What is the procedure when the light convergent reflective type Optical Sensor B5W-LB series is influenced by external disturbing light interference?
The digital output type of B5W-LB contains a special circuit that minimizes the influence of disturbing lights. However, we recommend implementing a mechanical design that prevents any external disturbing light from penetrating into the light receiving surface of the sensor.
If the sensing surface of the light convergent reflective type Optical Sensor B5W-LB series must be exposed to ambient light, please mount the sensor or design the equipment structure so that the external light should not enter the light receiver. Select an analog output model and check the sensor output voltage for the influence of the external light.
If the external light is sunlight or incandescent lamp, try the analog output model to cancel the effect of the external light. First, the light emitting device (LED) of the sensor emits a pulse. In this case, the sensor output when the LED is off can be regarded as the amount of receiving light due to external light (see the figure below). By offsetting this, the effect of external light can be canceled. However, it may not be possible to cancel the external light depending on its intensity, and it is necessary to evaluate sufficiently with actual equipment. For details, see B5W-LB: User’s Manual, 6. Usage guidance (external circuit).
When designing the equipment structure so that external light does not enter the sensor’s light receiving path, consider indirect light from disturbing light as well. Indirect light is light that is reflected by other objects and indirectly enters the sensor. In particular, if the object has a glossy surface, the intensity level of indirect light may be comparable to that of direct light. If the object is part of the equipment, try to reduce the amount of indirect light received by the sensor as much as possible by changing the angle of the object’s surface, changing its surface to a low-reflectivity one, or applying a low-reflectivity sheet.
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