Switches are where the simplicity of your design will
play out, but the simplicity of the interaction will depend
on the decisions you make when specifying each switch in
the interface of your device. When it comes to streamlining the human-machine interface, designers need to pay
attention to a particular set of criteria to ensure the interface will accomplish its intended purpose. When designing
your next device, consider the following questions.
How will the user interact with the machine?
The needs of the end-user must be considered first and
foremost. This includes factors such as feedback, illumination, and legends to indicate dedicated functions or statuses
designers should consider if feedback needs to be tactile,
audible, or visual.
Tactile feedback transmits a sensation to the
operator to indicate
transfer of circuit.
Other switch applications may use
at the man-machine
interface. Illuminated switches use an internal light, typically a LED or incandescent bulb, to indicate status. There
are pros and cons to each. LEDs have a virtually unlimited
service life at about 100,000 hours and an unmatched level
of brightness. On the other hand, incandescent lamps operate in a self-destructive mode to produce light, resulting
in a shorter lifetime of approximately 7,000 hours.
Another option for indicting switch status is legends.
Legends, which include engraving, screen printing, pad
printing, and Mylar inserts, can be used to identify specific functions. Some LED switches offer alternating legends
and colors that display different combinations when the
switch is ON or OFF. For example, bi-color LEDs use standard RGB colors that alert users to different options based
on pre-programmed functions and add aesthetic appeal to
What about switch size?
The size, location, and application of the human-machine
interface will have a significant role in determining the
switch best-suited for your device. Designers should
also consider the ease of use of different switch sizes.
Consumers and designers often feel that smaller is better,
but it is more important to select a switch that not only
fits the size parameters but is also sufficiently user-friendly.
This is especially important in consumer products.
What is the best actuator for the user?
Actuators come in a wide selection of categories, such as
pushbutton, toggle, rocker, paddle, rotary, keylock, and
slide-actuated, and within each category a multitude of
sub options are available. No matter the actuator type,
these switches have one hardwired function. The key to
determining the best actuator type for a switch design is
to determine what the switch will specifically be used for
and by whom it will be used, and then logically consider
each actuator option in those terms.
Keylock switches, for instance, are often used to enhance
the security of a system. A server blade in a data center
may use a keylock switch that requires the user to insert
a key in order to operate the switch. This helps to reduce
human error and to prevent tampering.
Will your user and design benefit from a Smart Switch?
As demand for greater functionality from devices and
equipment continues to increase, many designers have
found that the use of traditional switches, whether toggle,
rocker or pushbutton, in certain scenarios is no longer
sufficient. Programmable switches have become a useful
Programmable switches combine the easy-to-read,
well-illuminated menus and multiple functions of a
touchscreen with the tactile feedback of a dedicated
function key. These smart switches provide designers with
space-saving, multifunction alternatives to traditional
switches. In large banks of switches, programmable switches can be invaluable to simplifying your design and assist
users in completing tasks more efficiently.
For example, the broadcast industry commonly uses programmable switches to help control the various elements of
television broadcasts. Complex control panels can quickly
become littered with dedicated function keys. However,
programmable switches allow for more functionality from
a smaller panel size because a single programmable switch
is capable of accomplishing the same functions as multiple
dedicated function keys.
Equipment used in the food service industry can also
use programmable switches to simplify tasks, reduce human error, and increase safety. Quick-service restaurants
may use a programmable switch to alert workers when a
grill is hot, when to flip the burger, and when to remove it.
The ability to program the switch not only ensures consistent cook times but also reduces training time, speeds up
service, and makes food handling safer.
Remember to keep it simple
For the design engineer, creating the human-machine
interface often feels like a work of art, as this is where
your device shows the user the simplicity of your complex design. If the designer does a poor job with the
human-machine interface, the device will be difficult to
use and ultimately fail. However, if you bear in mind the
old acronym KISS and the words of Albert Einstein, your
design will clearly indicate what is going to happen next
and make the interface intuitive.
For more Design Talk articles visit www.ecnmag.com/designtalk