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Light emitting device and electronic equipment

a light emitting device and electronic equipment technology, applied in the direction of static indicating devices, instruments, transistors, etc., can solve the problems of lowering the luminance of oled which accompanies degradation, increasing the current consumption of light emitting devices, and unable to display images in desired colors

Inactive Publication Date: 2003-10-09
SEMICON ENERGY LAB CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem in putting a light emitting device into practice is lowering in luminance of OLED which accompanies degradation of its organic light emitting material.
Then the difference in luminance between OLEDs of different colors will be noticeably large as time passes, making it impossible for the light emitting device to display an image in desired colors.
Since a change in temperature of the organic light emitting layer thus causes a change in OLED luminance, displaying an image in desired gray scales is difficult and current consumption of the light emitting device is increased accompanying a temperature rise.
It is impossible to obtain desired colors when OLEDs of different colors lose their luminance balance.
Therefore, the amount of current supplied to one pixel is changed as well as the gray scale number thereof when the gray scale number of other pixels that receive a current from the same wiring line as the one pixel is changed, making it impossible for the one pixel to keep a constant gray scale.
Therefore, the amount of current supplied to one given pixel is changed as well as the gray scale number thereof when the gray scale number of other pixels that receive a current from the same wiring line as the one pixel is changed, making it impossible for the one pixel to keep a constant gray scale.

Method used

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  • Light emitting device and electronic equipment
  • Light emitting device and electronic equipment

Examples

Experimental program
Comparison scheme
Effect test

embodiment 1

[0128] Embodiment 1

[0129] Next, described with reference to FIGS. 9 to 13 is a method of forming the light emitting device of the present invention. Here, the method of simultaneously forming, on the same substrate, transistors Tr2, Tr3 and Tr5 of the pixel, and transistors of a driving portion provided surrounding the pixel portion is described in detail according to steps. In addition, transistors Tr1 and Tr4 can be manufactured according to the manufacturing method of transistors Tr2, Tr3, and Tr5. The pixels shown in FIGS. 7, 8, 30A, 30B, and 30C can also be manufactured according to the manufacturing method shown in this embodiment.

[0130] This embodiment uses a substrate 900 of a glass such as barium borosilicate glass or aluminoborosilicate glass as represented by the glass #7059 or the glass #1737 of Corning Co. There is no limitation on the substrate 900 provided it has a property of transmitting light, and there may be used a quartz substrate. There may be further used a pl...

embodiment 2

[0175] Embodiment 2

[0176] In this embodiment, a method of manufacturing a light emitting device different from that in Embodiment 1 is described.

[0177] The process through the formation of the second interlayer insulating film 939 is the same as in Embodiment 5. As shown in FIG. 14 (A), after the second interlayer insulating film 939 is formed, a passivation film 981 is formed to contact the second interlayer insulating film 939.

[0178] The passivation film 981 is effective in preventing moisture contained in the second interlayer insulating film 939 from permeating the organic light emitting layer 950 through the pixel electrode 948 or a third interlayer insulating film 982. In the case where the second interlayer insulating film 939 includes an organic resin material, it is particularly effective to provide the passivation film 981 since the organic resin material contains a large amount of moisture.

[0179] In this embodiment, a silicon nitride film is used as the passivation film 9...

embodiment 3

[0196] Embodiment 3

[0197] This embodiment gives a description on the top view of the pixel shown in FIG. 7. FIG. 15 shows a top view of a pixel of this embodiment. Insulating films such as a insulating gate film and an interlayer insulating film are omitted from FIG. 15 in order to show positions of wiring lines and of semiconductor layers clearly. In FIG. 15, wiring lines formed on the same layer are similarly hatched. The top view in FIG. 15 is of the pixel after a pixel electrode is formed and before an organic light emitting layer is formed.

[0198] The pixel shown in FIG. 15 has one scanning line 211, one signal line 210, and one power supply line 217. Portions of the scanning line 211 are denoted by 212 and 213 and respectively serve as gate electrodes of transistors Tr4 and Tr5.

[0199] The transistor Tr4 has a source region and a drain region one of which is connected to the signal line 210 and the other of which is connected to a drain region of a transistor Tr1 through a conne...

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PUM

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Abstract

A display device capable of keeping the luminance constant irrespective of temperature change is provided as well as a method of driving the display device. A current mirror circuit composed of transistors is placed in each pixel. A first transistor and a second transistor of the current mirror circuit are connected such that the drain current of the first transistor is kept in proportion to the drain current of the second transistor irrespective of the load resistance value. The drain current of the first transistor is controlled by a driving circuit in accordance with a video signal and the drain current of the second transistor is caused to flow into an OLED, thereby controlling the OLED drive current and the luminance of the OLED.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to an OLED (organic light emitting diode) panel obtained by forming an OLED on a substrate and sealing the OLED between the substrate and a cover member. The invention also relates to an OLED module in which an IC including a controller, or the like, is mounted to the OLED panel. In this specification, `light emitting device` is the generic term for the OLED panel and for the OLED module. Electronic equipment using the light emitting device is also included in the present invention.[0003] 2. Description of the Related Art[0004] Being self-luminous, OLEDs eliminate the need for a backlight that is necessary in liquid crystal display devices (LCDs), and thus they are most suitable when manufacturing thinner devices. Also, the self-luminous OLEDs are high in visibility and have no limit in terms of viewing angle. These are the reasons for the attention that light emitting devices using the OLEDs are receiving in recen...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H05B44/00G09G3/20G09G3/30G09G3/32G11C7/00H01L27/32H01L29/786H01L31/036H01L51/50H05B33/14
CPCG09G3/2022G09G3/3241G09G3/3266G09G3/3283G09G2300/0426H01L27/3244G09G2300/0842G09G2320/0266G09G2320/043H01L27/3211G09G2300/0809H10K59/35H10K59/12
Inventor KOYAMA, JUN
Owner SEMICON ENERGY LAB CO LTD
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