BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention relates to an adjustable back pad, and more particularly to a back pad which can be emplaced on a chair back to reduce a pressure exerted to a lumbar vertebra or a back, thereby mitigating fatigue and soreness caused by an improper sitting posture.

b) Description of the Prior Art

A back of an ordinary office chair or vehicle chair is mostly fixed and cannot be adjusted. Therefore, it is easy to result in waist soreness and back pain to a user after a long time of use. Although most users will put a cushion on the chair to soothe a pressure exerted to a lumbar vertebra, the cushion is not equipped with an elastic buffering function, and thus, when a vehicle is running on a bumpy road, it is easy to cause lower back pain and fatigue from an improper sitting posture to the user.

SUMMARY OF THE INVENTION

Accordingly, the primary object of the present invention is to provide an adjustable back pad, wherein a novel back pad to improve the shortcoming of a conventional cushion or back rest that the waist soreness and back pain to the user cannot be overcome completely and efficiently. The elastic back pad can be used to adjust an up, down, left, right position of the back rest to adapt to the users of various body shapes; whereas, a design of a dual back rest uses a hollow ventilation structure, so that the user can feel more comfortable. The present invention is primarily characterized in that rear sides of the back rests are provided with plural elastomers and elastic elements to mitigate the pressure exerted to the lumbar vertebrae and to modify the sitting posture, thereby soothing a phenomenon of waist soreness and back pain.

To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments,

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of the present invention.

FIG. 2 shows an exploded view of the present invention.

FIG. 3 shows a rear schematic view illustrating actions of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 and FIG. 2, an adjustable back pad of the present invention comprises a back rack 10 and two back rests 20, wherein the back rack 10 is in a shape of an L if viewed from a side, a fold plate 11 at a bottom thereof can be extended into a seam of an ordinary chair to clamp the back rack 10, a rear side of the back rack 10 is provided with at least one set of slot holes 12 that are left-and-right symmetric (three sets in FIG. 2), inner sides to the symmetric slot holes 12 are provided respectively with an elastomer 13 which is a U-shaped elastic object with a buffering function, and a proper position above the back rack 10 is clamped with a strap 14 which can bind the back rack 10 on all kinds of back rests of chairs.

A back plate of each symmetric back rest 20 is provided with plural openings 21 for ventilation. As shown in FIG. 2, a rear side of each of the two back rests 20 is installed with an elastomer 22 which is a U-shaped elastic object with a buffering function. A center of the elastomer 22 is provided with a lock hole 221, and a screw A first penetrates a washer A1 and then passes through one slot hole 12 of the back rack 10, followed by being locked into the lock hole 221 of the elastomer 22 on the back rest 20. Thus, the two back rests 20 can be locked symmetrically on the back rack 10 as shown in FIG. 1). Furthermore, a lower side of the elastomer 22 on the rear side of the back rest 20 is installed with an elastic element 23 which can be an elastic object with a buffering function or can be formed by a spring 231, a flexible tube 232, a fixing plate 233, a screw 234, a washer 235 and a fixing seat 236, wherein the fixing seat 236 and the back rest 20 are connected as one unit, the screw 234 penetrates the washer 235 and then passes through a through-hole 2331 of the fixing plate 233 to be locked into a lock hole 2361 of the fixing seat 236 for positioning, the fixing plate 233 is provided with plural clips 2332 to clamp the spring 231, and an exterior side of the spring 231 is then sheathed with the flexible tube 232, thereby forming the elastic element 23.

Referring to FIG. 3, when the adjustable back pad of the present invention is put on an ordinary chair, in order to adapt to users of various body shapes and weights, the back pad can adjust an up and down or a left and right position of the two back rests 20, as follows:

- 1. If the up and down position of the back rest 20 is to be adjusted, the screw A and the washer A1 at the rear side of the back rack 10 can be dismantled first, and after the up and down position of the back rest 20 has been adjusted, the screw A is transfixed into the washer A1 again, followed by penetrating the other slot hole 12 of the back rack 10. Finally, the screw A. is locked into the lock hole 221 of the elastomer 22 on the back rest 20, which accomplishes the adjustment of the up and down position of the back rest 20.
- 2. if the left and right position of the back rest 20 is to be adjusted, only the screw A at the rear side of the back rack 10 needs to be loosened and then the left and right position of the screw A in the slot hole 12 of the back rest 20 is adjusted transversally. Finally, the screw A is locked tightly. Thus, the left and right position of the back rest 20 can be adjusted quickly. On the other hand, a periphery of each slot hole 12 of the back rack 10 is provided with a scale B, and therefore, when the left and right position of the back rest 20 is to be adjusted, the left and right position of the back rest 20 can be adjusted accurately according to a position of the scale B.

There are a total of ten elastic buffering pivots between the two back rests 20 and the back rack 10. Among the ten pivots, two pivots are provided respectively on the elastomer 22 of one back rest 20, and so there are a total of four pivots for the two back rests 20. Each elastomer 13 on the back rack 10 is provided respectively with two pivots, and hence, there are a total of four pivots for the two elastomers 13. The elastomer 23 of each back rest 20 is provided respectively with one pivot, and thus, there are a total of two pivots for the two back rests 20, Accordingly, there are a total of ten elastic buffering pivots between the two back rests 20 and the back rack 10, these pivots are provided with an excellent elastic supporting function for a waist and a back of the user.

In conclusion, the present invention provides an adjustable back pad which is an ergonomic back pad and put on an ordinary chair back to provide the user with a most comfortable and best elastic buffering function, in addition to being provided with a ventilation function, Therefore, the present invention is able to mitigate the pressure exerted to the lumbar vertebra or the lower back actually and effectively, modify the sitting posture of the user, and even soothe a phenomenon of fatigue and soreness.

It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.