Needle threader with height adjustable thread pusher

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a needle threader for facilitating the insertion of a thread into the eye of a needle.

2. Description of the Related Art

A conventional needle threader is disclosed in JP Laid-open No. 2000-51561, for example. As shown in

FIG. 15

of the accompanying drawings of the present application, the conventional needle threader includes two needle holders

91

provided on the main body

90

. Each needle holder

91

has a trunk

91

b

formed with a needle receiving hole

91

a

for insertion of a needle

8

. On a prescribed side of the trunk is provided a groove

92

for positioning a thread T. The main body

90

is provided with an operating member

93

and a pair of pushers

94

. When the operating member

93

is pushed down in the direction shown by an arrow Na, each of the pushers

94

rotates about a shaft

95

in the direction shown by an arrow Nb, and advances towards the needle holder

91

. Consequently, as shown in

FIG. 16

, the thread T is pushed by the pusher

94

to pass through the eye

80

of the needle

8

.

While being functional in several respects, the conventional needle threader suffers the following drawbacks.

Generally, sewing needles come in various sizes, and the location and size of the needle eyes usually differ. Specifically, as shown in

FIG. 17

, a diametrically small needle

8

A tends to have a small eye

80

A, and the distance s

1

between the head end and the eye

80

A is short. On the other hand, a diametrically greater needle

8

B may have a large eye

80

B, and the distance s

2

between the head end and the eye

80

B is relatively long.

In the prior art, the forward path of the pusher

94

to push the thread T toward the needle holder

91

is permanently fixed. Thus, the insertion of the thread into the eye

80

may fail if a change is made in the height of the eye

80

of the needle

8

set in the needle holder

91

.

In light of the above, the prior art is provided with two sets of threading mechanisms each including the combination of a pusher

94

and a needle holder

91

, one set being arranged for a thick needle, and the other for a thin needle, so that either one of the needles is properly threaded.

However, providing a plurality of threading mechanisms increases the number of components in the threader as a whole, thereby complicating the overall structure and resulting in a higher production cost. Also, it allows the threader to become bulky and renders inconvenient to be stored or carried. Further, in case where a small needle is inserted into the larger needle holder by mistake, the thread cannot be passed through the needle's eye, which forces the user to reset the needle into the other needle holder for thinner needles. Particularly, since the user has difficulties in deciding which one of the needle holders

91

is suitable for a needle to be threaded, the above troublesomeness becomes more conspicuous.

SUMMARY OF THE INVENTION

The present invention has been proposed under the circumstances described above. It is, therefore, an object of the present invention to provide a needle threader that can deal with needles of various sizes, with a single or reduced number of threading mechanisms, whereby the overall structure is simplified and the convenience is improved.

According to the present invention, there is provided a needle threader comprising: a needle holder for holding a needle; and a pusher for inserting a thread into an eye of the needle, the pusher being movable in a forward direction toward the needle holder and in a backward direction opposite to the forward direction. The pusher is movable longitudinally of the needle while the pusher is held in sliding contact with the needle.

Preferably, the needle threader of the present invention may further comprise a pusher guide for guiding the pusher, wherein the pusher guide changes its position for causing the pusher to move longitudinally of the needle.

Preferably, the needle threader of the present invention may further comprise a working mechanism provided with an operation lever for operating the pusher, wherein the operation lever continues to be operated after the pusher comes into contact with the needle, so that the pusher guide causes the pusher to move longitudinally of the needle.

Preferably, the needle threader of the present invention may further comprise an elastic member arranged between the operation lever and the pusher. The elastic member permits further operation of the operation lever after the pusher is brought into contact with the needle.

Preferably, the needle holder may comprise a needle receiving hole for vertically holding the needle. The needle holder may be formed with a pusher path extending across the needle receiving hole for allowing the passage of the pusher across the needle receiving hole.

Preferably, the pusher path may be large enough to allow the pusher to move longitudinally of the needle.

Preferably, the pusher may undergo a first forward move and a second forward move subsequent to the first forward move. The pusher may advance horizontally from an initial position to the needle during the first forward move, while the pusher may ascend during the second forward move.

Preferably, the pusher may undergo a first backward move subsequent to the second forward move and a second backward move subsequent to the first backward move. The pusher may retreat horizontally during the first backward move to pull out of the eye of the needle, while the pusher may descend during the second backward move to return to the initial position.

Preferably, the needle threader of the present invention may further comprise a needle presser that is horizontally reciprocative for selectively pressing the needle against a wall surface of the needle receiving hole.

Preferably, the pressing of the needle by the needle presser may be performed before the pusher comes into contact with the needle.

Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a perspective view showing an example of a needle threader embodying the present invention;

FIG. 2

is a sectional view taken along II—II in

FIG. 1

;

FIG. 3A

is an enlarged fragmentary sectional view of

FIG. 2

, and

FIG. 3B

is a sectional view taken along III—III in

FIG. 3A

;

FIG. 4

is a sectional view illustrating the operational state of the needle threader shown in

FIGS. 1 and 2

;

FIG. 5A

is an enlarged fragmentary sectional view of

FIG. 4

, and

FIG. 5B

is a sectional view taken along V—V in

FIG. 5A

;

FIG. 6A

is a view illustrating the basic parts of an arm and a guide for providing a working mechanism, while

FIG. 6B

is a sectional view taken along VI—VI in

FIG. 6A

;

FIGS. 7A and 7B

are fragmentary sectional views of a cam plate and a guide for providing the working mechanism;

FIG. 8

is a fragmentary sectional view illustrating a cam plate and a guide for providing the working mechanism;

FIGS. 9A and 9B

illustrate how the pusher moves;

FIG. 10

is a sectional view showing a process step of the needle threader shown in

FIGS. 1 and 2

;

FIG. 11

is a fragmentary sectional view showing a process step of the needle threader shown in

FIGS. 1 and 2

;

FIG. 12

is a sectional view showing a process step of the needle threader shown in

FIGS. 1 and 2

;

FIG. 13

shows another example of the pusher's move;

FIG. 14

shows another example of the pusher's move;

FIG. 15

shows a conventional needle threader;

FIG. 16

shows a threading step in the conventional needle threader; and

FIG. 17

shows conventional needles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 through 12

show a needle threader in accordance with an embodiment of the present invention. The needle threader A of this embodiment has an appearance shown in

FIG. 1

, where a working mechanism

3

shown in

FIG. 2

is incorporated in a synthetic resin housing

10

for operation of a pusher

2

.

The housing

10

includes a side surface from which an operation lever

30

for operating the working mechanism

3

protrudes. An upper region of the housing

10

is provided with a needle holder

4

for holding a needle

8

in an upstanding posture, a cutter

11

for cutting a thread T, and a valley

12

. When the needle threader A is used, a part of the thread T is set to be caught by the bottom of the valley

12

.

As best shown in

FIG. 3A

, the needle holder

4

includes a needle receiving hole

40

with a supporting surface

40

a

at its bottom, a pusher path

41

, and a needle presser

42

. The needle receiving hole

40

extends in an up-and-down direction (in a vertical direction) to be open in the upper surface of the housing

10

. The needle receiving hole

40

receives the needle

8

with its head (the end formed with an eye

80

) positioned below. The needle receiving hole

40

has an inner diameter great enough to accommodate needles of the largest type among several ordinary types used for sewing or handicraft-making purposes.

The supporting surface

40

a

is provided for supporting the head of the needle

8

. The supporting surface

40

a

is configured as a concave, curved surface. Generally, the eye-formed head of a needle is rendered flat. The supporting surface

40

a

comes into contact with the flattened needle head, thereby correcting the orientation of the needle so that the needle's eye faces to the pusher

2

. The pusher path

41

extends across the needle receiving hole

40

and allows the end stick

20

of the pusher

2

to go across the needle receiving hole

40

. As described later, the pusher

2

not only reciprocates horizontally but moves upward and downward. In light of this, the vertical size of the pusher path

41

is greater than the vertical thickness of the end stick

20

of the pusher

2

.

The needle presser

42

is provided for holding the needle

8

in place by pressing the needle

8

against an inner wall of the needle receiving hole

40

. The needle presser

42

may be made of synthetic resin, for example, and is formed with a hole

42

a

communicating with the needle receiving hole

40

. The needle

8

is set to extend through the hole

42

a

. The needle presser

42

is moved horizontally when the lever

30

is operated.

More specifically, as shown in

FIG. 2

, an actuator

70

including a first and a second arms

70

a

,

70

b

is rotatably supported by a shaft

71

for operatively linking the operation lever

30

and the needle presser

42

. The first arm

70

a

, which passes through a through-hole formed at one end of the needle presser

42

, is constantly biased in the arrowed N

1

direction by a spring

72

. Thus, the actuator

70

tends to be turned in the N

2

direction, thereby pressing the second arm

70

b

against the upper surface of the operation lever

30

. The upper face of the operation lever

30

is a cam surface formed with a convex

30

a

, and when the operation lever

30

is pushed downward as shown in

FIG. 4

, the convex

30

a

comes into contact with the second arm

70

b

, whereby the second arm

70

b

rises in the arrowed N

3

direction. Consequently, the first arm

70

a

moves in the arrowed N

4

direction, together with the needle presser

42

moved in the same direction.

When the needle presser

42

moves in the N

4

direction, the needle

8

is pressed against the inner wall of the needle receiving hole

40

by the needle presser

42

, as shown in FIG.

5

A. Referring to

FIGS. 5B and 3B

, the side surfaces of the needle presser

42

are formed with a concavity

42

b

, in which protrusions

14

of the housing

10

are accommodated. The walls defining the concavities

42

b

come into contact with the protrusions

14

so as to prevent the needle presser

42

from moving with an unduly great stroke or from pushing the needle

8

against the inner wall of the needle receiving hole

40

with unnecessarily great force.

In the needle presser

42

, the hole

42

a

is partially cut open in the circumference, and formed with a pair of protrusions

42

c

flanking the opening for pressing the needle

8

against the inner wall of the needle receiving hole

40

. With this arrangement, each of the protrusions

42

c

can be elastically deformed in pressing the needle

8

against the inner wall of the needle receiving hole

40

. This is advantageous to pressing the needle

8

with an appropriate force regardless of the size of the needle

8

. Further, each of the protrusions

42

c

is formed with a curved surface by which the needle

8

is pressed. Thus, when the needle

8

is pushed against the inner wall of the needle receiving hole

40

, a positional correction can be made, as viewed perpendicularly to the direction in which the pusher

2

reciprocates, so that the axis of the needle

8

will coincide with the center between the projections

42

c

. As a result, the longitudinal axis of the needle

8

is positioned right in front of the pusher

2

, thereby preventing the misalignment between the eye

80

of the needle

8

and the pusher

2

in the direction perpendicular to the reciprocal movement of the pusher

2

. When the operation lever

30

is brought back to the original position shown in

FIG. 2

, the needle presser

42

returns to the original position shown in FIG.

2

and

FIGS. 3A

,

3

B.

The pusher

2

for pushing the thread T into the eye

80

of the needle

8

may be formed by stamping out a thin metal plate into a prescribed form. The end stick

20

of the pusher

2

extends in the prescribed direction to be inserted into the eye

80

of the needle

8

. The extremity of the pusher

2

is formed as a concave end so that it does not easily let go of the thread T being pushed.

As shown in

FIG. 2

, in addition to the operation lever

30

, the working mechanism

3

includes an operation plate

31

, a swing arm

32

, a cam plate

33

, a guide

34

, and a first and a second springs

35

,

36

. Among these members, the first and the second springs

35

,

36

are coil springs made of metal, whereas the others are made of synthetic resin.

The first spring

35

exerts urging force to push up the operation lever

30

in the arrowed N

5

direction. The operation plate

31

is secured to the operation lever

30

by pins

79

. The operation plate

31

and the operation lever

30

are integrally rotatable about a shaft

78

.

The guide

34

, provided for guiding the pusher

2

in motion, is formed with a straight slit

34

a

, as shown in FIG.

6

A. The pusher

2

is attached to the guide

34

in a manner such that it can move reciprocally along the slit

34

a

. As shown in

FIG. 6B

, this attachment of the pusher

2

is effected by securing members

77

A,

77

B. The securing member

77

A has a pair of projections

77

a

penetrating the slit

34

a

and a pair of holes

21

formed in the pusher

2

. These projections

77

a

are fitted in a pair of holes

77

b

formed in the securing member

77

B whereby the securing members

77

A,

77

B clamp to hold the pusher

2

.

Referring to

FIG. 6A

, the swing arm

32

which is pivotally mounted on the shaft

78

moves the pusher

2

reciprocally. A top portion

32

c

of the swing arm

32

enters the region between a pair of walls

77

c

of the securing member

77

B, and the swing arm

32

pushes these walls

77

c

, to cause the pusher

2

to reciprocate in the slit

34

a

. As described later, the guide

34

is pivotable about a shaft

76

, and the pivoting of the guide

34

determines the moving direction of the pusher

2

.

The second spring

36

is disposed between the swing arm

32

and a pin

37

, to provide some elasticity between the operation of the lever

30

and the pivoting of the swing arm

32

. The pin

37

is configured substantially in a cylinder, but a portion surrounded by the second spring

36

is configured accordingly for that purpose. As illustrated in

FIG. 2

, the pin

37

is disposed at one side of an opening

31

a

formed in the operation plate

31

. Thus, the pin

37

transfers along an arc centered about the shaft

78

in response to the operation of the lever

30

. Referring to

FIG. 6A

, the swing arm

32

is moved in the N

7

direction as the pin

37

moves in that direction pushing the swing arm

32

via the second spring

36

. A side surface

32

a

of the swing arm

32

faces one side surface

30

b

of the operation lever

30

. The rotation of the swing arm

32

in the N

8

direction opposite to the above direction is caused by the lever

30

the side surface

30

b

of which pushes the swing arm

32

in that particular direction.

As shown in

FIG. 7A

, the cam plate

33

is substantially fan-shaped and pivotably mounted on the shaft

78

. The cam plate

33

is formed with an opening

33

a

for receiving the pin

37

. The opening

33

a

is oval-shaped and allows the pin

37

to make an arc for a certain distance s

3

inside thereof. As shown in

FIG. 7B

, the cam plate

33

moves in the N

6

direction when the pin

37

abuts the top of the opening

33

a

thereof and pushes it in that direction. The cam plate

33

moves in the opposite direction when the pin

37

comes to the bottom and pushes it downward. In an ordinary state (i.e. when the lever

30

is not operated), the cam plate

33

is pressed onto a frictional surface

15

near the bottom of the housing

10

, and the frictional force &mgr; in relation to the surface

15

prevents the cam plate

33

from rotating. Thus, supposing that some rotational force is exerted on the cam plate

33

, the cam plate

33

does not rotate when the force is weaker than the frictional force u, but begins to rotate upon application of a greater rotational force.

The cam plate

33

includes cam portions

33

b

-

33

d

on its outer surface for moving the guide

34

. The cam portion

33

c

is flanked by the cam portions

33

b

,

33

d

and raised higher than the cam portions

33

b

,

33

d

. The guide

34

includes a protrusion

34

b

coming into contact with the cam portions

33

b

-

33

d

. As shown in FIG.

7

A and

FIG. 8

, when the protrusion

34

b

is on either of the cam portions

33

b

or

33

d

, the guide

34

is held in a position causing the slit

34

a

to extend horizontally. On the other hand, as shown in

FIG. 7B

, when the protrusion

34

b

is on the cam portion

33

c

, the guide

34

is held in a position causing the slit

34

a

to extend upward to the right in the figure.

Next, how to use the needle threader A and the function thereof will be described.

First, as shown in

FIG. 2

, a needle

8

is held by the needle holder

8

and a thread T is laid at the bottom of the valley

12

. In this state, the operation lever

30

is pushed downward against the elastic force of the first spring

35

. Then, as noted above with reference to

FIGS. 4 and 5

, the convex

30

a

of the operation lever

30

causes the actuator

70

to rotate, and the needle presser

42

is moved in the arrowed N

4

direction. As a result, the needle

8

is pushed against the inner wall of the needle receiving hole

40

, whereby the needle

8

is positioned so that the axis thereof is located immediately in front of the pusher

2

.

In response to the operation of the lever

30

, on the other hand, the working mechanism

3

moves the pusher

2

forward to and then backward from the needle holder

4

. The operational behavior of the pusher

2

of the working mechanism

3

can be divided into a first operational mode shown in

FIG. 9A and a

second operational mode shown in FIG.

9

B. For better understanding of the specific functions of the working mechanism

3

, the general outlines of the first and the second operational modes will be described below.

In the first operational mode shown in

FIG. 9A

, the end stick of the pusher

2

is held at the same height as the eye

80

of the needle

8

while the pusher

2

is advancing towards the needle

8

, whereby the end stick

20

of the pusher

2

is allowed to go straight into the eye

80

. The movement of the pusher

2

includes a first and a second forward moves F

1

, F

2

and a first and a second rearward moves R

1

, R

2

. In the first forward move F

1

, the pusher

2

horizontally moves from the initial position shown in

FIG. 2

towards the needle

8

, whereas in the subsequent second forward move F

2

, the pusher

2

advances further in a diagonally upward direction. In the first rearward move R

1

subsequent to the second forward move F

2

, the pusher

2

retreats horizontally, while in the second rearward move R

2

, the pusher

2

retreats further in a diagonally downward direction.

In the second operational mode shown in

FIG. 9B

, on the other hand, the end stick

20

of the pusher

2

differs in height from the needle eye

80

of the needle

8

as the pusher

2

advances towards the needle

8

. As for the movements of the pusher

2

, the second forward move F

2

′ is different from the above-described second forward move F

2

, while the other moves are the same as those in the first operational mode. The second forward move F

2

′ includes an ascent of the pusher

2

sliding on the needle

8

, which enables the end stick

20

of the pusher

2

to enter into the eye

80

of the needle

8

.

The specific function of the working mechanism

3

will now be explained. Referring to

FIG. 4

, when the operation lever

30

is pushed downward as shown in

FIG. 4

, the pin

37

is rotated about the shaft

78

in the N

9

direction. As a result, the swing arm

32

is pushed in that direction by the pin

37

via the second spring

36

, to be rotated together with the operation lever

30

while being held in contact with a side surface

30

b

of the operation lever

30

. This rotation of the swing arm

32

causes the pusher

2

to advance towards the needle

8

. At an early moving stage of the pin

37

, the pin

37

shifts only in a region of the size s

3

within the opening

33

a

of the cam plate

33

shown in FIG.

7

A. Thus, at this stage, the cam plate

33

remains stationary, thereby causing the protrusion

34

b

of the guide

34

to keep in contact with the cam portion

33

b

of the cam plate

33

, and allowing the slit

34

a

of the guide

34

to be horizontally elongated. Accordingly, the advancement of the pusher

2

is performed horizontally. The horizontal movement of the pusher

2

continues until the end stick

20

of the pusher

2

comes just before the needle

8

. This horizontal movement corresponds to the first forward move F

1

shown in

FIGS. 9A and 9B

.

When the operation lever

30

is pushed further down as shown in

FIG. 7B

, the pin

37

comes into contact with the top of the opening

33

a

, thereby pushing the cam plate

33

in the N

6

direction. As a result, the cam portion

33

c

of the cam plate

33

comes into contact with the protrusion

34

b

of the guide

34

whereby the guide

34

is caused to tilt, with the right end raised higher. Meanwhile, the swing arm

32

, being pressed by the pin

37

via the second spring

36

, continues to rotate, thereby advancing the pusher

2

further.

As seen from the above, if the end stick of the pusher

2

and the eye

80

of the needle

8

are at the same height at the end of the first forward move F

1

, the second forward move F

2

shown in

FIG. 9A

takes place, where the end stick

20

of the pusher

2

is inserted straight into the eye

80

and then moves diagonally upward.

FIG. 10

shows the state where the end stick

20

of the pusher

2

extends through the eye

80

. By this movement of the pusher

2

, the thread T is passed through the eye

80

. For the second forward move F

2

, the pusher

2

advances upward, and may lift the needle

8

by abutting on the upper edge of the eye

80

of the needle

8

, though this lifting does not damage the needle

8

. The pusher

2

advances sufficiently after its tip passes through the eye

80

. With this arrangement, an appropriate length of thread T is pushed into the eye

80

. Thus, the thread T is not easily pulled out of the eye

80

when the needle

8

is taken out from the needle holder

4

.

On the other hand, when the pusher

2

is lower than the eye

80

of the needle

8

, as shown in e.g.

FIG. 11

, the end stick

20

of the pusher

2

bumps into the needle

8

. When the pusher

2

and the needle

8

abut each other in this manner, the pusher

2

cannot advance any further, nor can the swing arm