Sheet switch, sensing mechanism, and card reader

Provided is a sheet switch suitable as a sensing mechanism to sense the removal of a subordinate device from a host device. Specifically, the sheet switch is provided with a contact electrode formed in a dome shape with a conductive metal, a counter electrode disposed facing the contact electrode, and a metal sheet made of metal that is disposed on the opposite side of the counter electrode from the side facing the contact electrode with insulating members interposed therebetween. The sheet switch becomes conductive when the contact electrode and the counter electrode touch.

The present application claims priority from PCT Patent Application No. PCT/JP2009/005479 filed on Oct. 20, 2009, which claims priority from Japanese Patent Application Nos. JP 2008-273904 filed on Oct. 24, 2008 the disclosures of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet switch, a sensing mechanism having the sheet switch, and a card reader having the sensing mechanism.

2. Description of Related Art

Card readers which reproduce the data written on cards such as magnetic cards, IC cards, or the like or record data thereon are installed as subordinate devices in host devices, for example, ATM and the like. Popular card readers of this type include IC card readers which are constructed to prevent IC cards from various frauds (tampering activities) committed in an attempt to reproduce the data stored in the card for counterfeiting (i.e. See JP 2006-180244A).

In the IC card reader as described in JP 2006-180244A, when the IC card reader is removed from the host device and its secure board is physically attacked, the attack is sensed by the tamper-switch, and the key data in the secured board is deleted automatically.

In recent years, in order to prevent tampering, the PCI-PED or PCI-UPT standard based card readers have been demand by the market. In order to satisfy the PCI-PED or PCI-UPT standards, there is a clause requiring sensing of the removal of card readers from host devices.

However, conventionally, a sheet switch is known as a thin light weight switch used for operating parts of electric devices (i.e. See JP 2007-018887A). The sheet switch described in JP 2007-018887A comprises a resin surface sheet on which a contact electrode is mounted and a resin counter sheet on which a counter electrode facing the contact electrode is mounted.

SUMMARY OF THE INVENTION

As described above, in order to satisfy the PCT-PED or PCTI-UPT standards, the removal of the card reader from the host device must be sensed. And in order to enhance the security performance of the card reader, it is preferable that the removal of the card reader from the host device be sensed, even if a card reader is lifted only slightly from a host device.

In order to overcome the problem, the present inventors tried to apply the above-mentioned sheet switch to the sensing mechanism to detect the removal of the card reader from the host device. Specifically, the sheet switch was positioned in such a way that a card reader is fixed on the host device in the state in which the contact electrode the counter electrode are in contact with each other, and the contact electrode and the counter electrode separate when the card reader is removed from the host device.

Nevertheless, through the investigation by the inventors, it became clear that, under certain conditions, the conventional sheet switch used as is could not detect the removal of the card reader from the host device appropriately. Specifically, through the investigation by the inventors, it became clear that, particularly under high temperatures, due to creep deformation of the surface sheet or counter sheet, the contact electrode and the counter electrode stay in contact and do not separate when the card reader is removed from the host device.

For this reason, the object of the present invention is to provide a sheet switch which is suitable for the sensing mechanism for sensing the removal of the subordinate device from the host device. Moreover, the object of the present invention is to provide a card reader which comprises a sensing mechanism having the switch, and the sensing mechanism.

In order to overcome the problem, the sheet switch of the present invention is characterized in that it comprises a contact electrode formed in a dome shape with a conductive metal; a counter electrode disposed facing the contact electrode; and a metal sheet made of metal that is disposed on the opposite side of the counter electrode from the side facing the contact electrode with insulating members interposed therebetween wherein the contact electrode and the counter electrode come into contact with each other to become conductive.

In the sheet switch of the present invention, the contact electrode is formed in a dome shape with a conductive metal. In other words, the contact electrode is not mounted on a resin sheet. Therefore, creep deformation does not occur on the resin sheet on which the contact electrode is mounted. Moreover, since the contact electrode is formed with metal, the problem of creep deformation does not occur easily, even under high-temperature conditions.

Moreover, in the sheet switch of the present invention, a metal sheet is disposed on the opposite side of the counter electrode from the side facing the contact electrode with insulating members interposed therebetween. For this reason, even if the counter electrode is mounted (or formed) on a resin sheet, the sheet does not deform easily, and the pressure, generated by the contact between the contact electrode and the counter electrode, tends not to be concentrated on one part of this sheet. Therefore, creep deformation occurs with difficulty on the sheet on which the counter electrode is mounted.

As described above, in the present invention, the creep phenomenon generated on the counter electrode side can be prevented, and, at the same time, the creep phenomenon generated on the contact electrode side can be suppressed. Accordingly, with the sheet switch of the present invention for the sensing mechanism to detect the removal of the subordinate device from the host device, the contact electrode and the counter electrode can be prevented from generating the problem of coming into contact with each other and not separating. In other words, the sheet switch of the present invention is suitable for the sensing mechanism which senses the removal of the subordinate device from the host device.

In the present invention, It is preferable that the sheet switch be provided with an insulating surface sheet to cover the surface of the contact electrode and that the surface sheet be in contact with the contact electrode without being bonded thereto. In this case, for instance, the sheet switch comprises a cover sheet to cover the surface of the conductive pattern connected to the counter electrode, and a spacer interposed between the surface sheet and the cover sheet with an arrangement hole on which the contact electrode is mounted, wherein the surface sheet is bonded to the spacer.

With this configuration, the contact electrode is unlikely to be affected by the effects of creep deformation of the surface sheet, even if the surface sheet for protecting the contact electrode undergoes creep deformation. Accordingly, the contact electrode and the counter electrode can be prevented from generating the problem of coming into contact with each other and not separating without fail.

In the present invention, it is preferable that the contact electrode be formed with a metallic material comprising a spring member. With this configuration, by removing the pressing force against the contact electrode, the elastic recovery force of the contact electrode can separate the contact electrode from the counter electrode reliably.

In the present invention, it is preferable that the contact electrode and the metal sheet be formed from a stainless steel. With this configuration, the contact electrode tends not to undergo creep deformation. Moreover, since the stainless steel plate has a relatively large Young's modulus, with this configuration, permanent deformation occurs with difficulty on the metal sheet, even if the pressure is applied to the metal sheet when the contact electrode and the counter electrode are in contact with each other. Therefore, for example, even if the counter electrode is mounted on a resin sheet, the pressure generated by the contact between the contact electrode and the counter electrode can be spread over the resin sheet easily.

The sheet switch of the present invention can be used for the sensing mechanism equipped with a shock-absorbing member which is in contact with a metal sheet. In this sensing mechanism, the creep phenomenon generated on the contact electrode side can be prevented, and, at the same time, the creep phenomenon generated on the counter electrode side can be suppressed. Therefore, by using this sensing mechanism to sense the removal of the subordinate device from the host device, the contact electrode and the counter electrode can be prevented from generating the problem of coming into contact with each other and not separating.

Moreover, since this sensing mechanism is equipped with a shock-absorbing member which comes into contact with the metal sheet, even if the sheet switch is positioned in such a way that, for example, it protrudes outward from the mounting surface of the subordinate device, the sheet switch can be prevented from damages. For this reason, the sheet switch can be provided in the condition in which it protrudes outwards from the mounting surface of the subordinate device. Therefore, even if the contact sections of the host device vary in size, the contact sections can touch the sheet switch reliably, and enable the contact between the contact section and the sheet switch.

In the present invention, it is preferable that the sensing mechanism be equipped with a holding member to hold a shock-absorbing member and that the holding member be provided with a recessed arrangement section on which shock-absorbing member is mounted. With this configuration, the shock-absorbing member can be aligned easily, and the sensing mechanism can be assembled easily

In the present invention, it is preferable that the shock-absorbing member be equipped with a contact pressure receiving section, which is disposed at the position corresponding the contact point between the contact electrode and the counter electrode, and a notch section so that the entire perimeter of the outside circumference surface of the shock-absorbing member does not touch the wall surface of the recessed arrangement section. With this configuration, the stress applied to the contact pressure receiving section can be released by deforming the shock-absorbing member while the contact electrode and the counter electrode are in contact. Accordingly, the sheet on which the counter electrode is mounted is less subjected to excess stress; creep deformation of the sheet on which the counter electrode is mounted is easily prevented.

In the present invention, it is preferable that the shock-absorbing member be provided with a cross-shaped section formed substantially in a cross-shape around the contact receiving [sic, contact pressure-receiving] section, and that at least one end of the cross-shaped section be able to come into contact with the wall surface of the recessed arrangement section. With this configuration, the stress applied to the contact pressure-receiving section can be released, and the shock-absorbing members can be aligned easily.

In the sensing mechanism of the present invention, for example, in the state in which the subordinate device is attached to the host device, the contact electrode and the counter electrode come into contact with each other, and when the subordinate device is removed from the host device, the contact electrode and the counter electrode separate. This sensing mechanism can be used for the card reader which is attached to the host device in the state in which the contact electrode and the counter electrode are in contact with each other. Since this card reader can prevent the contact electrode and the counter electrode from generating the problem of coming into contact with each other and not separating, the removal of the card reader from the host device can be sensed reliably.

As described above, by using the sheet switch of the present invention for a sensing mechanism which senses the removal of the subordinate device from the host device, the contact electrode and the counter electrode can be prevented from generating the problem of coming into contact with each other and not separating. Moreover, by the use of the sensing mechanism of the present invention for sensing the removal of the subordinate device from the host device, the contact electrode and the counter electrode can be prevented from generating the problem of coming into contact with each other and not separating. Furthermore, because the card reader of the present invention can prevent the contact electrode and the counter electrode from generating the problem of coming into contact with each other and not separating, the removal of the card reader from the host device can be sensed reliably.

DETAILED DESCRIPTION OF EMBODIMENTS

Schematic Configuration of the Card Reader:

FIG. 1is a perspective view of card reader1of the embodiment of the present invention.FIG. 2is a perspective view showing the schematic configuration of host device5to which card reader1is attached.FIG. 3is a perspective view showing a part of the back face of card reader1inFIG. 1.

Card reader1of this embodiment comprises, as illustrated inFIG. 1, card insert-eject port3through which card2is inserted and ejected; and card processing section4which reproduces the data recorded on card2and/or record data on card2. As illustrated inFIG. 2, this card reader1is attached to host device5such as ATM, KIOSK terminals, and the like.

Card2is, for example, a vinyl chloride card formed in a rectangular shape having a thickness of 0.7˜0.8 mm. The surface of this card2is provided with, for example, a magnetic stripe to record magnetic data. Moreover, for example, the surface of card2is provided with an IC chip fixed thereto. Further, card2may have a built-in communication antenna. Additionally, a printing section to undergo thermal printing may also be provided on the surface of card2. Furthermore, card2may be a polyethyleneterefuthalate (PET) card having a thickness of about 0.18˜0.36 mm, or a paper card and the like having a given thickness.

Card insert-eject port3comprises exposed section3aprovided through the opening formed on front panel6of host device5. Exposed section3ais provided so that it protrudes from main body section3bof card insert-eject section3pointing toward the front side of the sheet inFIG. 1. Moreover, exposed section3ais provided with card insert-eject port3cthrough which card2is inserted and ejected.

Both the right and left sides of exposed section3ainFIG. 1are provided with mounting sections3dto attach card reader1to host device5. Mounting sections3dare provided with insertion holes3ein which screws (not illustrated) are inserted to fix card reader1on host device5.

Card processing section4is equipped with a recording-reproducing means such as magnetic head, IC contact and/or communication antenna and the like, for recording or reproducing the data. Back of the body frame of card processing section4(the rear end of the sheet inFIG. 1), as illustrated inFIG. 3, is provided with recessed mounting section4awhich is recessed from the back face of the body frame. The bottom face of this recessed mounting section4aprovides mounting surface4b(mounting reference plane) to mount card reader1on host device5. Moreover, to recessed mounting section4a, sensing mechanism7is provided to sense the removal of card reader1from host device5. The detailed configuration of sensing mechanism7and its peripheral components are described later.

Further, card processing section4may or may not comprise a card transfer mechanism to transfer card2in card processing section4. In other words, card reader1may be a self-propelled or it may be a manual card reader.

Configurations of Sensing Mechanism and Its Peripheral Components:

FIG. 4is an exploded perspective view of the E section as marked inFIG. 3.FIG. 5is an F-F cross sectional view ofFIG. 3.FIG. 6is a diagram illustrating sheet switch11as illustrated inFIG. 4wherein (A) is a plan view and (B) is a side view thereof.FIG. 7is an expanded view of the G section as illustrated inFIG. 6(B).FIG. 8is a plan view illustrating counter electrode21viewed from the H-H direction as marked inFIG. 7.FIG. 9is a plan view illustrating shock-absorbing member12as shown inFIG. 4.

As illustrated inFIG. 4, mounting surface4bis provided with substantially rectangular recessed arrangement section4cin a recessed manner to accommodate later-described shock-absorbing member12constituting sensing mechanism7. In this embodiment, as illustrated inFIG. 5, card reader1is secured on host device5by the use of a screw in the state in which the plane at the tip of contact projection5aprovided on host device5is in contact with mounting surface4b.

As illustrated inFIG. 6(A), sheet switch11comprises wide section11a, located on the left end side inFIG. 6, and narrow section11bwhich is an elongated section narrower than wide section11a. Wide section11ais provided with a switch section which is depressed when it is pressed by the plane of the tip of contact projection5a; this wide section11ais placed in recessed mounting section4a. Moreover, narrow section11bis drawn in toward the inner section of card reader1as illustrated inFIG. 5.

This sheet switch11comprises, as illustrated inFIGS. 6 and 7, a contact electrode15provided in wide section11ato constitute a part of the above-mentioned switch section, surface sheet16to cover the surface of contact electrode15(the upper surface inFIG. 7), counter sheet18having the surface provided with conductive pattern17, cover sheet19to cover the surface of conductive pattern17(the upper surface inFIG. 7), and metal sheet20provided on the back face side of counter sheet18(the lower surface inFIG. 7). As illustrated inFIG. 7, the left end side of conductive pattern17is exposed without being covered by cover sheet19. The exposed part of this conductive pattern17provides counter electrode21facing contact electrode15.

Contact electrode15is formed with a conductive metallic material. Further, contact electrode15is formed with a metallic material comprising a spring member. Specifically, contact electrode15of this embodiment is formed from a thin stainless steel plate. Further, contact electrode15is formed in a dome shape. Specifically, contact electrode15is formed in a dome shape rounded toward the upper side inFIG. 7; if it is pressed from the upper side, it is depressed toward the lower side. Moreover, contact electrode15is restored to its original dome-shape when pressure from the upper side ceases. In other words, contact electrode15restores itself to its original shape when the pressure from the upper side is terminated. In other words, when the pressure on contact electrode15applied from the upper side is removed, elastic recovery force of contact electrode15enables contact electrode15to separate from electrode21, and enter into the OFF-state in which contact electrode15and counter electrode21do not touch. Moreover, contact electrode15may be formed with other metallic materials comprising spring members such as phosphor bronze.

One part of the lower end of contact electrode15inFIG. 7is in contact with insulating sheet22formed into a thin sheet and the other part of the lower end of contact electrode15is in contact with cover sheet19. In this embodiment, as illustrated inFIG. 6(A), two contact electrodes15are disposed on wide section11aso that the two contact electrodes15constitute a part of wide section11a. Further, there may be one or more than three contact electrodes11that are provided on wide section11a.

Surface sheet16is formed into a thin sheet using an insulating material. Specifically, surface sheet is formed with a resin such as PET and the like. As illustrated inFIG. 7, this surface sheet16is adhesively fixed on the upper surface of spacer23having arrangement hole23ain which contact electrode15is placed. Spacer23is formed with a resin such as PET and the like, and is adhesively fixed on the upper surfaces of cover sheet19and insulating sheet22. Surface sheet16and spacer23are provided in wide section11asuch that they constitute a part of wide section11a.

Moreover surface sheet16is in contact with contact electrode15as illustrated inFIG. 7. In this embodiment, surface sheet16is not bonded to contact electrode15. In other words, surface sheet16is in contact with contact electrode15without being bonded to contact electrode15.

Counter sheet18is formed into a thin sheet using an insulating material. Specifically, counter sheet18is formed with a resin such as PET and the like. Moreover, counter sheet18is formed into a long sheet elongated in the left-to-right direction inFIG. 6(specifically it is formed from the left end to the right end of sheet switch11), thereby constituting a part of each wide section11aand narrow section11b. The upper surface of the right end side of counter sheet18is provided with connector-connection section18a, as illustrated inFIG. 6(A). Moreover, the lower surface of the right end side of counter sheet18is, as illustrated inFIG. 6(B), secured with reinforcement plate24formed with a resin such as PET and the like.

Conductive pattern17is formed with, for example, a printed silver paste. Moreover, conductive pattern17is provided from the lower part of contact electrode15inFIG. 6(B) to the right end side of counter sheet18. As described above, the exposed section of conductive pattern17(the left end side inFIG. 7) is counter electrode21facing contact electrode15. In other words, counter electrode21is provided on the lower part of contact electrode15as illustrated inFIG. 7. As illustrated inFIG. 8, counter electrode21is formed substantially in a semicircle. Further, in this embodiment, the lower part of one contact electrode15is provided with a pair of (that is, two) counter electrodes21that are separate.

Cover sheet19is formed into a thin sheet with an insulating material. Specifically, cover sheet19is formed with a resin such as PET and the like. Moreover, cover sheet19is formed into a long sheet elongated in the left-to-right direction inFIG. 6, thereby constituting a part of both wide section11aand narrow section11b.

Insulating sheet22is also formed into a thin sheet with an insulating material in the same manner as cover sheet19. Specifically, insulating sheet22is formed with a resin such as PET and the like. Moreover, insulating sheet22is made thicker than cover sheet19.

In this embodiment, cover sheet19is formed into insulating sheet22. As illustrated inFIG. 8, cover sheet19and insulating sheet22are provided with opening section30. Additionally, the lower end of circular contact electrode15is placed at the edge of said opening section30. In other words, the lower end of contact electrode15are in contact with the edge of opening30of cover sheet19and insulating sheet22; contact electrode15and conductive pattern17are insulated. Further, cover sheet19and insulating sheet22may be formed as separate members.

Metal sheet20is formed into a thin sheet. Metal sheet20of this embodiment is formed from a thin stainless steel plate. This metal sheet20is fixed on the back face of counter sheet18by the use of gummed sheet25. Gummed sheet25is formed with an insulating material such as resins and the like. Moreover, metal sheet20is provided on almost the entire area of wide section11a, and it constitutes a part of wide section11a.

In sheet switch11thus configured, when contact electrode15is pressed from the upper side inFIG. 7and depressed toward the lower side, and contact electrode15comes into contact with a pair of counter electrodes21, it becomes conductive. In other words, a pair of counter electrodes21is electrically connected to each other via contact electrode15to cause a flow of electric current from one of the paired counter electrodes21to the other.

Furthermore, in this embodiment, two contact electrodes15are provided to wide section11a, and the lower part of one contact electrode15accommodates a pair of counter electrodes21. Therefore, sheet switch11may become conductive when one of these two contact electrodes15comes into contact with a pair of counter electrodes21disposed on the lower part of contact electrode15, or it may become conductive when both of these two contact electrodes15come into contact with a pair of counter electrodes21disposed on the lower part of contact electrode15. In other words, sheet switch11may become non-conductive when both of these two contact electrodes15separate from counter electrode21disposed on the lower part of contact electrode15, or it may become non-conductive when one of these two contact electrodes15separates from counter electrode21disposed on the lower par of contact electrode15.

Shock-absorbing member12is formed with, for example, rubber. Shock-absorbing member12of this embodiment is formed with rubber with little compression set and excellent heat resistance, cold resistance, as well as excellent weather resistance, ozone resistance and non-conductance. Shock-absorbing member12, is formed with, for example, silicone rubber. As illustrated inFIG. 4, this shock-absorbing member12is placed in recessed arrangement section4cformed on mounting surface4bto be held in recessed arrangement section4c. The main body frame of card processing section4of this embodiment is the holding member which holds shock-absorbing member12.

Furthermore, shock-absorbing member12comprises, as illustrated inFIG. 9, two cross-shaped section12aformed substantially in a cross shape. Shock-absorbing member12of this embodiment is formed by connecting one ends of each member of these two cross-shaped sections12a. Specifically, shock-absorbing member12is formed by connecting the lower end of cross-shaped section12apositioned on the upper side inFIG. 9and the upper end of cross shaped section12apositioned on the lower side inFIG. 9. In other words, shock-absorbing member12of this embodiment is provided with a plurality of rectangular notch sections12bso that the entire perimeter of the outside circumference surface of shock-absorbing member12does not touch wall surface4dof recessed arrangement section4c(SeeFIGS. 4 and 9). By forming these notch sections12b, shock-absorbing member12has the shape comprising two cross-shaped sections12a.

The upper end and both of the right and left ends of cross-shaped section12apositioned on the upper side inFIG. 9can come into contact with wall surface4dof recessed arrangement section4c. And the lower end and both of the right and left ends of cross-shaped section12apositioned on the lower side inFIG. 9can come into contact with wall surface4dof recessed arrangement section4c. Furthermore, the center of cross-shaped section12ais contact pressure-receiving section12cwhich is provided at the position corresponding to the contact position between contact electrode15and counter electrode21(that is, lower part of contact electrode15inFIG. 7).

Sheet switch11is secured inside recessed mounting section4ain such a way that metal sheet20comes into contact with shock-absorbing section12as illustrated inFIG. 5. Specifically, sheet switch11is secured inside recessed mounting section4ain such a way that, when card reader1is not attached to host device5, the contact electrode15side of sheet switch11protrudes from mounting surface4b(SeeFIG. 5).

As described above, card reader1is fixed on host device5in such a manner that the plane of the tip of contact projection5aprovided in host device5is in contact with mounting surface4. In the state in which card reader1is fixed on host device5, shock-absorbing member12contracts upward inFIG. 5. Moreover, in this state, the plane of the tip of contact projection5ais in contact with the contact electrode15side of sheet switch11, and contact electrode15is depressed by the pressure until contact electrode15and counter electrode21come into contact with each other to cause sheet switch11to become conductive. In other words, card reader1is attached to host device5in the state in which electrode15and counter electrode21are in contact with each other, and sheet switch11is conductive.

If card reader1is removed from host device5in this state, the pressing force applied to contact electrode15is eliminated, and the elastic recovery force of contact electrode15enables contact electrode15to separate from counter electrode21, which causes sheet switch11to be non-conductive. In other words, the removal of card reader1from host device5is sensed when sheet switch11is in the non-conductive state.

Further, as described above, sheet switch11may become non-conductive when both of these two contact electrodes15separate from counter electrodes21provided on the lower part of contact electrode15; or sheet switch11may become non-conductive when one of these two contact electrodes15separates from counter electrodes21provided on the lower part of contact electrode15. In other words, the removal of card reader1from host device5may be sensed when both of these two contact electrodes15separate from counter electrodes21provided on the lower part of contact electrode, or the removal of card reader1from host device5may be sensed when one of these two contact electrodes15separates from counter electrode21provided on the lower part of contact electrode15.

In the event that the removal of card reader1from host device5is sensed when both of these two contact electrodes15separate from counter electrodes21provided on the lower part of contact electrode15, erroneous sensing made by sensing mechanism7can be prevented. Moreover, in the event that the removal of card reader1from host device5is sensed when one of these two contact electrodes separates from counter electrode21provided on the lower part of contact electrode15, the failure of one of the contact electrodes15(and/or counter electrodes21provided on the lower part of contact electrode15) will not affect sensing of the removal of card reader1from host device5.

Major Effects of the Embodiment:

As described above, in this embodiment, contact electrode15is formed in a dome shape with a conductive metal. In other words, contact electrode15is not mounted on a sheet made of resin. For this reason, the problem of creep deformation the resin sheet on which contact electrode15is mounted is eliminated. Moreover, since contact electrode15is formed from a stainless steel plate, creep does not occur easily, even under high-temperature conditions.

Furthermore, in this embodiment, metal sheet20is provided on the back face of counter sheet18. For this reason, the elastic recovery force of shock-absorbing member12generated when it contracts at the time card reader1is fixed on front panel6, tends not to be concentrated on one part of resin counter sheet18. As a result, creep occurs with difficulty on counter sheet18. Particularly, since metal sheet20of this embodiment is formed with a stainless steel plate, even though the elastic recovery force generated in shock-absorbing member12is applied to metal sheet20, it is difficult to deform metal sheet20permanently. Therefore, it becomes easier for the elastic recovery force generated by shock-absorbing member12to be transmitted to counter sheet18in a much dispersed manner.

Thus, in this embodiment, the creep phenomenon generated on the contact electrode15side can be prevented and, at the same time, the creep phenomenon generated on the counter electrode21side can be suppressed. Therefore, with sensing mechanism7of this embodiment, contact electrode15and counter electrode21can be prevented from generating the problem of coming into contact with each other and not separating. Accordingly, this embodiment can reliably sense the removal of card reader1from host device5.

In this embodiment, contact electrode15is formed with a metallic material comprising a spring member. Therefore, by removing the pressing force against contact electrode15, the elastic recovery force of contact electrode15can separate contact electrode15from counter electrode21reliably. In other words, the removal of the pressing force against contact electrode15can ensure the state in which contact electrode15and counter electrode21do not touch each other.

In this embodiment, surface sheet16is not bonded to contact electrode15. Therefore, even if resin surface sheet16undergoes creep deformation, contact electrode15is unlikely to be affected by the effects of creep deformation of surface sheet16. As a result, contact electrode15and counter electrode21are prevented from generating the problem in which they stay in contact and do not separate.

In this embodiment, sensing mechanism7is equipped with shock-absorbing member12which is in contact with metal sheet20. Therefore, sheet switch11can be placed inside recessed mounting section4awhile protruding outward from mounting surface4bwithout being damaged. Accordingly, even if contact projection5aof host device5vary in size, contact projection5acan touch sheet switch11reliably, and ensure the contact between contact electrode15and counter electrode21.

In this embodiment, mounting surface4bis provided with recessed arrangement section4c, which accommodates shock-absorbing member12. Further, the upper end and both of the right and left ends of cross-shaped section12a, positioned on the upper side inFIG. 9, can come into contact with wall surface4dof recessed arrangement section4c; and, at the same time, the lower end and both of the right and left ends of cross-shaped section12a, positioned on the lower side inFIG. 9, can also come into contact with wall surface4dof recessed arrangement section4c. Therefore, shock-absorbing member12can be easily aligned with respect to card processing section4, and card reader1can be assembled easily.

In this embodiment, shock-absorbing member12is formed by connecting one end to the other of each of two cross-shaped sections12a. Shock-absorbing member12is provided with a notch section12bso that the entire perimeter of the outside circumference surface of shock-absorbing member12does not touch wall surface4dof recessed arrangement section4c. For this reason, when shock-absorbing member12is placed inside recessed arrangement section4c, the stress applied to contact pressure receiving section12ccan be released by deforming shock-absorbing member12while contact electrode15and counter electrode21are in contact. Accordingly, counter sheet18is less subjected to excess stress; creep deformation of counter sheet18is easily prevented.

Furthermore, in sensing mechanism7of this embodiment, if the plane at the tip of contact projection5ais lifted 0.2 mm or more above mounting surface4b(i.e. the plane at the tip of contact projection5ais lifted from mounting surface by 0.2 mm or more), contact electrode15separates from counter electrode21, and the removal of card reader1from host device5can be sensed. In other words, in this embodiment, the removal of card reader1from host device5can be sensed, even if card reader1is lifted only slightly from host device5.

Moreover, in this embodiment, even if the variation range of the plane at the tip of contact projection5avaries in the range of −0.2 mm˜+0.3 mm, for example, to design values, when card reader1is attached to host device5, contact electrode15and counter electrode21are in secure contact; moreover, when card reader1is removed from host device5, contact electrode15and counter electrode21can be separated without fail. In other words, with this embodiment, there can be a larger design tolerance for contact projection5a.

The above-described embodiment is one of the preferable embodiments of the present invention. However, the present invention is not limited to this, and can have any variations as long as the spirit of the present invention remains the same.

In the above-described embodiment, shock-absorbing member12is formed by connecting one end to the other of each of two cross-shaped sections12a. However, shock-absorbing section12may have another shape as long as it comprises a contact pressure receiving section, which is provided to the position which corresponds to the contact position between contact electrode15and counter electrode2, and a notch section so that the entire perimeter of the outside circumference surface of shock-absorbing member12does not touch wall surface4dof recessed arrangement section4c. Moreover, shock-absorbing member [12] may be formed in a shape of cylinder, polygonal cylinder, truncated cone, or polygonal truncated pyramid. In this case, this shock-absorbing member is provided at the position corresponding to the contact point between electrode15and counter electrode21.

In the above-mentioned embodiment, as illustrated inFIG. 8, counter electrode21is shaped substantially in a semicircle. Alternatively, as illustrated inFIG. 10, counter electrode21may be formed in a shape of comb teeth comprising multiple projections21aand recessed sections21bprovided among projections21a. In this case, projection21aof one of paired counter electrodes21is placed in recessed sections21bof the other counter electrode21.

In the above-mentioned embodiment, sheet switch11is used for sensing mechanism7for sensing the removal of card reader1from host device5. Alternatively, sheet switch11can be used for a sensing mechanism which is used for sensing the removal of for example, a subordinate device other than card reader1from the host device. Moreover, usually, sheet switch11may also be used for a sensing mechanism which senses a given state: Usually, the state in which contact electrode15and counter electrode21stay in contact, or on an as needed basis, the state in which contact electrode15and counter electrode21separate.