Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1998-09-30
2001-02-06
Hjerpe, Richard A. (Department: 2774)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S174000, C178S018010, C178S018030
Reexamination Certificate
active
06184872
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coordinate data input device of an electrostatic capacity type capable of detecting the position of a point on a screen touched mainly with a finger through the detection of a change in electrostatic capacity, and a method of fabricating such a coordinate data input device.
Recently, a coordinate data input device of an electrostatic capacity type generally referred to as tablet has been put to practical use. An operator is able to enter the x- and the y-coordinate of a point on the screen of the coordinate data input device by touching the point with a finger.
A conventional coordinate data input device has a printed circuit board, a sensing sheet using a rectangular dielectric film as a base film and placed on the printed wiring board, and a flexible wiring board electrically connecting the printed wiring board and the sensing sheet. The dielectric film of the sensing sheet is provided on its front surface with a plurality of parallel x-electrodes extended in parallel to the x-axis. Ends of the x-electrodes on the same side of the dielectric film serve as connecting ends, and a first connector is connected to the connecting ends of the x-electrodes. The dielectric film is provided on its back surface with a plurality of parallel y-electrodes extended in parallel to the y-axis. Ends of the y-electrodes on the same side of the dielectric film serve as connecting ends, and a second connector is connected to the connecting ends of the y-electrodes. The opposite ends of the flexible wiring board are connected to the connectors and the printed wiring boards to electrically connect the electrodes of the sensing sheet to drive circuits and control circuits formed on the printed wiring board.
When an operator's finger is put to an optional position on the sensing sheet, part of lines of electric force extending from the x-electrodes toward the y-electrodes is intercepted by the operator's finger to reduce lines of electric force reaching the y-electrodes, so that the electrostatic capacity changes, and the coordinates of the position touched with the operator's finger can be determined on the basis of an output current produced by the sensing sheet varying according to the variation of the electrostatic capacity.
As mentioned above, in the conventional coordinate data input device of an electrostatic capacity type, the x-electrodes and the y-electrodes formed on the sensing sheet are electrically connected through the connectors and the flexible wiring board to the printed wiring board. Therefore, the thickness of the coordinate data input device is dependent on the relatively great thickness of the connectors attached to the front and the back surface of the sensing sheet. Since the flexible wiring board is expanded toward one side of the sensing sheet and is extended to the printed wiring board, a relatively large space is required to layout the flexible wiring board, which increases the overall external dimensions of the coordinate data input device.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a miniaturized coordinate data input device having a relatively small thickness, and to provide a method of fabricating the coordinate data input device.
According to one aspect of the present invention, a coordinate data input device comprises: a sensing board having a film provided with a plurality of parallel first electrodes on its front surface, a plurality of parallel second electrodes extending perpendicularly to the first electrodes on its back surface, and through holes formed at one end of each of the first electrodes and at one end of each of the second electrodes; a printed wiring board mounted with the sensing board, and provided with a plurality of through holes at positions corresponding to the through holes formed at the ends of the first and the second electrodes, and a circuitry for controlling and driving the first and the second electrodes of the sensing board formed on its back surface; and conductive films formed on the side surfaces of the through holes of the sensing board and those of the printed wiring board so as to electrically connect the first and the second electrodes of the sensing board to the circuitry of the printed wiring board.
The coordinate data input device of the present invention does not need any connectors and any flexible wiring board, which are necessary in the conventional coordinate data input device to electrically connect the sensing board to the printed wiring board. The thickness of the coordinate data input device of the present invention is smaller by the thickness of the connectors than that of the conventional coordinate data input device, and does not need any space for laying the flexible wiring board.
According to another aspect of the present invention, a method of fabricating a coordinate data input device according to the present invention comprises steps of: mounting a sensing board having a film provided with a plurality of parallel first electrodes on its front surface, a plurality of parallel second electrodes extending perpendicularly to the first electrodes on its back surface, and through holes formed at one end of each of the first electrodes and at one end of each of the second electrodes on a printed wiring board provided with a plurality of through holes at positions corresponding to the through holes formed at the ends of the first and the second electrodes, and a circuitry formed on its back surface, for driving and controlling the first and the second electrodes of the sensing board; and forming conductive films of a conductive material by printing on the side surfaces of the through holes of the sensing board and those of the printed wiring board so as to electrically connect the first and the second electrodes of the sensing board to the circuitry of the printed wiring board while air is sucked through the through holes.
The conductive films can simply be formed by printing on the side surfaces of the through holes so as to be electrically connected to the electrodes of the sensing board and, therefore, the electrodes of the sensing board can easily connected electrically to the circuitry of the printed wiring board with satisfactory reliability.
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Hagiya Ryuichi
Matsufusa Hideto
Yamada Naoki
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Hjerpe Richard A.
Nguyen Kimnhung
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