Adjusting device of a chair

An adjusting device of a chair includes a base frame in which an inner frame has one end thereof pivotally connected to a front end of the base frame by a first pin and the other end of the inner frame is connected to a sound pin which extends through two first slots defined in two side walls of the base frame. A bracket is pivotally mounted to a rear end of the base frame by a third pin and a fourth pin extending through two second slots respectively defined in the side walls and fixedly connected within the bracket. An urging element is connected between a top plate of the base frame and a fifth pin which is transversely connected within the bracket via two fourth slots defined in the two side walls. A transmitting device is connected between the fourth pin and the second pin which is slidably connected between two first slots respectively defined in the two side walls. The transmitting device has a third slot defined therein for a quick release device extending therethrough such that when pulling a back portion disposed to the bracket, a seat portion disposed on the base frame can be pivoted about the first pin simultaneously.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an adjusting device and more particularly, 
to an improved adjusting device disposed in a chair such that a seat 
portion and a back portion can be adjusted simultaneously. 
2. Brief Description of the Prior Art 
A conventional office chair is partially shown in FIG. 1, the chair 
includes a seat portion disposed on a base frame 90 and a back portion 
disposed to a post 922 which is slidably received in a bracket 92 which is 
pivotally engaged to a rear end of the base frame 90 by a first pin 906. 
The base frame 90 is pivotally engaged to a chair support 912 which has an 
extending plate 91 extending radially therefrom for a spring 904 disposed 
between the extending plate 91 and an under surface of the base frame 90 
so as to provide a satisfactory feature. A first moving means 94 has one 
end thereof pivotally connected to the bracket 92 by a second pin 928 and 
the other end of the first moving means 94 has a first/slot 942, a second 
moving means 93 having one end thereof pivotally connected to a lug 916 
extending from the extending plate 91 and the other end of the second 
moving means 93 having a second slot 932. A control bar 96 extends through 
the first slot 942 and the second slot 932, the control bar 96 can fixedly 
position the first moving means 94 and the second moving means 93 by a 
rotation action, i.e. the control bar 96 performs as a quick release to 
control the first moving means 94 and the second moving means 93. Each of 
the first moving means 94 and the second moving means 93 includes of 
plurality of plates and each of the plates of the two moving means 94, 93 
are alternately overlapped with each other at the respective two ends 
having the first slot 942 and the second slot 932. An urging element 908 
is mounted to the first pin 906 and has two legs respectively contacting 
against the under surface the base frame 90 and the second pin 928. When 
operating the control bar 96, the first moving means 94 and the second 
moving means 93 move freely along the first slot 942 and the second slot 
932 respectively so as to adjust the seat portion 902 and the back portion 
924. After the desired positions of the seat portion 902 and the back 
portion 924 have been set, the control bar 96 is re-operated to fixedly 
position the first moving means 94 and the second moving means 93. 
However, when pushing the back portion 924, the seat portion 902 is 
maintained still unless a force is exerted downwardly to the seat portion 
902. Generally, a user adjusts the chair when he/she sits in the chair 
and, according to the above mentioned description, when the user exerts a 
force to the back portion 924 the seat portion 902 is maintained still, 
this puts the user in an unsatisfactory pose and his/her clothing will be 
pulled upwardly. Therefore, in order to adjust the seat to a desired 
status, the user has to use two different forces, one is exerted to the 
back portion 924 from the back of the user and the other force is exerted 
to the seat portion 902 from the posterior of the user. It is difficult 
for the user to exert the two forces separately when sitting on the chair. 
The present invention intends to provide an improved adjusting device which 
can adjust the seat portion and the back portion to a desired position 
simultaneously so as to mitigate and/or obviate the above-mentioned 
problems. 
SUMMARY OF THE INVENTION 
The present invention provides an adjusting device of a chair, which 
comprises a base frame having two side walls extending from a front end 
thereof, each of the side walls having a first slot and a second slot 
defined therein, a top plate connected across the two side walls and an 
open rear end. A fourth slot is defined in each of the side walls and is 
located above the second slot corresponding thereto. An inner frame 
received between the two side walls has a front end thereof pivotally 
received between the two side walls by a first pin and a rear end of the 
inner frame fixedly connected to a second pin which extends through the 
two first slots of the base frame. 
A bracket has two lateral plates pivotally mounted to the two side walls by 
a third pin extending through the two side walls and the two lateral 
plates, a fourth pin extending through the two second slots and the two 
lateral plates. A fifth pin extends through the two fourth slots and is 
connected between the two lateral plates. One end of an urging element is 
connected to the fifth pin and the other end of the urging element is 
connected to an under side of the top plate of the base frame. 
A transmitting means is connected between the second pin and the fourth 
pin, and comprises a plurality of long plates each having a third slot 
defined therein for a quick release means extending therethrough which is 
slidably received in the first holes. The quick release means comprises a 
rod extending through the third slots and an operating handle is connected 
to the rod and extends laterally from one of the side walls so that the 
long plates are released by operating the operating handle. A back portion 
is connected to the bracket and can be pulled by the fourth pin sliding 
along the second slots and thus pushing the transmitting means to force 
the second pin to slide along the first slot such that the base frame is 
rotated about the first pin accordingly. 
It is an object of the present invention to provide an adjusting device of 
a chair and which has a simple structure. 
It is another object of the present invention to provide an adjusting 
device of a chair which allows a user to adjust the back portion and the 
seat portion simultaneously. 
Other objects, advantages, and novel features of the invention will become 
more apparent from the following detailed description when taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings and initially to FIGS. 2 and 3, an adjusting 
device in accordance with the present invention generally includes a base 
frame 10 having two side wall 11 extending from a front end thereof, a top 
plate 19 connected across the two side walls 11 and an open rear end. A 
seat portion 51 is fixedly connected to an upper surface of the top plate 
19. Each of the side walls 11 has a first slot 16 inclinedly defined in a 
middle portion thereof and a second slot 17 inclinedly defined in a rear 
end thereof. A fourth slot 110 is inclinedly defined in each of the side 
walls 11 and is located above the second slot 17 corresponding thereto. A 
first hole 18 is defined in each of the side walls 11 and is located 
between the first slots 16 and the second slots 17. 
An inner frame 20 has a front end thereof pivotally received between the 
two side walls 11 by a first pin 13 extending through the side walls 11 
and the inner frame 20, and a rear end of the inner frame 20 is fixedly 
connected to a second pin 24 which extends through the inner frame 20 and 
is slidably received within the two first slots 16 of the base frame 10. 
The inner frame 20 connects to a chair stand 22 (partly shown). 
A bracket 30 has an end board 301, two lateral plates 303 respectively 
extending from the end board 301 and a top portion 302 connected between 
the two lateral plates 303. The top portion 302 has an oblong hole 33 
defined therein for a post 52 received therein which is positioned by a 
screw element 34 and has a back portion 50 (FIG. 3) connected thereto. The 
two side walls 11 are pivotally received between the two lateral plates 
303 by a third pin 14 extending therethrough. A fourth pin 32 extends 
through the two second slots 17 and is fixedly connected between the two 
lateral plates 303. 
A fifth pin 31 is connected between the two lateral plates 303 via the two 
fourth slots 110 in the two side walls 11 and has a first tube 311 
extending perpendicularly therefrom to receive a first end of an urging 
element 60 therein. The top plate 19 has a second tube 191 disposed to an 
under side thereof and the second tube 191 extends downwardly and 
inclinedly from the under side of the top plate 19. A second end of the 
urging element 60 is received in the second tube 191. 
A transmitting means 44 comprising a plurality of long plates 441 is 
connected between the second pin 24 and the fourth pin 32, each of the 
long plates 441 having a third slot 442 defined therein for a quick 
release means 40 extending therethrough which further extends through the 
first holes 18. The quick release means 40 comprises a rod 43 extending 
through the third slots 442 and an operating handle 41 is connected to the 
rod 43, the operating handle 41 extending laterally from one of the side 
walls 11 for controlling the long plates 441 to clamp the rod 43 or not. 
When releasing the long plates 441 from clamping the rod 43 by operating 
the operating handle 41, the back portion 50 together with the rod 52 
connected to the bracket 30 can be rotated about the third pin 14 to slide 
the fourth pin 32 and the fifth pin 31 along the second slots 17 and the 
fourth slots 110 respectively, thus depressing the urging element 60 and 
pushing the transmitting means 44 to push the second pin 24 within the 
first slots 16. Because the front end of the inner frame 20 is pivotally 
connected to the base frame 10 by the first pin 13 and the rear end of the 
inner frame 20 is connected to the second pin 24 and, the inner frame 20 
is fixedly connected to the chair stand 22 such that when bracket 30 is 
rotated, only the base frame 10 can be rotated and the rear end of the 
base frame 10 together with the seat portion 51 are rotated about the 
first pin 13. 
Accordingly, the adjusting device allows a user to adjust the back portion 
50 and the seat portion 51 simultaneously and the structure of the 
adjusting device has fewer components compared to the conventional 
adjusting device as shown in FIG. 1. 
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.