Headrest folding device

1. A headrest folding device comprising:

a main bracket mounted in a seat back or a headrest;

a stay, mounted in any one of said seat back and said headrest, being rotated with respect to said main bracket so as to be moved between an upright (unfolding) position and a folding position;

a lock link having one end supported by said main bracket through a first hinge shaft and an other end engaged with a horizontal bar of said stay;

a first twisted coil spring having one end supported by said main bracket and an other end supported by said horizontal bar of said stay;

a release lever having one end supported by said main bracket through a second hinge shaft;

a ratchet which is rotatably supported by said main bracket through a line shaft, and wherein contact thereof with said lock link is released by said release lever;

a second twisted coil spring having one end supported by said main bracket and an other end supported by said release lever; and

an operating member configured to apply operating force to the other end of said release lever.

2. The headrest folding device according to claim 1 ,

wherein said main bracket comprises:

a front plate;

a pair of side plates which is formed at the left and the right sides of said front plate and bended backward;

a pair of coupling plates, in said side plates, bended towards the left and the right directions respectively; and

an upper plate and a lower plate which are respectively formed at the upper and the lower sides of said front plate and bended backward, wherein

an open slot disposed before the other end of said first twisted coil spring is pressed is formed in said upper plate.

3. The headrest folding device according to claim 1 ,

wherein said lock link comprises:

a link plate;

a hinge hole formed in the upper side of said link plate;

a V-shaped groove formed in the lower end of said link plate; and

a rear groove formed in the back side of said link plate and inserted into said horizontal bar, and fixed thereby; and

said release lever comprises:

a lever main body having a length along the front to rear direction;

a rotation hole formed in the front side of said lever main body;

a stopping threshold formed in the front side of said lever main body; and

a hanger portion formed in the rear side of said lever main body wherein said operating member is hanged, and

said ratchet comprises:

a ratchet main body wherein a rotation hole is formed;

a V-shaped ridge formed in the upper side of said ratchet and being contacted with said V-shaped groove; and

a stopping protrusion formed in the lower side of said ratchet main body and held in said stopping threshold.

4. The headrest folding device according to claim 3 ,

wherein

a stopper protrusion is formed in the front end side of said lever main body;

a slot which forms a space wherein said stopper protrusion can be rotated is formed in said front plate of said main bracket; and

a stopper retaining plate wherein said stopper protrusion is held is formed in the lower end of said slot.

5. The headrest folding device according to claim 4 ,

further comprising

a third twisted coil spring having one end supported by said main bracket and an other end supported by said ratchet.

6. The headrest folding device according to claim 1 ,

wherein

said main bracket is mounted in said headrest, and

said stay is mounted in said seat back, and

said stay comprises a horizontal bar fixed to said lock link and a pair of vertical pipes installed in both sides of said horizontal bar respectively, wherein

said operating member is a wire pulling the other end of said release lever, and said wire is disposed so as to be inserted into and passing through any one of said vertical pipes.

7. The headrest folding device according to claim 1 ,

wherein

said main bracket is mounted in said headrest, and

said stay is mounted in said seat back, and

said operating member is a button unit pushing the other end of said release lever.

8. The headrest folding device according to claim 7 ,

wherein

said lock link comprises:

a link plate;

a hinge hole formed in the upper side of said link plate;

a V-shaped groove formed in the upper end of said link plate; and

a rear groove formed in the back side of said link plate and inserted into said horizontal bar, and fixed thereby; and

said release lever comprises:

a lever main body having a length along the left to right direction;

a rotation hole formed in the right side of said lever main body;

a stopping threshold formed in the left side of said lever main body; and

a pressing plate formed in the left side of said lever main body and being pressed by said button unit, wherein

said pressing plate is disposed above said rotation hole, and

said stopping threshold is disposed below said rotation hole, and

said ratchet comprises:

a ratchet main body wherein said rotation hole is formed;

V-shaped ridge formed in the lower side of said ratchet main body and being contacted with said V-shaped groove; and

a stopping protrusion formed in the upper side of said ratchet main body and held in said stopping threshold.

9. The headrest folding device according to claim 1 ,

wherein

a bumper is further installed in said main bracket so as to be in contact with said horizontal bar of said stay when said stay is in the upright position.