Seat back height adjustment mechanism

Claim 1

In a chair having a base, and seat means supported on the base for supporting a person seated in the chair, an improved backrest comprising: a. a back brace mounted to the seat means and having a generally vertical section having a plurality of generally vertically spaced notches; b. a tubular slide slidable over the back brace for vertical reciprocation thereon, the slide including a housing that defines generally rectangular horizontal and vertical non-intersecting channels; c. a generally rectangular plunger received within the housing horizontal channel for selected reciprocation therein for engagement and disengagement with the back brace notches; d. a pin attached to one side of the plunger and extending therefrom into the housing vertical channel; e. a generally rectangular latch received within the housing vertical channel for vertical reciprocation between extended and depressed positions relative to the slide, the latch defining an angled slot for receiving the plunger pin to thereby produce positive horizontal reciprocation of the plunger between the notch engagement and disengagement positions upon vertical reciprocation of the latch; f. a spring interposed between the housing and the latch to bias the latch and plunger into engagement with the back brace notches; and g. shell means mounted to the housing for providing a backrest, and said plunger means and slide arranged so that when the plunger means is engaged with the back brace notches the slide means is retained against movement relative to the back brace.