Automatic waistrest adjusting device for office chairs

Abstract

An automatic waistrest adjusting device for office chairs includes a waistrest combined with the bottom of a backrest, and the waistrest comes with a design of connecting a curved flexible metal plate and making use of whose flexibility to suspend the bottom of the waistrest that can be turned flexibly with a user's waist to achieve an ergonomic stepless angular adjustment to allow the user's waist to lean at the most comfortable position. The waistrest adjusting device combines the waistrest and the backrest by simple components and assembling method, and achieves the effects of preventing poor performance and quality caused by an elastic fatigue and extending the use life.

Description

BACKGROUND OF THE INVENTION[0001](a) Field of the Invention[0002]The present invention relates to a waistrest adjusting device for office chairs, and more particularly to a waistrest adjusting device with a structure that connects a curved flexible metal plate to the bottom of a backrest for automatically turning and adjusting the angle of a waistrest.[0003](b) Description of the Related Art[0004]According to U.S. Pat. No. 7,303,232, shown in FIGS. 1A and 1B and filed by the applicant of the invention, a “BACKREST ADJUSTING DEVICE FOR OFFICE CHAIRS” includes a back frame 10. A waistrest 12 is mounted at the center 11 of the back frame 10. The waistrest 12 is flexibly moved back and forth within the center 11 of the back frame 10 by means of two pivots and springs positioned within a tube body 15. In this way, an angular adjustment is achieved.[0005]According to U.S. Pat. No. 6,843,530, a “MULTI-STAGE BACKREST ASSEMBLY” includes a back plate positioned on a support frame. A waist pla...

AI Technical Summary

Benefits of technology

[0007]Therefore, a primary object of the present invention is to provide an automatic waistrest adjusting device for office chairs for elastically adjusting an office chair with a user's waist according to the position of a human waist to achieve an ergonomic stepless angular adjustment of the office chair and provide the most comfortable leaning condition for an individual's waist.

[0008]Another object of the present invention is to provide an automatic waistrest adjusting device for office chairs that combines a waistrest and a backrest by simple components and assembling method to achieve high applicability and excellent elastic fatigue resistance to extend the using life.

[0014]Based on the above-mentioned configuration, the waistrest in accordance with the invention is displaceable up and down for height-adjustment with the movement of the backrest, thereby achieving the best ergonomic operation state.

Problems solved by technology

Regardless of a compression spring or a torque spring, the performance of the conventional waistrest adjusting device may be affected since the spring becomes elastically fatigue easily, particularly to the flexibility of the adjustment and the comfortability of an application.

Furthermore, the spring is installed on a shaft element, higher material and assembling costs are incurred, and the installed spring and shaft elements may produce frictional noises after a long time of use.

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