Front plug system with lagging end contact arrangement

A front plug system with a lagging end contact arrangement. The front plug system for flat components includes a front element (1) with front plug connector (20) which can be plugged on by a swinging motion. If the front plug connector is plugged on until the point of engagement of a closing arrangement (27, 15) is reached, all operating contacts of the front plug systems arranged in receiving arrangements (3, 24) are already closed. An end contact arrangement (51, 52) arranged opposite the center of rotation of the front plug connector engages only when, after operating the closing arrangement, the front plug connector is plugged completely onto the front element and secured against being pulled off. With the end contact arrangement according to the invention the electrical signals of the operating contacts can be released simultaneously in particular across a control on the flat component.

BACKGROUND OF THE INVENTION 
The invention relates to a front plug system for a flat component, and more 
particularly to a front plug system including one front element and one 
front plug connector attachable to the front element with a swing motion. 
Many electrical circuits are fabricated in a compact form, possibly 
including integrated circuits, on a flat component. In these electrical 
circuits, signal groups, such as data busses, are routed toward the edge 
of the flat component. Signals of this type can then be displayed at the 
front of the flat component for purposes of circuit diagnostics, 
indicating, monitoring and measuring. The signals may also be tapPed at 
the front of the flat component and, if necessary, may be redirected 
across additional connections. In contrast, signal groups, which 
constantly need to be exchanged between circuit parts disturbed over 
several flat components, are preferentially redirected across stationary 
flat ribbon cable connections on the back sides of sub-racks. 
To tap and apply electrical signals on the front faces of components 
closely arranged in sub-racks parallel to each other, front systems are 
used consisting of front elements firmly connected with the particular 
component and a front plug connector which can be attached on the 
component. For example, in the European patent application having 
publication number 0 129 883 and application number 84 107 202.8 a front 
system is disclosed for components, which can be slid into sub-racks, and 
frame-like sub-racks to hold them. On the front strip of the particular 
flat component a socket for receiving a front plug is provided, with which 
given electrical signals can be diverted preferentially across a cable. 
However, such an arrangement has the disadvantage that a front plug 
sitting in the socket can not, or only with additional expense, be 
safeguarded against being unintentionally pulled off. Furthermore, in a 
plugging process, the contacts may make contact in an unpredictable or 
accidential sequence. Consequently, to avoid feedback effects on the 
circuit on the flat component it may become necessary before plugging 
takes place to briefly take this circuit completely out of operation. In 
the case of several components combined in a sub-rack, the entire 
arrangement may be taken out of operation by separating it from the power 
supply. 
The German patent having publication number 28 50 093 further discloses a 
holding arrangement for circuit boards. One electrical connecting element 
associated with the particular circuit board is swingable from a waiting 
position into an operating position, in which it engages on the circuit 
board. This arrangement also has the disadvantage that the contacts 
disposed on the front face of the circuit board in the transition from the 
waiting position to the operating position are not closed simultaneously. 
In a piece of equipment, to which these tapped signals are supplied for 
further processing, at least transitory error functions can occur. 
Furthermore, in this arrangement the electrical connecting element is also 
not secured against being unintentionally swung into the waiting position. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide for a front plug system including 
a front plug connector which can be plugged onto a front element such that 
when the front plug connector is plugged onto the front element, the 
connected signals can only be through-connected to the front plug 
connector after all operating contacts between the front element and front 
plug connector and have been connected. 
Accordingly, there is provided a front plug system for a flat component 
comprising a front element, defining a first end and a second end, 
including operating contacts; a front plug connector including operating 
contacts, which can be plugged onto the front element with a swinging 
motion; and a receiving arrangement extending from the first end to the 
second end of the front element including a closing arrangement and an end 
contact arrangement at the second end of the front element. The connector 
further includes a supporting arrangement at the first end of the front 
element for hooking the front plug connector over a pivot rest. The front 
element and front plug connector cooperate such that a point of engagement 
for the closing arrangement is reached when the front plug connector and 
the end contact arrangement only after the front plug connector is 
completely plugged onto the front element. 
The front plug system according to the invention has the special advantage 
that, due to the end contract arrangement trailing during the plug-on of 
the front plug connector all electrical signals for the operating contacts 
can be released nearly simultaneously through activation of a data latch. 
This is accomplished in part by means of a control arranged on the flat 
component and triggered by the end contact arrangement. Additionally, a 
reliable seating monitor for the front plug connector becomes possible, 
since the end contact arrangement engages only in connection with latching 
the front plug connector on the front element across the closing 
arrangement. Lastly, a further advantage of the front plug system 
according to the invention is that when the front plug connector is pulled 
out by the closing arrangement being unlatched, the end contract 
arrangement is disengaged before any operating contacts are interrupted. 
Consequently, sufficient time is available to carry out suitable safety 
measures. These safety measures may include triggering an alarm function 
and triggering data protection and terminating routines such that they can 
be completed before the actual interruption of the operating contacts 
occurs.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The front plug system according to the invention includes a front element 
1, into which according to the representation of FIG. 1, a front plug 
connector 20 is hooked. The connector 20 can be hooked into a supporting 
arrangement by way of a pivot rest 31 provided on the lower end 26, and 
can be rotatably mounted there. The supporting arrangement itself consists 
of a bolt 10, which is arranged at the lower end 8 of the front element 1, 
and functions simultaneously as a bearing for one of the lifting handles 
9. The front plug connector 20 can be plugged onto the front element 1 
with a swing motion around bolt 10 as a center of rotation. This 
establishes contact between the electrical operating contacts, which are 
arranged in a receiving arrangement extending from one end 7 to the other 
end 8 of the front element 1 and from one end 25 to the other end 26 of 
the front plug connector 20. In the preferred embodiment, shown in FIG. 1, 
the receiving arrangement 3 is built on the front face 2 of the front 
element 1 in the form of a slit and contains preferentially the contact 
blades of the operating contacts. This receiving slit 3 engages the 
preferentially bar-shaped receiving arrangement 24 of the front plug 
connector 20, which contains preferentially the contact clip of the 
operating contacts. The support of the parts of the operating contacts in 
the slit 3 and the bar-shaped receiving arrangement 24 has the special 
advantage that in a plug-in process through a swing motion the front plug 
connector 20 is guided due to the mutual engagement of the two 
arrangements 3 and 24. In this manner, accidental tilting and, hence, the 
danger of damaging the operating contacts is essentially eliminated. 
The front element 1 is connected mechanically through bores 5 with a flat 
component, which, for the sake of greater clarity, is now shown in FIG. 1. 
In this arrangement, contact pins 6, which are arranged on a long side of 
the front element 1, engage bores on the flat component and can be brought 
into contact there with conductor paths through a process such as 
soldering. In this manner, electrical signals of the circuit on the flat 
component can be brought "outside" and are applied on the parts of the 
operating contacts arranged in the receiving arrangement 3 of the front 
element 1. After the front pug connector is plugged in, these electrical 
signals can be redirected across a cable connected in its interior of the 
back side of the operating contacts. This can be led outside 
preferentially across a shaft 32 at the lower end 26 of the front plug 
connector 20. 
According to the preferred embodiment, a last operating contact 52, 
distinct from the other operating contacts, is provided at the end 25 of 
the receiving arrangement 24 of the front plug connector 20. This 
operating contact 52 is preferentially set back relative to the remaining 
operating contacts, and is represented in the embodiment of FIG. 1 by a 
step at the upper end 25 of the bar-shaped receiving arrangement 24 of the 
front plug connector. The contact 52 is associated with, and engageable 
with, a contact 51 provided at the end 7 of the front element 1. The 
portion of this operating contact arranged opposite in the slit-shaped 
receiving shaft 3 of the front element 1 can be set back relative to the 
remaining parts. 
An important feature of the preferred embodiment of the invention is that 
the end contact arrangement 51, 52 engages only upon operation of a 
closing arrangement available at the front plug system. Accordingly, the 
front plug connector can only be plugged on the front element by way of 
the swing motion until the point of engagement of the closing arrangement 
is reached. The closing arrangement is designed according to the invention 
such that in this state the receiving arrangements of front element and 
front plug connector have already engaged each other and all operating 
contacts have been closed with certainty. The completely plugged on state 
is only achieved through an additional operation of the closing 
arrangement. This overcomes the last closing path, engages the end contact 
arrangement, and simultaneously latches the front plug connector against 
being pulled off. 
In the preferred embodiment of FIG. 1 the closing arrangement is arranged 
together with the end contact arrangement 51, 52 at the other ends 7, 25 
of the front plug system. The closing arrangement includes at least one 
screw 27 guided through the front plug connector 20 and at least one inner 
thread supported opposite in the front element 1. A screw 27 shown in FIG. 
1 is preferentially supported in the front plug connector by way of a 
holding means 30 and a screw shaft 29 with enlarged outer diameter. 
Plugging the front plug connector is initially only possible until the 
screw threads 28 stop at the inlet of the inner threads 15. The operating 
contacts of the receiving arrangements 3 and 24 are in this state already 
closed. Since the set-back arrangement of the operating contact 52 serves 
as an end contact arrangement 51, 52 at the upper ends 7, 25 of the front 
plug system, this is closed according to the embodiment only after the 
front plug connector 20 is completely pulled against the front element 1 
by screwing the screw 27 into the inner threads 15. Through suitable 
choice of the length of the screwing threads 28, the delay time can be set 
in order to trigger safety measures between interruption of the end 
contact arrangement 51, 52 and the interruption of one of the operating 
contacts and, if possible, also be able to complete them. This delay time 
is advantageous for purposes of unlatching the closing arrangement. 
Since the front plug connector is preferentially an aid for conducting 
electrical signals of the operating contacts into a cable, it is 
advantageous to built the front plug connector in two parts. This is 
already shown in the embodiment of FIG. 1. The front plug connector shown 
there consists of a basic body 21 and a detachable cover 22, which can be 
stopped preferentially with a clamping projection 23. FIG. 2 shows a 
possible internal structure of a front plug connector with the cover taken 
off. On the inner side of the basic body 21 opposing the receiving 
arrangement 24 for this purpose, one strip terminal 37 and one screwing 
strip 38 are arranged for tightening the individual binding posts. In this 
manner, the wires of a cable inserted by way of shaft 36, at the lower end 
26 of the front plug connector can be connected to the part of the 
operating contacts in the receiving arrangement 24. Lastly, the cable can 
be fastened on the basic body 21 preferentially with cable binders, which 
are led through lead-throughs 36. 
In another embodiment, it is possible to use the front plug connector for 
as a programming plug. At this end, shortcircuit connections can belayed 
between individual binding posts of the operating contacts. The front plug 
system according to the invention permits a particularly simple correction 
of the available connections through temporary unlatching of the closing 
arrangement when the end contact arrangement is disengaged. To unlatch, it 
is not necessary to remove the front plug connector. 
Another embodiment of the end contact arrangement according to the 
invention is shown in FIG. 3. The front plug system contains additional 
indicator elements 12, which are placed in an additional receiving 
arrangement 11. These elements 12 are arranged parallel to the receiving 
arrangement 3 for the operating contacts. Light emitting diodes are 
particularly suitable as indicator elements 12. These diodes are inserted 
on the inner side of a trough strip 4 arranged on one long side of the 
front element. The leads of the indicator elements are led outside by 
means of a row of bores 13 arranged on a long edge of the trough strip 4 
and can be connected there with conductor paths of the flat components. 
The number of indicator elements 12 corresponds preferentially to the 
number of operating contacts in the receiving arrangements 3 and 24, such 
that the active states of the signals of the electrical circuit of the 
flat component applied to the operating contacts can be indicated 
optically. 
In the embodiment of FIG. 3, the front plug connector, in its attached 
state, projects beyond the indicator elements. In particular, with 
additional bores opposing the particular indicator elements in the front 
plug connector, the indicator elements can be made visible. It is 
presently preferred to set in the end contact arrangement instead of the 
indicator elements. All operating contacts, consequently, are available 
for signal transmission. Furthermore, no mechanical changes, for the 
receiving arrangement and the position of the operating contacts are 
required. 
The indicator element at the upper ends 7, 25 of the front plug system is 
particularly advantageously replaced by the end contact arrangement. 
Corresponding to the representation of FIG. 3, a part of the end contact 
arrangement is used instead of the indicator element 14 in the front 
element. Opposite, an additional part of the end contact arrangement is 
shown on the front plug connector labeled 34. 
FIG. 4 shows in a view corresponding to FIG. 2, wherein the front plug 
connector according to the design of FIG. 3 has the cover 22 removed. 
Here, the bores 33 in the basic body 21 for visualization of the 
individual indicator elements can be recognized. 
A particularly advantageous design for an end contact arrangement suitable 
in place of one of the indicator elements in FIG. 3 is shown in FIGS. 5 to 
8. This consists of a contact counter piece 14 and a contact pin 39. As 
shown in FIGS. 5 and 6, the contact counter piece is adapted to the outer 
shape of one of the indicator elements. In the illustrated embodiment, the 
contact counter piece 14 has nearly the shape of a light emitting diode 
41. Further, leads 46 and 47 are led in the same way as leads 43 and 44 of 
the light emitting diode 41. Thus, without great expense, it is possible 
to replace one of the indicator element with such contact counter piece. 
The detail representation of FIGS. 5 and 6 show a cutout of a possible 
structure of the inner side of the additional receiving arrangement 11. In 
particular, over troughs 48 and webs 49 arranged between them, the inner 
side is adapted to the shape of the indicator elements to be received. The 
contact counter piece 14 and their leads 43, 44, 46 and 47 are received in 
such a way that all inserted elements are safeguarded against a 
displacement such as falling out. 
The contact counter piece 14 includes an insulating body 45 on the contact 
surface 50 of from which the electrical leads 46, 47 are led. The form of 
the piece 14 corresponds to the shape of a diode carrier 42 with inset 
diode glass body 41. In the state of the front plug connector, in which 
the latter is completely plugged on the front element, a state which can 
be achieved by operating the closing element, these leads are 
shortcircuited through a metal contact pin resting on the contact surface 
50. In FIG. 7 an advantageous design of such cylindrical contact pin 39 is 
shown. Into it, a contact piece 34 is set braced by a spring 40, with 
which the actual contact is established. 
The contact pin can have an outer shape such that it can be supported in 
the bore 35 opposing the contact piece. The bore can function to make 
visible the indicator element. FIG. 8 shows such arrangement. All 
remaining bores 33, for making the indicator elements at the end of the 
particular bore more readily visible, can be filled advantageously with a 
lightwave guide consisting of a glass-like synthetic material.