JP2010157029A - Coordinate input system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coordinate input system for preventing incorrect detection by contact or the like of a palm, in a coordinate input panel of resistance film type where the protective layer is made thick to improve the durability. <P>SOLUTION: In the input panel requiring high durability, a thick non-insulating resin film is sometimes used as the protective layer, but a coordinate shifted from the position specified by a finger can be input in response to influence of capacitance binding between the palm and a face resistance element. The coordinate input system has a calculating means for identifying whether the number of contact or proximity parts of a coordinate input region with a conductor such as the finger is one or two, thereby preventing incorrect detection even when the protective layer is made thick to improve the durability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coordinate input system for detecting a position indicated by a conductor such as a finger, and more particularly to a coordinate input system having a calculation means for identifying whether a coordinate input region is in contact with or close to a coordinate input region by one or two locations.

The input panel of the coordinate input system is provided with a rectangular resistive surrounding electrode in which a resistance value per length of each side is constant within each side in a form surrounding the surface resistor in a uniform surface resistor. In addition, detection electrodes are provided at four vertices. The detection electrode is electrically connected to the resistive surrounding electrode.
As a coordinate detection method of the coordinate input system, a method of measuring a current value distributed to four vertices of a current flowing into a surface resistor of an input panel is known (see Patent Document 1). It is known that the coordinates of the position indicated by the finger can be calculated using the distribution values of the current flowing into the surface resistor to the four vertices (see Patent Document 2). The number of detection point electrodes needs to be set at least at the apex of the input panel, but more detection electrodes may be set on the side. The coordinate calculation method in that case has been filed as Japanese Patent Application No. 2008-251905 (Patent Document 3).

The coordinate input system as described above may be installed in public places such as ticket machines and ATMs. In that case, the input panel must be highly durable because it is used by an unspecified number of people. It has been demanded.

In order to improve the durability of the input panel, it is conceivable to provide a protective layer on the surface resistor. The protective layer may be an insulating layer or a non-insulating resin film is known (see Patent Document 4). At this time, current flows into the surface resistor due to capacitive coupling between the finger and the surface resistor. In addition, the thicker the protective layer, the higher the durability.

When the protective layer is provided on the surface resistor, it is necessary to provide a threshold value for the total value of the current amounts measured by the respective detection electrodes in order to determine whether or not the finger is in contact with the protective layer. That is, when the total value of the measured current amounts is less than a certain value, it is assumed that the finger is not touching and the coordinates are not calculated. Since the capacitive coupling changes depending on the distance between the finger and the surface resistor, when the protective layer is provided thickly on the surface resistor, it is necessary to lower the threshold setting.

JP 2000-132319 A Japanese Patent No. 4168537 Japanese Patent Application No. 2008-251905 JP 2003-140833 A

The magnitude of the capacitive coupling varies greatly depending on the distance and area between the human body and the surface resistor. In other words, the capacitive coupling increases as the distance between the human body and the surface resistor decreases, and the capacitive coupling increases as the area receiving the capacitive coupling increases. That is, when the protective layer is provided thick, the capacitive coupling between the finger and the surface resistor is relatively small even when the finger touches the coordinate input area. At this time, depending on how the operator gives an instruction, it may be affected by the capacitive coupling between the palm and the surface resistor, which could be ignored in the past. In other words, the detected coordinate is the position where the finger is capacitively coupled, or not only the finger but also the palm is capacitively coupled to the surface resistor, and as a result, it deviates from the position indicated by the original finger. I couldn't determine if it was a position.
The present invention has been made in consideration of such points, and performs coordinate calculation of the position indicated from the current amount measured by each detection electrode, and one capacitive coupling in the coordinate input area. It is an object of the present invention to provide a coordinate input system that can prevent erroneous detection even if the protective layer is thickened for the purpose of improving durability, by identifying whether there are two locations.

  The present invention provides a rectangular resistive surrounding electrode in which the resistance value per length of each side is constant within each side around or inside a surface resistor formed on an insulating substrate, and all sides are said surfaces. A coordinate input system that is provided so as to be in electrical contact with a resistor, and the inside of the resistive surrounding electrode is a coordinate input area, and when the coordinate input area is in contact with or close to a conductor such as a finger, A detection electrode for measuring the current flowing through at least all the vertices of the resistive surrounding electrode; and a coordinate calculation means for calculating the position of the coordinate input region in contact with or close to the conductor from the current value measured by the detection electrode; The gist of the present invention is a coordinate input system having identification calculation means for identifying whether the coordinate input region is in contact with or close to the coordinate input region from the current value measured by the detection electrode.

In the coordinate input system according to the present invention, it is possible to identify whether or not the coordinates are deviated from the position of the finger due to the influence of the palm even if the protective layer is thickened in order to improve durability. Therefore, a device such as a ticket vending machine using the coordinate input system according to the present invention uses coordinates as it is when it is not affected by the palm, and inputs it to the operator again as an error when it is affected by the palm. By issuing a prompting message, it is possible to avoid false detection.

In the case of a coordinate input system used by an unspecified number of people, it is possible to react even when touched lightly by setting a low threshold to identify whether or not it is receiving capacitive coupling from fingers. It becomes a highly convenient touch panel that can be used. Even in this case, erroneous detection can be avoided.

By identifying whether there is one or two capacitive couplings in the coordinate input area, it is possible to identify whether one finger is operating or two fingers. If you operate with, you can disable it or assign it to a function such as double-clicking to improve convenience. However, even if the operation is performed with two fingers, the coordinates are calculated as one point. Therefore, when assigning such an operation to a function, it is necessary to pay attention to the handling of the coordinate values.

Hereinafter, preferred embodiments of a coordinate input system according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a configuration diagram illustrating an example of a coordinate input system. It is a block diagram of the coordinate input system which detects the position (X, Y coordinate) which the finger | toe 7 pointed in the coordinate input area 12 of the input panel. The surface resistor 1 is formed by uniformly forming an ITO film, a NESA film, or the like on one side of a transparent glass, resin, or opaque insulating substrate by coating, vapor deposition, or the like. In order to improve durability, the surface of the surface resistor 1 is provided with a protective layer, and the protective layer is insulated so that the finger 7 does not touch the surface resistor 1 directly. The signal may be transmitted by capacitive coupling, the protective layer may be as described in Patent Document 4, or the protective layer is not provided and the finger 7 and the surface resistor 1 are directly connected. You may make it transmit the signal by electrical contact. Here, the case where the protective layer which performed the insulation process on the surface resistor 1 surface is provided is demonstrated.
The resistive surrounding electrode 2 is closely arranged around or inside the uniform surface resistor 1, and the inside of the resistive surrounding electrode 2 is used as a coordinate input area 12. On the resistive surrounding electrode 2, the detection electrodes 3 to 6 are installed at the four corner positions of the coordinate input area, and the lead wires 8 to 11 are connected to the detection electrodes 3 to 11, respectively. The lead wires 8 to 11 are connected to the oscillating voltage application circuit 16 in the analog signal processing unit 15.

  When detecting the coordinates, the oscillating voltage generator 17 serving as an AC signal source applies an oscillating voltage to the oscillating voltage applying circuit 16, and the oscillating voltage applying circuit 16 vibrates the corresponding detection electrodes 3 to 6 with low impedance, In addition, the current flowing from the detection electrode is output to the analog multiplexer 18. As a simple example, a transistor base is vibrated by an AC signal, an emitter is connected to a detection electrode, and a current is output from a collector.

  The vibration resistance generator 17 serving as an AC signal source causes voltage oscillation of the entire surface resistor 1. As is known in the art, the human body has a grounding effect on the AC signal. When the human finger 7 contacts or approaches the surface resistor 1, the surface resistor is passed through the fingertip by capacitive coupling. AC signal current flows between 1 and 1. The detection electrodes 3 to 6 are connected to an A / D converter (analog / digital converter) 19 through an analog multiplexer 18, and a voltage proportional to the current flowing through each detection electrode is applied to the A / D converter 19. The current value flowing from the fingertip through the surface resistor 1 and distributed to the detection electrodes 3 to 4 can be obtained as a digital value as a voltage value. The CPU 20 switches the analog multiplexer 18 in order, inputs the digital value output from the A / D converter 19, and calculates the coordinates of the designated position of the finger 7. In addition, a calculation is performed to identify whether the measured current amount flows from the instructed finger 7 or is influenced by another conductor.

The coordinate calculation method of the finger position is as disclosed in Patent Document 2 and is calculated based on the ratio of the measurement levels of each detection electrode, so even if the coupling amount of capacitance changes greatly. The coordinates on the finger panel are detected with high accuracy. The CPU 20 outputs the calculated coordinates, and the coordinates are used by a subsequent apparatus.

If the palm position is close to the coordinate input area 12 when operating, there are cases where capacitive coupling is performed at two locations on the coordinate input area 12, the finger and the palm. At this time, a total amount of current flowing through the detection electrodes 3 to 6 is capacitively coupled. As described above, since the coordinates are calculated from the ratio of each detection electrode, the coordinates between the finger and the palm are calculated.
That is, even if the coordinate calculation formula alone is affected by the palm and the calculated coordinate is different from the position indicated by the finger, it cannot be identified.

For this reason, whether it is influenced by the palm separately from the calculation of coordinates, that is, whether the capacitive coupling is performed at one place or two places in the coordinate input area 12 is identified. A method is needed.
For example, if the current amounts measured by the detection electrodes 3 to 6 at the apexes of the coordinate input area in FIG. 1 are I _A , I _B , I _C , and I _D , respectively, Equation 1 is calculated based on Patent Document 2. I understood that it was true.

However, Formula 1 is an equation that holds when there is only a finger, that is, in a state where capacitive coupling is performed at one location in the coordinate input area 12. It has been found that it does not hold when receiving capacitive coupling.
Therefore, the current amount of the relationship of the detection electrode in the apex of the coordinate input region, the value of S ₁ defined by the equation 2, or a state in which the capacitive coupling at one point on the coordinate input region 12 2 It is possible to identify whether the capacitive coupling is in place. Here, I is the total sum of the detection electrodes.

S _{1 in} Equation 2 has a different sign depending on the positional relationship between the two points that are subjected to capacitive coupling, and the absolute value increases as the distance between the two points increases. The closer the quantity ratio is to 1: 1, the greater the absolute value. However, the parallel position relationship between the two points on the Y-axis or, if it becomes parallel to the X axis to a value of S ₁ is 0.
By performing identification calculation of Formula 2, when the value of S ₁ is 0, there is one capacitive coupling in the coordinate input area 12. If the value of S ₁ is other than 0, it can be identified that there are two capacitive couplings in the coordinate input area 12. At this time, there is a case where the value of S ₁ capacitive coupling even when the one place under the influence of such noise is not zero. The, for example ± 0.01 below the value of S ₁ it is necessary threshold setting, such as 0 and regarded.

However, with the formula 2 alone, when the positional relationship between the two points, that is, the positional relationship between the hand and the palm is parallel to the Y axis or parallel to the X axis, the value of S ₁ is close to 0. Thus, it becomes difficult to distinguish from the case where there is one capacitive coupling. In this case, can be identified by reducing the threshold value S _1, is too small a threshold value S _1, for example, capacitive coupling between the palm and the coordinate input region 12 is coordinate precision Even if it is small enough not to cause a problem (substantially at the time of one input operation), it is determined that there is capacitive coupling at two locations, so that the system becomes difficult to use.
For this reason, when discriminating only with this discrimination calculation method, the system configuration is such that it does not matter even if the position parallel to the X-axis and Y-axis directions cannot be discriminated, or different from this calculation method. It is necessary to make a judgment by using identification calculation and this together.

In order to calculate the coordinates, the number of detection electrodes needs to be set at least at all apexes of the resistive surrounding electrode, but more than that may be set. For example, in the case of an input panel having 8 detection electrodes in which the detection electrodes 21 to 24 are installed at the midpoints of the sides in addition to the detection electrodes 3 to 6 at the four vertices as shown in FIG. 2, the coordinates are calculated. In the above, since it can be considered to be the same as the case of the octagonal input panel, the coordinates can be calculated by the calculation method described in Patent Document 3.
Also, assuming that the measured current amounts of the detection electrodes 21 to 24 on the sides are I _E , I _F , I _G , and I _H , respectively, since the resistance value per side is constant, Equation 2 is expressed by Equation 3 Can be defined as

Next, a calculation formula of the identification calculation means different from the above method will be described.
It has been found that the current amount of the detection electrodes 21 to 24 on the side of FIG. 2 and the distance from the side where the detection electrode is located to the position where the conductor touches are not in a linear relational expression. For example, FIG. 3 shows the relationship between the current amount _IE measured by the detection electrode 21 and the distance from the detection electrode 21 to the finger at the position of the center line of the coordinate input area. Assuming that the same amount of current flows from the inflow points 41 to 45, assuming that the position farthest from the detection electrode 21 at the center line position of the coordinate input area is the inflow point 41 and the closest position is the inflow point 45, the inflow point is The closer to the detection electrode 21, the larger the current amount _IE , but the relational expression is not linear.
This is because the current amount _IE detected by the detection electrode 21 in a state where the capacitive coupling is received from two places, and one position of the coordinates calculated when the capacitive coupling is received from the two places. This means that the amount of current _IE detected by the detection electrode 21 when capacitive coupling is performed is different.
Using this phenomenon, it is possible to identify whether the detected coordinates have received capacitive coupling from two locations or whether they have received capacitive coupling from one location.

In the entire coordinate input region, the amount of current flowing through the detection electrode when capacitively coupled at one location is recorded in advance by the CPU 20, and when the coordinates are calculated, the amount of current flowing through the detection electrode is compared, It can be identified whether the capacitive coupling is performed at two locations or the capacitive coupling is performed at one location.
However, it is almost impossible to discriminate only with the current amount of the detection electrode on this side, particularly at a position near the apex of the resistive surrounding electrode, because a large amount of current flows through the detection electrode at the nearby apex. . Therefore, the value of the referenced to the detection electrode 21 for example S ₂ defined by the equation 4, the capacitive coupling in a state or two places that the capacitive coupling at one point on the coordinate input region Can be identified.

Formula 4 is a form in which the amount of current measured by the detection electrode on the side divided by the amount of current measured by the detection electrode at both ends of the side is added. Effective identification is possible in the entire area.
In addition, Formula 4 is large at a position near a certain side of the detection electrode 21 and is small at a position near the certain side of the detection electrode 23 on the opposite side, so that it is difficult to identify the position at a small value. Since the same can be said for the detection electrodes on each side, in order to enable identification in the entire coordinate input region, it is defined by Equation 5 from the relationship between the current amounts of the detection electrodes on the sides of the coordinate input region. it may be used a value of S _2.

The value of S ₂ Equation 5 when combined capacitance in one place is previously recorded in the CPU 20, when the coordinate calculations, to calculate the equation 5, the coordinates of which are calculated are prerecorded it can be identified by comparing the value of S _2.
In other words, performed simultaneously identification calculation and the calculation of coordinates, from the calculated coordinates, that the read value of S ₂ of the coordinate values from the CPU 20, compares the value of S ₂ value of S ₂ identification calculation result and CPU 20 In the case of the same value, there is one capacitive coupling in the coordinate input area. When the values are different, it can be identified that there are two capacitive couplings in the coordinate input area. At this time, even if there is one capacitive coupling due to the influence of noise or the like, the same value may not be obtained. Therefore, for example, it is necessary to set a threshold value such that ± 0.1 or less is the same value.

In addition, since Formula 5 shows the same value in the vertical and horizontal directions centered on the center of the panel when the coordinate input area is normalized, the range to be recorded in advance may be a quarter of the coordinate input area. . Further positions allowed to store may like 10mm intervals, for example the coordinate input region, the value of S ₂ when the capacitance coupling at one location when it is detected during the coordinates, the coordinates of the S ₂ value of around You may calculate from Since S ₂ is the ratio of the current amount, not changed by the strength of the bond, therefore, S ₂ during capacitive coupling one place to be stored may be a single type for the position to be stored.

Taking the difference between the case of two locations from the case of one portion of S ₂ in the formula 5, different signs in a positional relationship of the two points, as the distance between two points is away absolute value becomes large, The absolute value increases as the ratio of the coupling amounts of the two capacitances approaches 1: 1. However, when the positional relationship between the two points is on the same straight line parallel to the diagonal line of the rectangular coordinate input area, the capacitance coupling is very close to the case of one place and the case of two places. It becomes a difficult state attaches static identification, threshold adjustment of the same manner as in the case of S ₂ value equation 2, by a not without such a system configuration be indistinguishable in this direction issue, only equation 5 But it can be identified.

Also, there detecting electrode 8 points, when there is a detection electrode at a position of the midpoint of each side, for example, by a combination of S ₂ of S ₁ and Equation 5 Equation 3 identified formula, difficult to identify each Since the positional relationship between the two points can be supplemented, it is possible to more accurately identify whether the coordinate input area is in one or two places that are in contact with or close to each other with a conductor such as a finger.

By calculating Equation 5, it is possible to discriminate between one and two capacitive couplings in the entire coordinate input area. However, for example, only the upper part of the coordinate input area is identified due to the system configuration. For example, the detection electrode may be provided only on the upper side, and five detection electrodes may be provided, or the detection electrode may be provided on the left and right.
In addition, the detection electrode on the side does not need to be placed at the center of the side, but in consideration of the identification accuracy of the entire panel, it is desirable to install it at the midpoint of the side.

As shown in FIG. 4, when the detection points on the side are two at equal intervals, that is, a total of 12 detection electrodes are installed, the measured current amounts of the detection electrodes 3 to 6 at the four corners , I _A , I _B , I _C , I _D , and measured current amounts of the detection electrodes 31 to 38 on the sides, respectively, I _E , I _F , I _G , I _H , I _I , I _J , Assuming that I _K and I _L , Equation 5 can be defined as Equation 6.

Similarly to Expression 5, Expression 6 can also be used in combination with Expression 3 to perform identification calculation, whereby the case of one capacitive coupling and the case of two places can be identified. At this time, it is preferable that Equation 3 changes the coefficient of the current amount of the detection electrode on the side in accordance with the position of the detection electrode on the side.
The difference between one location and two locations of the values of S ₂ Equation 6, since a value greater than the difference between one location and two locations Equation 5 is obtained, hardly affected by disturbance such as noise from Equation 5 However, the number of detection electrodes increases, leading to an increase in cost.

Although the present invention has been described with respect to a rectangular coordinate input system, it does not necessarily have to be a rectangle. For example, even if an octagon is formed at a slight angle at the position of the detection electrode on the side, the identification accuracy However, the discrimination calculation described above can be used.

Hereinafter, the present invention will be described with reference to examples and comparative examples. The present invention is not limited to the following examples, and includes various modifications within the technical scope of the present invention.

Example 1
In the coordinate input system of this embodiment, a sheet resistor 1 having an ITO film formed on a square glass substrate is placed on a personal computer display, and a resistive peripheral electrode 2 provided to surround the sheet resistor 1 is And formed by screen printing of silver carbon ink. In order to increase durability, a protective layer was provided on the surface resistor 1 with a glass coating agent having a thickness of 0.5 mm. The detection electrodes were provided at the four apexes of the resistive surrounding electrode 2 and the midpoints of the respective sides, the lead wires were connected, and the detection electrodes were connected to the hardware created as shown in the configuration diagram shown in FIG. However, eight oscillation voltage application circuits 16 are used, and the analog multiplexer 18 capable of processing eight inputs is used so that the CPU 20 can switch the input channel.
When a plurality of buttons having a diameter of 20 mm are displayed in the coordinate input area from the personal computer and the operator's finger or palm touches or approaches the coordinate input area, the CPU 20 calculates the input coordinates by the method of Patent Document 2.
When the operator presses the button, depending on the pressing method, not only the finger but also the palm may be capacitively coupled to the surface resistor. That is, depending on how the button is pressed, there are two capacitive couplings in the coordinate input area, and coordinates that deviate from the position designated by the original finger may be calculated.
In this example, S ₁ according to Equation 3 and S ₂ according to Equation 5 were used in combination, and the threshold of S ₁ was set to ± 0.01 and the threshold of S ₂ was set to ± 0.5. If the threshold value is exceeded, it is determined that the coordinates are not accurate, and the operator is given accurate explanations by explaining the points to be noted (why they were not entered and the correct input method) and prompting them again. To be entered.
If it is below the threshold value, it is determined that the coordinates are accurate, and the coordinates are sent to the personal computer by serial communication. When the sent coordinates are within the coordinate area of the button on the display, the personal computer recognizes that the button has been pressed, and performs a function assigned to the button, such as turning on a light. If the sent coordinates are not within the coordinate area of the button, it is not recognized that the button has been pressed.

  In order to evaluate how correctly multiple operators randomly pressed the multiple button areas with their fingers and input them correctly, the recognition rate (number of times the button was recognized / number of times the operator pressed the button ) Was measured. As a result, the recognition rate was about 80%.

(Example 2)
As shown in FIG. 5, the detection electrodes on the resistive surrounding electrodes of the coordinate input system are installed in a total of seven locations, that is, detection electrodes 3 to 6 at four vertices and two detection electrodes 31 and 32 at equal intervals on the upper side. The identification calculation formula of the CPU 20 at this time is as follows: the measured current amounts of the detection electrodes 3 to 6 are I _A , I _B , I _C , I _D , and the detection electrodes 31 and 32 are I _E and I _F , respectively. Equations 7 and 8 can be defined. Otherwise, the configuration is the same as that of the first embodiment.

The same measurement as in Example 1 was performed using the system in Example 2 described above. As a result, the recognition rate differs between when the button placed at the top of the coordinate input area is pressed and when the button placed at the bottom is pressed, about 80% at the top and about 30% at the bottom. It was. When the button arranged at the lower part is pressed, even if the coordinates are shifted due to the influence of the palm, the thresholds of S ₁ and S ₂ are satisfied, so that the coordinates are not determined to be accurate. On the other hand, the personal computer does not recognize that the button has been pressed because the coordinates received are not within the coordinate area of the button. However, since the message was not displayed, the operator was unaware of the situation, and it turned out that the recognition rate was low as a result of pressing the button many times.

(Example 3)
Only four vertices are detected on the resistive peripheral electrode of the coordinate input system, and the identification calculation of the CPU 20 is only Expression 2. Otherwise, the configuration is the same as that of the first embodiment.
Using the system of Comparative Example 1 above, the same measurement as in Example 1 was performed. As a result, the recognition rate varies depending on the position where the buttons are arranged, and is about 70% to 30%. This positional relationship between the two points in the identification of only S ₁ by Equation 2, i.e. parallel positional relationship of the hand and the palm is the Y-axis or, in the case of position parallel to the X axis, the S ₁ value This is because it becomes a value close to 0, and it is difficult to distinguish between the case of one capacitive coupling and the case of two capacitive couplings.

(Comparative Example 1)
The detection electrodes on the resistive surrounding electrodes of the coordinate input system have only four vertices, and the CPU 20 sends the input coordinates to the personal computer without performing identification calculation. Otherwise, the configuration is the same as that of the first embodiment.
Using the system of Comparative Example 1 above, the same measurement as in Example 1 was performed. As a result, the recognition rate was about 20%. This is the same as the button arranged at the bottom of the second embodiment. Even when the coordinates are shifted due to the influence of the palm, it is not determined that the coordinates are accurate, so the operator repeatedly presses the button. As a result, it was found that the recognition rate was low. In addition, troubles such as the response of a button different from the button indicated by the operator occurred.

(Comparative Example 2)
The detection electrodes on the resistive surrounding electrodes of the coordinate input system have only four vertices, and the CPU 20 sends the input coordinates to the personal computer without performing identification calculation. And the protective layer on the surface resistor 1 shall not be provided. Otherwise, the configuration is the same as that of the first embodiment.
Using the system of Comparative Example 1 above, the same measurement as in Example 1 was performed. As a result, the recognition rate was about 90% at first, but continued to fall gradually to about 10%. This is because the portion of the ITO film on the surface resistor 1 touched by the finger was damaged during use, and the surface resistor did not become a uniform surface resistor, and the coordinates of that portion could not be detected accurately. There was found.

The system according to the first embodiment is a system that has good recognition rate and durability over the entire coordinate input area. If the buttons are arranged only on the upper part, the system according to the second embodiment may be used. It can be said that the system has good recognition rate and durability.
In comparison, the system of Comparative Example 1 is a system that has good durability but a low recognition rate, and has a false detection such as pressing a different button. The system of Comparative Example 2 has a good recognition rate. However, it is a system with poor durability. From the above, it was confirmed that the present invention is effective.

Configuration diagram showing an example of a coordinate input system Configuration diagram showing an example of installation positions when there are 8 detection electrodes The figure which shows the amount of detection of the amount of current of the detection electrode on the side and the position of the current inflow point The block diagram which shows an example of the installation position in case a detection electrode is 12 points | pieces The figure which shows the position of the detection electrode of Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface resistor 2 Resistive surrounding electrode 3, 4, 5, 6 Detection electrode 7 Finger 8, 9, 10, 11 Lead line 12 Coordinate input area 15 Analog signal processing part 16 Vibration voltage application circuit 17 Vibration voltage generator 18 Analog Multiplexer 19 A / D converter 20 CPU
21, 22, 23, 24 Detection electrode 31, 32, 33, 34, 35, 36, 37, 38 Detection electrode 41, 42, 43, 44, 45 Current inflow point

Claims (1)

A rectangular resistive surrounding electrode in which the resistance value per length of each side is constant within each side around or inside the surface resistor formed on the insulating substrate, and all sides are electrically connected to the above-mentioned surface resistor. A coordinate input system in which the inside of the resistive surrounding electrode is a coordinate input area, and the resistive surrounding when the coordinate input area is in contact with or close to a conductor such as a finger. A detection electrode for measuring a current flowing through at least all the vertices of the electrode; a coordinate calculation means for calculating a position of the coordinate input area in contact with or close to the conductor from a current value measured by the detection electrode; and A coordinate input system comprising: an identification calculation means for identifying whether the coordinate input area is in contact with or close to the coordinate input area with the conductor from one or two positions based on a measured current value.

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