RF treatment apparatus, method of controlling RF treatment apparatus and skin treatment method using RF energy

1. An RF treatment apparatus, comprising:

an RF generator generating RF energy;

an electrode applying the RF energy for a target tissue;

a sensor unit configured to sense the RF energy; and

a controller that is configured to:

control output of the RF generator,

receive a sensing value from the sensor unit,

calculate impedance of the target tissue,

determine when the target tissue that is denatured by the RF energy is in a coagulation phase, and determine that a transition from the coagulation phase to an ablation phase is occurring for a specific period after an initial period, and

cut off the RF energy before the tissue enters the ablation phase, wherein the controller determines whether the tissue transition is occurring based on a rate of change of impedance, and the rate of change of impedance is determined using a product or average of impedance values measured in three consecutive time periods.

2. The RF treatment apparatus of claim 1 , wherein:

the controller determines that the transition from the coagulation phase to the ablation phase is occurring when a parameter exceeds a threshold, and

wherein the parameter is based on the rate of change of impedance.

3. The RF treatment apparatus of claim 2 , wherein the parameter is defined as a product of a rising time in which impedance increases for the three consecutive time periods and the rate of change of impedance for the rising time.

4. The RF treatment apparatus of claim 2 , wherein the parameter is defined as a product of a specific time and an average of rate of change of impedance up to the specific time.

5. The RF treatment apparatus of claim 2 , wherein:

the sensor unit measures current, a voltage and power applied to the electrode, and

the controller calculates the rate of change of impedance as a root mean square (RMS) when calculating the impedance.

6. The RF treatment apparatus of claim 5 , wherein the controller controls an output voltage of the RF generator so that the power does not exceed a specific range.

7. The RF treatment apparatus of claim 2 , wherein the electrode comprises at least one of a contact type and an insertion type.

8. The RF treatment apparatus of claim 1 , wherein the controller is further configured to perform in a coagulation mode in which the controller is configured to determine that the transition from the coagulation phase to an ablation phase is occurring for a specific period after an initial period, and reduce the amount of RF energy applied by the electrode at a predetermined time to maintain the coagulation phase without entering the ablation phase.

9. A method of controlling an RF treatment apparatus, comprising steps of:

applying RF energy to a tissue through an electrode;

calculating impedance of the tissue for a plurality of time periods;

calculating a parameter based on a rate of change of impedance using impedance values or changes for at least three consecutive time periods of the plurality of time periods during which RF energy is applied;

determining that a transition from a coagulation phase to an ablation phase is occurring after an initial period by comparing the parameter to a threshold; and

cutting off the RF energy when the parameter exceeds the threshold.

10. The method of claim 9 , wherein the parameter is defined as a product of a rising time from a current time to a specific time and the rate of change of impedance for the rising time.

11. The method of claim 9 , wherein the parameter is defined as a product of a rising time from a current time to a predetermined time before and an average of rate of change of impedance for the rising time.

12. The method of claim 9 , wherein the step of determining whether the parameter exceeds the threshold is performed after a specific time from a point of time at which the RF energy is applied.

13. The method of claim 9 , wherein the step of positioning the electrode in the tissue is performed by at least one of a contact and insertion of the electrode on and into the tissue.

14. A skin treatment method using RF energy, comprising steps of:

positioning an electrode in a tissue;

heating the tissue to a treatment temperature by applying RF energy to the electrode;

measuring the RF energy applied to the tissue for a plurality of time periods;

calculating a rate of change of impedance of the tissue to which the RF energy is applied using a product or average of impedance changes for at least three consecutive time periods of the plurality of time periods;

comparing a parameter based on the rate of change in the impedance of the tissue to a threshold;

determining that a transition from a coagulation phase to an ablation phase is occurring after an initial period when the parameter exceeds a threshold; and

cutting off the RF energy when the transition occurs in the tissue based on a result of the comparison between the parameter and the threshold in order to prevent ablation of the tissue.