JPS63115218A - Position detector - Google Patents

Abstract

PURPOSE:To eliminate a need of cords and improve the operability by detecting a designated position by the induced voltage which is generated by radio transmission and reception between loop coils of a position detecting part and the tuning circuit of a position designating part. CONSTITUTION:The radio wave from a transmitting circuit 40 is transmitted between a position pointer 60 having a tuning circuit 61 and a loop coil C which is successively selected from plural loop coils of a position detecting part 4 by information sent from a processor 70 to a selecting circuit 20 and a connection switching circuit 30. In this case, the induced voltage generated in a receiving circuit 50 is converted to a detection voltage proportional to the distance between the position pointer 60 and the selected loop coil C to calculate a coordinate value indicating the position pointer 60, and designated position data is displayed on a coordinate display device with the same coordinates. By this constitution, cords are eliminated to improve the operability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a position detection device in which a position indicator is not connected anywhere and which has high position detection accuracy.

(Prior Art) As a conventional position detection device, a pulse current is applied to a drive coil provided at one end of a magnetostrictive transmission medium or a tip of a position indicator, and magnetostrictive vibration waves are generated in the magnetostrictive transmission medium. , a processing device or the like measures the time until an induced voltage based on the magnetostrictive oscillation waves is detected in a detection coil provided at the tip of the position indicator or one end of the magnetostrictive transmission medium, and calculates the specified position of the position indicator from this. There was something I did.

In addition, as another conventional position detection device, a plurality of drive lines and detection lines are arranged perpendicularly to each other, and current is sequentially applied to the drive lines and detection lines are sequentially selected to detect induced voltage. There is a device in which a position specified by a position indicator made of a magnetic material such as ferrite is detected from the position of a detection line in which a large induced voltage is induced.

(Problem to be solved by the invention) Although the former device has relatively good position detection accuracy, it requires a code between the position indicator and the processing device to send and receive timing signals, etc. There are problems in that handling is severely restricted and the position indicator must be held perpendicular to the magnetostrictive transmission medium and used very close to it. In addition, although the position indicator in the latter device can be made cordless, the resolution of the coordinate position is determined by the line spacing, and if the line spacing is made small to increase the resolution, the S/N ratio and stability will deteriorate. It was difficult to increase the resolution, it was difficult to detect the position directly above the intersection of the drive line and the detection line, and there were other problems such as the position indicator had to be placed extremely close to the line. .

The present invention has improved these conventional problems, and has good operability since the position indicator is not connected anywhere, and highly accurate position detection can be obtained, and the position detection result can be transferred to the position indicator. It is an object of the present invention to provide a position detection device that is displayed using the same coordinates as the support position.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes a position detecting section in the X direction and the Y direction in which a plurality of loop coils are arranged in parallel in the X direction and the Y direction, respectively; an X-direction and Y-direction selection circuit that sequentially selects one loop coil in the X-direction and Y-direction from a plurality of loop coils in the X-direction and Y-direction; and a predetermined frequency that is supplied to the X-direction and Y-direction loop coils. a transmitting circuit that generates an alternating current signal; a receiving circuit that detects an induced voltage having approximately the same frequency as the alternating current signal among the induced voltages generated in the loop coil in the X direction and the Y direction; an X-direction and Y-direction connection switching circuit that alternately connects one loop coil in the Y-direction to the transmitting circuit and the receiving circuit; and an X-direction and Y-direction loop that includes a coil and a capacitor and is supplied with the AC signal. a position indicator having a tuning circuit tuned to radio waves generated by the coil; and a processing device that determines the specified position of the position indicator in the X direction and Y direction from the induced voltage generated in each of the loop coils in the X direction and the Y direction. , and a coordinate display display superimposed above the position detecting section and displaying designated position data in the X direction and Y direction determined by the processing device using common coordinates.

(Embodiment) Fig. 1 shows the configuration of a system of a position detection device as an embodiment of the present invention.
3 is a control device, 3 is a power supply device, and 60 is an input pen as a position indicator.

As shown in FIGS. 1 and 2, the input/output cover panel 1 is
Each position detector 4X in direction and Y direction.

A flat display panel, for example, a liquid crystal display panel 5, as a display for displaying coordinates, is mounted on the position detection unit 4 made up of a 4Y, and these are housed in a case 6 made of metal or the like.

As shown in FIG. 3, the control device 2 includes a position detection control circuit 7 that controls the position detection section 4, a display control circuit 8 that controls the liquid crystal display panel 7, and a computer 9 that centrally controls these. It has become.

The power supply device 3 includes a well-known rectifier, transformer, DC-DC converter, etc., and supplies power to each circuit within the control device 2 .

FIG. 4 shows the position detection control circuit related to the X direction of the position detection control circuit 7 and the configuration of the position detection section 4, and mainly describes the control in the X direction.

In the figure, 4x is an X-direction detector of the position detection unit 4, 20 is a selection circuit, 30 is a reception circuit, 40 is a selection circuit, 50 is a connection switching circuit, 60 is a position indicator, and 70 is an electronic computer 9. This is a processing device that

The position detection unit 4 includes a plurality of loop coils, for example, 48 loop coils CI, C2°...C4, each having conductors parallel to each other.
8 is the direction of arrow A in the figure (hereinafter referred to as the position detection direction).

) are arranged in parallel. In addition, each loop coil 01
~C4B are arranged parallel to each other and overlapping each other.

The position detecting section 4 is constructed by connecting a large number of parallel conductors formed by etching a well-known printed circuit board with jumper wires or the like.
The plurality of loop coils described above can be used.

The selection circuit 20 selects the plurality of loop coils 01 to C48.
One end of each of the loop coils 01 to C4B is connected to one terminal group 21, and the other end is connected to another terminal group 22, respectively.

Selection contact 23 corresponding to terminal group 21 and terminal group 22
The selection contacts 24 corresponding to the processing device 70 are interlocked with each other.
One loop coil is selected by operating based on information from the above.

The selection circuit 20 can be realized by combining a large number of well-known multiplexers.

The connection switching circuit 30 connects the loop coil selected by the selection circuit 20 to the transmitting circuit 40 and the receiving circuit 5.
0 alternately, and the selection contacts 23 and 24 of the selection circuit 20 are connected to the selection contacts 31 and 32, respectively. Further, the two output terminals of the transmitting circuit 40 are connected to the terminals 33 and 35, and the receiving circuit 5
The two input terminals of 0 are connected to terminals 34.36.

The selection contact 31 corresponding to the terminal 33.34 and the selection contact 32 corresponding to the terminal 35.36 are interlocked with each other,
It operates based on a transmission/reception switching signal, which will be described later, and switches between transmission and reception.

Note that the connection switching circuit 30 is also realized by a well-known multiplexer.

FIG. 5 is an overall configuration diagram of the position detection control circuit 7 and the position detection section 4, and the same parts as in FIG. 4 are denoted by the same reference numerals.
The Y-direction control portion having the same function as the X-direction control portion is indicated by the same reference numeral with a dash. In the same figure,
4x and 4Y are X formed on the printed circuit board, respectively.
position detectors in the direction and Y direction, 20 and 20' are
The direction and Y direction selection circuits 30 and 30' are connection switching circuits for the X direction and Y direction, and the position detectors 4X, 4
Regarding Y, each loop coil shown in the position detection section 4 in FIG. 4 is perpendicular to the X direction and the Y direction, respectively.
are superimposed on each other.

Furthermore, the processing device 70 alternately performs position detection in the X direction and the Y direction.

FIG. 6 shows details of the transmitting circuit 40 and receiving circuit 50. Note that since the control in the X direction and the Y direction is the same, the figure shows one of them. In the same figure, 41
is an oscillator, 42 is a frequency divider, 43.44 is a Nant gate,
45 is exclusive OR (EXOR) gate, 46
is a driving circuit, and these constitute the transmitting circuit 40.

Further, 51 is an amplifier, 52 and 53 are phase detectors, and 54 and 55 are low-pass filters (LPF), which constitute the receiving circuit 50.

A position indicator (hereinafter referred to as an input pen) 60 has a built-in tuning circuit 61 including a coil and a capacitor.

FIG. 7 shows the detailed structure of the input pen 60, in which a core body 63 of a ballpoint pen or the like is inserted into a pen shaft 62 made of a non-metallic material such as synthetic resin from near its tip. Ferrite core 64 with a through hole that can be freely accommodated
, a coil spring 65 , and a switch 611 . A coil 612 .wound around the ferrite core 64 . capacitor 6
A tuning circuit 61 consisting of an 18.degree.

The capacitor 613 and the variable capacitor 815 are
As shown in FIG. 8, they are connected in parallel to each other, and both ends thereof are connected to a coil 612, forming a well-known parallel resonant circuit. In addition, the coil 812 and the capacitor 6
13 and the variable capacitor 615 are selected to resonate (synchronize) with the frequency of the radio waves transmitted from each loop coil of the position detection section 4.

On the other hand, a capacitor 814 is connected to both ends of the coil 812 via a switch 811, and when the switch 611 is turned on, it acts to delay the phase of the current in the parallel resonant circuit described above by a predetermined angle.

Note that when the switch ett pushes the tip of the core 63 into the pen barrel 62 by pressing the tip of the core 63 against the input surface (not shown) of the position detection unit 4, the coil spring 65 is activated by the rear end. It is turned on by being pressed through the switch.

The processing device 70 controls switching of each loop coil and calculates designated coordinate values based on a transmission/reception switching signal described later and the output of the receiving circuit 50.

Next, the operation will be described. First, the manner in which radio waves are transmitted and received between the position detecting section 4 and the input vent 60, and the signal to be ablated will be described with reference to FIG.

In the transmitting circuit 40, a clock pulse of, for example, 4 MHz generated by the oscillator 41 is divided into 1/4 by the frequency divider 42.
, 1/8 and 1/256.

One input terminal of the Nant gate 43 receives a 500kHz pulse signal A divided by l18, and the other input terminal receives a 15.825kHz pulse signal A divided by 1/256.
The transmission/reception switching signal B of
The signal C is a signal that may or may not emit a Hz pulse signal.

The signal C is converted into a balanced signal by the drive circuit 46, and is further sent to one loop coil, for example Ci, of the position detection section 4 via the connection switching circuit 30 and the selection circuit 20. The coil Ci generates radio waves based on the signal C.

At this time, if the input pen 60 is held in a substantially upright state near the loop coil Ci of the position detection section 4, the radio wave excites the coil 612 of the input pen 60, and its tuning circuit 61
An induced voltage synchronized with the signal C is generated.

Thereafter, when the signal C enters a no-signal period, that is, a reception period, and the loop coil Ci is switched to the reception circuit 50 side, the radio waves from the loop coil Ci disappear immediately, but the tuning circuit 61 of the input pen 60 Since there is no circuit change in , the induced voltage gradually attenuates.

On the other hand, the coil 612 generates radio waves by the current flowing through the tuned circuit 61 based on the induced voltage. Since the radio wave reversely excites the loop coil Ci connected to the receiving circuit 50, an induced voltage E is generated in the loop coil Ci.

Since the connection switching circuit 30 is switched by the transmission/reception switching signal B, it accepts the signal from the loop coil Ci only during the transmission stop period. The received signal E is sent to the amplifier 5
1 and becomes a signal F, which is further amplified by phase detector 5
Sent on 2.53.

The pulse signal A is input as a detection signal to the phase detector 52, and at this time, if the phase of the received signal F matches the phase of the pulse signal A, the received signal F has just been inverted to the positive side. Outputs signal G. The signal G is converted into a flat signal H of voltage VH by a low-pass filter 54 having a sufficiently low cutoff frequency, and is sent to a processing device 70.

Further, the phase detector 53 receives a pulse signal A having the same frequency as the pulse signal A and having a phase delayed by 90 degrees, which is generated by inputting the pulse signal A and a pulse signal having twice the frequency to the EXOR gate 45. - (not shown) is input as a detection signal. At this time, if the phase of the received signal F matches the phase of the pulse signal A', a signal I that is exactly the negative inverted version of the received signal F is output. The signal I
is the voltage -V at the low-pass filter 55 whose cut-off frequency is sufficiently low.
J is converted into a flat signal J and sent to the processing device 70.

Here, when the switch 611 is off in the input vent 60, the phases of the voltage and current at the resonant frequency of the tuned circuit 61 match as described above, and therefore, the received signal F and the pulse signal A The phases of are matched. At this time, a voltage appears only in the signal H, and no voltage appears in the signal J.

Furthermore, when the switch 811 is on in the input vent 60, the phase of the current at the resonant frequency of the tuned circuit 61 is delayed by a predetermined angle with respect to the phase of the voltage, as described above, and therefore, the received signal F The phase of the pulse signal A is also delayed by a predetermined angle with respect to the phase of the pulse signal A. Then,
At this time, a voltage appears in both signals H and J (note that if the phase delay at this time is 90 degrees, a voltage will appear only in signal J).

The signals H and J sent to the processing device 70 are converted into digital signals, and are further expressed by the following equation (1),
The calculation process shown in (2) is performed.

V − (VH + VJ 2) '/” ...-
...(1)V-tan-' (VJ/VH)
--(2) θ Here, the voltage Vx shows a value proportional to the distance between the input vent 60 and the loop coil Ci. Further, the voltage V indicates a value proportional to the phase difference between the voltage and current in the tuning circuit 61 of the input vent 60.

The value of the voltage (2) changes when the loop coil Ci that transmits and receives radio waves to and from the input valve 60 is switched, and the position of the input valve 60 is detected from this point as described later.

The voltage V. Since the value of V changes only depending on whether the switch 811 is turned on or off, the voltage V. By comparing the voltage with a predetermined threshold voltage, whether the switch 611 is on or off is identified.

Next, the state of position detection in the apparatus of the present invention will be explained according to FIGS. 10 to 12.

First, when the entire device is powered on and enters the measurement start state, the processing device 70 moves the loop coil C1-
Information for selecting the first loop coil C1 from C48 is sent to the selection circuit 20, and the loop coil CI is connected to the connection switching circuit 30.

The connection switching circuit 30 connects the loop coil C1 to the transmission circuit 40 and the reception circuit 5 based on the transmission/reception switching signal B described above.
Switching control is performed alternately to 0.

At this time, the transmitting circuit 40 sends 16 pulse signals of 500 kHz as shown in FIG. 10(a) to the loop coil C1 during a 32 μsec transmission period. The switching between transmission and reception is repeated seven times for one loop coil, here C1, as shown in FIG. 10(b). These seven transmission and reception repetition periods correspond to one loop coil selection period (448 μsec).

At the output of the phase detectors 52 and 53 of the receiving circuit 50, induced voltages are obtained for one loop coil every seven reception periods, and these induced voltages are passed through the low-pass filters 54.53 as described above. The signals are averaged at 55 and sent to a processing device 70. The two induced voltages are converted by the processing device 70 into a detected voltage Vx which is proportional to the distance between the input valve 60 and the loop coil C1 (+'), and are stored at -.

Next, the processing device 70 sends information for selecting the loop coil CI to the selection circuit 20, connects the loop coil C2 to the connection switching circuit 30, and generates a detection voltage vX□ proportional to the distance between the input vent 60 and the loop coil C2. After that, the loop coils 03 to C48 are sequentially connected to the connection switching circuit 30 in the same way, and the distance between each loop coil and the input bend 60 is proportional to the distance as shown in FIG. 10(C). detected voltage V
X1 to V (however, only a part of them is shown in FIG. 10(e)) is stored.

The actual detected voltage is as shown in FIG.
Detection voltage Va-Vg is generated only in several loop coils before and after the position (xp) where is placed as the center.

When the voltage values of the stored detection voltages are above a certain detection level, the processing device 70 calculates coordinate values representing the position of the input ben 60 from these voltage values, and transfers the coordinate values to a storage section (not shown).

When the first position detection is completed in this way, the processing device 70 detects a certain number of loop coils, for example, 10, around the loop coil from which the maximum detected voltage is obtained among the loop coils C1 to C4g. Information for selecting only the loop coil is sent to the selection circuit 20, a detection voltage is obtained in the same manner as described above, position detection is performed, and the obtained coordinate values are transferred to the storage section and the values are updated.

On the other hand, the processing device 70 calculates a detection voltage V which is proportional to the phase difference between the voltage and current at 4B in the tuning circuit 61 of the input vent 60, together with the detection voltages vx1 to V, and calculates the detection voltage V. is constantly compared with a predetermined threshold θ voltage. Therefore, at this time, when the switch 611 of the input pen 60 is turned on, the processing device 70 detects this from the comparison result and sends the coordinate value at this point as an input value to another computer, etc. (not shown).

FIG. 12 shows the timing of the second and subsequent detection operations in the processing device 70. In addition, in the figure, level check means checking whether the maximum value of the detection voltage has reached the detection level and which loop coil has the maximum detection voltage, and checking whether the detection level has been reached. If not, the coordinate calculation is stopped, and the center of the loop coil to be selected in the next detection operation is set.

Each coordinate value detected in this manner is displayed on the liquid crystal display panel 5 under the control of the display control circuit 8 each time it is detected.

FIG. 13 shows details of the display control circuit 8. Position data consisting of X-direction data and Y-direction data sequentially instructed by the position detection section 4 is sent to the computer 9.
After being input into the display memory 81, the position data is arranged and stored in a certain order, and the position data is sent to the controller, which is a display processor.
are read out sequentially by timing pulses from 82
It is output to a direction driver 83 and a Y direction driver 84.

Furthermore, scanning pulses generated by a scanning pulse generator 85 are inputted to these X-direction drivers 83 and Y-direction drivers 84 in synchronization with the timing pulses of the controller 82, and each driver 83, 84 causes the display panel 5 to receive the above-mentioned scanning pulses. One piece of data in the X direction and the Y direction is input, and accordingly, the position specified on the position detection section 4 is displayed at the same position on the display panel 5. That is,
The handwriting of characters and figures written with the input pen 60 from above the display panel 5 overlaid on the position detection unit 4 is displayed in the same handwriting on the display panel 5 by optical display. Therefore, if a character editing device is provided between the display panel 5 and the computer 9, the characters input on the position detection unit 4 can be corrected and displayed on the display panel 5, and the text can be edited such as additions and deletions. It becomes possible.

(Effects of the Invention) As explained above, according to the present invention, radio waves are transmitted from the loop coil of the position detection unit to the position indicator having a tuned circuit, and radio waves are transmitted from the tuned circuit in the opposite direction. The specified position of the position indicator is detected by receiving the signal in the loop coil and detecting the induced voltage generated at this time, so it is only necessary to provide a tuning circuit on the position indicator side, eliminating the need for a cord. In addition, heavy parts such as batteries and magnets are not required, and operability is improved accordingly. In addition, since no special parts are required for the position detection unit,
It can be made larger and can be applied to electronic whiteboards, etc. Since the designated position of the position indicator is displayed with the same coordinates on the coordinate display, it is possible to input the coordinates while visually confirming the locus of the position indicator.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a position detection device showing an embodiment of the present invention, Fig. 2 is a sectional view of an input/output cover panel, Fig. 3 is a block diagram of a control device, and Fig. 4 is a position detection control circuit and position detection. Figure 5 is a diagram showing the overall configuration of the position detection control circuit and position detection unit, Figure 6 is a diagram showing the detailed configuration of the transmitting circuit and receiving circuit, and Figure 7 is a diagram showing the specific configuration of the input pen. 8 is a diagram showing the configuration of the tuning circuit, FIG. 9 is a waveform diagram of each part of FIG. 6, FIG. 10 is a timing diagram showing the basic detection operation in the present invention, and FIG. FIG. 12 is a timing diagram showing detection voltages obtained from each loop coil during the first detection operation, FIG. 12 is a timing chart showing the second and subsequent detection operations, and FIG. 13 is a display control circuit diagram. 4... Position detection unit, 5... Liquid crystal display panel, Cl-C48... Loop coil, 20... Selection circuit, 30... Connection switching circuit, 40... Transmission circuit, 5
0... Receiving circuit, 60... Position indicator, 61...
Tuning circuit, fill... switch, 70... processing device, 4X... X direction position detector, 4Y... Y direction position detector.

Claims (2)

[Claims] (1) An X-direction and a Y-direction position detection unit formed by arranging a plurality of loop coils in parallel in the X-direction and a Y-direction, respectively;
X to sequentially select one loop coil in the direction and Y direction
and a transmission circuit that generates an AC signal of a predetermined frequency to be supplied to the loop coils in the X and Y directions; a receiving circuit that detects an induced voltage having approximately the same frequency as an AC signal; and connection switching in the X and Y directions that alternately connects the selected loop coils in the X and Y directions to the transmitting circuit and the receiving circuit. a position indicator having a tuning circuit that includes a coil and a capacitor and is tuned to radio waves generated by the loop coils in the X and Y directions to which the AC signal is supplied; and each of the loop coils in the X and Y directions. a processing device that determines the designated position of the position indicator in the X and Y directions from the induced voltage generated in the position; A position detection device comprising a coordinate display display that displays data at the specified position using common coordinates. (2) Using a position indicator that has a tuned circuit that changes the phase of voltage and current based on the operation of a switch, etc., the state of the switch, etc. in the position indicator is determined based on the phase of the induced voltage detected by the receiving circuit. 2. The position detection device according to claim 1, wherein the position detection device is configured to detect.