US3181188A - Electric hand appliances, particularly toothbrushes - Google Patents

Description

M. MORET May 4, 1965 ELECTRIC HAND APPLIANCES, PARTICULARLY TOOTHBRUSHES Filed April 25, 1963 3 Sheets-Sheet l INVENTOR Michel More? Y fi M W a ATTORN EYS M. MORET May 4, 1965 ELECTRIC HAND APPLIANCES, PARTICULARLY TOOT HBRUSHES 3 Sheets-Sheet 2 Filed April 25, 1963 INVENTOR Michel Moret 4 W 2 116. 7

ATTORNEYS FIG. 3

May 4, 1965 M. MORET 3,181,188

ELECTRIC HAND APPLIANCES, PARTICULARLY TOOTHBRUSHES Filed April 25, 1963 s Shee ts-Sheet 5 INVENTOR Michel Moref 42 ATTORNEYS United States Patent M 351815.88 ELECTRIC HAND APPLKANCES, PARTECU- LARLY TGGTHBRUSHES Michel Moret, Geneva, Switzerland, assiguor to Etahlisse= ments AEUP, Vaduz, Liechtenstein, a firm of Liechtenstein Filed Apr. 25, B63, SeLNb. 275,646 Claims priority, application Switzerland, Apr. 27, 1962,

5,087/62 7 Claims. (til. 15-22) This invention relates to electrically-operated hand appliances forcorporal care, and especially to electrically operated toothbrushes. The invention is particularly directed to the provision of an electrically safe appliance of this character incorporating an electric switch therein.

It is well known that the use of elecrical appliances is very dangerous when the device that should enclose operative elements in a fluidtight manner at the voltage of their control switch happens to fail unexpectedly, and a conducting liquid, particularly water, enters the casing provided for such elements. This danger is particularly great in hygienic appliances, either because the user employs them when his body is partily immersed in the water or is not sufiiciently insulated from the ground, for instance when using in a bathroom, or else because these appliances are expressly designed to operate in the presence of a conducting liquid medium, particularly in the case of electrical toothbrushes.

Electrically-operated toothbrushes are now known including a casing forming a handle, a shaft extending through one end of the casing for carrying a toothbrush head, and electrical means mounted within the casing for oscillating the shaft. One particular type is disclosed in US. Patent No. 2,917,758, issued December 22, 1959 to Held et al. In this toothbrush the shaft is rotationally oscillated so as to impart a corresponding motion to a toothbrush head attached thereto and brush the teeth in the lengthwise direction thereof. Other types are known in which a longitudinal oscillation is imparted to the shaft. By using different types of heads, the appliance can be used for other types of corporal care, such as massage, beauty treatment, etc.

When such appliances are arranged to be connected to an external power supply such as the power mains, it is highly important to provide complete protection against the danger of an electric shock. They are commonly employed in the bathroom where the appliance or the hands of the user may be wet, so that even small amounts of electrical leakage could be dangerous. In the case of a toothbrush, water and toothpaste are commonly used on the brush and, when inserted in the mouth, a fairly good electrically conducting path exists for any leakage current from the device. a

With an oscillating shaft, it is difiicult to achieve watertightness, while at the same time permitting oscillaious of sufiicient amplitude to be obtained with the limited power available. Further, even though initially obtained, over an extended period of use the watertightness may become impaired.

In devices of this type, an electric switch therein is convenient so that the device can be turned 0E without unplugging the cord from the electric outlet. Further, since it may be desired to start and stop the device during its use, as in applying dentifrice to the brush head, it is desirable for the switch actuating mechanism to be arranged for convenient action by the fingers with the device held in the hand in normal operating position.

However, since a switch inherently involves the making and breaking of an electric circuit, and hence movement of parts, great care must be exercised to preserve watertightness. Due to space limitations in a device of this Patented May 4, 1%65 type, switch water-tightness is difficult to attain while at the same time preserving convenience of use.

An electric toothbrush with an electric switch incorporating several features for providing watertightness is described in copending application Serial No. 155,366, now Patent No. 3,112,416, filed November 28, 1961 by Moret for Electrically-Operated Hand Appliances for Corporal Care, particularly Toothbrushes. In the spe cific embodiment there described the switch contacts are mounted in a fitting in the casing and covered by a watertight elastic member. A slider is mounted on the fitting for movement transversely of the casing. A pin mounted for longitudinal movement of the fitting is engaged by an inclined surface of the slider and presses against the elastic covering to move one switch contact relative to the other. A pair of resilient areas in the easing on opposite sides of the shaft near respective ends or" the slider enable transverse movement of the slider in cit-her direction by manual pressure on respective resilient areas, thereby enabling the switch contacts to be opened and closed.

The present invention is an improvement on that or" the aforesaid application, and avoids the use of an elastic coveringagainst which a pin is pressed, thereby avoiding the possibility of eventual wear or deterioration of the elastic covering which would impair watertightness. The present invention provides a switch structure which is normally watertight, but which is so designed that if, through wear during use, deterioration with time, or errors in assembly, etc. watertightness is impaired, the amount of leakage current which can flow is so small as not to endanger the user. To this end, certain switch elements are assembled and cooperate with one another with clearances that are sufliciently small so that the resistance of a liquid path between the elements will be suficient to prevent any current flow which would be dangerous to the user.

As specifically described hereinafter, the switch contacts are mounted in a chamber of a fitting of insulating material which is completely closed except for a small aperture Whose length is large compared to its diameter. A pin of insulating material fits into the aperture with a very small clearance, and the head of the pin is actuated by a slider to open and close the switch contacts. Sealing means are provided between the pin and surrounding walls near the head thereof, so as to normally prevent water, toothpaste and the like from entering the switch contact chamber. 'I-lowever, the diameter, length and FIG. 1 is an overall view of an electrically-operated toothbrush including a handle and an attached sternbrush;

FIGS. .2 and 3 are longitudinal views of the handle, taken at right angles to each other, with the upper portion of the casing cut away;

FIG. 4 is a fragmentary longitudinal section through the portion of the casing containing the switch mechanism, in a plane at right angles to that of FIG. 3;

FIG. 5 is a transverse cross-section taken along line 55 of FIG. 4;

FIG. 6 is a transverse cross-section taken along line 6d of FIG. 4; and

FIG. 7 is a cross-section taken along arcuate line 77 of FIG. 5.

Referring to FIG. 1, a casing .10 forms a handle, and shaftend 11' holding a brush head projects from the front end thereof. In this embodiment the brush head is detachable from the handle and comprises a stem 12 with bristles 13 mounted thereon, with a coupling 14 enabling the brush stem to be. conveniently attached and removed.

The casingis preferably made of an insulating material such as a plastic, and resilient areas, i.e. buttons 15, 15', are provided for actuating the internal switch mechanism. Alternating current from an external power source is supplied through an insulated, multiple-conductor electric cord 16 extending through a reinforcement 17 in the end cap 10 of the casing, all secured together in watertight relationship.

Referring to FIGS. 2, 3 and 4 the electrical means shown for oscillating shaft 11 may be a motor of the type shown in the aforesaid Patent 2,917,758. The stator of the motor includes a pair of longitudinally extending pole pieces 21, 21 with a coil (not shown) to which A.-C. current is supplied from line 16 for producing magnetic flux in the gap between the ends of the pole pieces.

A rotor 22 mounted on shaft 11 is located between the front ends of pole pieces 21,21. Shaft 11 is rotatably mounted in bearing plate 23* and an axial hole in fitting 24. of insulating material. The bearing plate 23 is attached to the pole pieces 21, 21' and an annular surface 25 of fitting 24 is likewise attached to the pole pieces. The rotor 22 includes a permanent magnet which interacts withthe alternating magnetic flux between adjacent portions of pole pieces 21, 21' to produce rotational oscillation. Springs 26, 26 are each secured at one end to the shaft 11, and the other ends are fixed in fitting 24 so as to provide spring biasing which returns the shaft 11 to its mean position of equilibrium after each oscillation imparted to it in one direction or the other.

This type of motor is described in detail in the aforesaid Patent 2,917,758, and further description here .is

unnecessary.

To prevent the entry of water, etc. into the portion of the casing containing the. motor and electric switch, a flaring sleeve 31 of resilient, water-impermeable material is provided. The front end 32 thereof encircles an enlarged section 18 of shaft end ll'inwatertightrela tionship, and the rear end is pressed against the inside of casing 10 by an annular section 27 of fitting 24. As shown in FIG. 4, the shaft end 11 is a molded section of plastic material fitting over and attached to shaft 11 by a steelpin 19. Waterproofing sleeves of this type are described in Patent No. 3,060,474,.issued October 10, 1962,to Woog, and in copending application Serial No. 221,258, filed September 4, 1962,by Robert Simmen. The flexibility of the sleeve allows rotational oscillation of the shaft without impairing the watertight connections with shaft and casing. This, together with the watertight casing rearward of the sleeve, normally prevents entry of water, etc. to the motor compartment.

Describing now the electric switch of the present invention, a slider 41 is mounted inthe fitting 24 and arranged to be pushed in either direction by buttons 15, 15'. The slider is arranged to actuate a pin 42 of insulating material which fits into an aperture 43 in therfitting 24 and engages a flexible contact blade 44 to move it toward a corresponding fixed contact. r 7

Considering first the slider 41, this is bestshown in FIG. 5. The slider may be of insulating material and has a cutout 45 which fits around a rounded post section 46 of the fitting 24. As shown, the cutout 45 is ofgenerally trapezoidal form. In moving frornone position to the other, the slider pivots around post section 46.

A raised section 48 of portion of the fitting 24 so as to provide additional guidance along the arcuate path.

As shown in FIG. 7, the slider is recessed along a por tion of its lower face at 49 and this face is provided with two laterally-extending grooves 51 and 52 of diiferent depths. These grooves are shaped to accommodate the head 42' of pin42. Withthe slider 41 inthe position shown in FIG. 7, the head of the pin is in the deeper groove corresponding to the open switch position. With the slider moved to the right as seen in FIG. 7, by pressing button 15 (FIG. 5), the shallower groove 52rwill engage the head, corresponding to the closed switch position.

The switch contact arrangement is best shown in FIGS. 4 and 6. An annular insulating support 53 fits into an annular recess in fitting 24 around a neck portion 54 of the fitting. The flexible contact blade 44 is fixedly attached to support 53 at 55, an insulating stub 53' on support 53 assisting in initial orientation of the blade. A fixed contact 56 is also mounted on support 53 beneath the free end of the flexible blade, as seen in FIG. 6.

The flexible blade 44 extends around the neck portion 54 of the fitting 24, and pin 42 engages it in the region indicated at 57. Downward movement of the pin 42, as seen in FIG. 4, presses the end of the flexible blade 44 against the fixed contact 56 to close the switch. When the leads have been attached to the blade and fixed contact, the support 53 is sealed in the fitting by a plug 58 of insulating plastic material. Thus, the switch contacts are in a chamber of insulating fitting 24 which is completely sealed except for the aperture 43 in which the pin 42 is mounted.

The pin 42 is 'made fluid-tight with the fitting 24 by means of a resilient washer 59 which is force-fitted around the upper portion of the pin, just below the head 42', and also force-fitted against the wall 61 of a hole 62 in the fitting 24 leading to the smaller diameter aperture 43. The lower end 61' of the hole 61 is tapered to restrict downward movement of washer 59. Also, the pin 42 is provided with a tapered section 42". Thus, when the pin 42 is pressed downward, as seen in FIG. 7, the washer 59 bends "but maintains a fluid-tight seal. The head 42' of the pin advantageously forms a close fit in the upper end of hole 61.

The switch contact members 44 and .56 are connected in series with the motor coil and the cord 16; To this end, lead 63 (FIG. 3) is placed in a slot in pole piece 21 and connected to the flexible blade 44. Another lead (not shown) lies in a similar slot in the other pole piece 21 and is connected to the fixed contact 56. i

'It will be observed that with proper assembly the switch contact members are protected from the entry of water, etc. by the sealing thereof in fitting 24 and the sealing of the pin 43 in the fitting by washer 59. Additionally, the flexible sleeve 31 prevents entry of water. In use, it is possiblethat eventually the sleeve 31 will fail to preserve watertightness through deterioration, chemical action, etc. The same is true of washer 59. In case of such deterioration, or in case washer 59 is inadvertently omitted during assembly, water, or a mixture of water with toothpaste, etc., could reach the pin 42 and eventually enter the chamber containing the switch contacts.

As a further factor on safety, the pin 42 and aperture 43 are of sufiiciently small diameter compared to the length of the aperture, and the clearance therebetween is suificiently small, so that the small cross-section and length of the tube of liquid capable of forming in' the clearance space provides a high resistance sulficient to limit the current to a safe value. The resistance under such circumstances may be determined by the application of Ohms law, according to the formula:

where R is the resistance, l is the length of the path along aperture 43, s is the cross-sectional. area of the clearance between'pin 42 and aperture 43, and its the specific resistivity of any liquid encountered in'use. In one par ticular embodiment, wherein the diameter-of the pin'was about 1 millimeter, the diameter of the aperture was just 5 to 5.5 milliampe'res at 200 volts and about 3 to 4.5 milli- V arnperes at 100 volts.

ohms. Thus, under the most, unfavorable conditions, the leakage current is not high enough to endanger the user, and will commonly result in only a slight tingling The invention has been described in connection with a specific embodiment thereof showing a preferred arrangement. It will be understood that. modifications and changes in detail may be made by those skilledin the art within the spirit and scope of theinvention.

I claim: j,

-1. An electrically-operated hand appliance for corporal care which comprises 7 (a) an elongated casing forming a handle,

(b) a shaft extending to the exterior at one end of the casing for carrying an appliance head,

(c) electrical means mounted Within the casing for driving the shaft and means for supplying electric power thereto,

(d) a fitting of insulating material fixedly mounted in the casing,

(e) a slider mounted on said fitting for movement transversely of the casing with at least one end thereof adjacent the casing and having a surface inclined to the direction of movement thereof,

(1) at least .one resilient area on the casing near said end of the slider for enabling transverse movement of the slider by manual pressure thereon,

(g) a pair of cooperating, relatively movable switch contact members mounted within a chamber in said fitting and connected in the power supply circuit to said electrical means, a

(12) at least one of said switch contact members being flexible,

(i) a longitudinally-extending elongated aperture of small crosssect-ion in said fitting communicating with said chamber,

(i) said chamber being insulatedly closed except for said aperture,

(k) a pin of insulating material in said aperture for engaging said-flexible switch contact member,

(I) said pin being positioned for engagement by the inclined surface of the slider to move the pin longitudinally thereof and thereby move the flexible switch contact member to and away from the other contact member,

(m) and a resilient sealing member near the end of said pin adjacent the slider in sealing contact with said pin and said fitting.

2. An appliance in accordance with claim 1 in which the length and diameter of said aperture and the clearance of the portion of the insulating pin therein are predetermined to yield a high resistance in the presence of liquid that may leak thereinto during use and limit any leakage current to a low value. i

3. An electrically-operated hand appliance for corporal care which comprises (a) an elongated casing forming ahandle,

(b) a shaft extending to the exterior at one end of the casing for carrying an appliance head, i

(c) electrical means mounted within the casing for driving the shaft and means for supplying electric power thereto,

(d) a fitting of insulating material fixedly mounted in the casing,

(e) a slider mounted on said fitting for movement transversely of the ca-sing'with at least one end The corresponding resistances may be calculated to be in the range of20,000 to 40,000

6 thereof adjacent the casing and havinga surface inclined to the direction of movement" thereof, .(f) at leastone resilient area on' the casing-nearsaid end of the slider for enabling transverse movement er the slider byma'nual pressure thereon, a '(g) apairrof lcooperating, relatively movable switch contact members mounted Within achamber in said fitting andtconnected in the power supply circuit to said electrical means, a (h) atleast one of said switch contact members being flexible, a

i *(z') a longitudinally-extending aperture in, said fitting extending from said chamber toward said slider,

-(j) said aperture having a portion adjacent the chamber of small cross-section and length large compared 'to the diameter thereof and a portion toward the slider of larger diameter, j I

(k) said chamber being insulated-1y closed except for 1 lsaidaperture,

' (l) a pin of nsulating material closely fitting in the small cross-sectional portion of said aperture for engaging said flexible switch contact member and having a head of larger cross-section for engaging said slider,

(m) said pin being movable longitudinally bythe in-.

olined surface of the slider to rnove the flexible switch contact member to and away from the other contact member,

(n) and a resilient sealing washer encircling said pin below the head thereof in sealing relationship and tightly engaging the larger diameter wall section of said aperture in sealing relationship.

4. An appliance in accordance with claim 3 in which said resilient sealing washer is substantially rforce-fitted on said pin and in said aperture, and the space between the washer and the small diameter portion of the aperture is predetermined to accommodate flexing of the washer over the range of movement of the pin.

5. An appliance in accordance with claim 3 in which said pin has an outwardly tapered section engaging the center of said resilientwasher on the pin head side thereof and the wall section of the aperture has an inwardly tapered section engaging the periphery of the washer on the other side thereof, the space between the washer and the small diameter portion of the aperture being predetermined to accommodate flexing of the washer over the range of movement of the pin.

6. An electrically-operated toothbrush which comprises (a) an elonagted casing forming a handle,

(12) a shaft extending to the exterior at one end of the casing for carrying a toothbrush head,

(c) electrical means mounted within the casing for driving the shaft,

(d) means for supplying power to said electrical means from a power main,

(e) a fitting of insulating material fixedly mounted in the casing, a

(f) a slider mounted on said fitting for movement transversely of the casing with at least one end thereof adjacent the casing and having a surface inclined to the direction of movement thereof,

(g) at least one resilient area on the casing near said end ofthe slider for enabling transverse movement of the slider by manual pressure thereon,

'(h) a pair of cooperating, relatively movable switch contact members mounted Within a chamber in said fitting and connected in the power supply circuit to said electrical means,

(i) at least one of said switch contact members being flexible,

(i) a longitudinally-extending aperture in said fitting extending from said chamber toward said slider,

(k) said aperture having a portion adjacent the chamber of small cross-section and length large compared to the diameter thereof :and a portion toward the slider of larger diameter,

*(I) said chamber being insu-latedly closedexcept-for said aperture, (m) a pin of insulating material closely fitting in the small cross-sectional portion of said aperture for engaging said flexible switch contact member and having'a head of larger. cross-section for engaging said slider,

(71) said pin being movable longitudinally by theiin-.

dined sunfiaee of the slider to move the flexible switch contact member to and away from the other contact member,

(o) and a resilient sealing washer'eneireling said pin below the head thereof in sealing relationship and tightly engaging the larger diameter wall section'of said aperture in sealing relationship,

7 (17) said pin having an outwardly tapered section engaging the'center of said resilient washer on the pin head side thereof and the wall section of the aperture having an inwardly tapered section engagwith claim 6 in which the length and diameter of thesmall cross-section portion of said aperture andthe clear-' ance. of the portion of, the insulating pin therein are predetermined to yield a high resistance in the presence of liquid that may leak therein'to during use and limit any leakage current to alow value.

References Cited by the Examiner UNITED STATES PATENTS 2,442,164 5/48 Ferris 200-457 2,532,000 111/50 West. 2,677,730 5/54 Weidenman 200-157 3,112,416 11/63 Moret 1522X CHARLES A. WILLMUTH, Primary Examiner.

Claims (1)

1. AN ELECTRICALLY-OPERATED HAND APPLIANCE FOR CORPORAL CARE WHICH COMPRISES (A) AN ELONGATED CASING FORMING A HANDLE, (B) A SHAFT EXTENDING TO THE EXTERIOR AT ONE END OF THE CASING FOR CARRYIONG AN APPLIANCE HEAD, (E) ELECTRICAL MEANS MOUNTED WITHIN THE CASING FOR DRIVING THE SHAFT AND MEANS FOR SUPPLYING ELECTRIC POWER THERETO, (D) A FITTING OF INSULATING MATERIAL FIXEDLY MOUNTED IN THE CASING, (E) A SLIDER MOUNTED ON SAID FITTING FOR MOVEMENT TRANSVERSELY OF THE CASING WITH AT LEAST ONE END THEREOF ADJACENT THE CASING AND HAVING A SURFACE INCLINED TO THE DIRECTION OF MOVEMENT THEREOF, (F) AT LEAST ONE RESILIENT AREA ON THE CASING NEAR SAID END OF THE SLIDER FOR ENABLING TRANSVERSE MOVEMENT OF THE SLIDER BY MANUAL PRESSURE THEREON, (G) A PAIR OF COOPERATING, RELATIVELY MOVABLE SWITCH CONTACT MEMBERS MOUNTED WITHIN A CHAMBER IN SAID FITTING AND CONNECTED IN THE POWER SUPPLY CURCUIT TO SAID ELECTRICAL MEANS, (H) AT LEAST ONE OF SAID SWITCH CONTACT MEMBERS BEING FLEXIBLE, (I) A LONGITUDINALLY-EXTENDING ELONGATED APERTURE OF SMALL CROSS-SECTION IN SAID FITTING COMMUNICATING WITH SAID CHAMBER, (J) SAID CHAMBER BEING INSULATEDLY CLOSED EXCEPT FOR SAID APERTURE, (K) A PIN OF INSULATING MATERIAL IN SAID APERTURE FOR ENGAGING SAID FLEXIBLE SWITCH CONTACT MEMBER. (L) SAID PIN BEING POSITIONED FOR ENGAGEMENT BY THE INCLINED SURFACE OF THE SLIDER TO MOVE THE PIN LONGITUDINALLY THEREOF AND THEREBY MOVE THE FLEXIBLE SWITCH CONTACT MEMBER TO AND AWAY FROM THE OTHER CONTACT MEMBER, (M) AND A RESILIENT SEALING MEMBER NEAR THE END OF SAID PIN ADJACENT THE SLIDER IN SEALING CONTACT WITH SAID PIN AND SAID FITTING.

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