JPS6019832B2 - digitizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tablet digitizer configured to measure the position of a cursor on the tablet based on electromagnetic coupling between the cursors, and the present invention relates to a tablet digitizer configured to measure the position of a cursor on the tablet based on electromagnetic coupling between the cursors. This device is characterized in that the tablet is provided with an electrostatic adsorption mechanism for fixing a recording medium on which graphic information is recorded onto the tablet.

Digitizers are widely used as means for converting and transmitting analog graphic information recorded on a recording medium into digital format data. One type of such device is an electromagnetic coupling system that is configured to measure the position of a cursor on a tablet based on electromagnetic coupling between the tablet and the cursor.

This method has the advantages of being relatively easy to construct tablets and force-sols, having excellent operability, and being less affected by temperature changes. Among them, as an inexpensive digitizer that can read position coordinates with relatively high accuracy, there is a digitizer (Japanese Patent Application Laid-Open No. 57-139479) filed by the applicant of the present invention. FIG. 1 is a block diagram of a main part of this digitizer, showing an embodiment of a one-dimensional digitizer specifically for explaining the principle. In Figure 1, 2
0' is an insulating board such as a printed board or glass, with a plurality of conductor loops 21 (six loops 2 in the figure) on its surface.
1, to 216) are arranged to have a single pole. This conductor loop 21 is connected to a switch circuit 2 which will be described later.
A current is supplied by 2. The magnetic flux generated from the conductor loop is detected by the magnetic flux detection cursor 3. This cursor 30' has a magnetic flux detection coil, and is provided with a position designation indicator (cross-shaped mark, etc.) in the center of the cursor 30' to enable positioning. The electromotive force of the cursor 30 is appropriately amplified by an amplifier 32 via a tuning circuit 31 and then guided to a polar detector 33. The tuning circuit 31 has a bandpass characteristic as shown in FIG. 2, and its tuning frequency is the frequency fp.of the pulse P applied to the switch circuit 22. The harmonics in the electromotive force signal generated by the cursor 3 are attenuated and removed, and only signals near the tuning frequency are passed. The polar detector 33 can be a synchronous detector, for example, and its output is a pulsating wave as shown by the dot Sunsen in Fig. 3.The fundamental wave of this pulsating wave (the third
The bandpass filter 34 extracts only the solid line waveform shown in FIG. The generation time from the start of current driving of the conductor loop until the generation of pulsating waves is determined by the conductor loop 21 of the cursor 30.
, corresponds to the separation distance for . A counter 35 counts the clocks of the oscillator 26 as shown at the beginning of FIG. 3 until the fundamental wave crosses zero when the fundamental wave changes from positive to negative.

In this case, at the point where the fundamental wave crosses zero (point A in Figure 3A), an excitation signal generated at a position corresponding to a position shifted by 90 degrees in phase from the position of the cursor 30 is applied as a start pulse from the switch circuit 22 to the counter 35. is set, and the counting operation starts. The output clock of the oscillator 26 is divided by a first frequency divider 27 and given to the switch circuit 22 as a modulation pulse P, shown in FIG. The signal is frequency-divided by and applied to the switch circuit 22 as a shift pulse P2 shown at the beginning of FIG. The switch circuit 22 internally receives a modulation pulse P.
, and the shift pulse P2 generates a current pattern that sequentially shifts the conductor loops 21, 216 as shown in FIG. The conductor loop is driven by such a current pattern, and the position of the cursor 30 can be read from the count value of the counter 35 as described above. In this case, the resolution of the digitizer is determined primarily by the short-term stability of the filter 34. There is a limit to this short-term stability, so the following measurement method is used to further improve resolution. That is, as mentioned above,
In addition to the coarse measurement mode in which the position of the cursor 30 is measured by sequentially driving the conductor loops with current, the switch circuit 22 divides the conductor loops 21 into multiple groups (for example, the loop 21
,, 212, 213 and loops 214, 215, 216) and drive the group, and each loop group has a 360°
Adopts a micro measurement mode that can detect drive based on phase changes.
If the division is made into N groups, the measurement range in the fine measurement mode will be 1/N of the measurement range in the coarse measurement mode, and the resolution in the fine measurement mode will be improved to 1/N of that in the coarse measurement mode. By the way, in such a digitizer, when fixing the recording medium on which analog graphic information to be converted into digital format data is recorded onto the tablet, it is necessary to fix it on the tablet with adhesive tape or to attach magnetic material to the outer periphery of the tablet. It is practiced to provide a body and fix it using magnetic means. However, with the former configuration, the surface of the tablet may become stained with adhesive, and with the latter configuration, it is difficult to stably adhere a recording medium smaller than the tablet. In order to solve these drawbacks, the present invention provides a tablet with an electrostatic adsorption mechanism.

Hereinafter, it will be explained in detail using the drawings. FIG. 5 is a configuration diagram of essential parts showing one embodiment of the present invention, and parts equivalent to those in FIG. 1 are given the same reference numerals.

In FIG. 5, 41 and 42 are conductive patterns for electrostatic adsorption, and 43 is a drive circuit. One conductor pattern 41 is provided in a comb shape on the insulating plate 20 common to the conductor loop 21 so as to sandwich the conductor loop 21 from both sides in the longitudinal direction, and one end thereof is commonly connected to one output terminal of the drive circuit 43. a, and the other conductor pattern 42 is provided in a comb-like shape on the insulating plate 20 common to the conductor loop 21 along the longitudinal direction of the conductor 21 within the area surrounded by the conductor loop 21. One end is common to the drive circuit 4
It is connected to the other output terminal b of 3. Drive circuit 43
A tortoise pressure is applied and released between the conductor patterns 41 and 42 to generate a potential difference of about 1000V. As a result, an electric field is generated between the conductor patterns 41 and 42, and the recording medium is electrostatically attracted to an arbitrary position on the tablet.
Here, the operation as a digitizer is performed in a sufficiently high frequency range compared to the ripple frequency component included in the voltage applied for electrostatic adsorption, so the electrostatic adsorption operation is performed as a digitizer. There will be no impact.

FIG. 6 is a block diagram showing a main part of another embodiment of the present invention, in which a conductor loop 21 is used in place of the conductor pattern 42 in FIG.

That is, the conductor loops 21 are each commonly connected to the output terminal b of the drive circuit 43. As a result, the fifth
The same electrostatic adsorption operation as shown in the figure can be obtained, and the insulating plate 2
The number of conductor patterns on 0 can be reduced. In the above embodiment, an example was explained in which the digitizer generates magnetic flux on a tablet and detects it with a cursor, but it may be configured such that magnetic flux is generated with a cursor and this magnetic flux is detected with a tablet. .

Further, in the above embodiment, an example was shown in which a conductor pattern for electrostatic adsorption is provided on the insulating slope that constitutes the tablet, but the conductor pattern for electrostatic adsorption is provided on another insulating plate.
It may be overlapped with the tablet.

In addition, in the above embodiment, an example was explained in which a conductor pattern for electrostatic adsorption is newly provided and the electrostatic adsorption operation is performed regardless of whether or not it operates as a digitizer. The loop may also be used as a conductor pattern for electrostatic attraction, and may be operated in a time-sharing manner as a digitizer and as an electrostatic attraction mechanism.

That is, when performing two-dimensional measurement in X and Y, the conductor loop in the x direction and the conductor loop in the Y direction are driven alternately, so that one of the conductor loops is always at rest.
A predetermined voltage may be applied to this resting conductor loop to perform an electrostatic adsorption operation. With this configuration, the configuration of the tablet can be simplified. As explained above, according to the present invention, it is possible to realize an electromagnetic coupling type digitizer that can stably fix a recording medium on which analog graphic information to be converted into digital format data is recorded on a tablet, and to put it into practical use. The above effect is significant.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional digitizer, Figure 2 is a diagram for explaining the bandpass characteristics of a tuning circuit, Figures 3 and 4 are operational waveform diagrams of each part, and Figure 5 is a diagram of the present invention. FIG. 6 is a block diagram showing another embodiment of the present invention. 20... Insulating plate, 21... Conductor loop, 41, 42...
- Conductor pattern, 43... drive circuit. Multiple Z diagrams, multiple J diagrams, multiple 4 diagrams * Foundation J diagram, multiple diagrams

Claims (1)

[Claims] 1. A cursor having a coil is movably placed on a tablet to which is fixed a recording medium made of an insulating plate on which a plurality of conductor loops are arranged and on which analog graphic information to be converted into digital data is recorded, In a digitizer configured to measure the position of a cursor on a tablet as data in digital form based on electromagnetic coupling between the tablet and the cursor,
A digitizer characterized in that the tablet is provided with a plurality of conductor patterns to which a voltage is applied for electrostatically attracting the recording medium.