Differential clear container sensor with improved noise immunity
First Claim
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1. An optical sensor system for detecting the passage of target objects on a conveyor comprising:
- (a) first and second light detectors spaced apart in the direction of conveyor movement for detecting light that has traveled across the conveyor and for emitting signals indicative of the amount of light detected;
(b) at least one light source for passing detectable light across said conveyor, said light source and said detectors being located on a first side of said conveyor;
(c) a reflector located on an opposite side of the conveyor from said light source for returning the light to said detectors; and
(d) a processing unit for receiving and comparing said signals and determining their difference to thereby determine the passage of the target object.
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Abstract
A photoelectric sensing unit, especially useful for determining the passage of clear bottles or other low contrast targets on a conveyor, contains two sensors and a signal processing unit to determine the signal differential. The signal differential is compared to a selected value and sensor output is enabled or disabled. High noise immunity, resistance to target reflection, and output reliability result. The unit may correct the selected value to account for environmental change and/or unit component performance. The unit can also figure the speed of passage of the bottles.
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Citations
14 Claims
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1. An optical sensor system for detecting the passage of target objects on a conveyor comprising:
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(a) first and second light detectors spaced apart in the direction of conveyor movement for detecting light that has traveled across the conveyor and for emitting signals indicative of the amount of light detected; (b) at least one light source for passing detectable light across said conveyor, said light source and said detectors being located on a first side of said conveyor; (c) a reflector located on an opposite side of the conveyor from said light source for returning the light to said detectors; and (d) a processing unit for receiving and comparing said signals and determining their difference to thereby determine the passage of the target object. - View Dependent Claims (2, 3, 4, 5)
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6. An optical sensor system for detecting the passage of light transmissive objects on a conveyor comprising:
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a light emitter positionable on a first side of said conveyor for emitting light substantially perpendicular to direction of said conveyor travel; a reflector positionable on a second side of said conveyor for returning light towards emitter; the emitter and reflector spaced at a distance to let the objects pass therebetween; a first sensor and a second sensor placed on the first conveyor side, the first sensor being upstream respective to conveyor travel, for detecting light returned from said reflector and outputting a signal based on the amount of light received therefrom; a signal processing unit for accepting signals from the first and second sensors, comparing the signal difference and determining the passage of a target object based upon said difference. - View Dependent Claims (7, 8, 9, 10)
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11. A method of detecting the passage of a light transmissive object on a conveyor comprising:
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emitting light across the direction of movement of the conveyor; moving the object through the emitted light;
simultaneously detecting the emitted light at first and second locations spaced along the direction of movement of the conveyor and determining the amount of light received at said first and second locations;comparing the difference in said amount of light received at said first and second locations to a constant value; and outputting a signal indicative of said object passage based on said comparing. - View Dependent Claims (12, 13, 14)
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Specification