Abstract:
The invention concerns a push-push mechanism, particularly for a card reader with a control cam and a control pin, which engages with the control cam and is operatively connected with a slider, during which the transition of the control pin from the initial position to the reading position takes place by a first push and the transition from the reading position back into the initial position by a second push on the control pin and thus the slider, whereby the control pin is flexibly deflected during its actuation along the control cam.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of International Patent Application no. PCT/EP2008/007554, filed Sep. 12, 2008, and German Patent No. 10 2007 044 170, filed Sep. 15, 2007, the entire disclosures of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a push-push mechanism and thus the design of a control cam for a push-push mechanism. The invention thus concerns a push-push mechanism and particularly a control cam for a push-push mechanism, according to preamble in patent claim  1 . In particular the invention concerns such push-push control cams that are suitable for application with a card reader, that includes a push-push mechanism. “Card” refers to chip-cards, smart cards and SIM cards, as well as other typical cards that are utilised in technology. Card reader refers to a card contacting device for application with a card. In the sense of the present invention, under push-push mechanism or push-push control cam respectively a device is understood which is suitable for inserting cards into a card reader with an initial push and with a second push on the card, this can be removed again from the card reader. In general the invention refers to a push mechanism, in which a control pin guided by the control cam is provided, which according to the present invention is mounted form-fittingly in a slider. Connectors of this kind with a push-push mechanism are already known in the state of the art. Thus U.S. Pat. No. 6,839,431 demonstrates a card contacting device with a push-push mechanism and a heart-shaped control cam. The mechanism shown there is composed of a variety of components. A slider which can be actuated by the card, works together via a control element with a control cam located in the card reader, in other words a heart-shaped control cam shown here. Furthermore a spring is provided which is mounted on the slider at its actuation end. The push-push mechanism shown here has on the one hand the disadvantage that many components are needed that in particular work together in a complicated way and if they in an inexact position, the function of the card reader will be impaired. The height of the whole card reader due a push mechanism of this type is another disadvantage. The required control cam or heart cam includes several stepwise mounted control regions, along which the control pin slides, depending on the actuation state. The various steps thus enable the control pin to be forcibly guided along the cam following one direction, as well as attaining specific intermediate states. However the number of states and intermediate states as well as the reading state and the opening state only possible with many steps within the control cam. 
     SUMMARY OF THE INVENTION 
     The basis of present invention is thus to so improve a generic push-push mechanism for a card contacting device that the total height of the card contacting device can be significantly minimised, at the same time as having a high degree of operational reliability. Another objective of the present invention is to reduce the number of components of a push-push mechanism according to the present invention. This task is achieved by the characteristics of claim  1 . In the sub-claims preferred designs of the invention are indicated. 
     According to the present invention a push-push mechanism is so designed with a control cam, that the control cam has a spring-loaded control pin which is forcibly guided and tensioned along the wall so that thereby the number of steps in the control cam can be reduced. 
     According to the present invention the control cam is designed as a two-step control cam, so that the control pin is pre-tensioned and can only follow a pre-defined path and thus is forcibly guided. However, with the number of steps the height increases due to its design. In the reading position the control pin is in a rest position which is formed by a V-shaped wall funnel. Since in the deflected state the control pin, due to its spring tension, tries to spring back against its deflection, it is possible to save steps in the area of the rest position. The return of the control pin back to the initial position in this respect does not have to take place with a compulsory step. In order to thus reduce the height of the control cam and the control pin, the control pin length can be matched with the only present step-height, so that on the one hand the total height are reduced by reducing the control pin length while at the same time reducing the number of steps. 
     According to the present invention the control pin is form-fittingly connected to the slider, which when used in a push-push card reader, can be actuated by inserting a card. According to the present invention due to its mounting the control pin has a stop upwards, so that due its pre-tension is always tries to return to its initial position against this pre-tension. 
     According to the present invention the slider is designed as one piece with the control pin and preferably manufactured as a bent stamped metal part. The control pin thus already obtains its pre-tension. 
     According to the present invention the slider features a card stop, over which the slider and thus the control pin can be actuated. According to the present invention, by actuation with a card after insertion of the card in the card contacting device, the slider is actuated via the card stop. By actuating the slider the control pin, which is form-fittingly connected to the slider, is forced along the wall and transported into a first latching and reading position. According to the present invention, the latching and reading position is thereby attained, in that the control pin at the end of the actuation path with the card, which moves the slider and thus the control pin into such a position, can spring into the said latching and reading position against its pre-tension. In this position, in other word the reading position of the card with respect to the card contacting device, a stable latching position is attained. In order to remove the card again from the card-receiver of the card contacting device and thus from the reading position, the card is actuated with a further push over the slider card stop against a spring with which the slider is connected. Thus the slider is pushed a bit further into the card-receiving compartment and the control pin, which is mounted on this, can thus leave its latching position, so that it strives to deflect further against its tension in order to lie flat against a second guide wall. If now the actuator lets go of the card after the second push, as a result of the spring tension acting on the spring slider, the slider complete with the card can be transported out of the card-receiving shaft and the control pin slides along the second guide wall back to its initial position. As a result the control pin covers a difference in height and surmounts a step at the end of the actuation process in order to return to its initial position. Preferably at the first push, and thereby with the insertion of the card, the control pin is so moved along the guide walls out of its rest position, that the pre-tension with increasing coverage of the actuation path increases and at the end of the actuation path a maximum pre-tension has been built up. If pressure is maintained on the push, thus at the end of the first push, as a result of the actuation of the card the control pin slips into the said latching position, in which the card is held in its reading position and the slider is thus tensioned against a coil spring. 
     Further advantages, objectives and details of the invention are shown in the description of design examples by means of the drawings; in the drawing is shown: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  a schematic top view, skew from above of a push-push mechanism; 
         FIG. 2  a detailed view in accordance with  FIG. 1  including the control cam; 
         FIG. 3  a schematic top view of a push-push mechanism, in accordance with  FIG. 1  in the initial position; 
         FIG. 4  a schematic top view, skew from above, of a push-push mechanism, in accordance with  FIG. 1 , but with actuated slider in a position shortly before the reading position; 
         FIG. 5  a schematic top view of a push-push mechanism, in accordance with  FIG. 4 ; 
         FIG. 6  a schematic top view, skew from above, of a push-push mechanism after a further push, however in particular the control pin has sprung back into a non-deflected position; 
         FIG. 7  a top view in accordance with  FIG. 6   
     
    
    
     In  FIGS. 1 to 8  a section of card reader is shown in each case, which preferably represents a chip card reader, a smart card connector or a SIM card reader, or a reader in general and the present invention part of the push-push mechanism of such a card reader is shown in various positions. In  FIG. 1  such a detail is shown, namely a push-push mechanism  1  of a card reader according to the present invention. Not shown is the left area of the card-receiving compartment connected to the detail and the cover typically provided for such a card reader, which together with the base  2  of the card reader forms the card-receiving compartment. Between the base  2  and the non-depicted cover there is a card-receiving compartment  3 . In  FIG. 1  this card-receiving compartment is only shown to some extent in the partial view. Part of the base  2  of the card reader is also shown, on which a card is lying ready to be inserted. A card is so far inserted at the insertion side end  4  of a card reader according to the present invention, until the insertion side end of the card meets the stop  6  of the slider  5 . The push-push mechanism  1  perspectively shown in  FIG. 1  essentially consists of a slider  5 , with a card stop  6 , and a spring  7 , which pre-tensions the slider  5  in the position shown in  FIG. 1  and furthermore including a control pin  8 , which is fixed as one piece to the slider  5 . 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following first of all the slider  5  and the control pin  8  will be described. 
     In  FIG. 3  the slider  5  is in an initial position A and has a longitudinal arm  9 , on which at both ends respectively a projecting cross arm  6 ,  16  is fixed. The first cross arm  6 , which is in the card-receiving compartment and which projects into it, acts as the card stop  6 . If a card is inserted into the card-receiving compartment  3 , after insertion, it reaches the card stop  6  with the insertion side end, with which the slider  5  can be actuated. The second cross arm  16 , which is fixed onto the insertion side end of the slider  5 , projects in the opposite direction towards the side outer wall  10 . 
     The cross arm  16  lies against the insertion side outer wall  11  with its front face, due to the pre-tension of the spring  7 , which holds the slider  5  in this position. As can be clearly seen from  FIG. 3 , the spring-loaded control pin  8  is in its slack initial position and runs parallel to the longitudinal arm  9  of the slider  5 . The slider  5  with the single-piece designed control pin  8  is here shown as a bent stamped part. The slider  5  in its cross-section has a more-or-less L-form and is bent along its radius  12  to the aforementioned L-form, so that the slider  5  has a base part  13 , with which it can slide along the base  2  of the card reader. The base part  13  runs from one of the cross arms  6  over the longitudinal arm  9  to the second cross arm  16  along the whole slider  5  and is connected in between by means of a connecting element  14  to the control pin  8 . The connecting element  14  is a partial elongation of the base part  13 . On the front side end of the connecting element  14  the control pin  8  has a spring-loaded design. As evident in  FIG. 1 , the control pin  8  is fitted out with a guide pin  15  at its free end, which projects downwards away from the longitudinally aligned control pin  8  and with its end is seated on the control cam  20 . In the initial position A of the slider  5  shown in  FIG. 1  to  FIG. 3 , the control pin  8 , which is fixed to this, is in its rest position and thus free of tension. The control pin  15  is so designed that it is guided along the control cam  20  when the slider  5  is actuated with the card. The control pin  8  thus has a free end  17  and a fixed end  18 , which is flexibly hinged to the connecting element  14 . The total height of the reader is thus given by the height of the control cam and the total height of the control pin, and particularly the length of the guide pin  15 . 
     The Control Cam  20   
     The total height of the reader is defined by the geometric dimensions of the guide pin with the control pin, and the height or the total height of the control cam over which the control pin  8  slides with the end of its guide pin. Since the control cam  20  with its surface  21  travels up a slope with regard to the card sliding surface, which is shown as a parallel surface to the base  2  of the card reader, the highest point of the control cam  20  with regard to the base of the card reader is thus defined as the sum of the total height of the control pin  8  with the guide pin  15 , which at the highest point lies with its end on the control cam  20 . According to the present invention is shown as in  FIG. 2 , only with a step  26  placed in the control cam  20 . The control cam  20  is a self-contained guide slot restricted by guide walls. The function of the control cam is to forcibly guide the control pin  8  with its guide pin  15  after actuation of the slider  5 , namely along the given direction of movement in a clockwise direction, according to the sequence of  FIGS. 1 ,  4  to  6 . 
     The control cam is surrounded along its longitudinal alignment at any one time on both sides by the guide walls  22 ,  23 . The guide wall  22  serves as a sliding surface for the guide pin  15 , along which the control pin with its guide pin  15  can slide when the slider  5  is actuated. The control cam runs further to a recess  24 , which is embossed in a V-form in the guide wall  22 . The purpose of this recess  24  is the securing arrangement of the guide pin  15  of the control pin  8 . At the end of the control cam section  25  the control cam end at a step  26 , which then leads back to the initial position of the control cam  20 . The control cam section  25  is restricted on its left side by the chamber wall  27  and on its right side by the surrounding guide wall  22  already mentioned previously. The total height of the reader and thus the height of the chamber wall  27  is determined by the height of the control cam  20  with reference to the underside of the base  2 , which is the sum of the height of the control pin  8  with its guide pin  15 . 
     If the slider  5  is actuated with a card inserted into the opening slit of the card reader from the initial position A, as shown in  FIG. 1  and  FIG. 3 , to the position as shown in  FIG. 4 , then the control pin  8  is guided along the guide wall  22  and along the control cam  20  until a maximum deflected position  28 . As can be seen in  FIG. 5 , in this position the slider  5  has slid into the card-receiving compartment and the control pin  8  is flexibly deflected and pre-tensioned compared to its initial position. If the slider  5  is further actuated in the direction mentioned the guide pin  15  slides around the tip of the guide wall  22  and immerges in the recess  24 . If the actuation pressure is now released on the card, the spring  7  tries to move the slide  8  against the actuation direction back into its initial position, which however is prevented, since the guide pin  15  of the control pin  8  engages and is retained in the recess  24  and the slider  5  is thus prevented from sliding back. Through this movement the purpose of the first push is therefore to move the card into a stable reading position, in which the control pin  8  is held in its latching position in the recess  24 . According to the present invention as is shown in  FIG. 5  the control pin  8  is flexibly deflected, so that when a the slider is further actuated as just described, it forcibly endeavours to return to its initial position, and thus moves in the direction of the chamber wall  27 . In this way it slides automatically into the stable latching position and thus into the recess  24 . 
     If again actuated, in other words there is another push on the card to remove this from the stable reading position, the control pin  24 , which is still deflected in a spring-loaded and pre-tensioned state compared to its rest position, tries to spring back out of the recess  24  further in the direction of the chamber wall  27 , as shown in  FIG. 6  and  FIG. 7 . 
     In this position the control pin  8  is aligned parallel to the slider  5  and to the chamber wall  27  and can now slide along the control cam section  25  when the pressure is released. Since the control pin  8  can now move freely along the control cam, the spring  7  causes the slider  5  to be moved back into its starting position. Shortly before reaching the starting position A the control pin  8  reaches the step  26  with its guide pin  15 . In this position the maximum height of the control cam and thus the minimum height of the card reader is defined. Since the control cam  20  is only designed with one single step  26 , the total height of the reader is only influenced by the height of the control pin and this step. The control cam thus has a flat section, starting from the starting point A until the control cam section  26 , which rises obliquely up to step  26 , and shortly before reaching step  26  defines another flat, essentially triangularly designed control cam section  29 . As can be seen in  FIG. 4 , the slider  5  slides into a guide slot  30  with a non-depicted guide pin. In the design here shown the slider  5  is pressed against the chamber wall  27  and slides along this, without having any concrete guiding devices, since due to the spring tension of the control pin  8 , the slider  5  is also pressed continuously against the chamber wall  27 , as soon as the slider is deflected from its initial position A and actuated. Thus the forcible guiding of the slider  5  parallel to the actuation direction is also achieved with the control pin  8 , without requiring any further construction elements. Besides being a contact surface for the spring  7 , the cross arm  16  forms a guide pin for the guide slot  30 . The push-push movement described previously and thus the guiding of the control pin along the control cam can be repeated as often as desired and with the first push causes, so to speak, a stable reading position to be attained, and with a second push the removal of the card from the reading position into the removal position, corresponding to initial position A, is achieved. 
     LIST OF REFERENCE CHARACTERS 
     Push-Push Mechanism, in Particular for Card Readers 
     
         
           1  push-push mechanism 
           2  base 
           3  card-receiving compartment 
           4  card insertion side 
           5  slider 
           6  card stop/cross arm 
           7  spring 
           8  control pin 
           9  longitudinal arm 
           10  side outer wall 
           11  insertion side outer wall 
           12  radius 
           13  base part 
           14  connecting element 
           15  guide pin 
           16  cross arm 
           17  free end of the control pin 
           18  fixed end of the control pin 
           20  control cam 
           21  surface 
           22 ,  23  guide walls 
           24  recess 
           25  control cam section 
           25   a  start of the ascending control cam section 
           25   b  end of the ascending control cam section 
           26  step 
           27  chamber wall 
           28  deflection position 
           29  flat control cam section 
           30  guide slot