US3732430A

US3732430A - Photoelectric scanning apparatus

Info

Publication number: US3732430A
Application number: US00184797A
Authority: US
Inventors: F Hujer; H Fengler
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1970-10-02
Filing date: 1971-09-29
Publication date: 1973-05-08
Anticipated expiration: 1990-05-08
Also published as: FR2110874A5; DE2048414A1; CH534393A; DE2048414B2

Abstract

A photoelectric scanning apparatus which detects one or more rows of information encoded in or on travelling webs or interconnected photographic films or prints has one or more pairs of mirror symmetrical light-conducting rods which are embedded in a support adjacent to the path of the web so that their axes intersect at a point of the path which is in line with the row of information to be scanned. The support is formed with two chambers each of which is located behind a different rod and each of which receives a removable clip. One of the clips contains one or more removable lamps and the other clip contains one or more removable photosensitive elements. A lamp in the properly inserted clip emits a light beam which passes through the respective rod and is normally reflected on the travelling web to thereupon pass through the other rod and to impinge on the photosensitive element behind the other rod. If the encoded information is in the form of notches or perforations, the reflection of light is interrupted whenever a notch or perforation register with the intersection of the axes of the rods whereby the photosensitive element generates a signal.

Description

United States Patent Hujer et a].

May 8, 1973 [54] PHOTOELECTRIC SCANNING APPARATUS [75] Inventors: Friedrich Hujer, Grunwald; Harald Fengler, Munich, both of Germany [73] Assignee: Agl'a-Gevaert Aktiengesellschaft,

Leverkusen, Germany [22] Filed: Sept. 29, 1971 [21] Appl. No.: 184,797

[30] Foreign Application Priority Data Oct. 2, 1970 Germany ..P 20 48 414.4

[52] US. Cl ..250/219 FR, 250/227 [51] Int. Cl. ..G01n 21/30 [58] Field of Search ..250/219 FR, 219 DC,

[56] References Cited UNITED STATES PATENTS 3,278,754 10/1966 Wallace ..250/219 DC 1,969,465 8/1934 Jones ..250/219 FR X 3,308,301 3/1967 Weissbach... ..250/219 FR 3,533,657 lO/1970 Da Silva ..250/219 DC 3,573,478, 4/1971 Stempler ..250/239 Primary ExaminerWalter Stolwein Attorney-Michael S. Striker [57] ABSTRACT A photoelectric scanning apparatus which detects one or more rows of information encoded in or on travelling webs or interconnected photographic films or prints has one or more pairs of mirror symmetrical light-conducting rods which are embedded in a support adjacent to the path of the web so that their axes intersect at a point of the path which is in line with the row of information to be scanned. The support is formed with two chambers each of which is located behind a different rod and each of which receives a removable clip. One of the clips contains one or more removable lamps and the other clip contains one or more removable photosensitive elements. A lamp in the properly inserted clip emits a light beam which passes through the respective rod and is normally reflected on the travelling web to thereupon pass through the other rod and to impinge on the photosensitive element behind the other rod. If the encoded information is in the form of notches or perforations, the reflection of light is interrupted whenever a notch or perforation register with the intersection of the axes of the rods whereby the photosensitive element generates a signal.

8 Claims, 3 Drawing Figures PI-IOTOELECTRIC SCANNING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to scanning apparatus in general, and more particularly to improvements in photoelectric scanning apparatus. Still more particularly, the invention relates to improvements in photoelectric scanning apparatus which can be used with advantage to detect information encoded on travelling bodies, such as webs of paper, photographic film or the like, or to produce signals in response to detection of brighter or darker spots or voids on or in the travelling bodies.

A drawback of presently known photoelectric scanning apparatus which are used for detection of information encoded on or otherwise present in travelling bodies is that all component parts of the scanning apparatus must be produced and mounted with a high degree of precision. Thus, the relative positions of the light source and the photosensitive transducer which is exposed to light emitted by the light source and normally reflected on the travelling body must be selected with a very high degree of accuracy. This presents serious problems whenever it becomes necessary to inspect, clean and/or replace the light source and/or the transducer. Thus, the dimensions of spare light sources and/or transducers must match exactly the dimensions of the light source and transducer which are in actual use, and the means for mounting such parts adjacent to the path for a travelling body must be designed with utmost precision to insure proper reflection of light on a predetermined area of the body, namely, on the area which carries a row of encoded data. Therefore, many photoelectric scanning apparatus are of the expendable type without any possibility of replacing a defective light source and/or transducer.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved photoelectric scanning apparatus wherein all parts which are likely to require inspection, cleaning and/or replacement are readily accessible and wherein minor or major differences between the dimensions of several removable component parts do not affect the accuracy of the scanning action.

Another object of the invention is to provide a photoelectric scanning apparatus which is particularly suited to scan information which is encoded on travelling webs of paper, photographic film or the like and which is capable of discriminating between two or more different types of information.

A further object of the invention is to provide a photoelectric scanning apparatus which can be installed in or on many existing machines, such as developing, printing, copying and packing machines for photographic film and/or photographic prints, to serve as a superior substitute for presently known scanning apparatus.

An additional object of the invention is to provide a scanning apparatus wherein one or more light sources and/or one or more transducers can be reached, in-

spected, cleaned and/or replaced by semiskilled or unskilled persons and which insures optimal guidance of travelling material at the scanning station or stations.

Still another object of the invention is to provide a photoelectric scanning apparatus which, though eminently suited for detection of information which is encoded in the form of opaque or bright symbols, is particularly suited for detection of perforations, holes, notches or like voids in a travelling sheet-like body.

The invention is embodied in an apparatus for photoelectrically scanning webs of flexible material, such as photographic films or paper strips, which are transported along a predetermined path. The apparatus comprises support means which is adjacent to one side of the path for a web, at least one pair of substantially rod-shaped mirror symmetrical light-conducting members which are mounted in the support means in such positions that the extensions of their axes intersect each other at a predetermined point of the path for the web, namely, at a point which is in line with a row of encoded data provided on the web and being intended to be scanned by the apparatus, a light source position ed behind one of the light-conducting members so that a beam of light which issues from such source and passes through the one member is normally reflected by a web in the path and impinges against the other member to pass lengthwise through such other member, and a photosensitive element positioned behind the other member to be exposed to reflected light. The absence of reflected light or the presence of such light can cause the element to produce signals which .are thereupon" amplified (if necessary) and used to control the transport, severing and/or other manipulation of the web.

The light-conducting members are preferably provided with smooth end surfaces which face the aforementioned'point in the path for the web and extend at vantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partly side elevational and partly sectional view of a photoelectric scanning apparatus which embodies the invention;

- FIG. 2 is a transverse vertical sectional view asseen' in the direction of arrows from the line II-II of FIG. 1;

and

FIG. 3' is a fragmentary partial plan view and partial horizontal sectional view of an insert which is utilized in the scanning apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS.

Referring first to FIG. 1, there is shown a frame or housing 101 which supports two rotary pressing rollers 3, 4, a pair of cooperating advancing rolls or wheels 6 7, and a block-shaped support 1. The latter has a convex guide surface 1a which is adjacent to and faces the undersides of the pressing rollers 3, 4. These rollers define with the guide surface la an elongated path for lengthwise transport of a web 2 which can constitute a series of spliced-together photographic customer films or a strip of paperconsisting of a succession of photographic prints. If the web 2 consists of a series of films, such films can be spliced together by uniting bands prior to introduction into a continuous developing machine. It is customary to provide such films with encoded information in the form of perforations or notches which are applied in the region of splices between successive films to allow for automatic detection of splices for the purpose of subdividing the web into discrete films which'are thereupon returned to customers. Furthermore, such web is normally provided with additional encoded information, such as notches, perforations or graphite marks, one for each film frame, to facilitate accurate positioning of film frames in a photographic printing or copying machine. Such encoded information is used in many photographic processing laboratories bedause it allows for rationalization of the developing, printing and sorting operation. As mentioned above, the information which is encoded in the region of splices is scanned subsequent to completion of the developing (and, if necessary, printing or copying) operation to allow for automatic detection of splices for the purpose of arresting the web at necessary intervals so as to separate the films from each other and to allow-for manual or automatic insertion of separated films into customer containers or envelopes. The information which is encoded in the region of each film frame is scanned in a printing or copying machine to allow for automatic stoppage of the web whenever a fresh film frame registers with the printing or copying station.

If the web 2 consists of a series of photographic prints which are obtained by reproducing theimages of film frames onto a photosensitive paper, the web is provided with encoded information in the region of each print so as to allow for automatic scanning of such information and, intermittent stoppage of the web for the purpose of severing successive prints from each other,

, for example, in order to allow for manual accumulation with a severing device, or to place the frame lines between successive photographic prints into register with a severing device,

The curvature of the convex guide surface la on the support 1 preferably corresponds to that of an are which forms part of a circle. It is preferred to provide the surfacela with one or more cutouts, especially if the web 2 consists of a series of films which are spliced to each other end-to-end, so that the surfaces at the undersides of the films are contacted only by two transversely spaced relatively narrow ribs lb (see particularly FIG. 2) each of which contacts the respective marginal portion of the adjacent film. The scanning station wherethe web 2 is scanned for the presence of absence of encoded information in the form of perforations, marginal notches, graphite marks or symbols which are exposed onto the photosensitive layers of films is located midway between the pressing rollers 3 and 4. Each of these rollers can be biased toward the adjacent portion of the guide surface la by one or more springs (not shown) or is mounted in such a way that it can rest on the adjacent portion of the web 2 by gravity. The direction in which the web 2 is transported lengthwise by the advancing rolls 6, 7 is indicated by an arrow 5. At least one of the advancing rolls 6, 7 is driven in a manner not forming part of the present invention and preferably in such a way that the drive can be arrested in response to signals produced by the improved photoelectric scanning apparatus on detection of encoded information. The pressing rollers 3, 4 produce a desirable braking action by biasing the-adjacent portions of the travelling web 2 against the stationary guide surface 1a to thus insure that the web follows the outline of the surface 1a and remains in its predetermined path during travel past the scanning station between the pressing rollers.

The guide surface 1a of the fixedly mounted support 1 is provided with three transversely spaced continuous uninterrupted grooves 1c (see particularly FIG. 2) each of which extends all the way between the two vertical edge faces of the support. The spacing of the grooves 1c from each other corresponds to the spacing of different types of encoded information on the travelling web 2. For example, a row of marginal notches in the web 2 can pass above the leftmost groove 10 of FIG. 2; a row of perforations may pass along the median groove. 10 of FIG. 2; and a second row of marginal notches can pass above the right-hand groove lc'of FIG. 2. One row of notches can denote successive film frames, the other row of notches can denote the splices between successive films of the web 2, and the perforations can denote customer data, such as account numbers, customer addresses, the number of prints desired, and/or other information. The improved scanning apparatus comprises three transverselyspaced photoelec-. tric detectors the first of which can detect the notches in one marginal portion, the second of which can detect the notches in the other marginal portion and the third of which can detect the perforations in the intermediate portion of the web 2. However, it is equally' possible to provide the improved scanning apparatus with a single photoelectric detector or with two,,four or more detectors, depending on the number of different data which are applied to the web. 7

Each detector of the scanning apparatus comprises two mirror symmetrical light-conducting members in the form of bars or rods 8 and 9. The front or upper end portions of each pair of light-conducting members (hereinafter called rods for short) extend beyond the bottom surface of the respective groove 1c toward but short of the adjacent point P of the path for the web 2-. The support 1 is provided with prefabricated bores le for reception of the rods 8, 9 and each such rod can be bonded to the support 1, for example, by resorting to a suitable adhesive. These rods may consist of vitreous or synthetic plastic material and the extensions of the axes of each pair of associated rods 8, 9 intersect'each other at the predetermined point P of the path for the web 2, namely, at that point which is in register with the row'of notches, perforations or other encoded information which is to be scanned by the respective detector. In the illustrated embodiment, the axes of the rods 8, 9 of each pair of associated rods make acute angles with a symmetry plane 2020 which is located midway between the rods 8, 9 and includes the point P in the path for the web 2 where the axes of such rods intersect each other. The front or

upper end surfaces

8a, 9a of the rods 8, 9 shown in FIG. 1 are normal to the axes of the respective rods and face the point P where such axes intersect each other in the path for the web 2. The

surfaces

8a, 9a are preferably smooth by being ground, polished or otherwise treated to a high degree of precision finish. The distance between the

front end surfaces

8a, 9a and the point P where the axes of the rods 8, 9 shown in FIG. 1 intersect each other preferably approximates or equals the diameter of a rod 8 or 9. The width of each groove 10 in the support 1 preferably at least equals but normally slightly exceeds the diameter of a rod 8 or 9.

The support 1 is further provided with two substantially slot-shaped

chambers

1d and 1d which are respectively located behind the rear end surfaces of the rods 8 and 9. The

chambers

1d, 1d are machined into the support 1 and extend at right angles to the plane of FIG. 1. The chamber 1d accommodates a removable insert or clip 10 which contains a battery of several (preferably three) light sources 12 in the form of electric lamps. The chamber 1d accommodates a similarly dimensioned block-shaped insert or clip 11 which contains several (preferably three) photosensitive elements or transducers 112 (one shown in FIG. 1). The insert 10 is formed with parallel bores 10a each of which receives one of the light sources 12 and the insert 11 is provided with similar bores (not specifically shown) for the photosensitive elements 112. As shown in FIG. 3, each light source 12 includes a transparent envelope surrounding a filament l2a-and having a front end portion 12b which constitutes a lens to focus the light beam issuing from the respective filament 12a upon the rear end surface of the respective rod 8 in the support 1. The rear or lower end portions of the light sources 12 have reduced diameters and are received in complementary portions of the respective bores 10a in the insert 10. The latter contains at least as many light sources 12 as there are rods 8 in the support 1, and the lens 12b of each light source is located behind the rear end surface of a different rod 8 when the insert 10 is properly accommodated in the chamber 1d of the support 1.

The dimensions of each photosensitive element or transducer 112 in the insert 11 preferably equal or approach the dimensions of a light source 12. Such transducers may also comprise transparent envelopes of glass or synthetic plastic material having lenticular upper end portions serving to focus reflected light onto a suitable photosensitive surface in the envelope. The narrower or smaller-diameter lower end portions of the light sources 12 and transducers 112 are just large enough to permit for proper introduction of suitable conductors which connect the light sources 12 with a source of electrical energy, not shown, and the transducers 112 with the device which receives signals from the respective detector (e.g., a severing device or a device which drives the advancing rolls 6, 7). The

inserts

10, 11 preferably (but not necessarily) resemble bricks and may be held in the

respective chambers

1d, 1d by friction or by suitable detent means, not shown. In the illustrated embodiment, the

inserts

10, 11 are respectively held in operative positions by tightening and retaining

screws

13, 14 shown in FIG. 1.

The operation:

The user threads the leader of a web 2 between the guide surface 1a of the support 1 and the pressing rollers 3, 4 and thereupon through the nip of the advancing rolls 6, 7. When the drive for the advancing roll 6 and/or 7 is started, the web 2 moves lengthwise in the direction indicated by the arrow 5 and follows closely the outline of the guide surface 1a so that its notches, perforations, graphite marks and/or other indicia can be properly scanned by the light beams issuing from the filaments 12a of light sources 12 in the insert 10. It is assumed that the light beam issuing from the source 12 behind the rod 8 of FIG. 1 impinges upon a row of perforations in the web 2. Such light beam impinges upon the web 2 at the point P and at an angle of 45 to the symmetry plane 2020 and is reflected at the same angle to pass through the rod 9 of FIG. 1 and to impinge upon the corresponding transducer 112. The curvature of the guide surface 1a on the support 1, combined with the biasing action of the pressing rollers 3, 4, prevents any transverse curling of the web 2 at the scanning station (point P), i.e., the web remains in its predetermined path; consequently, the beam of light issuing from the rod 8 at the front end surface 8a invariably finds an oncoming perforation and passes therethrough so that no reflection takes place and the corresponding transducer 112 produces a signal which is transmitted to the drive for the advancing roll 6 and/or 7 or to another device which receives signals from the detector including the rods 8, 9 of FIG. 1. If the web 2 consists of a series of spliced-together exposed and developed photographic films, the reflectivity of such films is highly satisfactory so that the difference between the amounts of light which reach the transducer 112 when a light beam is reflected on the web 2 and the amounts of light which reach the transducer 112 when the light beam issuing from the rod 8 can pass through a perforation at the point P is very pronouncedjThe lens at the upper or forward end of the envelope of the transducer 112 behindthe rod 9 of FIG. 1 focusses reflected light on the photosensitive surface whose resistance to the flow of electric current is very low in response to strong illumination and very high in the absence of illumination. The lens 12b on the envelope of the light source 12 behind the rod 8 of FIG. 1 focusses the light beam on the rear end surface of the rod 8. The fact that some stray light might reach the transducer 112 behind the rod 9 when the light beam issuing from the rod 8 and passing through a perforation at the point P cannot be reflected against the surface 9a of the rod 9 does not affect the accuracy of measurement because the amount of stray light is very small, particularly when compared with the amount of light which reaches the rod 9 when a perforation has moved beyond the point P. The signal produced by the transducer 1 12 can be readily amplified, shaped and/or otherwise processed to serve for regulation of the operation of one or more devices, such as the drive for the roll 6 and/or 7, a severing device for the web 2 or a counter of signals. The counter can be used to arrest the drive for the roll 6 and/or 7 in response to detection of a predetermined number of perforations, for example, if each film of the web 2 is to be subdivided into sections of predetermined length.

Dust or other foreign matter which is entrained by the web 2 and happens to descend onto the highly polished front end surfaces 811, 9a of the rods 8, 9 shown in FIG. 1 descends by gravity into the respective groove of the support 1. If the groove 1c is filled with dust, the additionally admitted dust is carried away by the underside of the web 2 without affecting the accuracy of the scanning action.

It was found that the positioning of rods 8, 9 in a manner as shown in FIG. 1 (at an angle of about 45 with reference to the symmetry plane -20) is a satisfactory compromise between a compact design and an optimum angle of reflection. The amount of reflected light is particularly high if the angles between 'the plane 20-20 and the axes of the rods 8, 9 are small.

An important advantage of the improved photoelectric scanning apparatus is that minor or even major deviations of the dimensions of light sources 12 and/or transducers 112 from a standard size do not appreciably affect the accuracy of the scanning action. This is attributed to the provision of light-conducting rods 8 9 which are firmly embedded in the support 1 so that their positions with reference to the path for the web 2 remain unchanged. Therefore, the exact positioning of lightsources 12 and transducers 112 behind the rear endsurfaces of the rods 8 and 9 is of lesser importance. It suffices if the dimensions of all light sources 12 approximate each other and if a light source 12 which is inserted in place of-a damaged light source assumes in the insert 10 a position which is at least close to the position of the previously employed light source. The same holds true for the transducers 112. It was found that even substantial differences between the distance from the rear end surface of a rod 8 to the filament "12a of a removed light source 12 and the distance from the rear end surface of such rod 8 and the filament 12a of a freshly inserted light source 12 cannot appreciably affect the'light guiding action of the rod 8 so that the accuracy of. the scanning action remains practically unchanged. This is of advantage because the replacement of a spent light source 12 or transducer 112 can be carried out by an unskilled attendant and the apparatus will continue to operateproperly even if the newly inserted part 12 and/or 112 is not in an optimum position with reference to the respective light-conducting rod.

As mentioned above, the improved scanning apparatus is susceptibleof many further modifications and can be used in connection with the scanning of a wide variety of travelling bodies. For example, the photosensitive element or elements can be designed to produce signals in response to reflection of light on opaque spots of a travelling paper web or the like, in response to detection of data which are exposed onto a web consisting of photographic films, or in response to detection of specially configurated perforations or notches. Furthermore, one detector of the scanning apparatus may be designed to produce signals in response to detection of opaque data and the other detector or detectors may be designed to produce signals in response to detection of bright spots, or vice versa.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omittingfeatures which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. Apparatus for photoelectrically scanning webs of flexible material, such as photographic films or paper webs, particularly to detect portions of reduced reflectivity, comprising support means having a convex guide surface defining a portion of an elongated path for webs of flexible material; means for advancing successive webs along said path in a predetermined direction; means for biasing the webs in said portion of said path against said guide surface; a light source removably mounted in said support means; a photosensitive element removably mounted in said support means; a first rod-shaped light-conducting member at least partially embedded in said support means between said light source and said guide surface to direct a beam of light which issues from said light source against the web at a predetermined point of said portion of said path whereby the web reflects said light beam; and a second rod-shaped light-conducting member at least partially embedded in said support means to direct said reflected light beam against said photosensitive element, each of said light-conducting members having a' smooth end face adjacent to said portion of said path and located in a plane which is substantially normal to the axis of the respective light-conducting member, the axes of said light-conducting members making identical acute angles with a plane which includes said point and is located midway between said light-conducting members.

'2. Apparatus as defined in claim 1, wherein the ex-I tensions of axes of said light-conducting members intersect each other at said point of said portion of said path. 3. Apparatus as defined in claim 1, wherein said sup port means is provided with chambers for said light source and said photosensitive element. v

4. Apparatus as defined in claim 1, wherein said means for biasing comprises at least one roller adjacent to said portion of said path opposite said guide surface.

5. Apparatus as defined in claim 1, wherein said guide surfaceis provided witha continuous groove through which the light from said source passes between said point and said members.

6. Apparatus as defined in-claim 5, wherein the width of said groove slightly exceeds the diameters of said members. I

7. Apparatus as defined in claim 1, further comprising at least one additional pair of light-conducting members in said support means, an additional light source behind one of said additional members and an additional photosensitive element behind the other of said additional members, said additional members reference to said first-mentioned point transversely of said path.

8. Apparatus as defined in claim 7, wherein said support means defines a first chamber behind said one members and a second chamber behind said other members, and further comprising a first insert removably accommodating said light sources and a second insert removably accommodating said elements, said first and second inserts being respectively received in said first and second chambers.

Claims

1. Apparatus for photoelectrically scanning webs of flexible material, such as photographic films or paper webs, particularly to detect portions of reduced reflectivity, comprising support means having a convex guide surface defining a portion of an elongated path for webs of flexible material; means for advancing successive webs along said path in a predetermined direction; means for biasing the webs in said portion of said path against said guide surface; a light source removably mounted in said support means; a photosensitive element removably mounted in said support means; a first rod-shaped light-conducting member at least partially embedded in said support means between said light source and said guide surface to direct a beam of light which issues from said light source against the web at a predetermined point of said portion of said path whereby the web reflects said light beam; and a second rod-shaped light-conducting member at least partially embedded in said support means to direct said reflected light beam against said photosensitive element, each of said light-conducting members having a smooth end face adjacent to said portion of said path and located in a plane which is substantially normal to the axis of the respective lightconducting member, the axes of said light-conducting members making identical acute angles with a plane which includes said point and is located midway between said light-conducting members.

2. Apparatus as defined in claim 1, wherein the extensions of axes of said light-conducting members intersect each other at said point of said portion of said path.

3. Apparatus as defined in claim 1, wherein said support means is provided with chambers for said light source and said photosensitive element.

5. Apparatus as defined in claim 1, wherein said guide surface is provided with a continuous groove through which the light from said source passes between said point and said members.

6. Apparatus as defined in claim 5, wherein the width of said groove slightly exceeds the diameters of said members.

7. Apparatus as defined in claim 1, further comprising at least one additional pair of light-conducting members in said support means, an additional light source behind one of said additional members and an additional photosensitive element behind the other of said additional members, said additional members being laterally offset with reference to said first-mentioned members so as to cause a light beam issuing from said one additional member to impinge on a web in said path at a second point which is offset with reference to said first-mentioned point transversely of said path.