APPLIANCE

S P E C I F I C A T I O N BACKGROUND OF THE INVENTION This application is a continuation-in-part of a "SAFETY" device for an electrical appliance given Serial No. 07/260,453, filed October 20, 1988, and is co-pending therewith.

This invention relates, generally, to appliances and, more particularly, to appliances such as electric hair dryers, curling irons, kitchen appliances and the like which include a means for disconnecting the electrical current therein should the device become saturated with water or for any other reason where a shock hazard exits.

The state of consumer appliances in present day households indicates that usage of electrical devices is increasing. There are many types of devices, particularly handheld types, which generally fall into three categories - health and beauty, kitchen and electric hand tools. Health and beauty handheld electrical devices are generally comprised of electric hair dryers, curling irons, electric razors; kitchen devices are generally mixers, blenders, coffee makers, etc. ? while handheld electric tools are generally comprised of drills, hedge-clippers, handheld saws and the like.

The reasons for the proliferation of these devices is quite simple. They are generally inexpensive to purchase, while being convenient and well adapted to

their individual purpose. However, use of these devices produces a distinct danger, particularly when used around water, or even steel wool pads. This danger is in the form of electrocution. Frequency of electrocution as a result of these types of devices, particularly handheld electric hair dryers, is increasing. Since these types of devices are typically used in wet areas, such as by sinks, tubs or outside, it is readily apparent that there is a significant likelihood that the object will either be dropped into water, such as a bathtub or a sink, or that it may become contaminated with water, such as by a splash of water when clipping shrubbery due to moisture present on the grass, adjacent foundations or the like. Presently, ground faulting interrupters are being used in new and renovation construction, which are expressly for the purpose of minimizing the chances of electrocution. However, these types of devices have not been integrated into existing housing, which comprises the bulk of usage areas. Hence, safety is a problem from place to place and not merely between devices.

Another significant and distinct disadvantage, regardless of whether conventional ground faulting detectors are being utilized, is that fault current must generally flow through the user before the device detects and interrupts the flow of current therethrough. A further disadvantage is in the situation where there are no conventional ground fault interrupters and a separate interrupter is utilized with the device. Generally, conventional ground fault interrupters are somewhat bulky and cumbersome due to the fact that they not only detect and interrupt the flow of ground fault current, but also have user accessible test and reset buttons. This therefore drives up the cost and size requirements of any device wishing to utilize current interrupters.

Yet another disadvantage is that encompassing

standard ground fault interrupters into a handheld electrical device, such as a hair dryer or the like, requires that the case or housing must be specifically designed or re-engineered in order to accommodate the components. Thereafter, new molds must be made at considerable time and expense, and the outer profile of the handheld device must necessarily be changed.

Accordingly, it is an object of the present invention to provide a current path in a handheld electrical device which allows a current interruption device to operate more quickly.

It is a further object of the present invention to provide a current path in an electrically powered handheld device which avoids leakage current paths through the user of the device.

It is yet another object of the present invention to produce a device which incorporates a current interruption mechanism as an integral part thereof.

' Yet another object of the present invention is to produce a handheld electrical device having current interruption integral therein wherein reset, once the device has been tripped, can only be accomplished by a special tool.

A still further object of the present invention is to produce a handheld electrical device having a current interrupting mechanism integral therein which . is resettable only after inspection by a trained service person.

Yet another object of the present invention is to produce a handheld electrical device having an interrupting safety mechanism which is inexpensive to manu acture.

Another object of the present invention is to produce a device which adds few additional components and is easy to assemble.

Still a further object of the present invention is to produce a current interruption mechanism which is small and compact -and may also fit into existing

housing configurations and sizes.

Yet another object of the present invention is to produce a safety device which is retrofittable to existing designs. Still another object of the present invention is to produce a safety device which will automatically and completely electrically disconnect the line cord from any interior components in the device when an electrically hazardous condition exists. Another object is to hermetically seal all electrical interconnections with the line cord and the safety device.

It is also another object of the present invention to produce a safety device which is in the form of a module which is extremely compact. A further object is to produce an invention which may fit into existing casings of handheld devices and which does not necessitate additional engineering, retooling, molding, and the like. Still another object is to produce a device which does not require the change or enlargement of the outer profile of the case of the handheld electrical device.

Yet another object of the present invention is to produce a module which may be purchased by any manufacturer and which may therefore be manufactured as a standard item of standard size usable with any presently existing or future handheld electrical devices.

Another object of the present invention is to produce a device having an electrical path for driving a load therein Which comprises a ground plane disposed within the device in order to provide an electrical path, a detector with an input for detecting the presence of electrical current in the ground plane and an output for producing an electrical signal after detection of the presence of electrical current in the ground plane, and a current interrupter which has an input adapted to receive the output of the detector and

an output for interrupting the electrical path in the device.

Another object of the present invention is to produce a device a safety device for an electrical device having a first electrical path for driving a load therein and which provides an alternate ground path, comprising a ground plane disposed within the electrical device for providing an electrical ground path; a detector disposed within the electrical device, the detector comprised of a gate having a biasing lead for detecting the presence of electrical current in the ground plane, an input connected to the first electrical path, and an output and an output lead thereat for producing an electrical signal proportional to the current in the ground path; a current interruption device disposed within the electrical device, having an input adapted to receive the electrical signal of the output lead, and an output for interrupting the first electrical path in the electrical device; and an electrical storage device in series circuit relationship with the output lead.

Yet another object is a safety device for an electrical device having a first electrical path for driving a load therein and which provides an alternate ground path, comprising ground path disposed within the electrical device for providing an electrical ground path; a detector disposed within the electrical device, the detector comprised of a gating device having a biasing lead for detecting the presence of electrical current in the ground plane, an input connected to the first electrical path, and an output at an output lead thereat for producing an electrical signal proportional to the current in the ground path; a current interruption device disposed within theeleσtrical device, having an input adapted to receive the electrical signal of the output lead, and an output for interrupting the first electrical path in the electrical device; and an electrical storage device in

series circuit relationship with the output lead.

Finally, another object of the invention is a safety cartridge for a handheld electrical device wherein the electrical device has a first electrical path for driving a load therein wherein the handheld electrical device has an alternate ground path, comprising a module disposable within a handheld electrical device for interrupting the flow of electrical current in the first electrical path in response to detecting current in the alternate ground path.

BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be had to the accompanying drawings in which: Figure 1 is a representational view of an electric handheld hair dryer incorporating the present invention;

Figure 2 is a view substantially identical to Figure 1 illustrating alternate current interruption mechanisms;

Figures 3 and 4 show two alternate circuit configurations for effecting current interruption; and

Figure 5 shows an additional circuit configuration for effecting current interruption using a module approach.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to Figure 1, there is shown a diagrammatic view of the device encompassing the preferred embodiment of the present invention. Shown is an electric handheld hair dryer 10. It is to be understood that other types of handheld electric devices can and may be used without departing from the spirit and scope of the present invention such as, for example, electric curling irons, hand tools and the like. The hair dryer is comprised of a barrel 12 and handle 14 housing a number of components therein. At one end of handle 14 is an electric cord 16 which terminates at plug 18 and is suitable for typical

household use. An ON/OFF lever 20 is disposed at the base of handle 14 and may be of any suitable type such as slide, rotary or the like and may be single pole, double pole or any other suitable or desired configuration. At one end of barrel 12 is a front grill 22 which permits the passage of heated air therethrough as described more fully below. A screen 24 is typically located at the rear end of barrel 12 and utilized so that foreign matter, i.e., hair, cannot be sucked into barrel 12. A blower or fan is generally disposed adjacent screen 24 and takes air in through screen 24 and passes air over heating element 28. Heating element 28, in turn, heats the air before the air exits through the front grill 22. A ground screen or plane 30 is used to electrically connect front grill 22 to screen 24. Further, screen/plane 30 provides a continuous electrical path throughout the interior of hair dryer 10. By ground screen/plane 30 is meant any electrically conductive means to direct the current to a current interrupter device and, therefore, the ground plane 30 is not necessarily at earth "ground" potential. In this manner, should hair dryer 10 fall into water or should hair dryer 10 become wet to an unacceptable level, a ground path is provided between electrically conductive "live" areas in the hair dryer and the ground screen. The electrical connection between grill and screen 22 and 24 respectively via a ground screen/plane 30 may be accomplished in any number of suitable ways, such as crimp type fits, compression type fits, soldering or welding to mention a few. Any of the live areas can and may include exposed portions of hot or neutral wires 50,52 respectively, portions of heating element 28 or blower motor 26 as well as portions of ON/OFF switch 32 having load contacts 34 therein.

It has been determined that the ground screen/plane 30 may be in a number of embodiments or configurations, although all are acceptable as long as

a continuous electrically conductive ground path is provided. Accordingly, the ground screen/plane 30 may be in the form of a metal screen, or plating disposed on the interior portions of hair dryer 10, or on one side of heating insulators (not shown) which are typically disposed in barrel 12, and may be fabricated from aluminum or other type of metal foil. In this manner, a current return path is readily available between any of the electrically "live" components inside hair dryer 10 (as previously discussed) through water and hence to ground screen/plane 30. It has been found that this provision of an alternate return or ground path minimizes or eliminates the chance of current flow through a user, particularly when the unit merely has too much water present such as having water splashed on to it as it lies adjacent a sink or, in the case of a hand tool, it is laid down or adjacent to a puddle.

It has been found that the provision of a ground screen/plane 30 provides another distinct and significant. advantage in that present hair dryer or appliance design need not be changed from two conductor to three conductor cord sets (not shown) since present designs are most cost sensitive. For this reason I have found that provision of an Interrupt device, shown generally at 35, which is contained directly in handle 14, is appropriate. The interrupt device 35 is generally comprised of two portions, an electronic components portion 37 and a mechanical interlock portion 39. The function of the electronic component portion 37 is to detect and utilize electrical energy passing through or present on ground screen/plane 30. The mechanical interlock 39 is used to physically disconnect incoming power via electric cord 16 to the remainder of hair dryer 10.

The electronic components 37 include field effect transistor (FET) 48 having its gate terminal (G) connected to a terminal of biasing battery B _a , with the

remaining lead of the battery B _a connected to ground screen/plane 30. Therefore, the biasing battery B _a will render the FET 48 conductive in the event of any current leakage between ground screen/plane 30 and elsewhere in the device 10. A lithium or hearing-aid type battery B _a (or other long shelf life battery) may be utilized to provide an internal POWER SUPPLY which would cause mechanical interlock 39 to be energized regardless of whether plug 18 has power applied thereto, should the hair dryer be immersed and present during a shock hazard or the like. Therefore, when plug 18 is energized, the device would have been previously tripped and no chance of electrical short or the like can be applied to the user. Source terminal (S) of FET 48 is connected to hot lead 50 and to one terminal of condenser Cl. The remaining terminal of condenser Cl is connected to one terminal of coil 40 and to the cathode of diode Dl. The remaining terminal of diode Dl is connected to neutral lead 52. The drain terminal (D) of FET 48 is connected directly to the remaining terminal of coil 40.

Coil 40 is preferably a "latch" type solenoid coil having a movable rod 42 disposed therein. In the preferred embodiment of the present invention, movable rod 42 is either an integral part of or connected to ball 36. Therefore, energization of coil 40 causes ball 36 to be urged downward. However, it is to be understood that rather than rod 42 pulling ball 36 downward, similar satisfactory results may be obtained by having rod 42 merely push ball 36 upward. A stop 38 is provided to maintain ball 36 in a stationary position with ball 36 being used to bias spring-type load contacts 34 against appropriate terminals of ON/OFF switch 32. In this manner, when rod 42 is urged downward, due to electromotive force present in coil 40, ball 36 is similarly urged downwards with the result that load contacts 34 will electrically and

mechanically disconnect from the contacts of ON/OFF switch 32.

Therefore, when current exists between ground screen 30 and hot wire 50 (or neutral wire 52) , current will be permitted to flow through FET 48 with the result that coil 40 will be energized. Accordingly, in the preferred embodiment of the present invention, a ground fault in the traditional sense is not required in order to "trip" the present invention and prevent user injury. Rather, a current between ground screen/plane 30 and any electrically live component, such as is present during a shock hazard, will be detected and will result in operation of interrupt device 35. This shock hazard may be the result of immersion, high humidity, steel wool used during cleaning, or as a result of damage. Such damage may occur when, for example, a user tries to clean a toaster by using a knife and causes a short therein.

In this manner, the "user" is not required to be the electrical return path in a circuit and hence subject to shock before the device will trip. Another significant advantage of a battery in this type of circuit operation is that even if plug 18 is not energized, that is in a receptacle, the battery supplies the power to enable the interrupt device 35 to function. Accordingly, FED 48 and hence coil 42 are in effect "biased" in order to ensure rapid response time. Consequently, when the hair dryer 12 is eventually plugged in, there will be no chance of a shock hazard. When tripped, rod 42 will, as previously mentioned, preferably be urged downward. Further, in the preferred embodiment of the present invention, rod 42 is of an appropriate length such that after tripping it cannot and will not emerge through reset aperture/keyway 44 present in the underside of handle 14. In the preferred embodiment of the present invention, return of rod 42 to the normal position which enables load contacts 34 to be energized, cannot

be accomplished except by use of reset key 46. Accordingly, reset key 46 must be passed through reset aperture/keyway 44 in order to properly reorient rod 42. Preferably, keyway 44 and hence reset key 46 are of a cross-type configuration. In this manner, reset may only be accomplished by an individual having the correct reset key. Accordingly, it is preferred that only qualified service individuals be given a reset key, thereby adding an extra level of safety. Should interrupt device 35 trip, the user would be required to bring the device to any service center having qualified technicians who will then examine hair dryer 10 to ensure that the interior is dry, there are no damaged components, frayed wires or extraneous matter or the like, before the resetting of interrupt device 35.

Additionally, in the preferred embodiment of the present invention, it is preferred that load contacts 34 and ON/OFF switch 32 be at least moisture proof and preferably waterproof. Therefore, should a hair dryer be immersed in water, water cannot flow into the switch 32 which might permit a flow of current through switch 32 to load contacts 34 at any time. Alternately, in the present invention, a reset aperture/keyway may not be utilized with the result that a trained service technician must open up the hair dryer to ensure that they physically inspect the interior thereof and to effectuate reset of mechanical interlock 39.

Further, in the preferred embodiment of the present invention, condenser Cl is an eleσtret which is well known and understood by one skilled in the art. An eleσtret is highly desirable since it retains a charge, absent outside electrical stimulation. In this regard, it is not necessary for condenser Cl to build a charge prior to energization of coil 40. Since the electret retains its own charge, quick energization of coil 40 is inherent. Hence, this cuts down significantly on the interrupt time of mechanical

-- interlock 39. This is especially important since electromagnets, such as coil 40, typically have a relatively "long" energization time when viewed in terms of the time required for an electrical hazard to harm an individual. For this reason, a fast-acting FET is preferred. Additionally, should it be desired, a transient filter (not shown) may be inserted in series circuit relationship between the source terminal of FET 48 and the electrical connection to the ground screen/plane 30 should nuisanσe trips be a concern or a problem.

Referring now to Figure 2, a view substantially similar to Figure 1 is shown. Accordingly, only the differences between Figures 1 and 2 will be explained herein. Shown is trigger mechanism 54 which has a number of electrical appliances, connected thereto. Ground screen/plane 30 is connected via terminal A to trigger mechanism 54 while similarly terminals D and E of trigger mechanism 54 are respectively connected to coil 40. Terminal B is connected to the hot lead 50 while terminal C is σσnneσted to neutral lead 52, although, for the reasons previously mentioned, terminals B and C may be reversed. Aσcordingly, trigger mechanism 54 may enσompass a variety of different components or alternate embodiments.

Accordingly, referring now to Figures 3 and 4, schematic representations of alternate embodiments of the present invention may be viewed. More particularly, trigger mechanism 54, as shown in Figure 3, would supplant electronic components 37 disposed in Figure 1 while similarly trigger mechanism 54 of Figure 4 would supplant electronic components 37 of Figure 1. Referring to Figure 3, terminal A and hence ground screen/plane 30 is conneσted to one terminal of condenser C2. The remaining terminal of condenser C2 is connected to the gate terminal of FET 56. The drain terminal of FET 56 is conneσted to terminal D or one terminal of coil 40. Hot lead 50, terminal B, is

connected to the source terminal of FET 56 and to one terminal of condenser C3. The remaining terminal of condenser C3 is conneσted to the remaining lead of terminal E and hence, coil 42 and also to the σathσde of diode D2. The anode or diode D2 is σσnneσted to terminal C, neutral lead 52. It is preferred that σondensers C2 and C3 be eleσtrets, thereby providing a certain amount of bias to FET 56 and σoil 42 for the purpose of deσreasing the "trip time" of mechanical interlock 39. Additionally, by σonnecting to neutral lead 52, one half-σyσle of delay time is eliminated sinσe alternating current is utilized and hence lead 52 is at a high potential when lead 50 is at a low potential. Figure 4 performs in a manner similar to that of Figure 3 but is, of course, somewhat simpler. There, terminal A is connected to one terminal of condenser C4 while the remaining terminal of condenser C4 is σonneσted to the gate terminal of FET 58. The drain terminal of FET 58 is σonneσted to the D terminal while the sourσe terminal of FET 58 is σσnneσted to terminal B and to one terminal of σσndenser C5. The remaining terminal of condenser C5 is conneσted to terminal E. As before, it is preferred that σondensers C4 and C5 be eleσtrets, thereby shortening the interrupt time.

Referring now to Figure 5, another alternate embodiment is shown. Λσσσrdingly, only the differences between Figures 1 and 5 will be explained herein. Shown is safety cartridge 110 whiσh is preferably a "module" containing the components indicated therein. By safety cartridge or module is meant the enclosure of the electriσal and/or meσhaniσal σompσnents or interloσk of the present invention into a package. Therefore, the detection and current interruption portions may be packaged in a single enclosure (or separately) either in a case, or encapsulated, or any other similar means for manufacturing purposes. It is

preferred, although not absolutely necessary, that safety σartridge 110 be sealed so as to be waterproofed, suσh as by hermetiσ sealing or enσapsulation or the like. Therefore, the σartridge 110 may be an off-the-shelf item whiσh is readily distributed to manufacturers of handheld eleσtriσal deviσes. Disposed within safety σartridge 110 is σurrent interruption σirσuitry, that would make the module perform the same funσtion as eleσtroniσ and meσhaniσal σσmponents 37, 39 previously desσribed.

Readily apparent when viewing figure 5 is that due to the preferred enσapsulatiσn of σartridge and the position of disσonneσt 122 prior to the σontaσts of the on/off εwitσh 20, all components in the - hand held device 10 are autσ atiσally and σompletely electrically isolated from the line cord 16. It has been found that this offers signifiσant safety advantages over previously known designs.

Here, sensing eleσtret 114 has one terminal σonneσted to ground sσreen/plane 30 and the remaining terminal σσnneσted to the base terminal of PNP transistor 112. It is understood that an NPN, a FET or any other type of eleσtroniσ triggering or gating deviσe may be utilized without departing from the spirit and sσσpe of the present invention. The emitter of transistor 112 is σonneσted to one terminal of the σσil of magnetiσ trip switσh 118. The σolleσtor terminal of PNP transistor 112 is σonneσted to one terminal of tripping eleσtret 116 with the remaining terminal of tripping eleσtret 116 σσnneσted to the remaining terminal of the σoil σomprising trip switσh 118. The σolleσtor of PNP transistor 112 is also σonneσted to hot lead 50 inside the handheld deviσe itself. An aσtuating bar 120 disσonneσts σontaσt arms 122 from contacts 124 during actuation of the device during an electriσal hazard. A reset aperature 126 is axially disposed from actuating bar 120 and is an optional item which may be used to reset the device

when tripped similar to the reset aperature 44 of Figure 1. Aperture 126 is preferably a seal and is adjaσent sealing plug 130 disposed in the housing of the hand held eleσtriσal device 10. Therefore, reset of the cartridge after tripping may be aσσσmplished by removal of plug 130 and the insertion of a reset tool as desσribed above. Acσordingly, the seal of aperture 126 may be replaσeable or a "self sealing" type of seal. A plurality of termination or terminating points 128 are utilized to interσonneσt the safety σartridge 110 with the different eleσtrical cσntaσt points inside the hair dryer 10. It is to be understood, however, that these terminations should be internal to the safety σartridge 110, thereby minimizing the σhanσes of eleσtriσal short between them should an eleσtrically hazardous condition present itself. Aσσordingly, eaσh terminating point 128 is preferably hermetiσally sealed in the form of plugs similar to reset aperature 126. Similarly, seal 132 hermetically seals the joint between the σartridge 110 and σord 16. However, any arrangement whiσh prohibits the introduσtion of extraneous matter into the eleσtriσal σonneσtion is aσσeptable, suσh as waterproof type σσnneσtσrs whiσh are readily available and known to one skilled in the art. Similarly, with respeσt to eleσtriσ σord plug 16, 18 respeσtfully, the entire safety σartridge 110 is preferably sold with the σord and plug 16, 18 attaσhed thereto or eleσtriσal σonneσtion may be thereafter made by the manufaσturer or assembler of the hair dryer 10.

It is to be understood that although only several variations of eleσtroniσ components are shown, other variations may be utilized without departing from the spirit and scope of the present invention. For example, a standard ground fault interrupter cirσuit such as LM1851 Ground Fault Interrupter produced by National Semiconduσtσr Corporation whiσh are readily

available and known to one skilled in the art may be utilized. Additionally, other types of meσhaniσal interlσσks may be utilized without departing from the spirit and sσope of the present invention. Further, σurrent interruption may be aσcomplished by replacing the eleσt*—»niσ σomponents and/or meσhaniσal interrupt with othet suitable σurrent interrupting deviσes, such as, for example, high σurrent transistors, latσhing relays, opto-isolators, and the like. Aσσσrdingly, the present invention prσduσes an extremely safe deviσe for individuals to utilize which enσompasses a present design without the need for retooling and the like. Additionally, the present invention adds minimal σost while substantially inσreasing the safety of handheld deviσes suσh as hair dryers and the like. Further, the present invention may be enσompassed into other small applianσes, suσh as, mixers, blenders, and other kitσhen-type aids.

Having thus desσribed the present invention in detail, it is to be understood that the foregoing desσriptiσn is not intended to limit the spirit and sσope thereof. What is desired to be proteσted by Letters Patent is set forth in the appended σlai s.