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Proximity sensors come in many shaper and forms. HoloTouch has technology for a hands-free holographic switch and Silicon Labs just introduced two infrared proximity sensors.

Silicon Labs -- Si1102 and the Si1120 Sensor ICs

In October 2009, Silicon Labs introduced two QuickSense infrared proximity sensor, the Si1102 and the Si1120. The Si1102 has a detection range of 40-cm (about 16 inches) and the Si1120 has a range of 50 cm (about 20 inches). The latter includes an ambient-light sensor.

The Si1102 sensor lets electronic devices quickly detect a person nearby and generate a logic output for a host processor. Thus, if a user comes close to a display, the sensor can direct an MCU to turn on or adjust the display's lighting. The Si1120 sensor will detect the ambient light incident on it and it lets developers set one of seven control modes that a host MCU can change on the fly. Those seven modes comprise three proximity ranges, three ranges for sensing ambient light, and one calibration mode. Silicon Labs' news release notes potential uses in touch screens, instrument panels, games, security equipment, appliances, and toys, among others. The device produces a pulse-width modulated output and its average power consumption comes in at about 0.5 mA.

The Front Panel Evaluation kit (FrontPanel2EK, $US 40) includes capacitance touch sensors and an Si1120 IR proximity sensor.

Silicon Labs also introduced an infrared touch-less slider control, the QuickSense IrSlider, that can detect motions such as pause, tap, retract, up/down (or right/left) scroll, and flick.

You can read more at: news.silabs.com/article_display.cfm?article_id=4620. The company's QucikSense Development Studio provides a set of development tools common to all the infrared proximity sensors. And you can buy development kits for these sensors, too. Learn more at: www.silabs.com/products/mcu/capacitivesense/Pages/QuickSenseStudio.aspx.

Holotouch -- Holographic Switch Floats in Air

I talked recently with Doug McPheters, president of HoloTouch, which has an interesting technology that projects holographic images and reacts when people "touch" those images that seem to float in air. McPheters explained his technology fits well in places where people cannot or should not touch a switch. Electrical switches in operating rooms, slot machines, elevators, automatic doors, and human-machine interfaces come to mind. In essence, the switch projects a 3D holographic image while an LED light source and a reflected-light sensor detect the presence of an object, such as a hand, finger, pen, and so on, in the image.

This type of design eliminates the mechanical elements of a switch and thus the switch does not wear out, is easy to sanitize, and can be customized with specific messages or capabilities. McPheters explained that switches on automatic doors often go bad after a few months because people give them rough treatment. The HoloTouch switch eliminates the need to frequently replace mechanical switch.

HoloTouch doesn't yet produce switches and you can't buy an evaluation sample. Instead, the company focuses on the design of the electronics and optics. (The company has many patents on its designs.) So, McPheters aims to find a manufacturer that can produce the switches in volumes that make them an economical as well as an electrical replacement for older switches and candidates for new applications. Learn more at: www.holotouch.com. --Jon Titus