Abstract:
An apparatus for locking a table of a seat back to selectively secure the table in multiple stages, may include a base, a shaft coupled to the base and the table, an actuating arm fastened to the shaft and rotatable with the shaft, the actuating arm having actuating gear teeth, a locking arm rotatably provided on the base, wherein the locking arm includes locking gear teeth and the locking gear teeth is selectively engaged with the actuating gear teeth by the actuating arm such that when the actuating arm is rotated in a forward direction, the actuating gear teeth is engaged with the locking gear teeth or pass over the locking gear teeth according to rotational degree of the actuating arm, and a locking arm holding unit co-axially coupled with the actuating arm to the base and selectively activated by the actuating arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application Number 10-2008-0119496 filed Nov. 28, 2008, the entire contents of which application is incorporated herein for all purpose by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for locking a table of a seat back such that the table can be maintained in a state of having been extracted from or refracted into the seat back, and an angle of the table with respect to the seat back in the extracted state is adjustable. 
     2. Description of Related Art 
     Recently, according to an increase in the needs of consumers with respect to installation of various systems for convenience in vehicles, various kinds of apparatuses for convenience are installed in rear seats of the vehicles. 
     A table of a seat back is a representative example of the convenience apparatuses which are installed in the rear seats of the vehicles. A table may be provided on a seat back to allow a passenger to place food, books or the like on the table. The table of the seat back is preferably constructed such that when the use of the table is required, the table can be extracted from the seat back, and when it is not required, the table can be folded onto the seat back. 
       FIG. 1  is a view showing a table of a seat back, according to a conventional art. As shown in the drawing, a table T for a passenger, who sits on a rear seat, is provided on a rear surface of a seat back S of a front seat. For installation of the table T on the seat back S, a table locking apparatus is provided between the table T and the seat back S. In this art, as the table locking apparatus, a gas spring (not shown) is provided between the table T and the seat back S to unfold the table T from the seat back S and maintain the unfolded state of the table T. 
     However, in the conventional art, because of the volume of the gas spring, the table T is installed on the seat back S in a shape in which it protrudes from the seat back S. Therefore, the external appearance of the seat back S is deteriorated, and there is a possibility of interference between the table T and the knees of the passenger. 
     Furthermore, the installation of the gas spring increases the cost of manufacturing the seat back S having the table T. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY OF THE INVENTION 
     Various aspects of the present invention are directed to provide an apparatus for locking a table of a seat back which can adjust an angle, at which the table is unfolded from the seat back, using a relatively simple structure, and which minimizes a space for installation of the table in the seat back, thus preventing the table from interfering with knees of a passenger. 
     In an aspect of the present invention, the apparatus for locking a table of a seat back, the apparatus being provided between the table and the seat back to selectively secure the table with respect to the seat back in multiple stages, may include a base fastened to the seat back, a shaft pivotally coupled to the base and fastened on an end portion of the table, the shaft being rotatable along with the table on the base, an actuating arm fastened to the shaft and rotatable along with the shaft, the actuating arm having actuating gear teeth formed in an end portion thereof, a locking arm rotatably provided on the base at a position spaced apart from the shaft by a predetermined distance, wherein the locking arm includes locking gear teeth formed in an end portion thereof and elastically biased toward the shaft and the locking gear teeth is configured to be selectively engaged with the actuating gear teeth by a rotation of the actuating arm such that when the actuating arm is rotated in a forward direction, the actuating gear teeth is engaged with the locking gear teeth or pass over the locking gear teeth according to rotational degree of the actuating arm, and a locking arm holding unit co-axially coupled with the actuating arm to the base and selectively activated by the actuating arm, wherein, while the actuating gear teeth completely pass over the locking gear teeth, the actuating arm activates the locking arm holding unit to release the locking arm from a first position of the locking arm holding unit to be locked to a second position thereof so that the locking gear teeth does not interfere with the actuating gear teeth while the actuating arm is rotated in a reverse direction, and wherein the locking arm holding unit releases the locking arm to return to the first position of the locking arm holding unit so that the locking gear teeth is positioned to a trajectory locus of the locking gear teeth when the actuating arm rotates the locking arm holding unit in the reverse direction. 
     The apparatus may further include a guide pin provided on the actuating arm and configured to be selectively coupled to the locking arm holding unit according to a rotational direction of the actuating arm, wherein a guide slot is formed in the locking arm holding unit to receive the guide pin of the actuating arm therein, the guide slot extending a predetermined length along a trajectory locus of the guide pin, so that when the guide pin pushes a first end of the guide slot, the locking arm holding unit is rotated in the forward direction, when the guide pin pushes a second end of the guide slot, the locking arm holding unit is rotated in the reverse direction, and while the guide pin moves between the first and second ends of the guide slot, the locking arm holding unit is secured stationary. 
     The apparatus may further include a stop protrusion provided on the locking arm holding unit, a hook pivotally mounted to the base, and a stopper fastened to the hook to rotate along with the hook, wherein the hook or the stopper is elastically supported to bias the hook toward the locking arm holding unit to selectively couple the hook to the stopper protrusion of the locking arm holding unit, and wherein the hook is configured to lock the stop protrusion to the base to prevent the locking arm holding unit from rotating in the reverse direction while the locking arm is locked to the locking arm holding unit in the second position thereof; but when the actuating arm is rotated in the reverse direction to the predetermined distance, the stopper is pushed by the guide pin of the actuating arm to release the hook from the stop protrusion to enable the locking arm holding unit to rotate in the reverse direction by the actuating arm, wherein the stopper is disposed in front of the second end of the guide slot in the reverse direction of the locking arm holding unit such that the hook is released from the stopper protrusion before the second end of the guide slot is activated by the actuating arm when the locking arm holding unit rotates in the reverse direction. 
     A locking pin may be provided on the locking arm, and a locking depression is formed at the second position of the locking arm holding unit, so that while the locking arm holding unit is rotated in the forward direction, the locking pin is locked to the locking depression by the locking arm holding unit while the actuating gear teeth pass over the locking gear teeth, wherein an insert depression extending from one end of the insert depression is formed at the first position of the locking arm holding unit so that the locking pin of the locking arm is inserted into the insert depression when the guide pin rotating in the reverse direction activates the second end of the guide slot of the locking arm holding unit, and wherein a rotational radius between the rotation axis of the locking arm holding unit and the insert depression is shorter than a rotational radius between the rotation axis of the locking arm holding unit and the locking depression. 
     In another aspect of the present invention, the apparatus may further include a stop protrusion provided on the locking arm holding unit, wherein a subsidiary locking unit is pivotally coupled to the base at a predetermined position thereof and while the locking arm is locked to the second position of the locking arm holding unit, the subsidiary locking unit locks the stop protrusion to the base to prevent the locking arm holding unit from rotating in the reverse direction, wherein the subsidiary locking unit includes, a hook pivotally mounted to the base, and a stopper fastened to the hook to rotate along with the hook, wherein the hook or the stopper is elastically supported to bias the hook toward the locking arm holding unit to selectively couple the hook to the stopper protrusion of the locking arm holding unit, and wherein the hook is configured to lock the stop protrusion to the base to prevent the locking arm holding unit from rotating in the reverse direction while the locking arm is locked to the locking arm holding unit in the second position thereof, but when the actuating arm is rotated in the reverse direction to the predetermined distance, the stopper is pushed by the guide pin of the actuating arm to release the hook from the stop protrusion to enable the locking arm holding unit to rotate in the reverse direction by the actuating arm. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a conventional table of a seat back. 
         FIG. 2  is an exploded perspective view of an exemplary seat back having an apparatus for locking a table of the seat back, according to the present invention. 
         FIG. 3  is a perspective view of the table locking apparatus of  FIG. 2 . 
         FIG. 4  is a perspective view showing a first side of a portion B of the table locking apparatus of  FIG. 3 . 
         FIG. 5  is a perspective view showing a second side of the portion B of the table locking apparatus of  FIG. 3 . 
         FIGS. 6 and 7  are sectional views illustrating the operation of the table locking apparatus of  FIG. 3 . 
         FIGS. 8 and 9  are front views illustrating the operation of the table locking apparatus of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
       FIG. 2  is an exploded perspective view of an apparatus for locking a table of a seat back S, according to various embodiments of the present invention. The seat back table is installed on the seat back S and includes a front cover  1 , a table frame  10 , the table locking apparatus (B), a table support plate  30  and a rear cover  50 . The table frame  10  is fastened to a shaft  100  and rotated along with the shaft  100 . The shaft  100  is coupled to the locking apparatus B such that an angle at which the shaft  100  is rotated is determined in stages. Actuating structures are provided on the respective opposite ends of the shaft  100 , that is, on portions designated by the reference characters A and B. The locking apparatus means the portion B. A latch unit C is provided in the lower end of the seat back, so that a latch of the table is inserted into the seat back through a seating hole S 10  and is selectively latched to the latch unit C. 
       FIG. 3  is a perspective view of the table locking apparatus of  FIG. 2 . The table frame  10  which is rotated along with the shaft  100  is fastened to the shaft  100 . A spring  120  is provided on a first end (on the portion A) of the shaft  100  to elastically support the table frame  10 . The table locking apparatus of the present invention is provided on a second end (on the portion B) of the shaft  100 . For the installation of the table locking apparatus, bases  300  are provided on the shaft  100 . 
       FIGS. 4 and 5  are perspective views showing the table locking apparatus according to various embodiments of the present invention. The table locking apparatus is provided between the seat back S and the table T and selectively determines a position at which the table T is in a locked state. In detail, the table locking apparatus includes the shaft  100 , which is provided on one end of the table T and rotated along with the table T on the seat back S, and an actuating arm  200 , which is fastened to the shaft  100  and rotated along with the shaft  100 . Actuating gear teeth  220  are formed in a distal end of the actuating arm  200 . 
     The table locking apparatus further includes the bases  300 , which are provided on the shaft  100 , and a locking arm  500 , which is provided on one base  300  at a position spaced apart from the shaft  100  by a predetermined distance. Locking gear teeth  520  which engage with the actuating gear teeth  220  of the actuating arm  200  are formed in an end of the locking arm  500  which is adjacent to the shaft  100 . The locking arm  500  is elastically supported by an elastic member  562  so that when the actuating arm  200  is rotated in a normal direction, the actuating gear teeth  220  pass over the locking gear teeth  520  in stages. 
     The table locking apparatus further includes a locking arm holding unit  600 , which is provided between the actuating arm  200  and the locking arm  500 . The locking arm holding unit  600  moves the locking arm  500  backwards and holds it in the backwardly moved state after the actuating gear teeth  220  completely pass over the locking gear teeth  520 , thus preventing the actuating gear teeth  220  and the locking gear teeth  520  from interfering with each other when the actuating arm  200  is reversely rotated. Furthermore, the locking arm holding unit  600  releases the backwardly moved and held state of the locking arm  500  when the actuating arm  200  is returned to its original position. 
     The bases  300  are disposed on opposite sides of the table T and fastened to the seat back S. Each base  30  may be made of several panels, and the shaft  100  may pass through the bases  30 . The shaft  100  is fastened to the table T so that when a user rotates the table T, the shaft  100  is rotated along with the table T. The actuating arm  200  is fitted over and fastened to the shaft  100  and is thus rotated along with the shaft  100 . Furthermore, the locking arm holding unit  600  is fitted over the shaft  100  so as to be rotatable with respect to the shaft  100 . 
     When the table T is extracted from the seat back and is rotated upwards, the shaft  100  and the actuating arm  200  rotate in normal directions. When the table T is rotated downwards and is retracted into the seat back, the shaft  100  and the actuating arm  200  rotate in reverse directions. Here, the terms ‘normal direction’ and ‘reverse direction’ merely mean that the directions are opposite each other, but are not to be construed as limiting the present invention. 
     Meanwhile, the actuating arm  200  is fitted at a proximal end thereof over the shaft  100  and has the actuating gear teeth  220  in the distal end thereof. It is preferable that the actuating gear teeth  200  be spur gear teeth. Furthermore, a guide pin  240  is provided on the actuating arm  200 . A guide slot  620  which guides the guide pin  240  therein and extends a predetermined length along a movement trajectory of the guide pin  240  is formed through the locking arm holding unit  600 . The guide pin  240  is moved along the guide slot  620  of the locking arm holding unit  600  when the actuating arm  200  is rotated. Here, the guide pin  240  moves along the guide slot  620 , but the locking arm holding unit  600  maintains the stationary state. 
     The locking arm  500  is provided on the base  300  by a hinge pin  560  below the locking arm holding unit  600 . The locking gear teeth  520  corresponding to the actuating gear teeth  220  are formed on a distal end of the locking arm  500 . It is also preferable that the locking gear teeth  520  are spur gear teeth. The locking arm  500  having the locking gear teeth  520  is supported by the elastic member  562 . 
     When the table T, the shaft  100  and the actuating arm  200  rotate in normal directions, the actuating gear teeth  220  of the actuating arm  200  come into contact with the locking gear teeth  520  of the locking arm  500 . Here, when the actuating gear teeth  220  push the locking gear teeth  520 , the locking arm  500  moves while overcoming the elastic force of the elastic member  562 , and the actuating gear teeth  220  pass over the locking gear teeth  520  in stages. The number of stages in which the table T is unfolded is determined depending on the number of actuating gear teeth  220  and the number of locking gear teeth  520 . The table T can maintain a state of having been unfolded at various angles in stages. 
     Meanwhile, a locking pin  540  is provided on the locking arm  500 . An insert depression  640 , into which the locking pin  540  is inserted, is formed in the lower end of the locking arm holding unit  600 . A locking depression  642  which extends from the insert depression  640  is formed in the locking arm holding unit  600 . While the locking pin  540  is in a state of having been inserted in the insert depression  640  of the locking arm holding unit  600 , the locking arm holding unit  600  maintains the stationary state as the locking arm  500  and the actuating arm  200  are engaged each other and the locking arm  500  is supported by the elastic member  562 . 
     After the actuating arm  200  is rotated in the normal direction and the actuating gear teeth  220  completely pass over all the locking gear teeth  520 , if the actuating arm  200  is further rotated, the guide pin  240  of the actuating arm  200  pushes a first end  622  of the guide slot  620 , and the locking arm holding unit  600  is thus rotated in the normal direction. Then, the locking pin  540  is pushed by the rotation of the locking arm holding unit  600  in the normal direction. Thus, the locking pin  540  is removed from the insert depression  640  and locked to the locking depression  642 . When the locking pin  540  enters the locking depression  642 , the locking arm  500  overcomes the elastic force of the elastic member  562  and is moved backwards from its original position. When the locking pin  540  is in the state of having been locked to the locking depression  642 , the locking arm  500  maintains the state of being moved backwards. Thereby, the locking gear teeth  520  of the actuating gear  220  no longer engage with the actuating gear teeth  220  of the actuating arm  200 . 
     Furthermore, a stop protrusion  660  is provided on an upper end of the locking arm holding unit  600  which is opposite the locking arm  500 . A subsidiary locking unit  700  is provided at a predetermined position on the base  300 . The subsidiary locking unit  700  hooks the stop protrusion  660  in the state in which the locking arm holding unit  600  rotates in the normal direction and the locking arm  500  is thus moved backwards and locked to the locking arm holding unit  600 , thus preventing the locking arm holding unit  600  from being undesirably rotated in the reverse direction. The subsidiary locking unit  700  includes a hook  720 , which is mounted to the base  300  by a hinge pin  722  and hooks the stop protrusion  660  to prevent the locking arm holding unit  600  from being rotated in the reverse direction, and a stopper  740 , which is rotated along with the hook  720  and is supported by a spring  760 . When the actuating arm  200  is rotated in the reverse direction, the stopper  740  is pushed upwards by the guide pin  240  and thus moves the hook  720  backwards to enable the locking arm holding unit  600  to rotate in the reverse direction. 
     The hook  720  and the stopper  740  are mounted together to the base  300  by the hinge pin  722 . The stopper  740  is connected to a spring  760 , which biases the stopper  740  downwards. Therefore, when the guide pin  240  of the actuating arm  200  pushes the stopper  740 , the stopper  740  and the hook  720  are rotated upwards. When the guide pin  240  is removed from the stopper  740 , the stopper  740  and the hook  720  are rotated downwards again. 
     When the actuating arm  200  rotates in the normal direction and the locking arm holding unit  600  is rotated in the normal direction by the guide pin  240 , the stop protrusion  660  of the locking arm holding unit  600  is hooked to the hook  720 , thus preventing the locking arm holding unit  600  from rotating in the reverse direction. When the actuating arm  200  rotates in the reverse direction, the guide pin  240  pushes the stopper  740  upwards such that the hook  720  is removed from the stop protrusion  660 . When the guide pin  240  pushes a second end  624  of the guide slot  620  of the locking arm holding unit  600 , the locking arm holding unit  600  is rotated in the reverse direction, and the locking pin  540  is removed from the locking depression  642  and enters the insert depression  640  again. In addition, the locking arm  500  is returned to its original position. 
       FIGS. 6 and 7  are sectional views illustrating the operation of the table locking apparatus of  FIG. 3 . In an initial stage, the actuating arm  200  is disposed at the upper end of the locking arm holding unit  600 , and the guide pin  240  is disposed on the second end  624  of the guide slot  620 . From this state, when the table T is rotated upwards, the actuating arm  200  is rotated along with the shaft  100  in the normal direction. At this time, the position of the table T is adjusted in stages while the actuating gear teeth  220  pass over the locking gear teeth  520 . 
     After the guide pin  240  is brought into contact with the first end  622  of the guide slot  620 , when the actuating arm  200  is further rotated, the guide pin  240  rotates the locking arm holding unit  600  in the normal direction. Then, the locking pin  540  of the locking arm  500  is removed from the insert depression  640  and enters the locking depression  642 . This means that the locking arm  500  overcomes the elastic force of the elastic member  562  and is locked to the locking arm holding unit  600 . Hence, the locking arm  500  is maintained in the state of having been moved backwards and locked to the locking arm holding unit  600 . 
     When the locking arm  500  is in the backwardly moved and locked state, the locking gear teeth  520  is prevented from interfering with the actuating gear teeth  220 . Therefore, when the table T is rotated downwards, the table T, the shaft  100  and the actuating arm  200  can be rotated in the reverse directions and returned to their original positions. When the guide pin  240  of the actuating arm  200  pushes the second end  624  of the guide slot  620  by the reverse rotation of the actuating arm  200 , the locking arm holding unit  600  is also rotated in the reverse direction. Then, the locking pin  540  of the locking arm  500  is removed from the locking depression  642  and inserted into the insert depression  640  again. Thus, the locking arm  500  is returned to its original position, at which the locking gear teeth  520  of the locking arm  500  can engage with the actuating gear teeth  220  of the actuating arm  200 . 
     As such, in the present invention, when the table T is rotated upwards, that is, in the normal direction, from the state in which it has been retracted in the seat back S, the angle of the table T with respect to the seat back S can be adjusted in stages. When the table T is maximally rotated upwards, the locking arm  500  is moved backwards and locked, so that the table T enters the state in which it can be rotated in the reverse direction and retracted into the seat back S. After the table T is rotated in the reverse direction at a predetermined angle, the locking arm  500  is returned to its original position. As described above, because the table locking apparatus is provided on one end of the shaft  100 , to which the table T is fastened, the table T can be flush with the surface of the seat back. Furthermore, the present invention does not require a separate gas spring mechanism, thus reducing the production cost. 
       FIGS. 8 and 9  are front views illustrating the operation of the table locking apparatus. When the guide pin  240  is disposed on the second end  624  which is the uppermost end of the guide slot  620 , the guide pin  240  pushes the stopper  740  upwards and thus supports it. In this state, when the table T, the shaft  100  and the actuating arm  200  are rotated in the normal directions, the guide pin  240  is moved downwards along the guide slot  620 , and the stopper  740  and the hook  720  are returned to their original positions. Thereafter, when the guide pin  240  pushes the first end  622  of the guide slot  620  and the locking arm holding unit  600  is thus rotated in the normal direction, the locking pin  540  is removed from the insert depression  640  and inserted into the locking depression  642  while compressing the elastic member  562 . Here, because the elastic member  562  of the locking arm  500  always biases the locking arm  500  to its original position, if the locking pin  540  is not in a state of being completely locked to the locking depression  642 , the locking arm  500  is returned to its original position by the elastic force of the elastic member  562 . Then, the locking pin  540  strikes the locking arm holding unit  600  because of the force with which the locking arm  500  is returned to its original position. Thereby, the locking arm holding unit  600  is rotated again in the reverse direction. To prevent this event, the stop protrusion  660  is provided on the upper end of the locking arm holding unit  600 . In detail, when the locking arm holding unit  600  is rotated in the normal direction, the stop protrusion  660  is hooked to the hook  720 , thus preventing the locking arm holding unit  600  from being undesirably rotated in the reverse direction. 
     When the actuation arm  200  rotates in the reverse direction and thus pushes the stopper  740  upwards, the hook  720  is also pushed upwards and removed from the stop protrusion  660 . When the actuating arm  200  further rotates in the reverse direction until the guide pin  240  pushes the second end  624  of the guide slot  620 , the locking arm holding unit  600  is rotated in the reverse direction. The locking pin  540  is inserted into the insert depression  640  again by the reverse rotation of the locking arm holding unit  600 , and the locking arm  500  is returned to its original position. 
     As described above, in an apparatus for locking a table of a seat back according to the present invention, the table can be locked to the seat back by a relatively simple structure without using a separate gas spring mechanism. Furthermore, the angle at which the table is locked to the seat back is adjustable. In addition, a gap between the table and the seat back when the table is retracted into the seat back is minimized, thus ensuring a good appearance, and preventing the table from interfering with knees of a passenger. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “downward”, “forward”, and “reverse” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.