Sewing apparatus with needle bar position changing control

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a sewing apparatus with a cassette mount to which a thread cassette is detachably attached, and more particularly to a technique for performing different needle bar position changing control manners depending upon whether or not the thread cassette has been attached to the cassette mount when a needle bar position changing means has been operated.

2. Description of the Related Art

There has conventionally been proposed a sewing apparatus which includes a cassette mount to which a thread cassette accommodating a thread spool is detachably attached and in which a thread drawn from the thread cassette serves as a needle thread. In the sewing apparatus, the thread drawn from the thread cassette attached to the cassette mount is caught between a pair of thread tension discs of a thread tensioning mechanism. The thread extending downstream from the thread tension discs is caught on a needle thread take-up lever, and the thread extending downstream from the lever is passed through an eye of a sewing needle mounted on a needle bar.

It is desirable that the above-described sewing apparatus be provided with a threading mechanism for passing a thread drawn from the thread cassette attached to the cassette mount through an eye of a sewing needle. Furthermore, in order that the thread may be passed through the needle eye, the threading mechanism needs to be operated while a needle bar vertically moved by a needle bar vertically moving mechanism is stopped at an upper stop position.

On the other hand, the assignee of this application filed a Japanese patent application assigned with Application No. 2002-91558 and relating to a sewing apparatus including a thread carrying mechanism and a threading mechanism each operated in synchronization with attachment of the thread cassette to the cassette mount. The thread drawn from the thread cassette is automatically passed through the needle eye by the thread carrying mechanism and threading mechanism. In the disclosed sewing apparatus, the thread drawn from the thread cassette is caught and carried near the needle eye by the thread carrying mechanism, and the carried thread is caught by the threading mechanism to be passed through the needle eye.

In the above-described sewing apparatus, the threading mechanism is operated in synchronization with the operation of attaching the thread cassette to the cassette mount. Accordingly, in order that passing the thread through the needle eye may be realized by the threading mechanism, the thread cassette needs to be attached to the cassette mount while the needle bar is stopped at an upper stop position.

Cloth to be sewn is set to the sewing apparatus while the needle bar is stopped at the upper stop position. While the needle bar is stopped at a lower stop position, the thread is stuck into the set cloth so that a positional relationship is maintained between the cloth and needle. The cloth can be turned about the needle in order that a sewing direction may be changed. In conventional sewing apparatus, a needle up-down key is provided which is operated to change the position of the needle bar between the upper and lower stop positions alternately. Furthermore, there are some conventional sewing machines in which the threading mechanism is not operated when the needle bar has a height lower than a predetermined one.

When a conventional sewing machine with the cassette mount to which the thread cassette is detachably attached includes a threading mechanism, a user has a difficulty in moving the needle bar to the upper stop position to stop it there by operating a spindle pulley or the like while viewing the needle bar. Threading sometimes fails when the threading mechanism is operated although the needle bar is stopped at any position other than the upper stop position. The threading mechanism or the like would be damaged depending in certain conditions. A trial-and-error operation would be required at many times until the needle bar reaches a suitable height. As a result, the working efficiency would be reduced.

In the sewing apparatus disclosed in aforesaid Japanese patent application No. 2002-91558, the thread cassette needs to be attached to the cassette mount while the needle bar is stopped at the upper stop position. The above-described problems also apply to the disclosed sewing apparatus. When threading has failed, the thread cassette would need to be re-attached to the cassette mount, and the preparation for threading needs to be re-executed, thereby resulting in troubles.

Furthermore, the aforesaid needle up-down key may be applied to the sewing apparatus with the cassette mount to which the thread cassette is attached. However, the needle bar is changed between the upper and lower stop positions alternately every time the needle up-down key is operated. Accordingly, even when the needle up-down key is operated before threading so that the needle bar is located at the lower stop position, the threading mechanism would sometimes be operated (or the thread cassette would be attached to the cassette mount in the sewing apparatus disclosed in Japanese patent application No. 2002-91558).

The location of the needle bar needs to be confirmed in order that the user may operate the needle up-down key to stop the needle bar at the upper stop position. Furthermore, in certain cases, the needle up-down key needs to be operated twice to stop the needle bar at the upper stop position. Thus, load applied to the user is increased and accordingly, the position change is troublesome. In order that the sewing apparatus may be improved in the convenience thereof, it is desirable that the needle up-down key be operated to change the needle bar between the upper and lower stop positions alternately.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a sewing apparatus in which when a needle bar position changing means is operated, the needle bar is changed to the upper or lower stop position according to the position at the time of operation of the needle bar position changing means in the case where the thread cassette is attached to the cassette mount, and the needle bar is changed only to the upper stop position when the thread cassette is unattached to the cassette mount, whereupon the thread cassette can desirably be attached to the cassette mount.

The present invention provides a sewing apparatus comprising, a needle bar, a needle bar vertically moving mechanism vertically moving the needle bar, a needle bar position changing operation unit operated via the needle bar vertically moving mechanism to change a vertical position of the needle bar, a thread cassette having a thread accommodating section accommodating a supply of thread, a cassette mount to which the thread cassette is detachably attached, a cassette detector detecting the thread cassette attached to the cassette mount, and a needle bar position changing control unit. The needle bar position changing control unit controls the needle bar vertically moving mechanism so that in a case where the needle bar position changing unit has been operated, the needle bar is changed from an upper stop position to a lower stop position or from the lower stop position to the upper stop position according to a position of the needle bar at the time of operation of the needle bar position changing unit when the thread cassette is attached to the cassette mount according to a result of detection by the cassette detector. The needle bar position changing control unit further controls the needle bar vertically moving mechanism so that the needle bar is changed to the upper stop position irrespective of the position of the needle bar at the time of operation of the needle bar position changing unit when the thread cassette is unattached to the cassette mount according to the result of detection by the cassette detector.

When the presence or absence of the thread cassette attached to the cassette mount has been detected by the cassette detector and the needle bar position changing operation unit has been operated, the needle bar position changing control unit controls the needle bar vertically moving mechanism on the basis of the result of detection by the cassette detector. In the control, when the thread cassette is attached to the cassette mount, the needle bar is changed from the upper stop position to the lower stop position or from the lower stop position to the upper stop position according to the position of the needle bar at the time of operation of the needle bar position changing unit. When the thread cassette is unattached to the cassette mount, the needle bar is changed to the upper stop position irrespective of the position of the needle bar at the time of operation of the needle bar position changing unit.

A space for set and removal of cloth to and from the sewing apparatus is defined below the needle bar when the needle bar is at the upper stop position. When the needle bar is at the lower stop position, the needle is stuck into cloth set to the sewing apparatus so that a positional relationship is maintained between the cloth and needle. In a case where the thread cassette has been attached to the cassette mount, the needle bar is changed between the upper and lower stop positions alternately every time the user operates the needle bar position changing operation unit once. On the other hand, when the thread cassette has not been attached to the cassette mount, the needle bar need not be changed to the lower stop position. Accordingly, the needle bar is changed to the upper stop position irrespective of the position of the needle bar when the user operates the needle bar position changing operation unit once.

The needle bar position changing control unit preferably controls the needle bar vertically moving mechanism so that when the thread cassette is unattached to the cassette mount according to the result of detection by the cassette detector and the needle bar is at the upper stop position, the needle bar is changed to the lower stop position once and subsequently to the upper stop position.

The sewing apparatus preferably further comprises a threading mechanism passing the thread drawn from the thread cassette through an eye of a needle attached to the needle bar when the thread cassette is attached to the cassette mount. In this case, the upper stop position is determined so that the threading mechanism is operable to pass the thread drawn from the thread cassette through the needle eye.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become clear upon reviewing the following description of embodiment, made with reference to the accompanying drawings, in which;

FIG. 1

is a front view of a sewing machine in accordance with one embodiment of the present invention during attachment of a thread cassette to a cassette mount;

FIG. 2

is a front view of the sewing machine with the sewing head being eliminated;

FIG. 3

is a front view of the sewing machine with the thread cassette having been attached;

FIG. 4

is a front view of the sewing machine with the sewing head being eliminated;

FIG. 5

is a front view of the thread cassette;

FIG. 6

is a rear view of the thread cassette;

FIG. 7

is a left-hand side view of the thread cassette with the lid open;

FIG. 8

is a bottom view of the thread cassette;

FIG. 9

is a front view of the front interior of the head;

FIG. 10

is a front view of the front interior of the head in another condition;

FIG. 11

is a plan view of thread tension discs of a thread tensioning mechanism;

FIG. 12

is a left-hand side view of a thread carrying mechanism;

FIGS. 13A and 13B

are a left-hand side view and a front view of a threading mechanism, respectively;

FIGS. 14A and 14B

illustrate the threading mechanism when a threading hook extends through the needle eye and when the thread is passed through the needle eye with the threading hook having been returned through the needle eye, respectively;

FIG. 15

is a block diagram showing an electrical arrangement of the control system of the sewing machine;

FIG. 16

is a schematic diagram of a program stored in ROM of a control device;

FIG. 17

is a first half of flowchart including a needle bar position changing control;

FIG. 18

is a second half of the flowchart including the needle bar position changing control;

FIG. 19

shows positions of the needle bar changed according to the needle bar position and presence or absence of the thread cassette;

FIG. 20

is a flowchart including the needle bar position changing control in a modified form of the sewing machine; and

FIG. 21

is a flowchart including the needle bar position changing control in another modified form of the sewing machine.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present invention will be described with reference to the accompanying drawings. The invention is applied to a household sewing machine provided with a cassette mount to which a thread cassette having a thread accommodating section for accommodating a supply of thread is detachably attached.

Referring to

FIGS. 1

to

4

, a household sewing machine M includes a sewing bed

1

having a horizontal bed plane, a pillar

2

standing from a right end of the bed

1

, a sewing arm

3

extending left ward from an upper end of the pillar

2

so as to be opposed along the bed

1

, and a machine head

4

located at a left end of the arm

3

. The head

4

is provided with a cassette mount

5

to which a thread cassette

10

is detachably attached. A thread

11

drawn from the thread cassette

10

attached to the cassette mount

5

serves as a needle thread. The arm

3

or the head

4

thereof includes operation switches

6

(see

FIG. 15

) such as a sewing start switch, sewing finish switch, etc. The arm

3

further includes a liquid crystal display

7

and a touch panel

8

provided on the surface of the liquid crystal display.

Referring to

FIGS. 2

,

4

,

9

and

10

, in the head

4

are provided a needle bar

12

, a needle thread take-up lever

13

, a thread tensioning mechanism

14

adjusting a thread tension of the needle thread drawn from the thread cassette

10

attached to the cassette mount

5

. In the head

4

are further provided a cassette detaching mechanism

15

including a detaching operation member

15

a

operated for detachment of the thread cassette

10

attached to the cassette mount

5

. The head

4

further includes a thread carrying mechanism

16

A, a threading mechanism

16

B and a needle bar threading mechanism

17

all of which are operated in synchronization with attachment of the thread cassette

10

to the cassette mount

5

. The head

4

still further includes a needle bar vertically moving mechanism

18

for vertically moving the needle bar

12

, a needle bar rocking mechanism

19

for rocking the needle bar

12

, and a needle thread take-up lever driving mechanism.

The thread carrying mechanism

16

A catches the thread

11

drawn from the thread cassette

10

and carries the caught thread

11

near an eye

12

b

of a sewing needle

12

a

. The threading mechanism

16

B passes the thread

11

carried by the thread carrying mechanism

16

A through the needle eye

12

b

. The needle bar threading mechanism

17

causes the thread

11

to be caught on a thread guide H (see

FIG. 12

) of the needle bar

12

.

Referring to

FIGS. 3 and 4

, the thread

11

drawn from the thread cassette

10

attached to the cassette mount

5

is placed on a thread tension shaft

40

(see

FIG. 11

) disposed between a pair of thread tension discs

41

and

42

of the thread tensioning mechanism

14

in attachment of the thread cassette

10

to the cassette mount

5

. The thread

11

extending downstream from the thread tension shaft

40

is caught on the needle thread take-up lever

13

. The thread

11

extending downstream from the needle thread take-up lever

13

is passed through the needle eye

12

b

(see FIG.

14

), whereupon the thread

11

is set in the sewing machine M so that a sewing operation can be carried out.

The bed

1

is provided with a bobbin mount (not shown) to which a bobbin (not shown) is detachably attached. A thread drawn from the bobbin serves as a bobbin thread. The bed

1

is further provided with a shuttle mechanism (not shown). When the needle and bobbin threads are set for the sewing operation and a sewing machine motor

9

(see

FIG. 15

) is driven, the needle bar

12

is vertically moved by the needle bar vertically moving mechanism

18

. The shuttle mechanism is driven in synchronization with the vertical movement of the needle bar

12

so that the needle thread

11

near the needle

12

a

lowered below a needle plate

1

a

of the bed

1

, whereupon the needle and bobbin threads are entangled to be formed into stitches.

The thread cassette

10

will now be described. Referring to

FIGS. 5

to

8

, the thread cassette

10

comprises a cassette body

20

and a lid

21

pivotally mounted on the body

20

. The cassette body

20

with the lid

21

defines therein a thread accommodating cavity

23

for accommodating a thread spool

22

serving as a supply of thread. A spool pin

24

is mounted on the lid

21

. When the lid

21

is opened forward as shown in

FIG. 7

, the thread spool

22

is allowed to be attached to and detached from the spool pin

24

. When the lid

21

is closed with the thread spool

22

attached to the spool pin

24

, the thread spool is enclosed in the thread accommodating cavity

23

.

The thread

11

extends upward from the thread spool

22

to be drawn out of the thread accommodating cavity

23

. The thread

11

further extends through a thread path

35

defined between the cassette body

20

and a left-hand end of the lid

21

. The thread

11

is then put on a first thread guard

26

a

at a left lower end of the thread cassette

10

, further extending rightward thereafter to be put on a second thread guard

26

b

at a lower end of a partition wall

27

and a third thread guard

26

c

at a right lower end of the thread cassette

10

. The thread

11

further extends forward to be put on a fourth thread guard

26

d

and is then returned to extend leftward. The thread

11

is then retained on a thread retainer

28

. Furthermore, the thread

11

extending leftward is cut by a left blade

29

of the thread retainer

28

and the resultant end is put on a fifth thread guard

26

e

near the blade

29

.

The thread cassette

10

is thus prepared for attachment to the cassette mount

5

as described above. A needle thread take-up lever guide space

30

defined at a right end of the thread cassette

10

extends substantially over the length of the cassette. The guide space

40

is open at the rear and the lower portion of the cassette. A thread tensioning space

31

is defined at a central lower end of the thread cassette

10

and open at a lower portion thereof. These spaces

30

and

31

are partitioned by a partition wall

27

.

The thread cassette

10

is descended to be inserted into the cassette mount

5

. In this case, the needle thread take-up lever

13

and a needle thread take-up lever guide

13

a

(see

FIG. 2

etc.) guiding the lever enter the guide space

30

from below the cassette, whereas a thread tensioning shaft

40

(see

FIG. 11

) of the thread tensioning mechanism

14

and a pair of thread tension discs

41

and

42

enter the thread tensioning space

31

from below the cassette. A notch

20

a

is formed in the lower end of the rear wall of the cassette body

20

to prevent the thread tensioning shaft

40

from interference with the thread cassette

10

. When the thread cassette

10

has been inserted slightly into the cassette mount

5

, a thread part

11

a

between the thread guards

26

a

and

26

c

is caught by the needle thread take-up lever

13

in the guide space

30

.

Subsequently, when the thread cassette

10

is further inserted into the cassette mount

5

, the thread guards

26

a

and

26

b

are descended relative to the needle thread take-up lever

13

on which a thread part

11

a

is caught. However, the thread downstream the thread part

11

a

is continuously held by the thread holding portion

28

. Accordingly, the thread

11

is drawn from the thread spool

22

in the thread accommodating cavity

23

. For example, the thread part

11

a

has a generally triangular shape when two thirds of the thread cassette are inserted into the cassette mount

5

, as shown in

FIGS. 1 and 2

. When the thread cassette

10

is completely attached to the cassette mount

5

, the thread part

11

b

between the thread guards

26

a

and

26

b

is caught on the thread tensioning shaft

40

between the paired thread tension discs

41

and

42

in the thread tensioning space

31

.

The thread tensioning mechanism

14

will now be described. Referring to

FIG. 11

, the thread tensioning mechanism

14

includes the thread tensioning shaft

40

fixed to a frame (not shown) and extending rearward, the front thread tension disc

41

fixedly fitted with the shaft

40

, the rear thread tension disc

42

fixedly fitted with the shaft

40

so as to be brought into a face-to-face contact with the front thread tension disc, and a thread tensioning spring

42

a

comprising a compression coil spring fitted with the shaft

40

so as to urge the rear disc

42

against the front disc

41

. A drive mechanism

43

(see

FIG. 10

) is provided for opening and closing the thread tension discs

41

and

42

and includes a pulse motor

44

(see FIG.

15

).

The drive mechanism

43

includes a plurality of gear members and link members as well as the pulse motor

44

and opens the thread tension discs

41

and

42

at least when the thread cassette

10

is attached to the cassette mount

5

. The drive mechanism

43

opens the thread tension discs

41

and

42

when the thread cassette

10

is detached from the cassette mount

5

. The pulse motor

44

also serves to drive the needle bar rocking mechanism

19

.

The thread carrying mechanism

16

A will be described. Referring to

FIGS. 9 and 12

, the thread carrying mechanism

16

A is provided on the frame on which a needle bar base

60

(see

FIG. 13

) is pivotally mounted and includes a threading member

50

catching the thread

11

drawn from the thread cassette

10

and a threading drive mechanism section

55

lowering the threading member

50

from a standby position (see

FIG. 9

) while the attitude of the threading member is being changed, whereby the threading member is transferred from a threading position (not shown) toward the thread carrying position (see FIG.

14

).

The threading member

50

has a pair of threading plates

51

. When the threading member

50

is at the threading position, a part of the thread

11

located downstream the needle thread take-up lever

13

is caught over the paired threading plates

51

in a tight state. Furthermore, when located at the thread carrying position, the threading member

50

is positioned relative to the position of the needle bar

12

with respect to the vertical position thereof, and the needle thread

12

a

is located between the threading plates

51

, whereupon the thread

11

is close to the needle eye

12

b.

The threading mechanism

16

B will be described. Referring to

FIGS. 13 and 14

, the threading mechanism

16

B is mounted on the needle bar base

60

and includes a threading shaft

61

and slider guide shaft

62

supported on the needle bar base

60

on the left of the needle bar

12

so as to be vertically moved, a threading slider

63

fitted with upper portions of these shafts

61

and

62

so as to be vertically moved, and a hook mechanism section

64

mounted on a lower end of the threading shaft

61

. The needle bar

12

is supported on the needle bar base

60

so as to be vertically moved. The needle bar base

60

has an upper end pivotally mounted on a frame. The needle bar

12

and the threading mechanism

16

B are rocked together.

The threading shaft

61

has two pins

65

a

and

65

b

protruding from an upper portion thereof. The upper pin

65

a

is in engagement with a spiral engagement groove

63

a

formed in the threading slider

63

, whereas the lower pin

65

b

is engageable, from above, with the engaging member

12

c

fitted with the needle bar

12

. A compression coil spring

66

is provided around the threading shaft

61

to urge the slider

63

upward relative to the threading shaft, whereby the pin

65

a

usually engages a lower end of the engagement groove

63

a

. Furthermore, another compression coil spring

67

is provided around the slider guide shaft

62

to urge the threading slider

63

upward, whereby the threading shaft

61

and the threading slider

63

are usually located at respective upper limit positions. The hook mechanism section

64

includes a threading hook

68

capable of passing through the needle eye

12

b

and having a distal end formed with a threading portion

68

a

, two guide members

69

located at both sides of the threading hook

68

respectively, and a wire

69

a

engageable with the threading portion

68

a

of the threading hook

68

.

The threading mechanism

16

B is in the state as shown in

FIG. 13

when the thread cassette

10

is unattached to the cassette mount

5

. When the thread cassette

10

is inserted into the cassette mount

5

, the threading slider

63

is descended. The threading shaft

61

is also descended with the threading slider

63

at an initial stage. The threading shaft

61

is disallowed to be moved downward thereby to be stopped when the pin

65

b

thereof engages the engagement member

12

c

of the needle bar

12

from above, whereupon the threading shaft is positioned in the vertical direction relative to the needle bar.

Subsequently, the threading slider

63

is descended relative to the threading shaft

61

. Accordingly, the pin

65

a

engages the spiral engagement groove

63

a

of the threading slider

63

thereby to be moved upward, whereupon the threading shaft

61

is turned. At this time, the hook mechanism section

64

is located near the needle

12

a

, and moreover, the thread

11

drawn from the thread cassette

10

by the thread carrying mechanism

16

A is carried near the needle

12

a

, held in front of the needle

12

a

in a stretched state. More specifically, when the threading shaft

61

is turned, the threading hook

68

of the hook mechanism

64

passes through the needle eye

12

b

as shown in

FIG. 14A

, so that the thread

11

is caught by the distal threading portion

68

a

of the threading hook

61

as shown in FIG.

14

B. When the threading shaft

61

is then turned in the opposite direction, the threading hook

68

is returned through the needle eye

12

b

such that the thread

11

is passed through the needle eye

12

b

. At this time, the thread

11

is also placed on the needle bar thread guide H by the threading mechanism

17

.

The sewing machine M is constructed so that the thread

11

can reliably be passed through the needle eye

12

b

when the thread carrying mechanism

16

A and threading mechanism

16

B are operated while the needle bar

12

is stopped at a predetermined upper stop position. More specifically, the needle bar

12

is stopped at the upper stop position with the thread cassette

10

detached from the cassette mount

5

in order that the thread

11

may reliably be passed through the needle eye

12

b

. In this state, the thread cassette

10

needs to be attached to the cassette mount

5

and the thread carrying mechanism

16

A and threading mechanism

16

B needs to be operated.

The needle bar vertically moving mechanism

18

transmits torque of the spindle

9

a

(see

FIG. 10

) rotated by the sewing machine motor

9

via a crank mechanism section

18

a

(see

FIG. 10

) etc., thereby vertically moving the needle bar

12

. The needle bar

12

is reciprocated vertically during one turn of the spindle

9

a.

Referring now to

FIGS. 1 and 3

, a needle up-down key or NP key

77

is provided on the front of the head

4

. The needle up-down key

77

serves as a needle bar position changing control unit operated so that the vertical position of the needle bar

12

is changed via the needle bar vertically moving mechanism

18

. When the needle up-down key

77

is operated during stop of the needle bar

12

, the switching operation is effected, so that the needle bar vertically moving mechanism

18

is driven according to the presence or absence of the thread cassette

10

attached to the cassette mount

5

and the position of the needle bar at the time of operation of the needle up-down key

7

, whereupon the needle bar

5

is changed to a predetermined upper or lower stop position.

For the purpose of the above-described change in the needle bar position, the sewing machine M includes a spindle angle sensor

71

(see

FIG. 15

) for detecting an angle of the spindle

9

a

rotated by the sewing machine motor

9

and cassette detecting switch

72

(see

FIG. 15

) for detecting the presence or absence of the thread cassette attached to the thread cassette

5

.

The spindle angle sensor

71

comprises an encoder having an encoder disc fixed to the spindle

9

a

and a photo-interrupter sandwiching the encoder disc, for example. The cassette detecting switch

72

comprises a limit switch, for example and is mounted to a portion of the head near the lower end of the cassette mount

5

. The cassette detecting switch

72

is turned on when the thread cassette

10

is attached to the cassette mount

5

. The cassette detecting switch

72

is turned off when the thread cassette

10

is pulled so as to be ascended from the cassette mount

5

a predetermined distance.

A thread winding mechanism (not shown) is provided in the right portion of the arm

3

. The thread winding mechanism has a bobbin thread winding shaft which is switched between a standby position and a bobbin thread winding position. When the motor

9

is driven while the bobbin thread winding shaft is at the bobbin thread winding position, a driving force of the motor is transmitted to the thread winding mechanism to rotate the thread winding shaft but not to the needle bar vertically moving mechanism

18

.

A bobbin mounted on the thread winding shaft is rotated with the bobbin thread winding shaft so that a thread is drawn from a supply of thread attached to a predetermined mount to be wound as a bobbin thread. For example, the thread supply may be the thread spool

13

accommodated in the thread cassette

10

. A bobbin thread winding switch detecting switch

73

(see

FIG. 15

) is provided for detecting a position of the bobbin thread winding shaft (a standby position or bobbin thread winding position).

The control system of the sewing machine M will be described. Referring to

FIG. 15

, the sewing machine M includes a control device

70

having CPU

70

a

, ROM

70

b

, RAM

70

c

, an input interface

70

d

and an output interface

70

e

. To the input interface

70

d

are electrically connected operating switches

6

, the touch-panel

8

, spindle angle sensor

71

, cassette detecting switch

72

, the bobbin thread winding switch detecting switch

73

and needle up-down key

77

. To the output interface

70

e

are electrically connected drive circuits

75

a

to

75

d

driving the sewing machine motor

9

, pulse motor

44

, liquid crystal display

7

and lamps

74

respectively.

ROM

70

b

stores a control program for the sewing machine M as shown in FIG.

16

. The control program includes a sewing control program for the sewing operation, a cassette attachment and detachment control program for attaching and detaching the thread cassette

10

to and from the cassette mount

5

, and a needle bar position change control program for changing a vertical position of the needle bar.

In the needle bar position changing control, the control device

70

controls the needle bar vertically moving mechanism

18

in the following manner. In the case where the needle up-down key

77

has been operated, the needle bar

12

is changed from an upper stop position to a lower stop position or from the lower stop position to the upper stop position according to a position of the needle bar at the time of operation of the needle up-down key

77

when the thread cassette

10

is attached to the cassette mount

5

according to a result of detection by the cassette detector. Furthermore, when the thread cassette

10

is unattached to the cassette mount

5

, the needle bar

12

is changed to the upper stop position irrespective of the position of the needle bar at the time of operation of the needle up-down key

77

. Particularly when the thread cassette

10

is unattached to the cassette mount

5

, the needle bar is changed to the lower stop position once and subsequently to the upper stop position in the case where the needle bar

12

is at the upper stop position. This control manner means that the needle bar

12

is transferred via the lower stop position to the upper stop position. In this case, the movement direction of the needle bar

12

is reversed at the lower stop position. However, this does never mean that the needle bar

12

is stopped at the lower stop position for a predetermined period of time.

The following is the description of control carried out by the control device

70

on the basis of the needle bar position changing control program. Referring to

FIG. 17

, the control starts with interrupt at intervals of 1 msec. When the bobbin thread winding shaft is not at the bobbin thread winding position (NO at step S

1

; sewable condition), the control device

70

advances to step S

2

. When the motor

9

is inoperative (YES at step S

2

), the control device

70

advances to step S

3

. When the needle up-down key

77

is operated to be turned on (YES at step S

3

), the control device

70

advances to step S

4

. Furthermore, the control device

70

advances to step S

9

when the bobbin thread winding shaft is at the bobbin thread winding position (YES at step S

1

), when the motor

9

is not inoperative (NO at step S

2

), or when the needle up-down key

77

is not operated (NO at step S

3

).

When a sewing machine motor start processing is carried out at step S

4

, the needle bar vertically moving mechanism

18

is driven by the motor

9

so that the needle bar

12

is vertically moved. At this time, the control device

70

determines the presence or absence of the thread cassette

10

attached to the cassette mount

5

, based on the result of detection by the cassette detecting switch

72

(step S

5

). When the thread cassette

10

has been attached to the cassette mount

5

(YES at step S

5

) and the spindle angle is an upper stop position angle (YES at step S

6

), the control device

70

sets a lower stop position command flag (step S

7

) and subsequently advances to step S

9

.

The spindle angle is calculated on the basis of information from the spindle angle sensor

71

comprising the encoder. In this case, the angle of the spindle at the needle upper position, which is an upper limit position of the needle bar

12

(or needle

12

a

) is 0 degrees or 360 degrees. The aforesaid upper stop position angle is previously set to a range from 20 to 50 degrees. Furthermore, when the thread cassette

10

is unattached to the cassette mount

5

(No at step S

5

) or when the thread cassette has been attached to the cassette mount

5

but the spindle angle is not at the upper stop position angle (YES at step S

5

; NO at step S

6

), the control device

70

sets the upper stop position command flag (step S

8

) and subsequently advances to step S

9

. The aforesaid lower stop position angle is previously set to a range from 200 to 230 degrees, for example.

After execution of the other interval processing (step S

9

), the control device

70

advances to the control as shown in FIG.

18

. When the motor

9

is in operation (YES at step S

10

), the control device

70

determines whether the spindle angle is at the lower stop position angle (step S

11

). In the case where the spindle angle is at the lower stop position angle (YES at step S

11

), the control device

70

carries out a sewing machine motor stop processing (step S

13

) when the lower stop position flag has been set (YES at step S

12

). As a result, the motor

9

is stopped so that the needle bar

12

is stopped at the lower stop position.

On the other hand, when the spindle angle is not at the lower stop position angle (NO at step S

11

) or when the spindle angle is at the upper stop position angle (YES at step S

14

) but the upper stop command flag has been set (YES at step S

15

), the control device

70

carries out the sewing machine motor stop processing (step S

13

), whereupon the motor

9

is stopped so that the needle bar

12

is stopped at the upper stop position. The control device

70

carries out the other interval processing (step S

16

) after step S

13

or after the negative determination has been made at step S

10

, S

12

, S

14

or S

15

, thereafter finishing the control.

By the above-described control, the position of the needle bar

12

is changed as shown in

FIG. 19

on the basis of the presence or absence of the thread cassette

10

attached to the thread cassette

5

and the needle bar position when the needle up-down key

77

is operated. The control device

70

and the control manners as shown in

FIGS. 17 and 18

serve as a needle bar position changing control unit in the invention. Steps S

3

to S

8

and S

10

to S

15

correspond to a first routine in the invention, whereas steps S

3

to S

5

, S

8

, S

10

, S

11

, S

14

and S

15

correspond to a second routine in the invention.

The operation of the sewing machine M will now be described. In order that the thread cassette

10

maybe attached to the cassette mount

5

, the thread cassette

10

is threaded so that the thread

11

drawn from the thread spool

22

extends around the cassette, whereby the thread cassette

10

is prepared. After the preparation, the thread cassette

10

is attached to the cassette mount

5

. The threading and thread carrying mechanisms

16

B and

16

A are then operated synchronously. When the needle bar

12

is stopped at least at the upper stop position, the thread

11

drawn from the thread cassette

10

is passed through the eye

12

b

of the needle

12

a

attached to the needle bar

12

, by the threading and thread carrying mechanisms

16

B and

16

A. The cassette detecting switch

72

is turned on when the thread cassette

10

has been inserted to each the lowermost position of the cassette mount

5

.

However, the needle bar

12

is not always stopped at the upper stop position when the thread cassette

10

is attached to the cassette mount

5

. Passing the thread

11

through the needle eye

12

b

may fail when the thread cassette

10

is attached to the cassette mount

5

and the threading mechanism

16

B is operated while the needle bar

12

is stopped at a position other than the upper stop position. In this case, the thread cassette

10

needs to be re-attached to the cassette mount

5

and the thread cassette needs to be re-threaded. Thus, load applied to the user is increased, resulting in inconvenience.

In view of the above-described problem, the needle up-down key

77

is operated once before the thread cassette

10

is attached to the cassette mount

5

. In this case, since the thread cassette

10

is not attached to the cassette mount

5

, the needle bar

12

is reliably changed to the upper stop position no matter where the needle bar may be located. Accordingly, when the thread cassette

10

is thereafter attached to the cassette mount, the thread

11

drawn from the thread cassette

10

can be passed through the needle eye

12

b

reliably. Consequently, failure in threading can be prevented and accordingly, the threading mechanism

168

etc. can be prevented from being broken. In the case where the thread cassette

10

has already been attached to the cassette mount

5

, the needle bar

12

can be switched between the upper and lower stop positions alternately according to the position of the needle bar at the time of operation every time the needle up-down key

77

is operated once. Consequently, the convenience of the sewing machine M can be improved.

In the foregoing embodiment, the convenience of the sewing machine can be improved since the needle bar

12

is changed to a suitable position according to the presence or absence of the thread cassette

10

attached to the cassette mount

5

. Particularly in the case where the thread cassette

10

is not attached to the cassette mount

5

, the needle bar

12

can be changed to the upper stop position readily and reliably when the needle up-down key

77

is operated once. Thus, the preparation for attachment of the thread cassette

10

can easily be made. Furthermore, the needle bar

12

is changed to the lower stop position once and then to the upper stop position when the thread cassette

10

is not attached to the cassette mount

5

and the position of the needle bar at the time of operation of the needle up-down key

77

is the upper stop position. Accordingly, the user can clearly find that the needle bar

12

has been changed to the upper stop position. Additionally, in the case where the needle up-down key

77

is operated when the thread cassette

10

has been attached to the cassette mount

5

, the control device

70

controls the motor

9

so that the stop position of the needle bar

12

is changed every time the needle up-down key is operated. Thus, the sewing machine M can be used in the conventional manner.

A modified form of the above-described embodiment will be described. In the foregoing embodiment, in the case where the thread cassette

10

is not attached to the cassette mount

5

and the needle bar is located at the upper stop position, the spindle

9

a

is driven by the motor

9

when the needle up-down key

77

is operated. As a result, the needle bar

12

is changed to the lower stop position once and then to the upper stop position. However, the spindle

9

a

may not be driven even when the needle up-down key

77

is operated. In other words, the needle bar

12

may be maintained at the upper stop position without being moved to the lower stop position.

In the modified form, as shown in

FIG. 20

, when the needle up-down key

77

has been operated (YES at step S

3

), the control device

77

determines whether the thread cassette

10

has been attached to the cassette mount

5

(step S

5

). When the thread cassette

10

has been unattached to the cassette mount

5

(NO at step S

5

) and the spindle angle is the upper stop position angle (YES at step S

30

), the other interval processing (step S

9

) is carried out without drive of the motor

9

since the needle eye

12

b

has already been located at a location where threading is possible. Furthermore, when the spindle angle is not the upper stop position angle (NO at step S

30

), the sewing machine motor start processing (step S

32

) and setting the upper stop command flag (step S

34

) are carried out. When the thread cassette

10

has been attached to the cassette mount

5

(YES at step S

30

), the sewing machine motor start processing (step S

36

) and steps (Steps S

6

to S

8

) for setting a stop command flag are carried out.

In the previous embodiment, in the case where the thread cassette

10

has been attached to the cassette mount

5

and the needle up-down key is operated, the needle bar

12

is changed to the upper stop position when the position of the needle bar at the time of operation is other than the lower stop position. However, when the needle bar

12

is at a position between the lower stop position and the upper stop position, said position excluding the lower and upper stop positions, the needle bar may be changed to the upper stop position. The needle bar

12

may be changed to the lower stop position when the needle bar

12

is at a position between the upper stop position and the lower stop position, said position excluding the lower and upper stop positions.

In the above-described case, as shown in

FIG. 21

, a step S

25

may be added after the negative determination at step S

6

. At step S

25

, the control device determines whether the spindle angle is between the lower and upper stop position angles (for example, 201 and 19 degrees). When the spindle angle is between the lower and upper stop position angles (YES at step S

25

), the upper stop command flag is set (step S

8

). When the spindle angle is not between the lower and upper stop position angles (NO at step S

25

), the lower stop command flag is set (step S

7

) and in the subsequent stop control, the needle bar is changed to the above-described position.

Furthermore, an informing section such as LED etc. may be provided near the cassette mount

5

of the head

4

. When the needle bar

12

is stopped at the upper stop position and the thread cassette

10

can be attached to the cassette mount

5

, the informing section may be turned on to inform that the thread cassette

10

can be attached to the cassette mount

5

. Furthermore, when the needle bar

12

is not stopped at the upper stop position, the informing section may be turned off to inform that the thread cassette

10

cannot be attached to the cassette mount

5

.

The thread cassette

10

in the foregoing embodiment is a mere example and need not be a supply of thread in which the thread is wound on a thread spool. For example, a mere mass of thread may be accommodated in the accommodating cavity. Furthermore, at least one of the walls covering the thread accommodating cavity may be eliminated and the thread spool may be held on a holding portion such as a spool pin.

The needle bar position changing control program stored in ROM

70

b

of the control device

70

may be applied to sewing machines similar to the sewing machine M. The needle bar position changing control program may be supplied via communication means such as the Internet or may be recorded on a recording medium such as CD, MD or FD to be supplied on the recording medium. The first and second routines are the same as described above.

In the foregoing embodiment, the needle bar

12

is not stopped at the lower stop position where the direction of movement of the needle bar is reversed when the thread cassette

10

has not been attached to the cassette mount and the needle bar is at the upper stop position at the time of operation thereof. However, the needle bar may be stopped at the lower stop position and automatically moved to the upper stop position after a predetermined period of time.

The foregoing description and drawings are merely illustrative of the principles of the present invention and are not to be construed in a limiting sense. Various changes and modifications will become apparent to those of ordinary skill in the art. All such changes and modifications are seen to fall within the scope of the invention as defined by the appended claims.

Number	Name	Date	Kind
6641598	Shimizu et al.	Nov 2003	B2
6694904	Mamiya	Feb 2004	B2

Sewing apparatus with needle bar position changing control

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

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US

International Classifications

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (2)

Foreign Referenced Citations (1)