JP5634148B2 - Image display device and control method thereof - Google Patents

Description

The present invention relates to an image display device and a control method thereof.

Market demand for brightness and color reproduction capability of liquid crystal display devices using liquid crystal panels is becoming more sophisticated and diversified. Cold cathode fluorescent tubes are the mainstream of light sources for backlights of liquid crystal display devices, but light emitting diodes (LEDs) that are superior in luminous efficiency compared to cold cathode fluorescent tubes
Has begun to be adopted.
Light sources for backlights using LEDs are roughly divided into two types: white backlights and RGB backlights. The white backlight is composed of a monochromatic white LED. The RGB backlight is composed of LEDs of three colors, red, green, and blue, and obtains white light by mixing these colors. The white backlight has an advantage that high luminance can be easily obtained as compared with the RGB backlight. On the other hand, the RGB backlight has an advantage that it can easily reproduce a wide color gamut compared to the white backlight.

  Patent Literature 1 discloses a light source control technique for switching between a white backlight and an RGB backlight based on the image quality mode setting of an image displayed on a liquid crystal panel in order to appropriately set the color reproduction capability of the liquid crystal display device. Yes.

JP 2007-264659 A

In a liquid crystal display device provided with a plurality of light sources (light emitting means) typified by a white backlight and an RGB backlight, if the use frequency of the light sources is biased, only the light sources that are frequently used will deteriorate in luminance. As a result, there is a problem that the liquid crystal display device cannot exhibit the desired performance and cannot be used due to the deterioration of the other light source, even though one of the light sources can be used.
Accordingly, an object of the present invention is to provide a technique for reducing unevenness of deterioration of light emitting means and enabling high-quality display over a long period in an image display apparatus including a plurality of light emitting means. .

A first aspect of the present invention includes a plurality of input units to which image data is input, a first light emitting unit configured by a light emitting element capable of white lighting , and a plurality of light emitting elements of different colors, A display panel capable of displaying an image by light emitted from either the first light-emitting means or the second light-emitting means, the second light-emitting means capable of lighting white by turning on a plurality of light-emitting elements A storage unit that records the frequency of use of each of the first light emitting unit and the second light emitting unit, and a calibration unit that performs calibration individually for each input unit according to a specified target value For each of the input units, a light emitting unit capable of displaying a target value designated at the time of calibration is used for image display, out of the first light emitting unit and the second light emitting unit . Possible luminous hand Determining means for determining as said first when both of the light emitting means and the second light emitting means is input available for the display image is selected, the second light emitting and the first light emitting means comparing the frequency of use of means to emit a light emitting means more infrequent, the first light emitting means and said one of the light emitting means only input unit usable for the display image of the second light emitting means If the chosen, the selected input unit, and a control means for the light emitting means can be used for image display, the possess, the calibration means is possible to display the specified target value When possible light-emitting means are determined, and when it is determined that the target value can be displayed by both the first light-emitting means and the second light-emitting means, the first light-emitting means and the second light-emitting means
Provided is an image display device that executes calibration for each light emitting means .

A second aspect of the present invention includes a plurality of input units to which image data is input, a first light-emitting unit configured by a light-emitting element capable of white lighting , and a plurality of light-emitting elements of different colors, A display panel capable of displaying an image by light emitted from either the first light-emitting means or the second light-emitting means, the second light-emitting means capable of lighting white by turning on a plurality of light-emitting elements A recording step of recording the usage frequencies of the first light emitting unit and the second light emitting unit in the storage unit, and the input unit. A calibration step for performing calibration individually according to a specified target value for each of the first light emitting means and the second light emitting means for each of the input units . The And using the light-emitting means capable of displaying the target value, and determining step of determining a light emission unit which can be used in image display, both of said first light emitting means and said second light emitting means in the display image When a possible input unit is selected, the use frequency of the first light-emitting means and the second light-emitting means are compared, and the light-emitting means having the lower use frequency is caused to emit light. control step only one of the light emitting means when the input unit available is selected in the display image, in which the selected input unit, causes the light emitting means can be used to image display of said second light emitting means If, have a, in the calibration step, it is determined emission means capable of displaying the specified target value, the first of said target value in both of the light emitting means and the second light emitting means When it is determined that can be displayed Each provides a method for controlling an image display apparatus capable of performing a calibration for said second light emitting means and the first light emitting means.

According to the present invention, in an image display device including a plurality of light emitting means, it is possible to reduce the bias of deterioration of the light emitting means and perform high-quality display over a long period.

1 is a block diagram illustrating a main configuration of a liquid crystal display device. The example of a flow of backlight lighting control. FIG. 6 is a diagram illustrating a connection between a liquid crystal display device, a video input device, and a colorimeter according to a second embodiment. The example of an operation | movement flow of calibration PC at the time of a calibration operation | movement. An example of an operation flow of a liquid crystal display device during a calibration operation. 10 is an example of a light source candidate selection table according to the second embodiment. 10 is an example of a light source candidate storage table according to the second embodiment. 10 is an example of a light source candidate storage table according to the third embodiment.

  The present invention includes a white backlight (first backlight) composed of white light emitting diodes and an RGB backlight (second backlight) composed of light emitting diodes of three colors of red, green and blue. The present invention relates to a liquid crystal display device provided. Specifically, the present invention relates to a backlight lighting control technique in such a liquid crystal display device. Hereinafter, preferred embodiments of the liquid crystal display device and the control method thereof according to the present invention will be described.

[Example 1]
Embodiment 1 of the present invention will be described below with reference to the drawings. Example 1 is an example in which the usage frequencies of the white backlight and the RGB backlight are compared, and the backlight with the lower usage frequency is turned on preferentially.

  FIG. 1 is a block diagram showing a main configuration of a liquid crystal display device. The liquid crystal display device 101 includes a liquid crystal panel 107 and two types of light sources, an RGB backlight 114 and a white backlight 115. The liquid crystal display device 101 also includes a liquid crystal driving unit 106 that drives the liquid crystal panel 107, a backlight driving unit 113 that drives both backlights, and a system control unit 112 that serves as a control unit that controls the entire apparatus. Further, the liquid crystal display device 101 includes a video input unit (1) 102, a video input unit (2) 103, an input control unit 104, a video processing unit 105, a data transmission / reception unit 108, a data transmission / reception control unit 109, a storage unit 110, and a timer unit. 111, a power button 118, and an input switching button 119.

First, the basic video display function of the liquid crystal display device 101 will be described.
(Processing from power on to video display)
When the user presses the power button 118, a power-on request is sent to the system control unit 112. When the system control unit 112 detects a power-on request, the system control unit 112 starts energizing each block in the liquid crystal display device 101.
After energization, the system control unit 112 reads the video input selection information from the storage unit 110 when the power was last turned off. The video input selection information is information for identifying whether the video being displayed is an input from the video input unit (1) 102 or the video input unit (2) 103. The system control unit 112 determines which video input to be selected from the video input unit (1) 102 and the video input unit (2) 103, and requests the input control unit 104 to switch the input. When the switching is completed, the system control unit 112 updates the video input selection information and stores it in the storage unit 110. Although two video input units are shown in FIG. 1, the number of video input units may be one or more than two.

  In addition, the system control unit 112 issues a backlight lighting control request to the backlight driving unit 113 and turns on one of the RGB backlight 114 and the white backlight 115. A method for determining which of the RGB backlight 114 and the white backlight 115 is used will be described later.

  The input control unit 104 transmits the video signal input from the selected video input unit to the video processing unit 105. The video processing unit 105 generates display data and timing signals suitable for the display resolution, the number of display colors, and the refresh rate of the liquid crystal panel 107 based on the video signal, and transmits them to the liquid crystal driving unit 106. The liquid crystal driving unit 106 converts the data received from the video processing unit 105 into a control signal for the liquid crystal panel 107 and controls the liquid crystal panel 107. As a result, an image is displayed on the liquid crystal panel 107.

(Switching video input)
When the user presses the input switching button 119, an input switching request is sent to the system control unit 112. When detecting an input switching request, the system control unit 112 reads video input selection information from the storage unit 110. The system control unit 112 determines which video input is selected according to the input switching request, and requests the input control unit 104 to switch the input. When the switching is completed, the system control unit 112 updates the video input selection information and stores it in the storage unit 110.

(Recording frequency of backlight usage)
The usage frequency information of the RGB backlight 114 and the white backlight 115 is recorded in the storage unit 110. The system control unit 112 creates / updates usage frequency information. Specifically, when any one of the backlights starts lighting, the system control unit 112 measures a lighting time (usage time) using the timer unit 111, and uses the storage unit 110 based on the measurement result. Update frequency information. The update timing may be at power-off, video input switching, channel switching, or the like, or may be updated at regular time intervals.

  Here, the usage frequency information may be accumulated usage time (total usage time), or information calculated from usage time and luminance (light emission amount). In the former case, the system control unit 112 has only to accumulate and add the lighting time measured by the timer unit 111 to the usage frequency information in the storage unit 110, and there is an advantage that the update process is simple. In the latter case, the system control unit 112 does not accumulate the usage time as it is, but accumulates the coefficient corresponding to the luminance of the backlight multiplied by the usage time. The latter method has an advantage that backlight deterioration can be more accurately evaluated. When the backlight brightness is uniformly adjusted according to the display mode, user settings, installation environment, etc., the coefficient can be calculated based on the adjustment value. Alternatively, when the backlight luminance changes dynamically or partially depending on the video, the coefficient can be calculated from the video data of each frame.

(Backlight lighting control)
A flow of backlight control of the liquid crystal display device 101 will be described with reference to FIG. The processing in FIG. 2 may be performed at any timing. However, since the color and brightness of the displayed video may change when the backlight is switched, for example, power on, video input switching, channel switching, etc. It is preferable to carry out at a timing such as a scene change.

In step S <b> 701, the system control unit 112 reads the light source candidate storage table from the storage unit 110. The light source candidate storage table is data in which types of light sources (backlights) that can be used for video display are set. In this embodiment, in principle, both the RGB backlight 114 and the white backlight 115 are set as possible light source candidates. However, when one of the backlights cannot be used, only the other backlight may be set as a usable light source in the light source candidate storage table. For example, when one of the backlights becomes unusable due to a failure or deterioration, or when a setting is made such that only one of the backlights is preferentially used according to user settings.

  In step S702, the backlight switching determination unit 117 in the system control unit 112 starts the light source determination process based on the setting values in the light source candidate storage table. If both the RGB backlight 114 and the white backlight 115 can be used, the backlight switching determination unit 117 reads the usage frequency information of each backlight from the storage unit 110 and compares them in step S703. In step S704, the backlight switching determination unit 117 determines the backlight with the lower usage frequency as the light source to be used. On the other hand, when only one of the RGB backlight 114 and the white backlight 115 is usable in step S702, the backlight switching determination unit 117 determines a usable backlight as a use light source (step S705). , S706).

  In step S707, the backlight switching determination unit 117 requests the backlight driving unit 113 to switch the light source, and starts lighting the desired backlight. In step S708, the backlight switching determination unit 117 starts measuring the lighting time of the lit backlight by the timer unit 111.

  According to the configuration of the present embodiment described above, when both the RGB backlight 114 and the white backlight 115 can be used for video display, the backlight with the lower usage frequency is preferentially used. This lighting control reduces the uneven use frequency of the backlight, and as a result, it is possible to prevent the deterioration of only one backlight. Therefore, high-quality video display can be realized over a long period of time.

[Example 2]
Next, a second embodiment of the present invention will be described. The second embodiment is an example in which the type of backlight that can be used is set for each video input unit, and the light source to be used and lighting control are performed when the video input unit is switched. The basic configuration of the liquid crystal display device is the same as that of the first embodiment (FIG. 1).

(Calibration)
First, a calibration operation by the liquid crystal display device 101 and a video input device connected thereto will be described. Here, the calibration means that the liquid crystal display device 101 is adjusted so that the video from the video input device can be displayed in the correct color as much as possible. As the video input device, for example, a personal computer, a game machine, a digital camera, a digital video camera, a broadcast receiver, a video playback device, and the like are assumed.

  FIG. 3 is a diagram showing a connection configuration of the liquid crystal display device 101, personal computers (PC (1) 201, PC (2) 202) as video input devices, and a colorimeter 203 used during calibration.

  Calibration of the liquid crystal display device 101 can be performed individually for each video input unit. The calibration control unit 116 in the system control unit 112 of the liquid crystal display device 101, calibration software executed by the PCs 201 and 202 connected to each video input unit, and the colorimeter 203 cooperate to perform calibration. Is executed. Hereinafter, PC (1) 201 and PC (2) 202 that operate during calibration are collectively referred to as “calibration PC”.

  The colorimeter 203 has a function of measuring three values of X, Y, and Z called tristimulus values from the display screen of the liquid crystal display device 101 and outputting the measured values to the calibration PC. The colorimeter 203 is installed and used on the display surface of the liquid crystal display device 101 during calibration. When the PC (1) 201 and the liquid crystal display device 101 are calibrated, the colorimeter 203 and the PC (1) 201 are connected. At the time of calibration of the PC (2) 202 and the liquid crystal display device 101, the colorimeter 203 and the PC (2) 202 are connected.

  4 shows an example of the operation flow of the calibration PC during the calibration operation, and FIG. 5 shows an example of the operation flow of the liquid crystal display device 101 during the calibration operation. The process of FIG. 5 is executed by the calibration control unit 116 in the system control unit 112 of the liquid crystal display device 101. In this embodiment, the calibration control unit 116 corresponds to the calibration means of the present invention.

  In step S <b> 301 of FIG. 4, the calibration PC starts a calibration operation and transmits a calibration target value to the liquid crystal display device 101. The calibration target value includes, for example, a luminance value, a white point, a gamma value, and color gamut range information. The color gamut range information is information on a color gamut (Adobe RGB, sRGB, etc.) to be reproduced by the liquid crystal display device 101. After transmitting the calibration target value, the calibration PC waits for reception of a calibration preparation completion notification from the liquid crystal display device 101. Data transmission / reception between the liquid crystal display device 101 and the calibration PC is performed via the data transmission / reception unit 108. In this embodiment, a USB (Universal Serial Bus) is used for the data transmission / reception unit 108.

  In step S401 in FIG. 5, the calibration control unit 116 of the liquid crystal display device 101 receives the calibration target value. In step S <b> 402, the calibration control unit 116 determines a light source candidate for the backlight based on the received calibration target value and the light source candidate selection table stored in advance in the storage unit 110.

FIG. 6 shows an example of a light source candidate selection table. In this example, the luminance and the color gamut range in the calibration target value are used for selection of light source candidates. For example, when the luminance value included in the calibration target value is smaller than 100 cd / m ² and the color gamut range information is AdobeRGB, the light source candidate is determined as “RGB backlight”. When the luminance value included in the calibration target value is in the range of 100 to 400 cd / m ² and the color gamut range information is SMPTE-C, the light source candidate is determined as “RGB backlight or white backlight”. “RGB backlight or white backlight” means that either of two types of backlights can be used. In the example of FIG. 6, the RGB backlight is set as a light source candidate for AdobeRGB having a wide color gamut, and the white backlight is set as a light source candidate for a request for high luminance. When it is determined that either backlight can display the target luminance value and color gamut, two types of backlights are set as light source candidates.

  In step S403, the calibration control unit 116 transmits a calibration preparation completion notification together with the light source candidate information to the calibration PC.

In step S <b> 302 of FIG. 4, when the calibration PC receives a calibration preparation completion notification from the liquid crystal display device 101, thereafter, the calibration PC performs a calibration operation together with the liquid crystal display device 101. In step S303, the calibration PC transmits backlight instruction information for designating a backlight type used when executing calibration. When the light source candidate information received from the liquid crystal display device 101 is “RGB backlight”, the calibration PC executes calibration using the RGB backlight in step S304. If the light source candidate information is “white backlight”, calibration using the white backlight is executed in step S304. When the light source candidate information is “RGB backlight or white backlight”, calibration using the RGB backlight and calibration using the white backlight are sequentially executed in step S304.

  In step S404 of FIG. 5, when the calibration control unit 116 receives the backlight instruction information from the calibration PC, the calibration control unit 116 switches to the instructed backlight in step S405. In step S406, upon receiving a calibration execution request from the calibration PC, the calibration control unit 116 executes calibration in cooperation with the calibration PC in step S407.

  For example, a patch image for calibration input from the calibration PC is displayed on the screen of the liquid crystal display device 101, measured by the colorimeter 203, and the measured value is input to the calibration PC. The calibration PC calculates an adjustment value based on the difference between the target value and the measurement value, and adjusts the brightness or color of the patch image. The calibration PC repeats this adjustment until the difference between the target value and the measured value becomes smaller than a predetermined threshold value. The adjustment value obtained by the calibration is stored in the storage unit in the calibration PC or the storage unit 110 of the liquid crystal display device 101.

  In step S305 of FIG. 4, the calibration PC determines whether calibration for all light source candidates is completed. If completed, the calibration PC transmits a calibration completion notice to the liquid crystal display device 101 in step S306. If not completed, the process returns to step S303, and calibration using the other backlight is executed.

  In step S <b> 408 of FIG. 5, when the liquid crystal display device 101 receives the calibration completion notification, the liquid crystal display device 101 updates the light source candidate storage table stored in the storage unit 110. FIG. 7 shows an example of a light source candidate storage table applicable to this embodiment. In the light source candidate storage table, the light source candidate information determined by the above-described calibration operation and the presence / absence of calibration execution are described for each video input unit. In the example of FIG. 7, the calibration for the video input unit (1) has been executed, and the light source candidate is set to “RGB backlight”. On the other hand, calibration for the video input unit (2) has not been performed yet. For such a video input unit (2), “RGB backlight or white backlight” is set as a light source candidate.

(Backlight lighting control)
In the present embodiment, the type of backlight that can be used for each video input unit is set. Therefore, the backlight lighting control is performed at the timing when the power of the liquid crystal display device 101 is turned on or the video input unit is switched. Since the specific flow of lighting control is the same as that of Example 1 (FIG. 2), description is abbreviate | omitted here.

According to the configuration of the present embodiment described above, as in the first embodiment, the uneven use frequency of the backlight is reduced, and as a result, it is possible to prevent the deterioration of only one backlight. In addition, in this embodiment, since the light source candidates are set for each video input unit, it is possible to turn on an appropriate backlight with a simple process linked to the switching of the video input unit. Furthermore, since the light source candidates for each video input unit are determined according to the target values specified during calibration, the light source candidates can be used in a range that does not affect video reproduction in the desired luminance and color gamut. Light source switching can be performed. In addition, if a video input unit that has not been calibrated is selected, it is determined that both backlights can be used. This can be expected to further reduce the bias. Further, when both backlights are set as light source candidates, calibration is separately performed for the two backlights, so that the difference in video reproduction due to light source switching can be minimized.

[Example 3]
Next, a third embodiment of the present invention will be described. Example 3 is an example in which the type of backlight that can be used is set for each type of application that performs screen display, and the light source used is determined and the lighting control is performed based on the application type information acquired from the video input device. It is. The basic configuration of the liquid crystal display device is the same as that of the first embodiment (FIG. 1).

  The liquid crystal display device 101 receives application type information from a personal computer (PC) that is a video input device via the data transmission / reception unit 108. The application type information is information that can identify the application type that is currently being executed by the calibration PC, such as “image viewer”, “image editor”, and “Web browser”. When a plurality of applications are being executed, the PC transmits the application displaying the highest window as application type information.

  FIG. 8 shows an example of a light source candidate storage table applicable to the present embodiment. In the light source candidate storage table, appropriate light source candidate information is described for each application running on the PC. The liquid crystal display device 101 receives the light source candidate storage table from the PC via the data transmission / reception unit 108 and stores it in the storage unit 110.

  The backlight switching determination unit 117 according to the present embodiment performs backlight lighting control using the application type information received from the PC and the light source candidate storage table of FIG. The specific flow of lighting control is the same as that of the first embodiment (FIG. 2). For example, when the application type is an image editor, RGB backlight is used. When the application type is an image viewer or a web browser, the backlight switching determination unit 117 turns on the backlight that is used less frequently.

  When the application type is unknown or when the screen saver or the OS (Operating System) startup end screen is being displayed, the backlight switching determination unit 117 treats both the RGB backlight and the white backlight as usable. Good.

  According to the configuration of the present embodiment described above, as in the first embodiment, the uneven use frequency of the backlight is reduced, and as a result, it is possible to prevent the deterioration of only one backlight. Therefore, high-quality video display can be realized over a long period of time.

  107: Liquid crystal panel, 114: RGB backlight (second backlight), 115: White backlight (first backlight), 110: Storage unit, 112: System control unit, 117: Backlight switching determination unit

Claims (4)

A plurality of input units for inputting image data;
A first light emitting means comprising a light emitting element capable of white lighting;
A plurality of light emitting elements of different colors, a second light emitting means capable of white lighting by lighting the plurality of light emitting elements;
A display panel capable of displaying an image by light emitted from any of the first light emitting means and the second light emitting means;
A storage unit that records the frequency of use of each of the first light emitting unit and the second light emitting unit;
Calibration means for performing calibration individually for each input unit according to a specified target value;
For each of the input units, a light emitting unit capable of displaying a target value designated at the time of calibration among the first light emitting unit and the second light emitting unit can be used for image display. Determining means for determining as light emitting means;
When an input unit that can be used for image display by both the first light emitting means and the second light emitting means is selected, the frequency of use of the first light emitting means and the second light emitting means is compared. The light emitting means with lower frequency of use is caused to emit light, and when an input unit is selected in which only one of the first light emitting means and the second light emitting means can be used for image display, Control means for emitting light emitting means usable for image display of the selected input unit;
Have
The calibration unit determines the light emission hand stage capable of performing the display of the specified target value, it can be displayed both at the target value of the first light emitting means and the second light emitting means images display you characterized in that each performs calibration for the second light emitting means and the first light emitting means when it is determined that there. The determination means determines that both the first light emission means and the second light emission means can be used for image display with respect to an input unit that has not been calibrated. Item 4. The image display device according to Item 1 . The first unit is composed of a plurality of input units to which image data is input and a light emitting element capable of white lighting.
The second light emitting means, which is composed of one light emitting means and a plurality of light emitting elements of different colors, and can be lit white by turning on the plurality of light emitting elements, the first light emitting means, and the second light emitting means. A display panel capable of displaying an image by light emitted from any one of the light emitting means, and a storage unit, and a control method of an image display apparatus,
A recording step of recording usage frequencies of the first light emitting means and the second light emitting means in the storage unit;
A calibration step for performing calibration individually for each input unit according to a specified target value;
For each of the input units, a light emitting unit capable of displaying a target value designated at the time of calibration among the first light emitting unit and the second light emitting unit can be used for image display. A determination step of determining as a light emitting means;
When an input unit that can be used for image display by both the first light emitting means and the second light emitting means is selected, the frequency of use of the first light emitting means and the second light emitting means is compared. The light emitting means with lower frequency of use is caused to emit light, and when an input unit is selected in which only one of the first light emitting means and the second light emitting means can be used for image display, A control step of causing the selected input unit to emit light emitting means that can be used for image display; and
Have
Wherein in the calibration step, it is determined luminous hands stage capable of performing the display of the specified target value, said first light emitting means and the second on both of the light emitting means is capable of displaying the target value the method of images display you characterized in that if it is determined that each run of the calibration for the second light emitting means and the first light emitting means. In the determining step, it is determined that both the first light emitting unit and the second light emitting unit can be used for image display with respect to an input unit that is not calibrated. Item 4. A method for controlling an image display device according to Item 3 .

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