Abstract:
A retractable headrest assembly for a seat includes a headrest assembly mounted on a top portion of a seatback for pivotal movement between use and retracted positions about a first axis, and a retracting mechanism for toggling the headrest assembly to either of the use and retracted positions. The retracting mechanism includes a first shaft member defining the first axis and coupled with a seatback frame, embedded in the seatback, and a biasing element for urging the headrest assembly rearwardly about the first axis.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a seat assembly in general and, more particularly, to a retractable headrest assembly for an automobile seat assembly although not exclusively limited thereto. 
     2. Description of the Related Art 
     In some countries over the world, seat assemblies in automotive vehicles are required by law to have a headrest for protecting one or more vehicle occupants. The headrest assembly generally in use is now available in two types, liftable and retractable types. While the liftable headrest is specifically designed to allow the position of the headrest to be adjustable to suit to the position of, for example, a vehicle driver, the currently available retractable headrest is of a structure employed in combination with a pivot or retracting mechanism by which the headrest can be pivoted forwards or rearwards between a use position and a retracted position in which the headrest is accommodated inside the seatback. 
     In this known retractable headrest assembly, the retracting mechanism makes use of a combination of at least one spring element with a damping device, or an electrically driven motor. In addition, installation of the known retractable headrest assembly requires a relatively large space so as to hinder the field of view from a rear seat occupant and also to increase the weight and cost of the seat assembly as a whole. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been devised to substantially eliminate the foregoing problems and inconveniences and is intended to provide a lightweight, inexpensive retractable headrest assembly employing an improved retracting mechanism effective to provide a relatively large field of view while neatly accommodated within the seatback. 
     In order to accomplish the foregoing and other objects and features of the present invention, there is provided a retractable headrest assembly for a seat, which includes a headrest assembly mounted on a top portion of a seatback for pivotal movement between use and retracted positions about a first axis; and a retracting mechanism for toggling the headrest assembly to either of the use and retracted positions. The retracting mechanism includes a first shaft member defining said first axis and coupled with a seatback frame, embedded in the seatback, and a biasing means for urging the headrest assembly rearwardly about the first axis. 
     In a preferred form of embodiment of the present invention, the retractable headrest assembly for use in a seatback includes a headrest having a frame structure embedded therein and having two spaced apart connecting portions. The seatback has a top portion formed with a recess configured to represent a shape substantially complemental to a shape of the headrest, so that when the headrest is in a retracted position, the headrest can be neatly accommodated within the recess. The headrest assembly may also include generally elongated connecting members each coupled at one end with a corresponding seatback frame embedded in the seatback so as to extend generally transverse to the associated seatback frame and axially aligned with each other to define a common axis and positioned on respective opposite sides of the recess, generally ring-shaped stop plates each rigidly secured to the respective connecting member so as to lie in a plane perpendicular to the connecting member, a bearing rod having its opposite ends coupled with the stop plates so as to extend parallel to, but be offset a distance from the common axis, and support plates pivotally mounted on the bearing rod and fixedly coupled with the connecting portions of the frame structure embedded in the headrest for movement together therewith. At least one biasing element is used and is connected between one of the support plates and one of the connecting members for retaining the headrest in one of use and retracted positions about the bearing rod. This biasing element is operable to allow the headrest to be toggled to either of the use and retracted positions as the headrest is pivoted about the bearing rod moves past a top dead center position defined on one side of the bearing rod opposite to the common axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become readily understood from the following description of preferred embodiments thereof made with reference to the accompanying drawings, in which like parts are designated by like reference numerals and in which: 
     FIG. 1 is a fragmentary perspective view of a seatback employing a retractable headrest assembly designed in accordance with the present invention, with a headrest held at a use position; 
     FIG. 2 is a view similar to FIG. 1, showing the headrest held at a retracted position; 
     FIG. 3 is an exploded view of a retracting mechanism shown in FIGS. 1 and 2; 
     FIG. 4 is a perspective view of the retracting mechanism showing the skeleton thereof when the headrest is held at the use position; 
     FIG. 5 is a view similar to FIG. 5, showing the skeleton of the headrest assembly when the headrest is held at the retracted position; and 
     FIG. 6 is a schematic side view of a portion of the retracting mechanism, showing an engagement between a stopper plate and a stopper bracket. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This application is based on an application No. 2001-126 filed Jan. 4, 2001 in Japan, the content of which is herein expressly incorporated by reference in its entirety. 
     Referring first to FIGS. 1 and 2, there is shown a retractable headrest assembly R according to the present invention. The headrest assembly R is shown as used in an automobile seat assembly including a seatback S, but may be employed in any other seat such as, for example, a home reclining chair such as a lounger. As will be readily understood from the subsequent description, the retractable headrest assembly R according to the present invention does neither make use of an electrical installation nor any connection with an external actuating mechanism and, accordingly, the retractable headrest assembly R of the present invention can be employed in any type of seats or chairs that may be used where neither electric power nor an external drive source is available. 
     The retractable headrest assembly R embodying the present invention includes a headrest HR pivotable between a use position as shown in FIG. 1 and a retracted position as shown in FIG. 2 by means of the retracting mechanism generally identified by M. In FIGS. 1 and 2, the seatback S is shown to have its top portions formed with a recess  4  leaving a pair of shoulder supports Sa on respective sides thereof. As will become clear from the subsequent description, seatback support frames  2  connected at one end with, for example, seat cushion frames (not shown) or frame elements of any known seatback reclining adjustment (also not shown) extend to such an extent as to terminate within the shoulder supports Sa. 
     The headrest HR is shown to be of a generally triangular configuration and, hence, the recess  4  may have a correspondingly triangular configuration complemental to the shape of the headrest HR so that when the headrest HR is pivoted to the retracted position the headrest HR can be snugly and neatly accommodated within the recess  4 , although any other combination of shapes of the headrest HR and the recess  4  can be employed. It is, however, to be noted that the headrest assembly R embodying the present invention may be combined with any known headrest lift mechanism, but where no headrest lift mechanism is employed, the triangular shape of the headrest R such as shown is particularly advantageous in that when the headrest R is pivoted to the use position as shown in FIG. 1, a vertex portion of the headrest R can come to a position generally aligned with the head of a seat occupant. 
     Referring particularly to FIGS. 3 to  5 , respective top ends of the seatback support frames  2  may have headrest support bars  6  rigidly connected thereto, respectively, so as to extend further upwardly within the associated shoulder supports Sa. Each of the headrest support bars  6  has a transverse support rod  8  fixed at one end to the corresponding headrest support bar  6  so as to extend perpendicular thereto and also so as to face towards and be axially aligned with the transverse support rod  8  secured to the other of the headrest support bars  6 . It is to be noted that the headrest support bars  6  may be dispensed with, in which case the transverse support rods  8  are to be fixedly connected to the seatback support frames  2  so as to extend perpendicular thereto. 
     A generally L-shaped bracket  10  having a fixing arm and a bearing arm at right angles to the fixing arm is mounted on each of the headrest support rods  8  with the fixing arm secured thereto by means of a set bolt. A generally annular stopper plate  14  is secured to the bearing arm of each bracket  10  through an associated connecting pin  12 . The annular stopper plates  14  carried by the transverse support rods  8  in the manner described above are oriented in the same direction with their bores aligned with each other in a direction traversing the recess  4 . Although in the illustrated embodiment the transverse support rods  8 , and the connecting pins  12  separate therefrom are employed, each connecting pin  12  may be an integral part of the associated transverse rod  8  and may hence be defined by a single rod member. 
     The retracting mechanism M also includes a pair of generally rectangular side plates  20  and a bearing rod  16 . Each of the rectangular side plates  20  has a bearing hole defined therein at a location adjacent one end thereof, and the bearing rod  16  has its opposite ends extending through the bearing holes in the side plates  20  and axially immovably received in the bores of the stopper plates  14 , respectively. A washer  18  may be interposed between an annular shoulder at each end portion of the bearing rod  16  and the adjacent side plate  20 . The bearing rod  16  has its longitudinal axis positioned offset a distance laterally from a common axis connecting between the connecting pins  12  for a reason which will become clear from the subsequent description. 
     In order to define the use and retracted positions of the headrest HR. a stopper piece  22  is fixedly mounted on, or otherwise welded to, one of opposite surfaces of each side plate  20  adjacent the corresponding annular stopper plate  14 . This stopper piece  22  is cooperable with the corresponding annular stopper plate  14  and, for this purpose, has a bottom face slidingly engaged with a portion of the outer peripheral edge of the annular stopper plate  14  substantially as best shown in FIG.  6 . As shown, a rubber piece  24  is bonded to the bottom face of each stopper piece  22 , which may not be always necessary. 
     The side plates  20  are connected together by means of a generally V-shaped upper headrest frame  26  having its opposite ends welded to respective upper ends thereof and a lower headrest frame  28  having its opposite ends received and fixed in position within respective holes each defined in the lower end of the associated side plate  20  so as to extend substantially parallel to the bearing rod  16 . The assembly including the side frames  20  and the upper and lower headrest frames  26  and  28  is pivotable about the bearing rod  16  between two positions corresponding to the use and retracted positions of the headrest HR. For enabling the headrest HR to be toggled between the use and retracted positions, biasing elements such as coil springs  32  are employed and each has one end anchored to the adjacent connecting pin  12  and the other anchored to an associated anchor pin  30 . Each anchor pin  30  is secured to one of the side plates  20  at a location on one side of the stopper piece  22  opposite to the bearing hole so as to protrude laterally towards the adjacent transverse support rod  6 . 
     It will readily be seen that since the longitudinal axis of the bearing rod  16  is offset laterally from the common axis aligned with the connecting pins  12 , the assembly including the side frames  20  and the upper and lower headrest frames  26  and  28  can be toggled to the use position or the retracted position by the action of the coil springs  32  while pivoting about the longitudinal axis of the bearing rod  16 . 
     More specifically, assuming that the headrest HR is in the use position as shown in FIGS. 1 and 4, the stopper pieces  22  are, having been pulled by the coil springs  32 , held in abutment with radially outward protrusion  14   a  integral with the respective annular stopper plates  14  as best shown in FIG. 6 and, therefore, the headrest HR cannot go beyond the use position. When the headrest HR is pivoted counterclockwise about the bearing rod  16  against the coil springs  32  in readiness for the headrest HR to be accommodated neatly within the recess  4  by the application of an external pushing or pulling force acting in a forward direction confronting the position of the head of the seat occupant, and as the headrest HR passes over a top dead center position, the headrest HR can be quickly toggled over the top dead center position and then folded into the recess  4  by the action of the coil springs  32 . The dead center position referred to above is defined at a location on one side of the bearing rod  16  opposite to the common axis aligned with the connecting pins  12 , at which the coil springs  32  are axially outwardly expanded to accumulate respective energies necessary to toggle the headrest HR in the manner described above. 
     When the headrest HR is so pivoted to the retracted position as shown in FIGS. 2 and 5, the stopper pieces  22  are brought into engagement with radially outwardly protruding stops  14   b , as shown in FIG. 6, each integral with the corresponding stopper plate  14 , and are kept in that retracted position by the action of the coil springs  32 . 
     In practice, the assembly including the side frames  20 , the upper and lower headrest frames  26  and  28 , the bearing rod  16 , the coil springs  32 , and the brackets  10  is concealed within a casing (not shown) embedded in the headrest HR. The casing may include casing halves of identical configuration made of a suitable synthetic resin. At least one of the casing halves may have a plurality of interior ribs  34 , some of which may be utilized for connection with fixture lugs  20   a,  formed integrally with the side plates  20  so as to protrude transverse thereto, and fixture brackets  36  welded to the V-shaped headrest frame  26 . After such one of the casing halves has been connected to the assembly, the other of the casing halves may be welded, or otherwise bonded or screwed, to such one of the casing halves and the resultant casing is then embedded in a cushioning material to finish the headrest HR. 
     Although the present invention has been described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims, unless they depart therefrom.