Keyboards for electronic devices are now more technologically advanced

Technology and innovations are continuously driving the world of keyboards. They offer multiple options for customisation as well

By Nitasha Chawla

Tuesday, July 10, 2012: A keyboard is essential for operating and controlling tools, equipment and machinery. The keyboards used for operating electronic devices are sturdy and quite different from the computer keyboards we are familiar with, as they are specifically designed for machinery used under varied environments.

While most keyboards are based on the QWERTY format, one can get custom designed keyboards depending on personal requirements. Today, there are many options available in the market, with keyboards coming in different shapes and colours.

Electronic keyboards can be used in any product that requires just a momentary input of about 15 V and a maximum of 25 mA current. They are used in devices ranging from simple toys to complicated electronic controls. Some keyboard applications are weighing machines, microcontrollers for machines, appliances or gadgets, washing machines, microwave ovens, electronic safes, etc.

Says Amit Agrawal, proprietor, Advance Technologies, “In India, we get keyboards with push switches, touch switches or touch screens. Keyboards can be developed with tactile switches, non-tactile switches, mechanical switches, silicon rubber type touch sensors, etc. A keyboard is purely a customised product, which is developed as per the user’s requirement.”

Types of keyboards

Broadly speaking, there are three basic categories of keyboards that are used for interfacing with any machine. These are:

Long travel type keyboards which are similar to computer keyboards and are mainly used for applications like point of sale (POS), toll collections or any application where the user is a layman and expects feedback in response to the key being pressed. The life of these keys is more than 30 million operations.

Short travel type keyboards are preferred when the device doesn’t require frequent use of keys. They are used in medical diagnostics devices and handheld instruments.

The life of these keys varies from 1 million to 30 million operations depending on which technology is opted for. The advantage of

this type of keyboard is that it is not too thick and can be illuminated and customised for particular colour and size requirements.

Limited or no-travel type

keyboards are those that incorporate the latest innovation in haptics, which is basically a keyboard like a touch screen. Informs Rajesh Kulkarni, managing director, Keetronics (India) Pvt Ltd, “Unlike the touch screen, this technology gives users a feel of movement, without actual physical movement. Keetronics, a leading manufacturer, is working on this technology and will soon release such keyboards on a trial basis.”

Another proven technology in this category is the capacitive keyboard, which could be of glass, acrylic or even wood as the front facia, but the user will not get a feel of acknowledgement.

Coming to types of keyboards, these mainly comprise PCB and PCF based keyboards, metallic or vandal proof keyboards, capacitance keyboards, PC compatible keyboards, illuminated keyboards, resistive membrane keyboards (including snap dome keyboards), and touch electrical switches.

Shares Pankaj B Jambusaria, director, Vallabha Graphics Pvt Ltd, “Membrane keyboards are used quite commonly and are technologically advanced too but the only problem with them is that they are generally non-repairable (specially the flexible type of membrane keypads). Therefore, it is important that they should be properly designed as well as installed. Otherwise, if one key fails then the whole keypad and ultimately the entire machine that it has to connect with, fails.”

What players offer

Vallabha Graphics offers membrane keyboards of all types like soft touch flexible keypads, tactile touch flexible keypads, keypads mounted on metal plates or panels of aluminium, PCB based keypads that are developed on glass epoxy, PCB with varied thickness, etc. The company also makes front plates duly assembled with colourful graphics that can be used by customers to make keyboard panels with individual micro switches. It also offers flexible keyboards with inbuilt LEDs and resistors as well as polydome-type tactile keypads and keypads with embossed graphics.

Advance Technologies makes customised membrane keyboards, apart from rigid, flexible and rigid-flex keyboards with and

without tactile keys. These are available in various colours and designs, with tin, nickel and gold plating options that come with embossed keys.

Amit Agrawal cautions against the use of silver conductive paint or inks to make circuits by some manufacturers of membrane keyboards. “Customers are not aware of the disadvantages and risks of using silver ink while making membrane keyboards. Silver migration or pad lifting are some issues faced with such keyboards. Even though they are low cost, we strongly recommend that customers do not use silver paint or inks to make circuits,” he says. Instead of using silver, Advance Technologies uses flexible printed circuit boards (etched copper) to make flexible keyboards. The flexible copper clad sheets are available in different base materials and thickness. Some of these sheets are extremely flexible and can even be folded up to 360 degrees.

Keetronics (India) Pvt Ltd has all kinds of keyboards in its portfolio. The latest range being duraswitch keyboards, which offer the next generation of switch technology. The company’s devices offer a crisp consistent tactile feel and the life of the switch in such keyboards is above 30 million operations. These keyboards incorporate high impact construction, environment sealing and resistance to extreme temperature and pressure.

Duraswitch technology has applications in the medical, military, industrial controls and access control sectors.

SMD Circuit and Systems is a leading manufacturer and exporter of membrane keypads in India, offering a wide range of membrane keyboards in polyester, polycarbonate, PVDC, penta and static cling vinyl. These keyboards enable users to draw and mark diverse symbols and prompts that are useful when entering data. The membrane on the keyboard protects the electronic components of the keyboard from the hazards of spilt liquids, dust, etc.

Electronics India manufactures all types of membrane keyboards including the latest illuminated keyboards with functional indication as well as fibre optic backlighting. For many applications both function and indication backlighting is an important consideration. In most cases, this is achieved with LEDs mounted on the PCB directly below the membrane switch. However, Vikram Vilasagar, owner, Electronics India feels that this can cause some constraints on PCB positioning (directly below the membrane switch) or require the PCB to be bigger than the necessary size. He says, “Embedding the LEDs within the membrane switch is a useful alternative. The LEDs are surface mounted on a separate circuit to the membrane switch, however, low profile LEDs may be mounted on the same layer as the bottom circuit.

Technological advancements

Technology and innovations are continuously driving the world of keyboards. The latest development is the use of high grade conductive silver paste with the latest available heat stabilised polyester film. Recent innovations in polyester films, with scratch and chemical resistance and anti-microbial properties, ensures that the keyboard works fine even in challenging environments such as fuel dispensing pumps or operation theatres.

Says Rajesh Kulkarni, “Superior grade steel springs have increased the operating life of the keyboard compared to those of the previous generation. Also, the reduction in costs and the availablility of electronic chips in low volumes have opened up new opportunities to produce customised computer compatible keyboards for application in the cement industry, in power generation plants, etc.”

A new addition to the family of keyboards are the backlit variety that are best suited for applications where an operator has to work in the dark. Here, the intensity of the keyboard can be adjusted as per requirements. The keyboard is enclosed in a rugged enclosure made of thermosetting plastic. Due to its compact dimensions, the product is suitable for a variety of applications, such as biomedical, defence, handheld and other portable devices.

Keetronics have recently added these backlit keyboards to its range and they are available in red, green and amber colour lighting.

The company has also recently introduced 3D keys concept to the membrane keyboard market. This product is a result of a vast study of user requirements, where a user has to operate certain keys blindly or in the dark. It comes packed with features like extremely high chemical and mechanical durability of the keys, aesthetic and exclusive design possibilities, excellent tactile feel and faster data entry due to short travel of the keys with less operating pressure.

Says Rajesh Kulkarni, “We have put epoxy domes on the flat membrane overlay to have a great tactile feel and an excellent look to the product. A dome shaped area of a shiny plastic is accurately placed on the flat membrane overlay. This crystal clear material supports the visual appearance and improves the readability even where there is a wide viewing angle. The keys can be produced virtually in any shape and size and are best suited for industrial applications as well.”

The latest from SMD Circuit and Systems is the feather touch non-tactile keyboards, which do not cause any sensation while pressing the keys and are widely used for a flexible momentary contact designed to carry a low voltage signal. Informs Sanjay Agrawal, owner, SMD Circuit and Systems, “These keyboards are available with keys made without metal domes and need less pressure to activate. The conductor circuitry is completely sealed to provide a clean, durable and reliable electromechanical function. They have a life span of more than 5 million contacts.”

Electronics India manufactures keyboards with fiber optic backlighting. The main advantage of these keyboards is that fiber optic backlighting never wears out. In a typical design, two or more layers of woven fiber optic cloth are used to form a rectangular light emitting area. The fiber optic product is typically 0.068” (1.7 mm) thick and anywhere from 0.025 sq m to over 2.54 sq inches. The fibres coming off from one end are then bundled into a circular ferrule and coupled to one or more LED light sources. Says Vikram Vilasagar, “Fibre optic panels never need replacement. Remote light sources offer 10,000 to 100,000 hours life. Optical fibres are not affected by extremes in humidity (0% to 100%) or temperature (-40 to +85 deg. C).”

Tips for buyers

The following points should be considered before choosing a keyboard for your machines:

The environment and the usage of keypad: If the keyboards are for use in industry, they should have a rugged button operation that ensures that the operator’s fingers do not slip off when working in various environments. Therefore, silicon material is widely used in the making of these keyboards.

No compromise on quality: A buyer should never compromise on the quality of the keyboard on account of its cost because even if one key fails, not only the entire keypad fail but the very machine the keyboards is connected to becomes non-operational.

Adherence to quality standards: If a manufacturer follows the American Society for Test and Measurement (ASTM) standards for membrane switches and keyboards, it will result in a quality product.

Technical specifications: Generally, for electronics applications, the rating for keyboards is 15 V DC and 25 mA of DC current; the lifecycle of keys should be about 1 million operations; the contact bounce should be less than 5 ms and resistance, which is circuit dependent generally, should be less than 100 ohms (barring a few exceptions).

Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine