What is the minimum object size that can be sensed for light convergent reflective type Optical Sensor B5W-LB series?

ID: FAQE40039E



Ideally, the size of the actual object to be sensed must be bigger than the emitter’s lighting spot of the light convergent reflective type Optical Sensor in order to utilize as much light as possible.


Since the light convergent reflective type sensor B5W-LB series carries an infrared LED, the light spot is invisible. However, the size of the spot can be checked according to “Spot diameter – distance characteristics.” The sensing area of the sensor is determined not only by the area where the LED is emitting light but also by the combination with the area the light receiving element is viewing (see the figure below). It can be checked according to “Operating range” of the datasheet. The curve on the graph represents the position where the sensing object moves in the direction of the arrow and the sensor output turns ON.

Spot diameter - distance characteristics
Sensing area
B5W-LB2□: Operating range (Up and Down)
B5W-LB2□: Operating range (Left and Right)

For stable detection of objects, it is important that the amount of light the sensor receives is sufficient. If the sensing objects are small, it is recommended to select an analog output model and design the equipment so that the sensing objects should be within a distance range with a high light-receiving output margin by referring to “Receiver output – sensing distance characteristics” in the datasheet. Make sure that the amount of receiving light (output voltage) on the actual equipment is sufficient, and set the optimum threshold.

B5W-LB2112/2122: Receiver output - sensing distance characteristics

Quick tips

Reading the sensing area of the sensor from the graph of “Operating range” can be applied to the following.
If there is a background object (that you do not want to detect) in the sensing area of the sensor, such as the frame of the equipment, check the sensing area at that distance, and perform structural design such as drilling on the background object to increase the detection margin for stable detection. The evaluation must be done using the actual equipment.

Product category Sensors Light Convergent Reflective Sensors/Diffuse Reflective Sensors
Classification Usage, Applications
Related keywords
  • Optical Sensor
  • Light Convergent Reflective Sensor
  • Sensing Object
  • Objects Size
  • B5W-LB

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