JP2019101329A - Display unit and method of controlling the same - Google Patents

Abstract

To provide a display unit that can superpose an OSD and that can suppress an influence of whether the OSD is present on a display image.SOLUTION: A display unit 100 according to the present invention comprises: a back light 11 capable of having a plurality of control regions controlled in light emission luminance individually; a luminance setting part 103 which sets a light emission luminance value of each control region based upon a part of input image data corresponding to the control region; a correction part 106 which corrects the input image data based upon a set light emission luminance value of each control region; a liquid crystal panel 12 which transmits irradiation light from the back light 11 based upon the corrected input image data to display an image; and a light emission control part which controls a control region whose set light emission luminance value is lower than predetermined luminance among the plurality of control regions with a lower-limit luminance value, and also controls other control regions among the plurality of control regions with a control luminance value obtained by correcting the light emission luminance value so that the back light 11 has a power consumption equal to or less than a threshold.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a display device including a backlight and a transmissive panel, and a control method thereof.

  There is a display device that displays an image using an image signal (HDR image signal) corresponding to High Dynamic Range (HDR) whose corresponding luminance range (dynamic range) is wider than that of the conventional (Standard Dynamic Range, SDR). Since the dynamic range of the HDR image signal corresponds to higher luminance than before, when displaying an image based on the HDR image signal, the display device can display the image with higher display luminance than before. It is required to

  In order to display an image at a higher display brightness with a display including a backlight and a transmissive panel that transmits light from the backlight to display an image, the brightness of light emitted from the backlight to the transmissive panel is used. Need to improve than before. However, there has been a problem that increasing the brightness of the backlight causes an increase in power consumption.

  With respect to such problems, power consumption can be suppressed by reducing the luminance of the area of the backlight corresponding to the dark part of the image to be displayed (area control, local dimming control). In addition, there is a technology of controlling the light emission luminance of the backlight so that the power consumption of the backlight (display device) becomes equal to or less than a predetermined amount. Specifically, when the power consumption of the backlight becomes larger than a certain amount by controlling the area of the backlight based on the image signal, the light emission luminance of each region of the backlight is determined based on the image signal Reduce the luminance than the light emission. As a result, while the luminance of light emitted from the backlight is lowered and the upper limit value of the display luminance of the display device is lowered, the power consumption of the backlight can be reduced to a certain amount or less.

  On the other hand, in a display device, an image may be displayed on a screen by combining an image signal with an On Screen Display (OSD) such as a graphical user interface (GUI) for a user to operate. The OSD often includes relatively high luminance gradations (white gradations) in order to enhance the user's visibility.

  The display device disclosed in Patent Document 1 is a display device that performs area control of the backlight, and when displaying an image on which the OSD is superimposed, the luminance of the region of the backlight corresponding to the region where the OSD is displayed It is disclosed to control the light intensity to a predetermined luminance value.

JP, 2013-125157, A

  However, the power consumption of the backlight may be higher than a certain amount by increasing the light emission luminance of the corresponding region by OSD superposition as in Patent Document 1. In this case, although the original image is the same, the light emission luminance control for suppressing the power consumption of the backlight is activated by the OSD superposition, and the display luminance of the image visually recognized by the user is changed. Therefore, the user may feel disturbed in the visibility of the image.

  In view of the above problems, the present invention is a display device capable of superimposing an OSD, and is capable of suppressing the influence on the display image due to the presence or absence of the OSD while suppressing the power consumption. Intended to be provided.

In order to solve the problems described above, the liquid crystal transmission type display device of the present invention is
A local dimming unit that performs local dimming processing based on an input image;
A loading unit that adjusts the backlight brightness so that the power consumption does not exceed a certain value;
A lower limit luminance setting unit for setting a minimum light emission luminance of backlight luminance;
An image superimposing unit that superimposes a graphics image on the input image;
A liquid crystal unit that displays an image,
Equipped with
In the loading process, control is performed so that the luminance does not fall below a certain level even in a dark area.

  According to the present invention, while suppressing power consumption, the user can view an image whose OSD visibility is good and whose luminance does not change due to the presence or absence of the OSD.

It is a first block diagram showing functional blocks of the display device. It is a flowchart which shows the determination processing of the control brightness value which a brightness | luminance determination part performs. It is a schematic diagram which shows the control area | region of a backlight. It is a schematic diagram which shows input image data. It is a schematic diagram which shows the light emission luminance value and control luminance value which were set with respect to each control area | region. It is a 2nd block diagram which shows each function block of a display apparatus. It is a 3rd block diagram which shows each function block of a display apparatus. It is a schematic diagram which shows the input image data in a comparative example. It is a schematic diagram which shows the input image data which superimposed the OSD image in a comparative example.

Example 1
A first embodiment of the present invention will be described. FIG. 1 is a block diagram showing functional blocks of the display device 100. As shown in FIG. The display device 100 includes a backlight 11, a liquid crystal panel 12, and a control unit 13. Further, the control unit 13 includes an input unit 101, a statistic acquisition unit 102, a luminance setting unit 103, an image superposition unit 104, an OSD generation unit 105, a correction unit 106, an output unit 107, a lower limit luminance setting unit 108, and a luminance determination unit 109. And the light emission control unit 110. The control unit 13 also includes a CPU 120, an I / F unit 121, a memory 122, and a memory 122.

  The backlight 11 is a lighting device that includes a plurality of light source units and emits light. The backlight 11 can individually control the light emission luminance for each control area corresponding to at least one of the plurality of divided areas obtained by dividing the display area of the screen of the liquid crystal panel 12. The backlight 11 controls the light emission luminance of each light source unit based on the information indicating the light emission luminance of each control area acquired from the control unit 13, and emits light.

  The liquid crystal panel 12 is a transmissive display panel disposed in the light irradiation direction of the backlight 11. The liquid crystal panel 12 includes a plurality of liquid crystal elements arranged in a matrix. The transmittance of each liquid crystal element is controlled based on the image signal output from the control unit 13. An image is displayed on the screen of the liquid crystal panel 12 by transmitting the light emitted from the backlight 11 through the respective liquid crystal elements with the transmittance controlled based on the image signal.

  The control unit 13 is a control circuit board that controls the backlight 11 and the liquid crystal panel 12 to display an image on the screen. The control unit 13 includes one or more processors, one or more memories, and one or more electronic circuits.

  The input unit 101 separates the input video signal into header data and image data, and the header data is demodulated to the CPU 120 described later, and the image data is demodulated and output to the statistic acquisition unit 102. Demodulation refers to rearranging video signals arranged for transmission within a display device for display. The video signal is input to the input unit 101 from the signal line output from the output device (not shown) through the input terminal.

  The statistic acquisition unit 102 acquires, for each control area, the statistic of the portion of the image data displayed in the divided area of the liquid crystal panel 12 corresponding to the control area of the backlight 11. The statistic acquisition unit 102 outputs the statistic acquired for each control region to the luminance setting unit 103. The statistic is, for example, a pixel value Vmax which is the maximum luminance among the pixels included in the portion of the image data corresponding to each control region. Here, when the element of a pixel is three elements of red, green, and blue, the pixel value used as the maximum luminance points out the thing of the maximum value among each element value. Further, the image data is output to the image superimposing unit 104.

  The luminance setting unit 103 sets the light emission luminance value of each control region based on the statistics of each control region output from the statistic acquisition unit 102. The luminance setting unit 103 sets the light emission luminance according to the ratio of the statistic (pixel value Vmax) to the maximum value of the pixel values that can be taken by the pixels of the image data. It is assumed that the relationship between the ratio and the light emission luminance value to be set is associated in advance so that the light emission luminance value becomes larger as the ratio is larger. In addition, when the ratio of the statistic (pixel value Vmax) to the maximum value of the pixel values, or the pixel value Vmax is higher than a predetermined threshold, the brightness setting unit 103 has a light emission brightness value higher than that otherwise. The light emission luminance value may be set such that is set. The luminance setting unit 103 outputs information indicating the light emission luminance value of each control area to the luminance determination unit 109 and the correction unit 106.

  The image superimposing unit 104 superimposes a graphics image output from the OSD generation unit 105 described later on the image data output from the statistic acquisition unit 102, and outputs the image data to the correction unit 106.

  The OSD generation unit 105 generates an image for OSD related to an image or a device according to a CPU 120 described later. The generated graphics image is output to the image superimposing unit 104.

  The correction unit 106 corrects the pixel value of the image data output from the image superimposing unit 104 based on the light emission luminance value of each control area set by the luminance setting unit 103.

  The correction unit 106 estimates the luminance distribution of the light irradiated to the liquid crystal panel 12 when each control area emits light based on the set emission luminance value of each control area. For example, the correction unit 106 estimates, for each pixel of the liquid crystal panel 12, the brightness of the light to be emitted.

  The correction unit 106 corrects the pixel value in accordance with the estimation result of the luminance of the emitted light. Specifically, when the correction unit 106 causes each control region of the backlight 11 to emit light with the maximum emission brightness value, the brightness (Lmax) with which the liquid crystal panel 12 is irradiated, and the brightness estimated for each pixel ( The pixel value of each pixel is corrected using the ratio to Lt) as a coefficient. The correction unit 106 multiplies the pixel value of each pixel by Lmax / Lt in the corresponding pixel. The coefficient is not limited to the above-described format, and may be multiplied by a constant. Thereby, even when the light emission luminance of the control area of the backlight 11 is reduced, the user can view and listen with the original luminance of the image data. The corrected image data is output to the output unit 107.

  The output unit 107 outputs the image data output from the correction unit 106 to the liquid crystal panel 12. The liquid crystal panel 12 transmits light from the backlight 11 to display an image by controlling the transmittance of each liquid crystal element based on the acquired image data. That is, it can be said that the output unit 107 is a display control unit that controls the liquid crystal panel 12 such that the liquid crystal panel 12 displays an image based on the image data by outputting the image data to the liquid crystal panel 12.

  The lower limit luminance setting unit 108 outputs, to the luminance determination unit 109, the lowest luminance light emission luminance value (hereinafter, referred to as a lower limit luminance value) L0 that allows the user to view the OSD generated by the OSD generation unit 105. L0 differs depending on the transmittance of the liquid crystal device and the viewing environment, and may be stored in advance in the non-volatile memory 123 described later. In addition, it may be calculated according to the viewing environment using an external light sensor or the like not described at the time of viewing. For example, it is assumed that the lower limit luminance value is a value corresponding to light emission luminance which is half of the light emission luminance capable of emitting light in the control region.

  Luminance determination unit 109 controls the emission of light in each control area from the emission luminance value of each control area output from luminance setting section 103 and the lower limit luminance value L0 input from lower limit luminance setting section 108. Determine the value (control luminance value). The method of determining the control luminance value will be described later. The luminance determination unit 109 outputs information indicating the determined control luminance value of each control area to the light emission control unit 110.

  The light emission control unit 110 controls the light emission by driving the light source of each control region of the backlight 11 based on the control luminance value of each control region output from the luminance determination unit 109. The backlight 11 comprises one or more light sources for each control area. For example, it is assumed that the light source is an LED (Light Emitting Diode). In this case, the light emission control unit 110 drives the light source with the output voltage corresponding to the control luminance value. The light emission control unit 110 may drive the light source by pulse modulation control. In this case, the light emission control unit 110 drives each light source at a duty ratio corresponding to the control luminance value.

  The CPU 120 is a processor that controls processing performed by each functional block of the control unit 13.

  The I / F unit 121 is an interface for acquiring user operation information. The operation information of the user refers to pressing information of a button or touch panel attached to the display device, button pressing information from a remote controller not connected in a wired or wireless manner, or the like. The CPU 120 obtains a setting value and a target value from the user from the user's operation information and the OSD generated by the OSD generation unit 105.

  The memory 122 stores programs and parameters used by the CPU 120 to control each functional block, and is a storage medium on which the CPU 120 can read and write data. The memory 122 is a storage medium that stores programs and parameters used by each functional block, and each functional block can execute data reading and writing. The memory 122 may be configured with one storage medium, or may be configured with a plurality of storage media. When the memory 122 is configured with a plurality of storage media, each storage media may include two or more different types of storage media. For example, volatile storage media and non-volatile storage media can be selected according to the nature of the data they store.

  FIG. 2 is a flowchart showing determination processing of the control luminance value which the luminance determination unit 109 executes. It is assumed that the determination process starts in response to the light emission luminance value of each control area set by the luminance setting unit being input to the luminance determination unit 109.

  In S201, the luminance determination unit 109 sets the target control area (target control area) A (n) of the control areas as an initial target control area A (1) determined in advance. It is assumed that the backlight 11 has a total of X × Y control areas X in the vertical direction and Y in the horizontal direction with respect to the screen. For example, it is assumed that X and Y are each 3. FIG. 3 is a schematic view showing a control area of the backlight 11. The control regions are represented by symbols from 1 to X × Y, respectively.

  In S202, the luminance determination unit 109 acquires a light emission luminance value L (n) for the control area A (n).

  In S203, the luminance determination unit 109 determines whether the light emission luminance value L (n) is larger than the lower limit luminance value L0. If the light emission luminance value L (n) is larger than the lower limit luminance value L0, the process proceeds to S204. If not, the process proceeds to S205.

  In S204, the luminance determination unit 109 acquires the difference between the lower limit luminance value L0 and the light emission luminance value L (n) as the excess value D (n). The excess value D (n) is represented by L (n) -L0.

  In S205, the luminance determination unit 109 sets the light emission luminance value L (n) as the lower limit luminance value L0. Further, the luminance determination unit 109 sets the excess value D (n) to zero.

  In step S206, the luminance determination unit 109 determines whether the above-described processing is completed for all control regions. Specifically, the luminance determination unit 109 determines whether n = X × Y. If the process is completed for all control regions, the process proceeds to S207. If not completed, 1 is added to n and the process returns to S202.

  In S207, the luminance determination unit 109 adds the excess values of all the control regions to calculate a total excess value Ds.

  In S208, the luminance determination unit 109 determines whether the total excess value Ds is larger than the allowable value M. The allowable value M is a difference between the maximum allowable value Mmax and a value L0_sum obtained by multiplying the lower limit luminance value L0 by the number of control areas. Here, the maximum allowable value Mmax is emitted by the control region of the backlight 11 which is preset based on the upper limit value of the power consumption allowable in the display device 100 and the upper limit value of the calorific value of the backlight 11 allowable. Refers to the total amount of possible light emission luminance values. If the total excess value Ds is larger than the allowable light emission luminance value M, the process proceeds to S209. Otherwise, the light emission luminance value set in each control area is determined as the control luminance value, and the process proceeds to S213.

  At S209, the target control area is set to A (1). That is, n indicating the target control area is initialized.

  In S210, the luminance determination unit 109 determines whether the light emission luminance value L (n) is larger than the lower limit luminance value L0. If the light emission luminance value L (n) is larger than the lower limit luminance value L0, the process proceeds to S211. If not, the process proceeds to S212.

In S211, the luminance determination unit 109 corrects the light emission luminance value L (n) based on the total excess value Ds and the allowable value M to obtain a control luminance value B (n). Specifically, the luminance determination unit 109 determines the control luminance value B (n) based on Expression 1. Equation 1 is the emission brightness obtained by reducing the emission brightness where the control brightness value of the control region where the set emission brightness exceeds the lower limit brightness exceeds the lower limit brightness value L0 by a coefficient, and the lower limit brightness value L0 And the luminance value of the sum of The processing proceeds to step S213.
B (n) = L0 + (L (n) -L0) × (M ÷ Ds) formula 1

  In S212, the luminance determination unit 109 sets the light emission luminance value L (n) as the control luminance value B (n). The processing proceeds to step S213.

  In S213, the luminance determination unit 109 determines whether or not the above-described processing is completed for all control regions. Specifically, the luminance determination unit 109 determines whether n = X × Y. If the process is complete for all control areas, the process proceeds to step S214. If not completed, 1 is added to n and the process returns to S210.

  In S214, the luminance determination unit 109 outputs the control luminance value B (n) of each control area to the light emission control unit 110.

  Thus, the process of determining the control luminance value of the luminance determination unit 109 is completed.

  First, the case where the control luminance value determination process of this embodiment is not executed will be described. The case where the control luminance value determination process of the present embodiment is not executed is the case where the light emission of each control area is controlled based on the image data in which the OSD image is superimposed on the input image data.

  FIG. 8 is a schematic view showing input image data, light emission luminance of a backlight controlled based on the input image data, and a display image displayed on the liquid crystal panel 12. FIG. 8A shows input image data. The input image data is assumed to be image data in which a bright area (white tone) and a dark area (black tone) are arranged side by side.

  FIG. 8B is a schematic view showing light emission luminance of a backlight controlled based on input image data. It is assumed that the control area of the backlight 11 is arranged as shown in FIG. In this case, the emission brightness values of the control areas A (1), A (2), A (4), A (5), A (7), and A (8) correspond to the maximum emission brightness of each control area. Is set to the Further, the light emission luminance values of the control areas A (3), A (6), and A (9) are set to values corresponding to the minimum light emission luminance of each control area. It is assumed that the power consumption when the backlight 11 is driven based on the light emission luminance value set in each control region is equal to or less than a predetermined value. Therefore, the light emission luminance value set in each control area is determined as the control luminance value of each control area, and light is emitted as shown in FIG. 8 (b).

  FIG. 8C is a schematic view showing a display image of the liquid crystal panel 12 when an image is displayed based on input image data. Since each control area of the backlight 11 emits light at luminance based on the corresponding portion of the input image data, an image is displayed at the display luminance indicated by the input image data. That is, the decrease in luminance of the display image due to the decrease in luminance of the backlight 11 for suppressing power consumption does not occur.

  FIG. 9 is a schematic view showing input image data on which the OSD image is superimposed, light emission luminance of the backlight controlled based on the input image data on which the OSD image is superimposed, and a display image displayed on the liquid crystal panel 12. FIG. 9A shows input image data on which the OSD image is superimposed. The OSD image is superimposed on part of the dark area of the input image data shown in FIG. The OSD image is an image including an object expressed in white tones. For simplicity, it is indicated by a white square area in the figure.

  FIG. 9B is a schematic view showing the light emission luminance of the backlight controlled based on the input image data on which the OSD image is superimposed. The emission luminance values of the control areas A (1), A (2), A (4), A (5), A (7), and A (8) correspond to the values corresponding to the maximum emission luminance of each control area. It is set. Further, since the OSD image is arranged in the area corresponding to the control area A (9), the light emission luminance value of the control area A (9) is set to a value corresponding to the maximum light emission luminance of each control area.

  The light emission luminance values of the control areas A (3) and A (6) are set to values corresponding to the minimum light emission luminance of each control area. It is assumed that the power consumption when the backlight 11 is driven based on the light emission luminance value set in each control area exceeds a constant value due to the fluctuation of the light emission luminance value of the control area A (9). Therefore, a value obtained by uniformly reducing the light emission luminance value set in each control area so as to suppress the excess of the power consumption is taken as the control luminance value of each control area. At this time, the backlight 11 emits light as shown in FIG.

  FIG. 9C is a schematic view showing a display image of the liquid crystal panel 12 when the image is displayed based on the input image data on which the OSD image is superimposed. Since each control area of the backlight 11 emits light with overall lower luminance than the luminance based on the input image data as shown in FIG. 9B, display luminance lower than the display luminance indicated by the input image data The image is displayed. That is, the decrease in the brightness of the display image occurs due to the decrease in the brightness of the backlight 11 for suppressing the power consumption.

  Next, the effect when the process in this embodiment is performed will be described.

  FIG. 4 is a schematic view showing an example of input image data used to explain the effect of the process of this embodiment. It is assumed that the input image data of FIG. 4 is image data in which an area corresponding to the control area A (3) includes an area of white gradation with respect to the image data shown in FIG.

  FIG. 5 is a schematic view showing a light emission luminance value L set based on input image data and a control luminance value B determined by the determination processing for each control region. The black squares in FIG. 5 each indicate a light emission luminance value L set based on input image data. The shaded squares in FIG. 5 indicate the control luminance values determined based on the process of determining the control luminance values described above for the light emission luminance value L set based on the input image data.

  Since the image signal displayed in the divided areas corresponding to control areas A (3), A (6) and A (9) is composed of only black pixels (0 gradations), it is set in each control area The light emission luminance value is assumed to be 10% of the minimum light emission luminance. In addition, it is assumed that the light emission luminance value set in the other control region is the maximum light emission luminance 100%.

  As in such control areas A (3), A (6) and A (9), the area corresponding to the dark image in the input image data may have a low light emission luminance. When the OSD image is superimposed later on such a region, it may be difficult for the user to view the OSD because the light emission luminance of the corresponding control region is low.

  According to the process of determining the control luminance value described above, the light emission luminance value set for the control area (control areas A (3), A (6) and A (9)) corresponding to the dark image in the input image data Is corrected to the lower limit luminance value L0.

  On the other hand, as shown in the comparative example, when six or more control regions are controlled with the maximum light emission luminance, the power consumption of the backlight becomes a certain value or more. Therefore, in the control area where the light emission luminance value set is higher than the lower limit luminance value L0, the total excess value Ds is decreased at a constant rate so as not to exceed the allowable value M.

  By determining the control luminance value as described above, it is possible to make the light emission luminance of each control region equal to or higher than the light emission luminance necessary for the user to view the OSD, and to suppress the decrease in the visibility of the OSD. . In addition, the power consumption of the backlight 11 can be suppressed to a certain amount or less. Further, since the control luminance value is determined based on the light emission luminance value set based on the input image data before superimposing the OSD, the visual recognition of the image displayed in the area other than the OSD image depending on the presence or absence of the OSD image It is possible to suppress the change in sex.

  Therefore, it is possible to suppress the influence on the display image by the presence or absence of the OSD while suppressing the power consumption.

  Although the loading control is performed using the light emission luminance value in the present embodiment, a current value for controlling the backlight or a value that substitutes it may be used.

Example 2
The display device of the second embodiment can improve the contrast of the dark part in the display device of the first embodiment. The display device according to the second embodiment displays an image by transmitting light of a backlight using two liquid crystal panels. In the display device having such a configuration, it is possible to reduce the dark area of the image compared to the case of using one liquid crystal panel by suppressing the light transmission amount in two steps by each liquid crystal panel. Therefore, even in the control area lit with the lower limit luminance L0, it is possible to view a high contrast image in a local area, where black is tighter.

  FIG. 6 is a block diagram showing each functional block of the display device 400. As shown in FIG. About the functional block which exhibits the function similar to the display apparatus 100 of Example 1, the same name and code | symbol are used. The description of functional blocks that exhibit the same function as the display device 100 according to the first embodiment will be omitted.

  The display device 400 includes not the liquid crystal panel 12 but the back liquid crystal panel 21 and the front liquid crystal panel 22.

  The front liquid crystal panel 22 is a transmissive panel that further transmits light transmitted through the rear liquid crystal panel 21 to display an image. The front liquid crystal panel 22 is assumed to be a liquid crystal panel of the same type as the liquid crystal panel 12.

  The back liquid crystal panel 21 is a transmissive panel that controls the liquid crystal element to be non-transmissive or totally transmissive for each pixel based on the transmission setting information output from the control information output unit 401. The number of pixels (liquid crystal elements) of the back liquid crystal panel 21 is at least the same as that of the front liquid crystal panel 22.

  The control information output unit 401 calculates the transmittance information of the back liquid crystal according to each pixel of the image data output from the correction unit 106. For example, in the corrected image data, the pixel whose pixel value is equal to or less than the threshold value sets the transmittance information to 0 (information indicating the minimum transmittance), and the pixel other than that has the transmittance 100% (information indicating the maximum transmittance) I assume. The transmittance information may be in the form of image data. For example, a tone value 0 (black tone value) is specified as information indicating the minimum transmittance, and a tone value 255 (white tone value, in the case of 8-bit data) is specified as information indicating the maximum transmittance. Control image data may be used as the transmittance information. The control information output unit 401 outputs the transmission setting information to the back liquid crystal panel 21.

  By performing the control as described above, it is possible to reduce the amount of light emitted from the back liquid crystal panel 21 to the area of the front liquid crystal panel 22 corresponding to the pixel having a small pixel value. Therefore, even if the control luminance value is determined so as to compensate the lower limit value visible to the OSD for the control area corresponding to the divided area where the dark image is displayed in the input image data, the area where the OSD is displayed It is possible to reduce the display brightness of dark areas other than the above. Therefore, the user can view the dark part in the image data as an image in which black is tight regardless of the presence or absence of the OSD.

  In the present embodiment, the pixels of the back liquid crystal panel 21 and the front liquid crystal panel 22 correspond to each other one by one, but the present invention is not limited to this. One-to-many or many-to-one correspondence may be used. Further, although the control information output unit 401 determines the pixel value of the corrected image data as either a dark area pixel or a non-dark area pixel, the present invention is not limited to this. The control information output unit 401 may set the transmission setting information having the gradation value by averaging the surrounding pixels and the image data by the filter of the spatial frequency.

Example 3
The display device of the third embodiment makes it possible to control the display brightness of the OSD more suitably to the display device of the second embodiment.

  FIG. 7 is a block diagram showing each functional block of the display device 500. As shown in FIG. About the functional block which exhibits the function similar to the display apparatus 100 of Example 1 and the display apparatus 400 of Example 2, the same name and code | symbol are used. The description of the functional blocks that exhibit the same function as the display device 100 of the first embodiment and the display device 400 of the second embodiment will be omitted.

  The control unit 13 further includes an OSD luminance setting unit 501 and an adjustment unit 502. The OSD luminance setting unit 501 outputs, to the adjusting unit 502, the luminance value Lg at the time of displaying the OSD that can be expressed by the lower limit luminance value set by the lower limit luminance setting unit 108. Lg may be stored in advance in the memory 122. In addition, it may be calculated according to the viewing environment using an external light sensor or the like not described at the time of viewing.

  The adjustment unit 502 determines whether or not the light emission luminance value is equal to or less than a predetermined threshold value for each pixel of the image data output from the correction unit 106, and generates information of dark area pixels. Further, an area on which the OSD is superimposed by the image superimposing unit 104 is specified by the image data. Calculates the gradation value T of the back liquid crystal unit 402 where the control luminance value B (n) input from the luminance determination unit 109 becomes the luminance value Lg input from the OSD luminance setting unit 501 in the identified OSD overlapping area Do. The calculation may use linear conversion that represents the characteristics of the back liquid crystal panel 21. Alternatively, table values representing the characteristics of the rear liquid crystal panel 21 may be prepared in advance, and interpolation calculations may be performed using the table values. The calculated gradation value T is output to the rear liquid crystal panel 21.

  As a result, even when the background image changes, graphics are displayed with constant luminance, and the visibility of the user is improved.

Reference Signs List 100 display device 11 back light 12 liquid crystal panel 13 control unit 103 brightness setting unit 106 correction unit 109 brightness determination unit

Claims (16)

Light emitting means capable of individually controlling the light emission luminance of each of the plurality of control regions;
Setting means for setting light emission luminance of each control area based on a portion of input image data corresponding to each control area;
A correction unit that corrects the input image data based on the light emission luminance of each set control region;
Display means for transmitting the light emitted from the light emitting means based on the corrected input image data to display an image;
A light emission control unit configured to control light emission of each control region based on the light emission luminance of each set control region;
Equipped with
The light emission control means is
Among the plurality of control areas, a first control area having the set light emission luminance lower than a predetermined luminance is controlled with the predetermined luminance,
Of the plurality of control areas, the second control area which is not the first control area is a light emission luminance obtained by correcting the light emission luminance set so that the power consumed by the light emitting means is equal to or less than a predetermined threshold. A display device characterized by controlling.   The light emission control means is configured to reduce the light emission luminance exceeding the predetermined luminance among the light emission luminance set in the second control area by a predetermined coefficient to reduce the total luminance of the light emission luminance and the predetermined luminance. The display device according to claim 1, wherein the light emission of the second control area is controlled.   The display device according to claim 1, wherein the display panel is a liquid crystal panel that transmits an image based on the corrected input image data and displays the image. The display panel is
A first liquid crystal panel transmitting light emitted from the light emitting means; and a second liquid crystal panel transmitting an image transmitted by the light transmitted through the first liquid crystal panel based on the corrected input image data Equipped
The first liquid crystal panel transmits light emitted from the light emitting means based on control image data generated based on the corrected input image data. The display device as described in. The image processing apparatus further comprises synthesizing means for superimposing an OSD image on the input image data,
The display device according to any one of claims 1 to 4, wherein the correction means corrects the input image data on which the OSD image is superimposed. A storage medium storing a setting value of display brightness of the OSD image;
The display device according to claim 5, wherein the correction unit corrects a pixel value of the OSD image such that display brightness of a region on which the OSD image is superimposed becomes the setting value.   The display device according to any one of claims 1 to 6, wherein the predetermined luminance is half of the upper limit value of the luminance that allows the control area to emit light. The apparatus further comprises estimation means for estimating the luminance distribution of the light irradiated to the display means when each control region emits light at the emission luminance set by the setting means.
The display device according to any one of claims 1 to 7, wherein the correction unit corrects the input image data in accordance with the luminance distribution of light estimated by the estimation unit. A control method of a display device, comprising: light emitting means capable of individually controlling light emission luminance of each of a plurality of control regions; and display means for transmitting light emitted from the light emitting means to display an image.
Setting the light emission luminance of each control area based on the portion of the input image data corresponding to each control area;
A correction step of correcting the input image data based on the light emission luminance of each set control region;
A display control step of displaying an image by transmitting the light emitted from the light emitting means based on the corrected input image data;
A light emission control step of controlling light emission of each control region based on the light emission luminance of each set control region;
Equipped with
The light emission control step is
Among the plurality of control areas, a first control area having the set light emission luminance lower than a predetermined luminance is controlled with the predetermined luminance,
Of the plurality of control areas, the second control area which is not the first control area is a light emission luminance obtained by correcting the light emission luminance set so that the power consumed by the light emitting means is equal to or less than a predetermined threshold. And controlling a display device.   In the light emission control step, of the light emission luminance set in the second control area, the light emission luminance exceeding the predetermined luminance is multiplied by a predetermined coefficient to reduce the total luminance of the light emission luminance and the predetermined luminance. The control method of the display device according to claim 9, wherein light emission of the second control area is controlled.   The control method of a display device according to claim 9 or 10, wherein the display means is a liquid crystal panel which transmits an image based on the corrected input image data and displays the image. The display means displays a first liquid crystal panel transmitting the light emitted from the light emitting means, and transmits the light transmitted through the first liquid crystal panel based on the corrected input image data to display an image Equipped with 2 liquid crystal panels,
The first liquid crystal panel transmits light emitted from the light emitting means based on control image data generated based on the corrected input image data. The control method of the display apparatus as described in these. The method further comprises a combining step of superimposing an OSD image on the input image data,
The control method of a display device according to any one of claims 9 to 12, wherein the correction step corrects the input image data on which the OSD image is superimposed. The display device includes a storage medium storing a setting value of display brightness of the OSD image,
The method according to claim 13, wherein the correcting step corrects the pixel value of the OSD image so that the display brightness of the area where the OSD image is superimposed becomes the set value. .   The control method of a display device according to any one of claims 9 to 14, wherein the predetermined brightness is half of the upper limit value of the brightness that the control area can emit light. The method further comprises an estimation step of estimating the luminance distribution of the light irradiated to the display means when each control area emits light at the emission luminance set in the setting step.
The control of the display device according to any one of claims 9 to 15, wherein the correction step corrects the input image data in accordance with the luminance distribution of light estimated by the estimation step. Method.

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