Sewing machine provided with a threading device and a needle bar raising device

A sewing machine comprising a threading device and a needle-bar raising means. A threading switch is operated and a sewing machine motor is stopped. Subsequently, thread is passed onto a linkage, a needle bar is disconnected from an arm shaft, and the needle bar is raised to a given position. After the needle bar is set in its uppermost position, thread stretched out from the linkage 38 to the front of an eye in a needle is passed through the eye in the needle. If the end of thread is manually held in front of the eye in the needle to stretch out prior to threading operation, the needle bar does not lower, thus enhancing operational safety and preventing thread from loosening.

BACKGROUND OF THE INVENTION 
This invention relates to a sewing machine that is provided with a 
threading device for threading an eye in a needle with thread. 
A sewing machine provided with a threading device is disclosed in Japan 
Published Unexamined Patent Application No. S63-89194. The threading 
device includes a stretching member for catching thread and stretching out 
the thread prior to threading, and a threading member such as a threading 
hook for threading a needle. In related-art sewing machines, an operator 
holds the end of thread and stretches the thread in front or at the rear 
of an eye in a needle. Subsequently, a threading hook is brought through 
the eye in the needle to hook the thread and thread the eye in the needle. 
In the above related-art sewing machines, the threading hook is moved 
toward the eye in the needle for threading. Before the needle is thus 
threaded, a needle bar is raised to a position such that the threading 
hook can come through the eye in the needle attached to the end of the 
needle bar without contacting other component such as a presser foot 
assembly. 
However, the related-art sewing machines have the following problem. 
(1) The eye in the needle should be raised to a given position before the 
thread is stretched out in front or at the rear of the eye in the needle. 
Threading operation is thus intricate. 
(2) To put the thread onto a stretching member for stretching out the 
thread before the threading of the needle, an arm shaft is rotated. The 
needle may lower in its stroke according to the rotation of the arm shaft, 
and a thread guide attached to the needle bar lowers and draws thread from 
a bobbin or the stretching member, thereby loosening the thread. Since the 
thread cannot be stretched out at a given position, the threading member 
fails to thread the eye in the needle. 
(3) If the operator holds the end of the thread passed through the thread 
guide attached to the lower end of the needle bar and rotates the arm 
shaft to stretch out the thread at a given position, the needle may lower 
according to the stroke of the needle corresponding to the rotation of the 
arm shaft. The operator might be hurt at the lowering needle. 
In the related art, the eye in the needle must be raised to the given 
position before the thread is stretched out. 
SUMMARY OF THE INVENTION 
The object of this invention is to provide a sewing machine that can 
position a needle eye in a given position and stretch out thread prior to 
the threading of a needle eye. 
To attain this and other objects, the invention provides a sewing machine 
including a threading device for threading an eye in a needle attached to 
the lower end of a needle bar vertically movable for sewing operation, and 
a needle-bar raising means for raising the needle bar to a given position 
prior to a threading operation regardless of vertical movement of the 
needle bar for sewing operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1, an arm shaft 1 is driven and rotated through a 
sewing-machine motor (not shown). A crankpin 4 is set on a counterbalance 
2 on the arm shaft 1. One end of a connecting rod 6 is rotatably inserted 
into the crankpin 4, and a needle-bar connecting stud 8 is rotatably 
inserted into the other end of the connecting rod 6. The needle-bar 
connecting stud 8 is slidably engaged on a needle bar 10. As shown in FIG. 
3, a groove 12 radially and horizontally extends in the needle-bar 
connecting stud 8. 
A needle bar frame 14 is attached to the needle bar 10. A stud 16 is 
inserted into the needle bar frame 14 and slidably supports a clutch latch 
18 in the needle bar frame 14. One end of a torsion spring 22 is attached 
to the stud 16, and the other end of the torsion spring 22 is engaged on a 
clutch pin 20 inserted into the clutch latch 18 perpendicularly to the 
needle bar 10. The torsion spring 22 applies a force to the clutch latch 
18 so that the end of the clutch latch 18 engages the groove 12 in the 
needle-bar connecting stud 8. The clutch latch 18 can be engaged to and 
disengaged from the groove 12 through the torsion spring 22. As shown in 
FIG. 3, a positioning stopper 24 is secured through a screw 25 onto the 
needle bar 10 at a predetermined position above the needle-bar connecting 
stud 8. A projection 24a projects from the positioning stopper 24 
perpendicularly to the axial direction of the needle bar 10. 
A needle bar support 26 supports the needle bar 10 such that the needle bar 
10 can vertically slide. A needle 32 is attached through a clamp screw 30 
and a needle connecting stud 28 with a thread guide 28a to the lower end 
of the needle bar 10. A threading mechanism 33 adjoins the needle bar 
support 26. The threading mechanism 33 includes a threading rod 34 
provided in parallel with the needle bar 10 on the needle bar support 26. 
The threading rod 34 can rotate about its axis and slide vertically. As 
shown in FIG. 2, the threading rod 34 has a threading hook 36 on its lower 
end. When the threading rod 34 rotates about its axis, the threading hook 
36 is rotated through a known linkage 38 toward an eye 32a in the needle 
32. 
As shown in FIG. 3, an actuating pin 40 is inserted and secured in its 
axial direction through the upper part of the threading rod 34. When the 
threading rod 34 lowers, the actuating pin 40 lowers and contacts the 
projection 24a of the positioning stopper 24. The positioning stopper 24 
is secured through the screw 25 to the predetermined position of the 
needle bar 10 so that when the actuating pin 40 contacts the projection 
24a, the threading hook 36 is lowered to the eye 32a in the needle 32. 
As shown in FIG. 3, an actuating rod 42 is slidably inserted onto the 
threading rod 34, and a compression spring 44 is interposed between the 
actuating pin 40 and the actuating rod 42. As shown in FIG. 2, an S-shaped 
guide slot 46 extends upward in the outer periphery of the actuating rod 
42. One end of the actuating pin 40 engages the guide slot 46. A contact 
surface 48 is formed on the upper end of the actuating rod 42 and projects 
along the radius of the threading rod 34. A hook 49 is formed on the outer 
periphery of the actuating rod 42. A spring 50 extends between the hook 49 
and a hook (not shown) formed as one piece with the needle bar support 26. 
The spring 50 exerts an upward force on the actuating rod 42. 
As shown in FIG. 1, one end of an L-shaped member 51 is rotatably inserted 
onto the upper end of the needle bar support 26. The other end of the 
L-shaped member 51 is rotatably attached through a screw 54 into a 
threading housing 52 secured to a sewing-machine housing (not shown). A 
spring 55 extends between the L-shaped member 51 and the needle bar frame 
14, and exerts an upward force through the needle bar frame 14 to the 
needle bar 10. 
A guide bar 56 is secured onto the threading housing 52 in parallel with 
the threading rod 34. A moving board 58 is slidably attached to the guide 
bar 56, separately from the actuating rod 42. The moving board 58 includes 
a slot 60 extending along the sliding direction of the moving board 58. A 
pin 62 on the guide bar 56 engages the slot 60, thus preventing the moving 
board 58 from rotating. A projection 64 is formed on the upper end of the 
moving board 58. As shown in FIG. 3, a reverse switch 65 is secured to the 
underside of the projection 64, such that, as shown in FIG. 2, when the 
moving board 58 slides down toward the needle 32, a switch body 65a 
contacts the contact surface 48. An operating portion 65b of the reverse 
switch 65 is arranged above an opening 48a in the contact surface 48. When 
the threading rod 34 protrudes from the opening 48a of the contact surface 
48, and an upper end 34a of the threading rod 34 pushes the operating 
portion 65b of the reverse switch 65, the reverse switch 65 turns on. 
As aforementioned, when the actuating rod 42 slides down, the threading rod 
34 rotates, and the threading hook 36 is rotated ready to enter the eye 
32a in the needle 32, the end 34a of the threading rod 34 pushes the 
operating portion 65b and turns on the reverse switch 65. A disconnecting 
pin 66 is provided in parallel with the clutch pin 20 on the lower end of 
the moving board 58. 
A rotating shaft 70 is secured through two screws 68 in parallel with the 
guide bar 56 onto the needle bar support 26. A disconnecting board 72, 
which is supported on the rotating shaft 70, can rotate. A torsion spring 
74 wound around the rotating shaft 70 puts the disconnecting board 72 in 
parallel with the axis of the clutch pin 20 and that of the disconnecting 
pin 66. A ridge 76, which is formed on the disconnecting board 72, slopes 
away from the disconnecting pin 66. When the moving board 58 and the 
disconnecting pin 66 rotate and lower, the disconnecting pin 66 presses 
down the ridge 76 and the disconnecting board 72 is rotated. While the 
needle bar 10 is vertically moving, the disconnecting board 72 can rotate 
and contact the clutch pin 20, thereby pressing up the clutch pin 20. The 
clutch pin 20 disconnects the clutch latch 18 from the groove 12. In the 
embodiment, as shown in FIGS. 1 and 2, the disconnecting board 72 is 
provided with a step 72a so that the disconnecting board 72 rotates but is 
prevented from raising the clutch pin 20 when the needle bar 10 is in its 
uppermost position. 
As shown in FIG. 2, a flat piece 58a extends backward perpendicularly to 
the front surface having the slot 60 of the moving board 58. A rack 78 is 
provided at the side of the flat piece 58a of the moving board 58. The 
teeth of the rack 78 are formed transverse to the sliding direction of the 
moving board 58. The rack 78 meshes with a pinion 80 rotatably supported 
on the threading housing 52. The pinion 80 and a helical gear 82 form one 
member and are rotatably supported on the threading housing 52. A worm 
gear 86 is attached to a rotating shaft of a pulse motor 84 on the 
threading housing 52 and meshes with the helical gear 82. 
On the other hand, as shown in FIG. 2, a stopper 88 is attached on the 
needle bar support 26 extending along the axis of the needle bar 10 such 
that the stopper 88 is a distance S away from the upper end of the needle 
bar 10. A presser bar 166 is supported in parallel with the needle bar 10 
on a frame of the sewing machine such that the presser bar 166 can 
vertically move. The presser bar 166 has a presser foot assembly 170 for 
holding the cloth steady at its lower end. A presser bar guide bracket 174 
is attached via a screw 172 to the presser bar 166. A coil spring 176 is 
wound around the presser bar 166 such that the coil spring 176 forces down 
the presser bar 166 through the presser bar guide bracket 174. 
A lifting lever 178 is provided under the presser bar guide bracket 174 and 
is rotatably supported on the frame of the sewing machine. A presser foot 
raising actuator (not shown) adjoins the lifting lever 178 to raise the 
presser bar 166. A thread tension regulating cam (not shown) is formed on 
the lifting lever 178 and contacts one end of a release lever 186 
rotatably supported via a support stud 184 on the frame of the sewing 
machine. When the lifting lever 178 is operated, the release lever 186 is 
rotated against the force of a spring 188. 
A projection 190 is formed on the release lever 186 to turn on a 
presser-foot detecting switch 192 when the lifting lever 178 is rotated 
clockwise and the presser foot assembly 170 is raised. 
As shown in FIG. 1, the arm shaft 1 for vertically moving the needle 32 is 
provided with an NP1 arm-shaft phase detector 194 and an NP2 arm-shaft 
phase detector 196. The NP1 arm-shaft phase detector 194 includes an NP1 
shutter 198 rotating with the arm shaft 1, an NP1 LED 200 secured to the 
frame of the sewing machine, and an NP1 phototransistor 202. The NP2 
arm-shaft phase detector 196 includes an NP2 shutter 204, an NP2 LED 206, 
and an NP2 phototransistor 208. 
When the arm shaft 1 rotates to raise the needle 32 to its uppermost 
position, the rotation angle of the arm shaft 1 is 0.degree.. While the 
arm shaft 1 further rotates about 15.degree., the NP1 arm-shaft phase 
detector 194 sends an NP1 signal. On the other hand, after the needle 32 
reaches its uppermost position, the arm shaft 1 further rotates 
45.degree.. While the arm shaft 1 further rotates about 15.degree. and the 
rotation angle of the arm shaft 1 is from 45.degree. to 60.degree., the 
NP2 arm-shaft phase detector 196 sends an NP2 signal. 
An electric structure for the embodiment will now be explained referring to 
the block diagram in FIG. 4. The sewing machine for the embodiment is 
controlled by an electronic controller 300. The electronic controller 300 
is connected to a start-stop switch 302 for instructing the starting and 
finishing of sewing operation, and a threading switch 304 for instructing 
threading operation. The electronic controller 300 is also connected to 
the NP1 arm-shaft phase detector 194 and the NP2 arm-shaft phase detector 
196 for sending NP1 and NP2 signals, respectively, corresponding to the 
position of the needle bar 10 rising and lowering according to the 
rotation of the arm shaft 1, the presser-foot detecting switch 192, and 
the reverse switch 65. The electronic controller 300 sends control signals 
to a pulse-motor driver 312, a sewing-machine motor driver 316, and a 
presser-foot driver 322. The pulse-motor driver 312 sends pulses to the 
pulse motor 84. The sewing-machine motor driver 316 supplies power to a 
sewing-machine motor 314 for rotating the arm shaft 1. The presser-foot 
driver 322 sends control signals to a presser-foot rising actuator 320 for 
raising the presser foot assembly 170. 
A threading routine will now be described referring to the flowchart of 
FIGS. 5A and 5B. After a power switch (not shown) on the sewing machine is 
turned on, step S400 initializes the pulse motor 84. An operator presses 
the threading switch 304 so that the eye 32a in the needle 32 is threaded 
prior to sewing operation. Step S410 determines whether the threading 
switch 304 is turned on. If at step S410 the threading switch 304 is on, 
step S420 resets a counter K for counting the rotation amount of the pulse 
motor 84, and step S430 determines whether the start-stop switch 302 is 
turned off. If at step S430 the start-stop switch 302 is on and the 
sewing-machine motor 314 is rotating, step S440 turns off the start-stop 
switch 302, thereby stopping the sewing-machine motor 314. While the 
process is waiting for step S410 where the threading switch 304 is turned 
on again, the operator passes the thread guided via a thread take-up (not 
shown) or the thread guide 28a of the needle bar 10 onto a given place of 
the linkage 38. 
If at step S410 the threading switch 304 is on and at step S430 the 
start-stop switch 302 is off, step S450 determines whether the 
presser-foot detecting switch 192 is turned on and the presser foot 
assembly 170 is raised. If at step S450 the presser foot assembly 170 is 
not raised, step S460 raises the presser foot assembly 170 by sending 
signals to the presser-foot driver 322 for driving the presser-foot rising 
actuator 320. Subsequently, steps S410 through S450 are repeated. 
After the process at steps S400 through S460 is executed, the 
sewing-machine motor 314 is stopped and the presser foot assembly 170 is 
raised. Subsequently, step S470 rotates forward the pulse motor 84 by a 
given number N of pulses PL. Step S480 adds the number N to the counter K. 
Consequently, the threading mechanism 33 is operated as follows. 
When the pulse motor 84 rotates, such rotation is transmitted to the worm 
gear 86, the helical gear 82, and the pinion 80, and the rack 78, thereby 
lowering the moving board 58 along the guide bar 56. 
When the moving board 58 lowers, the switch body 65a of the reverse switch 
65 secured to the projection 64 of the moving board 58 contacts the 
contact surface 48 of the actuating rod 42. The actuating rod 42 is thus 
lowered against the force of the spring 50. When the actuating rod 42 
lowers, the compression spring 44 and the actuating pin 40 engaging the 
guide slot 46 also lower, thereby lowering the threading rod 34. The 
linkage 38 and the threading hook 36 are also lowered. 
In the embodiment, when the pulse motor 84 rotates forward by the given 
pulses PL and the moving board 58 lowers a given distance L, as shown in 
FIG. 6, the disconnecting pin 66 presses in the ridge 76 of the 
disconnecting board 72 and the disconnecting board 72 is rotated 
outwardly. The clutch pin 20 of the click 18 is rotated forcibly outwardly 
about a vertical axis, thus disconnecting the clutch latch 18 from the 
groove 12. Subsequently, the needle bar 10 is pulled up by the force of 
the spring 55 until the upper end of the needle bar 10 contacts the 
stopper 88. In the embodiment, after the clutch latch 18 disengages from 
the groove 12, the needle bar 10 is raised to a position higher by the 
distance S than its uppermost position to which the rotation of the arm 
shaft 1 brings the needle bar 10. Even when the arm shaft 1 rotates to 
return the needle bar connecting stud 8 to its uppermost position, the 
clutch latch 18 fails to engage in the groove 12 of the needle bar 
connecting stud 8. Even when the arm shaft 1 vertically moves the needle 
bar connecting stud 8 by rotating, the needle bar 10 is not lowered or 
raised. When the arm shaft 1 rotates, the thread guide 28a holding thread 
guided from the linkage 38 fails to lower or rise. If the distance S 
between the stopper and the upper end of the needle bar 10 is zero, every 
time the arm shaft 1 raises the needle bar 10 for sewing operation, the 
needle bar 10 contacts the stopper 88, thereby causing noise. To avoid 
noise, the distance S should be larger than zero. 
As aforementioned, when the pulse motor 84 rotates forward by the given 
pulses PL, the needle bar 10 is disengaged from the click 18 and the 
needle bar 10 rises to the stopper 88. Subsequently, step S490 rotates the 
sewing-machine motor 314 by sending the control signal to the 
sewing-machine motor driver 316. Step S500 determines whether the NP1 
arm-shaft phase detector 194 sends the NP1 signal to the electronic 
controller 300. If at step S500 NP1 signal is issued, step S510 stops the 
sewing-machine motor 314. The arm shaft 1 is set in the position 
corresponding to the uppermost position of the needle bar 10. The arm 
shaft 1 is ready for connecting the needle bar 10. 
After the arm shaft 1 is thus positioned, step S520 rotates forward the 
pulse motor 84 by sending the control signal to the pulse-motor driver 
312. Step S530 determines whether the reverse switch 65 turns on. 
When the pulse motor 84 rotates forward, the threading rod 34 and the 
actuating pin 40 lower, and the end of the actuating pin 40 contacts the 
projection 24a of the positioning stopper 24. On the other hand, the 
clutch latch 18 is disengaged from the groove 12 by the disconnecting 
board 72, and the needle bar 10 is pulled only by the force of the spring 
55. By contacting the projection 24a, the actuating pin 40 lowers the 
needle bar 10. When the needle bar 10 lowers the distance S from the 
stopper 88, the click 18 engages in the groove 12 of the needle bar 
connecting stud 8 stopped in its uppermost position. Since the arm shaft 1 
is stopped, no rotation of the arm shaft 1 is transmitted to the 
connecting rod 6 or the needle bar connecting stud 8. The needle bar 10 is 
thus stopped in its uppermost position, and the threading rod 34 is 
prevented from lowering further. When the moving board 58 is further 
lowered by the pulse motor 84, the actuating rod 42 lowers against the 
force of the compression spring 44. The actuating pin 40 slides in the 
guide slot 46, thereby rotating the threading rod 34. When the threading 
rod 34 rotates, the linkage 38 applies tension to thread in front of the 
eye 32a in the needle 32. The threading hook 36 is rotated by the linkage 
38 toward the eye 32a. When the threading hook 36 is ready to penetrate 
the eye 32a in the needle 32, the reverse switch 65 turns on. 
If at step S530 the reverse switch 65 turns on, step S540 starts a timer T, 
while continuing rotating forward the pulse motor 84. Step 550 determines 
whether time period set on the timer T has elapsed. If at step S550 the 
time period has elapsed, step S560 reverses the pulse motor 84 until the 
counter K counts down to zero. 
Consequently, after the threading hook 36 is ready for going through the 
eye 32a in the needle 32, the threading hook 36 rotates during the time 
period set on the timer T. Subsequently, the pulse motor 84 is reversed by 
the number N of pulses required for rotating forward the pulse motor 84. 
The threading hook 36 thus enters the eye 32a and catches thread. 
Subsequently, the pulse motor 84 reverses, and the moving board 58 rises. 
The actuating rod 42 also rises using the tensile force of the spring 50. 
The guide slot 46 also rises, and the actuating pin 40 slides in the guide 
slot 46 and rotates the threading rod 34 in reverse. The threading hook 36 
is rotated by the linkage 38, and draws back with thread caught thereon 
from the eye 32a in the needle 32, thereby threading the eye 32a. 
By threading the eye 32a and returning the threading rod 34 to its 
uppermost position, the threading process ends. 
In the sewing machine for the embodiment, after the threading switch 304 is 
operated, the sewing-machine motor 314 is stopped. After thread is passed 
onto the linkage 38, the needle bar 10 is disconnected from the arm shaft 
1. The needle bar 10 is raised to the stopper 88 regardless of the 
rotation of the arm shaft 1. Subsequently, thread from the linkage 38 is 
passed through the eye 32a in the needle 32 by the threading mechanism 33. 
After thread guided via the thread guide 28a attached to the lower end of 
the needle bar 10 is passed onto the linkage 38 prior to threading 
operation, the thread guide 28a stays in its uppermost position or rises 
irrespective of the rotation of the arm shaft 1. The thread guide 28a is 
thus prevented from lowering, drawing thread from the bobbin and loosening 
thread stretched from the linkage 38. Proper tension is applied to thread 
stretched in front of the eye 32a. The threading mechanism 33 securely 
threads the eye 32a in the needle 32. 
This invention has been described above with reference to the preferred 
embodiment. Modifications and alterations may become apparent to one 
skilled in the art upon reading and understanding the specification. It is 
intended to include all such modifications and alterations within the 
scope of the appended claims. 
For example, in a sewing machine without a device for disconnecting the arm 
shaft from the needle bar 10, as shown in FIG. 7, the arm shaft 1 can be 
provided with an arm-shaft phase detector 600 that detects whether the 
needle bar 10 is lowering. If the arm shaft 1 is in phase where the needle 
bar 10 will lower, the threading switch 304 is operated, and the 
sewing-machine motor 314 is rotated in reverse to position the needle bar 
10 in its uppermost position. If the arm shaft 1 is in phase where the 
needle bar 10 will rise, the sewing-machine motor 314 is rotated forward 
to position the needle bar 10 in its uppermost position. 
In the embodiment, thread is stretched out from the linkage 38 to the front 
of the eye 32a in the needle 32. Thread can manually be stretched out in 
front of the eye 32a. If the end of thread is held in the operator's hand 
near the needle 32, the needle 32 never lowers during threading operation, 
thus giving no fear to the operator.