Keyboard protected against vandalism and spill

The invention provides means to protect a widely used keyboard such as the IBM XT PC and PS/2 keyboard against vandalism and spill if such a keyboard is used in exposed situations, e.g. in self-service application/transaction machines which are publically accessible and unattended. On the base plate or housing 1 respectively of the keyboard 12 a grid plate 8 is fixed. This grid plate has openings 10 arranged in the pattern of the keys and in such a size that the cone-like keys 11 cannot be removed toward the top. The grid plate may be fixed directly to the keyboard housing or by means of a supporting frame 4 which is secured to the housing. In both cases grid plate or supporting frame respectively include a rim 5 to form a shallow trough 21 with the keyboard housing. A gasket 2 is provided between grid plate or supporting frame respectively and the keyboard housing. A drain 3 is provided in the rim to give controlled outflow. Thus spilled liquid cannot intrude over the edges into the interior of the keyboard housing and by the grid plate the removal of keys toward the top is not possible.

DESCRIPTION 
The invention relates to a keyboard having a housing comprising in rows and 
columns apertures for keys, said housing having stem-like chimneys 
protruding from a base plate and forming said apertures, said chimneys 
being open to the top of the keyboard and being adapted for carrying keys, 
each of said keys having an umbrella or cone-like cap with a base wider 
than the top and wider than the opening of said chimney. 
The PCT Application WO 81/00762 (PCT/US 80/00940) describes a photo-optical 
keyboard having an improved keyboard housing and keys for the purpose of 
confining debris and liquid spills on the keyboard. The keyboard housing 
has a matrix of rows and columns of apertures for keys. The housing has 
recesses open to the top of the keyboard between the apertures. Further, 
there are structural supports between the apertures which separate the 
recesses and cause the recesses to be reservoirs. Multiple keys are 
positioned in the keyboard housing apertures. Each of the cone-like keys 
has an umbrella cap with lower edges extending over the recesses. Liquid 
or debris spilled on the umbrella cap will fall into recesses to be 
contained. This known keyboard construction does not give the possibility 
to the contained liquid to leave the area between the stem-like key 
openings. That means that liquid and debris spilling are confined in the 
recesses and can only be removed by cumbersome means. The very serious 
problem of avoiding the possibility to remove the keys or the key caps to 
the top from the keyboard is not at all addressed by this citation. 
Another example of a keyboard having a housing from which stem-like 
chimneys protrude in which keys are confined and guided, is described in 
the German Gebrauschsmuster G 87 00 721.5. The cone-like formed hat or cap 
of the key has lower edges that are wider than the top edges, and the 
lower edges are also wider than the opening of the keyboard housing or 
chimneys respectively. The cap overlaps the chimney thus avoiding that 
spill can intrude into the openings of the keyboard housing. Liquid 
spilled over such a keyboard housing might not intrude into the chimneys 
directly. Anyhow it is possible that liquid intrudes into the housing at 
the edges of the keyboard housing when running across the plate of the 
keyboard housing. So also this construction does not avoid completely the 
intruding of spill liquid into the housing. Furthermore it does not at all 
address the avoidance of the possibility to remove cone-like caps toward 
the top of the keyboard. 
Also in the German Patent DE 33 25 409 C2 there is described a keyboard 
with discrete keys having a cone-like cap or hat form respectively. The 
keys are guided in chimneys protruding from the keyboard housing. Those 
chimneys forming on the inside apertures in which the stems of the keys 
are guided to switch underlying switch means if they are pressed down. 
Again, the caps or key buttons have lower edges that are wider than the 
openings of the chimneys and overlap those. Between the chimneys there is 
given space to confine debris and spilled liquid. Also here the problem 
exists that spilled liquid running over the edges of the keyboard housing 
might intrude there into the interior of the keyboard. Furthermore, the 
problem of avoidance of the removal of the caps toward the top is not 
addressed at all. constructed from the beginning to be protected against 
vandalism and spill problems. It is not considered to make out of a widely 
used keyboard of special design a keyboard which by simple means can be 
made spill prove and vandal-protected. 
A further means to protect keyboards against vandalism is shown in U.S. 
Pat. No. 4,449,763. There a protective cover in the form of a transparent 
hood is fixed to the housing of the machine and allows only that the 
operator can insert his hand between the keyboard and the hood. The 
distance between the top of the hood and the buttons of the keyboard is 
sufficient to allow normal hand and finger movement by the operator, but 
to close to permit any appreciable hole-hand movements normally to the 
keyboard whereby the operator cannot strike the keyboard buttons with 
accessive force which can damage the machine. Also the hood prevents 
access of spilled liquid and other debris to the keyboard. A keyboard 
provided with such a hood can only be used in a certain design arrangement 
because it must be certain that the operator can insert his or hers hand 
between the hood and the keyboard panel. Thus the possibilities to include 
such a keyboard into a machine are very limited. There is no possibility 
to have open access from the top to the keyboard which makes it 
unaccessable for most applications. 
It is the object of the present invention to provide out of a widely used 
standard keyboard such a keyboard that is protected against vandalism and 
spill. This should be reached by simple means and without changing 
anything at the base keyboard itself. 
These objects as well as others are basically solved using a keyboard as 
provided in the preamble of claim 1 A keyboard in which the removal of 
keys towards the top of the keyboard might be avoided is shown in the 
European Patent 0 088 365 B1. There a keyboard is described in which the 
keys are arranged in a carrier plate and in which a contact plate with 
electrical switching contacts is arranged underneath the keys. The contact 
plate presses the keys toward the supporting plate. The keys themselves 
have a special form with a wider foot part resting underneath the carrier 
plate. The body of the key itself is somewhat cone-like formed and 
protrudes through the opening within the carrier plate to the top of the 
keyboard. By the construction of the wider foot of each key this key 
cannot be removed toward the top of the keyboard. When the key in this 
kind of keyboard construction is depressed, there is generated a gap 
between the key and the carrier plate. Thus upon depressing of such a key 
spilled liquid standing on the support plate and the top of the keys, 
might intrude into the interior of the keyboard. So this construction 
cannot be considered to be spill prove. 
In the UK Patent Application GB 2 046 524 A there is described a keyboard 
comprising a rigid apertured top plate and a tray-like aperture retention 
plate placed against the back of the top plate to define a cavity 
therebetween. The operating button operates within the cavity and extends 
trough the apertures in the two plates. The inward and outward movement is 
limited by a flange arranged around the button. A sheet of resilient 
material is sandwiched between the retention plate and the rigid backing 
plate to thereby seal the cavity. The construction is deemed to provide a 
very tough switch usable in arduous environments and where vandalism is a 
problem. This known construction provides a special purpose keyboard, 
specially and by applying the features laid down in the characterizing 
clause of claim 1. 
In advantageous manner the invention provides that the removal of keys 
toward the top of the keyboard is not possible and that spilled liquid is 
hindered to intrude over the edges into the interior of the keyboard 
housing. 
Further developments and advantageous attainments of the present invention 
are laid down in the dependent claims.

FIG. 1 consisting of FIG. 1A, 1B, 1C and 1D shows different parts which 
together form the protected keyboard in accordance with the present 
invention. So as basis in FIG. 1D in perspective view a standard PC 
keyboard base group 1 is shown. FIG. 1C shows above FIG. 1D a rubber 
gasket 2 and a drain 3 separate from it together with FIG. 1B. The gasket 
and the liquid drain could be separate parts as shown or they could be one 
single part. In any case the gasket fits on the base group 1 to seal a 
certain part of the keyboard. Above the FIG. 1C with the gasket 2 and the 
liquid drain 3 there is shown in FIG. 1B a grid support 4 that also could 
be called supporting frame. The supporting frame 4 has a rim 5 of 
rectangular form. On both sides along the length side of this rim 5 there 
are provided two flanges 6 and 7. Also shown in FIG. 1B are clamps 9 by 
which the supporting frame 4 might be connected to at one length side to 
the base group 1. Above FIG. 1B there is shown in FIG. 1A a grid plate 8. 
This grid plate 8 has openings 10 that are arranged in the same pattern as 
the keys 11 on the base group 1 shown on FIG. 1D as will be apparent later 
on. The size of the openings 10 is chosen such that the asymmetric 
conically formed key buttons cannot be removed toward the top of the 
keyboard if grid plate 8 is fixed to the supporting frame 4. 
In FIG. 2 there is shown the completely assembled protected keyboard 12 
consisting of the base group 1 to which the supporting frame 4 is fixed. 
Fixing is performed on one side by the clamps 9 and on the other side by 
screws 13. To the supporting frame 4 with its side flanges 6 and 7 there 
is secured the grid plate 8 by means of screws 14. As can be seen from 
FIG. 2, the rim 5 of the supporting frame 4 provides a distanced fixture 
of the grid plate 8, distanced from the base part 1. By this arrangement 
above the surface of the base group 1 the rim 5 forms a shallow trough. 
Liquid contained in this trough may be outflow controlled in manner 
through the liquid drain 3. 
In FIG. 3 there is shown a side view of the assembled and protected 
keyboard 12 as shown in FIG. 2. In this example the upper row 15 (see FIG. 
1D) of key buttons is not confined by the grid plate 8. Only the five rows 
on the right hand side of row 15 are confined by grid plate 8. This grid 
plate 8 is fixed to the flanges 6 and 7 of supporting frame 4. As can be 
seen, supporting frame 4 is fixed to the base group 1 by means of base 
plate 16 and the clamps 9 on the right hand side and the screw connection 
13 on the left hand side. 
As further can be seen, emanating from the base group 1 there are stem-like 
chimneys 17 on top of which the key buttons 18 are provided. Those key 
buttons 18 are formed asymmetric conically. The lower edges 19 are all 
longer than the top edges 20 of each single key button 18. To avoid that a 
key button 18 can be removed from the stem-like chimney 17 to the top of 
the keyboard the openings 10 in the grid plate 8 have a size between the 
measuring values given by the lower edges 19 and the upper edges 20 of 
each associated key button. Thus a removal toward the top is avoided. 
As also can be seen from FIG. 3 through the liquid drain 3 all liquid 
confined in the shallow trough indicated by the reference number 21 and 
collected above base group 1 and between the rim 5 can be disposed in 
controlled manner through the liquid drain 3. 
FIG. 4 shows the keyboard protected against vandalism and spill in 
accordance with the present invention incorporated into a self service 
transaction station like the IBM 4737. For a person using this keyboard 
for entering information and commands into the machine there are exposed 
to that person only those keys which are necessary. That means for example 
then that the keys in row 15 (see FIG. 1D) and the six keys below row 15 
on the right hand side in FIG. 1D, are covered by a special cover 22. 
Therefore in the example shown in the different FIGS. 1, 2, 3, the row 15 
is not included into the supporting frame and the aperture grid plate. 
In the example shown in the FIGS. there is provided a separate supporting 
frame 4. It is clear to a person skilled in the art, that to the grid 
plate 8 there could be provided immediately in one and the same piece the 
rim 5. Furthermore the supporting part could be provided in one piece 
together with the grid plate 8 and immediately secured and fixed to the 
base group 1 of the keyboard. Also other fixing means as clamps 9 or 
screws 13 and 14 could be provided. It also can be provided that the edges 
of the openings 10 have a slope coinciding with slopes of the immediately 
adjacent sides of the appropriate key button.