Specular surface inhibit

• US 4,853,532 A
• Filed: 05/27/1988
• Issued: 08/01/1989
• Est. Priority Date: 05/27/1988
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Stauffer, Norman L.
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Allen, Stephone B.
• Application Number:
  US07/199,636
• Time in Patent Office: 431 Days
• Field of Search: 250/221, 250/222.1, 250/561, 356/1, 356/4
• US Class Current: 250/221
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A proximity detection system which detects the presence of highly specular surfaces which could produce erroneous indications for the system and suppresses them so that they will not affect the system adversely.

Claims

1. In a proximity detecting system having a beam of energy transmitted to remote objects for reflection therefrom and energy detecting means positioned to receive reflected energy so as to produce an output of magnitude dependent on the amount of energy received thereby, apparatus for determining when reflected energy is received from a highly specular object, comprising:

first means connected to receive the output and to produce a resultant signal as a function thereof, the resultant signal having a value greater than a predetermined value when a specular surface is encountered; and

second means connected to receive the resultant signal and to produce an inhibit signal when the resultant signal exceeds the predetermined value.

2. Apparatus according to claim 1 wherein the second means is a high pass filter.

3. Apparatus according to claim 1 wherein the second means is a level detector.

4. Apparatus according to claim 1 wherein energy detecting means includes first and second detectors and the first means includes a differential amplifier connected to the first and second detectors and operable to produce the resultant output in accordance with the difference therebetween.

5. Apparatus according to claim 1 wherein the first and second means are portions of a microcomputer.

6. Apparatus according to claim 3 wherein the level detector has a first input to receive the resultant signal and a second input to receive a reference signal, the level detector operating to produce the inhibit signal whenever the resultant signal exceeds the reference signal.

7. Apparatus according to claim 4 wherein the second means is a high pass filter.

8. Apparatus according to claim 4 wherein the second means is a level detector.

9. Apparatus according to claim 8 wherein the level detector has a first input to receive the resultant signal and a second input to receive a reference signal, the level detector operating to produce the inhibit signal whenever the resultant signal exceeds the reference signal.

10. Apparatus according to claim 5 wherein the first means includes a first subtract circuit to receive the outputs D₁ and D₂ of the detecting means and produce a D₁ -D₂ output, storage means to store D₁ -D₂ periodically and a second subtract circuit to subtract a present D₁ -D₂ value and a previous D₁ '"'"'-D₂ '"'"' value and produce the resultant signal S in accordance therewith.

11. Apparatus according to claim 5 wherein the first means includes a subtract circuit to receive the outputs D₁ and D₂ of the detecting means and produces an output V indicative of D₁ -D₂.

12. Apparatus according to claim 10 further including a first level check circuit to compare S with a first reference value +L1 and to produce the inhibit signal if S is greater than +L1 and a second level check circuit to compare S with a second reference value -L1 and to produce the inhibit signal if S is less than -L1.

13. Apparatus according to claim 11 further including a first level check circuit to compare V with a first reference value +R1 and to produce the inhibit signal if V is greater than +R1 and a second level check circuit to compare V with a second reference value -R1 and to produce the inhibit signal if V is less than -R1.

14. A proximity detecting system comprising:

means for projecting a beam of energy;

scanning means for directing the beam of energy to remote objects for reflection therefrom;

detecting means to receive energy reflected from the objects and to produce first and second detector signals of magnitude dependent upon the amount of radiation received thereby, the relative magnitudes of the first and second detector signals varying as a function of the proximity of the objects;

function means connected to receive the first and second detection signals and to produce an output signal in accordance therewith; and

inhibit means connected to receive the output signal and operable to produce an inhibit signal whenever the output signal exceeds a predetermined value.

15. Apparatus according to claim 14 wherein the scanning means comprises a rotating mirror.

16. Apparatus according to claim 14 wherein the function means comprises a differential amplifier.

17. Apparatus according to claim 14 wherein the inhibit means comprises a high pass filter to pass output signals whose rate of change exceeds the filter pass level.

18. Apparatus according to claim 14 wherein the inhibit means comprises a level detector having a reference input and operable to produce an inhibit signal whenever the output signal exceeds the reference signal.

19. Apparatus according to claim 14 wherein the function means and the inhibit means comprise portions of a microprocessor.