U.S. patent number 3,836,710 [Application Number 05/287,733] was granted by the patent office on 1974-09-17 for pattern discrimination system using television.
This patent grant is currently assigned to N A C Incorporated. Invention is credited to Masaaki Takahashi.
United States Patent |
3,836,710 |
Takahashi |
September 17, 1974 |
PATTERN DISCRIMINATION SYSTEM USING TELEVISION
Abstract
A pattern discrimination system for automatic and rapid
detection of occurrences of an abnormal condition in a pattern
under surveillance comprising the means and steps of producing at
least one horizontal gate pulse and vertical gate pulse of any
required width and position by utilizing the television art,
sampling a video signal with the horizontal and vertical gate
pulses to form at least one sample surface variable in position,
size or shape thereof in the field of view of a monitor, producing
an integrated value of voltage of a video signal corresponding to
the sample surface of the pattern under surveillance, digitally
storing the integrated value of voltage of the video signal in a
digital memory, and producing another integrated value of voltage
of the video signal corresponding to said sample surface of the
pattern under surveillance after a lapse of a predetermined time
interval and comparing the second integrated value of voltage with
the integrated value of voltage stored previously.
Inventors: |
Takahashi; Masaaki (Yokohama,
JA) |
Assignee: |
N A C Incorporated (Tokyo,
JA)
|
Family
ID: |
27277520 |
Appl.
No.: |
05/287,733 |
Filed: |
September 11, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Dec 9, 1971 [JA] |
|
|
46-99008 |
Jan 20, 1972 [JA] |
|
|
47-7238 |
May 4, 1972 [JA] |
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47-43727 |
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Current U.S.
Class: |
348/155 |
Current CPC
Class: |
G06K
9/20 (20130101); G06K 9/78 (20130101); G08B
13/19634 (20130101); G06K 9/78 (20130101); G06K
9/78 (20130101); G06K 9/62 (20130101); G08B
13/18 (20130101); G08B 13/19602 (20130101); G06K
9/62 (20130101); G06K 9/20 (20130101); G06K
9/20 (20130101); G06K 9/62 (20130101) |
Current International
Class: |
G08B
13/18 (20060101); G08B 13/194 (20060101); G06K
9/78 (20060101); H04n 007/18 () |
Field of
Search: |
;178/6.8,DIG.33,DIG.38,DIG.1,DIG.37 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Britton; Howard W.
Attorney, Agent or Firm: Stevens, Davis, Miller &
Mosher
Claims
What is claimed is:
1. A pattern discrimination method for automatic and rapid
detection of occurrences of an abnormal condition in a plurality of
patterns under surveillance comprising the steps of producing a
number of horizontal gate pulses and vertical gate pulses of any
width and position as required by utilizing the television art,
forming in the field of view of a monitor one or more sample
surfaces variable in position, size and shape thereof by sampling
by using said horizontal gate pulses and vertical gate pulses,
converting optical images of the patterns under surveillance into
electric signals by means of at least one television camera,
producing and storing separately in a plurality of memories a
plurality of sets of integrated values of voltages of video signal
components corresponding to said one or more sample surfaces of the
patterns under surveillance, and producing further plurality of
sets of integrated values of voltages of video signal components
corresponding to said one or more sample surfaces of the patterns
under surveillance and comparing said further plurality of sets of
integrated values of voltages with the plurality of sets of
integrated values of voltages stored separately in the
memories.
2. A pattern discriminating apparatus for automatic detection of
occurrences of an abnormal condition in a pattern under
surveillance, comprising:
generating means for generating horizontal and vertical gate
pulses;
sampling means for sequentially sampling first and second portions
of a video signal corresponding to a predetermined portion of the
field of view of a television camera with said horizontal and
vertical gate pulses;
integrating means for integrating the sampled video signal
portions;
converting means for converting the integrated video signal
portions into first and second series of corresponding digital
pulses;
digital memory means for storing said first series of digital
pulses therein;
comparing means for comparing said stored digital pulses with said
second series of digital pulses;
indicator signal means for producing a signal when said stored
series of pulses and said second series of pulses compared in said
comparing means differ by a predetermined amount;
a plurality of AND gates, each having one input connected to an
output of said sampling means;
a gate pulse generator connected to a second input of each of said
AND gates, said gate pulse generator generating a plurality of
pairs of vertical and horizontal gate pulses, one pair of gate
pulses being supplied to a corresponding one of said AND gates
through said second input thereof;
means applying outputs of said AND gates sequentially to said
integrating means;
means applying outputs of said integrating means in a corresponding
sequence to a corresponding plurality of digital memory means and
comparing means; and
means applying outputs of said plurality of comparing means to said
indicator signal means.
Description
This invention relates to improvements in pattern discrimination
systems using the television art.
The practice of using a television system comprising at least one
television camera and at least one minitor for keeping watch on
various conditions (for protecting safes, detecting unwarranted
intruders, keeping vigil against burglars, detecting fires and
effecting control of traffic conditions, for example) has in recent
years become very popular. However, this system has the
disadvantage that an operator is required to watch one or more
monitors at all times. It is a strain on the operator to constantly
watch, particularly at night, a plurality of minitors and this
entails an increase in the number of operators required for this
task and hence a rise in personal expenses.
To solve this problem, proposals have been made to employ a
surveillance apparatus which uses a television system and produces
an alarm only when an abnormal condition is detected. By this
arrangement, it is possible to save labor because the operator has
to look at a minitor only when an alarm is given for an accident or
to take a picture or keep a record on a video tape recorder of the
abnormal condition upon production of a signal indicating the
trouble without requiring the operator.
Generally, the use of a digital system for discrimination of
information on a pattern under surveillance entails the use of an
enormous number of bits for covering every nook and corner of the
pattern. At the present status of art, the surveillance apparatus
of the type described uses very expensive video discs, memories and
other components. Thus, full realization of advantages from use of
the surveillance apparatus of the type described has been hampered
by inability to produce an apparatus which is low in cost and
reliable in performance. In addition to being uneconomincal, the
use of a digital system designed to compare video signals for the
whole pattern has an additional disadvantage in that fatal trouble
occurs when comparison of information on the pattern is effected
with respect to the entire field of view of the monitor as
subsequently to be described.
The present invention obviates the aforementioned disadvantages of
the prior art. Accordingly, the invention has as its object the
provision of a pattern discrimination system using a television
system wherein a number of horizontal gate pulses and vertical gate
pulses corresponding to portions of a pattern to be sampled are
produced. A video signal of the pattern produced by a television
camera is sampled by the horizontal and vertical gate pulses in
order to produce a signal or signals representing a sample portion
or portions of the pattern, voltage or voltages of an integrated
value of said signal or integrated values of said signals for one
field being supplied to a digital memory as a piece of information
for the pattern under surveillance, and such piece of information
for the one pattern under surveillance being compared with the
information of the pattern stored in the digital memory, so that
pattern discrimination can be effected rapidly and
automatically.
One feature of the invention lies in the fact that comparison of
information is made not between video signals for the whole pattern
under surveillance but between components of the video signals for
discrete portions of the pattern under surveillance of any size,
shape, position and number obtained by sampling. The integrated
value of the voltage for one field period for each of these
discrete portions or sample surfaces is compared with the
corresponding integrated value of the voltage for one field which
is obtained earlier at a predetermined time interval and stored in
the digital memory.
The reasons why the aforementioned specific portion or portions of
the field of view of the television camera which may be of any
number, size, shape and position are used as sample surfaces are as
follows: If the pattern discrimination system used as a
burglar-proof device for the paintings shown in FIG. 6, for
example, is designed to cover the entire field of view of the
television camera or the minitor, the movement of a person in the
field of view would be detected by the system as an abnormal
condition even if the paintings are not involved in an accident. If
a sample surface or surfaces of suitable number, shape, size and
position are selected which consists of relevant portions of the
paintings, the aforementioned disadvantage could be obviated and
the accident involving the paintings could only be detected as an
abnormal condition. The gate pulses produced correspond in
position, size, shape and number to the sample surfaces on the
field of view of the monitor.
When optical images of a pattern illuminated by a light source are
converted into electric signals by a television camera, the
intensity of illumination may undergo a gradual change caused by a
change in weather or the light source and such change may be
detected as an abnormal condition in the pattern discrimination
system according to this invention. However, this can be obviated
by replacing at regular intervals the information stored in the
memory by new information. Replacements of the stored information
also have the effect of preventing the system from passing the
judgement of the existence of an abnormal condition by error due to
drift which may be encountered in the television circuit.
The pattern discrimination system according to this invention also
permits the number of objects passing through the field of view of
the monitor to be determined by counting the number of occurrences
of the abnormal conditions in the sample surfaces obtained in
comparison with the normal conditions stored in the digital
memory.
Additional and other objects, as well as features and advantages of
the invention, will become evident from the description set forth
hereinafter when considered in conjunction with the accompanying
drawings, in which:
FIG. 1 shows the basic concept of the present invention, showing a
pattern and sample surfaces thereof, and vertical and horizontal
gate pulses in relation to a video signal;
FIG. 2 is a block diagram of an apparatus used for carrying out the
system according to this invention into practice;
FIG. 3A is a diagrammatic representation of one form of the
vertical and horizontal gate pulse producing circuit used in the
system according to this invention;
FIG. 3B shows the vertical and horizontal gate pulses;
FIG. 4 shows one form of the video signal amplifying, integrating
and gating circuit used in the system according to this
invention;
FIG. 5 shows one form of the buffer and AND circuit and the scanner
used in the system according to this invention; and
FIGS. 6 and 7 show examples of the system according to this
invention.
The basic concept of the present invention will be described with
reference to FIG. 1. When optical images of a pattern D are
converted into electric signals by means of a television camera,
the pattern D appears in a field of view A of a monitor. B
designates horizontal gate pulses and C, vertical gate pulses. If a
video signal S which corresponds to the monitor field of view A is
sampled by the horizontal gate pulses and vertical gate pulses, a
signal or signals corresponding in number to the sample surfaces of
pattern D can be produced. Each of the signals representing the
sample surfaces of pattern D may, for example, be integrated for
one field period.
The sample surfaces, 1, 2, . . . 9 appearing in the monitor field
of view A shown in FIG. 1 correspond to the signals produced by
sampling the video signal of the pattern D by the horizontal gate
pulses and vertical gate pulses B and C. In actual practice,
outputs of a gate pulse generator 10 shown in FIG. 2, adapted to
produce horizontal gate pulses with vertical gate pulses, are taken
out through a line 23 and mixed with the video signal S, so that
the sample surfaces 1, 2, . . . 9 are superimposed on the pattern D
in the monitor field of view A and can be seen as shown in FIG. 1
with respect to their position, size, shape and number. This
facilitates setting of the position, size, shape and number of the
sample surfaces.
The image actually seen in the monitor field of view A as shown in
FIG. 1 consists of the sample surfaces 1, 2, . . . 9 and the
pattern D. Other portions shown in FIG. 1 are inserted in FIG. 1
merely for the sake of convenience to enable the invention to be
clearly understood and are not actually visible in the monitor
field of view A.
Production of gate pulses will be described with reference to FIGS.
3A and 3B. In FIG. 3A, h designates horizontal drive pulses. 30
designates a differentiation circuit which differentiates each of
the pulses h and triggers a one-shot multivibrator 31 by a
differentiated pulse corresponding to the trailing edge of the
pulse h as shown in FIG. 3B to cause the latter to produce a pulse
j. The pulse width t.sub.1 may be varied by a variable resistor
34.
The pulse j is differentiated by differentiation circuit 32, and a
one-shot multivibrator 33 is triggered by a differentiated pulse
corresponding to the trailing edge of pulse j and caused to produce
a pulse k. The pulse width t.sub.2 may be varied by a variable
resistor 35.
Gate pulses H.sub.1 are reversed in form with respect to pulses k
and correspond to the horizontal gate pulses H.sub.1 shown in FIG.
1. The horizontal drive pulses h shown in FIG. 3B have a horizontal
scanning period of T.sub.H corresponding to the width of the
monitor field of view A.
It will be seen that the horizontal position of gate pulses H.sub.1
can be changed by varying pulse width t.sub.1 by means of variable
resistor 34 and that the width of gate pulses H.sub.1 can be
changed by varying pulse width t.sub.2 by means of variable
resistor 35. This also applies to the vertical gate pulses. In FIG.
3A, 40 and 42 are differentiation circuits, 41 and 43 are one-shot
multivibrators, and 44 and 45 are variable resistors capable of
adjusting the width of vertical gate pulses. l designates vertical
drive pulses. The gate pulses V.sub.1 shown in FIG. 1 can be
produced by inverting pulses n shown in FIG. 3B. Pulses m shown in
FIG. 3B are produced by one-shot multivibrator 41.
Gate pulses k and n are of reversed polarity and are mixed by a
polarity reversing and mixer circuit 46 to produce gate pulses
H.sub.1 and V.sub.1 shown in FIG. 1 which are taken out through a
terminal 47. The sample surface 1 shown in FIG. 1 is formed by a
pair of one horizontal gate pulse and one vertical gate pulse
H.sub.1 and V.sub.1. Thus, it will be appreciated that the sample
surface 1 may be disposed in any position and may have any shape
and size as desired in the monitor field of view A.
The gate pulse generator 10 shown in FIG. 2 comprises circuits for
producing the abovementioned gate pulses which may be in any number
as required. In the embodiment shown and described, there are
provided six gate pulse producing circuits for H.sub.1, H.sub.2,
H.sub.3 and V.sub.1, V.sub.2, V.sub.3 which are combined with one
another for V.sub.1 H.sub.1, V.sub.1 H.sub.2, V.sub.1 H.sub.3,
V.sub.2 H.sub.1, V.sub.2 H.sub.2, V.sub.2 H.sub.3, V.sub.3 H.sub.1,
V.sub.3 H.sub.2 and V.sub.3 H.sub.3 which correspond to nine sample
surfaces 1, 2, . . . 9. Gate pulse V.sub.1, for example, is
concerned with the simultaneous formation of sample surfaces 1, 2
and 3, so that a variation in the position and width of gate pulse
V.sub.1 simultaneously affects sample surfaces 1, 2 and 3. Thus, if
it is desired to cause a variation to occur in each of the sample
surfaces independently of one another, it would be necessary to
provide eighteen gate pulse producing circuits.
There are a number of gate pulse producing systems which can be
used in this invention. The gate pulse producing system used in
this embodiment is one which uses one-shot multivibrators to
produce nine sample surfaces.
A video signal corresponding to a line E in the monitor field of
view A is indicated by F in FIG. 1. Signals on sample surfaces 4, 5
and 6 have wave forms a, b and c in video signal F respectively. In
a video signal G, d is a composite signal for sample surfaces 7, 8
and 9, e is a composite signal for sample surfaces 4, 5 and 6 and f
is a composite signal for sample surfaces 1, 2 and 3. Thus, it is
possible to take out the component of a video signal corresponding
to the sample surface 1 by using gate pulses V.sub.1, H.sub.1, the
component of the video signal corresponding to the sample surface 2
by using gate pulses V.sub.1, H.sub.2, and so on so that the
components of the video signal corresponding to sample surfaces 3
to 9 can be taken out by using gate pulses V.sub.1, H.sub.3 to
V.sub.3, H.sub.3.
FIG. 2 shows one form of the apparatus used for carrying out the
system according to this invention into practice. The video signal
S is supplied to video signal amplifying, integrating and gating
circuits AG.sub.1 to AG.sub.9. On the other hand, gate pulses
V.sub.1 H.sub.1, V.sub.1 H.sub.2, V.sub.1 H.sub.3, V.sub.2 H.sub.1,
V.sub.2 H.sub.2, V.sub.2 H.sub.3, V.sub.3 H.sub.1, V.sub.3 H.sub.2
and V.sub.3 H.sub.3 are taken out from the gate pulse generator 10
described with reference to FIG. 3A and supplied to circuits
AG.sub.1 to AG.sub.9.
FIG. 4 shows one of the video signal amplifying, integrating and
gating circuits shown in FIG. 2. Video signal S is supplied to a
video signal amplifier circuit 50 and amplified thereby. The
amplified video signal is introduced into a sampling and holding
circuit 51 performing the operation of integration to which the
aforementioned gate pulses H.sub.1, V.sub.1 are supplied through a
line 52, so that the portion of the video signal S corresponding to
the sample surface 1 is sampled. More specifically, the integrated
value of the voltage for one field period corresponding to the
sample surface 1 is produced and stored as a signal for the sample
surface 1. At the same time, circuit 51 is reset after a lapse of
one field period by a reset pulse produced by a blanking signal
supplied through a line 53. Thus, circuit 51 is ready for
integrating the next following input thereto.
In this way, the video signal S supplied to video signal
amplifying, integrating and gating circuits AG.sub.1 to AG.sub.9 is
amplified and sampled so that the integrated values of the voltages
for one field period corresponding to sample surfaces 1 to 9 are
produced and stored while the gating circuits are reset by reset
pulses after the lapse of one field period. This cycle of operation
is repeated. GT.sub.1 in FIG. 4 is the same gate GT.sub.1 shown in
FIG. 2, and 54 designates a line through which a clock pulse is
supplied to the gate GT.sub.1.
Thus, the integrated value of the voltage for one field period
corresponding to the video signal for the sample surface 1 shown in
FIG. 1 is stored in the video signal amplifying, integrating and
gating circuit AG.sub.1 shown in FIG. 2. In like manner, the
integrated values of the voltages for one field period
corresponding to the video signal for sample surfaces 2 to 9 shown
in FIG. 1 are stored in the video signal amplifying, integrating
and gating circuits AG.sub.2 to AG.sub.9 respectively. Gate pulse
generator 10 is connected through a line 20 to a synchronizing
signal generator (not shown) so that the gate pulses may be
produced in synchronism with the video signal S.
The output signal voltages of circuits AG.sub.1 to AG.sub.9 are
supplied to gates GT.sub.1 to GT.sub.9 respectively. Gates GT.sub.1
to GT.sub.9 successively effect gating upon receiving a supply of
clock pulses from a clock pulse generator 11, and the outputs of
gates GT.sub.1 to GT.sub.9 are successively converted into digital
values by an analogue-to-digital converter 12. At the same time,
gates GT.sub.10 to GT.sub.18 are successively made to effect gating
by clock pulses supplied from clock pulse generator 11 to transmit
the output of gate GT.sub.10 to a buffer and AND circuit BF.sub.1.
It will be appreciated that the outputs of integrating and gating
circuits AG.sub.2 to AG.sub.9 are successively transmitted through
gates GT.sub.2 to GT.sub.9, A-D converter 12 and gates GT.sub.11 to
GT.sub.18 to buffer and AND circuits BF.sub.2 to BF.sub.9,
respectively.
Clock pulse generator 11 shown in FIG. 2 is connected through line
20 to the synchronizing signal generator (not shown) so that the
transmission of the outputs of gates GT.sub.1 to GT.sub.9 may be in
synchronism with the video signal S. The nine output signal
voltages of integrating and gating circuits AG.sub.1 to AG.sub.9
are succesively converted into digital quantities within about 1
millisecond in each vertical blanking period by the
analogue-to-digital converter 12.
In this embodiment, the output of analogue-to-digital converter 12
is set at a digital quantity represented by three bits by
considering economy and also because this arrangement suits the
purpose for which the invention is intended. It is to be understood
that the invention is not limited to this digital quantity and that
a digital quantity represented by a greater number of bits may be
used in this invention. The analogue-to-digital converter 12 used
in this embodiment is of the successive operation type. It is also
to be understood that the invention is not limited to this type and
that nine analogue-to-digital converters may be used and arranged
in parallel with one another.
The operation of buffer and AND circuits BF.sub.1 to BF.sub.9 will
be described with reference to circuit BF.sub.1 shown in FIG. 5
which comprises a first buffer 60 and a second buffer 62 (which are
buffers of three bits as aforementioned), an AND circuit 63 for
checking on the digital quantity stored in the two buffers, and a
gate circuit 61.
The digital quantity obtained from the output of circuit AG.sub.1
by analogue-to-digital converter 12 is invariably stored in the
first buffer 60 initially. As aforementioned, new digital
quantities are stored one after another in the first buffer 60 each
for one field period. For example, if a memory command signal 21 is
supplied from outside to a scanner 13, then the digital quantity
stored in the first buffer 60 is transferred by the gating action
of gate 61 which is operated by a pulse producing circuit 69
through a line 65 to the second buffer 62. At this time the movable
contact of a switch SW is in contact with the lower fixed contact
shown. The digital quantity stored in the second buffer 62 shows no
change unless the memory command signal 21 is supplied thereto.
Thus, the buffer and AND circuit BF.sub.1 is, in the absence of the
memory command signal 21, in a collation mode in which a fresh
digital quantity introduced into the first buffer 60 is examined
and compared with the digital quantity stored in the second buffer
62 by the AND circuit 63 whose output is taken out through a line
64.
Other buffer and AND circuits BF.sub.2 to BF.sub.9 function in the
same manner as described with reference to circuit BF.sub.1. The
outputs of the buffer and AND circuit BF.sub.1 to BF.sub.9 are
supplied to an AND circuit 14 as shown in FIG. 2.
One example of examining and comparing a new digital quantity with
the digital quantity stored in the second buffer 62 will be
described with reference to FIG. 6. This example is an application
of the invention in a burglar-proof device adapted for use with
paintings exhibited in a gallery. In the figure, A designates a
field of view of the monitor as shown at A in FIG. 1. Paintings 71
to 79 and men 70, 70 correspond to the pattern D shown in FIG. 1.
The paintings 71 to 79 and men 70, 70 are used as nine sample
surfaces corresponding to the nine sample surfaces shown in FIG. 1.
This device is intended to detect the theft of any one of the
paintings concerned without detecting the movement of men in the
gallery.
When there is no abnormal condition involving any one of the nine
paintings, the components of a video signal of normal value
corresponding to the nine sample surfaces are supplied to video
signal amplifying, integrating and gating circuits AG.sub.1 to
AG.sub.9, passed successively through gates GT.sub.1 to GT.sub.9
respectively by clock pulses supplied successively from clock pulse
generator 11, and converted into digital quantities by
analogue-to-digital converter 12 which are stored in the first
buffers 60 in buffer and AND circuits BF.sub.1 to BF.sub.9
respectively.
If a memory command signal is supplied to the scanner 13, each gate
61 of each buffer and AND circuit performs a gating operation so as
to transfer the digital quantity stored in the first buffer 60 of
each buffer and AND circuit to the second buffer 62 thereof.
If no other memory command signal is supplied to the scanner 13
after one digital quantity transfer operation is performed, then a
new digital quantity supplied as an input to each of the first
buffers 60 is examined and compared with the digital quantity
stored previously in each of the corresponding second buffers 62,
and the results are transferred from all the circuits BF.sub.1 to
BF.sub.9 to the AND circuit 14. The outputs of the AND circuits of
the buffer and AND circuits BF.sub.1 to BF.sub.9 will indicate
agreement of the compared digital quantities and the output of the
AND circuit 14 will also indicate agreement of the compared digital
quantities, so that an alarm circuit 15 is not actuated.
Assuming that the painting 71 shown in FIG. 6 is stolen, a change
will occur in the component of the video signal corresponding to
the sample surface 1. Thus, the digital quantity supplied to the
first buffer 60 in the buffer and AND circuit BF.sub.1 after the
theft has taken place will vary from the digital quantity stored in
the second buffer 62 therein. As a result, a disagreement signal
will be produced by the AND circuit 63 and the AND circuit 14 will
also produce a disagreement signal, so that the alarm circuit 15 is
actuated to give warning of the theft.
An alarm signal produced by the alarm circuit 15 and taken out
through a line 22 shown in FIG. 2 to the outside may be supplied to
a photographic camera or a video tape recorder to keep a record of
the scene of the crime. Alternatively, the line 22 for taking out
the alarm signal to the outside may be connected to an apparatus to
transmit the alarm signal through communication lines to a remote
place.
It is possible to obtain the number of objects that have moved in
the field of view of the monitor by counting the number of alarm
signals produced by the alarm circuit. Also, it is possible to
obtain the number of alarms given for each sample surface by
counting the outputs of each AND circuit of buffer and AND circuits
BF.sub.1 to BF.sub.9.
Another example of application of this invention is shown in FIG.
7. As shown, the invention is directed to a burglar-proof device
for a jewel 80 placed in a showcase. A designates the showcase
which corresponds to the field of view of the monitor, 1, 2, 3, 4
and 5 designate sample surfaces, the sample surfaces 1,2, 3 and 4
surrounding the jewel 80 while the sample surface 5 is set on the
jewel 80.
In case the pattern under surveillance is illuminated by a light,
such as one supplied through a household power supply outlet, whose
intensity of illumination remains constant at all times, only one
memory command signal 21 may be supplied at the beginning of the
operation to store initial digital quantities in the second buffers
62 in buffer and AND circuits BF.sub.1 to BF.sub.5 and digital
quantities successively produced thereafter may be compared with
the initially stored digital quantities. If, however, the pattern
under surveillance is disposed out of doors and subjected to
illumination which gradually varies in intensity, or if the
circuits of the television camera used are not stable in
performance and the signal voltages produced vary gradually with
time, false alarms will be produced by changes in the signal
voltages of sample surfaces due to changes in the intensity of
illumination to which the pattern is subjected or to the
instability of the television camera circuits, even if no abnormal
condition is produced in the pattern. This problem is obviated in
the present invention by using a timer, for example, which is
operative to produce a plurality of memory command signals at
intervals of, say, 5 minutes and to supply the same to the scanner
13. By this arrangement, the digital quantities stored in the
second buffers 62 in all the buffer and AND circuits each can be
replaced by a new digital quantity at intervals of 5 minutes.
If there is no appreciable change in the intensity of illumination
in 5 minutes, there will be no change between the stored
information on the pattern and the information on the pattern
obtained five minutes later; therefore, no alarm is produced. Thus,
it is possible to eliminate the likelihood of false alarms which
might otherwise be produced by changes in the digital quantities of
the sample surfaces of the pattern caused not by the abnormal
conditions occurring in the pattern but by changes in extraneous
conditions not involving the pattern.
The embodiment shown and described above concerns the application
of the invention in cases where one pattern is placed under
surveillance at a time in an effort to detect the occurrence of
abnormal conditions in it. The invention is not limited to this
embodiment and can have application in cases where a plurality of
patterns are placed under surveillance at a time to detect the
occurrences of the abnormal condition in them by storing the
reference information in a plurality of memories.
In these cases, one television camera with a pantilt head may be
used or a plurality of television cameras may be utilized for
converting the optical image of a plurality of different patterns
into electric signals. This application will be described with
reference to FIG. 5. The movable contact of the switch SW shown in
the figure is brought into contact with an upper fixed contact to
connect gate 61 to a gate 66. If a signal is supplied through a
line 90 to a scanner circuit 68 in scanner 13, then the scanner
circuit 68 selects any one of memories M.sub.1 to M.sub.10.
Assuming that an optical image of a first image is converted into
an electric signal and memory M.sub.1 is selected, a gate pulse
will be produced by pulse generator 69 and transmitted through line
65 to gates 61 and 66 if a memory command signal 21 is supplied to
scanner 13. This permits the digital quantities of the sample
surfaces to be passed on from the first buffer to the memory
M.sub.1 through the scanner circuit 68 to be stored therein. The
outputs of buffer and AND circuits BF.sub.2 to BF.sub.9 are taken
out through a line 94.
The digital quantity corresponding to each sample surface is
represented by three bits, so that it is possible to store in a
memory the digital quantity corresponding to one pattern by using
27 bits altogether since one pattern comprises nine sample
surfaces. This is conducive to reducing the cost of production of
the memories.
When the information on a second pattern is stored in a memory, a
signal is supplied through line 90 to the scanner circuit 68 to
connect the same to memory M.sub.2, so that the information on the
second pattern is stored in memory M.sub.2 in like manner. The
information on the next following patterns is stored successively
in the same manner till the information on a tenth pattern is
stored in memory M.sub.10.
Upon completion of storing of the information on the tenth pattern
in memory M.sub.10, the apparatus is placed in a collation mode
till another memory command signal 21 is supplied to scanner 13.
Now, if the optical image of the first pattern is converted into an
electric signal again and memory M.sub.1 is selected by the scanner
circuit 68 in scanner 13, the information in memory M.sub.1 will be
returned through a gate 67 in the scanner 13 to the second buffer
62 in the first buffer and AND circuit BF.sub.1. Gate 67 is open in
the absence of a memory command signal 21 to permit the information
stored in a memory M.sub.1 to be returned to the second buffer 62
in a buffer and AND circuit. A line 93 from the gate 67 in the
scanner 13 is one through which information is transferred to the
second buffers 62 in buffer and AND circuits BF.sub.2 to
BF.sub.9.
All the information represented by twenty-seven bits in memory
M.sub.1 is transferred to the second buffers 62 in buffer and AND
circuits BF.sub.1 to BF.sub.9 in this way and compared with the
information stored in the first buffers 60 therein.
Then, if the optical image of the second pattern is converted into
an electric signal again and memory M.sub.2 is selected by the
scanner circuit 68, the information stored in the second buffers 62
in the buffer and AND circuits BF.sub.1 to BF.sub.9 is replaced by
the information stored in memory M.sub.2 and compared with the new
information supplied to the first buffers 60 therein.
The optical images of the third to tenth patterns are successively
converted into electric signals which are processed in the same
manner as aforementioned so as to compare the patterns with one
another at regular intervals. The AND circuit 14 is actuated in the
same manner when ten patterns are placed under surveillance as when
one pattern is placed under surveillance.
Another application of the invention presently to be described also
involves a sort of pattern discrimination. In this application, the
information on 10 different patterns may, for example, be stored in
10 memories M.sub.1 to M.sub.10 respectively, and the information
on the pattern D shown in FIG. 1 may be stored in memory M.sub.1,
for example. A television camera may selectively convert the
optical image of any one of a plurality of patterns including the
pattern D as desired into an electric signal to compare the
information on the selected pattern with the information stored in
any one of the memories M.sub.1 to M.sub.10.
If scanner 13 is made to scan memories M.sub.1 to M.sub.10 at high
speed and the information stored therein is compared with the
information on the pattern D while the television camera is
converting the optical image of the pattern D into an electric
signal, a coincidence signal should be produced when memory M.sub.1
is scanned. The coincidence signal is produced by the alarm circuit
15 shown in FIG. 2 and indication is given at the same time that
the memory whose information coincides with the information on the
pattern being surveyed is memory M.sub.1. A line 91 shown in FIG. 5
is one through which an output signal of the scanner 13 is
transmitted to a counter 16 to cause the latter to indicate that
the memory sought is memory M.sub.1. A line 92 shown in FIG. 5 is
one through which an output signal of counter 16 is transmitted to
the alarm circuit 15 to give an alarm that the memory sought is
memory M.sub.1.
All the embodiments of the invention shown and described
hereinabove involve the use of the monochrome television camera or
cameras and the processing of the video signal S produced by
converting the optical image of the pattern D into electric
signals. It is to be understood, however, that the invention is not
limited to these embodiments and that the invention can have
application in cases where the pattern D is in color and a color
television camera is used to effect pattern discrimination based on
colors. If the optical image of the pattern D is converted into an
electric signal by using a color television camera when the pattern
D is colored, three video signals for red, green and blue colors
respectively will be produced in place of one video signal which is
the case when a monochrome television camera is used. It will thus
be necessary to use three sets of the apparatus shown in FIG. 2 and
to supply each of the red, green and blue video signals to the
input terminal of one of these three apparatus, and it will be
possible to effect pattern discrimination in color.
Discrimination of a pattern represented in one or more colors may
be effected by using the apparatus shown in FIG. 2 which may agree
in number with the number of color or colors of the pattern.
Discrimination of a color pattern can be effected based on a color
characteristic of the pattern by using a monochrome television
camera. In this case, various types of color filters are inserted
in the television camera and the color of the pattern which is
characteristic thereof is only converted into an electric signal
for processing.
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