JP4308694B2 - Coordinate detection apparatus and coordinate detection method - Google Patents

Description

  The present invention relates to a coordinate detection device and a coordinate detection method, and in particular, applies a voltage between a pair of wiring patterns formed on a substrate on which a resistance film and a pair of wiring patterns arranged in parallel with each other on the resistance film are formed. Thus, the present invention relates to a coordinate detection apparatus and a coordinate detection method for detecting a potential at a contact position with a resistance film in a state where a potential difference is generated in the resistance film, and detecting coordinates of the contact position according to the detected potential.

  In an information processing system or the like, various input methods such as devices such as a keyboard and a mouse have been proposed as input means for inputting data and commands, etc. As one of input methods, a touch panel has been proposed in which various inputs can be made by directly touching a screen displayed on a display.

  FIG. 1 is a diagram for explaining the detection principle of a touch panel. FIG. 1A shows the operation when the X coordinate is detected, and FIG. 1B shows the operation when the Y coordinate is detected.

  The touch panel 1 includes a lower glass substrate 2 and an upper film substrate 3. On the lower glass substrate 2, a transparent resistive film such as ITO is formed over the entire surface. Furthermore, electrodes 4 and 5 are formed on the transparent conductive film substantially parallel to both ends in the Y-axis direction.

  A transparent resistance film such as ITO is formed on the upper film substrate 3 over the entire surface. Furthermore, electrodes 6 and 7 are formed on the transparent resistance film substantially parallel to both ends in the X-axis direction.

  When the X-axis coordinate is detected by the touch panel 1, a voltage Vcc is applied between the electrode 6 and the electrode 7 of the upper film substrate 3 as shown in FIG. At this time, when the coordinates (x1, y1) on the touch panel 1 are pressed by the pen 8, the transparent resistance film of the lower glass substrate 2 and the transparent resistance film of the upper film substrate 3 come into contact with each other at the coordinates (x1, y1). . As a result, the potential Vsx at the X coordinate x1 of the transparent resistance film of the upper film substrate 3 is detected through the resistance film of the lower glass substrate 2. The X coordinate x1 is recognized by the detection potential Vsx.

  When the Y-axis coordinate is detected by the touch panel 1, a voltage Vcc is applied between the electrode 4 and the electrode 5 of the lower glass substrate 2 as shown in FIG. At this time, when the coordinates (x1, y1) on the touch panel 1 are pressed by the pen 8, the transparent resistance film of the lower glass substrate 2 and the transparent resistance film of the upper film substrate 3 come into contact with each other at the coordinates (x1, y1). . As a result, the potential Vsy at the Y coordinate y1 of the transparent resistance film of the lower glass substrate 2 is detected through the resistance film of the upper film substrate 3. The Y coordinate y1 is recognized by the detection potential Vsy.

  As described above, in the touch panel 1, a voltage is applied to the resistance film through the electrodes 6, 7 or the electrodes 4, 5 and the wiring pattern. At this time, if the electrodes 6, 7 or the electrodes 4, 5 and the wiring pattern are to be thinned for narrowing the frame, the electrodes 6, 7 or the electrodes 4, 5 and the wiring pattern have a high resistance and a relatively transparent resistance. Since the voltage applied to the film decreases, the detection accuracy decreases. For this reason, it is necessary to keep the electrodes 6 and 7 or the electrodes 4 and 5 and the wiring pattern at a low resistance.

In this type of coordinate input device, the influence of resistors other than the resistance film such as wiring is large, and in order to improve the coordinate detection accuracy, in the two resistive film analog type touch panels provided in the quadrilateral, the voltage adjustment circuit and the error In order to eliminate the need for correction calculation, a pair of auxiliary electrodes is provided on each resistive film, and a voltage is applied to the pair of auxiliary electrodes to detect the pressed coordinate position in the X and Y directions, and wiring and switches outside the operation area A proposal has been made to reduce the influence of a voltage drop caused by an element (Patent Document 1).
In addition, a proposal has been made that a stripe-shaped auxiliary electrode parallel to the electrode is provided on the surface resistance sheet surface to correct a deviation between an actual input point and output coordinate data (Patent Document 2).

Japanese Utility Model Publication No. 05-004256 JP 62-184521 A

  However, in the coordinate input device that performs coordinate input using the auxiliary electrode, there is a problem that the microcomputer needs to detect the potential of the auxiliary electrode in addition to the detection potential, which increases the load on the microcomputer.

  In addition, in a coordinate input device in which a striped auxiliary electrode parallel to the electrode is provided on the surface resistance sheet surface, it is necessary to detect the potential independently from the striped auxiliary electrode, which makes wiring and switching complicated. There was a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a coordinate input apparatus capable of detecting coordinates with high accuracy and having a narrow frame with a simple configuration.

The present invention includes a resistive film disposed on the resistive film, to apply a potential to the resistive film, the substrate and the conductive pattern for detecting potential the resistance film is formed, a voltage between said conductive pattern In a coordinate input device having detection means for detecting the potential of the contact position with the resistance film in a state where the resistance film is applied and generating a potential difference in the resistance film, and detecting the coordinates of the contact position according to the potential, The conductive pattern is composed of a set of wiring patterns, one end of which is connected to each other and the other end of which is provided with a connection pad, and which is wired in parallel to each other. The pattern resistance detection detects the resistance of the conductive pattern. And correction means for correcting the relationship between the contact potential and the coordinate position in accordance with the resistance value of the wiring pattern detected by the pattern resistance detection means.

According to the present invention, in order to detect resistance of a conductive pattern, the conductive pattern is connected to one end of the conductive pattern, the other end is provided with the connection pad, and the wiring pattern is connected in parallel to each other. By configuring, coordinate detection is performed in consideration of the resistance component of the conductive pattern, that is, the resistance of the wiring pattern is detected, and the relationship between the contact potential and the coordinate position is corrected according to the detected resistance value of the wiring pattern By doing so, coordinate detection can be performed only with the resistance of the resistance film from which the resistance of the wiring pattern has been removed, so that the coordinate position can be detected with high accuracy. Further, the resistance of the wiring pattern is removed, and the resistance of the wiring pattern can be increased. Therefore, since the wiring pattern can be thinned, the touch panel can be narrowed. Furthermore, the current flowing through the resistance film can be reduced by increasing the resistance of the wiring pattern, which contributes to lower power consumption.

〔overall structure〕
FIG. 2 shows a perspective view of one embodiment of the present invention.

  The touch panel 10 according to the present embodiment includes a touch panel body 11, a connection cable 12, and a controller 13.

  The touch panel body 11 has a structure in which an upper film substrate 22 is laminated on a lower glass substrate 21 with a slight gap. The touch panel body 11 is connected to the controller 13 via the connection cable 12. The connection cable 33 is composed of an FPC (Flexible Printed Circuit) board, one end is connected to the touch panel body 31, and the other end is connected to the controller 32, and a drive voltage is supplied from the controller 13 to the touch panel body 11. At the same time, it is used as a signal transmission path for supplying a detection signal from the touch panel body 11 to the controller 13.

  The controller 13 supplies a driving voltage to the touch panel body 11 to perform a process of detecting a wiring resistance, generates input coordinate information according to a detection signal supplied from the touch panel body 11, and supplies the input coordinate information to a host device (not shown). .

[Touch panel body 11]
FIG. 3 is an exploded perspective view of the touch panel body 11.

  The touch panel body 11 has a configuration in which a lower glass substrate 21 and an upper film substrate 22 are bonded to each other with a double-sided adhesive 23 or the like sandwiched therebetween and laminated with a slight gap.

[Lower glass substrate 21]
FIG. 4 shows a configuration diagram of the lower glass substrate 21. 4A shows a top view and FIG. 4B shows a side view.

  The lower glass substrate 21 includes a glass substrate 31, a transparent resistance film 32, conductive patterns 33 to 38, and an insulating film 39. The glass substrate 31 is made of a transparent and plate-like glass material. The transparent resistance film 32 is made of a transparent conductive material such as ITO (Indium-Tin-Oxide), and is formed over substantially the entire upper surface of the glass substrate 31.

  The conductive pattern 33 is composed of two wiring patterns 33a and 33b. The two wiring patterns 33a and 33b are formed in parallel to each other, and have a pattern shape in which one end is short-circuited and the other end is opened. The wiring pattern 33a is formed on the inner peripheral side with respect to the wiring pattern 33b, and includes an electrode portion 33a-1 and a wiring portion 33a-2. The electrode portion 33a-1 is formed in the vicinity of the side in the arrow Y1 direction of the glass substrate 31 so as to extend in the arrow X1 and X2 directions.

  At this time, the electrode portion 33 a-1 is a conductive pattern for applying a voltage to the transparent resistance film 32, and is formed directly on the transparent resistance film 32. The wiring part 33a-2 and the wiring pattern 33b of the wiring pattern 33a are wiring patterns for guiding the electrode part 33a to the connection part with the connection cable 12, and are formed on the transparent resistance film 32 via the insulating film 39. Yes.

  The conductive pattern 34 is composed of two wiring patterns 34a and 34b. The two wiring patterns 34a and 34b are formed in parallel to each other, and have a pattern shape in which one end is short-circuited and the other end is opened. The wiring pattern 34a is formed on the lower glass substrate 21 on the inner peripheral side from the wiring pattern 34b, and is composed of an electrode part 34a-1 and a wiring part 34a-2. The electrode portion 34a-1 is formed in the vicinity of the side in the arrow Y2 direction of the glass substrate 31 so as to extend in the arrow X1 and X2 directions. At this time, the electrode portion 34 a-1 is a conductive pattern for setting the transparent resistance film 32 to the ground potential, and is formed directly on the transparent resistance film 32. Further, the wiring part 34a-2 and the wiring pattern 34b of the wiring pattern 34a are wiring patterns for guiding the electrode part 34a-1 to the connection part with the connection cable 12, and the insulating film 39 is interposed on the transparent resistance film 32. Is formed.

  The conductive pattern 35 is a wiring pattern for connecting the upper film substrate 22 and the connection cable 12, and includes a connection pad 35 a and a wiring pattern 35 b. The wiring pattern of the upper film substrate 22 is connected to the connection pad 35a. The connection pad 35a is led to a portion where the connection cable 12 on the lower glass substrate 21 is connected by the wiring pattern 35b.

  The conductive pattern 36 is a wiring pattern for connecting the upper film substrate 22 and the connection cable 12, and includes a connection pad 36 a and a wiring pattern 36 b. The wiring pattern of the upper film substrate 22 is connected to the connection pad 36a. The connection pad 36a is led to a portion where the connection cable 12 on the lower glass substrate 21 is connected by the wiring pattern 36b.

  The conductive pattern 37 is a wiring pattern for connecting the upper film substrate 22 and the connection cable 12, and includes a connection pad 37 a and a wiring pattern 37 b. The wiring pattern of the upper film substrate 22 is connected to the connection pad 37a. The connection pad 37a is led to a portion where the connection cable 12 on the lower glass substrate 21 is connected by the wiring pattern 37b.

  The conductive pattern 38 is a wiring pattern for connecting the upper film substrate 22 and the connection cable 12, and includes a connection pad 38 a and a wiring pattern 38 b. The wiring pattern of the upper film substrate 22 is connected to the connection pad 38a. The connection pad 38a is led to a portion where the connection cable 12 on the lower glass substrate 21 is connected by the wiring pattern 38b.

  The lower glass substrate 21 extends from the upper film substrate 22 in the direction of the arrow X1, and the connection portion 12 is connected to the extended portion.

[Upper film substrate 22]
FIG. 5 shows a configuration diagram of the upper film substrate 22. 5A is a bottom view and FIG. 5B is a side view.

  The upper film substrate 22 includes a film substrate 41, a transparent resistance film 42, conductive patterns 43 and 44, and an insulating film 45. The film substrate 41 is made of a transparent resin material such as PET. The transparent resistance film 42 is made of a transparent conductive material such as ITO (Indium-Tin-Oxide), and is formed over substantially the entire upper surface of the film substrate 41.

  The conductive pattern 43 is composed of two wiring patterns 43a and 43b. The two wiring patterns 43a and 43b are formed in parallel to each other, and have a pattern shape in which one end is short-circuited and the other end is opened. The wiring pattern 43a is formed on the upper film substrate 22 on the inner peripheral side from the wiring pattern 43b, and includes an electrode portion 43a-1, a wiring portion 43a-2, and a connection pad 43a-3. The electrode portion 43a-1 is formed in the vicinity of the side in the arrow X2 direction of the film substrate 41 so as to extend in the directions of arrows Y1 and Y2.

  At this time, the electrode portion 43 a-1 is a conductive pattern for applying a voltage to the transparent resistance film 42, and is formed directly on the transparent resistance film 42. The wiring part 43a-2 of the wiring pattern 43a is a wiring pattern for guiding one end of the electrode part 43a-1 to the connection pad 43a-3, and is formed on the insulating film 45.

  The wiring pattern 43b includes a wiring part 43b-1 and a connection pad 43b-2. The wiring part 43b-1 is a wiring pattern for guiding the other end of the electrode part 43a-1 to the connection pad 43b-2, and is formed on the insulating film 45.

  The conductive pattern 44 is composed of two wiring patterns 44a and 44b. The two wiring patterns 44a and 44b are formed in parallel to each other, and have a pattern shape in which one end is short-circuited and the other end is opened. The wiring pattern 44a is formed on the upper film substrate 22 on the inner peripheral side with respect to the wiring pattern 44b, and includes an electrode portion 44a-1, a wiring portion 44a-2, and a connection pad 44a-3.

  The electrode portion 44a-1 is formed in the vicinity of the side in the arrow X1 direction of the film substrate 41 so as to extend in the directions of arrows Y1 and Y2. At this time, the electrode portion 44 a-1 is a conductive pattern for applying a voltage to the transparent resistance film 42, and is formed directly on the transparent resistance film 42. The wiring portion 44a-2 of the wiring pattern 44a is a wiring pattern for connecting one end of the electrode portion 44a-1 to the connection pad 44a-3, and is formed on the insulating film 45. The wiring pattern 44b is a wiring pattern for connecting the other end of the electrode portion 44a-1 to the connection pad 44b-2, and is formed on the insulating film 45.

  The connection pad 43 a-3 is connected to the connection pad 35 a so as to face the connection pad 35 a of the lower glass substrate 21 when the upper film substrate 22 is laminated on the lower glass substrate 21. The connection pad 43b-2 faces the connection pad 36a of the lower glass substrate 21 when the upper film substrate 22 is laminated on the lower glass substrate 21, and is connected to the connection pad 36a.

  The connection pad 44a-3 faces the connection pad 38a of the lower glass substrate 21 when the upper film substrate 22 is laminated on the lower glass substrate 21, and is connected to the connection pad 38a. The connection pad 44b-2 faces the connection pad 37a of the lower glass substrate 21 when the upper film substrate 22 is laminated on the lower glass substrate 21, and is connected to the connection pad 37a.

[Controller 13]
FIG. 6 is a block diagram of the touch panel 1.

  As shown in FIG. 1, the controller 13 has a configuration in which an electronic component 52, connectors 53 and 54, etc. are mounted on a printed wiring board 51. The connection cable 12 is connected to the connector 53, and the host device is connected to the connector 54.

  The controller 13 includes a switching circuit 61, an input amplifier 62, a microcomputer 63, and an output amplifier 64 as shown in FIG. The switching circuit 61 is configured by a switching element such as a transistor, and switches connection between both ends of the conductive patterns 33 and 34 of the touch panel body 11 and one end of the conductive patterns 35 to 38 according to a switching control signal from the microcomputer 63.

  The microcomputer 63 is connected to the switching circuit 61, and controls the switching circuit 61 to switch the connection between both ends of the conductive patterns 33 and 34 of the touch panel main body 11 and one end of the conductive patterns 35 to 38, thereby conducting the conductive pattern 33. The resistance value R33 of the conductive pattern 34, the resistance value R43 of the conductive patterns 35, 43, 36, the resistance value R44 of the conductive patterns 37, 44, 38 are calculated, and the calculated resistance values R33, R34, R43, The detected coordinates are corrected based on R44.

[Operation]
Next, the processing operation of the microcomputer 63 will be described.

[Overall operation]
FIG. 7 shows a process flowchart of the microcomputer 63.

  When the power is turned on in step S1-1, the microcomputer 63 calculates the resistance values R33, R34, R43, and R44 of the conductive patterns 33 to 38, 43, and 44 in step S1-2, and calculates the calculated resistance value R33. , R34, R43, and R44 are performed to correct the detected coordinates.

  After completing the correction process, the microcomputer 63 performs a normal coordinate detection process in step S1-3. If the power source is not turned off in step S1-4, the microcomputer 63 determines whether or not a predetermined time has elapsed in step S1-5. When the predetermined time has elapsed, the microcomputer 63 returns to step S1-2 and performs the correction process again. . When the power is turned off in step S1-5, the process ends.

  As described above, the correction process can be performed when the power is turned on and every predetermined time. Thereby, the microcomputer 63 can perform coordinate detection in consideration of the resistance of the conductive patterns 33 to 38, 43, and 44 during the coordinate detection process. For this reason, coordinate detection accuracy can be improved.

[Correction process]
FIG. 8 shows a process flowchart of the correction process by the microcomputer 63.

  The microcomputer 63 obtains the resistance values of the conductive patterns 33 to 38, 43, and 44 in step S2-1.

  Here, a method for obtaining the resistance value R33 of the conductive pattern 33 by the microcomputer 63 will be described.

When the microcomputer 63 detects the resistance value of the conductive pattern 33, for example, the power supply voltage Vcc is applied to one end of the conductive pattern 33 and the other end is grounded via a built-in detection resistor, and the conductive pattern 33 and the detection resistor are detected. The switching circuit 61 is controlled so that the potential at the connection point is applied to the microcomputer 63. The potential at the connection point between the conductive pattern 33 and the detection resistor is a potential corresponding to the current flowing through the conductive pattern 33. Here, when the potential of the connection point between the conductive pattern 33 and the detection resistor is Vs and the detection resistor is Rs,
The current Is flowing through the detection resistor Rs is
Is = Vs / Rs (1)
Is required.

  At this time, if the current flowing through the microcomputer 63 is substantially zero, the detection current Is becomes the current flowing through the conductive pattern 33.

At this time, a voltage (Vcc−Vs) is applied to the conductive pattern 33.
Therefore, the resistance R33 of the conductive pattern 33 is
R33 = (Vcc-Vs) / Is = (Vcc-Vs) / (Vs / Rs)
= {(Vcc / Vs) -1} Rs (2)
Is required. At this time, since the power supply voltage Vcc and the detection resistor Rs are known, the microcomputer 63 can calculate the resistance value R33 of the conductive pattern 33 from the detection voltage Vs.

  Similarly, the resistance values R34, R43, and R44 of the conductive pattern 34, the conductive patterns 35, 43, and 36, and the conductive patterns 37, 44, and 38 can be detected.

  Next, the microcomputer 63 detects the total resistance RX1 in the X-axis direction in step S2-2.

  Here, a method for obtaining the total resistance RX1 in the X-axis direction will be described.

  When the microcomputer 63 detects the total resistance RX1 in the X-axis direction, for example, the power supply voltage Vcc is applied to the conductive pattern 35, the conductive pattern 38 is grounded via the detection resistor Rs, and the conductive pattern 38 and the detection resistor The switching circuit 61 is controlled so that the connection point with Rs is supplied to the microcomputer 63 via the input amplifier 62.

At this time, the potential at the connection point between the conductive pattern 38 and the detection resistor Rs supplied to the microcomputer 63 via the input amplifier 62 passes through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38. It becomes a potential according to the flowing current. Here, when the potential at the connection point between the conductive pattern 33 and the detection resistor is Vxas and the detection resistor is Rs,
The current Ixas flowing through the detection resistor Rs is
Ixas = Vxas / Rs (3)
Is required.

  At this time, if the current flowing through the microcomputer 63 is substantially zero, the detected current Ixas is a current that flows through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38.

  At this time, a voltage (Vcc−Vxas) is applied to a path that penetrates the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38.

Therefore, the resistance RX1 of the path passing through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38 is
RX1 = (Vcc-Vxas) / Ias = (Vcc-Vxas) / (Vxas / Rs)
= {(Vcc / Vxas) -1} Rs (4)
Is required. At this time, since the power supply voltage Vcc and the detection resistor Rs are known, the microcomputer 63 can calculate the resistance RX1 of the path passing through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38 from the detection voltage Vas. .

  Next, the microcomputer 63 calculates a resistance value R42 between the electrodes 43a-1 and 44a-1 in the X-axis direction of the transparent resistance film 42 in step S2-3. The resistance value R42 can be obtained from the resistance RX1 and the wiring resistances R43 and R44 of the path passing through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38 from the detection voltage Vas.

  Here, when coordinates are detected, no voltage is applied to the wiring pattern 36b of the conductive pattern 36, and the circuit is opened. For this reason, at the time of coordinate detection, the current is supplied from the conductive pattern 35 to the transparent resistance film 42 through the wiring pattern 43a.

At this time, the wiring pattern 43a and the wiring pattern 43b, and the conductive pattern 35 and the conductive pattern 36 are formed in parallel to each other and have substantially the same resistance value. Therefore, the resistance value of the path passing through the wiring pattern 43a and the conductive pattern 35 becomes a resistance value (R43 / 2) that is half of the resistance value R43.

Similarly, the resistance value of the path passing through the wiring pattern 44a and the conductive pattern 38 is half the resistance value R44 (R44 / 2).

Therefore, the resistance value R42 between the electrode 43a-1 and the electrode 44a-1 in the X-axis direction of the transparent resistance film 42 is
R42 = RX1- (R43 / 2)-(R44 / 2) (5)
It can be calculated from

  Next, the microcomputer 63 detects the total resistance RY1 in the Y-axis direction in step S2-4.

  Here, a method for obtaining the total resistance RY1 in the Y-axis direction will be described.

  When the microcomputer 63 detects the total resistance RY1 in the Y-axis direction, for example, the power supply voltage Vcc is applied to the wiring pattern 33a, the wiring pattern 34a is grounded via the detection resistance Rs, and the wiring pattern 34a and the detection resistance are detected. The switching circuit 61 is controlled so that the connection point with Rs is supplied to the microcomputer 63 via the input amplifier 62.

At this time, the potential at the connection point between the wiring pattern 34a and the detection resistor Rs supplied to the microcomputer 63 via the input amplifier 62 depends on the current flowing through the wiring pattern 33a, the transparent resistance film 32, and the conductive pattern 34a. Potential. Here, when the potential at the connection point between the conductive pattern 34a and the detection resistor Rs is Vyas and the detection resistor is Rs,
The current Iyas flowing through the detection resistor Rs is
Iyas = Vyas / Rs (6)
Is required.

  At this time, if the current flowing through the microcomputer 63 is substantially zero, the detected current Iyas is a current that flows through the conductive pattern 33a, the transparent resistance film 32, and the conductive pattern 34a.

  At this time, a voltage (Vcc-Vyas) is applied to the path passing through the conductive pattern 33a, the transparent resistance film 32, and the conductive pattern 34a.

Therefore, the resistance RY1 of the path passing through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38 is
RY1 = (Vcc-Vyas) / Iyas = (Vcc-Vyas) / (Vyas / Rs)
= {(Vcc / Vyas) -1} Rs (7)
Is required. At this time, since the power supply voltage Vcc and the detection resistor Rs are known, the microcomputer 63 can calculate the resistance RX1 of the path passing through the conductive patterns 35 and 43, the transparent resistance film 42, and the conductive patterns 44 and 38 from the detection voltage Vas. .

  Next, the microcomputer 63 calculates a resistance value R32 between the electrode 33a-1 and the electrode 34a-1 in the Y-axis direction of the transparent resistance film 32 in step S4-5. The resistance value R32 can be obtained from the detection voltage Vyas from the resistance RY1 and the wiring resistances R33 and R34 in the path passing through the conductive pattern 33a, the transparent resistance film 32, and the conductive pattern 34a.

  Here, when the coordinates are detected, no voltage is applied to the wiring pattern 33b, and the circuit is opened. For this reason, at the time of coordinate detection, the current is supplied to the transparent resistance film 32 through the wiring pattern 33b.

At this time, the wiring pattern 33a and the wiring pattern 33b are formed in parallel to each other and have substantially the same resistance value. Therefore, the resistance value of the wiring pattern 33a is half the resistance value R33 (R33 / 2).

Similarly, the resistance value of the path passing through the wiring pattern 34a is half the resistance value R34 (R34 / 2).

Therefore, the resistance value R32 between the electrode 33a-1 and the electrode 34a-1 in the X-axis direction of the transparent resistance film 32 is
R32 = RY1- (R33 / 2)-(R34 / 2) (8)
It can be calculated from

  The microcomputer 63 creates a coordinate information table in step S2-6.

  FIG. 9 shows the data structure of the coordinate information table. FIG. 9A shows an X coordinate information table, and FIG. 9B shows a Y coordinate information table.

  The X coordinate information table shown in FIG. 9A is a table in which X coordinate information DX0 to DXn corresponding to the X coordinate detection voltages VX0 to VXn is stored.

  The X coordinate information table shown in FIG. 9B is a table in which X coordinate information DY0 to DYn corresponding to the Y coordinate detection voltages VY0 to VYn is stored.

  The microcomputer 63 updates the X coordinate information table shown in FIG. 9A based on the conductive patterns 35, 43, 36, the conductive patterns 37, 44, 38 and the resistance values R43, R44, R42 of the transparent resistance film 42. Further, the microcomputer 63 updates the Y coordinate information table shown in FIG. 9B based on the resistance values R33, R34, and R32 of the conductive pattern 33, the conductive pattern 34, and the transparent resistance film 32.

  Here, a method for updating the X coordinate information table will be described.

  FIG. 10 is a diagram for explaining a method of updating the X coordinate information table.

When the X coordinate is detected, a circuit configuration in which resistance values (R43 / 2), R42, and (R44 / 2) are connected in series between the power supply voltage Vcc and the ground as shown in FIG. The current IX0 flowing through this series circuit is
IX0 = {(R43 / 2) + R42 + (R44 / 2)} / Vcc (9)
Is required.

The potential VXn at the connection point between the transparent resistance film 42 and the conductive pattern 43 is:
VXn = Vcc- (R43 / 2) * IX0 (10)
It can be calculated from At this time, IX0 can be calculated from the known power supply voltage Vcc and the resistance values R42, R43, and R44 from the equation (9), so the equation (10) can also be calculated from the known power supply voltage Vcc and the resistance values R42, R43, and R44. Therefore, the maximum value of the detected potential of the X coordinate in the transparent conductive film 42 can be obtained from Expression (10). The voltage VXn obtained by the equation (10) is set as the maximum detected voltage in the X coordinate information table, and the maximum X coordinate information DXn is associated with the voltage VXn.

The potential VX0 at the connection point between the transparent resistance film 42 and the conductive pattern 44 is
VX0 = Vcc-{(R43 / 2) + R42} * IX0 (11)
It can be calculated from From Equation (11), the minimum value of the detected potential of the X coordinate on the transparent conductive film 42 can be obtained. The voltage VX0 obtained by the equation (11) is set as the minimum detection voltage in the X coordinate information table, and the minimum X coordinate information DX0 is made to correspond to the voltage VX0.

Further, the voltage V0 applied to the transparent resistance film 42, that is, the resistance value R42, can be calculated from the equation (9) as follows:
It can be calculated from

  By dividing the voltage V0, the detection voltages VX1 to VXn-1 set in the X coordinate information table are obtained, and the X coordinate information DX0 to DXn is obtained by dividing the obtained detection voltages VX1 to VXn-1. X coordinate information DX1 to DXn-1 is set.

  Thus, the X coordinate information table is obtained.

  Similarly, the Y coordinate information table can be updated.

  The coordinate detection process is executed with reference to the X coordinate information table and the Y coordinate information table obtained as described above.

[Coordinate detection processing]
FIG. 11 shows a process flowchart of the coordinate detection process.

  When the touch panel body 11 is operated in step S3-1, the microcomputer 63 controls the switching circuit 61 in step S3-2 to apply the power supply voltage Vcc between the conductive pattern 36 and the conductive pattern 38, thereby The potential of the wiring pattern 33a of the pattern 33 is detected. The microcomputer 63 acquires X coordinate information corresponding to the detected potential with reference to the X coordinate information table shown in FIG.

  Next, the microcomputer 63 controls the switching circuit 61 in step S3-3 to apply the power supply voltage Vcc between the electrode portion 33a of the conductive pattern 33 and the electrode 34a of the conductive pattern 34, and the potential of the conductive pattern 36. Is detected. The microcomputer 63 acquires Y coordinate information corresponding to the detected potential with reference to the Y coordinate information table shown in FIG. 9B in step S3-4.

  Next, the microcomputer 63 sends the acquired X coordinate information and Y coordinate information to the host device through the output amplifier 64.

〔effect〕
According to the present embodiment, since the influence of the conductive pattern can be removed, coordinate detection can be performed with high accuracy.

  Further, in this embodiment, it is only necessary to form a pattern capable of detecting the resistance of the conductive pattern, so that the configuration such as pattern and switching can be easily performed.

  In addition, even when the conductive pattern has a high resistance, the coordinates can be detected by removing the influence of the resistance of the conductive pattern, so that the conductive pattern can be thinned, and the touch panel body 11 is narrowed. Can be framed. Furthermore, current consumption can be reduced by increasing the resistance of the conductive pattern.

[Others]
Note that the shape of the conductive pattern of this embodiment is not limited as long as the resistance value of the conductive pattern can be obtained.

  In the present embodiment, the conductive patterns 33 and 34 for detecting the Y coordinate are formed on the lower glass substrate 21 and the conductive patterns 43 and 44 for detecting the X coordinate are formed on the upper film substrate 22. The conductive patterns 33 and 34 and the X coordinate detection conductive patterns 43 and 44 are formed on the lower glass substrate 21, and the coordinates are detected by detecting the potential of the contact position from the transparent resistance film 42 of the upper film substrate 22. The method may be applied to a touch panel.

  In this embodiment, the X coordinate information table and the Y coordinate information table are changed based on the resistance values of the conductive patterns 33 to 38, 43, and 44. However, the power supply voltage Vcc applied thereto is changed to the transparent resistance film 32, You may make it correct | amend so that the voltage applied to 42 may become fixed.

It is a figure for demonstrating the detection principle of a touch panel. It is a perspective view of one Example of this invention. 2 is an exploded perspective view of a touch panel body 11. FIG. 2 is a configuration diagram of a lower glass substrate 21. FIG. 3 is a configuration diagram of an upper film substrate 22. FIG. 2 is a block configuration diagram of the touch panel 1. FIG. It is a process flowchart of the microcomputer 63. FIG. 6 is a processing flowchart of correction processing by a microcomputer 63; It is a data block diagram of a coordinate information table. It is a figure for demonstrating the update method of a X coordinate information table. It is a process flowchart of a coordinate detection process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Touch panel 11 Touch panel main body, 12 Connection cable, 13 Controller 21 Lower glass substrate, 22 Upper film substrate 31 Glass substrate, 32 Transparent resistance film, 33-38 Conductive pattern 39 Insulating film 41 Film substrate, 42 Transparent resistance film, 43, 44 Conductive pattern 51 Printed wiring board, 52 Electronic component, 53, 54 Connector 61 Switching circuit, 62 Input amplifier, 63 Microcomputer, 64 Output amplifier

Claims (3)

And resistive film, is disposed on the resistive film, to apply a potential to the resistive film, the substrate and the conductive pattern for detecting potential the resistance film is formed, a voltage between the conductive pattern is applied, the In a coordinate input device having detection means for detecting the potential of the contact position with the resistance film in a state where a potential difference is generated in the resistance film, and detecting the coordinates of the contact position according to the potential,
The conductive pattern is composed of a set of wiring patterns, one end of which is connected to each other, the other end of which is provided with a connection pad, and which is wired in parallel to each other.
Pattern resistance detection means for detecting the resistance of the conductive pattern;
A coordinate input device comprising correction means for correcting the relationship between the contact potential and the coordinate position in accordance with the resistance value of the wiring pattern detected by the pattern resistance detection means. The correction means applies a constant voltage between the other end of the wiring pattern and the other end of the detection wiring pattern, detects a current flowing between the wiring pattern and the detection wiring pattern, and coordinate input apparatus according to claim 1, wherein the detecting the resistance of the wiring pattern according to the detected current. Path resistance detecting means for detecting a path resistance on a path from one wiring pattern of the set of wiring patterns constituting the conductive pattern to the other wiring pattern through the resistance film;
The correction means detects the resistance of the resistance film based on the path resistance detected by the path resistance detection means and the pattern resistance detected by the pattern resistance detection means, and the contact potential based on the resistance of the resistance film. The coordinate input device according to claim 1, wherein a relationship between the coordinate position and the coordinate position is corrected.

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