Abstract:
A reader ( 18 ) for a smart card (S) for a mobile telephone ( 10 ) includes a baseplate ( 40 ), carrying conducting contacts suitable for engaging with corresponding conducting contacts on the card (S), and a device for guiding and actuating the card (S) for translational movement thereof in a direction of installation (D 1 ) of the card, between a card-gripping position in which the card is accessible and a use position in which the card (S) is held in place with respect to the baseplate ( 40 ). The device for guiding and actuating the card includes a movable slide-in unit ( 42 ) for supporting the card (S) and a device for immobilizing the card (S) in the direction of installation (D 1 ). The slide-in unit ( 42 ) slides with respect to the baseplate ( 40 ) between an engaged position in which the card (S) is in a use position and a disengaged position in which the card (S) is in a gripping position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a reader for a smart card, especially an identification smart card, for a mobile telephone, of the type comprising a baseplate, carrying conducting contacts suitable for engaging with corresponding conducting contacts on the card, and means for guiding and actuating the card for its translational movement in a direction of installation of the card, between a card-gripping position in which the card is accessible and a use position in which the card is held in place with respect to the baseplate. 
     2. Discussion of Background 
     In the GSM standard, identification smart cards for cellular telephones are generally called “SIM (Subscriber Identity Module) cards”. Such a smart card has an integrated circuit used for storing the identity of a subscriber having right of access to the network, as well as algorithms for authenticating the latter. 
     SIM cards are rectangular in shape. One of the corners is cut off as a bevel. This cut-off corner provides the polarization function, so as to ensure that the card is correctly positioned in the reader. The contacts on the chip are visible on the same side of a main face of the card with which they are flush. 
     SIM card readers of certain mobile telephones include connectors placed directly on the motherboard of the telephone. The connectors then occupy a large amount of space on the motherboard, which increases the area of the motherboard and therefore the overall size of the telephone. 
     In order to reduce the area of the motherboard, the smart-card readers are advantageously separated from it. 
     Document U.S. Pat. No. 5,790,659 describes, by way of example, a card reader of the aforementioned type. With this reader, the card is inserted into the reader through a slot made inside the body of the telephone. When the card is in its use position, it is completely concealed inside the body. Thus, in order to allow the user to remove it, a pusher is provided in the card reader. This pusher is controlled by a knob projecting on the rear face of the telephone. 
     However, the insertion and removal of the card are not straightforward since the pusher has a very short travel. Thus, the card, after it has been moved by the pusher, projects only a few millimetres from the reader and it is difficult to grip it by its free end. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a solution to the problem of the difficulty of handling a SIM card when inserting it into or removing it from a card reader, especially one installed in a mobile telephone. 
     For this purpose, the subject of the invention is a reader for an identification smart card, especially for a mobile telephone, of the aforementioned type, characterized in that the means for guiding and actuating the card comprise a movable slide-in unit for supporting the card, having means for immobilizing the card in said direction of installation, which slide-in unit can move slidingly with respect to said baseplate between an engaged position in which the card is in its use position and a disengaged position in which the card is in its gripping position, in that the slide-in unit comprises means for supporting the card forming, at least partially, an area of support for the card in its gripping position and said area of support is open for the insertion of the card in its gripping position in a direction of insertion which is offset at some angle to said direction of installation, said direction of insertion being parallel to said area of support for the card. 
     Depending on the particular embodiments, the reader has one or more of the following characteristics: 
     the conducting contacts on the card and on the baseplate are far apart in the gripping position of the card and the conducting contacts on the card and on the baseplate are in contact with each other in the use position of the card; 
     said area of support for the card in its gripping position is formed, on the one hand, by said means for supporting the card and, on the other hand, by a bearing surface made on the baseplate; 
     the baseplate has a ramp for guiding the card towards said bearing surface, which ramp is inclined so that its height varies along the direction of insertion of the card; 
     the slide-in unit has an end stop for the card in its gripping position while it is being put into position on the area of support in said direction of insertion; 
     the slide-in unit has a cut-away for manual access to the card in its gripping position in order to move it in the direction of insertion for the purpose of removing it; 
     the slide-in unit has a blade for masking the conducting contacts on the baseplate, which blade can be moved between a position in which it is away from the conducting contacts, when the slide-in unit is in its engaged position, and a position in which it masks the conducting contacts, preventing access to them when the slide-in unit is in its disengaged position; 
     the baseplate has a base through which the conducting contacts project and tabs for retaining the card in its use position in contact with the conducting contacts, said tabs extending so as to face said base; 
     the baseplate has surfaces for laterally guiding the card, which surfaces extend along the direction of installation of the card; 
     the baseplate has an end stop for the card in its use position during its movement in the direction of installation; 
     the end stop for the card carried by the baseplate and the means for immobilizing the card in the direction of installation have intercalated complementary projecting profiles, which can move translationally with respect to each other in said direction of installation. 
     The subject of the invention is also an item of telecommunication equipment, especially a mobile item of telecommunication equipment, especially a mobile telephone, having a card reader as defined above. 
     Depending on the particular embodiments, the mobile item of equipment has one or more of the following characteristics: 
     the item of equipment comprises a body in which a housing for accommodating a supply battery is defined, and means preventing the slide-in unit from moving towards its disengaged position when the battery is accommodated in the housing; 
     the item of equipment comprises a body in which a housing for accommodating a supply battery is defined, and means preventing the battery from being accommodated in the housing when the slide-in unit is not in its engaged position; 
     in the disengaged position, the movable slide-in unit projects inside the housing in a region normally occupied by the supply battery; 
     the body of the item of equipment has a recess made at least opposite the conducting contacts on the baseplate, making said conducting contacts accessible in the absence of the slide-in unit; 
     the slide-in unit, in the engaged position, extends into said recess and has a manoeuvring surface accessible through said recess; 
     the body of the item of equipment has a cut-away, which cut-away partially defines a passage for inserting the card in said direction of insertion towards its gripping position; 
     the body of the item of equipment has means for guiding the slide-in unit in said direction of installation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more clearly understood on reading the description which follows, given solely by way of example, and with reference to the drawings in which: 
     FIGS. 1 and 2 are three-quarter perspective views of the rear face of a mobile telephone according to the invention, the supply battery of which has been removed, and in which figures the slide-in unit for supporting the SIM card is in the engaged position and in the disengaged position, respectively; 
     FIG. 3 is a longitudinal sectional view of the mobile telephone in FIG. 2, taken in a plane passing through the movable slide-in unit; 
     FIG. 4 is a simplified longitudinal sectional view of the mobile telephone in FIG. 1, in which a supply battery has been fixed to the body; 
     FIGS. 5 and 6 are three-quarter perspective views of the top and bottom, respectively, of the baseplate of the reader according to the invention; and 
     FIGS. 7 and 8 are three-quarter perspective views of the top and bottom, respectively, of the movable slide-in unit of the reader according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1 to  8  thereof, there are illustrated embodiments of the present invention as will now be discussed. 
     The mobile telephone  10  shown in FIGS. 1 to  4  comprises a body  12  from a rear face  14  of which emerges a housing  16  for accommodating a supply battery  16 A, visible in FIG.  4 . The housing  16  occupies most of the lower region of the rear face  14 . The upper region of the rear face  14  is bounded by a cover  17  which extends the external surface of the battery  16 A when the latter is installed in the housing  16 . 
     A SIM card reader  18  emerging in the housing  16  is provided in the body  12 . It is manually accessible from the cover  17 , under which it is placed. 
     As shown in FIG. 3, the telephone  10  has, on its front face opposite the rear face  14 , a keypad  20 , a display screen  22 , a microphone (not shown) provided at its lower end  24  and a sound reproduction element (not shown) placed near its upper end  26 . A motherboard  28  is placed inside the body  12 . Most of the electronic components for operating the mobile telephone are placed on this motherboard. 
     The reader  18  essentially comprises, on the one hand, a baseplate  40  bearing conducting metal contacts intended to come into contact with the chip of a SIM card denoted by S and, on the other hand, a movable slide-in unit  42  for supporting the card S. 
     The movable slide-in unit  42  for supporting the card can move slidingly with respect to the baseplate  40  in a direction of installation D 1  parallel to the motherboard  28 . The slide-in unit can move between an engaged position, in which the slide-in unit is engaged in the body  12 , and a disengaged position, in which the slide-in unit is disengaged from the body. In the engaged position, in which it is engaged in the body, as shown in FIGS. 1 and 4, the card S is in a use position. The conducting contacts on the card S and on the baseplate  40  are then applied against each other and the card is held in place with respect to the baseplate. In the disengaged position, when it is disengaged from the body, shown in FIGS. 2 and 3, the card S is in a gripping position. The conducting contacts on the card S and on the baseplate  40  are then far apart and the card is accessible. 
     The card can be inserted into the slide-in unit  42  in a direction of insertion D 2  which is offset at some angle to the direction of installation D 1 . The directions D 1  and D 2  are advantageously orthogonal. 
     The baseplate  40  is placed inside the body of the telephone opposite a recess  44  of rectangular shape which extends longitudinally on the rear face  14  in the direction D 1 . The recess  44  emerges at its free end in the housing  16  for accommodating the battery. In the engaged position, the external surface of the slide-in unit  42  fills the recess  44  and is flush with the cover  17 , providing a continuous surface with the latter. 
     The body  12  has, along the longitudinal edges of the recess  44 , means  46  for guiding the slide-in unit  42 . These means comprise, for example, rails placed along the direction of installation D 1 . 
     The baseplate  40  shown in FIGS. 5 and 6 has a base  50  intended to support that face of the card S with which the contacts on the chip are flush when the card is in the use position. The base  50  extends parallel to the direction of installation D 1  of the card and has a rectangular general shape, the length of which extends along the direction D 1 . 
     At an end for inserting the card, denoted by  52 , the base  50  has a bearing surface  53  for the card in its gripping position. 
     At this end, the base  50  is extended externally by a transverse wall  54  extending parallel to the surface of the base  50 . The wall  54  is provided on its free edge opposite the base  50  with notches  56  for passage of curved first ends  58  of the flexible conducting blades  60 . 
     As shown in FIG. 6, the conducting blades  60 , shown in a simplified manner, extend parallel to the lower surface of the base  50  and project at their second ends  62  through windows  64  passing through the base  50 . The ends  62  are bent so as to form conducting contacts which are applied, by elastic deformation, against the corresponding conducting contacts on the chip carried by the card S. 
     As shown in FIGS. 3 and 4, the baseplate  40  is placed so that it extends parallel to the motherboard  28 , the ends  58  of the conducting blades  60  being applied against the latter so as to provide electrical continuity between the chip on the card S and the other components of the motherboard  28 . 
     Furthermore, the baseplate  40  is placed partially opposite the recess  44  so that the conducting contacts  62  are accessible through the recess in the absence of the slide-in unit  42 . 
     The base  50  is bordered, on both sides, along its length, by tabs  72 ,  74 ,  76 ,  78  for retaining the card S against the base  50 . The tabs  72  to  78  each have a pillar  72 A,  74 A,  76 A,  78 A extending perpendicular to the surface of the base  50 . The pillars define surfaces for guiding the card S laterally during its movement in the direction of installation D 1 . Each pillar  72  to  78  is extended by a retaining flange denoted by  72 B,  74 B,  76 B and  78 B respectively. These flanges extend in a cantilever fashion above the base  50  and parallel to the latter. 
     The height between the facing surfaces of the base  50  and of the flanges  72 B to  78 B is fixed by the height of the pillars  72 A to  78 A. The height of this gap, denoted by I, is approximately equal to the thickness of the card S plus a fraction of the height of the conducting contacts. 
     Thus, a slot for guiding the card, extending along the direction of installation D 1 , is defined between the base  50  and the tabs  72  to  78 . 
     The retaining tabs  72  and  78  extend parallel to each other along the length of the base  50  in the running part of the latter. The retaining tabs  74  and  76  are provided in the corners of the rear end, denoted by  80 , of the base  50 , this end being opposite the insertion end  52 . 
     The foot  74 A has an inclined lateral surface  90  designed to engage with the cut-off corner of the card S. The inclined face  90  defines an angle of 45° with the longitudinal axis of the base  50 . 
     At its rear end  80 , the base  50  has an end stop for the card S in the direction D 1 . This stop is formed by studs denoted by  92  which project from the surface of the base  50 . These studs together define a comb. These stops are designed to engage with the end of the card S and to provide correct axial positioning of the latter with respect to the conducting contacts  62 . The height of the studs  92  is approximately equal to that of the gap I. 
     The studs  92  between them define crenels designed to accommodate elements of complementary shape provided by the slide-in unit  42 . 
     One of the crenels is of greater depth. It is extended over the entire length of the base  50  by a longitudinal groove  94  extending along the direction D 1 . This groove  94  has, at the insertion end  52  of the baseplate, a gradually increasing width. The groove  94  runs out at its two ends. 
     At its insertion end  52 , the baseplate  40  has a lateral ramp  100  for guiding the card S during its insertion into the slide-in unit  42 . This ramp is oriented transversely to the longitudinal axis D 1  of the base  50 . It extends in a region of the base devoid of card-retaining tabs. 
     In the example shown, the ramp is made in the thickness of the transverse wall  54 . 
     Moreover, provided on both sides of the bearing surface  53  are chamfers  101 A and  101 B, these being on an extension  101  of the pillar  72 A and on the pillar  78 A, respectively. The function of these chamfers is to facilitate the insertion of the card S between the surfaces  101 ,  72 A,  78 A and  76 A for guiding the card S laterally. 
     As shown in FIGS. 1 and 2, the housing  16  for accommodating the battery  16 A is extended in the cover  17  of the telephone by a cut-away  110  made opposite the ramp  100 , in front of the tab  78 . The cut-away  110  allows passage for the front end of the card during its transverse engagement into the slide-in unit  42  along the direction of insertion D 2 . 
     The slide-in unit  42  is shown by itself in FIGS. 7 and 8. 
     It comprises an elongate body  150  provided with means for supporting a rear end of the card S and with means for retaining the latter in the direction of movement D 1  of the slide-in unit  42 . 
     The body  150  is provided at its rear end, in contact with the housing  16 , with a transverse wall  152  for supporting and axially retaining the card S. 
     At its front end, the body  150  is extended axially by a blade  154  for masking the conducting contacts  62 . 
     The body  150  has an approximately flat bottom  155  facing the inside of the body  12  of the telephone. The bottom has a ramp  155 A which favours the insertion of the card S. The body  150  has laterally, on each side, parallel guiding grooves  156  made in the thickness of the body. These grooves are designed to engage with the corresponding guiding rails  46  made in the cover  17  of the telephone, along the recess  44 . 
     The fit between the rails and the grooves is designed to ensure that the slide-in unit is held in place, by friction, in the engaged position even in the absence of the battery. The rails and the grooves have stop-forming complementary profiles, comprising projections and indentations, which prevent the slide-in unit from going back into the disengaged position. The projections have ramps allowing the slide-in unit to be put into place by the elastic deformation of these ramps. 
     The profile of the upper face, denoted by  157 , of the body  150  is designed to extend the rear face  14  of the telephone in a continuous manner, when the slide-in unit  42  is in its engaged position in the body of the telephone. The upper face  157  has two raised features  158  which make it easier for the slide-in unit  42  to be moved with a finger of one hand. 
     The width of the body  150  is less than the corresponding width of the card S. 
     The transverse wall  152  has an external shape corresponding to that of an opening made in the transverse wall of the body defining the housing  16 . It is extended laterally on each side of the body  150  over a distance greater than the width of the card S. 
     The transverse wall  152  constitutes an axial stop preventing the card S from moving with respect to the slide-in unit  42  in the direction of installation D 1  along which the slide-in unit  42  slides. 
     On its internal face, turned towards the body  150 , the transverse wall  152  has, on both sides of the body, pads  160 ,  162  for supporting the rear edge of the card S. 
     The pad  162 , placed on the opposite side from the side in which the card S is inserted into the slide-in unit  42 , is bordered by a lateral stop  164  designed to engage with the corner of the card S in order to position the latter correctly with respect to the slide-in unit before the latter moves into its engaged position. The stop  164  stops the card S during its insertion in the direction D 2 . The stop  164 , although retaining the card S on only one side is sufficient to stop it since the card S cannot rotate about the stop  164  as it is rotationally immobilized by the shoulders  184  on the one hand, and by the face internal to the slide-in unit of the wall  152  on the other hand. 
     Furthermore, the transverse wall  152  has, on its internal face, on the side for inserting the card S, a temporary bearing surface area  166  for the card, making it easier to insert the latter into the slide-in unit  52  before the card rests on the pads  160  and  162 . 
     The pads  160  and  162  are placed on the wall  152  at a height suitable for the card S, in its gripping position, to rest, on the one hand, on the pads  160  and  162  and, on the other hand, on the bearing surface  53  formed on the insertion edge of the base  50 . The card then extends parallel to the plane of the base and to the grooves  156 . The pads  160 ,  162  and the bearing surface  53  together form an area of support for the card S in its gripping position. In this position, a cut-away  168 , for manual access to the card S, is formed between the wall  152  and the baseplate  40 , because the body  150  has a smaller width than that of the card S and thus the latter protrudes on each side of the body  150 . Thus, the cut-away  168  makes it possible to push the card, using a finger, in the direction of insertion D 2 , so as to release the card from the slide-in unit. 
     The gap between the pads  160 ,  162  and the bottom of the body  150  is slightly greater than the thickness of the card S. 
     The masking blade  154  has a small thickness so as to be able to be accommodated in a recess in the body  12  beyond the baseplate  40 , when the slide-in unit  42  is in its engaged position. Its upper face, turned towards the outside, is essentially smooth. 
     The length of the masking blade  154  is slightly less than that of the base  50 . It is at least equal to the length of that region of the base which carries the conducting contacts  62 . Thus, the length of the masking blade  154  is such that, when the slide-in unit  42  is in the disengaged position, the blade covers the conducting contacts  62  and makes them inaccessible through the recess  44 . 
     Provided on the lower face of the masking blade  154 , which face is turned towards the baseplate  40 , are parallel axial ribs  180  designed to engage in the crenels bounded by the studs  92  and the pillars  74 A and  76 A. 
     At the free end of the masking blade  154 , the ribs  180  have ramps  182  which reduce their height towards this free end. 
     At their other end, the ribs  180  terminate in coplanar shoulders or steps  184  which together form an axial stop against which the front end of the card S bears. The distance separating the shoulders  184  from the facing surface of the transverse wall  152  is slightly greater than the total length of the card S. 
     The height of the ribs  180  is designed so that, during the sliding of the slide-in unit  42 , the surface of these ribs is approximately flush with the surface of the base  50 . Thus, the height of the ribs is approximately equal to the thickness of the card S. 
     One of the ribs  180  is designed to be partially accommodated in the longitudinal groove  94 . For this purpose, it has a height greater than that of the other ribs. Its height is approximately equal to the sum of the thickness of the card S and the depth of the groove  94 . 
     The card reader according to the invention is used in the following manner. 
     With the supply battery  16 A removed from the mobile telephone, the slide-in unit  42  is brought into its disengaged position (shown in FIGS. 2 and 3) by moving it in the direction D 1 . 
     The card S is then inserted into the slide-in unit  42  in the direction of insertion D 2 . For this purpose, the lateral edge of the card is first brought into contact with the ramp  100  and with the bearing area  166 . Next, the card is pushed inside the slide-in unit  42  using a finger of one hand. It then slides along the direction D 2 , being supported at one of its ends on the pads  160  and  162  and at its other end on the bearing surface  53  until it comes into contact with the end stop  164  of the slide-in unit. The card S may also be put into place by gravity, by tilting the telephone about the axis D 1  so that the area of support for the card, defined between the base and the slide-in unit, is vertical with the stop  164  under the bearing area  166 . 
     The movement of the card S is completed when the latter comes into contact with the end stop  164 . 
     In this position, the card S is then correctly aligned with the base  50 . 
     Next, the slide-in unit  42  is pushed manually in the direction D 1  towards its engaged position. During the movement of the slide-in unit  42 , the card S is pushed by the transverse wall  152 . The card S then slides over the base  50 , being guided laterally by the pillars  72 A to  78 A. 
     At the start of the travel of the slide-in unit, the card S is inserted between the pillars  72 A and  78 A, this insertion being facilitated by the chamfers  101 A and  101 B as well as by the cut-off corner of the card which slides over the chamfer  101 A. 
     The movement of the card S is completed when the latter comes into contact with the studs  92 . Once in contact with the latter, the card is correctly positioned so that the conducting contacts on the chip carried by the card are in contact with the conducting contacts  62  on the reader. 
     If the card S is not initially positioned correctly in the slide-in unit  42 , the slide-in unit cannot be brought completely into its engaged position since one of the corners of the card which has not been cut off then butts against the inclined surface  90 . The user is then aware of the insertion error, since it is impossible for him to put the battery in. 
     After the slide-in unit  42  has been engaged in the body of the telephone, the supply battery  16 A is repositioned in its housing  16 . The card S is then no longer accessible and the slide-in unit  42  can no longer be moved, the transverse wall  152  butting against the supply battery  16 A. 
     In order to remove the card, the supply battery  16 A must firstly be removed so as to allow the slide-in unit  42  to move. 
     By acting on the raised feature  158  with one finger, the slide-in unit is brought into its position in which it is partially disengaged from the body and in which it projects into the housing  16 . During the movement of the slide-in unit  42  in the direction D 1 , the shoulders  184  press on the front end of the card S and push the latter out of the body of the telephone. 
     Once the slide-in unit  42  is in its disengaged position, a finger of one hand inserted into the cut-away  168  allows the card S to be removed from the slide-in unit  42 , by moving the card in the direction D 2 . 
     In addition, since the card S is not constrained by the pressure of the conducting contacts when the slide-in unit is in the disengaged position, an alternative way of removing the card S from the slide-in unit is to tilt the telephone about the axis D 1  so that the area of support for the card, partially defined by the slide-in unit, and therefore the card, are thus brought into a vertical plane, the stop  164  being above the bearing area  166 , and so that the card falls out of the slide-in unit under the effect of gravity. 
     The reader according to the invention, and the telephone in which it is employed, have the following advantages. 
     Since the card is supported by the movable slide-in unit  42 , the card is moved away from the baseplate  40  with a long travel. Thus, when the slide-in unit  42  is in its disengaged position, it is easier to grip the card. 
     Since the conducting contacts  62  are placed opposite the recess  44 , they are accessible by a probe for testing the telephone when the slide-in unit  42  has not yet been fitted. Thus, the telephone can be easily tested during its manufacture. 
     On the other hand, after the slide-in unit  42  has been fitted, the masking blade  154  prevents the conducting contacts  62  from being accessible whatever the position of the slide-in unit  42 . Thus, the risks of the conducting contacts  62  becoming damaged or dirty are small. 
     When the card is in its use position, it is held in place against the base  50  by the tabs  72  to  78  and not by the slide-in unit  42 . Thus, since the tabs are made as one piece with the base  50 , the positioning is carried out correctly, independently of the precise position of the slide-in unit  42 . 
     Since the slide-in unit  42  opens into the housing  16  for accommodating the supply battery, the card cannot be removed while the mobile telephone is energized. 
     According to embodiments not shown, the slide-in unit may be fitted so as to be able to move in a transverse direction of the mobile phone or in the thickness direction of the latter. 
     In both cases, the slide-in unit  42  advantageously has a stop suitable for being held in place by the supply battery  16 A, so as to prevent the slide-in unit  42  from moving when the battery  16 A is installed in the housing  16 . 
     In general, in order to avoid any short circuit in the card, it is desirable for the card S to be unable to be removed or connected when the telephone is energized. 
     As a result, there are two constraints, the first being that it is impossible to bring the slide-in unit into the disengaged position with the battery fitted and the second being that it is impossible to fit the battery if the slide-in unit is not in the engaged position. 
     It should be noted that the first constraint does not mean that the battery holds the card S in place, since the slide-in unit stays all by itself in the engaged position without the battery being fitted. 
     Three other embodiments (not shown) have been envisaged: 
     in the first embodiment, the sliding direction D 1  of the slide-in unit is transverse with respect to the mobile telephone; 
     in the second embodiment, the direction D 1  is in the thickness of the telephone; and 
     in the third embodiment, the direction D 1  is longitudinal but, in contrast to the embodiment shown, the slide-in unit opens on the opposite side from the housing for the battery. 
     In these other embodiments, it should be noted that the cut-away corresponding to the cut-away  110  may be blocked off by a lateral extension of the front face corresponding to the front face  152  of the slide-in unit, instead of being blocked off by the battery as in the embodiment shown. 
     In these three other embodiments, the first constraint may be fulfilled in the direction D 1  by a stop on the slide-in unit which engages with a stud on the battery, the stud retaining the slide-in unit in the engaged position when the battery is fitted. In the embodiment shown, the first constraint is automatically fulfilled, since the slide-in unit  42  opens into the housing  16  for accommodating the battery—the slide-in unit is de facto locked in the engaged position when the battery is fitted since the front face  152  butts against the body of the battery. 
     In the two first embodiments, the second constraint may be fulfilled by a stud on the battery which butts against a rib on the slide-in unit, the rib being opposite the stud when the slide-in unit is not in the engaged position, whatever its precise position. In the third embodiment, such a solution is possible if the blade corresponding to the blade  154  slides in the housing of the battery so as to always have a part in the housing when the slide-in unit is not in the engaged position, whatever its precise position; consequently, a stud on the battery may butt against the blade when the slide-in unit is not in the engaged position. An alternative solution in the case of the third embodiment is for the battery to be fixed by a flexible tongue carried by the battery and engaged under the rim of the blade corresponding to  154 ; thus, when the slide-in unit is not in the engaged position, the rim is clear and the tongue can no longer bear against it, making it impossible to fit the battery. 
     In the embodiment shown, the second constraint is automatically fulfilled since the body of the battery butts against the bottom  150  of the slide-in unit when it is attempted to fit the battery while the slide-in unit is open. This is particularly advantageous as the user can clearly see why the battery cannot be fitted, whereas in the other three embodiments, the user may not understand why and get angry with the telephone. 
     Thus, in the light of the objective of fulfilling the two constraints mentioned above, the solution using the embodiment shown, in which the slide-in unit  42  opens onto the housing  16  for the battery, is the obvious and natural one. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.