US3718823A

US3718823A - Optical detectors for inspecting the condition of samples

Info

Publication number: US3718823A
Application number: US00196293A
Authority: US
Inventors: I Niikura; H Arita
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1970-11-11
Filing date: 1971-11-08
Publication date: 1973-02-27
Anticipated expiration: 1990-02-27
Also published as: GB1372403A; JPS5116319Y1

Abstract

To inspect the condition of a sample, for example a paper money, there are provided a conveyor for successively conveying the sample along a predetermined path; optical means including a source of light disposed on one side of the conveyor for projecting light upon a predetermined area containing a predetermined portion, e.g., the margin of the sample, and a photoelectric transducer on the opposite side and including a plurality of juxtaposed unit elements for producing electric outputs proportional to the quantity of light impinging thereon; and a selection circuit responsive to the outputs from respective unit elements for selecting the output only from a particular unit element corresponding to the predetermined portion of the sample irrespective of the deviation of the position of the sample from said path.

Description

United States Patent (191 Niikura et al.

[ 51 Feb. 27, 1973 [54] OPTICAL DETECTORS FOR INSPECTING THE CONDITION OF SAMPLES [75] Inventors: Isamu Niikura, Hiratsuka; Hirosi Arita, Yokohama, both of Japan [73] Assignee: Tokyo Shibaura Electric Co., Ltd.,

Kawasaki-shi, Japan [22] Filed: Nov. 8, 1971 [21] Appl. No.: 196,293

[30] Foreign Application Priority Data Nov. 11,1970 Japan ..45/1ll205 [52] US. Cl. ..250/223 R, 209/1 1 1.7, 250/219 D, 250/220 [51] Int. Cl. ..H0lj 39/12 [58] Field of Search ..250/22l, 222, 223, 219 LG, 250/219 WD, 83.3 D, 219 D, 219 DR; 178/7.l, 7.6; 356/71; 209/1115, 111.7

[56] References Cited UNITED STATES PATENTS Kieferle ..250/219 LG Akuta ..250/223 R Primary Examiner-James W. Lawrence Assistant Examiner-D. C. Neims AttorneyRobert D. Flynn et a1.

[57] ABSTRACT To inspect the condition of a sample, for example a paper money, there are provided a conveyor for successivelyconveying the sample along a predetermined 'path; optical means including a source of light disposed on one side of the conveyor for projecting light upon a predetermined area containing a predetermined portion, e.g., the margin of the sample, and a photoelectric transducer on the opposite side and including a plurality of juxtaposed unit elements for producing electric outputs proportional to the quantity of light impinging thereon; and a selection circuit responsive to the outputs from respective unit elements for selecting the output only from a particular unit element corresponding to the predetermined portion of the sample irrespective of the deviation of the position of the sample from said path.

10 Claims, Drawing Figures PATENTED 3,718,823

SHEET 1 or 2 FIG.

OPTICAL DETECTORS FOR INSPECTING THE CONDITION OF SAMPLES This invention relates to an optical detector and more particularly to an optical detector wherein materials or samples of definite configuration and size are successively conveyed and the condition of particular portions of the samples is inspected or detected during conveyance.

Examples of the samples of definite configuration and size are paper moneys, certificate stamps, stockcertificates and the like. Among these, paper moneys are severely damaged of spoiled during their long period of circulation by frequent use and handling by many people. Thus, paper moneys are frequently folded and unfolded. Frequently, edge portions are often teared and severed paper moneys are connected together as by an adhesive tape or a thin paper. These damaged paper moneys should be detected and separated when they are recovered by banks or other banking facilities. Prior art manual detection and separation of damaged paper moneys is not only inaccurate but also inefficient and requires much labors.

Based on the optical difference between normal or sound samples and damaged samples, it is possible to detect abnormal samples by optically inspecting particular portions of the samples while they are successively conveyed thus sorting abnormal samples which are spoiled, broken or repaired. More particularly, where the samples to be inspected are paper moneys which are printed with particular patterns except their margins on the periphery, it is possible to detect optically the dirts, breakages and repairs on the longitudinal side edge margins by means of transmitted or reflected light which are converted into electric signals.

To this end, samples are successively conveyed by clamping them between moving belts and by inspecting particular portions, that is margins of the samples by means of an optical detector located on one or both sides of the conveyor belts. However, it is difficult to correctly position the samples on the belt. Depending upon the accuracy of the conveyor mechanism the longitudinal direction or orientation of the samples is often deviated, sometimes by 90, from the direction of movement. Moreover, as the margins of the samples are generally narrow it is difficult to inspect the condition of such margins unless the samples are maintained in correct positions during conveyance. More particularly, the direction of the margins of the samples with reference to the stationary optical detector varies from sample to sample as they are successively conveyed.

Although the following detecting means have been proposed, all of them were proved unsatisfactory.

l. A method wherein a plurality of optical detectors are located along the path of samples so as to substantially enlarge the detection range.

This method requires bulky detector means of complicated construction because it is necessary to use a switching circuit.

2. A method wherein a wide surface of a sample is scanned optically to inspect particular portions on the surface of the sample.

The apparatus is complicated because it is necessary to scan moving samples. Moreover, as the frequency of the signal produced is high its processing is troublesome and requires difficult operation.

3. A method wherein the movement of the samples is stopped intermittently to scan their prescribed portion while they are held stationary.

This method is not practical because of a complicated construction of the conveyor mechanism and of low processing efficiency.

Accordingly, it is an object of this invention to provide an optical detector capable of inspecting or detecting the condition of particular portions of samples while they are successively conveyed.

Another object of this invention is to provide a detector capable of inspecting the condition particular portions of samples even when these orientations are deflected from the direction of normal movement thereof.

According to this invention there is provided an optical detector for inspecting the condition of a sample comprising conveyor means for successively conveying said sample along a predetermined path; optical means including a source of light disposed on one side of said path for projecting light upon a predetermined area containing a predetermined portion of said sample, and a photoelectric transducer disposed on the opposite side of said path for receiving the light transmitted through said area; said photoelectric transducer including a plurality of juxtaposed unit elements each producing an electric output proportional to the quantity of light impinging thereon; and a selection circuit responsive to the outputs from respective unit elements of said photoelectric transducer for selecting the output from a particular unit element corresponding to said predetermined portion of said sample irrespective of the deviation of the position of said sample from said path.

Where the condition of a paper money is to be inspected, the margin of the paper money may be used as said predetermined portion and where the sample is a printed matter printed with a definite pattern having adjoining bright and dark portions, an area covering both bright and dark portions may be used as said predetermined area.

Further objects and advantages of the invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a perspective view of one embodiment of this invention;

FIG. 2 shows a block circuit diagram of the embodiment shown in FIG. 1: and

FIG. 3 is an elevational view showing various positions of samples while they are being conveyed.

For the sake of description, in the following description it is assumed that the samples to be detected are paper moneys and that portions to be detected are their longitudinal side edges or margins.

As diagrammatically shown in FIG. 1, a paper money 10 has its central portion 11 printed with a prescribed pattern and a peripheral margin 12 not printed. Such margin is likely to be most spoiled or damaged so that by detecting the difference in the brightness thereof, spoilage can be readily detected. Further, the margin permits ready detection of repair as by lining or lap bonding. A conveyor device 13 for successively conveying paper moneys comprises a pair of juxtaposed belts l4 and rollers 15 for driving the belts at a constant speed. The width of the belts is selected such that most of the upper and lower side edges or margin 12 of the paper money being conveyed are exposed.

An optical detector 16 is located at a suitable position along the conveyor device 13. Detector 16 comprises a source of light, or a lamp 17 on one side of belts l4, and a photoelectric transducer 18 on the opposite side.

Condenser lenses

19 and 20 are disposed between lamp 17 and photoelectric transducer 18. The relative position between the lamp, lenses and photoelectric transducer is selected such that the light from lamp 17 is converted into parallel light beams, that a portion of the parallel light beams transmits through the margin 12 of the paper money whereas remaining parallel beams are directly directed to the photoelectric transducer 18 by lens 20. The photoelectric transducer 18 comprises an assembly of 24 unit elements 180, for example. Each unit element 18a has an area to receive light corresponding to an area of 1.0 X 0.8 cm of the paper money, for example. Accordingly, the unit element receiving the light directly from the lamp and the unit element receivingthe light that has transmitted through the margin of the paper money are positioned on the opposite sides of a particular unit element receiving the light that has passed by the longitudinal side edge 10a of the paper money. Thus, by detecting this particular unit element it is possible to determine the position of the side edge.

In the detection circuit shown in FIG. 2, unit elements 18a of photoelectric transducer 18 are designated as l8a(l), 18a(2) 18a(n) starting from the upper-most one. The output of each unit element is coupled to a level detection circuit that is a quantizing circuit 23 such as a Schmidt circuit. The output of each Schmidt circuit, for example the i-th Schmidt circuit 22(i), is connected to one input terminal of an AND circuit 24(i) through an inverter 23(1) whereas the other input terminal of AND circuit 24(i) is connected to the output of a Schmidt circuit corresponding to the next unit element, that is the (i 1)th Schmidt circuit 22(i 1). The output of AND circuit 24(i) is connected to one input terminal of another AND circuit 25(i), the other input terminal of the later AND circuit being connected to the output of the amplifier associated with a unit element preceding the unit element connected to said later AND circuit, that is the (i 1)th amplifier 21(i 1). With this arrangement, the portions of the margin 12 of the paper money 10 above line AB and corresponding to the (i l)th unit element l8a(i 1) are detected. Outputs of AND circuits 25 are connected to an OR circuit 26 and the output thereof is supplied to a comparator 28 together with the output from a reference signal generating circuit 27, which is constructed to generate a signal corresponding to a signal which is generated when said specified portions of a reference paper money above line AB are detected.

The device operates as follows:

Paper moneys l clamped between conveyor belts 14 take various positions with respect to belts during conveyance. More particularly, in addition to the normal position shown at a in FIG. 3 they assume various abnormal positions as shown at 10b to 10:2. When paper moneys at such various positions arrive at the detector 16, the light from lamp 17 is projected upon an area including the margin 12 of the paper money and adjacent regions. Thus, respective unit elements 18a of photoelectric transducer 18 receive the light from lamp 17 directly or through margins of the paper moneys. The quantizing level of each Schmidt circuit is selected such that the circuit 22 produces an output signal by the direct light but does not provide an output by the light transmitted through the margin of the paper money. By the action of lens 20, the light passed near the edge 10a of the paper money 10 forms an inverted image on respective unit elements 18a which produce outputs corresponding to the quantity of the light received which are supplied to Schmidt circuits 22.

More particularly, with reference now to FIG. 2, assuming that the outputs from unit elements 18a(i 1) and l8a(i) are smaller than the quantizing level and that the output from unit element l8a(i l) is larger than the quantizing level, Schmidt circuits 22(i l) and 22(1') will not provide any output whereas Schmidt circuit 22(i 1) will provide an output. Thus, an AND condition is not held for AND circuits 24(i 1) and 24(i l) but held for AND circuit 24(i) by the outputs from inverter 23(i) and Schmidt circuit 22(i 1), thus giving an output to the one input terminal of AND circuit 25(1'). Accordingly, an AND condition is held for AND circuit 25(i) by the output from amplifier 21(i l) and the output thereof is taken out through OR circuit 26. Accordingly, this output always corresponds to a region within a definite distance from edge 10a of the paper money. In other words, this output represents the optical output of the region above line AB. Thus, a given AND circuit 25 provides an output corresponding to a given unit element 18a irrespective of the variation in the positions of successive paper moneys being conveyed by the conveyor belts. The output from OR circuit 26 is compared with the reference signal from the reference signal generating circuit 27 by comparator 28. When there is a difference between these two signals, comparator 28 provides an output which is utilized to detect or remove an abnormal paper.

While in the embodiment described above, the longitudinal side edge 10a of a paper money 10 is utilized as a border line and the condition of the region within a predetermined distance from the edge 10a is detected optically, where the pattern printed on the sample contains bright and dark portions, in other words where there is a bordor line between adjacent regions having different transmissibility of light it is also possible to detect a particular portion of the sample spaced a definite distance from such border line in a direction parpendicular to the movement of the sample, e.g., a bright or dark image of the pattern.

In such a modified embodiment of this invention, the light from lamp 17 is adjusted to irradiate a given area of the pattern including the borderline and the quantizing level of the Schmidt circuit of the detection circuit is set to correspond to the quantity of light transmitted through the bright portion or margin of the sample and to the quantity of light transmitted through the dark portion or the printed pattern so as to produce an output from a unit element of the photoelectric transducer corresponding to the border line.

Further by the duplicate provision of the detector 16 it is possible to simultaneously inspect opposite edges AB and A'--B' of the margin 12.

What we claim is:

1. An optical detector for inspecting the condition of a sample comprising conveyor means for successively conveying said sample along a predetermined path; optical means including a source of light disposed on one side of said path for projecting light upon a predetermined area containing a predetermined portion of said sample, and a photoelectric transducer disposed on the opposite side of said path for receiving the light transmitted through said area; said photoelectric transducer including a plurality of juxtaposed unit elements each producing an electric output proportional to the quantity of light impinging thereon; and a selection circuit responsive to outputs from respective unit elements of said photoelectric transducer for selecting the output only from a particular unit element corresponding to said predetermined portion of said sample irrespective of the deviation of the position of said sample from said path.

2. An optical detector according to claim 1 wherein said sample comprises a printed matter having a definite pattern printed on the central portion and a not printed margin around its periphery.

3. An optical detector according to claim 1 wherein said sample comprises a printed matter printed with a definite pattern having relatively bright and dark portions divided by a definite border line.

4. An optical detector according to claim 2 wherein said light is projected upon an area including said margin and portions outside said margin.

5. An optical detector according to claim 4 wherein said samples are carried by said conveyor means with said margins exposed.

6. An optical detector according to claim 3 wherein said light is projected upon a predetermined area of said printed pattern including said bright and dark portions and said border line therebetween.

7. An optical detector according to claim 1 wherein said selection circuit comprises a plurality of quantizing circuits for quantizing the outputs from said plurality of unit elements of said photoelectric transducer, a plurality of first AND circuits, one of the inputs of each AND circuit being connected to the output of corresponding one of said quantizing circuits through an inverter while the other of said inputs being connected to the output of the next quantizing circuit, and a plurality of second AND circuits, one of the inputs of each second AND circuit being connected to the output of a corresponding one of said first AND circuit while the other input of said each second AND circuit being connected to the output of a preceding first AND circuit.

8. An detector device according to claim 6 wherein said selection circuit further comprises an OR circuit connected to the outputs of said second AND circuits.

9. An detector device according to claim 6 wherein said selection circuit further comprises a comparator which compares the outputs from said second AND cir cuit and a reference signal.

10. An detector device according to claim 8 wherein said reference signal represents a normal condition of said predetermined portion of said sample.

Claims

9. An detector device according to claim 6 wherein said selection circuit further comprises a comparator which compares the outputs from said second AND circuit and a reference signal.