Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Patent
1996-09-13
1998-10-13
Sikes, William L.
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
151152, G02F 11345
Patent
active
058220305
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the structure of a liquid crystal display device and to the structure for mounting the liquid crystal display device in a main unit or various devices, and it also relates to an electronic device equipped with the liquid crystal display device.
2. Background of the Invention
Generally, liquid crystal display devices comprise a liquid crystal cell wherein a liquid crystal layer is sandwiched between two glass substrates, a drive circuit for driving the liquid crystal, a control circuit for controlling liquid crystal display, and a power supply circuit for supplying the power and input signals. Currently, connection of the liquid crystal cell and the drive circuit is performed most commonly by a TAB system that uses TAB technology to batch connect the tape carrier package (TCP) whereon the semiconductor chip for liquid crystal drive is mounted.
A typical example of a prior art liquid crystal display wherein the TAB system is utilized is shown in FIG. 20. The output terminals of TCP 4 whereon semiconductor chip 3 for liquid crystal drive is mounted are connected by an anisotropic conductive film, for example, to the input terminals disposed along one side 2 of liquid crystal cell 1. Circuit board 6 whereon electronic components 5; e.g., chip capacitors, resistors and controllers, other than said semiconductor chip for liquid crystal drive are mounted is connected to the input terminals of TCP 4 by soldering. Input cable 7 made from a flexible film wiring sheet, for example, is connected to circuit board 6, whereby said liquid crystal display device is connected to the main electronic device unit and power and signals are input.
However, since liquid crystal display devices manufactured by the prior art TAB method require at least TCP 3, circuit board 6 and input cable 7 in addition to liquid crystal cell 1 as component parts, there are many parts, which increases the number of connections for connecting them, thus increasing the number of production processes and labor, and this in turn can increase production costs and lower production yield. Further, since input and output wiring is formed on each of said TCP, circuit board and input cable, the mounting area is greatly increased, thus increasing the size of the so-called frame member and resulting in a liquid crystal display device that is large overall. Also, a larger area must be provided in the electronic device in order to mount the liquid crystal display device, thus greatly restricting product design and making it larger than necessary. Moreover, compared to the overall size of the device, the area of the display screen is relatively small and sufficient information cannot be displayed. This is particularly a major obstacle in realizing greater compactness and functionality in developing portable electronic products such as cellular telephones.
Other methods for connecting liquid crystal cells and drive circuits are also known such as the rubber connection method that uses conductive rubber, connection methods that use a heat seal or flexible film wiring sheet, and the chip on glass (COG) method that connects the semiconductor chip for liquid crystal drive directly to the glass substrate surface of the liquid crystal cell. The rubber connection method, though it does make assemble easy, uses conductive rubber to connect the output of the drive circuit to the input of the liquid crystal cell, and therefore it cannot readily accommodate tight pitches, and since the drive circuit is disposed behind the liquid crystal cell, it is difficult to attach a backlight, thus increasing the thickness of the entire device.
The COG method that is now being used mounts the semiconductor chip for liquid crystal drive directly by patterning input/output wiring and electrodes from transparent indium tin oxide (ITO) on the peripheral surface of the glass substrate from which the liquid crystal cell is configured. Therefore, though the number of parts and connections is small, the wiring must
REFERENCES:
patent: 3863436 (1975-02-01), Schwarzchild et al.
patent: 4640581 (1987-02-01), Nakanowatari et al.
patent: 4690510 (1987-09-01), Takamatsu et al.
Ngo Julie
Seiko Epson Corporation
Sikes William L.
Watson Mark P.
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