Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1999-04-13
2002-04-09
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S173000, C345S176000, C345S177000, C178S018010, C178S018030, C178S018040, C178S018050, C178S019010, C178S019020
Reexamination Certificate
active
06369806
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a coordinate-detecting device used as input means for personal computers and word processors and a coordinate input pad thereof, and particularly relates to a coordinate-detecting device of a voltage-detecting type which generates coordinate data based on voltage values detected when there is a touch on a coordinate input panel having an x-coordinate and a Y-coordinate, and the coordinate input pad thereof.
2. Description of the Related Art
Recently, information-processing devices such as personal computers and word processors are provided with improved operation systems and other improved characteristics so as to be easily manipulated by the users. Also, for such information processing devices, coordinate-detecting devices are commonly used as pointing devices rather than mouses. This is because the coordinate-detecting devices are simple to use.
The coordinate-detecting device may be of an electromagnetic induction type, a capacitive coupling type or a resistive film type. Among those types of devices, the resistive film type is often used because of its various advantages such as a simple structure, a reduced cost and a reduced thickness.
In the following, a coordinate-detecting device of the prior art will be described with reference to FIG.
3
.
FIG. 3
shows a coordinate-detecting device of the prior art including a coordinate input pad
201
and a detecting part
202
. The coordinate input pad
201
serves as an operating surface via which a user can input information into an information-processing device such as a personal computer or a word processor. The detecting part
202
applies a voltage to the coordinate input pad
201
and then detects a position of a contact point on the coordinate input pad
201
. Thus, the coordinate-detecting device outputs switching data and coordinate data when there is a touch on the coordinate input pad
201
.
FIG. 1A
is a perspective diagram showing a coordinate input pad used in the coordinate-detecting device of the related art. The coordinate input pad has two resistive films
203
,
204
opposing each other with a plurality of dot spacers
216
placed between the resistivefilms
203
,
204
. The resistive films
203
,
204
are provided with pairs of electrodes
205
,
206
and
207
,
208
, respectively, which are formed along the edges and located at opposite sides of central input regions
215
.
The resistivefilms
203
,
204
are located such that the pair of electrodes
205
,
206
and the pair of electrodes
207
,
208
formed on the respective resistive films are perpendicular to each other. For example, as shown in
FIG. 3
, the electrode
205
parallel to the x-axis may be used for detecting a voltage corresponding to a y-coordinate. Also, the electrode
207
parallel to the y-axis may be used for detecting a voltage corresponding to an x-coordinate. It is to be noted that the plurality of dot spacers
216
made of an insulating material is provided in order to prevent any short-circuit between the two resistive films
203
,
204
during a normal state.
The detecting part
202
includes a pair of transistors
209
,
210
for applying a voltage across the pair of electrodes
205
,
206
on the resistive film
203
and a pair of transistors
211
,
212
for applying a voltage across the pair of electrodes
207
,
208
on the resistive film
204
. The detecting part
202
applies voltages to the resistive films
203
,
204
by alternately turning on the pair of transistors
209
,
210
and the pair of transistors
211
,
212
.
Further, the detecting part
202
includes a control part
213
for controlling the transistors
209
,
210
,
211
,
212
and a voltage-detecting part
214
for detecting a voltage corresponding to a pressed-down point on the coordinate input pad
201
. Thus, the detecting part
202
detects a coordinate of the pressed-down point on the coordinate input pad
201
.
With the coordinate-detecting device of the above structure, when a point on the coordinate input pad
201
is pressed down, the two resistive films
203
,
204
will be in contact at the pressed-down point. If a voltage has been applied across the electrodes
205
,
206
, the voltage will be divided at the contact point and a voltage representing the y-coordinate will be output via the electrode
207
. Also, if a voltage has been applied across the electrodes
207
,
208
, the voltage will be divided at the contact point and a voltage representing the x-coordinate will be output via the electrode
205
.
After detecting the voltages representing the x-coordinate and the y-coordinate, the voltage-detecting part
214
sends the voltages to the control part
213
. At the control part
213
, coordinate data or switching data of the contact point will be generated based on the voltages. Finally, the generated data is output from the control part
213
.
The coordinate-detecting device of the prior art is advantageous in that, when the resistive films
203
,
204
are flexed due to a factor such as a thermal stress, the opposing resistive films
203
,
204
are prevented from coming into contact by means of the dot spacers
216
provided at appropriate intervals. Therefore, the resistive films
203
,
204
will be in contact only when there is a touch on the coordinate input pad
201
.
FIGS. 2A and 2B
are cross-sectional diagrams showing problematic aspects of the coordinate input pad of the related art. As shown in
FIG. 2A
, the coordinate-detecting device of the prior art is provided with dot spacers made of an insulating material between opposing resistive films. Therefore, when there is a touch on the coordinate input pad at a point directly or substantially above a particular dot spacer, the resistive films will be in contact at locations surrounding the dot spacer (see FIG.
2
B). Thus, detected data may be unstable.
In order to avoid such a problem and thus improve operability, it is necessary to increase intervals between the dot spacers while reducing the size and height of the dot spacers.
However, when the configuration of the dot spacers is altered as described above, there is a greater possibility that the resistive films are short-circuited since a gap between the resistive films may be narrowed due to a distortion or bowing of the resistive films.
Also, with the coordinate-detecting device of the prior art, the resistive films are joined by means of an adhesive layer of an order of several tens of micrometers. With this structure, there may be joint gaps at the joining part because of a level difference due to patterns provided at the joining part or because of the roughness of the surface of a resist layer. With such joint gaps, when the coordinate input pad is pressed over a comparatively large area, some of the air existing between the resistive films will escape via the joint gaps. Once the air has escaped, not enough air will immediately flow back to the space between the resistive films even if the pressure on the coordinate input pad is released. Therefore, the coordinate-detecting device of the prior art has a disadvantage that the resistive films may remain in contact for a considerable time.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a coordinate-detecting device and a coordinate input pad used in the coordinate-detecting device which can solve the above problems.
It is another and more specific object of the present invention to provide a coordinate-detecting device which can detect accurate coordinate data at any point on an operating surface of a coordinate input pad.
In order to achieve the above objects according to the present invention, a coordinate-detecting device of a voltage-detecting type includes a coordinate input pad having an upper sheet and a lower sheet opposing each other at a predetermined gap by a repulsive force between magnetic poles with the same polarity.
The coordinate-detecting device described above does not include dot spacers. Therefore, the
Endo Michiko
Nishino Takeshi
Ootani Yasuo
Fujitsu Takamisawa Component Ltd.
Hjerpe Richard
Lesperance Jean
Staas & Halsey , LLP
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