Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
11~'55~7
1 The present invention relates to the construction of touch
sensitive panel keyboards which have data entry applications for
computer, industrial, commercial and domestic users.
The conventional keyboard at present in use has a plurality of
separate key-buttons which are mounted to allow each key button to be
depressed. However there is another type of keyboard which we will
call a touch sensitive panel keyboard in this specification. This
type of keyboard has no key-buttons but is in the form of a flat
panel consisting of a number of layers.
The front layer is called a facia overlay and carries markings
indicating an array of key positions each with key indicia such as
letters or numbers. The other layers form a complementary array of
switching devices which may be operated by touching the facia overlay
with a finger or stylus. Depending upon the switching device the
facia overlay may require zero depression for example with a cap-
acitive type switching device or a depression of about 0.5 millimetres
(0.02 inches) for closing the contacts of an electrical diaphragm
switch or of an electrical microswitch.
Keyboards including diaphragm switches are described in US
Patents 3,308,253, 3,560,675, 3,668,337 and 4,017,697. Keyboards
including capacitive switching are described in UK Patents 1,435,265,
1,457,572 and US Patent 3,244,369. A piezoelectric keyboard is
described in the IBM* Technical Disclosure Bulletin, June 1977,
pages 315, 316.
One touch sensitive panel keyboard construction of the diaphragm
switch type has been used by International Business Machines Corporation
in data processing equipment types 3704, 3614, 3203, 5937, 3800 and
3850. With this construction the diaphragm switch is formed by a
layer having aperatures at switch positions, which is sandwiched be-
tween layers carrying printed circuit switch wiring.
The facia overlay for these keyboards is a laminated structure
* Registered Trade Mark
UK9-77-016 - 2 -
~.
ll~SS8~'
1 requiring numerous manufacturing steps and is thus expensive to pro-
duce. As a result these keyboards have only found application in
equipment such as cash issuing terminals where appearance is important
enough to justify the high cost. Five layers, laminated together are
required as detailed below.
Layer 1. Front. Clear polyethylene terephthalate 0.025 mm
(0.001 inches) thick.
Layer 2. Clear polyvinyl chloride acetate film 0.12 mm (0.005
inches) thick.
Layer 3. Clear polyvinyl chloride film 0.12 mm (0.005 inches)
thick. This third layer is screen printed. Where eight colours are
required this involves eight screens and eight separate screen
printing operations.
Layer 4. Clear polyvinyl chloride acetate film 0.12 mm (0.005
inches) thick.
Layer 5. Red polyethylene terephthalate film 0.025 mm ~0.001
inches) thick, if required.
The screen printing steps produce opaque colours for key positions,
key indicia and other associated graphics, and it may be noted that
both white and black can be screen printed. Portions of the facia
overlay not screen printed are a transparent red colour due to the
presence of the aforementioned red transparent layer 5. This red
layer is necessary when portions of the facia overlay are required
to transmit red light from selectively illuminated rear indicator
lamps.
The object of the present invention is to provide an improved
construction of touch sensitive panel keyboards.
According to the present invention a touch sensitive panel key-
board comprises a plurality of electrical switching devices providing
an array of key positions, and a laminated overlay including a photo-
graphic film transparency developed to provide a complementary array
of key indicia or graphics associated with key positions.
UK9-77-016 - 3 -
iS~7
1 According to another aspect of the present inyention a method of
manufacturing a touch sensitiye panel keyboard comprises fabrlcating
a plurality of electrical switching devices to provide an array of key
positions, fabricating a laminated overlay including a photographic
film transparency developed to provide a complementary array of key
indicia or graphics and placing the overlay over the array of key
positions.
According to a further aspect of the present invention a touch
sensitive panel keyboard overlay comprises a laminated structure in-
cluding a photographic film transparency developed to provide an array
of key indicia or graphics and a white backing for colourless portions
of the photographic film transparency required to appear white.
In embodiments of the present invention the screen printed prior
art facia overlay on touch sensitive panel keyboards, described above
is replaced by a facia overlay in which coloured key positions, key
indicia and other associated graphics are produced on a photographic
film colour transparency. The overlay may extend beyond the actual
key positions to provide desired additional information, graphics or
illustrations. This provides an improved manufacturing process as all
colours, except white, required may be reproduced by one exposure,
whereas the prior art requires a separate screen printing step for each
required colour with resulting high production costs.
The prior art facia overlay requires an additional transparent
red layer for rear illuminated portions, whereas the colour trans-
parency of the present invention provides transparent portions of any
desired colour without the need of additional transparent coloured
layers.
Although black may be reproduced on the colour transaprency
white cannot. Thus where white indicia or graphics are required these
are produced by transparent uncoloured portions accompanied by a
backing layer with selectively applied white portions.
As a touch sensitiye panel keyboard embodying the present inven-
UK9-77-016 - 4 -
llG5587
1 tion is not restricted to a few colours as required with the prior artscreen printed keyboards, the designer Is glven greater colo~r freedom
of the whole colour spectrum to proYide a Yisually attractiYe multi-
coloured keyboard with elaborate graphics or illustrations. ~lso
characters in the many languages required may be provided at little
additional cost.
In order that the invention may be more readily understood,
reference will now be made, by way of example, to the accompanying
drawings in which:
FIGURE 1 is a schematic showing the components of a diaphragm
type keyboard embodying the present invention.
FIGURE 2 is a schematic showing the components of a capacitive
type keyboard embodying the present inYention.
FIGURE 3 shows the layout of keys for a typical touch sensitive
panel keyboard.
Referring now to Figure 1 which shows the components of a dia-
phragm type touch sensitive panel keyboard. The keyboard is assembled
in an aluminium base 1 with a sealing gasket 3. Base 1 carries
peripheral slots (not s~wn) into which the other layers of the key-
board slide. Location is by a pair of dowel pins 2 which mate with
corresponding holes in the other layers. Base 1 also has a plurality
of apertures 4 to accommodate a corresponding plurality of light
emitting diodes 5 mounted on printed circuit board 6 to provide
selectiYe illumination of the keyboard. When used in equipment the
assembled keyboard is mounted by means of bracket 7, whilst board 6
is plugged into a separate socket.
Next to base 1 is substrate 8 of glass filled epoxy aperatured at
9 to transmit light ~rom light emitting diodes 5. Substrate 8 carries
gold plated printed circuit wiring (not shown~ in a generally Yertical
direction along columns of key positions and which crosses each key
position as is well known in the art, The printed circuit wiring
terminates on edge contacts 10.
UK9-77-016 - 5 -
SS8~7
1 The next layer is separator 11 of polyethylene terephthalate which
has a plurality of holes 12 one for each key position. AboYe separator
11 is diaphragm 13 which carries gold plated printed circuit wiring
(not shown) in a generally horizontal direction along rows of key
positions and crosses each key position. The printed circuit terminates
on edge contacts 14.
The next layer 15 of flexible plastics material is called an under-
lay which carries a switch element at each key position 16. Each
switch element consists of two adjacent rectangular holes separated
by a strip of the flexible material.
The last layer is facia overlay 17 with a plurality of key positions
18 whose construction is described in detail later. The assembly is
completed by screws 19 which pass through clamp 20, pad 21, overlay 17,
underlay 15, diaphragm 13, separator 11, substrate 10 to secure the
layers to base 1.
Pressure at a key position 18 on the front of the keyboard de-
presses the strip of flexible material of a switch element at position
16 to operate a flexible diaphragm switch in layers 13, 11 and 8.
Facia overlay 17 consists of three layers of flexible material
bonded together with adhesive to form a multilayer laminate.
Layer 1. Front film of clear polyethylene terephthalate 0.025 mm
(0.001 inches) thick to provide wear resistance as it is contacted by
an operator's finger, and antiglare.
Layer 2. Photographic film colour transparency with emulsion
down to provide coloured key positions, key indicia, and other re~uired
graphics and illustrations. Suitable photographic colour film is
commercially aYailable from photographic film manufacturers haYing
an ester or acetate base,
Layer 3. White opaque polyYinly chloride film 0.12 m~ (0.005
inches) thick to proYlde white characters which are formed on the
colour transparency by colourless characters and brighter colours
when Yiewed from the front. Lay~r 3 is apertured to pro~ide light
UK9-77-016 - 6 -
iS~7
1 transmission for light emitting diodes 5.
Alternatively the third layer may be of clear polyvinyl chloride
film selectively screen printed white as backing to provide characters
of white appearance. When intense red appearance of indicators is
required, an additional fourth layer of red transparent polyethylene
terephthalate film 0.025 mm (0.001 inches) thick is added as the last
layer. These layers are bonded together by adhesive to form facia
overlay 17.
The exposure of the colour film requires the preparation of a
hand made coloured artwork master including photographic illustrations
if required which is photographed to produce a working master. The
artwork master may exclude indicia which change with language. These
may be included on a series of transparencies, one for each language.
These are placed in front of the artwork master before photographing
so that one artwork master can provide a working master for each language.
Figure 2 shows the components of a capacitance type touch sensitive
panel keyboard including associated electronics. A facia overlay 25
provides a plurality of key positions 26 with the required key indicia 27
and graphics (not shown). This facia overlay is similar to the overlay
2~ 17 described earlier and includes a photographic colour film. As key
indicia 27 are white, a white dielectric screen printed white backing
sheet 28 is required to give transparent key indicia on the photographic
film a white appearance as previously explained.
The next layer is a printed circuit card 29 with a capacitance pad
30 corresponding to each key position 26. Each capacitance pad 30 is
associated with a pair of capacitance elements on the rear of the cards
which are selectively connected to edge contacts 31. The three layers
consisting of overlay 25, dielectric sheet 28 and printed circuit card
29 are bonded together to form a rigid structure with edge contacts 31
projecting to plug into a connector 32 attached to a conventional
electronic printed circuit card 33 which carries printed wiring 34 and
electronic components 35. Printed circuit card 33 provides the
UK9-77-01~ - 7 -
ii~
l electronic to sense the capacitance change when a key position is
touched.
An alternative construction of a facia overlay for use in
embodiments of the invention follows:
Layer 1. Front film of clear polyethylene terephthalate 0.025 mm
(0.001 inches) thick to provide wear resistance, and antiglare.
Layer 2. Photographic film colour transparency with emulsion down.
This layer provides coloured key positions, key indicia, other illus-
trations or graphics.
Layer 3. Clear polyvinyl chloride film 0.12 mm (0.005 inches)
thick. White colour is selectively screened onto this layer to pro-
vide a white backing for layer 2. The white backing is omitted in
areas where light transmission from indicator lamps through the panel
is required or in areas where layer 2 is black.
Layer 4. Clear polyvinyl chloride acetate film 0.12 mm (0.005
inches) thick.
Layer 5. Red polyethylene terephthalate film 0.025 mm (O.OOl
inches) thick. This layer is optional and is only required when
intense red appearance of indicator lamps is specified.
~ The above layers are bonded together with adhesive to form a
laminated structure.
Where a coloured keyboard is not required layer 2 is replaced by
a "black and white" film to give a lower cost overlay. Also red
layer 5 may be omitted and self coloured light emitting diodes used
for the indicator lamps. White is obtained as previously by the use
of a white backing film.
Figure 3 illustrates the appearance of a typical banking terminal
keyboard facia overlay 17 which may be used in embodiments of the
present invention. The length is approximately 15 inches and width
approximately 8 inches. This figure is reproduced as a line drawing
with no attempt to indicate colours. The keyboard is black external
to key positions and nearly all the characters are white.
UK9-77-0l6 - 8 -
1 l~SSt~7
l The eight keys 40 have white characters on a blue background whilst
keys 41 have white characters on a green background. Keys 40 and 41
each have a transparent circular red indicator 42 outlined in black.
The twelve numerical keys 43 have white characters on a red background.
The colours of the remaining right hand keys follow with back-
ground followed by character: 44 red, white : 45 white : 46 yellow,
black : 47 green, white.
Figure 3 illustrates that embodiments of the invention may provide
touch sensitive keyboard panels which use colours freely and no rest-
riction is placed on the selection of colours from the human factors
point of view.
Another keyboard facia overlay (not shown) which may be used inembodiments of the present invention is what could be called a customer
choice keyboard overlay. This overlay has a number of key positions
each of which is associated with pictures illustrating the possible
choices. Instructions for operating the keyboard are included on
the overlay located on a portion of the overlay remote from the key
positions.
UK9-77-016 - 9 -
