Title:
Head Rest Having Rotary Wing
Kind Code:
A1


Abstract:
The present invention relates to a headrest having a rotary wing. The headrest includes a rotary shaft installed in a seat; a wing unit having a outer casing for receiving the rotary shaft therein; a locking unit for locking the wing unit to the seat; and a return spring for returning the wing unit to an original position of the wing unit. The headrest has a simple construction for rotating the wing unit, which thus reduces the production cost of the headrest.



Inventors:
Park, Moo Hwan (Seoul, KR)
Application Number:
12/160189
Publication Date:
01/01/2009
Filing Date:
01/03/2007
Primary Class:
International Classes:
A47C7/36
View Patent Images:
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Primary Examiner:
MCPARTLIN, SARAH BURNHAM
Attorney, Agent or Firm:
HYUN JONG PARK (Milford, CT, US)
Claims:
1. A headrest having a rotary wing, comprising: a rotary shaft installed in a seat body; a wing unit having a outer casing for receiving the rotary shaft therein; a locking unit for locking the wing unit to the seat body; and a return spring for returning the wing unit to an original position of the wing unit.

2. A headrest having a rotary wing, comprising: a rotary shaft installed in a seat body; a wing unit having a outer casing for receiving the rotary shaft therein; a clutch, which engages with or disengages from the wing unit, a locking unit for locking the clutch to the seat body; and a return spring for returning the wing unit to an original position of the wing unit.

3. The headrest having the rotary wing according to claim 2, wherein the clutch comprises a responder, which detects shocks and causes the clutch to engage with or disengage from the wing unit.

4. The headrest having the rotary wing according to claim 1, wherein the locking unit comprises a protrusion; the wing unit comprises a guide groove, which receives the protrusion therein, and a locking groove, which has a height higher than the guide groove and communicates with the guide groove; and the rotary shaft comprises a bore, which receives the locking unit therein, and a longitudinal guide slot, which communicates with the bore and receives the protrusion therein, wherein an upper spring is provided on the locking unit, and a push member is provided on the upper spring, and a lower spring is provided below the locking unit.

5. The headrest having the rotary wing according to claim 1, wherein the seat body comprises: a body; a middle seat part mounted to an upper end of the body; and a connection unit for connecting the middle seat part to the body, wherein the connection unit comprises: a connection frame; a connection body installed on the connection frame and connected to the middle seat part, a spring provided on a side of the connection body; and a support unit for supporting the spring.

6. The headrest having the rotary wing according to claim 2, wherein the seat body comprises: a body; a middle seat part mounted to an upper end of the body; and a connection unit for connecting the middle seat part to the body, wherein the connection unit comprises: a connection frame; a connection body installed on the connection frame and connected to the middle seat part, a spring provided on a side of the connection body; and a support unit for supporting the spring.

Description:

TECHNICAL FIELD

The present invention relates, in general, to headrests having rotary wings and, more particularly, to a headrest having a rotary wing, which includes a wing unit having a outer casing to receive a rotary shaft therein, a locking unit to lock the wing unit to a seat body, and a return spring to return the wing unit to the original position of the wing unit, thus having a simple construction for rotating the wing unit and reducing the production cost of the headrests.

BACKGROUND ART

An example of conventional vehicle seats is found in Korean Utility Model Laid-open publication No. 1998-37917.

A seatback frame is arranged in a seatback and supports the seatback. A side headrest is eccentrically installed on the upper surface of the seatback at a position adjacent to a main headrest. At the upper end of the side headrest, a stay, which has an adjusting knob and extends along an eccentric hole of the side headrest, is secured to the seatback frame.

A gear is connected to the lower end of the stay, which is secured to the seatback frame, such that the gear can be rotated in the same direction when the adjusting knob is manipulated. Further, a geared bracket is installed at a predetermined location, at which the geared bracket engages with and is operated in conjunction with the gear by simple manipulation of the adjusting knob, in other words, at a location adjacent to the fixed position of the stay relative to the seatback frame.

Further, when a passenger, who has leaned his/her head backwards against the headrest of a back seat while a vehicle is driven, wants to assume a more comfortable sitting and leaning posture, the passenger may rotate counterclockwise the adjusting knob, which is installed on the eccentric shaft of the side headrest parallel to the upper surface of the seatback. In the above state, the gear, which is connected to the lower end of the stay, engages with the gear of the seatback frame, and thus the two gears are rotated in conjunction with each other. Therefore, the outside end of the side headrest is slowly rotated toward the front seat, so that the passenger, who sits in the back seat, can adjust the angle of the side headrest to a desired angle and can fix the side headrest at the adjusted angle prior to using the side headrest as a headrest.

However, the headrest of the above-mentioned vehicle seat can support the head of a passenger when the passenger leans his/her head to one side. Further, when two side headrests are provided on opposite sides of a vehicle seat and a shock is applied to the vehicle seat, the two side headrests may not efficiently absorb the shock, and instead may injure the head of the passenger.

Further, when the shock is applied to a passenger while the passenger leans his/her head on a side headrest, the passenger knocks his/her head against the side headrest, thus his/her head is easily wounded.

Further, the conventional side headrest has a complex mounting structure, thus being heavy and increasing the production cost of the headrests.

DISCLOSURE

Technical Problem

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a headrest having a rotary wing, which includes a wing unit having a outer casing to receive a rotary shaft therein, a locking unit to lock the wing unit to a seat body, and a return spring to return the wing unit to the original position of the wing unit, thus having a simple construction for rotating the wing unit and reducing the production cost of the headrest.

Technical Solution

In order to accomplish the above object, in an aspect, the present invention provides a headrest having a rotary wing, comprising: a rotary shaft installed in a seat body; a wing unit having a outer casing for receiving the rotary shaft therein; a locking unit for locking the wing unit to the seat body; and a return spring for returning the wing unit to the original position of the wing unit.

According to the above-mentioned construction, the present invention has a simple construction for rotating the wing unit of the headrest, thus reducing the production cost of headrests.

In another aspect, the present invention provides a headrest having a rotary wing, comprising: a rotary shaft installed in a seat body; a wing unit having a outer casing for receiving the rotary shaft therein; a clutch, which engages with or disengages from the wing unit; a locking unit for locking the clutch to the seat body; and a return spring for returning the wing unit to the original position of the wing unit. Thus, in a state of emergency, the wing unit can be opened to prevent a passenger from being injured.

In the headrest, the clutch may comprise a responder, which detects a shock and causes the clutch to engage with or disengage from the wing unit. Thus, when an impact is applied to the seat, the wing unit can be automatically opened to prevent a passenger from being injured.

The locking unit may comprise a protrusion; the wing unit may comprise a guide groove, which receives the protrusion therein, and a locking groove, which has a height higher than the guide groove and communicates with the guide groove; and the rotary shaft may comprise a bore, which receives the locking unit therein, and a longitudinal guide slot, which communicates with the bore and receives the protrusion therein, wherein an upper spring is provided on the locking unit, and a push member is provided on the upper spring, and a lower spring is provided below the locking unit. Thus, the locking unit has a simple construction, so that the present invention can easily release the wing unit or the clutch from a locked state. Further, the locking unit is installed on the rotary shaft, thus realizing a headrest having a compact construction.

In the headrest, the seat comprises: a seat body; a middle body part mounted to the upper end of the body; a connection unit for connecting the middle body part to the body, a spring provided at one side of the connection unit; and a support unit for supporting the spring. The present invention efficiently absorbs shocks which are applied to the headrest, thus preventing a passenger from being injured.

ADVANTAGEOUS EFFECTS

The headrest having a rotary wing according to the present invention is advantageous for the following reasons.

The headrest comprises the rotary shaft installed in the seat body, the wing unit having the outer casing for receiving the rotary shaft therein, the locking unit for locking the wing unit to the seat, and the return spring for returning the wing unit to its original position. Thus, the headrest has a simple construction for rotating the wing unit and thus reduces the production cost of headrests.

Further, when the headrest of the present invention is used in seats of buses, trains or airplanes, in which case passengers must sit in the seats for a lengthy period of time, the headrests enable the passengers to sleep comfortably.

The headrest of the present invention includes the clutch, which engages with or disengages from the wing unit, and the locking unit for locking the clutch to the seat body. Thus, in a state of emergency, the wing unit can be opened to prevent a passenger from being injured.

Further, the clutch includes the responder, which detects shocks and causes the clutch to engage with or disengage from the wing unit, so that, when an impact is applied to the seat, the wing unit can be automatically opened to prevent a passenger from being injured.

The locking unit includes the protrusion, while the wing unit includes the guide groove, which receives the protrusion therein, and the locking groove, which is higher than the guide groove and communicates with the guide groove. Further, the rotary shaft includes the bore, which receives the locking unit therein, and the longitudinal guide slot, which communicates with the bore and receives the protrusion therein. Further, the upper spring is provided on the locking unit, the push member is provided on the upper spring, and the lower spring is provided below the locking unit. Due to the simple construction of the locking unit, the present invention can easily release the wing unit or the clutch from a locked state. Further, the locking unit, which is installed on the rotary shaft, permits the compact construction of the headrest.

Further, the headrest includes a spring, which is provided on one side of the connection body, and a support unit for supporting the spring, so that the present invention can efficiently absorb impacts applied to the middle seat part, thus preventing a passenger from being injured.

Further, when a passenger sleeps, the wing unit may be rotated to support the head of the passenger. Further, the middle seat part and the wing unit may move leftwards or rightwards at the same time, thus enabling the passenger to assume a natural leaning posture, and thus sleep comfortably.

The headrest includes both a nut part, which is provided in a connection frame to be placed outside the support unit, and a bolt, which is threaded to the nut part, so that the headrest can appropriately control the elasticity of springs and more efficiently absorb shocks.

Further, the headrest has both a vertical part, which is installed on the connection body such that it is placed between the connection body and the support unit. In addition, a damping material is provided in the space between the support unit and the vertical part, so that the headrest dampens shocks and thus more stably and efficiently absorbs shocks.

DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view illustrating a coupling structure of a middle seat part and a wing unit according to a second embodiment of the present invention;

FIG. 2 is a longitudinal sectional view of FIG. 1;

FIG. 3 is a cross-sectional view schematically illustrating the operation of the coupling structures shown in FIG. 1;

FIG. 4 is a cross-sectional view schematically illustrating the operation of coupling structures of a middle seat part and a wing unit according to a first embodiment of the present invention;

FIG. 5 is a longitudinal sectional view illustrating the coupling structure shown in FIG. 4;

FIG. 6 is a cross-sectional view schematically illustrating another operation of the coupling structure shown in FIG. 4;

FIG. 7 is a longitudinal sectional view illustrating a coupling structure of a middle seat part and a wing unit according to a third embodiment of the present invention;

FIG. 8 is a cross-sectional view schematically illustrating the operation of the coupling structures shown in FIG. 7;

FIG. 9 is a longitudinal sectional view illustrating a coupling structure of a middle seat part and a wing unit according to a fourth embodiment of the present invention;

FIG. 10 is a cross-sectional view schematically illustrating the operation of the coupling structures shown in FIG. 9;

FIG. 11 is a sectional view illustrating a connection unit according to a preferred embodiment of the present invention; and

FIG. 12 is a sectional view illustrating a connection unit according to another embodiment of the present invention.

BEST MODE

Hereinbelow, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the embodiments of the present invention, for a description of members the same as those in the related art, reference is to be made to the description of the related art, and additional description thereof is omitted.

FIG. 1 is an exploded perspective view illustrating a coupling structure of a middle seat part and a wing unit according to a second embodiment of the present invention. FIG. 2 is a longitudinal sectional view of FIG. 1. FIG. 3 is a cross-sectional view schematically illustrating the operation of the coupling structures shown in FIG. 1.

FIG. 4 is a cross-sectional view schematically illustrating the operation of coupling structures of a middle seat part and a wing unit according to a first embodiment of the present invention. FIG. 5 is a longitudinal sectional view illustrating the coupling structure shown in FIG. 4. FIG. 6 is a cross-sectional view schematically illustrating another operation of the coupling structure shown in FIG. 4.

FIG. 7 is a longitudinal sectional view illustrating a coupling structure of a middle seat part and a wing unit according to a third embodiment of the present invention. FIG. 8 is a cross-sectional view schematically illustrating the operation of the coupling structures shown in FIG. 7.

FIG. 9 is a longitudinal sectional view illustrating a coupling structure of a middle seat part and a wing unit according to a fourth embodiment of the present invention. FIG. 10 is a cross-sectional view schematically illustrating the operation of the coupling structures shown in FIG. 9.

FIG. 11 is a sectional view illustrating a connection unit according to a preferred embodiment of the present invention. FIG. 12 is a sectional view illustrating a connection unit according to another embodiment of the present invention.

As shown in FIG. 1 through FIG. 12, the seat for vehicles according to a preferred embodiment of the present invention comprises a seat body and a headrest having a rotary wing. The headrest includes a rotary shaft 230, 330, 430, 530, which is mounted in the seat body, a wing unit 260, 360, 460, 560, which has a outer casing that is fitted over the rotary shaft 230, 330, 430, 530, a locking unit 220, 320, 420, 520, which locks the wing unit 260, 360, 460, 560 to the seat body, and a return spring 250, 350, 450, 550, which returns the wing unit 260, 360, 460, 560 to its original position.

The seat body comprises the body 100 and a middle seat part 210, 310, 410, 510, which is mounted to the upper end of the body 100.

The connection unit, which connects the middle seat part 210, 310, 410, 510 to the body 100, comprises a connection frame 170, 670, a connection body 150, 650, which is installed in the connection frame 170, 670 and is connected to the middle seat part 210, 310, 410, 510, a spring 160, 660, which is provided at a side of the connection body 150, 650, and a support unit 130, 630, which supports the spring 160, 660.

The connection frame 170, 670 is provided in the upper part of the body 100, and defines therein a space. The connection body 150, 650, the spring 160, 660, and the support unit 130, 630 are received in the space of the connection frame 170, 670, so that the connection unit of the middle seat part 210, 310, 410, 510 is configured as a module.

The connection body 150, 650 is installed in the connection frame 170, 670 and is connected to the middle seat part 210, 310, 410, 510.

The connection frame 170, 670 is provided on each side of the upper part of the connection body 150, 650 and is connected to the middle seat part 210, 310, 410, 510. The connection body 150, 650 is provided with a slit, which movably receives the connection frame 170, 670 therein such that the connection body 150, 650 can move leftwards or rightwards.

The spring 160, 660 is provided on each side of the connection body 150, 650.

The support unit 130, 630 is provided outside the spring 160, 660 and supports the spring 160, 660.

The support unit 130, 630 comprises a front wall 134, 634, which contacts the spring 160, 660, a rear wall 132, 632 and a connection wall 133, 633, which connects the front wall 134, 634 to the rear wall 132, 632.

Further, the headrest includes a nut part 110, which is installed in the connection frame 170, 670 and is placed outside the support unit 130, 630, and a bolt 120, which is threaded to the nut part 110.

The nut part 110 is configured as a plate part, and has a through hole, which is formed through the center of the nut part 110 and is internally threaded.

The bolt 120 comprises a bolt head part and a threaded shank part, which is externally threaded and engages with the through hole of the nut part 110.

Further, a vertical part 141, 641 is provided in the connection body 150, 650 at a position between the connection body 150, 650 and the support unit 130, 630. A damping material 131, 631 is provided in a space between the support unit 130, 630 and the vertical part 141, 641.

The vertical part 141, 641 is placed in the support unit 130, 630 and is connected to the connection body 150, 650 through the connection part 142, 642.

The connection part 142, 642 passes through the front wall 134, 634 of the support unit and moves along with the connection body 150, 650.

The damping material 131, 631, which is charged in the support unit 130, 630, preferably comprises a viscous fluid, and dampens vibrations applied to the connection body 150, 650.

Thus, when shocks are applied to the head of a passenger, who leans on the headrest, in which the wing unit 260, 360, 460, 560 of the middle seat part 210, 310, 410, 510 has been rotated and supports the passenger's head, both the connection body 150, 650 and the vertical part 141, 641 move in the impact direction, in which the wing unit 260, 360, 460, 560 and the middle seat part 210, 310, 410, 510 are impacted.

In the above state, the connection body 150, 650, which is elastically supported by the spring 160, 660, absorbs the shock and vibrates. The vibration of the spring 160, 660 is dampened by the damping material 131, 631, so that the shock is more efficiently absorbed.

Further, the interval between the support unit 130, 630 and the connection body 150, 650 can be adjusted by rotating the bolt 120 in either direction, so that it is possible to adjust the elasticity of the spring 160, 660, which biases the connection body 150, 650.

The rotary shaft 230, 330, 430, 530 is installed at each side of the seat. The rotary shaft may be installed on the middle seat part 210, 310, as shown in the drawings of the first embodiment and the second embodiment, or may be installed on the body 100, as shown in the drawings of the third embodiment and the fourth embodiment.

The rotary shaft 230, 330, 430, 530 is provided with a bore to receive the locking unit 220, 320, 420, 520 therein, with two longitudinal guide slots 231, 232, 331, 332, 431, 531 formed in the sidewall of the rotary shaft in vertical directions such that the guide slots receive the protrusions 221, 321, 421, 521 and communicate with the bore.

The outer casing of the wing unit comprises a hollow part, and may be directly fitted over the rotary shaft 430, 530 to surround the rotary shaft 430, 530, as shown in the drawings of the third embodiment and the fourth embodiment. Alternatively, the outer casing of the wing unit, which comprises the hollow part, may be indirectly fitted over the rotary shaft 230, 330, such that a clutch is interposed between the rotary shaft 230, 330 and the outer casing, as shown in the drawings of the first embodiment and the second embodiment.

The wing unit 260, 360, 460, 560 may be formed outside the outer casing, as shown in the drawings of the first embodiment and the second embodiment, or may be formed on the upper part of the outer portion of the outer casing, as shown in the drawings of the third embodiment and the fourth embodiment, thus supporting the head of a passenger.

The locking unit 220, 320, 420, 520 locks the wing unit 260, 360, 460, 560 to the seat body, thus maintaining the position of the wing unit 260, 360, 460, 560 relative to the seat body.

The locking unit 220, 320, 420, 520 may be configured as one of a variety of structures. In the embodiments, the locking unit 220, 320, 420, 520 is configured as a cylindrical member, which is axially received in the bore of the rotary shaft 230, 330, 430, 530 with a protrusion 221, 321, 421, 521 and a second protrusion 222, 322, 422, 522 externally provided on the side surface of the locking unit 220, 320, 420, 520.

The second protrusion 222, 322, 422, 522 is received in a second longitudinal guide slot 232, 332, and thus enables the locking unit 220, 320, 420, 520 to move in the rotary shaft 230, 330, 430, 530 in a vertical direction while maintaining horizontally.

The protrusion 221, 321, 421, 521 passes through a first longitudinal guide slot 231, 331, 431, 531 of the rotary shaft, while the second protrusion 222, 322, 422, 522 is inserted into the second longitudinal guide slot 232, 332, which is formed on the rotary shaft at a position diametrically opposite the first longitudinal guide slot 231, 331, 431, 531.

The protrusion 221, 321, 421, 521 is longer than the second protrusion 221, 321, 421, 521.

The outer casing of the wing unit is provided with a guide groove 246, 361, which receives the protrusion 221, 321, 421, 521 therein, and a locking groove 242, 362, 446, 563, which has a height higher than the guide groove 246, 361 and communicates with the guide groove 246, 361.

The locking groove 242, 362, 446, 563 is formed at an end of the guide groove 246, 361.

In the second embodiment and the fourth embodiment of the present invention, both the locking groove 362, 563 and the guide groove 361 are formed in the outer casing. Meanwhile, in the first embodiment and the third embodiment, both the locking groove 242, 446 and the guide groove 246 are formed in the clutch.

At the upper part of the locking unit 220, 320, 420, 520, an upper spring 225, 325, 425, 525 is provided. A push member 224, 324, 424, 524 is installed on the top of the upper spring 225, 325, 425, 525. At the lower part of the locking unit 220, 320, 420, 520, a lower spring 228, 328, 428, 528 is provided.

A support step 229, 429, 529 is provided on the inner surface of the hollow rotary shaft 230, 330, 430, 530 to stop and support the lower spring 228, 328, 428, 528.

Further, to more efficiently transmit the pushing force of the push member 224, 324, 424, 524, a transmission member 226, 326, 426, 526 is placed below the upper spring 225, 325, 425, 525.

The transmission member 226, 326, 426, 526 may be configured as a block body or as a frame having an I-shaped cross-section.

A ball 227, 327, 427, 527 is placed below the transmission member 226, 326, 426, 526, so that, even if a user eccentrically pushes the push member 224, 324, 424, 524, the pushing force can be efficiently transmitted to the locking unit 220, 320, 420, 520.

The clutch engages with or disengages from the wing unit 260, 360, 460, 560. When the clutch engages with the wing unit 260, 360, 460, 560, the clutch is rotated along with the wing unit 260, 360, 460, 560 and is locked by the locking unit 220, 320, 420, 520.

When the clutch is locked as described above, the wing unit 260, 360, 460, 560 is locked at the same time.

The clutch includes a responder, which detects impact and enables the clutch to engage with or disengage from the wing unit 260, 360, 460, 560 in response to the detected impact.

The responder comprises a sensor, which detects impact, and an actuating pin. In response to a signal output from the sensor, the responder actuates the actuating pin to make the clutch engage with or disengage from the wing unit 260, 360, 460, 560, so that the clutch may engage with or disengage from the wing unit 260, 360, 460, 560.

The clutch comprises a first transmission unit 270, 370, 470, 570, a second transmission unit 280, 380, 480, 580, which is received in the first transmission unit 270, 370, 470, 570, and a third transmission unit 290, 390, 490, 590, which is received in the second transmission unit 280, 380, 480, 580. The clutch further comprises a fourth transmission unit 240, 340, 440, 540, which may be received in the third transmission unit 290, 390, 490, 590 in the same manner as that described for the first embodiment and the second embodiment, or which may surround the first transmission unit 270, 370, 470, 570 in the same manner as that described for the third embodiment and the fourth embodiment.

The responder according to the embodiments comprises a plurality of block 272, 275, 292, 295, 372, 375, 392, 395, 472, 475, 493, 495, 593, 572, 575, 595, and a plurality of springs 273, 275, 292, 295, 373, 376, 393, 396, 473, 476, 492, 496, 573, 574, 592, 595 to elastically support the block 272, 275, 292, 295, 372, 375, 392, 395, 472, 475, 493, 495, 593, 572, 575, 595.

The first transmission unit 270, 370, 470, 570 is provided with a first slot 271, 371, 471, 571, while the outer casing of the wing unit or the fourth transmission unit 240, 340, 440, 540 is provided with a first hole at a position corresponding to the first slot 271, 371, 471, 571.

The first transmission unit 270, 370, 470, 570 is also provided with a second slot 274, 374, 474, 576, while the second transmission unit 280, 380, 480, 580 is provided with a second hole at a position corresponding to the second slot 274, 374, 474, 576.

The first slot 271, 371, 471, 571 and the second slot 274, 374, 474, 576 are aligned in one straight line.

The third transmission unit 290, 390, 490, 590 is provided with a third slot 291, 391, 491, 591, while the outer casing of the wing unit or the fourth transmission unit 240, 340, 440, 540 is provided with a third hole at a position corresponding to the third slot 291, 391, 491, 591.

The third transmission unit 290, 390, 490, 590 is also provided with a fourth slot 294, 394, 496, 596, while the outer casing of the wing unit or the fourth transmission unit 240, 340, 440, 540 is provided with a fourth hole at a position corresponding to the fourth slot 294, 394, 496, 596.

The third slot 291, 391, 491, 591 and the fourth slot 294, 394, 496, 596 are aligned in one straight line, while the third slot 291, 391, 491, 591 and the fourth slot 294, 394, 496, 596 are aligned in another straight line, which is at an angle of 90 degrees with the straight line of the first slot 271, 371, 471, 571 and the second slot 274, 374, 474, 576.

Because the slots are formed on the transmission units at positions with the above-mentioned angular difference, the clutch can be separated from the wing unit 260, 360, 460, 560 no matter which direction a shock is applied from.

The slots and the holes, which correspond to each other, receive block 272, 275, 292, 295, 372, 375, 392, 395, 472, 475, 493, 495, 593, 572, 575, 595, with springs 273, 275, 292, 295, 373, 376, 393, 396, 473, 476, 492, 496, 573, 574, 592, 595 seated in the slots to elastically bias the block 272, 275, 292, 295, 372, 375, 392, 395, 472, 475, 493, 495, 593, 572, 575, 595.

A protrusion 241, 341, 441, 541 protrudes downwards from the lower end of the fourth transmission unit 240, 340, 440, 540. An arcuate guide groove 211, 311, 411, 511, which has a central angle of 90 degrees, is formed on a guide unit of the seat body, and receives the protrusion 241, 341, 441, 541 therein.

In the first embodiment and the second embodiment, the fourth transmission unit 240, 340 is provided with an upper flange 244, 344 and a lower flange 243, 343.

The upper flange 244, 344 supports the first transmission unit 270, 370, the second transmission unit 280, 380, and the third transmission unit 290, 390.

The lower flange 243, 343 is provided with the protrusion 241, 341 on a lower end thereof, and is furnished with teeth 245, 345 around the circumferential surface thereof.

In the third embodiment and the fourth embodiment, a lower flange 443, 543 is formed on the inner surface of the fourth transmission unit 440, 540. The lower flange 443, 543 is furnished with teeth 445, 545 around the circumferential surface thereof, and is provided with a protrusion 441, 541 on a lower end thereof.

The return spring 250, 350, 450, 550 elastically returns the wing unit 260, 360, 460, 560 to its open state.

The return spring 250, 350, 450, 550 is a torsion spring, in which the fixed end 251 of the return spring is fixed to the guide unit, while the movable end 252 of the return spring is stopped by the outer casing of the wing unit 260, 360, 460, 560 and is rotated along with the wing unit.

The middle seat part 210, 310, 410, 510 or the connection body 150, 650 is provided with a motor to automatically rotate the wing unit 260, 360, 460, 560.

The motor is provided with a gear, which engages with the teeth 245, 345, 445, 545, thus rotating the fourth transmission unit 240, 340, 440, 540 and rotating the wing unit 260, 360, 460, 560 at an angle of 90 degrees.

When the motor is installed in the connection body 150, 650, the connection frame 170, 670 is used as the rotary shaft 230, 330, 430, 530 and both the nut part and the bolt may be removed, as shown in FIG. 12.

Further, the headrest may further comprise an unlocking unit, in which a switch is manipulated instead of the clutch to push the transmission member 226, 326, 426, 526, or a push member 224, 324, 424, 524 is manipulated to unlock the locking unit,

Thus, when an impact is applied, a passenger may directly open the wing unit 260, 360, 460, 560.

Further, the headrest may comprise an impact sensor, and thus the locking unit may be automatically unlocked even if a passenger does not manipulate the switch.

Hereinbelow, the operation of the embodiments of the present invention will be described.

As shown in FIG. 5, in a normal state (a) of the first embodiment, the wing unit 260 is in an opened state. When a passenger wants to use the wing unit 260 for sleeping, the passenger rotates the wing unit 260 at an angle of 90 degrees.

When the wing unit 260 is rotated as described above, the clutch, which is coupled to the wing unit 260, is rotated along with the wing unit 260. Thus, the protrusion 221 is inserted into the guide groove 246 of the fourth transmission unit 240 and is rotated along the guide groove 246. When the protrusion 221 has been rotated at an angle of 90 degrees, the protrusion 221, which is biased upwards by the lower spring 228, is inserted into the locking groove 242, so that the wing unit 260 is locked to the clutch.

When an external shock is applied to the wing unit 260 in the above state, the block 272, 275 are retracted inwards from the first slot 271 and the second slot 274 due to the shock.

When the block 272, 275 are retracted during the impact state (c), as described above, the block 272, 275, which have functioned as pins for locking the wing unit 260 to the clutch, are removed from the outer casing, so that the wing unit 260 is separated from the clutch.

When an external shock is applied to the headrest in the opposite direction, the block 272, 275 are retracted inwards from the third slot 291 and the fourth slot 294, so that the wing unit 260 is separated from the clutch.

As described above, the clutch is fabricated with a plurality of transmission units, which are coupled to each other using the block 272, 275 and the springs 273, 276, so that, regardless of the direction from which a shock is applied to the headrest, the wing unit 260 can be reliably opened.

Further, the protrusion 221 is locked to the locking groove 242 of the fourth transmission unit 240, so that, even if a passenger does not push the push member 224, the wing unit 260 can be returned to its open state by the return spring 250.

Meanwhile, when a passenger pushes the push member 224 to open the wing unit 260 and thus change the state of the wing unit 260 from the usage state (b) to the normal state (a), the pushing force is transmitted to the locking unit 220 through the transmission member 226 and the ball 227. Due to the transmitted pushing force, the protrusion 221 moves downwards along the first longitudinal guide slot 231.

When the push member 224 is released from the pushing force, the push member 224 is returned to its original position by the upper spring 225.

Thus, the locked state is released and the wing unit 260 is returned to its open state by the return spring 250.

However, as shown in FIG. 6, the initial state of the wing unit 260 may be set to a position at which the wing unit 260 has been rotated at an angle of 90 degrees.

In a normal state, the wing unit 260, which has the initial state at the position rotated at the angle of 90 degrees and is used in a back seat, is oriented backwards in the body 100. When a passenger wants to change the state of the wing unit 260 to the usage state (b) to support his/her head, the wing unit 260 is rotated forwards at an angle of 90 degrees. When a shock is applied to the headrest, the wing unit 260 is opened.

As shown in FIG. 3, in a normal state, the wing unit 360 of the second embodiment is in a 180 degree closed position. In the above state, the protrusion 321 is locked to the locking groove 362 of the outer casing, and the wing unit 360 is maintained in the 180 degree closed position.

When a passenger, who wants to use the wing unit 360, pushes the push member 324, the protrusion 321 moves downwards and is released from the locking groove 362. Thereafter, the protrusion 321 is moved along the guide groove 361 of the outer casing by the restoring force of the return spring 350.

In the embodiments, the central angle of the guide groove 361 is preferably set at an angle of 180 degrees. Further, the central angle of the second longitudinal guide slot 342, which is formed on the fourth transmission unit 340 such that the second longitudinal guide slot 342 becomes level with the first longitudinal guide slot 331 of the rotary shaft 330, is preferably set to an angle of 180 degrees. Thus, the first longitudinal guide slot 331 and the second longitudinal guide slot 342 do not disturb the vertical movement of the protrusion 321.

The protrusion 341 of the fourth transmission unit 340 is rotated along the guide groove 311 of the guide unit, which has a central angle of 90 degrees.

When the wing unit 360 has been rotated at an angle of 90 degrees, the protrusion 341 of the clutch is stopped by the guide groove 311, so that both the clutch and the wing unit 360 are maintained in the 90 degree rotated state, thus being put in the locked state, which is the usage state (b).

Further, when an external shock is applied to the wing unit 360, the wing unit 360 is put in the impact state (c). In the above state, the block 372, 375 are retracted in the same manner as that described for the first embodiment, and the block 372, 375, which have functioned as pins for connecting the wing unit 360 to the clutch, are retracted from the outer casing, so that the wing unit 360 is separated from the clutch.

In the above state, the guide groove 361 of the outer casing, so that the wing unit 360 is opened.

When the wing unit 360, which is closed at an angle of 180 degrees, is used in a front seat of a vehicle, the wing unit 360 in a nonuse state realizes a compact seat and thus does not obstruct a driver's field of vision.

As shown in FIG. 8, the wing unit 460 of the third embodiment in a normal state (a) is maintained in an opened state. When the wing unit 460 is put in a usage state (b), the wing unit 460 is rotated at an angle of 90 degrees and is maintained at this rotated position.

When a passenger rotates the wing unit 460 in the normal state (a) by hand, the clutch, which is coupled to the wing unit 460, is rotated, so that the protrusion 421 is inserted into and is rotated along the guide groove of the fourth transmission unit 440. When the protrusion 421 has been rotated along the guide groove of the fourth transmission unit 440 at an angle of 90 degrees, the protrusion 421 is stopped by the locking groove 446, so that both the clutch and the wing unit 460 are put in the locked state, that is, the usage state (b).

To prevent the outer casing of the wing unit from interfering with the rotation of the protrusion 421, the outer casing is provided with a longitudinal slot 463, which is leveled with the longitudinal guide slot 431 of the rotary shaft 430 and has a central angle of 90 degrees.

When an external shock is applied to the wing unit 460, the wing unit 460 is put in an impact state (c). In the above state, the block 472, 475 of the first and second slots 471 and 474 are retracted inwards by the shock.

When the block 472, 475 are retracted inwards as described above, the block 472, 475, which have functioned as pins for connecting the wing unit 460 to the clutch, are retracted from the outer casing, so that the wing unit 460 is separated from the clutch.

However, when an external shock is applied to the headrest in the opposite direction, the block 493, 495 of the third slot 491, 591 are retracted inwards due to the shock, so that the wing unit 460 is separated from the clutch.

The protrusion 421 is locked to the locking groove 446 of the fourth transmission unit 440, while the longitudinal slot 463 is formed in the outer casing to enable the free rotation of the protrusion 421. Thus, even if a passenger does not push the push member 424, the wing unit 460 can be returned to its opened state by the return spring 450.

Meanwhile, when a passenger pushes the push member 424 to open the wing unit 460 and thus change the state of the wing unit 460 from the usage state (b) to the normal state (a), the pushing force is transmitted to the locking unit 420 through both the transmission member 426 and the ball 427. Due to the transmitted force, the protrusion 421 moves downwards along the longitudinal guide slot 431, 463.

Thus, the locked state is released and the wing unit 460 is returned to its open state by the return spring 450.

As shown in FIG. 10, the wing unit 560 of the fourth embodiment in a normal state (a) is maintained in a 180 degree closed state. Further, the protrusion 521 is locked to the locking groove 563 of the outer casing, so that the wing unit 560 is maintained in the 180 degree closed state.

When a passenger pushes the push member 524 to use the wing unit 560, the protrusion 521 moves downwards and thus is removed from the locking groove 563. The protrusion 521 is moved along the guide groove of the outer casing by the restoring force of the return spring 550.

In the above state, the central angle of the guide groove is preferably set to 180 degrees, so that the guide groove does not interfere with the movement of the protrusion 521.

The protrusion 541 of the fourth transmission unit 540 is rotated along the guide groove 511 of the guide unit, which has a central angle of 90 degrees.

When the wing unit 560 has been rotated at the angle of 90 degrees, the protrusion 541 of the clutch is stopped by the end of the guide groove 511, so that both the wing unit 560 and the clutch are maintained at a 90 degree rotated state, thus being put in a locked state.

Further, when an external impact is applied to the wing unit 560, the block 572, 575 are retracted in the same manner as that described for the first embodiment. In the above state, the block 572, 575, which have functioned as pins for connecting the wing unit 560 to the clutch, are removed from the outer casing. Thus, the wing unit 560 is separated from the clutch.

In the above state, the protrusion 521 moves along the guide groove of the outer casing, which has a central angle of 180 degrees, so that the wing unit 560 is opened.

Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.