JPS61292732A - Coordinate input device - Google Patents

Abstract

PURPOSE:To prevent the breakage due to the excessive force to be applied to a coordinate input device which detects the component of force at each support point of a panel by a distortion gauge, by protecting a component distortion converting member consisting of a plastic post with a metallic protecting member. CONSTITUTION:The component of force produced when a point of a panel 20 is pushed by a finger, etc. is applied to a component distortion converting member 40 consisting of a plastic post via the protecting members 21 and metallic member 41 of the component detecting part 30 provided at four corners of a substrate 10. The distortion produced by the component of force are detected by distortion gauges 42 and 43. Then the coordinate input value is decided by the distribution of components of force at each support part. Here the member 40 is compressed with input of the excessive force. Thus the breakage of the part 30 is prevented by a contact secured between the metallic protecting member 21 at the side of the panel 20 and a cylindrical protecting member 31 fixed to the substrate 10 via a fixing nut 32.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a transparent panel attached above a display surface, and an operator's instruction inputted by pressing a point on the panel with a finger or the like according to instructions on the display. This relates to a useless coordinate input device t.

[Conventional technology]

Conventional devices of this type include those that detect the interruption of parallel light beams emitted parallel to the X and Y axes, those that utilize electromagnetic induction, and those that utilize surface acoustic waves.

There are methods that utilize membrane resistance, methods that use a matrix to detect contact between crossing parallel conducting wires, and methods that use mechanical force using rigid body mechanics. Among the various proposals, the mechanical type is superior in terms of simplicity of structure and ease of panel selection. In this mechanical power type, Japanese Patent Publication No. 49-34247,
Japanese Unexamined Patent Publication No. 59-225439 has been proposed.

[Problem that the invention seeks to solve]

In all of these, the component of force applied to one point on the panel surface is converted into the deflection of the leaf spring, and the K is designed to detect the amount of distortion of the leaf spring, so the contact position between the panel surface and the leaf spring is (
The disadvantage is that the position of the substantive support point changes, causing a systematic error in the detected value.1.The input device described above is different from a relatively well-maintained environment such as an office, and is not used in a relatively well-maintained environment such as an office. When used by a specific number of people, it is inevitable that it will withstand rough and rough input operations intentionally or inadvertently by those users.
No proposals to date have targeted these areas.

This invention has been made in consideration of the above points, and does not have the problems seen with mechanical force types using leaf springs, and can prevent damage to the device due to excessive force input, making it suitable for use on the street. The object of the present invention is to provide a coordinate input device that can withstand heavy use.

[Means for solving problems]

In the coordinate input device according to the present invention, the component force strain converting member that converts the component force at each support point of three or more points into strain is a column made of plastic, and the compression applied to the component force strain converting member is made of plastic. It is equipped with a cup gauge that detects each strain.

[Effect]

According to this invention, when an input is applied by pressing the panel board, each force component strain converting member of the column made of plastic converts the component force at each support point into strain.

This strain is detected by each strain gauge, and the pressed input point is detected.

〔Example〕

FIG. 7 is a diagram for explaining the principle of mechanical coordinate detection, and 2Q indicates a panel board. According to mechanics, the force F acting on a rigid body and the position vector rl K of the point of action of this F
It is known that a rigid body can be balanced if a quintic equation holds. (c, f.

Kyoritsu Shuppansha Physics Formula In particular, when F is a parallel force, II +1)
The formula is F, VC perpendicular plane seat! 1A(x,y), it can be expressed as follows.

Here, F, = I F, I, and xIa'It
are the Cx, y) coordinate values of F.

Now, regarding one point (and its coordinates (:t(syt)K) on the panel board 20 supported at n points, the following equation holds true.

From this equation, the coordinate value (xp+7-) of one point on the surface of the panel board 20 to which force F is applied is expressed as the coordinate value of n support points ("l=
#Yl) and the reaction force f applied to the support point.

It can be obtained from K as follows.

Here, the following consideration can be made regarding the number nK of support points. Geometrically, three or more points are required for K to determine the panel surface as a plane. By the way, if the number of support points is more than 3 points (
In this case, it is necessary to adjust the height of the support point to make the detection surface flat, and the reaction force per support point is small (as a result, the reaction force detection output level by strain gauges etc. decreases and approaches the noise level). However, in the case where the panel board 20 is supported by three points, if a force is applied to the inside of the triangle to be manufactured by the three points, each point will be damaged. The component force at the support point becomes a compressive force, but when a force is applied to the outside of the triangle, the pressure on the side opposite to the force application point is applied to the straight line formed by the two support points near the force application point. Since the component force is on the tensile side, the component force detection unit at the support point must be configured to detect both compressive and tensile stress.When supporting at 63 points, component force detection at the support point K is only on the compression side, and the force application range is 3
It has to be limited to the triangular shape formed by the support points, which has the drawback of increasing the size of the device compared to the rectangular shape of the panel board 20 that is normally used. On the other hand, this invention, which targets the compressive force at each support point, can easily be applied to a general rectangular panel, and in the following explanation, the number of support points will be four. do.

Fig. 8(a) is a diagram for explaining coordinate detection in the eldest-shaped panel, with the diagonal edge connecting support points a, b, e, and d as the coordinate axis, and the intersection point as the coordinate origin 0 (0, 0). , panel board 2 with the long sides of the rectangle created by the support points added.
The coordinates (Xp *y,) of a point on the 0 plane are determined as follows.

Now, let's change the coordinate system to a coordinate system (x
, y) After VC conversion, equation (5) becomes K as shown in the following equation.
Become. (FIG. 8(b)) FIG. 1 is a perspective view showing an embodiment of the present invention, in which 10 is a substrate, 2G is a panel board, 30 is a component force detection section,
They are provided at the four corners of the substrate 10.

Based on the operator's operation instructions from a display (not shown) installed below the panel board 2G.

An input is made by pressing a point on the surface of the panel board 20 above the display with a finger or the like, and this input position is determined from the strain gauge output of the component force detection section 30 placed at four support points VC.

FIG. 4 shows details of the configuration of the component force detection section 3a.

In FIG. 4, reference numeral 31 designates a cylindrical protection member, with screws 32 and 33 formed on the outer and inner peripheries, and 34 a fixing nut. (The S material 31 is fixed to the substrate 10 by screwing the screw 32 on its outer periphery into the screw hole 1 of the substrate 10 and tightening the fixing nut 34 fitted with the screw 32 at 554 degrees. Reference numeral 35 designates a receiver member, which has a screw 36 on its outer periphery and is screwed into the screw 33 of the protection member 31. 37, 38, and 39 are spacers, all of which have approximately the same outer diameter, and spacer 3
9 is the inner diameter of another spacer 37. ．． 31) It is formed larger.

Reference numeral 40 denotes a force strain converting member, which passes through each of the spacers 37 to 39, and its bottom surface is supported by the member 35. A metal member 41 is attached to the top of the component force strain conversion member 40,
In addition, at a portion of the component force strain converting member 40 located within the spacer 39, a strain gauge 42.4 is provided that converts the strain converted from the component force f of the force F into an electrical resistance change.
3 is attached, each lead @44, 45 is molded into the spacer 38, and the end is led out.

Further, a protection member 21 is attached to the lower surface of the panel board 20 with an adhesive or the like, and protects the panel board 20 by contact with the component force strain converting member 40.

Note that the strain gauges 42 and 43 may be molded onto the component force strain converting member 41.

2 is a side view of FIG. 1, and FIG. 3 is a top view of FIG. 1, with the panel board 20 removed.

Four cylindrical force detectors 30 are attached to the substrate 10, and the component force detectors 30 are arranged so that they are in contact with the surface of the panel board 20 with approximately equal compressive stress (depending on the panel's own weight, etc.). ing.

FIG. 5 shows an example of a processing circuit for the outputs of the strain gauges 42 and 43 of the component force detection section 30. Strain gauges 42 and 43
are a set of strain gauges (referred to as R1 to Rd), which are provided in each component force detection section 30. 54 is a multiplexer, 55 is an A/D converter, 60 is a control unit, and I10 Hanwha 61, 62 . Memory 63. C.P.
cRo comprised of the U6i bus 65 is a resistor.

Also, vI is the input voltage, vo is the voltage across the resistor R6, FPffilm is the minimum value of the input pressure,
4 represents the output of each strain gauge set R1 to R, and the operation will be explained next. The difference between the outputs of the strain gauges R, R4e, R1, and Ro at the diagonal support points of the panel board 200 is amplified by operational amplifiers 51, 52, and input to the multiplexer 54. Also, the strain gauges R1 to R4
The changes in the outputs from the initial values are added by the operational amplifier 53VC and input to the multiplexer 54. The multiplexer 54 follows instructions from the control unit 60.
One of the inputs is connected to an A/D converter 55.

The A/D converter 55 converts the input measurement data into digital values and outputs the digital values according to instructions from the control section 60. The system #s60 calculates the coordinates *Cx, yp) of the input point from this digital output using equation 00) obtained by converting equation (6) described below. An example of the data processing procedure of the control unit 60 is shown in FIG.

The processing contents of this circuit will be explained below.

Now, it is assumed that the strain gauges 42 and 43 of each component force detection unit 30 and the component force strain conversion member 40 are equal, and the strain gauges 42 and 4
Converting equation (6) using equation (7), which is the conversion equation in step 3, we get: Here, R1 is the electrical resistance value of the strain gauges 42 and 43 at each support point, and Ro is the value of R. The reference value, S is the cross-sectional area of the component force strain converting member 40, E is the longitudinal elastic modulus of the component force strain converting member 40, and the coordinates (
xpr Yp) becomes 5 as shown in the following equation.

this! Now, in the circuit shown in Fig. 5, the input voltages from the strain gauges 81 to R- to the operational amplifiers 51 and 52 are as follows: =R, -I,
・・・・・・・・・・・・・・・・・・・・・・・・
...(Since it is off, Vo ” R6・■.
Equation (10) becomes as follows.

As described above, it can be seen that the locus II (X, #y,) of the input instruction point can be found using the circuit shown in FIG.

Incidentally, although a constant current power supply is used here for convenience of explanation, similar results can be obtained even if a constant voltage power supply is used, although some approximations are required.

Also, as you can see from equation 10, Xp e Yp
The formula for calculating " is the linear formula for the output voltages of the strain gauges 42 and 43, divided by 5. Therefore, distortion game 942
．． The influence of the temperature characteristics of 43 on the detected coordinate values is canceled out by the numerator and denominator, and highly accurate results can be obtained.

(2) Now, when a force F is applied to the panel board 20, the component force detector 30 is compressed by the compression components f and K. If the component force strain converting section and the material 40 are made of plastic, the amount of compressive strain of the component force detecting section 30 will be approximately equal to that of the component force strain converting member 40.
The amount of distortion is The effective measurement length of the strain gauges 42 and 43 attached to the component force strain conversion member 40 is l, and the component force strain conversion member 40
Let S be the cross-sectional area and E be the longitudinal elastic modulus, then component force detection unit 3
The compressive strain amount Δl of 0 is given by the following equation.

−t Δl=−1”−・・・・old・・・・n1・・・・(12
)-E Now, considering that f, /S is the compressive stress σ1 applied to the component force strain conversion member 40, Δig・-1・
・・・・・・・・・・・・・・・ Song (137) Make the converted output thicker (k is l or (σ, /E) should be made larger.

Therefore, it is necessary to increase the value of (σ, /E) for the same strain gauge. by the way.

σ1 becomes thicker (
However, it cannot be made larger than the compressive yield stress σa. Therefore, by using a large value (σ, /E), the conversion output can be made thicker.

Conventionally, the value of (σa/E) for metals often used for stress-strain conversion is relatively small, as shown in Table 1. It was necessary to make it big. On the other hand, for plastics, the value of K(σ, /E) is relatively large, as shown in Table 2, so the compressive component force can be directly detected without using conversion means that cause errors, such as leaf springs. (It's worth it.

Table 1 Table 2■ Next, K, if the maximum value of the component force of the force applied to the panel plate 2GVC is 'l (wax) and the length of the 1-component force strain conversion member 4G is L, then the component force strain conversion member 40 The amount of strain ΔL compressed by component force is determined by the following equation.

Here, if fB□8〆S is larger than the compressive yield stress σa of the component force strain converting member 40, the component force strain converting member 40 will yield, making detection of the component force difficult.

Now, if the protection member j is placed near the component force detection unit 300 and the amount by which the one component force detection unit 30 protrudes from the panel side surface of the protection member 31 toward the panel side is ΔD, then when ΔL>ΔD The protection member 31 supports the panel board 20 and can protect the 1-minute force detection section 30 from destruction. By the way, in this case, the value of ΔD may be as follows from the 64th formula.

■Next, it is better to make the contact area between the panel plate 20 and the component force detector 30 as small as possible, because if the coordinates of the 1 component force detector 30 are made highly accurate, the yield stress will be small, which will go against this condition. That will happen. In this case, this can be avoided by bonding a metal member with a large yield stress to the panel plate 20 side of the component force strain converting member 40.
Accuracy can be improved.

On the other hand, due to the application of force F to the contact portion between the panel plate 20 and the component force detection unit 30, the panel plate 20 bends slightly (which changes from the intended contact condition). is likely to be deformed by being subjected to a stress greater than the yield stress. Therefore, by attaching a protective member 31 made of metal to the side of the panel plate 20 that contacts the component force detection section 30, the deformation of the panel plate 20 is prevented. Here, the area of the protective member 31 is S9, and the maximum value of the force component applied to the panel board 20 is f.
l(+max)' If the yield stress of the panel board 20 is σa, then it is necessary to satisfy the following equation.

■ Since the amount of adjustment of ΔD mentioned in (■) is minute, the protective member 31 is made into a cylindrical shape, and the screw 33 is inserted into the inner surface of the protective member 31.
By moving the member 35 back and forth, the receiver can adjust ΔD with high accuracy.

■ Also, since the surface of the panel board 20 is generally not perfectly flat, the protective member 31 is made into a cylindrical shape, and a screw 32 is attached to the outer surface of the protective member 31. By fixing, it is possible to make the contact between the panel plate 20 and the component force detection section 30 at each support point equal, so that the component force detection 83G receives the correct component force.

〔Effect of the invention〕

As explained above, this invention has three parts that support the panel board.
Each component force strain converting member of the component force detecting section installed at a support point or more is made of a column made of plastic, and each component force strain converting member is provided with a strain gauge. !
Since the coordinates of the designated input position can be detected relatively close to the IC, highly accurate coordinate input is possible. Moreover, the device provided with the protective member can withstand excessive input, and has the advantage that it can be used on the street where it is subjected to relatively rough handling.

[Brief explanation of drawings]

1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a side view of the embodiment shown in FIG. 1, and FIG. 3 is a side view of the embodiment shown in FIG. 1, with the panel removed. 4 is an enlarged view of the configuration of the main part of the present invention, FIG. 5 is a diagram showing an example of a processing circuit for the output from the strain gauge of the component force detector, and FIG. Flowchart showing the data processing procedure for determining coordinates performed by the control unit of
The figure shows a force F applied to one point on the panel surface supported at n points,
Diagram for explaining the principle of determining the coordinates of that single point, No. 8
Figure 8(b) is an explanatory diagram of a rectangular panel supported at four points with the diagonal line as the coordinate axis and the intersection of the diagonal lines as the coordinate origin. Figure 8(b) shows the coordinate system of Figure 8(a) It is an explanatory diagram for performing a coordinate system transformation with the origin at the upper left of the panel. In the figure, 10 is a board, 20 is a panel board, 30 is a component force detection section, 31 is a protection member, and 40 is a component force strain conversion member. , 41
is a metal member, and 42.43 is a strain gauge. Figure 1 Figure 2 U 31: Protection N-n material Figure 4 Figure 6 Figure 7 Diagram O Figure 8

Claims (6)

[Claims] (1) Detect the component force of the force applied to one point on the board surface of the panel board at three or more support points that support the panel board on the board, and determine the coordinates of the point where the force was applied. In the coordinate input device equipped with a detection unit, the component force strain conversion member of the component force detection unit that converts the component force into strain at each of the support points is a column made of plastic, and the component force strain conversion member applied to these component force strain conversion members is A coordinate input device characterized in that each of the component force strain conversion members is provided with a strain gauge for detecting compressive strain. (2) Claims characterized in that the component force detection section includes a protective member made of metal for protecting the component force detection section by limiting the amount of compressive strain caused by the component force to a certain value or less. No. (
Coordinate input device described in section 1). (3) The coordinate input device according to claim (1), wherein the component force strain converting member includes a metal member on a side that contacts the plate surface of the panel plate. (4) The coordinate input device according to claim (1), wherein the panel plate is provided with a protective member made of metal at a portion that comes into contact with the component force detection section. (5) The protection member of the component force detection section has a cylindrical shape that surrounds the component force strain conversion member and the strain gauge, and has a thread cut on its inner surface, and the screw protects the component force strain conversion member and the strain gauge. 2. A coordinate input device according to claim 2, further comprising a component force detection portion receiving member that can move forward and backward inside the coordinate input device. (6) The protection member of the component force detection unit is cylindrical and surrounds the component force strain conversion member and the strain gauge, and a thread is cut on its outer surface, and this screw allows the cylindrical protection member to advance and retreat with respect to the board. The coordinate input device according to claim (2), characterized in that the coordinate input device is configured to be able to perform the following operations.