JP2894473B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for information equipment, communication equipment, video equipment, game equipment and the like which are used in a portable manner, and as a display device for equipment mounted on a moving body such as a ship or an automobile. It is suitable for use.

[0002]

2. Description of the Related Art Conventionally, a display device such as a notebook type personal computer which is used in a portable manner uses a TFT active matrix type liquid crystal display panel in which a plurality of pixels are arranged in a matrix in the horizontal and vertical directions. A power supply voltage is supplied from a battery to the liquid crystal display panel, and the liquid crystal display panel is driven by a driver, in this case, a source and a gate driver, to display an image.

More specifically, in this liquid crystal display panel, a plurality of signal electrodes 1, scanning electrodes 2, TFTs 3, and pixel electrodes 4 are formed in a matrix on one insulating substrate (not shown) as shown in FIG. At the same time, a common electrode 5 is formed on the other insulating substrate (not shown) facing the same, and display by each pixel constituted by a liquid crystal layer interposed between the common electrode 5 and each pixel electrode 4 is performed. The scanning is performed by line-sequential scanning using the signal electrodes 1 and the scanning electrodes 2.

For example, when a scanning voltage is applied from the gate driver 6 to the scanning electrodes 2 on the first line, the TFTs 3 on the first line connected to the scanning electrodes 2 are turned on, and the pixel electrodes 4 on the first line are connected. Each signal electrode 1 is connected to each pixel, and a signal voltage (that is, an image signal) is applied from the source driver 7 to each pixel on the first line.
Therefore, by repeating such an applying operation (scan driving) in the horizontal cycle for each line sequentially from the first line, an image signal for one field can be displayed on the liquid crystal display panel. The image is reproduced by repeating every field, that is, in a vertical cycle. Note that the polarity of the signal voltage is inverted for each line and each field so that no DC component is applied to the liquid crystal display panel.

[0005]

By the way, the driving voltage of the liquid crystal in such a display device has been increasing due to the necessity of a high duty, and the power supply voltage to the liquid crystal display panel is set to be relatively high. ing. As a result, power consumption during image display increases, which is a problem for a display device such as a portable device having a limited power supply capacity such as a battery.

The present invention has been made in view of the above points, and has as its object to provide a display device capable of reducing power consumption without deteriorating the quality of a display image on a display unit to the left. It is assumed that.

[0007]

In order to achieve the above object, according to the present invention, in a display device for driving a display unit by a driving unit to display an image signal, an image signal supplied to the display unit is displayed. Storage means for storing, a comparison means for comparing an image signal read from the storage means with an image signal supplied to the display unit to determine whether to display a still image or an operation image, and display the still image by the comparison means And a control unit for driving the display unit to thin out by the driving unit when it is determined that the display unit is compared. Specifically, the storage means stores the image signal supplied to the display unit for one field, and the comparison means stores the image signal of the previous field read from the storage unit and the current signal supplied to the display unit. This is to compare with the image signal of the field. Further, the display unit is a liquid crystal display panel, and the storage unit is a nonvolatile memory. The thinning drive of the display unit
Can be performed in pixel units, pixel units or lines
It is also possible to perform in units.

[0008]

According to such a configuration, during display of a moving operation image, the display section is driven in the same manner as usual, and a high-definition image is expressed, thereby making it easy to see a moving image. During the display of a still image, a higher definition is not required to the left because there is no movement, and the visual afterimage effect can be used to the maximum. Power consumption is reduced by minimizing the required drive. Especially,
When thinning drive is performed in pixel units or line units
Changes the pixels or lines to be decimated from field to field.
Can increase the sharpness of the displayed image
Clear when not thinning drive, while changing parts and parts
You can keep in time. This allows long-term thinning drive
Display power while greatly reducing power consumption.
Quality can be maintained above a certain level.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A display device of a personal computer using a liquid crystal display panel as an embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, the driving of the liquid crystal display panel is normally performed during the display of the operation image, but is performed by thinning out during the display of the still image, for example, so as to suppress the driving to the minimum necessary for maintaining the image display. Such a drive control function is added to the display device side so as to be able to respond to the display of various devices.

[0010] More specifically, it is configured as shown in FIG. 1. Reference numeral 8 denotes a plurality of pixels (48 in this case) in the horizontal and vertical directions.
A TFT active matrix type liquid crystal display panel in which (0 × 640 pixels) are arranged in a matrix. A driver 9 drives the liquid crystal display panel 8 line-sequentially based on a timing signal from a controller 10 to perform image display. A gate driver sequentially selects the lines from the line 480 to the line 480, and a source driver for applying an image signal to each pixel on the line selected by the gate driver, that is, 640 pixels.

Reference numeral 11 denotes a personal computer CPU for controlling image display on the liquid crystal display panel 8. The CPU 11 controls a timing signal output from the controller 10 in accordance with an operation key input on the keyboard side. The image display is controlled. Reference numeral 12 denotes a controller for extracting an image signal supplied from the personal computer to the liquid crystal display panel 8 and storing the image signal in a memory 13. The memory 13 is a non-volatile memory such as an EEPROM or an FRAM which does not require a special battery backup device. And the image signal supplied to the liquid crystal display panel 8 is 1
Fields are stored.

Reference numeral 14 compares the image signal of the current field supplied to the liquid crystal display panel 8 with the image signal of the previous field read from the memory 13 to determine whether to display an operation image such as screen scrolling or a still image display. In the comparator,
If the image signal of the current field is not different from the image signal of the previous field, that is, if the image signal is not updated, it is determined that the image is a still image display. Is determined. Reference numeral 15 denotes a controller that controls the driving of the liquid crystal display panel 8 by the driver 9 based on the comparison and determination by the comparator 14. When the comparison is determined to be a still image display, the controller 9 controls the driver 9 to change the liquid crystal display panel 8 to a pixel. The thinning-out drive is performed in units, lines, or fields, and is suppressed to the minimum necessary for maintaining image display. In addition, by this thinning drive,
In order to prevent the DC component from being applied to the liquid crystal display panel 8, it is assumed that countermeasures such as shifting the thinned portion in pixel units, line units, or field units are taken. Picture
When performing thinning drive in elementary units or line units,
Instead of culling the entire field
When thinning out elements or lines, feel the part to be thinned out.
By changing the setting for each mode, the sharpness of the displayed image is
It is possible to prevent the lower part partially and changing the part
Display image is constant even if the thinning drive is continued for a long time.
The sharpness can be maintained. Also the field
When performing thinning drive in units, the thinning period ends and drive
When the display is restarted, the displayed image sharpens sharply,
When thinning drive is performed in units of places or lines, such a sudden
The change in sharpness hardly occurs.

Therefore, when the image signal of the operation image is supplied to the display device having such a configuration, the image signal of the current field supplied from the driver 9 to the liquid crystal display panel 8 and the image signal of the current field are stored in the memory 13. The image signal of the previous field does not become the same, that is, the image signal is updated for each field, and the comparator 14 determines that the image is an operation image display. Therefore, in such a case, the liquid crystal display panel 8 is normally driven by the controller 15 so that the operation image display is not hindered, that is, by sequentially selecting the first line to the 480th line. By applying an image signal to each of the 640 pixels on the selected line and repeating this for each field, an image with high definition can be reproduced.

Conversely, when a still image signal is supplied to the display device, the current field image signal supplied from the driver 9 to the liquid crystal display panel 8 and the previous field image signal stored in the memory 13 are displayed. The signal becomes the same, and the comparator 14 determines that the still image is displayed. Therefore, the controller 1
5, the drive of the liquid crystal display panel 8 can be reduced to the minimum drive required for maintaining the image display, and the power consumption can be reduced accordingly.

FIG. 2 is a flow chart for explaining such drive control. As shown in FIG.
The predetermined line number in the vertical (Y) direction of the liquid crystal display panel 8 of 0 × 640 pixels is Ym, and the predetermined pixel number in the horizontal (X) direction on the line is Xn.
Assuming that the image signal of the -1st field is displayed on the liquid crystal display panel 8, at step # 10, the i-1
The image signal of the third field is stored in the memory 13. Then, before the image signal of the next i-th field is displayed on the liquid crystal display panel 8 in step # 20, the image signal of the i-th field is stored in the memory 13 in step # 10 in step # 15. Compare with the image signal of the (i-1) th field.

If the two image signals are not the same, for example, during the comparison, the image signal X of the (i-1) -th field
If (i-1) n and Y (i-1) m do not match the image signals X (i) n and Y (i) m of the i-th field,
The process proceeds to step # 45 assuming that the image is an operation image, and the liquid crystal display panel 8 is driven as usual, so that the image signal of the i-th field is displayed in step # 20. Conversely, if the two image signals are the same, it is determined that the image is a still image, and the process proceeds to step # 50 to drive the liquid crystal display panel 8 to thin out.
Display of the image signal of the i-th field is performed in step # 20.
Let me do it.

Then, in step # 25, the image signal of the i-th field is stored in the memory 13, and the same operation is repeated thereafter. That is, step #
Before the image signal of the next (i + 1) th field is displayed on the liquid crystal display panel 8 at 35, at step # 30, the i
The image signal of the (+1) th field is compared with the image signal of the i-th field stored in the memory 13 in step # 25, and the process proceeds to step # 45 or # 50 according to the comparison result, and proceeds to step # 40. Similarly, the image signal of the (i + 1) th field is stored in the memory 13.

In this embodiment, the liquid crystal display panel is T
Although the case of FT has been described, the case of STN may be used.
In that case, the liquid crystal display panel is driven by a segment driver and a common driver. Further, a picture tube, a light-emitting diode, a plasma display, or the like may be used as the display unit. In these cases, the power consumption is reduced by performing the thinning-out operation when a still image is displayed. .

[0019]

As described above, according to the display device of the present invention, the liquid crystal display panel is normally driven when displaying an operation image so as not to hinder the operation image display. At the same time, when the still image is displayed, the liquid crystal display panel is thinned out to reduce the power consumption, so that a display device with low power consumption and little deterioration in image quality can be realized. In particular, pixel units
Or a certain level by thinning out drive in line units
Ensure low power consumption while maintaining high image quality
It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram for explaining the drive control.

FIG. 3 is a diagram showing predetermined line numbers and pixel numbers of the liquid crystal display panel.

FIG. 4 is a diagram showing a driving example of a conventional liquid crystal display panel.

[Explanation of symbols]

 8 LCD panel 9 Driver 13 Memory 14 Comparator 15 Controller

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G09G 3/00-5/40 H04N 9/00-11/24 G06T 7/20

Claims (4)

(57) [Claims] In a display device for driving a display unit by a driving unit to display an image signal, a storage unit for storing an image signal supplied to the display unit, and an image signal read from the storage unit. A comparison unit that compares the image signal supplied to the display unit to determine whether the display is a still image display or a motion image display; and if the comparison unit determines that the display is a still image display, the display unit is thinned by the driving unit. A display device, comprising: control means for driving. 2. A display device for driving a display unit by a driving unit to display an image signal, wherein the storage unit stores an image signal supplied to the display unit for one field, and is read from the storage unit. A comparing unit that compares the image signal of the previous field with the image signal of the current field supplied to the display unit to determine whether to display a still image or an operation image, and the comparing unit compares and determines that the image is a still image display. And a control means for thinning out the display unit by the driving means. 3. The display device according to claim 1, wherein the display unit is a liquid crystal display panel, and the storage unit is a nonvolatile memory. 4. The control means controls the display unit.
By the driving unit, thinning is performed in pixel units or line units.
3. The driving method according to claim 1, wherein
A display device according to claim 1.