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Semiconductor display device and the driving method thereof

A technology for display devices and semiconductors, applied to static indicators, cathode ray tube indicators, instruments, etc., which can solve problems such as false contours, increased drive circuits, and short subframe periods

Inactive Publication Date: 2009-03-04
SEMICON ENERGY LAB CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, in the driving method disclosed in Patent Document 1, the total grayscale level and the number of subframe periods of one frame period are equal to each other. Therefore, when increasing the number of subframe periods in order to increase the total grayscale level, it is necessary to shorten Each sub-frame period. However, in each sub-frame period, the video signal usually needs to be input to the pixels of all rows. Therefore, when the sub-frame period is too short, it is necessary to increase the driving frequency of the driving circuit. When considering the reliability of the driving circuit It is not preferable to make the sub-frame period shorter than necessary when the nature of the
[0008] Note that each subframe period can be extended to a certain extent by extending the frame period. However, lengthening the frame period is not preferred, because it cannot achieve a sharp increase in the total gray level, but more false contours are generated.
[0009] In Patent Document 1, there is also described a technique of pseudo-increasing the total grayscale level to be displayed without increasing the number of subframe periods, in which image processing such as dithering is performed. However, by performing Image processing can display a large total grayscale level, and the displayed image seems to be sprinkled with sand, which inevitably leads to image quality degradation.

Method used

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  • Semiconductor display device and the driving method thereof
  • Semiconductor display device and the driving method thereof
  • Semiconductor display device and the driving method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0113] Next, use Figures 6A to 6C A circuit diagram depicting a pixel in a light emitting device of the present invention.

[0114] Figure 6A is an example of an equivalent circuit diagram of a pixel, which includes a signal line 6114, a power supply line 6115, a scanning line 6116, a light emitting element 6113, TFTs 6110 and 6111, and a capacitor 6112. A video signal is input to the signal line 6114.TFT through a signal line driver circuit The 6110 can control the supply of the video signal potential to the gate of the TFT 6111 according to the selection signal input to the scanning line 6116. The TFT 6111 can control the current supply to the light emitting element 6113 according to the potential of the video signal. The capacitor 6112 can hold the gate source of the TFT 6111 voltage. It should be noted that Figure 6A However, if the gate capacitance of the TFT 6111 or other parasitic capacitance is sufficient to maintain the gate-source voltage, the capacitor 6112 may...

Embodiment 2

[0119] In this embodiment, the timing at which each subframe period occurs is described in the case of the driving method described in FIG. 4 .

[0120] Fig. 7 is a timing diagram in the case of 4-bit grayscale display using the driving method shown in Fig. 4. In Fig. 7, the horizontal axis represents the subframe period SF within one frame period 1 to SF 9 The length of the vertical axis shows the selection order of the scan lines. From SF 1 Start the subframe period SF 1 to SF 9 The length ratio sequence is set to 1:1:1:1:1:2:2:3:3.

[0121] When each sub-frame period starts, each pixel of a row sharing the scan line performs video signal input. After the video signal is input to the pixel, the light-emitting element emits light or does not emit light according to the data of the video signal. The light-emitting element in each pixel Keep lighting up or not lighting up until the next subframe period starts according to the data of the video signal.

[0122] It should be...

Embodiment 3

[0125] In this example, using Figures 8A to 8C Describes the cross-sectional structure of a pixel in which the transistor for controlling the current supply to the light-emitting element is of the P-channel type. Note that in this specification, the potential in the anode and cathode of the light-emitting element can be controlled by the transistor One is called the first electrode, and the other is called the second electrode. In Figures 8A to 8C The description will be made in the case where the first electrode is an anode and the second electrode is a cathode. However, it is also possible that the first electrode is a cathode and the second electrode is an anode.

[0126] Figure 8A is a cross-sectional view of a pixel in the case where the transistor 6001 is a P-channel type and the light emitted from the light emitting element 6003 is extracted from the first electrode 6004 side. The first electrode 6004 of the light emitting element 6003 is electrically connected to ...

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PUM

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Abstract

The invention provides a semiconductor display device with less generation of a pseudo contour while the drive frequency of a driver circuit is suppressed. Furthermore, the invention provides a semiconductor display device with less generation of a pseudo contour while the decrease in image quality is suppressed. A semiconductor display device comprises a table storing data for determining a relationship between the gray scale level of a video signal and a subframe period for light emission in the plurality of subframe periods, a controller for changing a video signal in accordance with the data and outputting, and a panel whose pixel gray scale level is controlled in accordance with the outputted video signal. The number and the length of the plural subframe periods for each gray scale level of 2 or more are determined in accordance with a subframe ratio Rwhich is calculated in accordance with a sharing ratio Rdetermined by the frame frequency.

Description

technical field [0001] The invention relates to a semiconductor display device and a driving method thereof displayed by a time gray scale method. Background technique [0002] As a driving method of a light emitting device which is one of semiconductor display devices, a time gray scale method is known in which the light emitting period of pixels in one frame period is controlled using a binary voltage of a digital video signal to display gray scale. The response speed of the luminescent material is usually faster, so it is more suitable for the time gray scale method than the liquid crystal. In particular, when displaying through the time gray scale, one frame period is divided into multiple subframe periods. Then, the pixel according to The video signal in each sub-frame period determines whether to emit light or not. According to the above structure, the total actual light-emitting period of pixels in a frame period can be controlled by the video signal, thereby displayi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G09G3/30G09G3/20G09G5/00
Inventor 宫川惠介
Owner SEMICON ENERGY LAB CO LTD