US 3813147 A
Disclosed is a dental apparatus comprising a chair-instrument tray combination, wherein the instrument tray is attached to the articulating backrest of the dental chair so that the tray follows the movement of the backrest. The support of the tray includes a parallelogram linkage which maintains the tray horizontally oriented as the backrest is moved between an upright and a reclined position. The tray support also includes a leveling mechanism for initially leveling the tray and adjusting it parallel to the true horizontal independent of the chair itself. This is to compensate for situations where the floor on which the chair rests is not level.
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Description (OCR text may contain errors)
United States Patent 11 1 Rick A 1451 May 28, 1974 DENTAL APPARATUS 75 Inventor: Mich el Ed ard IR k R h t 1, Primary Examiner james McCall 1 N Y a W 0c es C Attorney, Agent, or FirmTheodore B. Roessel; Roger Aceto  Assignee: Sybron Corporation, Rochester,
[57 ABSTRACT  Flled: 1972 Disclosed is a dental apparatus comprising a chair-  A N 296,094 instrument tray combination, wherein the instrument tray is attached to the articulating backrest of the dental chair so that the tray follows the movement of the  Cl. 297/191, 297/146 backrest The Support of the tray includes a parallel() lift. g linkage which maintains the y horizontally  of Search 9 61 oriented as the backrest is moved between an upright and a reclined position. The tray support also includes  References Cted a leveling mechanism for initially leveling the tray and UNITED STATES S adjusting it parallel to the true horizontal independent 2,098,426 11/1937 McDonald 297/191 X of the chair itself. This is to compensate for situations 3,009,737 11/1961 Burnett 297/146 where the floor on which the chair rests is not level. 3,049,374 8/1962 Nance 297/146 9 3,588,172 6/1971 McGregor 297 191 srclfllms, 2 Drawing Flgul'es .8 3a a a 3O BACKGROUND OF THE INVENTION The present invention relates to dental apparatus and more particularly to a dental chair-instrument tray combination, wherein the tray automatically follows the chair backrest as the backrest is moved between an upright and a reclined position.
Various dental chairs are known having an instrument tray or the like mounted to a support extending from beneath the seat of the chair. Such an arrangement permits the location of various dental instruments over the patient within easy reach of the dentist or his assistant. The support for the tray is usually capable of movement in both horizontal and vertical planes, so that the tray can be moved to a position most convenient to the dentist or assistant.
A primary disadvantage of the prior art trays is that once the tray is positioned for one patient and one particular dental procedure repositioning the patient, for example by raising or lowering the chair or moving the backrest between an upright and reclined position requires that the tray be manually repositioned. For example if the backrest is moved-between an upright and reclined position, the dentist or assistant must translate the tray horizontally so that it follows generally the head of the patient. Likewise, if the chair is tilted, or if the elevation of the chair is changed, the tray must be manually repositioned.
In the present invention, the tray is mounted for movement with the backrest in a manner which maintains the tray level as the chair is raised, lowered, or tilted or the backrest moved between an upright and reclined position. As the tray automatically follows movement of the backrest only minimal manual adjustment, if any, is required to properly position the tray.
SUMMARY OF THE INVENTION The present invention may be characterized in one aspect thereof by the provision of a dental chair having a movable backrest; a parallel motion linkage having oneend supported by. the seat of the dental chair and a second end operatively connected to the backrest for movement with the backrest; a cantilevered support arm carried by the second end of the linkage; a tray member supported on the outward extending end of the support arm; and means for adjusting the first end of the linkage for orienting the tray member to substantially true horizontal independently of the level of the dental chair.
OBJECT OF THE INVENTION One object of the present invention, is to provide a dental chair-tray combination wherein the tray is arranged to follow the movement of the dental chair backrest. t
Another object of the present invention, is to provide a dental tray attached to the movable backrest of a den tal chair together with means for maintainingthe tray substantially horizontally oriented as the backrest .is moved between anupright and reclined.
A further object of the present invention, is to provide a dental tray mounted to a dental chair in a manner which substantially eliminates the need for manually repositioning the dental tray as the chair is moved to various adjusted positions. A
A still further object of the present invention, is to provide a dental tray attached to a dental chair, including means for setting the tray at a true level position regardless of the floor level on which the chair is placed.
These and other object and advantages and characterizing features of the present invention will become more apparent upon consideration of the following detailed description thereof when taken in connection with the accompaning drawings depicting the same.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view partly broken away and in section showing the dental chairtray combination of the present invention with the chair backrest in a reclined position; and
FIG. 2 is a cross sectional view on a larger scale of a portion of the chair backrest taken along lines 22 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG. 1 shows the dental chair to include a conventional lift column 10 for supporting the chair ,above a floor surface. The upper end of the lift column'carries a seat frame member 12 which may be fixed to the column as shown or which may be pivotted to the column to provide for tilting of the dental chair seat indicated at 14. The dental chair also includes a back-rest member 16 which is arranged for movement between an upright and reclined position with respect to the seat. In the embodiment as shown in FIG. 1, this movement is provided by pivoting the chair backrest at 18 to an upstanding member 20 of seat frame 12. This pivoting arrangement is not part of the present invention andis merely shown to illustrate one way of arranging the backrest for movement with respect to the seat.
Carried at the rear end of seat frame 12is a leveling mechanism generally indicated at 22 to be described in further detail herein below. Upstanding from the leveling mechanism isa mounting knuckle 24. Mounting knuckle 24 forms one end of a parallelogram linkage, the other end of the linkage being formed by a support knuckle 26 wherein the mounting knuckle and support knuckle are connected by parallelogram linkage members 28. The operation of such a'parallelgram linkage is well known in the art and it should be sufficient for purposes of the present invention merely to say that the linkage acts to maintain orientation of support knuckle 26 substantially parallel to mounting knuckle 24 as the I support knuckle is moved vertically with respect to the mounting knuckle.
Support knuckle 26 is mounted in a recess 30 (best seen-in FIG. 2) at one side of backrest 16. A pivot mount 32 is carried by the support knuckle and extends outwardly from the. recess. Connected to this pivot mount for movement about the mount in a generally horizontal plane is a cantilevered support arm'34. The outwardly extending end of arm 34 is pivotted to an arm knuckle 36 (FIG l) which in turn supports one end of a parallel motion linkage arm 38. Arm knuckle 36 is arranged so that parallel motion linkage arm 38 may rotate in a horizontal plane whereas the linkage itself is desposed for movement in a vertical plane'The other end of parallel motion linkage arm 38 pivotally supports a dental instrument tray 40. It should be appreciated that support arm 34 may be omitted and the parallel motion linkage arm 38 with arm knuckle 36 connected directly to pivot 32. However, the addition of support arm 34 is desirable in that it increases the range of movement of the tray.
Accordingly, with the arrangement shown, tray 40 can be raised or lowered on parallel motion linkage arm 38 and can be pivoted about the axis connecting the tray to arm 38, about pivot 36 or about pivot 32. In addition arm 38 may be spring loaded or provided with a detent mechanism, both arrangements being well known in the art for maintaining the tray in any vertically adjusted position.
The means for making the tray follow the movement of the backrest is best illustrated in FIG. 2. In this respect the chair backrest is provided with a guide member 42 which forms a portion of recess 30. The guide member is provided with an elongated slot 44 which extends generally parallel to parallelogram link members 28. Support knuckle 26 is in turn provided with a guide pin 46 which extends into guide slot 44. Thus this guide pin keys the support knuckle to the chair backrest so that the knuckle automatically follows movement of the chair backrest as it moves between an upright and a reclined position. The pin is also free to translate in slot 44. For example, as the chair backrest is lowered, the guide pin translate in the slot upwards toward the head end. In this manner the instrument tray is automatically adjusted as the chair backrest is lowered. When the chair backrest is raised, the guide pin translates toward the seat and the instrument tray automatically follows. The parallelogram link members 28 being anchored at one end to mounting knuckle 24 insures that the pivot 32 on support knuckle 26 is kept horizontally oriented as the chair backrest is raised or lowered. This in turn, maintains the horizontal orientation of instrument tray 40.
Since the floor of the dental operatory may not necessarily be level, the present invention allows for a level adjustment of the tray independent of the chair. With this arrangement the chair may be located in the dental operatory and then the tray support adjusted to a true horizontal position. Adjustment is accomplished by the tray leveling mechanism generally indicated at 22. This mechanism includes a spherical socket 48 either attached to or formed integral with seat frame 12. A ball member 50 rides in the socket and has an upstanding portion 52 which extends through the socket and connects to mounting knuckle 24. Any suitable means such as a locking nut 54 threaded to a flange 56 of the socket holds the ball firmly in position.
In operation, then, once the chair is located in th dental operatory, locking nut 54 is losened to permit a tilting of the mounting knuckle 24 by rotating the ball in spherical seat 48. This movement of the mounting knuckle is in turn translated through parallel link members 28 to support knuckle 26 which moves to tilt arm 34. In this manner the tray can be adjusted to true hori zontal after which the locking nut is tightened to hold the ball firmly in socket 48.
Thus, it should be appreciated that the present invention accomplishes its intended objects in providing a dental chair tray combination having means to automatically cause the dental tray to follow the movement of the dental chair backrest and which maintains the tray horizontally oriented during such movement. This represents a considerable savings in time and energy to the dentist because the need for manual tray adjustment is minimized and in many cases eliminated. Since the guide pin 46 is keyed to slot 44, the mechanism which holds or locks the chair backrest at any adjusted angle, also holds the instrument tray at a particular level. Accordingly no separate lock mechanism is required for holding parallel link members 28 in a vertically adjusted position corresponding to the inclination to the backrest. Further, the tray leveling mechanism 22 provides means for orienting tray 40 to a true horizontal position independent of the level of the operatory floor and therefore the position of the dental chair. Since dental trays are customarily are very shallow, permitting the orientation of the tray to a true horizontal position eliminates the danger of any implement placed on the tray rolling or sliding off the tray and on to the floor.
Having thus described the invention in detail what it is claimed as new, is:
1. Dental apparatus comprising in combination:
a. a dental chair having a seat frame and a backrest frame, said backrest being supported for deflection between an upright and a reclined position;
b. a parallel motion linkage having a first portion supported by said seat frame, and a second portion rotatable by said linkage in concert with said backrest as the latter is deflected between an upright position and a reclined position; and
c. a horizontally oriented tray member carried by said second portion, said tray being maintained horizontally oriented by said linkage as said second portion rotates in concert wtih said backrest frame.
2. A combination as set forth' in claim 1 including means for rotating said second portion in concert with said backrest comprising:
a. a guide plate on said backrest having a slot therethrough extending generally'parallel to said parallel motion linkage; and
b. a guide pin fixed to said parallel motion linkage second portion and extending slidably through said slot.
3. A combination as set forth in claim 2 wherein said guide plate forms a wall of a recess in the side of said backrest, said parallel motion linkage being generally located in said recess.
4. A combination as set forth in claim 1 including a horizontal support arm pivoted to said parallel motion linkage second portion for movement in a horizontal plane, said tray being carried by said support arm.
5. A combination as set forth in claim 4 wherein said support arm includes a parallel motion linkage capable of movement in a vertical plane.
6. A combination as set forth in claim 1 including adjustable means at said parallel motion-linkage first portion operablethrough said parallel motion linkage for adjusting said tray to a true horizontal position independent of the level orientation of said chair on the floor of a dental operatory.
7. A combination as set forth in claim 6 wherein said adjusting means comprises:
a. a socket provided adjacent the rear of said seat frame;
b. a ball member adjustably positioned in said socket;
said ball having a upstanding member supporting said parallel linkage first portion; and c. lock means for fixing said ball in said socket in an adjusted position.
8. Dental apparatus comprising in combination:
a. a dental chair having a seat frame and a backrest frame, said backrest frame being supported for deflection between an upright and a reclined position;
b. a parallel motion linkage having a first portion supported by said seat frame and a second portion; 0. a guide plate on said backrest frame having a slot therethrough extending generally parallel to said parallel motion linkage; Y v d. a guide pin fixed to said parallel motionllnkage backrest frame.