Split back dental chair apparatus
United States Patent Rasmussen 1 1 Apr. 15, 1975 [54] SPLIT BACK DENTAL CHAIR APPARATUS 1,260,032 3/1918 Pcrpick 297/410 1,867,600 7 1932 S h k f 297 ll [75] Inventor: Keith 0. Rasmussen, San Francisco, I c warz Op 0 C&#39; lf.  
  a l Primary Examiner-Casmrr A. Nunberg [73] Assignee: Hek Manufacturing Company, Inc., Attorney, A nt, r Firm s happ and Hatch San Francisco, Calif.  
 [22] Filed: July 30, 1973 [57] ABSTRACT [21] Appl. No.: 384,013 A dental chair conversion apparatus capable of use as a lounge-type chair and having an adjustable head rest mounted on an elongated plate with a rack formed [52] U.S. C1 297/410, 297/408 thereon and with the plate and rack Slidable in a [51] Int. Cl A47c 7/36; A47c 7/42 Field of Search 297/410 396 408 4l0 bracket which 18 mounted in the keyway of a conventional back support of the dental chair and fixedly [56] References Cited held there by a screw. A latch having a pro ection 15 pm mounted through ears on the bracket and spring UNITED STATES PATENTS biased to permit manual operation of the latch to se- 942,603 2/190 Undcland 4 97/ 10 X lectively engage the rack in ratchet fashion, to permit 955.094 4/19l0 MCNCC&#39; 297/7&#39;10 X manual adjustment of the height of the head rest. 1,078,828 11/1913 Campbell.... 297/410 X 1,196,413 8/1916 Yohe 297/410 2 Claims, 4 Drawing Figures PATENIEDAPR 1 51915 FIE--3 SPLIT BACK DENTAL CHAIR APPARATUS BACKGROUND OF THE INVENTION The present invention relates to a SPLIT BACK DENTAL CHAIR APPARATUS. and more particularly to a kit for converting the back of a conventional chair to a split back configuration.  
  Various conventional dental chairs havebeen constructed to have a single back and a bifurcated or curved pad head support. Dental chairs of this type manufactured by the SS White Company are characteristically constructed so that the bifurcated or curved pad head rest is coupled to mechanical linkages mounted on a back support of the dental chair. Such head rest assemblies have been also used for prosthetic operations by dentists.  
  The linkage mechanism of such a chair and its bifurcated or curved pad head support however. causes a widening of the profile of the dentists chair. It has been found desirable to permit the dentist to operate on the patient in such a manner that the patients head is directly above the dentist&#39;s lap. This permits the dentist to sit down while performing his operation on the patient. To facilitate this ease of operation. it has become necessary to convert the back of the dentist&#39;s chair to a thin profile split back configuration.  
 SUMMARY OF THE INVENTION The apparatus of the present invention may be in the form ofa kit to convert the head rest assembly ofa conventional dental chair such as the kind manufactured by the SS White Company into a thin profile split back configuration to be used as a lounge-type chair. In effect. the apparatus splits the back of the chair to provide a flattened head rest adjustable with respect to the back rest portion to vary the length of the back. The apparatus comprises a head rest mounted on an elongated plate with a rack formed on the plate. The elongated plate is proportioned to be slidable through a bracket which is mounted in the keyway of the back support member mounted on the seat frame of the dental chair. The bracket is fixedly held in the keyway by a screw. A latch having a projection is pin mounted on the bracket and spring biased to selectively engage the teeth of the rack. The latch may be manually disengaged from the rack to permit selective adjustment of the height of the head rest.  
  This apparatus may be in the form of a kit which may be used to convert conventional dental chairs such as the kind manufactured by the SS White Company by removing the conventional bifurcated or curved pad head support and mechanical linkages which are secured in the keyway of the back support on the chair. The bracket of the present invention may be slid into the keyway of the back support and fixedly held there by a screw. The bracket may then be screwed directly to the back of the seat and the slidable elongated member mounted on the head rest may be slid through the bracket to obtain the split back configuration.  
  Accordingly, an object of the present invention is to provide a thin profile split back dental apparatus.  
  Another object is to provide a kit for converting the back of a conventional dental chair such as the type manufactured by the SS White Company to a thin profile split back configuration.  
  A further object of the invention is the provision of bracket means for supporting a head rest and slidable in the keyway of a dental chair.  
  Still another object is the provision in apparatus of the character described ofa latch which is pin mounted on a bracket and having a projection for selectively engaging the teeth of a rack mounted on an elongated plate formed for supporting a head rest.  
  Further objects and advantages of the present invention will become apparent as the specification proceeds. and the new and useful features thereof will be fully defined in the claims attached hereto.  
 BRIEF DESCRIPTION OF THE DRAWINGS The preferred forms of the present invention are illustrated in the accompanying drawings, forming part of the specification, in which:  
  FIG. I is a fragmentary perspective view of a dental chair with the split back configuration shown in solid and the conventional swingable head support and linkage shown in phantom;  
  FIG. 2 is a side elevational view of the back portion of the apparatus of the present invention showing the thin profile achieved thereby;  
  FIG. 3 is a sectional view taken substantially along the plane of line 3-3 of FIG. 2; and  
  FIG. 4 is a sectional view taken substantially along the plane of line 4-4 of FIG. 2.  
  DESCRIPTION OF THE PREFERRED EMBODIMENTS I Referring now to FIG. 1, there is shown a dental chair 10 having a head rest 11 mounted on an elongated plate 12 which is slidable in a bracket 13. The plate 12 has a rack 14 as shown in greater detail in FIGS. 2 and 4 and the bracket 13 has a latch 16 which is biased by a spring I7 to urge the projection 18 of the latch to engage the rack 14 in ratchet fashion. The latch 16 may be manually pivoted by an ear 19 formed thereon around a pivot pin 21 to disengage the projection 18 of the latch 16 from the rack 14 to thereby permit the height of the head rest 11 to be selectively adjusted to any desired level.  
  The apparatus is readily adaptable to conventional dental chairs such as the kind manufactured by the SS White Company and copies thereof having a back support 22 with a keyway as shown in FIG. I. A conventional swingable head support 23 is supported by linkages 24 and 26 which are mounted in the keyway. The linkages may be removed and the bracket 13 may be slid in the keyway and secured therein by a screw 27 as shown in FIG. 3. The bracket itself may be secured to a back 28 of the dental chair by screws 29.  
  Hence the apparatus of the present invention permits the dental chair to be converted to a thin profile split back configuration as shown in- FIG. 2 from the&#39;conventional thick profile configuration having a bifurcated or curved pad support assembly with swingable linkages as shown in phantom in FIG. I. This permits the dentist to operate on the patient while the patient&#39;s head is directly above the dentist&#39;s lap to thereby permit the dentist to sit down while operating on the patient.  
  Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.  
 I claim:  
  1. A thin .profile split back conversion for a dental chair having a frame including a tiltable back support member formed with a keyway for slidably supporting a backrest and an articulated headrest. said conversion comprising a bracket formed for slidable mounting in the keyway of the back support member and having a second keyway formed therein;  
 means for adjustably securing said bracket in said first named keyway;  
 a thin profile backrest secured to said bracket;  
 a thin profile headrest havingan elongated tongue slidable in said second keyway and formed with a claim 1 and wherein said bracket is of substantially U- shaped cross section opening toward said backrest, and mounting ears are formed at the corners of said bracket for rigidly securing to said backrest.  
 2. A thin profile split back conversion as described in