing unit 45 belongs to. Based on the X and Y coordinates of the drawing target pixel acquired from the position information processing unit 45, the region determining unit 46 determines which region of A to G shown in FIG.

  The distribution ratio storage unit 47 stores the distribution ratio of a plurality of LUTs to be applied for each divided area. In the present embodiment, the distribution ratio storage unit 47 holds a distribution ratio table shown in FIG.

  In the present embodiment, the front LUT and the diagonal LUT are separately used for the region A having the smallest line-of-sight angle and the region G having the largest line-of-sight angle, without using a plurality of LUTs. Adopt and determine the split value. Therefore, in the example shown in FIG. 12A, in the distribution ratio table, information indicating that 100% of a single LUT is used as the distribution ratio is associated with these areas. On the other hand, the value “SHIFT_N (N is 1 to 5 here)” indicating the ratio of adopting the oblique LUT is associated with the other areas according to the size of the line-of-sight angle. For example, SHIFT_4 means that 50% of the oblique LUT is used.

  The distribution ratio selection unit 48 selects a distribution ratio associated with the region from the distribution ratio table stored in the distribution ratio storage unit 47 based on the region determined by the region determination unit 46. is there. The distribution ratio selection unit 48 transmits the selected distribution ratio (for example, “distribution ratio: SHIFT_4 (= 0.5)” when the region is determined to be E) to the image composition unit 39.

  FIG. 13 is a block diagram for explaining the operation of the image composition unit 39. The image composition unit 39 acquires the X and Y coordinates of the drawing target pixel P from the position information processing unit 45. Then, the data value of the pixel of the main image M and the data value of the pixel of the side image S corresponding to the position of the pixel P are obtained from the main image memory 30 and the side image memory 31, respectively. Then, the image composition unit 39 acquires a distribution ratio from the distribution ratio selection unit 48. When the ratio of one LUT is 0, the distribution ratio may simply be information specifying the other single LUT to be adopted. The image composition unit 39 acquires the front LUT and / or the oblique LUT from the division parameter storage unit 38 according to the distribution ratio.

  When the distribution ratio selection unit 48 selects one of the distribution ratios (SHIFT_1 to 5), the image composition unit 39 combines the front LUT 380 and the diagonal LUT 381 with the distribution according to the distribution ratio. Thus, the intermediate LUT 382 is generated. From the intermediate LUT, a division value for reproducing the gradation of the pixel P to be drawn in the main image is obtained. Based on the division value, the gradation value of the pixel P can be modulated (that is, the division value is added or subtracted depending on the pixel position). The value of the intermediate LUT is obtained by, for example, intermediate LUT = front LUT * (1−SHIFT_N) + diagonal LUT * SHIFT_N (N is 1 to 5 here).

Note that the image composition unit 39 does not generate an intermediate LUT, but derives a luminance value to be aimed at in order to derive a division value to be applied to the pixel P based on the gradation value X of the pixel P, using the following formula [ 1].
Luminance ratio to be aimed = Luminance ratio L _x1 of gradation value X in front LUT (FIG. 9) * (1-SHIFT_N) + Luminance ratio L _x2 of gradation value X in oblique LUT (FIG. 10) * SHIFT_N (here Then, N is 1 to 5) ... [1]
The application division value D to be applied to the pixel P is determined based on the “brightness ratio to be aimed at” obtained by the equation [1] and the gradation of the side image.

  According to the above configuration, the image composition unit 39 modulates the gradation value based on the division value obtained according to the positional relationship of the display screen with respect to the modulation area. Thus, the closer the display screen region is to the end, the higher the proportion of adopting the oblique LUT. Therefore, the same side image effect as that obtained when viewing a region near the center where there is almost no line-of-sight angle can be obtained even in the end region where the line-of-sight angle is large. That is, it is possible to prevent the side image from being visually recognized in the same manner when the on-axis observer sees the region A near the center or the end regions G and F from the same viewpoint Vp.

  The distribution ratio storage unit 47 may hold the distribution ratio table stored in FIG. In this case, the distribution ratio selection unit 48 transmits the ratio of each of the front LUT and the diagonal LUT to the image composition unit 39 as a distribution ratio for each determined area. Thereby, the image composition unit 39 uses the respective ratios acquired from the distribution ratio selection unit 48 as they are as the weighting coefficients, and generates an intermediate LUT or obtains an application division value without using the above formula. be able to.

  As described above, the shape of the map stored in the area information storage unit 44 is not limited to concentric circles. For example, as shown in FIG. 14, the region information storage unit 44 may hold, as region information, an association of seven elliptical regions and the coordinate system of the display screen. This makes it possible to more appropriately adjust the effect of the side image more appropriately in accordance with the line-of-sight angle considering both eyes of the observer as the viewpoint.

  By the way, in recent years, as represented by a mobile phone or the like, many liquid crystal display devices of electronic devices have a configuration that can rotate about the normal direction of the display screen. For example, when the display screen of the LCD module 22 is a horizontally long rectangle, the display content can be observed by rotating it 90 degrees to make it vertically long. However, when the shape of each area of the map is an ellipse or a rectangle as in the example shown in FIG. 14, when the display screen is rotated 90 degrees, the correspondence between each area and the coordinate system of the display screen changes. Therefore, in such a case, it is preferable to update the area information according to the rotation of the display screen. For example, as shown in FIG. 15, when the CPU 11 detects the rotation of the LCD module 22, the coordinate system of the display screen is rotated 90 degrees with respect to the map in the same manner as the actual rotation, and the area information is updated. This makes it possible to always keep the correspondence between the line-of-sight angle on the display screen after rotation and the region correct.

<< Embodiment 2 >>
In the above-described embodiment, the configuration of the LCD controller 21 that can be adjusted so that the side image does not appear uniformly to the on-axis observer has been described. The LCD controller 21 of the present invention is not limited to this, and the effect of the side image for the off-axis observer can be made uniform. Hereinafter, another example of the LCD controller 21 as a display control apparatus of the present invention that makes the effect of the side image uniform will be described.

[Non-uniformity of side image effect based on gaze angle]
FIG. 16 is a view of the LCD module 22 and the off-axis observer V _off that observes (looks at) the display surface S from the right of the _on- axis observer V _on as viewed from above the observer.

When observing the display surface S from the viewpoint Vp off-axis viewer V _off, the line of sight angle theta ₂ in the case of the observation point area A _L near the left end on the display surface S, the observation area A _R of the vicinity of the right end portion angle difference occurs between the line of sight angle theta ₁ at which a, which causes a non-uniformity of density of the side image. Here, the vicinity of the left (right) and left (right) ends of the display surface S indicates the left side (right side) of the display surface S as viewed from the observer.

Specifically, the angle of the line of sight angle theta ₁ is less than the line of sight angle theta _2, therefore, the side image off-axis viewer V _off is observed in the region A _R is the side image to be observed in the area A _L It is thinner and less noticeable. This makes it difficult for the off-axis observer V _{off to} recognize what the side image is as a whole. As a result, the attention degree of the side image is lowered, and the shielding effect of the main image against the _off- axis observer V _off is weakened, and there is a problem that the role of preventing peeping cannot be played.

  In the present embodiment, the LCD controller 21 can make the side image effect uniform for the off-axis observer. By showing the side image with a uniform density to the off-axis observer, it is possible to increase the degree of attention of the side image and enhance the shielding effect of the main image.

[Configuration of display control device]
FIG. 17 is a diagram illustrating an example of area information stored in the area information storage unit 44 of the LCD controller 21 according to the present embodiment. In the example shown in FIG. 17, the region information storage unit 44 divides the horizontally long side of the display screen into seven equal parts and divides the information into seven areas so that the widths of the areas are equally spaced. And the coordinate system of the display screen of the LCD module 22 associated with the map. It should be noted that the width of each area of the map does not need to be equally spaced, and the number of areas may be smaller or larger than seven.

  The region determination unit 46 in FIG. 1 determines to which region the pixel to be drawn belongs based on the region information shown in FIG. 17 and transmits the determination result to the distribution ratio selection unit 48.

  18A and 18B are diagrams showing an example of a distribution ratio table stored in the distribution ratio storage unit 47 of the LCD controller 21 according to the present embodiment.

In the present embodiment, two distribution ratio tables shown in FIGS. 18A and 18B are held. This is because the relationship between each area and the distribution ratio varies depending on whether the off-axis observer V _off is on the right side of the display surface S or on the left side. The distribution ratio table shown in FIG. 18A is a table that the distribution ratio selection unit 48 should refer to when the _off- axis observer V _off is on the right side of the display surface S, and is shown in FIG. The distribution ratio table is a table that the distribution ratio selection unit 48 should refer to when the _off- axis observer V _off is on the left side of the display surface S.

When the off-axis observer V _off is on the right side of the display surface S, the distribution ratio selection unit 48 refers to the distribution ratio table in FIG. 18A and corresponds to the region determined by the region determination unit 46. Select a distribution ratio.

  As in the case of the first embodiment, the image composition unit 39 determines a division value based on the distribution ratio transmitted from the distribution ratio selection unit 48 and modulates each pixel in the modulation region.

According to the above arrangement, for example, an off-axis viewer V _off is, if you are in the right side of the display surface S, the right area A _R of the display surface S close to the off-axis viewer V _off, the front for LUT while modulated according cutoff value is made based, in left area a _L of the display surface S, as it approaches the left end, are increasing the rate of synthesis of diagonal for LUT.

When obtaining the divided value, the more increased the percentage to refer to the diagonal for LUT, from the right side of the axis viewer V _off, the line of sight angle is increased (e.g., line of sight angle theta ₂₎ of the side image on the area A _L Can reduce the intensity. Therefore, originally a small angle (e.g., line of sight angle theta ₁₎ for the density of the region A _R of the side image appears relatively thin, it is possible to unify the density of the side image. Therefore, the off-axis observer can visually recognize the side image with uniform darkness.

  For example, while moving a long distance with a vehicle, use cases such as preventing the main image from being peeked by showing the side image uniformly to passengers in the next seat (off-axis observer) As assumed. Note that the method for determining whether the off-axis observer is on the left or right of the user (on-axis observer) of the electronic device 10 is not particularly limited, and may be recognized by an arbitrary method. A configuration may be adopted in which the user selects whether to prevent peeping from an off-axis observer on the left or right and inputs the electronic device 10.

  As described above, according to the LCD controller 21 of the present embodiment, the effect of the side image for the off-axis observer is made uniform, thereby increasing the degree of attention of the side image and preventing peeping of the main image. It is possible to enhance the original effect of the image.

≪Modification≫
In each of the above embodiments, the display screen is divided into seven regions, and the image composition unit 39 determines the degree of modulation with reference to a plurality of LUTs according to a certain distribution ratio for each region. The configuration of the image composition unit 39 is not limited to this.

  When the distribution ratio changes greatly at the boundary of the divided area, a side near the boundary on the display screen by each pixel modulated according to the division value obtained from the LUT adopted based on the distribution ratio. There may be a noticeable difference in image effect (darkness). Therefore, it is preferable that the distribution ratio is gradually changed near the boundary of the region so that the boundary is not noticeable.

  Therefore, for the pixels near the boundary between two adjacent regions, the image composition unit 39 adopts a weighted average of the distribution ratios associated with both regions according to the distance of the pixel from the boundary. May refer to a plurality of LUTs after interpolating the distribution ratio.

  In each of the embodiments described above, the configuration in which the division parameter storage unit 38 holds two types of division parameters, the front LUT and the diagonal LUT, is not limited to this, and the division parameter storage unit 38 is not limited thereto. Two or more types of division parameters may be stored in the division parameter storage unit 38 according to the realizable storage capacity. For example, in the above-described example, the area information storage unit 44 stores seven areas as the area information. Therefore, the division parameter storage unit 38 may hold seven types of LUTs corresponding to each area. Alternatively, one type of division parameter is stored in the division parameter storage unit 38, and the image synthesis unit 39 performs weighting according to the pixel position to be drawn, uses the division parameter, and determines the gradation value. The degree of modulation may be determined.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The display control device of the present invention can make the effect of the side image uniform for the observer regardless of the size of the viewing angle with respect to the display screen. Therefore, the present invention can be applied to various electronic devices having a function of preventing peeping by side images, and particularly suitable for electronic devices including a liquid crystal display device having a display surface with a sufficient area for increasing the viewing angle. Can do.

10 Electronic Equipment 11 CPU (Main Control Device)
12 bus 13 memory 14 LCD unit (display device)
21 LCD controller (display control device)
22 LCD module (liquid crystal display element)
30 Main image memory (main image acquisition unit)
31 Side image memory (side image acquisition unit)
34 color arrangement pattern storage unit 35 color switching unit 36 enlargement / reduction rate storage unit 37 image enlargement / reduction unit 38 division parameter storage unit (modulation table storage unit)
39 Image composition unit 40 Rotation / inversion information storage unit 41 Rotation / inversion unit 44 Area information storage unit 45 Position information processing unit 46 Area determination unit 47 Distribution ratio storage unit 48 Distribution ratio selection unit 380 Front LUT (first image data modulation) table)
381 Slanting LUT (second image data modulation table)
382 Intermediate LUT

Claims (8)

A display control device that controls a liquid crystal display element to display a display image on a display screen by spatial luminance modulation,
A main image acquisition unit for acquiring image data of the main image from the outside;
A side image acquisition unit that acquires image data of a side image from outside;
With respect to the luminance from the liquid crystal display element, based on the nonlinear correspondence between the luminance with respect to the axial direction parallel to the normal line of the display screen and the luminance with respect to the off-axis direction, and the image data of the side image, An image composition unit that modulates image data of an image and uses the modulated image data as image data of the display image;
When the image synthesis unit modulates the data value of each pixel of the main image, the image synthesis unit modulates the pixel according to the pixel position when the modulation target pixel is output as the display image to the liquid crystal display element. A display control apparatus characterized by changing the degree of the display. Based on the gamma characteristic of the liquid crystal display element indicating the relationship between the data value of the pixel of the main image input to the liquid crystal display element and the luminance rate of the pixel output from the liquid crystal display element, the image composition unit A modulation table storage unit that holds an image data modulation table that stores the degree of modulation when modulating the data value of the pixel of the main image in association with the data value of the pixel,
The modulation table storage unit is at least
Based on the first image data modulation table based on gamma characteristics when the display screen is observed from an axial direction parallel to the normal line of the display screen, and based on gamma characteristics when observed from a direction different from the axial direction. Holding a second image data modulation table,
The image composition unit determines the degree of modulation for the pixel according to at least one of the first image data modulation table and the second image data modulation table selected according to the pixel position of the pixel to be modulated. The display control device according to claim 1, wherein the display control device is determined. An area information storage unit for storing area information in which the coordinate system of the display screen is associated with a map obtained by dividing the display screen into a plurality of areas;
An area determination unit that determines which of the plurality of divided areas the pixel position of the pixel to be modulated belongs to;
A distribution ratio storage unit that stores a distribution ratio indicating which ratio of the first image data modulation table and the second image data modulation table is adopted for each of the plurality of divided areas;
A distribution ratio selection unit that selects a distribution ratio corresponding to the region determined by the region determination unit from the distribution ratio storage unit;
The image synthesizing unit is configured to weight the pixels according to the first image data modulation table and the second image data modulation table weighted based on the distribution ratio selected by the distribution ratio selection unit. The display control apparatus according to claim 2, wherein: The area information storage unit
Storing region information for at least dividing the first region closest to the center of the display screen and the second region closest to the edge of the display screen;
The distribution ratio storage unit
In association with the first area, the distribution ratio at which the ratio of the first image data modulation table is the largest is stored,
4. The display control apparatus according to claim 3, wherein a distribution ratio at which the ratio of the second image data modulation table is maximized is stored in association with the second area. The area information storage unit
Storing region information that at least separates the left and right side edges of the display screen as a first region and the other side edge as a second region;
The distribution ratio storage unit
In association with the first area, the distribution ratio at which the ratio of the first image data modulation table is the largest is stored,
4. The display control apparatus according to claim 3, wherein a distribution ratio at which the ratio of the second image data modulation table is maximized is stored in association with the second area. The image composition unit
The distribution ratio received from the distribution ratio selection unit according to the distance from the boundary line with the adjacent area in the area information of the pixel position of the modulation target pixel, and the distribution ratio corresponding to the adjacent area 6. The display control apparatus according to claim 3, wherein the first image data modulation table and the second image data modulation table are employed at a ratio obtained by a weighted average.   A display device comprising: the display control device according to claim 1; and a liquid crystal display element controlled by the display control device. A display device according to claim 7 and a main control device,
The main control device transmits image data of the main image and the side image to the display control device.

Images