JP2003280551A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply current to an electric field light emitting element without lowering an opening ratio of a pixel. <P>SOLUTION: In an image display device in which light emitting elements 5 and transistors for driving the light emitting elements 8 are formed on the same substrate 1 and which has a plurality of display cells each of which has structure in which the light emitting element 5 and the driving transistor 8 are connected between a power source supplying line and a ground line and which displays the image by selectively driving the driving transistors 8, power source supplying pillars 21 for supplying currents to respective display cells are formed on a common electrode for power source 20 which is formed on the surface of the counter substrate 13 parallel to the substrate 1. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using a current driving type light emitting element such as an organic electroluminescent element.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing an example of an image display device using an organic electroluminescent device, FIG. 2 (a) is a sectional view, and FIG.
(B) is a top view. Interlayer insulation layer 2 on glass substrate 1,
3 are laminated, and an anode 4 made of a transparent conductive film that defines each light emitting area, an organic light emitting layer 5, and a cathode 6 are formed on the entire surface. In addition, a power supply line 7 is provided on the glass substrate 1.
A current driving thin film transistor 8 supplied with current through the transistor 8, a transistor 9 for controlling ON / OFF of the transistor 8, and a vertical electrode 1 for selecting a display cell to emit light.
0, lateral electrodes 11 are formed. The vertical electrode 10 and the horizontal electrode 11 are insulated by the interlayer insulating layer 2, each transistor is protected by the interlayer insulating layer 3, and the surface on the transistor is smoothed so that the current driving thin film transistor 8 and the anode 4 are insulated from each other. Connected through layer 3 through holes.
Further, a counter sealing plate 12 is provided for sealing the image device so as to cover the entire cathode 6.

In the image display device having such a structure, when the transistor 9 of the display cell selected by the vertical electrode 10 and the horizontal electrode 11 is turned on, the current driving thin film transistor 8 becomes conductive and the anode 4 is supplied through the power supply line 7. A current flows through the organic light emitting layer 5 and the cathode 6, and the selected cell emits light. This light emission state is OFF for the transistor 9.
Until the signal for is added. An image is displayed by selectively driving each light emitting cell arranged in a matrix in this way with a transistor.

[0004]

By the way, a current-driven light-emitting element such as an organic electroluminescence element emits light when a current is passed through it. Therefore, it is necessary to keep the current flowing in order to maintain the light-emitting state. Therefore, in order to perform active matrix driving of the current-driven light emitting device, at least two active devices in total, that is, a device for keeping current flowing and a device for controlling this device, are required. In addition, a dedicated current supply line is required to keep the current flowing.

As shown in FIG. 2, the light emitting element is connected to the current driving transistor 8 and is connected between the common power supply line 7 and the common ground line (cathode). One light emitting element requires at least two transistors, and the wiring requires four electrodes of a data line and a scanning line (digit electrode and horizontal electrode) for selecting the light emitting element, a power supply line, and a ground line. Therefore, it has a complicated structure. In particular, when the number of display pixels increases, the power supply line needs to have a low resistance because the current supply capability needs to be increased, and if the line width is increased to reduce the resistance, the aperture ratio of the pixel decreases. There is a problem.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and it is possible to reduce the aperture ratio of pixels without lowering the aperture ratio.
The purpose is to make it possible to supply a current to the electroluminescent device. Therefore, the invention according to claim 1 has a plurality of light emitting elements and a transistor for driving the light emitting element formed on the same substrate, and the light emitting element and the driving transistor are connected between a power supply line and a ground line. In an image display device having a display cell and selectively driving a driving transistor to display, in order to supply a current to each display cell to a common electrode for power supply formed on a counter substrate surface parallel to the substrate. The power supply electrode column of is formed. According to a second aspect of the present invention, the power supply electrode column is connected to a power supply pad provided in a notch formed in a part of the cathode formed on the light emitting element, and is connected to the driving transistor through the pad. Is characterized by.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are diagrams illustrating an example of an image display device of the present invention, FIG. 1A is a cross-sectional view, and FIG. 1B is a top view. Note that the same numbers as those in FIG. 2 indicate the same contents, and thus detailed description thereof will be omitted. Glass substrate 1
An interlayer insulating layers 2 and 3, an anode 4 made of a transparent conductive film, an organic light emitting layer 5 and a cathode 6 are formed on the substrate, and a current is supplied to the anode 4 through a current driving thin film transistor 8 formed on the glass substrate 1.

In the present embodiment, the counter substrate 13 (the counter sealing plate 12 shown in FIG. 2) arranged so as to face the glass substrate 1 is arranged.
(Corresponding to the above) on the entire surface facing the cathode 6
0 is formed, and a power supply electrode column 21 for supplying a current to the current driving thin film transistor 8 of each display cell is formed on the common electrode 20. The power supply electrode column is made of metal or conductive resin and also has a function as a spacer between the substrates. Then, a notch is formed in each of the cathode 6 and the organic light emitting layer 5 formed on the entire surface of the glass substrate 1 side for each anode that defines each light emitting area of the display cell, and a power supply pad 22 is provided in this notch. It is formed, and this is connected to each power supply electrode column 21.

In such a configuration, since the voltage is constantly applied to the current driving thin film transistor 8 from the power source common electrode 20 of the counter substrate through the power source electrode column 21 and the power source pad 22, the vertical electrode 10 and the horizontal electrode 11 are provided. When the transistor 9 of the display cell selected in step 1 is turned on, the corresponding current driving thin film transistor 8 becomes conductive, and a current flows through the anode 4, the organic light emitting layer 5 and the cathode 6, and the selected cell emits light.

As described above, since no power supply line is formed on the glass substrate 1 as in the prior art, and current is supplied from the power supply electrode column 21 extending vertically from the counter substrate, a light emitting area is formed by the power supply line. There is no limitation, and a high aperture ratio can be secured. Further, the counter substrate 12 is provided as a sealing plate even in the conventional one, and is also used for forming the common electrode for power supply, so that the aperture ratio can be increased while maintaining the conventional structure. .

[0011]

When a current-driven light emitting device such as an organic light emitting device is driven by active matrix, a common line for supplying power to each pixel is conventionally formed on the same surface as the light emitting device, and this is the aperture of the pixel. However, in the present invention, the common electrode for power supply is formed on the opposing sealing substrate and the electric current is supplied to each pixel through the electrode column from here, so that the light emitting element side No power supply line is required on the substrate, and a high aperture ratio can be realized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of an image display device of the present invention.

FIG. 2 is a diagram showing a conventional example of an image display device using an organic electroluminescent element.

[Explanation of symbols]

1 ... Glass substrate, 2,3 ... Interlayer insulating layer, 4 ... Anode, 5 ...
Organic light emitting layer, 6 ... Cathode, 7 ... Power supply line, 8 ... Current driving thin film transistor, 9 ... Transistor, 10 ... Vertical electrode, 11 ... Horizontal electrode, 12 ... Opposing sealing plate, 13 ... Opposing substrate, 20 ... Power supply Common electrode, 21 ... Power supply electrode column, 2
2 ... Power supply pad.

Claims (2)

[Claims] 1. A plurality of display cells having a structure in which a light emitting element and a transistor for driving the light emitting element are formed on the same substrate, and the light emitting element and the driving transistor are connected between a power supply line and a ground line. In the image display device that selectively drives and displays the driving transistor, a power supply electrode for supplying a current to each display cell to a common electrode for power supply formed on a counter substrate surface parallel to the substrate. An image display device characterized in that a pillar is formed. 2. The power supply electrode column is connected to a power supply pad provided in a cutout part formed in a part of a cathode formed on the light emitting element, and is connected to a driving transistor through the pad. The image display device according to claim 1, wherein the image display device is a display device.