Headrest and vehicle seat provided with the same

A versatile and thin headrest can be tilted lightly and reliably from a head support state to a storage state by reducing an operation load. The headrest includes a support member mounted on the upper part of a backrest seat, a frame rotatably engaged with the support member, a frame urging element(s), and a lock mechanism provided between the frame and the support member. The lock mechanism includes locking members disposed on the support member and formed with engagement groove parts, a movable operation lever having concave parts formed directed toward the support member side, fixing members pivotally supported on the frame and capable of being crossingly engaged with and disengaged from the engagement groove parts along with the movement of the operation lever, and an operation lever urging element(s) for urging the operation lever so that the fixing members are urged in the direction of the engagement groove parts.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase of the International Patent Application No. PCT/JP2008/051879 filed Feb. 5, 2008, which claims the benefit of Japanese Application No. 2007-026169, filed Feb. 5, 2007, and Japanese Application No. 2007-026170, filed Feb. 5, 2007, the entire contents of which are incorporated herein by reference.

This application is also related to the subject matter of International Patent Application No. PCT/JP2008/051880 filed Feb. 5, 2008.

BACKGROUND

The present invention relates to a headrest and a vehicle seat provided with the headrest. More particularly, it relates to a headrest capable of being in a head support state in which the headrest is raised with respect to a backrest seat and being tilted from the head support state to a storage state, and a vehicle seat provided with the headrest.

Generally, on the upper part of a backrest seat of a vehicle seat, a headrest for protecting the passenger's head is mounted. Conventionally, there has been publicly known a technique in which the lower parts of a pillar of the headrest are attached to a transverse rod extending in the right-and-left direction in the backrest seat so as to be rotatable in the front-and-rear direction, the pillar is attached so as to be movable in the right-and-left direction, and the headrest is tilted to the rear and stored after being moved transversely (see Japanese Unexamined Utility Model Application Publication No. 7-11951 (“the '951 Publication”)).

Also, there has been proposed a technique in which a headrest includes a pillar having a transverse shaft part and mounted on the upper part of a seat back; a headrest main body the lower part side of which is rotatably provided in the transverse shaft part of the pillar; and a tilting mechanism incorporated in the headrest main body to tilt the headrest main body backward, and the tilting mechanism includes a headrest urging element(s) for urging the upper part of the headrest main body to the rear side; a lock plate provided on the transverse shaft part of the pillar and having a first locking part; a latch provided on the headrest main body and having a second locking part capable of being locked to the first locking part of the lock plate; a latch urging element(s) for urging the latch so as to lock the second locking part to the first locking part of the lock plate when the headrest main body is in a raised state in which the headrest main body is approximately vertical; and an actuator for unlocking the second locking part of the latch from the first locking part of the lock plate against the urging force of the latch urging element(s) (Japanese Unexamined Patent Application Publication No. 2005-349915 (“the '915 Publication”)).

Furthermore, there has been proposed a technique in which in a tiltable headrest in which a bracket can be moved between a folded position and an upright position, a concave part is formed in a lock reciprocating member and a lock member respectively, and the lock reciprocating member can be made slidable between a lock position and an unlock position by a spring (International Patent Publication WO2005/120894A1 (“the '894 Publication)).

The publicly known technique described in the '951 Publication has a problem in that because the rotation supporting point of the headrest is present in the upper part of the backrest seat under the headrest, the headrest rotates backward greatly together with the pillar and therefore the displacement thereof is large, so that the space occupied at the storage time is large.

That is to say, when the headrest is tilted to the rear, one headrest fully projects to the rear side of the backrest seat. Also, this technique has a problem in that a pillar movement grooves must be formed in the upper part of the backrest seat, so that the construction is complicated, and also the backrest seat cannot be used in common with another backrest seat.

The publicly known technique described in the '915 Publication has a problem in that although the entire of the tilting mechanism of the headrest can be accommodated in the headrest main body, and the headrest has excellent versatility, since the first locking part of the lock plate and the second locking part provided on the latch to be locked to the first locking part are used, the lock plate and the latch are arranged in the tiltable direction of the headrest, so that some degree of size must be secured in the front-and-rear direction, and therefore there is a limit to the thinning of the headrest.

In the publicly known technique described in the '894 Publication, the concave part is formed in the lock reciprocating member and the lock member respectively, and the lock reciprocating member can be made slidable between a lock position and an unlock position by the spring. However, since the lock position and the unlock position are switched over by two members of the lock reciprocating member and the lock member, a spring force urging the bracket toward the folding direction is directly applied to the lock reciprocating member and the lock member. Therefore, the reciprocating motion of the lock reciprocating member is sometimes difficult to perform smoothly. Also, in the case where a plurality of lock members are present, the lock reciprocating member and all of the lock members are made slidable between the lock position and the unlock position by one lock reciprocating member, so that the size of the lock reciprocating member increases, so that this headrest has a disadvantage that a greater load is applied to the lock reciprocating member.

SUMMARY

An object of the present invention is to provide a headrest that has excellent versatility and thin shape, and can be tilted lightly from a head support state to a storage state by reducing an operation load, and a vehicle seat provided with this headrest.

Also, another object of the present invention is to provide a headrest capable of reliably operating a lock mechanism for switching over the head support state and the storage state, and a vehicle seat provided with this headrest.

To solve the above problems, according to various embodiments of the invention discussed below, in the headrest capable of being in a head support state in which the headrest is raised with respect to a backrest seat and being tilted from the head support state to a storage state, the headrest includes a support member mounted on the upper part of the backrest seat; a frame engaged rotatably with the support member; a frame urging element(s) for urging the frame to one side; and a lock mechanism provided between the frame and the support member, and is characterized in that the lock mechanism includes a locking member disposed on the support member and formed with an engagement groove part; an operation lever having a concave part formed so as to be directed toward the support member side and being movable; a fixing member pivotally supported on the frame rotatably and disposed so as to be capable of being crossingly engaged with and disengaged from the engagement groove part of the locking member along with the movement of the operation lever; and an operation lever urging element(s) for urging the operation lever so that the fixing member is urged in the engagement groove part direction of the locking member.

Also, according to an embodiment of the invention, in the headrest capable of being in a head support state in which the headrest is raised with respect to a backrest seat and being tilted from the head support state to a storage state, the headrest includes a pillar having a transverse shaft part and mounted on the upper part of the backrest seat; a headrest frame rotatably engaged with the transverse shaft part of the pillar by combining a main frame and a sub frame; a headrest frame urging element(s) for urging the headrest frame to one side; and a lock mechanism provided between the headrest frame and the pillar, and is characterized in that the lock mechanism includes a latch plate disposed on the transverse shaft part of the pillar and formed with an engagement groove part along the transverse shaft part; a ratchet lever provided with an engagement concave part formed so as to be directed toward a pillar side and sliding in the transverse direction; a ratchet one end side of which is engaged with the engagement concave part of the ratchet lever and the other end side of which can be engaged crossingly with the engagement groove part of the latch plate; and a ratchet lever urging element(s) for urging the ratchet lever so that the ratchet is urged in the engagement groove part direction of the latch plate, the ratchet being switchable between an engagement position at which the ratchet is positioned in the engagement groove part of the latch plate, and a disengagement position at which the ratchet comes off the engagement groove part.

As described above, when the headrest is kept in the head support state in which the headrest is raised with respect to a backrest seat and is tilted from the head support state to the storage state as the lock mechanism, the operation lever (ratchet lever), the locking member (latch plate), and the fixing member (ratchet) are used, and the engagement position and the disengagement position are switched over via the fixing member (ratchet) one end side of which is engaged with the engagement concave part of the operation lever (ratchet lever) and the other end side of which can be engaged crossingly with the engagement groove part of the locking member (latch plate). Therefore, the lock mechanism itself can be configured so as to be compact without requiring a wide width.

In the above-described configuration, according to an embodiment of the invention, it is preferable that one end side of the fixing member be formed into a circular shape, and the operation lever hold the circular one end side of the fixing member and allow the rotation of the fixing member.

Also, in the above-described configuration, according to an embodiment of the invention, it is preferable that one end side of the ratchet held in the engagement concave part of the ratchet lever be formed into a circular shape, and the engagement position and the disengagement position can be switched over by the rotation of the ratchet along with the movement of the ratchet lever.

By making one end side of the fixing member (ratchet), which is held in the engagement concave part of the operation lever (ratchet lever), circular, one end side of the fixing member (ratchet) is turned smoothly in the engagement concave part of the operation lever (ratchet lever) along with the movement of the operation lever (ratchet lever). Therefore, the fixing member (ratchet) can be engaged with and disengaged from the engagement groove part of the locking member (latch plate), so that the lock can be released exactly.

In the above-described configuration, according to an embodiment of the invention, the configuration can be made such that the ratchet lever is formed with at least two engagement concave parts, and at least two ratchets are held in and engaged with the engagement concave parts. Thus, since the plurality of (at least two) ratchets are held in the engagement concave part of the ratchet lever, by the operation of the ratchet lever, all of the ratchets are moved simultaneously in synchronization, so that the ratchets can be prevented from moving while turning or not turning individually.

That is to say, since one end side of the ratchet is held in and engaged always with the engagement concave part of the ratchet lever, a state in which only one ratchet turns can be prevented. Further, the ratchet turns smoothly following the movement of the ratchet lever, malfunction is prevented, and the switching-over by the lock mechanism can be performed reliably.

In the above-described configuration, according to an embodiment of the invention, the configuration can be made such that by operating the ratchet lever against the ratchet lever urging element(s), the ratchet is taken away from the engagement groove part of the latch plate. Thus, at the normal time, the ratchet lever is urged in the direction such that the ratchet is engaged with the engagement groove part of the latch plate. Therefore, when the ratchet is taken away from the engagement groove part of the latch plate by operating the ratchet lever against the ratchet lever urging element(s), the headrest frame is tilted to the storage state by the headrest frame urging element(s). Therefore, the lock can be released by one operation (one action).

In the above-described configuration, according to an embodiment of the invention, it is preferable that a distance between the rotation axis of the ratchet and the position of one end side of the ratchet engaging with the engagement concave part of the ratchet lever be longer than a distance between the rotation axis of the ratchet and the position of the ratchet engaging with the engagement groove part of the latch plate. By this configuration, when the ratchet is turned from the engagement position at which the ratchet is positioned in the engagement groove part of the latch plate to the disengagement position at which the ratchet comes off the engagement groove part (when the lock is released), the ratchet can be moved with less force, so that the releasing load at the time when the lock is released can be decreased. That is to say, the link ratio can be set, and thereby the releasing load can be adjusted.

In the above-described configuration, according to an embodiment of the invention, the configuration is preferably made such that the ratchet rotates in the range of rotation angle of 20 to 40 degrees around the rotation axis of the ratchet. Thus, by making the configuration such that the ratchet rotates in the range of rotation angle of 20 to 40 degrees around the rotation axis of the ratchet, the transverse displacement of the ratchet lever for the disengagement caused by the turning of the ratchet from the engagement position to the disengagement position and the turning of the ratchet can be made optimum. Thus, the displacement relating to the operation caused by the lock mechanism can be adjusted.

To solve the above problems, according to an embodiment of the invention, in the vehicle seat provided with a headrest capable of being in a head support state in which the headrest is raised with respect to a backrest seat and being tilted from the head support state to a storage state, the vehicle seat is characterized in that the headrest includes a support member mounted on the upper part of the backrest seat; a frame engaged rotatably with the support member; a frame urging element(s) for urging the frame to one side; and a lock mechanism provided between the frame and the support member, and the lock mechanism includes a locking member disposed on the support member and formed with an engagement groove part; an operation lever having a concave part formed so as to be directed toward the support member side and being movable; a fixing member pivotally supported on the frame rotatably and disposed so as to be capable of being crossingly engaged with and disengaged from the engagement groove part of the locking member along with the movement of the operation lever; and an operation lever urging element(s) for urging the operation lever so that the fixing member is urged in the engagement groove part direction of the locking member.

In the above-described configuration, according to an embodiment of the invention, the configuration is preferably made such that one end side of the fixing member is formed into a circular shape, and the operation lever holds the circular one end side of the fixing member and allows the rotation of the fixing member.

Also according to the vehicle seat according to an embodiment of the invention, in the vehicle seat provided with a headrest capable of being in a head support state in which the headrest is raised with respect to a backrest seat and being tilted from the head support state to a storage state, the vehicle seat is characterized in that the headrest includes a pillar having a transverse shaft part and mounted on the upper part of the backrest seat; a headrest frame rotatably engaged with the transverse shaft part of the pillar by combining a main frame and a sub frame; a headrest frame urging element(s) for urging the headrest frame to one side; and a lock mechanism provided between the headrest frame and the pillar, the lock mechanism includes a latch plate disposed on the transverse shaft part of the pillar and formed with an engagement groove part along the transverse shaft part; a ratchet lever provided with an engagement concave part formed so as to be directed toward a pillar side and sliding in the transverse direction; a ratchet one end side of which is engaged with the engagement concave part of the ratchet lever and the other end side of which can be engaged crossingly with the engagement groove part of the latch plate; and a ratchet lever urging element(s) for urging the ratchet lever so that the ratchet is urged in the engagement groove part direction of the latch plate, the ratchet being switchable between an engagement position at which the ratchet is positioned in the engagement groove part of the latch plat, and a disengagement position at which the ratchet comes off the engagement groove part.

In the above-described configuration, according to an embodiment of the invention, the configuration is preferably made such that one end side of the ratchet held in the engagement concave part of the ratchet lever is formed into a circular shape, and the engagement position and the disengagement position can be switched over by the rotation of the ratchet along with the movement of the ratchet lever.

As described above, according to the above-described vehicle seat, a vehicle seat having the above-described headrest function can be provided.

According to embodiments of the invention, there can be provided a headrest that has excellent versatility and thin shape, and can be tilted lightly from a head support state to a storage state by reducing an operation load, and a vehicle seat provided with this headrest. Also, according to an embodiment of the invention, there can be provided a headrest capable of reliably operating a lock mechanism for switching over the head support state and the storage state, and a vehicle seat provided with this headrest.

According to embodiments of the invention, the lock mechanism itself can be configured so as to be compact without requiring a wide width. That is to say, the lock mechanism can be provided in a narrow headrest, so that the headrest can be tilted by a compact configuration. Also, the headrest in accordance with the present invention can be mounted on any type of backrest seat if the backrest seat can be mounted with the support member (pillar). Thus, the backrest seat need not be provided with a mechanism for tilting the headrest, so that the whole configuration can be simplified.

According to embodiments of the invention, the lock can be released exactly.

According to embodiments of the invention, the malfunction of the lock mechanism can be prevented, and switching-over can be performed reliably by the lock mechanism.

According to embodiments of the invention, the lock can be released by one operation (one action).

According to embodiments of the invention, a so-called link ratio can be set, and thereby the releasing load can be adjusted.

According to embodiments of the invention, the displacement relating to the operation can be adjusted.

According to embodiments of the invention, a vehicle seat provided with the headrest in accordance with the present invention can be provided.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will now be described with reference to the accompanying drawings. The members, arrangements, and the like explained below do not restrict the present invention, and needless to say, can be changed variously based on the teachings of the present invention as would be understood by one of ordinary skill in the art.

A vehicle seat S may be, e.g., a rear seat for an automobile. As shown inFIG. 1, the vehicle seat S includes a seating seat S1and a backrest seat S2, and a headrest HR is provided in the upper part of the backrest seat S2. The seating seat S1and the backrest seat S2have a publicly known configuration in which a frame, a pad, and a seat cover material for covering the frame and the pad are provided. The explanation of the details of this configuration is omitted. In this embodiment, the example of a rear seat for an automobile is shown. However, the vehicle seat S may be a front seat or an intermediate seat of vehicle if the seat is mounted with a headrest.

The headrest HR of this embodiment can be mounted on the backrest seat S2by using a pillar serving as a support member so as to be moved up and down. As a height adjusting mechanism for moving the headrest HR up and down, a publicly known mechanism can be used. Therefore, the explanation of this mechanism is omitted.

As shown inFIG. 1, the headrest HR of this embodiment can be tilted from a head support state in which the headrest HR is raised with respect to the backrest seat S2to a storage state (in the example shown inFIG. 1, the left-hand side in the figure shows the storage state).

The headrest HR of this embodiment includes, as main components, a pillar1serving as a support member, a headrest frame2serving as a frame, and a headrest frame urging element(s)3serving as a frame urging element(s), and a lock mechanism4.

As shown inFIGS. 3 and 9, the pillar1serving as a support member of this embodiment has two leg parts11,11mounted on the upper part of the backrest seat S2, and a transverse shaft part12connecting the two leg parts11,11to each other. To the transverse shaft part12of the pillar1, latch plates41and42serving as a locking member are fixed in the direction perpendicular to the axis of the transverse shaft part12by welding or the like at a predetermined interval. A portion between the latch plates41and42of the transverse shaft part12is rotatably held by substantially semicircular concave parts21aand22aformed in the lower part of a headrest frame2(a main frame21and a sub frame22) serving as a frame, described later.

The latch plates41and42of this embodiment constitute a part of the lock mechanism4, described later.

As shown inFIGS. 3 and 6, the headrest frame2serving as a frame of this embodiment is rotatably engaged with the transverse shaft part12of the pillar1as described above, and is configured by combining the sub frame22with the main frame21so that the sub frame22enters into the main frame21. In the headrest frame2consisting of the main frame21and the sub frame22, a ratchet lever44serving as an operation lever and a ratchets46serving as a fixing member are held. The main frame21and the sub frame22are assembled integrally by crimping from both external sides with rivets101and102being held therebetween. Also, the rivet101,102has a larger diameter in a central part101a,102a, and is formed with a caulking part101b,102bon both sides. The ratchet lever44and the ratchets46constitute the lock mechanism4, described later.

As shown inFIGS. 3 to 5, the main frame21of this embodiment consists of a rectangular plate body. The substantially semicircular concave part21ais formed in the lower part of the main frame21, a crimping part21bis formed continuously with the concave part21a, and a jutting-out part21gis formed on the upper side of the main frame21.

Also, at the outer periphery of the main frame21, a folded wall part21cis formed excluding a predetermined range on both sides of the concave part21a.

On the inside of the main frame21, boss parts21eare formed so as to project toward the inside in portions through which the rivet101serving as a rotation shaft for the ratchet46is inserted. Also, on the outer periphery side of each of the boss parts21e, a substantially bow-shaped protruding part21fprojecting toward the rotating surface of the ratchet46is formed.

On one side surface of the folded wall part21c, a cut-away part21dis formed. The ratchet lever44is inserted through this cut-away part21d. Also, on the extension of the cut-away part21d, three tongue pieces21h,21iand21jbent toward the inside are formed so as to serve as a movement guide when the ratchet lever44is inserted.

Among these three tongue pieces21h,21iand21j, the two tongue pieces21hand21jare formed spacedly in the right-and-left direction by being bent to the inside from the upside to the downside. In a substantially central portion between the tongue pieces21hand21jarranged in the right-and-left direction, one tongue piece21ibent to the inside from the lower side to the upper side is formed. The ratchet lever44is inserted with the end parts of the three tongue pieces21h,21iand21jbeing used as guides. The ratchet lever44of this embodiment constitutes a part of the lock mechanism4, described later.

As shown inFIGS. 3,6and7, the sub frame22of this embodiment consists of a rectangular plate body, and is configured in a shape such that the upper part thereof extending from a predetermined portion, in this example, a position at which the ratchet lever44is disposed, is offset to one side (the side distant from the cut-away part21d). In the lower part of the sub frame22, a substantially semicircular concave part22ais formed, and a crimping part22bis formed continuously with the concave part22a. Also, on the opposite side to the crimping part22b, an urge receiving part22kis formed continuously with the concave part22a. A folded part22cfolded to the inside is formed excluding the substantially semicircular concave part22aside, that is, on the upper side and the right and left sides.

On the sub frame22, boss parts22eare formed so as to project toward the inside at positions aligning with the boss parts21eof the main frame21, that is, in portions in which the rivet101serving as a rotation shaft for the ratchet46is inserted through.

Also, on the inside of the sub frame22, substantially bow-shaped protruding parts22fprojecting toward the rotating surface of the ratchet46are formed so as to align with the substantially bow-shaped protruding parts21fformed on the main frame21.

As shown inFIGS. 3 and 6, the headrest frame urging element(s)3serving as a frame urging element(s), which is used to urge the headrest frame2to one side (that is, the tilt side), is made up of a shaft31, a damper32, a spring33, shaft insertion holes41dand42dformed in the latch plates41and42constituting the lock mechanism4, and the aforementioned urge receiving part22k.

The shaft31is a round bar, and the damper32is formed by a hollow cylindrical body made of rubber. Also, the spring33is disposed so that one end33athereof is locked to the latch plate41and the other end33bside is in contact with the damper32, and is brought into contact with the aforementioned urge receiving part22kwith the other end33bthereof being used as a wide pressing part. By the urging, at the normal time, the headrest frame2is subjected to an urging force in the tilt direction.

Assembling is performed by inserting the shaft31through the two latch plates41and42. At this time, the shaft31is inserted through the shaft insertion hole41d(or42d) in one latch plate41(or42), and then the damper32and the spring33are put on the shaft31. Thereafter, the shaft31is inserted through the shaft insertion hole42d(or41d) in the other latch plate42(or41).

The symbol4shown inFIG. 7denotes the lock mechanism, which is provided between the pillar1and the headrest frame2.

The lock mechanism4of this embodiment includes, as main components, the latch plates41and42serving as a locking member, the ratchet lever44serving as an operation lever, the ratchets46serving as a fixing member, and a spring45serving as a ratchet lever urging element(s) (operation lever urging element(s)).

The latch plates41and42are fixed to the transverse shaft part12of the pillar1in the direction perpendicular to the axis of the transverse shaft part12by welding or the like at a predetermined interval as described above.

On the upper sides of the latch plates41and42, as shown inFIG. 9, engagement groove parts41aand42aare formed along the transverse shaft part12.

The latch plate41,42is formed with an arcuate outer periphery part41b,42band a stopper part41c,42cformed by a wall of a portion beyond the engagement groove part41a,42a.

In this embodiment, the latch plates41and42are formed so that the engagement groove parts41aand42ahave a different shape. The engagement groove part42aof the latch plate42provided on the right-hand side inFIG. 9is formed so that the width thereof on the upper end side is narrower, and the engagement groove part41aof the latch plate41provided on the left-hand side inFIG. 9is formed so that the groove width is constant in the up-and-down direction. On the end part side (the lower side inFIG. 9) of the latch plate41,42, a stopper part41e,42eis formed.

As for the configurations of the latch plates41and42, the engagement groove part42aof at least one latch plate (in this embodiment, the latch plate42) is formed so that the upper end side tilts to the inside with a portion somewhat wider than the thickness of the ratchet46being left. Therefore, the contact points of the latch plate42and the ratchet46are the upper end side of the engagement groove part42aof the latch plate42and a lock engagement part46cof the ratchet46shown inFIG. 11. The lock engagement part46c, which is the contact point, is a side surface position at the time when the ratchet46comes into contact with the groove bottom of the engagement groove part42aof the latch plate42. The symbol46dshown inFIG. 11denotes a locus formed by moving the ratchet46from a disengagement position at which the ratchet46comes off the engagement groove part42ato a position at which the ratchet46comes into contact with the groove bottom of the engagement groove part42aof the latch plate42.

That is to say, as shown inFIG. 7, the configuration is made such that the distance Z from the transverse shaft part12of the pillar1to a portion in which the upper end side of the latch plate42, which is formed so as to be narrower, comes into contact with the ratchet46is long as compared with any other portion of the ratchet46. Therefore, the contact point separates from the axis of the transverse shaft part12of the pillar1(the rotation center of the headrest frame2), so that when the ratchet46moves from the engagement position to the disengagement position (when the lock is released), a releasing load placed by the urging force of the headrest frame urging element(s)3(the spring33) from the rear can be decreased, and the adjustment of releasing load can be made. In the case of this embodiment, since the engagement groove part42aof the latch plate42located on the side engaging with an operation knob of the ratchet lever44is formed so as to be narrow, a force from the ratchet lever44can be transmitted reliably.

Also, the latch plate41,42is provided with the shaft insertion hole41d,42dfor inserting the shaft31.

As shown inFIG. 10, the ratchet lever44of this embodiment is formed by a slender plate body, and has a plate main body44asliding in the transverse direction. The plate main body44ais formed with engagement concave parts44b,44bdirected to the pillar1side. On the opposite side to the engagement concave parts44b,44b, a movement locking part44cis formed so as to extend from the plate main body44ain the substantially perpendicular direction, and the movement locking part44cis formed with a locking part44dfor the ratchet lever urging element(s)45.

The engagement concave parts44b,44bare formed between jutting-out parts44f,44fjutting out from the plate main body44ato the pillar1side so as to hold circular one end side of the ratchet46and to allow the ratchet46to rotate.

To the ratchet lever44, one end of the ratchet lever urging element(s) (spring)45is connected so that the ratchet46is urged in the engagement groove part direction of the latch plate41,42. The symbol44edenotes end part side engaging with the operation knob.

As shown inFIGS. 3,7and11, the ratchet46of this embodiment has a rotation hole46aserving as a rotation axis, an engagement part46b, and the lock engagement part46c, and is pivotally supported on the headrest frame2with the rivet101disposed between the main frame21and the sub frame22being used as a rotation shaft.

The engagement part46bon one end side of the ratchet46engages with the engagement concave part44b,44bof the ratchet lever44, and the lock engagement part46cengages with the engagement groove part41a,42aof the latch plate41,42, by which the raised state of the headrest HR is maintained.

The engagement part46bon one end side of the ratchet46engages with the engagement concave parts44b,44bof the ratchet lever44, and the surface touching the engagement concave part44b,44bis formed into a circular shape, preferably a complete round shape. Thereby, the ratchet46can be rotated following the movement of the ratchet lever44stably. The ratchet46has a thickness larger than that of the ratchet lever44. Therefore, the ratchet46can be prevented from coming off the ratchet lever44.

Also, as shown inFIG. 11, the ratchet46is formed so that the distance X1between the center of the rotation hole46aof the ratchet46and the center position of the engagement part46bon one end side of the ratchet46engaging with the engagement concave part44bof the ratchet lever44is longer than the distance Y1between the center of the rotation hole46aof the ratchet46and the position of the lock engagement part46con the other end side of the ratchet46engaging crossingly with the engagement groove part42aof the latch plate42(in the case ofFIG. 11, the engagement locus46d). Thereby, the releasing load at the time when the lock of the ratchet46to the latch plate41,42is released can be decreased.

That is to say, in this embodiment, in the raised state, the ratchet46pivotally supported on the headrest frame2is urged in the tilt direction by the spring33, so that friction is generated in a portion in which the ratchet46comes into contact with the engagement groove part42aof the latch plate42. Therefore, when the ratchet46is rotated from the engagement position at which the ratchet46is positioned in the engagement groove part42aof the latch plate42to the disengagement position at which the ratchet46comes off the engagement groove part42a, frictional resistance is exerted, so that a difficult-to-rotate state is formed.

However, the ratchet46of this embodiment is formed so that the distance X1between the center (supporting point) of the rotation hole46aand the center position (power point) of the engagement part46bto which a weight is applied by the ratchet lever44is longer than the distance Y1between the center (supporting point) of the rotation hole46aand the position (point of application) of the lock engagement part46cengaging crossingly with the engagement groove part42aof the latch plate42. Therefore, the ratchet46can be moved from the engagement position to the disengagement position with less force. That is to say, a so-called link ratio can be set, and thereby the releasing load can be adjusted.

Also, the ratchet lever44is configured so as to hold circular one end side of the ratchet46and to allow the ratchet46to rotate. Therefore, the engagement part46bon one end side of the ratchet46is held by and engages normally with the engagement concave part44bof the ratchet lever44, so that the ratchet46can be prevented from turning by one. That is to say, the ratchet46rotates smoothly following the movement of the ratchet lever44constantly, malfunction is prevented, and the switching-over by the lock mechanism4can be performed reliably.

The ratchet46of this example can rotate in the range of rotation angle of 20 to 40 degrees around the rotation hole (rotation axis)46a.

If the ratchet46is configured so as to turn in the range of rotation angle of 20 to 40 degrees around the rotation hole (rotation axis)46athereof, the displacement in the transverse direction of the ratchet lever44for the disengagement caused by the rotation of the latch plates41,42and the ratchet46from the engagement position to the disengagement position and the rotation of the ratchet46can be adjusted so as to be optimum. Thus, the displacement relating to the operation caused by the lock mechanism4can be adjusted.

FIG. 12shows an assembled state of a cover material7. After the pillar1serving as a support member, the headrest frame2serving as a frame, the headrest frame urging element(s)3serving as a frame urging element(s), the lock mechanism4, and the like have been assembled, these elements are covered with the cover material7. The cover material7consists of a front cover member7a, a rear cover member7b, and a seat cover fastening cover member7c, which are made of a resin, and a garnish7dfor preventing the operation knob of operation section and the like from coming off.

As shown inFIG. 2, a pad material8is disposed at the outer periphery of the cover material7, and a seat cover material9covers the pad material8.

The seat cover material9of this embodiment is formed into a bag shape one end side of which is open. Various members surrounded by the cover material7are mounted through the opening of the seat cover material9and are arranged in the cavity of a mold, resin foam is poured and expanded, and the seat cover terminal part on the opening side of the seat cover material9is covered by the seat cover fastening cover material7con the pillar1side, by which the headrest HR is integrally molded.

Next, the operation of the headrest HR configured as described above is explained.

Since the headrest HR is configured so that the headrest frame2is rotatably installed on the transverse shaft part12of the pillar1, and is fixed by the lock mechanism4, the headrest HR at the normal time can protect the seater's head when being subjected to a shock in a raised state.

That is to say, the pillar1mounted on the upper part of the backrest seat S2has the transverse shaft part12, and the transverse shaft part12of the pillar1is rotatably engaged with the headrest frame2. The headrest2is urged so as to be tilted by the headrest frame urging element(s)3at the normal time. In the raised state, the state in which the tilt is locked is formed by the lock mechanism4provided between the headrest frame2and the pillar1. This raised state is shown inFIGS. 4 to 7. Therefore, as shown inFIG. 2, the headrest HR is in a raised state.

In the lock mechanism4, when the engagement part46bon one end side of the ratchet46is pushed by the sliding of the ratchet lever44, the ratchet46rotates around the rotation axis, and the lock engagement part46con the other end side of the ratchet46moves in the direction of engaging crossingly with the engagement groove part41a,42aof the latch plate41,42.

In the raised state, the ratchet46is positioned in the engagement groove part41a,42aand comes into contact with the latch plate41,42, the pillar1and the headrest frame2are in a locked state, and the raised state of the headrest HR is maintained.

By operating the ratchet lever44against the ratchet lever urging element(s)45, the engagement part46bon one end side of the ratchet46is pushed, and the ratchet46is rotated around the rotation axis. Therefore, the ratchet46retracts from the engagement groove part41a,42a, so that the ratchet46comes off the engagement groove part41a,42aof the latch plate41,42. At this time, since the spring33, which is the headrest frame urging element(s)3, urges the headrest frame2in the tilt direction at the normal time, the headrest HR tilts around the transverse shaft part12, by which the storage state is formed.

As described above, when the head support state in which the headrest HR is raised with respect to the backrest seat S2is formed and when the storage state is formed by tilting the headrest HR from the head support state, in the present invention, as the lock mechanism4, the ratchet lever44, the latch plates41and42, and the ratchets46are used. Also, the engagement position and the disengagement position are switched over via the ratchet46one end side of which engages with the engagement concave part44bof the ratchet lever44and the other end side of which engages crossingly with the engagement groove part41a,42aof the latch plate41,42. Therefore, the lock mechanism4itself can be configured so as to be compact without requiring a wide width. Moreover, since at least one of the engagement groove parts41aand42aof the latch plates41and42serving as a locking member is formed so that the upper end side is narrow, the contact point of the ratchet46with the latch plate42separates from the contact point with the transverse shaft part12of the pillar1. Therefore, when the lock is released, the releasing load placed by the urging force of the headrest frame urging element(s)3(the spring33) from the rear can be decreased.

Also, at the normal time, the ratchet lever44is urged by the ratchet lever urging element(s)45in the direction such that the ratchet46is engaged with the engagement groove part41a,42aof the latch plate4142. When the ratchet lever44is operated against the ratchet lever urging element(s)45, the ratchet46comes off the engagement groove part41a,42a, and the headrest frame2is tilted to the storage state by the headrest frame urging element(s)3, so that the headrest HR tilts down. Therefore, the lock can be released by one operation (one action).

Furthermore, since one end side of the ratchet46touching the engagement concave part44bof the ratchet lever44is formed into a circular shape, the ratchet46turns smoothly in the engagement concave part44bof the ratchet lever44with respect to the movement of the ratchet lever44. Therefore, the ratchet46can be engaged with and disengaged from the engagement groove part41a,42aof the latch plate41,42, so that the lock can be released exactly.

When the headrest HR in the storage state is raised to the raised state, since in the normal time, the ratchet lever44is urged by the ratchet lever urging element(s) (spring)45, and the ratchet46is urged in the engagement groove part41a,42adirection of the latch plate41,42, if the headrest HR is raised by a hand, the ratchet46rotates, and the lock engagement part46cengages with the engagement groove part41a,42aof the latch plate41,42, by which the locked state is formed.

In the above-described embodiment, the pillar1, the latch plate41,42serving as a locking member for the lock mechanism4, and the ratchet46serving as a fixing member each are provided in number of two. However, the number of these members may be one or may be three or more. Needless to say, the number of engagement concave part44bof the ratchet lever44serving as an operation lever may be one or may be plural accordingly.