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Comparison of Sensor Characteristics

Active Infrared Sensor Microwave Sensor Characteristics Advantages Not affected by temperature change Stationary detection possible Not affected by changes in the floor area. The detection area does not change due to the color or temperature of the detection object. Disadvantages Detection possible only when there is a difference in the amount of reflected light between the floor surface and the object Stationary detection impossible The area is not well defined. Functions Stationary detection Possible Not possible. Mutual interference May be solved with a changeover switch. Although interference is possible in principle, malfunction does not occur. Detection of carts Possible. A constant amount of reflected light is required. Detection is made normally. Environmental factors Rain, wind and snow Snow and rain detected. A microcomputer may be employed as a filter. Snowstorms can also be detected. When the detection glass is wet, beam diffusion may cause malfunction. Cancelled out by computer. Malfunction may nevertheless occur when the cover is wet. Mist, smoke and steam Can be detected. Detection is made normally. Water pools Pools of water in the detection area can be detected. Does not malfunction.. Reflective objects such as mats, hard aluminum and textured paving blocks Deflection off the transom or vibration transfer may cause malfunction. Malfunction may occur if fluorescent light is reflected off a hard metal surface and enters the sensor.. Temperature change No problem. Does not malfunction. Insects and small animals May be detected. A microcomputer may be employed to filter out. Detection is made normally. Optical noise from fluorescent and strobe lights May cause malfunction. Microcomputers do not filter these factors out. Care should be taken with new products. May malfunction with fluorescent light. Noise of radio wave More resistant Weaker than light rays. Products using infrared rays Interference may result. Care should be taken when the detection glass is black and the detection area is near the door. Does not malfunction.

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