JP2016218403A - Transmission device, display device, and display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission device, a display device, and a display system with which it is possible to reduce the power consumption of a display device and cut down costs.SOLUTION: A video transmission device 1 comprises a frame memory 13, a comparison circuit 14, a refresh rate setting unit 15a, and a determination result addition unit 16. The frame memory 13 successively stores consecutive image data. The comparison circuit 14 compares the image data stored in the frame memory 13 with image data that follows the image data, and determines a portion that changed in both image data and a portion that did not change. The refresh rate setting unit 15a sets the refresh rate of the portion determined to have not changed by the comparison circuit 14 to lower than that of the portion determined to have changed. The determination result addition unit 16 adds the refresh rate set by the refresh rate setting unit 15a to the image data and transmits it to a display device 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transmission device, a display device, and a display system that transmit continuous image data constituting a video to a display device.

  In the display driving device described in Patent Document 1, a matching portion and a mismatching portion of image data that are continuously input are determined, a refresh rate of the matching portion is set low, and a refresh rate of the mismatching portion is set high. Yes. Thus, by partially performing low frequency driving, power consumption of the display driving device is reduced.

  In the image display system described in Patent Document 2, the image display device includes a frame memory that expands image data based on the header data, and the image data transmission device displays the image data on the screen in the continuous image data. The header data including the portion where the change occurs is transmitted to the image display device.

JP 2013-213913 A JP 2002-278526 A

The display driving device described in Patent Document 1 is a device built in the display device, and is formed as, for example, a dedicated driver LSI (large scale integrated circuit).
In addition, the display driving device is provided with an image comparison unit that determines a matching portion and a mismatching portion of image data continuously input from the host controller.
That is, since the image comparison unit compares image data, a frame memory for sequentially storing the image data is required.
As described above, in the display driving device described in Patent Document 1, the frame memory is an indispensable component, and there is a problem that the component cost is always increased.
In addition, when the display drive device is built in the display device, the cost of the display device itself increases.

Moreover, in the image display system described in Patent Document 2, the image data transmission device transmits information regarding a portion where a change has occurred on the screen in continuous image data.
As a result, information to be transmitted from the image data transmission device to the image display device is reduced, and it is possible to drive a large high-definition panel only by making a small change to an existing system.
However, Patent Document 2 does not mention control of refresh rate in a display device capable of low-frequency driving, and knowledge about a technique for performing low-frequency driving partially on the screen of such a display device is obtained. Absent.
In the image display system described in Patent Document 2, a frame memory is provided on the display device side, and it cannot be denied that the cost of the display device increases.

  The present invention solves the above-described problems, and an object thereof is to obtain a transmission device, a display device, and a display system that can reduce power consumption and cost of the display device.

  The transmission apparatus according to the present invention includes a storage unit, a comparison unit, a setting unit, and an adding unit. The storage unit sequentially stores continuous image data. The comparison unit compares the image data stored in the storage unit with the image data subsequent to the image data, and determines a portion that has changed between the image data and a portion that has not changed. The setting unit sets the refresh rate of the portion determined not to be changed by the comparison unit to be lower than that of the portion determined to have changed. The adding unit adds the refresh rate set by the setting unit to the image data and transmits the image data to the display device.

  According to the present invention, the refresh rate of the portion that does not change in the continuous image data is set lower than that of the changed portion. As a result, low-frequency driving can be partially performed and power consumption of the display device can be reduced. Furthermore, since the transmission device includes a storage unit that sequentially stores continuous image data, the component cost of the display device can be reduced.

It is a block diagram which shows the structure of the display system which concerns on Embodiment 1 of this invention. 1 is a block diagram illustrating a detailed configuration of a video transmission device according to Embodiment 1. FIG. It is a figure which shows an example of the corresponding data of determination data and a refresh rate. It is a figure which shows an example of the transmission method of refresh rate information. It is a figure which shows the other example of the transmission method of refresh rate information.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a display system according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram showing a detailed configuration of video transmission apparatus 1 according to Embodiment 1. As shown in FIG.
The display system shown in FIG. 1 includes a video transmission device 1 and a display device 2, and the video transmission device 1 and the display device 2 are connected by a monitor cable. As the monitor cable, for example, an existing digital monitor cable such as a DVI (Digital Visual Interface) cable may be used.

The video transmission device 1 is a host-side device that transmits image data to the display device 2, and is realized by, for example, a personal computer (hereinafter referred to as a PC).
The video transmission device 1 also includes a VRAM (Video Random Access Memory) 11 and a CPU (Central Processing Unit) 12, which are general PC configurations. As a configuration unique to the present invention, a frame memory 13, A comparison circuit 14, a refresh controller 15, and a determination result adding unit 16 are provided.

The CPU 12 controls writing of image data to the VRAM 11 and reading of image data from the VRAM 11.
The image data input to the video transmission device 1 is video data generated by application processing or broadcast video image data received by a television tuner for display on the display device 2. That is, image data for each frame is continuously input to the video transmission device 1, and the display device 2 sequentially displays continuous image data for each frame received from the video transmission device 1.

The frame memory 13 embodies the storage unit in the present invention, and sequentially stores continuous image data. In the frame memory 13, the image data is temporarily stored and then read, so that a delay of one frame occurs between the read image data and the next image data input from the CPU 12.
The frame memory 13 is configured by using a RAM such as a DRAM (Dynamic RAM) or an SRAM (Static RAM) provided in a general PC.
In this way, by using the memory provided in the PC as a standard, an increase in component costs can be suppressed.

  The comparison circuit 14 embodies the comparison unit in the present invention. The comparison circuit 14 compares the image data stored in the frame memory 13 with the image data input subsequent to the image data, and changes on the screen when both image data are displayed on the display device 2. Judge the part and the part that does not change. The determination unit may be a line unit, but may be a single pixel unit, a plurality of pixel units, a plurality of line units, or a block unit.

For example, when the determination is performed in units of lines, if all the pixel data of the first line in both image data match, the determination result of the first line is output to the refresh controller 15 as “0”. At this time, the comparison circuit 14 counts the number of times that the determination result is “0”. That is, when the determination result is “0” for the first time on the first line, the count is 1, and the determination result on the first line is between the image data of the next frame and the image data of the next frame. When it becomes “0” again, the count number becomes 2. This count number is also output to the refresh controller 15 as a determination result.
If all the pixel data of the second line do not match, the determination result of the second line is output to the refresh controller 15 as “1”.

The refresh controller 15 is a controller that sets a refresh rate when image data is displayed on the display device 2 based on the determination result of the comparison circuit 14, and includes a refresh rate setting unit 15a as shown in FIG.
The refresh rate setting unit 15a is a component that embodies the setting unit in the present invention, and sets the refresh rate of the portion determined not to be changed by the comparison circuit 14 to be lower than the portion determined to have changed.

For example, if the determination result of the line input from the comparison circuit 14 is “1” and the image data of this line has changed on the screen, the refresh rate setting unit 15a determines that the image data has been updated in this line. to decide.
In this case, the refresh rate setting unit 15a sets a maximum refresh rate of 60 Hz for this line with reference to the correspondence table as shown in FIG. The determination data shown in FIG. 3 is 3-bit data indicating the number of times the determination result is “0” in binary.

On the other hand, when the determination result is “0” and the image data of this line has not changed on the screen, the refresh rate setting unit 15a determines that the image data is not updated in this line. At this time, the refresh rate setting unit 15a gradually lowers the refresh rate of the line every time it is determined that the line determined not to change by the comparison circuit 14 does not change continuously.
For example, the correspondence table shown in FIG. 3 is referred to based on the count number at which the determination result is “0”. When the count number is 1, since it corresponds to the determination data = 001, 30 Hz lower than the maximum refresh rate is set for this line.
Further, when the count number is 2, since the determination data corresponds to 010, lower 15 Hz is set for this line.
Similarly, every time it is determined that there is no continuous change, a gradually lower refresh rate is set. When the count number is 6, the determination data is equal to 110, and therefore, this line has the lowest refresh rate of 1 Hz. Is set.
By using the correspondence table in this way, the calculation load of the refresh rate setting unit 15a can be reduced.

When the comparison circuit 14 determines for each line, the refresh rate setting unit 15a sets the refresh rate for each line according to the determination result for each line.
In the example of FIG. 2, the refresh rate is 15 Hz for the first line, 4 Hz for the second line, 60 Hz for the third line, 2 Hz for the fourth line, 1 Hz for the n-1 line, and 8 Hz for the n line. The refresh rate is set.

The determination result adding unit 16 is a component that embodies the adding unit in the present invention, and adds the refresh rate set by the refresh rate setting unit 15 a to the image data input from the CPU 12 and transmits it to the display device 2. To do.
For example, when the comparison circuit 14 makes a determination in line units, the determination result adding unit 16 adds the refresh rate information of each line set by the refresh rate setting unit 15a to the horizontal blanking period of the image data and displays the display device. 2 to send.

FIG. 4 is a diagram showing an example of a refresh rate information transmission method, and shows a case where refresh rate information is transmitted to the display device 2 in units of lines. In FIG. 4, while the horizontal synchronization signal HSYNC is at the L level, the signal Data Enable indicating the period in which the RGB video signal exists is at the H level. At this time, image data for one line is transmitted from the video transmission device 1 to the display device 2.
The determination result adding unit 16 adds the refresh rate information of each line to the horizontal blanking period of the image data, as shown in FIG.

For example, the refresh rate information indicating which refresh rate is 1, 2, 4, 8, 15, 30, or 60 Hz is the 3-bit determination data shown in FIG.
This 3-bit determination data is added to the horizontal blanking period in the RGB 24-bit data signal line of the video signal. If the refresh rate value to be set is made fine, the number of bits may be increased such as 4 bits, 5 bits, 6 bits,.
By adding the refresh rate information to the horizontal blanking period in this way, the image data to which the refresh rate information is added is displayed on the display device without greatly changing the existing interface between the video transmission device 1 and the display device 2. 2 can be transmitted.

Further, when the comparison circuit 14 makes a determination on a pixel basis, the determination result adding unit 16 adds the refresh rate of each pixel set by the refresh rate setting unit 15a to the image data through a dedicated signal line and displays it. You may transmit to the apparatus 2.
FIG. 5 is a diagram illustrating another example of the refresh rate information transmission method. When transmitting the refresh rate information to the display device 2 in pixel units, a dedicated signal line for transmitting the refresh rate information is added to the monitor cable. In the example shown in FIG. 5, the determination result for each pixel, which is 3-bit determination data, is transmitted through the signal line.
Even in this way, it is possible to transmit the image data to which the refresh rate information is added to the display device 2 without greatly changing the existing interface between the video transmission device 1 and the display device 2.
If the refresh rate value to be set is made fine, the number of bits may be increased as in FIG.

The display device 2 is a display device that displays image data received from the video transmission device 1, and includes a timing generator 21, a gate driver 22, a source driver 23, and a liquid crystal panel 24 as shown in FIG.
The timing generator 21 is a component that embodies the timing generator in the present invention. The timing generator 21 receives image data received from the video transmission apparatus 1 and sets drive timing based on the refresh rate added to the image data. Generate. For example, the presence / absence of updating of the image data specified in each line and the presence / absence of driving of the liquid crystal panel 24 are determined in units of frames based on the refresh rate set thereto.

The gate driver 22 and the source driver 23 embody the drive unit in the present invention, and display the image data input from the timing generator 21 on the liquid crystal panel 24 in synchronization with the moving timing.
The liquid crystal panel 24 embodies the display unit of the present invention, and displays the image data received from the video transmission device 1. For example, it has a matrix substrate having source lines and gate lines intersecting each other, pixel electrodes corresponding to RGB are disposed along the gate lines, and transistors corresponding to the pixel electrodes are disposed at intersections of both lines. ing.

The gate driver 22 outputs a gate signal to the gate line to drive the transistor. The source driver 23 outputs the gradation voltage of the image data to the source line.
The image data for each frame received from the video transmission device 1 is displayed on the display device 2 by the operation of these drivers.

The feature of the display device 2 according to the present invention is that it does not include a frame memory necessary for setting a refresh rate, despite the configuration capable of low-frequency driving as described above. That is, in this invention, paying attention to the fact that the video transmission device of the host device is a PC having a memory that can be a frame memory as a standard, the frame memory that is essential on the display device side is the memory of the video transmission device. It is substituted.
Furthermore, the refresh rate information and the image data can be transmitted without greatly changing the existing interface between the video transmission device and the display device.
Thereby, the cost of the display device 2 can be reduced, and the cost of the entire display system can be reduced.

As described above, the video transmission device 1 according to Embodiment 1 includes the frame memory 13, the comparison circuit 14, the refresh rate setting unit 15a, and the determination result adding unit 16.
The frame memory 13 sequentially stores continuous image data. The comparison circuit 14 compares the image data stored in the frame memory 13 with the image data subsequent to the image data, and determines a portion that has changed between the image data and a portion that has not changed. The refresh rate setting unit 15a sets the refresh rate of the portion determined not to change by the comparison circuit 14 to be lower than the portion determined to have changed. The determination result adding unit 16 adds the refresh rate set by the refresh rate setting unit 15a to the image data and transmits the image data to the display device 2. In this way, the refresh rate of the portion that does not change in the continuous image data is set lower than that of the changed portion. As a result, low-frequency driving can be partially performed and power consumption of the display device can be reduced. Furthermore, since the video transmission apparatus 1 includes the frame memory 13 that sequentially stores continuous image data, the component cost of the display apparatus 2 can be reduced.

  In the video transmission device 1 according to the first embodiment, the comparison circuit 14 determines, on a line basis, a portion that changes on the screen and a portion that does not change when both image data are displayed on the display device 2. Then, the determination result adding unit 16 adds the refresh rate of each line set by the refresh rate setting unit 15a to the horizontal blanking period of the image data and transmits it to the display device 2. With this configuration, it is possible to transmit the image data to which the refresh rate information is added to the display device 2 without greatly changing the existing interface between the video transmission device 1 and the display device 2. .

  Further, in the video transmission device 1 according to the first embodiment, the comparison circuit 14 determines, on a pixel basis, a portion that changes on the screen and a portion that does not change when both image data are displayed on the display device 2. Then, the determination result adding unit 16 adds the refresh rate of each pixel set by the refresh rate setting unit 15a to the image data via a dedicated signal line and transmits the image data to the display device 2. Even with this configuration, it is possible to add and transmit refresh rate information to image data without greatly changing the existing interface between the video transmission device 1 and the display device 2.

  Furthermore, the display device 2 according to the first embodiment includes a liquid crystal panel 24, a timing generator 21, a gate driver 22, and a source driver 23. The liquid crystal panel 24 displays image data. The timing generator 21 receives the image data received from the video transmission device 1 and generates drive timing based on the refresh rate added to the image data. The gate driver 22 and the source driver 23 cause the liquid crystal panel 24 to display the image data input from the timing generator 21 in synchronization with the drive timing. With this configuration, since the video transmission device 1 includes the frame memory 13, the component cost of the display device 2 can be reduced.

  Furthermore, the display system according to Embodiment 1 includes a display device 2 and a video transmission device 1 that transmits image data to which a refresh rate is added to the display device 2. With this configuration, it is possible to reduce power consumption by partially driving the display device 2 while reducing the component cost of the display device 2.

  In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.

  DESCRIPTION OF SYMBOLS 1 Video transmitter, 2 Display apparatus, 11 VRAM, 12 CPU, 13 Frame memory, 14 Comparison circuit, 15 Refresh controller, 15a Refresh rate setting part, 16 Judgment result addition part, 21 Timing generator, 22 Gate driver, 23 Source driver 24 LCD panel.

Claims (5)

A transmission device that connects to a display device that displays image data according to a refresh rate and transmits image data to the display device,
A storage unit for sequentially storing continuous image data;
A comparison unit that compares the image data stored in the storage unit with the image data subsequent to the image data, and determines a portion that has changed in both image data and a portion that does not change;
A setting unit for setting a refresh rate of a portion determined not to change by the comparison unit to be lower than a portion determined to have changed;
A transmission apparatus, comprising: an addition unit that adds the refresh rate set by the setting unit to image data and transmits the image data to the display device. The comparison unit compares the image data stored in the storage unit and the image data subsequent to the image data, determines a portion that has changed in both image data and a portion that does not change in line units,
The transmission device according to claim 1, wherein the adding unit adds the refresh rate of each line set by the setting unit to a horizontal blanking period of image data and transmits the image data to the display device. The comparison unit compares the image data stored in the storage unit with the image data subsequent to the image data, determines a portion that has changed in both image data and a portion that does not change in pixel units,
2. The transmission device according to claim 1, wherein the adding unit adds the refresh rate of each pixel set by the setting unit to image data via a dedicated signal line and transmits the image data to the display device. . A display device for displaying image data received from a transmission device,
A display for displaying image data;
A timing generator that inputs image data received from the transmission device and generates drive timing based on a refresh rate added to the image data;
A display device comprising: a drive unit that causes the display unit to display image data input from the timing generation unit in synchronization with the drive timing. A display device according to claim 4;
4. A display system comprising: the transmission device according to claim 1 that transmits image data to which a refresh rate is added to the display device.

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