US3672143A

US3672143A - Doffing apparatus and method

Info

Publication number: US3672143A
Application number: US82455A
Authority: US
Inventors: William R Whitney
Original assignee: Leesona Corp
Current assignee: Leesona Corp
Priority date: 1970-10-20
Filing date: 1970-10-20
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

A spinning frame has a plurality of stations for spinning roving into yarn and winding the yarn onto a bobbin. A tender moves passed the stations and stops at any of the stations requiring servicing such as, for example, doffing a filled bobbin and donning an empty bobbin. The tender then continues patrolling the stations until it comes upon another station requiring servicing. As the tender patrols the stations, a first sensing device on the tender scans the stations to determine whether or not the yarn is advancing normally and provides an appropriate signal. A signal from a second sensing device indicates whether or not the station is operational. The signal from the first sensing device is combined with the signal from the second sensing device to stop the tender only at an operational station requiring servicing, whereupon the servicing cycle commences. At the end of servicing, if the yarn is advancing normally the tender resumes its patrolling. If the yarn is not advancing properly, another servicing cycle is commenced. Thereafter, if the yarn is still not advancing properly, the roving is automatically broken above the usual drafting rolls of the station as a signal flag is positioned to indicate to the second sensing device that the particular station is non-operational. The tender is not stopped at a non-operational station. The two sensors may both be phototransducers. The first sensor provides a particular fluctuating signal responsive to a transverse alternating motion of the yarn which results from ballooning of the yarn as it is advanced longitudinally while being wound onto the bobbin, and this signal results in the tender passing the station and continuing its patrolling. All other fluctuating signals from the first sensor, such as may be caused by ambient light, either day light or artificial light, for example, as well as signals resulting from movement of the tender while patrolling the stations, are filtered out.

Description

United States Patent Whitney 51 June 27, 1972 [54] DOFFING APPARATUS AND METHOD [72] Inventor:' William R. Whitney, Cranston, R.1.

[73] Assignee: Leesona Corporation, Warwick, RJ.

[22] Filed: Oct. 20, 1970 [21] Appl. No.: 82,455

[52] US. Cl. ..57/53, 57/34 R, 57/81, 57/156 [51] Int. Cl. ..D01h 9/10 [58] Field ofSearch ..57/34 R,53, 156,81; 242/37 R, 35.5, 35.6

[56] References Cited UNITED STATES PATENTS 2,716,004 8/1955 Reiners et al. ..242/37 3,373,551 3/1968 Gillon et a1. ..57/34 Primary Examiner-Wemer 1-1. Schroeder Attorney-Albert P. Davis and Burnett W. Norton [57] ABSTRACT A spinning frame has a plurality of stations for spinning roving into yarn and winding the yarn onto a bobbin. A tender moves passed the stations and stops at any of the stations requiring servicing such as, for example, doffing a filled bobbin and donning an empty bobbin. The tender then continues patrolling the stations until it comes upon another station requiring servicing. As the tender patrols the stations, a first sensing device on the tender scans the stations to determine whether or not the yarn is advancing normally and provides an appropriate signal. A signal from a second sensing device indicates whether or not the station is operational. The signal from the first sensing device is combined with the signal from the second sensing device to stop the tender only at an operational station requiring servicing, whereupon the servicing cycle commences. At the end of servicing, if the yarn is advancing normally the tender resumes its patrolling. if the yarn is not advancing properly, another servicing cycle is commenced. Thereafter, if the yarn is still not advancing properly, the roving is automatically broken above the usual drafting rolls of the station as a signal flag is positioned to indicate to the second sensing device that the particular station is nonoperational. The tender is not stopped at a non-operational station. The two sensors may both be phototransducers. The first sensor provides a particular fluctuating signal responsive to a transverse alternating motion of the yarn which results from ballooning of the yarn as it is advanced longitudinally while being wound onto the bobbin, and this signal results in the tender passing the station and continuing its patrolling. All other fluctuating signals from the first sensor, such as may be caused by ambient light, either day light or artificial light, for example, as well as signals resulting from movement of the tender while patrolling the stations, are filtered out.

17 Claims, 8 Drawing Figures PATENTEU JUN 2 7 1212 SHEET 10F 2 26 1] FlG.l

INVENTOR WILLIAM R. WHITNEY FIGZ ATTORNEYS WENIEBJUW 1272 3,672,143

SHEET 2 or 2 k A l/Ol IOI '0' 9* FIG. 5

IOG

F I e. 6

FIG. 8 F G 7 INVENTOR.

WILLIAM R. WHITNEY ATTORNEYS DOFFING APPARATUS AND METHOD This invention relates to a dofling apparatus and method and, more particularly, to such apparatus and method for dofimg strand processing equipment.

The following Leesona Corporation patents and patent applications are of interest and are incorporated by reference: US. Pat. No. 3,403,866, granted Oct. 1, 1968; U.S. Pat. No. 3,449,902, granted July 7, 1969; and U.S. Pat. No. 3,498,039, granted Mar. 3, 1970; and cospending US. patent applications Ser. No. 884,960, filed Dec. 15, 1969; and Ser. No. 877,678, filed Nov. 18, 1969.

As used herein the term yarn" means any strandular material, whether textile or otherwise; the term bobbin" is used in a general sense to include anything on which yarn may be wound, such as a bobbin core, either filled or partially filled with yarn; and the term signal" means the presence or absence of a transmission.

Automatic operation of a spinning or twisting machine is disclosed in the previously noted Leesona corporation US. Pat. No. 3,403,866 which is directed to a servicing tender for patrolling or scanning a series of bobbin winding stations of the machine. The tender includes a control system for initiating servicing of any station requiring attention. More particularly, the tender stops at a station to doff a full bobbin, or in the event of disruption of the advancing strand of yarn to the bobbin, to remove the partially filled bobbin, and in either event then donns an empty bobbin core and initiates winding of the strand onto the core. Should the tender be unable to adequately service the station, the station is rendered nonoperational and thereafter the tender by-passes the station until the station is again placed in operational condition.

Another previously noted Leesona Corporation U.S. Pat. No. 3,498,039 discloses an optical electronic control system for the tender. The control system has a phototransducer responsive to an indicator at each station for providing an operational signal when the station is in operational condition and other phototransducers for providing a servicing signal when the station requires servicing, either because the bobbin is fully wound and requires doffing, or because of an interruption in the strand along the path to the bobbin. Responsive to these two signals, a work cycle of the tender is initiated. Ifthe tender is unable to adequately service the station, it automatically operates a roving breaker which breaks the roving upstream of drafting rolls of the station. In its normal or operational position, the roving breaker serves as the indicator for the operational signal and when in its strand breaking position the operational signal is not provided.

While interruption of the advancing strand, as by a break in the strand, has been detected as noted above, a stationary or fluttering strand has not been entirely satisfactorily differentiated from a normally advancing strand.

The invention is, in brief, directed to a doffing apparatus and method for strand processing equipment including at least one station at which normal longitudinal advancement of a strand is accompanied by a transverse motion of the strand and responsive to not sensing the transverse motion, servicing of the station is regulated. Servicing is provided by a patrolling tender, and following servicing of a station, patrolling of the tender is resumed. If the servicing attempt is unsuccessful, the station is rendered non-operational and patrolling of the tender is resumed. Sensors on the patrolling tender scan the stations and if a station is operational and requires servicing a control system responsive to the sensors causes the tender to stop at the station requiring servicing. One of these sensors provides a signal indicating whether or not a station is operational and this signal is used in conjunction with a fluctuating signal responsive to the transverse motion of the strand, for regulating operation of the tender.

It is a primary object of this invention to provide a new and improved doffing apparatus and method.

Another object is provision of a new and improved doffing apparatus and method for strand processing equipment with provision for normally advancing a strand onto a bobbin at a station, provision for dofifing the bobbin at the station, and provision for sensing whether or not the strand is advancing at the station and responsive thereto controlling dofi'mg of the bobbin at the station. A related object is provision for normally longitudinally advancing the strand at the station and concurrently therewith imparting to the strand a particular range of transverse alternating motion, sensing whether or not the strand is advancing by providing various outputs and responsive to the aforementioned transverse motion of the strand providing a particular one of the outputs for regulating doffing of the station. Another related object is provision of a plurality of such stations and, provision for scanning the stations and responsive to the various outputs controlling doffing of the bobbin at the station being scanned. Further related objects include: providing the particular output in the form of a particular fluctuating signal, passing the particular fluctuating signal and responsive thereto providing a signal for dofling of the bobbin at the particular station; provision for determining whether ornot the strand is in operational condition to be advanced and when the strand is in such condition providing another signal, and responsive to receiving both the operational signal and the particular fluctuating signal, by-passing doffing of the station; and apparatus having a phototransducer for scanning the stations and providing the fluctuating signal, the phototransducer having either: only one photosensitive area for receiving an image of the transverse motion of the strand to provide the fluctuating signal, or a photosensitive area having a plurality of particular photosensitive areas of greater sensitivity than intervening areas,or a plurality of discrete photosensitive areas for receiving an image of the transverse motion of the strand, such areas receiving at most the,

image of only a limited portion of the transverse span of motion of the strand.

These and other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which:

FIG. 1 is a fragmentary, schematic plan view. of a preferred embodiment of a spinning machine, with parts broken away and removed, generally as indicated along the line 1-1 in FIG. 2;

FIG. 2 is a fragmentary sectional view taken generally along the line 2-2 in FIG. 1;

FIG. 3 is a fragmentary sectional view taken generally along the line 3-3 in FIG. 2;

FIG. 4 is an electrical diagram of. a portion of a control system for the machine;

FIGS. 5 and 6 are facial views of phototransducers which may be provided in the control system;

FIG; 7 is a wave form graph; and

FIG. 8 is an electrical diagram of a portion of another control system for the machine.

Referring to FIG. 1 of the drawings, a spinning frame 10 includes a base 12 on which a series of spindles 14 are suitably joumaled and rotated, one at each of a plurality of stations 16. Each spindle l4 removably mounts a bobbin core telescoped on the spindle and on which a strand of yarn is wound to form a package such as a bobbin 18.

As is more fully discussed in the aforementioned U.S. Pat. No. 3,403,866, in order to scan the bobbins l8 and to service stations 16 requiring attention, a pair of parallel tracks 20 are mounted on the base 12 and receive wheels 22 of a tender in the form of a carriage 24 mounted to traverse back and forth on the tracks past the stations 16. The carriage wheels 22 are suitably joumaled on a carriage body 26 and, more particularly, a pair of the wheels 22 at the right end of the carriage body 26 are fixedly mounted on a shaft 28 received in journals 30 on the carriage body. This shaft has fixed thereto a driven pulley wheel 32 connected by a timing belt 34 with a drive wheel 36 of a suitable reversible air motor 38 mounted on the carriage body 26. As the carriage 24 moves toward the right end of its tracks 20, a pivoted actuator 40 of a switch 42 mounted on the carriage body 26 engages an abutment 44 on the base 12 to reverse the position of the switch actuator 40 and thereby the direction of the carriage 24, and at the left end of the tracks 20 the actuator 40 engages another abutment 46 to again reverse the carriage. The switch 42 is connected in circuit (FIG. 4) with a four-way solenoid valve 48 so that when the switch actuator engages one of the abutments, the solenoid valve is energized to reverse operation of the motor 38, and when the switch actuator engages the other of the abutments, the solenoid valve is taken out of circuit to again reverse the direction of operation of the air motor, thus causing the carriage 24 to traverse to and fro past the bobbins 18 being wound at the stations 16.

During normal operation of the machine, roving 49 (FIG. 2) advances downwardly through a trumpet guide 50 and a set of drafting rolls 52, then past an inlet in a vacuum duct 54 for receiving and removing the roving in the event of breakage downstream of the drafting rolls. The roving 49 is spun into yarn 55 and the yarn passes through a lower yarn guide 56 centered above the bobbin 18 and the rotating spindle l4, and from the lower guide 56 the yarn passes through a traveler 58 on a ring 60 encircling the bobbin l8 and mounted on a ring rail 62 (FIG. 2) which moves up'and, down as the yarn 55 is advanced from the traveler 58 and is wound onto the bobbin. The parts 50-54 and 56-62 are all suitably mounted on the base 12.

As the yarn is advanced longitudinally it has imparted to it a concurrent transverse oscillatory movement or balloon 62 (FIGS. 2 and 3) between the drafting rolls and the lower guide. This oscillatory movement provides an image having a transversely alternating motion. The frequency and amplitude of the alternating motion will vary depending on the amount of yarn wound on the bobbin.

In keeping with established practice, the trumpet guides 50 at each station are mounted on a horizontally movable bar 63 which is usually automatically reciprocated, as indicated by the arrow 63A in FIG. 3, so that the roving 49 is moved to and fro across the drafting rolls to avoid grooving the rolls.

If the station 16 is in operational condition, an indicator in the form of a roving breaker 64 is in an operational position as indicated by the solid lines in FIG. 2. The roving breaker 64 is pivoted at its lower end to a suitable fixed support 66 of the machine and carries suitable means, such as a plurality of pins 68, for engaging the roving 49 above the trumpet guide 50 when the roving breaker 64 is pivoted to a position against a frame member 70 as indicated by dotted lines in FIG. 2. Movement of the roving breaker 64 from its operational to its non-operational position may be effected in any suitable manner, and as illustrated in FIG. 2 is effected by opening a shutoff valve 72 to project a jet of air from a tube 74 fixed on the carriage body 26 and aligned with the roving breaker in its operational position, with the carriage in its servicing position at a station. Opening of the valve 72 may be controlled in any desired manner, for example by a suitable signal as disclosed in the aforementioned U.S. Pat. No. 3,403,866.

As the carriage 24 is moving past a station 16, an opera tional signal is provided by a suitable phototransducer unit 76 fixedly mounted on the carriage body 26 and energized by a ray of light 78 originating from a suitable lamp 80 fixed on the carriage body and reflected off of the roving breaker 64 when the roving breaker is in its operational position as shown by solid lines in FIG. 2. This signal, combined with a servicing signal starts the work cycle of the carriage 24. The servicing signal may be provided either by a second or advancing yarn phototransducer unit 82 fixed on the carriage body 26 and receiving a ray of light 84 from a lamp 86 fixed on the carriage body and reflected off of the advancing and therefore ballooning yarn 55 at a point between the drafting rolls 52 and the lower yarn guide 56 and passing through a suitable lense unit 87 to provide a strand interruption signal, or by a full bobbin signal from a phototransducer assembly (not shown) fixed to the carriage body 26, as is more fully described in the previously noted patent application Ser. No. 877,678.

Referring to FIG. 4, the operational signal phototransducer unit 76 is connected through an amplifier 1A with a relay IR and upon energization of this unit a normally open switching means, such as a contact 1R1 of the relay 1R closes. If the roving breaker 64 is in its non-operational position, as shown by dotted lines in FIG. 2, the operational signal phototransducer unit 76 is not energized and the relay contact 1R1 remains open.

When the yarn 55 is advancing properly to the bobbin, the advancing yarn phototransducer unit 82 provides a servicing signal (to be described later) which is received by a circuit, to be described later, and through a resultant control signal a relay 2R is energized and opens its normally closed switching means, such as a contact 2R1, which is in series with the contact 1R1. If the contacts IR] and 2R1 are closed, a starting signal is provided to a control unit 96 of the carriage 24 causing the carriage to stop at the station 16 requiring service and to proceed with servicing of the station, as described in the previously mentioned U.S. Pat. No. 3,403,866. Otherwise, if either contact 1R1 or 2R1 is open, the carriage continues its patrolling operation and passes the station.

The portion of the control system for determining whether or not the yarn is advancing properly to the bobbin includes the previously noted phototransducer unit 82 which may be a plurality of phototransducers (FIGS. 1-5) or a single phototransducer unit 98 (FIG. 6). As shown in FIGS. 4 and 5, a plurality of (four) phototransducers, 100, each having a sensitive area 101, pass various outputs or servicing signals to an OR gate 102 from which the signals pass to a filter 104. The filter pases only a particular one of the signals to an electronic switch 106 which, upon receiving the particular control signal, energizes the relay 2R to open its normally closed contact 2R1.

If only one phototransducer 98 is provided, as in FIG. 6, the OR gate may obviously be eliminated from the circuit, but the remainder of the circuit remains the same as is shown in FIG. 4. The phototransducer unit 98 has but one photosensitive area 108, but this area has a plurality of (four) generally parallel and interconnected portions 110 of greater sensitivity than the intervening areas 112. The portions 110 are transverse, and preferably normal to the path of the tender.

In FIG. 7 the upper curve shows components of the servicing signal from a normally advancing and ballooning yarn 55, and these components are passed by the filter 104. The lower curve shows a typical signal from a stationary yarn, and this signal is not passed by the filter.

In a typical mill installation, light strikes the phototransducer unit from many sources. This light may be sunlight or artificial light, either direct or reflected from various parts of the apparatus. Sunlight and artificial illumination operated from direct current does not fluctuate in intensity. Most mill illumination uses 60 cycle per second alternating current which causes the ambient light intensity to fluctuate times per second.

In order to generate a fluctuating signal which can be discriminatedagainst the ambient background, the width of the sensitive area 101 (FIG. 5) of each phototransducer 100 and the spacing between the sensitive areas, in the direction of movement of the unit 82, must be smaller than the optically projected width of the smallest diameter of the balloon 63 observed by the sensitive areas 101. The maximum width is equal to the product of the minimum balloon diameter times the magnification ratio of the optical system. For a minimum diameter of three thirty-second inch and a magnification ratio of H3, the maximum width is one thirty-second inch. If the traveler is rotating at 200 r.p.s. and the image of the yarn is projected on the transducer for less than its full width and then returns over the same path, the output will be equal to the traveler rotation rate or 200 pulses per second. If the image is projected so that it completely traverses the phototransducer and goes into the insensitive area and then returns across the transducer sensitive area, again the output will fluctuate at a rate double that of the traveler rate or 400 pulses per second.

In FIG. 8 a simplified phototransducer portion of the FIG. 4 circuit is diagrammed for a tender preferably having a lineal speed as it approaches a station of 9 inches per second. Therein, a phototransducer unit 114 has but one transducer with a single sensitive area smaller than the smallest normally possible balloon 63, as previously discussed. If desired the unit 114 may have a plurality of sensitive areas, as previously described. The unit 114 may be a Motorola MRD 150 phototransistor, and is connected in the circuit as shown, in which: a Darlington Amplifier configuration 118 is General Electric part No. 2N5306; and

transistors

120 and 122 are General Electric part No. 2N 5354 and 2N5027, respectively; resistors 124 are 0.5M; resistors 126 are lOM; resistor 128 is 16.8K; and resistors 130 are 6.8K; and capacitors 132 are 0.1MFD; and capacitor 134 is 4MFD. A power supply of 12-14 volts D.C., for example, is provided between

connectors

136 and 138 and a control or output signal is provided between

connectors

138 and 140.

The phototransducer unit (82 or 98) will provide various outputs or fluctuating signals from the various sources of light which may be reflected from the advancing yarn or other parts of the equipment, but only the particular output within a particular frequency and amplitude range, resulting from the image reflected from the ballooning yarn will be passed by the filter for actuating the electronic switch to stop the tender and start servicing of the station.

When a first servicing cycle at a station is completed and the yarn is advancing normally, the phototransducer unit again provides the particular signal whereupon the relay 2R is energized and opens its contact 2R1 to drop the control unit out of circuit and the carriage resumes its patrolling. As the carriage moves on, the operational phototransducer unit moves away from its roving breaker target and the relay IR is, taken out of circuit, opening its contact 1R1 which remains open until another target causes the cycle to be repeated. As described in the previously noted patent, U.S. Pat. No. 3,403,866, if the first servicing cycle was not successful, the control unit cause the service cycle to be repeated, and if the yarn is still not advancing normally to the bobbin after the second cycle, the control unit causes the roving breaker to break the roving, and causes the tender to continue its patrolling and scanning of the stations and to by-pass any station on which the indicator flag hasbeen dropped, as previously described.

While this invention has been described with reference to particular embodiments in a particular environment, various changes may be apparent to one skilled in the art and the invention is therefore not to be limited to such embodiments or environment except as set forth in the appended claims.

What is claimed is:

l. Doffing apparatus for strand processing equipment comprising, means for longitudinally advancing a strand at a strand processing position and taking the strand up on a bobbin while currently imparting to the strand a particular range of transverse alternating motion, means for doffing the bobbin at said position, sensing means including first means providing various outputs and a particular output, said particular output being produced in response to the transverse motion of said strand, and second means for differentiating between said particular output and said various outputs and being responsive to said particular output to control the doffing means.

2. Apparatus as set forth in claim 1 wherein said first means provides said particular output as a fluctuating signal, and said second means comprises filter means and control means, said filter means passes said fluctuating signal, and said control means is responsive to said fluctuating signal to provide a control signal for regulating operation of the doffing means.

3. Apparatus as set forth in claim 2 wherein said sensing means includes third means for determining whether the strand is in operational condition to be advanced and when the strand is in operational condition for providing a second control signal, and means responsive to receiving said second control signal and not receiving the first said control signal for controlling operation of the doffing means to doff the bobbin.

4. Apparatus as set forth in claim 3 wherein said fluctuating signal has a component within particular amplitude and frequency ranges, and said first means provides said fluctuating signal in the form of a signal having a component within said ranges.

5. Apparatus as set forth in claim 1 wherein said first means comprises phototransducer means.

6. Apparatus as set forth in claim 5 wherein said phototransducer means comprises a single photosensitive area for receiving an image of the transverse motion of the strand.

7. Apparatus as set forth in claim 5 wherein said phototransducer means comprises a plurality of photosensitive areas for receiving an image of the transverse motion of the strand, and said areas are positioned so that at least one of said areas receives the image of only a limited portion of the transverse span of the transverse motion of the strand when said areas receive said image to provide said fluctuating signal.

8. Apparatus as set forth in claim 7 wherein said areas are spaced apart in the direction of said transverse motion of said image a distance less than the transverse span of the image as received by the areas.

9. Apparatus as set forth in claim 8 wherein said phototransducer means comprises a photon'ansducer having a single photosensitive zone having a plurality of photosensitive areas of greater sensitivity than other photosensitive areas intervening therebetween.

10. Apparatus as set forth in claim 8 wherein said phototransducer means comprises a plurality of spaced apart phototransducers each having one of said photosensitive areas.

11. Apparatus as set forth in claim 5 including at least a second strand processing position arranged with said first mentioned strand processing position, said doffing means being operable to doff the bobbin at either of said positions, said advancing means being operable to advance a strand at each of said positions while concurrently imparting to said strands a particular range of transverse alternating motion, means for actuating said first means to scan said positions and provide said various outputs in response to said scanning, and said second means regulating operation of said dofiing means to selectively doff the bobbin at the position being scanned in response to an output from the last said position.

12. Apparatus as set forth in claim 11 wherein the doffing means comprises a tender and means mounting the tender and the positions for relative movement, operating means for providing said relative movement and for stopping said relative movement with said tender proximate any of said positions, said first means being mounted on said tender for scanning said positions, and said second means regulating operation of said operating means for providing and stopping said relative movement.

13. Apparatus as set forth in claim 12 wherein said sensing means includes third means for determining whether the strand is in operational condition to be advanced and when the strand is in operational condition for providing a second control signal, and means responsive to receiving said second control signal and not receiving the first said control signal for controlling operation of the doffing means to dofi the bobbin at the position being scanned.

. 14. A method of dofiing strand processing apparatus having a position at which a strand is advanced onto a bobbin during operation of the apparatus and mechanism for doffing a bobbin at the position comprising the steps of; longitudinally advancing the strand at the position while concurrently imparting to the strand a particular range of transverse alternating motion, providing various outputs and a particular output, said particular output being provided in response to said transverse motion of said strand, and differentiating between said particular outputs and said various outputs and controlling the operation of the doffing mechanism by said particular output.

15. A method as set forth in claim 14 wherein the step of providing various outputs includes providing said particular output as a fluctuating signal, and the step of differentiating includes passing said fluctuating signal and responsive thereto providing a control signal for regulating operation of the doffing mechanism.

16. A method as set forth in claim including the step of determining whether the strand is in operational condition to be advanced and when the strand is in operational condition providing a further control signal, and regulating operation of the doffing mechanism in response to said further control signal and the absence of the first mentioned control signal.

17. A method as set forth in claim 16 wherein the apparatus includes a plurality of strand processing positions at each of which a strand is advanced onto a bobbin, and the dolfing mechanism is operable for doffing the bobbin at any of the

Claims

1. Doffing apparatus for strand processing equipment comprising, means for longitudinally advancing a strand at a strand processing position and taking the strand up on a bobbin while currently imparting to the strand a particular range of transverse alternating motion, means for doffing the bobbin at said position, sensing means including first means providing various outputs and a particular output, said particular output being produced in response to the transverse motion of said strand, and second means for differentiating between said particular output and said various outputs and being responsive to said particular output to control the doffing means.

9. Apparatus as set forth in claim 8 wherein said phototransducer means comprises a phototransducer having a single photosensitive zone having a plurality of photosensitive areas of greater sensitivity than other photosensitive areas intervening therebetween.

11. Apparatus as set forth in claim 5 including at least a second strand processing position arranged with said first mentioned strand processing position, said doffing means being operable to doff the bobbin at either of said positions, said advancing means being operable to advance a strand at each of said positions while concurrently imparting to said strands a particular range of transverse alternating motion, means for actuating said first means to scan said positions and provide said various outputs in response to said scanning, and said second means regulating operation of said doffing means to selectively doff the bobbin at the position being scanned in response to an output from the last said position.

13. Apparatus as set forth in claim 12 wherein said sensing means includes third means for determining whether the strand is in operational condition to be advanced and when the strand is in operational condition for providing a second control signal, and means responsive to receiving said second control signal and not receiving the first said control signal for controlling operation of the doffing means to doff the bobbin at the position being scanned.

14. A method of doffing strand processing apparatus having a position at which a strand is advanced onto a bobbin during operation of the apparatus and mechanism for doffing a bobbin at the position comprising the steps of; longitudinally advancing the strand at the position while concurrently imparting to the strand a particular range of transverse alternating motion, providing various outputs and a particular output, said particular output being provided in response to said transverse motion of said strand, and differentiating between said particular outputs and said various outputs and controlling the operation of the doffing mechanism by saId particular output.

16. A method as set forth in claim 15 including the step of determining whether the strand is in operational condition to be advanced and when the strand is in operational condition providing a further control signal, and regulating operation of the doffing mechanism in response to said further control signal and the absence of the first mentioned control signal.

17. A method as set forth in claim 16 wherein the apparatus includes a plurality of strand processing positions at each of which a strand is advanced onto a bobbin, and the doffing mechanism is operable for doffing the bobbin at any of the positions, and wherein the step of advancing includes longitudinally advancing the strands at their respective positions and concurrently therewith imparting a particular range transverse alternating motion to the strands, and the step of sensing includes scanning the positions and responsive to scanning each position providing said various outputs, and responsive to said various outputs from the position being scanned regulating operation of the doffing mechanism to selectively doff the bobbin at the position being scanned.