JP5072087B2 - Liquid crystal display device and liquid crystal display method - Google Patents

Description

  The present invention relates to a liquid crystal display device, a liquid crystal display method, and a program, for example.

  The liquid crystal display device includes a liquid crystal display panel for performing display based on various image signals, and a backlight for illuminating the liquid crystal display panel from behind in order to ensure sufficient visibility when performing display.

  The backlight determines the brightness of the background when displaying, so that the user can check the display content with high visibility even when the liquid crystal display device is in a dark place or in a light place. The brightness of the backlight can be changed according to the ambient illuminance of the liquid crystal display device.

  As an example of an apparatus for controlling the brightness of a backlight, a solid-state imaging device, a liquid crystal display device to which a video signal is supplied from the solid-state imaging device, a back illumination unit attached to the liquid crystal display device, and a light detection unit And an electronic camera device characterized by having control means for controlling the light emission luminance of the back illumination means based on the light detection output of the light detection means (see, for example, Patent Document 1). .

  In addition, for example, when the liquid crystal display device is moved to a dark place and the backlight is changed so that the luminance of the backlight is lowered, the display becomes dark accordingly, and the display contents are difficult to visually recognize. Therefore, when the brightness of the backlight is changed, image signal correction such as contrast correction is performed to minimize degradation of visibility.

  As an example of a method for controlling the luminance of the backlight and correcting the image signal, display data generated by combining a plurality of image data is displayed on a light receiving display device that displays light by irradiating light from a light source. A method of extracting a first feature amount indicating a feature of at least one of the image data; generating at least one of the image data based on the first feature amount; Synthesizing the image data to generate display data; extracting a second feature amount indicating the feature of the display data; adjusting brightness of the light source and the display based on the second feature amount; There is known a display method including a step of performing correlation in luminance adjustment of image data (see, for example, Patent Document 2).

JP 2002-344778 A JP 2006-154064 A

  However, in the conventional liquid crystal display device, the backlight control for controlling the luminance of the backlight and the liquid crystal control for correcting the image signal such as contrast correction are performed independently. Therefore, for example, when the liquid crystal display device is moved to a place with different ambient illuminance, the luminance of the backlight is changed based on the ambient illuminance, and the feature amount of the image signal is changed based on the changed luminance of the backlight, The image signal is corrected based on the changed feature amount of the image signal. For this reason, the display screen of the liquid crystal display device may suddenly become brighter or darker.

  A specific example is shown in FIG. In FIG. 13, a straight line BX indicates the relationship between the feature amount of the image signal and the luminance (BL luminance) of the backlight, and a straight line CX indicates the relationship between the feature amount of the image signal and the degree of contrast correction. Yes.

  For example, when the ambient illuminance decreases, a BL control unit that controls the luminance of the backlight decreases the BL luminance. As a result, it is assumed that the BL brightness is lowered from the point A to the point B on the straight line BX. In this case, the feature amount of the image signal is actually the feature amount at point A. However, the liquid crystal control unit for correcting the image signal has changed to the feature amount of the image signal corresponding to the lowered BL luminance, although the feature amount of the image signal does not change with the backlight control. I get the illusion. Therefore, since the liquid crystal control unit performs contrast correction corresponding to the feature amount of the image signal at point B on the straight line BX, the degree of contrast correction is changed from point A to point C on the straight line CX. As described above, even when the feature amount of the image signal is not actually changed, the contrast becomes a higher degree of correction than before the movement, and the display screen may suddenly become brighter.

  The present invention has been made in view of the above circumstances, and provides a liquid crystal display device, a liquid crystal display method, and a program capable of smoothly changing the brightness of a display screen and ensuring sufficient visibility. The purpose is to provide.

Liquid crystal display device of the present invention comprises a a liquid crystal display device having a liquid crystal panel dimming controllable light sources, the image feature extraction unit for extracting a feature value of the image signal to be displayed on the liquid crystal panel, Ambient illuminance detection unit that detects the illuminance around the liquid crystal display device, and stores characteristic information indicating the relationship between the ambient illuminance and the conversion feature amount for converting the ambient illuminance as the feature amount of the image signal A characteristic information storage unit, a characteristic information of the characteristic information storage unit, a control unit that generates control information based on the feature amount of the image signal and the conversion feature amount, and the control information based on the control information , a light source control section for controlling the luminance of the light source, Ru comprising a.

According to this configuration, the brightness of the display screen can be changed smoothly and sufficient visibility can be ensured. For example, when the ambient illuminance decreases, it is possible to prevent the display screen from being instantly brightened by excessively correcting the image signal. When the ambient illuminance increases It is possible to prevent the display screen from being darkened instantaneously by correcting the image signal excessively.
In addition, the ambient illuminance can be converted as a feature quantity of the image signal, and it is possible to perform backlight control and image signal correction in consideration of both the ambient illuminance and the feature quantity of the image signal. Can be smoothly changed and sufficient visibility can be ensured.

The liquid crystal display device of the present invention, the control unit, on the basis of the feature amount and the transformed feature of the image signal to generate a feature value of a new image signal, the feature value of the new image signal based on, that generates the control information.

  According to this configuration, it is possible to perform backlight control according to the feature amount of a new image signal in consideration of ambient illuminance, and the brightness of the display screen can be changed smoothly and sufficient visibility can be obtained. It can be secured.

The liquid crystal display device of the present invention, auxiliary positive information, chroma correction information indicating the correction degree of the saturation of the contrast correction information and the image signal indicating the correction degree of contrast of the image signal is included, before An image signal conversion unit that performs contrast correction and saturation correction of the image signal based on the correction information.

  According to this configuration, it is possible to maintain the optimal contrast and saturation of the image signal in accordance with the ambient illuminance, to change the brightness of the display screen more smoothly and to ensure sufficient visibility.

The liquid crystal display method of the present invention is a liquid crystal display method of the liquid crystal display device, comprising the steps of: extracting a feature value of the image signal to be displayed on the LCD panel, detects the illuminance around the liquid crystal display device Referring to characteristic information of a characteristic information storage unit that stores characteristic information indicating a relationship between the ambient illuminance and the converted feature value for converting the ambient illuminance as a feature value of the image signal, Generating control information based on a feature amount of an image signal and the converted feature amount; and controlling brightness of a light source capable of dimming control of the liquid crystal panel based on the control information.

According to this method, the brightness of the display screen can be changed smoothly and sufficient visibility can be ensured. For example, when the ambient illuminance decreases, it is possible to prevent the display screen from being instantly brightened by excessively correcting the image signal. When the ambient illuminance increases It is possible to prevent the display screen from being darkened instantaneously by correcting the image signal excessively.
In addition, the ambient illuminance can be converted as a feature quantity of the image signal, and it is possible to perform backlight control and image signal correction in consideration of both the ambient illuminance and the feature quantity of the image signal. Can be smoothly changed and sufficient visibility can be ensured.

  The first program of the present invention is a program for causing a computer to execute each step of the liquid crystal display method.

  According to this program, the brightness of the display screen can be changed smoothly and sufficient visibility can be ensured. For example, when the ambient illuminance decreases, it is possible to prevent the display screen from being instantly brightened by excessively correcting the image signal. When the ambient illuminance increases It is possible to prevent the display screen from being darkened instantaneously by correcting the image signal excessively.

  According to the present invention, the brightness of the display screen can be changed smoothly and sufficient visibility can be ensured.

  A liquid crystal display device, a liquid crystal display method, and a program according to embodiments of the present invention will be described below with reference to the drawings.

  As the liquid crystal display device in the embodiment of the present invention, for example, a mobile phone device, a television receiver, a liquid crystal display for PC, other liquid crystal display devices, and the like can be considered, but a liquid crystal used in a place where ambient illuminance changes It is particularly effective to apply the present invention to a display device.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of a liquid crystal display device according to an embodiment of the present invention. A liquid crystal display device 10 shown in FIG. 1 includes an input image signal storage unit 11, a color space conversion unit 12, an image feature extraction unit 13, an illuminance sensor 14, a control unit 15, a backlight control unit 16, a contrast correction unit 17, and a saturation. The correction unit 18, the color space conversion unit 19, the liquid crystal panel 20, the backlight (BL) 21, and the characteristic information storage unit 22 are configured.

  The input image signal storage unit 11 stores an input image signal. This storage includes temporary storage. As the input image signal, a video signal or a video signal of a moving image or a still image stored in advance, an image signal or a video signal, an image signal of content delivered by streaming from an external server, a TV signal of digital TV broadcasting, or the like can be considered. The input image signal is an example of an image signal to be displayed on the liquid crystal panel 20.

  The color space conversion unit 12 receives the input image signal from the input image signal storage unit 11, converts the color space of the input image signal, and uses the converted signal as a converted image signal, the contrast correction unit 17, and the saturation correction unit. 18. Output to the image feature extraction unit 13.

  As a color space, an RGB color space expressing a color as a combination of three colors of red (R), green (G), and blue (B), a difference between a luminance signal (Y), a luminance signal, and a blue component (U) In addition, there are a YUV color space that expresses a color by three information of a difference (V) between a luminance signal and a red signal, an HSI color space composed of hue, saturation, and luminance.

  The color space conversion unit 12 receives an input image signal in such a color space and converts it into a signal in another color space. The color space conversion unit 12 can be omitted.

  The image feature extraction unit 13 extracts an image feature amount indicating the feature of the image from the converted image signal from the color space conversion unit 12 and outputs the image feature amount to the control unit 15 as image feature information. As the image feature amount, for example, the value of each parameter in the converted color space can be considered. Note that the image feature extraction unit 13 has a function as an image feature amount extraction unit.

  The illuminance sensor 14 is, for example, an optical sensor that detects light in a predetermined wavelength band, detects the illuminance around the liquid crystal display device 10 (environment light), and outputs ambient illuminance information to the control unit 15. Illuminance detection by the illuminance sensor 14 can be performed periodically. The illuminance sensor 14 is an example of an ambient illuminance detection unit.

  The control unit 15 refers to the characteristic information stored in the characteristic information storage unit 22, and based on the image feature information from the image feature extraction unit 13 and the ambient illuminance information from the illuminance sensor 14, contrast correction, saturation correction, etc. Correction information for performing image correction and control information for performing backlight control are generated. The correction information is output to the contrast correction unit 17 and the saturation correction unit 18. The control information is output to the backlight control unit 16.

  The backlight control unit 16 controls the backlight 21 based on the control information from the control unit 15 and causes the backlight 21 to emit light. The backlight control unit 16 changes the luminance of the backlight 21 by changing the light emission rate of the backlight 21. For example, when the maximum backlight luminance value that can be set by the user's instruction of the backlight 21 is 100, 80 backlight luminance values may appear brightest at a certain ambient illuminance. In this case, the light emission rate for 80 backlight luminance values is set to 100%. That is, the light emission rate of 100% is determined in consideration of ambient illuminance. The backlight control unit 16 has a function as a light source control unit.

  The contrast correction unit 17 corrects the contrast of the converted image signal from the color space conversion unit 12 based on the correction information from the control unit 15 and outputs the corrected image signal to the color space conversion unit 19 as a contrast corrected image signal. The contrast correction unit 17 functions as an image signal conversion unit that performs contrast correction.

  Based on the correction information from the control unit 15, the saturation correction unit 18 corrects the saturation of the converted image signal from the color space conversion unit 12 and outputs the correction image signal to the color space conversion unit 19 as a saturation correction image signal. The saturation correction unit 18 has a function as an image signal conversion unit that performs saturation correction.

  The color space conversion unit 19 generates a signal capable of expressing the corrected contrast and saturation based on the contrast correction image signal from the contrast correction unit 17 and the saturation correction image signal from the saturation correction unit 18, Further, the color space of the generated signal is converted into an RGB color space, and is output to the liquid crystal panel 20 as a display signal.

  The liquid crystal panel 20 has, for example, a structure in which an oily transparent liquid crystal composition is sandwiched between two transparent substrates and the periphery is sealed, and displays a display signal from the color space conversion unit 19.

  The backlight 21 is, for example, a light source for illuminating the liquid crystal panel 20 from the back, and emits light according to an instruction from the backlight control unit 16.

  The characteristic information storage unit 22 stores characteristic information for reference by the control unit 16. As characteristic information, a characteristic B1 indicating the relationship between the feature amount of the image signal and the backlight luminance value, a characteristic C1 indicating the relationship between the feature amount of the image signal and the correction degree of contrast correction and saturation correction, and the ambient illuminance It has a characteristic E1 indicating the relationship with the conversion feature value for converting the ambient illuminance as the feature value of the image signal.

  2 and 3 are diagrams illustrating examples of characteristic information stored in the characteristic information storage unit 22.

  FIG. 2 is a diagram illustrating an example of the characteristics B1 and C1. FIG. 2 shows that when the feature amount of the image signal is dark, the backlight luminance value is low, the correction degree is high, and when the feature amount of the image signal is bright, the backlight It is understood that the luminance value is high and the correction degree is low.

  FIG. 3 is a diagram illustrating an example of the characteristic E1. For example, in order to perform backlight control and image correction based on both the ambient illuminance and the feature amount of the image signal, the converted feature amount is obtained by calculating the difference between the ambient illuminance detected this time and the ambient illuminance detected last time. It is converted into a feature value. In this case, if the current ambient illuminance is greater than the previous ambient illuminance, that is, greater than 0, a converted feature quantity is generated so that the feature quantity of the image signal is larger, and the current ambient illuminance is the previous ambient illuminance. If it is smaller than 0, that is, smaller than 0, the converted feature quantity is generated so that the feature quantity of the image signal becomes smaller. 3 is an example, and the ambient illuminance may be changed to the feature amount of the image signal by a method other than the difference.

  Next, an example of the operation of the liquid crystal display device 10 will be described. FIG. 4 is a flowchart showing an example of the operation of the liquid crystal display device 10.

  First, the illuminance sensor 14 detects ambient illuminance and outputs ambient illuminance information to the control unit 15 (step S11). Here, it is assumed that ambient illuminance detection is performed periodically.

  Subsequently, the control unit 15 determines whether or not the ambient illuminance at the previous detection and the ambient illuminance at the current detection have changed (step S12).

  When it is determined that the ambient illuminance has changed, the control unit 15 refers to the characteristic E1 of the characteristic information storage unit 22 and acquires a conversion feature amount corresponding to the detected ambient illuminance (step S13).

  Subsequently, the control unit 15 generates a new feature amount of the image signal based on the feature amount of the image signal and the converted feature amount (step S14). For example, the conversion feature amount acquired from the characteristic information storage unit 22 is added to the feature amount of the image signal from the image feature extraction unit 13.

  Subsequently, the control unit 15 refers to the characteristic B1 of the characteristic information storage unit 22, acquires a backlight luminance value corresponding to the feature amount of the new image signal, and generates control information based on the backlight luminance value. Then, control information is output to the backlight control unit 16 (step S15).

  Subsequently, the control unit 15 refers to the characteristic C1 of the characteristic information storage unit 22, and the degree of contrast and saturation correction corresponding to the feature amount of the image signal from the image feature extraction unit 13 (how much contrast correction and saturation are required). Correction information is generated, correction information is generated based on the degree of correction, and the correction information is output to the contrast correction unit 17 and the system correction unit 18 (step S16).

  Subsequently, the backlight control unit 16 controls the luminance of the backlight 21 based on the control information (step S17).

  Subsequently, the contrast correction unit 17 performs contrast correction of the image signal (converted image signal) based on the correction information (step S18).

  Subsequently, the saturation correction unit 18 performs saturation correction of the image signal (converted image signal) based on the correction information (step S19).

  Note that the contrast correction process and the correction process can be performed simultaneously. The same applies to the contrast correction processing and the correction processing described later.

  Further, although it has been described that the subsequent processing shown in FIG. 4 is performed when a change in ambient illuminance is detected in step S12, step S12 can be omitted.

  According to the processing of FIG. 4, the backlight control and the correction of the image signal in consideration of both the ambient illuminance and the feature amount of the image signal are possible, so that the brightness of the display screen can be changed smoothly, It is also possible to ensure sufficient visibility.

  Next, a specific example of image signal correction and backlight control performed by the liquid crystal display device 10 will be described.

First, a case where the ambient illuminance decreases will be described.
FIG. 5 is a diagram illustrating a specific example of image signal correction and backlight control performed by the liquid crystal display device 10 when the ambient illuminance decreases.

  In the process of FIG. 4, if the feature amount of the image signal from the image feature extraction unit 13 indicates point A and the feature amount of the new image signal indicates point B due to a decrease in ambient illuminance, a new point indicated by point B is displayed. The correction degree corresponding to the feature amount of the image signal, that is, the correction degree indicated by the point C is not acquired from the characteristic C1, but the correction degree corresponding to the feature amount of the image signal from the image feature extraction unit 13, that is, the point A is Correction information is generated based on the same correction level as the correction level shown. Therefore, correction information based on the point D, not the point C in FIG. 5, is generated.

  In this way, the luminance of the backlight 21 is controlled so as to change from the luminance indicated by the point A to the luminance indicated by the point B. Further, the image signal is corrected so that the correction level shown at point D is changed from the correction level shown at point A. That is, the degree of correction of the image signal does not change.

  Thereby, it is possible to suppress a sudden change in the brightness of the display screen due to the decrease in the ambient illuminance, and to perform natural display according to the ambient illuminance and the feature amount of the image signal. As a result of the decrease in ambient illuminance, the backlight luminance value decreases, but the correction level for contrast correction and saturation correction is the same as the correction level before the decrease in ambient illuminance, so the display screen is dark. Since the ambient illuminance is reduced, the user is not recognized, the user's eyes are less tired, and sufficient visibility can be secured.

Next, a case where the ambient illuminance increases will be described.
FIG. 6 is a diagram illustrating a specific example of image signal correction and backlight control performed by the liquid crystal display device 10 when the ambient illuminance increases.

  In the process of FIG. 4, when the ambient light intensity increases, the feature amount of the image signal from the image feature extraction unit 13 indicates the point A, and the feature amount of the new image signal indicates the point E, a new point indicated by the point E The correction level corresponding to the feature amount of the image signal, that is, the correction level indicated by the point F, is not acquired from the characteristic C1, but the correction level corresponding to the feature amount of the image signal from the image feature extraction unit 13, that is, the point A is Correction information is generated based on the same correction level as the correction level shown. Therefore, correction information based on the point D, not the point F in FIG. 5, is generated.

  In this way, the luminance of the backlight 21 is controlled so as to change from the luminance indicated by the point A to the luminance indicated by the point E. Further, the image signal is corrected so as to have a correction level indicated by point G from a correction level indicated by point A. That is, the degree of correction of the image signal does not change.

  Thereby, it is possible to suppress a sudden change in the brightness of the display screen due to the increase in the ambient illuminance, and to perform natural display according to the ambient illuminance and the feature amount of the image signal. As a result of the increase in ambient illuminance, the backlight brightness value increases, but the correction level for contrast correction and saturation correction is the same as the correction level before the decrease in ambient illuminance. Since the ambient illuminance is increased, it is not recognized by the user, the user's eyes are less tired, and sufficient visibility can be secured.

(Second Embodiment)
FIG. 7 is a block diagram showing an example of the configuration of the liquid crystal display device according to the second embodiment of the present invention. In the liquid crystal display device 10B shown in FIG. 7, the same components as those of the liquid crystal display device 10 shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  The liquid crystal display device 10B includes a characteristic information storage unit 22B instead of the characteristic information storage unit 22. Other components are the same as those of the liquid crystal display device 10.

  The characteristic information storage unit 22 has characteristic B1 and characteristic C1 shown in FIG. 2 as characteristic information, and characteristic E2 indicating the relationship between ambient illuminance and backlight luminance value.

  FIG. 8 is a diagram illustrating an example of the characteristic E2. It can be understood from FIG. 8 that the backlight luminance value changes with a predetermined value as a boundary when the ambient illuminance is 100 (lux) or 10000 (lux).

  Next, an example of an operation performed by the liquid crystal display device 10B when the ambient illuminance decreases will be described. FIG. 9 is a flowchart illustrating an example of an operation performed by the liquid crystal display device 10B when the ambient illuminance decreases.

  First, the illuminance sensor 14 detects ambient illuminance and outputs ambient illuminance information to the control unit 15 (step S21). Here, it is assumed that ambient illuminance detection is performed periodically.

  Subsequently, the control unit 15 determines whether or not the ambient illuminance detected this time is lower than the ambient illuminance at the time of the previous detection, that is, whether or not the ambient illuminance has decreased (step S22).

  When it is determined that the ambient illuminance has decreased, the control unit 15 refers to the characteristic E2 of the characteristic information storage unit 22 and acquires a backlight luminance value corresponding to the detected ambient illuminance (step S23).

  Subsequently, the control unit 15 refers to the characteristic B1 of the characteristic information storage unit 22, and acquires the feature amount of the image signal corresponding to the acquired backlight luminance value (step S24).

  Subsequently, the control unit 15 refers to the characteristic C1 of the characteristic information storage unit 22, and acquires the degree of contrast correction and saturation correction corresponding to the characteristic amount of the acquired image signal (step S25).

  Subsequently, the control unit 15 generates control information based on the acquired backlight luminance value, and outputs the control information to the backlight control unit 16 (step S26).

  Subsequently, the control unit 15 generates correction information based on the acquired correction degree, and outputs the correction information to the contrast correction unit 17 and the saturation correction unit 18 (step S27).

  Subsequently, the backlight control unit 16 controls the luminance of the backlight 21 based on the control information (step S28).

  Subsequently, the contrast correction unit 17 performs contrast correction of the image signal (converted image signal) based on the correction information (step S29). At this time, the contrast correction is started as soon as the backlight control by the backlight control unit 16 is completed. At the time of completion of the backlight control, the contrast correction degree is set to 0 (indicating that no contrast correction is performed), and the correction information Contrast correction is gradually performed at a predetermined low speed so as to achieve the included contrast correction level. This makes it possible to perform optimal display without the user recognizing changes in luminance of the backlight 21 or image characteristics.

  Subsequently, the saturation correction unit 18 performs saturation correction of the image signal (converted image signal) based on the correction information (step S30). At this time, the saturation correction is started as soon as the backlight control by the backlight control unit 16 is completed, but the saturation correction degree is set to 0 (indicating that no saturation correction is performed) at the time of completion of the backlight control, The saturation correction is gradually performed at a predetermined low speed so that the saturation correction level included in the correction information is obtained. This makes it possible to perform optimal display without the user recognizing changes in luminance of the backlight 21 or image characteristics.

  According to the processing of FIG. 9, since it is possible to perform backlight control and image signal correction in consideration of both the ambient illuminance and the feature amount of the image signal, the brightness of the display screen can be changed smoothly, It is also possible to ensure sufficient visibility. In addition, even if the ambient illuminance is reduced, the correction processing is performed immediately after the user is sufficiently used to the change in the viewing environment without performing contrast correction and saturation correction immediately. There is little burden.

  Although it has been described that the contrast correction and the saturation correction are performed after the backlight control is completed, the correction information includes the start time for starting the contrast correction and the saturation correction, and the correction is started after a predetermined period. Also good.

  FIG. 10 is a diagram illustrating a specific example of image signal correction and backlight control performed by the liquid crystal display device 10B when the ambient illuminance decreases.

  In the process of FIG. 9, when the ambient light intensity decreases, the feature amount of the image signal from the image feature extraction unit 13 indicates the point A, and the feature amount of the image signal acquired in step S24 indicates the point B. The correction information is generated based on the correction degree corresponding to the feature amount of the image signal indicated by, that is, the correction degree indicated by the point C. Further, since the contrast correction and the saturation correction are started from the correction degree 0, they are started from the H point.

  In this way, the luminance of the backlight 21 is controlled so as to change from the luminance indicated by the point A to the luminance indicated by the point B. Further, the image signal is corrected so that the correction level shown at point C is changed from the correction level shown at point H (= 0).

  Next, an example of an operation performed by the liquid crystal display device 10B when the ambient illuminance increases will be described. FIG. 11 is a flowchart illustrating an example of an operation performed by the liquid crystal display device 10B when the ambient illuminance increases. Note that steps that perform the same processing as the steps in FIG. 9 are given the same step numbers, and descriptions thereof are omitted or simplified.

  First, the liquid crystal display device 10B performs step S21.

  Subsequently, the control unit 15 determines whether or not the ambient illuminance detected this time is higher than the ambient illuminance at the previous detection, that is, whether or not the ambient illuminance has increased (step S32).

  When it is determined that the ambient illuminance has decreased, the liquid crystal display device 10B performs the processes of steps S23 to S27.

  Subsequently, the backlight control unit 16 controls the luminance of the backlight 21 based on the control information (step S38). At this time, as shown in FIG. 14 described later, the luminance of the backlight 21 is gradually changed from the state of the maximum backlight luminance at the light emission rate determined by the ambient illuminance to the backlight luminance value included in the control information at a predetermined low speed. To change.

  Subsequently, the contrast correction unit 17 performs contrast correction of the image signal (converted image signal) based on the correction information (step S39). At this time, when the backlight control by the backlight control unit 16 is started, that is, when the backlight luminance is maximized, the contrast correction degree is set to 0 (indicating that no contrast correction is performed) and is included in the correction information. The contrast correction is gradually performed at a predetermined low speed so as to achieve a contrast correction level. That is, backlight control and contrast correction are performed in parallel. This makes it possible to perform optimal display without the user recognizing changes in luminance of the backlight 21 or image characteristics.

  Subsequently, the saturation correction unit 18 performs saturation correction of the image signal (converted image signal) based on the correction information (step S40). At this time, when the backlight control unit 16 starts the backlight control, that is, when the backlight luminance is maximized, the saturation correction degree is set to 0 (indicating that no saturation correction is performed), and the correction information The saturation correction is gradually performed at a predetermined low speed so as to achieve the saturation correction level included in. That is, backlight control and saturation correction are performed in parallel. This makes it possible to perform optimal display without the user recognizing changes in luminance of the backlight 21 or image characteristics.

  According to the processing of FIG. 11, since it is possible to perform backlight control and image signal correction in consideration of both the ambient illuminance and the feature amount of the image signal, the brightness of the display screen can be changed smoothly, It is also possible to ensure sufficient visibility. Also, even if the ambient illuminance increases, backlight control, contrast correction, and saturation correction are not performed immediately, and the process is performed gradually after the user is sufficiently accustomed to changes in the viewing environment. , Less burden on the user.

  FIG. 12 is a diagram illustrating a specific example of image signal correction and backlight control performed by the liquid crystal display device 10B when the ambient illuminance increases.

  In the process of FIG. 11, when the ambient illuminance increases, the feature amount of the image signal from the image feature extraction unit 13 indicates the point A, and the feature amount of the image signal acquired in step S24 indicates the point E. The correction information is generated based on the correction degree corresponding to the feature amount of the image signal indicated by, that is, the correction degree indicated by the point F. Further, the backlight control is started from the state of the maximum backlight luminance at the light emission rate determined by the ambient light intensity of the light emission rate backlight 21 as shown in FIG. The backlight control is started from the point I shown in FIG. 12 with the light emission rate as a reference, and the light emission rate remains unchanged until the point E is reached. As shown in FIG. 14, the light emission rate of the backlight at point I varies depending on the illuminance, for example, 50% at 100 lux, and the light emission rate of the backlight at point E is, for example, 80% based on point I. The light emission rate (50% issue rate x 80% at 100 lux). Further, since the contrast correction and the saturation correction are started from the correction degree 0, they are started from the H point.

  In this way, the luminance of the backlight 21 is controlled so as to change from the maximum luminance indicated by the point I to the luminance indicated by the point E. Further, the image signal is corrected so that the correction level shown at point F is changed from the correction level shown at point H (= 0).

  As described above, the brightness of the display screen can be changed smoothly, and the present invention is useful for a liquid crystal display device, a program, and the like that can ensure sufficient visibility.

1 is a block diagram showing an example of a configuration of a liquid crystal display device according to a first embodiment of the present invention. The figure which shows an example of the characteristic information which the characteristic information storage part in the 1st Embodiment of this invention memorize | stores The figure which shows an example of the characteristic information which the characteristic information storage part in the 1st Embodiment of this invention memorize | stores The flowchart which shows an example of operation | movement of the liquid crystal display device in the 1st Embodiment of this invention. The figure which shows the specific example of the image signal correction | amendment and backlight control at the time of the surrounding illumination fall in the 1st Embodiment of this invention The figure which shows the specific example of the image signal correction | amendment at the time of the surrounding illumination rise in 1st Embodiment of this invention, and backlight control The block diagram which shows an example of a structure of the liquid crystal display device in the 2nd Embodiment of this invention. The figure which shows an example of the characteristic information which the characteristic information storage part in the 2nd Embodiment of this invention memorize | stores. The flowchart which shows an example of the operation | movement which the liquid crystal display device in the 2nd Embodiment of this invention implements when ambient illumination intensity falls. The figure which shows the specific example of the image signal correction | amendment at the time of the surrounding illumination fall in the 2nd Embodiment of this invention, and backlight control The flowchart which shows an example of the operation | movement which the liquid crystal display device in the 2nd Embodiment of this invention implements when ambient illuminance rises. The figure which shows the specific example of the image signal correction | amendment at the time of the surrounding illumination rise in the 2nd Embodiment of this invention, and backlight control The figure which shows the specific example of the conventional image signal correction | amendment and backlight control The figure which shows an example of the relationship between ambient illumination intensity and the backlight light emission rate in the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10B Liquid crystal display device 11 Input image signal storage part 12 Color space conversion part 13 Image feature extraction part 14 Illuminance sensor 15 Control part 16 Backlight control part 17 Contrast correction part 18 Saturation correction part 19 Color space conversion part 20 Liquid crystal panel 21 Backlight 22, 22B Characteristic information storage unit

Claims (4)

A liquid crystal display device having a light source capable of dimming control of a liquid crystal panel,
An image feature amount extraction unit that extracts a feature amount of an image signal to be displayed on the liquid crystal panel;
An ambient illuminance detector that detects the illuminance around the liquid crystal display device;
A characteristic information storage unit that stores characteristic information indicating a relationship between the ambient illuminance and the converted feature value for converting the ambient illuminance as a feature value of the image signal;
A control unit that refers to characteristic information in the characteristic information storage unit and generates control information based on the feature amount of the image signal and the converted feature amount;
A light source controller that controls the luminance of the light source based on the control information;
A liquid crystal display device comprising: The liquid crystal display device according to claim 1,
The control unit generates a new image signal feature amount based on the image signal feature amount and the converted feature amount, and generates the control information based on the new image signal feature amount. apparatus. The liquid crystal display device according to claim 1 or 2 ,
Complement positive information, chroma correction information indicating the correction degree of the saturation of the contrast correction information and the image signal indicating the correction degree of contrast of the image signal is included,
Based on the previous SL correction information, a liquid crystal display device including an image signal converting unit that performs contrast correction and chroma correction of the image signal. A liquid crystal display method in a liquid crystal display device,
Extracting a feature amount of an image signal for displaying on the LCD panel,
Detecting the illuminance around the liquid crystal display device;
Refer to the characteristic information of the characteristic information storage unit that stores characteristic information indicating the relationship between the ambient illuminance and the converted feature value for converting the ambient illuminance as the feature value of the image signal, and the feature of the image signal Generating control information based on a quantity and the converted feature quantity;
Controlling the luminance of a light source capable of dimming the liquid crystal panel based on the control information;
A liquid crystal display method comprising:

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