Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1998-09-17
2001-03-27
Saras, Steven J. (Department: 2775)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C178S018050
Reexamination Certificate
active
06208332
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a resistance film tablet system and a method of controlling the resistance film tablet system, and particularly to a resistance film tablet system comprising two resistance films superposed on each other and spaced by a predetermined distance therebetween and a method of controlling the resistance film tablet system.
Conventionally, a resistance film tablet system is composed of two resistance films which have resistance values equal to each other and each of which has parallel electrodes at both ends thereof. The two resistance films are then faced to each other to have a space of a predetermined distance therebetween with their directions shifted by 90 degrees from each other. With this structure, when the two resistance films are pressed from outside by a tapered tip like a pen tip and so on, the two resistance films are arranged to come into contact with each other at the pressed point.
Regarding the four parallel electrodes of such a tablet, it is known that a physical position of the contact point of the two resistance films can be measured by using the following scanning modes.
As will later be described more in detail, the conventional resistance film tablet system is subjected to the following basic scanning modes. Namely, the modes consist of “contact detection” to check whether or not the two resistance films are in contact with each other, “X-detection” to check a position in the direction of X, and “Y-detection” to check a position in the direction of Y. And, these detecting modes or operations are sequentially repeated until the two resistance films are judged as being not in contact with each other in the “contact detection” mode.
In addition, it is a recent trend that a faster sampling is required from demands for a character recognition with a normal writing speed, etc.
However, when users measure contact point voltages by the X-detection and the Y-detection modes in the conventional resistance film tablet system, they have to wait a certain period of time due to a change of a mode. Thereby, sampling is substantially restricted. In other words, when contact point voltages are measured by the X-detection and the Y-detection, tablet scanning of the conventional resistance film tablet system has a drawback that users have to wait a certain period of time after a mode is set.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a resistance film tablet system which is capable of carrying out a sampling faster than the conventional resistance film tablet system and a control method therefor by shortening the aforesaid waiting time.
Other objects of the present invention will become clear as the description proceeds.
On describing the gist of the present invention, it is readily understood that a resistance film tablet system is composed of two resistance films superposed on each other and spaced by a predetermined distance therebetween.
According to an aspect of the present invention, there is provided a resistance film tablet system which includes a pair of resistance films superposed on each other and spaced by a predetermined distance therebetween, comprising: contact detection means for detecting that a pair of resistance films are in contact with each other at a contact point; charging means for charging a capacitance between a pair of resistance films in response to the detection; and detection means for detecting a position in a first direction and a position in a second direction orthogonal to the first direction regarding the contact point of a pair of resistance films after the charging.
A pair of resistance films may be both rectangular resistance films with uniform resistance value and may be constituted so as to be superposed on each other with parallel electrodes provided on the opposing sides of the rectangles mutually shifted by 90 degrees.
A pair of resistance films may be both rectangular resistance films with uniform resistance value and the first direction may be along one side of the rectangle and the second direction may be along the other side of the rectangle. The charging means may comprise a memory for storing position data regarding the position in the first direction and the position in the second direction detected by the detection means, and voltage impression means for impressing a voltage corresponding to the position data stored in the memory across a pair of resistance films.
The position data may be stored in the memory after converting them into digital data.
The charging means may charge the capacitance in accordance with a signal after the data read from the memory has been transformed into analog data.
According to another aspect of the present invention, there is also provided a method of controlling a resistance film tablet system composed of a pair of resistance films superposed on each other and spaced by a predetermined distance therebetween, comprising the steps of; detecting a contact state between a pair of resistance films; charging a capacitance between a pair of resistance films in response to the detection of the contact state; and detecting a position in a first direction and a position in a second direction orthogonal to the first direction regarding the contact point of a pair of resistance films after the charging.
A pair of resistance films may be both rectangular resistance films with uniform resistance value and may be constituted so as to be superposed on each other with parallel electrodes provided on the opposing sides of the rectangles mutually shifted by 90 degrees.
A pair of resistance films may be both rectangular resistance films with uniform resistance value and the first direction may be along one side of the rectangle and the second direction may be along the other side of the rectangle. The charging step may comprise a step of impressing a voltage corresponding to the position data stored in the memory storing the position data regarding the position in the first direction and the position in the second direction detected by the position detection step between a pair of resistance films.
According to yet another aspect of the present invention, there is further provided a recording medium for storing a computer program to achieve a method of controlling a resistance film tablet system composed of a pair of resistance films superposed on each other and spaced by a predetermined distance therebetween, wherein the computer program makes a computer detect a contact state between a pair of resistance films, and charge a capacitance between a pair of resistance films in response to the detection of a contact state, and detect a position in a first direction and a position in a second direction orthogonal to the first direction regarding the contact point of a pair of resistance films after the charging.
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Bell Paul A.
NEC Corporation
Saras Steven J.
LandOfFree
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