Title:
METHOD AND MEANS FOR DETECTING THE APPROACHING END OF A THREAD AND A BOBBIN THEREFOR
United States Patent 3845320
Abstract:
This invention teaches a bobbin having a plurality of parts on which a continuous length of thread may be wound such that when the main portion or length of the thread is unwound from the bobbin, a terminal portion or length of the thread may be utilized to indicate the approaching end of the thread. The bobbin includes parts about which the thread may be wound in a continuous manner but to separate portions of the thread from each other to enable the winding of the thread such that the terminal end of the thread may be detected with the use of a sensor structure.
US Patent References:
Bobbin for lockstitch sewing machines
Ashworth - February 1944 - 2340574
Indicating and control device
Pomarico - March 1960 - 2926860
Automatic tape cartridge for magnetic recorders
Sampson - February 1961 - 2971716
CONTROL SYSTEM
Kent et al. - March 1970 - 3498039
Bobbin for lockstitch sewing machines
Ashworth - February 1944 - 2340574
Indicating and control device
Pomarico - March 1960 - 2926860
Automatic tape cartridge for magnetic recorders
Sampson - February 1961 - 2971716
CONTROL SYSTEM
Kent et al. - March 1970 - 3498039
Application Number:
05/344743
Publication Date:
10/29/1974
Filing Date:
03/26/1973
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
250/222.100, 242/118.400, 139/273A, 112/278
International Classes:
D05B59/02; D05B59/00; G01B7/12
Field of Search:
250/219S,222R,561,571 356/159,239 139/273A
Primary Examiner:
Stolwein, Walter
Attorney, Agent or Firm:
Bauer, And Amer
Claims:
1. In an apparatus for indicating the approaching end of a thread wound on a rotatable bobbin,
2. In an apparatus as in claim 1,
3. In an apparatus as in claim 1,
4. In an apparatus as in claim 3,
5. In the method of determining the approaching end of a thread wound on a bobbin wherein the thread has a main portion thereof wound on one part of a bobbin contiguous with a terminal portion of the thread wound on another part of the same bobbin having a transparent outer wall, the method comprising
6. In the method as in claim 5,
2. In an apparatus as in claim 1,
3. In an apparatus as in claim 1,
4. In an apparatus as in claim 3,
5. In the method of determining the approaching end of a thread wound on a bobbin wherein the thread has a main portion thereof wound on one part of a bobbin contiguous with a terminal portion of the thread wound on another part of the same bobbin having a transparent outer wall, the method comprising
6. In the method as in claim 5,
Description:
BACKGROUND OF THE DISCLOSURE
At present in commercial sewing machines, a bobbin is provided with thread that forms the lower stitch. This lower stitch is engaged by thread forming the upper stitch that is usually supplied from a spool mounted on and in full view of the operator. Thus, the operator may easily see when the thread on the spool is approaching its end and, therefore, may readily change the same. Unfortunately, however, there is no way for the operator, who is intent upon and absorbed in the sewing operation, to know when the bobbin is about to run out of thread.
Contributing reasons are that the operator is too intent upon performing the sewing operation to pay attention to the thread on the bobbin and also because the bobbin is usually contained within a bobbin housing that is mounted beneath the stitching plate and obscured within the housing and, therefore, is not readily accessible for easy and rapid viewing. Hence, it often happens that the absorbed sewing machine operator will continue to sew even after the bobbin has run out of thread. This results in a line of stitching in which only the upper thread will be sewn without a locking stitching in the lower thread coming from the bobbin.
SUMMARY OF THE INVENTION
The desideratum of the invention is to provide a unique bobbin, method of winding the same and a method and means for determining when the thread on the bobbin is approaching the end of its supply without requiring the operator to stop from time to time to physically remove the bobbin from its nest or housing to visually check the same.
An object of the invention is to provide a bobbin that has provision thereon for winding a continuous length of thread in two separate portions such that the unwinding of the terminal portion may be detected and an indication provided to the operator without requiring the operator to divert attention to the condition of the thread on the bobbin.
Another object is to provide a novel method of winding a bobbin to enable the detection and to signal the approaching end of the thread.
Still a further object is to provide a sensing structure cooperable with the bobbin to sense and to afford a method of sensing the approaching end of the thread without interfering with the functions of the sewing operation.
The above description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative, embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a conventional sewing machine with a vertically disposed bobbin;
FIG. 2 is a perspective view of a conventional sewing machine with a horizontally disposed bobbin;
FIG. 3 is a perspective view of a bobbin constructed according to the teaching of the invention and usable in the machines of FIGS. 1 and 2;
FIG. 4 is an enlarged partial view of the bobbin wound with an extent of thread thereon and positioned in a machine of the type shown in FIG. 1 and with a sensor means diagrammatically illustrated in operation in accordance with the teaching of the invention;
FIG. 5 is an enlarged partial view of the bobbin in a horizontal position and with another embodiment of a sensor means schematically illustrated in accordance with the teaching of the invention; and
FIG. 6 is an enlarged partial view of a bobbin of the invention and a further embodiment of a sensor means illustrated diagrammatically and constructed in accordance with the teaching of the invention.
DESCRIPTION OF THE INVENTION
Referring to the drawing, FIGS. 1 and 2 illustrate two different types of sewing machines. In FIG. 1, the bobbin is positioned vertically whereas in FIG. 2, the bobbin is illustrated as positioned horizontally. FIGS. 1 and 2 are illustrated solely to suggest that the broad concept of the invention is not limited to any particular arrangement of sewing machine bobbin, but rather that the invention may be utilized in any position of the bobbin in a sewing machine. For this reason, like numerals will be utilized to designate like parts of structure in both FIGS. 1 and 2.
In FIGS. 1 and 2, the sewing machine generally identified by the numeral 10 includes a head 12, a foot 14, and a needle 16. Mounted beneath the sewing foot 14 is a foot plate 18 and a sliding plate 20. The sliding movement of the plate 20 serves to cover and uncover or expose the bobbin mechanism beneath the foot plate 18. In each of FIGS. 1 and 2, the bobbin mechanism usually includes a bobbin carriage 22 that supports a bobbin housing 24. All of the aforementioned structure is conventional in sewing machines, whether the same be intended for commercial or home use and, therefore, the details of the same form no part of the present invention, except that it will be helpful but not necessary to understand the arrangement of such details in the functioning of the subject matter of the present invention.
Usually mounted within the bobbin housing 24 is a bobbin. The bobbin may be described as a spool or reel about which thread is wound. The bobbin thread provides the locking lower stitch that cooperates with the upper stitch formed by the thread 26 passed through the eye of the needle 16. For the purposes of the present invention, reference is made to the term "bobbin." This term is intended to mean and to include, without limitation, spools, reels and other like structures for use with such elongated and continuous materials as thread, yarn, filaments, wire, cord and like materials that are usually wound about bobbins whether they be for spooling or reeling. Hence, for convenience, it is also important to recognize that throughout the disclosure, reference will be made to the term "thread." This term is not intended to constitute a limitation upon the scope of the invention. It will be recognized by those skilled in the art, as the description proceeds, that the invention may be utilized not just in the sewing machine arts but in other arts including those finding it necessary to determine beforehand the approaching end of such threads as, but not limited to, wire, yarn, filaments, cord and the like.
Referring now to FIG. 3, there is disclosed a unique bobbin generally identified by the numeral 28. The bobbin 28 includes a body 30 here shown circular in shape and axially extending to provide a surface about which a thread may be wound. For convenience, the body 30 has a hollow interior or axially directed opening 32 to render it easily applicable and mounted upon the conventional spindle that is normally provided in the bobbin housing 24. The axial extent of the body 30 is a matter of choice. Basically, the invention comprises the body 30 about which a leading portion of a thread is adapted to be wound. The extent of the body 30 about which such leading portion of the thread is to be wound is delineated by a partition or wall 34. The wall 34 is positioned on the body intermediate the ends thereof as can be more clearly seen from a side view of the bobbin in FIGS. 3, 4 and 5.
Spaced from the partition wall 34 are outer walls 36 and 38. The outer wall 36 is more closely spaced with respect to the partition 34 than is the opposite outer wall 38. Although the outer walls 36 and 38 are illustrated as defining the opposite axial ends of the bobbin structure 28, it should be apparent that they need not be so located on the body 30. Such outer walls 36 and 38 may be spaced slightly inward from the ends of the bobbin and on the body 30.
The three walls 34, 36 and 38 are arranged substantially radially with respect to the body 30. As illustrated in the Figures of the drawing, the outer walls 36 and 38 may have interior surfaces that are concave in shape while the outer surfaces thereof may be convex in shape. The particular shape of such walls should not constitute a limitation upon the invention and, therefore, the particular illustration is made solely to enable a clearer understanding of the invention. It will be noted that the radial extent and diameter of the inner partition wall 34, although illustrated as slightly smaller, may be of equal radial size as outer walls 36 and 38. Moreover, the partition 34 is provided with one or more notches 40 in its outer periphery to accommodate the thickness of the thread to be wound on the bobbin. Again, the purpose and function of such notches will become apparent as the description proceeds.
Referring to FIG. 3 and more particularly to the bobbin structure 28, the three relatively spaced walls define two winding parts on the bobbin, one of such parts, the main or larger, being defined between the partition 34 and the outer wall 38 while the other winding part, here referred to as the reserve space, is defined between the partition 34 and the opposite outer wall 36. The main winding part is adapted to support, in overlying turns, the main portion of the thread that is to be wound on the bobbin while the reserve part is adapted to support an extent or length of the terminal end of the thread which is deemed to be sufficient to warn the operator of the approaching end of the thread and to know well in advance of the actual end of the thread when the bobbin will run completely out of thread.
Referring to FIG. 4, there is a bobbin 28 illustrated with thread shown positioned thereabout. When the thread is wound about the bobbin, the terminal extent of such thread is first wound in position within the reserve space defined between the partition 34 and the outer wall 36. Thus, the bobbin is first wound wtih thread into the reserve space and is illustrated by the thread 42. The reserve or terminal end of the thread 42 is wound to the substantial full diameter of the reserve space of the bobbin as limited by the partition 34 and then crossed over by way of one of the notches 40 into the main winding part of the body between the wall 34 and the outer wall 38. Hence, the notches 40 enable this cross over without tearing or damaging the thread and also prevent the thread from unwinding and snarling. Thereafter, the remainder of the thread is wound on the body 30 that forms a part of the main part of the bobbin.
FIG. 4 shows the thread 42 within the reserve part of the bobbin and an extent of the thread 44 wound in the main part of the bobbin. The main part of the bobbin is then also wound with overlying turns of thread 44 until the same reaches approximately the full diameter of the outer walls 36 and 38 during which some turns of the thread 44 may overlie but not entangle with the threads 42 in the reserve part. Usually, a length of the main winding thread 44 is permitted to extend loosely from the bobbin so when the bobbin is placed on the spindle 46 of the bobbin housing 24, the thread will extend outwardly and be accessible through an opening 48 in the bobbin housing. The bobbin housing is then placed within the bobbin carriage 22 beneath the sewing needle 16 and the plate 20 is then slid to close thereover.
During the sewing operation, the upper thread 26, threaded in the needle 16, engages in locking arrangement with the thread 44 of the bobbin to form the lock stitch. During the sewing operation and the formation of stitches, the main thread 44 unwinds from the bobbin 28 until such time that all of the thread 44 is used up from the main part of the bobbin between the partition 34 and the outer wall 38. At that point, the continued unwinding thread crosses over the partition 34 by way of the notch 40 within which it was held and begins to unwind the reserve wound thread 42 from the reserve space. It will be understood that the partition 34, therefore, functions as a separator between the main part of the bobbin 28 and the reserve part of the same bobbin so that the turns of the reserve and main threads 42 and 44 do not become tangled with each other.
The cross over afforded by the partition wall 34, at the notches 40, assures that the turns 42 and 44 are continuous and that the windings 42 and 44 are, therefore, contiguous and unbroken so that there is a smooth transition of unwinding of the main turns 44 and thereafter the reserve turns 42. The notches 40 further aid in the separation of the reserve and main thread turns from each other and prevents the cross over thread, that is to say, the thread that crosses over during the initial winding of the bobbin from the reserve turns 42 to the main turns 44, from sliding over or along the surface or rim or outer peripheral edge of the partition wall 34. Hence, the notches retain the cross over thread in a fixed and desired position on the wall 34 until the cross over unwinding action is completed.
In winding the thread on the bobbin 26, an extent of the terminal end of the thread is wound in overlying turns in the reserve part of the bobbin. These are depicted at 42. The winding is continued uninterruptedly across the partition through one of the notches 40 provided thereon and the remainder portion of the thread is wound in overlying turns 44 on the main and reserve parts of the bobbin. This winding is provided such that the end of the main turns of the thread 44 thereafter becomes the leading end by which the thread 44-42 is subsequently unwound from the bobbin 28 so that the turns of the thread 44 must be unwound first from the bobbin before the reserve or terminal end of the same thread or turns 42 can be unwound from the bobbin.
What has been disclosed thus far is a unique bobbin adapted to support a continuous length of thread of any kind thereon and wound in such manner that the end of the thread, here defined as the reserve portion of the thread 42, can be utilized for the purpose of detecting its approaching complete unwinding from the bobbin and to thereafter provide the operator using such bobbin with the knowledge that the bobbin is about to run out of thread. For this purpose, the bobbin 28 may be constructed in a number of ways. FIG. 4 illustrates one embodiment of such bobbin. There, the bobbin is disclosed with each of its walls 34, 36 and 38 being able to permit the passage of light therethrough. To permit this, it has been found in practice that if the walls are made of clear plastic, the same will permit the through passage of light.
Illustrated in FIG. 4 is a light source 50 that may be connected to any convenient source of electricity such as that powering the sewing machine motor. The light source 50 passes through an opening that is a conventional formation in the bobbin carriage 22. The light then passes through the walls 38, 34 and 36 of the bobbin 28 mounted within the carriage and within the housing 24. The housing 24 is conventionally provided with an opening 52 which thereby permits the light from the source 50 to pass completely through the carriage and the housing and outwardly therefrom to be detected by a conventional light detector 54 which may also be connected to any convenient source of electrical energy such as that shown in 56 and thereafter to a bulb or other convenient signal means 58. The illustrated arrangement of the sensing means, which includes the light source 50 and detector means 54, clearly illustrates the manner in which the presence of and the progressive unwinding of the reserve turns of thread 42 from the spool 28 may be detected and a signal provided to the operator long before the thread eventually completely unwinds from the bobbin 28.
As the main turns of thread 44 unwind from the bobbin, the light from the source 50 is permitted to penetrate and pass through the outer wall 38 to the partition 34. However, until such time as the thread in the reserve part of the bobbin starts to unwind, the light cannot penetrate beyond the partition 34. As the thread 44 is completely used up and crosses over the partition 34 to cause the reserve turns 42 to unwind, such unwinding of the reserve thread begins to progressively expose increasing greater radial portions of the reserve space between the partition 34 and the outer wall 36. This then permits the light from the source 50 to pass in increasing intensity through the wall 34, the reserve space and thereafter through the wall 36 and to be detected by the light sensing means 54 which is connected with the indicator means 58.
As more and more of the reserve turns of thread 42 are unwound from the reserve space, more light is permitted to pass through the reserve space to the sensor means 54. If the indicator or signal means 58 is a light bulb that may be conveniently mounted in any position here shown on the head 12 of the sewing machine 10, the operator will be attracted by the illumination of the bulb 58. As more light passes from the source 50 through the reserve part of the bobbin and is detected by the sensing means 54, the indicator bulb 58 will grow stronger in intensity to attract the attention of the sewing machine operator who will then realize that the reserve thread is now being unwound from the bobbin and that the thread is approaching the terminal end of its extent.
In carrying out the method of the present invention, the main portion of the thread 44 is unwound from the main part of the bobbin before unwinding the reserve portion threads 42 from the reserve part of the bobbin. The light 50 is directed at the reserve portion of the bobbin and the light detecting means 54 is directed at that point from which the light is to pass through the reserve part of the bobbin so as to sense the light and thereby provide an indication to the operator that the reserve threads are being unwound from the reserve part of the bobbin.
In a further embodiment in FIG. 5, the outer wall 36 is constructed of a material to enable the passage of light therethrough while the partition 34 is provided with a light reflecting surface. The light source 50 is directed at an angle to the reflective surface of the partition 34 while the light sensing means 54 is also positioned at an angle to the reflecting surface of the partition 34. As illustrated in FIG. 5, both the light source 50 and the detecting or sensing means 54 are positioned on one side of the bobbin so that as the reserve turns of thread 42 are unwound from the reserve part of the bobbin between the partition 34 and the outer wall 36, the light will penetrate to the reflective surface of the partition 34 and the reflected light will be sensed by the indicator 54 to thereby operate the signalling means 58.
In the embodiment shown in FIG. 6, the outer wall 36 and the partition 34 are constructed to enable the passage of light from the source 50 completely therethrough to the outer wall 38 which has a reflective surface. Once again, both the light source 50 and the light indicator 54 may be positioned on one side of the bobbin 28 with the light source and detecting means angled such that the light from the source may pass through the reserve part of the bobbin to be reflected back by the reflective surface of the outer wall 38 to the light sensor or detector 54. Hence, as the turns of reserve thread 42 unwind from the reserve part of the bobbin defined between the partition 34 and the outer wall 36, light from the source 50 will penetrate and pass through the same to the reflective surface of the outer wall 38 and be reflected thereby to the light indicator 54 which will then operate the signalling device 58.
The present invention discloses a unique bobbin and method of winding the same and also an arrangement of structure for detecting the approaching end of the thread wound upon such bobbin. The structure of the bobbin is simple and inexpensive. The arrangement of sensing means, which includes the light source 50 and light detector or sensor 54, may be conveniently installed on any conventional sewing machine whether the same utilizes a vertical or horizontal bobbin. Although the present invention has been disclosed and described for use in connection with a sewing machine, those who are skilled in the art will readily recognize that the teaching of the present invention may be applied with equal facility to other machines requiring the use of bobbins, spools, reels, and the like and wherein it is important to be able to detect the approaching end of the particular type of thread being unwound therefrom.
While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
At present in commercial sewing machines, a bobbin is provided with thread that forms the lower stitch. This lower stitch is engaged by thread forming the upper stitch that is usually supplied from a spool mounted on and in full view of the operator. Thus, the operator may easily see when the thread on the spool is approaching its end and, therefore, may readily change the same. Unfortunately, however, there is no way for the operator, who is intent upon and absorbed in the sewing operation, to know when the bobbin is about to run out of thread.
Contributing reasons are that the operator is too intent upon performing the sewing operation to pay attention to the thread on the bobbin and also because the bobbin is usually contained within a bobbin housing that is mounted beneath the stitching plate and obscured within the housing and, therefore, is not readily accessible for easy and rapid viewing. Hence, it often happens that the absorbed sewing machine operator will continue to sew even after the bobbin has run out of thread. This results in a line of stitching in which only the upper thread will be sewn without a locking stitching in the lower thread coming from the bobbin.
SUMMARY OF THE INVENTION
The desideratum of the invention is to provide a unique bobbin, method of winding the same and a method and means for determining when the thread on the bobbin is approaching the end of its supply without requiring the operator to stop from time to time to physically remove the bobbin from its nest or housing to visually check the same.
An object of the invention is to provide a bobbin that has provision thereon for winding a continuous length of thread in two separate portions such that the unwinding of the terminal portion may be detected and an indication provided to the operator without requiring the operator to divert attention to the condition of the thread on the bobbin.
Another object is to provide a novel method of winding a bobbin to enable the detection and to signal the approaching end of the thread.
Still a further object is to provide a sensing structure cooperable with the bobbin to sense and to afford a method of sensing the approaching end of the thread without interfering with the functions of the sewing operation.
The above description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative, embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a conventional sewing machine with a vertically disposed bobbin;
FIG. 2 is a perspective view of a conventional sewing machine with a horizontally disposed bobbin;
FIG. 3 is a perspective view of a bobbin constructed according to the teaching of the invention and usable in the machines of FIGS. 1 and 2;
FIG. 4 is an enlarged partial view of the bobbin wound with an extent of thread thereon and positioned in a machine of the type shown in FIG. 1 and with a sensor means diagrammatically illustrated in operation in accordance with the teaching of the invention;
FIG. 5 is an enlarged partial view of the bobbin in a horizontal position and with another embodiment of a sensor means schematically illustrated in accordance with the teaching of the invention; and
FIG. 6 is an enlarged partial view of a bobbin of the invention and a further embodiment of a sensor means illustrated diagrammatically and constructed in accordance with the teaching of the invention.
DESCRIPTION OF THE INVENTION
Referring to the drawing, FIGS. 1 and 2 illustrate two different types of sewing machines. In FIG. 1, the bobbin is positioned vertically whereas in FIG. 2, the bobbin is illustrated as positioned horizontally. FIGS. 1 and 2 are illustrated solely to suggest that the broad concept of the invention is not limited to any particular arrangement of sewing machine bobbin, but rather that the invention may be utilized in any position of the bobbin in a sewing machine. For this reason, like numerals will be utilized to designate like parts of structure in both FIGS. 1 and 2.
In FIGS. 1 and 2, the sewing machine generally identified by the numeral 10 includes a head 12, a foot 14, and a needle 16. Mounted beneath the sewing foot 14 is a foot plate 18 and a sliding plate 20. The sliding movement of the plate 20 serves to cover and uncover or expose the bobbin mechanism beneath the foot plate 18. In each of FIGS. 1 and 2, the bobbin mechanism usually includes a bobbin carriage 22 that supports a bobbin housing 24. All of the aforementioned structure is conventional in sewing machines, whether the same be intended for commercial or home use and, therefore, the details of the same form no part of the present invention, except that it will be helpful but not necessary to understand the arrangement of such details in the functioning of the subject matter of the present invention.
Usually mounted within the bobbin housing 24 is a bobbin. The bobbin may be described as a spool or reel about which thread is wound. The bobbin thread provides the locking lower stitch that cooperates with the upper stitch formed by the thread 26 passed through the eye of the needle 16. For the purposes of the present invention, reference is made to the term "bobbin." This term is intended to mean and to include, without limitation, spools, reels and other like structures for use with such elongated and continuous materials as thread, yarn, filaments, wire, cord and like materials that are usually wound about bobbins whether they be for spooling or reeling. Hence, for convenience, it is also important to recognize that throughout the disclosure, reference will be made to the term "thread." This term is not intended to constitute a limitation upon the scope of the invention. It will be recognized by those skilled in the art, as the description proceeds, that the invention may be utilized not just in the sewing machine arts but in other arts including those finding it necessary to determine beforehand the approaching end of such threads as, but not limited to, wire, yarn, filaments, cord and the like.
Referring now to FIG. 3, there is disclosed a unique bobbin generally identified by the numeral 28. The bobbin 28 includes a body 30 here shown circular in shape and axially extending to provide a surface about which a thread may be wound. For convenience, the body 30 has a hollow interior or axially directed opening 32 to render it easily applicable and mounted upon the conventional spindle that is normally provided in the bobbin housing 24. The axial extent of the body 30 is a matter of choice. Basically, the invention comprises the body 30 about which a leading portion of a thread is adapted to be wound. The extent of the body 30 about which such leading portion of the thread is to be wound is delineated by a partition or wall 34. The wall 34 is positioned on the body intermediate the ends thereof as can be more clearly seen from a side view of the bobbin in FIGS. 3, 4 and 5.
Spaced from the partition wall 34 are outer walls 36 and 38. The outer wall 36 is more closely spaced with respect to the partition 34 than is the opposite outer wall 38. Although the outer walls 36 and 38 are illustrated as defining the opposite axial ends of the bobbin structure 28, it should be apparent that they need not be so located on the body 30. Such outer walls 36 and 38 may be spaced slightly inward from the ends of the bobbin and on the body 30.
The three walls 34, 36 and 38 are arranged substantially radially with respect to the body 30. As illustrated in the Figures of the drawing, the outer walls 36 and 38 may have interior surfaces that are concave in shape while the outer surfaces thereof may be convex in shape. The particular shape of such walls should not constitute a limitation upon the invention and, therefore, the particular illustration is made solely to enable a clearer understanding of the invention. It will be noted that the radial extent and diameter of the inner partition wall 34, although illustrated as slightly smaller, may be of equal radial size as outer walls 36 and 38. Moreover, the partition 34 is provided with one or more notches 40 in its outer periphery to accommodate the thickness of the thread to be wound on the bobbin. Again, the purpose and function of such notches will become apparent as the description proceeds.
Referring to FIG. 3 and more particularly to the bobbin structure 28, the three relatively spaced walls define two winding parts on the bobbin, one of such parts, the main or larger, being defined between the partition 34 and the outer wall 38 while the other winding part, here referred to as the reserve space, is defined between the partition 34 and the opposite outer wall 36. The main winding part is adapted to support, in overlying turns, the main portion of the thread that is to be wound on the bobbin while the reserve part is adapted to support an extent or length of the terminal end of the thread which is deemed to be sufficient to warn the operator of the approaching end of the thread and to know well in advance of the actual end of the thread when the bobbin will run completely out of thread.
Referring to FIG. 4, there is a bobbin 28 illustrated with thread shown positioned thereabout. When the thread is wound about the bobbin, the terminal extent of such thread is first wound in position within the reserve space defined between the partition 34 and the outer wall 36. Thus, the bobbin is first wound wtih thread into the reserve space and is illustrated by the thread 42. The reserve or terminal end of the thread 42 is wound to the substantial full diameter of the reserve space of the bobbin as limited by the partition 34 and then crossed over by way of one of the notches 40 into the main winding part of the body between the wall 34 and the outer wall 38. Hence, the notches 40 enable this cross over without tearing or damaging the thread and also prevent the thread from unwinding and snarling. Thereafter, the remainder of the thread is wound on the body 30 that forms a part of the main part of the bobbin.
FIG. 4 shows the thread 42 within the reserve part of the bobbin and an extent of the thread 44 wound in the main part of the bobbin. The main part of the bobbin is then also wound with overlying turns of thread 44 until the same reaches approximately the full diameter of the outer walls 36 and 38 during which some turns of the thread 44 may overlie but not entangle with the threads 42 in the reserve part. Usually, a length of the main winding thread 44 is permitted to extend loosely from the bobbin so when the bobbin is placed on the spindle 46 of the bobbin housing 24, the thread will extend outwardly and be accessible through an opening 48 in the bobbin housing. The bobbin housing is then placed within the bobbin carriage 22 beneath the sewing needle 16 and the plate 20 is then slid to close thereover.
During the sewing operation, the upper thread 26, threaded in the needle 16, engages in locking arrangement with the thread 44 of the bobbin to form the lock stitch. During the sewing operation and the formation of stitches, the main thread 44 unwinds from the bobbin 28 until such time that all of the thread 44 is used up from the main part of the bobbin between the partition 34 and the outer wall 38. At that point, the continued unwinding thread crosses over the partition 34 by way of the notch 40 within which it was held and begins to unwind the reserve wound thread 42 from the reserve space. It will be understood that the partition 34, therefore, functions as a separator between the main part of the bobbin 28 and the reserve part of the same bobbin so that the turns of the reserve and main threads 42 and 44 do not become tangled with each other.
The cross over afforded by the partition wall 34, at the notches 40, assures that the turns 42 and 44 are continuous and that the windings 42 and 44 are, therefore, contiguous and unbroken so that there is a smooth transition of unwinding of the main turns 44 and thereafter the reserve turns 42. The notches 40 further aid in the separation of the reserve and main thread turns from each other and prevents the cross over thread, that is to say, the thread that crosses over during the initial winding of the bobbin from the reserve turns 42 to the main turns 44, from sliding over or along the surface or rim or outer peripheral edge of the partition wall 34. Hence, the notches retain the cross over thread in a fixed and desired position on the wall 34 until the cross over unwinding action is completed.
In winding the thread on the bobbin 26, an extent of the terminal end of the thread is wound in overlying turns in the reserve part of the bobbin. These are depicted at 42. The winding is continued uninterruptedly across the partition through one of the notches 40 provided thereon and the remainder portion of the thread is wound in overlying turns 44 on the main and reserve parts of the bobbin. This winding is provided such that the end of the main turns of the thread 44 thereafter becomes the leading end by which the thread 44-42 is subsequently unwound from the bobbin 28 so that the turns of the thread 44 must be unwound first from the bobbin before the reserve or terminal end of the same thread or turns 42 can be unwound from the bobbin.
What has been disclosed thus far is a unique bobbin adapted to support a continuous length of thread of any kind thereon and wound in such manner that the end of the thread, here defined as the reserve portion of the thread 42, can be utilized for the purpose of detecting its approaching complete unwinding from the bobbin and to thereafter provide the operator using such bobbin with the knowledge that the bobbin is about to run out of thread. For this purpose, the bobbin 28 may be constructed in a number of ways. FIG. 4 illustrates one embodiment of such bobbin. There, the bobbin is disclosed with each of its walls 34, 36 and 38 being able to permit the passage of light therethrough. To permit this, it has been found in practice that if the walls are made of clear plastic, the same will permit the through passage of light.
Illustrated in FIG. 4 is a light source 50 that may be connected to any convenient source of electricity such as that powering the sewing machine motor. The light source 50 passes through an opening that is a conventional formation in the bobbin carriage 22. The light then passes through the walls 38, 34 and 36 of the bobbin 28 mounted within the carriage and within the housing 24. The housing 24 is conventionally provided with an opening 52 which thereby permits the light from the source 50 to pass completely through the carriage and the housing and outwardly therefrom to be detected by a conventional light detector 54 which may also be connected to any convenient source of electrical energy such as that shown in 56 and thereafter to a bulb or other convenient signal means 58. The illustrated arrangement of the sensing means, which includes the light source 50 and detector means 54, clearly illustrates the manner in which the presence of and the progressive unwinding of the reserve turns of thread 42 from the spool 28 may be detected and a signal provided to the operator long before the thread eventually completely unwinds from the bobbin 28.
As the main turns of thread 44 unwind from the bobbin, the light from the source 50 is permitted to penetrate and pass through the outer wall 38 to the partition 34. However, until such time as the thread in the reserve part of the bobbin starts to unwind, the light cannot penetrate beyond the partition 34. As the thread 44 is completely used up and crosses over the partition 34 to cause the reserve turns 42 to unwind, such unwinding of the reserve thread begins to progressively expose increasing greater radial portions of the reserve space between the partition 34 and the outer wall 36. This then permits the light from the source 50 to pass in increasing intensity through the wall 34, the reserve space and thereafter through the wall 36 and to be detected by the light sensing means 54 which is connected with the indicator means 58.
As more and more of the reserve turns of thread 42 are unwound from the reserve space, more light is permitted to pass through the reserve space to the sensor means 54. If the indicator or signal means 58 is a light bulb that may be conveniently mounted in any position here shown on the head 12 of the sewing machine 10, the operator will be attracted by the illumination of the bulb 58. As more light passes from the source 50 through the reserve part of the bobbin and is detected by the sensing means 54, the indicator bulb 58 will grow stronger in intensity to attract the attention of the sewing machine operator who will then realize that the reserve thread is now being unwound from the bobbin and that the thread is approaching the terminal end of its extent.
In carrying out the method of the present invention, the main portion of the thread 44 is unwound from the main part of the bobbin before unwinding the reserve portion threads 42 from the reserve part of the bobbin. The light 50 is directed at the reserve portion of the bobbin and the light detecting means 54 is directed at that point from which the light is to pass through the reserve part of the bobbin so as to sense the light and thereby provide an indication to the operator that the reserve threads are being unwound from the reserve part of the bobbin.
In a further embodiment in FIG. 5, the outer wall 36 is constructed of a material to enable the passage of light therethrough while the partition 34 is provided with a light reflecting surface. The light source 50 is directed at an angle to the reflective surface of the partition 34 while the light sensing means 54 is also positioned at an angle to the reflecting surface of the partition 34. As illustrated in FIG. 5, both the light source 50 and the detecting or sensing means 54 are positioned on one side of the bobbin so that as the reserve turns of thread 42 are unwound from the reserve part of the bobbin between the partition 34 and the outer wall 36, the light will penetrate to the reflective surface of the partition 34 and the reflected light will be sensed by the indicator 54 to thereby operate the signalling means 58.
In the embodiment shown in FIG. 6, the outer wall 36 and the partition 34 are constructed to enable the passage of light from the source 50 completely therethrough to the outer wall 38 which has a reflective surface. Once again, both the light source 50 and the light indicator 54 may be positioned on one side of the bobbin 28 with the light source and detecting means angled such that the light from the source may pass through the reserve part of the bobbin to be reflected back by the reflective surface of the outer wall 38 to the light sensor or detector 54. Hence, as the turns of reserve thread 42 unwind from the reserve part of the bobbin defined between the partition 34 and the outer wall 36, light from the source 50 will penetrate and pass through the same to the reflective surface of the outer wall 38 and be reflected thereby to the light indicator 54 which will then operate the signalling device 58.
The present invention discloses a unique bobbin and method of winding the same and also an arrangement of structure for detecting the approaching end of the thread wound upon such bobbin. The structure of the bobbin is simple and inexpensive. The arrangement of sensing means, which includes the light source 50 and light detector or sensor 54, may be conveniently installed on any conventional sewing machine whether the same utilizes a vertical or horizontal bobbin. Although the present invention has been disclosed and described for use in connection with a sewing machine, those who are skilled in the art will readily recognize that the teaching of the present invention may be applied with equal facility to other machines requiring the use of bobbins, spools, reels, and the like and wherein it is important to be able to detect the approaching end of the particular type of thread being unwound therefrom.
While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.