US2591119A - Dental machine control - Google Patents

Description

April 1, 1952 J. A. BIGGS DENTAL MACHINE CONTROL Filed July 6, 1950 Patented Apr. 1, 1952 UNITED STATES PATENT OFFICE.

DENTAL MIACIIINE CONTRQL Justin Allen Biggs, J acksonville. 111.

Application July 6, 1950 Serial No. 17 2,,330

My invention relates to mercury switches for dental machines and has to do with a means of automatically turning on and shutting off the electric current.

An object of this invention is to make it convenient; practical and serviceable for a dentist to operate a dental drill throughout the hours of his daily dental service without having to keep his feet constantly pressing on a foot switch in a certain position to keep the drill going.

In the construction of a dental machine there are hingedly connecting extension arms that are normally moved hingedly to an upright position when the drill is shut off but are tilted down to an extended position when the operating drill is turned on and in use.

It is therefore my particular purpose of this invention to provide a very effective comfort for a dentist wherein he will be able to work as he stands in any desired working position around his dental chair without the tiring and nerve testing experience of trying to keep one foot in a certain position all daylong on a foot switch.

I achieve the purposes of my invention by the device described in the specification, defined in the claim and shown in the drawings wherein:

Fig. 1 is a perspective of my mercury switch secured to a drill support arm.

Fig. 2 is a detail in an exploded view showing the relative operating position of the several parts of my mercury switch.

Fig. 3 is a side view of my switch and its supporting arm when the drill is shut off with the extension arm upright in position on a hook. The dotted lines show this arm in position for use where the switch will energize the drill.

Fig. 4 shows a quarter section interior detail in perspective.

I shall now disclose the essential convenient and novel features of my invention as I point out the ease and comfort with which it is operated.

Dentists heretofore have had to stand from hour to hour with one foot on a drill energizing switch in order to do his work on teeth; but now with my new mercury switch the instant he lifts the drill off its supporting hook then he moves it over in an extended position toward his patient where the drill support arm tilts forwardly and downwardly causing the mercury in my switch to energize the drill ready for drilling and ready to keep it running until the dentist is ready to shut it off, without in any manner controlling its energizing switch with his foot.

I shall now show how I accomplish this outstanding improvement with my device.

1 Claim. (CI. 32-26) It is first essential that I provide. a sturdy mounting for support of my switch and I therefore removably secure my cylindrical drum I to the inside of its bracket housing 2 in a manner permitting drum I to beturned to right'or-left slightly on its axis 3 when-needed.

Housing 2 is preferably clamped or bolted; to drill support arm 4; down about the elbow 5 thereof to make a good firm operative support for'it on arm 4 at a position where no swivel action will be required as is the case normally with the middle portion 6 of arm 4, to permit a greater freedom of movement of a dentist's drill 'I when in use, since the middle portion 6 of arm 4 will freely swivel in its connection with elbow 5 of arm 4.

Housing 2 may well be held to arm 4 elbow 5 by a set screw 8 engaging a clamp strap 9 about elbow 5 of this arm 4, so that in this operative position the mercury switch unit may function correctly.

Since housing 2 is secured to elbow 5 of arm 4 it turns only with arm 4 and that is when drill I is lifted into a position for use oiT of its support hook on the dental machine, not shown.

Yet the amount of movement of housingZ is but little even with arm 4.

Note that drum I has a pair of opposed pockets Ill and II containing mercury I2 and I3 respectively. A wire I4 having one end I5 secured to drum section I6 contacts mercury I2 through its securing point II; while the other end I8 of wire I4 contacts mercury I3 through its securing point I9.

While housing 2 is fixed on elbow 5 of arm 4, yet drum I is slightly movable rotatably on its axis 20 within housing 2.

Here, it will be noted that drum I has a simple and handy means for adjusting it slightly for a setting as needed. The means for selectively setting the rotated position of drum I is provided in a claw 2| with finger 22 thereof engaging a peripheral recess 23 and fingers 24 and 25 gripping the side 25 of drum I; while the control axis 27 of claw 2! resting in an insulation bearing 28 of housing 2 has a thumb and finger knob 29 by which the adjusting claw 2| is turned for a selective setting.

In drum I is a central plate 36 of insulation material and is provided with a peripheral aperture 3I, and this plate is fixed in its central position in drum I to define an insulating partition plate 30 between mercury pocket I0 and opposed mercury pocket II for mercury I2 and I3 respectively.

Note then that a dentist who is tall need not extend drill support arm 4 as far as a shorter dentist would and that is why an adjustment needs to be made in the selected position of rotation of drum I, since when arm 4 is upright and not tilted to a position for use, then aperture 3'! will be set to a level above the mercury in pockets I and I I where the drill will not be energized; but when the dentist lifts drill 1 off of its support hook 32, then arm 4 moving to an extended position downwardly and outwardly will cause drum I in housing 2 to turn that much with arm 4, thus tipping aperture 3| forward far enough to move it down under the mercury surface level where mercury I2 and I3 from opposed pockets I0 and II respectively will at once merge through this aperture 3| in plate 30 thus closing the drill energizing electric circuit through wire I4 whose adjacent ends are connected to mercury I2 and I3 respectively in pockets I0 and II respectively.

Wire I4 is connected with a source of electric energy (not shown) and the make and break mercury switch efiectively connects and disconnects wire I4 in its operative functioning with this source of electric energy for running drill 1.

Thus a lot of fatiguing annoyance and discomforture is eliminated by my new and novel construction and service of mercury switch.

I have described and now I claim as my invention:

A dental machine in combination with a mercury switch and comprising a jointed extension drill support arm, a dental drill rotatably operative at the free end thereof, a motor for actuating said drill and a cable establishing drill control connection between said motor and said drill, a mercury switch operatively supported at the elbow joint of said drill support arm in position where said arm cannot be extended from a folded position for operation without automatically energizing the drill.

JUSTIN ALLEN BIGGS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Dec. 28, 1934

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