JPH0646277B2 - Liquid crystal display with built-in storage capacity - Google Patents

Description

The present invention relates to a method of forming a storage capacity in a matrix arrangement type liquid crystal image display device having a selection transistor and a storage capacity for each pixel without extremely reducing the aperture ratio of the pixel.

In a liquid crystal display device using a transistor array using a thin film, a pixel signal written with N pixel selection transistors of each pixel and an image signal written with N transistors are FFed to the transistors, and then in the next cycle. It is necessary to hold until a new image signal is written. At this time, if there is not enough storage capacity between the pixel and the common potential or the ground potential, there is no ability to hold the image signal, and the black-and-white contrast ratio of the entire image deteriorates.

Therefore, when actually making a matrix type liquid crystal display device, it is general to make a storage capacitor of several hundred fF to several pF between the pixel and the common potential or the ground potential.

FIG. 1 is a plan view of a pixel portion of a liquid crystal display device having a built-in storage capacitor formed between a conventional pixel and a gate region in the previous stage (which is kept at the ground potential when the pixel is driven). 2 is a sectional view of the same. After the transparent conductive film 4 for pixel electrodes (for example, IT film) is selectively deposited on the insulating substrate 1, the insulating film 3 (for example, silicon oxide) having a thickness corresponding to the capacitance value of the storage capacitance is entirely deposited. Then, a counter electrode 9 extending from the gate line of the previous stage is formed thereon to form a storage capacitor, and then the transistor element portion 6 is sequentially formed.

In a liquid crystal display device having such a structure, the aperture ratio becomes a sacrifice for obtaining a sufficient storage capacity without transmitting light in a portion where the storage capacity is formed.

In order to eliminate these drawbacks, it is an object of the present invention to provide a liquid crystal display device having a structure capable of incorporating a sufficient storage capacity without extremely reducing the aperture ratio.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 3 is a plan view of a pixel portion of a liquid crystal display device showing an embodiment of the present invention, and FIG. 4 is a sectional view thereof. After the transparent conductive film 4 for pixel electrodes (for example, IT film) is selectively deposited on the insulating substrate 1, the insulating film 3 (for example, silicon oxide) having a thickness corresponding to the capacitance value of the storage capacitance is entirely deposited. Then, the counter electrode 9 extending from the gate line in the previous stage is formed thereon to form a storage capacitor. However, when the transistor element portion 6 is sequentially formed thereafter, the counter electrode 9 and the transparent conductive film 4 for the pixel electrode are formed. A conductive film 10 (for example, Al-Si) for connecting the source terminal of the transistor element is covered with the gate insulating film 5 or a thin film layer corresponding thereto so as to cover the counter electrode 9 extending from the preceding gate line. To form. In the liquid crystal display device having such a structure, a larger storage capacity can be built in the same area in plan view as compared with the conventional structure. Therefore, the aperture ratio of the pixel portion can be made relatively large, and a bright and favorable liquid crystal display device can be provided as the entire system.

FIG. 5 is a plan view of a pixel portion of a liquid crystal display device showing another embodiment of the present invention, and FIG. 6 is a sectional view thereof. After sequentially forming each layer on the insulating substrate 1 in the same manner as in FIG. 4 to form the transistor element portion 6, the interlayer insulating film is formed.
11 is deposited on the entire surface and a light-shielding conductive film 12 is formed thereon. At this time, the light-shielding film 12 is selectively formed so as to planarly overlap with the portion forming the storage capacitor. However, the light shielding film 12 is electrically connected to the gate line in the previous stage.
In the liquid crystal display device having such a structure, compared with the structure of the liquid crystal display device according to the embodiment of the present invention shown in FIGS. A larger storage capacity can be built in the same area. Therefore, the aperture ratio of the pixel portion can be made sufficiently large, and a bright and good liquid crystal display device can be provided as a whole system.

As described above, according to the present invention, it is possible to provide a liquid crystal display device capable of forming a sufficient storage capacity in a smaller area and having a relatively high aperture ratio.

[Brief description of drawings]

FIG. 1 is a plan view of a pixel portion in a conventional liquid crystal display device with a built-in storage capacitor, and FIG. 2 is a sectional view thereof. FIG. 3 is a plan view of a pixel portion of a liquid crystal display device with a built-in storage capacitor according to an embodiment of the present invention, and FIG. 4 is a sectional view thereof. FIG. 5 is a plan view of a pixel portion of a liquid crystal display device with a built-in storage capacitor according to another embodiment of the present invention, and FIG. 6 is a sectional view thereof. 1 ... Insulating substrate 3 ... Storage capacitor insulating film 4 ... Pixel electrode transparent conductive film 5 ... Gate insulating film 6 ... Transistor element 7 ... Gate line 8 ... Drain path 9 ... Storage capacitor facing Electrode 10 …… Pixel electrode, conductive film for source terminal connection 11 …… Interlayer insulation film 12 …… Shade film

Claims (1)

[Claims] 1. A matrix-arranged liquid crystal display device having a built-in storage capacitor, wherein the storage capacitor is a transparent conductive film for pixel electrodes formed on an insulating substrate, on which a first memory is sequentially formed. From the insulating film for capacitance, the counter electrode for storage capacitor formed by extending from the previous gate line, the second insulating film for storage capacitor covering the counter electrode, and the conductive film for connection between the pixel electrode and the output terminal of the transistor A liquid crystal display device with a built-in storage capacitor, characterized in that conductive films formed by stretching are respectively laminated.