WO2012002258A1

WO2012002258A1 - Display device, method for controlling the display device, program, and recording medium

Info

Publication number: WO2012002258A1
Application number: PCT/JP2011/064473
Authority: WO
Inventors: 悟史井樋田
Original assignee: シャープ株式会社
Priority date: 2010-06-30
Filing date: 2011-06-23
Publication date: 2012-01-05

Abstract

Disclosed is a display device (100) which is provided with: a display panel (1) wherein a plurality of scanning lines and a plurality of signal lines are disposed such that the scanning lines and the signal lines intersect each other; a source driver (3), which supplies respective signal lines with image data to be displayed on the display panel (1); and a controller (5) which controls the source driver (3) to supply first image data at a lower frame frequency to a signal line, which acquires input data including the image data and supplies the first image data included in the acquired input data, said lower frame frequency being lower than the frequency with which a signal line supplies second image data included in the input data. The controller (5) sets a part of the input data as the first image data, and the rest of the input data as the second image data.

Description

Display device, control method therefor, program, and recording medium

The present invention relates to a display device, a control method thereof, a program, and a recording medium.

In recent years, electronic information processing has progressed, and electronic paper has been put into practical use as one of them. Although various display media can be used for electronic paper, among them, there is a liquid crystal panel suitable for color display.

As a liquid crystal panel of electronic paper, a reflective liquid crystal panel is often used because of low power consumption. However, there are many advantages of adopting a transmissive liquid crystal panel that can display more vividly, and a reduction in power consumption of the transmissive liquid crystal panel is desired.

One of the factors that consume power in a transmissive liquid crystal panel is that data must be rewritten for each frame in order to maintain display quality when performing full color (multi-gradation) display. For example,

Patent Documents

1 and 2 describe reducing power consumption by paying attention to the rewriting of data.

In the technique of Patent Document 1, as shown in FIG. 18A, the display screen is divided into a display area and a non-display area, and partial driving is performed. FIG. 18 is a diagram for explaining a drive control method in a conventional display device. In this driving method, the frame is rewritten every frame in the display area, but the data is rewritten every several frames in the non-display area (see FIG. 18B).

In the technique of Patent Document 2, a memory for holding still image data is mounted on a pixel (see FIG. 19), and writing is not performed until rewriting is required when displaying a still image. FIG. 19 is a diagram illustrating a circuit configuration of a display panel included in a conventional display device.

Japanese Patent Publication “Japanese Patent Laid-Open No. 2003-58130 (published on February 28, 2003)” Japanese Patent Publication “Japanese Patent Laid-Open No. 9-331490 (published on December 22, 1997)”

However, in the technique of Patent Document 1 using partial drive, only the solid screen can be displayed in the non-display area, so the display area of the entire screen becomes narrow.

Also, in the technique of Patent Document 2, the aperture ratio decreases because the memory is built in the pixel. As a result, the area of the opening is reduced and the entire screen appears dark.

The present invention has been made in view of the above problems, and an object thereof is to provide a display device capable of realizing low power consumption.

In order to solve the above problems, a display device according to one embodiment of the present invention includes a display panel in which a plurality of scanning lines and a plurality of signal lines are arranged to cross each other, and each of the plurality of signal lines. A signal driver that supplies image data to be displayed on the display panel, input signal including the image data, and the signal line that supplies first image data included in the acquired input data are Control means for controlling the signal driver to supply the first image data at a lower frame frequency than the signal line for supplying the second image data included in the input data, and the control means comprises: A part of the input data is the first image data, and the rest is the second image data.

In order to solve the above problem, a control method according to one embodiment of the present invention includes a display panel in which a plurality of scanning lines and a plurality of signal lines are arranged to intersect each other, and each of the plurality of signal lines. A control method for a display device comprising a signal driver for supplying image data for display on the display panel, the method comprising: obtaining input data including the image data; and first image data included in the acquired input data Control for controlling the signal driver to supply the first image data to the signal line for supplying the first image data at a lower frame frequency than the signal line for supplying the second image data included in the input data. In the control step, a part of the input data is the first image data, and the remaining part is the second image data.

According to the above configuration, in the display device, when input data including image data to be displayed on the display panel is acquired, among the acquired input data, a plurality of first image data and second image data are used. The frame frequency for supplying image data to each of the signal lines is changed.

Specifically, image data is supplied to the signal line that supplies the first image data at a lower frame frequency than the signal line that supplies the second image data.

For example, when a liquid crystal panel is used as a display panel, the polarity is generally inverted when writing a data signal, and power is consumed in this polarity inversion.

According to one aspect of the present invention, when the first image data is supplied to the signal line, the polarity inversion by the first image data is performed in order to make the frequency lower than the frame frequency at which the second image data is supplied to the signal line. The number decreases.

Also, the driving power of the signal driver that supplies the first pixel data to the signal line can be suppressed. Therefore, low power consumption can be realized.

A display device according to one embodiment of the present invention includes a display panel in which a plurality of scanning lines and a plurality of signal lines are arranged to intersect with each other, and a display panel for displaying on each of the plurality of signal lines. A signal driver for supplying image data, and input signal including the image data are acquired, and the signal line for supplying the first image data included in the acquired input data is provided with a second signal included in the input data. Control means for controlling the signal driver so as to supply the first image data at a frame frequency lower than that of the signal line for supplying image data, wherein the control means converts a part of the input data to Since the first image data is used and the remainder is the second image data, low power consumption can be realized.

It is a block diagram which shows schematic structure of the principal part of the display apparatus which concerns on one Embodiment of this invention. It is a figure which shows the structure of the display panel with which the display apparatus shown in FIG. 1 is provided. 3 is a table showing a comparison of frame frequencies of a text display area and a full color display area in the display device shown in FIG. 1. It is a graph which shows the relationship between the oscillation frequency of a clock generator, and power consumption. It is a figure which shows the ratio of a full color display area and a text display area with respect to the whole screen of the display panel with which the display apparatus shown in FIG. 1 is provided. It is a figure which shows the retention rate of the pixel potential of a text display area, and the retention rate of the pixel potential of a full color display area. It is a figure which shows the average power consumption concerning the data rewriting of the display panel with which the display apparatus shown in FIG. 1 is provided. It is a figure which shows the average power consumption concerning the data rewriting of each of a text display area and a full color display area. 3 is a table showing a comparison of frame frequencies of a text display area and a full color display area in the display device shown in FIG. 1. It is a figure which shows the ratio of a full color display area and a text display area with respect to the whole screen of the display panel with which the display apparatus shown in FIG. 1 is provided. It is a block diagram which shows the modification of the display apparatus shown in FIG. FIG. 12 is a diagram illustrating an example of a flow of processing for converting multi-gradation data into 1-bit data in the display device illustrated in FIG. 11. 3 is a table showing a comparison of frame frequencies of a text display area and a full color display area in the display device shown in FIG. 1. It is a figure which shows the structure of the equivalent circuit of the display panel with which the display apparatus which concerns on other embodiment of this invention is provided. It is a table | surface which shows the comparison of the frame frequency of the text display area | region and full color display area | region in the display apparatus which concerns on other embodiment of this invention. It is a figure which shows the drive voltage and element light emission intensity accompanying ON / OFF of Tr1. It is a figure which shows the average power consumption concerning the data rewriting of each of a text display area and a full color display area. It is a figure explaining the drive control method in the conventional display apparatus. It is a figure which shows the circuit structure of the display panel with which the conventional display apparatus is provided.

An embodiment of a display device according to the present invention will be described below with reference to FIGS. Note that, in the following description, various preferable limitations for implementing one aspect of the present invention are given, but the technical scope of the present invention is not limited to the description of the following embodiments and drawings. .

[First Embodiment]
(1-1. Configuration of display device)
FIG. 1 is a block diagram showing a schematic configuration of a main part of a display device 100 according to an embodiment of the present invention.

As shown in FIG. 1, the display device 100 includes a liquid crystal panel 1 (display panel), a gate driver 2, a source driver 3 (signal driver), a power supply 4, a controller 5 (control means), and a backlight 6.

The liquid crystal panel 1 is an active matrix type liquid crystal panel in which a plurality of pixels are arranged in a matrix. Although not shown, the liquid crystal panel 1 has a structure in which a liquid crystal layer is sandwiched between an active matrix substrate and a counter substrate. The liquid crystal panel 1 is not particularly limited as long as it is a transmissive liquid crystal panel, and a known liquid crystal panel can be used.

In the liquid crystal panel 1, a plurality of gate lines GL (scanning lines) and a plurality of source lines SL (signal lines) are arranged so as to intersect each other. A region surrounded by the gate line GL and the source line SL is one pixel, and each pixel is provided with a display electrode 12 and a switching element 13 such as a TFT. FIG. 2 is a diagram illustrating a configuration of the liquid crystal panel 1 included in the display device 100.

The gate line GL is connected to the gate driver 2, and the source line SL is connected to the source driver 3. A gate line GL, a source line SL, and a display electrode 12 are connected to the gate electrode, the source electrode, and the drain electrode of the switching element 13, respectively.

That is, the source signal is selectively supplied from the source driver 3 to the switching element 13 via the source line SL, and the gate signal is supplied from the gate driver 2 to the switching element 13 via the gate line GL. Control ON / OFF of.

The gate driver 2 supplies a voltage as a gate signal to each gate line GL in the scanning order based on the gate control signal supplied from the controller 5.

The source driver 3 supplies a source signal to each source line SL based on the source control signal supplied from the controller 5. Specifically, image data to be displayed on the liquid crystal panel 1 is supplied to each of the plurality of source lines SL.

The power supply 4 applies a voltage necessary for supplying to the switching element 13 to the gate driver 2 and the source driver 3 based on a control signal supplied from the controller 5.

The controller 5 acquires input data from an input data supply source (not shown), generates a gate control signal and a source control signal from the input data, supplies the generated gate control signal to the gate driver 2, and supplies the source control signal to the source This is supplied to the driver 3.

In the present embodiment, the controller 5 acquires input data including image data, and the second image data included in the input data is supplied to the source line SL that supplies the first image data included in the acquired input data. The source driver 3 is controlled to supply the first image data at a frame frequency lower than that of the source line SL to be supplied.

Specifically, the controller 5 sets a part of the input data as the first image data and the rest as the second image data. The conditions at this time are not particularly limited. For example, 1-bit to 4-bit image data may be used as the first image data for each of the three sub-pixels constituting the pixel. The first image data is 1-bit data. Other image data, that is, image data other than 1-bit to 4-bit image data for each sub-pixel is set as second image data.

Here, 1-bit image data is “FF” or “00” data, and when applied to a color panel of RGB 3 colors, binary 8 colors are displayed. Note that when “FF” or “00” is input to the signals of the RGB sub-pixels forming one pixel, a monochrome image is displayed because the signal is displayed in either white or black.

In this image data, as the number of bits increases, the number of gradations to be displayed increases, but the image quality tends to deteriorate accordingly. On the other hand, for example, if the signal input to each sub-pixel is low-bit image data of about 1 to 4 bits (16 gradations, 4096 colors), the number of gradation display is small, so the image quality is degraded. Few.

For example, when the voltage holding ratio of the pixel is 99.5%, the voltage drop in one frame is about 7% of the voltage difference for each gradation when it is 4 bits (16 gradations). Even if the frame rate, which is normally 60 Hz, is set to 20 Hz (write once every three times), the amount of voltage change is about 20%, which is a level that is not problematic for text display.

Therefore, by writing low-bit image data at a low frame frequency, low power consumption can be realized without impairing display quality.

The 1-bit to 4-bit data includes, for example, text data and image data displayed by at least one color selected from the group consisting of white, black, and RGB primary colors. Examples of the image data include books (characters, text), word processor documents, icons, and the like.

Further, the image data other than 1-bit to 4-bit data is an image displayed by a large number of gradations, that is, multi-bit image data having a large number of colors, for example, data of 5 bits or more. What is displayed by the second image data includes, for example, still images or moving images such as photographs or slide shows.

In the following description, an area for displaying the first image data is referred to as a text display area, and an area for displaying the second image data is referred to as a full color display area.

For example, in FIG. 1, a region 21 surrounded by a range from the source line SL1 to the source line SLn and a range from the gate line GL1 to the gate line GLn is a text display region. In FIG. 1, a region 20 surrounded by a range from the source line SLn to the source line SLn + a and a range from the gate line GLn to the gate line GLn + a is a full color display region.

In this specification, the area for displaying the first image data is referred to as a text display area. However, as described above, low-bit image data such as an icon included in the first image data is also displayed in text. Can be displayed in the area.

The input data supply source is not particularly limited, and examples thereof include a mobile phone, a portable game machine, a PDA (Personal Digital Assistant), a digital camera, a notebook computer, and an electronic book.

The backlight 6 is provided on the back side of the liquid crystal panel 1 (that is, the side opposite to the display surface) and irradiates the liquid crystal panel 1 with light. The backlight 6 is not particularly limited. For example, a light source using a conventionally known light emitting element such as an LED (light emitting diode) may be used.

In the present embodiment, the display device 100 includes the controller 5, but the controller 5 may be provided outside the display device 100. Further, although the gate driver 2 and the source driver 3 are provided outside the liquid crystal panel 1, at least one of the gate driver 2 and the source driver 3 may be formed integrally with the liquid crystal panel 1.

(1-2. Control of frame frequency)
Next, a frame frequency control method (control step) in the present embodiment will be described.

In the display device 100, the input data input from the input data supply source to the controller 5 includes image data such as text data, and control signals such as a horizontal synchronizing signal and a vertical synchronizing signal. The controller 5 acquires a control signal such as a horizontal synchronization signal and a vertical synchronization signal from an input data supply source, generates a gate control signal and a source control signal based on the acquired control signal, and generates a gate driver 2 and a source driver 3. To supply each.

This gate control signal is a timing signal for controlling the driving timing of the gate driver 2, and includes a gate start pulse, a gate shift clock, a gate output enable, and the like. The data control signal is a timing signal for controlling the driving timing of the source driver 3, and includes a source start pulse, a source shift clock, a source output enable, a polarity inversion signal, and the like.

Further, as described above, when the controller 5 acquires input data including image data to be displayed on the liquid crystal panel 1, among the acquired input data, the first image data and the second image data are: The frame frequency for supplying image data to each of the plurality of source lines SL is changed.

Specifically, if the acquired input data is low-bit data of about 1 to 4 bits for each of the three sub-pixels constituting the pixel, the first image data and the data with more bits are used. If so, the source line SL that determines the second image data and supplies the data determined as the first image data has a lower frame frequency than the source line SL that supplies the data determined as the second image data. Supply.

Generally, for example, low-bit image data of about 1 to 4 bits, for example, has a small number of gradation displays, so that the quality degradation of the image quality is less than that of data displaying multiple gradations. Therefore, even when low-bit image data is written at a low frame frequency, display quality is not impaired.

In addition, when the liquid crystal panel 1 is used as a display panel, the polarity is generally inverted when writing a data signal, but power is consumed in this polarity inversion.

According to the present embodiment, since the first image data has little deterioration in the quality of the image quality, it can be made lower than the frame frequency at which the second image data is supplied to the source line SL. Therefore, the number of polarity inversions by the first image data is reduced, and the driving power of the source driver 3 that supplies the first pixel data to the source line SL can be suppressed. Therefore, low power consumption can be realized.

Here, the frame frequency (Hz) represents the number of frames rewritten per second. In this embodiment, the normal frame frequency (that is, the state in which the frame frequency is not lowered) is 60 Hz. Also, frame rewriting is also referred to as “writing” or “refreshing”.

FIG. 3 shows a comparison of frame frequencies between the text display area and the full color display area in the present embodiment. FIG. 3 is a table showing a comparison of frame frequencies in the text display area and the full-color display area in the display device 100.

In the table of FIG. 3, “ON” and “OFF” indicate whether image data is supplied to the source line SL.

As shown in this table, every frame is rewritten in the full color display area. On the other hand, in the text display area, rewriting is performed in the first frame 1, but frames 2 to 10 are standby frames (pause frames) and are not rewritten.

That is, the period of the frame in which the text display area is written is 10 periods, and the frame frequency at this time is 1/10 of the frame frequency of the full-color display area.

Although depending on the specifications of the display panel, etc., here, the liquid crystal panel 1 having a power consumption of 10 mW per frame when the entire screen is a full color display region (that is, displayed at a normal frame frequency) is used. Explained as an example.

FIG. 4 is a graph showing the relationship between the oscillation frequency of the clock generator and the power consumption. The horizontal axis of the graph shows the oscillation frequency (Hz), and the vertical axis shows the power consumption (mW) in the display panel.

When the entire screen of the liquid crystal panel 1 is text display, since one frame is “ON”, the power consumption is 10 mW. Next, it is set to “OFF” from 2 frames to 10 frames. At this time, the timing clock for determining the write timing is always operating, so the power consumption does not become 0 mW. In the graph of FIG. As indicated by the arrow, for example, when the clock frequency is about 500 KHz, the power is approximately 2 mW.

Therefore, the average power consumption in this case is (10 + 2 × 9) /10=2.8 mW, and the power consumption can be reduced by about 70% compared to the case of full color display.

Therefore, for example, when the ratio of the full-color display area and the text display area to the entire screen of the liquid crystal panel 1 is 50% as shown in FIG. 5, the power consumption in the entire screen is about 5.4 mW on average. That is, power consumption can be reduced by 40% or more compared to the case where the entire screen is a full color display region. FIG. 5 is a diagram showing the ratio of the full color display area and the text display area to the entire screen of the liquid crystal panel 1 included in the display device 100.

In particular, when the display device 100 is used as an electronic book, 80% or more of the entire screen can be operated in text display. Therefore, power consumption can be reduced by 60% or more for full color display.

After that, since the text display area is also rewritten in the frame 11, data is written to all pixels. Not rewriting the text display area is also referred to as “standby”, “pause”, or “non-refresh”.

(1-3. Refresh)
Generally, when displaying halftones, image quality cannot be maintained without rewriting every frame. In other words, the pixel of the full color display region has a low voltage holding ratio. Therefore, in the full-color display region, as shown in FIG. 6, the pixel potential is inverted for each frame and driven in an alternating manner. FIG. 6 is a diagram showing the pixel potential holding ratio in the text display area and the pixel potential holding ratio in the full-color display area.

On the other hand, if the text data displayed in the text display area in this embodiment is, for example, 1-bit data, halftones are not displayed. Therefore, depending on the performance of the transistor, the rate at which the holding voltage decreases for each frame is, for example, about 1%, and the decrease in the pixel potential holding rate is moderate as shown in FIG.

Here, assuming that the voltage holding ratio when the text data is written (refreshed) is 100%, the user can read the text without any trouble if the holding ratio is reduced to 90%. Therefore, in the text display area, it is possible to maintain a constant image quality without frequently rewriting the frame.

Further, as described above, the entire screen of the conventional liquid crystal panel 1 is rewritten by writing the pixels in the text display area once every several frames as compared with the power consumption when writing all the pixels. In comparison with FIG. 7, the average power consumption can be reduced as shown in FIGS. FIG. 7 is a diagram showing average power consumption for data rewriting of the liquid crystal panel 1 in the display device 100, and FIG. 8 is a diagram showing average power consumption for data rewriting in the text display area and the full color display area. .

In the text display area of FIG. 8, the power consumption during the non-refresh period is 2 mW, the power consumption during the refresh period is 10 mW, and the average of these periods is 2.8 mW. Further, the average power consumption for data rewriting of the liquid crystal panel 1 shown in FIG. 7 is an average of the average power consumption for data rewriting in the text display area and the full color display area shown in FIG.

As described above, according to the display device 100, since the rewriting is performed every frame in the full-color display area, the display quality is not deteriorated, and in the text display area, the frame frequency is made lower than the full-color display area to reduce the number of rewrites. Therefore, power consumption can be reduced.

Further, for example, in the gate lines GL1 to GLn shown in FIG. 6, there is no full color display area on the line. Therefore, it is sufficient that the gate driver 2 keeps outputting the OFF voltage to the gate lines GL1 to GLn, and the power consumption of the gate driver 2 can be reduced.

At this time, since the source driver 3 only needs to apply a fixed OFF potential, the pixel potential difference in the region on the gate lines GL1 to GLn does not fluctuate. Therefore, power consumed with pixel displacement can also be reduced.

(1-4. Pause frame reset)
Incidentally, input data including a rewrite instruction for the first image data may be acquired during the non-refresh period described above. Therefore, it is preferable that the display device 100 includes a counting unit that counts a pause frame (also referred to as a standby frame) period in which the first image data is not supplied.

Here, the “pause frame period” is a period during which data is not written for the number of predetermined pause frames.

That is, the controller 5 controls the source driver 3 to supply the first image data in the next frame of the pause frame when the input data including the instruction to rewrite the first image data in the pause frame is acquired. The counting means can newly count the pause frame period from the next frame.

In this embodiment, as described above, writing to the text display area is 10 cycles. At this time, as shown in FIG. 9, when the text rewrite instruction is acquired during the standby frame period (frame 6), the controller 5 performs the first frame (frame 7) after the frame from which the text rewrite instruction is acquired. The source driver 3 is controlled to supply image data. As a result, all pixels are written in the frame 7.

FIG. 9 is a table showing a comparison of frame frequencies between the text display area and the full-color display area in the display device 100.

When all the pixels are written in this way, the counting means newly counts the pause frame period from the frame 7. Therefore, the predetermined pause frame period can be restarted from the beginning immediately after rewriting.

Note that the controller 5 may have the function of the counting means, or may be configured separately with the counting means.

Further, the rewrite instruction for the first image data may include a size change instruction for the first image data.

For example, when the ratio between the full color display area and the text display area with respect to the entire screen of the liquid crystal panel 1 is 50% (FIG. 10A), an instruction is given to increase the size of the text display area to 70%. If acquired, the controller 5 controls the source driver 3 so that all pixels are written in the frame following the frame from which the size change instruction is acquired.

Thus, each image data is displayed at a rate that the size of the text display area is 70% and the full-color display area is 30% ((b) of FIG. 10). FIG. 10 is a diagram showing the ratio of the full-color display area and the text display area to the entire screen of the liquid crystal panel 1 included in the display device 100.

Also in this case, the counting means newly counts the pause frame period from the frame in which all the pixels are written. Therefore, even if the size change instruction is acquired during the pause frame period, the predetermined pause frame period can be restarted immediately after the size change.

(1-5. Conversion of text data)
Next, a data conversion method when multi-tone text data is included in the input data in the present embodiment will be described with reference to FIGS.

FIG. 11 is a block diagram showing a modification of the display device 100, and FIG. 12 is a flowchart showing a flow of processing when converting multi-gradation text data into 1-bit text data.

As shown in FIG. 11, the display device 100 determines whether or not multi-tone text data is included in the input data. A CPU 7 (central processing unit, conversion means) that converts data into 1 to 4 bits per unit may be further provided. In this case, the controller 5 sets the text data converted by the CPU 7 as first image data.

For example, the input data may include multi-tone text data. That is, the character (text data) is not data displayed by at least one color selected from the group consisting of white, black, and RGB primary colors, but data displayed by a halftone color such as green or yellow. There is.

Therefore, it is determined whether or not multi-tone text data is included in the input data, and when multi-tone text data is included, the data is converted to 1 to 4 bits per subpixel. The area that can be driven at a lower frame frequency is increased.

In this embodiment, as shown in FIG. 12, first, the CPU 7 acquires input data from an input data supply source (step S1), and determines whether text data is included in the acquired input data (step S2). ).

If it is determined that text data is included (“YES” in step S2), the CPU 7 further determines whether the text data is 1 to 4 bits of text data per subpixel. It is determined whether the text data is multi-gradation text (step S3).

On the other hand, when it is determined that the text data is not included (“NO” in step S2), the controller 5 drives the input data determined as the first image data such as an icon at a low frame frequency as described above. The input data determined as the second image data is rewritten every frame (step S4).

If it is determined in step S3 that the data is multi-tone text data, the CPU 7 converts the multi-tone text data into 1-bit data (step S5).

The conversion method to 1-bit data is not particularly limited. For example, when it is determined that the data is multi-gradation text data, the conversion is performed so that all are displayed in monochrome regardless of the gradation of the data. May be.

For example, when 256-gradation data is input, multi-gradation data can be forcibly converted to 1-bit data by arbitrarily setting a slice level for 1-bit conversion. For example, data from 0 to 16 gradations is converted to “0”, that is, black, and data from 17 to 255 gradations is converted to “1”, that is, white, and output. Thereby, even if multi-tone text data is input, it can be driven at a low frame frequency.

Although an example of converting multi-gradation text data into 1-bit data is given here, the present invention is not limited to this. For example, the same method can be applied to conversion into 2-bit data. it can. Also in this case, the rewrite frame can be reduced without deteriorating the image quality.

Thereafter, the controller 5 uses the text data converted by the CPU 7 as the first image data, and controls the source driver 3 to drive at a frame frequency lower than that of the second image data (step S6).

For example, if multi-tone text data is included in the input data, and if the conversion processing as described above is not performed, the multi-tone text data is assumed to be the second image data and rewritten every frame. Control.

Therefore, it is determined whether or not multi-tone text data is included in the input data. If multi-tone text data is included, the input data is converted into 1-bit data, for example, at a lower frame frequency. The area that can be driven increases. Therefore, power consumption can be further reduced.

In this embodiment, the CPU 7 has a data conversion function (including determination of presence / absence of text), but is not limited to this form. For example, the controller may have a data conversion function or may incorporate another member having the function. In addition, data conversion may be performed in an external device.

(1-6. Write cycle of first image data)
Here, with reference to FIG. 13, the setting of the cycle for writing the first image data will be described. FIG. 13 is a table showing a comparison of frame frequencies in the text display area and the full-color display area in the display device 100.

In the embodiment described above, the frame in which the first image data is written is set every 10 cycles. However, for example, when the writing polarity of the image data is reversed for each frame, the frame in which the first image data is written is set in 10 cycles. In this case, the data writing polarity is always biased to one side.

That is, when data is written in 10 cycles, as shown in the table of FIG. 13, the polarity is “+” in the first frame in which the first image data is written, and “+” in the frame 11 in which the data is next written. In the frame 21 in which data is further written, the polarity is “+”.

As described above, if the data writing polarity is always biased to one side, the liquid crystal panel 1 is “burned” and has a short life.

Therefore, the controller 5 supplies only the second image data after the first image data and the second image data are supplied at the same time until the first image data and the second image data are supplied at the next time. It is preferable to control to supply even frames. Accordingly, image data can be written without being biased to a certain polarity, so that occurrence of burn-in can be suppressed.

For example, in the table of FIG. 13, the writing cycle of the first image data is 5 cycles. For this reason, the first frame in which the first image data is written has a “+” polarity, the second frame in which data is written has a “−” polarity, and the second frame in which data is written has a “+” polarity. The polarity is “−” in the frame 16 in which data is written.

Thus, in the frame in which the first image data is written, since the polarity is written every time, the occurrence of burn-in is suppressed and the life is prolonged.

In this embodiment, the frame writing cycle is fixed. However, for example, the frame writing cycle may be changed to a different writing cycle after a certain period of time has elapsed.

Further, when the liquid crystal panel 1 is in the normally white mode, the background of the text display area is displayed in white and the text is displayed in black so that only the character portion needs to be driven, so that the drive area is minimized. it can. Therefore, the power consumption of the gate driver 2 can be reduced.

On the other hand, when the liquid crystal panel 1 is in the normally black mode, the background of the text display area is displayed in black and the text is displayed in white so that only the character portion needs to be driven. it can. Therefore, the power consumption of the gate driver 2 can be reduced.

As described above, according to the display device 100, the second image data whose display quality is likely to deteriorate is rewritten every frame, and the display quality is reduced by reducing the frame frequency of the first image data whose display quality is difficult to deteriorate. There is no loss. Further, by reducing the frame frequency of the first image data, it is possible to reduce power consumption required for data rewriting.

Furthermore, in the display device 100, the area for displaying the first image data with the frame frequency lowered is not fixed, and the display area is changed each time according to the acquired input data. In addition, the frame frequency is decreased for data such as characters or icons with little decrease in pixel potential holding ratio. Therefore, a non-display area where no data is displayed does not occur, and the display area of the entire screen is not narrowed.

In addition, since there is little decrease in the pixel potential holding rate for characters or icons, it is not necessary to provide a memory or the like for holding these data in the pixel. Therefore, since the aperture ratio does not decrease as compared with a conventional display panel, the entire screen does not become dark.

[Second Embodiment]
Another embodiment relating to the display device of the present invention will be described. In 2nd Embodiment, since the member which has the same function as drawing demonstrated in 1st Embodiment is used except having used the organic electroluminescent panel as a display panel, the description is abbreviate | omitted.

FIG. 14 is a diagram showing a configuration of an equivalent circuit of an organic EL (electroluminescence) panel included in a display device according to another embodiment of the present invention.

As shown in FIG. 14, the structure of the organic EL panel includes two

transistors

33 and 34 and one capacitor 36. Specifically, a switching NMOS / TFT 33 (hereinafter referred to as Tr1) is disposed at the intersection of the data line 30 and the scanning line 31, and power is supplied to the driving PMOS / TFT 34 (hereinafter referred to as Tr2). For this purpose, a power supply line 32 is provided.

When Tr1 at the intersection of the signal line 30 and the scanning line 31 is turned on, the capacitor 36 is charged, and current is supplied from the power supply line 32 while Tr2 is turned on to cause the organic EL element 35 to emit light. Then, the organic EL element 35 emits light.

When the display device 100 includes an organic EL panel, the driving area can be minimized by displaying the text display area in black and displaying characters in white. Therefore, the power consumption of the gate driver 2 can be reduced similarly to the liquid crystal panel 1.

Also, if the background of the text display area is black, it is not necessary to cause the area to emit light, and it is not necessary to drive both Tr1 and Tr2. Further, it is not necessary to turn on Tr1 after the charging of the capacitor 36 is completed. Therefore, power consumption can be reduced. The characters in the text display area are not limited to white display, but may be RGB single color.

In addition, since there is free discharge of the capacitor 36, it is necessary to rewrite once every several frames like the liquid crystal. For example, as shown in FIG. 15, as in the first embodiment, the full-color display area rewrites pixels every frame, whereas the text display area rewrites pixels in several frame cycles. FIG. 15 is a table showing a comparison of frame frequencies of a text display area and a full color display area in a display device according to another embodiment of the present invention.

Here, Tr1 is turned on in the writing frame of the text display area, and Tr1 is turned off in the standby frame, and rewriting is performed at a frame frequency of 1/10 of the full-color display area. The drive voltage and element emission intensity at this time will be described with reference to FIG. FIG. 16 is a diagram showing a drive voltage and element emission intensity associated with ON / OFF of Tr1.

In FIG. 16, the timing of “Tr1 on / off” is synchronized with the timing of on / off of Tr1 shown in FIG. That is, FIG. 16 shows the operation of Tr1 in the text display area.

In the text display area of this example, Tr1 is turned on once every 10 frames, and the voltage of the capacitor connected to Tr1 can maintain the gate voltage of Tr2 for controlling the light emission of the organic EL for 10 frames.

In the present embodiment, the background of the text display area is displayed in black, and the characters (text, icons, etc.) are displayed in white or color, so that the emission intensity of the organic EL element 35 is maintained as shown in FIG. However, the frame frequency can be reduced.

Also, as with the liquid crystal panel 1, by dividing the entire screen into a full-color display area and a text display area, the text display area does not have to be rewritten every frame, so that power consumption can be reduced. FIG. 17 is a diagram showing average power consumption required for data rewriting in the text display area and the full-color display area.

As described above, even when the organic EL panel is used, the drive voltage can be lowered without degrading the display quality without rewriting the text display area every frame as in the liquid crystal panel 1. Reduction of power consumption can be realized.

(Program and recording medium)
Finally, each unit included in the display device 100 may be configured by hardware logic. Or you may implement | achieve by software using CPU as follows.

That is, the display device 100 includes a CPU that executes instructions of a program that realizes each function, a ROM that stores the program, a RAM that expands the program into an executable format, and a memory that stores the program and various data. Storage device (recording medium). With this configuration, the object of the present invention can also be achieved by a predetermined recording medium.

This recording medium only needs to record the program code (execution format program, intermediate code program, source program) of the program of the display device 100, which is software that realizes the functions described above, so that it can be read by a computer. This recording medium is supplied to the display device 100. Thereby, the display device 100 (or CPU or MPU) as a computer may read and execute the program code recorded on the supplied recording medium.

The recording medium that supplies the program code to the display device 100 is not limited to a specific structure or type. That is, the recording medium is, for example, a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, or a disk including an optical disk such as CD-ROM / MO / MD / DVD / CD-R. System, a card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM.

Further, even if the display device 100 is configured to be connectable to a communication network, the object of the present invention can be achieved. In this case, the program code is supplied to the display device 100 via the communication network. The communication network is not limited to a specific type or form as long as it can supply the program code to the display device 100. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication network, etc. may be used.

The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even with wired lines such as IEEE1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), 802.11 wireless, HDR, mobile phone It can also be used by radio such as a telephone network, a satellite line, and a terrestrial digital network.

The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope shown in the claims, and the present invention is also applied to an embodiment obtained by appropriately combining technical means disclosed in the embodiment. It is included in the technical scope of the invention.
(Other)
In the display device according to one aspect of the present invention, each pixel of the display panel includes RGB subpixels, and the control unit starts from 1 bit per subpixel in the input data. The signal driver may be controlled using the image data assigned in 4 bits as the first image data, and the image data other than the data assigned in 1 to 4 bits per subpixel as the second image data. preferable.

According to the above configuration, in the case of 1 to 4 bit image data per subpixel in the acquired input data, the image data is supplied to the signal line as the first image data at a lower frame frequency. If the image data is other than that, the second image data is controlled to be supplied to the signal line at the normal frame frequency.

1-bit image data is “FF” or “00” data, and when applied to an RGB 3-color panel, binary 8-color display is performed. Note that when “FF” or “00” is input to the signals of the RGB sub-pixels forming one pixel, a monochrome image is displayed because the signal is displayed in either white or black.

In the display device according to one embodiment of the present invention, it is determined whether or not the input data includes multi-tone text data. If the multi-tone text data is included, the text data is It is preferable that conversion means for converting data into 1 to 4 bits per subpixel is provided, and the control means preferably uses the text data converted by the conversion means as the first image data.

For example, the input data may include multi-tone text data. Therefore, it is determined whether or not multi-tone text data is included in the input data. When multi-tone text data is included, the input data is converted into 1-bit to 4-bit data, thereby lowering the frame frequency. The area that can be driven with increases. Therefore, power consumption can be further reduced.

In the display device according to one embodiment of the present invention, the control unit supplies the first image data and the second image data at the same time, and then the next time, the first image data and the second image data. It is preferable to perform control so that only the second image data is supplied in even frames until data is supplied simultaneously.

For example, when the polarity of writing image data is reversed for each frame, and when the number of frames in which the first image data is written is 10 cycles, the data writing polarity is always biased to one side. In this case, for example, “burn-in” occurs in the liquid crystal panel, resulting in a short life.

Therefore, after the first image data and the second image data are supplied simultaneously, only the second image data is supplied in an even number of frames, and the first image data and the second image data are supplied simultaneously again. Accordingly, image data can be written without being biased to a certain polarity, so that occurrence of burn-in can be suppressed.

The display device according to an aspect of the present invention further includes a counting unit that counts a pause frame period during which the first image data is not supplied, and the control unit instructs to rewrite the first image data in the pause frame. When the input data including is acquired, the signal driver is controlled to supply the first image data in the frame next to the pause frame, and the counting means newly starts the pause frame from the next frame. It is preferable to count the period.

Thus, for example, even if the first image data rewrite instruction is received during the pause frame period, the pause frame period can be restarted immediately after the rewrite.

Further, it is preferable that the rewrite instruction includes a size change instruction for the first image data.

Thus, for example, even if an instruction to change the size of the first image data is received during the pause frame period, the pause frame period can be restarted immediately after rewriting.

In the display device according to one embodiment of the present invention, the display panel is preferably a liquid crystal display panel or an organic EL display panel.

According to the above configuration, multi-tone color display can be suitably performed and power consumption can be reduced.

The display device may be realized by a computer. In this case, a program for causing a computer to operate as each of the above-described means and a computer-readable recording medium recording the program also fall within the scope of the present invention.

The present invention can be suitably used for display devices such as an electronic paper, a mobile phone, and an electronic dictionary provided with a liquid crystal panel or an organic EL panel, for example.

1 Liquid crystal panel (display panel)
2 Gate driver 3 Source driver (signal driver)
4 Power supply 5 Controller (control means)
6 Backlight 7 CPU (Conversion means)
13 Switching element 100 Display device

Claims

A display panel in which a plurality of scanning lines and a plurality of signal lines are arranged to cross each other;
A signal driver that supplies image data to be displayed on the display panel to each of the plurality of signal lines;
The signal line that acquires the input data including the image data and supplies the first image data included in the acquired input data is more than the signal line that supplies the second image data included in the input data. Control means for controlling the signal driver so as to supply the first image data at a lower frame frequency,
The display device characterized in that the control means uses part of the input data as the first image data and the rest as the second image data.
Each pixel of the display panel is composed of RGB subpixels,
The control means uses, as the first image data, image data allocated from 1 to 4 bits per subpixel of the input data, and is allocated from 1 to 4 bits per subpixel. The display device according to claim 1, wherein the signal driver is controlled with the second image data other than image data.
It is determined whether or not multi-tone text data is included in the input data. If multi-tone text data is included, the text data is converted into data of 1 to 4 bits per sub-pixel. Conversion means for converting,
The display device according to claim 2, wherein the control unit uses the text data converted by the conversion unit as the first image data.
The control means supplies the first image data and the second image data at the same time until the next time the first image data and the second image data are supplied at the same time. The display device according to any one of claims 1 to 3, wherein only the even frames are supplied.
Counting means for counting a pause frame period in which the first image data is not supplied;
The control means controls the signal driver to supply the first image data in a frame next to the pause frame when acquiring input data including a rewrite instruction for the first image data in the pause frame. And
5. The display device according to claim 1, wherein the counting unit newly counts the pause frame period from the next frame.
6. The display device according to claim 5, wherein the rewrite instruction includes a size change instruction of the first image data.
The display device according to any one of claims 1 to 6, wherein the display panel is a liquid crystal panel or an organic EL panel.
A display panel in which a plurality of scanning lines and a plurality of signal lines are arranged so as to intersect each other, and a signal driver that supplies image data to be displayed on the display panel to each of the plurality of signal lines An apparatus control method comprising:
The signal line that acquires the input data including the image data and supplies the first image data included in the acquired input data is more than the signal line that supplies the second image data included in the input data. A control step for controlling the signal driver to supply the first image data at a lower frame frequency,
In the control step, a part of the input data is the first image data, and the rest is the second image data.
A program for operating a computer as each means of the display device according to any one of claims 1 to 7.
The computer-readable recording medium which described the program of Claim 9.