The present invention relates to an instrument for cut¬ ting hair, as one of the instruments which are normally used by hairdressers, capable of simultaneously cauterize the cut hair ends.

Until now there has not been any relation among the func¬ tions performed by means of conventional scissors by hair¬ dressers and other conservatory acts which are performed on hair by means of other specialized instruments, in particular for preventing the growth of bifurcated hair ends, which is a frequent but not exclusive concern of women keeping relative¬ ly long hair. It has been heretofore a common practice of hairdressers to cure the tendency of hair to bifurcate by flame treating the hair, using a candle or a special torch. These treatments are time consuming and unpleasant to both the customer-patient and the operator, moreover the risks of inadvertently overda aging the hair or to accidentally cause more serious damages is attendant.

A main objective of the present invention is to provide an instrument for simultaneously cauterize the cut hair ends while cutting hair in a safe and effective manner, while causing the least uncomfort to the customer.

These objectives and other advantages are achieved by means of the instrument object of the present invention which consists in a hair cutting instrument having, under this as¬ pect a substantially common configuration, while the cutters or the cutter thereof is electrically heated to a temperature comprised in the range of 150°C and 300°C for cauterizing the hair being cut by the blade.

It has been found that hair cut with a blade held at such a high temperature show a markedly reduced tendency to bifur¬ cate upon growth and the hair comparatively appear to benefit overall from the high temperature cut treatment, by develop¬ ing an improved glossy appearance and an overall reinvigora- tion. These positive effects may be attributed to the simul¬ taneous cauterization of the cut produced in the hair which prevents a tendency of the hair to desquamate or to "loosen"

at the freshly produced cut which may originate degenerative processes such as the bifurcation of the hair and the like. In this respect, the high temperature cut produced by the in¬ strument of the present invention may be seen as providing a positive aseptic "sealing" of the cut which prevents degene¬ rative effects after the cutting.

According to a first embodiment of the invention, the in¬ strument is a pair of scissors, at least a blade or prefera¬ bly both blades of which are heated. However other embodi¬ ments may be in the form of single blade hair cutting instru¬ ments such as a razor and also of a comb-razor, as often used by hairdressers in place of scissors for performing special hairdressings. The cutter or the cutters, as the case may be, are preferably heated by electrical heaters which are prefe¬ rably set into an especially designed blade holder portion of the instrument in order to generate the required heat as close as possible to the cutting edge. Most preferably the instrument has heater elements incorporated therein and con¬ nected to a low voltage power supply through an insulated cable and most preferably the instrument is also provided with a thermocouple set in proximity of the heated blade and which is connectable through the same (multiconductor) insu¬ lated cable to a temperature control unit in order to main¬ tain the cutting blade or the cutting blades to a presettable constant temperature during the utilization of the hair cutting instrument. The temperature control-power supply unit may be combined in a wheeled caddie and be provided with a panel including all the control and temperature preselection switches and with a display for monitoring the correct tempe¬ rature to which the cutters are heated.

The different aspect and advantages of the haircut in¬ strument of the present invention will be more easily appre¬ ciated through the following detailed description of several embodiments and reference to the attached drawings, wherein:

Figure 1 is a schematic partial representation of a pair of scissors having an electrically heated cutter in accord¬ ance with the present invention;

Figure 2 is an enlarged partial cross sectional view in the plane II-II indicated in Fig. 1 of one blade of the scis-

sors incorporating an electrical heating element;

Figure 3 is an enlarged partial cross sectional view in the plane III-III indicated in Fig. 1;

Figure 4 is a schematic perspective view of a stand-by receptacle for the electrically heated scissors of Fig. 1, equipped with a temperature sensor for controlling the heating of the scissors during stand-by periods;

Figure 5 is a schematic perspectic view of a complete ap¬ paratus;

Figure 6 is a view of a pair of scissors with heated blades according to a further embodiment of the present in¬ vention;

Figure 7 is a schematic representation of the heated scissors of Fig. 6;

Figure 8 is a perspectic view of a caddie-mounted appara¬ tus of the invention;

Figure 9 is a schematic partial perspectic view of a ra¬ zor with a heated blade;

Figure 10 is an illustrative view of a comb-razor with electrically heated cutters.

With reference to Figures 1 to 5, a pair of scissors 1 conventionally comprises two blades 1' and 1", pivoted to¬ gether by means of a screw pivot 11.

According to the present invention, at least one blade or knife of the scissors is heated, at least in correspondence of a cutter piece 10. The cutter 10 is preferably replaceable and may be fixed to respective the blade holder, knife body 1" of the scissors by means of several screws 14. The knife 1" has a recessed portion wherein a flat strip heating resis¬ tor 2 is disposed, preferably by interposing a layer of ther¬ mally insulating material 22 having a suitably "L"-shaped cross section, in order to reduce heat dispersion through the knife 1" of the scissors and to minimize the power which is necessary for heating the cutter 10 having a sharpened cut¬ ting edge 10' .

The heads of the screws 14 for fastening the cutter are received into purposely stepped holes 13 formed through the cutter piece 10, which holes are preferably made with a cer¬ tain clearance in order to create a space which may be filled

with a thermally insulating paste 134, when mounting the cut¬ ter. The sleeve of thermally insulating cement 134 will avoid the formation of thermally conductive "bridges" through the assembling screws 14.

The heating resistor 2 is powered through two conductors 20 and 20' which may be laid into a purposely created chan¬ nel, cut in the handle portion of the scissors, and the elec¬ trically insulated conductors 20 and 20* may be permanently set in the channel by means of a potting compound.

An insulated, two-conductor, power-supply cable departs from the handle portion of the scissors and, in the case that both blades of the scissors are electrically heated, the two pairs of conductors emerging from each handle portion of the two knives of the scissors may be electrically connected to¬ gether in parallel or in electrical series and through a sin- gle power-supply cable 21 provided with an end plug 22, the heating resistances may be powered by connecting the plug 22 into an output socket of a power supply 5 which may comprise, as shown, a transformer 5' and an electronic circuitry with an adjusting potentiometer 55, for providing an appropriate power supply in order to attain the desired temperature which may be programmed by means of the knob 55, and controlled by a temperature sensing system 66-66'-66" during stand-by peri¬ ods. In Figures 4 and 5 is also depicted a stand-by scissors holder 6 in the form of a receptacle into which the scissors may be inserted during pauses of the hair cutting work. The scissors holder 6 has a top opening 6* and is provided inside with scissors rests 60, 61, 62 and 63, with a thermostat 66" and with a microswitch 65 for confirming to the control cir¬ cuit the insertion of the scissors in the stand-by holder. As shown in Fig. 5, the microswitch is connected to the power supply through the cable 65' and the thermostat 66" is con¬ nected by the cable 66' to a temperature controlling switch 66. According to this embodiment, the user adjusts the de¬ sired temperature of the cutters of the scissors by setting the knob 55. After the scissors have attained the desired temperature, which is normally comprised between 150°C and 350°C, preferably between 180°C and 230°C, the scissors may be used for cutting hair which are desirably cauterized by

the contact with the heated cutters of the scissors. During stand-by periods, the scissors may be placed in the holder 6 and by means of the presence confirmation given by the microswitch 65, the temperature of the scissors becomes thermostatically controlled and the control switch 66 provides to interrupt the power supply to the heating resistances when the temperature sensed by the thermostat 66" becomes higher than a preset value. This prevents overheating during stand-by periods and has a power saving function.

According to a preferred embodiment of the invention, a pair of scissors has both cutters heated by heating resist¬ ances set in the cutter holding portion of both knives of the scissors in order to promote a most effective cauterizing ac¬ tion during the cutting of hair, and the scissors are also provided with a thermocouple or similar temperature sensor set near at least one of the heated cutters in order to im—- plement a precise and constant temperature control through an appropriate electronic circuitry. Moreover according to such a preferred embodiment, the cable connection between the scissors and the temperature controlled power supply unit is advantageously made by means of a single cable connection through only one of the two handle portions of the scissors. This permits a freer use of the scissors without the hin¬ drance which is inevitably created by having electric cable connections departing from both handle portions of the scis¬ sors.

The problem of providing the necessary electric current path through the two heating resistances set in the two pivoted blade portions of the scissors, has been successfully resolved by exploiting the pivoting screw of the scissors as part of the electric path and by utilizing the metal bodies of the scissors also as part of the electric path.

The scissors made in accordance with this preferred em¬ bodiment are shown in Fig. 6, 7 and 8. As schematically shown in Fig. 7, the scissors comprise two similar metallic blade holding portions 31 and 32, having a recess on their opposing faces, 33 and 34, respectively.. The metallic blade-holding portions have a tail shaped termination, 35 and 36, respecti¬ vely, and a hole for a pivot screw, 37 and 38, respectively.

Custo arily the hole 37 of the blade holder 31 is threaded while the hole 38 of the blade holder 32 has a diameter of a sufficient clearance for a pivot screw 39 to pass through.

The handle portion of both knives of the scissors, 40 and 41, respectively, are made of a moldable plastic material having a low heat conductivity and are permanently joined to the metallic blade-holding portions 31 and 32; the joint being reinforced by the tail terminations 35 and 36.

Within the receptacles 33 and 34 are installed the heat¬ ing resistances 42 and 43. Each resistance has one end sol¬ dered or otherwise electrically connected to the respective metallic blade holder body, respectively at 44 and 45. Each resistance is connected at its other end to an insulated con¬ ductor, 46 and 47, respectively. These insulated wires permit the connection of the heating elements to the power supply outlet. In the left hand knife of the scissors, the insulated- wire 47 runs along the recess 33, housing the resistance 43, and passes through the conduit purposely formed in the molded plastic handle portion 41 to emerge through a hole at the end of the handle portion. The insulated wire 46 of the other knife of the scissors runs into the recess 34, housing the resistance 42, and passes through a conduit purposely formed in the molded plastic handle portion 40 and emerges through a hole in a neck portion of the handle. The insulated conductor forms several elicoidal turns before entering through a hole in the neck portion of the opposite handle portion of the scissors and passing through a channel purposely formed with¬ in the molded plastic body to emerge, together with the other isolated wire 47, through the same hole of the handle portion of the left hand knife of the scissors.

A two-conductor, insulated cable 48 is similarly passed through the same channel of the plastic portion and disposed in the recess 33 and the two conductors terminate with a thermocouple junction 49 which is suitably disposed as near as possible to the respective heated cutter of the scissors. The electric current path through the heating resistors 42 and 43- comprise the metallic body of both blade holder por¬ tions of the scissors, electrically connected together by the conducting pivoting pin 39 and the looped portion 46' of the

insulated wire 46. In this way the electric circuit is closed while having a cable connection to only one of the two hand. •: portions of the scissors. This arrangement gives a greater freedom to the user of the scissors by eliminating the hin¬ drance represented by having cables departing from both handle portions. The assembled scissors are depicted in Fig. 6. The bridging looped portion 46 ^* is conveniently made with a single isolated wire of a particularly elastic material and does not hinder the use of the scissors.

The use of a thermocouple 49, capable of sensing the ex¬ act temperature of the cutters of the scissors, permits the implementation of a constant precise temperature control by means of an electronic circuitry. In this way the power sup¬ ply to the heating resistances may be automatically modulated so as to maintain a predefined constant temperature of the cutters in any condition of use and of stand-by of the scis¬ sors.

The electronic control and power supply may be arranged on a wheeled caddie, as shown in Fig. 8, which may be pro¬ vided with a control panel 50 containing all the controls and displays for regulating and monitoring the temperature of the cutters.

The invention may also be embodied in a form different from the most common scissors. For example, the same cauter¬ izing action on the hair being cut may be effected by means of a razor type instrument as the one depicted in the sche¬ matic partial view of Fig. 9. According to this embodiment, a razor blade 51 may be mounted on a special blade holder 52 containing an electric heating element 53 and preferably a temperature sensing thermocouple (not shown in the figure) for controlling the temperature of the blade 51.

Fig. 10 depicts yet another embodiment of the instrument object of the present invention, in the form of a "comb- razor" 54. This hair cutting instrument, has heated blades 55 between the teeth of the comb. Also in this case the blades 55 may be heated to the desired tempearature by an electric heating element provided within the body of the instrument.