Abstract:
The invention consists of modification to the groove of the side panels and integration of locking system on seat and foot plates of the adjustable chair for children. The upright panel of the adjustable high chair has grooves with a single or plurality of holes along the top and bottom surfaces of the groove to catch a comparable interlocking device, for locking desired object at various positions. The modification to the groove allows more versatility to adjustment of height, and exchanging the usability of the adjustable chair to other types of fixtures. In addition to the modification, similar groove system is to be added to the outer surface of the side panels to accommodate changing positions of the food tray or grab rail in accordance to the changing positions of the seat plates. This groove system can also be applied to other adjustable chairs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/536,497 filed on Sep. 19, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to modification to the method of adjustment of seat depth and height of chair plates, and the height of food tray and/or grab rail on adjustable chair for children. 
     2. Discussion of Prior Art 
     The classic adjustable chair for children described in U.S. Pat. No. 4,109,961 is capable of accommodating children of various ages to adults with different heights by adjusting the height of the seat plate. The patent uses a series smooth-surfaced horizontal groove arranged vertically on inner surface of the uprights (or upright panels) and facing each other. A foot rest plate and a seat plate, both having opposite ends respectively slide in opposite ones of the grooves at desired vertical locations along the upright panels. These chair plates are tightly held in place by tension and friction force between the two upright panels and the plates. The tension created by tightening screws and nuts on the upright panels. This method of adjustment requires significant time and effort requiring significant amount of human strength to ensure tightness of the screws and nuts. Moreover, one or more tools are required to loosen and tightened screws and nuts. 
     In addition, the series of horizontal grooves only applied to inner upright panels and not on outer upright panels to support the synchronization of the food tray or grab rail with the position of the seat. As a result, a growing child will end up with a food tray at higher position than usual, causing improper seating in the adjustable chair. 
     SUMMARY OF INVENTION 
     The present invention relates to an easier method to adjust the chair plates on the adjustable chair. This is accomplished by changing the smoothed-surface groove into a groove of a single hole or plurality of holes. The seat and foot plates are attached with parts of interlocking system that snaps on and off the adjustable chair. By having this type of system, it allows an interlocking system that does not require friction force, or addition tools to secure the plates in place. The chair plate which consists of either seat or foot plate can be removed from the chair, and secured at the desired height on the chair quickly, with no additional tools required. Consequently, the chair can be adjusted from fitting a toddler to adult in a matter of seconds. In addition, to accommodate a growing child, the outer surface upright panels are now added with addition grooves each with different level of precise position according to child body height on sitting posture which allow the food tray or grab rail to switch positions for better comfort as the child grow. The series of grooves on the outer panels is designed to synchronize with the series of grooves on the inner upright panels. This is to avoid an excess gap or opening between the food tray or grab rail and the seat, when the seat position has been adjusted to different level of grooves. For example, if the seat position is lowered one level, the food tray or grab rail on outer position will be adjusted one level lower to ensure proper seat-tray alignment. Without adjusting the outer groove level, an excess vertical gap will appear which may cause the child to slip through the gap underneath the tray easily, causing a safety hazard. Besides creating a safety hazard, the food tray will also be out of a proper alignment for the child. The series of grooves on the outer panels are designed to make sure height of each level is closely coordinated with the groove on the inner panel, with precise measurement, so that distance between the food tray and the seating surface complies with ASTM F404, the American Society for Testing and Materials (ASTM) safety standard for high chair. 
     The present invention can be applied into any kind of adjustable chair of any shape and size made of wood or artificial materials. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING 
         FIG. 1  is a perspective view of the adjustable chair in its entirety showing the different parts of the chair. 
         FIG. 2  is partial perspective view of the upright panels, chair plate and lateral view of the grooves. 
         FIG. 3  is a close-up partial lateral view of the upright panel, showing the lower horizontal lip of the groove with a plurality of holes. 
         FIG. 4  is a partial lateral view of the inner surface of the upright panel, showing the upper and lower horizontal lips with plurality of holes. 
         FIG. 5  is a lateral view of the inner surface of the upright panel, showing the interlocking system, whereby the second part of the interlocking system on the chair plate, attaches onto the plurality of holes on the groove. 
         FIG. 6  is a top view of the locking mechanism on the chair plate with a plurality of tabs, instead of a single tab. 
         FIG. 7  is a view of a chair plate with a plurality of holes as an alternate embodiment of the invention. 
         FIG. 8  is a partial perspective view of an example of the alternate embodiment showing pattern of a plurality of tabs, corresponding to the plurality of holes on the chair plate depicted in  FIG. 7 . 
         FIG. 9  is a partial perspective view of an alternate embodiment with a plurality of holes on the vertical side of each groove on the upright panel. 
         FIG. 10  is a perspective view of the chair plate, with an alternate embodiment of the second part of the interlocking system on the vertical side of the chair plate, corresponding to fit the plurality of holes depicted in  FIG. 9 . 
         FIG. 11  is a partial perspective view of an alternate embodiment of the locking mechanism on the groove. 
         FIG. 12  is a partial perspective view of an alternate embodiment with column of slots along the upright panel. 
         FIG. 13  is a perspective view of an alternate embodiment of the second part of the interlocking system on the chair plate to fit into the slot depicted in  FIG. 12 . 
         FIG. 14   a  and  FIG. 14   b  is a lateral view of the adjustable chair showing the adjustment of the food tray heights. 
         FIG. 15  is a perspective view of the adjustable chair showing a lateral view of the grooves for the food tray. 
         FIG. 16  is a perspective view of the adjustable chair showing a lateral view of an alternate embodiment of the groove to fit a bracket for the food tray. 
         FIG. 17  is a perspective view of the adjustable chair showing a lateral view of an alternate embodiment of the groove with a single or plurality of tabs or similar projection means for interlocking system. 
         FIG. 18  is a posterior view of the groove said in  FIG. 17  showing the level to control the single or plurality tabs on each grooves. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The present invention relates to an easier method to adjust the seat depth and height of chair plates, and the height of food tray and/or grab rail on adjustable chair for children. It can be applied on any type of adjustable high chair of various designs, sizes and shapes. The general parts of an adjustable high chair comprises of chair plates  1 , of one designed as a seat plate, and another as a foot plate; two upright panels  2  on each sides of the chair, backrest  3  and a food tray or grab rail  81 . The invention modifies the method of fastening the said chair plates  1  onto the upright panels  2  by means of an interlocking system that utilizes a plurality of holes  32  or single hole on the grooves  30  aligned on the inner surface of the said upright panels  2 . See  FIG. 2 . These grooves are aligned vertically along the upright panels  2 , at the desired height span, equivalently on each facing sides. It is noted,  FIG. 3 , that even though the plurality of holes or single hole is intended on the lower lip of the groove, the plurality of holes  32  or single hole can also be on the lower and upper lips of the said groove. Advantages of this variation will be discussed in the next paragraph. 
     The plurality of holes  32  or single hole allows the chair plate be locked at a variety of positions horizontally, thus adjusting the chair depth in order to accommodate different sizes of the user. The plurality of holes  32 , compared to a single hole adds to the stability of the seat. This is because the plurality of holes increases the contact surface between and seat and the upright panel within the interlocking system, thereby minimizing the shakiness of seat. The advantage of having the single or plurality of holes on the upper and bottom ( FIG. 4 ) lips of each groove  30  is that it allows the chair plate to be installed in more than one way. This creates more variety of seat arrangements for different usage. For example, the chair plate of a smooth surface for seating can be flipped to reveal the bottom surface, which happens to be a non-skid surface for use of a stepladder. Or the chair plate that has a child passive restraint system on the front of the plate to prevent a baby from sliding out of the chair can be inverted where the child passive restraint is now at the back, and a smooth surface at the front for adult seating. 
     It is also noted that the plurality of the holes  32  or single hole can be of various shapes and sizes to fit the accompanied interlocking system on the chair plate  1 . The plurality of holes  32  or single hole can be of and not limited to, extension and indention (hills and valleys), holes for tabs, holes with slots for anchoring hook locks. The different sizes and designs will be further discussed in the paragraphs below when alternate embodiments are mentioned. 
     The second part of the interlocking system is found on the chair plate depicted  FIG. 5 . The plate  1  has, on each side, a complimentary strip of a single  33  or a plurality of tabs  34  (shown in  FIG. 6 ) designed to fit optimally onto the plurality of holes  32  or single hole on the groove. The said tab can also be a hook, or, a plurality of hooks. 
     The engagement of the lock is accomplished by the release of the tension created by a lever  35  that is attached to the tab  33  or plurality of tabs  34  (See  FIG. 6 ) to form a locking mechanism. The said lever  35 , when tension applied, depresses the tab/tabs  33 / 34 , allowing the plate  1  to slide along the groove  30 . When desired placement is reached, the lever tension is released to allow the tab/tabs  33 / 34  to engage lock onto the plurality of holes  32  or single hole. It is noted that the locking mechanism can be of various designs, sizes and shapes with the intent to engage tab/tabs  33 / 34  with the plurality holes  32  on the vertical side of the groove  30 . For example, the lever  35  can be replaced by a spring-operated push button. 
     Alternate Embodiments 
     It is to be noted that an alternate embodiment to the intervention is to exchange the positions of the interlocking system parts. Instead of being on the groove, the plurality of holes  42  or single hole is now placed on the chair plate  1 . See  FIG. 7 . Instead of being on the plate, the plurality of tabs  43  or single tab is on each groove along the upright panels  2 . See  FIG. 8 . The said chair plate  1  with single or plurality of holes will be slid into different spots along the plurality of tabs  43  or single tab for adjustments of desired positions, and then be locked in position by way of the interlocking system similar to the primary embodiment. 
     Another embodiment to the invention is that the plurality of holes  52  or single hole is disposed on the vertical aspect as opposed to the horizontal (upper and bottom lips) of the groove  30  on the upright panels  2 . See  FIG. 9 . In this case, the second part of the interlocking system, shown in  FIG. 10 , will be on the vertical sides  51  of the chair plate  1  to fit the vertical position of the said plurality of holes  52  or single hole. The tab/tabs  53 , now on the vertical sides  51  of the chair plate I will operate similarly with tension created by depression of the lever  55  with or without a button  56 , to slide the tab  53  attached to the said lever  55 , along the said groove  30  in  FIG. 9 . When desired position is obtained, the said lever will be released allowing the chair plate  1  to lock in position. It is to be noted that a hook can also be used in replacement of the said tab  53 . It is to be noted also that the said tab  53  can be replaced with a plurality tabs to fit the plurality holes  52  on the vertical side of the groove  30 . Similarly, the plurality of holes  52  can be replaced with a single hole, to fit a single or plurality of tabs  53 . It is also noted that the lever of the locking mechanism can be of various designs, sizes and shapes with the intent to engage tab  53  with the plurality holes  52  on the vertical side of the groove  30 . For example, the lever  55  can be replaced by a spring-operated push button. 
     Another embodiment to the above described, where the strip of single tab  63  or plurality of tabs are on the upright panels  2 . It is noted that the groove on the upright panels is equipped with the locking mechanism  61 , as shown in  FIG. 11 . The locking mechanism  61  is aligned in vertical series on each side of the inner surface of the upright panels  2 . The chair plate  1 , depicted in  FIG. 7 , equipped with corresponding plurality of holes  42  or single hole on each side slides along the locking mechanism  61  to engage the lock. The locking mechanism  61  consists of a tension lever  65 , much like the initial embodiment of the invention, with a single tab  63  or plurality of tabs to fit the plurality holes  42  or single hole on the said chair plate  1  as in  FIG. 7 . It is also noted that locking mechanism can be of various designs, sizes and shapes with the intent to engage tab  63  with the plurality holes  42  on the said chair plate  1 . For example, the lever  65  can be replaced by a spring-operated push button. 
     In  FIG. 12 , an alternate embodiment to the groove that comprises of a single or plurality of holes as discussed in above sections, the groove is replaced with a column  70  with slots  72  on the upper and/or the lower lips of the said column  70 . These columns  70  are arranged in vertical series along the upright panels  2 . This said column  70  utilizes a second part of the interlocking system that comprises of a hook mechanism  71  on the chair plate  1  depicted in  FIG. 13 . 
     Another embodiment to the invention is a series of grooves are disposed on the outer surface on the said upright panels  2 . The addition grooves on outer surface upright panels  2  allows the installation of a food tray or grab rail on the adjustable chair. Grab rail is a term to describe a bar across a child, used in the absence of a food tray on an adjustable chair. For the purpose of simplicity, the term “food tray” will include “grab rail” throughout the application. 
     To accommodate a growing child, adjusting the position of the food tray such as lowering it as the seat plate is lowered is necessary to ensure proper seating alignment of the child at all time. The adjustable chair is modified to having grooves on the outer surface of the said upright panels  2 . As depicted in  FIG. 14   a  and  FIG. 14   b , a younger child is shown in  FIG. 14   a , to be seated on a seat plate on highest groove level, with the food tray  81  in the proper position. With a older child seated on a seat plate at lower groove level in  FIG. 14   b , the food tray need to be lowered respectively to ensure proper seating for the older child. Otherwise, if the food tray remained in the position similar to the younger child, the food tray would be approximately at the upper chest level of the older child, a position not optimal for normal eating posture. 
     In  FIG. 15 , the food tray  81  is places at the highest groove level position on the adjustable chair. A series of grooves  83  is aligned along the outer surface of each upright panels  2 . It is to be noted that the distance between each groove along the outer surface of upright panels  2  is determined with respect to the distance of the grooves on the inner surface of said upright panels  2  so that proper seat-tray alignment can be achieved at every height. 
     As an alternate embodiment, the said grooves  83  can be designed to fit a bracket  84  that can be can be attached or detached from one groove to another at different level when adjustment is desired. This is depicted in  FIG. 16 . The food tray  81  will have a single or a plurality of holes and said bracket  84  will have a single or a plurality of tabs or vice versa, to achieve interlocking and an optional lever tension  87  to depress the tab(s) when the food tray slides into the said bracket  84 , and the said lever tension is released to lock the food tray in place. It is also noted that locking mechanism can be of various designs, sizes and shapes with the intent to lock food tray in place. For example, the lever tension  87  can be replaced by a spring operated push button to depress the tab(s) when the food tray slides into the said bracket  84 . 
     Another alternate embodiment of the groove is to have a single tab  86  or a plurality of tabs on each groove, with a lever tension  88  mounted along tabs connecting the said tabs along the series grooves. The said lever tension  88  depresses and releases the tabs  86  during the position adjustment of the food tray. This embodiment is depicted in  FIG. 17 . It is to be noted that the said lever tension can be located at other positions, not limited to one, shown in  FIG. 17 . 
       FIG. 18  is the posterior view of the alternate embodiment of the grooves shown in  FIG. 17 . In  FIG. 18 , the said lever tension  88  is shown as a long extension connecting the tabs  86  on the grooves. When depressed, the tabs are lowered into the floor of each groove, thereby allowing the food tray to slide into position. Once the desired position is obtained, the lever tension  88  is released and the said tabs will rise to lock the food tray in place. It is also noted the said lever tension  88  can be of various designs, sizes and shapes with the intent to lock the food tray in place. 
     It is to be noted that this embodiment can be of a separate unit mounted to the outer surfaces of the upright panels  2 , as opposed to being carved onto the upright panel. It is to be noted that this unit can be mounted on the inner surfaces of the upright panels as well if indicated or desired. The invention can also be fitted into any type of adjustable chair, regardless of its shape and design, as long as the purpose is to maintain optimum height between the seat and the food tray.