CA1046151A - Needle position detecting arrangement for sewing machines - Google Patents
Needle position detecting arrangement for sewing machinesInfo
- Publication number
- CA1046151A CA1046151A CA170,713A CA170713A CA1046151A CA 1046151 A CA1046151 A CA 1046151A CA 170713 A CA170713 A CA 170713A CA 1046151 A CA1046151 A CA 1046151A
- Authority
- CA
- Canada
- Prior art keywords
- hall
- flux
- needle
- magnet
- hall generator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000009958 sewing Methods 0.000 title claims abstract description 60
- 230000004907 flux Effects 0.000 claims description 46
- 230000005291 magnetic effect Effects 0.000 claims description 40
- 239000004065 semiconductor Substances 0.000 claims description 28
- 230000033001 locomotion Effects 0.000 claims description 17
- 230000000694 effects Effects 0.000 claims description 5
- 230000010287 polarization Effects 0.000 claims description 2
- BGPVFRJUHWVFKM-UHFFFAOYSA-N N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] Chemical compound N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] BGPVFRJUHWVFKM-UHFFFAOYSA-N 0.000 description 16
- 230000002045 lasting effect Effects 0.000 description 5
- 238000013459 approach Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 230000005355 Hall effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D05—SEWING; EMBROIDERING; TUFTING
- D05B—SEWING
- D05B69/00—Driving-gear; Control devices
- D05B69/22—Devices for stopping drive when sewing tools have reached a predetermined position
- D05B69/24—Applications of devices for indicating or ascertaining sewing-tool position
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Textile Engineering (AREA)
- Sewing Machines And Sewing (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention relates to a needle position detecting arrangement for sewing machines. Sewing machines include a hous-ing, a main shaft rotatably mounted in the housing, a needle con-nected to the main shaft and vertically reciprocated thereby and a rotary member fixedly mounted on the main shaft. In accordance with the invention, a Hall generator is secured to a part of the housing. A magnet is secured to a face of the rotary member fac-ing the Hall generator, and a clearance is provided between the magnet and the generator. Each time the magnet passes the gen-erator, a voltage is produced. This voltage is fed to a control circuit which detects the position of the needle. Hall generators may be fixed in two parts of the housing to detect two positions of the needle.
The invention relates to a needle position detecting arrangement for sewing machines. Sewing machines include a hous-ing, a main shaft rotatably mounted in the housing, a needle con-nected to the main shaft and vertically reciprocated thereby and a rotary member fixedly mounted on the main shaft. In accordance with the invention, a Hall generator is secured to a part of the housing. A magnet is secured to a face of the rotary member fac-ing the Hall generator, and a clearance is provided between the magnet and the generator. Each time the magnet passes the gen-erator, a voltage is produced. This voltage is fed to a control circuit which detects the position of the needle. Hall generators may be fixed in two parts of the housing to detect two positions of the needle.
Description
104~151 ~
The invention relates to a needle position detecting ~--arrangement for sewing machines in which a Hall generator and a magnet are used. The generator and magnet are respectively mounted on the machine housing and a rotating member of the sew-ing machine so that the invention will not disturb the outer appearance of the sewing machine. This is one way in which the invention differs from prior art devices in which the detecting device is mounted on the outside of the sewing machine. At the same time, the invention provides an almost permanently lasting needle position detecting arrangement for sewing machines which is free from the shortcomings such as vibration, noise and temp-erature rise. -~
According to the invention, a pulley is preferably utilized, by way of one example, which is fixed on the end of the main shaft of the sewing machine and projecting outwardly thereof, and a magnet, which is an element to be detected, is provided on the inner side of the pulley facing the machine housing, and the Hall generator, which is a detecting element, is provided on the machine housing opposite to the locus in which the magnet is rotated. Thus the magnet and the Hall generator are accommodated between the machine housing and the pulley so that the magnet, during rotation together with the pulley in synchronism with the motion of the needle of the sewing machine, may be detected by the Hall generator in a fixed position, and the position of the needle may be accordingly detected.
In the conventional needle position detecting arrange-ment for sewing machines, a slip ring is generally arranged as an element to be detected, and a brush as a detecting element for contacting the slip ring. The slip ring has a nonconductive part provided therein corresponding to a predetermined position of the needle in its motion in such a manner that when the brush contacts the nonconductive part, the associated electric circuit is deener-gized, and then the brake mechanism is actuated. Such a conven-tional arrangement, however, has many defects and difficultie~
caused by vibration, noise, a~ well as error operations caused by damage of the brush or short-circuit of the nonconductive part, all due to the contact between the 81ip ring and the brush.
Moreover, in such a conventional arrangement, the ~lip ring and the brush are generally mounted on the outside of the pulley which i~ fixedly connected to the main shaft of the sewing mach-ine, and other arrangements have been used where the needle posi-tion is detected by the lower shaft which is rotated in synchron-ism with the main shaft of the sewing machine. In the former arrangement, the slip ring and the brush are provided on the out-side of the sewing machine to simplify the assembly and to make its security easier. But the arrangement becomes bulky and the outer appearance becomes undesirable. Moreover, the arrangement stands in the way and accordingly it must be removed when it be-comes necessary to examine the mechanisms in the machine housing.
Therefore, it i8 desirable to make such an arrangement more com-pact to be placed in the sewing machine. As to the latter ar-rangement, it becomes necessary to provide additional devices for setting the needle position and the angular position of the lower shaft into alignment, because the rotation ratio of the main shaft is different from that of the lower shaft depending upon the types of sewing machines. In any case, such prior arrangements have been practically inconvenient and unsatisfactory.
The present invention provides a specific arrangement simple in structure and useful in function, to meet the required objectives, and is free from the defects and disadvantages of the prior art.
The primary object of the invention is to provide a sew-ing machine in which the detecting device of the invention in-cluding a needle position detecting element and an element to be r~
..~ ,.
, - ' :
1046~51 detected is accommodated within the pulley of the sewing machine, instead of being provided on the outside of the sewing machine, so that the sewing machine provided with the invention may be placed in a more compact space in an industrial sewing factory or in the home, and so that the arrangement may not be a hind-rance when it becomes necessary to fix or examine the sewing machine, all the more to improve the operating condition as well as operating efficiency.
Another object of the invention is to provide an ar-rangement in which the detecting element and the element to bedetected are placed in a sewing machine with no touching contact so that the sewing machine may be free from associated vibration, and noise which may be generated in the prior art, and according-ly the sewing machine with the invention is free from the wear and heat generated by friction, and 90 that the elements employed may be longer lasting to avoid a decrease in operating efficiency which may be caused by having to exchange elements during the sewing operation.
Another object of the invention is to provide a new needle position detecting arrangement for sewing machines which is free from the danger of error operations, and is reliable as well as longer lasting as compared with the prior arrangement of slip ring and brush type in which error operations have often occurred from the wear caused at the slip ring as well as at the brush, or from the particles produced as the result of the wear at the slip ring and the brush.
Another object of the invention is to provide a new needle position detecting arrangement for sewing machines which can be cheaply produced and which requires less maintenance, since the arrangement includes the detecting device which consists of a Hall generator as a detecting element and a magnet as an element to be detected so that the device may be simple as well 1046~51 as small, and also the associated electric circuit is simplified. -Another object of the invention is to save the number of Hall generators employed to less than the half as compared with the number of Hall generators generally employed, because in the arrangement of the invention the Hall generator i8 activated by the positive and negative magnetic fields of the magnet to make good use of the variation of electric signal due to the change of the polarities, thereby to detect the needle position.
Yet another object of the invention is to detect the needle position as an electric signal lasting for a certain period of time, by way of a yoke provided on the Hall generator or on the magnet to form a magnetic circuit with a proper width. With the use of such a yoke, one Hall generator is sufficient to be employed in the invention. However, if two Hall generators are employed, the use of the yoke becomes unnece~sary. Thus the combination of the electric signal i~sued from the Hall generators or Hall generator with an electrical memory circuit makes it pos-sible to detect the needle position as an electric signal lasting for a certain period of time.
The invention is thus concerned with a needle position detecting arrangement for sewing machines comprising a machine housing, a main shaft rotatably journalled in the machine housing, a needle connected to the main shaft and vertically reciprocated therefrom, a rotary member fixedly mounted on the main shaft, a Hall generator mounted on the machine housing, and magnet means secured to a face of the rotary member opposite to the Hall generator with a clearance provided between the magnet and the Hall generator with a clearance provided between the ma ~ and the Hall generator so that the magnet means may be detected by the Hall generator during the rotation of the rotary member.
~ ` .
More particularly the invention provides an improved arrangement in a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting the needle and the shaft for converting rotational movement of the shaft into longitudinal reciprocating movement of the needle, a hollow drive pulley fixedly mounted on one end of the main shaft, and a drive arrangement for driving the main shaft including a drive belt trained around the hollow drive pu 1 ley .
The improved arrangement includes magnet means mounted inside the hollow drive pulley for rotation there*ith, flux-responsive means; and mounting means mounting the flux-responsive means on a stationary part of ths sewing machine with such an orientation relative to the path of motion of the magnet means that when the drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of the needle, a flux-responsive voltage is induced in the flux-responsive means. The flux-responsive means comprises Hall generator means.
In one embodiment the Hall generator means includes a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes, and there is further included current source means connected across the control electrodes for establishing flow of a control current through the Hall generator semiconductor element. A detecting circuit is included, which comprises a pair of transistors, and means connecting the electrodes of the transistors to the electrodes of the Hall generator semiconductor element such that when magnetic flux of one polarity passes through the semiconductor element 4ne of the transistors becomes conductive, whereas when magnetic flux of opposite polarity passes through the semi-conductor element the other of the transistors ~? '.
... .
becomes conductive.
In a different a~pect of this embodiment the circuit includes a first electronic switch element having a control input connected between one of the Hall-voltage electrodes and one of the control electrodes of the Hall generator semiconductor element, and a second electronic switch element having a control input connected between the other Hall-voltage --electrode and the other control electrode of the Hall generator semiconductor element. In this aspect the magnet means comprises two permanent magnets mounted inside the hollow drive pulley member and angularly off-set from each other and having respective orientations such that whenone of the - ~-magnets passes the Hall generator semiconductor element, magnetic flux of one polarity penetrates the latter, whereas when the other of the magnets passes the Hall generator semiconductor element, magnetic flux of opposite polarity penetrates the latter.
In another embodiment the Hall generator means in-cludes a Hallsemiconductor element and magnetic yoke means posi~ioned adjacent the Hall semiconductor element, the magnetic yoke means extending in direction circumferentially of the axis of rotation of the rotary member and s~erving to form a magnetic circuit with the magnet means when the magnet means rotates into the vicinity of the yoke means, the yoke means being so configured and oriented with respect to the Hall semiconductor element as to effect passage through the latter of the flux originating from the magnet means when the angular orientation of the rotary member lies within a predetermined range corres-pnding to the circumferential extension of the yoke means, to induce in the Hall semiconductor element a Hall voltage indicating when the angular rotation of the rotary member lies within the predetermined range.
In yet another embodiment the magnet mean~ comprises two permanent magnet~ each mounted on the rotary member for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of the rotary met~ber, the polarization of the two permanent magnets differing in such a manner that when one of the magnets passes by the Hall generator means a first Hall voltage is generated whereas when the other of the magnets passes by the Hall generator means a second Hall voltage distinguishable from the first Hall voltage is generated.
Other features and advantages of the invention will be apparent from the following description of the preferred embodi-ments together with the attached drawings, in which:-Figure 1 is a perspective view of a sewing machine equipped w1th the invention.
Figure 2 shows a Hall generator and its associated magnetic fiel~.
Figure 3 shows a schematic view of an electric circuit in which the Hall generator is used.
Figure 4 is a "characteristic curve" of the Hall generator.
Figure-5 shows a schematic view of an electric circuit in accordance with one embodiment of the invention.
Figure 6 shows a schematic view of a magnetic circuit acting as a detecting device.
Figure 7 shows a relation between the magnet and the yoke in which the magnet gives a magnetic flux to the Hall generator for a certain period of tLme.
Figure 8 shows another embodiment of an electric cir-cuit in which one more Hall generator i8 additionally used as compared with the first embodiment shown in Figure 5.
Figure 9 shows a vertical section of the main device in which the first embodiment of the invention is provided.
Figure 10 shows a vertical section viewed from the dir-ection of the arrow marks in Figure 9.
Figure 11, which appears on the same sheet as Figure 8, shows the structures respectively of the Hall generator, the yoke and the seat for the deteçting element.
Figure 12 shows a vertical Qection of the main device in which the second embodiment of the invention is provided.
Figure 13 shows a vertical section viewed from the direction of the arrow marks in Figure 12.
Figure 14 shows a vertical section of the main device in which a modification of the second embodiment of the invention is provided, and Figure 15 shows a vertical section viewed from the direction of the arrow marks in Figure 14.
Referring to Figure 1, there is a Hall generator 3, which i8 a detecting element, fixed on one side of a machine housing 1 and electrically connected to an electric control cir-cuit 4~ A magnet 5, which is an element to be detected, is fix-edly mounted in a proper^position on the inner face of a pulley 6 in such a manner that the magnet may rotate in a locus spaced from the oppositely positioned Hall generator during its rotation with the pulley 6. The portion represented in chain line on the `iv - 8 _ '' ' ~ ', , ~, -10461Sl right side of the pulley shows a detecting device of the prior art so mounted.
To more fully describe one embodiment of the invention, reference i8 had to Figures 9 - 11, wherein reference numeral 8 indicates a main shaft of the sewing machine. The pulley 6 is fixedly mounted on one end of the main shaft which project3 out of the machine housing 1, by means of a fastening screw 9. Num-eral 10 indicates a seat for the detecting element 3. The ele-ment 3 fixedly mounted on the right side portion 2 of the machine housing 1 by means of a fastening screw 11. The seat has a yoke 12 of the material to allow the passage of magnetism therethrough placed within the seat. The yoke fixedly clamp~ a part of the Hall generator 3 which is used as a detecting element, so that the magnetic field of the magnet 5 may pass through the Hall generator by way of the yoke. Numeral 13 indicates an electric cord con-necting the Hall generator 3 and the electric control circuit 4.
The ~agnet 5, as an element to be detected, is fixedly mounted together with a yoke 15 of the same material as the yoke 12 for the Hall generator in the bowl shaped portion 14 of the pulley 6 which is placed on the right hand side of the machine housing 1.
As there is provided a proper clearance 16 between the yoke 12 and the yoke 15 on the side of the Hall generator, the detecting element 3 and the element 5 to be detected will never come into contact with each other during the rotation of the element 5 around the detecting element 3 together with the pulley 6.
During the rotation of the magnet 5, when it comes to the position near the yoke 12 of the Hall generator 3, the mag-netic field of the magnet 5 passes across the clearance 16 to the yoke 12 of the Hall generator 3, and after it passes through the Hall generator 3, it returns the yoke 15 of the magnet 5 over the clearance 16 as shown in Figure 6~ During such a passage of the magnetic field, there appears a Hall voltage, as will be _ g _ .
-described herein later, which will transmit to the electric con-trol circuit a signal indicating that the magnet 5 i~ approaching the Hall generator 3. Since the sewing machine is so con~tructed that one rotation of the main shaft 8 corresponds to one vertical reciprocation of the needle 17, it becomes possible to detect the upper and lower dead points of the needle with the use of one Hall generator 3, if the magnet 5 and the yoke 15 are mounted at a position in the pulley 6 so that they may come near the Hall generator when the needle is at the upper dead point while an-other magnet 18 and a yoke 19 are mounted at the diametricallyopposite position in the pulley 6 as shown in Figure 9.
To describe the embodiment and function of the Hall gener~tor and the electric control circuit, the Hall generator is, as well known, a generator element with a property of Hall effect, which iB a voltage (Hall voltage) generated in a certain condition. Namely, a rectangular sample of material is placed in a magnetic field with a certain strength in such a manner that the surface of thé sample material may intersect the mag-netic field at right angles. If an electric current is applied to one opposite side of the sample material, a certain amount of voltage is generated on the other opposite side of the rec-tangular sample material. In Figure 2, an electric current is applied to the control electrodes (S) of the Hall generator 3.
When the magnetic field (M) passes through the Hall generator, a voltage is generated on the Hall electrodes (H). If the con-trol voltages (VHl) and (VH~) are to be derived from between the Hall electrodes (H) and the control electrodes (S) by means of the Hall generator 3 as shown in Figure 3, the property of con-trol voltages as shown in Figure 4 are obtained depending upon the directions of the magnetic field passing through the Hall generator 3. Namely, if a magnet field (+M) acts on the Hall generator, the control voltage (VHl) will rise. On the contrary, : . . - . ., , :
104615~
if a magnet field (-M) acts on the Hall generator, the control voltage (VH2) will rise. The present invention is designed to make good use of such a property of the Hall generator.
To deæcribe the detection of the needle position of the sewing machine, reference is made to Figure 5 in which an elec-tric control circuit with an amplifier arrangement is shown as one embodiment of the invention. Enclosed by a broken line is a constant current circuit which is designed to increase the elec-tric current supplied to the Hall generator, to raise the environ-mental temperature, and also to compensate the Hall voltage. Theelectric current supplied from the constant current ~ircuit is fed, through the resistor (RA), to the control electrodes of the Hall generator 3. In this instance, if the magnetic field acts on the Hall generator, the base voltage (VHl) or (VH2) of trans-istor (Q2) or ~Q3) will rise and the transistor is controlled.
Now, if the magnetic field (+M) act~ on the Hall generator 3, the control voltage (VHl) ri~es and the transistor (Q2) is closed.
But if the magnetic field (-M) acts on the Hall generator 3, the control voltage (VH2) rises and the transistor (Q3) is closed.
Thus, depending upon the direction of the magnetic field acting on the Hall generator, transistor (Q2) or (Q3) is closed. The embodiment of such a detecting device is, as described hereinbe-fore, conætructed as shown in Figures 9 - 11. Figure 6 shows a magnetic circuit constituted when the magnet 5 on the pulley 6 approaches to the yoke 12 of the Hall generator 3. In this in-~tance, when the magnetic flux 20 from the magnet 5 acts on the Hall generator 3 as the magnet field (+M) through the yokes 15 and 12, the transistor (Q2) in Figure 5 is clo~ed.
Next, when the magnet 18 of a reversed polarity approaches to the yoke 12 of the Hall generator 3, the magnetic flux (-M) will act on the Hall generator 3 and the transistor (Q3) will be closed. Provided that the magnet 5 is designed to detect ,~
the upper dead point of the needle while the magnet 18 is design-ed to detect the lower dead point of the needle, these two dead poi~ts of the needle will be detected through the transistors (Q2) and (Q3) as a signal kept effective for a period of time which is determined by the width (BM in Figure 10), of the magnet, in the rotating direction and by the width (BY), of the yoke 12 of the Hall generator 3, in the rotating direction of the pulley 6.
Figure 11 shows a detecting device, relative to Figure 10, in which the seat 10 has the yoke 12 embedded therein, which 1~ in turn holds the Hall generator 3 in a clamped condition. Fig-ure lla shows the detecting device viewed from the same direction as that of Figure 10. Figure llb shows a plan view of the detect-ing device in Figure lla, and Figure llc shows a view from the left hand side of the same device in Figure lla. In this detect-ing device, the magnet 5 has a width (BM) in its rotating direc-tion aq shown in Figure 10 ~hile the yoke 12 of the Hall generator 3 has a width (BY) in the rotating direction of the pulley 6.
Accordingly the magnetic flux from the magnet 5 will act on the ~ -yoke 12 in the region BY - BM. Since the yoke 12 i9, as afore-mentioned, made of the material allowing the magnetic flux to pass through so that the magnetic flux acting on any part of the yoke 12 may pass through the Hall generator 3, it can be said that the region on which ~he magnetic flux evenly acts is BY - ~M.
It is, therefore, apparent that since a signal will be continuously generated for a certain period of time during the passage of the magnet 5 through the predetermined region, a break-ing mechanism of the sewing machine (not shown) may be actuated in response to the signal to stop the performance of the sewing machine when the needle is brought to the position near the upper dead point thereof.
With respect to the width of the magnet 5 and of the yoXe 12 of the Hall generator 3, it is essential that they be .. . ~
~' ' ' . , " ' . .
1~46~51 designed to attain the object that a certain width of the magnetic flux may pass through the Hall generator for a predetermined period of time. According to the embodiment of the invention as shown in Figure 7a, the yoke 12 of the Hall generator 3 i8 wider than the magnet 5. But the magnet 5 may be wider, and the yoke 12 may be eliminated as shown in Figure 7b to obtain the qame effect.
It will also be apparent that the polarities N and S of one magnet may be used as corresponding to the upper and lower dead points of the needle respectively without using two magnets for the two dead points of the needle respectively.
Another embodiment of the invention is shown in Figures - 8 and 12 - 15 in which one more Hall generator 21 i9 employed.
According to the second embodiment in reference to the electric circuit in Figure 8I the transistors (Q4) and (Q6) are closed when the magnetic flux (+M) acts on the Hall generators 3 and 21, and the transistors (Q5) and (Q7) are closed when the magnetic flux (-M) acts on the Hall generators 3 and 21. Thu~, when the magnet 22 approaches to the Hall generator 3 as the pulley 6 ro-tates in the direction indicated by the arrow as shown in Figure 13, the transistor (Q4) is closed to generate a signal pulse. If the signal pulse is applied as a setting pulse to a memory element, such as for example, a flip-flop, while a signal generated by Q5 as the magnet 23 approaches to the Hall generator 21 is made to be a resetting signal, the signal for detecting the upper dead point of the needle of the sewing machine will be obtained for a lLmited per-iod of time. The signal for detecting the lower dead point of the needle will be obtained by properly arranging the magnets 22 and 23 relatively of the Hall generator 21. The magnets 22 and 23 may be replaced by a proper use of the polarity of one magnet to obtain the same effect.
According to the detecting device shown in Figures 14 and 15, the signals for detecting the upper and lower dead points 1046~51 of the needle are given from the magnets 22 and 24 respectively, and the detecting realms are determined by the ~all generators 3 and 21. Namely, the ~etting pulses are given at the output term-inals 04 and 05, and the re~etting pulses are given at the output terminals 06 and 07 in Figure 8.
According to the first and second embodiments of the invention, one magnet i utilized to generate two kinds of signals depending upon the polarity of the magnet. It is, however, pos-sible that the Hall generator is utilized to generate one signal from between the Hall electrodes in the original usage of the Hall generator. In such a case, it is apparent that two Hall gen-erators are needed in the first embodiment of the invention while four Hall generators are needed in the second embodiment of the invention.
In the two kinds of embodiments of the invention, the ~all generators and the magnets are mounted in the pulley of the sewing machine. But these elements may be mounted on the other part of the sewing machine as occasion demands. The magnet may be mounted, for example, on a rotary member of the sewing machine such as the thread take up lever crank which is rotated in assoc-iation with the main shaft of the sewing machine, and the Hall generator may be mounted on a part of the machine housing adja-cent to the thread take up lever crank.
It is also apparent that the Hall generator may be re-placed by a magnetoresistance element in the same qtructure of the invention to maintain the same effect.
... . . .
. . .
The invention relates to a needle position detecting ~--arrangement for sewing machines in which a Hall generator and a magnet are used. The generator and magnet are respectively mounted on the machine housing and a rotating member of the sew-ing machine so that the invention will not disturb the outer appearance of the sewing machine. This is one way in which the invention differs from prior art devices in which the detecting device is mounted on the outside of the sewing machine. At the same time, the invention provides an almost permanently lasting needle position detecting arrangement for sewing machines which is free from the shortcomings such as vibration, noise and temp-erature rise. -~
According to the invention, a pulley is preferably utilized, by way of one example, which is fixed on the end of the main shaft of the sewing machine and projecting outwardly thereof, and a magnet, which is an element to be detected, is provided on the inner side of the pulley facing the machine housing, and the Hall generator, which is a detecting element, is provided on the machine housing opposite to the locus in which the magnet is rotated. Thus the magnet and the Hall generator are accommodated between the machine housing and the pulley so that the magnet, during rotation together with the pulley in synchronism with the motion of the needle of the sewing machine, may be detected by the Hall generator in a fixed position, and the position of the needle may be accordingly detected.
In the conventional needle position detecting arrange-ment for sewing machines, a slip ring is generally arranged as an element to be detected, and a brush as a detecting element for contacting the slip ring. The slip ring has a nonconductive part provided therein corresponding to a predetermined position of the needle in its motion in such a manner that when the brush contacts the nonconductive part, the associated electric circuit is deener-gized, and then the brake mechanism is actuated. Such a conven-tional arrangement, however, has many defects and difficultie~
caused by vibration, noise, a~ well as error operations caused by damage of the brush or short-circuit of the nonconductive part, all due to the contact between the 81ip ring and the brush.
Moreover, in such a conventional arrangement, the ~lip ring and the brush are generally mounted on the outside of the pulley which i~ fixedly connected to the main shaft of the sewing mach-ine, and other arrangements have been used where the needle posi-tion is detected by the lower shaft which is rotated in synchron-ism with the main shaft of the sewing machine. In the former arrangement, the slip ring and the brush are provided on the out-side of the sewing machine to simplify the assembly and to make its security easier. But the arrangement becomes bulky and the outer appearance becomes undesirable. Moreover, the arrangement stands in the way and accordingly it must be removed when it be-comes necessary to examine the mechanisms in the machine housing.
Therefore, it i8 desirable to make such an arrangement more com-pact to be placed in the sewing machine. As to the latter ar-rangement, it becomes necessary to provide additional devices for setting the needle position and the angular position of the lower shaft into alignment, because the rotation ratio of the main shaft is different from that of the lower shaft depending upon the types of sewing machines. In any case, such prior arrangements have been practically inconvenient and unsatisfactory.
The present invention provides a specific arrangement simple in structure and useful in function, to meet the required objectives, and is free from the defects and disadvantages of the prior art.
The primary object of the invention is to provide a sew-ing machine in which the detecting device of the invention in-cluding a needle position detecting element and an element to be r~
..~ ,.
, - ' :
1046~51 detected is accommodated within the pulley of the sewing machine, instead of being provided on the outside of the sewing machine, so that the sewing machine provided with the invention may be placed in a more compact space in an industrial sewing factory or in the home, and so that the arrangement may not be a hind-rance when it becomes necessary to fix or examine the sewing machine, all the more to improve the operating condition as well as operating efficiency.
Another object of the invention is to provide an ar-rangement in which the detecting element and the element to bedetected are placed in a sewing machine with no touching contact so that the sewing machine may be free from associated vibration, and noise which may be generated in the prior art, and according-ly the sewing machine with the invention is free from the wear and heat generated by friction, and 90 that the elements employed may be longer lasting to avoid a decrease in operating efficiency which may be caused by having to exchange elements during the sewing operation.
Another object of the invention is to provide a new needle position detecting arrangement for sewing machines which is free from the danger of error operations, and is reliable as well as longer lasting as compared with the prior arrangement of slip ring and brush type in which error operations have often occurred from the wear caused at the slip ring as well as at the brush, or from the particles produced as the result of the wear at the slip ring and the brush.
Another object of the invention is to provide a new needle position detecting arrangement for sewing machines which can be cheaply produced and which requires less maintenance, since the arrangement includes the detecting device which consists of a Hall generator as a detecting element and a magnet as an element to be detected so that the device may be simple as well 1046~51 as small, and also the associated electric circuit is simplified. -Another object of the invention is to save the number of Hall generators employed to less than the half as compared with the number of Hall generators generally employed, because in the arrangement of the invention the Hall generator i8 activated by the positive and negative magnetic fields of the magnet to make good use of the variation of electric signal due to the change of the polarities, thereby to detect the needle position.
Yet another object of the invention is to detect the needle position as an electric signal lasting for a certain period of time, by way of a yoke provided on the Hall generator or on the magnet to form a magnetic circuit with a proper width. With the use of such a yoke, one Hall generator is sufficient to be employed in the invention. However, if two Hall generators are employed, the use of the yoke becomes unnece~sary. Thus the combination of the electric signal i~sued from the Hall generators or Hall generator with an electrical memory circuit makes it pos-sible to detect the needle position as an electric signal lasting for a certain period of time.
The invention is thus concerned with a needle position detecting arrangement for sewing machines comprising a machine housing, a main shaft rotatably journalled in the machine housing, a needle connected to the main shaft and vertically reciprocated therefrom, a rotary member fixedly mounted on the main shaft, a Hall generator mounted on the machine housing, and magnet means secured to a face of the rotary member opposite to the Hall generator with a clearance provided between the magnet and the Hall generator with a clearance provided between the ma ~ and the Hall generator so that the magnet means may be detected by the Hall generator during the rotation of the rotary member.
~ ` .
More particularly the invention provides an improved arrangement in a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting the needle and the shaft for converting rotational movement of the shaft into longitudinal reciprocating movement of the needle, a hollow drive pulley fixedly mounted on one end of the main shaft, and a drive arrangement for driving the main shaft including a drive belt trained around the hollow drive pu 1 ley .
The improved arrangement includes magnet means mounted inside the hollow drive pulley for rotation there*ith, flux-responsive means; and mounting means mounting the flux-responsive means on a stationary part of ths sewing machine with such an orientation relative to the path of motion of the magnet means that when the drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of the needle, a flux-responsive voltage is induced in the flux-responsive means. The flux-responsive means comprises Hall generator means.
In one embodiment the Hall generator means includes a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes, and there is further included current source means connected across the control electrodes for establishing flow of a control current through the Hall generator semiconductor element. A detecting circuit is included, which comprises a pair of transistors, and means connecting the electrodes of the transistors to the electrodes of the Hall generator semiconductor element such that when magnetic flux of one polarity passes through the semiconductor element 4ne of the transistors becomes conductive, whereas when magnetic flux of opposite polarity passes through the semi-conductor element the other of the transistors ~? '.
... .
becomes conductive.
In a different a~pect of this embodiment the circuit includes a first electronic switch element having a control input connected between one of the Hall-voltage electrodes and one of the control electrodes of the Hall generator semiconductor element, and a second electronic switch element having a control input connected between the other Hall-voltage --electrode and the other control electrode of the Hall generator semiconductor element. In this aspect the magnet means comprises two permanent magnets mounted inside the hollow drive pulley member and angularly off-set from each other and having respective orientations such that whenone of the - ~-magnets passes the Hall generator semiconductor element, magnetic flux of one polarity penetrates the latter, whereas when the other of the magnets passes the Hall generator semiconductor element, magnetic flux of opposite polarity penetrates the latter.
In another embodiment the Hall generator means in-cludes a Hallsemiconductor element and magnetic yoke means posi~ioned adjacent the Hall semiconductor element, the magnetic yoke means extending in direction circumferentially of the axis of rotation of the rotary member and s~erving to form a magnetic circuit with the magnet means when the magnet means rotates into the vicinity of the yoke means, the yoke means being so configured and oriented with respect to the Hall semiconductor element as to effect passage through the latter of the flux originating from the magnet means when the angular orientation of the rotary member lies within a predetermined range corres-pnding to the circumferential extension of the yoke means, to induce in the Hall semiconductor element a Hall voltage indicating when the angular rotation of the rotary member lies within the predetermined range.
In yet another embodiment the magnet mean~ comprises two permanent magnet~ each mounted on the rotary member for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of the rotary met~ber, the polarization of the two permanent magnets differing in such a manner that when one of the magnets passes by the Hall generator means a first Hall voltage is generated whereas when the other of the magnets passes by the Hall generator means a second Hall voltage distinguishable from the first Hall voltage is generated.
Other features and advantages of the invention will be apparent from the following description of the preferred embodi-ments together with the attached drawings, in which:-Figure 1 is a perspective view of a sewing machine equipped w1th the invention.
Figure 2 shows a Hall generator and its associated magnetic fiel~.
Figure 3 shows a schematic view of an electric circuit in which the Hall generator is used.
Figure 4 is a "characteristic curve" of the Hall generator.
Figure-5 shows a schematic view of an electric circuit in accordance with one embodiment of the invention.
Figure 6 shows a schematic view of a magnetic circuit acting as a detecting device.
Figure 7 shows a relation between the magnet and the yoke in which the magnet gives a magnetic flux to the Hall generator for a certain period of tLme.
Figure 8 shows another embodiment of an electric cir-cuit in which one more Hall generator i8 additionally used as compared with the first embodiment shown in Figure 5.
Figure 9 shows a vertical section of the main device in which the first embodiment of the invention is provided.
Figure 10 shows a vertical section viewed from the dir-ection of the arrow marks in Figure 9.
Figure 11, which appears on the same sheet as Figure 8, shows the structures respectively of the Hall generator, the yoke and the seat for the deteçting element.
Figure 12 shows a vertical Qection of the main device in which the second embodiment of the invention is provided.
Figure 13 shows a vertical section viewed from the direction of the arrow marks in Figure 12.
Figure 14 shows a vertical section of the main device in which a modification of the second embodiment of the invention is provided, and Figure 15 shows a vertical section viewed from the direction of the arrow marks in Figure 14.
Referring to Figure 1, there is a Hall generator 3, which i8 a detecting element, fixed on one side of a machine housing 1 and electrically connected to an electric control cir-cuit 4~ A magnet 5, which is an element to be detected, is fix-edly mounted in a proper^position on the inner face of a pulley 6 in such a manner that the magnet may rotate in a locus spaced from the oppositely positioned Hall generator during its rotation with the pulley 6. The portion represented in chain line on the `iv - 8 _ '' ' ~ ', , ~, -10461Sl right side of the pulley shows a detecting device of the prior art so mounted.
To more fully describe one embodiment of the invention, reference i8 had to Figures 9 - 11, wherein reference numeral 8 indicates a main shaft of the sewing machine. The pulley 6 is fixedly mounted on one end of the main shaft which project3 out of the machine housing 1, by means of a fastening screw 9. Num-eral 10 indicates a seat for the detecting element 3. The ele-ment 3 fixedly mounted on the right side portion 2 of the machine housing 1 by means of a fastening screw 11. The seat has a yoke 12 of the material to allow the passage of magnetism therethrough placed within the seat. The yoke fixedly clamp~ a part of the Hall generator 3 which is used as a detecting element, so that the magnetic field of the magnet 5 may pass through the Hall generator by way of the yoke. Numeral 13 indicates an electric cord con-necting the Hall generator 3 and the electric control circuit 4.
The ~agnet 5, as an element to be detected, is fixedly mounted together with a yoke 15 of the same material as the yoke 12 for the Hall generator in the bowl shaped portion 14 of the pulley 6 which is placed on the right hand side of the machine housing 1.
As there is provided a proper clearance 16 between the yoke 12 and the yoke 15 on the side of the Hall generator, the detecting element 3 and the element 5 to be detected will never come into contact with each other during the rotation of the element 5 around the detecting element 3 together with the pulley 6.
During the rotation of the magnet 5, when it comes to the position near the yoke 12 of the Hall generator 3, the mag-netic field of the magnet 5 passes across the clearance 16 to the yoke 12 of the Hall generator 3, and after it passes through the Hall generator 3, it returns the yoke 15 of the magnet 5 over the clearance 16 as shown in Figure 6~ During such a passage of the magnetic field, there appears a Hall voltage, as will be _ g _ .
-described herein later, which will transmit to the electric con-trol circuit a signal indicating that the magnet 5 i~ approaching the Hall generator 3. Since the sewing machine is so con~tructed that one rotation of the main shaft 8 corresponds to one vertical reciprocation of the needle 17, it becomes possible to detect the upper and lower dead points of the needle with the use of one Hall generator 3, if the magnet 5 and the yoke 15 are mounted at a position in the pulley 6 so that they may come near the Hall generator when the needle is at the upper dead point while an-other magnet 18 and a yoke 19 are mounted at the diametricallyopposite position in the pulley 6 as shown in Figure 9.
To describe the embodiment and function of the Hall gener~tor and the electric control circuit, the Hall generator is, as well known, a generator element with a property of Hall effect, which iB a voltage (Hall voltage) generated in a certain condition. Namely, a rectangular sample of material is placed in a magnetic field with a certain strength in such a manner that the surface of thé sample material may intersect the mag-netic field at right angles. If an electric current is applied to one opposite side of the sample material, a certain amount of voltage is generated on the other opposite side of the rec-tangular sample material. In Figure 2, an electric current is applied to the control electrodes (S) of the Hall generator 3.
When the magnetic field (M) passes through the Hall generator, a voltage is generated on the Hall electrodes (H). If the con-trol voltages (VHl) and (VH~) are to be derived from between the Hall electrodes (H) and the control electrodes (S) by means of the Hall generator 3 as shown in Figure 3, the property of con-trol voltages as shown in Figure 4 are obtained depending upon the directions of the magnetic field passing through the Hall generator 3. Namely, if a magnet field (+M) acts on the Hall generator, the control voltage (VHl) will rise. On the contrary, : . . - . ., , :
104615~
if a magnet field (-M) acts on the Hall generator, the control voltage (VH2) will rise. The present invention is designed to make good use of such a property of the Hall generator.
To deæcribe the detection of the needle position of the sewing machine, reference is made to Figure 5 in which an elec-tric control circuit with an amplifier arrangement is shown as one embodiment of the invention. Enclosed by a broken line is a constant current circuit which is designed to increase the elec-tric current supplied to the Hall generator, to raise the environ-mental temperature, and also to compensate the Hall voltage. Theelectric current supplied from the constant current ~ircuit is fed, through the resistor (RA), to the control electrodes of the Hall generator 3. In this instance, if the magnetic field acts on the Hall generator, the base voltage (VHl) or (VH2) of trans-istor (Q2) or ~Q3) will rise and the transistor is controlled.
Now, if the magnetic field (+M) act~ on the Hall generator 3, the control voltage (VHl) ri~es and the transistor (Q2) is closed.
But if the magnetic field (-M) acts on the Hall generator 3, the control voltage (VH2) rises and the transistor (Q3) is closed.
Thus, depending upon the direction of the magnetic field acting on the Hall generator, transistor (Q2) or (Q3) is closed. The embodiment of such a detecting device is, as described hereinbe-fore, conætructed as shown in Figures 9 - 11. Figure 6 shows a magnetic circuit constituted when the magnet 5 on the pulley 6 approaches to the yoke 12 of the Hall generator 3. In this in-~tance, when the magnetic flux 20 from the magnet 5 acts on the Hall generator 3 as the magnet field (+M) through the yokes 15 and 12, the transistor (Q2) in Figure 5 is clo~ed.
Next, when the magnet 18 of a reversed polarity approaches to the yoke 12 of the Hall generator 3, the magnetic flux (-M) will act on the Hall generator 3 and the transistor (Q3) will be closed. Provided that the magnet 5 is designed to detect ,~
the upper dead point of the needle while the magnet 18 is design-ed to detect the lower dead point of the needle, these two dead poi~ts of the needle will be detected through the transistors (Q2) and (Q3) as a signal kept effective for a period of time which is determined by the width (BM in Figure 10), of the magnet, in the rotating direction and by the width (BY), of the yoke 12 of the Hall generator 3, in the rotating direction of the pulley 6.
Figure 11 shows a detecting device, relative to Figure 10, in which the seat 10 has the yoke 12 embedded therein, which 1~ in turn holds the Hall generator 3 in a clamped condition. Fig-ure lla shows the detecting device viewed from the same direction as that of Figure 10. Figure llb shows a plan view of the detect-ing device in Figure lla, and Figure llc shows a view from the left hand side of the same device in Figure lla. In this detect-ing device, the magnet 5 has a width (BM) in its rotating direc-tion aq shown in Figure 10 ~hile the yoke 12 of the Hall generator 3 has a width (BY) in the rotating direction of the pulley 6.
Accordingly the magnetic flux from the magnet 5 will act on the ~ -yoke 12 in the region BY - BM. Since the yoke 12 i9, as afore-mentioned, made of the material allowing the magnetic flux to pass through so that the magnetic flux acting on any part of the yoke 12 may pass through the Hall generator 3, it can be said that the region on which ~he magnetic flux evenly acts is BY - ~M.
It is, therefore, apparent that since a signal will be continuously generated for a certain period of time during the passage of the magnet 5 through the predetermined region, a break-ing mechanism of the sewing machine (not shown) may be actuated in response to the signal to stop the performance of the sewing machine when the needle is brought to the position near the upper dead point thereof.
With respect to the width of the magnet 5 and of the yoXe 12 of the Hall generator 3, it is essential that they be .. . ~
~' ' ' . , " ' . .
1~46~51 designed to attain the object that a certain width of the magnetic flux may pass through the Hall generator for a predetermined period of time. According to the embodiment of the invention as shown in Figure 7a, the yoke 12 of the Hall generator 3 i8 wider than the magnet 5. But the magnet 5 may be wider, and the yoke 12 may be eliminated as shown in Figure 7b to obtain the qame effect.
It will also be apparent that the polarities N and S of one magnet may be used as corresponding to the upper and lower dead points of the needle respectively without using two magnets for the two dead points of the needle respectively.
Another embodiment of the invention is shown in Figures - 8 and 12 - 15 in which one more Hall generator 21 i9 employed.
According to the second embodiment in reference to the electric circuit in Figure 8I the transistors (Q4) and (Q6) are closed when the magnetic flux (+M) acts on the Hall generators 3 and 21, and the transistors (Q5) and (Q7) are closed when the magnetic flux (-M) acts on the Hall generators 3 and 21. Thu~, when the magnet 22 approaches to the Hall generator 3 as the pulley 6 ro-tates in the direction indicated by the arrow as shown in Figure 13, the transistor (Q4) is closed to generate a signal pulse. If the signal pulse is applied as a setting pulse to a memory element, such as for example, a flip-flop, while a signal generated by Q5 as the magnet 23 approaches to the Hall generator 21 is made to be a resetting signal, the signal for detecting the upper dead point of the needle of the sewing machine will be obtained for a lLmited per-iod of time. The signal for detecting the lower dead point of the needle will be obtained by properly arranging the magnets 22 and 23 relatively of the Hall generator 21. The magnets 22 and 23 may be replaced by a proper use of the polarity of one magnet to obtain the same effect.
According to the detecting device shown in Figures 14 and 15, the signals for detecting the upper and lower dead points 1046~51 of the needle are given from the magnets 22 and 24 respectively, and the detecting realms are determined by the ~all generators 3 and 21. Namely, the ~etting pulses are given at the output term-inals 04 and 05, and the re~etting pulses are given at the output terminals 06 and 07 in Figure 8.
According to the first and second embodiments of the invention, one magnet i utilized to generate two kinds of signals depending upon the polarity of the magnet. It is, however, pos-sible that the Hall generator is utilized to generate one signal from between the Hall electrodes in the original usage of the Hall generator. In such a case, it is apparent that two Hall gen-erators are needed in the first embodiment of the invention while four Hall generators are needed in the second embodiment of the invention.
In the two kinds of embodiments of the invention, the ~all generators and the magnets are mounted in the pulley of the sewing machine. But these elements may be mounted on the other part of the sewing machine as occasion demands. The magnet may be mounted, for example, on a rotary member of the sewing machine such as the thread take up lever crank which is rotated in assoc-iation with the main shaft of the sewing machine, and the Hall generator may be mounted on a part of the machine housing adja-cent to the thread take up lever crank.
It is also apparent that the Hall generator may be re-placed by a magnetoresistance element in the same qtructure of the invention to maintain the same effect.
... . . .
. . .
Claims (9)
1. In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational move-ment of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation there-with; flux-responsive. means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means including a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes; and further including current source means connected across said control electrodes for-establishing flow of a control current through said Hall generator semi-conductor element; and a detecting circuit comprising a pair of transistors and means so connecting the electrodes of said transistors to the electrodes of said Hall generator semiconductor element that when magnetic flux of one polarity passes through said semiconductor element one of said tran-sistors becomes conductive whereas when magnetic flux of opposite polarity passes through said semiconductor element the other of said transistors becomes conductive.
2. In a sewing machine as defined in claim 1, wherein said current source means comprises a constant-current source.
3. In a sewing machine as defined in claim 1 or 2, wherein said magnet means comprises a permanent magnet extending in direction circumferentially with respect to the axis of rotation of said rotary member a distance several times greater than the circumferential extent of said Hall semiconductor element with respect to said axis.
4. In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith; flux-responsive means: and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a pre-determined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means including a Hall semi-conductor element and magnetic yoke means positioned adjacent said Hall semiconductor element, said magnetic yoke means extending in direction circumferentially of the axis of rotation of said rotary member and serving to form a magnetic circuit with said magnet means when said magnet means rotates into the vicinity of said yoke means, said yoke means being so configured and oriented with respect to said Hall semiconductor element as to effect passage through the latter of the flux originating from said magnet means when the angular orientation of said rotary member lies within a predetermined range corresponding to the circumferential extension of said yoke means, to induce in said Hall semiconductor element a Hall voltage indicating when the angular rotation of said rotary member lies within said predetermined range.
5. In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation there-with; flux-responsive means; and mounting means mounting said flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a pre-determined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means, and wherein said magnet means comprises two permanent magnets each mounted on said hollow pulley for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of said hollow pulley the polarization of said two permanent magnets differing in such a manner that when one of the magnets passes by said Hall generator means a first Hall voltage is generated whereas when the other of the magnets passes by said Hall generator means a second Hall voltage distinguishable from said first Hall voltage is generated.
6. In a sewing machine as defined in claim 5, wherein said magnet means comprises two permanent magnets each mounted on said hollow pulley for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of said hollow pulley and wherein said Hall generator means comprises two Hall generator units spaced from each other in direction circumferentially of the axis of rotation of said hollow pulley.
7. In a sewing machine as defined in claim 6, wherein each of said two magnets extends in direction circumferentially with respect to said axis a distance greater than the distance through which each of said Hall generator units extends in circumferential direction.
8. In a sewing machine as defined in claim 6, wherein each of said two magnets extends in direction circumferentially with respect to said axis a distance less than the distance through which said Hall generator units extend in circumferential direction.
9. In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith, flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orient-ation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes, and further including means connected across said control electrodes for establishing a flow of control current through said Hall generator semiconductor element: and circuit means including a first electronic switch element having a control input connected between one of said Hall-voltage electrodes and one of said control electrodes of said Hall generator semiconductor element, and a second electronic switch element having a control input connected between the other of said Hall-voltage electrodes and said one of said control electrodes of said Hall generator semiconductor element, and wherein said magnet means comprises two permanent magnets mounted inside said hollow drive pulley member and angularly off-set from each other and having respective orientations such that when one of said magnets passes said Hall generator semi-conductor element magnetic flux of one polarity penetrates the latter, whereas when the other of said magnets passes said Hall generator semiconductor element magnetic flux of opposite polarity penetrates the latter.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1972053900U JPS577437Y2 (en) | 1972-05-09 | 1972-05-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1046151A true CA1046151A (en) | 1979-01-09 |
Family
ID=12955581
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA170,713A Expired CA1046151A (en) | 1972-05-09 | 1973-05-08 | Needle position detecting arrangement for sewing machines |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US3881435A (en) |
| JP (1) | JPS577437Y2 (en) |
| CA (1) | CA1046151A (en) |
| DE (1) | DE2323443A1 (en) |
| GB (1) | GB1428254A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3972297A (en) * | 1974-01-30 | 1976-08-03 | Union Special Corporation | Sewing machine position and speed sensing system |
| US3990374A (en) * | 1975-03-28 | 1976-11-09 | Frankl & Kirchner | Contactless synchronizer for sewing machines |
| JPS5929661Y2 (en) * | 1977-07-25 | 1984-08-25 | アイシン精機株式会社 | Sewing machine drive control device |
| US4269132A (en) * | 1978-01-13 | 1981-05-26 | Hsu Yung San | Position indicating unit for sewing machines |
| WO2007089603A2 (en) | 2006-01-27 | 2007-08-09 | Suturtek Incorporated | Apparatus and method for tissue closure |
| CN107764176A (en) * | 2016-08-17 | 2018-03-06 | 北京大豪科技股份有限公司 | Pin height detection device and embroidery machine |
| CN107022857A (en) * | 2017-05-23 | 2017-08-08 | 浙江众邦机电科技有限公司 | Stop pin level control device and sewing machine on sewing machine |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2572635A (en) * | 1947-06-07 | 1951-10-23 | Gen Electric | Sewing machine |
| US2872885A (en) * | 1953-02-06 | 1959-02-10 | Schwab Olga Brunhilde | Electric sewing machines |
| JPS4316141Y1 (en) * | 1964-12-11 | 1968-07-04 | ||
| FR2012522A1 (en) * | 1968-07-09 | 1970-03-20 | Quick Rotan Becker & Notz Kg | |
| US3757232A (en) * | 1970-12-18 | 1973-09-04 | Matsushita Electric Ind Co Ltd | Tion device for stopping a rotating member at a predetermined angular posi |
-
1972
- 1972-05-09 JP JP1972053900U patent/JPS577437Y2/ja not_active Expired
-
1973
- 1973-05-04 US US357322A patent/US3881435A/en not_active Expired - Lifetime
- 1973-05-08 CA CA170,713A patent/CA1046151A/en not_active Expired
- 1973-05-09 GB GB2220573A patent/GB1428254A/en not_active Expired
- 1973-05-09 DE DE2323443A patent/DE2323443A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU5548973A (en) | 1974-11-14 |
| JPS4911962U (en) | 1974-01-31 |
| GB1428254A (en) | 1976-03-17 |
| DE2323443A1 (en) | 1973-11-22 |
| US3881435A (en) | 1975-05-06 |
| DE2323443B2 (en) | 1975-11-06 |
| JPS577437Y2 (en) | 1982-02-12 |
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