JP2019191237A - Display device and display device control method - Google Patents

Abstract

To provide a technique that can suppress image deterioration of a display image arising from a responce speed difference between a plurality of transmissive panels.SOLUTION: A display device of the present invention comprises: a light emission unit; a first transmissive panel where transmittance is controlled by a voltage to be applied, and which transmits light emitted from the light emission unit; a second transmissive panel where transmittance is controlled by the voltage to be applied, and which transmits the light transmitting the first transmissive panel and displays an image on a display screen; and control means that periodically controls the voltage to be applied to the first transmissive panel and the voltage to be applied to the second transmissive panel respectively on the basis of object image data. In a first period when the voltage to be applied to the first transmissive panel and the voltage to be applied to the second transmissive panel are controlled respectively, the control means is configured to temporarily control the voltage to be applied to the second transmissive panel to a voltage higher than a voltage according to the object image data so that a difference between a responce speed of the first transmissive panel and a responce speed of the second transmissive panel is equal to or less than a prescribed value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a display device having a light emitting unit and two or more transmissive panels, and a control method thereof.

  Improvement of the fidelity of a display image (an image displayed on a display surface) is desired for a display device. Specifically, it is desired to increase the brightness ratio (contrast ratio; brightness / darkness ratio) between the bright and dark areas of the display image and to improve the accuracy of the change in gradation (gradation) from the bright area to the dark area of the display image. Yes. As a technique for increasing the number of gradations of a display image, there is a technique for individually driving each of two overlapping liquid crystal panels (transmission panels). A display device provided with the two liquid crystal panels is called a “dual liquid crystal display device” or the like.

  Since each liquid crystal panel of the dual liquid crystal display device has a structure in which a liquid crystal layer is sandwiched between two glass plates, a space is generated between the two liquid crystal layers corresponding to the two liquid crystal panels. For this reason, if each liquid crystal panel (each liquid crystal layer) is controlled to have the same transmittance, the image displayed on the back panel (back side liquid crystal panel) is displayed on the front panel (front side side) when the display surface is viewed obliquely. A double image can be seen without overlapping the image displayed on the liquid crystal panel. Such a double image can be reduced by a spatial low-pass process that suppresses a spatial high-frequency component of an image displayed on the back panel (Patent Document 1).

International Publication No. 2007/040127

  However, in the dual liquid crystal display device, considering that light emitted from the backlight module is transmitted through the two liquid crystal panels, the light emission luminance of the backlight module is higher than that in the case of one liquid crystal panel. It is controlled to a high emission luminance (about twice). For this reason, in the dual liquid crystal display device, the power consumption and the heat generation amount of the backlight module are larger and the temperature of each liquid crystal panel is likely to increase than in the case where there is only one liquid crystal panel.

  In particular, the back panel is close to a backlight module that is a heating element. Further, in general, the amount of light transmitted through the back panel is greater than the amount of light transmitted through the front panel, and the transmitted light is converted into heat. The non-transparent light of the back panel is light that does not pass through the back panel among the light emitted from the backlight module to the back panel. The non-transmitted light from the front panel is light that does not pass through the front panel among the light emitted from the back panel to the front panel. As a result, the temperature difference between the back panel and the front panel is higher than the temperature of the front panel.

  The response speed of the liquid crystal panel is faster as the temperature of the liquid crystal panel is higher. As described above, the temperature difference between the back panel and the front panel is a temperature difference in which the temperature of the back panel is higher than the temperature of the front panel. For this reason, the response speed difference between the back panel and the front panel is higher than the response speed of the front panel.

And the image quality degradation of a display image will arise by the response speed difference mentioned above. For example, when displaying a moving image, there is a difference between the timing at which the transmittance of the back panel reaches the desired transmittance and the timing at which the transmittance of the front panel reaches the desired transmittance, resulting in a decrease in the brightness of the display image. , Increase in double image, etc.

  An object of the present invention is to provide a technique capable of suppressing deterioration in image quality of a display image due to a difference in response speed between a plurality of transmissive panels.

The first aspect of the present invention is:
A light emitting unit;
A first transmissive panel whose transmittance is controlled by an applied voltage and which transmits light emitted from the light emitting unit;
A second transmissive panel that displays an image on a display surface by transmitting the light that is transmitted from the light emitting unit and transmitted through the first transmissive panel, the transmittance being controlled by an applied voltage;
Control means for periodically controlling the voltage applied to the first transmissive panel and the voltage applied to the second transmissive panel based on target image data;
With
In one cycle in which each of the voltage applied to the first transmissive panel and the voltage applied to the second transmissive panel is controlled, the control means includes the response speed of the first transmissive panel and the second transmissive panel. The voltage applied to the second transmissive panel is temporarily controlled to a voltage higher than the voltage corresponding to the target image data so that the difference from the response speed is less than a predetermined value. It is a display device.

The second aspect of the present invention is:
A light emitting unit;
A first transmissive panel that transmits light emitted from the light emitting unit at a transmittance according to an applied voltage;
A second transmissive panel that transmits light transmitted through the first transmissive panel at a transmittance according to an applied voltage and displays an image on a display surface;
Control means for controlling the applied voltage of the first transmissive panel and the applied voltage of the second transmissive panel based on target image data;
Obtaining means for obtaining a parameter related to a difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel;
With
When the difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel is equal to or greater than a predetermined value, the control means applies the voltage applied to the first transmissive panel and the application of the second transmissive panel. In the display device, one of the voltages is controlled to a higher applied voltage than in the case where the voltage is not so.

The third aspect of the present invention is:
A light emitting unit;
A first transmissive panel whose transmittance is controlled by an applied voltage and which transmits light emitted from the light emitting unit;
A second transmissive panel that displays an image on a display surface by transmitting the light that is transmitted from the light emitting unit and transmitted through the first transmissive panel, the transmittance being controlled by an applied voltage;
A display device control method comprising:
A control step of periodically controlling a voltage applied to the first transmission panel and a voltage applied to the second transmission panel based on target image data,
In the control step, the response speed of the first transmissive panel and the second transmissive panel are controlled in one cycle in which each of the voltage applied to the first transmissive panel and the voltage applied to the second transmissive panel is controlled. The voltage applied to the second transmissive panel is temporarily controlled to a voltage higher than the voltage corresponding to the target image data so that the difference from the response speed is less than a predetermined value. A display device control method.

The fourth aspect of the present invention is:
A light emitting unit;
A first transmissive panel that transmits light emitted from the light emitting unit at a transmittance according to an applied voltage;
A second transmissive panel that transmits light transmitted through the first transmissive panel at a transmittance according to an applied voltage and displays an image on a display surface;
A display device control method comprising:
A control step of controlling the applied voltage of the first transmissive panel and the applied voltage of the second transmissive panel based on target image data;
Obtaining a parameter related to the difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel;
Have
In the control step, when the difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel is equal to or greater than a predetermined value, the applied voltage of the first transmissive panel and the application of the second transmissive panel The display device control method is characterized in that any one of the voltages is controlled to a higher applied voltage than the other voltage.

  A fifth aspect of the present invention is a program for causing a computer to execute each step of the above-described display device control method. A sixth aspect of the present invention is a computer-readable storage medium storing a program for causing a computer to execute each step of the display device control method described above.

  According to the present invention, it is possible to suppress deterioration in image quality of a display image due to a difference in response speed between a plurality of transmissive panels.

Schematic which shows an example of a structure of the display apparatus which concerns on Example 1. FIG. 1 is a block diagram illustrating an example of a configuration of a display device according to a first embodiment. 1 is a flowchart illustrating an example of a processing flow according to the first embodiment. The figure which shows an example of the correspondence of the temperature of the transmissive panel which concerns on Example 1, and a response speed. The figure which shows an example of the correspondence of the gradation value which concerns on Example 1, and a normal voltage. The figure which shows an example of the time change of the gradation value which concerns on Example 1. FIG. The figure which shows an example of the time change of the transmittance | permeability The figure which shows an example of the image represented by object image data The figure which shows an example of distribution of display luminance and transmittance The figure which shows an example of distribution of display luminance and transmittance The figure which shows an example of the time change of the applied voltage which concerns on Example 1. FIG. The figure which shows an example of the time change of the transmittance | permeability which concerns on Example 1. FIG. The figure which shows an example of the correspondence of the gradation change which concerns on Example 2, and a response speed. FIG. 10 is a diagram illustrating an example of gradation characteristics according to the second embodiment. FIG. 6 is a block diagram illustrating an example of a configuration of a display device according to a second embodiment.

<Example 1>
Embodiment 1 of the present invention will be described below. FIG. 1 is a schematic diagram illustrating an example of a configuration of a display device (dual liquid crystal display device) 100 according to the present embodiment. The display device 100 includes a front panel 104, a back panel 105, and a backlight module 106. After that
A description will be given assuming that the direction from the backlight module 106 toward the display surface is the forward direction. The back panel 105 is a liquid crystal panel provided on the front side (front side) with respect to the backlight module 106, and the front panel 104 is a liquid crystal panel provided on the front side with respect to the back panel 105. The light emitted from the backlight module 106 passes through the back panel 105 and the front panel 104 in that order, so that an image is displayed on the display surface. The display device 100 includes members (not shown) such as an exterior bezel, a power source, operation keys, and various circuits.

  Each of the front panel 104 and the back panel 105 may be a transmissive panel (a transmissive display panel) and may not be a liquid crystal panel. For example, at least one of the front panel 104 and the back panel 105 may be a MEMS shutter type display panel having a MEMS (Micro Electro Mechanical System) shutter as a display element. In order to prevent moiré, an optical sheet, a predetermined space, or the like may be provided between the front panel 104 and the back panel 105.

  FIG. 2 is a block diagram illustrating an example of the configuration of the display device 100. The display device 100 includes an image data input unit 101, a front panel drive circuit unit 102, a back panel drive circuit unit 103, a front panel 104, a back panel 105, a backlight module 106, a temperature detection unit 107, a storage unit 108, and a control. Part 109.

  The image data input unit 101 acquires target image data (input image data) output from an external device (not shown), and uses the target image data as a front panel drive circuit unit 102, a back panel drive circuit unit 103, and a control unit. To 109. For example, the image data input unit 101 is an input terminal conforming to a standard such as SDI or HDMI, and the external device is an imaging device, a playback device, or the like.

  The display device 100 may include a storage unit that stores image data, and the image data input unit 101 may acquire image data recorded in the storage unit from the storage unit as target image data. . The target image data is not limited to image data output from an external device, image data recorded in the storage unit, and the like. For example, the display device 100 may include a processing unit that performs predetermined processing on image data output from an external device, image data recorded in a storage unit, and the like. Image data may be used as target image data. The predetermined processing is, for example, decoding processing, resolution conversion processing, blurring processing, edge enhancement processing, luminance conversion processing, color conversion processing, and the like.

The front panel drive circuit unit 102 periodically controls the voltage applied to the front panel 104 based on the target image data. In this embodiment, the front panel drive circuit unit 102 applies a voltage (liquid crystal drive signal) based on the target image data to the front panel 104 in each cycle in which the applied voltage of the front panel 104 is controlled. Thereby, in each cycle, the transmittance of the front panel 104 is controlled to the transmittance based on the target image data. The front panel drive circuit unit 102 is equipped with an overdrive circuit that temporarily generates a voltage higher than the voltage corresponding to the target image data in one cycle in which the voltage applied to the front panel 104 is controlled. The front panel drive circuit unit 102 can apply a voltage corresponding to the target image data to the front panel 104 or a voltage generated by the overdrive circuit. The front panel drive circuit unit 102 switches whether to apply the voltage generated by the overdrive circuit according to an instruction from the control unit 109. By applying the voltage generated in the overdrive circuit to the front panel 104, the response speed of the front panel can be increased. The response speed of the transmissive panel is “the time from the start of applying the voltage based on the target image data to the transmissive panel until the transmission of the transmissive panel reaches the target transmittance corresponding to the target image data. (Response time) ”.

  The back panel drive circuit unit 103 periodically controls the voltage applied to the back panel 105 based on the target image data. In this embodiment, the back panel drive circuit unit 103 applies a voltage (liquid crystal drive signal) based on the target image data to the back panel 105 in each cycle in which the applied voltage of the back panel 105 is controlled. Thereby, in each cycle, the transmittance of the back panel 105 is controlled to the transmittance based on the target image data. In this embodiment, the back panel drive circuit unit 103 applies a voltage corresponding to the target image data to the back panel 105. Specifically, the back panel drive circuit unit 103 generates processed image data by performing spatial low-pass processing that suppresses spatial high-frequency components of the image on the target image data. Then, the back panel drive circuit unit 103 applies a voltage corresponding to the processed image data to the back panel 105. Since the spatial low-pass process is a predetermined process, the “voltage according to the processed image data” can also be said to be “the voltage according to the target image data”.

  One cycle in which the applied voltage of the front panel 104 is controlled is equal to one cycle in which the applied voltage of the back panel 105 is controlled. In one cycle in which the applied voltage of the front panel 104 and the applied voltage of the back panel 105 are controlled, the applied voltage and transmittance of the front panel 104 and the applied voltage and transmittance of the back panel 105 are controlled. It can be said that this is one control period. One control period is, for example, one frame period of target image data.

  The backlight module 106 is a light emitting unit that emits light to the front side. The backlight module 106 includes one or more light sources (light emitting elements). As a light source, for example, a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), an electroluminescence (EL) element, or the like can be used. The configuration of the backlight module 106 is not particularly limited as long as the back surface of the back panel 105 can be irradiated with light. For example, the configuration (type) of the backlight module 106 may be a direct type, an edge light type, or a planar light source type. The backlight module 106 may or may not include a plurality of light sources having different emission colors. For example, the backlight module 106 may include only a white light source, or may include a red light source, a green light source, and a blue light source. The backlight module 106 may include a white light source, a red light source, a green light source, and a blue light source.

  The back panel 105 is a liquid crystal panel whose transmittance is controlled by application of a voltage from the back panel drive circuit unit 103 and transmits light emitted from the backlight module 106. The front panel 104 has its transmittance controlled by application of a voltage from the front panel drive circuit unit 102, and displays an image on the display surface by transmitting light emitted from the backlight module 106 and transmitted through the back panel 105. It is a liquid crystal panel.

The configuration of the liquid crystal panel includes a plurality of configurations different from each other in the arrangement method of liquid crystal molecules, the driving method of liquid crystal molecules, and the like. For example, a liquid crystal panel driving method (driving method) includes a TN (Twisted Nematic) method, a VA (Vertical Alignment) method, an IPS (In-Plane-Switching) method, and the like. Examples of the liquid crystal panel include a color liquid crystal panel having a color filter and a monochrome liquid crystal panel having no color filter. The structure of the front panel 104 and the structure of the back panel 105 are not particularly limited as long as the transmittance can be controlled by controlling the applied voltage. For example, the driving method of each of the front panel 104 and the back panel 105 may be a TN method, a VA method, or an IPS method. Since an IPS liquid crystal panel has excellent color development characteristics, it is preferable to use an IPS liquid crystal panel. Each of the front panel 104 and the back panel 105 may be a monochrome liquid crystal panel or a color liquid crystal panel. The configuration of the front panel 104 may be different from the configuration of the back panel 105. For example, a configuration in which the back panel 105 is a monochrome liquid crystal panel and the front panel 104 is a color liquid crystal panel may be employed.

  The temperature detection unit 107 acquires temperature information regarding the temperature of the front panel 104 and the temperature of the back panel 105, and outputs the temperature information to the control unit 109. Specifically, the temperature detection unit 107 includes a temperature sensor (such as a thermistor) that detects the temperature of the front panel 104 and a temperature sensor that detects the temperature of the back panel 105, and the temperature detection of these two temperature sensors. The value is output as temperature information.

  The method for obtaining the temperature of the front panel 104 and the temperature of the back panel 105 is not limited to the above method. For example, one of the temperature of the front panel 104 and the temperature of the back panel 105 is detected by a temperature sensor, and the other of the temperature of the front panel 104 and the temperature of the back panel 105 is estimated based on the temperature detection value of the temperature sensor. Also good. A temperature sensor detects a temperature at a location where the temperature of the front panel 104 and the temperature of the back panel 105 are highly related, and the temperature of the front panel 104 and the temperature of the back panel 105 are estimated based on the temperature detection value of the temperature sensor. May be. The temperature of the front panel 104 and the temperature of the back panel 105 are estimated based on the driving conditions (such as light emission luminance) of the backlight module 106 that are closely related to the temperature of the back panel 105 and the external temperature of the display device 100. May be.

  The temperature information may not be information indicating the temperature of the front panel 104 and the temperature of the back panel 105. When the temperature of the front panel 104 and the temperature of the back panel 105 can be acquired from a certain parameter, the parameter may be used as temperature information. For example, information indicating the driving condition of the backlight module 106 and the external temperature of the display device 100 may be used as the temperature information.

  The storage unit 108 stores various information. For example, the storage unit 108 stores response speed information (table or function) indicating the correspondence between the temperature of the transmissive panel and the response speed of the transmissive panel. In this embodiment, it is assumed that the correspondence between the temperature of the front panel 104 and the response speed of the front panel 104 is equal to the correspondence between the temperature of the back panel 105 and the response speed of the back panel 105. The correspondence indicated by the response speed information is a correspondence between the temperature of the front panel 104 and the response speed of the front panel 104, and is also a correspondence between the temperature of the back panel 105 and the response speed of the back panel 105. The response speed information is recorded in advance in the storage unit 108 at the time of manufacturing inspection of the display device 100 or the like. Furthermore, the storage unit 108 stores a program for performing various processes (controls) described later.

  Note that the correspondence between the temperature of the front panel 104 and the response speed of the front panel 104 may be different from the correspondence between the temperature of the back panel 105 and the response speed of the back panel 105. The storage unit 108 individually stores information indicating the correspondence between the temperature of the front panel 104 and the response speed of the front panel 104 and information indicating the correspondence between the temperature of the back panel 105 and the response speed of the back panel 105. May be stored.

  The control unit 109 is configured by a CPU or FPGA (Field Programmable Gate Array), and implements various processes described later by executing a program read from the storage unit 108.

In the present embodiment, the control unit 109 controls the voltage applied to the front panel 104 (application of the front panel 104 so that the difference between the response speed of the front panel 104 and the response speed of the back panel 105 is equal to or less than a predetermined threshold. Voltage). Specifically, the control unit 109 is based on the temperature information obtained by the temperature detection unit 107, the response speed information recorded in the storage unit 108, the target image data obtained by the image data input unit 101, and the like. The applied voltage of the front panel 104 is determined. Then, the control unit 109 notifies the determined applied voltage to the front panel drive circuit unit 102. The front panel drive circuit unit 102 applies the voltage notified by the control unit 109 (application voltage of the front panel 104) to the front panel 104.

  As the applied voltage of the front panel 104, a voltage (overdrive voltage) higher than the voltage corresponding to the target image data may be determined. In that case, in the corresponding one control period, the front panel drive circuit unit 102 temporarily applies the notified overdrive voltage to the front panel 104 using the overdrive circuit (of the front panel 104). Overdrive drive). In overdrive driving of the front panel 104, for example, the voltage applied to the front panel 104 is temporarily controlled to the overdrive voltage and then controlled to a voltage (normal voltage) corresponding to the target image data.

  The applied voltage of the front panel 104 is generated by the front panel drive circuit unit 102. The front panel drive circuit unit 102 generates a voltage corresponding to an instruction (voltage notification) from the control unit 109 as the applied voltage of the front panel 104. appear. For this reason, it can be said that “the applied voltage of the front panel 104 is controlled by the front panel drive circuit unit 102” and “the applied voltage of the front panel 104 is controlled by the control unit 109”.

  FIG. 3 is a flowchart illustrating an example of a processing flow of the control unit 109. The processing flow in FIG. 3 is started in response to a power ON operation for turning on the display device 100, for example. Here, it is assumed that the temperature of the front panel 104 is 23 ° C. and the temperature of the back panel 105 is 30 ° C. For simplification, it is assumed that the gradation value of the target image data is a 3-bit value (a value between 0 and 7).

  In step S111, control unit 109 acquires temperature information (the temperature of front panel 104 and the temperature of back panel 105) from temperature detection unit 107.

  In step S112, the control unit 109 calculates the response speed of the front panel 104 and the response speed of the back panel 105 based on the temperature information acquired in step S111 and the response speed information recorded in the storage unit 108. to decide. FIG. 4 is a diagram illustrating an example of response speed information (correspondence between the temperature of the transmissive panel and the response speed of the transmissive panel). The faster the response speed, the smaller the response speed value (time). In the example of FIG. 4, the response speed of the transmissive panel is inversely proportional to the temperature of the transmissive panel. Therefore, when at least one of the temperature of the front panel 104 and the temperature of the back panel 105 is low, the difference between the response speed of the front panel 104 and the response speed of the back panel 105 (response speed difference) is compared to the case where the temperature is not so. ) Is likely to occur. And when both the temperature of the front panel 104 and the temperature of the back panel 105 are high, compared with the case where it is not so, the response speed difference of the front panel 104 and the back panel 105 does not arise easily. As described above, the temperature of the front panel 104 is 23 ° C., and the temperature of the back panel 105 is 30 ° C. Therefore, it is determined from the response speed information of FIG. 4 that the response speed of the front panel 104 is 30 msec, and the response speed of the back panel 105 is determined to be 23 msec.

In step S113, control unit 109 calculates the difference between the response speed of front panel 104 and the response speed of back panel 105 (response speed difference) using the response speed determined in step S112. Here, a response speed difference of 7 msec (= 30 msec−23 msec) is calculated. The response speed indicated by the response speed information is a response speed when overdrive driving is not performed. Therefore, in step S112, a response speed when overdrive driving is not performed is determined, and in step S113, a response speed difference when overdrive driving is not performed is calculated (determined).

  In step S114, control unit 109 determines whether or not the response speed difference calculated in step S113 is greater than a predetermined threshold value. If it is determined that the response speed difference is greater than the predetermined threshold value, the process proceeds to step S116; otherwise (if the response speed difference is equal to or smaller than the predetermined threshold value), the process proceeds to step S115. . The predetermined threshold is not particularly limited, but in the present embodiment, the predetermined threshold is 5 msec. Since the response speed difference 7 msec is larger than the predetermined threshold 5 msec, the process proceeds to step S116.

  In step S115, the control unit 109 determines a voltage (normal voltage) corresponding to the target image data as an applied voltage of the front panel 104. FIG. 5 is a diagram illustrating an example of a correspondence relationship between the gradation value of the target image data and the normal voltage. In step S115, for example, when the gradation value of the target image data is 6, the normal voltage 3.8V is determined as the applied voltage of the front panel 104 in accordance with the correspondence relationship in FIG.

  In step S116, the control unit 109 determines an overdrive voltage as an applied voltage of the front panel 104 according to the response speed difference calculated in step S113. In step S116, for example, when the gradation value of the target image data is 6, the normal voltage 5V (overdrive voltage) corresponding to the gradation value 7 larger than the gradation value 6 based on the correspondence relationship of FIG. ) Is determined as the voltage applied to the front panel 104.

  In step S117, the control unit 109 notifies the front panel drive circuit unit 102 of the applied voltage determined in step S115 or step S116. Thereby, when the response speed difference calculated in step S113 is larger than the predetermined threshold value, the overdrive drive of the front panel 104 is performed. On the other hand, when the response speed difference calculated in step S113 is equal to or smaller than the predetermined threshold value, the applied voltage of the front panel 104 is controlled to the normal voltage without performing overdrive driving of the front panel 104.

  The processing flow of FIG. 3 is performed every time the target image data is updated. For example, the processing flow in FIG. 3 is performed every control period or every frame period. Note that acquisition of temperature information (step S111) may be performed at a frequency lower than the frequency (for example, frame rate) at which the target image data is updated. For example, temperature information is acquired at any time in a period in which various temperatures of the display apparatus 100 are not stable, such as a period immediately after the display apparatus 100 is started up or a period immediately after the emission luminance of the backlight module 106 is changed. Is preferred. However, when various temperatures of the display device 100 are stable, the temperature information may be regarded as constant without performing the acquisition of the temperature information as needed, and other processing may be performed.

  A specific example of the effect of this embodiment (the effect of overdrive driving of the front panel 104) will be described. Here, for simplification, it is assumed that the gradation value of the target image data and the gradation value of the processed image data are 3-bit values (values of 0 or more and 7 or less). However, the number of bits of the processed image data and the number of bits of the target image data are not particularly limited, and the number of bits of the processed image data may be different from the number of bits of the target image data. Further, for the sake of simplicity, the correspondence between the gradation value of the processed image data and the voltage (normal voltage) corresponding to the processed image data is the voltage corresponding to the gradation value of the target image data and the target image data (normal voltage). )) (The correspondence relationship in FIG. 5). However, the correspondence between them is not particularly limited, and the correspondence between the gradation value of the processed image data and the voltage according to the processed image data is the difference between the gradation value of the target image data and the voltage according to the target image data. It may be different from the correspondence.

  FIG. 6 is a diagram illustrating an example of a temporal change in the gradation value (the gradation value of the target image data and the gradation value of the processed image data). In the example of FIG. 6, the gradation value of the target image data and the gradation value of the processed image data increase from 2 to 6 at the same timing. In this case, in the conventional technique in which overdrive driving is not performed, the applied voltage of the front panel 104 and the applied voltage of the back panel 105 increase from 3 V to 3.8 V at the timing when the gradation value increases from 2 to 6. As a result, as shown in FIG. 7, the transmittance of the front panel 104 and the transmittance of the back panel 105 change with time (increase). In FIG. 7, the transmittance 2 is the target transmittance according to the gradation value 2, and the transmittance 6 is the target transmittance according to the gradation value 6. Since the response speed of the back panel 105 is faster than the response speed of the front panel 104, in FIG. 7, the transmittance of the back panel 105 is before the timing at which the transmittance of the front panel 104 reaches the target transmittance 6. The target transmittance of 6 is reached. Then, the image quality of the display image (the image displayed on the display surface) deteriorates due to such a shift in timing (timing at which the transmittance reaches the target transmittance).

  A specific example in which the image quality deterioration occurs will be described. FIG. 8 is a diagram illustrating an example of an image represented by target image data. In the example of FIG. 8, a patch having a gradation value 6 exists in the center of the background having the gradation value 2. FIG. 9 is a diagram illustrating an example of a distribution of display luminance (display surface luminance; display image luminance), a transmittance distribution of the front panel 104, and a transmittance distribution of the back panel 105. The distribution in FIG. 9 is a distribution when the image in FIG. 8 is displayed, and is a distribution on the broken line 800 in FIG. Since the transmittance of the back panel 105 is controlled in accordance with the processed image data (image data after the spatial low-pass processing), the spatial high frequency component of the transmittance is suppressed in the back panel 105. Here, it is assumed that the patch scrolls in the horizontal direction (the direction along the broken line 800). In that case, each distribution changes over time from the distribution of FIG. 9 to the distribution of FIG. Specifically, since the response speed of the back panel 105 is faster than the response speed of the front panel 104, a deviation occurs between the transmittance distribution of the front panel 104 and the transmittance distribution of the back panel 105. Luminance loss (image quality degradation) occurs.

  Therefore, in this embodiment, the overdrive drive of the front panel 104 is performed so that the difference between the response speed of the front panel 104 and the response speed of the back panel 105 is reduced to a predetermined threshold value or less. For example, when the gradation value changes with time as shown in FIG. 6, the applied voltage is controlled as shown in FIG. Specifically, in step S116 of FIG. 3, an overdrive voltage 5V higher than the normal voltage 3.8V is determined as the applied voltage of the front panel 104. In step S117, the determined overdrive voltage 5V is notified to the front panel drive circuit unit 102. Then, as shown in FIG. 11, overdrive driving is performed in which an overdrive voltage 5V higher than the normal voltage 3.8V is temporarily applied to the front panel 104 in one control period. As a result, as shown in FIG. 12, the response speed of the front panel 104 is increased, the difference between the response speed of the front panel 104 and the response speed of the back panel 105 is reduced, and the above-described image quality deterioration is reduced.

  As described above, according to the present embodiment, the applied voltage of the front panel 104 is set to the target image data so that the response speed difference between the front panel 104 and the back panel 105 is equal to or less than a predetermined threshold in one control period. The voltage is temporarily controlled to be higher than the voltage corresponding to. Thereby, it is possible to suppress deterioration in the image quality of the display image due to the difference in response speed between the front panel 104 and the back panel 105. In order to further suppress image quality deterioration, it is preferable to perform overdrive driving of the front panel 104 so that the response speed of the front panel 104 substantially matches the response speed of the back panel 105.

As described above, in step S111 of FIG. 3, even if the temperature of the front panel 104 and the temperature of the back panel 105 are estimated based on the light emission luminance of the backlight module 106 and the external temperature of the display device 100. Good. In this case, for example, the display device 100 includes a temperature sensor that detects the external temperature of the display device 100 and a light emission control unit that controls the light emission luminance of the backlight module 106 in accordance with a user operation. And the control part 109 acquires the estimation result as temperature information by estimating the temperature of the front panel 104 and the temperature of the back panel 105 based on external temperature and user operation. The user operation is an operation in which the user designates the upper limit of display brightness using an image quality adjustment menu screen or the like. The light emission luminance of the backlight module 106 is controlled to be lower as the upper limit of the display luminance is lower. The control unit 109 controls the temperature of the front panel 104 and the back panel based on a predetermined correspondence relationship between the light emission luminance of the backlight module 106, the external temperature of the display device 100, the temperature of the front panel 104, and the temperature of the back panel 105. A temperature of 105 can be estimated.

  Consider a case where the light emission luminance of the backlight module 106 is low. In this case, the temperature rise of the back panel 105 due to the temperature of the backlight module 106, the light emitted from the backlight module 106, and the like is small. For this reason, the temperature difference between the front panel 104 and the back panel 105 is small. As described above, when at least one of the temperature of the front panel 104 and the temperature of the back panel 105 is low, a response speed difference between the front panel 104 and the back panel 105 is likely to occur as compared with the case where the temperature is not so. When the external temperature is low, the temperature of the front panel 104 and the temperature of the back panel 105 are low. Therefore, even if the temperature difference between the front panel 104 and the back panel 105 is small, there is a possibility that overdrive driving is necessary. high. On the other hand, when the temperature of the front panel 104 and the temperature of the back panel 105 are high, the response speed difference between the front panel 104 and the back panel 105 is less likely to occur than when the temperature is not so. When the external temperature is high, the temperature of the front panel 104 and the temperature of the back panel 105 are high. Therefore, if the temperature difference between the front panel 104 and the back panel 105 is small, it is unlikely that overdrive driving is required. .

  In step S114, whether or not overdrive driving is necessary is determined based on whether or not the difference between the response speed of the front panel 104 and the response speed of the back panel 105 is equal to or greater than a predetermined threshold. Not limited to this. For example, it may be determined whether or not overdrive driving is necessary based on whether or not the difference between the temperature of the front panel 104 and the temperature of the back panel 105 is greater than or equal to a threshold value. Specifically, when the temperature of the back panel 105 is higher than the temperature of the front panel 104 by a threshold value or more, the front panel 104 is overdriven. In other words, when the temperature of the back panel 105 is higher than the temperature of the front panel 104 by a threshold value or more, the voltage applied to drive the front panel 104 (applied voltage) is higher than when the temperature is not so. Panel 104 is controlled.

  The threshold value to be compared with the response speed difference or the temperature difference predetermined depends on any of the temperature of the front panel 104, the temperature of the back panel 105, the external temperature of the display device 100, and the light emission amount of the backlight module 106. It may be a changing value. As described above, the higher the temperature of each panel, the smaller the response speed difference between the panels based on the temperature difference between the panels. That is, the degree of influence of the temperature difference between the panels on the response speed difference between the panels is smaller as the temperature of each panel is higher. Therefore, when any of the temperature of the front panel 104, the temperature of the back panel 105, the external temperature of the display device 100, and the light emission amount of the backlight module 106 is higher than a predetermined value, the threshold value is set larger than the case where it is not so. Is possible. A larger value may be set as the threshold value as any one of the temperature of the front panel 104, the temperature of the back panel 105, the external temperature of the display device 100, and the light emission amount of the backlight module 106 increases.

  In this embodiment, the case where the temperature of the back panel 105 is higher than the temperature of the front panel 104 is illustrated, but overdrive driving is similarly performed when the temperature of the front panel 104 is higher than the temperature of the back panel 105. Can be done. In this case, when the temperature of the front panel 104 is higher than the temperature of the back panel 105 by a threshold value or more, the back panel 105 is overdriven.

  Also, if the relationship between the panel temperature and the response speed is not the relationship “the higher the temperature, the faster the response speed” as described above, but the relationship “the higher the temperature, the lower the response speed”, Is the opposite. That is, when the temperature of the back panel 105 is lower than the temperature of the front panel 104 by a threshold or more, the front panel 104 is overdriven. Alternatively, when the temperature of the front panel 104 is lower than the temperature of the back panel 105 by a threshold value or more, the back panel 105 is overdriven.

<Example 2>
Embodiment 2 of the present invention will be described below. Note that points (configuration and processing) different from those in the first embodiment will be described in detail, and descriptions of the same points as those in the first embodiment will be omitted.

  The response speed of the transmissive panel may depend on the start gradation value (the gradation value before the change) and the end gradation value (the gradation value after the change). In general, the response speed corresponding to a gradation change from an intermediate gradation value to another intermediate gradation value is a low gradation value (for example, 0) or a high gradation value (for example, an upper limit value) from the intermediate gradation value. It is slower than the response speed corresponding to the gradation change. An example of the correspondence between the gradation change and the response speed is shown in FIG. Here, a case where the start gradation value is 5 is considered. In FIG. 13, the response speed when the end gradation value is 0 is 15 msec, but the response speed when the end gradation value is 3 is 30 msec.

  In a display device having two transmissive panels, when the same gamma value is set for each transmissive panel, an image is displayed with a gamma curve (gradation characteristic) that is the square of the set gamma value. Therefore, two gammas different from each other are set so that a value obtained by taking the square root of the desired gamma value is set in each liquid crystal panel, or a desired gamma curve is obtained by combining (combining) the gamma curves of each transmission panel. The value may be set for two transparent panels. FIG. 14 shows an example of the gradation characteristics of the front panel 104 and the back panel 105. The horizontal axis in FIG. 14 indicates the input gradation value (the gradation value of the target image data), and the vertical axis in FIG. 14 is obtained by converting the input gradation value according to the output gradation value (set gradation characteristics). (Tone value). The front panel 104 is assigned gradation characteristics in which the output gradation value changes linearly with respect to the change in the input gradation value so that the same output gradation value as the input gradation value can be obtained. . For the back panel 105, the change in the input gradation value is such that desired gradation characteristics can be obtained by combining the gradation characteristics of the front panel 104 and the gradation characteristics of the back panel 105. Thus, a gradation characteristic in which the output gradation value changes nonlinearly is assigned.

  Therefore, when the gradation characteristics of the front panel 104 are different from the gradation characteristics of the back panel 105, the time change of the output gradation value with respect to the time change of the input gradation value is changed between the front panel 104 and the back panel 105. It will be different. For this reason, when overdrive driving is performed without considering the time change of the output gradation value of the front panel 104 and the time change of the output gradation value of the back panel 105, it is caused by the difference of the time change of the output gradation value. The response speed difference may not be reduced with high accuracy.

  FIG. 15 is a block diagram illustrating an example of the configuration of the display device 200 according to the present embodiment. 15, the same reference numerals as those in FIG. 2 are attached to the same functional units as those in FIG. 2 (Example 1).

The gradation distribution unit 210 generates front image data and back image data from the target image data acquired by the image data input unit 101. Specifically, the gradation distribution unit 210 decodes target image data. Then, the gradation distribution unit 210 generates front image data by converting the gradation value (input gradation value) of each pixel of the target image data into the output gradation value according to the gradation characteristics of the front panel 104. . The gradation distribution unit 210 generates back image data by converting the gradation value (input gradation value) of each pixel of the target image data into an output gradation value according to the gradation characteristics of the back panel 105. . Then, the gradation distributing unit 210 outputs the front image data to the front panel drive circuit unit 102 and outputs the back image data to the back panel drive circuit unit 103 (distribution of gradation values of target image data). Further, the gradation distribution unit 210 outputs the front image data and the back image data to the control unit 109.

  The front panel drive circuit unit 102 uses front image data instead of target image data, and the back panel drive circuit unit 103 uses back image data instead of target image data. For this reason, the transmittance of the front panel 104 is controlled by applying a voltage based on the front image data, and the transmittance of the back panel 105 is controlled by applying a voltage based on the back image data.

  The control unit 109 performs the same process as in the first embodiment. However, the control unit 109 determines the applied voltage to the front panel 104 by further considering the change in the gradation of the front image data and the change in the gradation of the back image data.

  An example in which the gradation value of the target image data changes from 2 to 6 over time will be described. Here, it is assumed that the temperature of the front panel 104 is 23 ° C. and the temperature of the back panel 105 is 25 ° C. The gradation characteristics of the front panel 104 and the gradation characteristics of the back panel 105 are not particularly limited, but these gradation characteristics are assumed to be the gradation characteristics of FIG. For simplification, the correspondence between the gradation change of the front image data and the response speed of the front panel 104 and the correspondence relation between the gradation change of the back image data and the response speed of the back panel 105 are shown in FIG. It is assumed that the relationship is However, the correspondence between them is not particularly limited, and the correspondence between the gradation change of the front image data and the response speed of the front panel 104 is the correspondence between the gradation change of the back image data and the response speed of the back panel 105. And may be different.

  In step S112 of FIG. 3, the control unit 109 determines the response speed of the front panel 104 corresponding to the gradation change of the front image data and the response speed of the back panel 105 corresponding to the gradation change of the back image data. Further processing. In step S113, the control unit 109 further performs a process of calculating the difference between the two response speeds determined based on the gradation change.

  When the gradation value of the target image data changes with time from 2 to 6 according to the gradation characteristics of FIG. 14, the gradation value of the front image data changes with time from 2 to 6, and the gradation value of the back image data changes from 4. Time changes to 7. In the correspondence relationship of FIG. 13, the response speed in the case of the start gradation value 2 and the end gradation value 6 is 30 msec, and the response speed in the case of the start gradation value 4 and the end gradation value 7 is 25 msec. Therefore, it is determined that the response speed of the front panel 104 corresponding to the gradation change of the front image data is 30 msec, and the response speed of the back panel 105 corresponding to the gradation change of the back image data is 25 msec. Then, 5 msec (= 30 msec−25 msec) is calculated as the response speed difference based on the gradation change.

  Further, as described above, the temperature of the front panel 104 is 23 ° C., and the temperature of the back panel 105 is 25 ° C. Therefore, it is determined from the response speed information of FIG. 4 that the response speed of the front panel 104 is 30 msec, and the response speed of the back panel 105 is determined to be 28 msec. Then, 2 msec (= 30 msec−28 msec) is calculated as the response speed difference based on the temperature difference.

In step S114 of FIG. 3, a total of 7 msec of the response speed difference 5 msec based on the gradation change and the response speed difference 2 msec based on the temperature difference is compared with a predetermined threshold 5 msec. Since the total 7 msec is larger than the predetermined threshold value 5 msec, the process proceeds to step S116, and the front panel 104 is overdriven. Front panel 1
When the gradation characteristic of 04 is equal to the gradation characteristic of the back panel 105, a response speed difference of 2 msec based on the temperature difference occurs, but a response speed difference based on the gradation change does not occur. Since the response speed difference 2 msec based on the temperature difference is equal to or less than the predetermined threshold 5 msec, the process proceeds to step S115 and overdrive driving is not performed.

  As described above, according to the present embodiment, overdrive driving is performed in consideration of the gradation change of the front image data and the gradation change of the back image data. Thereby, it is possible to suppress the deterioration of the image quality of the display image due to the difference in response speed between the front panel 104 and the back panel 105 with higher accuracy.

  Each functional unit of the first and second embodiments may or may not be individual hardware. The functions of two or more functional units may be realized by common hardware. Each of a plurality of functions of one functional unit may be realized by individual hardware. Two or more functions of one functional unit may be realized by common hardware. Each functional unit may be realized by hardware or not. For example, the apparatus may include a processor and a memory in which a control program is stored. The functions of at least some of the functional units included in the apparatus may be realized by the processor reading and executing the control program from the memory.

  Embodiments 1 and 2 are merely examples, and a configuration obtained by appropriately modifying or changing the configuration of Embodiments 1 and 2 within the scope of the gist of the present invention is also included in the present invention. A configuration obtained by appropriately combining the configurations of Examples 1 and 2 is also included in the present invention.

  For example, an overdrive circuit may be mounted on the back panel drive circuit unit 103 so that both the front panel 104 and the back panel 105 are overdriven. For example, the response speed of the back panel 105 may be increased by overdrive driving of the back panel 105. Then, the overdrive drive of the front panel 104 may be performed so that the response speed of the front panel 104 matches the response speed of the back panel 105 (response speed after overdrive driving).

  Without considering the temperature of the front panel 104 and the temperature of the back panel 105, only the gradation change of the front image data and the gradation change of the back image data may be considered. That is, the response speed difference based on the gradation change may be considered without considering the response speed difference based on the temperature difference. Other response speed differences may be considered. For example, a response speed difference based on the difference between the type of the front panel 104 and the type of the back panel 105 may be considered. In that case, a response speed difference based on a temperature difference, a response speed difference based on a gradation change, or the like may or may not be considered.

  The determination of the response speed (step S112 in FIG. 3), the calculation of the response speed difference (step S113), etc. may not be performed. The applied voltages of the front panel 104 and the back panel 105 may be controlled according to temperature information, external temperature, user operation, etc. without performing these processes.

  The display device 100 may have three or more transmissive panels. In that case, at least one transmissive panel may be overdriven so that a difference in response speed between three or more transmissive panels is reduced.

<Other examples>
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 100,200: Display apparatus 102: Front panel drive circuit part 103: Back panel drive circuit part 104: Front panel 105: Back panel 106: Backlight module 109: Control part

Claims (20)

A light emitting unit;
A first transmissive panel whose transmittance is controlled by an applied voltage and which transmits light emitted from the light emitting unit;
A second transmissive panel that displays an image on a display surface by transmitting the light that is transmitted from the light emitting unit and transmitted through the first transmissive panel, the transmittance being controlled by an applied voltage;
Control means for periodically controlling the voltage applied to the first transmissive panel and the voltage applied to the second transmissive panel based on target image data;
With
In one cycle in which each of the voltage applied to the first transmissive panel and the voltage applied to the second transmissive panel is controlled, the control means includes the response speed of the first transmissive panel and the second transmissive panel. The voltage applied to the second transmissive panel is temporarily controlled to a voltage higher than the voltage corresponding to the target image data so that the difference from the response speed is less than a predetermined value. Display device. The control means controls a voltage applied to the second transmissive panel so that a response speed of the second transmissive panel substantially matches a response speed of the first transmissive panel. The display device described in 1. In the one cycle, the control means temporarily controls a voltage applied to the second transmission panel to a voltage higher than a voltage corresponding to the target image data, and a voltage corresponding to the target image data The display device according to claim 1, wherein the display device is controlled as follows. Obtaining means for obtaining temperature information related to the temperature of the first transmissive panel and the temperature of the second transmissive panel;
The display device according to claim 1, wherein the control unit controls a voltage applied to the second transmission panel based on at least the temperature information. A difference in response speed between the first transmissive panel and the second transmissive panel when a voltage applied to the second transmissive panel is not temporarily controlled to a voltage higher than a voltage corresponding to the target image data. A judgment means for judging based on at least the temperature information,
The display device according to claim 4, wherein the control unit controls a voltage applied to the second transmission panel according to the response speed difference. Detecting means for detecting an external temperature of the display device;
Light emission control means for controlling the light emission luminance of the light emitting unit according to a user operation;
Further comprising
The acquisition means acquires the estimation result as the temperature information by estimating the temperature of the first transmission panel and the temperature of the second transmission panel based on the external temperature and the user operation. The display device according to claim 4, wherein the display device is characterized. Generating means for generating first image data and second image data from the target image data;
The transmittance of the first transmission panel is controlled by applying a voltage based on the first image data,
The transmittance of the second transmissive panel is controlled by applying a voltage based on the second image data,
The control means controls a voltage applied to the second transmissive panel based on at least a gradation change of the first image data and a gradation change of the second image data. The display device according to any one of 1 to 6. 2. The control unit according to claim 1, further comprising: temporarily controlling a voltage applied to the first transmission panel to a voltage higher than a voltage corresponding to the target image data in the one cycle. The display apparatus of any one of -7. A light emitting unit;
A first transmissive panel that transmits light emitted from the light emitting unit at a transmittance according to an applied voltage;
A second transmissive panel that transmits light transmitted through the first transmissive panel at a transmittance according to an applied voltage and displays an image on a display surface;
Control means for controlling the applied voltage of the first transmissive panel and the applied voltage of the second transmissive panel based on target image data;
Obtaining means for obtaining a parameter related to a difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel;
With
When the difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel is equal to or greater than a predetermined value, the control means applies the voltage applied to the first transmissive panel and the application of the second transmissive panel. One of the voltages is controlled to a higher applied voltage than the case where it is not so. A light emitting unit;
A first transmissive panel whose transmittance is controlled by an applied voltage and which transmits light emitted from the light emitting unit;
A second transmissive panel that displays an image on a display surface by transmitting the light that is transmitted from the light emitting unit and transmitted through the first transmissive panel, the transmittance being controlled by an applied voltage;
A display device control method comprising:
A control step of periodically controlling a voltage applied to the first transmission panel and a voltage applied to the second transmission panel based on target image data,
In the control step, the response speed of the first transmissive panel and the second transmissive panel are controlled in one cycle in which each of the voltage applied to the first transmissive panel and the voltage applied to the second transmissive panel is controlled. The voltage applied to the second transmissive panel is temporarily controlled to a voltage higher than the voltage corresponding to the target image data so that the difference from the response speed is less than a predetermined value. Display device control method. The voltage applied to the second transmissive panel is controlled in the control step so that a response speed of the second transmissive panel substantially matches a response speed of the first transmissive panel. The control method of the display apparatus as described in any one of Claims 1-3. In the control step, the voltage applied to the second transmission panel in the one cycle is temporarily controlled to a voltage higher than the voltage corresponding to the target image data, and the voltage corresponding to the target image data The control method of the display device according to claim 10 or 11, wherein An acquisition step of acquiring temperature information regarding the temperature of the first transmission panel and the temperature of the second transmission panel;
13. The display device control method according to claim 10, wherein, in the control step, a voltage applied to the second transmissive panel is controlled based on at least the temperature information. A difference in response speed between the first transmissive panel and the second transmissive panel when a voltage applied to the second transmissive panel is not temporarily controlled to a voltage higher than a voltage corresponding to the target image data. And a determination step for determining based on at least the temperature information,
14. The method of controlling a display device according to claim 13, wherein in the control step, a voltage applied to the second transmissive panel is controlled according to the response speed difference. A detection step of detecting an external temperature of the display device;
A light emission control step of controlling the light emission luminance of the light emitting unit according to a user operation;
Further comprising
In the obtaining step, the estimation result is obtained as the temperature information by estimating the temperature of the first transmission panel and the temperature of the second transmission panel based on the external temperature and the user operation. The method for controlling a display device according to claim 13 or 14, characterized in that: A generation step of generating first image data and second image data from the target image data;
The transmittance of the first transmission panel is controlled by applying a voltage based on the first image data,
The transmittance of the second transmissive panel is controlled by applying a voltage based on the second image data,
The voltage applied to the second transmissive panel is controlled in the control step based on at least a gradation change of the first image data and a gradation change of the second image data. The control method of the display apparatus of any one of 10-15. 11. The control step further includes temporarily controlling a voltage applied to the first transmission panel to a voltage higher than a voltage corresponding to the target image data in the one cycle. The control method of the display apparatus of any one of -16. A light emitting unit;
A first transmissive panel that transmits light emitted from the light emitting unit at a transmittance according to an applied voltage;
A second transmissive panel that transmits light transmitted through the first transmissive panel at a transmittance according to an applied voltage and displays an image on a display surface;
A display device control method comprising:
A control step of controlling the applied voltage of the first transmissive panel and the applied voltage of the second transmissive panel based on target image data;
Obtaining a parameter related to the difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel;
Have
In the control step, when the difference between the temperature of the first transmissive panel and the temperature of the second transmissive panel is equal to or greater than a predetermined value, the applied voltage of the first transmissive panel and the application of the second transmissive panel A control method for a display device, characterized in that either one of the voltages is controlled to a higher applied voltage than in the other case.   The program for making a computer perform each step of the control method of the display apparatus of any one of Claims 10-18.   A computer-readable storage medium storing a program for causing a computer to execute each step of the display device control method according to claim 10.

Images