JPH0612508B2 - Contact position detector - Google Patents

Description

The present invention relates to a CG (Computa Graphics) system and a CAD (C
The present invention relates to a contact type position detecting device which is used as an input device in an omputa Aided Design system or the like and detects a position where a finger or a pen-shaped member comes into contact and outputs a signal corresponding to the detected position.

2. Description of the Related Art Conventionally, a planar resistance member has a predetermined voltage gradient,
2. Description of the Related Art There is known a contact type position detection device that detects the contact position by the potential of the position where the stylus pen or the like contacts.

More specifically, for example, as shown in FIG. 4, this type of contact-type position detecting device is provided with electrodes 2 and 3 on opposite sides of a square-shaped planar resistance member 1, and the electrodes 2 and 3 are provided.
The principle is that when the stylus pen 11 is brought into contact with the sheet resistance member 1 in a state where a predetermined voltage is applied, a potential difference proportional to the distance is generated between the electrode 2 and the stylus pen 11.

Further, as shown in FIG. 5, the contact positions of the stylus pen 11 in the vertical and horizontal directions are further provided with electrodes 4 and 5,
It can be detected by alternately applying a voltage between the electrodes 3 and between the electrodes 4 and 5.

By the way, as described above, the electrodes 2 are provided on the four sides of the sheet resistance member 1.
5 to 5, when a voltage is applied between the electrodes 2 and 3, for example, a current leaking through the electrodes 4 and 5 is generated, resulting in a significant increase in power consumption. Therefore, it is possible to reduce the power consumption by providing the electrodes 2 to 5 with some resistance and connecting them as shown in FIG. In the figure, the connection for detecting the contact position in the X direction is omitted.

However, if the electrodes 2 to 5 are made to have a resistance, a potential difference occurs, for example, from the positions A and B to the position C, and the equipotential lines are not straight lines as shown by the broken lines in the figure. Therefore, the detected potential difference does not become proportional to the distance from the electrode 2 to the contact position, and the position detection accuracy decreases. therefore,
Calculation and correction for obtaining the contact position based on the detected voltage are required, which complicates the configuration of the device.

A contact-type position detecting device that solves such a problem is disclosed, for example, in US Pat. No. 4,1985,39,
As shown in FIG. 7, the resistive electrodes 2 to 5 are curved, and the end portions of the adjacent electrodes are connected to each other with the resistances 12 to 15.
It is known that they are connected via.

That is, the resistance values of the electrodes 2 to 5 and the resistors 12 to 15 are appropriately set, and for example, the voltage generated between the positions D and E, between D and F, and between both terminals of the resistor 12 when the power supply 16 is in the ON state. If the drops are equal to each other and the voltage drops generated between the positions G and H, between G and F and between both terminals of the resistor 12 when the power supply 17 is in the ON state are equal to each other, the equipotential lines are the same. It becomes a straight line as shown by a broken line or a two-dot chain line in the figure.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned conventional contact type position detecting device, the dimensions of each part of the planar resistance member 1 are restricted as follows.

That is, when the power source 16 is in the ON state, between the positions D and F,
And the voltage drop between both terminals of the resistor 12 is equal,
Further, in order to equalize the voltage drop generated between the positions G and F and between both terminals of the resistor 12 when the power supply 17 is in the ON state, the planar resistance member 1 is set to a substantially square shape, Moreover, it is necessary to set the distance between the positions D and F and the distance between the positions G and F to be equal to each other.

Therefore, there is a problem that the degree of freedom in designing the size and shape is small and the device tends to be large. In particular, it is difficult to mount the display on the front surface of a display which is usually in a horizontally long shape and to use it.

In view of the above points, an object of the present invention is to provide a contact-type position detection device that has a high position detection accuracy and a high degree of freedom in designing the size and shape of each part.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a square detection area surrounded by two sides parallel to a first main axis and two sides parallel to a second main axis near a central portion. And a contact-type position detecting device having a planar resistance member having a linearity imparting region on the outside of each side in the detection region, wherein the tip end portion is arranged in the linearity imparting region toward the detection region. A plurality of electrodes, having a resistance value proportional to the distance between the electrodes, a plurality of inter-electrode resistance connected between the electrodes,
A first feed resistance connected in series between the electrode at each end in the linearity imparting region parallel to the first main axis and the electrode at each end in the linearity imparting region parallel to the second main axis; And a second power feeding resistor, wherein the envelope of each electrode tip portion in each of the linearity imparting regions is set so as to draw radiation, the first main axis, and the second
The sum of the resistance values Ra and Rb of the inter-electrode resistances in the respective linearity imparting regions parallel to the main axis of
a = 4A · Da · ρ and Rb = 4 (1 / A) Db · ρ, and the resistance values Rac and Rbc of the first power feeding resistor and the second power feeding resistor are respectively Rac and Rbc. =
(2A · Da · Db (2Da + 1) ρ) / (1-4Da · Db), and Rbc =
It is characterized by being set to a resistance value given by (2 · Da · Db (2Db + 1) ρ) / (A (1-4Da · Db)).

Where ρ is the resistance value A, Da, and Db per unit length and unit width in the planar resistance member, A = Y /
The values given are X, Da = 2Ca / Y, and Db = 2Cb / X.

X is the length of the side parallel to the first main axis in the detection region, Y is the length of the side parallel to the second main axis in the detection region, and Ca is the linearity imparting region parallel to the first main axis. Width, C
b is the width of the linearity imparting region parallel to the second main axis.

Action According to the above configuration, a predetermined voltage drop occurs due to the current flowing through the inter-electrode resistance, the sheet resistance member, and the feeding resistance, and the equipotential lines become straight lines along each side of the detection region.

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

In the figure, 21 is a planar resistance member, 21a is a detection region, 21b to 21e are linearity imparting regions, 22 is a stylus pen, 31 to 34 are power supply terminals, 41 to 44 are electrodes, 5
1 to 54 are interelectrode resistances, 61 to 64 are power feeding resistances, 71 to
74 is a switch, 91 is a power supply, 93 and 94 are output terminals,
Reference numeral 95 is an A / D converter.

The planar resistance member 21 is parallel to the x-axis or the y-axis shown in the drawing and has a rectangular shape surrounded by a side having a length of X ′ or Y ′. The sheet-like resistance member 21 is made of a material having a uniform resistance value per unit length and unit width (hereinafter referred to as sheet resistance) ρ over the entire surface. For example, Michigan's Donnel
Those manufactured by ly of Holland are used. More specifically, for example, on a substrate made of plastic or glass, a thin film resistance coating made of a semiconductor metal oxide such as indium-tin oxide, tin oxide, tin-antimony oxide, indium oxide, or sputtering or A thick film resistor such as a vapor deposition film is formed.

These materials are selected so that the sheet resistance ρ is, for example, 200 to 500Ω. Further, the sheet resistance member 21 is CR
When it is mounted on the front surface of T and used, a transparent one needs to be selected, but when it is used for 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 a side whose length is X or Y. The linearity imparting regions 21b to 21e are provided outside the respective sides and are set to have a width Ca or Cb or Cb.

Each of the electrodes 41 to 44 is made of a conductor or a material having higher conductivity than at least the planar resistance member 21, and has a T-shape. The electrodes 41 to 44 are provided in the linearity imparting regions 21b to 21c so that their tip portions face the detection area, and at least their tip portions are in a conductive state on the surface of the planar resistance member 21.

More specifically, the shapes of the electrodes 41 to 44 are, for example, as shown in FIG. 2, a pitch p of the electrodes 41 to 44 of 20 mm.
Then, the width of the tip is p / 2 = 10mm, and the width of the base is p.
It is set so that / 4 = 5 mm. Also, the electrode 4
1 and the envelopes of the electrodes 42 ... Y = G (x),
And the envelope x = H of the electrodes 43 ... And the electrodes 44 ...
(Y) is Or It is set to draw a parabola represented by.

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

Inter-electrode resistors 51 to 54, which are chip resistors, are connected between the electrodes 41 to 44 in the linearity imparting regions 21b to 21c, respectively.

The sum of the interelectrode resistances 51 ... and the interelectrode resistance 52 ...
Ra is set so that Ra = 4A · Db · ρ (13). Here, A = Y / X (aspect ratio of the detection area 21a) and Da = 2Ca / Y.

Further, the sum of the interelectrode resistances 53 ... And the interelectrode resistance 54
The total sum Rb of ... Is set so that Rb = 4 (1 / A) Db · ρ (14). Here, Db = 2Cb /
It is X.

Between the electrode located at the end of the electrodes 41 to 44 and the power feeding terminals 31 to 34, the power feeding resistors 61 to 41 are respectively provided.
64 is connected.

The resistance value Rac of the power feeding resistors 61 and 62 and the resistance value Rbc of the power feeding resistors 63 and 64 are Is set to be

The switches 71 to 74 are alternately turned on by the control of a control device (not shown), and the power supply terminals 31.3
2 and the power supply terminals 33 and 34, or the power supply terminals 31 and 33
The voltage of the power source 91 is applied between the power feeding terminal 32 and the power feeding terminal 34, respectively.

The output terminals 93 and 94 are connected to the A / D converter 95. The A / D converter 95 outputs a digital signal according 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 under the control of the control device. Has become.

As described 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.
Since the resistance value of
When 73 is turned on, a current flows in the planar resistance member 21 from the electrodes 41 to the electrodes 42, and the equipotential lines are parallel to the x axis and are equally spaced throughout the detection region 21a. become. Further, when the switches 72 and 74 are turned on, the equipotential lines are parallel to the y-axis and at equal intervals.

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

Next, the reason why the equipotential lines are parallel to the x-axis or the y-axis and have equal intervals as described above will be described by showing the derivation process of the equations (11) to (16). Here, for simplification, the portion of the first quadrant when the switches 71 and 73 are in the ON state is considered as a representative, and the electrodes 41 ... And the interelectrode resistance 51 ... Are minute in the x-axis direction. It is assumed that it is composed of a group of electrodes and resistors divided into.

First, the distance G (x) from the straight line y = 0 to the tips of the electrodes 41 is set so that the potential at the position y = Y / 2 becomes Va regardless of the position in the x-axis direction. Is asked in this way.

(0,0), (0, x) in the planar resistance member 21,
In the region surrounded by (x, Y / 2) and (0, Y / 2), the magnitude i (x) of the current flowing in the direction parallel to the y axis is
Since the resistance value R = ρ (Y / 2) / x in the above region, Since this current i (x) is supplied through the portion of the interelectrode resistance 51 at the position x, the potential difference ΔE (x) between the minute distances Δx of the interelectrode resistance 51 is the resistance value ΔR =
Since it is Ra (Δx / X), Therefore, the potential difference E (x) at the portion between x = 0 and x in the interelectrode resistance 51 is Therefore, in order to set the potential at the position of y = Y = / 2 to Va regardless of the position in the x-axis direction, the potential difference at the portion of the distance G (x) −Y / 2 in the planar resistance member 21. And the potential difference E (x) may be equal. Here, since the potential difference per distance Y / 2 in the planar resistance member 21 is Va, On the other hand, since G (X / 2) = Y / 2 + Ca, From equations (20) and (22), Is obtained.

Further, from equation (22), using Da = 2Ca / Y, the sum Ra of the interelectrode resistances 51 ... Is obtained.

The equations (12) and (14) are also obtained in the same manner.

Further, the resistance values of the power feeding resistors 61 to 64 are set as follows, so that the positions (X / 2, Y / 2) and (X
/ 2 + Cb, Y / 2) can be equalized to Va.

That is, the potential Vs of the power supply terminal 31 is If the current flowing through the power feeding resistor 64 is ib, from equation (14), From the above formulas (23) and (24), On the other hand, similarly, considering the case where the switches 72 and 74 are in the ON state, A, Da, Db, and
And Rac with 1 / A, Db, Da and Rbc, If equations (25) and (26) are solved simultaneously, equation (15)
(16) is obtained.

That is, by setting the arrangement of the electrodes 41, the resistance value of the interelectrode resistance 51, and the like as described above, the detection region 21
Since the potentials on the respective sides of a are all equipotential, the equipotential lines are straight lines at equal intervals in the detection region.

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

Further, the shape of the electrodes 41 to 44 is T-shaped as described above, and good characteristics were obtained when the width of the base portion was set to about 40 to 60% with respect to the width of the tip portion. It is not limited.

In addition, the electrodes 41 to 44 and the interelectrode resistances 51 to 54
Need not be on the sheet resistance member 21, as long as the tips of the electrodes 41 to 44 are electrically connected to the sheet resistance member 21 at predetermined positions.

Further, the inter-electrode resistors 51 to 54 are not limited to the ones each formed of a single chip resistor, and may be, for example, ones in which a plurality of chip resistors are connected in parallel or in series, and further, printing of carbon or organic resistance ink or Apply, dry, etc.
The resistance value may be adjusted by laser trimming if necessary.

Further, for example, as shown in FIGS. 3 (a) to 3 (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 the sheet resistance ρ of the sheet resistance member 21 is used to form interelectrode resistance or the like. You may. That is, the gaps 101 to 1
If the shape and dimensions of 03 are set as shown in the figure,
A resistance having a resistance value of ρ × L / (sum of W or W1 ...) Can be formed. In particular, by forming the gaps 102 and 103 in a non-linear manner as shown in FIGS. 9B and 9C, it is possible to obtain a small resistance value without making the dimension L too small.

Further, since the resistance value is not affected by the thickness of the conductive member 104 ..., Screen printing of conductive ink or the like can be easily applied. In addition, since the resistance value is proportional to the surface resistance ρ of the sheet resistance member 21 as described above, even when the surface resistance ρ varies, an appropriate resistance value corresponding to the variation can be obtained. ing.

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

Further, the contact-type position detection device may be combined with a device such as a stylus pen 22 that detects a contact pressure or the like to enable three-dimensional parameter detection or the like.

EFFECTS OF THE INVENTION As described above, according to the present invention, the inter-electrode resistance and the resistance value of the power feeding resistance are set as described above according to the vertical and horizontal dimensions of the detection region and the widthwise dimension of the linearity imparting region. By setting to, the equipotential lines can be made straight lines along each side of the detection region.

Therefore, the size and shape of each part can be arbitrarily set without lowering the detection accuracy, and it is possible to easily downsize the device and optimize the shape.

[Brief description of drawings]

FIG. 1 is a plan view showing the configuration of a contact-type position detecting device in one embodiment of the present invention, FIG. 2 is a plan view showing the detailed shape of electrodes, and FIG. 3 is another example of interelectrode resistance. A plan view and FIGS. 4 to 7 are plan views showing the configuration of a conventional contact-type position detecting device, respectively. 21 ... Sheet resistance member, 21a ... Detection area, 21b-21
e ... Linearity imparting regions, 41-44 ... Electrodes, 51-54 ...
Resistance between electrodes, 61 to 64 ... Feed resistance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gary Barrett 5524 Bebe Caves Road, Austin, Texas, United States Within The Graphics Technology Company (56) References JP-A 61-182127 ( JP, A)

Claims (1)

[Claims] 1. A rectangular detection area surrounded by two sides parallel to a first main axis and two sides parallel to a second main axis is provided in the vicinity of a central portion and outside each side of the detection area. In a contact-type position detection device including a planar resistance member having a linearity imparting region, a plurality of electrodes arranged with the tip end facing the detection region in the linearity imparting region, and a distance between the electrodes A plurality of inter-electrode resistances having proportional resistance values and connected between the electrodes, electrodes at each end in the linearity imparting region parallel to the first main axis, and linearity parallel to the second main axis. A first power feeding resistor and a second power feeding resistor that are connected in series with the electrodes at each end in the application region are provided, and the envelope of each electrode tip in each linearity application region draws radiation. Parallel to the first and second main axes The sum of the resistance values of the inter-electrode resistances in the respective linearity imparting regions is set to the resistance values given by the first equation and the second equation, respectively. The contact-type position detecting device, wherein the resistance values are set to the resistance values given by the third and fourth expressions, respectively. However, Ra is the sum of the resistance values of the inter-electrode resistance in each linearity imparting region parallel to the first main axis, and Rb is the resistance value of the inter-electrode resistance in each linearity imparting region parallel to the second main axis. Rac is the resistance value of the first feeding resistance, Rbc is the resistance value of the second feeding resistance, ρ is the resistance value per unit length and unit width of the planar resistance member, A, Da, and Db are , And the values given by the fifth to seventh equations, respectively. Formula 5 A = Y / X Formula 6 Da = 2Ca / Y Formula 7 Db = 2Cb / X where X is the length of the side parallel to the first main axis in the detection region, and Y is the second in the detection region. Is the length of the side parallel to the main axis, Ca is the width of the linearity imparting region parallel to the first main axis, and Cb is the width of the linearity imparting region parallel to the second main axis.