Snap hook

A snap hook comprises a base member having a J-shaped hook and a flexible member, and a slider mounted on the base member for movement in directions perpendicular to the longitudinal direction of the base member to open and close the J-shaped hook, wherein the hook is normally held closed by the slider biased by the flexible member, and when the slider is depressed with a ring or the like, the slider is moved inwardly to open the hook so that the ring or the like can be hooked.

FIELD OF THE INVENTION AND RELATED ART STATEMENT 
This invention relates to a plastic snap hook for retaining a ring or like 
object and, more particularly, to a snap hook for retaining a metal ring 
or the like provided on a strap to be detachably mounted on a bag or the 
like. 
Various snap hooks of such type have been proposed and discriptions thereof 
can be found, for instance, in Japanese Utility Model Publication No. SHO 
57-24985 and Japanese Utility Model Application Public Disclosure No. SHO 
59-17314. 
The snap hook disclosed in the former publication comprises a base member 
having a hook provided at one end, a slider slidable back and forth along 
the base member in the longitudinal direction thereof and a coil spring 
biasing the slider toward the tip of the hook. The slider is moved into 
contact with and away from the hook tip. An O- or D-ring or like object 
can be detachably retained in the hook of the base member by operating the 
slider. 
However, since this snap hook includes the coil spring in addition to the 
base member and the slider, its structure is rather complicated, and its 
assembly is rather troublesome. Further, since the base member has to have 
a space for movement of the slider in its longitudinal direction, the snap 
hook inevitably has a considerably large length, resulting in a large 
overall size. Further, the operation of hooking an object in the hook is 
not so simple. More specifically, the slider first has to be pulled away 
from the hook by the finger. After the hook has been opened in this way, 
the object is fitted in the hook. That is, the object cannot be hooked in 
the hook by a single operation. 
The snap hook disclosed in the latter publication mentioned above comprises 
a base member having a hook provided at one end and an elastic pawl 
integrally extending from a stem of the base member toward the hook. 
Normally, the tip of the elastic pawl is held in contact with the inner 
surface of the hook by a spring force to have the hook closed. 
The hook is opened and closed by moving the end of the elastic pawl away 
from and into contact with the hook. The hook thus can be opened with a 
light force applied to the elastic pawl by depressing a portion thereof 
near the tip with the finger. However, the object is inserted into and 
taken out of the snap hook between the tip of the elastic pawl and the 
hook. Therefore, if a portion of the elastic pawl near the tip thereof is 
held depressed with the finger, the finger will constitute an obstacle to 
insertion or removal of the object. To avoid this, a portion of the 
elastic pawl near the stem thereof has to be depressed. This means that a 
strong force must be appolied to the elastic pawl when inserting or taking 
out the object. Otherwise, the finger depressing the elastic pawl 
constitutes an obstacle particularly when taking out the object from the 
hook. 
SUMMARY AND OBJECT OF THE INVENTION 
An object of the invention is to provide a snap hook, which permits a ring 
or like object to be reliably hooked in and taken out of a hook with a 
simple operation, and which also permits reduction of the size of the snap 
hook. 
To attain the above object of the invention, there is provided a plastic 
snap hook, which comprises a base member having a J-shaped hook provided 
at one end and a slider movable along the base member in directions 
perpendicular to the longitudinal direction of the base member, and in 
which an object is hooked in the J-shaped hook of the base member by 
moving the slider. The base member is provided at an intermediate point of 
its longitudinal direction with a flexible member. The slider has an end 
portion cooperating with the free end of the J-shaped hook, an operating 
portion with the inner surface thereof urging the flexible member at all 
times, and side portions extending from the opposite sides of the 
operating portion and in frictional contact with the opposite sides of the 
base member. The frictional contact surfaces of the base member and slider 
are provided with coupling means such that they are coupled together for 
relative movement in directions perpendicular to the longitudinal 
direction of the base member. The coupling means permits the slider to be 
moved along the base member between a position at which the hook is open 
and a position at which the hook is closed. 
To hook an object such as a ring in the J-shaped hook, the hook is opened 
by pushing the slider. The slider may be pushed either with the finger or 
with the object. In the latter case, the object can be inserted into the 
J-shaped hook as soon as the hook is opened. 
More specifically, when the outer surface of the operating portion of the 
slider is depressed with the object, the slider is moved toward the 
corresponding portion of the base member. At this time, the slider is 
guided along the opposite sides of the base member by coupling means 
provided on the frictional contact surfaces of the slider and base member. 
Also at this time, the flexible member provided on the base member is 
compressed against its elasticity by the inner surface of the operating 
portion of the slider. As the slider is depressed, its end portion is 
inwardly separated from the tip of the J-shaped hook, thus opening the 
hook. 
As soon as the hook is opened, the object may be moved along the outer 
surface of the operating portion of the slider toward the gap formed 
between the tip of the J-shaped hook and the end portion of the slider, 
whereby the object is fitted into the J-shaped hook through the gap 
mentioned above. 
When the object is fitted into the hook, the urging force on the operating 
portion of the slider is released. The slider is thus moved away from the 
corresponding portion of the base member along the opposite sides thereof 
by the elastic force of the flexible member urging the inner surface of 
the operating portion of the slider. The end portion of the slider is thus 
elastically click engaged with the end of the J-shaped hook from the inner 
side thereof, thus closing the hook. 
To take out the ring from the hook, the hook is again opened. The hook may 
be opened by depressing the operating portion of the slider with the 
finger. In this case, however, the finger depressing the slider is liable 
to interfere with the operation of taking out the object from the hook. To 
avoid this, the slider may be moved by holding its opposite sides with the 
fingers. In this case, the object can be readily taken out of the hook 
when the hook is opened. Then, only the fingers may be released from the 
opposite sides of the slider. As a result, the slider is again moved back 
into click engagement with the tip of the J-shaped hook to close the hook 
by the elastic force of the flexible member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The snap hook according to the invention will now be described in detail in 
conjunction with the illustrated embodiment thereof. 
Reference numeral 1 generally designates the snap hook, which comprises two 
parts, i.e. a base member 3 having a J-shaped hook 2 provided at one end 
and a slider 4 movable along the base member 3 in directions perpendicular 
to the longitudinal direction of the base member 3. The base member 3 and 
slider 4 are made as plastic moldings. 
The stem of the J-shaped hook 2 of the base member 3 extends as a 
plate-like portion and terminates in a substantially rectangular portion 5 
at the other end. The opposite sides 5' of the rectangular portion 5 are 
formed with perpendicular grooves 6, which extend in a direction 
perpendicular to the longitudinal direction of the base member 3 and are 
closed at the opposite ends. The grooves 6 define the range of movement of 
the slider 4. The base member 3 is provided on the upper surface 3' of its 
longitudinally intermediate portion with a flexible member 7. The flexible 
member 7 extends obliquely toward the tip 2' of the J-shaped hook 2. In 
the illustrated embodiment, the flexible member 7 is folded at 
intermediate portions in its length direction, so that it is zigzag-shaped 
or substantially M-shaped. However, it is possible to use a flat member 
without any folded portion instead of the illustrated flexible member 7. 
The free end of the flexible member 7 is in contact with the inner surface 
of the slider 4 and outwardly biases the slider 4. 
In the illustrated embodiment, a longitudinally intermediate portion of the 
base member 3 where the slider 4 is mounted is provided on opposite sides 
with notches 8' to form a slider mounting portion 8 having a reduced 
width. With this structure, the slider 4 mounted on the base member 3 does 
not protrude sidewise from the base member 3, that is, the opposite sides 
of the slider 4 are flush with the opposite sides of the base member 3. 
The slider 4 is mounted on the slider mounting portion 8 of the base member 
3 in a direction perpendicular to the longitudinal direction of the base 
member 3. The slider 4 has a channel-shaped sectional profile. More 
specifically, the slider 4 has a substantially hill-shaped operating 
portion 9 which can be readily depressed with the finger, and opposite 
side portions 10 extending from the opposite sides of the operating 
portion 9. The slider 4 further has a stepped end portion 11, which can 
engage the tip 2' of the hook 2 from the inner side thereof. The side 
portions 10 of the slider 4 are provided with protuberances 12 projecting 
from the inner surface. The protuberances 12 are received in the 
perpendicular grooves 6 of the base member 3. 
The end of the substantially rectangular portion 5 of the base member 3 
remote from the J-shaped hook 2 is coupled by snap coupling to a shaft 
portion 14 of a D-shaped ring 13, to which a belt, a band or the like is 
attached. 
More specifically, an anchor-shaped leg 15 extends from the end of the 
portion 5. The leg 15 consists of a shaft portion 16 extending from the 
end of the portion 5, a disk-like lid portion 17 provided on the free end 
of the shaft portion 16 and a pair of elastic portions 18 extending from a 
portion of the shaft portion 16 adjacent to the lid portion 17 in a 
mutually flaring fashion toward the portion 5. The transversal center of 
the shaft portion 14 of the D-shaped ring 13 is provided with a hollow 
cylindrical portion 19. The leg portion 15 is fitted in the hollow 
cylindrical portion 19. 
In this embodiment, the three parts i.e., the base member 3 having the 
J-shaped hook 2, the slider 4 and the D-shaped ring 13, are assembled 
together as a snap fastener 1. 
The slider 4 may be mounted on the slider mounting portion 8 of the base 
member 3 by fitting it on the portion 8 with its opposite sides 10 
slightly spread from each other. When the protuberances 12 of the side 
portions 10 of the slider 4 are received in the perpendicular grooves 6 of 
the base member 3, the side portions 10 of the slider 4 slightly close 
toward each other by their elasticity to restore the initial form of the 
slider 4. The protuberances 12 of the slider 4 are now restrained in the 
perpendicular grooves 6 of the base member 3 for movement along the 
grooves 6. 
Further, when the slider 4 is mounted, the inner surface 9' of its 
operating portion 9 engages and slightly pushes the flexible member 7 
provided on the base member 3. The inner surface 9' of the operating 
portion 9 of the slider 4 mounted on the base member 3 thus is outwardly 
biased by the flexible member 7. Normally, therefore, the end portion 11 
of the slider 4 is held urged against the tip 2' of the hook 2 from the 
inner side. That is, the hook 2 is normally closed. 
The D-shaped ring 13 is coupled to the base member 3 by inserting the leg 
portion 15 of the base member 3 into the hollow cylindrical portion 19 of 
the D-ring 13. The bore of the hollow cylindrical portion 19 has a reduced 
diameter portion (not shown) provided adjacent to or near the end, from 
which the leg portion 15 is inserted. As the leg portion 15 is inserted, 
the elastic portions 18 thereof are inwardly flexed by their engagement 
with the edge of the bore of the portion 19. When the flexed elastic 
portions 18 clear the reduced diameter portion of the bore, they are 
expanded to click engage with the inner wall of the portion 19. The bore 
of the portion 19 is thus closed by the lid portion 17. In this state, the 
leg portion 15 is retained in the portion 19 such that it cannot be taken 
out in the reverse direction. The base member 3 is rotatable about the 
shaft portion 16. The D-shaped ring 13 and base member 3 are swingable 
about the shaft portion 14 of the D-shaped ring 13 in directions 
perpendicular to the direction of rotation noted above. The D-shaped ring 
13 and base members 3 thus have a large degree of freedom of relative 
movement, so that it is possible to easily remove any twist in a belt or 
the like attached to the D-shaped ring. 
The operation of the snap hook having the above construction for hooking an 
object, e.g., an O- or D-shaped ring member 20, in the hook and removing 
the object therefrom, will now be described. 
To hook a ring 20, the J-shaped hook 2 is opened by pushing the operating 
portion 9 of the slider 4 either with the finger or with the ring 20. In 
the latter case, the ring 20 can be inserted into the J-shaped hook 2 as 
soon as the hook 2 is opened. 
When the outer surface of the operating portion 9 of the slider 4 is pushed 
with the ring 20, the slider 4 is moved toward the corresponding portion 
of the base member 3 against the elastic force of the flexible member 7. 
As the operating portion 9 is depressed, its inner surface 9' inwardly 
pushes the flexible member 7 and compresses it so that it is folded 
closely. At this time, the protuberances 12 of the side portions of the 
slider 4 are moved along the perpendicular grooves 6 of the sides 5' of 
the rectangular portion 5 of the base member 3 toward the longitudinally 
intermediate plate-like portion thereof. With the movement of the slider 
4, the end portion 11 thereof is separated inwardly from the top 2' of the 
hook 2 to open the J-shaped hook 2. 
In this state, the ring 20 may be quickly inserted into the open hook 2 by 
moving the ring 20 along the operating portion 9 toward the tip 2' of the 
hook 2 while continually applying the inward pushing force to the ring 20. 
When the ring 20 is inserted in the hook 2, the operating portion 9 is 
released from the inward force. The slider 4 is thus outwardly moved by 
the elastic force of the flexible member 7. The end portion 11 of the 
slider 4 is thus elastically click engaged with the end 2' of the J-shaped 
hook 2 from the inner side thereof, that is, the slider 4 is returned to 
its position closing the hook 2. In this way, the ring 20 is hooked in the 
J-shaped hook 2. 
To take out the ring 20 from the hook 2, the operating portion 9 of the 
slider 4 may be depressed with the finger as described before. So that the 
finger will suffer no interference with the removal, however, the slider 4 
may be grasped at the opposite sides 10 thereof with two fingers and 
pulled down. 
With the inward movement of the slider the hook 2 is opened again. With the 
opposite sides 10 of the slider 4 held by the fingers, the ring 20 can be 
readily taken out of the hook 2 past the tip 2' thereof without being 
interfered with the fingers. 
When the ring 20 has been taken out, the fingers are released from the 
sides 10 of the slider 4, whereby the slider 4 is returned to the initial 
position to close the hook 2 by the elastic force of the flexible member 
7. 
In the above embodiment, the perpendicular grooves 6 are provided on the 
side of the base member 3 and the protuberances 12 on the side of the 
slider 4 as means of coupling the base member 3 and slider 4. However, to 
the same end, it is also possible to provide protuberances on the side of 
the base member and perpendicular grooves on the side of the slider. 
If the base member 3 and slider 4 are made of plastic materials having 
different colors, the operating portion 9 of the slider 4 can be perceived 
at a glance. In addition, the use of different colors will have a 
decorative effect. 
As has been described in the foregoing, the snap hook according to the 
invention comprises two components, i.e., the base member and the slider, 
with the base member provided with the integral flexible member for 
biasing the slider. It is thus possible to provide a plastic snap hook 
which has a simple structure and can be very readily assembled. 
In addition, the slider is moved in directions perpendicular to the 
longitudinal direction of the base member. Therefore, the length of the 
base member can be reduced compared to the case of the structure where a 
slider is moved back and forth in the longitudinal direction of a base 
member. It is thus possible to reduce the size of the whole snap hook. 
Further, the slider may be moved either by depressing its operating portion 
with the finger or by pulling it with its opposite sides held by two 
fingers. The operation is thus easy compared to the case where the elastic 
pawl is depressed with the finger as mentioned before. Particularly, the 
object, such as a ring, can be readily taken out without interference from 
any finger.