Patent Publication Number: US-6702388-B1

Title: Ball chair with a securing device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a ball chair, and more particularly to a ball chair having a securing device to hold a ball-shaped cushion on a seat in position to enhance the safety of the ball chair. 
     2. Description of Related Art 
     A conventional ball chair is composed of a chair and a ball-shaped cushion. The chair has a seat plate with a top face and a partly-spherical passage defined in the top face of the seat plate to receive a lower portion of the ball-shaped cushion inside. By placing the ball-shaped cushion in the partly-spherical passage of the chair, a ball chair is achieved. However, when a user sits in the ball chair, the ball-shaped cushion is pressed to deform forward and then falls out of the partly-spherical passage such that the user easily falls from the ball chair. Additionally, when the ball chair is bumped or vibrated, the ball-shaped cushion rebounds and easily springs out of the partly-spherical passage. Therefore, the ball chair is not safe and not stable for the user. 
     The present invention has arisen to mitigate or obviate the disadvantages of the conventional ball chair. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide a ball chair with a securing device that avoids a ball-shaped cushion separating from a seat to whereby the ball chair is safe and steady. 
    
    
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate, reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a ball chair with a securing device in accordance with the present invention; 
     FIG. 2 is an exploded perspective view of the ball chair with a securing device in FIG. 1; 
     FIG. 3 is a side plan view of the ball chair with a securing device in FIG. 1; and 
     FIG. 4 is an operational side plane view of the ball chair with a securing device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIGS. 1,  2  and  3 , a ball chair with a securing device in accordance with the present invention comprises a seat ( 10 ), a ball-shaped cushion ( 20 ) and a securing device. 
     The seat ( 10 ) has a seat plate (not numbered) with a top face ( 11 ), a bottom face (not numbered), a front edge, and a rear edge, and has multiple legs ( 12 ), a dished passage ( 15 ) extending from the top face ( 11 ) to the bottom face, and a backrest ( 14 ). The multiple legs ( 12 ) are attached to the bottom face to support the seat plate and each leg ( 12 ) has a distal end and a wheel ( 13 ) attached to the distal end of each leg ( 12 ) to make the ball chair be moved easily. The backrest ( 14 ) upwardly extends from the rear edge of the seat plate to adapt to support a user&#39;s back. 
     The ball-shaped cushion ( 20 ) is made of resilient bladder and has a maximum diameter slightly larger than a maximum diameter of the passage ( 15 ) and a minimum diameter smaller than a minimum diameter of the passage ( 15 ), thus the ball-shaped cushion ( 20 ) rests on the seat plate such that a lower portion of the ball-shaped cushion ( 20 ) can protrude from the passage ( 15 ). Optionally, two connecting ears ( 16 ) are respectively formed on two opposite sides of the front edge of the seat plate for engaging with the securing device and each ear ( 16 ) has a through hole ( 162 ). 
     The securing device is attached to the front edge of the seat plate and is a guard rod ( 30 ) made of rigid material such as plastic rod, metal rod etc. The guard rod ( 30 ) has a main spar (not numbered) that is preferably curved and two end pieces somewhat perpendicular in a same direction to the main spar. Each end piece comprises a threaded end ( 31 ) with a flange ( 32 ) formed near the threaded end ( 31 ). The threaded ends ( 31 ) are respectively extended through the through holes ( 162 ) to secure the guard rod ( 30 ) to erect at the front edge of the seat ( 10 ) until the flanges ( 32 ) abut the connecting ear ( 16 ). Then, a nut ( 33 ) is mounted on the threaded end ( 31 ) to fasten the guard rod ( 30 ) on the seat ( 10 ). Thereby, the guard rod ( 30 ) holds at an upper portion in comparison with the lower portion of the ball-shaped cushion ( 20 ) in cooperation with the backrest ( 14 ) and the seat ( 10 ) to avoid the ball-shaped cushion ( 20 ) falling off from the seat ( 10 ), even when the ball chair vibrates. 
     With reference to FIG. 4, when a user sits on the ball chair, the ball-shaped cushion ( 20 ) is pressed to deform and biased to the front edge of the seat ( 10 ). The guard rod ( 30 ) stops the ball-shaped cushion ( 20 ) to further deform to avoid the malpositioning of the ball-shaped cushion ( 20 ), which may otherwise cause the user fall from the ball chair. Thus, the ball chair is safe and stable. 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.