Optical sensor arrangement for presence detection with variable pulse repetition frequency
First Claim
Patent Images
1. The method of operating an optical sensor arrangement for detecting articles present in a monitored region, said method comprising the steps of:
- emitting a plurality of light signals from a light transmitter into said monitored region, each of said light signals comprising a number of pulses, forming a pulse sequence, which follow each other at a pulse repetition frequency;
varying said pulse repetition frequency between any two successive emitted light signals;
receiving said light signals at a light receiver as received light signals;
processing said received light signals in a received signal processing stage, said received signal processing stage comprising a filter arrangement permeable to frequency components of the pulse sequence;
producing an article detection signal when said received light signals indicates the presence of an article in said monitored region.
0 Assignments
0 Petitions
Accused Products
Abstract
The invention relates to a method of operating an optical sensor arrangement for detecting articles present in a monitored region by means of a light transmitter and a light receiver. The light transmitter emits light signals which respectively comprise a number of pulses which follow each other at a determined pulse repetition frequency.
-
Citations
19 Claims
-
1. The method of operating an optical sensor arrangement for detecting articles present in a monitored region, said method comprising the steps of:
-
emitting a plurality of light signals from a light transmitter into said monitored region, each of said light signals comprising a number of pulses, forming a pulse sequence, which follow each other at a pulse repetition frequency; varying said pulse repetition frequency between any two successive emitted light signals; receiving said light signals at a light receiver as received light signals; processing said received light signals in a received signal processing stage, said received signal processing stage comprising a filter arrangement permeable to frequency components of the pulse sequence; producing an article detection signal when said received light signals indicates the presence of an article in said monitored region. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An apparatus for detecting articles present in a monitored region, said apparatus comprising:
-
an oscillator, generating an oscillation signal; a pulse repetition generator, receiving as input said oscillation signal for producing groups of pulses which follow each other at a pulse repetition frequency and for varying the pulse repetition frequency from one group of pulses to a next group of pulses; a light transmitter, receiving as input said pulses and emitting light signals comprising a group of light pulses generated in response to input pulses, with said pulse repetition frequency varying from one light signal to the next light signal; a light receiver, receiving as input said light signals and producing electrical signals; and a filter arrangement, receiving as inputs said electrical signals and said oscillation signal, and generating an output indicating the detection of articles in said monitored region; wherein; the fundamental frequency of said oscillation signal equals said pulse repetition frequency of said emitted light signals; and said filter arrangement is permeable to frequency components of pulse sequences. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
Specification