Dynamic user interfaces include lighting schemes that show HMI function. Here Robert Davies, Marketing Manager for EAO considers how multi-colour illuminated switches are lighting the way forward in consumer and industrial applications by allowing for more functionality and features
Ergonomically designed operator interfaces with intuitive controls enhance the user’s experience and perception of equipment. Designers increasingly need to add more functionality, but are often restricted by front panel space.
In many industrial and professional applications, operators still need pushbutton type controls that provide clear; tactile and visual feedback related to their input and that indicate the status of the equipment.
Multi-colour halo illuminated switch technology allows designers to fit additional functionality and -features into the pushbutton switch, by providing dynamic lighting effects that can prompt the user for action, or advise them about the status of the equipment.
The switch bezel can be illuminated with eight PLCC style SMD (surface mount display) LED’s and a central single LED or a bi-colour three pin LED. This design provides a high brightness and uniform halo of light around the switch body.
For designers and developers, this opens up new possibilities for creating exciting, engaging and more intuitively, easy-to-use control panels – in even smaller areas.
More functions can be assigned to single switches; initiation sequences can be shown with a dynamic LED countdown; a pushbutton can be used to increase or decrease output – with each press, another LED lights up around the ring, the pushbuttons can be flashed to prompt for input, or to show a fault status.
They are also ideal for use alongside touchscreens and displays as a way of emphasising additional or primary controls.
Consumer electronic applications
Up until recently this technology has been the realm of high volume ¬consumer electronics applications, requiring expensive moulded plastic light guides and buttons, but now EAO is able to bring this functionality to lower volume industrial applications with its ‘off the shelf’ panel mount transparent bezel light guide and range of metal and plastic buttons.
The IP67 sealed switch is fitted to the panel in a 22.5mm cut-out and the equipment manufacturer develops its PCB with the company’s switch ¬element, the SMD LED’s and the LED drive electronics.
The mounting flange is screwed to the PCB and the assembly snaps on to the back of the switch without the need for mounting pillars.
The switch lens can be made out of coloured plastic, or aluminium and be flush or slightly raised for palm push operation, the lenses can be engraved or printed with symbols or text.
There are also lacquered lenses with reversed out illuminated symbols like the international On/Off or the Standby symbol.
The PCB needs to be designed to accommodate a switch element, a central illumination LED, the ring of SMD LED’s along with the series resistors and microprocessor.
The circuit design will depend on the complexity of the lighting effects and how each LED needs to be controlled.
Individual LED’s at the different positions could be simply switched on and off with perhaps four LED’s of each colour to give a bi-colour effect.
For a more creative effect, each SMD LED could be a PLCC4 multi-colour RGB LED driven with PWM control to vary the brightness and the colours – giving a huge range of possible lighting configurations.
For example, a spinning halo of light rotating around the switch, a heartbeat that pulses, alternating colours, or lights that count up/down at each press of the button.
There are many microprocessors such as a PIC that could be used to control the LED and the programming could for example be in C – the selection is matter of personal choice.
The mechanical drawings and the component layout for the LED’s and switches are available from the -company’s website and there is also the chance to download Gerber files and drilling plans for the basic switch and SMD layout portions of the PCB design.
This technology can be used in a wide range of applications, with its rugged construction, and high level of environmental sealing it is particularly suitable for industrial machinery, control and instrumentation, and specialist vehicle applications and in particular where the pushbutton switch needs to convey additional information about the status of the equipment.
