Dentist's or other chairs

Details Dentist's or other chairs Dentist's or other chairs

1995-01-06

1997-07-08

Cuomo, Peter M.

Chairs and seats

Legrest or footrest interconnected to move relative to...

297 69, 297 84, 297330, 29735413, A47C 102, A61G 1502, A61G 1504, A61G 1506

Patent

active

056453132

DESCRIPTION:

BRIEF SUMMARY
This invention relates to jacks and to dentist's or other chairs.
There are times when it is desired to recline a dentist's or other chair completely, e.g. for use as an operating table for minor surgery. For such use it is desirable that the back rest, the seat and the leg rest should all be in the same horizontal plane. That contrasts with normal reclined use in which the seat tilts as the back reclines to a non-horizontal position. Electrically driven chairs,, for example, have only achieved the horizontal plane by use of two motors, one driving the back and leg rests and the other driving the seat. Known chairs, in which the reclining mechanism is driven by a single motor, suffer the problem, that as the back is reclined and the leg or foot rest is raised, the chair seat also tilts, so that to get all three flat, the back and the leg or foot rest must be positioned beyond horizontal to align with the chair seat. This usually produces a tilt of about 15 degrees to horizontal with the head lower than the feet.
Against this background, a first aspect of the invention provides a dentist's or other chair having a reclining mechanism interlinking the back rest, the chair seat and a leg or foot rest for raising and reclining the back rest, for tilting the chair seat, and for lowering and raising the leg or foot rest together, the mechanism including means for disengaging the chair seat so that with the chair seat disengaged and horizontal, the back rest can be reclined and the leg or foot rest can be raised both also to horizontal.
By disengaging the tilt mechanism, the chair may be reclined to a flat position which is horizontal, even if driven by a single electric motor.
In a preferred arrangement, said seat is mounted for tilting movement relative to a base, and the mechanism comprises a shaft mounted in the chair seat, a crank mounted fixedly on the shaft for rotation therewith and connected pivotally to the base, so that rotation of the shaft also tilts the chair seat.
In that arrangement, the means for disengaging the chair seat may comprise means for selectively disconnecting the crank from the base so that the leg or foot rest may be selectively raised without tilting the chair seat.
Conveniently, the mechanism may include a linkage comprising a crank mounted fixedly on the shaft for rotation therewith, an arm mounted for pivotal movement with the leg or foot rest and a link pivotally connected at one end to the crank and at the other end to the arm so that rotation of the shaft produces a pivotal movement in the arm to raise or lower the leg or foot rest.
In order that the dentist does not get, say, her or his knee trapped beneath the leg or foot rest when that is being lowered, the mechanism preferably includes a second arm mounted in fixed relationship to the first mentioned arm for movement therewith and against which the leg or foot rest is located so that it may be raised relative to the second arm or may be held back as the second arm moves in a leg or foot rest lowering direction.
If the back rest is merely pivoted, as it reclines it pivots about a different centre from that about which the patient's back pivots, namely her or his hip joints. This leads to the patient's back sliding on the back rest which is uncomfortable and may, for example, pull the patient's shirt out of her or his waist band.
To reduce this problem, the back rest preferably depends from a generally arcuate member which is mounted for arcuate movement so as to raise and lower the back rest, the arcuate member including gear teeth arranged around the arc thereof in engagement with a gear wheel driven by the electric motor, when engaged. If the arcuate member has a radius of about 9 inches and is correctly positioned the movement of the back will be about a centre approximately coincident with the patient's hip joints, so reducing or removing the sliding movement between the patient's back and the back rest.
In one arrangement, the generally arcuate member is mounted between rollers for said arcuate movement.
The mechanism p

REFERENCES:
patent: 3792905 (1974-02-01), Johnson
patent: 3804460 (1974-04-01), Leffler
patent: 4696512 (1987-09-01), Burnett et al.
patent: 5315726 (1994-05-01), Borenstein
patent: 5474359 (1995-12-01), Muffi

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