Touchless Switches Provide a Hygienic User Interface Option

IDEC Corporation, Sunnyvale, CA

Worldwide awareness surrounding the need for hygiene was escalated to the extreme by COVID-19. Now that the pandemic’s beginning is a few years in the past, designers and OEMs for machinery and other user-facing equipment are investigating ways to provide an adequate user interface, while minimizing the need for people to touch the controls.

A new option in the form of low-profile touchless switches incorporates smart electronics and a dedicated sensor to provide reliable detection without any moving mechanism. This means the devices are very durable and provide a long operating lifetime. The compact form factor is nearly flush and requires very little depth behind the panel face, so it is easy to install anywhere and resists damage from most types of contact (Figure 1).

Although cleanliness is always recommended, these touchless switches improve user safety and minimize infection risk even if large numbers of people operate them. There is no need for users to wear gloves, and no requirement for using protective films or performing chemical sanitation, which saves on labor and material costs.

The switch works using near infrared LED photoelectric reflection technology, with a central emitter and receiver in the front face to detect objects, such as a user hand or finger. A standard diffuse reflection model includes a sensitivity adjustment and is suitable for detection ranges of about 70 to 250 mm. A short-range convergent reflection model emits and receives light at an angle without any adjustment, for a detection range of about 5 to 30 mm.

The short-range model is less affected by object color or material, and is less susceptible to background objects, to avoid false detection. Of course, the reflectivity, color, material, and surface of the object being detected always plays a role. Dark objects, such as gloves, would be detected only at a closer distance than a bare hand, for instance. The switches will automatically adjust themselves so that multiple devices installed close together will not affect each other through mutual interference.

Intelligent electronics enable the device to drive an integrated two-color LED ring, which can be red/green or blue/white, the latter being more visible to people regardless of their color vision. Designers can configure the illumination and color status of the ring to provide users with visual feedback that a switch operation has occurred, or to indicate a standby state (Figure 2).

Because touchless switches include both detection and visualization capabilities, a single device can effectively be used to replace one sensor switch and two LED lamp indicators, saving installation space and overall cost. These touchless switches also incorporate the following features:

• solid-state optically isolated relay output

• selectable for a 0.5 second on-delay and 2.0 second off-delay timer, or direct acting

• operates at 12 to 24 VDC, with 100mA max load current and reverse connection protection

• installed in industry-standard 22-mm mounting holes, available in black plastic resin or silver aluminum alloy

• rated IP65/67 and UL Type 4X, and suitable for outdoor use.

Touchless switches can be affected by direct sunlight, dirt, and water in a way that could provide false signaling, so designers need to review the specifications for their applications. However, these devices help designers create hygienic systems, while avoiding costly provisions required by traditional devices.

Touchless switches are an ideal solution for industries such as food, beverage, pharmaceuticals, medical, and chemicals where sanitary design is important. They are also useful for protecting the well-being of users in everyday commercial applications, such as vending machines, elevators, ATMs, and anyplace where pushbuttons are needed.

This article was written by Luiz Shida, Marketing Specialist, IDEC Corporation (Sunnyvale, CA). For more information, visit here  .

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