JP2009271401A - Image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce significant luminance change during reproduction of moving image, to increase brightness in a specific luminance area, and to reduce consumption power. <P>SOLUTION: A display device has a luminance control curve, which controls luminance relative to an input video signal and is characterized by decreasing luminance gradually while having several appropriate areas for stabilizing the luminance. Obtaining stable area for display luminance makes it possible to reduce trouble caused by a luminance change, to maintain brightness for a specific video and to reduce consumption power. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a display device that adjusts display luminance in accordance with an input signal.

  In recent years, television receivers used in ordinary homes have been replaced with cathode ray tube displays, and flat flat panel displays such as liquid crystal display devices and plasma display devices have become widespread. Flat panel displays are becoming brighter due to improved device performance. However, increasing the brightness of the display device increases the visibility, but causes fatigue due to glare and eye fatigue.

  For these reasons, a method is generally employed in which a light receiving element for measuring brightness is mounted on a display device, and the display brightness of the screen is adjusted in accordance with the surrounding brightness environment. When the periphery is dark, the display brightness is adjusted to be low, and when it is bright, the display brightness is adjusted to be high. As a result, it is possible to suppress glare in a dark environment and to improve visibility in a bright environment.

  Further, depending on the light emitting area, a person may feel glare or darkness even at the same display luminance. For this reason, a display device that is easy for the viewer to view or feels desirable should adjust the display brightness not only by the surrounding brightness environment but also by a video signal such as a display area.

  For example, in a conventional display device, the viewer performs the viewer condition setting on the display device by a screen setting corresponding to age or a camera image, etc. The display brightness is adjusted according to the average brightness of the image, and the difference in the visual function with respect to the feeling of brightness is automatically compensated. (For example, Patent Document 1)

JP 2007-279405 (first term, FIG. 1)

  The display device disclosed in Patent Document 1 has an average display luminance (of a liquid crystal display device) based on human visual characteristics in the configuration shown in FIG. 8 with respect to an input average luminance level (APL: Average Picture Level). In this case, the backlight is controlled. For this reason, as shown in FIG. 9, the display luminance characteristics with respect to the average luminance level are controlled by lowering the display luminance in order to reduce glare when the average luminance level increases.

  However, when control is performed to lower the display brightness as the average brightness level of the video increases, the brightness of the viewer may change when the video has a high average brightness level or the area of the high brightness area in the image is large. You may notice and feel unnatural.

  When there are scenes that change violently, it is difficult to notice brightness changes because there is no comparison of brightness changes. In a scene such as panning where the brightness changes slowly, the brightness changes.

  For example, as shown in the control characteristic of the display brightness with respect to the average brightness level in FIG. 9, when the display brightness is lowered as the average brightness level is increased, 50% or more frequently found in variety programs and the like is the high brightness level region. In such a video, there may be a video with a large white display area, and if a white luminance change occurs, it may appear as a malfunction.

  Further, power consumption can be reduced by reducing display luminance. For example, if the luminance is lowered while maintaining the inclination of the display luminance control line with respect to the conventional average luminance level in order to reduce the power consumption, the display luminance may be excessively lowered in a region where the average luminance is high. When the display luminance is controlled with respect to the average luminance level as shown in FIG. 10A, darkness is felt particularly when the average luminance level is high.

  On the other hand, as shown in FIG. 10B, when the display luminance is lowered at a constant ratio, the darkness of the image is suppressed and the power consumption can be reduced. Further, since the display luminance change with respect to the average luminance level is reduced, the problem can be reduced. However, the peak luminance is excessively lowered in a scene with a low average luminance level, which causes a problem that the contrast is lowered.

  Therefore, the present invention has been made in view of the above-mentioned problems, and as a method for controlling display luminance at the average luminance level of an input video signal, the luminance change in a specific average luminance region is made constant or the amount of change is made small. Accordingly, an object of the present invention is to provide a display device that does not cause image quality deterioration such as a viewer noticing a change in luminance, being too dark, or reducing contrast.

  A display device, a video signal input unit, an average luminance level calculation unit that calculates an average luminance level of the video signal input from the video signal input unit, and a display luminance control that controls display luminance according to the average luminance level And a display device driving unit that drives the display device based on an output from the display luminance control unit, wherein the display luminance control unit falls within a specific average luminance level range. On the other hand, an image display apparatus that controls a display device driving unit so as not to change display luminance is provided.

  A display device, a video signal input unit, an average luminance level calculation unit that calculates an average luminance level of the video signal input from the video signal input unit, and a display luminance control that controls display luminance according to the average luminance level And a display device driving unit that drives the display device based on an output from the display luminance control unit, wherein the display luminance control unit falls within a specific average luminance level range. On the other hand, an image display apparatus is provided that controls a display device driving unit so that a change in display luminance with respect to a change in average luminance level is sufficiently reduced.

  According to the image display apparatus of the present invention, it is possible to adjust the display brightness of various videos and images to brightness that is not dazzling and not dark according to the brightness feature amount of the video.

  FIG. 1 is a block diagram showing a configuration of an image display apparatus according to the present invention. The image display apparatus includes a video signal input unit 10, a video processing unit 11, an image feature amount calculation unit 20 including an average luminance calculation unit 21, a display luminance control unit 30, a display device drive unit 40, a brightness sensor 51, and viewing. A viewing environment control unit 50 including a viewer information input unit 52 for inputting person information and a display device 60.

  The video signal input unit 10 is a video signal input device for inputting an external video signal such as a tuner, and is, for example, a tuner or a decoder. The video processing unit 11 performs signal processing on the video signal input from the video signal input unit 10, and outputs the processed video to the display luminance control unit 30 after processing.

  In the video feature amount calculation unit 20, the average luminance level of one frame or a plurality of frames of the video and image input by the average luminance calculation unit 21 is calculated. This information is output to the display brightness control unit 30.

  In the viewing environment control unit 50, the brightness sensor 51 is used to measure a brightness environment such as illumination in which the display device is viewed. In the viewer information input unit 52, information such as the viewer's age, viewing distance, and visual acuity is manually input from the remote control, or automatically from the video information of the monitor captured by a camera (not shown). The age is discriminated and input. These pieces of information are output to the display luminance control unit 30.

  The display brightness control unit 30 inputs or measures the feature amount calculated by the video feature amount calculation unit 20 and the viewing environment control unit 50 with respect to the input video signal processed by the video processing unit 11. Luminance setting information such as maximum display luminance is determined from the viewing environment information, and data is output to the display device drive unit 40.

  The display device driving unit 40 drives the display device 60 based on the luminance setting information output by the display luminance control unit 30.

As shown in FIG. 2, the video feature amount calculation unit 20 may be arranged behind the video processing unit 11. In this case, when the luminance information is processed by the video processing unit 11, the average luminance level can be calculated more accurately and reflected in the display luminance control. However, it is necessary to perform processing for matching the video output timing and the feature information output timing from the video feature amount calculation unit 20 by a method such as storing the video signal output from the video processing unit 11 in a memory.
Details of the brightness control method of the present invention will be described below with reference to the drawings.

  The display brightness control unit 30 performs display brightness control for the average brightness level shown in FIG. That is, the display brightness is set to a constant value for a certain range of average brightness levels. The display luminance control unit 30 has a numerical table so that the display luminance can be output when an average luminance level is given.

  The average luminance level shown in this table is an average luminance level from a video input from the video signal input unit 10 or one frame of an image signal, or from the current frame to a plurality of frames before. This is calculated by the average luminance calculation unit 21 and input to the display luminance calculation unit 30. The display luminance value on the vertical axis represents the luminance of the backlight in the case of a liquid crystal display device, and the maximum luminance value in the case of a self-luminous display device such as an organic EL. In the case of a self-luminous display device, the luminance of gradation is determined in accordance with the maximum luminance.

  The feature of this display brightness control is that the display brightness is lowered stepwise as the average brightness level increases. As shown in FIGS. 5A and 5B, the method of lowering the average luminance level with a linear function or the method of lowering with a quadratic function always changes the display luminance with respect to the change in the average luminance level of the video. Has occurred. Therefore, in the case of an image in which the average luminance level continuously changes, such as panning, the viewer may know the change in display luminance. In addition, in the linear function-like luminance control, the display luminance is excessively lowered for an image with a high average luminance level, and the darkness is felt.

  Therefore, as shown in FIG. 3, by changing the display luminance with respect to the average luminance level to a step-like shape in which the luminance is constant in a specific region, a high luminance level region in which the display luminance change is conspicuous or an image By setting a region where the luminance is not changed in the middle luminance level region where it is desired to stabilize the brightness, it is possible to maintain the feeling of brightness and reduce the problem of luminance change.

  For example, assuming that the maximum luminance level is 100%, in a dark image such as a movie, the average luminance level changes at about 10% to 30%. In a slightly bright scene such as a studio or variety, the rate changes between approximately 30% and 70%.

  Therefore, the point a1 shown in FIG. 3 is set to 30%, and the luminance change in the dark video up to 30% is stabilized. Next, the point of b1 is set to 50%, and control is performed so far that the luminance is lowered. Furthermore, c1 is set to 70%, the luminance is stabilized between 50% and 70%, and the luminance is not changed in a bright scene. Also, by setting the point of d1 to 80% and reducing the brightness so far, for a mean brightness of 80% or more, by creating a constant brightness area, the brightness change on a screen with many whites such as commercials To stabilize.

  FIG. 6 shows a comparison between the present invention and a conventional system. As shown by the one-dot chain line in FIG. 6, it is possible to control the luminance more effectively than the simple luminance control that lowers the display luminance with respect to the conventional average luminance level.

  For example, in the case of this example, since the display luminance change at the average luminance level from b1 to c1 is stable, no luminance change occurs in the scene during this period. As shown in FIG. 6, at the point c1, the display brightness is higher in the present system than in the conventional system indicated by the alternate long and short dash line. In this way, the display luminance is increased at a high average luminance level, and the brightness is also improved.

  In general variety video, since the average luminance level is concentrated around 50%, the luminance curve according to the variety is selected by making this level a stable luminance region, and the luminance is further stabilized. be able to.

  Further, in the region where the luminance is stabilized, the same effect can be obtained by making the display luminance change with respect to the average luminance level smaller than the other regions as shown in FIG. 4 instead of making the display luminance constant. .

  For example, the average luminance level shown in this example is a luminance level range from 0 to a1, a luminance level range from b1 to c1, and a luminance change amount greater than or equal to d1, and the other a1 to b1 and c1 to d1 The luminance change amount is smaller than the luminance change amount.

  In addition, in these luminance control methods, when determining the values of b1 and c1 as the range of the average luminance level stable region, the user can arbitrarily determine the range. For example, in a region where the luminance continuously changes such as panning, It is also possible to automatically adjust the values of b1 and c1 so as not to cause a luminance change, and to reduce the stable region in a scene with a large change. As a result, it is possible to suppress power consumption by adjusting the luminance due to inconvenience due to luminance change.

  In this luminance control, the illumination information of the viewing environment output from the brightness sensor 51 and the viewer information output from the viewer information 52 are controlled by the viewing environment control unit 50 for display brightness control. And is transformed based on this information.

  For example, if the brightness sensor 51 determines that the illumination condition of the display device is high, the entire brightness control curve is increased by a desired ratio or a fixed amount, and if it is determined to be low, the entire control control curve is determined by the desired ratio or Reduced by a certain amount. Also, if the viewer information is close by the viewer information, the entire brightness control curve is lowered by a desired ratio or a fixed amount, and if it is determined that the distance is far, the entire brightness control curve is decreased by a desired ratio or a fixed amount. Raised.

  In addition, the inclination can be changed according to the age group being viewed and characteristics such as visual acuity. For example, in the case of a young person who easily feels the glare as shown in FIG. 7A, the brightness of the stable region is lowered to reduce the glare of the image, and the display brightness is further increased as shown in FIG. 7B. When lowering, it is also possible to move points a to d which are inflection points.

  In this way, display brightness is controlled based on the average brightness level of images and images, and the brightness change at a specific average brightness level is stabilized or reduced to reduce glare, while maintaining brightness without being too dark. The luminance change that occurs when the luminance is reduced can be reduced.

  In addition, by dynamically controlling this constant value portion according to the change in the average luminance level, the luminance does not change in an image having a certain amount of bright area and number of pixels in the video signal. By making the area, it is also possible to reduce the luminance change.

  For example, if the video signal has a bright area with a certain amount or more, or the image has more than a certain number of pixels, the image does not change in luminance with respect to the average luminance level, or the inclination is By increasing the range to be reduced, it is possible to reduce a problem with respect to the luminance change, and when the average luminance level changes greatly, it is also possible to dynamically control to change the luminance with respect to the average luminance level.

It is a block diagram which shows the image display apparatus which concerns on this invention. It is another block diagram which shows the image display apparatus which concerns on this invention. It is a graph which shows the table showing the display luminance value with respect to an average luminance level at the time of eliminating the luminance change of a specific area based on this invention. It is a graph which shows the table showing the display luminance value with respect to an average luminance level at the time of reducing the luminance change of a specific area | region based on this invention. It is a graph which shows the example of the table showing the display luminance value with respect to an average luminance level. (A) In case of one-dimensional display luminance control (b) In case of two-dimensional display luminance control It is the figure which showed the comparison with the graph which shows the table showing the display luminance value with respect to the average luminance level which concerns on this invention, and the conventional graph. Table representing display luminance value with respect to average luminance level according to difference in age according to the present invention (a) Luminance control characteristic in which intermediate luminance area is changed according to age group (b) Overall luminance control is changed according to age group Brightness control characteristics It is a figure which shows the block diagram of a prior art example. It is the figure which showed the graph which shows the table showing the display luminance value with respect to the conventional general average luminance level. It is a graph showing the display luminance value with respect to the general average luminance level when reducing power consumption.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image | video signal input part 11 Image | video process part 20 Image | video characteristic calculating part 21 Average brightness | luminance level calculating part 30 Display brightness | luminance control part 40 Display device drive part 50 Viewing environment control part 51 Brightness sensor 52 Viewer information input part

Claims (3)

A display device;
A video signal input section;
An average luminance level calculation unit for calculating an average luminance level of the video signal input from the video signal input unit;
A display brightness control unit that controls display brightness in accordance with the average brightness level;
An image display device comprising: a display device drive unit that drives the display device based on an output from the display brightness control unit;
The display luminance control unit controls the display device driving unit so as not to change the display luminance with respect to a range of a specific average luminance level. A display device;
A video signal input section;
An average luminance level calculation unit for calculating an average luminance level of the video signal input from the video signal input unit;
A display brightness control unit that controls display brightness in accordance with the average brightness level;
An image display device comprising: a display device drive unit that drives the display device based on an output from the display brightness control unit;
The display luminance control unit controls the display device driving unit so that a change in display luminance with respect to a change in average luminance level is sufficiently small with respect to a specific average luminance level range. .   3. The image display according to claim 1, wherein the range of the specific average luminance level is a region having a low average luminance level, a region having a high average luminance level, and a region having a medium average luminance level. apparatus.

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