Claims
- 1. An optical sensor arrangement comprising:
- an optical sensor that operates by modulating a characteristic of light in relation to a physical parameter;
- a pair of devices that each functions in a first operating mode as a light source for the sensor, and in a second operating mode as a light detector for the sensor when the other device operates as a light source; and
- means for optically coupling said devices to the sensor.
- 2. The optical sensor arrangement according to claim 1 wherein each of said devices comprises a single LED that emits light at a wavelength that each LED can also respond to as a detector.
- 3. The optical sensor arrangement according to claim 2 wherein light transmitted between said devices travels bi-directionally along a non-reciprocal optical path so that the sensor can be interrogated to produce self-referenced outputs.
- 4. The optical sensor arrangement according to claim 2 wherein said LED devices are used to interrogate the sensor in a bi-directional manner such that light alternately travels along the optical path from one LED through the sensor to the other LED and then alternately light travels along the optical path in an opposite direction from said other LED through the sensor to said one LED so that both LFA) devices operate as a light source and a light detector in a mutually exclusive manner.
- 5. The optical sensor arrangement according to claim 1 further comprising feedback means for controlling output intensity of said devices.
- 6. The optical sensor arrangement according to claim 5 wherein said feedback means comprises a photoelectric detector that receives a portion of light emitted by said devices and produces an output that is used to control output intensity of said devices.
- 7. The optical sensor arrangement according to claim 6 where said feedback means controls the output intensity of a plurality of LED devices, each device being used as a light source and detector for the sensor.
- 8. The optical sensor arrangement of claim 1 wherein when one device is operating in a first mode as a light source for the sensor the other device is operating only in the second mode as a light detector.
Parent Case Info
This is a continuation of application Ser. No. 07/900,879, filed Jun. 18, 1992, which issued as U.S. Pat. No. 5,334,831, on Aug. 2, 1994, which is a continuation of application Ser. No. 07/709,627, filed Jun. 3, 1991, which issued as U.S. Pat. No. 5,149,962, on Sep. 22, 1992.
US Referenced Citations (25)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0050912 |
Feb 1989 |
JPX |
Non-Patent Literature Citations (3)
Entry |
Maurice et al. "Low Cost Binary Proximity Sensor for Automotive Applications"; SPIE vol. 1173 pp. 75-83 (1989). |
Nagao, "Light Applied Measuring Apparatus"; Published Japanese Patent Application No. 62-90547(A) (Apr. 1987). |
Tokumaru, "Light Application Measuring Instrument"; Published Japanese Patent Application No. 62-76474(A) (Apr. 1987). |
Continuations (2)
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Number |
Date |
Country |
Parent |
900879 |
Jun 1992 |
|
Parent |
709627 |
Jun 1991 |
|