JP6269950B2 - Capacitive coupling switch with non-contact IC card reader / writer - Google Patents

Description

  The present invention relates to an input device including an antenna for communicating with a non-contact IC card and using a capacitive coupling method.

Conventionally, when a switch such as a numeric keypad operated by a finger is incorporated in a communication device having a reader / writer of a non-contact IC card and an antenna, a mechanical switch has been used. However, touch switches have been used instead of mechanical switches in response to demands for thinner devices and greater design flexibility.
As a touch input means, for example, a resistive film type touch panel is known. A resistive film type touch panel has a conductive thin film affixed to each facing surface of a film placed with a gap, and when the user presses a specific position, the conductive thin films on the film touch each other. The position touched by the user is detected based on the passage of electricity.

Conventionally, when a touch switch is incorporated in a communication device having a reader / writer of an non-contact IC card and an antenna, the above-mentioned resistive film type touch panel is generally used. An area corresponding to one or more switches is defined on the touch panel, and when it is detected that the area is touched, it is recognized that the corresponding switch is input.
If a transparent touch panel is used and a liquid crystal display device is disposed under the touch panel, there is an advantage that the display on the switch surface can be freely changed during operation.

  However, when using the resistive film method, touch detection is based on film deformation caused by finger pressing, so the touch panel is placed on the outermost surface of the embedded device so that the finger can directly touch the resistive film type touch panel. There is a need. For this reason, the resistive touch panel is easily damaged. If the touch panel is damaged, the switch input malfunction is likely to occur, and the durability of the switch is poor. In addition, when used outdoors, since ultraviolet rays directly hit the resistive film type touch panel, deformation, discoloration, deterioration, etc. of the touch panel can be considered, resulting in poor weather resistance.

  In addition, a resistive touch panel must be placed on the outermost surface of the device, and in order to hide communication lines that are generally placed outside the input area of the touch panel, an edge space is placed around the touch area. Since it is necessary to provide it, the design around the touch panel is restricted.

  On the other hand, if a capacitive touch switch is used for the communication device having the reader / writer of the non-contact IC card and the antenna, it is not necessary to expose the touch switch on the outermost surface of the device. Since the touch switch can be arranged on the back side of the cover made of non-conductive resin or the like, the problems of durability, weather resistance, and edge space can be solved. As a technology of a conventional capacitive touch switch, for example, one described in Patent Document 1 can be cited.

The configuration of the capacitance type switch will be described with reference to FIG. The capacitive coupling type touch switch includes a switch unit 1 and a control board 2. The switch unit 1 uses the adhesive 6 including a double-sided tape or the like on the side opposite to the surface to be touched of the insulating base material 5 such as glass or an acrylic resin, with the switch electrode film on which the switch electrode is formed. Consists of pasted together. The switch electrode film usually surrounds the switch electrode 3 and the switch electrode 3 on the surface of the film (generally, polyethylene terephthalate film: PET film is used), and is connected to the ground of the control board 2. A connected ground line 4 is formed. The switch electrode 3 and the ground line 4 are formed by printing ITO (indium tin oxide), or silver paste or the like if not transparent. When a display device such as a liquid crystal display device is not disposed behind the touch switch and the touch switch does not have to be transparent, the switch electrode 3 and the surface of the glass epoxy substrate are used instead of the switch electrode film. A base material in which the ground wire 4 surrounding the switch electrode 3 is formed by copper etching may be used.

The capacitance type switch operation will be described with reference to FIG. When the finger 7 as an input object approaches the switch electrode 3, a parallel plate capacitor is formed between the finger 7 and the switch electrode 3, and a capacitance 8 is generated. This change in capacitance is converted into a change in frequency of an AC signal by a C / F conversion circuit (a circuit that converts capacitance C to frequency F) formed by a capacitor C9 and a resistor R10. The input capture 11 function (function of counting the number of AC signal cycles) is replaced with digital data, and the calculation process 12 determines the on / off state of the touch switch. When there are a plurality of switch electrodes 3, the switch electrodes 3 are selected by an electrode selection circuit 13 provided by the number of switch electrodes 3. Instead of providing the electrode selection circuit 13, the number of input captures 11 may be provided as many as the number of switch electrodes 3.
The input object may be not only a fingertip but also a hand or other human body part, or a touch pen having a tip formed of a conductive material.
A touch switch using the capacitive coupling method uses a region that can be touched by an input object such as a finger or a touch pen as a switch electrode, and detects that the input object has approached the switch electrode. This is a digital input device for detecting off / off.

RFID (Radio Frequency IDentification, an abbreviation of “individual identification by radio waves”) is known as a non-contact type automatic recognition technology that recognizes people and objects using radio waves. An antenna or an IC chip is processed into a tag or a label and attached to a product or a person, and communication is performed with respect to the IC chip using a reader / writer that reads and writes information.
Currently, non-contact IC cards use the same technology as RFID and are included in a broad sense of RFID. Non-contact IC cards have various uses such as boarding cards, electronic money, employee ID cards and security locks, and RFID has come to be used in various fields.

The reading / writing of the information of the non-contact IC card 14 is demonstrated using FIG. The non-contact IC card 14 includes an IC chip 15 that holds information and controls information through wireless communication, and an antenna 16 that performs communication. The reader / writer 17 includes an antenna 16 for communicating with the non-contact IC card 14 wirelessly and a control board 18 for performing control.
An antenna 16 for exchanging information is arranged in the non-contact IC card 14 and the reader / writer 17, and a magnetic field 19 generated from the antenna 16 in the reader / writer 17 is changed to an antenna in the non-contact IC card 14. The power is supplied to the IC chip 15 by the induced current 20 captured by the antenna 16 in the non-contact IC card 14 and data communication between them is performed. For this reason, the antenna 16 has a looped coil shape so as to generate a magnetic field 19 and flow an induced current 20.
As a conventional technique combining a capacitive touch switch and RFID, for example, the one described in Patent Document 2 can be cited.

JP 2005/084982 A JP 2011-002947 A

  When a touch switch and a non-contact IC card reader / writer are combined, the entire apparatus is required to be downsized. However, it is desirable to make the opening area of the loop-shaped antenna of the non-contact IC card as large as possible. In order to satisfy these requirements at the same time, the switch area of the touch switch and the opening area of the antenna of the non-contact IC card are often designed to overlap each other when viewed from a direction perpendicular to the switch surface.

  The patent document 2 is a technique in which the communication sensitivity of the RFID antenna is reduced due to the influence from the touch switch side. The touch switch is arranged inside the RFID antenna, and the RFID antenna A structure for tilting the angle is described. In this structure, since the RFID antenna is arranged around the touch switch, the RFID antenna is increased in size and the panel area of the housing of the device is increased. The depth dimension of the device casing is also increased. In particular, when the liquid crystal panel and the touch sensor are stacked, an edge space and a thickness for arranging the entire panel display unit are required, and the design freedom of the housing shape of the device is likely to be reduced.

On the other hand, a capacitance type touch switch is generally configured such that a ground line connected to the ground of a control board is arranged on the outer periphery of the touch switch as a closed loop circuit surrounding the switch electrode. However, many are used. This is to prevent the switch electrode from being affected by noise.
However, if a wiring connected to the ground exists in a region overlapping with the opening of the loop-shaped antenna of the non-contact IC card, it acts as a shield for the antenna, and thus the performance of the antenna is lost. For this reason, the communication sensitivity of the antenna of a non-contact IC card may fall.

The present invention has been made in consideration of such points, and the touch switch loses the performance of the antenna while superimposing the switch portion of the touch switch and the antenna of the non-contact IC card to reduce the size of the entire apparatus. An object of the present invention is to provide a capacitive touch switch that does not occur.

  The present invention relates to a reader / writer having an antenna for transmitting information to a contactless IC card by radio waves and receiving information transmitted from the contactless IC card, and for inputting information by an input object. One or more capacitance switch electrodes, a ground wire provided so as to surround the capacitance switch electrodes, a C / F conversion circuit for generating an AC signal by a capacitor and a resistor, and the one or more capacitance switches Either one of the capacitance switch electrodes and the C / F conversion circuit are connected, or all of the one or more capacitance switch electrodes are separated from the C / F conversion circuit to be in a floating state. A selection circuit and a ground connection switch that grounds or grounds the ground line, the ground line is grounded by the ground connection switch, and is connected to the electrode selection circuit. A touch switch mode in which the one or more capacitance switch electrodes are connected to the C / F conversion circuit to detect an input by the input object; and the ground line is floated by the ground connection switch; The operation of alternately performing at least once or more the non-contact IC card mode in which all of the one or more capacitance switch electrodes are floated by the electrode selection circuit and communicate with the non-contact IC card is repeated. The gist.

According to the present invention, when a capacitive touch switch is incorporated into a communication device having an RFID reader / writer and antenna including a non-contact IC card, information is transmitted to the non-contact IC card by radio waves, A reader / writer having an antenna for receiving information transmitted from a non-contact IC card, one or more capacitance switch electrodes for inputting information by an input object represented by a finger, and the static A ground line provided so as to surround the capacitance switch electrode, a C / F conversion circuit for generating an AC signal by a capacitor and a resistor, one of the one or more capacitance switch electrodes, and the C An electrode selection circuit that connects to a C / F conversion circuit, or separates all of the one or more capacitance switch electrodes from the C / F conversion circuit to float. A ground connection switch that grounds or floats the ground line, the ground line is grounded by the ground connection switch, and the one or more capacitance switch electrodes are connected to the C / C by the electrode selection circuit. Touch switch mode for detecting input by the input object by connecting to an F conversion circuit, and floating the ground line by the ground connection switch, and all the one or more capacitance switch electrodes by the electrode selection circuit. Since the operation of performing the contactless IC card mode for communicating with the contactless IC card in a floating state is repeated alternately at least once, the RFID reader / writer including the contactless IC card The touch switch can be placed without sacrificing the performance of the antenna, and thus the equipment housing Jo of freedom is improved, at the same time, it is possible to reduce the shape of the device.

Touch switch configuration diagram Touch switch operation diagram Non-contact IC card information reading chart Diagram Touch switch block diagram Switch electrode shape dimensions Non-contact IC card reading structure diagram

The configuration of the capacitance type switch, the non-contact IC card 14 and the reader / writer 17 according to the present invention will be described with reference to FIGS. On the reader / writer 17, a capacitive touch switch is overlaid with the acrylic 5 as a touch surface on the upper surface.
The capacitive touch switch and the reader / writer 17 for the non-contact IC card 14 are not detected by the capacitive touch switch, and the reader / writer 17 detects the non-contact IC card 14. While not detecting, it is operated almost alternately. Here, a period for operating the touch switch is referred to as a touch switch mode, and a period for operating the reader / writer 17 is referred to as a non-contact IC card mode.

In the touch switch mode, the ground connection switch 21 is closed and the ground line 4 is connected to the ground. The electrode selection circuit 13 switches in order to all the switch electrodes 3 to be detected, and checks whether a finger 7 touch exists. At this time, the antenna output of the reader / writer 17 is preferably in a state where the output does not fluctuate. If none of the switch electrodes 3 is touched, the touch switch mode is terminated and the non-contact IC card mode is entered. After the end of one touch switch mode, the touch switch mode may be repeated two or more times without shifting to the non-contact IC card mode, and then the non-contact IC card mode may be shifted.

In the non-contact IC card mode, the control board 2 of the touch switch opens the ground connection switch 21 and all the electrode selection circuits 13 so that all the switch electrodes 3 and the ground lines 4 are in a floating state. After that, the reader / writer 17 checks whether or not the non-contact IC card 14 exists within the detection range. If the non-contact IC card 14 is not detected, the non-contact IC card mode is ended and the touch switch mode is entered. This is repeated while neither the finger 7 nor the non-contact IC card 14 is detected.

The detection of the finger 7 in the touch switch mode is performed as follows. The ground connection switch 21 is closed, and the switch electrode 3 to be detected is selected by the electrode selection circuit 13. When the finger 7 that is a conductor approaches the vicinity of the switch electrode 3, a parallel plate capacitor is formed between the finger 7 and the switch electrode 3, and the capacitance 8 is generated. The capacitance 8 increases as the finger 7 approaches the switch electrode 3. When the capacitance 8 changes, the oscillation frequency of the AC signal converted by the C / F conversion circuit changes. In general, the oscillation frequency of the C / F conversion circuit formed by the capacitor C9 and the resistor R10 is expressed by using the capacitance C of the capacitor C9 and the electric resistance value R of the resistor R10. The formula f = 1 / (C XR) is proportional to f. Since the capacitance 8 increases as the finger 7 approaches the switch electrode 3, the oscillation frequency decreases as the finger 7 approaches the switch electrode 3. At the start of measurement when the power is turned on, the number of cycles counted by the input capture 11 in a state where the finger 7 is not in contact is held as a reference value for all the switch electrodes 3. In the subsequent touch switch mode, a touch is detected by examining how much the number of periods decreases for each switch electrode 3 due to a decrease in the frequency accompanying the approach of the finger 7.

The detection of the non-contact IC card 14 in the non-contact IC card mode is performed as follows. The reader / writer 17 transmits a synchronization signal and an inquiry command from the antenna 16 in the reader / writer 17. When the non-contact IC card 14 exists in the readable range, the antenna 16 in the non-contact IC card 14 captures the magnetic field 19 generated by the antenna 16 in the reader / writer 17, and the antenna in the non-contact IC card 14. Power is supplied to the IC chip 15 by the induced current 20 obtained in 16. The IC chip 15 transmits an answer to the inquiry command transmitted by the reader / writer 17 from the antenna 16 in the non-contact IC card 14, and the reader / writer 17 receives the response, whereby the non-contact IC card 14 Detects being within the readable range.

The minimum time required for the touch switch mode varies depending on the number of switch electrodes 3, the circuit configuration, the frequency used in the C / F conversion circuit, and the like. On the other hand, the minimum time required for the non-contact IC card mode also varies depending on the frequency used, the number of trials, and the like. The alternating repetition of the touch switch mode and the non-contact IC card mode may be performed alternately every time in consideration of the minimum time of each, or one of them is performed a plurality of times and then the other is transferred. You may make it do.

In addition, in either the touch switch mode or the non-contact IC card mode, after the finger 7 or the non-contact IC card 14 is detected, the touch switch mode and the non-contact IC card mode are alternately switched according to the use of the device. Alternatively, after the finger 7 is detected, only the touch switch mode may be repeated until the specific condition that a predetermined switch input is made, or the non-contact IC card 14 may be After the detection, the non-contact IC card mode may be continued until a specific condition that the non-contact IC card 14 is not detected is satisfied.

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
This will be described with reference to FIG. The switch part 1 used the switch electrode 3 which printed the silver paste on the surface of PET film 22, and the shape and dimension of the switch electrode 3 were made into the square of 10x10 mm which a human finger | toe 7 can touch. A ground line 4 was provided around the switch electrode 3 so as to have a pattern width of 1 mm and be surrounded by a 15 × 15 mm square.
This will be described with reference to FIGS. 7 (a) and 7 (b). The number of switch electrodes 3 is nine in total, three in the horizontal direction and three in the vertical direction so that the antenna 16 of the reader / writer 17 is covered with the switch electrode 3. A 1 mm thick acrylic 5 is placed on the surface of the PET film 22, and a reader / writer 17 (TM02-C-5V manufactured by GL Sciences Inc.) is placed on the back surface of the PET film 22 with the nine switch electrodes 3. The structure is placed in a surrounded position.

For reading data from the non-contact IC card 14, the reader / writer 17 was connected to a personal computer via USB and software (TZ01-DSET manufactured by GL Science Co., Ltd.) was used. Further, a non-contact IC card 14 (a test Felica card (“FeliCa” is a registered trademark of Sony Corporation)) was used as a test reading card.
The time required for the touch switch mode is about 20 ms per time, and the time required for the non-contact IC card mode is about 30 ms per time. Here, after the touch switch mode is executed five times, the operation of executing the non-contact IC card mode once is repeated.
Under this condition, the reader / writer 17 is held over the non-contact IC card 14 and the distance 23 from the surface of the antenna 16 of the reader / writer 17 is changed. I counted the success.

(Comparative Example 1)
In the configuration of the first embodiment, the touch switch mode and the non-contact IC card mode are not executed alternately, but both are always executed.
Under this condition, the non-contact IC card 14 is held over the reader / writer 17 and the distance 23 from the surface of the antenna 16 of the reader / writer 17 is changed. The number of successful readings was counted.

From the results of Table 1, it can be seen that in Example 1, the rate of successful reading increases as the distance 23 from the surface of the antenna 16 of the reader / writer 17 increases compared to Comparative Example 1. The effect of the invention was confirmed.

DESCRIPTION OF SYMBOLS 1 Switch part 2 Control board 3 Switch electrode 4 Ground wire 5 Acrylic 6 Adhesive
7 Finger 8 Capacitance 9 Capacitor C
10 Resistance R
11 Input capture 12 Arithmetic processing 13 Electrode selection circuit 14 Non-contact IC card 15 IC chip 16 Antenna 17 Reader / writer 18 Control board 19 Magnetic field 20 Inductive current 21 Ground connection switch 22 PET film 23 IC card reading distance

Claims (1)

A reader / writer having an antenna for transmitting information to a contactless IC card by radio waves and receiving information transmitted from the contactless IC card, and one or more for inputting information by an input object A capacitance switch electrode; a ground line provided so as to surround the capacitance switch electrode; a C / F conversion circuit that generates an AC signal by a capacitor and a resistor; and the one or more capacitance switches. An electrode selection circuit that connects any one of the electrodes and the C / F conversion circuit, or separates all of the one or more capacitance switch electrodes from the C / F conversion circuit; A ground connection switch that grounds or floats the ground line, the ground line is grounded by the ground connection switch, and the electrode selection circuit Touch switch mode in which one or more capacitance switch electrodes are connected to the C / F conversion circuit to detect input from the input object, and the ground line is floated by the ground connection switch, and the electrode selection circuit The one or more capacitance switch electrodes are all in a floating state, and a non-contact IC card mode for communicating with a non-contact IC card is alternately repeated at least once. Capacitance coupling type switch equipped with non-contact IC card reader / writer.

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