Patent ID: 9151865
Filing Date: 2015-10-06
Classification: G01V

Abstract:
1. A reflective photo-electric sensing system comprising: a transmitter for the transmission of light; a reflector for reflecting the light, said reflector being positioned in a far field from the transmitter; a light channeling device adapted for receiving reflected light from the reflector positioned in the far field and/or adapted for receiving reflected light from a near field of the transmitter if an object formed of a light reflective material is present in a path of the light and channeling the received reflected light to a near field receiver or a far field receiver dependent on an angle of the received reflected light; said near field receiver generating an electrical signal dependent on the received reflected light and said far field receiver generating an electrical signal dependent on the received reflected light; and a controller for evaluating the electrical signal of the near field receiver and the electrical signal of the far field receiver wherein the controller is adapted to carry out foreground suppression for the near field, the controller evaluates (a) when the electrical signal of the near field receiver is greater than the electrical signal of the far field receiver and an actuation signal is generated; (b) when the difference of the electrical signal of the far field receiver minus the electrical signal of the near field receiver is positive and less than a threshold value then the actuation signal is generated; and (c) when the difference of the electrical signal of the far field receiver minus the electrical signal of the near field receiver is positive and greater than a threshold value no actuation signal is generated, the foreground suppression is performed by evaluating the ratio and/or the difference of the electrical signal of the near field receiver and the electric signal of the far field receiver.