Object presence detection method and system having quick object departure detection to turn off system

• US 5,656,995 A
• Filed: 04/29/1994
• Issued: 08/12/1997
• Est. Priority Date: 04/29/1994
• Status: Expired due to Fees

• Current Assignee: Smiths Industries Aerospace & Defense Systems Incorporated
• Original Assignee: Hampton Electronics, Inc.
• Inventors: Peters, Wayne J.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US08/235,478
• Time in Patent Office: 1,201 Days
• Field of Search: 340/567, 340/565, 340/528, 340/541, 340/309.15, 250/342, 250/DIG. 1, 377/6, 315/307
• US Class Current: 340/541
• CPC Class Codes: G08B 13/19 using infrared-radiation detection systems G08B13/194 takes precedence

Abstract

The invention is directed to a detection system for detecting object presence in a detection zone and always detecting object departure from the detection zone so as to provide an object presence detection zone output signal indicative of zone occupancy. The system is comprised of a main system control unit mutually responsive to both an object presence signal from the zone and an object departure signal form the zone to provide the object presence detection zone output signal "ON". The object presence detection zone output signal remaining "ON" for a preset time period, which preset time period is retriggered "ON" as long as presence of an object in the zone is detected. The object departure signal causes a discrete moment of departure time delay signal that causes the object presence detection zone output signal to mm "OFF" when no object presence is detected in the zone during the discrete moment of departure time delay. The main system control unit is further responsive to the triggering/retriggering of the preset time period "ON" and the time delay moment of departure to ensure that the object presence detection zone output signal is "ON" during the triggering/retriggering and the discrete moment of departure time delay and is turned "OFF" just after the discrete moment in time and object departs the zone and no object has been detected in the zone.

Claims

1. A detection system for detecting object presence in a detection zone and for quickly detecting object departure from said detection zone so as to provide an object presence detection zone output signal indicative of zone occupancy, said system comprising:

an object presence detection means to provide an object presence signal when an object is detected in said zone;

an object departure detection means to provide an object departure signal when an object is detected departing said zone;

a main control means that is responsive to said object presence signal from said detection zone and said object departure signal provided from said zone, said object presence signal causing said object presence detection zone output signal to turn "ON" and remain "ON" for a preset time period which object detection zone output "ON" signal is maintained "ON" for as long as object presence is detected in said zone, and said object departure signal causing said object presence detection zone output signal to "OFF" a moment in time after an object departs said zone if no object has been detected in said zone during said moment in time, said moment in time always being shorter than said preset time period.

2. A detection system for detecting object presence in a detection zone and quickly detecting object departure from said detection zone so as to provide an object presence detection zone output signal indicative of zone occupancy, said system comprising:

an object presence detection means to provide an object presence signal when an object is detected in said zone;

an object departure detection means to provide an object departure signal when an object is detected departing said zone;

a main system control means that is responsive to both said object presence signal from said zone and said object departure signal from said zone to turn "ON" and "OFF" the object presence detection zone output signal,

said object presence signal acts to trigger said object presence detection zone output signal "ON", said object presence detection zone output signal remaining "ON" for a preset period of time and maintained "ON" as long as a presence of an object in said zone is detected,

said object departure signal causes a moment of departure time delay signal which interrupts said object presence detection zone output "ON" signal and causes said object presence detection zone output signal to turn "OFF" when no object presence is detected in said zone during said moment of departure time delay,

said main system control means further being responsive to said object presence detection zone output "ON" signal and said moment of departure time delay signal to ensure that said object presence detection zone output signal is "ON" during detection of objects in said zone and during said moment of departure time delay, and is turned "OFF" a moment in time after an object departs said zone if no object has been detected in said zone during said moment in time.

3. A detection system of claim 2 wherein said responsive means includes a long time delay means and moment of departure delay means responsively coupled to receive said object presence signal,

a zone departure initiating means responsively coupled to said object departure signal to thereby provide a departure indicating signal to said long time delay means and said moment of departure delay means to thereby establish said object presence detection zone output signal which is "ON" for a preset time period and said moment of departure time delay signal.

4. The detection system of claim 3 wherein said object presence detection zone output signal preset time period is always of a longer duration in time than said moment of departure time delay signal.

5. A detection system for detecting object presence in a detection zone and quickly detecting object departure from said detection zone to provide an object presence detection zone output signal indicative of zone occupancy, said system comprising:

a main system control means that is responsive to both an object presence signal from said detection zone and an object departure signal from said zone to provide said object presence detection zone output signal, said responsive means providing;

a preset time period "ON" signal, and

a moment of departure time delay signal,

said object presence signal initiating said preset time period "ON" signal, said preset time period "ON" signal causing an object presence detection zone output signal to turn "ON" and remain "ON" as long as presence of an object in said zone is detected,

said object departure signal causing said moment of departure time delay signal which is representative of object departure from said zone, said moment of departure time delay signal interrupts said object presence detection zone output "ON" signal when no object presence is detected in said zone during moment of departure time delay,

said main system control means further including holding means responsive to said preset time period "ON" signal and said moment of departure time delay signal to deliver a zone unoccupied signal to said responsive means to ensure that said object presence detection zone output signal is "ON" during detection of objects in said zone and during said moment of departure time delay and said object presence detection zone output signal is reset "OFF" a moment in time after an object departs said zone if no object has been detected in said zone during said moment in time.

6. The detection system of claim 5 wherein said preset time period signal is always of a longer duration in time than said moment of departure time delay signal.

7. A method of detecting object presence in a detection zone and for quickly detecting object departure from said detection zone to provide an object presence detection zone output signal which is "ON" to indicate the presence of an object in said zone and turns "OFF" an instant in time following a moment of departure of said object from said zone when no object is detected in said detection zone during said moment of departure, said method comprising the steps of;

(a) detecting the presence of an object in said detection zone to set "ON" said object presence detection zone output signal for a preset time period,

(b) maintaining said preset time period object presence detection zone output signal as long as object presence is detected in said zone,

(c) detecting object departure from said detection zone, and

(d) resetting to "OFF" said object presence detection zone output signal at an instant point in time just after a moment in time an object has been detected departing said detection zone and no object has been detected in said zone during said moment in time.

8. The method of claim 7 wherein said moment in time is always shorter in time than said preset time period.