Reader for chip cards

Read apparatus for chip cards with a housing (1) in which a contact support (3), with a number of contact pairs (4,4a) that corresponds to the number of read tracks and that can be connected by a limit switch (12), is held and a slide (6), operated by the chip card and acting on the contacts (4,4a) or the contact support (3), is guided such that, upon moving the card close to its end position, the contacts (4,4a) are pressed, on the one hand, firmly onto the contact field of the chip by means of the slide (6) and, on the other hand, the limit switch (12) is closed, wherein the limit switch (12) is arranged on the side next to the contact support (3) in the area between the card insertion slot and the slide (6), and wherein the slide (6) is equipped with a bar (13) having a tab (14) which reaches behind the contacts (12a, 12b) of the limit switch on the side of the card insertion slot with a spacing such that the limit switch (12) is closed by the entrainment of the slide (6) brought about by the approach of the card to its end position.

BACKGROUND OF THE INVENTION 
The invention proceeds from a read apparatus for chip cards according to 
the preamble of claim 1. In known read apparatuses of this type, the limit 
switch closing the circuit between the contacts and the read tracks is in 
the vicinity of the contact support, as a rule, directly on top of the 
contact support, such that, upon insertion into the card slot, the chip 
card entrains one of the contacts and presses it against the opposing 
contact immediately before reaching its final position. Functionally, the 
arrangement has largely proven itself, but nonetheless the position of the 
limit switch in the end area of the chip card is considered 
disadvantageous in that, in case of frequent actuation, that is, frequent 
insertion end pulling out of the card, the appearance of worn-off material 
from the card is inevitable, accumulating in particular on the opposing 
contact and leading to an insulation effect all the way to complete 
interruption of functioning. 
The present invention is based on the problem of creating a read apparatus 
for chip cards in which the contamination of the contact by worn-off 
material or by the card in some other manner is largely avoided. 
SUMMARY OF THE INVENTION 
This problem is solved by a read apparatus with the characteristics 
reproduced in claim. 
A read apparatus for chip cards is created by the invention in which the 
limit switch lies inside a closed chamber which is largely hermetically 
enclosed and thus is practically completely protected against the ingress 
of dust. Differing from the known limit switch arrangements, moreover, a 
pivoting of the two contact blades takes place during the entrainment 
after landing of the entrained contact on the opposing contact, due to the 
play that must be maintained, and thus, because of their differing pivot 
radii, a displacement of the contact point takes place with a frictional 
effect, whereby a continual self-cleaning of the contact field is brought 
about.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The read apparatus for chip card consists of a housing 1 that is closed off 
by means of a lid, not shown, and into which the chip card is pushed for 
operation under lateral guidance by means of the leaf springs 2 in the 
direction designated by the arrow. Inside the housing, a contact support 
3, with a number of contact pairs 4,4a corresponding to the number of 
contacting fields, is held. Also provided is a slide 6 running on guides 
5, which in the case of this example is pressed upon by a spring 7 in the 
direction towards the insertion slot and has a stop 8, against which the 
chip card makes contact with its front end when approaching its final 
(read) position. Inclined ramps 9 are also arranged on the slide and 
interact with pins 10 arranged on the contact support 3 such that, upon 
approach of the card to its final position, the slide 6 is entrained and 
in the process the inclined ramps 9 sliding up onto the pins 10 of the 
contact support 3 bring about a pivoting of the contact support 3 and thus 
the contact pairs 4, 4a, such that they are pressed firmly onto the chip 
arranged on the card. 
The limit switch 12 is arranged on the side next to the contact support 3 
in the area between the card insertion slot and the slide 6, the slide 6 
being equipped by means of a bar 13 (FIG. 1) with a tab 14 (FIG. 2) which, 
upon displacement of the slide 6 under the force of the inserted card 
first strikes the contact 12a and then entrains it on its additional 
travel to contact 12b, whereby the electrically conductive connection is 
produced. It can be recognized from the drawing that the switch lies in a 
chamber which is formed by the housing 1 and the housing lid, not shown, 
and is largely hermetically enclosed and thus practically completely 
protected against the ingress of dust. It is also clearly recognizable 
that the two contracts 12a, 12b, because of the differing positions of 
their pivot circles after the placement of the contact 12a on the contact 
12b, slide against one another a with a frictional displacement of the 
contact point, whereby a continual self-cleaning of the contact field of 
the switch is brought about.