JPS6012652B2 - Electromagnetic coupling type coordinate reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetically coupled coordinate reading device that inputs two-dimensional information such as handwritten characters and graphics into a computer, for example, by utilizing electromagnetic induction phenomena.

Conventionally, a coordinate indicator having a coil that generates an alternating magnetic field is electromagnetically coupled to a sense line board having a sense line laid according to the Gray code law, and coordinates are indicated by detecting the induced electromotive force generated in the sense line. Devices for determining the coordinate position of vessels were well known.

However, in the conventional technology, the resolution of the coordinate reading device was determined by the spacing between the sense lines, so even if print pattern technology was used, the resolution on the 0.5 side was the practical limit. . The present invention has been made in order to promptly solve the above-mentioned drawbacks, and by providing an additional sense line and performing arithmetic processing using the induced voltage generated in the additional sense line, the minimum pitch of the sense line according to the Gray code can be adjusted. The object of the present invention is to provide an electromagnetic coupling type coordinate sampling device that obtains a high resolution of at least one tenth. The drawings will be explained in detail below.

FIG. 1 shows an example of the sense line installation pattern of the device of the present invention. In Fig. 1, SI to S4' are a 4-bit configuration sense line group laid out on the sense line board according to the law of Gray codes, each having a one-turn coil having output terminals AI to A4 and grounds GI to G4. is formed. Output terminal A4 in the figure represents MSB, and sense line SI
The highest number is 4. Pitzchi. P1 and P2 indicate two bending points at the ends of the sense line SI. S5 is an additional sense line newly added and installed at the refraction point P2 parallel to the line connecting the output end AI and the refraction point PI. From the output end AI to the refraction point PI. The loop of the sense wire SI from P2 to the ground GI and the loop of the sense wire S5 from the additional output device A5 to the ground GI via the bending point P2 form a one-turn coil with opposite winding directions. ing. Figure 1 shows only the x axis, but
The actual sense line board is composed of a Y-shaped sense line group (not shown) laid perpendicular to the X-axis. For convenience, only the X-axis will be described below with reference to FIG. 2. Figure 2 is the first
This is an embodiment of a circuit that converts analog signals generated at the output terminals AI to A4 and the additional output terminal A5 of the figure into digital signals, and in which a coordinate indicator is located.

When the coordinate indicator (not shown) is brought close to the sense line board, the output terminals AI to A4 and the additional output terminal A5 have induced induced voltages whose size corresponds to the positional relationship between the coordinate indicator and the sense lines SI to S5. An analog signal that is a voltage is generated. This analog signal is switched from time to time by an analog switch CI selected by a control signal fl and inputted to a multiplier C2.
The output of the multiplier C2 is passed through the bandpass filter C3 and the full wave rectifier C4.
, passes through a low-pass filter C5 to become a DC signal, and further enters an AD converter C6 with, for example, a 4-bit calculation accuracy to become a 4-bit digital signal D. Next, an embodiment of a calculation method for determining coordinate values using this digital signal D will be described in detail. To obtain the coordinate values from the sense lines SI to S4 according to the normal gray code, first compare the digital signal D4 corresponding to the output terminal A4 with a preset reference value VTH, and if D4≧VTH, select the MSB. Score 1. By repeating this operation successively up to the output terminal AI, a 4-bit Gray code is obtained, and when this is converted into a binary signal, a 4-bit coordinate value is obtained. Since this is a conventional resolution, when the bit configuration of the finally obtained data is 8 bits as shown in FIG. 4, the coordinate value is set in the upper register C9 as the upper 4 bits. Next, to obtain the lower 4 bits related to high resolution, the ratio Q of the digital signal DI corresponding to the output terminal AI and the digital signal D5 corresponding to the additional output terminal A5 is set by the calculation circuit so as to satisfy the following [2] length. Calculate using C7. Q=DI/D5...
・・・・・・・・・・・・【1}0≦Q≦1 ……………
'21 Therefore, the above formula [1} is for DIS05,
When D>D5, Q=D5/DI.

Regarding the necessity of performing division, see Japanese Patent Application Laid-Open No. 53-31.
Since it is described in Publication No. 3, the explanation will be omitted. Figure 3 is a diagram showing the relationship between the value of the ratio Q determined by '1) above and the position within 1/21 determined by the upper 4 bits of the coordinate value of the coordinate indicator, where the vertical axis is Q and the axis is the coordinate indicator '1 indicates the minimum pitch of the sense line SI.

As is clear from FIG. 3, the value of Q exhibits an upwardly convex characteristic with respect to 1, and is symmetrical about the maximum point 1/21. The positional relationship between the value of Q and the coordinate indicator is such that if the upper 4 bits of the coordinate value are even numbers, they are to the left of 1/21 in FIG. 3, and if they are odd numbers, they are to the right. Therefore, if the value of Q is set as the address of ROMC8, and the left part of Figure 3 is input as the data of ROMC8, the lower 4 bits of the coordinate value will be the data of ROMC8 itself if the upper 4 bits are even, and if the upper 4 bits are odd, R.O.
Set the number 2 in the data of MC8 to the lower register CI. FIG. 4 shows the bit configuration of the coordinate values obtained by the above calculation operations. Bit B4 has a weight equal to 1/2 of the pitch of the sense line SI, and the weight of bit 80 is 1'32 of the pitch of the sense line S1. becomes the weight of In other words, theoretically, 1/6 of the sense line which has the smallest pitch
A resolution of 4 can be obtained. In the above embodiment, the signal at the additional output terminal was used to find the ratio Q so that 0≦Q≦1, but the same effect can be obtained even if the ratio Q is found so that Q≧1. Effects can be obtained.

It goes without saying that the number of bits of the sense line of the Gray code and the number of bits of the calculation accuracy of the A/○ converter can be set as appropriate, respectively, as required. Furthermore,
Arithmetic circuit, registers and ROM are CPU or MP
It is also possible to change the layer to U. As described above, according to the present invention, an additional sense line is provided to generate an induced electromotive voltage of a reverse gutter type with respect to the sense line having the smallest pitch among the sense line group according to the Gray code law. Since the configuration is configured to perform the comparison calculation, it is possible to provide an electromagnetic guide type coordinate reading device having a resolution of at least one-tenth of the minimum pitch.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the sense line board of the electromagnetically coupled coordinate reading device of the present invention, FIG. 2 is a block diagram showing the circuit configuration according to the embodiment of the present invention, and FIG. A characteristic diagram showing the positional relationship between the voltage ratio and the coordinate indicator, and FIG. 4 is an explanatory diagram showing the bit configuration of data in a register representing coordinates. SI~S4...Sense line, AI~A4...Output end, S5
...Additional sense line, A5...Additional output device, GI
~G4...Ground, PI~P2...Bending point at the end of sense line AI, CI...Analog switch, C2...Intensifier, C3...Obijo filter, C4...Rectifier ,
C5... Reduction filter, C6... AD converter, fl... Analog switch control signal, DI
~○5...Digital signal, Q...Induced voltage comparison value, 1...Minimum sense line pitch, Bo
...LSB, B4...Bit with weight equal to 1/2 of the pitch of the minimum sense line, B7...MSB. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In an electromagnetic coupling type coordinate reading device consisting of a sense line board equipped with a sense line group laid according to the Gray code law and a coordinate indicator corresponding to this sense line board, the minimum pitch of the sense line group is Sense line S1
An additional sense line S5 having an output end A5 is provided at the refraction point P2 at the end of the line so as to be parallel to the line connecting the other refraction point P1 and the output end A1 of the sense line having the minimum pitch; an arithmetic circuit that compares and calculates the induced electromotive force generated at the output terminal A5 and the induced electromotive force generated at the output terminal A1; and a ROM that uses the result of this operation as an address and outputs the position of the coordinate indicator as data. , and a register for adding the data in the ROM to data on the position of the coordinate indicator determined only by the sense line group excluding the additional sense line S5.