Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1979-08-22
1982-03-16
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
250221, G06F 302, G06K 900
Patent
active
043202926
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to coordinate input apparatus utilized in various data processing systems, picture image information systems, and the like.
BACKGROUND OF THE INVENTION
Among prior art apparatus of the type described above, one may refer to, for example, an apparatus as disclosed in U.S. Pat. No. 3,868,681 wherein an electromagnetic or electrostatic coupling between an electrical conductor net extending over an input board and an input pen is detected to determine the coordinate position designated by the input pen on the input board, or an apparatus as disclosed in Bremner IEEE Transaction C, 1970, June, PP 546-548 wherein an input pen which radiates an ultrasonic wave which is received by microphones disposed about an input board so as to detect the delay of the wave received by the microphones from the position designated by the input pen, thus determining the coordinate position designated by the input pen. However, they are not yet satisfactory from the standpoint of construction and performance.
More particularly, in the former, high accuracy is required for the electrical conductor net on the input board and the peripheral circuit also requires high degree of skill. In the latter, since the propagating velocity of the ultrasonic wave varies with ambient temperature and humidity, it is necessary to compensate for the variation in the velocity. Furthermore, in order to detect a small delay of the received wave, it is necessary to use complicated peripheral circuits, thus making it difficult to decrease the cost of manufacturing and to attain high reliability. Especially, in the latter, it is necessary to constantly supply to the input pen a signal necessary for radiating the ultrasonic wave through an electric cord. Thus, it has been impossible to drive the input pen by a self-contained battery, for example, which dispenses with the cord (cordless) for connection between the input pen and the apparatus.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of this invention to provide an improved coordinate input apparatus having a high reliability which can not only obviate the disadvantages described above but also eliminate the cord.
Another object of this invention is to provide a coordinate input apparatus having simple construction, high reliability and high resolution.
Still another object of this invention is to provide a tapered structure fiber optic sheet which is used as a connector between the output end of a fiber optic sheet and a photo detector array for accurately connecting the output of the fiber optic sheet to the photo detector array.
A further object of this invention is to provide improved optical coupling means for coupling the output end of the tapered structure fiber optic sheet to the photo detector array.
Still further object of this invention is to provide an electronic circuit suitable for deriving out, as a binary signal train, the coordinate position of the input light pen by utilizing the output detected by the photo detector array.
According to one aspect of this invention, there is provided a coordinate input apparatus comprising an input board including two optical guide channel arrays superposed one upon the other with the optical guide channels of one array intersected at right angles with the optical guide channels of the other array, each array having a plurality of parallelly disposed optical guide channels, each channel containing optical scatterer; a light pen adapted to project a light beam upon the input board; photo detectors disposed to oppose one end surface of the respective optical guide channels for detecting scattered light of the projected light beam which propagates through the optical guide channels to convert the detected light into electrical signals; and an electronic circuit responsive to the electrical signals for producing a binary signal train which determines a coordinate position where the light beam is projected by the light pen.
According to another aspect of this invention, there is provided a coor
REFERENCES:
patent: 4113353 (1978-09-01), Matsushita
Katayama Yuzo
Kurokawa Takashi
Oikawa Shigeru
Takato Norio
Hostetter Darwin R.
Nelms David C.
Nippon Telegraph and Telephone Public Corporation
Pfund Charles E.
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