Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Patent
1994-12-08
1996-11-19
Fahmy, Wael
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
359 54, G02F 11343
Patent
active
055768687
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a liquid crystal display, particularly to that comprising semiconductor integrated circuits (hereinafter referred to as "driver ICs") directly mounted on substrates for driving a display portion.
DESCRIPTION OF THE RELATED ART
A liquid crystal display is widely used in a liquid crystal TV, a video camera, a personal computer, a word processor, an electronic desk calculator, and other various information processing devices.
Particularly, a so-called COG (chip-on-glass) mounting method, i.e., a method of directly mounting the driver ICs for driving the display portion on substrates such as glass substrates is in increasing commercial use since the mounting portion is very compact in size and low in mounting cost in this method.
FIG. 3 is a plan view of a conventional liquid crystal display which employs the COG mounting method. As illustrated in the figure, the liquid crystal display is equipped with first and second substrates 1 and 2, on which driving electrodes 3 and 4 are formed, respectively.
A display portion 5 in which liquid crystal is encapsulated is accessed by way of the driving electrodes 3 and 4.
Driver ICs 6 and 7 are mounted on the first and second substrates 1 and 2 and, more particularly, are directly mounted (COG mounting) on the first and second substrates 1 and 2 in areas of IC mounting portions 8 and 9, respectively. The driving electrodes 3 and 4 are connected to output terminals 42 and output terminals 43 of the driver ICs 6 and 7, respectively.
Moreover, input electrodes 30 and input electrodes 31 are formed on the first and second substrates 1 and 2, respectively, and the input electrodes 30 and 31 are connected to the input terminals 40 and input terminals 41 of the driver ICs 6 and 7, respectively.
The input electrodes 30 and input 31 set forth above are connected to external wirings 34 and 35 in areas of outward connecting portions 32 and 33 respectively for supplying signals or voltages to the liquid crystal display from outside.
One aspect of such a conventional liquid crystal display is that the outward connecting portions 32 and 33 are disposed in areas in directions reverse to those of the display portion 5 viewed from the mounting portions 8 and 9 indicated by arrows 16 and 17, respectively, i.e., in areas in directions indicated by arrows 38 and 39 as illustrated in FIG. 3.
A liquid crystal display of high quality employs an active matrix system in which each pixel constituting the display portion is directly controlled by a switching element.
As representative switching elements, there are a TFT (Thin Film Transistor) which is a three-terminal switching element and an MIM (Metal-Insulator-Metal) which is a two-terminal switching element.
The TFT is an MIS (Metal-Insulator-Semiconductor) type field effect transistor, in which a gate insulating film serving as an insulator is particularly important. Recently an anodic oxidation film formed by subjecting tantalum (Ta) or Aluminum (Al) to anodic oxidation treatment has become mainstream as a gate insulating film which is pin-hole free and excellent in controllability.
The MIM which makes use of the nonlinear electrical conductivity of a (semi-) insulating thin film having a thickness of about 50 nm requires the controllability and uniformity of the (semi-) insulating thin film more than the TFT. The most of the (semi-) insulating thin films used in the MIM are also the anodic oxidation film formed by subjecting tantalum (Ta) to anodic oxidation treatment.
As described above, the fabrication of the active-matrix liquid crystal display of the TFT or MIM requires the anodic oxidation treatment, which further requires a common electrode for applying voltage.
In general, the fabrication of such a liquid crystal display employs a method comprising steps of forming a plurality of liquid crystal displays on a comparatively large substrate and dividing the same into individual liquid crystal displays after the same are almost completed, i.e., a so-called multiple-display layou
REFERENCES:
patent: 5189539 (1993-02-01), Suzuki
patent: 5200847 (1993-04-01), Mawatari et al.
Abraham Fetsum
Citizen Watch Co. Ltd.
Fahmy Wael
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