Photoelectric proximity sensor having shutter adjustment means for sensing region distance

Claim 1

A photoelectric proximity sensor for detecting presence of an object in a sensing region comprising: a housing having an internal cavity and first, second and third apertures extending through said housing communicating with said cavity; a light emitting element stationarily mounted in said cavity emitting a generally conical light beam directed through said first aperture toward said sensing region; a lighting detecting element stationarily mounted in said cavity for receiving light through said second aperture from said emitting element reflected by an object in said sensing region, said detecting element providing an electrical output signal in response to light of predetermined intensity impinging said detecting element; and adjusting means for linearly varying the distance said sensing region is spaced from said sensor in correspondence to incremental movement of said adjusting means, said adjusting means comprising a shutter disposed adjacent said first aperture within said cavity, said shutter being mounted directly on a shaft rotatably mounted in said third aperture, said shutter having a profile variably pivotally inserted into said emitted light beam by movement of said shaft to block a selectively predetermined proportion of said emitted light, thereby varying intensity of said light received by said detecting element and varying said distance, incremental movement of said shaft and shutter producing a corresponding linear variation of said distance.

Claim 6

A method of linearly adjusting the distance between a photoelectric proximity sensor and a sensing region thereof comprising: providing a sensor housing having an internal cavity and first, second and third apertures extending through said housing communicating with said cavity; fixing a light emitting element within said cavity and directing a generally conical light beam emitted from said emitting element through said first aperture toward said sensing region; fixing a light detecting element within said cavity in alignment with said second aperture and directing said detecting element for receiving light from said emitting element reflected from an object in said sensing region through said second aperture; pivotally supporting a shutter within said cavity adjacent said first aperture on a shaft rotatably mounted in said third aperture and directly connected to said shutter; providing a profile comprising first and second substantially straight edges joined at a common corner on said shutter; and rotating said shaft for pivoting said corner substantially through a center of a circular cross-section of said light beam, selectively blocking a predetermined proportion of said emitted light and thereby varying the intensity of said light received by said detecting element to linearly vary said distance in correspondence with incremental movement of said shaft and shutter.

Claim 7

A method of linearly adjusting the distance between a photoelectric proximity sensor and a sensing region thereof comprising: providing a sensor housing having an internal cavity and first, second and third apertures extending through said housing communicating with said cavity; fixing a light emitting element within said cavity and directing a generally conical light beam emitted from said emitting element through said first aperture toward said sensing region; fixing a light detecting element within said cavity in alignment with said second aperture and directing said detecting element for receiving light from said emitting element reflected from an object in said sensing region through said second aperture; pivotally supporting a shutter within said cavity adjacent said first aperture on a shaft rotatably mounted in said third aperture and directly connected to said shutter; providing a profile comprising first and second substantially straight edges joined at a common corner on said shutter; and rotating said shaft for pivoting said corner substantially through a center of a circular cross-section of said light beam, selectively blocking a predetermined proportion of said emitted light and thereby varying the intensity of said light received by said detecting element to linearly vary said distance in correspondence with incremental movement of said shaft and shutter.