Accurately detect objects and small changes in distance to a target with the HiTechnic EOPD. The EOPD or Electro Optical Proximity Detector uses an internal light source to detect the presence of a target or determine changes in distance to a target. By generating its own light source, the EOPD is able to filter out all external light signals so as a robot moves from bright areas to dimmly lit areas or through shadows, the EOPD automatically compensates and only returns a signal based on its own light source. Targets can be accurately detected over distances up to about 8 inches (20 cm), depending on the target size, shape and reflective qualities.

The HiTechnic EOPD Sensor is an Electro-Optical Proximity Detector. Electro-Optical? This means an electronic device which uses visible light as part of its operation.

The HiTechnic EOPD is similar to a standard light sensor except that it uses pulsed light to effectively eliminate the interference of ambient or background light from the reading. By using pulsed light, the brightness during the pulse can be relatively bright but remain safe because the average power output is very low. The sensor reads the difference between the light measurement at the detector before the pulse is emitted and the light measurement during the pulse. It then subtracts the difference so the reading is a direct measurement of the reflected light energy after removing any dependence on ambient light.

The EOPD sensor has two modes of operation, x1 sensitivity and x4 sensitivity. In x4 sensitivity mode, the HiTechnic EOPD can easily detect the red ball which comes with the LEGO MINDSTORMS NXT set at a range of at least 15 cm (approx. 6 inches). Since the sensor can be overloaded by close white targets, the x1 sensitivity mode can be used for detecting the position of LEGO pieces, such as a small white part attached to a black beam, used as a mechanism home detection device.

The HiTechnic EOPD can be read at up to 300 samples per second. Internally, the EOPD sensor actually runs at between 350 to 400 samples per second to ensure there is always a new reading for the NXT at 300 samples per second.

Each HiTechnic EOPD runs at a slightly different sampling rate which means they can be used near each other with a minimized chance of interference

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HiTechnic NXT Color Sensor Version 2 for LEGO MINDSTORMS NXThttp://s9/middle/7bad485fgc050ad001c38&690four sensor for light 如何区别四种不同的光传感器 9844 9694 EOPD COLOR V2" TITLE="lego four sensor for light 如何区别四种不同的光传感器 9844 9694 EOPD COLOR V2" />

The new and totally redesigned HiTechnic Color Sensor Version 2 (V2) operates by using a single white LED (light emitting diode) to illuminate the target and analyses the color components of the light reflected by the target's surface and calculates a Color Number that is returned to the NXT program.

The Color Sensor V2 works best when it is positioned so that it is not too close to the surface being tested. The picture on the right should be used as a guide for proper distance and angle to the surface. The angle prevents the direct reflection of the light from the LED from coming back into the sensor element, which can prevent proper color determination.

The Color Sensor is housed in a standard MINDSTORMS sensor housing to match the other MINDSTORMS elements and connects to an NXT sensor port using a standard NXT wire and digital I2C communications protocol. The Color Number calculated by the sensor is refreshed approximately 100 times per second.

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review:

四种感应器功能部分重叠，而侧重功能又不同，有时候真为需要用哪个传感器而头痛。

9844是9797套餐自带：主要检测环境光强度，检测颜色，红外发光可以通过选项开关；

9694是8547套餐自带：感应光源，能区别6色，并还可以做为灯泡显示红、绿、蓝光；

EOPD电子式光学距离感应器：微小物体测距，能通过自身光源过滤外部红外线干扰。

Color v2颜色传感器：检测多种程序，对各种颜色产生反应。