Panasonic Develops 3D Range Sensor Operable in Sunlight
Panasonic Electric Works Co Ltd developed a 3D range sensor that uses a CCD image sensor and can be used at 100,000lx, a luminance equivalent to sunlight on a bright day.
The sensor is slated for release in spring 2009. It is expected to be used for FA, distance measurement, robots, user interfaces (motion capture), security systems (to count the number of people or to detect flow lines) and other applications.
The company released a "distance image sensor" in February 2005, but it can only be used at a luminance of 3,000lx or lower, which is equivalent to a fluorescent lamp. The new sensor is free from this limitation and takes a shorter time to measure the distance.
The range sensor irradiates a signal light on the measurement target and observes the reflected light. However, when the measurement is conducted in extremely bright ambient light such as direct sunlight, the CCD sensor is saturated with only the ambient light, making it almost impossible to detect the signal light.
In the new sensor, the amount of the electric charge corresponding to that generated by the ambient light is removed from the charge generated in the photosensitive unit so that only the charge generated by the reflected light remains.
Specifically, the sensor performs the following processing. (1) It forms a separation area for the charge component with a capacity variable depending on the intensity of ambient light. (2) The charge generated by the ambient and signal light components is accumulated in a photosensitive area. (3) The accumulated charge is transferred to the separation area to separate the signal light component corresponding to a supernatant portion. (4) The ambient light component is discarded (removed).
The sensor has a resolution of 16 (horizontal) x 120 (vertical) pixels and the view angles of 50° (horizontal) and 36° (vertical). The sensor comes in two models, the standard type with a measuring range of 1.0-1.5m and a response speed of 20fps, and the high speed type with a measuring range of 0.4-1.2m and a response speed of 56fps.
The sensor outputs 11 bits of distance data and 8 bits of grayscale data. It operates on a 24V power source, and the output data is transmitted through a USB 2.0 interface. The sensor measures 150 (W) x 60 (D) x 80mm (H) and weighs 740g.