Sharp's New Sensor Detects Gestures, Illuminance, Proximity (page 2)

Jun 24, 2013
Satoshi Okubo, Nikkei Electronics

According to Sharp, there is another company's product that contains gesture and proximity detection functions in one package. It is possible to realize the same function as that of the new sensor by combining this product and an illuminance sensor, but, in this case, footprint increases, the company said.

"The new sensor can reduce package area by more than 30%," Sharp said.

Color of light source can be determined with illuminance sensor

The illuminance sensor contained in the new proximity sensor detects brightness by separating surrounding light into red (R), green (G) and blue (B) colors. Therefore, it can be used for determining if it is daytime or evening under sunlight and as well as for distinguishing between, for example, daylight color and incandescent color under artificial light such as of lighting apparatus.

"When an image on a display is seen in a bright outdoor environment, the blue and green colors of the image look darkish to human eyes," Sharp said. "On the other hand, under the light of an incandescent lamp, it is difficult to see red and yellow colors."

"With the new sensor, it is possible to realizes a display that emphasizes the blue and green colors of an image in a bright outdoor environment and the red and yellow colors under the light of a light bulb," the company said.

To detect RGB colors, the illuminance sensing part of the new sensor is made by covering photo diodes with RGB filters. Sharp made use of the technologies developed for its image sensors.

For the detection of gestures and proximity, Sharp used infrared LEDs and light-receiving elements. When the infrared light emitted from the LEDs is reflected on an object and enters the light-receiving elements, the sensor detects the movements (gestures) of the object based on the time variations of the illuminated and non-illuminated areas in the light-receiving elements. Proximity can be determined from the intensity of infrared light received by the light-receiving elements.