JPH04137026A - Contact type position detector - Google Patents

Abstract

PURPOSE: To improve the accuracy of position detection and further to improve the degree of freedom of designing the dimensions or shapes of respective parts by setting the specific resistance values across inter-electrode resistors and of feeding resistors. CONSTITUTION: Envelopes at the top end parts of respective electrodes 41-44 in respective linearity imparting regions are set so as to draw parabolas, and total sums Ra and Rb of resistance value s of respective inter-electrode resistors 51-54 in linearity imparting regions parallel to 1st and 2nd main axes are set at resistance values given by equation I and II. Besides, resistance values Rac and Rbc of feeding resistors 61-64 are set at resistance values given by equalities III and IV. In this case, in equations I-III, ρ is a resistance value per unit length and per unit width of a planar resisting members and A, Da and Db are values given by equation V-VII. Besides, X is the length of a side parallel to the 1st main axis in a detection area, Y is the lenght of a side parallel to the 2nd main axis, Ca is the width of the linearity applied area parallel to the 1st main axis, and Cb is the width of the linearity impacting regions parallel to the 2nd main axis. Thus, an equipotential line becomes a straight line along the respective sides of the detection regions.

Description

[Detailed description of the invention] Industrial Retirement ■ batch! The present invention is based on CG (Computer Graphics).
) systems and CA D (Computer Aided)
The present invention relates to a contact-type position detection device which is used as an input device in a design system, etc., and which detects a position touched by a finger or a pen-shaped member and outputs a signal according to the touched position.

Traditionally, a planar resistance member has a predetermined voltage gradient,
2. Description of the Related Art A contact position detection device is known that detects a contact position of a stylus pen or the like based on the potential of the contact position.

More specifically, as shown in FIG. 4, this type of contact-type position detection device has electrodes 2 and 3 provided on opposite sides of a rectangular sheet resistance member 1, respectively.
The principle is that when the stylus pen 11 is brought into contact with the sheet resistance member 1 while a predetermined voltage is applied to the electrode 2 and the stylus pen 11, a potential difference proportional to the distance is generated between the electrode 2 and the stylus pen 11.

In addition, the vertical and horizontal contact positions of the stylus pen 11 are determined by further providing electrodes 4 and 5, as shown in FIG.
Detection can be performed by alternately applying a voltage between electrodes 3 and 4 and 5.

By the way, as mentioned above, the electrodes 2 are placed on the four sides of the sheet resistance member 1.
5, for example, when a voltage is applied between electrodes 2 and 3, a current leaks through electrodes 4 and 5, resulting in a significant increase in power consumption. Therefore, by providing the electrodes 2 to 5 with a certain degree of resistance and connecting them as shown in FIG. 6, power consumption can be reduced. In addition, in the same figure, the connection for detecting the contact position in the X direction is omitted.

However, when the electrodes 2 to 5 are provided with resistance, a potential difference occurs, for example, from position A-B to position C, and the equipotential lines do not become straight lines as shown by the broken lines in the figure. Therefore, the detected potential difference is not proportional to the distance from the electrode 2 to the contact position, and the position detection accuracy decreases. therefore,
Calculations and corrections are required to determine the contact position based on the detected voltage, which complicates the configuration of the device.

A contact type position detection device that attempts to solve these problems is disclosed in, for example, USP 4198539,
As shown in FIG. 7, the resistive electrodes 2 to 5 are bent and the ends of adjacent electrodes
Those connected via are known.

That is, by appropriately setting the resistance values of the electrodes 2 to 5 and the resistors 12 to 15, for example, when the voltage 116 is in the ON state, the voltage generated between the positions D and E, between D and F, and between both terminals of the resistor 12 is set. If the voltage drops occurring between the positions G and H, between G and F, and between both terminals of the resistor 12 are made equal when the power supply 17 is in the ON state, The equipotential line is a straight line as shown by a broken line or a two-dot chain line in the figure.

However, in the conventional contact type position detection device described above, the dimensions of each part of the planar resistance member 1 are restricted as follows.

That is, when the power supply 16 is in the ON state, between positions D and F,
and the voltage drop occurring between both terminals of resistor 12 is equal,
In addition, in order to equalize the voltage drop that occurs between positions G and F and between both terminals of the resistor 120 when the power source 17 is in the ON state, the shape of the planar resistor member 1 is set to be approximately square, and , it is necessary to set the distance between positions D and F and the distance between positions G and F to be equal to each other.

Therefore, there is a problem in that there is little freedom in designing dimensions and shapes, and the device tends to be large. In particular, it is difficult to use it by attaching it to the front of a display that is usually horizontally long.

In view of the above points, the present invention aims to provide a contact type position detection device that has high position detection accuracy and has a high degree of freedom in designing the dimensions and shapes of each part.

In order to achieve the above object of i', the present invention has a rectangular detection area near the center surrounded by two sides parallel to the first principal axis and two sides parallel to the second principal axis. In addition, in the contact type position detection device including a planar resistance member having a linearity imparting area on the outside of each side in the detection area, a plurality of resistance members are arranged in the linearity imparting area with their tips facing the detection area. a plurality of inter-electrode resistors connected between each electrode and having a resistance value proportional to the distance between the electrodes;
a first power supply resistor connected in series between an electrode at each end in the linearity imparting region parallel to the first principal axis and an electrode at each end in the linearity imparting region parallel to the second principal axis; and a second power supply resistor, the envelope of each electrode tip in each linearity imparting region is set to draw a parabola, and the first principal axis and the second
The sums Ra and Rb of the resistance values between the electrodes in each linearity region parallel to the main axis of R
a=41Da・ρ, and Rb=4(1/A)Db・
The resistance values Rac and Rbc of the first feeding resistance and the second feeding resistance are set to the resistance value given by ρ, respectively, Rac=(2A-Da-Db(2Da+1)ρ
) / (1-4Da-Db), and Rb c −
(2・Da−Db(2Db+1) ρ) / (A(1
-40a-Db))).

However, ρ is the resistance value per unit length and unit width of the planar resistance member, A, Da, and Db are A = Y/X, Da = 2Ca/Y, and Db = 2C, respectively.
This is the value given by b/X.

In addition, X is the length of the side parallel to the first principal axis in the detection area, Y is the length of the side parallel to the second principal axis in the detection area, and Ca is the length of the linearity imparting area parallel to the first principal axis. Width, cb
is the width of the linearity imparting region parallel to the second principal axis.

Once the above configuration is established, a predetermined voltage drop occurs due to the current flowing through each interelectrode resistance, sheet resistance member, and power supply resistance, and the equipotential line is a straight line along each side of the detection area. become.

Embodiment 1 FIG. 1 is a plan view showing the configuration of a contact type position detection device according to an embodiment of the present invention.

In the figure, 21 is a sheet resistance member, 21a is a detection area, 21b to 21e are linearity imparting areas, 22 is a stylus pen, 31 to 34 are power supply terminals, 41 to 44 are electrodes, and 51
~54 is the interelectrode resistance, 61~64 is the power supply resistance, 71~7
4 is a switch, 91 is a power supply, 93 and 94 are output terminals, 9
5 is an A/D converter.

The planar resistance member 21 is parallel to the y-axis or y-axis shown in the figure, and has a rectangular shape surrounded by sides having a length of X' or Y'. The sheet resistance member 21 is made of a material having a uniform resistance value (hereinafter referred to as sheet resistance) ρ per unit length and unit width over the entire surface, and for example, one manufactured by Donnelly of Holland of Michigan is used. More specifically, a thin film resistive coating made of a semiconductor metal oxide such as indium-tin oxide, tin oxide, tin-antimony oxide, indium oxide, etc., or sputtering or A thick film resistor such as a vapor-deposited film is formed.

These materials are selected so that the sheet resistance ρ is, for example, 200 to 500Ω. Moreover, the planar resistance member 21 is CR
When used by attaching it to the front of a T, it is necessary to select a transparent one, but when used in a digitizer or the like, an opaque one may be selected.

The detection area 21a of the planar resistance member 21 has a rectangular shape surrounded by X or Y sides.

The linearity imparting regions 21b to 21e are provided outside each of the above-mentioned sides, respectively, and are set to have a width Ca or cb.

The electrodes 41 to 44 are each made of a conductor or at least a material with higher conductivity than the sheet resistance member 21, and have a T-shape. The electrodes 41 to 44 are provided in the linearity imparting regions 21b to 21c with their tips facing the detection region and at least the tips thereof being electrically conductive on the surface of the planar resistance member 21.

More specifically, the shape of the electrodes 41 to 44 is such that, for example, as shown in FIG.
m, the width of the tip is set to be p/2=10 mm, and the width of the base is set to be 1)/4=5 mm. In addition, the envelopes of the tips of the electrodes 41... and the electrodes 42..., 1y-C; (x), and the electrodes 43...
... and the envelope x=H(y) of the electrode 44... are set to draw a parabola represented by or, respectively.

Such electrodes 41 to 44 and 34 to the power supply terminal 31
can be formed in a desired pattern with a small error in shape and with a small number of manufacturing steps by, for example, silk screen printing using a known silver ink, but the invention is not limited thereto.

Inter-electrode resistors 51-54 made of chip resistors are connected between the respective electrodes 41-44 in each of the linearity imparting regions 21b-21e.

The sum of the inter-electrode resistances 51 and the inter-electrode resistance 5
The total sum Ra of 2... is set to be Ra=41Da・P・'' (13).Here, A=Y/×(aspect ratio of detection area 21a), Da=2Ca/Y It is.

Further, the sum of the inter-electrode resistances 53... and the sum Rb of the inter-electrode resistances 54... are as follows: Rb = 4(1/A)Db・ρ...(14
). Here, Db=2Cb
/X.

Power supply resistors 61 to 61 are connected between the electrodes 41 to 44 located at the ends thereof and the power supply terminals 31 to 34, respectively.
64 are connected.

The resistance value Rac of the power supply resistors 61 and 62 and the resistance value Rbc of the power supply resistors 63 and 64 are set as follows.

The spin chias 1 to 74 are alternately turned on under the control of a control device (not shown), and the power supply terminals 31 and 3
2 and power supply terminals 33 and 34, or between power supply terminals 31 and 33
and the power supply terminals 32 and 34, respectively.
It is designed to apply a voltage of .

Output terminals 93 and 94 are connected to an A/D converter 95. Under the control of the control device, the A/D converter 95 is configured to output a digital signal corresponding to the contact position of the stylus pen 22 in the X direction and the y direction in synchronization with the ON/OFF timing of the switches 71 to 74. It has become.

As mentioned above, the shapes of the envelopes of the tips of the electrodes 41 to 44, the interelectrode resistances 51 to 54, and the feeding resistances 61 to 64
By setting the resistance value etc. of the switch 71
- When 73 is in the ON state, current flows through the sheet resistance member 21 from the electrodes 41... to the electrodes 42...
Within the detection region 21a, equipotential lines are parallel to the X axis and are spaced at equal intervals over the entire area. In addition, the switch 72.7
4 is in the ON state, the equipotential lines are parallel to the y-axis and are equally spaced.

Therefore, when the stylus pen 22 contacts the detection area 2 ], a of the planar resistance member 21, the potential of the stylus pen becomes a potential having a linear relationship with the X-direction position of the contact point or the X-direction position.

Next, the reason why the equipotential lines are parallel to the y-axis or at equal intervals as described above will be explained by showing the process of deriving the equations (11) to (16). For the sake of simplicity, the first quadrant when the switches 71 and 73 are in the ON state will be considered as a representative, and the electrodes 41... and the inter-electrode resistances 51... It is assumed that it is composed of a collection of electrodes and resistors that are minutely divided in the axial direction.

First, the distance G(x) from the straight line y=o to the tip of the electrode 41... in order to make the potential at the position y=Y/2 equal to Va, which is related to the position in the X-axis direction, is , can be obtained as follows.

(0.O), (OX), (x
, Y/2), and (0, Y/2).
The magnitude of the current i (x) flowing in the direction parallel to the axis is
Since the resistance value in the above region is R-ρ(Y/2)/x, Va 2Va Rρ ・Y Since this current i (x) is supplied through the portion of position X in the inter-electrode resistance 51, the inter-electrode resistance The potential difference ΔE (x) between the minute distance Δχ of 51 is the resistance value ΔR=Ra (Δx / X), so ΔE (x
) -i (x) ・ΔRρ ・X-Y Therefore, the potential difference E (x) between x=Q and In order for the potential at the position of y=Y/2 to become Va, the potential difference at the distance G (x) Y/2 in the sheet resistance member 21 and the potential difference E (x) must be Just make sure they are equal. Here, since the potential difference per distance MY/2 in the sheet resistance member 21 is Va, and from formula (22), [) a = 2Ca / Y
Using , the total sum Ra of the inter-electrode resistance 51 is 2 2
ρ ・X On the other hand, G (X/2)=Y/20Ca, Ca
=G (X/ 2) - Y/ 2ρ ρ 2 (20) From this, 4YDa · ρ = 4A-Da -p - (13) is obtained.

The above formulas (12) and (14) can be obtained in the same manner.

In addition, the resistance values of the power supply resistors 61 to 64 are set as follows, and the positions (X/2.Y/2) and (X
/2+Cb, Y/2) so that the equation C<Va can be satisfied.

That is, the potential Vs of the power supply terminal 31 is ρ is obtained.

ρ・Y Also, if the current flowing through the power supply resistor 64 is ib, then the formula (
14), Vs=Va+1b-Rbc b From the above formulas (23) and (24), 1, °, 2 ρADaDb+2DbRaA2 R On the other hand, similarly, considering the case where the switch 72.7 becomes, the above formula % formula % and Rbc bc... (25) If 4 is in the ON state (24), A, Db, Da, 2 (25) and (26) are simultaneously solved, 2 (15)
(16) is obtained.

That is, the arrangement of the electrodes 41... and the inter-electrode resistance 51...
By setting the resistance value, etc. of
Within the detection region, the equipotential lines are straight and equally spaced.

In addition, in the above embodiment, each linearity imparting region 21b
Although an example has been described in which an odd number of electrodes 41 to 44 are provided at equal intervals in ~21e, the number of electrodes 41 to 44 may be an even number, and the arrangement may not necessarily be at equal intervals. It is sufficient that the resistance values of the resistors 51 to 54 are proportional to the interval.

In addition, the shape of the electrodes 41 to 44 is T-shaped as described above, and if the width of the base is set to about 40 to 60% of the width of the tip, good characteristics can be obtained. It's not a thing.

In addition, each electrode 41 to 44 and inter-electrode resistance 51 to 54
does not need to be on the planar resistance member 21 as long as the tips of the electrodes 41 to 44 are electrically connected to the planar resistance member 21 at a predetermined position.

Furthermore, the interelectrode resistances 51 to 54 are not limited to each consisting of a single chip resistor, but may also be formed by connecting a plurality of chip resistors in parallel or in series, or by printing carbon or organic resistance ink. The material may be coated, dried, etc., and the resistance value may be adjusted by laser trimming if necessary.

Furthermore, for example, as shown in FIGS. 3(a) to (c),
Conductive members 104 to 109 such as conductive films are provided on the sheet resistance member 21 so that predetermined gaps 101 to 103 are formed, and interelectrode resistance etc. are formed using the sheet resistance ρ of the sheet resistance member 21. You may. That is, gaps 101-1
If the shape and dimensions of 03 are set as shown in the figure,
A resistor having a resistance value ρXL/(the sum of W or Wl . . . ) can be formed. In particular, the same figure (b) (c)
By forming the gaps 102 and 103 non-linearly as shown in FIG. 1, it is possible to obtain a small resistance value without reducing the dimensions too much.

Furthermore, since the resistance value is not affected by the thickness of the conductive members 104, screen printing of conductive ink or the like can be easily applied. Furthermore, since the resistance value is proportional to the sheet resistance ρ of the sheet resistance member 21 as described above, it has the advantage that even if the sheet resistance ρ varies, an appropriate resistance value can be obtained in accordance with the variation. ing.

Further, the shape of the detection area 21a is not limited to the rectangle as described above, but may be a parallelogram or the like.

Furthermore, the contact type position detection device may be combined with a device that detects contact pressure, such as the stylus pen 22, to enable detection of three-dimensional parameters.

As explained above, according to the present invention, the resistance between each electrode and the resistance value of the power supply resistor can be adjusted according to the vertical and horizontal dimensions of the detection area, the widthwise dimension of the linearity imparting area, etc. By setting as described above, it is possible to make the equipotential line 4° a straight line along each side of the detection area.

Therefore, the dimensions and shapes of each part can be arbitrarily set without deteriorating the detection accuracy, and it is possible to easily miniaturize the device and optimize the shape.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the configuration of a contact type position detection device according to an embodiment of the present invention, Fig. 2 is a plan view showing the detailed shape of the electrodes, and Fig. 3 is a plan view showing another example of the inter-electrode resistance. The plan view and FIGS. 4 to 7 are plan views each showing the configuration of a conventional contact type position detection device.

Claims (1)

[Claims] (1) Two sides parallel to the first principal axis and two sides parallel to the second principal axis
A contact type position detection device including a planar resistance member having a rectangular detection area near the center surrounded by sides and a linearity imparting area on the outside of each side of the detection area, a plurality of electrodes disposed in the sex-imparting region with their tips facing the detection region; a plurality of inter-electrode resistors connected between each electrode and having a resistance value proportional to the distance between the electrodes; a first power supply resistor connected in series between an electrode at each end in the linearity imparting region parallel to the first principal axis and an electrode at each end in the linearity imparting region parallel to the second principal axis; and a second power feeding resistance, the envelope of each electrode tip in each linearity imparting region is set to draw a parabola, and each linearity imparting parallel to the first principal axis and the second principal axis is provided. The sum of the resistance values of the interelectrode resistances in the region is set to the resistance value given by the first equation and the second equation, respectively, and the resistance values of the first feeding resistance and the second feeding resistance are respectively set to the resistance values given by the third equation. A contact type position detection device characterized in that the resistance value is set to a value given by Equation 1 and Equation 4. 1st formula Ra=4A・Da・ρ 2nd formula Rb=4(1/A)Db・ρ 3rd formula Rac=2A・Da・Db(2Da+1)ρ/1
-4Da・Db4th formula Rbc=2・Da・Db(2D
b+1) ρ/A (1-4Da・Db) However, Ra is the first
Rb is the sum of the resistance values of interelectrode resistance in each linearity imparting region parallel to the second principal axis, Rac is the sum of the resistance values of interelectrode resistance in each linearity imparting region parallel to the second principal axis, and Rac is the sum of the resistance values of interelectrode resistance in each linearity imparting region parallel to the second principal axis. Rbc is the resistance value of the second power supply resistor, ρ is the resistance value per unit length and unit width of the planar resistance member, A, Da, and Db are each expressed by the fifth formula or This is the value given by the seventh equation. 5th equation A=Y/X 6th equation Da=2Ca/Y 7th equation Db=2Cb/X However, X is the length of the side parallel to the first principal axis in the detection area, and Y is the length of the second side in the detection area. The length of the side parallel to the principal axis, Ca is the width of the linearity imparting region parallel to the first principal axis, and Cb is the width of the linearity imparting region parallel to the second principal axis.