CA1105078A - Electrically isolated illumination control for dental drill - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Control means for selectively energizing a lamp serving as an illumination source for an elongated fiber optics bundle has a first end positioned adjacent to said lamp and a second end mounted at the working end of a dental handpiece. The control means comprise signal generating means including switch means for generating an enabling signal upon an actuation of said switch means, applying means for selectively applying AC power to said lamp, and sensing means responsive to said enabling signal generated by said signal generating means and switch means for causing said applying means to couple AC power to said lamp. The signal generating means is electrically isolated from both the applying means and the sensing means to protect the user of said dental handpiece. The sensing means includes means for latching the applying means to the lamp in a coupling relationship with said lamp until a subsequent activation of the switch means for disabling said applying means.

Description

ELECTRICALLY ISOLATED ILLUMINATION CONTROL
FOR DENTAL DRILL.
This invention relates to fiber optic illumination systems, and particularly -to dental fiber optic illumination systems.
One of the most widely used and important tools employed by dentists and dental hygienists is the hand-held drill which is typically a hand-held piece specifically designed and having a shape which provides for proper orientation within the mouth of 'the patient without requiring any awkward or unusual contortions on the part of the operator in order to appropriately position the operating end of the hand-held drill piece for the purpose of. drilling, cu't'ting, polishing, buffing, hammering, 'tamping, and the like. The patient's mouth is a confined area requiring 'the skilled operator to exercise a high degree of care in the performance of demtal procedures. It is quite imperativethat 'the immediate region of concern be adeqraately lighted so that the operator is confident that he is performing the proper function in the proper location. This capability has been very adequately provided for in 'the form o:E an elongated fiber optic bundle having its proximal end positioned immediately adjareml, a source of illumination and having :its distal end mounted within the body of -the drill handpiece and positioned adjacent the output shaft o:E 'the drill to flood the area of concern with ligYrt of an adequate level vto permit 'the operator to perform the desired procedures in an assured manner.

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The articulated design of the handpier.e, tool and supply tray and every the dental chair enable these members to be easily manipulated and movable with the objectives of both patient comfort and operator efficiency in mind.
As a result, it is most advantageous and in many cases even necessary to place the lamp source and power unit provided therefor in some location where it does not interfere with the articulated equipment employed by the operator dura.ng the performance of normal dental procedures. Since the drill handpiece is normally utilized in an intermittent fashion, it is most efficient and economical to be able to turn the lamp source on and off in a simple and straightforward fashion.
This basic capability is adequately provided for as taught by U.S. Patent No. 3,758,951, issued September 18, 1973, and assigned to the applicant of 'the present invention, wherein a small, compact, lightweight unit identified therein as a remote control unit (RCU) is adapted to be positioned in -the immediate vicinyty of the work area, and which is provided with an on/off'switch within easy reach of the 'operator o enable quick and simple -turnoff or turnon of , ,the lamp source,-and wherein the small size of the remote control unit enables the unit to be positoned within easy reach of vthe operavtor (typically beneath the articulated 'tray) withowt in any way interfering with other apparatus in the vicinity or with the access of -the operator to such apparatus, The conventional approach for such on/off control means is -to provide an electrical circuit including switch means rnoun-ted within the remote control unit and coupled aaross a pair of conductive leads extending between the _~~.
' : . ,:_ v t remote control unit and -the illuminating lamp supply source.
The switch may be selectively turned on and o.ff in order to respecf;ively energize and deenergize 'the light source to convey light to the area of concern by way of -the fiber optics bundles.
Since water is continuously utilized during many of the dental procedures such as, for example, to cool the drill bit and -tooth during drilling, as well as to periodically rinse a drilled tooth to facilitate examination to determine the progress of any procedure, it is not only important but frequently required by both local and federal regulations that the level of electrical energy of any electronic components present in the :immediate working area be no greater -than 27. volts at virtually zero current to protect bath operator and patient from electrical shock or injury. With 'the apparatus of -the above-mentioned issued patent, -this is accomplished by providing a step-down 'transformer within -the housing of the supply source to reduce the voltage output derived fram,a conventional wall receptacle -typically rated at 115 volts AC, down to 'the above--mentioned voltage/current level.
Although -this technique reduces -the ou'tpu't power delivered -to the remote control unit, the danger of minor shock is still present. In additian thereto, -the we~.gh-t of -the step-down transformer required for -the above application; together with its size, makes the supply source unit unduly large arid heavy, serving to :increase -the cost of the equipment and x.mposing physical restrictions on both the ease of mounting -and the locations in, on or upon which the unit may be mounted.

According to the present invention, there is provided cone ral means for selectively energizing a lamp serving as an illumina-tion source for an elongated fiber optics bundle having a first end positioned adjacent to the lamp and a second ~' end mounted at the warking end of a dental handpiece, the control means comprising signal generating means including switch means for generating an enabling signal upon an actuation of the switch means, applying means for selectively applying AC power to said lamp, and sensing means responsive to an enabling signal generated by the signal generating means and switch means for causing the applying means to couple AC power to the lamp, the signal generating means being electrically isolated from both the applying means and 'the sensing means to pro'tec't 'the user of the dental handpiece and the patient, and the sensing means including means for latching the applying means to 'the lamp in a coupling relation-ship with the lamp until a subsequent activation of -the switch means for disabling the applying means.
The signal generating .means, switching means, applying means, and sensing means may -take many forms. For example, in one embodiment 'the strritching means comprises a pressure sensitive switch arranged in 'the air conduit of the dental handpiece: What is impor'tan't is that the AC
power is electrically isolated from the dentist and patient.
2n order that the invention may be fully understood, i-t wil7. now be described with reference to the accompanying drawings, in which:
Figure l shows a perspective view of a control apparatus designed in accordance with the principles of the present invention .

Figure la shows a sectional view o:E the remote control unit o.f Figure 1 looking in the direction of arrows la-la.
Figure 1b shows a sectional view of the remote control unit of Figure 1 looking in the direction o:~ arrows lb-lb.
Figure 2 shows a perspective view of another preferred emboidment o.f the present invention.
figure 3a shows a top plan view of a portion of another preferred embodiment of a remote control unit embodying the principles of the present invention.
Figure 3b shows a sectional view of the remote control unit of Figure 3a looking in the direction of arrows 3b-3b.
Figure 3c shows a sectional view of a modification of the remote control unit of Figure 3a looking in 'the direction of arrows 3b-3b .
Figures 3d and 3e shows still further preferred embodiments of the present invention employing battery powered electrical means for utilization in the remote control unit, wherein Figure 3e further employs level corntrol means of the type employed in Figures 3a:1-3c .
Figure 3:f shows still another embodiment of the present invention employing wireless carrier techniques.
Figure ~F shows a perspective view of s~t~.ll another pre:Eerred embodiment of the present invention in which 'the remote control function is in'tegra'ted into the dental handpiece.
Figure 4a shows a sectional view of the switch portion of -the handpiece of Figure ~t looking in 'the direction of arrows 4a-4a.

Figure 4b shows a detailed perspective view of the switch arrangement of Figure 4.
Figure 5 shows one typical dental unit for use in treating patients and 'the manner in which the apparatus of the present invention may be mounted with regard 'thereto.
Figure 6 shows a simplified perspective view of a cradle for supporting a dental handpiece and for automatically activating the maim light source.
Figure 6a shows a simplified schematic o.f an elec-trical circuit which may be employed with the cradle of Figure F~.
Figure 7 shows a block diagram of another embodiment o:E the control means.
Figure 7a shows a detailed block diagram of the phase shift control circuitry shown in simplified .form in Figure 7.
Figure 7b shows an alternative embodiment of a magnetically coupled isolator which may be used in place of the optically coupled isolator of Figure %.
Figure 8 shows a dental handpiece assembly which may be operated by the control circuitry of Figure 7, Figure 8a shows a pressure sensitive switch which may be used to control turnon and 'turnoff. of -the lamp.
Figure 9 is a perspective view of a stand alone :Fiber optics :illuminator embodying the principles of -the present invention.
Figure 10 shows a schematic diagram of another isolator circuit which may be employed to caup7-a the remote switch of Figure 7 to the taunt of -three counter o.f Figure '7 .
_6_ Turning initially to a consideration of Figure 5, there is shown therein a patient unit 10 comprised of a pedestal 11 upon which chair 12 is mounted in a fashion so as to be both tiltable and swingable upon pedestal 11.
A horizontally aligned arm 13 extends outwardly from pedestal 11 and to one side of chair 12,. A vertically aligned post 14 is mounted upon the free end of arm 13 and has a swivel arm 15 pivoted thereto so as to swing about pivot point 15a. The free end of arm 15 is pivotally connected to a second arm 16 swingable about pivot point 16a so as to enable . tray 17, mounted to the free arm of 16, to be positioned at a location convenient for the operator to place implement s and rr~aterials utilized during a dental procedure without leaving the patient's side. The housing 18 may be mounted on post 14 and is designed to house a variably intensity light source which is remote from the immediate work area, such mounting being accomplished through suitable mounting brackets or other securement means.
A remote control unit 19 is mounted upon tray 17 and is shown as being positioned immediately adjacent to the control panel 20a of a control housing 20 providing easy and immediate access for manipulation of -the dials and/or switches associated with control functions normally required in the dental work area. The remote control unit is typically provided with switch means in -the form of a manually operable knob 19a for turning the light source on or off and, in some preferred embodiments, for controlling the intensity of light emi-t-ted by the light source. In certain preferred embodiments, the remote control unit 19 is coupled to -the light source receptacle 18 by a suitable electrical cable or conduit,21 which may be clamped on post l~t and arms 15 and l6 at spaced intervals, for example as spawn by -the clamping means 22:

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The light sourr.e housed in receptacle 18 is preferably a lamp capable of utilizing conventional 115 vale AC power.
Although not shown in Figure 5 for purposes of simplicity, a blower is preferably provided within housing 18 for cooling the lamp. The blower is preferably turned on and off in conjunction with the lamp. Louvers 18a may be provided along one or more surfaces of the receptacle to aid in such cooling.
The lamp conveys light to the dental handpiece by means of a fiber optics bundles, -the proximal end of the fiber optics bundle being positioned immediately adjacent the lamp housed within receptacle 18 and the distal end -thereof being fixed to -the handpiece so as to be in close proximity to the drill mounted within the handpiece, as is described in detail in 'the above-mentioned U.S. Pa.-tent 3,758,951, and as shown for example in Figure 1 of the patent.
In alternate arrangement, as shown in Figure 4, the fiber optics bundle 23 may extend -through the body of the handpiece 2,4 and be divided into first and second branches 23a and 23b, whose distal ends 23a-1 and 23b-1 are positioned on opposite sides of the handp9.ece drill 25 so as to flood the region to be drilled with light.
Considering Figures 1 -through 1b, showing remote control unit 19 and a portion of receptacle 18, -the apparatus for controlling "on" and turnoff of the lamp utilizes fiber optics bundles and operates in 'the :following manner Receptacle l8 is provided with a separate small housing 30 divided into compar-tmer~~ts 30a and 30b by barrier wall 31. A first fiber optics btandle 32 has its proximal end 32a secured by bracket 35 to one face of cover plate _g-33 having an opening 33a. Compartment 30b houses an LED
34 coupled between the positive terminal of a voltage source and ground potential as shown. The distal end of 32b of fiber optics bundle 32 is secured to the top surface of remote control unit 19 by suitable mounting means 36. Although not shown, it should be under~~tood that 'the fiber optics bundle 32 may be housed within a separate protective sleeve.
Thus, light emitted from LED 34 is conducted through fiber optics bundle 32 to remote control unit 19 and through the opening 19c in top swrface 19b as shown best in Figure la.
Chamber 30a houses a phototransistor 37 having its collector coupled to the positive -terminal of a voltage source through resistor Rl and having i-ts emitter coupled to ground through resistor R2. The emitter of 37 is also coupled to the trigger input 38a of a bistable flip--flop 38 through capacitor Cl whose opposite -terminal is coupled to trigger input 38a and to ground potential 'through resistor R3.
The cover plate 39 of chamber 30a is provided with an opening 39a. The proximal end of fiber optics bundle 40 is secured to the upper face of cover 'plate 39 by mounting means 41. The distal end of 40b of fiber optics bundle 40 secured to one side face 19d of remote control unit 19 by a moumting bracket 43. Side face 19d is provided with an opening 19e.
The remote control unit 19 houses a reflective ! member 44 which re:Flec-ts light entering into housing 19 from fiber optics bundle 32 'toward fiber optics bundle 40 when an unobstructed ligYrt path is present. The condition of the light path is controlled by switch means 7.9a comprised of a slide member 46 having an upwardly extending manually operable projection 46a extending -through elongated slot 19f in upper surface 19b.
The slide member 46 is slidably guided between two downwardly depending arms 47 and 48, each having inwardly directed flange portions 4'la and 48a, respectively, forming slide grooves Gl and G2 which receive the opposite sides of slide member 46 as shown best in Figure 1b. By moving projection 46a in the direction shown by arrow 49, the right-hand portion thereof extends into the path PL of light emitted from fiber optics bundle 32 so as to prevent light from reaching reflective member 44 sa as to be directed -toward the distal end of fiber optics bundle 40.
By moving the slide arm projection in 'the opposite direction as shown by arrow 49a, the right-hand end of slide member 46 moves out of the light path PL enabling light from fiber optics bundle 32 to impinge upon the reflective surface of member 44 so as to be directed into -the distal end of fiber optics bundle 4U and -thereby conveyed by bundle 40 to impinge Upon phototransistor 37.
The current signal developed 'by photot:ransistor :57 is applied -to -the trigger input of the bistable flip-flop 38 causing its output terminals 38b and 38c to go high and low respec-tivehy. The high ou'tpu't at terminal 38b is utilized to tt,~rrt on the lamp source in receptacle 13 to provide light of suitable intensity for -the dental handpiece 24 as shown, for example, in Figure 4 of the present invention.

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The switch may be automatically reset by coupling a suitable biasing spring 50 between the right-hand end of slide member 46 and the vertical side wall 19d requiring a subsequent opening of the switch turnoff of the light source. For example, by closure of the switch under the control of spring 50, light no longer reaches phototransistor 37, causing the voltage level at its emitter to drop to reference potential. Bistable flip-flop 38 may be of the type which changes state only on a positive going edge and hence the negative going edge has no effect on its state.
By operation of the switch at a later time, the next positive going edge causes flip-flop 38 to reverse its stable state whereby outputs 38b and 38c go low and high respectively to turn off the main lamp source. Obviously, any other type of switching means may be provided, it being understood that the nature of the control established through the fiber optics is such as to totally eliminate the need for any electrical leads between the remote control unit 19 and receptacle 18.
The arrangement of Figure 2 eliminates the need for two fiber optics bundles and LED 34 by providing a remote control unit 19' which, although having a similar switch arrangement 19a, is provided with an opening 19c in its upper face 19b which is preferably fitted with a transparent lens member 53.
The separate chamber housing 30' provided in recep-tacle 18 is provided with a single chamber 30a housing the phototransistor 37. The opening 39a serves as a means to enable the passage of light from the proximal end 40a of fiber optics bundle 40 to the phototransistor 37. The distal ' ~..~~.~ d end 40b of fiber optics bundle 40 eRtends inta remote control unit 19' and is preferably positioned beneath and in close proximity to transparent lens 53. The similar switch arm >: assembly 45 is provided so as to position its right-hand a portion between opening 1.9c and the distal end 40b of fiber optics bundle 40, or to be moved to a position displaced therefrom so as to enabl e ambientlight passing through r i the transparent lens 53 to reach the distal end of fiber optics bundle 40 and be conveyed through the bundle 40 in E;
F:

opening 39a so that the light inging upon phototransistor imp 37 causes generation of a signal for operating bistab:Le flip-flop 38 in a manner similar to that described hereinabove.

Since the dental area is normally 'well lighted, ambient ' :

light will be of a level more 'than sifficient to assure positive operation of the switching means. Thus, 'the embodimewt of Figure 2 performs -the same switching :function as 'the remote control unit of Figure 1 while totally eliminating one fiber optics bundle and LED 34 as well as its powering means.
The embodiments described hereinabove serve to h:
corntrol the selective turnon and turnoff of a remote electrical function. However, numerous applications exist wherein it is desirable to not only turn on and turn off the main lamp, a~ but ~to adjust its light intensity. Figures 3a through 3e teach embodiment s for providing this capability.
Turning initially to a consideration of Figures 3a and 3b, the top face 19b of 'the remote co.rrtrol unit is shown as having a circular opening 19c and an arcuate shaped ~~1:
slot 19g concentric with opening 19c. A polarized lens 56 jf!
b~~ is fitted in opening 19c. A second polarized lens 57 is f~,a ' >,;

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rotat ably mounted between three roller members 58, 59, and 60, arranged at 120° int e.rvals about the axis of rotation A of polarized lens 57. Each of these rollers is provided with a groove. For example, roller .58 is shown as being provided with a groove 58a arranged around its cylindrical periphery t ° receive and support the marginal edge of polarized lens 57. A thin frame 62 encircles polarized lens 57 and has secured thereto an outwardly extending projection arm 63 whose free end 63a is bent upwardly so as to extend -through arcuate shaped slot 19g to serve as the operating arm for the remote control means.
By moving 'the operating arm 63a either clockwise or counterclockwise, lens 57 may be rotated thraugh an angle of 100° or more. This permits rela-five rotation between polarized lenses 56 and 57 to prevent light rays from the :, ambient light as represented by arrow LR from passing through the lenses and entering into the distal end 40b of fiber optics bundle 40. By rotation of lens 57 -through a suitable angle from the position where 'the lenses provide an "opaque"
condition, the amount of ambient light passing therethrough may be controlled over a range which at one limit provides a subs~tamtially opaque condition and at -the other limit provides a substantially transparent condition to thereby attenuate 'the light passing through fiber optics bundle 40 by an adjustable amount which rnay be utilized to cause a phototrans:istor to generate a current whose magnitude is a :Function of 'the intensity of light so as to control a servo-mechanism or other suitable device (not shown for purposes of simplicity) to convert the intEnsity of light and magnitude of current unto a control value for controlling the intensity of light emitted by the main light source Thus, light is emitted through the polarized lenses 56 and 57 -to enter -the distal end 40b of fiber optics bundle 40.
Light of a constant brightness is provided, and the intensity of light is regulated by rotating polarized lens 56 relative to lens 57 in the same manner as the control apparatus shown in Figures 3a and 3b. Again, the embodiment of Figure 3e utilizes a small, low power battery within the remote control unit, which battery experiences low current drain due to the low current requirements of the LED 66.
Figure 3f shows still another embodiment of 'the present invention wherein a positive DC source, which is preferably a penlite battery, is selectively coupled to a high frequency generator 76 by means of a normally opened switch 77. Switch 77 ~.s normally biased 'to 'the open position by spring means 78. By depressing switch button 77a, rrtovable arm 7?b provides a shunt path across stationary contacts 77c and 77d to energize 'tone generator 76 which generates a constant frequency lane, the 'tone being transmitted over antenna 79 to a small receiver antenna 80 provided within 'the receptacle 18. The received signal is stepped down in frequency at 85, is amplified at 81, undergoes filtering by band-pass filter 82, and is again amplified at 83, which circuit further provides wave shaping of the signal to create a trigger signal for operating a bistable flip-flop 84 for turnan of 'the main lamp source referred to hereinabove.

The tone generator 76 generates a radio frequency wave picked up by a receiver 85 tuned to the proper frequency.
Alternatively, the tone generator 76 may generate a signal in the audio range, preferably in excess of 2.0,000 cycles per second so as to lie above the normal hearing range.
The signal may be generated 'by a constant frequency generator 76 and applied to a piezo-electric crystal element for r_on-verting -the electrical signal into a sonic frequency. The receiver 80 is preferably a piezo-electric cyrstal utilized to convert the received audio frequency signal into an elec-trical signal which is agaa_n amplified, filtered and appro-priately wave-shaped to control 'the bistable flip-flop 84, or, for that matter, any other control circuit suitable for turning on and turning off the light source.
The main light source may be automatically activated merely by lifting 'the light carrying handpiece. For example, Figure 6 shows the handpiece 24 (of Figure 4) as being held by a cradle member 100 when not in use. The cradle mezriber is bifurcated to receive -the body portion 24a in slot 101, while the bifurcated arms 100a and 100b support 'the larger diameter head portion 24c.
As shown in Figure 6a, 'the cradle may be pivot ally mounted at a point 102 intermediate its ends, a spr ing 103 having a light spring force tends to urge the cradle clockwise about pivot 102. A microswitch 104 is connected between a voltage source -+-V and a ~transm_L t;ter 76 ( see also Figure 3f ) .
_17__ When the handpiece 24 is resting in the cradle 100, the weight of the handpiece overcomes the light spring force of spring 103 and rotates -the cradle counterclockwise, causing the right-hand end of the cradle to urge the arm 104a of the microswitch contacts (not shown) in the open position. When the handpiece is lifted from the cradle, the spring 103 urges the cradle clockwise about pivot 102 to move the cradle arm away from -the microswitch arm 104a causing -the microswitch to couple source +V to transmi-tter 76 which operates in the same manner as was described in connection with Figure 3f-.
In place of a pivotally mounted cradle, the micro-switch rnay be activated by insertion of 'the handpiece into a nesting opening (not shown) which is adapted to receive and support the handpiece 24 when not in use. The microswitch rnay be activated when the handpisce is inserted and/or removed from the nesting socket.
The microswitch may be replaced by a switching -tec:hnique of -the type shown in Figures 4-4b, wherein -the cradle may be provided with a projection movable between -the adjacent ends of -two fiber optics bundles to couple light f-rom a light source to a photo-transistor for activating 'the main light source.
As still another alternative embodiment for -the present invention, -the capability o:~ -the remote control unit may be directly built into 'the dental handpiece as an integral part -thereof, or, alternatively, may be strapped to or otherwise affixed to the handpiece, preferably at a location which does not interfere with -the holding and manipulation of the handpiece so as to avoid accidental turnon ar turnoff of the light source. Alternatively, the _18_ The tone generator 76 generates a radio frequency wave picked up by a receiver 85 tuned to the proper frequency.
Alternatively, the tone generator 76 may generate a signal in the audio range, preferably in excess of 2,0,000 cycles per sf~cond so as to lie above the normal hearing range.
The signal may be generated by a constant frequency generator 76 and applied to a piezo-electric crystal element for r_on-verting the electrical signal into a sonic frequency. The receiver 80 is preferably a piezo-electric cyrstal utilized to convert the received audio frequency signal into an elec-trical signal which is again amplified, filtered and appro-priately wave-shaped to control the bistable flip-flop 84, or, for that matter, any other control circuit suitable for turning on and turning off the light source.
The main light saurce may be automatically activated merely by lifting the light carrying handpiece. For example, Figure 6 shows the handpiece 24 (of Figure 4) as being held by a cradle member 100 when not in use. The cradle member is bifurcated to receive the body portion 24a in slot 101, while the bifurcated arms 100a and 100b support the larger diameter head portion 24c.
As shown in Figure 6a, the cradle may be pivotally mounted at a point 102 intermediate its ends, a spring 103 having a light spring force tends to urge the cradle clockwise about pivot 102. A microswitch 104 is connected between a voltage source +V and a transmitter 76 (see also Figure 3f ) .

light from passing therebetween. By moving slide button from the OFF position and downwardly in the direction shown by arrow 99, the plate-like projection 97 is moved from its position between the distal ends 40b and 32b of 'the fiber optics bundles 40 and 32 to permit light conveyed toward -the distal end of fiber optics bundle 32 (for example, from the LED 34 shown in Figure 1) to enter the distal end 40b of fiber optics bundle 40 so as to be conveyed, for example, to phototransistor 37 shown in Figure l so as to enable remote operation of the main light soLirce conveying light to the fiber optics branches 23a and 23b, to be controlled directly from the dental handpiece, -thereby totallly eliminating the remote control unit. Obviously, if desired, the fiber optics bundle 32 may be eliminated and ambient light may be utilized in 'the embodiment shown in Figures 4-4b by using the ~technic~ue described in connection with the embodiment of Figure 2. Also, 'the alternative arrangements for providing intensity control and/or a localized power source at the denvtal handpiece may also be incorporated therein (i.e., a penli~te battery). However, it is most desirable to maintain the handpiece as trim and uncluttered as is possible so that the preferred arrangement therefor is that shown in Figures 4 'through 4b.
Turning to a consideration of Figure 7, there is showntherein still another preferred embodiment 110 of the present invention which is comprised of a miniature size switch 111, preferably of 'the normally-open type push-button and wh~.ch is adapted to be mounted either directly upon or in close proximity to the dental handpiece (see Figure 8). A pair of Plongated leads 112 serve to couple the remate switch 111 into the activating circuit to provide automatic control of the lamp as will be more fully described.

Considering Figure 8, 'the aforementioned pair of lead lines l12 is corribined in a single bundle with the other conduits which serve as the means for conveying light, pressurized air, water, and so forth to the harxdpiece. Typi-cally, the handpiece 24 may be coupled with a bundle of conduits such as the water 113, air 114, chip air 115, and exhaust 116 conduits, as well as a fiber optic cable 117 in which is mounted 'the fiber optics bundle 118. A strain relief cord 119 may also be provided to prevent any of 'the individual conduits, cables, lead lines and the like from being stretched or broken.
Exhaust conduit 116 may be provided with a pressure transducer or pressure sensitive switch 155 mounted within conduit 116 and coupled to suitable circuit cantrol means by lead lines 120. fhe pressure transducer or pressure sensitive switch 155 is ..render~ed operative in the presence of air under pressure within the exhaust conduit 116 for the purpose of cowtrolling lamp 131 as will be more fully described.
The lead lines 112, may extend to a position just below the handpiece coupling member 24C as shown at 112' or~, alternatively, may extend 'through coupling 24C as shown at 112" and may extend unto 'the handpiece 24 as Shawn at 112", enabling the switch 111 to be mounted directly upon handpiece 24: Alternatively, the remote switch 111 may be mounted at or just below 'the handpiece coupling 24C which is also a convenient location far manipulation by the operator.
The bundling of the lead lines 112 in 'the manner shown does not in any way complicate the design of the handpiece or its conduits and .further~ serves to prevent the lead lines for switch 11.1 from iwterferirxg in any way with the physical positioning, movement or functioning of the handpiece and the canduits servicing the handpiece.

Turning to a consideration of Figure 7, remote switch 111 is shown as being connected in electrical series with pulse circuit 121 and the light emitting diode element 123 provided within the optically coupled isolator 122.
The optically coupled isolator 122 is, in one preferred embodiment, a small, fully self-contained package comprised of an enclosure having lead lines extending through the body of the enclosure for facilitating its connection in an electrical circuit and housing in its interior a light emitting diode 123 and a phototransistor 124. One suitable device of this type is the 4N25 optically coupled isolator which may be obtained from Optron, Inc., and having a light emitting diode 123 of the gallium arsenide infrared -type and having a silicon 'type phototransistor 124.
As shown in Figure 7, the light emitting element 123 is connected in the electrical circuit loop including remote switch 111 and pulse circuit 121. Pulse circuit 121 is comprised of parallel connected resistor and capacitor R1 and Cl, respectively. A resistor R2 is connected in series with the parallel connection, while a power source E1, which in the present example is a small size 9 volt battery, is utilized as the low voltage power source for 'the pulse circuit.
Momentary closure of remote swatch 11 causes a pulse to be instantaneously applied to 'the light emitting element 7.2.3, said pulse instantaneously building to 'the voltage of source E1, and decaying at a rate determined by the value of the circuit components R1, C1 and R2.

The aforementioned generated pulse causes the light emitting diode (LED) 123 to conduct and thereby emit light (in the in:E'rared wave length in the example given).
This light is detected by phototransistor 124 whose conductivity increases as a function of the intensity of infrared light impinging thereon.
The conductor-emitter electrodes of phototransistor 124 are connected across the 'terminals of capacitor C2 forming a part of receiver circuit 125. Receiver circui-t 125 is further comprised of a transistor Ql which has its collector connected to a positive DC source -~VCC through resistor R4 whi7.e its emitter is connected to ground. A charging resistor R3 connects capacitor C2 to source +Vcc and the common terminal between R3 and C2 is connected to the base electrode of Q1 'through diode Dl. During the 'time that photo-~trans~.s~tor 124 is nonconductive, capacitor C2 charges to the level +Vcc causing transistor Ql to conduct so that its collector electrode is substantially at ground potential.
When remote switch 111 is closed, causing emitting element 123 to be pulsed with electrical energy, 'the infrared light emitted from LED 123 subs'tan'tially increases -the conduc-tivity (i.e. , substantially reduces the resistivity) o:~
phototransistor 124 to ground. The abrupt reduction irz the voltage level at the common terminal between R3 and C2 serves to turn transistor Ql off , causing the voltage level at the collector of Q1 to move abruptly toward the supply level +Vcc. This positive going pulse is applied to the trigger input 126a of a counter 126. In the preferred embodiment, '\
count er 126 is provided with two stages and is electrically hand-wired so as to be capable of counting up to a count of 3 and then automatically resetting the counter, thus repetitively producing the binary outputs (00), (0l), (10), (00), (0l), (10). One typical way of providing the desired circuitry is through the employment of an integrated circuit, for example of the type 4027 which is comprised of first and second J-K master/slave flip-flops. One suitable integrated circuit of this type is the CD 4027 AD digital integrated circuit produced by the Solid State Division of RCA.
The control signals utilized for purposes of control-ling off, on and lamp intensity level are taken from one output of each 126b and 126c of the two stages (i.e., flip-flops) comprising counter 126. In order to operate 'the fan, a third output 126d of the second stage is utilized. A descrip-Lion of the manner in which 'the or.~~tput signals of 'the counter 126 are employed to control turnon and in'tensi'ty level of the lamp and turnon and turnoff of the blower is set forth hereinbelow in greater detail.
The outputs 126b and 126c are coupled to an on/off and ir~tensity decoder circuit 127. An on/off decoder circuit 128 for the fan is connected to output 126d.
Decoder 127 i.s coupled to a lamp phase shift intensity control circuit 129, while decoder 128 is coupled to a similar type circuit 130 for controlling selective energization of fan 132.
Lamp 131 and fan 132 are connected in a circui.-t Loop with AC source 135 and triacs 133 and 134, respectively.
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The triacs 133 and 134 are three-'terminal devices.
Two of the terminals (133a and 133b) may be likened to anode and cathode electrode while the 'third terminal (133c} is a gate electrode. Each triac will conduct when the voltage across its anode-cathode electrodes (133a and 133b) is greater than zero and when pulsed at its gate electrode such that the direction of the pulse applied at the gate electrode and the polari-ty of voltage across 'terminals I33a and 133b determines the direction of current flow. As a result, triacs 133 and 134 can be seen to be bidirectional devices with the anode and cathode electrodes 133a and 133b being interchange-able and functioning as cathode and anode electrodes during one half cycle and as anode and cathode electrodes during the next succeeding half cycle of the alternating ourrent signal from source 135. Thus, if the gate electrode 133a is pulsed at the beginning of each half cycle, ~triac 133 will -turn on and remain on throughout that half cycle. However, as soon as the alternating current wave form passes through zero so that the voltage levels at -the anode and cathode electrodes are reversed, t riac 133 will no longer conduct unless another gate pulse of the proper polarity is applied to gate 133c at 'the inception of or at some point during the inception of the next half cycle of 'the AC signal. The gate pulse may occur at any time during each half cycle.
If each gate pulse is caused to occur upon the initiation of each half cycle, i.e., as each half cycle passes through zero voltage in the positive going direction, triac 133 may remain on for 100% of each cycle of AC signal. However, by delaying application of each gate pulse a predetermined time after initiation of each half cycle, it is possible to regulate the portion of each half cycle during which triac 133 is turned on.

-2 5-These characteristics are utilized to advantage in the present invention by regulating 'the turnon time of the triac during each half cycle of the AC signal, in accordance with the count present in counter 126 to either turn off lamp 131, turn on lamp 131 at half intensity, or turn on lamp 131 in full intensity, respectively.
The manner in which this is accomplished is by means of the decoder and phase shift intensity control circuitry shown in greater detail in Figure 7a. As shown therein, the on/off and intensity decader 127 is comprised of operational amplifier 137 having an inverting input coupled to output 126b of counter 126 'through diode D2 and having a naninverting input coupled to output 126c of counter 126. The ou'tpu't of operational amplifier 137 is coupled to the noninverting input of the amplifier through resistor R5. The output of the operational amplifier is also coupled to 'the input of comparator 138 forming a part of the lamp phase shift and intensity control circuit. The circuit 129 further includes a zero crossing detector 139, ramp generator 140, zero current detector 141, control logic circuit 142, chopper circuit 143, output logic s'ta'te circuit 144 and gate pulse stage 145 .
The zero-crossing de'tec'tor circuit 139 is coupled -to the AC source 135 which serves to power lamp 131 as well as fan 132. Each time circuit 139 detects a zero crossing, its ou'tpu't 7.39a triggers .ramp generator 140 to develop a ramp signal at its output 140a. This signal is compared by comparator 138 against the level appearing at the output of operational amplifier 137. When the ramp signal developed at output 140a ruches the voltage level applied to comparator 138 by operational amplifier 137, control signals are developed at outputs 138a and 138b of comparator 138. The zero-crossing detector also determines the polarity of each gate pulse signal and is coupled to control logic 1.42 for this purpose.
Zero-current detector circuit 141 is connected in series with AC source 135 and lamp 131 through resistor R7 to monitor 'the current through lamp I31. When -the current through lamp 131 falls to zero, output 141a applies an enabling signal to control .Logic 142. Control logic circuit 142 which includes gating means (not shown for purpose of simplicity) serves to develop an output pulse. Three conditions occur simultaneously, i.e., when there is no curremt flowing through lamp 131, when 'the AC wave form has made a zero crossing, and when the signal level ramp generator 140 has been reset and has increased to the level. applied to comparator 138 by operational amplifier 13'7. The square pulse developed by control logic 142 is applied to chopper circuit 143 'through capacitor C6 which converts the square pulse into an impulse signal. The output 138d of comparartor coupled to chopper 143 prevents spurious gate pulses from forming before the Comparator has switched correctly. The impulse signal appearing at output 143a is applied to ou'tpu't logic stage 144 which develops an owtpLrt signal so long as a zero-crossing Conductor is present. The output signal from 'the output logic stage 144 undergoes pulse shaping at agate pulse stage 145 to provide a sharp pulse of 'the proper polarity for application to 'the gate electrode 133a of tri.ac 133. 'Fhe manner of operation is such that when counter 126 is at a count of zero, the control level applied to input 138a of comparator 138 through operational amplifier 137 is sufficiently high to prevent the ramp signal from reachingvthat level during each half cycle so as vto keep lamp 131 in 'the off condition.

By closing switch 111, the count in counter 126 is advanced by one count (i.e., to O1) to develop a signal level applied to input 138a of cornparator 138 by operational amplifier 137 to turn on triac 133 after a delay subsequent to each zero crossing which is sufficient to illuminate lamp 133 at half intensity.
A subsequent momentary closure of switch 111 causes counter 126 to be advanced by one count to a count l0, causing the output level applied by operational amplifier 137 to input 138a of comparator 138 to be reduced below the aforesaid half intensity level, whereby -the signal developed by ramp generator 140 builds to the signal level at input 138a at a time still closer to the last occurring zero crossing to cause the gate of 'the t riac to be pulsed at a closer point in -time to the beginning of each :half cycle to increase 'the on 'time of the lamp during each AC half cycle sufficient to cause the lamp to glow at full in'tensi'ty.
By closing remote switch 111 once more, counter 126 is automatically reset to a count of "zero" (00) returning the 1. amp l31 to the off condition by developing a signal level at input 183a high enough to prevent 'the ramp signal from reaching -the level at input 138a during each AC half cycle:
The on/off decoder 128 of the fan on/off control 130 may be comprised of the same 'type of circuitry as that wti~.ized for the lamp decoder 127 and lamp pulse shift intensity control 129, exceptwtha~t the fan on/of.f control and decoder is preferably connected to cause the fan to be operated at its full rated output regardless of -the fact that the lamp is on at either full or half intensity. The circuitry which may be employed for the decoder and triac phase shift control is -the L120 integrated circuit for triac phase control available from SGS-ATES.

.~,~~~-~~~
The arrangement of Figure 7 may be simplified by replacing the count of 3 counter 126 by a count of 2 counter, i.e., by a bistable flip-flop which is driven to one of its two stable states by closure of switch 111 and which is driven to the other of its two stable states by a subsequent closure of switch 111, wherein these states are utilized for turning off lamp 131 and for turning on 131 to full intensity, respectively.
Obviously, the opposite capability may likewise be provided wherein count of 3 Counter 126 may be replaced by counter means having a capability of counting to greater than 3 counts in order to provide levels of iwtensi-ty other than half intensity and full intensity as was set forth hereinabove.
As still another alternative to 'the embodiment described hereinabove, the optically coupled isolator may be replaced by a transducer capable of generating an audio frequency and a receiver element adapted to generate an electrical signal responsive to operation of 'the transducer element at the :frequency of the 'transducer.
Figure 7b shows still another alternative embodiment wherin 'the optically coupled isolator may be rep7.aced by a reed swiU;ch assembly 150 comprised of a pair of switch elements 152 encapsulated within an evacuated envelope 153 and adap~tedvta be maintained in the normally open position.
The reed switch assembly is further comprised of a winding 151 wound about envelope 153 and electrically connected within the circuit loop including remote swatch 111 and pulse circuit 121.. upon rnomenta~~y closure of switch 111, winding 151 is pulsed to set up a magnetic field which pauses momentary closure of reed switch Contact elements 152. By .,~:~~ ~'~l connecting these reed switch contact elements across capacitor C2, shown in Figure 7, capacitor C2 may be caused to discharge through the closed reed switch elemen-is -to pulse counter 126 in -the same manner as previously described with respect to the phototransistor 12~~ of 'the optically coupled isolator 122. It should be understood that the embodiment of Figure 7 accomplishes all of the advantages of previously described embodiments of the present invention in that all of the elements shown in Figure 7, with the exception of the remote swi-tch 111 and its lead line 112, may be housed within a single housing represented by dashed line 60. The assembly is provided with a single power cord which may be coupled to a conventional 115 volt AC 60 Hertz power source which is wired to provide the power for driving lamp 13:L and fan 132. 'The aforementioned integrated circuit 'type L120, further includes the capability of rectification and filtering of the AC signal vo provide the DC levels necessary for powering transistor Ql and counter 126, as well as the DC powered circuits of decoder l27 and the shift control circuit 129, which circuits are shown in Figure 7A. In addition, 'the circuit of Figure 7 totally eliminates the need for an expensive and heavy transformer and for a special purpose lamp, which elements a~~e required in 'the prior art design of U.s. Patent No. 3,758,951, described herEinabove. The last described embodiment is quite compact, having a housing which occupies a small amount of space.

Figure 8a shows a pressure actuated switch assembly 155 which is advantageous for use in 'the present invention.
The switch is comprised of enclosure halves 156a and 156b forming enclosure 156, having a hollow interior 157 for mounting resilient blades 158, 159 connected to electrical terminals 160, 161, respectively, 'through conductive pins 162, 163. Screw 156c adjusts the exposure of an aperture 156e in housing to control 'the pressure sensitivity. Hollow pressure port 7.56d receives air under pressure through a flexible conduit 165, coupled to drive air conduit 114 (Figure 8) through T-connector 166. Diaphragm 170, which is sandwiched between enclosure halves 156a and 156b, moves upwardly against cantilevered contact 158 to close the switch.
When the operator depresses the pressure delivery switch, not shown .for purposes of simplicity, air pressure is introduced into drive air conduit 114. The dental handpiece is typically provided with an impeller rotated by -the drive air to operate a drill mounted at the working end of the dental handpiece. The drive air conduit 11~~ extends to one end of the impeller while 'the exhaust air conduit is placed on 'the downstream s:Lde of the impeller and carries exhaust air away from 'the dental har~dpiece to avoid an undesirable presure drop at the impeller.
The pressure activated switch 155 is mounted within the exhaust air conduit 116 and closes 'when air under pressure is delivered to 'the dermal handpiece 2~~. Switch closure may activate 'the pulse circuit 121 of Figure 7 to selectively energize lamp 131 and fan 132 in the manner previously described.

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The switch may alternatively take -the form of a transducer which generates an electrical signal for activating one of the transmitting devic:~es 123, for example, for control-ling lamp 131 and fan 132.
Figure 9 shows a fiber optics illuminator which may employ the remote switching capability of the present invention and which is an independent unit, as opposed to being integrated in a dental handpiece. The unit 190 is comprised of an elongated sleeve 191 whose lower end is shown broken, but is understood to be positioned adjacent to the lamp source 131, for example, as shown in Figure 7.
Th.e sleeve 7.91 houses a bundle of optical fibers which are separate from one another to allow the sleeve to bend through rather small bending radii to facilitate manipulation and positioning of the unit.
The upper end 192 of the bundle is comprised of said optical fibers which have been potted in a transparent epoxy and then polished.
Elongated helical spring 193 serves to prevent undue bending of 'the upper end of 'the illuminator 190.
A. Sw7.tCh 19~r having a depressible member 195 is arranged below spring 193. By depressing member 195, the switch contacts (not srxown) are closed. The contacts may be similar -to 'those shown schematically as switch 111 in Figure 7.
Figure 1U shows another electrical isolation technique which may be substituted for the optical isolator 122 shown in Figure 7.

The circuitry 200 shown in Figure 10 is comprised of a low voltage lOkHz signal generator 201 coupled to capacitor 202 through the one winding 203a of a transformer 203. The -transformer further includes a winding 203b tightly inductively coupled to winding 203a by transformer core 203c. The end terminals of winding 203b are coupled to remote switch 111 through conductive leads 112 which may extend through sleeve 191 of the illuminator 190 shown in Figure 9.
The closing of remote switch 111 alters -the impedance of winding 203a by providing a direct short circLlit condition across winding 203b. The short circuit condition across winding 203b is reflected back to winding 203a, 'thereby greatly increasing the charging current to capacitors 202 and G04. Diode 205 prevents capacitor 204 from discharging back to either capacitor 202, or -the oscillator 201. Thus, capacitor 204 can only discharge -through resistor 206 which has a high ohmic value (of the order of 100k ohms) so that capacitor 204 discharges slowly.
When capacitor 204 charges to a sufficient level, Ql is turned on to operate 'the count of 3 counter in the same rna.nner as was previously described with regard 'to Figure 7.
The signal developed by oscillator 201 is insufficient to cause any shock or injury to an operator especially due to its 1. ow voltage rating, and further avoids 'the need for a separate battery since oscillator 201 may be powered by rectifying and filtering line voltage down to a level of tYze order of 5 volts DC, or less.

~~ D~~' The present invention can be used in illumination systems .for dental drills. In such an environment, 'the invention provides added safety in that the patient is isolated from posible high-voltage shocks, etc. The invention may also be used, generally, for controlling any fiber optic illumination system.
_ 3tr_

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Control means for selectively energizing a lamp serving as an illumination source for an elongated fiber optics bundle having a first end positioned adjacent to said lamp and a second end mounted at the working end of a dental handpiece, said control means comprising signal generating means including switch means for generating an enabling signal upon an actuation of said switch means, applying means for selectively applying AC power to said lamp, and sensing means responsive to said enabling signal generated by said signal generating means and switch means for, causing said applying means to couple AC power to said lamp, said signal generating means being electrically isolated from both said applying means and said sensing means to protect the user of said dental handpiece, said sensing means including means for latching said applying means to said lamp in a coupling relationship with said lamp until a subsequent activation of said switch means for disabling said applying means.

2. Apparatus according to Claim 1, wherein said sensing means and said applying means comprise counter means having a plurality of stable states and being responsive to each enabling signal to advance the counter means from one stable state to the next, a triac and an AC source coupled in series with said lamp, said triac having a gate electrode, means for generating a gate signal responsive to the state of said counter means for controlling the time when the gate signal is applied to said gate electrode under conditions where said gate signal is inhibited when said counter is in a first one of said stable states, said gate signal is applied to said gate electrode at a first predetermined time after the initiation of each half-cycle of the AC signal when said counter is in a second one of said stable states; and said gate signal is applied to said gate electrode at a second predetermined time after the initiation of each half-cycle of the AC signal, said second predetermined time being greater than said first predetermined time.

3. Apparatus according to Claim 1, wherein said sensing means and said applying means comprise counter means for counting the number of operations of said switch means, an AC source and a triac connected in series with said light source, means for detecting the zero crossings at the AC
signal provided by said AC source, ramp signal generating means responsive to each zero crossing for generating a ramp signal, delay control means coupled to said counter means for developing a signal level representative of the count in said counter, comparator means coupled to said delay control means and said ramp signal generating means for generating a signal when the level of said ramp signal reaches the level of the signal developed by said delay control means, and means responsive to the output signal of said comparator means for applying a gate pulse to the electrode of said triac for triggering said triac to conduct at a point in each half-cycle of the AC signal which is a function of the count in said counter means.

4. Apparatus according to Claim 1, wherein said dental handpiece includes an air conduit for delivering air under pressure to said dental handpiece arid said switch means comprises pressure sensitive means arranged in said air conduit and responsive to the delivery of air under pressure to said dental handpiece through said air conduit to cause a generation of said enabling signal.

5. Apparatus according to Claim 4, wherein said pressure sensitive means comprises a normally-open pressure sensitive switch acting to assume a closed condition when air under pressure is introduced into said air conduit.

6. Apparatus according to Claim 1, wherein said dental handpiece includes an air conduit for delivering air under pressure to said dental handpiece and a branch conduit communicating with said air conduit, and said switch means comprises pressure sensitive means arranged in said branch conduit and responsive to the delivery of air under pressure to said dental handpiece through said air conduit to cause a generation of said enabling signal.

7. Apparatus according to Claim 6, wherein said pressure sensitive means comprises a normally-open pressure sensitive switch acting to assume a closed condition when air under pressure is introduced unto said air conduit.

8. Apparatus according to Claire 1, wherein said signal generating means comprises manually operable switch means, oscillator means provided at said illumination source, impedance means coupling said oscillator means to said sensing means, and means inductively coupling said switch means to said impedance means for reducing said impedance when said switch means is operated.

9. Apparatus according to Claim 6, wherein said oscillator means is a high-frequency oscillator and further comprises an iron core transformer, and wherein said impedance means is formed by a first winding of said transformer, and said inductive coupling means is formed by a second winding of said transformer which is inductively coupled to said first winding.

10. Apparatus according to Claim 1, wherein said signal generating means comprises means for generating an electrical signal of a signal frequency in the audio range, transducer means for converting the electrical signal into a sonic wave, said sensing means comprising transducer means responsive to receipt of said sonic wave for converting same into an electrical signal, and filter means for passing electrical signals lying within a narrow predetermined frequency range.

11. Apparatus according to Claim 1, wherein said signal generating means comprises means for generating a radio frequency signal and miniature antenna means for trans-mitting said radio frequency signal, and said sensing means comprises an antenna for picking up the aforesaid radio frequency signal, filter means for passing only those received signals lying within a narrow predetermined frequency range, and means responsive to those received signals passed by said filter means for generating said activating signal.

12. Apparatus according to Claim 1, wherein said signal generating means comprises field producing means for generating a magnetic field responsive to operation of said switch means, and said sensing means includes second switch means responsive to said magnetic field for producing said activating signal.