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CN-121986544-A - Safety circuit system

CN121986544ACN 121986544 ACN121986544 ACN 121986544ACN-121986544-A

Abstract

A safety circuit for a low heat capacity hair styling appliance is described. The safety circuit may rely on a deliberately designed weak link or temperature sensor, as well as electronic circuitry that can remove power from the heater electrode, as well as a dual microprocessor design.

Inventors

  • ANDREW WILLIAM NORFOLK
  • AZIZ TOKGOZ
  • Ian Richard. Thorpe
  • ROBERT ALEXANDER WEATHERLY

Assignees

  • 洁美来有限公司

Dates

Publication Date
20260505
Application Date
20241004
Priority Date
20231004

Claims (20)

  1. 1. A hair drying and/or styling apparatus comprising: A heater for providing heat for drying and/or styling hair, the heater having a heating rate of greater than 30 ℃ per second; A power supply for supplying power to the heater, and Safety circuitry for disconnecting the power supply from the heater in response to a overheat triggering event or a fault detection event; Wherein the safety circuitry is configured to disconnect the power supply from the heater for a period of between 0.02 seconds and 2 seconds of the overheat triggering event or the fault detection event.
  2. 2. The hair drying and/or styling device of claim 1 wherein the heater comprises independently operable heater zones, and wherein each heater zone comprises at least one independently operable heater electrode.
  3. 3. A hair drying and/or styling device according to claim 2 wherein the safety circuitry is configured to de-energize the heater in dependence upon detection of the overheat trigger event or the fault detection event in any one (or more) of the heater regions, preferably to de-energize all heater electrodes in dependence upon detection of the overheat trigger event or the fault detection event in any one (or more) of the heater regions.
  4. 4. A hair drying and/or styling device according to any one of claims 1 to 3 wherein the safety circuitry comprises an array of temperature sensors, and means for detecting whether any one (or more) of the temperature sensors is indicative of a overheat triggering event.
  5. 5. The hair drying and/or styling device of claim 4 wherein at least one of the temperature sensor arrays is provided in thermal connection with one or more heater regions of the heater, or wherein at least one of the temperature sensor arrays is provided in thermal connection with each heater electrode of the heater.
  6. 6. A hair drying and/or styling device according to any preceding claim wherein the safety circuitry comprises at least one weak link configured to melt at a predetermined temperature indicative of a overheat triggering event, thereby opening the circuit.
  7. 7. The hair drying and/or styling device of claim 6 wherein at least one weak link is provided in thermal connection with one or more heater regions of the heater such that the weak link is configured to melt when any of the corresponding heater regions exceeds the predetermined temperature, or wherein at least one weak link is provided in thermal connection with each heater electrode of the heater such that the weak link is configured to melt when the corresponding heater electrode exceeds the predetermined temperature.
  8. 8. The hair drying and/or styling apparatus of claim 7 wherein the safety circuitry is configured to disconnect power to only the corresponding heater region and/or heater electrode in accordance with at least one weak link melting.
  9. 9. The hair drying and/or styling device of any one of claims 6 to 8 wherein the at least one weak link is configured to melt within a period of between 0.02 and 2 seconds, preferably between 0.025 and 1 seconds, and more preferably between 0.05 and 0.6 seconds of the overheat trigger event.
  10. 10. The hair drying and/or styling device of any one of claims 6 to 9 wherein the at least one weak link has a mass of 0.1 gram or less and preferably 0.5 milligrams or more.
  11. 11. Hair drying and/or styling device according to any of claims 6 to 10, wherein the at least one weak link comprises a first soldering material having a first melting temperature and a second soldering material having a second melting temperature, preferably wherein the second melting temperature is higher than the first melting temperature and the second soldering material constitutes a connection, preferably a physical connection and an electrical connection, between the first soldering material and an electrical conductor of the electrical circuit.
  12. 12. The hair drying and/or styling device of claim 11 wherein the at least one weak link is deposited by heating to a temperature between the first and second melting temperatures.
  13. 13. The hair drying and/or styling device of claim 11 or 12 wherein the combined mass of the first and second welding materials is 0.1 gram or less, and preferably 0.5 milligrams or more.
  14. 14. The hair drying and/or styling apparatus of any one of claims 6 to 13 wherein the substrate on which the weak link is provided has a solder resist coating to facilitate removal of melted solder to ensure electrical disconnection.
  15. 15. The hair drying and/or styling device of any one of claims 6 to 14 further comprising a microfluidic structure adjacent the at least one weak link for guiding out the melted material and thereby breaking the electrical connection.
  16. 16. The hair drying and/or styling device of any one of claims 6 to 15 wherein the at least one weak link is resiliently biased such that the electrical connection breaks when melted.
  17. 17. A hair drying and/or styling device as claimed in any one of claims 6 to 16 wherein the at least one weak link is connected to a switch, preferably wherein the switch is configured to de-energise the heater in dependence on the at least one weak link melting.
  18. 18. The hair drying and/or styling device of any one of claims 6 to 17 wherein the safety circuitry comprises an array of weak links, wherein the weak links are connected in series to a switch, preferably wherein the switch is configured to de-energize the heater in dependence on melting of at least one weak link in the array of weak links.
  19. 19. The hair drying and/or styling device of any one of claims 6 to 18 wherein the at least one weak link is coupled to a switch, whereby in the event of one or more of the at least one weak link melting, the switch is configured to change state and prevent power from being provided to at least one heater electrode of the heater.
  20. 20. The hair drying and/or styling device of claim 19 wherein the heater comprises a plurality of heater electrodes, and wherein a change in state of the switch prevents power from being provided to each of the heater electrodes.

Description

Safety circuit system Technical Field The present invention relates to a safety circuit system and method for a hair styling appliance. The invention also relates to a hair styling appliance having such a safety circuit system for ensuring a safe operation of the hair styling appliance by a user. Background There are a variety of devices for styling hair that use heat to effect a change in hair shape. Examples include hair straighteners, curling irons, and curlers (HAIR CRIMPER). The hair styling apparatus heats the hair directly above its glass transition temperature, at which the hair becomes plastic. Hair is styled at a temperature above its glass transition temperature and once cooled, the hair generally retains its styling until it becomes wet after it has been cooled. Hair styling appliances, such as hair straighteners (as shown in fig. 1a and 1 b), typically comprise a heating surface (typically defined by a heating plate) that heats hair in contact with the heating surface. Other styling devices, such as curling irons, provide a curved heating surface, but the principle remains unchanged, i.e., the hair is heated above its glass transition temperature and styled by the user. Existing hair styling appliances typically use relatively thick heating plates or tubes that provide a certain amount of heat capacity to the hair styling appliance. Because of the heat capacity, heaters require time to heat and once heated they may require a considerable amount of time to cool. This heat capacity makes it difficult to control the heating of the hair and can lead to overheating or underheating of the hair. It is generally desirable to develop hair styling appliances that use heaters that have a lower heat capacity and therefore can heat and cool more quickly. Therefore, such low heat capacity heaters are more sensitive and easier to control. However, the inventors have recognized that existing safety circuitry and methods typically used to ensure safe operation of hair styling appliances are not suitable for use with hair styling appliances employing such low heat capacity heaters. Accordingly, there is a need for an improved safety circuit system and method that ensures safe operation of hair styling appliances that use lower heat capacity heaters. Existing hair styling appliances typically use a thermistor for temperature sensing to control the heating of the heater or as part of safety to de-energize the heater in the event the heater is overheated. However, especially when producing thermistors for low heat capacity heaters, it is difficult to mass produce and accurately calibrate such thermistors, resulting in increased inefficiency and greater waste potential. The present invention aims to solve or at least partially obviate one or more of the above problems. Disclosure of Invention The invention is set forth in the appended independent claims. Optional features are set out in the appended dependent claims. In the following, any examples and embodiments that do not fall within the scope of the claims do not form part of the invention and are provided for illustrative purposes only. According to a first aspect there is provided a hair drying and/or styling apparatus comprising a heater for providing heat for drying and/or styling hair, the heater having a heating rate of greater than 30 ℃ per second, a power supply for providing power to the heater, and safety circuitry for disconnecting the power supply from the heater in response to a overheat triggering event or a fault detection event, wherein the safety circuitry is configured to disconnect the power supply from the heater assembly within a period of between 0.02 seconds and 2 seconds of the overheat triggering event or the fault detection event. Preferably, the safety circuitry is configured to disconnect the power supply from the heater assembly for a period of between 0.02 seconds and 1 second of a overheat triggering event or a fault detection event, more preferably for a period of between 0.025 seconds and 1 second, and even more preferably for a period of between 0.05 seconds and 0.6 seconds. This period of time typically depends on the heating rate and the temperature difference between the trigger temperature and the maximum allowable temperature, as well as any additional latency associated with activating the trigger. In some embodiments, the heater may comprise independently operable heater zones, and preferably each heater zone may comprise at least one independently operable heater electrode. The heater may be a heater assembly (and these terms may be used interchangeably). The safety circuitry may be configured to de-energize the heater in dependence upon detection of the overheat trigger event or the fault detection event in any one (or more) of the heater zones, preferably to disconnect power to all heater electrodes in dependence upon detection of the overheat trigger event or the fault detection event in any one (or more) of the heate