US 2280402 A
Description (OCR text may contain errors)
E. H. GREPPIN 2,280,402
DENTAL OPERATING LAMP April 21, 1942.
Filed Aug. 10, 1939 2 Sheets-Sheet 1 INVENTOR.
%z'sATTORNEYS April 1942- E. H. GREPPIN 2,280,402
DENTAL OPERATING LAMP Filed Aug. 10, 1939 2 Sheets-Sheet .2
M N FEW P g mil M INVENTOR. flnasiflfief nh I BY 2 z 8 4 r fig ATTORNEYS Patented Apr. 21, 1942 DENTAL OPERATING LAMP Y Ernest H. Greppin, Brighton, N. Y.,
assignor to Wilmot Castle Company, Rochester, N. Y., a corporation of New York Application August 10, 1939, Serial No. 289,444
This invention has to do with lamps and more particularly with lamps for providing a high intensity of illumination upon limited areas, such lamps being useful particularly for performing surgical operations, dental work, etc. An object of the invention is to provide a generally improved and more satisfactory and efllcient lamp of this character.
Another object is the provision of a lamp so designed and constructed that the beam of light projected therefrom will be confined or restricted in one direction, such as a vertical direction when the beam extends horizontally, so that the beam may be made to shine into and provide brilliant illumination within the mouth of a patient, for example, without falling upon the patient's eyes.
Still another object is the provision of such a lamp in which the beamof light, in addition to being vertically confined or restricted, is also horizontally expanded in a lateral direction to provide a relatively wide beam which, without readjustment of the lamp, will enter the mouth of a dental patient even when the patient moves his mouth through a considerable sideways range, as by turning his head.
A further object is the provision of improved color correcting means, especially adapted to an operating lamp but useful also in connection with any other lamp where it is desired to have a color value of higher fidelity than. that heretofore readily attainable.
To these and other ends the invention resides in certain improvements and. combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.
In the drawings:
Fig. 1 is a side elevation of a lamp constructed in accordance with a preferred embodiment of the invention; a
Fig. 2 is a fragmentary plan of the same;
Fig 3 is a central cross section taken axially through the preferred lamp;
Fig. 4 is a side view of the blocking screen and heat absorbing screen, seen from one direction;
Fig. 5 is a similar view of the same, seen from a different direction;
Fig. 6 is a face view of the lens employed in the lamp; and
Fig .7 is a diagram illustrating schematically the cross sectional shape of the beam produced by the lamp.
the lamp is shown mounted on a preferred form of support which includes, a first arm I I mounted to swing horizontally on a substantially vertical axis or shaft i3 which may be mounted on a wall l5 or on any suitable standard or support. The free end of the arm I I is connected by a substantially vertical pivot I! to a second arm l9 provided with a vertical pivot 2| on which is rotatably mounted a forked bracket 23. The arms H and I9 are preferably hollow, to accommodate electric wiring within them. At the ends of the two arms of the forked bracket 23, horizontal pivots 25 (Fig. 3) extend inwardly into a generally ring-shaped fixture 21 having a handle 29 by which the fixture may be conveniently ti ted. on the forked arms. The pivot pins 25 preferably are threaded into tapped openings in the ring 2! and are held against rotation elative to the ring by set-screws 3|, and when the ring is oscillated relatively to the forked arms 23, the movement is accomplished by the pins 25 turning in the arms 23. Friction washers 33 may be employed between the bolt heads of the pins 25 and the arms 23, to hold the parts frictionallv in any position to which they are set.
Mounted on the ring 21 is a lamp reflector of generally concave shape, indicated in general at 4!, preferably made of a single piece of metal having formed, integral with the concave reflecting portion thereof, a cylindrical flange or wall 43 seated within the central opening of the ring 2'! and held thereto by a series of screws 45.
Back of the cylindrical flange 43 lindrical flange 41 of slightly smaller diameter, joined thereto by a shoulder 48. Around the outside. of the flange 41 fits a cylindrical flange is a second cy- 49 on the bulb holder unit, which unit includes i The same reference numerals throughout the several views indicate the same parts.
a small casing 5| containing a lamp socket 53 in which a suitable incandescent bulb 55 is mounted. The flange 49 of the bulb holder unit may be removably held on the flange 41 of the reflector by any suitable means, such as a bayonet type joint, or by set-screws, or simply by friction. When the bulb holder unit is removed from the lamp, it is moved backwardly relative to the reflector unit, the bulb 55 passing out through a large opening in the back of the reflector unit, within the flange 41, and the parts are quickly and easily brought together again by a reverse movement.
The bulb 55 is supplied with electric current by means of a flexible cord 6| extending from the back of the bulb holder unit 5| into an opening at the top of the pivot 2| and downwardly through the same to a snap switch controlled by a button 63 mounted on the arm l9 beneath the pivot 2 I, the cord then extending through the hollow arm is, through a suitable recess formed at the Joint l1, and through the hollow arm ll until thecord emerges from the bottom end of the arm II, as shown at 61, and terminates in a prong plug 69 which may be thrust into any suitable socket 'H such as a socket formed in a lateral extension 'of the lower bracket 13 which holds ber of generally cylindrical shape surrounds the bulb 55, as indicated at 8| in Fig. 3. This cylinder may be made of anykind of so -called heat absorbing glass which is commonly available, such, for example, as the ferrous oxylate glass called Aklo" glass. The cylinder is preferably of such diameter that its rear end is seated on the shoulder 48, within the flange 43, as shown in Fig. 3. An opaque metal plate 83 extends across and closes the front end of the heat absorbing cylinder and is held in place by a series of coiled t-ensioned springs 85 connected at their forward end to ears 81 on the plate 83 and connected at their rear ends to studs 89 on the reflector unit. These springs 85, constantly tending to pull the heat absorbing cylinder 8| rearwardly, hold it seated firmly against the shoulder 48 of the reflector unit.
Where it is desired to use the lamp for dental work or similar purposes, the lamp is preferably provided with an opaque metal shield or blocking member 9| surrounding the heat absorbing cylinder 8|, as shown in Figs. 3, 4, and 5. This shield 9| has the shape best shown in Figs. 4 and 5, which are side views thereof taken from two different directions at right angles to each other. As seen, the shield is in general a cylinder of about the same length as the heat absorbing cylinder 8|, on two diametrically opposite sides. On two other diametrically opposite sides at right anglesto the long sides, the shield is cut back so as to be of comparatively short axial length, the edges of the cut back portions being oblique or approximately helical, as indicated at 93. The shield is so placed in the reflector that the cut-away sides of the shield lie in a plane passing along the optical axis of the unit and also passing through the pivot pins 25, while the long or full-length sides of the shield extend along those sides'which would be out by another axial plane at right angles to the pivot pins 25; Described another way, if the reflector unit is turned on its pivot on the forked arms 23 until the optical axis of the reflector unit is horizontal, then the cut-away sides of the blocki'ng member 9| are at the lateral sides of the heat absorbing cylinder 8! while the long or fulllength sides of the blocking member are at top and bottom ofthe heat absorbing cylinder, which cylinder now extends horizontally.
With this arrangement (again assuming for convenience of description that the lamp is turned so that its optical axis extends horizontally), the light which would otherwise pass from the fllament to the upper and lower parts of the reflector 4i, and which would be projected as the upper and lower parts of the reflected beam, is
blocked oi! by the long or full-length upper andlower walls of the metal shield or blocking member II. The light which passes laterally from the fllament, however, goes through the cutaway side walls of the shield SI, and is not intercepted thereby, but falls on the lateral side portions of the reflecting surface and is pro- Jected as a beam which, considered in cross section, is compressed or confined in a vertical direction (that is, in height) or flattened at top and bottom, due to the blocking effect of the member, 9|, but which is not compressed or flattened in a lateral or horizontal direction.
The purpose of blocking off the beam of light at both top and bottom, instead of at the top alone, is to provide a projected beam which is of the desired flattened form at its top, regardless of the distance from the reflector to the patient.
At some distance from the reflector, the light rays cross each other, and from that point onwardly, the rays forming the top half of the beam are those reflected from the bottom half of the reflector. By blocking off or flattening the beam both at top and bottom at the outset, it follows that the top of the beam falling upon the patients face will be flattened, regardless of whether he is placed inthe path of the rays before they cross or after they cross each other.
The front of the reflector unit is closed by a lens l0! extending across the front, and according to the preferred construction this lens I0! is formed with a multiplicity of difiusing ribs, approximately parallel to each other as indicated in the face view, Fig. 6, the direction of the ribs being in the direction of a plane passing longitudinally along the optical axis of the lamp and perpendicular to the pivotal axis defined by the pivot pins 25. In other words, these difiusing ribs will be arranged vertically when the lamp is so tilted on its pivots that its optical axis extends horizontally. Whenever the lamp is swung on its pivots, the diffusing ribs will still remain in vertical planes passing along or parallel to the optical axis and perpendicular to the pivot pins 25. These diffusing ribs may, within the scope of this invention, be of various sizes, although it is usually preferred to employ a great number of small ribs.
These diffusing ribs cause the beam of light passing through the lens llll to be diffused or spread in a lateral direction perpendicular to the length of the ribs; that is, in a direction horizontally lateral with respect to the optical axis, when the lamp is placed with its optical axis horizontal. Thus the beam of light is widened in a lateral direction by the use of these diffusing ribs, and as already described, it is narrowed or flattened in a vertical direction (when the optical axis is horizontal) by the use of the blocking member 9|. The combination of the diffusing ribs and the blocking member produces a resultant beam of light which is extraordinarily satisfactory for dental use for illuminating the oral cavity.
The characteristics of this beam of light are 11- lustrated schematically, in a general way, in the diagram constituting Fig. '7 of the drawings. The dotted circle Ill indicates the shape which the cross section of the projected beam of light would have, at any given transverse plane, if the diffusupon the face oi. a dental patient, the beam, due to being flattened or cut 03 at the top, will not fallupon the patients eyes, although it will fur- ,nish adequate and brilliant illumination at the area of the mouth and in the oral cavity. Due to the horizontal expansion or widening of the cross section of the beam of light, the beam need not be readjusted as the patient turns his head from side to side, and the mouth will still be within the brilliantly illuminated area of the beam even when it moves back and forth from side to side, through the normal extent of movement occasioned by turning the head from one side to the other. Hence, with this improved lamp, the dentist usually flnds it unnecessary to readjust the beam of light when the patient is required to turn his head one way or the other.
Another feature of the invention, particularly useful in a dental lamp or other operating lamp where reasonably true color values are desirable, is the feature of using, in conjunction with the heat absorbing screen 8|, a material which will correct some of the color deficiency caused by this screen.
The heatabsorbing cylinder, if made of the commonly available heat absorbing glass as mentioned above, will unavoidably absorb a substantially greater proportion of the visible light rays from the red end of the spectrum than those at other parts of the spectrum, and will thus shift the violet end of the spectrum. According to the present invention, means is provided for absorbing enough of the green rays to compensate roughly or approximatelyfor the excess absorption of the red rays by the heat absorbing cylinder, thus shifting the color value of the light thereon to be reflected thereby, a cylinder of light transmitting and heat absorbing'materiai surrounding said source of light and interposed in the path of travel of light therefrom toward said reflector, a cylindrically shaped blocking member of material opaque to light closely surrounding said heat absorbing cylinder and blocking the travel of part of the light from said source toward said reflector approximately along two diametrically opposite directions, to control the dimensions of the beam of reflected light projected from said reflector, and a light transmitting element interposed in the path of reflected rays projected from said reflector, said transmitting element being provided with a plurality of diil'using ribs.
2. A lamp as described in claim 1, in which said heat absorbing cylinder absorbs a greater proportion of light rays near the red part of the Bib the color value or the transmitted light toward passed through the heat absorbing cylinder or screen 8|. The green absorbing fllter can be made of cylindrical shape to surround the heat absorbing cylinder 8|, or it may be placed in any other desired or suitable location so that the light will pass through it either before or after being reflected by the reflector. In the preferred form, the lens "II which closes the front of the lamp unit constitutes the green absorbing fllter, this lens being made of suitable glass for absorbing a substantial proportion of the green rays. For instance, it may be made of glass containing selenium, or 01' any known glass having green-absorbing properties. It is found that the light from an incandescent light, bulb passing first through the heat absorbing glass BI and then through the green-absorbing lens I III will issue from the lamp in a beam having a color value greatly improved over that produced if the greenlxgsorbing filtering medium is omitted.
1. A lamp including a reflector, a source of a light associated with said reflector to cast light visible spectrum than those at other parts thereof, and in which said light transmitting element absorbs a substantial proportion of light rays near the green part of the visible spectrum to improve the color value of the transmitted light by compensating partially for the excess absorption of red by the heat absorbing cylinder.
3. A lamp including a reflector of generally concave shape with an opening near its center and a rearwardly extending annular flange sur rounding said opening, a bulb holding unit including an annular flange for detachable engagement with said flange on said reflector and means for holding a light bulb in position to extend into the interior space within said reflector, a heat absorbing screen of generally cylindrical form surrounding said bulb and having its rear edge seated within said flange on said reflector, and a metal shield surrounding said cylindrical screen and likewise having its rear edge seated within said flange on said reflector, said shield serving to block transmission of light rays from said bulb toward said reflector in two diametrically opposite directions and being cut away at its sides between said two directions to permit transmission of light rays from said bulb toward said reflector in diametrically opposite directions substantially perpendicular to the blocked directions.
4. A lamp including a reflector of generally concave shape with an opening near its center and a rearwardly extending annular flange surrounding said opening, a bulb holding unit including an annular flange for detachable engagement with said flange on said reflector and means for holding a light bulb in position to extend into the interior space within said reflector, a heat absorbing screen of generally cylindrical form surrounding said bulb and having its rear edge seated within said flange on said reflector, and a metal shield surrounding said cylindrical screen and likewise having its rear edge seated within said flange on said reflector, said shield being of approximately the full length of said cylindrical screen along two diametrically opposite sides and being cut away to be of materially reduced length along two other sides between said full length sides.
ERNEST H. GREPPIN.