U.S. patent number RE32,828 [Application Number 06/502,649] was granted by the patent office on 1989-01-10 for passive infrared intrusion detection system.
This patent grant is currently assigned to Cerberus A.G.. Invention is credited to Philip H. Mudge.
United States Patent |
RE32,828 |
Mudge |
January 10, 1989 |
**Please see images for:
( Certificate of Correction ) ** |
Passive infrared intrusion detection system
Abstract
The invention comprises a passive infrared intrusion detector
including a lamp for locating the zones being protected by the
detector. The detector includes a heat sensor, a lens system for
receiving and focusing the body heat of an intruder on the heat
sensor, and electrical circuitry responsive to the heat sensor for
actuating an alarm or detection signal when the body heat of an
intruder is detected. The zone locator lamp is positioned near the
heat sensor and its light passes through a lens in the general
direction of a zone to be protected. The light parallels a portion
of radiation which is focused on the heat sensor by another lens.
If the light can be observed from a given position in front of the
detector, that position is in a zone being observed by the detector
and body heat radiated from that zone will be focused on the heat
sensor. Thus, zones protected by the intrusion detector can be
established by adjusting the position of the detector until light
from the zone locator lamp is observed. Once these zones are
established, the lamp may be disconnected and the intrusion
detector placed in the "ready" or "stand by" mode.
Inventors: |
Mudge; Philip H. (New
Fairfield, CT) |
Assignee: |
Cerberus A.G.
(CH)
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Family
ID: |
26787548 |
Appl.
No.: |
06/502,649 |
Filed: |
June 9, 1983 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
93443 |
Nov 13, 1979 |
04275303 |
Jun 23, 1981 |
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Current U.S.
Class: |
250/342; 250/353;
250/DIG.1 |
Current CPC
Class: |
G08B
13/193 (20130101) |
Current International
Class: |
G08B
13/193 (20060101); G08B 13/189 (20060101); G01J
001/00 () |
Field of
Search: |
;250/221,234,330,340,341,342,353 ;340/567 ;378/206 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1262833 |
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Mar 1968 |
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DE |
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1547451 |
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Nov 1969 |
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DE |
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7515814 |
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Sep 1975 |
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DE |
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2836462 |
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Mar 1980 |
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DE |
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Other References
Projektierung und Installation, Jun. 1977, Heft 1. .
Inbertriebsetzung und Unterhalt, Sep., 1977, Heft 2. .
"Infrared Heat Radiation: A New Principle of Intruder Detection",
in Cerberus, Apr. 1976, publication of Cerberus A.G.,
Mannedorf/Switzerland. .
Cerberus data sheet, Dec. 1978, Typ IR21, No. Ye3/294 719/1(1) p.
9..
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Primary Examiner: Howell; Janice A.
Attorney, Agent or Firm: Brumbaugh, Graves, Donohue &
Raymond
Claims
What is claimed is:
1. In a passive infrared intrusion detector of the type including a
heat sensor for detecting a change in temperature caused by a
passing intruder, a lens mounted in front of said heat sensor for
receiving infrared radiation from the body of said intruder and
focusing said radiation on said heat sensor, and means coupled to
said heat sensor for actuating a signal when said heat sensor
detects said temperature change,
the improvement comprising:
a lamp for emitting visible light positioned within said intrusion
detector proximate to said heat sensor,
said lens including a first lens segment positioned to receive
infrared radiation from a first zone to be protected and focus a
portion of said radiation on said heat sensor, and a second lens
segment positioned to receive radiation from a second zone to be
protected and focus a portion of said radiation on said heat
sensor,
said second lens segment being positioned relative to said lamp and
said heat sensor such that light from said lamp passes through said
second lens segment and parallels that portion of radiation from
said first zone which is focused on said heat sensor by said first
lens segment,
wherein said first zone may be located by adjusting said intrusion
detector so that light from said lamp is observed in said first
zone.
2. An intrusion detector as claimed in claim 1 wherein the top edge
of said second lens segment is integrally joined to the bottom edge
of said first lens segment.
3. An intrusion detector as claimed in claim 1 wherein said first
and second lens segments are subdivided into a number of
corresponding sections, each having a different field of view.
4. An intrusion detector as claimed in claim 1 wherein said first
and second lens segments are collimating lenses.
5. An intrusion detector as claimed in claim 1 including means
operatively associated with said lamp for deenergizing said lamp
after said first zone has been located.
6. An intrusion detector as claimed in claim 1 further including
means for movably mounting said lens relative to said heat sensor
and said lamp.
7. An intrusion detector as claimed in claim 1 wherein said lamp is
a light emitting diode (LED).
8. A method of locating zones protected by a passive intrusion
detector of the type including a sensor for detecting infrared
radiation from the body of an intruder, a lens for focusing said
radiation of said sensor, and means coupled to said sensor for
actuating a signal when the body heat of an intruder is sensed,
comprising:
providing a first lens segment for receiving infrared radiation
from a first zone to be protected and focusing a portion of said
radiation on said sensor,
providing a second lens segment for receiving infrared radiation
from a second zone to be protected and focusing a portion of said
radiation on said sensor,
providing a lamp which emits visible light,
positioning said lamp relative to said sensor and said second lens
segment such that light emitted from said lamp passes through said
second lens segment and parallels that portion of radiation from
said first zone which is focused on the sensor by said first lens
segment,
selecting a first zone to be protected, and
adjusting said intrusion detector so that light from said lamp is
visible in said first zone through said second lens segment.
9. The method of claim 8 further including the step of:
deenergizing said lamp after said zone is located.
10. The method of claim 8 wherein said lamp is a light emitting
diode (LED). .Iadd.
11. In a passive infrared intrusion detector of the type including
an infrared sensing element, responsive to infrared radiation
emanating from within at least one zone comprising an angular
region of space desired to be protected and including means coupled
to said sensing element for actuating a signal in response to
changes in said infrared radiation within said zone, the
improvement comprising: a lamp for emitting visible light and means
for focusing said visible light to be emitted from said infrared
intrusion detector into said angular region of space, said light
being emitted in a direction generally parallel to the direction of
radiation from said zone to said sensing element such that the
boundaries of said zone are defined by the location of said
detector and the angular region of space in which said light is
visually observable. .Iaddend. .Iadd.12. An intrusion detector
according to claim 11 wherein said focusing means comprises a lens.
.Iaddend. .Iadd.13. An intrusion detector according to claim 12
wherein said lens has a first lens segment for focusing infrared
radiation emanating from said zone onto said sensing element and a
second lens segment for focusing light from said lamp into said
zone. .Iaddend. .Iadd.14. An intrusion detector according to claim
13 wherein said second lens segment is arranged to focus infrared
radiation
from a second zone onto said sensing element. .Iaddend. .Iadd.15.
An intrusion detector according to claim 13 wherein the top edge of
said second lens segment is integrally joined to the bottom edge of
said first lens segment. .Iaddend. .Iadd.16. An intrusion detector
according to claim 13 wherein said first and second lens segments
are subdivided into a number of corresponding sections, each having
a different field of view. .Iaddend. .Iadd.17. An intrusion
detector according to claim 12 wherein said lens is a collimating
lens. .Iaddend. .Iadd.18. An intrusion detector according to claim
13 wherein said first and second lens segments are collimating
lenses. .Iaddend. .Iadd.19. An intrusion detector according to
claim 11 including means operatively associated with said lamp for
selectively deenergizing said lamp. .Iaddend. .Iadd.20. An
intrusion detector according to claim 12 further including means
for moveably mounting said lens relative to said sensing element
and said lamp. .Iaddend. .Iadd.21. An intrusion detector according
to claim 13 further including means for moveably mounting said lens
relative to said sensing element and said lamp. .Iaddend. .Iadd.22.
An intrusion detector according to claim 11 wherein said lamp is a
light emitting diode (LED). .Iaddend.
.Iadd.23. A method of locating a first zone which comprises an
angular region of space to be protected by a passive infrared
intrusion detector of the type including an infrared sensing
element arranged to receive infrared radiation emanating within
said zone, and including means coupled to said sensing element for
actuating a signal in response to changes in said infrared
radiation within said zone comprising: providing said detector with
a lamp arranged to emit visible light and means for focusing
visible light from said lamp into said zone, said light being
emitted in a direction generally parallel to the direction of
radiation emanating from said zone to said sensing element;
selecting a desired zone to be protected; and adjusting said
detector so that light from said lamp is visually observable within
said desired zone. .Iaddend. .Iadd.24. The method according to
claim 23 wherein the lamp is deenergized after said step of
adjusting. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a passive infrared intrusion
detector. This type of detector includes a heat sensor, a lens for
focusing heat energy on the heat sensor, and means operatively
associated with the heat sensor for providing a detection signal
when the heat sensor detects a sudden change of temperature, as for
example, caused by the body heat of a passing intruder. One common
example of a type of passive infrared intrusion detector
incorporates a pyroelectric detector as the heat sensor.
One problem with known passive infrared intrusion detectors is that
it is difficult to establish specific zones to be observed and
protected by the detector before the detector is put into
operation. It is imperative that the zones to be protected be
directed away from any potential source of false alarms. Any
surface or object which can change temperature rather rapidly is a
source of false alarms. These sources include grills on heater
ducts, light bulbs, air conditioners, and the like.
In the past, trial and error techniques have been used to focus
infrared intrusion detectors away from sources of false alarms. For
example, a source of heat (as for example a human body) was moved
about in the zone desired to be protected while the intrusion
detector was adjusted. The generation of an alarm signal indicated
that the intrusion detector was focused on the desired zone to be
protected. Such trial and error techniques were obviously time
consuming and cumbersome.
It is an object of the present invention to provide a method and
apparatus which utilizes a lamp which emits visible light to locate
and establish zones to be protected by the detector before the
intrusion detector is put into operation.
SUMMARY OF THE INVENTION
The present invention provides an improved passive infrared
intrusion detector and a method of locating and establishing zones
to be protected before the alarm is placed in operation. The
intrusion detector is of the type including a heat sensor, a lens
positioned to focus heat on the heat sensor, and means operatively
associated with the heat sensor for actuating a detection signal or
alarm in response to a sudden change of temperature detected by the
heat sensor. Such sudden change in temperature can be caused by
heat radiated from the body of a passing intruder.
A lamp which emits visible light is positioned within the detector
near the heat sensor. Light from the lamp passes through the lens
in the general direction of the zones to be protected by the
detector. The light from the lamp parallels the portion of heat
radiated from the zone to be protected which will be focused on the
heat sensor. The detector is adjusted until an observer in front of
the lens can see the light from the lamp. The observer is then
standing in a zone which is being observed by the detector.
Accordingly, at least a portion of the body heat radiated from a
person in that zone will impinge upon the lens and be focused on
the heat sensor. Thus, when the detector is in its operational
mode, an intruder passing through the established zone of
protection will actuate the detector which will generate a
detection or alarm signal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the new passive infrared intrusion
detector with a cover mounted thereon.
FIG. 2 is a front elevational view of the intrusion detector with
its cover partially broken away to show its lens and power supply
unit. The details of the electronic circuitry have been
omitted.
FIG. 3 is the intrusion detector of FIG. 2 with the lens removed to
show a heat sensor and a zone locator lamp positioned behind the
lens.
FIG. 4 is a block diagram of the electronic circuitry used in one
type of passive infrared intrusion detector.
FIG. 5 is a perspective view of a lens used in connection with the
intrusion detector.
FIG. 6 is a schematic view of the intrusion detector showing light
emitted from the zone locator lamp travelling through the lens and
heat radiation from zones to be protected impinging upon the lens
and being focused on a heat sensor.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGS 1 through 6 of the drawings illustrate a preferred embodiment
of an improved passive infrared intrusion detector. Such detectors
are generally known to the art and include a heat sensor, a lens
for focusing heat on the heat sensor, and means responsive to the
heat sensor for generating a detection or alarm signal when the
heat sensor senses a sudden change in temperature, such as a change
caused by the body heat of a passing intruder.
A common type of passive infrared intrusion detector well-known to
the art incorporates a pyroelectric heat sensor. Briefly stated,
such as an alarm includes a pyroelectric element (as for example
the Pyroelectric IR Detector Model 406, sold by Eltec Instruments,
Inc.) which generates an electric current proportional to the rate
of change of temperature detected.
It should be noted that although the apparatus and method disclosed
herein employ pyroelectric heat sensors, they are also applicable
to passive infrared intrusion systems using other types of heat
sensors. Accordingly, although pyroelectric intrusion detectors
will be referred to in the description herein, this is intended to
be illustrative only and not restrictive of the users of the
disclosed improved detection system.
FIG. 1 of the drawings illustrates a passive infrared intrusion
detector 2 as it would appear when mounted. The detector includes a
housing 4 having a grill 6 removably mounted to the front of the
housing. The housing is tapered towards its rear wall 8. Means (not
shown) are provided on the rear wall of the housing for mounting
purposes. For example, the rear wall 8 can be mounted to a wall so
that the grill 6 will face an area to be protected by the
detector.
FIG. 2 is a front view of the detector of FIG. 1 with the grill 6
removed. A Fresnel lens 10, which is positioned behind the grill 6,
has a border 12 which is mounted to a frame 24 (shown in FIG. 3).
The lens includes an upper section 14 which is also referred to as
the far field lens, and a lower section 16, which is also referred
to as the near field lens. Both the upper and lower lens sections
are subdivided into a plurality of panels 14a and 16a,
respectively, as is more clearly shown in FIG. 5. Also, both the
upper and lower lens sections can be collimating lenses. The lens
border 12 is mounted to the frame 24 by screws 22. Batteries 18 are
held in position to one side of the lens 10 by clamps 20 mounted
within the housing.
FIG. 3 is a front view of the intrusion detector of FIGS. 1 and 2
with the lens 10 removed from the frame 24. As is clear from this
drawing, frame 24 forms the border of the open front of a pyramidal
inner housing 26 which is positioned within the larger housing
4.
The sidewalls 28, 30, 32 and 34 of the inner housing 26 converge
rearwardly on a rear wall 36. This rear wall is mounted to the
front surface of rear wall 8 of the larger housing 4, and means are
provided for pivotally mounting the inner housing 26 to the rear
wall 36. Accordingly, the lens 10 is movable relative to the rear
wall 36 of the inner housing 26.
A heat sensor 38 and a lamp 40 for emitting visible light are
mounted to the front surface of the rear wall 36. Both the heat
sensor and the lamp are positioned so they are facing towards the
front of the larger housing 4. The lamp 40 is positioned near the
heat sensor 38. Both the heat sensor and the lamp are located
behind lens 10 when the lens is mounted to the inner housing
26.
In the preferred embodiment of the invention, the lamp 40 is a
light emitting diode (LED) and means are provided to selectively
electrically actuate the LED. However, as will become apparent, any
source capable of emitting visible light can be used as the lamp
40. As will also be discussed in detail below, the lamp 40 enables
the user of the intrusion detector to locate and establish the
protection zones to be observed by the detector before the detector
is actually placed in operation.
FIG. 4 is a very simple block diagram of the electrical circuitry
of the passive intrusion detector. The heat sensor 38 can be, for
example, a pyroelectric element such as the previously mentioned
Eltec Model 406. Other types of heat sensors, which are known to
the art, can also be used. Examples of specific electronic
circuitry for passive infrared intrusion alarms are illustrated in
U.S. Pat. Nos. 3,928,843; 3,839,640; and 3,703,718.
In the diagram of FIG. 4, a power supply 42 can be electrically
coupled by the switch 43 to either the relay 44 or the lamp 40.
When the power supply is coupled to the lamp 40, no power is
provided to the relay which will cause the relay to deenergize or,
in effect, go into the alarm mode and transmit a detection signal
to an alarm control panel. The alarm control panel includes switch
means for inhibiting the generation of a signal to an associated
alarm (not shown). Accordingly, the lamp 40 can be actuated and
used to adjust the intrusion detector, as will be described below,
without causing an actual alarm signal during the adjustment
operation. Once the intrusion detector is adjusted, and the cover
replaced, switch 43 is moved so that the lamp will be turned off
and power will be provided to the relay 44. The relay becomes
energized as it is now receiving power from the power supply
42.
Heat sensor 38 is electronically coupled to the relay 44 through
amplifiers 38, 41 and signal comparator 45. When an intruder is
detected by the heat sensor, the relay 44 is deactivated by the
heat sensor and sends a detection signal to the alarm control
panel. As noted before, the alarm control panel includes means for
inhibiting the alarm signal even though a detection signal is
provided by the relay. This feature is useful during adjustment of
the detector as mentioned above, and when it is not desired to
generate an intrusion alarm signal as, for example, during business
hours when the detector is mounted in business premises. Neither
the alarm control panel nor the alarm form part of the intrusion
detector. The intrusion detector may also include a tamper switch
which will deenergize relay 44 if the grill 6 is removed from the
intrusion detector.
Operation of the disclosed intrusion detector will now be discussed
with reference to FIG. 6 of the drawings which is a schematic
diagram of the effect of a single upper lens panel 14a and a single
lower lens panel 16a on light and infrared radiation, in accordance
with the present invention.
The intrusion detector may be mounted on the wall of premises to be
protected. After this is done, with the cover still removed, the
lamp 40 is electrically actuated by switch 43 which connects the
lamp to the power supply. As discussed above, although relay 44
will provide a detection signal when the switch is in this
position, the alarm control panel prevents the generation of an
alarm signal during the adjustment of the detector. The light
emitted from the lamp, illustrated by waveform 46, is transmitted
through the lower lens panel 16a and into the general zone to be
protected by the detector.
Lens 10 includes a far field lens panel 14a (the upper lens) and a
near field lens panel 16a (the lower lens). In FIG. 6, waveform 48
illustrates the portion of heat radiating from a body in a near
field (shown by arrow 50) which is focused on the heat sensor 38,
while waveform 52 illustrates the portion of heat radiating from a
body in a far field (shown by arrows 54) which is focused on the
heat sensor 38. The heat radiated from the near field (waveform 48)
strikes the near field panel 16a of lens 10 and is focused on the
heat sensor 38, and the heat radiated from the far field (waveform
52) strikes the far field panel 14a of lens 10 and is focused on
the heat sensor 38. Accordingly, the body heat of an intruder
passing through either the near field or the far field will be
detected by the heat sensor.
In addition to monitoring the near field, the lens panel 16a serves
an alignment function. It does so with visible light (waveform 46)
from the lamp 40. The lamp is positioned relative to the lower lens
panel 16a and the heat sensor 38 so that in front of the lower lens
panel 16a the collimated light (waveform 46) from the lamp 40
parallels the portion of the radiation (waveform 52) from the far
field 54 which is focused on the heat sensor 38 by the upper lens
panel 14a.
Light from the lamp 40 is used to locate and establish the zones
protected by the intrusion detector before the intrusion detector
is placed in operation. After the larger housing 4 has been
mounted, an observer stands in a specific zone desired to be
protected. The lamp 40 is turned on, and the inner housing 26 is
adjusted until the observer sees the light from the lamp through
lower lens panel 16a. Once the observer sees the light from the
lamp, he is in a zone being observed by the detector. Accordingly,
a portion of the body heat radiated from that position or zone will
parallel the light emitted from the lamp back towards the lens,
strike the upper lens panel 14a, and be focused on the heat sensor.
All positions from which the light from the lamp can be seen are
zones that are being observed and will be protected by the
detector. Because both the near field and far field lenses are
subdivided into an equal number of individual panels 14a and 16a,
respectively (see FIG. 5), a corresponding number of zones to be
protected by the intrusion detector can be located and
established.
If it is determined that one of the zones includes an object that
is a potential source of false alarms, the internal housing
containing the lens segments can be repositioned slightly either
horizontally or vertically to avoid the potential problem. Under
some circumstances it may be more desirable to eliminate the zone
that is viewing the potential source of false alarms. This can be
accomplished by masking over the appropriate lens segment. (A piece
of tape cut to size and appied only to the appropriate lens will
accomplish this).
Once all desired zones of protection are located in the above
manner, the grill 6 is mounted to the front of the housing 4, and
the switch 43 now connects power to the relay 44, and removes it
from lamp 40. Then, the alarm control panel is adjusted so that any
detection signal which that panel receives from the relay will
generate an alarm signal. The intrusion detector is now in its
operational or "ready" mode, and any intrusion detected by the heat
sensor will actuate the alarm.
The invention as described above employs a single lamp for
establishing the position of the far field. It would also be within
the scope of the invention to similarly employ a second lamp for
establishing the position of the near zone via the far zone lens.
In that case, the second lamp would be positioned relative to the
far field lens and the heat sensor so that light from the second
lamp passes through the far field lens and parallels the portion of
radiation which is focused on the heat sensor by the near field
lens.
The description of the invention provided herein is intended to be
illustrative only and is not restrictive of the scope of the
invention, that scope being defined by the following claims and all
equivalents thereto.
* * * * *