JPH0844482A - Coordinate input device - Google Patents

Abstract

PURPOSE:To provide a coordinate input device capable of preventing the generation of an electromagnetic noise, suppressing the influence of an electromagnetic noise generated on the external or in an internal circuit of its own device, improving detection accuracy, detecting pen pressure, and executing operation by low current consumption and a low cost. CONSTITUTION:Plane members 2 to which plural stripe-like magnetic resistance element patterns 3 are stuck respectively along X and Y coordinate axes are arranged through a spacer 11 so that respective patterns 3 are mutually opposed, coordinates are inputted to the user plane member 2 by a pen 1 fixing a magnetic substance on its tip and the coordinates inputted by the pen 1 are detected through output changes in the patterns 3 along the X and Y axes. Each plane member 2 is formed of a transparent material, a display part 9 of a computer 8 is arranged under the coordinate input part so that the display part 9 can be observed through the members 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device, and more particularly to a coordinate input device for detecting a two-dimensional coordinate value and inputting it to a computer or the like.

[0002]

2. Description of the Related Art In recent years, personal computers and LCDs
With the reduction in power consumption and the reduction in size and thickness of (liquid crystal display devices),
A pen input computer without a keyboard has appeared. This kind of device is opening up a new field in the computer market with its usability and portability as a weapon, and in the future, it is expected as a tool in the paperless era replacing notebooks and notebooks.

This type of device has a device for detecting pen input. Conventionally, as a coordinate input technology, an electromagnetic coupling method, an electrostatic capacity method, a resistance film method, and an ultrasonic method are known.

FIG. 8 and FIG. 9 show the structure of an electromagnetic coupling type coordinate input device as an example of a conventional example. FIG. 8 shows a schematic configuration of a pen computer having an electromagnetically coupled coordinate input device.

As shown in FIG. 8, the device comprises a tablet / LCD unit 100 which is an input / display unit and a printed circuit board unit 200 which is an arithmetic processing / interface unit. The printed circuit board section 200 is reinforced by the lower case 300. Since the tablet / LCD unit 100 is configured by overlapping the input unit on the display surface of the LCD, a computer without a keyboard and having excellent portability can be configured.

The printed circuit board portion 200 includes an input connector of the AC adapter 400, a battery 210, and an inverter 2.
11, a power supply unit such as the DC-DC converter 212, a logic circuit unit 220 for performing arithmetic processing, an IC card 230
Interface part 24
It consists of 0 and so on. The interface cable 5 is provided between the tablet / LCD unit 100 and the printed circuit board unit 200.
00 for connection.

FIG. 9 illustrates the detection principle when the tablet of the tablet / LCD unit 100 is constructed by the electromagnetic coupling method. Loop antenna group 101 on the tablet surface
Are arranged in large numbers, and this loop antenna group 101
Is three loop coils X1, X2, X3 for detecting the X coordinate
And three loop coils Y1, Y2, Y3 for Y coordinate detection
Composed of and.

On the other hand, a transmission / reception coil 102 is embedded in the tip of the electronic pen to form a resonance circuit composed of a coil and a capacitor. The electronic pen only has this resonance circuit and does not have a built-in battery.

In such a configuration, when a signal matching the resonance frequency of the transmitting / receiving coil 102 of the electronic pen is input to the loop antenna group 101 from the high frequency signal sources 103 and 104, an electromagnetic wave matching the resonance frequency of the electronic pen is loop antenna. Emitted from.

The transmission / reception coil 102 of the electronic pen resonates and stores electromagnetic energy. At the next moment, the loop antenna group on the tablet is connected to the receiving circuits 105 and 106, switches to the receiving state, and detects the electromagnetic wave emitted from the transmitting / receiving coil 102. The coils X1 to X3 and Y1 to Y3 are used in time division during the above transmission and reception, and the position of the pen tip can be obtained from the intensity distribution of the detection signals of these loop coils.

[0011]

As described above,
An electromagnetically coupled pen input tablet is a wireless station composed of multiple loop antennas. Therefore, it is difficult to avoid the problem of radiating electromagnetic noise to the outside, and as shown by the dashed arrow in FIG.
There is a problem that the detection accuracy is affected by the near magnetic field generated from the DC converter 212 and the logic circuit unit 220.
Further, there is a problem that the housing shield disturbs the electromagnetic waves transmitted and received between the loop antenna 101 and the transmission / reception coil 102 inside the electronic pen.

Further, the electromagnetic coupling method uses a high frequency circuit, and therefore consumes a large amount of current, and if the control circuit is included, the cost is relatively high.

Other coordinate input methods include a resistance film method and an electrostatic capacity method. However, the electrostatic capacity method uses a high frequency circuit like the electromagnetic coupling method, and therefore consumes a large amount of current and causes a cost problem. is there.

The resistance film method consumes less current and is inexpensive, but has a problem that the detection accuracy is reduced by one digit as compared with the electromagnetic coupling method and the capacitance method. Further, the electrostatic capacitance method and the resistance film method have a problem that the writing pressure cannot be detected.

The object of the present invention is to solve the above problems, to generate no electromagnetic noise, and not to be affected by the electromagnetic noise of the outside or the internal circuit of the own machine, and the detection accuracy is high, and the writing pressure can be detected. It is therefore to provide a coordinate input device that can be implemented at low cost with low current consumption.

[0016]

In order to solve the above-mentioned problems, in the present invention, in a coordinate input device for detecting a two-dimensional coordinate value and inputting it into a computer or the like, the tip end for instructing the coordinate is magnetized. Pen with magnetic material
By arranging a flat member having a plurality of stripe-shaped magneto-electric conversion elements attached along each of the two coordinate axes of the dimensional coordinates and by disposing the pen tip at a desired position on the flat member, the magnetic property of the pen can be improved. A configuration including a detection circuit that detects a change in the output of the magnetoelectric conversion element by the body and calculates and outputs the input coordinates by the pen based on the detection result is adopted.

[0017]

With the above arrangement, the input coordinates of the pen can be detected through the change in the output of the magnetoelectric conversion element due to the magnetic substance of the pen.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on the embodiments shown in the drawings. The coordinate input device of the present invention performs coordinate input using a magnetoelectric conversion element such as a magnetoresistive element. An embodiment in which the coordinate input device is applied to a pen computer will be described below.

FIG. 1 shows a first embodiment of a pen computer adopting the coordinate input device of the present invention.

In this embodiment, the pen tip of the pen 1 holding the magnetic material at its tip is freely moved while being in contact with the surface of the plane member 2 to input coordinates.

The plane member 2 is transparent, and two sheets are used for detecting the X coordinate and detecting the Y coordinate, respectively. A magnetoresistive element pattern 3 is formed as a magnetoelectric conversion element on the opposing surfaces of these two planar members 2. The magnetoresistive element pattern 3 is formed by applying a magnetoresistive element material such as permalloy and then etching it in a comb shape.

A connector land pattern 4 is provided at the end of the tooth portion of the magnetoresistive element pattern 3, and when a corresponding portion of the flat member is inserted into the connector 5, the magnetoresistive element and the position detection circuit are connected. With such a configuration, assemblability is improved as compared with wire bonding and soldering of leads.

The flexible board (FP
C) 6 is drawn out and connected to a position detection circuit described later.

The coordinate input section of the computer 8 is constructed as described above. A switch 7 is provided on the upper surface of the computer 8, and the switch 7 constitutes a function key or the like, and is used for various known information processing operations.
It is for performing special operations such as resetting the origin of the coordinate system.

The size and size of the plane member 2 forming the coordinate input surface are the same as the size and size of the display unit 9 of the computer 8, and their coordinates are also the same. The input coordinate system of the pen 1 and the coordinate system of the display unit 9 are usually associated one-to-one in the coordinate detection process.

FIG. 4 shows a graph of the dependence of the electric resistance value on the change of the magnetic field strength of the magnetoresistive element which is the magnetoelectric conversion element. As shown, when a magnetic field is applied, the N pole S
The electric resistance value decreases regardless of the pole and saturates at a certain strength of the external magnetic field.

That is, the magnetoresistive element has the highest electric resistance value when there is no magnetic field, and the rate of change in resistance value corresponding to the change in magnetic field is about 3 to 4%. As a typical magnetoresistive element material, there is Permalloy.

FIG. 2 shows the plane member 2 and the magnetoresistive element 3.
An example of the structure of the magnetic layer constituting the is shown. As described above, the plane member 2 is transparent, and the information displayed on the display unit 9 of the computer 8 of FIG. 1 can be viewed through the plane member 2. As the material of the plane member 2, reinforced glass such as quartz glass or plastic is most suitable.

Permalloy, which is the X-direction magnetoresistive element 301, is vapor-deposited on the upper surface of the lower planar member 2 to a thickness of about 500 angstroms, and is spaced at a constant interval in the X-axis direction, for example, 80 μm. Width (for example, 20 μm)
Are etched in stripes parallel to the Y-axis direction. With this dimension setting, a detection accuracy of 0.1 mm can be ensured. In this case, considering the magnetoresistive element as a light shielding member, the transmittance of light from the computer display unit 9 is 80.
%. On the magnetoresistive element 3, a silicon nitride layer 10 as a protective layer is vapor-deposited with a thickness of about 2 μm.

A plane member 2 for detecting the Y coordinate is obtained by rotating a similar member in a plane of 90 degrees and arranging the magnetic layer upward.
The coordinate input section is configured by stacking these two planar members 2 with the spacer 11 interposed therebetween.

In the upper right of FIG. 2, the structure of the tip of the pen 1 is shown. As shown in the figure, a magnetic body 13 is magnetized at the tip of the grip portion 15 (in this case, the pen tip is the N pole).
Is stuck.

Further, a contact portion 14 made of a non-magnetic material is provided at the tip of the grip portion 15 so as to surround the magnetic material 13. The contact portion 14 is held via the elastic member 12. The contact portion 14 protects the pen tip and applies a magnetic field according to the writing pressure to the magnetoresistive element pattern 3 of the planar member 2.
To act on.

That is, when the tip contact portion 14 of the pen 1 contacts the surface of the flat member, the electric resistance value of the magnetoresistive element 3 for detecting the coordinates of the corresponding coordinates in the X and Y directions becomes small. When the pen 1 is pushed harder, the gap between the magnetic body 13 and the contact portion 14 is reduced, and the magnetic resistance value of the magnetoresistive element is further reduced. The magnitude of this change can be detected as writing pressure information.

FIG. 5 shows an example of the position detecting circuit according to the present invention. In FIG. 5, the X and Y direction magnetoresistive elements are input to a multiplexer 16 as a switching device, and the plane member 2
The constant current source 18 is connected to one magnetoresistive element corresponding to the count value indicated by the counter 17, which is preset to a numerical value corresponding to the number of magnetoresistive elements 3. The constant current source 18 inputs to the multiplexer 16 via the reference resistance 19 and supplies a current to the magnetoresistive element.

The resistance value detection circuit 20 measures the voltage values from the ground at both ends of the reference resistance 19, Vi and Vr, and performs the following calculation to output the resistance value Ri of the magnetoresistive element.
That is, assuming that the resistance value of the reference resistor 19 is RS, Ri = V / I = Vi / ((Vr-Vi) / Rs) = Vi * RS / (Vr-Vi) The digital data of the measured resistance value is output to the device 22 and the arithmetic processing circuit 23. The voltages Vi and Vr across the reference resistor 19 are digitally converted by the AD converter when they are input to the resistance value detection circuit 20.

The data input to the RAM 21 is stored in the address corresponding to the counter 17, that is, the address corresponding to the predetermined magnetoresistive element pattern 3 on the plane member 2, and the counter value makes one round and the same address is again stored. When counting, the comparator 22 again compares the value output by the resistance value detection circuit 20 with the value output from the RAM one cycle before. On the other hand, the data input to the arithmetic processing circuit 23 is
Used to detect pen pressure.

The output characteristic of the comparator 22 is shown in FIG. As illustrated, when the current value Rt becomes smaller than the previous value Rt-1 by Rd or more, the High level is output. That is, the comparator 22 has a hysteresis of ± Rd as follows.

Low → High: Rt−Rt−1 <−Rd High → Low: Rt · Rt−1> Rd The output of the comparator 22 is input to the arithmetic processing circuit 23, and the comparator output 22 changes from Low to High level. When
The arithmetic processing circuit 23 reads the counter value and outputs the value as the position coordinate of the pen 1. The output of the comparator 22 is L
At the ow level, the output of the coordinates is canceled.

Further, as described above, the arithmetic processing circuit 23
From the output of the resistance value detection circuit 20 and the value of the RAM 21,
At the timing when the comparator output 22 changes from Low level to High level, the magnitude of the amount of change is detected and a writing pressure signal corresponding to the amount of change is output. Comparator output 22 is Low
When the level is reached, the output is canceled.

The coordinate detecting operation in the above configuration will be described below with reference to the timing chart of FIG. Figure 6
Focusing on the part indicated by the alternate long and short dash line, the counter 17 outputs the address data (10110111). The multiplexer 16 uses the (101
1011) The magnetoresistive element at the address and the constant current source 18 are connected, and the resistance value detection circuit 20 makes the resistance value 2 by a predetermined operation.
The measured value of 4 is output.

The comparator 22 compares the resistance value data at the address (10110111) before one cycle recorded in the RAM 21 with the current data which is the resistance value output 24, and detects that the resistance value has become small. , Comparison output 27 is output.

The comparator output of the arithmetic processing circuit 23 is High.
After confirming that the level has become the h level, coordinate data (10110111) is output as the coordinate data of the pen 1 until the comparator output returns to the Low level.

Further, the arithmetic processing circuit 23 measures the amount of change in resistance value before and after one cycle, and according to the amount of change, FIG.
The writing pressure value shown on the right side of is output until the comparator output returns to the Low level.

On the other hand, the RAM 21 updates the stored contents of the address (10110111) at the fall of the clock 28, that is, the rise timing of the clock output of the inverter 29 in FIG.

In this way, the points on the mesh of each magnetoresistive element are sequentially scanned, the resistance value at that point is measured, stored in the RAM 21, and the previous point on the same mesh stored in the RAM 21 is stored. Based on the comparison with the resistance value, it is determined whether or not the pen is present at that point, thereby detecting the coordinates and the writing pressure at that time.

By the above processing, the coordinates of the pen 1 can be detected, and the coordinates can be detected with the accuracy of the pattern pitch of the magnetoresistive element. Even if it is considered that the transmittance for visually recognizing the display unit 9 is about 80%, the coordinate detection accuracy of the order of 10 μm can be achieved by the dimension setting described above.

In the above structure, the current flowing through the magnetoresistive element for detecting the change in the magnetic field may be 1 mA or less, and low power consumption can be realized. Further, since there is no loop antenna or the like, it has an excellent advantage that it does not emit electromagnetic noise and is not affected by the internal circuit.

In the detection circuit of FIG. 5, all the intersections on the mesh of the magnetoresistive elements are scanned.
If the number of teeth of the magnetoresistive element increases, the detection speed may be too late. In that case, for example, one circuit is used for each of the X coordinate and the Y coordinate, and the same configuration as in FIG.
By operating these in parallel, the problem of detection speed can be solved.

Further, the coordinate detecting section shown in FIG. 2 can be configured as shown in FIG. The configuration of FIG. 3 is different from that of FIG. 2 in that the magnetoresistive elements 301 and 302 for detecting the X and Y directions are superposed on one plane member 2 via a protective layer 10 having an insulating property such as glass. That is, the protective flat member 12 is disposed on the coordinate input surface via the spacer 11 (here, unlike FIG. 2, the side surface from the y-axis direction is shown).

According to the structure shown in FIG. 3, since the XY coordinate detecting element is formed on one substrate, it is not necessary to align the two planar members with each other, and the assemblability is improved. There is an advantage that there is no variation between products in terms of coordinate detection accuracy and absolute coordinates.

Further, in the structure shown in FIG. 3, since the pen 1 is applied from the side of the protective flat member 12 to input the coordinates, the protective flat member 12 has the same size as the flat member 2 described above. Since it does not require strength and can be made thin, the change in the resistance value of the magnetoresistive element increases and the SN ratio of the signal improves,
There is an advantage that the writing pressure sensitivity is also improved.

[0052]

As is apparent from the above, according to the present invention, coordinate input is performed on a planar member having a plurality of stripe-shaped magnetoelectric conversion elements attached along each of two coordinate axes of a two-dimensional coordinate. Since it is configured to detect the input coordinate by the pen through the output change of the magnetoelectric conversion element by the magnetic body of the pen, it does not generate electromagnetic noise, and is not affected by the electromagnetic noise of the outside or the internal circuit of the own machine, It is possible to provide an excellent coordinate input device that has high detection accuracy, can detect pen pressure, and can be implemented at low cost with low current consumption.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an input unit of a coordinate input device according to the present invention.

FIG. 2 is a cross-sectional view illustrating a coordinate detection element unit of the device of FIG.

FIG. 3 is a cross-sectional view illustrating a different configuration of the coordinate detection element unit of the device of FIG.

4 is a graph illustrating the operating principle of a magnetoresistive element used in the device of FIG.

5 is a block diagram of a coordinate detection circuit used in the device of FIG.

FIG. 6 is a timing chart illustrating the coordinate detection process in FIG.

7 is a graph showing the output characteristic of the comparator 22 in FIG.

FIG. 8 is a perspective view illustrating a conventional coordinate detection input device.

FIG. 9 is a perspective view illustrating a detection principle of an electromagnetic coupling method, which is one of conventional coordinate detection methods.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 pen 2 plane member 3 magnetoresistive element pattern 4 connector land pattern 5 connector 8 computer 9 display part 12 elastic member 13 magnetic body 14 contact part 16 multiplexer 17 counter 18 constant current source 20 resistance value detection circuit 21 RAM 22 comparator 23 operation Processing circuit 301 Magnetoresistive element pattern 302 Magnetoresistive element pattern

Claims (6)

[Claims] 1. A coordinate input device for detecting a two-dimensional coordinate value and inputting it to a computer or the like, and a pen having a magnetized magnetic body at its tip for instructing the coordinate and two coordinate axes of the two-dimensional coordinate. Of a plurality of stripe-shaped magnetoelectric conversion elements along each of the above, and by disposing the pen tip at a desired position on the plane member, A coordinate input device comprising a detection circuit for detecting an output change and calculating and outputting the input coordinate by the pen based on the detection result. 2. A plurality of stripe-shaped magnetoelectric conversion elements provided along each of the two coordinate axes of the two-dimensional coordinates are arranged on the same plane member so as to intersect with each other with an insulating protective layer interposed therebetween. The coordinate input device according to claim 1, wherein: 3. The tip of the pen is brought into contact with a surface of the plane member opposite to a surface on which the magnetoelectric conversion element is arranged, or
The coordinate input device according to claim 1 or 2, wherein a protective member is provided on the plane member so that the pen does not directly contact the magnetoelectric conversion element. 4. The coordinate input device according to claim 1, wherein the magnetoelectric conversion element is a magnetoresistive element. 5. A contact portion, which is displaced by a contact pressure with a coordinate input surface, is provided outside the magnetic body at the tip of the pen, and the writing pressure at the time of input is detected through an output change of the magnetoresistive element. The coordinate input device according to any one of claims 1 to 4, which is characterized. 6. The detection circuit sequentially scans each intersection on a mesh formed by a plurality of magnetoelectric conversion elements arranged along each of two coordinate axes of a two-dimensional coordinate to measure a resistance value, The coordinate input device according to any one of claims 1 to 5, wherein the input coordinates of the pen are detected by detecting a change from the resistance value of the scanning point in the immediately preceding scan.