Photoelectric sensor

• US 20040089791A1
• Filed: 10/15/2003
• Published: 05/13/2004
• Est. Priority Date: 11/08/2002
• Status: Active Grant

• Current Assignee: Hosiden Corporation
• Original Assignee: Hosiden Corporation
• Inventors: Fujita, Kouji
• Granted Patent: US 7,247,834 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: G01V 8/10 Detecting, e.g. by using light barriers by reflection from the object G01S17/00

Abstract

An object of the present invention is to enable the detection of the presence/absence of an object over a plurality of detection areas without using a plurality of light-receiving devices and light-emitting devices. A sensor detects the presence/absence of an object in a detection area where a light-emitting area of a light-emitting device and a light-receiving area of a light-receiving device are overlapped with each other, and includes: a power supply unit that outputs a driving current I of the light-emitting device such that its current value is variable; a control unit that has the function of controlling the power supply unit to change in magnitude of the driving current I of the light-emitting device, and determining the presence/absence of an object based on an output from the light-receiving device to output the result of determination as a detection signal; and an output signal 50 that converts the detection signal into an analog signal to output the converted signal as a signal α.

Claims

1. A photoelectric sensor for detecting the presence/absence of an object in a detection area where a light-emitting area of a light-emitting device and a light-receiving area of a light-receiving device are overlapped with each other, the photoelectric sensor comprising:

a power supply unit that outputs a driving current of the light-emitting device such that its current value is variable; and

a control unit that controls the power supply unit in order to change in magnitude of the driving current of the light-emitting device.

2. The photoelectric sensor according to claim 1, wherein the control unit is configured to have the function of controlling the power supply unit to change in magnitude of the driving current of the light-emitting device, and determining the presence/absence of an object based on an output from the light-receiving device to output the result of determination as a digital or analog detection signal.

3. The photoelectric sensor according to claim 1 or 2, wherein the control unit is configured to have the function of repeatedly changing in magnitude of the driving current of the light-emitting device in a predetermined pattern.

4. A photoelectric sensor for detecting the presence/absence of an object in a detection area where a light-emitting area of a light-emitting device and a light-receiving area of a light-receiving device are overlapped with each other, the photoelectric sensor being configured to allow the light-emitting device to emit light, compare an output level of the light-receiving device with a plurality of reference values different from one another, and output the result of comparison as a digital or analog detection signal.

5. A photoelectric sensor for detecting the presence/absence of an object in a detection area where a light-emitting area of a light-emitting device and a light-receiving area of a light-receiving device are overlapped with each other, the photoelectoric sensor being configured to allow the light-emitting device to emit light, compare an output level of the light-receiving device with a reference value to output the result of comparison as a detection signal, change the reference value to compare the output level of the light-receiving device with the reference value in each change in the reference value, and output the result of comparison as a detection signal.

6. The photoelectric sensor according to claim 5, that is configured to have the function of repeatedly changing the reference value in a predetermined pattern.