US2962596A

US2962596A - Control system for the contactless scanning of textile webs and like sheet material

Info

Publication number: US2962596A
Application number: US764594A
Authority: US
Inventors: Leimer Albert; Zerle Ludwig
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-10-01
Filing date: 1958-10-01
Publication date: 1960-11-29
Anticipated expiration: 1977-11-29

Description

Nov. 29, 1960 LEIMER ETAL L) OF TEXTILE W Filed Oct. 1, 1958 FOR THE CONTACTLESS SCANNING EBS AND LIKE SHEET MATERIAL 2 Sheets-Sheet 1 CONTROL SY Nov. 29, 1960 A. LEIMER ET AL CONTROL SYSTEM FOR THE CONTACTLESS SCANNING Filed Oct. 1, 1958 OF TEXTILE WEBS AND LIKE SHEET MATERIAL 2 Sheets-Sheet 2 INVENTORS: ,uararze/ms/e 4 00 N16- 25/915 CONTROL SYSTEM FOR THE CONTACTLESS SCANNING OF TEXTILE WEBS AND LIKE SHEET MATERIAL Albert Leimer, Beimlerstr. 15, Augsburg, Germany, and Ludwig Zerle, Paarstr. .4, Mering, Germany Filed Oct. 1, 1958, Ser. No. 764,594

Claims. (Cl. 250-219) The present invention relates, in general, to control systems for travelling sheet material webs and, in particular, to a photoelectric apparatus for the contactless scanning control of the edges of the webs.

It is an object of the present system to provide means offering the possibility of completely eliminating the sensitivity of a control system to contamination by dirt, difference in photocell aging, a change in the voltage of the light source, etc.

It is another object of the present invention to provide means permitting the control of web-edge migrations by the quality of the light reflected by the web material rather than by light quantum.

It is another object of the present invention to provide means affording a zone of edge migration in which no control operation is effected.

It is another object of the present invention to provide' means contributing to a variation in the width of a zone of edge migration in which no control operation is effected.

It is another object of the present invention to provide means rendering it possible to control web-edge migrations through the use of an intermittent light source.

These and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings showing preferred embodiments of the invention.

In the drawings, which illustrate the best modes presently contemplated of carrying out the invention:

Fig. 1 is a more or less diagrammatic and schematic illustration, partly in section, of an apparatus pursuant to the present invention for use with sheet material which has an irregular or scattered light reflection characteristic;

Fig. 2 is a top plan view of the apparatus shown in Fig. 1;

Fig. 3 is a view similar to Fig. 1 for use with sheet material which has a uniform or regular light reflection characteristic; and

Fig. 4 is a schematic wiring diagram for the control apparatus shown in Fig. 1.

In contrast to prior art devices, which are based upon measurement of a quantum of light or the difference between two light quanta, the apparatus of the present invention utilizes the quality of the light reflected by the sheet material web to control the path of travel of the edge thereof.

The term light quality as used herein, does not refer to a certain constant wavelength or color, but to varying light of a preferably determined frequency. The present invention deals primarily with light which is varying in intensity, and, under. certain conditions, it deals also with light which is varying in frequency. A light source, which provides rhythmic light intensity variations, radiates its rays into the space or area in which photoelectric cells are to control the course or path of travel of the edge of the sheet material web. This area must be free of all other objects. When a sheet material web enters the States Patent scanned area, a portion of the light ray directed thereon by a light source is reflected by the web onto one or more photoelectric cells, depending upon the reflection factor or character of the material. The reflection may either be irregular or uniform. The light sources and photoelectric cells are so arranged and blocked off that direct radiation to the photoelectric cells is prevented. The photoelectric cells monitor or scan a conical portion of the area in front thereof. In webs formed of a material that provides regular reflection of light, for example in the case of sheet material as clear as glass, the longitudinal axis of the scanned conical area forms an angle with the plane of the web such that a light ray radiated from the light source to the web is reflected thereby to the photoelectric cell.

Referring now to Figs. 1 and 2 of the drawings in detail, there is shown a web-edge control system 60 pursuant to the present invention. A light source 1,. here shown as an incandescent lamp, is mounted over a sheet material web which is moving in the direction of the arrow 61. The light source is energized by an alternating current voltage supply so that the light rays vary in intensity in accordance with the frequency of the supply.

By means of a suitable rectifier 97 the current from the A.-C. source can be interrupted during one half cycle thereof, so as to increase the variation or flickering of the light rays. The photoelectric cell 4 is mounted above the Web and has a conical field of view 3 through which the web is moving in the direction of the arrow 61. By irregular or diffuse reflection from the upper surface 62 of the web, light rays from the lamp 1 are reflected to; the photoelectric cathode 8 of the cell 4. The light is reflected through a passageway 63 defined by an enclosed light tube or channel 6 provided with an apertured closure plate or diaphragm 5 having a restricted opening 64 which limits the field of view 3 of the photocell. The inner surface 65 of the tube 6 is formed of non-reflecting light absorbing material so that rays of light which impinge thereon, for example the light ray 7 reflected through opening 64, do not reach the photoelectric cell 4 which is mounted at the rear end of the tube 6. A second light, tube '10, having a front end aperture 65 in front end plate 11 and a photoelectric cell 9 at its rear end, is mounted laterally of tube 6 and is similar in all respects thereto.

In the condition of the parts shown in Fig. 1, there is nothing in the field of view 12 of the photoelectric cell 9 so that no light is reflected from web 2 through aperture 11 to the cathode 13 of the photoelectric cell. The photoelectric cells 4 and 9 control lateral adjusting devices, for moving the web or its edge in the direction of the arrows 66, through amplifiers and relays, as hereinafter described in detail. If the response points of these conventional lateral adjusting devices (not illustrated) are set to coincide with the

center lines

14 and 15 of the conical scanning or

viewing fields

3 and 12, respectively, of the photoelectric cells 4 and 9, respectively, the distance or section represented by the arrows 52 between said center lines represents the range or zone of lateral excursion or migration of the web edge 16, within which the edge can move in the direction of the arrows 66 without effecting the energization or operation of a lateral adjusting device. The broken line 17 in Fig. 1 represents a fixed vertical axis between the light tubes 6 and 10. If said tubes are mounted so that they can be adjustably rotated about said axis 17, the response points for the lateral adjusting devices, which coincide with the

center lines

14 and 15, respectively, can be moved as close to each other as desired, i.e. the distance 52 can be reduced, as will be readily apparent from Fig. 2.

More specifically, viewing Fig. 2, when the cells '4 and 9 are rotated in a clockwise direction as indicated at M about the axis 17, the

center lines

14 and 15 will each approach the edge 16 in opposite directions so as to W reduce the extent of the range 52.

Referring now to Fig. 3 in detail, there is shown another embodiment of a control system 67 pursuant to the present invention. In this embodiment a light source 18, energized from an A.-C. source, radiates its light rays onto the upper surface 68 of a web 20 which is moving perpendicular to the plane of the drawing, as in Fig. l. The web 20 is formed of material having a very high reflection characteristic so that the reflection from surface 68 is uniform and not uneven or irregular as in the case of surface 62 of web 2. For the purpose of simplicity, only one photoelectric cell 19 is illustrated. In order to limit the field of view or conical monitoring area 21 of the photoelectric cell, provision is made for an optical system comprising a lens 22 and a diaphragm 23 interposed between the lens and the photoelectric cell, the diaphragm having a central aperture 69. The axis 27 of the optical system intersects the web 20', at such an angle that a light ray 53 radiated from the source 18 has such an angle of incidence to provide an angle of emergence which is such that the reflected ray 54 is coincident with the axis 27.

The lens 22 produces an image of the web 20, within the field of view 21, in the plane of the diaphragm 23 at the aperture 69 thereof. By changing the diameter of the aperture 69, it is possible to precisely limit the field of view of the photoelectric cell 19. The baffle or partition 26 is interposed between lamp 18 and photoelectric cell 19 to prevent light rays from being radiated directly to the photoelectric cathode 24.

1 Referring now to Fig. 4 in detail, there is shown a wiring diagram of the control system 60. As previously described, the light source -1 is connected to an A.-C. source 70 and light rays therefrom impinge upon the sheet material web 2 from which they are reflected into the light tubes 6 and through

openings

64 and 65 to energize the photoelectric cells 4 and 9. The varying light rays produce A.-C. voltage outputs at the photoelectric cells. Photocell 4 developes its output signal voltage across load resistor 28 and photocell 9 developes its output signal voltage across load resistor 29. The output signal voltage of cell 4 is applied through a coupling condenser 30 to the control grid 71 of the triode 32. The output signal voltage of cell 9 is applied through coupling capacitor 31 to the control grid 72 of the triode 33.

The signal voltages are amplified in the respective tubes and the tube outputs are applied through coupling capacitors 34 and 35 to rectifier networks 73 and 74, respectively. Network 73 comprises

rectifiers

36 and 37 connected in opposition to condenser 34 and condenser 38 in parallel with rectifier 37. Network 74 comprises

rectifiers

39 and 46 connected in opposition to condenser 35 and condenser 41 in parallel with rectifier 40. It will be noted that each of the

tubes

32 and 33 is cathodebiased by a resistor 75 and a bias cell 76. The resistors 77 are conventional grid voltage dropping resistors. The resistors 78 are conventional plate load resistors for the

tubes

32 and 33 across which their output voltages are developed. The alternating voltage outputs of

tubes

32 and 33 are rectified by their associated rectifier networks 73 and 74 and'charge the condensers 38 and 41. The charges on these condensers are applied as negative biases to the

control grids

79 and 86 of the

triodes

42 and 43, respectively. The grid resistors for said tubes are indicated at 81 and 82 connected to the reference potential line 83. A suitable plate voltage supply for

tubes

32 and 33 is'connected between terminals 84 and a suitable plate voltage supply for

tubes

42 and 43 is connected. between terminals 85.

A relay 44, which operates the relay contacts 46 con stitutes the plate load for tube 42 and the relay 45, which operates the relay contacts 47, constitutes the plate load for tube 43. The contact .6 a e n rm y p n a the contacts 47 are normally closed. When contacts 46 are closed a coil 48 is connected to a suitable voltage supply which is connected between the terminals 86. When the contacts 47 are closed a coil 49 is connected to said voltage supply. The

coils

48 and 49 operate a conventional contact mechanism 50 which may be a reversing relay. A reversing motor 51 is energized through the contact mechanism 50 in conventional manner. The motor 51 operates a conventional adjusting mechanism (not illustrated) for moving the web transversely of the direction of arrow 61 in Fig. 2.

The control system 60 operates as follows: If the Web 2 is not'in a position to reflect light to the photoelectric cells, there are no signals applied to

tubes

32 and 33 so that condensers 38 and 41 are not charged and

tubes

42 and 43 are not blocked and remain conductive. As a result, the relays 44 and 45 are both energized so that the normally open contact 46 is closed and the normally closed contact 47 is open. As a result, coil 48 is energized and operates the reversing relay 50 to energize the motor 51 for clockwise rotation, as shown by arrow I; The motor now operates the web-adjusting mechanism so that the web is moved in the direction of arrow 87 As soon as the web has been moved sufli in Fig. 1. ciently to reflect light to the photocell 4, the condenser 38 is charged, tube 42 is cut off and relay 44 is de-energized so that contact 46 opens and interrupts the circuit of coil 48 to stop the motor. Thereafter, if the edge 16 migrates sufficiently in the direction of arrow 87 to reflect light to photocell 9 so that both cells are now energized, the condenser 41 is now also charged so that tube 43 is cut off and relay 45 is de-energized. This causes contact 47 to close to complete the circuit for coil 49 and energizes reversing relay 50 to energize motor 51 for counterclockwise rotation, as shown by arrow II. This energizes the adjusting mechanism to move the web 2 in the direction of the arrow 88 in Fig. 1. When the web has been moved out of the viewing field 12 of cell 9 so that it is only in the viewing field 3 of cell 4, as shown in Fig. 1, no light is reflected to cell 9 but light is still reflected to cell 4. As a result, the tube 43 is rendered conductive again, contact 47 is opened to dc-energize coil 49 and interrupt the motor.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims. Having thus described the invention, what is claimed asnew and desired to be secured by Letters Patent, is:

1. A control system for the contactless scanning of sheet material webs comprising'photoelectric means disposed to scan a marginal edge of the Web and disposed at one side thereof, a source of intermittent light rays disposed at said one side of the web to shine light thereon forfreflection to said photoelectric means, means to prevent direct radiation of light from said source to said photoelectric means, said photoelectric means comprising a pair of laterally related photoelectric devices each having a predetermined field of view, and the axes of said fields of view defining a predetermined range of migration of the marginal edge of the web within which a lateral web adjustment is not required, each photoelectric device being mounted at one end of a light tube having a light opening at the other end for limiting the associated field of view, each tube having a light absorbing inner surface.

2. A control system for the contactless scanning of sheet material webs comprising photoelectric means disposed to scan a marginal edge of the web and disposed at one side thereof, a source of intermittent light rays disposed at said one side of the Web to shine light thereon for reflection to said photoelectric means, means to prevent direct radiation of light from said source to said photoelectric means, said photoelectric means comprising 'a pair of laterally related photoelectric devices each having a predetermined field of view, the axes of said fields of view defining a predetermined range of migration of the marginal edge of the Web within which a lateral web adjustment is not required, and means mounting said photoelectric devices for rotation about a fixed vertical axis therebetween to vary said predetermined range and to adjustably position said light tubes relative to the marginal edge, each photoelectric device being mounted at one end of a light tube having a light opening at the other end for limiting the associated field of view.

3. A control system for the contactless scanning of sheet material webs comprising photoelectric means disposed to scan a marginal edge of the web and disposed at one side thereof, a source of intermittent light rays disposed at said one side of the web to shine light thereon for reflection to said photoelectric means, means to prevent direct radiation of light from said source to said photoelectric means, said photoelectric means comprising a pair of laterally related photoelectric devices each having a predetermined field of view, the axes of said fields of view defining a predetermined range of migration of the marginal edge of the Web Within which a lateral Web adjustment is not required, and means mounting said photoelectric devices for rotation about a single axis to vary said predetermined range, each photoelectric device being mounted at one end of a light tube having a light opening at the other end for limiting the associated field of view, said range-varying means being means to adjustably position said light tubes relative to the Web edge.

4. A control system for the contactless scanning of sheet material Webs comprising photoelectric means disposed to scan a marginal edge of the web and disposed at one side thereof, a source of intermittent light rays disposed at said one side of the web to shine light thereon for reflection to said photoelectric means, means to prevent direct radiation of light from said source to said photoelectric means, said photoelectric means comprising a pair of laterally related photoelectric devices each having a predetermined field of view, the axes of said fields of view defining a predetermined range of migration of the marginal edge of the web within which a lateral web adjustment is not required, means for moving the web in opposite directions laterally thereof, means to energize said moving means for operation in a first direction when no light is reflected to both said photoelectric devices and in an opposite direction when light is refiected to both said photoelectric devices, means to deenergize said moving means when light is reflected to one only of said photoelectric devices, and means mounting said photoelectric devices for rotation about a fixed vertical axis therebetween to vary said predetermined range and to adjustably position said light tubes relative to the marginal edge, each photoelectric device being mounted at one end of a light tube having a light opening at the other end for limiting the associated field of view.

5. A control system as defined in claim 4, further characterized in that said light source includes means for energizing said light source from an A.-C. source, and a rectifier interposed between said sources.

References Cited in the file of this patent UNITED STATES PATENTS 2,196,893 Berry Apr. 9, 1940 2,208,447 Berry July 16, 1940 2,220,736 Stockbarger et a1 Nov. 5, 1940 2,246,501 Bradner et a1. June 24, 1941 2,295,327 Bendz Sept. 8, 1942 2,445,041 Scholz July 13, 1948 2,566,399 Bishop Sept. 4, 1951 2,810,316 Snyder Oct. 22, 1957