JP7066059B6 - Hair styling using dielectric heating - Google Patents

Description

The present invention relates to a hair styling device using dielectric heating.

US2017 / 0360174 discloses a device for manipulating the shape of hair using dielectric heating. Typically, the device comprises opposing first and second electrodes provided on the first and second arms that are movable towards each other and movable away from each other, respectively. The drive circuit supplies electrical energy to the first and second electrodes to generate an alternating electric field in the vicinity of the electrodes in use, which causes dielectric heating of the hair placed between the electrodes in use. .. The sensing circuit senses changes in the binding of energy from the alternating current field to the hair during the heating of the hair. The control circuit controls the drive circuit to change the electrical energy supplied to the first and second electrodes based on the sensed change in coupling.

The frequency range is preferably from about 1 MHz to about 100 MHz. More preferably, the frequency range is from about 10 MHz to about 100 MHz. More preferably, the frequency range is from about 20 MHz to about 40 MHz, which are well suited for consumer products. This is because they have limited wave propagation (unlike microwaves) and therefore do not pose a health risk or unwanted EMC (electromagnetic compatibility) effect. An AC voltage of about 50V is used.

In particular, an object of the present invention is to provide an improved hair styling device using dielectric heating.

The present invention is defined by the independent claims. Preferred embodiments are set forth in the dependent claims.

The embodiment of the present invention is based on the recognition that dielectric loss tangent and heat generation largely depend on the water content in the frequency range of 40 MHz or less, which is preferred in US2017 / 0360174. Therefore, at frequencies below 40 MHz, which is preferred in the prior art, the power level needs to be adapted based on the moisture content of the hair. In addition, since the water content changes significantly during the styling process, heating control measures the water content in real time to obtain the optimum heating effect so as to prevent unwanted overheating effects and poor effects due to lack of treatment. It needs to be monitored accurately. In that sense, a method that is less dependent on water content and does not require critical sensing and control of treatment parameters is desirable. According to one aspect of the invention, this can be achieved by using frequencies in the range 50 MHz to 90 MHz, which makes the treatment less dependent on water content and at the same time due to dry hair. Will provide about the same effectiveness as about 1 MHz. Preferably, the voltage of the radio frequency signal does not exceed 30V. A first heat source for heating the hair to a first temperature not exceeding 150 ° C. (thus lower than the critical temperature at which hair cuticle damage occurs), even at a voltage not exceeding 10 V. It works well in configurations that apply with radio frequency electrodes to selectively heat the hair cortex in combination with heat from another heat source, above temperature and up to a second temperature high enough for hair styling.

It is a figure which shows the graph of the dielectric loss tangent pair frequency. It is a figure which shows one Embodiment of the hair styling apparatus by this invention.

These and other aspects of the invention will be apparent from the embodiments described below and will be described with reference to these embodiments.

FIG. 1 shows graphs of dielectric loss tangent to frequency with respect to wet hair W and dry hair D, respectively. The graph shows that at frequencies below 40 MHz, the difference in dielectric loss tangent between wet and dry hair W is relatively large, while at high frequencies above 50 MHz, the difference is much smaller. The results show that at such high frequencies it is not necessary to accurately and constantly measure the water content of the hair while styling the hair. The graph shows that frequencies above 90 MHz have similar advantages, but frequencies above 90 MHz reduce the effectiveness of RF heating.

FIG. 2 shows an embodiment of the hair styling device 100 according to the present invention, which is similar to application WO2017 / 080957 (reference number 2015PF01581), but in the embodiment of FIG. 2, high frequency (RF) heating is used instead of light. There is a difference that it is used. The hair styling device 100 has two claws 101 hinged to sandwich the hair strands. Each claw 101 has an array of RF electrodes or large area electrodes 102, which selectively heats the hair cortex to a temperature of about 170 ° C. required for styling. This temperature can be controlled to prevent other undesired heating effects such as melting and vaporization expected at 250 ° C and 1200 ° C, respectively.

Each claw 101 optionally has a separate heat source 103, which brings the hair to a first temperature of 150 ° or less, preferably 140 ° or less, for example 120 ° or less, in order to enhance the dielectric properties of the hair. Preheating may be performed directly or indirectly. The combined heating effect from the other heat source 103 and the RF electrode 102 provides the temperature of about 170 ° C. required for styling.

An additional hair conductivity sensing control 104 can be used to measure the dielectric properties of the hair and adjust the power to optimize the treatment. An additional thermal control system 105 can be used to adjust the temperature setting and treatment time. For straightening / styling hair, the strands of hair are sandwiched between the plates and moved until the hair is styled.

Contact-resistant RF heating is preferred over non-contact capacitive RF heating for consumer suggestions because of the high voltage and power required for one of the latter or the long cut time. In the embodiment of FIG. 2, a voltage of 10 V or less is suitable for use at high frequencies in the range between 50 MHz and 90 MHz.

It should be noted that the above embodiments are illustrative, but not limiting, to the invention, and one of ordinary skill in the art can design many alternative embodiments without departing from the appended claims. For example, although the embodiment shown in FIG. 2 is a straightening device, the present invention can be used instead to curl hair. In the claims, any reference code placed between the parentheses should not be construed as limiting the claims. The word "have" does not preclude the existence of elements or steps other than those described in the claims. The word "a" or "an" preceding an element does not preclude the existence of a plurality of such elements. The present invention can be realized by hardware including several separate elements and / or by a properly programmed processor. In a device claim enumerating several means, some of these means can be implemented by one and the same item of hardware. The means described in the different dependent claims can be used in combination to their advantage.

Claims (3)

It ’s a hair styling device.
Has electrodes that apply radio frequency signals to the hair between the electrodes
A hair styling device in which the frequency of the radio frequency signal is 50 MHz or more and 90 MHz or less. The hair styling device according to claim 1, wherein the voltage of the radio frequency signal does not exceed 30 V. The hair styling device further has a different heat source than the electrodes, which heats the hair to a first temperature not exceeding 150 ° C.
The hair styling device according to claim 2, wherein the voltage of the signal of the radio frequency does not exceed 10 V.

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