Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-12-13
2002-12-24
Pham, Toan (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S545300, C340S565000, C348S152000
Reexamination Certificate
active
06498564
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a tracking and monitoring system and, more particularly, to a tracking and monitoring system equipped with heat source tracker used for a penetrating object.
DESCRIPTION OF THE RELATED ART
The prior art monitoring system has a human body detecting sensor or a magnet switch. When the human body detecting sensor or the magnet switch founds an invader, the sensor or the switch supplies a detecting signal to a monitor camera, and the monitor camera is directed to the invader. The monitor camera continuously or intermittently takes a moving picture, and stores the image of the invader in magnetic tape or a magnetic disk. The monitor camera may take static pictures at intervals. The images of the static pictures are stored in a photographic film.
When an inspector wants to check the images stored in the magnetic tape or the magnetic disk, the inspector instructs the controller to drive the magnetic tape or the magnetic disk for heading each of the frames, and searches the series of frames for an image to be required. However, a lot of frames are incorporated in the moving picture, and the inspector consumes a large amount of time and labor.
On the other hand, the static pictures are usually less than the frames of the moving picture, and the search is less time-consuming. Moreover, a silver film is usually used as the photographic film, and the image is clearer than those in the frames. However, the image is produced through the development, and the inspector can not promptly search an image to be required.
Another prior art monitoring system is equipped with an electronic still camera. The electronic still camera has a semiconductor memory for storing the images, and pieces of video data representative of the images are supplied from the semiconductor memory to an image reproducing apparatus. An inspector easily searches the semiconductor memory for the image to be required. However, several seconds are consumed for writing a piece of video data information. This is because of the fact that the semiconductor memory is of the type electrically writable non-volatile memory such as an EEPROM (Electrically Erasable and Programmable Read Only Memory). If an invader passes the detectable area within a short time, the prior art monitoring system merely takes several pictures, and an inspector can not clearly discriminate the invader.
Japanese Patent Publication of Unexamined Application No. 11-234653 discloses a monitoring system, which determines the traveling speed of an invader for regulating the recording intervals. The prior art monitoring system is described in detail with reference to the drawings.
FIG. 1
illustrates the first prior art monitoring system. The prior art monitoring system comprises a monitor camera
101
for taking pictures of an invader, a recording unit
102
for storing pieces of video data representative of images of the invader, a velocity sensor
103
for determining the traveling speed of the invader in the field angle &thgr; and a camera controller
109
for controlling the intervals of photographing work. The monitor camera is corresponding to an image pick-up section of the electronic still camera, and a CCD (Charge Coupled Device) is used in the image pick-up section. The monitor camera
101
is directed to the monitoring area, and does not change the direction. However, the field angle covers the monitoring area.
The velocity sensor
103
includes an object detecting sensor
104
and a mode changer
105
. The object detecting sensor
104
detects infrared light radiated from a source of heat such as a human body, and produces an object detecting signal S
1
. The object detecting sensor
104
supplies the object detecting signal S
1
to the mode changer
105
. The mode changer
105
determines the source of heat to move at a high-speed or a low-speed on the basis of the object detecting signal S
1
, and selectively supplies mode signals S
2
and S
3
to the camera controller
109
. The camera controller
109
is responsive to the mode signal S
2
or S
3
, and requests the monitor camera
101
to take pictures at high speed or a low speed. The video data are supplied from the monitor camera
101
to the recording unit
102
, and are stored in the recording unit
102
.
The object detecting sensor
104
has a differential infrared detector
106
, an optical element
107
and a signal processing unit
108
. The differential infrared detector
106
produces detecting signals at intervals, and the signal processing unit
108
produces the object detecting signal S
1
from the detecting signals.
The differential infrared detector
106
is implemented by a pair of pyroelectric infrared detecting elements
106
a
/
106
b,
and the pyroelectric infrared detecting elements
106
a
and
106
b
are connected in such a manner as to be opposite in polarity. For this reason, the pyroelectric infrared detecting elements
106
a
/
106
b
serve as the differential infrared detector
106
. The optical element
107
is implemented by a Fresnel lens, and the Fresnel lens
107
directs incident light from the detecting areas E
1
, E
2
, E
3
, E
4
and E
5
to the pyroelectric infrared detecting elements
106
a
/
106
b
. Thus, the Fresnel lens
107
makes the monitor camera
101
have a coverage as wide as the monitoring area.
The detecting areas E
1
to E
5
are spaced from one another, and the optical element
107
assigns all of the detecting areas E
1
to E
5
to the object detecting sensor
104
. Each of the detecting areas E
1
to E
5
contains two sub-areas e
1
and e
2
, and the sub-areas e
1
and e
2
are assigned to the pyroelectric infrared detecting elements
106
a
/
106
b
, respectively. When a heat source is in the sub-areas e
1
, the pyroelectric infrared detecting element
106
a
produces a detecting signal, and supplies the detecting signal to the signal processing unit
108
. On the other hand, when the heat source is in the sub-areas e
2
, the pyroelectric infrared detecting element
106
b
produces a detecting signal, and supplies the detecting signal to the signal processing unit
108
. The detecting signal from the pyroelectric infrared detecting element
106
a
is opposite in polarity to the detecting signal from the other pyroelectric infrared detecting element
106
b.
The signal processing unit
108
includes a signal processing circuit, an amplifier, a reference level generator and a level detector. The differential infrared detector
106
is connected to the signal processing circuit, and supplies the detecting signals to the signal processing circuit. The signal processing circuit is connected to the amplifier, and the detecting signals are amplified by the amplifier. The reference level generator produces a pair of reference signals, and the pair of reference signals is indicative of a positive threshold level and a negative threshold level. The amplifier and the reference level generator are connected to the level detector, and the level detector compares the detecting signals with the reference signal. When the detecting signals exceed the threshold level, the level detector changes the object detecting signal S
1
to an active high level, and keeps the detecting signals at the threshold levels in so far as the detecting signals exceed the threshold levels. Thus, the level detector produces the object detecting signal S
1
from the detecting signals indicative of the source of infrared light.
Assuming now that a human body walks in the monitoring field as indicated by arrow M, the human body radiates infrared light, and crosses the detecting areas E
1
to E
5
. While the human body is crossing each of the detecting areas E
1
to E
5
, the human body firstly enters the sub-area e
1
, thereafter, exiting from the sub-area e
1
, entering the sub-area e
2
, finally exiting from the sub-area e
2
. When the human body enters the sub-area e
1
, the pyroelectric infrared detecting element
106
a
detects the infrared light, and changes the detecting signal to the positive level as shown in FIG.
2
. Thereaft
Choate Hall & Stewart
NEC Corporation
Pham Toan
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