Coordinate input device

A coordinate input device of a low manufacturing cost is to be provided using a position detector and an arithmetic unit of simple configurations. The coordinate input device comprises a contact type coordinate detecting section provided with a first substrate having a plurality of X electrodes arranged in parallel in X-axis direction and a second substrate having a plurality of X electrodes arranged in parallel in X-axis direction, the first and second substrates being disposed in proximity to each other, and some of the X and Y electrodes being rendered conductive by a pushing operating of an operating means, a scanning section which provides scanning signals successively to the X electrodes, a position detecting section which outputs detection signals from the Y electrodes during scanning of the X electrodes, and an arithmetic section which calculates X and Y coordinate positions on the basis of both scanning signals and detection signals. The X and Y coordinate positions calculated by the arithmetic section correspond to central coordinate positions operated by the operating means and detected from the differences between conducted maximum X, Y coordinate positions and minimum X, Y coordinate positions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a coordinate input device and more 
particularly to a coordinate input device wherein a coordinate position 
detected by a contact type coordinate detecting section adapted to be 
pushed by an operating means such as a finger can be calculated easily by 
an arithmetic operation performed by a coordinate position calculating 
circuit. 
2. Description of the Related Art 
Heretofore, in a signal processor such as a personal computer there has 
been used a coordinate input device provided with a capacitance detection 
type coordinate detecting section which is operated by an operating means 
such as a finger. 
FIG. 3 is a block diagram showing an example of a schematic configuration 
of such a known coordinate input device. 
As shown in FIG. 3, the coordinate input device illustrated therein 
comprises a capacitance detection type coordinate detecting section 31 
having a plurality(n number) of X electrodes 3.sub.21 to 32.sub.n arranged 
in parallel in X-axis direction and a plurality (m number) of Y electrodes 
3.sub.31 to 33.sub.m arranged in parallel in Y-axis direction, an 
operating means 34, for example a finger of an operator, for operating a 
desired coordinate position on an operating surface of the coordinate 
detecting section 31, a drive signal generating section 35 for providing 
drive signals to the X electrodes 32.sub.1 .about.32.sub.n, a position 
detecting section 36 which outputs as an electric current a change in 
capacitance of Y electrodes 33.sub.1 to 33.sub.m which is caused upon 
operation by the operating means 34, an arithmetic section 37 which, on 
the basis of the drive signals and changes in electric current, calculates 
the coordinate position on the operating surface of the coordinate 
detecting section 31 having been operated by the operating means 34 and 
then outputs coordinate position data, a data output section 38 which 
converts the coordinate position data into a signal suitable for 
transmission, and a control section 39 for controlling the operation of 
the entire coordinate input device. 
The known coordinate input device constructed as above generally operates 
as follows. 
In the capacitance detection type coordinate detecting section 31, the X 
electrodes 32.sub.1 to 32.sub.n are scanned successively with drive 
signals outputted from the drive signal generating section 35, and 
electric currents proportional to capacitance values in Y electrodes 
33.sub.1 to 33.sub.m are detected successively by the position detecting 
section 36. In this state, when the operator operates a desired position 
on the operating surface of the coordinate detection section 31 with his 
or her finger 34, there occurs changes in the value of capacitance of the 
operated Y electrodes 33.sub.1, and the changes in capacitance are 
detected as changes in electric current by the position detecting section 
36, which in turn outputs electric current values. In accordance with the 
control signal fed from the control section 39 and the electric current 
values provided from the position detecting section 36, the arithmetic 
section 37 calculates, as coordinate position data, both X and Y 
coordinate positions where the change in capacitance value is the largest. 
The data output section 38 converts the coordinate position data obtained 
in the arithmetic section 37 into a transmission signal suitable for 
transmission, which signal is then transmitted to a signal processing 
means(not shown) such as a personal computer through a connection line or 
by wireless means such as infrared light or radio. 
Since the above known coordinate input device detects a delicate change in 
capacitance between X electrode (32.sub.1 .about.32.sub.n) and Y electrode 
(33.sub.1 .about.33.sub.m) upon contact therewith of the operating means 
34 and then calculates coordinate position data, it requires an amplifier 
circuit for amplifying the change in capacitance, a processing circuit for 
processing against disturbance noise, and a complicated arithmetic 
processing circuit. Thus, there arises the problem that the manufacturing 
cost of the coordinate input device becomes high. 
SUMMARY OF THE INVENTION 
The present invention solves the above-mentioned problem and it is an 
object of the invention to provide a coordinate input device of a low 
manufacturing cost wherein coordinate position data are calculated by a 
simple processing circuit without using capacitance detecting means or the 
like. 
In order to achieve the above-mentioned object, the coordinate input device 
of the present invention comprises a contact type coordinate detecting 
section which causes X and Y electrodes to come into contact with each 
other, a scanning section for scanning X electrodes, a position detecting 
section for detecting detection signals provided from Y electrodes, and an 
arithmetic section for calculating X and Y coordinate positions, the 
arithmetic section being provided with means for detecting central 
coordinate positions operated by the operating means on the basis of 
differences between maximum coordinate positions of conducted X, Y 
electrodes and minimum coordinate positions thereof. 
According to the above-mentioned means, X and Y coordinate positions 
detected upon pushing the operating surface of the contact type coordinate 
detecting section correspond respectively to a central X coordinate 
position based on the difference between conducted maximum and minimum 
coordinate positions and a central Y coordinate position based on the 
difference between conducted maximum and minimum Y coordinate positions, 
and a plurality of conducted positions of X and Y electrodes are detected 
and the respective central coordinate positions are used as position data. 
Therefore, a position data processing circuit of a simple structure 
suffices and hence it is possible to provide a coordinate input device of 
a low manufacturing cost. 
The coordinate input device according to the present invention comprises a 
contact type coordinate detecting section provided with a first substrate 
having a plurality of X electrodes arranged in parallel in X-axis 
direction and a second substrate having a plurality of Y electrodes 
arranged in parallel in Y-axis direction, the first and second substrates 
being disposed in proximity to each other, plural such X and Y electrodes 
being rendered conductive by a pushing operation of an operating means, a 
scanning section which provides scanning signals successively to the X 
electrodes, a position detecting section which outputs the scanning 
signals as detection signals of Y electrodes during scanning of X 
electrodes, and an arithmetic section for calculating X and Y coordinate 
positions on the basis of the scanning signals and the detection signals. 
The X and Y coordinate positions calculated by the arithmetic section 
correspond to central coordinate positions operated by the operating means 
and detected from the differences between conducted maximum X,Y coordinate 
positions and minimum X,Y coordinate positions. 
For example, the operating means is a finger of an operator. 
Preferably, the arithmetic section stores the calculated central coordinate 
positions successively in an internal memory and, on the basis of a 
shifting state of the central coordinate positions thus stored, detects 
movement data indicative of a moving speed and/or a moving direction of 
the contact type coordinate detecting section operated by the operating 
means. 
Preferably, when there is no change in the detected movement data, the 
arithmetic section detects switch data based on a tapping operation of the 
operating means. 
According to the above embodiments of the present invention, X and Y 
coordinate positions on the operating surface of the contact type 
coordinate detecting section detected upon pushing operation by the 
operating means correspond respectively to a central X coordinate position 
calculated by the arithmetic section on the basis of the difference 
between conducted maximum and minimum X coordinate positions and a central 
Y coordinate position calculated by the arithmetic section on the basis of 
the difference between conducted maximum and minimum Y coordinate 
positions. Therefore, as compared with a capacitance type coordinate input 
device, both a position detecting circuit and an arithmetic processing 
circuit are simplified in structure and it is possible to provide a 
coordinate input device of a low manufacturing cost.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
An embodiment of the present invention will be described hereinafter with 
reference to the accompanying drawings. 
FIG. 1 is a block diagram showing a coordinate input device according to an 
embodiment of the present invention, and FIG. 2 is a perspective view 
showing an example of construction of a contact type coordinate detecting 
section used in the coordinate input device illustrated in FIG. 1. 
As shown in FIG. 1, the coordinate input device of this embodiment 
comprises a contact type coordinate detecting section 1 having a plurality 
(twelve in this embodiment) of X electrodes 2.sub.1 to 2.sub.12 arranged 
in parallel in X-axis direction and a plurality (sixteen in this 
embodiment) of Y electrodes 3.sub.1 to 3.sub.16 arranged in parallel in 
Y-axis direction; an operating means 4, for example a finger of an 
operator, which performs operation for a desired coordinate position on an 
operating surface 1A of the contact type coordinate detecting section 1; a 
scanning section 5 which provides scanning signals successively to the 
twelve X electrodes 2.sub.1 to 2.sub.12 ; a position detecting section 6 
for detecting one or more Y electrodes operated by the operating means 4 
out of the sixteen Y electrodes and outputting detection signals; an 
arithmetic section 7 which, on the basis of the provided scanning signals 
and detection signals, calculates X and Y coordinate positions on the 
operating surface 1A of the contact type coordinate detecting section 1 
operated by the operating means 4 and then outputs coordinate position 
data; an internal memory 7M incorporated in the arithmetic section 7 to 
store the coordinate position data temporarily; a switch data generating 
section 8 for generating switch data; a data output section 9 which 
converts the coordinate position data and the switch data into signals 
suitable for transmission to a personal computer (signal processor) 20; 
and a control section 10 for generally controlling the operation of each 
component of the coordinate input device. 
As shown in FIG. 2, the contact type coordinate detecting section 1 
comprises a flexible first substrate 11 and a flexible second substrate 
12, which are opposed to each other at a slight distance through spacers 
13, twelve X electrodes 2.sub.1 to 2.sub.12 formed in parallel on the 
first substrate 11, and sixteen Y electrodes 3.sub.1 to 3.sub.16 formed in 
parallel on the second substrate 12. 
The coordinate input device of this embodiment constructed as above 
operates in the following manner. 
In the contact type coordinate detecting section 1, the twelve X electrodes 
2.sub.1 to 2.sub.12 are successively scanned continually with scanning 
signals outputted from the scanning section 5, and the sixteen Y 
electrodes 3.sub.1 to 3.sub.16 are connected to the position detection 
section 6. In this state, if the operator pushes a desired position on the 
operating surface 1A of the coordinate detecting section 1, using his or 
her finger (operating means), the slight distance between the first and 
second substrates 11, 12 changes partially at the position pushed with the 
finger 4, and plural X electrodes and plural Y electrodes come into 
contact and conduction with each other on the basis of such partial 
change. This conduction causes scanning signals to flow through the Y 
electrodes, which signals are detected by the position detecting section 6 
and outputted as detection signals from the same section. Then, the 
arithmetic section 7 receives from the control section 10 signals 
indicating the state of supply of scanning signals fed to the twelve X 
electrodes 2.sub.1 to 2.sub.12, and at the same time receives the 
detection signals provided from the position detecting section 6. On the 
basis of these signals, the arithmetic section 7 determines the largest X 
coordinate position Xmax and the smallest X coordinate position Xmin out 
of the X coordinate positions conducted and likewise determines the 
largest Y coordinate positions Ymax and the smallest Y coordinate 
positions Ymin out of the Y coordinate positions conducted. Thereafter, 
the arithmetic section 7 calculates {(Xmax-Xmin)/2}+Xmin to obtain a 
central X coordinate position and also calculates {(Ymax-Ymin )/2}+Y min 
to obtain a central Y coordinate position, then outputs the central X and 
Y coordinate positions thus obtained as position detection data. The 
signal transmitting section 9 converts the coordinate position data 
outputted from the arithmetic section 7 into transmission signals suitable 
for transmission to the personal computer 20, which are infrared 
transmission signals in the illustrated example, and transmits the 
thus-converted infrared transmission signals to the personal computer 20 
by wireless. 
Further, the arithmetic section attains the following functions in 
accordance with the position coordinate data thus calculated. 
The first function is to store new position coordinate data temporarily in 
the internal memory 7M at every calculation of position coordinate data. 
The second function is to compare new position detection data with several 
immediately preceding position detection data already stored in the 
internal memory 7M and, when it is judged that there has been a shift in 
operating position based on operation with the finger 4 between such 
position detection data, to form movement data representing a moving 
direction and a moving speed of the positional shift and to output the a 
movement data together with new position detection data. 
The third function is to compare new position detection data with several 
immediately preceding position detection data already stored in the 
internal memory 7M and, when there is no change between such position 
detection data, to drive the switch data generating section 8 on the 
assumption that a tapping operation has been performed, to allow switch 
data to be generated from the switch data generating section 8, and to 
output the switch data instead of new position detection data. 
Thus, according to the coordinate input device of this embodiment, detected 
X and Y coordinate positions on the operating surface 1A of the contact 
type coordinate detecting section 1 correspond respectively to a central X 
coordinate position calculated by the arithmetic section 7 on the basis of 
the difference between conducted maximum X coordinate position Xmax and 
minimum X coordinate position Xmin and a central Y coordinate position 
also calculated by the arithmetic section on the basis of the difference 
between conducted maximum Y coordinate position Ymax and minimum X 
coordinate position Ymin. In this way coordinate position data are 
calculated by only the detecting section for the detection of scanning 
signals based on conduction and the arithmetic section which calculates 
the center between maximum and minimum values. Therefore, the processing 
circuit used can be simplified in structure. 
Although in the above embodiment the number of X electrodes X.sub.1 to 
X.sub.12 and that of Y electrodes Y.sub.0 to Y.sub.16, as constituents of 
the contact type coordinate detecting section 1, are twelve and sixteen, 
respectively, no limitation is placed thereon. The X and Y electrodes are 
not always required to be arranged perpendicularly to each other. 
Although in the above embodiment the operating means 4 for operating the 
operating surface 1A of the contact type coordinate detecting section 1 is 
a finger of the operator, this constitutes no limitation. For example, it 
may be a pen-shaped operating means. 
Further, although in the above embodiment the signal processor supplied 
with transmission signals from the coordinate input device is the personal 
computer 20 and the transmission signals are transmitted as infrared 
signals by wireless, this constitutes no limitation. The signal processor 
to which transmission signals are to be transmitted may be any other 
signal processor than the personal computer, and the transmission signals 
may be in any other form than infrared signals. 
According to the coordinate input device of the present invention, as set 
forth above, X and Y coordinate positions on the operating surface of the 
contact type coordinate detecting section detected upon pushing of the 
operating surface of the operating means corresponds respectively to a 
central X coordinate position calculated by the arithmetic section from 
the difference between conducted maximum and minimum X coordinate 
positions and a central Y coordinate position calculated by the arithmetic 
section from the difference between conducted maximum and minimum Y 
coordinate positions. Therefore, it suffices to use only a position 
detecting section of a simple structure for detection of scanning signals 
and an arithmetic section also of a simple structure for the calculation 
of central coordinates based on the difference between maximum and minimum 
coordinate positions. This is effective in reducing the manufacturing 
cost.