JP2013114506A - Electrostatic induction touch sheet and rfid device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic induction touch sheet being freely assembled without taking account of a physical relationship with an RFID antenna and an influence on RFID communication caused thereby, and an RFID device including the electrostatic induction touch sheet.SOLUTION: An electrostatic induction touch sheet 5 in which a grounded loop circuit 11 is formed to enclose a sensor electrode 10, includes a resistive element 16 as a filter for preventing a shield current for suppressing a magnetic field for RFID communication from flowing to the loop circuit 11. The generation of the shield current of the loop circuit 11 is suppressed by the resistive element 16, so that the electrostatic induction touch sheet 5 is freely assembled without taking account of the physical relationship with an RFID antenna 4 and an influence on the RFID communication caused thereby.

Description

  The present invention relates to an electrostatic induction touch sheet and an RFID device including the same.

  Conventionally, when a touch switch sheet (hereinafter simply referred to as a touch sheet) is incorporated into an interface device having an RFID (Radio Frequency Identification) antenna coil, a resistive film type touch sheet has been widely used. However, in the case of the resistive film type, it is necessary to place a touch sheet on the surface side of the touch panel. 1) Since it is exposed to the outside and directly touched by a finger, durability and weather resistance are inferior. 2) Touch Since the communication line of the sheet is arranged on the surface side of the touch panel, it is necessary to provide an edge space around the touch part to hide the communication line, and there are problems such as being restricted by the design around the touch panel. .

On the other hand, if the electrostatic induction type touch sheet is used, the contact of the finger can be detected even if the touch sheet is arranged on the back side of the touch panel, so that the above problem can be solved.
In addition, as a conventional example of a technique in which an electrostatic induction touch sheet is combined with RFID, for example, those described in Patent Documents 1 and 2 can be cited.

JP2011-2948A JP 2011-2947 A

  However, the actual situation is that electrostatic induction type touch sheets are hardly used for incorporation into an interface having an RFID antenna coil. This is because, in the case of an electrostatic induction type touch sheet, a grounding loop circuit is often arranged on the outer periphery of the touch sheet so as to surround the sensor electrode. When laid out close to each other, a shielding current that cancels the magnetic field of the RFID antenna coil flows in the loop circuit due to the magnetic field of the RFID antenna coil, and this may be a factor that hinders the magnetic flux including the data signal from the RFID antenna coil. Because.

  The technique of Patent Document 1 is a technique in which the RFID antenna coil as a conductor reduces the sensing area of the touch part, and there is no description regarding the generation of the shielding current of the ground circuit. On the other hand, Patent Document 2 is a technique for solving the problem that the communication sensitivity of the RFID antenna coil is lowered due to the influence from the touch sheet side, and after arranging the touch sheet inside the RFID antenna coil, the RFID antenna coil Is described that is inclined at an angle of 45 to 90 degrees. However, in this structure, since the RFID antenna coil is arranged around the touch sheet, the RFID antenna coil is increased in size and the panel area of the device casing is increased. The depth of the body is also thicker. In particular, when a liquid crystal panel and a touch sheet are laminated to make the entire panel display unit a touch detection range, an edge space for arranging an RFID antenna coil around the panel display unit is required, and the device casing is required. It becomes a structure in which the design freedom of the body shape is likely to decrease.

  The present invention was created to solve such problems, and is an electrostatic induction type that can be freely assembled without considering the positional relationship with the RFID antenna and the influence on the RFID communication. An object of the present invention is to provide a touch sheet and an RFID device including the electrostatic induction touch sheet.

In order to solve the above problems, an electrostatic induction touch sheet of the present invention is an electrostatic induction touch sheet formed so that a grounded loop circuit surrounds a sensor electrode, and the loop circuit is used for RFID communication. A filter is provided to prevent a shield current that suppresses the magnetic field from flowing.
In addition, the RFID device of the present invention is provided in the vicinity of the RFID antenna and the RFID antenna, and a grounded loop circuit is formed so as to surround the sensor electrode, and a magnetic field for RFID communication is suppressed in the loop circuit. And an electrostatic induction touch sheet provided with a filter for preventing a shield current from flowing.

According to the eye of the present invention, even when the electrostatic induction touch sheet is arranged in a configuration that is most likely to exhibit the performance alone, while the RFID antenna is also arranged in a configuration that is most likely to exhibit the performance as such, the former to the latter are arranged. The purpose of this is to maintain the functions of both of them at a high level.
According to the electrostatic induction touch sheet and the RFID device of the present invention, the loop circuit is provided with a filter that prevents the shielding current that suppresses the magnetic field for RFID communication from flowing, thereby simplifying the influence of the RFID communication due to the shielding current. Can be reduced with a simple configuration. Therefore, the electrostatic induction touch sheet can be freely assembled without considering the positional relationship with the RFID antenna and the influence on the RFID communication. In the RFID device, the degree of freedom in designing the housing shape of the device can be increased.

  In the electrostatic induction touch sheet and the RFID device according to the present invention, the filter is a resistance element.

  As a filter, a low-pass filter using an inductor or the like is conceivable, but if an element or circuit having a frequency dependency is used, waveform distortion may occur. On the other hand, since the frequency characteristics of the resistance element are stable, there is no risk of waveform distortion, and the touch detection function is not impaired. Further, since the resistor is an inexpensive and simple element, it becomes an economical filter.

  The RFID device of the present invention includes a touch panel in which the RFID antenna and the electrostatic induction touch sheet are arranged on the back side, and the RFID antenna is a reader / writer of a non-contact IC card held over the surface of the touch panel. It is characterized by comprising an antenna.

  According to this RFID device, it is possible to realize a card reader / writer with a high degree of freedom in designing the housing shape.

  According to the present invention, the electrostatic induction touch sheet can be assembled freely without considering the positional relationship with the RFID antenna and the influence on the RFID communication.

1 is an exploded perspective view of a card reader / writer to which the present invention is applied. It is a plane sectional view of a card reader / writer to which the present invention is applied. It is explanatory drawing which shows the positional relationship of a loop circuit and a RFID antenna when a card reader / writer is seen from the front. It is a block diagram of a card reader / writer. It is a front view of the electrostatic induction type touch sheet to which the present invention is applied. It is the schematic diagram which showed a mode that a shielding current generate | occur | produces in a loop circuit with the magnetic field of a RFID antenna.

  A mode in which the RFID device is a card reader / writer for reading and writing a non-contact IC card will be described. As shown in FIG. 1, a card reader / writer 1 includes a front casing 2 and a rear casing 3 as casings, and an RFID antenna coil (hereinafter simply referred to as an antenna coil for a reader / writer of a non-contact IC card). (Referred to as an RFID antenna) 4, an electrostatic induction touch sheet 5, a touch sheet control board 6, a reader / writer unit 7, and a control board 8.

  The front housing 2 is made of, for example, glass (tempered glass with an anti-scattering film, etc.), and the front surface of the front housing 2 functions as a touch panel with numbers and characters for touch-inputting a personal identification number with a finger. Since glass (particularly tempered glass) and acrylic are excellent in durability and weather resistance, the card reader / writer 1 having excellent durability and weather resistance can be obtained by using these glass and acrylic as a front touch panel. The RFID antenna 4 is formed in a thin film on an antenna sheet 9 which is a substantially rectangular film substrate, and is formed as a rectangular loop that circulates several times as shown in FIG. Therefore, the range in the rectangular loop is generally the readable range of the non-contact IC card. The position of the RFID antenna 4 when the front housing 2 is viewed from the front is as shown by a thick broken line in FIG.

  In FIG. 1, the electrostatic induction touch sheet 5 is formed of a substantially rectangular film substrate, and includes a plurality of sensor electrodes 10 corresponding to numerals and characters attached to the front housing 2, and a ground surrounding the sensor electrodes 10. Loop circuit 11 is formed. Both the sensor electrode 10 and the loop circuit 11 are formed as a thin film. The sensor electrode 10 is composed of, for example, a large number of electrode lines arranged in a lattice pattern, and detects numbers and characters touched with a finger. The loop circuit 11 is a closed loop circuit formed in a rectangular loop shape. The position of the loop circuit 11 when the front housing 2 is viewed from the front is as shown by a thin broken line in FIG. The loop circuit 11 is formed of, for example, ITO (Indium Tin Oxide) or silver paste.

  As shown in FIG. 2, the antenna sheet 9 and the electrostatic induction touch sheet 5 are overlapped with each other by an adhesive, and are attached to the back surface of the front housing 2 constituting the touch panel with the adhesive. FIG. 2 shows an aspect in which the antenna sheet 9 and the electrostatic induction touch sheet 5 are attached to the rear surface of the front housing 2 in this order, but the electrostatic induction touch sheet 5 and the antenna sheet 9 are in this order. It can be pasted with. By superimposing the antenna sheet 9 and the electrostatic induction touch sheet 5, in this embodiment, the upper sides of the RFID antenna 4 and the loop circuit 11 and the lower sides of the RFID antenna 4 and the loop circuit 11 substantially overlap each other as shown in FIG. Placed in.

  The drawer part of the antenna sheet 9 (RFID antenna 4) is connected to the reader / writer part 7 through the wiring 12, as shown in FIG. The reader / writer unit 7 is connected to the control board 8 via the wiring 13. The lead-out of the electrostatic induction touch sheet 5 (sensor electrode 10, loop circuit 11) is connected to the touch sheet control board 6 through the wiring 14. The touch sheet control board 6 is connected to the control board 8 via the wiring 15.

  FIG. 4 is a configuration block diagram of the card reader / writer 1. The antenna sheet 9 performs electromagnetic induction type RFID communication with a non-contact IC card. When the ID data transmitted from the non-contact IC card is permitted ID data, various commands are transmitted from the control board 8 to the reader / writer unit 7 under the control of the control board 8 as necessary. The reader / writer unit 7 modulates data according to the command and transmits the data from the antenna sheet 9 to the non-contact IC card, and demodulates the data received from the non-contact IC card and transmits the data to the control board 8.

  The touch sheet control board 6 applies a low voltage to the electrostatic induction touch sheet 5 and detects a change in the capacitance between the sensor electrode 10 and the loop circuit 11 which is a ground circuit, thereby touching a number touched by a finger. And identify characters. The specified data is transmitted to the control board 8.

  By overlapping the antenna sheet 9 and the electrostatic induction touch sheet 5, the portion surrounded by the RFID antenna 4 and the portion surrounded by the loop circuit 11 overlap each other. In such an arrangement, as shown in FIG. 6, a shield current I is generated in the loop circuit 11 by the magnetic field H generated in the portion surrounded by the RFID antenna 4. The shield current I suppresses the RFID communication magnetic field, generates a reaction magnetic flux that cancels the magnetic field H, and inhibits the magnetic flux including the data signal from the RFID antenna 4.

  With respect to this problem, the electrostatic induction touch sheet 5 of the present invention is provided with a resistance element 16 as a filter for preventing the shield current I from flowing in the loop circuit 11. By providing the resistance element 16 in the loop circuit 11, the shielding current I is reduced, and the influence on the RFID communication can be suppressed correspondingly. Although FIG. 5 shows a mode in which the resistance elements 16 are inserted in the pair of lead portions of the loop circuit 11, the arrangement position and the number of the resistance elements 16 are not limited to this.

  What is important in the function of the electrostatic induction touch sheet 5 is a change in capacitance between the loop circuit 11 serving as a ground circuit and the sensor electrode 10 at each touch point. For this reason, even if the loop circuit 11 has the resistance value of the resistance element 16, if the resistance value is sufficiently smaller than the equivalent resistance from the loop circuit 11 to the sensor electrode 10 at the touch point, the touch detection function is impaired. There is nothing. As an example of a test conducted by the present inventor, a resistance equivalent to the resistance value of the loop circuit 11 itself without the resistance element 16 (when a plurality of resistances are included, the total resistance is indicated) is included. Thus, it was possible to achieve both suppression of the shielding current I and securing of the touch detection function.

  As a method of increasing the resistance of the loop circuit 11, it is thought that the wiring width of the circuit is narrowed. However, this method is likely to be affected by variations in manufacturing and local aging. 11 The degree of freedom in design related to the original touch detection function is reduced. On the other hand, if the loop circuit 11 is provided with a filter such as the resistance element 16, the reliability of the device can be improved compared to a method of increasing the resistance value of the loop circuit 11 itself, such as reducing the wiring width of the loop circuit 11. Performance and design freedom.

  Examples of the filter other than the resistive element 16 include a low-pass filter that shields the 13.56 MHz frequency band and passes the frequency band of the touch signal when the RFID antenna 4 performs communication in the 13.56 MHz frequency band. It is done. However, these low-pass filters are often composed of frequency-dependent elements and circuits such as inductor elements, so the problem of waveform distortion must be noted. On the other hand, the resistance element 16 has a stable frequency characteristic as compared with other filters, so there is no risk of waveform distortion, and it is the cheapest and simplest element. Therefore, the resistance element 16 is suitable as a filter used in the present invention. is there.

  Examples of the resistive element 16 include a surface-mounted metal glaze chip resistor, but are not limited thereto, and may be a thin film resistor such as a carbon film resistor.

  As described above, according to the present invention, even when the RFID antenna 4 and the loop circuit 11 are disposed close to each other by stacking or providing the antenna sheet 9 and the electrostatic induction touch sheet 5, the RFID antenna 4 and the touch detection function of the electrostatic induction touch sheet 5 can be achieved.

  According to the present invention, in an RFID device including a touch panel such as the front housing 2, the RFID antenna 4 and the electrostatic induction touch sheet 5 can be disposed close to each other on the back side of the touch panel. Therefore, there are problems with the structure in which a resistive touch panel is placed on the surface of the touch panel, that is, the durability and weather resistance of the touch sheet due to exposure to the outside, and the communication line with the touch sheet around the touch part. This eliminates the problem of requiring a forehead space around the touch portion to hide the wiring. As for the former problem, in the present invention, the surface of the touch panel is exposed to the outside instead of the touch sheet, but the touch panel is made of a material having excellent durability and weather resistance, such as tempered glass and acrylic. The card reader / writer 1 having excellent performance and weather resistance can be realized.

  In addition, according to the present invention, the electrostatic induction touch sheet 5 can be freely assembled without considering the positional relationship with the RFID antenna 4 and the influence on the RFID communication, and as a result, the housing shape of the device. The degree of design freedom can be increased. It is not necessary to arrange an RFID antenna around the touch sheet as in Patent Document 2, and the loop circuit 11 and the RFID antenna 4 can be arranged to overlap each other when viewed from the front view direction of the front housing 2. . Therefore, the increase in the size of the RFID antenna 4 and the increase in the touch panel area of the front case 2 can be suppressed, and further, since the RFID antenna does not need to be inclined, the depth dimensions of the front case 2 and the rear case 3 are reduced. Can also be suppressed.

  The preferred embodiment of the present invention has been described above. In the described embodiment, the RFID antenna 4 has a sheet shape. However, the RFID antenna 4 is not limited to a sheet shape, and is a metal wire processed into a loop shape or formed on a substrate by etching. There may be.

1 Card reader / writer (RFID device)
2 Front housing (touch panel)
DESCRIPTION OF SYMBOLS 4 RFID antenna 5 Electrostatic induction type touch sheet 6 Touch sheet control board 7 Reader / writer part 8 Control board 9 Antenna sheet 10 Sensor electrode 11 Loop circuit

Claims (5)

An electrostatic induction type touch sheet formed so that a grounded loop circuit surrounds the sensor electrode,
The electrostatic induction touch sheet, wherein the loop circuit is provided with a filter that prevents a shield current that suppresses a magnetic field for RFID communication from flowing.   The electrostatic induction touch sheet according to claim 1, wherein the filter is a resistance element. An RFID antenna;
Provided in the vicinity of the RFID antenna, a grounded loop circuit is formed so as to surround the sensor electrode, and a filter is provided in the loop circuit to prevent a shielding current that suppresses the RFID communication magnetic field from flowing. An electrostatic induction touch sheet;
An RFID device comprising:   The RFID device according to claim 3, wherein the filter is a resistance element. A touch panel in which the RFID antenna and the electrostatic induction touch sheet are arranged on the back side,
5. The RFID device according to claim 3, wherein the RFID antenna is a reader / writer antenna of a non-contact IC card held over the surface of the touch panel.

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