JPH0210443B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention detects a position specified by a position specifying magnetic generator based on a change in magnetic permeability of a magnetic body to which a magnetic field is applied by the position specifying magnetic generator. The present invention relates to a position detection device.

(Prior Art and Problems) Conventional position detection devices generate magnetostrictive vibration waves in the magnetostrictive transmission medium by applying a pulse current to a drive coil provided at one end of the magnetostrictive transmission medium or at the tip of a position indicating pen. From that point on, a processor 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 positioning pen or at one end of the magnetostrictive transmission medium, and from this time the indicated position of the positioning pen is determined. There was something that I did to calculate. Although this device has relatively good position detection accuracy, it requires a cord between the pen and the device in order to send and receive timing signals, etc. between the pen and the processor, which severely limits its handling. ,
It is susceptible to induction from other devices and may malfunction, or may even become a source of noise. Furthermore, the pen must be held perpendicular to the magnetostrictive transmission medium and very close to it. There were some problems, such as not being able to do so.

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 indicating pen made of a magnetic material such as ferrite is detected from the position of a detection line where a large induced voltage is induced. With this device, the positioning pen can be made cordless, but the resolution of the coordinate position is determined by the line spacing, and if you reduce the line spacing to increase the resolution, the signal-to-noise ratio and stability will deteriorate, and therefore the resolution will decrease. In addition, it is difficult to detect the position directly above the intersection of the drive line and the detection line, and the position indicator pen must be placed extremely close to the line, making it difficult to place thick objects on the input surface. There were some problems, such as not being able to use it by leaving it in place.

(Object of the Invention) The present invention improves these conventional drawbacks, and the magnetic generator for position designation is not connected anywhere, has good operability, is resistant to external guidance, and emits noise. Our goal is to provide a highly accurate position detection device that never fails.

(Embodiment) FIG. 1 is a partially cutaway exploded perspective view showing an embodiment of the present invention. In the figure, 10 is an X-direction position detection section, 20 is a Y-direction position detection section, 30 is a driving current source, 41 and 42 are signal selection means, such as a multiplexer, and 50 is a position designating magnetic generator, such as a bar magnet. 60 is a processing device.

The X-direction position detection section 10 includes a flat magnetic body 11, excitation lines 12a to 12i, detection lines 13a to 13h, and insulating sheets 14 and 15. The magnetic body 11 is sandwiched between insulating sheets 14 and 15.
The magnetic material 11 is preferably a material that is difficult to be magnetized even when a magnet is brought close to it, that is, has a small coercive force and has a high magnetic permeability (μ), such as an amorphous alloy or a permalloy alloy. As an amorphous amorphous alloy, for example, Fe ₇₉ B ₁₆ Si ₅ (atomic %) (coercive force
0.2e, magnetic permeability (μ) = 14000), etc. can be used. Further, although the magnetic material 11 is in the form of a flat plate (sheet), since an amorphous alloy can be manufactured into a compact material with a thickness of 20 to 50 μm, this may be used as is. Further, it is also possible to use a long magnetic material, for example, a sheet-like material in which a large number of amorphous alloys in the form of strips with a rectangular cross section or linear amorphous alloys with a circular cross section are brought close together and in close contact with each other. In this case, better results can be obtained by arranging the magnetic bodies so that the longitudinal direction of each magnetic body coincides with the position detection direction (in this case, the X direction).

Each of the excitation wires 12a to 12i is a portion disposed on the upper surface of the insulating sheet 14 (hereinafter referred to as an upper half portion).
and a portion disposed on the lower surface of the insulating sheet 15 (hereinafter referred to as the lower half) are continuous at one end thereof, and the excitation wires 12a, 12
b, 12c, 12d, 12e, 12f, 12g,
The other end of the lower half of 12h and the excitation wires 12b, 12
c, 12d, 12e, 12f, 12g, 12h,
The other end of the upper half of the excitation wire 12i is connected to the other end of the upper half of the excitation wire 12i, that is, the excitation wires 12a to 12i are connected in series, and the other end of the upper half of the excitation wire 12a and the other end of the lower half of the excitation wire 12i are connected to each other. source 30. Moreover, each excitation line 12a to 12i is directed in a direction perpendicular to the X direction,
That is, they are arranged parallel to each other at predetermined intervals along the Y direction.

Each of the detection lines 13a to 13h is located on the upper surface of the insulating sheet 14 (hereinafter referred to as the upper half).
and a portion disposed on the lower surface of the insulating sheet 15 (hereinafter referred to as the lower half) are continuous at one end thereof, and the detection lines 13a to 13h
The other ends of the upper halves are respectively connected to the multiplexer 41, and the other ends of the lower halves of the detection lines 13a to 13h are commonly grounded. In addition, each detection line 13a to 1
3h are arranged parallel to each other between each of the excitation lines 12a to 12i.

The Y-direction position detection section 20 consists of a flat magnetic body 21, excitation lines 22a to 22i, detection lines 23a to 23h, and insulating sheets 24 and 25, and its detailed structure is similar to the X direction position detection section 10. It is.
The Y-direction position detection section 20 is superimposed on the lower part of the X-direction position detection section 10 via an insulating sheet (not shown) as close as possible so that the excitation line and the detection line are orthogonal to each other (however, the structure is not shown in the drawings). For clarity, the X-direction position detection unit 10 and the Y
It is drawn apart from the direction position detection section 20. ). Further, each excitation line 22a to 22i is connected to a drive current source 30, and each detection line 23a to 23h is connected to a multiplexer 42.

The drive current source 30 constantly supplies an alternating current with a predetermined period (the alternating current here includes all of sine waves, rectangular waves, triangular waves, etc.) to the excitation lines 12a to 12i and 2.
2a to 22i. Further, the multiplexers 41 and 42 are configured to selectively send the output signals of the detection lines 13a to 13h and 23a to 23h to the processing device 60 in accordance with a control signal from the processing device 60.

In such a configuration, the detection lines 13a to 13
h and 23a to 23h are the excitation lines 12a to 1
An induced voltage is generated by electromagnetic induction based on the alternating current flowing through 2i and 22a to 22i. Since this electromagnetic induction occurs via the magnetic bodies 11 and 21, the higher the magnetic permeability of the magnetic bodies 11 and 21, the greater the voltage value of the induced voltage. Incidentally, the magnetic permeability of the magnetic bodies 11 and 21 changes greatly depending on the magnetic bias applied from the outside. The state of the change varies depending on the composition of the magnetic material, the frequency of the alternating current, the heat treatment applied to the magnetic material, etc., and is set so that it becomes maximum when a certain magnetic bias is applied, as shown in Figure 2. can do. Therefore, in this case, when a magnetic bias is applied to the magnetic bodies 11 and 21, the excitation lines 12a to 12i, 2
Detection lines 13a to 13h, 23a from 2a to 22i
The voltage induced to ~23h also increases.

Now, in FIG. 1, the position specifying bar magnet 50 is located at a distance in the X direction from the detection line 13a with its N pole facing down.
It is located on position A of the X _- direction position detection unit 10, which is separated by a distance _ys in the Y direction from Xs and the detection line 23a, and applies a magnetic bias to the extent that the magnetic permeability increases.
1 and 21.

At this time, induced voltages _V1 to _V8 as shown in FIG. 3 are generated in the detection lines 13a to 13h in the X direction.
In FIG. 3, the horizontal axis indicates coordinate positions in the X direction, where the positions of the detection lines 13a to 13h are x ₁ to x ₈ , respectively, and the vertical axis indicates voltage values.
V ₁ to _{V 8} reach their maximum values (local maximum values) directly below position A.
Since each of the voltages V ₁ /V ₈ is obtained from the multiplexer 41, if the processing device 60 calculates the X coordinate value at which the induced voltage becomes the maximum value from these, the X coordinate value x _s of the bar magnet 50 is determined. be able to.

As one of the calculation methods for determining the coordinate value x _s , the third
There is a method of approximating the waveform near the maximum value in the figure with an appropriate function and finding the coordinates of the maximum value of that function. For example, if the interval between each detection line 13a to 13h is Δx, and the coordinates from coordinate x ₃ to coordinate x ₅ in FIG. 3 are approximated by a quadratic function (indicated by a solid line in the figure), then
It can be calculated as follows. First, from the voltage and coordinate values of each detection line, V ₃ = a (x ₃ - x _s ) ² + b ... (1) V ₄ = a (x ₄ - x _s ) ² + b ... (2) V ₅ = a( _x5 − _xs ) ² +b...(3). Here, a and b are constants (a<0).

Also, x ₄ −x ₃ =Δx ……(4) x ₅ −x ₃ =2Δx ……(5). Substituting equations (4) and (5) into equations (2) and (3) and rearranging, x _s = x ₃ + Δx/2 (3V ₃ −4V ₄ +V ₅ /V ₃ −2V ₄ +V ₅ )… (6
) becomes. Therefore, the detection lines 13c, 13d, 13e
Voltages V ₃ , V ₄ , V ₅ induced in and the detection line 13c
The processing device 60 calculates the X coordinate value of the bar magnet 50 from the coordinate value x ₃ (known) by calculating equation (6). Further, even if the bar magnet 50 is moved along the Y axis, the same X coordinate value can be obtained.

Also, a third
An induced voltage similar to that shown in the figure is obtained, and the Y coordinate value _ys can be determined by the same calculation process as described above.

The magnetic field emitted from the tip of the position specifying bar magnet 50 is approximated to be emitted from a point r on the extension of the center line of the bar magnet 50, as shown in FIG. Therefore, if the input surface 100 is formed at a position corresponding to the distance from the magnetic bodies 11 and 21 to the point r, even if the bar magnets are tilted with respect to the magnetic bodies 11 and 21 (however, in the illustrated example, the two-dot chain line (This shows that the bar magnet 50 is tilted with reference to the magnetic body 11 shown in .) The direction of the magnetic field with respect to the same position of the magnetic body does not change, and the detection position also does not change.
The position can be specified without being affected by the inclination of the bar magnet 50. In experiments, the tilt was within ±30° and the error was less than ±0.5mm (height of the input surface was 12mm).
mm).

FIG. 5 shows a specific example of the drive current source 30. In the figure, numeral 31 is a function generator, for example, Intersil IC 8038, which outputs a sine wave signal of a predetermined frequency determined by the values of capacitor C and resistor R. Further, 32 is a power driver, which is composed of an operational amplifier and a current amplifier, and amplifies the current of the sine wave signal and sends it to the excitation lines 12a to 12i and 22a to 22i.

FIG. 6 is a sectional view showing a specific example of the position designating magnetic generator 50, and FIG. 7 is an electric circuit diagram thereof. In the figure, 51 is a pen-shaped container made of synthetic resin, etc., and a bar magnet 5 with a tapered tip is attached to one end of the pen-shaped container.
2 is accommodated so as to be slidable in the axial direction. Also,
Reference numeral 53 denotes an operation switch, which is attached opposite to the other end of the bar magnet 52. Further, 54 is an ultrasonic signal transmitter, 55 is an ultrasonic transmitter, and a battery 56
It is stored in a proper place in the container 51. When the tip of the bar magnet 52 that holds the container 51 and has the rubber cover 57 attached is pressed against the input surface, the bar magnet 52 slides and the switch 53 is turned on.
As a result, the oscillation circuit 54a and amplifier 54b in the transmitter 54 operate, and the transmitter 55 transmits a signal indicating the start of measurement, for example, a continuous pulse signal of a predetermined frequency, by converting it into an ultrasonic signal.

FIG. 8 is a circuit block diagram showing a specific configuration of the processing device 60. In the figure, when an ultrasonic signal indicating the start of measurement is sent out from the above-mentioned transmitter 55, the ultrasonic signal is received by a receiver 61, further amplified and waveform-shaped by a receiver 62, and then inputted. It is sent to the buffer 63. The arithmetic processing circuit 64 reads the measurement start signal from the input buffer 63, and when recognizing the start of measurement, sends a control signal to the switching circuit 66 and the multiplexer 41 via the output buffer 65 to guide the detection lines 13a to 13h in the X direction. The voltages are sequentially input to the amplifier 67. Each of the induced voltages is amplified by an amplifier 67, rectified by a detector 68, converted into a DC voltage, further converted into a digital value by an analog-digital (A/D) converter 69, and processed through an input buffer 63. The signal is sent to circuit 64. The arithmetic processing circuit 64 temporarily stores each of the induced voltages (digital values) in a memory 70,
Among these, the voltage value near the peak is detected.
This detection method involves, for example, sequentially comparing the magnitude of each induced voltage, and if a certain voltage, V _k , is larger than the immediately preceding voltage V _k-1 and larger than the next voltage V _k+1 , then (V _k-1 <V _k >V _k+1 ), voltage V _k can be detected as a peak voltage. The arithmetic processing circuit 64 takes out the voltages V _k-1 , V _k , V _k+1 and converts them into the voltages V ₃ , V 4 , V ₄ and
As _V5 , perform the arithmetic processing of equation (6) to obtain the X coordinate value.

Next, the arithmetic processing circuit 64 sends a control signal to the switching circuit 66 and the multiplexer 42 via the output buffer 65, sequentially inputs the induced voltages of the detection lines 23a to 23h in the Y direction, performs the same processing as described above, and Find the value. The X and Y coordinate values of the digital values obtained in this way are output to the output buffer 71.
to a digital display (not shown) for display, or to a computer (not shown) for processing, or for conversion to an analog signal via a digital-to-analog (D/A) converter 72. and processed.

Note that the numbers of excitation lines and detection lines in the examples are merely examples, and it goes without saying that the numbers are not limited thereto. Moreover, it has been confirmed through experiments that position detection can be performed with relatively high accuracy if the distance between the detection lines is about 2 to 6 mm. Furthermore, the magnetic generator for specifying the position is not limited to a bar magnet, and may be a plate, ring, square body, etc., or may be an electromagnet.

Further, in the embodiment, a signal indicating the start of measurement is transmitted from the position specifying ceramic generator 50 to the processing device 60.
Although ultrasonic signals have been used for transmission up to this point, optical signals such as infrared rays may also be used. Furthermore, since the signal indicating the start of measurement is simply for making the arithmetic processing circuit 64 recognize the timing of coordinate detection, it does not need to be sent from the magnetic generator 50, but rather from a keyboard or other device provided in the processing device 60 itself. The switch circuit may send a signal for recognizing the timing.

(Effects of the Invention) As explained above, according to the present invention, the X-direction and Y-direction position detection parts are formed by alternately arranging excitation lines in a flat magnetic body so as to be orthogonal to the position detection direction thereof. , a drive current source that applies an alternating current at a predetermined period to each of the excitation lines in the X and Y directions, and a position specifying source that applies a local magnetic bias to each of the magnetic bodies in the X and Y directions and is not connected anywhere. A magnetic generator, X-direction and Y-direction signal selection means connected to the X-direction and Y-direction detection lines, respectively, and the position determined from each induced voltage extracted from the X-direction and Y-direction signal selection means. Since it is equipped with a processing device that calculates the coordinate values in the X and Y directions of the specified position by the specified magnetic generator, the magnetic flux change between the excitation line and the detection line occurs only within the magnetic body, and the coupling is tight. The detection voltage is large and the SN
It has a good ratio, is less susceptible to external induction and generates less external induction noise, and the magnetic generator for position specification does not need to send timing signals etc. to the equipment side for position detection. The connection between the device and the device can be made cordless, and the cord will not break, become tangled, or become loose due to fatigue. Therefore, it is easy to operate, and the magnetic generator for position specification can be used freely. The position can be easily moved to the desired position, and the position can be specified by simply applying a slight magnetic bias to the magnetic material, so the magnetic generator for position specification does not necessarily need to be close to the tablet, and can be placed at a distance of several centimeters or more. Alternatively, an object other than a magnetic material may be interposed, and even in these cases, effects such as position detection with high resolution can be obtained.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is a partially cutaway exploded perspective view showing an embodiment of the present invention, FIG. 2 is a characteristic diagram of magnetic bias versus magnetic permeability, and FIG. 3 is a diagram showing characteristics of magnetic bias in the X direction. A graph showing an example of the induced voltage generated in each detection line, Fig. 4 is an explanatory diagram showing the magnetic flux applied to the magnetic material from the position specifying bar magnet, and Fig. 5 shows a specific example of the drive current source. Electric circuit diagram, FIG. 6 is a sectional view showing a specific example of a magnetic generator for position designation,
FIG. 7 is an electric circuit diagram thereof, and FIG. 8 is a circuit block diagram showing a specific configuration of the processing device. DESCRIPTION OF SYMBOLS 10... X direction position detection part, 20... Y direction position detection part, 30... Drive current source, 41, 42... Multiplexer, 50... Magnetic generator for position specification, 60... Processing device, 11, 21... Magnetic body, 12a ~12i,
22a-22i...Excitation line, 13a-13h, 23
a to 23h...detection line.

Claims (1)

[Claims] 1.
a drive current source that applies an alternating current at a predetermined period to each of the excitation lines in the X and Y directions; and a drive current source that applies a local magnetic bias to each of the magnetic bodies in the X and Y directions. and a magnetic generator for position designation that is not connected to anywhere; X-direction and Y-direction signal selection means connected to each of the X-direction and Y-direction detection lines, respectively; and the X-direction and Y-direction signal selection means. A position detection device comprising: a processing device that calculates coordinate values in the X direction and Y direction of the position designated by the position designation magnetic generator from each induced voltage taken out.