JP2008242342A - Television apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a television apparatus capable of displaying an image of almost uniform image quality over the whole display screen when the display screen is viewed from an oblique direction. <P>SOLUTION: A representative correction value for controlling a display device 8 so that color attributes may not be changed even when an angle of a user's visual line is changed is stored in a correction value storage means 4, an angle of viewer's visual line about the display screen is detected by position detection means 1, 2, the angle of the user's visual line is calculated in each area or in each pixel by a correction value calculation means 3, a partial correction value for controlling the display device so that color attributes of the whole display screen may not be changed is calculated, and a control means 7 controls the display device in accordance with the partial correction value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a television apparatus suitable for a viewer who is not facing a display screen (hereinafter also referred to as a user) to perform comfortable viewing.

  2. Description of the Related Art A thin television device using an LCD (Liquid Crystal Display) or a PDP (Plasma Display Panel) often employs a swing mechanism that can change the angle of a display screen in the horizontal direction. The reason is that, when the user is not facing the display screen, the display screen is directed toward the user side, so that the geometrical deformation of the image is eliminated, and the image quality that changes within the viewing angle is displayed on the LCD. The purpose is to make it close to the image quality when viewed from the front, and to compensate for the drawback of a narrow viewing angle.

On the other hand, an effort has been made to reduce the difference in image quality between when viewed from the front and when viewed from an oblique direction by widening the viewing angle against “change in image quality” that occurs when viewing from an oblique direction. As an example, Patent Document 1 below discloses a liquid crystal display device that uses an input image signal as an input and sequentially switches and displays a plurality of images having different gamma characteristics. In addition, when the screen is large, a phenomenon that the image quality is different between the left and right sides of the screen when viewed from an oblique direction is likely to occur. Therefore, Patent Document 2 below discloses a display device that corrects brightness at the same time as correcting geometric distortion when viewed obliquely.
JP-A-7-121144 (paragraph 0016) Japanese Patent Laying-Open No. 2005-115069 (paragraphs 0018 and 0022)

  However, the technique disclosed in Patent Document 1 described above has a problem that the image quality viewed from the front is deteriorated and the image quality viewed from other than the front is not the same as that of the front. The technique disclosed in Patent Document 2 described above corrects a change in brightness that occurs when correcting geometric distortion, but does not correct a change in luminance or hue caused by the tilt of the display screen. For this reason, the display device having viewing angle characteristics has a problem that luminance unevenness and hue unevenness occur on the screen.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a television device capable of displaying an image with substantially uniform image quality over the entire display screen when the display screen is viewed from an oblique direction. It is to provide.
Another object of the present invention is to provide a television device that does not deteriorate image quality even when used normally from the front, even if the image quality is improved when viewed from an oblique direction.

In order to achieve the above-described object, the present invention provides a display screen composed of a plurality of areas by independently controlling R, G, and B for each area or each pixel for displaying an image on the display screen. A display device that is configured to change the attributes of
A correction value for storing the correction value for controlling the display device so that the color attribute does not change even if the angle of the line of sight viewing the display screen from an oblique direction is changed, corresponding to the angle of the typical line of sight. Storage means;
Position detecting means for detecting the angle of the line of sight of the viewer with respect to the display screen at a plurality of locations at different distances from the viewer;
The viewer's line-of-sight angle is calculated for each area or each pixel based on the detection value of the position detection means, and the entire display screen is calculated based on the correction value stored in the correction value storage means. Partial correction value calculating means for calculating a partial correction value for controlling the display device for each area or for each pixel so that the color attribute does not change;
Control means for controlling the display device according to the calculated partial correction value;
A television device provided.

  In the present invention, the correction value for controlling the display device so that the color attribute does not change even if the angle of the line of sight viewing the display screen from an oblique direction is changed is stored corresponding to the angle of the typical line of sight. The angle of the viewer's line of sight with respect to the display screen is detected at a plurality of locations at different distances from the viewer, and the angle of the viewer's line of sight is calculated for each area or pixel, and the color of the entire display screen Since the partial correction value for controlling the display device is calculated for each area or pixel so that the attribute does not change and the display device is controlled according to this partial correction value, the display screen is viewed obliquely. A television device capable of displaying an image with substantially uniform image quality over the entire display screen is provided.

  Further, in the present invention, it is configured to control the display device by detecting the angle of the line of sight for the user facing the display screen, so even if the image quality is improved when viewed from an oblique direction, Provided is a television device in which image quality does not deteriorate even during normal use as viewed from the front.

  Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a television apparatus according to the present invention, in particular, for each area in which a liquid crystal panel is used as a display medium and the display screen is divided into a plurality of parts on control. In addition, in order to control brightness, color density, and hue, a display device having a backlight capable of independently controlling RGB light sources (only a backlight and a liquid crystal panel are shown in FIG. 1) is a constituent element.

  In FIG. 1, the remote control light receiving unit 1 has a plurality of PSDs (Position Sensitive Devices: position detection) mounted at positions at different distances from the user viewing the display screen from an oblique direction, preferably at the left, right, top and bottom edges of the display screen. Element). This PSD receives infrared light emitted from a remote control device (not shown) (hereinafter also referred to as a remote control), that is, receives a remote control signal and detects the incident angle as the angle of the user's line of sight. Thus, for example, those disclosed in paragraph 0009 of JP-A-6-6645 can be used.

  Based on the remote control signal received by the remote control light receiving unit 1, the user position detection unit 2 as a position detection unit uses, as the user's viewpoint position information, the angle of two horizontal lines of sight at the edges of the display screen separated from each other, and The angles of two lines of sight in the vertical direction are respectively calculated. The ROM 4 as a correction value storage means corresponds to each of a plurality of typical angles in order to make the attributes of three colors, namely luminance, color density and hue constant, with respect to a change in the angle of viewing the display screen from an oblique direction. The correction values of the brightness, color density, and hue of the backlight are stored as a table. Based on the user's viewpoint position information calculated by the user position detection unit 2, the control unit 3 serving as the partial correction value calculation unit has the luminance, color density, and hue for each area having different angles when viewed from the oblique direction. Referring to the correction value stored in the ROM 4 so as to be substantially equal to each other, a backlight control signal for controlling the backlight is generated, and the line-of-sight angle for each area to correct the geometric deformation Generate information. The backlight area control unit 7 controls the RGB light sources for each area into which the backlight 8 is divided in accordance with the backlight control signal generated by the control unit 3. In addition, the scaling circuit 6 performs a process of correcting the trapezoidal distortion on the video signal received through the tuner 5 based on the information on the line-of-sight angle generated by the control unit 3 and applies it to the liquid crystal panel 9. .

  The operation of the present embodiment configured as described above will be described below with reference to FIGS. In general, when a display screen is viewed obliquely, a liquid crystal display device changes in luminance, color density, and hue according to the angle. FIG. 2A is a diagram showing the relationship between the line-of-sight angle and the luminance when the display screen is viewed obliquely. When the luminance in the front where the line-of-sight angle is 0 ° is 100%, The luminance decreases as the distance from the front increases, that is, as the absolute value of the line-of-sight angle increases. FIG. 2B is a diagram showing the relationship between the line-of-sight angle and the color displacement Δ (u ′, v ′) when the display screen is viewed obliquely, and the line-of-sight angle is 0 °. As the distance from a certain front increases, that is, as the absolute value of the line of sight increases, the degree of color displacement increases and the hue changes. In the present embodiment, when the display screen is viewed from an oblique direction, the image quality is made uniform over the entire display screen by correcting the luminance, color density, and hue for each display area having a different line-of-sight angle. .

Now, as shown in FIG. 3, when the user 12 is shifted to the right in the horizontal direction with respect to the display screen 11, attention is paid to two places at the edges where the distance from the user 12 is different from each other. Here, the angle formed by the line of sight 13 with the normal 14 at the left end of the display screen 11 having the horizontal width L, that is, the angle of the line of sight α, and the angle formed by the line of sight 15 with the normal 16 at the right end of the display screen 11, that is, the line of sight. If the angle is β, and the angle of the line of sight of the user 12 at a position away from the right end of the display screen 11 by the distance x is deg, the following equation is established.
deg = {α · x + β · (L−x)} / L (1)

  As apparent from the equation (1), when the user 12 views the display screen 11 from an oblique direction, the angle of the line of sight gradually changes according to the distance x from the end in the horizontal width direction. That is, when the user is not facing the display screen 11, the distance x from the edge in the lateral width direction depends on the luminance and color displacement degree change characteristics shown in FIGS. 2 (a) and 2 (b). As a result, the luminance, color density, and hue gradually change, and the image quality does not become uniform. According to the inventor's experiment, an area with a large line-of-sight angle, that is, an area located in the back, looked darker. In addition, the color density is the same, and it has been recognized that color unevenness occurs between the front and back when the entire screen is displayed in a single color. This problem becomes more noticeable as the screen becomes larger. Such luminance, color density, and hue changes are performed for each fine area of the display screen using characteristics opposite to the characteristics of luminance and color displacement shown in FIGS. 2 (a) and 2 (b). If the hue is corrected, it is possible to display a screen with almost uniform image quality even when the display screen is viewed obliquely.

  Ideally, it is conceivable to prepare correction values for luminance, color density, and hue in increments of 0.1 degrees of the line-of-sight angle. However, this increases the amount of data in the correction value table. Therefore, as shown in FIG. 4, in order to correct the viewing angle characteristics, the correction values are quantized for luminance, color density, and hue, respectively, and representative line-of-sight angles of 5 °, 10 °, 15 °, 20 °, Numerical values obtained corresponding to 25 °, ... are stored in the ROM 4 as a table. On the other hand, based on the remote control signal received by the remote control light receiving unit 1, the user position detection unit 2 calculates the angle of each line of sight at the four edges of the display screen in the horizontal direction and the vertical direction as the user viewpoint position information. To do. Therefore, the control unit 3 substitutes the line-of-sight angle calculated by the user position detection unit 2 into the above equation (1), and calculates the line-of-sight angle of each area obtained by dividing the display screen into a plurality of parts on the control. FIG. 5 is an example of division in which the display surface of the liquid crystal panel corresponding to the display screen is divided in terms of control.

  Further, the control unit 3 reads out correction values of luminance, color density, and hue corresponding to the line-of-sight angle in 5 ° increments, which is quantized and stored in the ROM 4, and performs interpolation calculation using an interpolation method in FIG. As shown, a correction value according to a smooth correction curve is calculated and applied to the backlight area control unit 7. As described above, the backlight 8 is composed of independent light sources as RGB, and the backlight area control unit 7 corrects the luminance, color density, and hue by the backlight module for each divided area shown in FIG. To do.

  FIGS. 7A and 7B are configuration examples of an LCD, in which an LED (Light Emitting Diode) backlight is disposed on the back surface of a liquid crystal panel and optical sheets. In the “direct type” shown in FIG. 7A, the light emission amount is controlled using RGB LEDs as control units. In the case of a current control type LED, the luminance, color density, and hue can be adjusted by controlling the current values of the RGB LEDs. In the “side edge type” shown in FIG. 7B, RGB LEDs are arranged on the edge of the liquid crystal panel, and the entire display screen is caused to emit light by the light guide plate. If a large number of LEDs are arranged as control units, a light emission amount control region can be created in a matrix.

  When the control unit 3 calculates the gaze angle of each area obtained by dividing the display screen into a plurality of values by substituting the gaze angle calculated by the user position detection unit 2 into the above equation (1), The calculation result is added to the scaling circuit 6. The scaling circuit 6 has a line memory, receives the angle information of the line of sight of each area from the control unit 3, performs horizontal, vertical and diagonal reduction, and geometrically converts the image. Geometric transformation is generally performed using spatial transformation represented by affine transformation. At this time, the relationship between the user's line-of-sight angle and the filter coefficient is stored as a table in a ROM (not shown). In this way, when the geometric distortion is corrected according to the angle at which the user views the display screen from an oblique direction, the user who has viewed the display screen from the oblique direction, as shown in FIG. An image with the same aspect ratio and no geometric distortion as that of the user is displayed. In the present embodiment, luminance, color density, and hue are also corrected in accordance with the angle of the user's line of sight when viewing the display screen from an oblique direction, so that a screen with substantially uniform image quality can be displayed.

  As described above, when the correction of the luminance, the color density and the hue and the correction of the geometric distortion described above are performed based on the angle of the user's line of sight as viewed obliquely with respect to the display screen, the screen is displayed by other users. When viewed from the front, as shown in FIG. 8B, there is a geometric distortion, and the left side of the screen appears bright and the right side of the screen appears dark.

  By the way, the user position detection unit 2, the control unit 3, and the backlight area control unit 7 surrounded by the wavy line A in FIG. 1 can have their respective functions. FIG. 9 is a flowchart showing a specific processing procedure when the CPU is provided with these functions, and the operation will be described in accordance with this flowchart.

  First, in step S101, a remote control signal transmitted from the remote control light receiving unit 1 is received. Subsequently, in step S102, as the viewpoint position information of the user, two horizontal line-of-sight angles and vertical edges at the horizontal edge. The angles of two lines of sight in the vertical direction at the edges are calculated respectively. Next, in step 103, the line-of-sight angle deg of each divided area of the liquid crystal panel divided as shown in FIG. 5 is calculated for each of the horizontal direction and the vertical direction. Next, in step S104, correction value data stored in the ROM 4 is read, and in step S105, correction values for luminance, color density, and hue for each divided area of the liquid crystal panel are calculated by interpolation using interpolation. In step S106, an angle signal of the line of sight of each divided area is output. Next, in step S107, RGB light sources are controlled for each divided area based on the correction value calculated in step S105. With these processes, the functions of the user position detection unit 2, the control unit 3, and the backlight area control unit 7 shown in FIG. 1 can be realized by the CPU.

  As described above, by correcting luminance, color density and hue, and correcting geometric distortion, when the display screen is viewed obliquely, a screen with almost uniform image quality is displayed over the entire display screen. Can do. In addition, when the user faces the display screen, the brightness, color density, and hue are controlled to be almost constant according to the angle of the line of sight with a small value. can get.

  In the above embodiment, the display device is divided for each area divided into a plurality of areas for control so that the luminance, color density, and hue of the entire display screen are substantially constant based on the correction values stored in the ROM 4. Although controlled, it is also possible to control for each pixel displaying an image instead of controlling for each area.

  In the above embodiment, the backlight 8 itself is controlled. However, in a system using a white backlight and a filter, the luminance is corrected by the backlight, the color density and the hue are corrected by the filter, and the display screen is corrected. What is necessary is just to comprise so that a brightness | luminance, a color density, and a hue may become substantially constant.

  In the above embodiment, as means for obtaining the user's viewpoint position information, the remote control signal is received by four PSDs and the incident angle is detected. Instead, the position information is transmitted from the remote control itself. Either a method, a method of detecting a face by mounting a camera on the main body of the television apparatus, or a method of detecting by mounting various sensors on the main body of the television apparatus can be adopted.

  In the above embodiment, the display surface of the liquid crystal panel is divided into both the vertical direction and the horizontal direction for control, and the luminance, color density and hue, and geometric distortion are corrected for each divided area. The image may be divided into only one of the vertical direction and the horizontal direction, and the luminance, color density, hue, and geometric distortion may be corrected for each divided area. Furthermore, not only the luminance, the color density and the hue, and the geometric distortion, but any one or two of them may be corrected.

  In addition, depending on the lighting method of the liquid crystal panel, it may be difficult to correct all of the luminance, color density, and hue. In this case, even if either or both of the luminance and the hue are corrected, the above-mentioned The substantially same effect as that of the embodiment can be obtained.

  The present invention calculates a user's line-of-sight angle for each area or pixel, and calculates a partial correction value for controlling the display device for each area or pixel so that the color attribute of the entire display screen does not change Since the display device is controlled according to this partial correction value, when viewing the display screen from an oblique direction, an image with almost uniform image quality can be displayed over the entire display screen. This is useful for a television apparatus in which a user who has not been viewing can enjoy viewing comfortably.

It is a block diagram which shows schematic structure of one embodiment of this invention. In order to explain the operation of an embodiment of the present invention, it is a diagram showing the relationship between the viewing angle and the luminance when the display screen is viewed obliquely, and the relationship between the viewing angle and the color displacement. It is explanatory drawing which calculates the angle of the visual line of an intermediate part from the angle of the visual line of the edge part of a display screen, in order to demonstrate operation | movement of one embodiment of this invention. It is the table | surface which showed the memory content of ROM which comprises one embodiment of this invention. It is the example of a division | segmentation which divided | segmented the display surface of the liquid crystal panel which comprises one embodiment of this invention on control. It is explanatory drawing which calculates a correction value by the interpolation calculation by the interpolation method in order to demonstrate operation | movement of one embodiment of this invention. It is explanatory drawing which shows the structural example of LCD which comprises one embodiment of this invention. In order to explain the operation of the embodiment of the present invention, it is a specific display example when the display screen is viewed from an oblique direction and when viewed from the front. It is the flowchart which showed the specific process sequence at the time of giving CPU the function which the one part component which comprises one embodiment of this invention has.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Remote control light-receiving part 2 User position detection part 3 Control part 4 ROM
5 Tuner 6 Scaling Circuit 7 Backlight Area Control Unit 8 Backlight 9 LCD Panel

Claims (4)

A display device configured to change a color attribute by independently controlling R, G, and B for each area or each pixel that displays an image on the display screen, the display screen including a plurality of areas; ,
A correction value for storing the correction value for controlling the display device so that the color attribute does not change even if the angle of the line of sight when the display screen is viewed obliquely is stored corresponding to the angle of the representative line of sight Storage means;
Position detecting means for detecting the angle of the viewer's line of sight with respect to the display screen at a plurality of locations at different distances from the viewer;
The angle of the viewer's line of sight is calculated for each area or each pixel based on the detection value of the position detection means, and the entire display screen is calculated based on the correction value stored in the correction value storage means. Partial correction value calculating means for calculating a partial correction value for controlling the display device for each area or for each pixel so that the color attribute does not change;
Control means for controlling the display device according to the calculated partial correction value;
A television device provided.   The television apparatus according to claim 1, further comprising a keystone correction unit that performs keystone correction based on an angle of the line of sight of the viewer for each area or each pixel calculated by the partial correction value calculation unit.   The television apparatus according to claim 1 or 2, wherein the correction value stored in the correction value storage means is a value based on data obtained by measuring characteristics of the display device in advance.   The television apparatus according to claim 1, wherein the partial correction value calculation unit calculates the partial correction value by interpolation calculation with respect to the correction value stored in the correction value storage unit.

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