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Overlay Material
It is very important to select the proper overlay material
first! The overlay material can be specified depending
on the environment in which it is to be used. The most
commonly used material can be used where exceptional
chemical resistance is not required. It has basically
a non-glaze matte surface with good handling characteristics.
We use special grade POLYESTER to provide special characteristics
like chemical resistance, scratch resistance and excellent
durability.
Colours on Graphics
Any shade of colour can be used for the keyboard provided
that the sample of colour shade is given. However it
is recommended that one should use primary colours.
The reason being, it is very difficult to obtain the
same shade of colour harmony of the keyboard overlay
it is recommended that minimum colours should be used.
We recommend four colour combinations to achieve excellent
result. The use of less colours will also reduce the
cost of keyboard.
Keyboard Layout
In order to give accurate requirement of your keyboard
it is necessary that you must specify all sizes, shapes
and dimensions in detail. The fixed starting point for
all dimensions can be any one of the corners of the
keyboard. To avoid confusion, we recommend the following
sequence of drawings as far as possible. You must furnish
front view, side view and basic view of each drawings.
Sequence
Sheet 1: This sheet should contain the detailed
overlay drawing. Here you must also indicate the name
of the font and size for legends on the graphic.
Sheet 2: This sheet should contain detailed
dimensions of overall keyboard size, LEDs, keys, display
window etc.
Sheet 3: This sheet should contain details of
keys, display windows, or any other graphic mimic to
be done on overlay with proper dimensions.
Sheet 4: This sheet should contain a detailed
drawing of mounting holes & keyboard connectors
with dimensions. The drawing may show the rear view
when viewed from front and side view to give details
of length of studs.
Sheet 5: This sheet should contain details about
colour specifications showing colour shades and specific
locations.
Sheet 6: This sheet should provide details about
circuit diagrams, pinout details, dome specification,
connector specifications etc.
Tactile & Non-Tactile Keyboards
Non-tactile keyboards are momentary contact keyboards
designed to carry low voltage signals. These keyboards
are made without metal domes and need less pressure
to activate the key. The life expectancy of each key
in these keyboards is very high at over 2,000,000 cycles.
Tactile keyboards are momentary-contact keyboards designed
to carry low voltage signals by using metal domes or
poly domes to provide a tactile feedback when the key
is pressed. In non tactile keyboards, it is preferable
to have embossed keys for this feedback. The metal domes
normally used are of stainless steel with nickel or
gold plating. The life expectancy in these keyboard
is over 1,000,000 cycles.
Display Window
There are various types of selective textured windows.
To have a better and clear visibility, the display should
be mounted as close as possible to the keyboard. For
LCD display, one can have either clear and transparent
window or transparent textured window. For LED displays,
one can have coloured textured window or transparent
window.
Pin-Outs
When you specify the circuit and pinout yourself, it
is very important that pin no. 1 be designed in the
circuit. However, because of our experience in track
design we recommend to allow us to specify pinout, which
can result in the supply of workable, cost effective
keyboard to you.
Connectors
We can supply any type of connector, which is PCB solderable.
There can be different types of connectors, like low
cost Reliamate connector, FRC connectors etc. all these
connector s can be either right angled or straight.
The specifications of connectors and their pin configurations
have to be given properly to enable us to quickly develop
the keyboard.
Thickness/ Mounting
Keetronics can offer various thickness for the PCB depending
on your requirement. The minimum thickness like 0.8mm,
1.6mm, 2.4mm can be ideally replace membrane keypads.
For 1.6mm thickness, we suggest the use of mounting
studs. Metal studs from 7 mm length to 30 mm length
are offered for mounting the keyboards for longer stud
lengths we prescribe to use internal threads Stand Off,
where any length of screws can be inserted. For firm
grip and mounting , we recommend to use M3 and M4 thread
studs.
ESD/ EMI Shielding
We can provide special protection to keyboards, when
they are to be used in conditions of extreme temperature
and humidity. We can also provide ESD/EMI shielding
on keyboards, to protect sensitive circuit components
from Electromagnetic interference and Electrostatic
Discharge.
Keyboard Edge Protection
Sealed Keyboard Switches should always be mounted in
such a way so as to protect keyboard edges against operator
handling and abuse. We offer some of the best protection
methods which you can easily use in your applciaiton. |
