JPH04370820A - Digitizer - Google Patents

Abstract

PURPOSE:To hold efficient relation between a position indicator and a tablet which are not connected physically by adding a signal for controlling the position indicator to a radio wave generated on the tablet side and providing a means which decodes the signal on the position indicator side. CONSTITUTION:The power supply grid plate 1 and radio wave detection plate 2 of the tablet are superposed on one over the other to form one coordinate input plate. The power supply grid plate l consists of two grid lines 11 and 12. The radio wave detection plate 2, on the other hand, has plural looped coils extended in an X and a Y direction respectively and they are connected to an X-axial scanner and a Y-axial scanner 36. A crystal oscillator 32 operates under the command of a processor 31 provided in an electric part and generates a clock of specific frequency. This clock is supplied to a frequency divider 37 to generate an operation clock for controlling the power supply grid plate 1 as the rear stage. A phase shifter 38 as a following stage applies a signal SIN and a signal COS to the grid according to the generated clock.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digitizer for reading the coordinates of a designated position on a surface, and more particularly to a so-called cordless digitizer in which a position indicator for indicating the position to be read is not connected to the tablet body.

0002

[Prior Art] One of the conventional cordless digitizers of this kind
One method is to apply for patent application No. 2-7 filed earlier by the applicant.
There is a device described in the '85 application.

[0003] This device includes a power capture coil as a power capture means for receiving electric waves emitted from the tablet side and capturing power into the position indicator, a resonance capacitor for the power capture coil, and a capacitor for resonance thereof, and a power capture device that receives radio waves emitted from the tablet side and captures the power into the position indicator. A DC converter that rectifies and smoothes the converted electric power to convert it into DC current, a transmitter that receives the DC current from this DC converter and generates a predetermined signal, and a transmitter that connects to this transmitter and transmits radio waves to the tablet. A position indicator is constituted by a coil serving as a means for generating , and a radio wave detection means for detecting radio waves emitted from the position indicator is provided on the tablet side.

0004

[Problem to be solved by the invention] By the way, in the above-mentioned device, the position indicator and the tablet are not connected in any way, and therefore it is a good device to use, but it is difficult to match the timing of measuring the position etc. However, it had some difficult drawbacks.

For example, consider a case where a position indicator is provided with a plurality of switches, and these switches are coded to identify which of the plurality of switches is in operation. The position indicator captures radio waves from the tablet and uses them as power to operate the position indicator. For example, if each switch of the position indicator is encoded as an 8-bit signal, the 8-bit signal needs to be transmitted as a group. In this case, it is generally considered that a clock generator (transmitter) is provided within the position pointing device and the above-mentioned encoded information is placed on the generated clock.

However, in this case, it is necessary to match the oscillation frequency of the clock oscillator on the position indicator side with the oscillation frequency of the clock oscillator that defines the detection timing of the radio wave detection means on the tablet side. However, even with this configuration, the position indicator will still emit the necessary signals as described above in response to arbitrary operations by the operator, so the timing of the transmission on the position indicator side and the reception on the tablet side will be different. There is a drawback that it is difficult to match the timing, etc., and the time required to measure the position, etc. is inevitably increased.

[0007] The present invention was made in view of this point, and was made for the purpose of matching the transmission and reception timing between a position indicator and a tablet that are connected cordlessly (wirelessly) using a relatively simple method. be.

[0008]

[Means for Solving the Problem] Therefore, in this device, a control signal for controlling the position indicator by the control means of the tablet is added to the radio waves emitted by the radio wave emitting means of the tablet, and a control signal for controlling the position indicator is added to the radio waves emitted by the radio wave emitting means of the tablet. The device is provided with a decoding means for decoding the control signal added to the radio waves from the tablet, and a processing means for performing necessary processing based on the decoding result of the decoding means.

[0009]

[Operation] A control signal that defines the signal output timing of a position indicator, for example, is added to the radio waves generated by the radio wave emitting means of the tablet. That is, a control signal for obtaining a signal indicating the operation state of a switch of a position indicator from the tablet side is added to the radio waves emitted from the tablet by the control means. In the position indicator, this radio wave is taken in by the power acquisition means, but at that time, this control signal is also taken in and the decoder installed in the position indicator decodes what kind of signal the control signal is required. . Based on the decoding result of the decoding means, a processing device provided in the position pointing device performs a predetermined process, and transmits a signal to the tablet according to the request from the tablet. When the tablet side adds the control signal to the radio wave and transmits it, it is equipped with a system to receive the transmission signal corresponding to the control signal from the position indicator, and can receive it efficiently.

0010

[Embodiment] Figures 1 to 4 show the configuration of a cordless digitizer according to the present invention. Figure 1 is an explanatory diagram showing the overall configuration of this digitizer, and Figure 2 is the configuration of a grid plate as a radio wave emitting means. An explanatory diagram showing an example, FIG. 3 is a waveform diagram for explaining the method of adding a control signal of this radio wave emitting means, and FIG. 4 is an explanatory diagram showing an example of position indicator information transmitted based on this control signal. be.

First, the configuration and operation of a digitizer related to the present invention will be explained with reference to FIG.

The digitizer shown in FIG. 1 is composed of a tablet main body composed of a power supply grid plate 1, a radio wave detection plate 2, and an electric component 3, and a position indicator 4.

The power supply grid plate 1 and the radio wave detection plate 2 of the tablet are stacked on top of each other to form one coordinate input plate. This power supply grid plate 1 is composed of two grid lines 11 and 12, as shown in FIG. 2, for example. The first grid line 11 and the second grid line 12 are provided so as to be shifted from each other by 1/4 pitch, and have a so-called two-phase configuration. On the other hand, as shown in FIG. 1, the radio wave detection plate 2 has a plurality of loop coils stretched in the X direction and the Y direction, and is connected to an X-axis scanner 35 and a Y-axis scanner 36, respectively. There is.

A crystal oscillator 32 operates according to a command from a processor 31 provided in the electrical section to generate a clock of a predetermined frequency. This clock is used by a frequency divider 37 to create an operating clock for controlling the power supply grid plate 1 at the subsequent stage. Based on the created operating clock, the next stage phase shifter 38
creates a SIN signal and a COS signal, and applies the COS signal of these to the first grid line 11 and the SIN signal to the second grid line 12 shown in FIG. The power supply grid plate 1 thereby generates radio waves.

The radio waves emitted by the power supply plate 1 excites the power receiving coil 41 of the position indicator 4. A capacitor is connected to this power receiving coil 41 to form a resonant circuit. The power is taken in as electric power to a power converter 42 configured with a rectifier circuit, a rechargeable battery, or the like. This power becomes energy for the crystal oscillator 40, frequency divider 49, demodulator 43, parallel/serial converter 45, modulator 46, and amplifier 47.

Each switch in the switch group 44 is assigned a different code string, and when any one of the switches is operated, the radio waves transmitted by the amplifier 47 and the radio wave transmitting coil 48 are affected by the specific switch. The code string information is configured to be superimposed.

The radio waves from the radio wave transmitting coil 48 act on each loop coil of the radio wave detection plate 2. An induced voltage is generated in each loop coil depending on the degree of coupling with the radio wave sending coil 48 of the position indicator. X-axis scanner 35
And the Y-axis scanner 36 detects induced voltages generated in these loop coils. By calculating these induced voltages by the main body circuit 34 and processor 31, the position indicated by the position indicator can be determined.

By the way, in this device, different code strings are assigned to each of the plurality of switches 44 provided in the position indicator. Now, assuming that this code string information is expressed in 8 bits, the radio waves sent out from the radio wave sending coil 48 of the position indicator have 8 bits.
Bit information is given. Therefore, an induced voltage on which these 8 bits of information are superimposed is generated in each loop coil of the radio wave detection plate 2. In this case, the main circuit 34 needs to read the voltages induced in these loop coils on a bit-by-bit basis without error. For this purpose, it is necessary to make the operating clock of the radio waves sent out from the radio wave sending coil 48 and the operating clock of the main body circuit 34 almost the same. Therefore, in this embodiment device, the frequency divider 33 and the position indicator 4 of the tablet-side electrical component are
The clock generated by the frequency divider 49 mounted on the clock is related to each other.

As an example of this relationship, the operating clock on the position indicator 4 side and the operating clock of the main circuit 34 are set to the same frequency, and on the position indicator 4 side, for example, every 1000 operating clocks are set to the same frequency. Information to be transmitted 1
It can be configured such that a bit signal is given and the main circuit 34 acquires bit information every 1000 operation clocks. By configuring like this,
Information can be transmitted without error even if the tablet and the position indicator 4 are not physically connected.

Furthermore, in the present invention, in order to achieve more efficient information transmission, the timing of information transmission and reception is matched. See FIG. 3. A signal indicated by the symbol A is a control signal indicating a request for information from the processor 31 shown in FIG. 1 to the position pointing device 4. This control signal is superimposed on the radio wave (reference numeral B in FIG. 3) generated by the power supply grid plate 1 (FIG. 1) and transmitted to the position indicator 4.

Control signals from the processor 31 are applied to the two signals SIN and COS, which are input to the modulator 30 and supplied to the power supply grid plate 1, via respective amplifiers 391 and 392. As a result, the radio waves emitted from the power supply grid plate 1 become as shown by the symbol C in FIG.

[0022] The power receiving coil 41 of the position indicator is excited by this radio wave. The voltage induced in this power receiving coil 41 is ESIN (ωt+2πX/D) in a normal case where no control signal is included (symbol B in FIG. 3).
. Here, X is the amount of displacement of the power receiving coil 41 in the X direction. The voltage induced in the power receiving coil 41 is rectified by a power converter 42, for example, and is used as power for operating each element of the position indicator 4.

When a control signal is added to the radio wave from the power supply grid plate 1 as shown in the symbol B in FIG. 3, the demodulator 43 of the position indicator 4 outputs a signal as shown in the symbol D in FIG. Create. A predetermined relationship is defined in advance between the demodulated signal of the demodulator 43 of the position indicator 4 and the control signal added to the radio waves emitted by the tablet. As shown in FIG. 3D, it is decided in advance what state the position indicator 4 should be set in depending on the case, such as when a single pulse signal is used or when a plurality of pulse trains are continuously generated at predetermined intervals. Then, a logic circuit (included in the demodulator 43 in FIG. 1) for decoding and processing these control signals is configured on the position indicator 4 side. As a result, a signal as indicated by symbol E in FIG. 3 is transmitted to the tablet. Note that the signal indicated by symbol D in FIG.
In this embodiment device, the switch 44 of the position indicator 4
It is defined as requiring the operational status of.

The code information of any of the switches in the switch group 44 that is activated is superimposed on the signal to be sent out by the modulator 46 via the parallel-to-serial converter 45. This modulated signal is emitted by the radio wave sending coil 48 toward the radio wave detection plate 2 of the tablet. This emitted radio wave is sent out in accordance with the operation clock of the position indicator 4, as shown by reference symbol F in FIG. Note that this operating clock F is 1000
A collection of clocks is shown here. Information transmission regarding the switch state of the position indicator 4 is superimposed on this transmitted radio wave. As shown by symbol E, one bit of information is transmitted every 1000 clocks, and a total of 8 bits of data are used to represent one operating state. The first two bits are the start bit, the next five bits are the switch information, and the last bit is the stop bit.

The transmitted radio wave containing the switch information from the position indicator 4 induces a predetermined voltage in the loop coil group of the radio wave detection plate 2 of the tablet. The voltage induced in the radio wave detection plate 2 is detected by the X-axis scanner 35, the Y-axis scanner 36, and the main circuit 34. The switch information from the position indicator described above is in a predetermined format and is transmitted in response to a request from the tablet side, so the X-axis scanner 35, Y-axis scanner 36, and main body circuit 34 are By operating according to the following operating procedure, the switch information of the position indicator 4 can be received efficiently and without error.

In the embodiment of the present invention, an example is shown in which a power supply grid plate using two grid lines is used as the radio wave emitting means, but each loop coil of the radio wave detection plate 2 is connected in a time-sharing manner. It may be configured to be used as a radio wave emitting means or a radio wave detecting means.

[0027]

[Effects of the Invention] As explained above, according to the present invention,
A signal for controlling the position indicator is added to the radio waves generated from the tablet side, and a means for decoding and processing this control signal is provided on the position indicator side, so it can be used as a position indicator that is physically uncoupled. It is possible to have an efficient relationship with the tablet.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a cordless digitizer showing one embodiment of the present invention.

FIG. 2 is a configuration diagram showing an example of a power supply grid plate according to the present invention.

FIG. 3 is a waveform diagram of main parts of the cordless digitizer shown in FIG. 1;

FIG. 4 is a waveform diagram of switch information related to the present invention.

[Explanation of symbols]

1: Power supply grid board 2: Radio wave detection board 3: Electrical component 4: Position indicator

Claims (1)

[Claims] Claim 1: The position indicator includes a power capture device that captures radio waves emitted from the tablet side as power, and a radio wave transmission device that transmits radio waves generated based on the captured power to the tablet side. has a radio wave emitting means for emitting radio waves toward the position indicator, a radio wave detecting means for detecting the radio waves sent from the position indicator, and a control means for controlling the radio wave emitting means and the radio wave detecting means, In the digitizer configured to detect the indicated position of the position indicator on the tablet, a control signal for controlling the position indicator by the control means is added to the radio waves emitted by the radio wave emitting means of the tablet. In addition, the position indicator is equipped with decoding means for decoding the control signal added to the radio waves from the tablet, and processing means for performing necessary processing based on the decoding result of the decoding means. A digitizer featuring: