Abstract:
A thin integrated circuit card with an improved manually activated switch. The card is of the type that has two external plates, a lower one ( 12 ) and an upper one ( 14 ) that are separated by at least one interconnecting plate in which there is at least one switch ( 26 ). The switch is able to allow or inhibit the passage of an electric current between its two terminals ( 34 ). The switch has a pushbutton ( 28 ) which is positioned at a peripheral edge ( 40 ) of the card.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a thin integrated circuit card having an improved manually actuated switch. 
     The invention relates in particular to an integrated circuit card of the type having two external plates, a lower and an upper plate, separated by at least one intermediate plate, of the type in which the plates have electronic components connected to each other by conducting traces, and of the type containing at least one switch able to allow or prohibit passage of an electric current between two of its terminals that are connected to at least one of the traces. 
     Because new manufacturing techniques have been developed, it is now possible to obtain very small-sized electronic components that can be integrated into cards with a very small total thickness. 
     2. Description of the Related Art 
     French Patent Application No. 96.12661 has now proposed an integrated circuit card having both a chip with flush contacts and a circuit for producing sound signals that is connected to a sound transducer, the whole being contained in the total thickness of the card which does not exceed 0.8 mm, which is compatible with the widest-spread standard format for integrated circuit cards. 
     Such cards, provided with a sound signal producing circuit, can transmit coded information over a classic telephone line, such information serving for example for remote control of various types of apparatus. 
     This information is generally coded by a principle known in English as “dual tone modulation frequency (DTMF).” 
     However, the presence of such a circuit requires provision of a trigger switch designed to be actuated by the card user to cause coded signals to be transmitted. 
     According to the prior art, such switches are made in the form of a deformable dome provided on one of the external faces of the card, which the user must press in the thickness direction of the card to establish an electrical contact between the deformed dome and a conducting area provided opposite the dome on one of the faces of the card. 
     To trigger such a switch, the user must grip the card in its thickness direction, for example between the thumb and index finger, and he generally applies substantial force to the card which necessarily bends it, particular in the case of very thin cards. 
     Such bending, repeated regularly, can eventually damage some of the components of the card, which then becomes unusable. 
     BRIEF SUMMARY OF THE INVENTION 
     The goal of the invention is thus to provide a switch for a very thin integrated circuit card whose design allows easy manipulation by the user without subjecting the card to excess force. 
     With this goal, the invention provides an integrated circuit card of the type seen previously, characterized in that the switch has a pushbutton provided at one peripheral edge of the card, which slides in a lengthwise direction in the plane of the card between an active and a resting position, and which controls a contact key designed to connect the terminals of the switch electrically. 
     According to other characteristics of the invention: 
     The pushbutton of the switch is guided in a vertical direction perpendicularly to the general plane of card by two faces opposite each other, an upper face and a lower face, of two plates of the card; 
     The pushbutton of the switch is received at least partially in a slot formed in at least one of the intermediate plates which terminates in a peripheral edge of the card, and whose two lengthwise edges, opposite each other, guide the pushbutton; 
     The pushbutton of the switch has at least one tab that extends in a transverse direction in the general plane of the card, the tab is received in an opening provided in one of the lengthwise edges of slot of the intermediate plate, and the travel of the pushbutton in the lengthwise direction is determined, in at least one direction, by cooperation of the tab with one lengthwise end transverse edge of the opening; 
     The pushbutton is in the shape of a plate, it has a rear control edge, in it has two lengthwise side edges that guide it in the slot, the pushbutton has two transverse tabs that extend transversely outward from each of its lateral edges and are received in two openings formed in the lengthwise edges of the slot, and it has a T-shaped cutout of which a lengthwise portion terminates rearward in a transverse portion of the cutout and frontward in a the front edge of the pushbutton; 
     The pushbutton is returned elastically to its resting position by a return spring; 
     The return spring is provided between the front edge of the pushbutton and a bottom transverse edge of the slot; 
     The return spring is provided in the form of a deformable elastic blade whose center portion is supported by the bottom edge of the slot and whose two edges are bent back so that they contact the front edge of the pushbutton on either side of the front edge of the cutout; 
     The rear edge controlling the pushbutton is flush with the edge of the card when the pushbutton is in the resting position, and the outer plates of the card have, opposite the slot, notches formed in their edges to allow the user to urge the pushbutton lengthwise toward the inside of the card into its active position, particularly by acting on the pushbutton by one of his fingers; 
     The contact key is parallelepipedic, it is received in the transverse portion of the cutout of the pushbutton, and one front face of the contact key is designed to cooperate with a fixed component of the switch which, when the pushbutton is in the active position, is received inside the lengthwise portion of the cutout of the pushbutton; 
     The fixed component has two ends connected to the terminals of the switch, which are intended to be connected electrically by the contact key when the pushbutton is in the active position; 
     The fixed component is an insulator, both of whose ends are metallized and which is intended to be short-circuited by the contact key; 
     The fixed component is a capacitor, and the contact key is designed to cause the capacitor to discharge; 
     The contact key of the switch is a conducting pellet made of a polymer material containing conducting particles; 
     The switch causes an active component of the card to be triggered; 
     The switch controls a circuit that produces sound signals; 
     The thickness of the card is approximately 0.8 mm. 
     Other characteristics and advantages of the invention will emerge from reading the detailed description that follows, for understanding of which reference will be made to the attached drawings wherein: 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a perspective exploded schematic view of an integrated circuit card provided with a switch according to the teachings of the invention; 
     FIGS. 2 and 3 are partial plane views in which the switch according to the invention has been illustrated in the resting position and in the active position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an integrated circuit card  10  whose structure is essentially composed of two outer plates, a lower plate  12  and an upper plate  14 , separated by an intermediate plate  16 . 
     As can be seen in FIG. 1, upper face  18  of lower plate  12  has electronic components connected together by conducting traces to form, among other things, a control circuit for a generator of sound signals supplied to a sound transducer  22 . 
     Card  10  can also have other types of components and circuits (not shown) such as a memory module with flush contacts enabling data to be exchanged with an apparatus provided with a suitable reader. 
     Intermediate plate  16  is critical to the rigidity of the card and has openings  24 , or windows, designed to accommodate the electronic components when card  10  is assembled. 
     Lower plate  12  is for example approximately 0.2 mm thick while intermediate plate  16  can be between 0.4 and 0.5 mm thick, upper plate  14  being very thin. 
     In certain cases, upper plate  14  can also carry electronic components. 
     It would also be possible to provide several stacked intermediate plates, provided with various windows. 
     Intermediate card  16  can also have metallized areas (not shown) designed to connect some of the circuits contained in the card with each other. 
     According to the teaching of the invention, card  10  has a switch  26  designed to allow the sound-signal-producing circuit connected to sound transducer  22  to be triggered. 
     According to a first feature of the invention, switch  26  is designed to be mounted between lower plate  12  and upper plate  14  slidably in a lengthwise direction in the general plane of card  10 . 
     Switch  26  has an actuating pushbutton  28  provided with a contact key  30  that constitutes the trigger element of switch  26  and is designed to come in contact with a fixed component  32  of switch  26  when pushbutton  28  is urged from a shown in FIG. 3, which component  32  is electrically connected to two terminals  34  of switch  26 , the terminals being connected by conducting traces  36  to the control circuit of transducer  22 . 
     A return spring  37  is also provided to continuously urge pushbutton  28  into its resting position. 
     Pushbutton  28  is an element also in the shape of a plate, with the same thickness as intermediate plate  16 , and is guided lengthwise in a slot  38  provided in a rear edge  40  of intermediate plate  16 . 
     Slot  38  has two lengthwise edges  42  that are opposite and parallel to guide pushbutton  28  which is symmetrical with respect to the median lengthwise axis of symmetry X—X of slot  38 . 
     Slot  38  terminates rearward in rear edge  40  of intermediate plate  16  and is delimited lengthwise frontward by a front transverse edge  44 . 
     Slot  38  can advantageously by made simply and precisely by cutting with a high-pressure water jet or by laser cutting. 
     When card  10  is assembled, pushbutton  28  is then able to slide lengthwise in slot  38  and is guided, in a direction of the general plane of card  10 , by opposite inside faces  18 ,  46  of lower plate  12  and upper plate  14  is open lengthwise rearward in edge  40  of card  10 , and which close off slot  38  below and above. 
     Where several intermediate plates  16  exist, the thickness of pushbutton  28  may be such that it does not exceed the thickness of one of these intermediate plates, and pushbutton  28  is then guided between one of outside plates  12 ,  14  and an intermediate plate that has no guide slot. 
     Plate-shaped pushbutton  28  has a rear control edge  48  which is flush with rear edge  40  of intermediate plate  16  when pushbutton  28  is in its resting position shown in FIG.  2 . Moreover, outer plates  12 ,  14  are each provided with a notch  50  opposite the rear end of slot  38  so that the user can act on rear edge  48  of the pushbutton to urge it lengthwise in the direction of the inside of the card, toward the bottom of slot  38 , up to its active position shown in FIG.  3 . 
     By preventing pushbutton  28  from projecting beyond the side edges of the card, it is prevented from being inadvertently pushed into its active position. 
     The lengthwise travel of pushbutton  28  in slot  38  is determined by two tabs  52  that extend transversely in the general plane of card  10  from two lengthwise lateral edges  54  of pushbutton  28  which cooperate with the lengthwise edges  42  of slot  38  to guide pushbutton  28 . 
     Tabs  52  are received in openings  56  cut transversely into lengthwise edges  42  of slot  38 . 
     Openings  56  are delimited lengthwise by rear transverse edge  58  and front transverse edge  60  with which tabs  52  cooperate to determine the resting position and active position, respectively, of pushbutton  28 . 
     The travel of pushbutton  28  can for example be approximately 0.5 mm. 
     Pushbutton  28  is provided with a T-shaped cutout having essentially a transverse part  64  arranged substantially in the center of pushbutton  28  and a lengthwise part  68  that extends along axis of symmetry X—X of switch  26  and which terminates rearward at transverse portion  64 , and frontward at a front transverse edge  70  of pushbutton  28 . 
     Contact key  30 , which is parallelepipedic in shape, is designed to be inserted vertically into transverse portion  64  of cutout  62  in order to have a front face portion  72  which forms a rear transverse bottom for lengthwise portion  68  of cutout  62 . 
     Key  30  is of substantially the same thickness as pushbutton  28  and as intermediate plate  16  so that it is also held in the direction perpendicular to the general plane of card  10  by outer plates  12 ,  14  with no need for additional fastening means. 
     Spring  37  that returns pushbutton  28  to its resting position is composed of a deformable blade that has a central portion  74  supported by the rear transverse edge  44  of slot  38 . Central portion  74  is extended on each side by arms  76  that are bent rearward lengthwise in the plane of card  10  and whose free ends  78 , bent back transversely outward relative to axis of symmetry X—X, rest on front transverse edge  70  of pushbutton  28  on outer side of the front lengthwise end of the two lengthwise portion  68  of cutout  62 . 
     Thus, when pushbutton  28  is urged lengthwise into its active position, arms  76  of pushbutton  28  are elastically bent transversely outward, and when the user releases the pressure on rear edge  48 , pushbutton  28  is returned to its resting position. 
     There are various options for the choice of fixed component  32  of switch  26 . 
     Fixed component  32  can for example be a pellet made of a ceramic insulator, substantially parallelepipedic in shape, whose two transverse end sections  80  are metallized and connected electrically to terminals  34  of switch  26 . 
     Fixed component  32  is then joined to upper face  18  of lower plate  12  such that, when pushbutton  28  is in the active position, fixed component  32  is received in lengthwise portion  68  of cutout  62  of pushbutton  28 , and front face  72  of contact key  30  electrically connects the two ends  80  of fixed component  32  which has the result of closing an electrical circuit enabling control circuit  20  to trigger the production of sound signals. 
     Switch  26 , here of the normally open type, can also be of the normally closed type. 
     Fixed component  32  can also be made in the form of a capacitor with a similar structure. Current techniques allow capacitors 0.35 mm thick to be manufactured inexpensively and reliably. 
     When key  30  comes in contact with fixed component  32 , it causes the capacitor, which had previously been electrically charged, to discharge, causing the difference in voltage at terminals  34  of switch  26  to drop suddenly, and this signal can be detected by control circuit  20 . 
     In both cases, it is advantageous to use a contact key  30  made in the form of a polymer material containing conducting particles. 
     Indeed, a “negative” play can be provided between front face  72  of contact key  30  and fixed component  32  when pushbutton  28  is in the active position, namely its front face  72  is slightly in front of a rear face of component  32 . 
     Front face  72  is then able to deform so that, on the one hand, it can be in perfect contact with fixed component  32  in order to provide a reliable electrical connection between the two metallized ends  80  of fixed component  32  and, on the other hand, to limit the stresses transmitted to fixed component  32  that could tear it off lower plate  12 . 
     Moreover, this enables manufacturing tolerances of such a switch  26  to be increased to the benefit of the production cost. 
     Such a design for switch  26  in card  10  enables the forces necessary for manipulating switch  26  to be directed in the general plane of card  10 , preventing it from being deformed without its thickness having to be increased. However, such a switch can also be used in thicker cards, while preserving the benefit of simplicity of production and use. 
     Of course, such a design for switch  26  can readily be used to control all types of integrated circuits in a thin card. 
     Moreover, such a switch is small in size, so that several switches can be provided on the same card to carry out different functions.