Hair styling using dielectric heating

Abstract

In a hair styling device (100) comprising electrodes (102) for applying a radio-frequent signal to hair, a frequency of the radio-frequent signal is between 50 MHz and 90 MHz. Preferably, a voltage of the radio-frequent signal does not exceed 30 V, while a voltage not exceeding 10 V would work well in a configuration that applies another heat source (103) for heating hair up till a first temperature that is no more than 150° C. (and thus lower than a critical temperature at which hair cuticle damage will occur), and the radio-frequent electrodes (102) for in combination with heat from the other heat source (103)—selectively heating a hair cortex to a second temperature exceeding the first temperature and sufficiently high for hair styling.

Description

FIELD OF THE INVENTION[0001]The invention relates to a hair styling device using dielectric heating.BACKGROUND OF THE INVENTION[0002]US 2017 / 0360174 discloses an apparatus that manipulates the shape of hair using dielectric heating. Typically, the apparatus includes opposing first and second electrodes respectively provided on first and second arms that are movable towards and away from one another. Drive circuitry supplies electrical energy to the first and second electrodes, to cause an alternating electric field to be produced in the vicinity of the electrodes in use, and thereby cause dielectric heating of hair placed between the electrodes in use. Sensing circuitry senses a change in coupling of energy from the alternating electric field to the hair during heating of the hair. Control circuitry controls the drive circuitry to vary the electrical energy supplied to the first and second electrodes in dependence upon the sensed change in coupling.[0003]The range of frequencies is ...

AI Technical Summary

Benefits of technology

[0005]Embodiments of the invention are based on the recognition that in the frequency range of below 40 MHz, as preferred by the prior art US 2017/0360174, the loss tangent and heat generation significantly depend on the moisture content. So, with frequencies below 40 MHz, as preferred by the prior art, the power levels need to be adapted depending on the water content of the hair. Moreover, since the water content changes significantly during the styling process, heat control requires real-time accurate monitoring of water content to provide optimal heating effects, to prevent undesirable over-heating effects and poor efficacy due to under-treatment from occurring. In that sense, it is desirable to have a method that is less dependent on the water content and which requires less critical sensing and control of treatmen

Problems solved by technology

Drive circuitry supplies electrical energy to the first and second electrodes, to cause an alternating electric field to be prod

Images