JPS6037492B2 - coordinate input device - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides an electromagnetic induction type coordinate system that is effective for inputting information such as handwritten characters and figures into electronic devices such as computers using an input pen. This relates to input devices.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, in the field of information equipment centered on computers, there has been an increasing demand for inexpensive coordinate input devices that can input handwritten characters and graphic information.

Electromagnetic induction type coordinate input devices have been known as such coordinate input devices, but in order to increase resolution, this device has many thin conductive wires densely arranged on the input board. However, it has the drawbacks that a huge number of lead wires are required and that it is difficult to arrange the conductor wires with high precision. In addition, in order to solve the above problems,
There is a coordinate input device that improves the resolution by using a coiled conductor on the input board and reduces the number of lead wires, but the problem is that the control circuit becomes complicated and expensive. there were.

OBJECTS OF THE INVENTION An object of the present invention is to provide an inexpensive coordinate input device that significantly reduces the number of conductors disposed on an input board, has high resolution, and does not require a complicated control circuit.

Structure of the Invention The coordinate input device of the present invention has a plurality of conductors arranged in a matrix at predetermined intervals in the X direction and the Y direction, and among the conductors in the X or Y direction,
an input board configured to sequentially select two conductors and supply current from the outside; a detection coil for coordinate input movably positioned on the surface of the input board; and the two selected conductors. detecting means for independently detecting the yield voltage induced in the detection coil by the current flowing through the conductors, and detecting the value of the current flowing through one of the two selected conductors and the other conductor. The value of the current flowing through the two conductors is relatively changed so that the sum of the flowing current values is constant, and the current is generated by each conductor in the detection coil placed between the two conductors. The position of the detection coil is determined by the current value of one conductor when the ratio of the values of the induced voltages induced by the magnetic field reaches a predetermined value, and the detection coil is connected to the detection coil by each conductor. The detection coil is configured to determine whether or not the detection coil exists between the two conductors by comparing the values of two induced voltages induced by the generated magnetic field with a predetermined threshold value. This makes it possible to significantly reduce the number of conductors arranged on the input surface, and interpolate between the conductors with a simple control circuit, making it possible to realize a high-resolution coordinate input device at low cost. .

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be specifically described based on the drawings.

FIGS. 1A and 1B are a schematic diagram showing the position detection principle of the coordinate input device of the present invention and a graph showing the magnetic field strength distribution. In FIG. 1A, 1 and 1 are conductors arranged in parallel, and 2 is a detection coil placed on the same plane as the conductor 1, which is provided, for example, at the tip of an input pen. Figure 1A
1 on one conductor and 1 on the other conductor as shown in
When a current of 2 is applied, the magnetic field generated between both conductors is 1
If the magnetic field due to , is day 2, and the magnetic field due to day 2 is day 2, then
Day, = step.・・・． ...'1} ratio = river
...state (where d is the distance between both conductors).

This can be illustrated as shown in the magnetic field strength distribution graph in FIG. 1B. Next, when the detection coil 2 is placed at the position x=xp as shown in Fig. 1, the voltage induced in the detection coil 2 is
The induced voltage due to day is V, and the induced voltage due to day 2 is V2.
Then, V. =k●day. :2nd voice...'31
V2=k●ratio=2　to Xp) ‐‐‐‐‐‐[4'
(However, k' is a constant).

Therefore, the position P of the detection coil 2 can be determined by both equations '3} and '41.
When p is determined, it is expressed as the formula (■). 11Xp=d
-I don't understand. ---1-------…----….・・・
・V・Juou LV2 12 Here, if poison=・, 1・112=et al. (10 is constant), the position xp of the detection coil 2 is the scream.・．． ...'6).

That is, 1 when the ratio of the values of the induced voltages V, V2 generated in the detection coil 2 by the currents 1, 12 becomes 1.
, the position xp of the detection coil 2 can be determined.

Also, from equations '3}, '4}, and {6), the induced voltage V,,
The value Vo of V,,V2 when the ratio of the values of V2 is 1 is V
.

= Crocodile...Represented as state.

Next, when the detection coil 2 is placed at the position xp' shown in FIG. 2, the magnitude of the yield voltage induced in the detection coil 2, V
,,V2 is '3},■From the formula, v,=ticket
i8'V2 = 2 汀 climb ≦ bird p') - ‐‐‐‐‐‐
It is expressed as '91.

As is clear from FIG. 2, xp' and d, and the conductor currents 1, 12 are 1, SL, 12 SI due to the conditions. Therefore, the following equation can be obtained from '7} and equation (2). V.

ZV, ... [1■ Also, when the position xp'' of the detection coil 2 is placed at the position x〆:xp', the following equation is similarly obtained from the {7} side equation.V .

ZV2 (11) That is, when the detection coil does not exist between two conductors through which current flows, at least one of the working equation or equation (11) holds true. Therefore, by comparing the magnitudes of the two induced voltages induced in the detection coil 2 with a predetermined function value,
It is possible to determine whether the detection coil 2 is present between two conductors through which current is flowing. FIG. 3 is a block diagram of a coordinate input device according to an embodiment of the present invention, in which 1 is a conductor arranged in a matrix on an input board 3, and 2 is a detection coil attached to the tip of an input pen.

6 is maintained so that the sum of currents 1, , 12 is a constant value, etc.
and a current scan circuit that changes the values of 1 and 12 from the binary code 'from the counter 8a, 5 is a current 1,
and 12 in the X direction or the Y direction, and 4a and 4b are multiplexers for distributing currents 1 and 12 in binary code from the counter 8b to the conductor 1.

Reference numeral 9 denotes a latch circuit for temporary storage, which holds and outputs the coordinate data from the counters 8a and 8b in response to a control signal from the AND circuit 14.

Reference numeral 7 denotes a clock pulse generation circuit for driving the counter 8a, the current scan circuit 6, and the modulation circuit 10.

10 is a modulation circuit for obtaining a high frequency current equal to that of Kasumi, , 12.

11a and 11b are two induced voltages V. induced in the detection coil 2. , V2, respectively, and 12 compares the two voltages V and V2 detected by the detection circuits 11a and 11b, and outputs a control signal when the ratio becomes 1. V, /V2 detection circuit,
Reference numerals 13a and 13b are voltage comparison circuits that compare the voltages V, V2 and a predetermined function voltage E to determine which conductor the detection coil 2 is located between.
The AND circuit 14 performs a logical product with the control signal of the detection circuit 12 to control the latch circuit 9.

The operation of the coordinate input device of this embodiment configured as described above will be explained below. First, the output code of the counter 8b is input to the multiplexers 4a and 4b to select two conductors through which current will flow. Next, the output code of the counter 8a is changed to change the values of the currents 1, 12.
After that, change the output code of the counter 8b and write the following 2
Select the book conductor and repeat the same operation. By the above operation, changing currents are sequentially applied to the conductors on the input surface 3. On the other hand, in the detection coil 2, a yield voltage is generated from each conductor, but when current flows through the conductors on both sides of the detection coil 2, the output voltage of the V, V2 detection circuits 11a and 11b is determined based on the above principle. Therefore, the voltage becomes larger than the predetermined value E, and the logic state of the outputs of the voltage comparison circuits 13a and 13b becomes 1. In the above state, when the values of detection voltages V, V2 become equal due to changes in currents 1, 12,
The logic state of the output of the V, /V2 detection circuit 12 also becomes 1,
At this time, the output codes of counters 8a and 8b are stored in latch circuit 9. Since the output codes of the counters 8a and 8b correspond to the coordinate values of the input board 3, the position of the detection coil 2 can be known from the output code of the latch circuit 9. As described above, according to this embodiment, by comparing the induced voltages V, , V2 induced in the detection coil 2 and a predetermined threshold voltage, it can be determined between which conductors the detection coil is present. Judging. Note that in this example, in order to determine whether a detection coil exists between conductors through which current flows, the detected induced voltage is directly compared with a predetermined voltage, but the present invention is not limited to this. rather than something that
Needless to say, any method may be used as long as the presence of the detection coil is determined from the detected yield voltage by comparison with a predetermined function value.

Effects of the Invention As is clear from the above explanation, according to the present invention, even with a simple configuration in which the induced voltage detected by the detection coil is compared with a predetermined relationship value, it is possible to determine between which conductors the detection coil exists. Since it is possible to determine whether the detection circuit is present or not, it is easy to simplify the detection circuit system, and accordingly, it is possible to reduce costs.

[Brief explanation of the drawing]

1A and 1B are schematic diagrams for explaining the position detection principle of the coordinate input device of the present invention and graphs showing the magnetic field strength distribution, and FIG. 2 is a schematic diagram for explaining the principle for determining the presence of a detection coil. 3 are block diagrams of an embodiment of the present invention. 1...Conductor, 2...Detection coil, 3...
...Input board, 4a, 4b...Multiplexer, 5
...Switch circuit, 6...Current scan circuit, 7.
...Clock pulse generation circuit, 8a, 8b...
・Counter, 9... Latch circuit, 10...
...Modulation circuit, 11a...V, detection circuit, 1 1b...
V2 detection circuit, I2...V, /V2 detection circuit,
13a, 1 3b...Voltage comparison circuit, 14...
...and circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 Having a plurality of conductors arranged in a matrix at predetermined intervals in the X direction and the Y direction, and
an input board configured to sequentially select two conductors among the conductors in each direction and supply current from the outside; and a detection coil for coordinate input movably positioned on the surface of the input board. , comprising detection means for independently detecting induced voltages induced in the detection coil by currents flowing through the two selected conductors, wherein the current flowing through one of the two selected conductors; The value of the current flowing through the two conductors is relatively changed such that the sum of the value of The position of the detection coil is determined based on the current value of one of the conductors when the ratio of the values of each induced voltage induced by the magnetic field generated by the conductor reaches a predetermined value. By comparing the values of two induced voltages induced in the detection coil by the magnetic fields generated by the respective conductors with a predetermined threshold value, the detection coil detects a voltage between the two conductors. A coordinate input device characterized in that it is configured to determine whether or not it exists.