CLAVIER

KEYBOARD ARRANGEMENT

Abrégé anglais

Abstract of disclosure
A keyboard arrangement wherein key elements (22) are mounted on a printed
circuit board (23) requires a good support of said board to withstand the
operation forces. This support is achieved by a foamed plastic molded body
(27) filling the entire remaining space below a cover (21). The evaluation
circuitry (26) is arranged on a separate printed circuit board (25) which is
interconnected with the printed circuit board carrying the key elements via a
connector (24). This results in a small keyboard arrangement, in a foamed
plastic molded body of simple design and in an easy replacement of the
evaluation circuitry in case of failure.
(Fig. 2)

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A keyboard arrangement comprising, in combination: a
foamed plastic body; a generally flat printed circuit board
mounted on one side of said foamed plastic body and having a
free end portion extending away from and generally parallel to
said side of said foamed plastic body and said end portion
having printed electrical circuits thereon for connection to
an external circuit; a plurality of key elements mounted on
said printed circuit board and being respectively electronically
connected to said circuits; a utilization device removably
attached to and electrically connected to said free end por-
tion of said printed circuit board; and, a cover member mounted
over said printed circuit board and enclosing said foamed
plastic body and said utilization device.

Description

5;3~
--1--
The present invention relates to a keyboard arrange--
mint wherein keys are mounted on a printed circuit board.
For keyboard arrangements of this kind it is compel-
story that the printed circuit board carrying the keys has to be
supported or that the key operation forces are taken over by
another element. For this reason known keyboard arrangements
of this kind were provided ego with blind plates in front of
or behind the printed circuit board. Blind plates in front
of the printed circuit board are usually metallic plates pro-
lo voided with a corresponding cut-out for each of the keys into
which the keys could be inserted and are fixed by resilient
notches as notches 254 of the key element known from Swiss
Patent No 596 460 whereas its electrical terminals may be
soldered into a printed circuit board arranged behind the key
elements. It is obvious that this blind plate is relatively
expensive due to the large number of cut-outs needed. Metallic
blind plates behind the printed circuit board have to be
insulated against the latter whereas blind plates of insulate
in material have to be of sufficient thickness or have to be
I provided with ribs resulting in heavy or bulky elements.
It is therefore an object of the present invention
to provide a keyboard arrangement having a good support for
the printed circuit board without the drawbacks of the known
supports.
According to the present invention, there is provided
a keyboard arrangement comprising, in combination: a foamed
plastic body; a generally flat printed circuit board mounted
on one side of said foamed plastic body and having a free end
portion extending away from and generally parallel to said side
of said foamed plastic body and said end portion having print
ted electrical circuits thereon for connection to an external
,
~,~

-lo-
circuit; a plurality of key elements mounted on said printed
circuit board and being respectively electrically connected to
said circuits, a utilization device removably attached to and
electrically connected to said free end portion of said print
ted circuit board; and r a cover member mounted over said
printed circuit board and enclosing said foamed plastic body
and said utilization device.
The invention will be best understood from the follow-
in description of embodiments taken in conjunction with the
accompanying drawing, in which:
Figure 1 shows the plan view of a keyboard arrangement
including two keyboards;
Figure 2 shows a sectional view of the keyboard
arrangement according to Figure l; and
Figure 3 shows the plan view of a keyboard arrange-
mint including three keyboards sloped against each other.
Figure 1 shows the plan view of a keyboard arrangement
including two keyboards and Figure 2 shows a sectional view of
this arrangement. The keyboard arrangement according to
Figure 1 includes a cover 11 having openings for an alpha-
numeric keyboard 12 and for a keyboard 13 including e.g. lung-
lion keys. From the sectional view of Figure 2 it can be seen
that the cover 21 rises with a small tilt angle from a bearing
surface - not shown -, continues to rise over the keyboard
after a small offset, is bent twice after the keyboard and
goes then

elf I
- 2 - Frey 10-5-2-2
back to the bearing surface. On a printed circuit board 23 arranged below the
cover 21 there are mounted key elements 22. To the upper end of the printed
circuit board 23 there is connected via a connector 24 a further printed
circuit board 25 carrying the elements 26 of an evaluation circuitry. Pro-
fireball the connector 24 is soldered to the printed circuit board 25 and
receives the printed conductors of the printed circuit board 23.
The printed circuit board 23 carrying the key elements 22 is supported by a
foamed plastic molded body 27 filling the entire space remaining below the
cover 21 and being fixed to the latter. The use of this foamed plastic molded
body results in a substantial saving of piece parts and consequently of
weight. Besides an easier displacement of the keyboard arrangement which is
desired for so-called manager keyboards, i.e. keyboards which are used
occasionally only for data outputs and then put away, the saving so weight
leads to lighter structures which nevertheless are able to stand fall tests
due to the decrease of impingement energy.
A favorable application of the principle to support the keyboard by a foamed
plastic molded body results for the keyboard arrangement shown in Fig. 3 which
corresponds roughly to the keyboard arrangement described in the European Pat.
Apply. No. 81810506.6, published as EN 0055220 (Frey et at 8-2-2) wherein key-
boars 31-33 are sloped against each other and have different tilt angles to a
bearing surface in order to achieve an ergonomically ameliorated body carriage
of the operator wherein his hands have to be flexed and turned by a smaller
amount than with an ordinary one-part or plane keyboard arrangement. In the
case of the above mentioned keyboard arrangement it might be advantageous to
provide a single foamed plastic molded body with cavities for each keyboard
into which the individual keyboards each provided with a rim can be inserted.
The subdivision of the electric circuitry onto two printed circuit boards 23
and 25 interconnected by the connector 24 has the advantage that in the case
of a keyboard with transformers for the relatively large printed circuit board
containing the primary and secondary windings of the key transformers and
carrying the key elements there can be used an inexpensive double-faced
printed circuit board having no connections between the two faces, i.e. no
through-platings, and requiring no soldering operation. The absence of sol-
during points on this printed circuit board allows to have it lain directly on
the foamed plastic molded body possibly with an insulating foil in between.
The evaluation circuitry needs through-platings~ but it can be placed on the
relatively small printed circuit board 25. Although an additional connector is
needed for the interconnection of the two printed circuit boards the three
elements together are less expensive than a single printed circuit board of a
larger size having through-platings.

5~3~
3 - Frey 10-5-2-2
In addition this subdivision allows to have a keyboard arrangement as small
as it is possible with the desired grid of keys since the evaluation circuitry
does not need additional space in the depth or width of the keyboard
arrangement, but is arranged where the space is available anyway due to the
ergonomically needed slope of the keyboard. The subdivision results also in a
simpler design of the foamed plastic molded body and allows an easy exchange
of the evaluation circuitry in case of failure.