CA1126853A

CA1126853A - Object inspection system

Info

Publication number: CA1126853A
Application number: CA342,557A
Authority: CA
Inventors: Hajime Yoshida
Original assignee: Hajime Industries Ltd
Current assignee: Hajime Industries Ltd
Priority date: 1978-12-25
Filing date: 1979-12-24
Publication date: 1982-06-29
Also published as: GB2041199B; JPS5587072A; DE2951780C2; FR2445676A1; FR2445676B1; GB2041199A; DE2951780A1

Abstract

ABSTRACT

An object recognition or inspection system with special features is disclosed, in which an object to be inspected is photoimaged by a photo image sensing device. While forming a comparative control signal by processing the horizontal as well as vertical synchronizing signals contained in a complex video signal from the photo image sensing device, at the same time by supplying the video signal from the photo image sensing device and the reference signal from a reference signal generator, to a comparator, and by further supplying the comparative control signal to the comparator only during the period as specified by the comparative control signal, the video signal is compared with the reference signal at the comparator and an inspection start signal is generated from the comparator and then such inspection start signal is supplied to the inspection system to start the inspection of the object recognition system.

Description

1~6853 --1~

BACKGROUND OF THE INyENTION
Field of the In~ention The present invention relates generally to an object inspection systems, and more particularly to a new object in-spection system of the type that takes the photo image of an object to be inspected by a photo image sensing device.
Description of the Prior Art Inspection systems for very small objects that are transferred by such means as belt conveyers under the prior art normally conduct insPection by microscopic magnification cf the inspected object.When the inspected object is very small, it is difficult to accurately detect whether or not the inspected object is transferred to a predetermined detecting position with high precision. Under the prior art, the arrival of the object to the predetermined detecting position is detected by a photo switch, proximity swltch, etc. ~hen the inspected object is very small, there are various points of ; ~ inconvenience.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic diagram showlng an object recognition system under the prior art;
~ Fig. 2 is a block diagram showing an example of the `~ object recognition system according to the present invention;
Figs. 3A, 3B and 3C are schematic diagrams used to explain the present inyention; and Figs. 4A and 4B, Figs. 5A and SB and Pigs. 6A and 6B
are waveform diagrams used to explain the present invention.

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-2-In order to o~ercome such inconveniences, object position detection systems are proposed where photo sensors are in-stalled on the monitor screen on which inspected objects are projected. Such systems will be now explained in reference to Fig. 1. In the system under the prior art shown on Fig. 1, 1 is a belt on which an object 2 to be inspected is transferred in the direction indicated by an arrow 3. At a predetermined position in connection with belt 1, a photo image sensing equipment such as a television camera or the like 4 is in-stalled which photo magnifies the inspected object 2. 5 is a monitor screen of the photo image sensing system 4 on which, at a predetermined position, a photo sensor 6 is installed in order to detect the positioning of the inspected object 2.
In Figure 1, the hatched block is an image 7 of the inspected object 2 on the belt 1 that is projected on the black back-ground of monitor screen 5. Object 2 moves on the monitor screen 5 in the direction indicated by an arrow 8 towards sensor 6. When image 7, for instance, overlaps sensor 6, ; ~ -sensor 6 generates a start signal which is supplied to an object inspection or recognition system 9 such as a computer or the like to conduct the specified inspection of the object 2. However, according to the shape and dimensions of the inspected object 2 or the position thereof on belt 1, for instance, when the image 7 of the inspected~object 2 as shown on Fig. 1, is in the position shown by brokén like block 10 and moves in the arrow direction 8 on monitor screen 5, image 10 does not~ovexlap sensor 6. Therefore, the inspection system 9 does not start its inspection operation and hence A

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inspection of the object 2 is not conducted. This type of problem can occur even though the sensor 6 is installed with due considerations to the scan direction of the television camera 4 and the transfer direction of the inspected object 2.
Further, from the functional standpoint of television camera 4, since the position detection of the inspected object 2 is at intervals of 16.7 milliseconds, the positioning detec-tion shall inevitably vary or scatter within 16.7 milliseconds.
It is further noted that non action may also be caused by trouble in the monitor television receiver, or upon a de-crease of brightness thereof. In addition, the monitor tele-vision receiver is constantly in motion so that its life may be shortened.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, an objective of the present invention is to provide a novel object recognition system, whi~ch avoids the above mentioned defects of systems under the prior art.
~` Another object of the invention is~to provlde an object recognition system which can positively inspect an object in a short time. ~
; More particularly there is provided an object inspection system comprising:
a) a photo image sensing device picking up an object to ~ , be inspected and delivering a complex video signal having at least a horizontal synchronizing signal, a vertical synchroniz~
ing signal and a video signal;
b) means for separating said horizontal and vertical synchronizing signals and sald video signal from said complex -~

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video signal;
c) means for producing a comparative control signal based upon the horizontal and vertical synchronizing signals;
d) means for generating a reference signal which is responsive to a characteristlc of said video signal;
e) means for comparing the video signal with the reference signal only within a period determined by the com-parative control signal and for producing an inspection start signal; and f) means for inspecting said object when the inspection start signal is supplied thereto.
. There is also provided:
An object inspection system for inspecting an object comprising: .
means for producing a complex video signal of said object and its background, said complex vldeo signal including at least a horizontal and a vertical synchronizing signal and a video signal;
means responsive to said horizontal and vertical synchroni7.ing signals to produce a comparison start signal;
~ means responsive to said background for producing ::~ a reference signal;
means for comparing said video signal and said -: reference signal in response to said comparison start signal to detect a presence of said object in said video signal, operative to produce an inspection start signal in response ~ .

~26~53 -4a-to said comparison; and means for inspecting said object in response to said inspection start signal.
The other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will hereinafter be explained in reference with Figs. 2 through 6.
Fig. 2 is a block diagram showing an example of the object recognition system according tothe present invention.
On Fig. 2, 11 designates a synchronizing signal separator cir-cuit, which separates the complex video signal input from the television camera or the like of the photo image sensing system 4 which photographs an object to be inspected (not shown on the Fig. 2), into a hori~ontal synchronizing signal h, a vertical synchronizing signaI v and a video signal s, respectiYely. The yertical synchronizing signal Y that is separated by the synchronlzing signal separator circuit 11 is : .- :

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1~26~53 ~5--supplied to a timing control circuit 12~ A strobe signal stv is produced by the timing control circuit 12 based upon the vertical synchronizing signal v. This strobe signal stv which specifies the vertical position of the detection area on the monitor screen of a monitor tele~ision receiver as later explained, is supplied to a strobe circuit 14.
The horizontal synchronizing signal h is supplied to a timing control circuit 13. The timing control~circuit 13 produces a strobe signal sth based upon the horizontal syn-chronizing signal h. Strobe signal sth specifies the hori-zontal position of the detection area on the monitor screen as later described. Strobe signal sth is supplied to the strobe circuit 14. Strobe circuit 14, combines strobe signals stv and sth respectively to produce a composite strobe signal or a comparative control signal cst which specifies the hori~ontal as well as the vertical position of the detection :
~; area on the monitor screen. Comparative control signal cst is supplied to a comparator 16. At the time defined as specified by the composite strobe signal~cst, m other words, only at the specified position on the monitor screen, the video signal s is compared with a reference signal which is representative of the brightness level on the monitor screen provlded from a level control or reference signal generator 15. The output of comparator 16 is supplied to a monostable multivibrator circuit 17 which includes a retriggerable mono~
stable multivibrator having a time width of, for instance, 63 microseconds minimum. In~response to an input, the monostable ; multivibrator circuit 17~generates an inspection start signal :~ .

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` ~2~;B53 sta. Inspection start signal sta is supplied to an inspection system 18 for inspecting the object such as a computer as well known, although it is not sho~n on Fig. 2, inspection of the object is conducted. This inspection of the object can be monitored on a monitor screen 19 of a monitor television receiver which receives the output video signal from the tele-vision camera 4.
According to the above described construction of the object recognition or inspection system according to the present invention the following inspection of the object is carried out. If, it is assumed that the monitor screen 19 has a black background, for instance, and an object 21 to be in-spected is white as shown on Fig. 3A. When an object 21 to be inspected arrives at a detection area 20 whose position is specified on the monitor screen 19 by the comparative control signal cst, the comparator 16 outputs a compared output by which the monostable multivibrator circuit 17 generates the start signal sta, and the inspection of the object 21 to be inspected is conducted by the inspection system 18.
Furtner, in order to establish the detection area 20 as indicated on Fig. 3A, it is sufficient that the timing con-trol circuit 12 so functions that the output signal stv from the timing control circuit 12 by the vertical synchronizing signal v shall be arranged as indicated on Fig. 4A and the timing control circuit 13 so functions that the output signal sth from the timing control circuit 13 by the horizontal synchronizing signal h shall be arranged as indicated on Fig.
4B. By the present invention as above described, it is not . . .
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~l~26853 necessary to provide a special photo optical sensor on the monitor screen 19 as in the case with the prior art, and since the detection area 20 is specified as a free determination based upon the horizontal as well as vertical synchronizing signals h and v from the photo image sensing system, the moni-tor television receiver is not directly necessary for the detection action. However, the monitor is only necessary in order to confirm the position of the object to be inspected and so on at the inspection starting time. Accordingly, inspection can not only be conducted without such influence of the monitor screen becoming difficult to observe, or the brightness drop of the monitor screen, or further monitor trouble, but since it does not have to be constantly operated, the life of the monitor television receiver can be preserved for longer periods. In other words, the conventional defects as above mentioned can be almost entirely avoided by this invention. ~ -Further, as shown on Fig. 3B as an example, when theobject 21 moves in the direction indicated by an arrow 22 to the left on the monitor screen 19, as indicated on the drawing, ~
by setting the detection area 20 narrow and long in the ver- ~;
tical direction on the~monitor screen 19, the object 21 can be surely detected in spite of its position being high or low, and the blank period for detection can be greatly reduced.
In order to establish the detection area 20 as illustrated on Fig. 3B, the timing control circuit 12 so fu~ctions such that the output signal stv from the timing control circuit 12 by the vertical synchronizing signal v ' . . . .
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.' . ~ , ~ , ~26~53 shall be as shown on Fig. 5A, and the timing control circuit 13 functions such that the output signal sth from the timing control circuit 13 produced by the horizontal synchronizing signal h shall be established as per Fig. 5B. Thus a short horizontal segment of a large nu~ber of vertical llnes is defined by the signal cst.
Also as illustrated on Fig. 3C, when the object 21 moves vertically up and down on the monitor screen 19 as indicated by an arrow 23, by establishing the detection area 20 narrow and long in horizontal direction on monitor screen 19 as shown on the drawing,in spite of the object 21 being mispositioned to the right or left, it can be surely detected. In order to establish the detection area 20 as shown on Fig. 3C, it is sufficient that the timing control clrcuit 12 functions such that the output signal stv from the timing control circuit 12 by the vertical synchronizing signal shall be set as shown on Fig. 6A and the timing control circuit 13~functions such that the output signal sth fxom the timing control circuit 13 by the horizontal synchronizing signal h shall be set as shown on Fig. 6B.
It is further noted that only a single preferred example of the present invention has been explained in refer-ence to the furnished drawings, but without losing the spirit of the present invention, variations and changes are obviously possible by any one skilled in the art.

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Claims

1. An object inspection system comprising:
a) a photo image sensing device picking up an object to be inspected and delivering a complex video signal having at least a horizontal synchronizing signal, a vertical synchronizing signal and a video signal;
b) means for separating said horizontal and vertical synchronizing signals and said video signal from said complex video signal;
c) means for producing a comparative control signal based upon the horizontal and vertical synchronizing signals;
d) means for generating a reference signal which is responsive to a characteristic of said video signal;
e) means for comparing the video signal with the reference signal only within a period determined by the com-parative control signal and producing an inspection start signal; and f) means for inspecting said object when the inspection start signal is supplied thereto.

2. An object inspection or recognition system as claimed in claim 1, wherein said means for producing the com-parative control signal include two timing control circuits which receive the horizontal and vertical synchronizing signals and produce strobe signals, respectively, and a strobe circuit which receives the strobe signals and then produces the comparative control signal.

3. An object inspection system for inspecting an object comprising:
means for producing a complex video signal of said object and its background, said complex video signal including at least a horizontal and a vertical synchronizing signal and a video signal;
means responsive to said horizontal and vertical synchronizing signals to produce a comparison start signal;
means responsive to said background for producing a reference signal;
means for comparing said video signal and said reference signal in response to said comparison start signal to detect a presence of said object in said video signal, operative to produce an inspection start signal in response to said comparison; and means for inspecting said object in response to said inspection start signal.