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 matt 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 - Tactlive 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 scan be either right angled or straight. The specifications of connect 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. |
