JPH0122930B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic coupling type coordinate reading device, and more particularly to a coordinate reading device that corrects variations in coordinate values due to expansion and contraction of a sense line plate.

Conventional electromagnetic coupling type coordinate reading devices have the disadvantage that when the sense line plate expands or contracts due to changes in temperature, the coordinate values also change accordingly, and to prevent this, the materials used are limited to expensive ones that do not change much. It was hot.

The present invention has been made to solve the above-mentioned drawbacks, and by providing an excitation coil for correcting coordinate values in the tablet, the sense line plate can be made of any material, and the coordinates that change due to the expansion and contraction of the sense line plate can be adjusted. The object of the present invention is to provide a coordinate reading device that corrects values as needed.

An embodiment of the structure and data processing of a tablet according to the present invention will be explained with reference to FIGS. 1, 2, 3, and 4.

FIG. 1 is a plan view of a tablet according to an embodiment of the invention, and FIG. 2 is a side sectional view of the tablet.

In the drawing, 1 is a sense line board on which a plurality of X-axis and Y-axis sense lines are laid, 2 is a decorative board that covers the upper surface of the sense line board 1, and 3
numeral 4 is a pin that penetrates and fixes the sense line board 1 together with the decorative board 2 at the end; 4 has a frame shape and fixes the sense line board 1 through the pin 3; A metal fixing plate 5, a correction coil fixed to the opposite side of the fixing side of the sense line plate 1 in the fixing plate 4 and disposed on the lower surface of the sense line plate 1; 6, normal coordinates; This is the reading range for reading, and the correction coil 5
is located outside this range 6. Reference numeral 7 denotes a coordinate indicator that faces the sense line plate 1 and has a built-in excitation coil for specifying coordinates, and 8 refers to a base plate that is built in the fixed plate 4 and supports the lower surface of the sense line plate 1. One end of this base plate 8 is fixed to the fixed plate 4 together with the sense line plate 1 via the pin 3 mentioned above. Processing of signals from the sense line plate 1 induced by the coordinate indicator 7 and the correction coil 5 of the tablet having these structures is carried out by a CPU 9 shown in FIG.

FIG. 3 shows a block diagram of the coordinate reading device according to the present invention, in which 10 is a switch circuit operated by a control signal C from the CPU 9; Excitation circuits 12 and 13 for supplying excitation signals F to the coordinate indicator 7 are
An analog circuit and an AD conversion circuit for processing the induction signal from the sense line board 1, which is controlled by the address signal A output from the CPU 9, and converting it into a digital signal D; 14 is an external device 1;
5 (host computer, etc.) is an interface circuit for outputting the coordinate value signal I from the CPU 9.

Next, the operation will be explained including the correction sequence flowchart shown in FIG. In normal coordinate reading operation, the excitation signal F from the excitation circuit 11 is supplied to the coordinate indicator 7 as shown in FIG.
The electromagnetic induction signal from the sense line plate 1 facing the coordinate indicator 7 is converted into a digital signal D.
It is input to CPU9. Within the CPU 9, the position of the coordinate indicator 7 on the sense line plate 1 is calculated and outputted to the external device 15 as a coordinate value signal I.

Next, we will discuss the case in which the correction coil 5 operates. First, at the moment the coordinate indicator 7 leaves the tablet surface and goes outside the reading range 6, the CPU 9 outputs the control signal C to activate the switch circuit 10. The correction coil 5 is switched to be energized, and the coordinate values generated thereby are determined. (Hereinafter, these will be referred to as correction coordinates.) A correction coefficient is calculated from this value and the coordinate value of the correction coil 5, which has been previously measured under certain conditions (hereinafter referred to as basic coordinates), and the CPU 9 Store it in internal memory. The coordinate indicator 7 approaches the tablet surface,
When a coordinate value (hereinafter referred to simply as a coordinate value is limited to one generated by the coordinate indicator 7) is generated within the reading range 6, the coordinate value is corrected using the above correction coefficient, and then Perform normal coordinate processing (for example, formatting).

Correction methods include finding the difference between the correction coordinates and basic coordinates, drawing a table, and multiplying the coordinate values by the contents of the table as a ratio; or, if the expansion and contraction of the fixed plate 4 can be ignored, directly calculating the correction coordinates. A possible example is a method in which the ratio of basic coordinates is calculated and the coordinate value is multiplied.

For example, if polycarbonate is used for the sense line plate 1 and iron is used for the fixed plate 4, the linear thermal expansion coefficient of polycarbonate is 7 x 10 ^-5 and that of iron is 1.1 x 10 ^-5 , so the operating temperature range of the coordinate reading device is 10℃～
When the temperature is 40° C. and the length of one side of the sense line plate 1 is 1.5 m, the sense line plate 1 expands and contracts by 3.15 mm and the fixed plate 4 expands and contracts by 0.5 mm. Here, with the correction method that directly takes the ratio of both, it is possible to suppress the variation in the coordinate values after correction to 0.5 mm, which is the amount of expansion and contraction of iron. This is on the same level as expensive glass epoxy resin. However, with the correction method of drawing the ratio in a table, it is possible to reduce the variation in coordinate values to 0 mm after correction.

Note that since this correction method detects the fluctuation itself, it is possible to promptly deal with fluctuations not only due to temperature but also due to all other causes.

As described above, according to the present invention, a correction coil is provided on the fixed plate made of a different material from the sense line plate, and the error in coordinate values due to expansion and contraction of the sense line plate is corrected. The material can be used as an addition to the traditional coordinate reading device,
Only a small amount of hardware is required to be changed, and the objective of cost reduction can be achieved through simple software processing without compromising coordinate reading accuracy. Furthermore, since sampling of the correction coefficient is performed at the moment when the coordinate indicator moves out of the reading range, it can be automatically performed at any time without interfering with the reading of coordinate values by the coordinate indicator. Therefore, no restrictions are placed on the user during correction.

[Brief explanation of drawings]

FIG. 1 is a plan view of a tablet according to an embodiment of the present invention, FIG. 2 is a side sectional view of FIG. 1, FIG. 3 is a circuit block diagram showing an embodiment of the present invention, and FIG. 4 is a CPU of the present invention. It is a flowchart showing processing. 1... sense line board, 2... decorative board, 3...
Pin, 4...Fixing plate, 5...Correction coil, 6...
...reading range, 7...coordinate indicator, 8...base board, 9...CPU, 10...switch circuit section, 1
1... Excitation circuit, 12... Analog circuit, 13...
...A/D conversion circuit, 14...Interface circuit, 15...External device, A...Address signal, D
...Digital signal, C...Control signal, F
...excitation signal, I...coordinate value signal.

Claims (1)

[Claims] 1. A sense line plate having a plurality of sense lines, a coordinate indicator facing the sense line plate, a fixing plate fixing one end of the sense line plate, a correction coil fixed to the fixing plate, The present invention includes an excitation circuit for appropriately exciting the correction coil, and is configured to detect the amount of expansion and contraction of the sense line plate based on an induction signal generated from the correction coil to the sense line, and correct the coordinate read value. An electromagnetically coupled coordinate reading device characterized by: