Abstract:
A smart card reader module is disclosed and it includes a biasing member ( 36,39 ) for ejecting a smart card ( 27 ) inserted into the module against a bias provided by the biasing member ( 36,39 ) and a locking member ( 46 ) to retain an inserted smart card ( 27 ) in the module, the biasing member ( 36,39 ) being operable to eject a smart card ( 27 ) from the module on release of the locking member ( 46 ). The smart card reader module is particularly intended for use in mobile telecommunications apparatus ( 1 ) for mounting a Subscriber Identification Module (SIM) card.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a smart card reader module and, in particular, to a module for securing a Subscriber Identification Module (SIM) into a mobile telecommunications device that incorporates contacts that must be maintained in contact with corresponding conductive elements on the card. 
   BACKGROUND TO THE INVENTION 
   A smart card is a plastic card that incorporates an embedded semi-conductor which lets it accept, send and store information and they are used in a variety of applications including mobile telephones, cash-less payment systems and user identification. 
   Smart cards typically fall into two general categories: contact and contactless. The chip communicates either directly via a physical contact or remotely via a contactless electromagnetic interface. The present invention is concerned with contact smart cards which must be inserted into smart card readers, which incorporate contacts that touch a conductive module on the surface of the card. Data, algorithm and other information are transmitted via the physical contacts. 
   The value of smart cards lies in their capability to store personal information with a high degree of security and portability. They are therefore ideal medium for the storage of private passwords, account numbers and other forms of personal data. In mobile telephones conforming to the Global System for Mobile Communications (GSM) recommendations, a smart card is generally referred to as a subscriber identification module (SIM) card. The SIM card holds a subscriber&#39;s identity number, security information and memory for a personal directory of telephone numbers. An overview of SIM cards is given in “The GSM System for Mobile Communications” by M. Mouly &amp; M. B. Pautet, Sell &amp; Sys, 1992 (ISBN-9507190-0-7), pp 67-71. 
   It is desirable to provide a smart card reader module which is reliable in operation and allows for simple insertion and release of a smart card. 
   SUMMARY OF THE INVENTION 
   According to the present invention, there is provided a smart card reader module comprising a biasing member to eject a smart card inserted into the module and a locking member to retain an inserted smart card in the module, the biasing member being operable to eject a smart card from the module on release of the locking member. 
   Preferably, the module includes a chassis having a chamber therein and a slot to enable insertion of a smart card into the chamber. 
   The biasing means preferably includes an actuator and a spring, the arrangement being such that a partially inserted card contacts one end of the actuator, further insertion of the card causing the actuator to move with the card and thereby compress the spring to bias the card in a direction against the direction of insertion. 
   The actuator and spring are conveniently disposed in an elongate cavity in the chassis, said one end of the actuator protruding from the cavity into the chamber. 
   The spring may be a compression spring. 
   In a preferred embodiment, the locking member is mounted to a resilient latch arm. 
   Preferably, the latch arm is resiliently deformed in response to the pressure of a card on the locking member during insertion, the locking member being deflected by the card to allow insertion thereof into the chamber. 
   The resilience of the latch arm preferably returns the locking member to its original position when the pressure applied thereto by a card is removed. 
   In a preferred embodiment, the locking member comprises a release button and a card engaging arm extending laterally therefrom into the chamber. 
   Preferably, the locking member is deflected in response to pressure of a card on a leading edge of the card engaging arm during insertion. 
   The locking member is conveniently positioned in a cut out in the chassis. 
   In a preferred embodiment, the leading edge of the card engaging arm to which pressure is applied by a card is bevelled such that the card deflects the card engaging arm against the bias provided by the resiliently deformable latch arm to allow the card to pass over the card engaging arm during insertion. 
   The module is advantageously configured such that when a card has been fully inserted, it clears the card engaging arm, the resilience of the latch arm causing the locking member to return to its original position such that the card is retained in the module by the locking member. 
   The present invention preferably includes a smart card having a chamfered corner portion, the card engaging arm having an angled card engaging face configured such that when the card is inserted and the chamfered corner clears the card engaging portion, the locking member returns to its original position such that the angled card engaging face engages the chamfered corner to lock the card in the module, the arrangement being such that the card does not clear the card engaging arm when inserted in any other orientation. 
   The smart card is preferably a subscriber identification module (SIM). 
   The reader module is preferably configured such that the resilient latch arm is deformed in response to pressure on the button to deflect the card engaging arm out of the chamber thereby releasing the card from the module. 
   The latch arm is conveniently integral with the cover plate. 
   The present invention also includes a mobile telecommunications device incorporating a smart card reader module according to the invention. 
   The mobile telephone of the invention preferably includes a casing and a battery pack, a smart card being inserted into the module through an opening in the casing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an illustration showing a perspective front view of a mobile telephone; 
       FIG. 2  is a schematic illustration the main components of the mobile telephone shown in  FIGS. 1  for connection to a cellular or cordless network; 
       FIG. 3  is a perspective view of a smart card reader module for mounting in the telephone illustrated in  FIGS. 1 and 2 ; 
       FIG. 4  is a top plan view of the chassis of the smart card reader shown in  FIG. 3 ; 
       FIG. 5  is a side elevation of the locking member and a portion of the smart card reader module shown in  FIG. 4 ; 
       FIG. 6  is an exploded perspective view of the smart card reader shown in  FIGS. 3 and 4 ; and 
       FIG. 7  is a perspective view of the locking member forming part of the smart card reader module shown in  FIGS. 3 ,  4  and  6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. 
   The general components and operation  1  of a mobile telephone  1  will now be described with reference to  FIGS. 1 and 2 . The telephone  1  has a front face  2  and rear face  3  and comprises a user interface having a keypad  4 , a display  5 , an ear piece  6 , a microphone  7  and an on/off key  8 . The telephone  1  is adapted for communication via a wireless telecommunications network, e.g. a cellular network. However, the telephone  1  could also have been designed for a cordless network. The keypad  4  has a first group of keys which are alphanumeric and by means of which a user can enter a telephone number, write a text message (SMS) or write a name associated with a particular number, etc. 
   The keypad  4  additionally includes two soft keys  9 , the functionality of which depends on the state of the telephone and the navigation in the menu by means of a navigation key  10 , and two call handling keys  10   a  which can be used for establishing a call or a conference call, terminating a call or rejecting an incoming call. 
     FIG. 2  illustrates the main parts of the telephone  1  which is adapted for use in connection with a GSM network or any other mobile telephone network and may also be configured to meet the wireless application protocol specification (WAP). The telephone is driven by a removable battery pack  13 . Signal processing is carried out under the control of a digital micro-controller  14  which has an associated RAM/ROM  15  and a flash memory  16 . Electric analogue audio signals are produced by microphone  7  and amplified by pre-amplifier  17 . Similarly, analogue audio signals are fed to ear piece  6  through amplifier  18 . The micro-controller  14  receives instruction signals from the keypad  4  including the soft keys  9  and navigation key  10  and controls the operation of the display  5 . 
   Information concerning the identity of a user is held on a smart card  19  in the form of a GSM SIM card. The SIM card  16  is removably received in a SIM card holder  20 . Radio signals are transmitted and received by means of an antenna  21  connected through an rf stage  22  to a codec  23  configured to process signals under the control of the micro-controller  14 . Thus, in use, for speech, the codec  23  receives analogue signals from microphone amplifier  17 , digitises them into a form suitable for transmission and feeds them to the rf stage  22  for transmission through antenna element  21  to the public land mobile network (PLMN). Similarly, received signals are fed through the antenna element  21  to be demodulated by the rf stage  22  and fed to codec  23  so as to produce analogue signals fed to amplifier  18  and ear piece  6 . 
   An example of a SIM card holder  20  in accordance with the present invention will now be described in detail with reference to  FIGS. 3  to  7 . 
   A perspective view of the SIM card holder  20  is shown in FIG.  3  and comprises a chassis  25  having a chamber  26  therein to receive a SIM card  27  (corresponding to the SIM card  19  shown in  FIG. 2 ) through a slot  28  in the front face  29  of the chassis  25 . The chassis  25  includes four mounting flanges  30  having apertures  31  therethrough for the passage of fasteners (not shown) to enable the chassis  25  to be mounted to the inside of an electronic apparatus such as the mobile telephone  1  described with reference to  FIGS. 1 and 2 . The chassis  25  has a bottom wall  32  that is provided with a plurality of terminals  33  to connect the electronic circuitry of the telephone  1  with a conductive module (not shown) embedded in the underside of the SIM card  27  when inserted into the chamber  26  through the slot  28  in the direction of arrow X in FIG.  3 . The chassis  25  also has a cut out region  24  adjacent to the slot  28  in the front face  29  in which a locking member  46  is disposed for engagement with an inserted SIM card  27 . The SIM card  27  has a leading edge  27   a  and a trailing edge  27   b . One corner  27   c  of the trailing edge  27   b  is cropped or chamfered. The locking member  46  and the interaction between it and a SIM card  27  will be described hereinafter. 
   As can be seen most clearly in  FIG. 6 , the chassis  25  includes a cavity  35  extending from the front face  29  of the chassis  25  alongside the chamber  26 . A spring holder  36  is disposed within the cavity  35  and includes a card engaging portion  37  that protrudes into the chamber  26  and an elongate recess  38  to receive a compression spring  39 . The spring  39  is constrained between a shoulder  40  integrally formed on the chassis  25  and the end  38   a  of the elongate recess  38  of the spring holder  36 . The spring holder  36  is slideable in the cavity  35  against a bias provided by the compression spring  39 . 
   A plate  42  is mounted on the chassis  25  and covers the cavity  35  containing the spring holder  36  and spring  39  as well as forming the top wall of the chamber  26 . The plate  42  extends over the chassis  25  and has edge portions  43 ,  44  which are folded downwardly over the side walls of the chassis  25 . A portion of the plate extending over the surface of the chassis  25  is folded back on itself to form a resiliently deflectable latch spring arm  45  having a hooked end part  47  that terminates in the cut out region  24  below the level of the slot  28 . 
   The locking member  46  is mounted on the hooked end part  47  of the latch spring arm  45  and fits within the cut out region  24 . The locking member  46  includes a base part  48 , a actuator button  49  upstanding from the base part  48 , and a card engaging arm  50  extending laterally from the base part  48  into the chamber  26 . The actuator button  49  has a protrusion  51  which rests on the hooked end part  47  of the latch spring arm  45 , as will be apparent from FIG.  5 . 
   The card engaging arm  50  is integrally formed with the locking member  46  and has a flat upper surface  52  and a bevelled or angled leading edge face  53 . The rear edge is cut at an angle to present an angled locking face  54  and the reason for this will become apparent. 
   The plate  42  includes a further central section also bent back on itself over the chassis  25  to form a resiliently deflectable arm  55 . A battery pack release button  56  is mounted on the end of this arm and incorporates a latch member  57  that cooperates with the battery pack  13  (not shown in  FIGS. 3  to  7 ) to lock it in position on the telephone  1 . To remove the battery pack  13 , the user presses the button  56  which disengages the latch  57  from the battery pack  13  which can then be removed. Release of the button  56  causes it to return to its original position due to the resilience of the arm  55 . 
   The method of operation of the SIM card holder will now be described. A SIM card  27  is inserted through the slot  28  in the direction of arrow X in  FIG. 3  with its leading edge  27   a  to the front and with the cropped corner  27   c  of the trailing edge  27   b  to the rear and to the right when looking at the front face  29  of the chassis  25 . To insert the card  27 , pressure must be applied with the leading edge  27   a  to the angled leading edge face  53  of the card engaging arm  50  to deflect the locking member  46  downwardly in the direction of arrow Y in FIG.  3  and against the bias provided by the resiliently deformable latch spring arm  45 , thereby allowing the card  27  to pass over the card engaging arm  50  into the chamber  26 . It will be appreciated that the locking member  46  is easily deflected to allow insertion of the card  27  due to the angled leading edge face  53  on the card engaging arm  50 . When the card  27  has been fully inserted into the chamber  26 , the length of the chamber  26  is such that the chamfered corner  27   c  just clears the card engaging arm  50  of the locking member  46  and the resilience of the spring latch arm  45  causes it to return to its original position in which the card engaging arm  50  extends into the chamber  26 . The locking face  54  is angled to correspond to the angle of the chamfered or cropped corner  27   c  of the SIM card  27  so that if the SIM card  27  is inserted in any other orientation, the unchamfered corner of the card  27  will not clear the card engaging arm  50  when fully inserted into the chamber  26 , so the locking member  46  will not return to its original position. 
   When the SIM card  27  has been partially inserted into the chamber  26 , the leading edge  27   a  of the SIM card  27  contacts the card engaging portion  37  protruding into the chamber  26  on the end of the spring holder  38 . Further insertion of the card  27  causes the spring holder  38  to slide in the cavity  35  together with the card  27  and compress the spring  39  thereby biasing the card  27  against its direction of insertion. Therefore, the card  27  is automatically or self-biased in a direction opposite to that in which it is being inserted during insertion of the card  27 . The person inserting the card  27  must apply sufficient pressure to it when contact with the card engaging portion  37  has been made to compress the spring  39  and bias the card  27  in the direction opposite to that in which it is being inserted. When the card  27  has been fully inserted in the correct orientation, the locking member  46  returns to its original position due to the resilience of the latch arm  45  and the card  27  is retained in the chamber  26  upon release by the person inserting it as the trailing edge  27   b  of the card  27  is biased against the angled locking face  54  by the spring holder  38  and spring  39 . If the card  27  has been inserted in an incorrect orientation, the locking member  46  does not return to its original location when the card  27  has been fully inserted, as it cannot be inserted far enough into the module so that it clears the card engaging arm  50 . Therefore, when the card  27  is released by the person inserting it, it is not retained against the angled locking face  54  of the locking means  46  but is ejected by the bias. This ensures that the card  27  will not be retained in the chamber  26  when it is inserted in an incorrect orientation and automatically ejects it when released, to enable the user to re-insert it in the correct orientation. 
   When a card  27  that has been correctly inserted is to be removed, the user presses the actuator button  49  downwardly in the direction as shown by arrow Z in  FIG. 5  to deflect the latch arm  45  so that the card engaging arm  50  is no longer blocking the passage of the card  27  from the chamber  26 . When the button  49  is depressed, the spring holder  38  and spring  39  ejects the card  27  from the chamber  26 . 
   In a preferred arrangement, the spring  39  has a sufficient compressive force to only partially eject the card  27  from the module so that approximately 8 mm of the card  27  protrudes from the slot  28 . This enables the end of the card  27  near to the to trailing edge  27   b  to be held between the fingers so that it can be removed from the module easily. 
   The actuator button  49  extends through an aperture (not shown) in the telephone housing. To prevent accidental actuation of the button  49  and ejection of the smart card  27  from the module, the module is located so that the slot  28  faces the end of the battery pack  13  so that the battery pack  13  must be removed before access to the slot  28  can be obtained. If the button  49  is pressed while the battery pack  13  is in position, the card  27  will not be ejected from the module as it is prevented from doing so by the battery pack  13 . 
   Many modifications and variations of the invention falling within the terms of the following claims will be apparent to those skilled in the art and the foregoing description should be regarded as a description of the preferred embodiments only. For example, the reader may be installed in apparatus other than a mobile telephone such as a personal digital assistant.