JP4646945B2 - Video display device and video display device control method - Google Patents

Description

  The present invention relates to a video display device that displays video on a display unit, and a control method for the video display device, specifically, a function capable of detecting the brightness of the surrounding environment in which the video display device is installed. The present invention relates to a video display apparatus having the above and a method for controlling the video display apparatus.

  Some recent video display devices such as digital televisions are provided with an external light sensor. The outside light sensor detects the illuminance of the environment by sunlight entering through a window, indoor illumination light, or the like in a room where an image display device is installed. By performing image quality adjustment suitable for the environment according to the detected illuminance, it is possible to achieve video display that is easy for the viewer to see, power consumption suppression, and the like.

Further, Patent Document 1 discloses a technique for suppressing erroneous detection of the brightness of the external environment by reflected light generated when a video display device displays a video such as a moving image or a still image. The display device disclosed in Patent Literature 1 is premised on a display device that detects external light and executes image processing, similar to that described in Patent Literature 1. When the display displays an image, the display itself becomes a light source, and the light is reflected on a wall, ceiling, object, or the like. Patent Document 1 discloses a technique for solving the problem that the reflected light is incident on an external light sensor so that the illuminance of the environment where the display device is installed fluctuates due to the reflected light and correct external light cannot be detected. Disclosure.
JP 2002-351445 A

  Here, the technique disclosed in Patent Document 1 will be described. First, Embodiment 1 of this document discloses that the correction amount of contrast or brightness is adjusted using the average luminance of video and the illuminance detected by a brightness detection means (external light sensor). The straight line (a) in FIG. 2 of Patent Document 1 shows the degree of change in the contrast correction amount when the luminance level is lower than the predetermined luminance level, that is, in the case of a dark image. The straight line (b) indicates the degree of change in the contrast correction amount when the luminance level is higher than the predetermined luminance level, that is, in the case of a bright video. The ambient brightness on the horizontal axis in FIG. 2 is brightness composed of ambient light such as illumination and reflected light. Further, the correction amount works in the direction of lowering contrast and luminance as the amount increases.

  Subsequently, in Embodiment 2 of this document, the brightness of the video signal is corrected using the illuminance detected by the brightness detection unit and the luminance detected by the luminance detection unit. Specifically, when the illuminance of the ambient light is constant, the illuminance detected by the outside light sensor has a correlation with the luminance change of the video signal by being affected by the incident of the reflected light from the display image as the light source. It is described. Therefore, the correlation component with the luminance change of the video signal is removed from the illuminance detected by the external light sensor using the means for detecting the luminance change and the means for detecting the illuminance change. Then, brightness and contrast correction values are obtained based on the illuminance detection result from which the influence of the reflected light is removed, and output to the brightness / contrast control means. According to these techniques, Patent Document 1 describes that stable image quality correction that is not affected by reflected light using a display image as a light source can be performed.

  However, the technique described in Patent Document 1 described above cannot solve the following problems.

  For example, if the illumination is dimmed in a room with an element that reflects light and a DTV is viewed, the light emitted from the DTV panel is reflected in the room so that the entire room changes in the brightness of the image. Flickers accordingly. In particular, when a video that repeats a bright video scene and a dark video scene in a short time is displayed, the brightness of the room fluctuates in a short time. When such a phenomenon occurs, the viewer may feel uncomfortable.

  In the technique disclosed as Embodiment 1 of Patent Document 1, when a dark video scene is displayed in a dark room, the degree of brightness around the display device is reduced due to a small amount of reflected light, resulting in a correction amount. Becomes larger. That is, it is a process for reducing contrast and brightness. On the other hand, when a bright video scene is displayed, the reflected light increases, so the degree of ambient brightness also increases, and as a result, the correction amount decreases. That is, the process does not correct contrast and brightness. Therefore, when a video image that repeats a bright video scene and a dark video scene in a short time is displayed, the bright video scene is displayed at a high brightness without correction, but the dark video scene reduces the brightness. Display brightness difference increases. When the control for increasing the display luminance difference of the video is performed, naturally, the change in brightness due to the reflection in the room is more emphasized, which may increase the viewer's discomfort.

  The technique disclosed as the second embodiment removes the illuminance corresponding to the reflected light from the illuminance incident on the sensor. As a result, the brightness of the room without the influence of the reflected light as shown in the graph (2) of FIG. 4 is obtained, this brightness is set on the horizontal axis of the graph of FIG. 2, and the brightness and contrast correction values are set. Looking for.

  However, since the configuration of the second embodiment ignores the component of the reflected light, the luminance level variation of the video signal is used for adjusting the correction amount without considering the degree of reflection at all. As a result, the correction amount is reduced for a video scene with high luminance, and the correction amount is increased for a video scene with low luminance. That is, the situation is the same as in the first embodiment, and the brightness change due to the reflection in the room is emphasized.

  The present invention has been made to solve the above problems, and can reduce viewer discomfort caused by fluctuations in indoor brightness caused by reflection of light emitted from a video display device. An object of the present invention is to provide a video display device and a control method for the video display device.

In order to achieve the above object, a video display device of the present invention is a video display device including a display unit that displays a video signal and an external light detection unit that detects the illuminance of external light around the display unit. The acquisition means for acquiring the detected illuminance value detected by the external light detection section, the calculation means for calculating the average luminance value for each frame data of the video signal displayed on the display section, and the calculation means Display means for displaying a low-brightness video signal whose average brightness value is low and a high-brightness video signal whose brightness is high on the display unit, and the low-brightness video signal and the high-brightness video signal displayed by the display means Reflected light illuminance generated by displaying an image on the display unit using the detected illuminance value acquired by the acquisition means and the average luminance value of the low luminance video signal and the high luminance video signal. Decide Determining means for, using said reflected light intensity and said average luminance value, and a control means for performing correction control for reducing the display brightness of the video signal to be displayed on the display unit, wherein, When the average luminance value is larger than the first threshold and the reflected light illuminance is large, the display luminance reduction degree is larger than the display luminance reduction degree when the reflected light illuminance is small. Thus, the correction control is executed as described above.

In order to achieve the above object, a method for controlling a video display device of the present invention includes a display unit that displays a video signal and an external light detection unit that detects the illuminance of external light around the display unit. A method of controlling a video display device, wherein an acquisition step of acquiring an illuminance detection value detected by the external light detection unit, and a calculation for calculating an average luminance value for each frame data of a video signal displayed on the display unit A display step for displaying on the display unit a low-brightness video signal in which the average luminance value calculated in the calculation step is low and a high-brightness video signal in which the average luminance value is high, and the low luminance by the display step An image is displayed on the display unit using the illuminance detection value acquired in the acquisition step when the video signal and the high luminance video signal are respectively displayed, and the average luminance value of the low luminance video signal and the high luminance video signal. Display Yes and a control step of executing a correction control and determining step of determining, using said reflected light intensity and said average luminance value, reduces the display brightness of the video signal to be displayed on said display unit the reflected light intensity caused by the In the control step, the display luminance is reduced when the average luminance value is larger than the first threshold value and the reflected light illuminance is large, and the display luminance when the reflected light illuminance is small. The correction control is executed so as to be larger than the reduction degree.

  As described above, according to the video display device and the video display device control method of the present invention, viewer discomfort caused by fluctuations in indoor brightness caused by reflection of light emitted from the video display device. Can be reduced.

Example 1
The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the functions, shapes, relative arrangements, and the like of the components described in the present embodiment and other embodiments described later limit the scope of the present invention only to those unless otherwise specified. It is not intended. Further, the functions and shapes of the components and components once described in the following description are assumed to be the same as those in the initial description unless otherwise described.

  FIG. 1 is a block diagram showing a configuration of a video display device 100 of the present invention. The input video signal displayed on the video display device 100 is input to the luminance gain control circuit 101 and the APL calculation unit 103, respectively.

  The luminance gain control circuit 101 is a control circuit that operates as correction means for correcting the gain of the luminance value of the input video signal. The video signal whose luminance is corrected by the luminance gain control circuit 101 is output to the display unit 102. The gain correction of the luminance value of the video signal executed by the luminance gain control circuit 101 will be described later.

  A display unit 102 as a display unit is a display for displaying a video signal whose luminance gain is corrected by the luminance gain control circuit 101. In the present invention, any type of display may be used, but in the present embodiment, description will be made assuming a SED (Surface-Conduction Electron-Emitter Display) which is a self-luminous display. .

  An APL calculation unit 103 that is an example of an average luminance value calculation unit is a calculation unit that measures an APL (Average Picture Level) of an input video signal. APL corresponds to the average luminance value in the frame data of the input video signal, and corresponds to the average value of the luminance values of each pixel constituting the image data constituting one frame of the video signal. The APL calculation unit 103 calculates the APL for each frame of the input video signal, and outputs the calculated APL value (average luminance value) to the reflection amount calculation unit 105 and the first adjustment value generation unit 107 described later.

  The external light sensor 104 serving as an external light detection unit is a sensor that detects the amount of light (illuminance) that strikes the video display device in a viewing environment where the video display device 100 is installed. The external light sensor 104 outputs the detected illuminance detection value to the reflection amount calculation unit 105. Note that the illuminance detected by the external light sensor 104 is determined by illuminance components in ambient light such as illumination in the viewing environment and sunlight, and display light generated by displaying an image on the display unit 102 around the image display device 100. And an illuminance component (reflection amount) of the reflected light reflected by the object.

  The reflection amount calculation unit 105 is an acquisition unit that acquires the illuminance detection value input from the external light sensor 104, and at the same time, the reflection included in the illuminance detection value using the APL calculation value input from the APL calculation unit 103. It operates as a determination means for determining the illuminance component of light.

  FIG. 2 is a graph showing the concept of the reflection amount calculation process executed by the reflection amount calculation unit 105. The horizontal axis is the APL calculation value, and the vertical axis is the illuminance detection value detected by the external light sensor 104. The reflection amount calculation unit 105 obtains the illuminance component amount in the reflected light from the difference between the illuminance detection value when the APL calculation value is low and the illuminance detection value when the APL calculation value is high.

  As described above, the display light generated by displaying the video on the display unit 102 is reflected on the wall, ceiling, floor, installation object, etc. in the room where the video display device 102 is installed, and the external light sensor 104. Is input. That is, the illuminance detection value detected by the external light sensor 104 includes the illuminance component in the reflected light in addition to the illuminance component in the ambient light. When the APL calculation value of the input video signal is sufficiently low, the amount of display light generated from the display unit 102 is small, resulting in less reflected light. Therefore, in this case, the illuminance detection value output from the external light sensor 104 to the reflection amount calculation unit 105 is a value close to the illuminance of the ambient light in the viewing environment (point I1 in FIG. 2). On the other hand, when the APL calculation value of the input video signal is sufficiently high, the amount of display light generated from the display unit 102 is large, resulting in an increase in reflected light. Therefore, in this case, the illuminance detection value output from the external light sensor 104 to the reflection amount calculation unit 105 is the total value of the illuminance of the ambient light and the illuminance of the reflected light in the viewing environment (point I2 in FIG. 2).

  In other words, the reflection amount calculation unit 105 can subtract the illuminance detection value at the point I1 from the illuminance detection value at the point I2, thereby removing the illuminance of the ambient light in the viewing environment and determining the illuminance component due to the reflected light. .

  In the present embodiment, the determination of the illuminance component by the reflected light performed by the reflection amount calculation unit 105 assumes a case where the reflected light in the installation environment of the video display device 100 does not change. Therefore, the determination of the amount of reflection (the illuminance of the reflected light) is executed by the following procedure, for example. First, a black image is displayed immediately after the video display device 100 is powered on. Then, the detected illuminance value at this time is acquired from the external light sensor 104. Thereafter, an image that shows a high APL value is displayed, and the detected illuminance value at this time is acquired from the external light sensor 104. By obtaining the difference between the detected illuminance values, the illuminance component of the reflected light in the environment where the video display device 100 is installed can be determined.

  The calculated value of the reflection amount determined by the reflection amount calculation unit 105 is output to the second adjustment value generation unit 108 described later.

  Next, the first adjustment value generation unit 107 in FIG. 1 will be described. The first adjustment value generation unit 107 calculates a first adjustment value used for processing in the luminance gain control value generation unit 106 described later for each APL value, that is, for each frame data of the video signal.

  FIG. 3 is a graph showing the concept of the first adjustment value generation process executed by the first adjustment value generation unit 107. The horizontal axis of the graph is the APL value, and the vertical axis is the output value of the first adjustment value generation unit 107. In the present embodiment, the range of the first adjustment value is a value from −1 to 0. The first adjustment value generation unit 107 outputs 0 as the first adjustment value if the APL value is equal to or less than the predetermined threshold value S1. When the APL value exceeds a predetermined threshold value S1, a value smaller than 0 is output, and a value that causes the first adjustment value to approach −1 as the APL value increases is derived. That is, when the APL value increases beyond the threshold value S1, the reflected light increases, so a parameter for reducing the peak luminance of the video is output. The first adjustment value (parameter) generated by the first adjustment value generation unit 107 is output to the luminance gain control value generation unit 106.

  Note that the first adjustment value generation unit 107 may derive the first adjustment value using data in a predetermined table format. Further, the first adjustment value may be derived by calculation using a function corresponding to the graph shown in FIG.

  Next, the second adjustment value generation process executed by the second adjustment value generation unit 108 will be described. FIG. 4 is a graph showing the concept of the second adjustment value generation process executed by the second adjustment value generation unit 108. The horizontal axis of the graph is the reflection amount calculated by the reflection amount calculation unit 105, and the vertical axis is the output value of the second adjustment value generation unit 108.

  The second adjustment value generation unit 108 causes the luminance gain control value generation unit 106 to generate a second adjustment value for changing the slope of the portion where the APL value exceeds the threshold value S1. In FIG. 4, when the amount of reflection (the illuminance of the reflected light) is equal to or smaller than a predetermined threshold S2, the second adjustment value generation unit 108 outputs 1 as a parameter. When the reflection amount exceeds the predetermined threshold S2, the second adjustment value generation unit 108 outputs a value larger than 1 as a parameter. Note that the amount of reflection set as the predetermined threshold S2 is preferably a value corresponding to the illuminance of reflected light that does not make the viewer feel uncomfortable. Therefore, when the reflection amount is larger than the threshold value S2, the luminance of the video signal can be reduced. The second adjustment value (parameter) generated by the second adjustment value generation unit 108 is output to the luminance gain control value generation unit 106.

  Note that the second adjustment value generation unit 108 may derive the second adjustment value using data in a predetermined table format. Further, the second adjustment value may be derived by calculation using a function corresponding to the graph shown in FIG.

  Next, the luminance gain control value generation unit 106 will be described. The luminance gain control value generation unit 106 is configured to generate a luminance gain based on the output (first adjustment value) from the first adjustment value generation unit 107 and the output (second adjustment value) from the second adjustment value generation unit 108. A luminance gain control value that is a correction value used in the control circuit 101 is generated.

  FIG. 5 is a graph showing the concept of the luminance gain control value generation process executed by the luminance gain control value generation unit 106. The horizontal axis corresponds to the APL value calculated by the APL calculation unit 103, and the vertical axis corresponds to the luminance gain control value output from the luminance gain control value generation unit 106. The luminance gain control value is obtained by multiplying the first adjustment value output from the first adjustment value generation unit 107 by the second adjustment value output from the second adjustment value generation unit 108 and then adding 1. .

  As described above, the second adjustment value is 1 when the reflection amount is equal to or less than the threshold value S2. Therefore, the second adjustment value (value is 1) is multiplied by the first adjustment value, and the luminance gain control value has the same characteristics as the output of the first adjustment value. That is, the portion below the threshold S1 in FIG. 5 is obtained by adding 1 to the result (value is 0) obtained by multiplying the portion below the threshold S1 in FIG. 3 by 1. That is, the value is 1. Further, the part exceeding the threshold value S1 in FIG. 5 is a value obtained by adding 1 to the result obtained by multiplying the part exceeding the threshold value S1 in FIG.

  A line 501 in FIG. 5 is a line indicating the value of the luminance gain control value when the APL value increases beyond the threshold value S1 when the reflection amount is small. That is, the line 501 is a line segment corresponding to the case where the reflection amount is equal to or less than the threshold value S2. In this case, since the second adjustment value is always 1, the result of adding 1 to the multiplication result of the first adjustment value and the second adjustment value is equal to the value obtained by adding 1 to the line segment in FIG.

  On the other hand, when the reflection amount exceeds the threshold value S2 and the APL value exceeds the threshold value S1, the luminance gain control value becomes smaller than 1. A line 502 in FIG. 5 is a line indicating the value of the luminance gain control value when the reflection amount is larger than the state of the line 501, that is, when the APL value increases beyond the threshold value S 1 when the reflection amount is larger than the threshold value S 2. is there. In this case, the luminance gain control value is smaller than that of the line 501. That is, when the APL value exceeds the threshold value S1, the luminance gain control value decreases as the reflection amount increases beyond the threshold value S2.

  The luminance gain control value generated by the luminance gain control value generation unit 106 is output to the luminance gain control circuit 101. Note that the luminance gain control value generation unit 106 may derive the luminance gain control value using data in a predetermined table format. Further, the luminance gain control value may be derived by calculation using a function corresponding to the graph shown in FIG.

  Next, the luminance gain control circuit 101 will be described. The luminance gain control circuit 101 uses the output from the luminance gain control value generation unit 106 to correct the luminance gain for the input video signal. The correction by the luminance gain control circuit 101 is a process for reducing the display luminance of the video displayed on the screen. In this embodiment, since an SED that is a self-luminous display is assumed, the luminance gain of the video signal is adjusted so as to reduce the display luminance of the video displayed on the display unit.

  FIG. 6 is a graph showing the correction level of the peak luminance when the luminance gain of the input video signal is corrected by the luminance gain control circuit 101. The horizontal axis corresponds to the APL value calculated by the APL calculation unit 103, and the vertical axis corresponds to the peak luminance level of the video displayed on the display unit 102. That is, FIG. 6 is a diagram showing the relationship between the APL of the video signal corrected by the luminance gain control circuit 101 and the peak luminance level.

  A line 601 in FIG. 6 indicates the correction level of the peak luminance level when the APL value increases beyond the threshold value S1 when the reflection amount is small. That is, this corresponds to the peak luminance level corrected by the luminance gain control value indicated by the line 501 in FIG. A line 602 indicates the correction level of the peak luminance level when the reflection amount is larger than the state of the line 601 and the APL value increases beyond the threshold value S1. That is, it corresponds to the peak luminance level corrected by the luminance gain control value indicated by the line 502 in FIG. As described above, when the APL value is equal to or smaller than the threshold value S1, the luminance gain control value shown in FIG. 5 is 1, so that the peak luminance level is not corrected. However, in the case where the APL value exceeds the threshold value S1, the luminance gain control value changes, so that correction for reducing the peak luminance level works accordingly. The correction degree is based on the luminance gain control value generated from the second adjustment value corresponding to the reflection amount and the first adjustment value corresponding to APL.

  As shown in FIG. 6, when the APL of the input video signal is high, an environment where the illuminance of the reflected light reflected by the screen display is large has a degree of correction that lowers the peak luminance level than an environment where the illuminance of the reflected light is small. Strengthen. By reducing the peak luminance level, the display luminance of the video is reduced. As a result, the amount of light emitted from the display screen is reduced, and the discomfort during viewing due to the reflected light reflected by the light emitted from the display screen can be reduced.

  Further, in this embodiment, even in an environment where the illuminance of the reflected light is large, when the APL of the input video signal is low, the peak luminance level is not lowered, so that it is possible to avoid the image becoming darker than necessary. Is possible.

  Next, FIG. 7 shows a processing flow in the present embodiment. This flow shows the operation of each unit described above as a processing procedure. Note that, among the functional units constituting the video display device 100, all processes other than the operations in the above-described units are executed by a control unit (not shown) such as a CPU that controls the video display device 100.

  First, in step S701, the control unit determines whether or not the video display device 100 is powered on. If the power is turned on, the process proceeds to step S702.

  In step S <b> 702, the control unit controls the display unit 102 to display a low-luminance video. Thereafter, in step S703, the external light sensor 104 detects the illuminance when displaying a low-luminance video. The illuminance detected by the external light sensor 104 is output to the reflection amount calculation unit 105. In addition, the APL calculation unit 103 outputs the APL value at this time to the reflection amount calculation unit 105.

  Note that the low-luminance video may be a black screen display as described above, and it is not always necessary to display any video. That is, equivalent illuminance can be obtained by detecting ambient light in a state where nothing is displayed on the screen.

  In step S704, the control unit controls the display unit 102 to display a high-luminance video. Thereafter, in step S705, the ambient light sensor 104 detects the illuminance when displaying a high-luminance video. The illuminance detected by the external light sensor 104 is output to the reflection amount calculation unit 105. In addition, the APL calculation unit 103 outputs the APL value at this time to the reflection amount calculation unit 105.

  After detecting external light during low-luminance video display and external light during high-luminance video display, the process proceeds to step S706, and the amount of reflection in the environment where the video display device is installed is calculated. This calculation is performed by the reflection amount calculation unit 105.

  The reflection amount calculation unit 105 determines the reflection amount from the difference between the APL value and the detected illuminance value at low luminance and the APL value and the detected illuminance value at high luminance. The determined reflection amount value is output to the second adjustment value generation unit 108. Since the method for determining the illuminance (reflection amount) of the reflected light has been described with reference to FIG. 2, description thereof is omitted here.

  In step S707, the second adjustment value generation unit 108 generates a second adjustment value. Since the second adjustment value and generation of the value are as described above, description thereof is omitted. The generated second adjustment value is output to the luminance gain control value generation unit 106.

  Subsequently, in step S708, input of a video signal is started. A video signal composed of a plurality of frame data is input to the luminance gain control circuit 101 and the APL calculation unit 103 in units of frames. In step S709, the APL calculation unit 103 calculates an APL value for each frame data, and outputs the calculated APL value to the first adjustment value generation unit 107.

  In step S <b> 710, the first adjustment value generation unit 107 generates a first adjustment value according to the input APL value as described with reference to FIG. 3 and outputs the first adjustment value to the luminance gain control value generation unit 106.

  In step S711, the luminance gain control value generation unit 106 generates a luminance gain control value from the first adjustment value and the second adjustment value. Note that the video signal to which the luminance gain control value is applied is a video frame for which the APL calculation unit 103 has calculated the APL value. The luminance gain control value generation unit 106 outputs the generated luminance gain control value to the luminance gain control circuit 101.

  In step S712, the luminance gain control circuit 101 executes a process of correcting the luminance gain of the frame data corresponding to the video signal using the input luminance gain control value. Note that the luminance gain correction processing executed by the luminance gain control circuit 101 is the same as that described above, and a description thereof will be omitted.

  While the video signal is input, the processing from step S709 to step S712 is continuously performed for each frame until the power of the video display device 100 is turned off. When it is detected in step S713 that the power of the video display device 100 is turned off, the control unit ends the above processing.

  As described above, according to the present embodiment, it is possible to reduce viewers' discomfort caused by fluctuations in the brightness of the room caused by reflection of light emitted from the video display device 100.

  In this embodiment, based on the luminance gain control value, the luminance gain control circuit 101 executes a process of reducing the peak luminance level when the APL value is a video signal higher than a predetermined threshold S1 among the input video signals. did. However, in a transmissive display that emits a backlight, such as a liquid crystal display, the luminance level of a display image can be lowered by adjusting the amount of light emitted from the backlight. In this case, a value corresponding to the luminance gain in the above-described embodiment may be applied to the adjustment of the light emission amount of the backlight. As described above, the present invention is not limited by the method of adjusting the brightness, and any adjustment method may be adopted as long as the display brightness of the screen when the video is displayed on the display is finally adjusted. May be.

  In this embodiment, the luminance correction degree when the APL value is high is controlled according to the reflection amount. However, even if the amount of reflection is the same, the brightness fluctuation due to reflection is more pronounced when the ambient illumination is low in the viewing environment, such as in the viewing environment, that is, in a dark environment, compared to the bright environment. It becomes. Therefore, as a modification of the present embodiment, the second adjustment value generation unit 107 generates a second adjustment value according to the ratio between the amount of reflection and the illuminance when the APL value is low.

  FIG. 8 is a graph for explaining processing executed by the second adjustment value generation unit 107 in the present modification. In FIG. 8, the horizontal axis represents a value obtained by dividing the reflection amount by the illuminance of the ambient light at the time of low APL. The greater this value, the greater the amount of reflection. By using not only the amount of reflection but also the ambient light illuminance in the installation environment, the degree of correction is increased when the ambient light illuminance is low, and the degree of correction is decreased when the ambient light illuminance is high. can do. Accordingly, it is possible to execute appropriate luminance gain correction processing in cases where the viewer is likely to feel discomfort and cases where the viewer does not feel so much.

(Example 2)
Subsequently, a second embodiment of the present invention will be described. In the first embodiment, the reflection amount is calculated before the input of the video signal, and the luminance gain control value is generated using the second adjustment value obtained from the reflection amount and the first adjustment value obtained from the APL value. Was. On the other hand, this embodiment is intended to periodically calculate the reflection amount and correct the luminance gain with higher accuracy. In particular, as a structural difference from the first embodiment, each unit configured by reference numerals 901 to 905 determines the reflection amount instead of the reflection amount calculation unit 105. That is, these functional units operate as an acquisition unit and a determination unit. The structure of the function part of these codes | symbols is demonstrated below.

  FIG. 9 is a block diagram showing the configuration of the video display apparatus 100 in the second embodiment. Input video signals displayed on the video display device 100 are input to the luminance gain control circuit 101 and the APL calculation unit 103, respectively. In addition, the code | symbol similar to FIG. 1 is attached | subjected to the function part which performs the function similar to Example 1 mentioned above, and description is abbreviate | omitted.

  In this embodiment, the outside light sensor 104 always detects outside light in the environment where the image display device 100 is installed.

  The output of the APL calculation unit 103 is input to the first adjustment value generation unit 107 and the APL determination unit 901. The APL determination unit 901 executes processing for comparing the input APL value with a predetermined threshold value. The APL determination unit 901 compares the APL value with each of the threshold values S3 and S4. These two threshold values have a relationship of S3 <S4. As a result of comparison by the APL determination unit 901, the APL value is held in one of the APL / illuminance holding unit L and the APL / illuminance holding unit H according to the relationship between the two threshold values. When the APL value is between S3 and S4, it is not held in either the APL / illuminance holding unit L or the APL / illuminance holding unit H.

  The APL / illuminance holding unit L902 holds a set of the APL value and the detected illuminance value at that time when the APL value is equal to or less than the threshold value S3 as a result of comparison by the APL determination unit 901. Note that the illuminance detection value is the illuminance of external light detected by the external light sensor 104.

  The APL / illuminance holding unit H903 holds a set of the APL value and the detected illuminance value at that time when the APL value is equal to or greater than the threshold value S4 as a result of comparison by the APL determination unit 901.

  Here, the APL value held by the APL / illuminance holding unit L902 is A1, and the detected illuminance value is B1. The APL value held by the APL / illuminance holding unit H903 is A2, and the detected illuminance value is B2.

  The inclination calculation unit 904 uses a set of the APL value A1 and the detected illuminance value B1 output from the APL / illuminance holding unit L902 and the APL / illuminance holding unit H903, and a set of the APL value A2 and the detected illuminance value B2. The magnitude of the inclination corresponding to the amount of reflection is calculated. Details of the inclination calculation unit 904 that calculates the magnitude of the inclination using a plurality of sets of APL values and illuminance detection values will be described later.

  The holding unit 905 holds the magnitude of the tilt calculated by the tilt calculating unit 904 as a reflection amount. The amount of reflection held by the holding unit 905 is input to the second adjustment value generation unit 108. The process executed by the second adjustment value generation unit 108 is the same process as in the first embodiment. Also, the processing executed by the first adjustment value generation unit 107 and the luminance gain control value generation unit 106 is the same processing as in the first embodiment.

  Next, the processing flow of this embodiment will be described with reference to FIG. FIG. 10 is a flowchart for explaining a reflection amount calculation process in the second embodiment. Each process in the following flowchart is executed for each frame of the video signal.

  First, in step S <b> 1001, a video signal is input to the video display device 100. This video signal is video data (frame data) in units of frames.

  Subsequently, in step S1002, the APL calculation unit 103 calculates the APL value of the frame data. The APL value calculated by the APL calculation unit 103 is output to the first adjustment value generation unit 107, the APL determination unit 901, the APL / illuminance holding unit L902, and the APL / illuminance holding unit H903.

  In the video display device 100, the ambient light at the time of APL calculation is detected by the ambient light sensor 104, thereby obtaining the illuminance in the installation environment at this time. The obtained illuminance detection values are output to the APL / illuminance holding unit L902 and the APL / illuminance holding unit H903, respectively.

  Subsequently, in step S1004, the APL determination unit 901 compares the APL value output from the APL calculation unit 103 with the threshold value S3. If the APL value is equal to or less than the threshold value S3, the process proceeds to step S1005. If the APL value is larger than the threshold value S3, the process proceeds to step S1006.

  Step S1005 is processing when the APL determination unit 901 determines in step S1004 that the APL value is equal to or less than the threshold value S3. In this case, the APL determination unit 901 sends out a control signal for the APL / illuminance holding unit L902 to hold the APL value and the illuminance detected in step S1003. As described above, the APL value held by the APL / illuminance holding unit L902 is defined as A1, and the detected illuminance value is defined as B1. When the APL value is equal to or less than the threshold value S3, the APL / illuminance holding unit H903 does not hold the APL value.

  Subsequently, in step S1006, the APL determination unit 901 compares the APL value output from the APL calculation unit 103 with the threshold value S4. If the APL value is greater than or equal to the threshold value S4, the process proceeds to step S1007. If the APL value is smaller than the threshold value S4, the process proceeds to step S1008. Since the APL value determined to be equal to or smaller than the threshold value S3 in step S1004 is smaller than the threshold value S4, the process of step S1007 is passed through.

  Step S1007 is processing when the APL determination unit 901 determines in step S1006 that the APL value is equal to or greater than the threshold value S4. In this case, the APL determination unit 901 sends out a control signal for the APL / illuminance holding unit H903 to hold the APL value and the illuminance detected in step S1003. As described above, the APL value held by the APL / illuminance holding unit 903 is defined as A2, and the illuminance detection value is defined as B2. When the APL value is equal to or greater than the threshold value S4, the APL / illuminance holding unit L902 does not hold the APL value.

  Step S1008 is a process of determining whether or not the APL / illuminance holding unit L902 and the APL / illuminance holding unit H903 hold the APL value and the detected illuminance value, respectively. This determination is executed by a control unit (not shown). If no value is held in either holding unit, the process returns to step S1001, and the same process is continued for the next frame data. Also, when the value is held only in one of the holding units, the process returns to step S1001 and the same process is continued for the next frame data. If the values (A1, A2, B1, B2) are held in either holding unit, the process proceeds to step S1009.

  In step S1009, the inclination calculation unit 904 uses the APL values (A1, A2) and the illuminance detection values (B1, B2) held in the APL / illuminance holding unit L902 and the APL / illuminance holding unit H903, respectively, and the reflection amount. Is a process for obtaining the magnitude C of the inclination corresponding to.

  FIG. 11 is a graph that employs the APL value on the horizontal axis and the detected illuminance value on the vertical axis. The inclination calculation unit 904 sets a set of the APL value (A1) and the illuminance detection value (B1) when the threshold value is S3 or less, and a set of the APL value (A2) and the illuminance detection value (B2) when the threshold value is S4 or more. Using these values, the values are plotted on a graph, and the magnitude C of the inclination when connecting with a straight line is obtained.

  The magnitude C of the inclination is obtained by C = (B2-B1) / (A2-A1). The obtained value C is output from the inclination calculation unit 904 to the holding unit 905.

  In step S <b> 1010, the holding unit 905 holds the inclination magnitude C input from the inclination calculation unit 904. In this embodiment, the magnitude C of the inclination is the amount of reflection in the environment where the video display device 100 is installed. However, since the present embodiment assumes a case where the amount of reflection varies, the magnitude C of the inclination changes according to the variation of the amount of reflection.

  When the value C is input from the inclination calculation unit 904, the holding unit 905 proceeds to step S1011. In step S1011, the holding unit 905 sends a control signal for clearing the values held in the APL / illuminance holding unit L902 and the APL / illuminance holding unit H903. Based on this control signal, the APL / illuminance holding unit L902 clears (deletes) the held APL value (A1) and the detected illuminance value (B1). Further, the APL / illuminance holding unit H903 clears (deletes) the held APL value (A2) and the detected illuminance value (B2).

  In the flow shown in FIG. 10, it is described that the process is terminated when the process of step S1011 is completed. However, in this embodiment, when each value is cleared in step S1011, the process starts again from step S1001. Processing will be started.

  The reflection amount value C held in the holding unit 905 is input to the second adjustment value generation unit 108 and used to generate the second adjustment value. Note that the processing of the second adjustment value generation unit 108 is the same as that described in the first embodiment, and a description thereof will be omitted.

  Next, control for correcting the luminance gain of the input video signal using the reflection amount C calculated by the above processing will be described.

  The reflection amount C held in the holding unit 905 is input to the second adjustment value generation unit 108 at predetermined intervals. This corresponds to, for example, sampling and acquiring the value of the reflection amount held in the holding unit 905 by the second adjustment value generation unit 108 every 2 seconds. Here, among the times when the reflection amount is sampled, the first sampling time is t1, and then the sampling time after a predetermined period is t2.

  The first adjustment value generation unit 107 generates a first adjustment value for each frame based on the APL values calculated for all the frame data of the input video signal, and the luminance gain control value generation unit 106. Output to.

  The luminance gain control value generation unit 106 generates a luminance gain control value in units of frames based on the first adjustment value input in units of frames and the second adjustment value input in a predetermined cycle. Output to the control circuit 101.

  FIG. 11 is a graph showing the concept of the magnitude of the inclination calculated by the inclination calculating unit 904. Note that the graph of FIG. 11 shows the magnitude of the inclination held in the holding unit 905 at the time of sampling at time t1 and time t2, that is, the amount of reflection. FIG. 11 discloses a case in which the inclination held in the holding unit 905 when sampling at time t2 is smaller than the inclination held in the holding unit 905 when sampling at time t1. This means that the reflection amount C at the sampling time t2 is smaller than the reflection amount C at the sampling time t1. It should be noted that the two straight lines in FIG. 11 do not mean the APL value and the detected illuminance value obtained at time t1 or t2.

  FIG. 12 is a graph showing the correction level of the peak luminance when the luminance gain of the input video signal is corrected by the luminance gain control circuit 101. The horizontal axis corresponds to the APL value calculated by the APL calculation unit 103, and the vertical axis corresponds to the peak luminance level of the video displayed on the display unit 102. That is, FIG. 12 is a diagram showing the relationship between the APL value of the video signal corrected by the contrast control circuit 101 and the peak luminance level.

  The broken lines in FIG. 12 indicate the correction level of peak luminance in an environment where the amount of reflection is small. In addition, solid lines t1 and t2 in FIG. 12 indicate the correction degree of the peak luminance in the reflection amounts corresponding to the sampling time t1 and the sampling time t2 shown in FIG. 11, respectively. At the sampling time t1, since the inclination shown in FIG. 11 is large, the value of the reflection amount C is large. Therefore, the correction degree of the peak luminance having a high APL value is stronger than in the environment where the reflection amount is small.

  A luminance gain control value is generated based on the second adjustment value generated based on the reflection amount sampled at time t1 and the first adjustment value generated from the APL value calculated after time t1. When the APL value of the frame at this time shows a high value, as shown in FIG. 12, the correction level of the peak luminance is corrected more strongly than the correction level indicated by the broken line. Accordingly, when the frame data is displayed on the display unit 102, the amount of light emitted from the display is reduced, and the illuminance (reflection amount) of the reflected light is also reduced.

  Thereafter, based on the second adjustment value generated based on the amount of reflection sampled again at time t2 after a predetermined period, and the first adjustment value generated based on the APL value calculated after time t2. Thus, a luminance gain control value is generated. As described above, at the time of sampling time t2, the environment changes to an environment where the amount of reflection is smaller than that at the time of sampling time t1. Therefore, even if the APL value of the frame at this time shows the same value as that at the sampling time t1, as shown in FIG. 12, the correction degree of the peak luminance is weaker than that at the sampling time t1.

  Of course, if the amount of reflection does not vary between sampling time t1 and sampling time t2, the second adjustment value shows the same value, so the luminance gain control value also becomes the same value, and the correction level of the peak luminance does not change. Further, when the APL value is equal to or less than the threshold value S1, correction that reduces the peak luminance is not executed, and therefore processing for reducing the luminance to a video signal with a luminance that does not make the viewer feel uncomfortable is not performed.

  As described above, in this embodiment, even in a case where the illuminance of the reflected light fluctuates in the environment where the video display device is installed, the peak suitable for the illuminance of the reflected light is obtained by periodically obtaining the illuminance of the reflected light. Dynamically change the brightness correction level. As a result, it is possible to suppress the blinking of the viewing environment that makes the viewer feel uncomfortable.

  Note that the case where the illuminance of reflected light fluctuates during video viewing is, for example, when the orientation of the display of the video display device is changed, or when a reflective object is placed near the display or removed. Cases are given as examples.

  Further, in this embodiment, based on the luminance gain control value, the luminance gain control circuit 101 executes a process of reducing the peak luminance level when the APL value is a video signal higher than a predetermined threshold S1 among the input video signals. did. However, in a transmissive display that emits a backlight, such as a liquid crystal display, the luminance level of a display image can be lowered by adjusting the amount of light emitted from the backlight. In this case, a value corresponding to the luminance gain in the above-described embodiment may be applied to the adjustment of the light emission amount of the backlight. As described above, the present invention is not limited by the method of adjusting the brightness, and any adjustment method may be adopted as long as the display brightness of the screen when the video is displayed on the display is finally adjusted. May be.

  In the first and second embodiments described above, a graph that does not perform the process of correcting the luminance gain is used for a video signal having an APL value equal to or less than a predetermined threshold value S1. However, the present invention may execute a process of performing luminance correction that is weaker than the correction degree when S1 is exceeded even for a video signal having an APL value equal to or less than the predetermined threshold S1. The present invention is not characterized in that luminance correction is not performed on a video signal having a low APL value.

  In the first embodiment and the second embodiment described above, each functional unit other than the external light sensor may be realized by hardware, or may be realized by software. The present invention is not limited by whether these functional units are realized by hardware or software.

It is a block diagram which shows the structure of the video display apparatus in Example 1 of this invention. It is a graph which shows the concept of the calculation process of the reflection amount performed by the reflection amount calculation part in Example 1 of this invention. It is a graph which shows the concept of the production | generation process of the 1st adjustment value which the 1st adjustment value production | generation part in Example 1 of this invention performs. It is a graph which shows the concept of the production | generation process of the 2nd adjustment value which the 2nd adjustment value production | generation part in Example 1 of this invention performs. It is a graph which shows the concept of the production | generation process of the luminance gain control value which the luminance gain control value production | generation part in Example 1 of this invention performs. It is a graph which shows the correction process of the peak luminance level at the time of performing the luminance gain control in Example 1 of this invention. It is a flowchart which shows the processing flow in Example 1 of this invention. It is a graph which shows the concept of the production | generation process of the 2nd adjustment value which the 2nd adjustment value production | generation part in the modification of Example 1 of this invention performs. It is a block diagram which shows the structure of the video display apparatus in Example 2 of this invention. It is a flowchart which shows the calculation process of the reflection amount in Example 2 of this invention. It is a graph which shows the concept of the process which calculates the magnitude | size of the inclination which the inclination calculation part in Example 2 of this invention performs. It is a graph which shows the correction process of the peak luminance level at the time of performing the luminance gain control in Example 2 of this invention.

Claims (8)

A video display device comprising: a display unit that displays a video signal; and an external light detection unit that detects illuminance of external light around the display unit,
An acquisition means for acquiring an illuminance detection value detected by the external light detection unit;
Calculating means for calculating an average luminance value for each frame data of the video signal displayed on the display unit ;
Display means for causing the display unit to display a low-brightness video signal whose average brightness value calculated by the calculation means is low brightness and a high-brightness video signal whose brightness is high, respectively;
The illuminance detection value acquired by the acquisition unit when the low luminance video signal and the high luminance video signal are respectively displayed by the display unit, and the average luminance value of the low luminance video signal and the high luminance video signal are used. Te, determining means for determining the reflected light intensity caused by displaying an image on said display unit,
Control means for executing correction control for reducing display luminance of a video signal displayed on the display unit using the reflected light illuminance and the average luminance value;
The control means is a case in which the average luminance value is greater than a first threshold and the display luminance is reduced when the reflected light illuminance is large, and the display luminance reduction degree when the reflected light illuminance is small. A video display device , wherein correction control is executed so as to be larger than . First adjustment value generating means for generating, for each frame data, a first adjustment value used by the control means based on the average luminance value;
Second adjustment value generation means for generating a second adjustment value used by the control means based on the reflected light illuminance ,
The first adjustment value is a parameter corresponding to a display luminance reduction rate of the video signal when the average luminance value is larger than the first threshold value.
The second adjustment value is a parameter for adjusting the reduction rate when the reflected light illuminance is larger than a second threshold.
2. The video display device according to claim 1, wherein the control unit determines a reduction rate to be used for correction control of display luminance of the video signal, using the first adjustment value and the second adjustment value. . The second adjustment value generating means, said reflected light intensity, on the basis of a value obtained by dividing the illuminance of the external light detection unit in said detected illuminance detected value the reflected light that in the resulting ambient light to reduce illumination from said The video display device according to claim 2, wherein the second adjustment value is generated. A video display device comprising: a display unit that displays a video signal; and an external light detection unit that detects illuminance of external light around the display unit,
An acquisition means for acquiring an illuminance detection value detected by the external light detection unit;
First calculating means for calculating an average luminance value for each frame data of the video signal displayed on the display unit;
The average luminance value is compared with a predetermined threshold value S3 and threshold value S4 (S3 <S4), and when the average luminance value is smaller than the threshold value S3, the average luminance value A1 and the image of the average luminance value A1 When the signal is displayed on the display unit and associated with the detected illuminance value B1, and the average luminance value is larger than the threshold value S4, the video signal of the average luminance value A2 and the average luminance value A2 is displayed on the display unit. A determination means for associating the detected illuminance value B2 when displayed on the holding unit with the holding unit;
By displaying an image on the display unit using the set of the average luminance value A1 and the illuminance detection value B1 held in the holding unit and the set of the average luminance value A2 and the illuminance detection value B2. The reflected light illuminance C produced
C = (B2-B1) / (A2-A1)
A second calculating means obtained by:
Control means for performing correction control for reducing display luminance of a video signal displayed on the display unit using the reflected light illuminance C and the average luminance value;
The control means is the case where the average luminance value is larger than the first threshold value and the degree of reduction of the display luminance when the reflected light illuminance C is large, and the display luminance when the reflected light illuminance C is small. A video display device that performs correction control so as to be larger than a reduction degree. A control method for a video display device comprising: a display unit that displays a video signal; and an external light detection unit that detects illuminance of external light around the display unit,
An acquisition step of acquiring an illuminance detection value detected by the external light detection unit;
A calculation step of calculating an average luminance value for each frame data of the video signal displayed on the display unit;
A display step of causing the display unit to display a low luminance video signal whose average luminance value calculated in the calculation step is low luminance and a high luminance video signal which is high luminance, respectively,
The illuminance detection value acquired in the acquisition step when the low luminance video signal and the high luminance video signal are respectively displayed in the display step, and the average luminance value of the low luminance video signal and the high luminance video signal are used. Determining a reflected light illuminance generated by displaying an image on the display unit;
Using the reflected light illuminance and the average luminance value, and performing a correction control to reduce the display luminance of the video signal displayed on the display unit, and
In the control step, the display luminance is reduced when the average luminance value is larger than the first threshold and the reflected light illuminance is large, and the display luminance reduction degree when the reflected light illuminance is small. A control method for a video display device, wherein correction control is executed so as to be larger than. A first adjustment value generation step for generating, for each frame data, a first adjustment value used by the control unit based on the average luminance value;
A second adjustment value generating step for generating a second adjustment value used in the control step based on the reflected light illuminance,
The first adjustment value is a parameter corresponding to a display luminance reduction rate of the video signal when the average luminance value is larger than the first threshold value.
The second adjustment value is a parameter for adjusting the reduction rate when the reflected light illuminance is larger than a second threshold.
6. The video display device according to claim 5, wherein in the control step, a reduction rate used for correction control of display luminance of the video signal is determined using the first adjustment value and the second adjustment value. Control method. In the second adjustment value generation step, based on a value obtained by dividing the reflected light illuminance by the illuminance of ambient light obtained by subtracting the reflected light illuminance from the illuminance detection value detected by the external light detection unit, The method of controlling a video display device according to claim 6, wherein the second adjustment value is generated. A control method for a video display device comprising: a display unit that displays a video signal; and an external light detection unit that detects illuminance of external light around the display unit,
An acquisition step of acquiring an illuminance detection value detected by the external light detection unit;
A first calculation step of calculating an average luminance value for each frame data of the video signal displayed on the display unit;
The average luminance value is compared with a predetermined threshold value S3 and threshold value S4 (S3 <S4), and when the average luminance value is smaller than the threshold value S3, the average luminance value A1 and the video of the average luminance value A1 When the signal is associated with the detected illuminance value B1 when the signal is displayed on the display unit and the average luminance value is larger than the threshold value S4, the video signal of the average luminance value A2 and the average luminance value A2 is displayed on the display unit. A determination step of associating and holding the detected illuminance value B2 when displayed on the holding unit,
By displaying an image on the display unit using the set of the average luminance value A1 and the illuminance detection value B1 held in the holding unit and the set of the average luminance value A2 and the illuminance detection value B2. The reflected light illuminance C produced
C = (B2-B1) / (A2-A1)
A second calculation step determined by:
Using the reflected light illuminance C and the average luminance value, and performing a correction control for reducing the display luminance of the video signal displayed on the display unit,
In the control step, the display luminance is reduced when the average luminance value is larger than the first threshold and the reflected light illuminance C is large, and the display luminance when the reflected light illuminance C is small. A control method for a video display device, wherein correction control is executed so as to be larger than a reduction degree.

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