Active matrix display device

Abstract

An active matrix display device is provided in which parasistic capacitance or the like is suppressed by forming a thick insulating film around an organic semiconductor film, and disconnection or the like does not occur in an opposing electrode formed on the upper layer of the thick insulating film. In the active matrix display device, first, a bank layer composed of a resist film is formed along data lines and scanning lines. By depositing an opposing electrode of a thin film luminescent element on the upper layer side of the bank layer, capacitance that parasitizes the data lines can be suppressed. Additionally, a discontinuities portion is formed in the bank layer. Since the discontinuities portion is a planar section which does not have any a step due to the existence of the bank layer, disconnection of opposing electrode does not occur at this section. When an organic semiconductor film is formed by an ink jet process, a liquid material discharged from an ink jet head is blocked by the bank layer.

Description

[0001] The present invention relates to an active matrix display device in which a thin film luminescent element such as an EL (electroluminescence) element or LED (light emitting diode) element, that emits light by application of a driving current to an organic semiconductor film, is driven and controlled by a thin film transistor (hereinafter referred to as a TFT).[0002] Active matrix display devices using current-controlled luminescent elements such as EL elements or LED elements have been disclosed. Since luminescent elements used in display devices of this type are self-luminescent, backlights are not required, unlike in liquid crystal display devices, and the viewing angle dependence is small, all of which are advantageous.[0003] FIG. 13 is a block diagram of an active matrix display device which uses organic thin-film EL elements of the charge-injection type as described above. In an active matrix display device 1A shown in the drawing, on a transparent substrate 10, a plural...

AI Technical Summary

Benefits of technology

[0011] In the present invention, since the opposing electrode is formed at least on the entire surface of the display area and opposes the data lines, a large amount of capacitance parasitizes the data lines if no measures are taken. In the present invention, however, since a thick insulating film is interposed between the data lines and the opposing electrode, parasitization of capacitance in the data lines can be prevented. As a result, the load on the data side drive circuit can be decreased, resulting in lower consumption of electric power or faster display operation. If a thick insulating film is formed, although the insulating film may form a large step and disconnection may occur in the opposing electrode formed on the upper layer side of the insulating film, in the present invention, a discontinuities portion is configured at a predetermined position of the thick insulating film and this section is planar. Accordingly, the opposing electrodes in the individual regions are electrically connected to each other through a section formed in the planar section, and even if disconnection occurs at a step due to the existence of the insulating film, since electrical connection is secured through the planar section which corresponds to the discontinuities portion of the insulating film, disadvantages resulting from disconnection of the opposing substrate do not occur. Therefore, in the active matrix display device, even if a thick insulating film is formed around the organic semiconductor film to suppress parasitic capacitance and the like, disconnection does not occur in the opposing electrode formed on the upper layer of the insulating film, and thereby display quality and reliability of the active matrix display device can be improved.

[0016] In the present invention, preferably, in the region in which a pixel electrode is formed, a region overlapping the region in which the conduction control circuit is formed is covered with the insulating film. That is, preferably, in the region in which the pixel electrode is formed, the thick insulating film is opened only at a planar section in which the conduction control circuit is not formed, and the organic semiconductor film is formed only in the interior of this section. In such a configuration, display unevenness due to the layer thickness irregularity of the organic semiconductor film can be prevented. In the region in which the pixel electrode is formed, in a region overlapping the region in which the conduction control circuit is formed, even if the organic semiconductor film emits light because of a driving current applied from the opposing electrode, the light is shielded by the conduction control circuit and does not contribute to the display. The driving current that is applied to the organic semiconductor film in the section which does not contribute to the display is a reactive current in terms of display. In the present invention, the thick insulating film is formed in the section in which such a reactive current should have flowed in the conventional structure, and a driving current is prevented from being applied thereat. As a result, the amount of current applied to the common feeder can be reduced, and by decreasing the width of the common feeder by that amount, the emission area can be increased, thereby display characteristics such as luminance and contrast ratio can be improved.

[0018] In the present invention, when the insulating film is composed of an organic material such as a resist film, a thick film can be formed easily. In contrast, when the insulating film is composed of an inorganic material, an alteration in the organic semiconductor film can be prevented even if the insulating film is in contact with the organic semiconductor film.

Problems solved by technology

If such disconnection of the opposing electrode op occurs at the step bb, the opposing electrode op in this portion is insulated from the surrounding opposing electrode op, resulting in a dot defect or line defect in display.

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