EP4346499A1

EP4346499A1 - Hair styling apparatus, temperature control systems, and methods for controlling hair styling apparatus

Info

Publication number: EP4346499A1
Application number: EP22811884.0A
Authority: EP
Inventors: Dave William EVERETT, JR; Benjamin Miles CLEPPE; Jay William KUZIA; Michael John Degrood
Original assignee: Spectrum Brands Inc
Current assignee: Spectrum Brands Inc
Priority date: 2021-05-25
Filing date: 2022-05-19
Publication date: 2024-04-10
Also published as: WO2022251044A1

Abstract

A hair styling apparatus includes a heating assembly that is configured to deliver heat to hair. The hair styling apparatus is configured to energize a heating element of the heating assembly to deliver heat to the hair during a first styling operation. In one embodiment, the hair styling apparatus is configured to determine an estimated hair temperature, compare the estimated hair temperature to a desired hair temperature profile, and energize the heating assembly during a second styling operation based on the comparison. In another embodiment, the hair styling apparatus determines a curl profile of the hair based on a temperature of the heating assembly or the hair. The hair styling apparatus is configured to compare the curl profile to a desired curl profile, and energize the heating assembly during a second styling operation based on the comparison.

Description

HAIR STYLING APPARATUS, TEMPERATURE CONTROL SYSTEMS, AND METHODS FOR CONTROLLING HAIR STYLING APPARATUS

CROSS-REFERENCE TO RELATED APPLICATIONS

[ 0001 ] This application claims priority to U. S .

Provisional Patent Application No . 63/192959, filed on May 25,

2021 and titled "HAIR STRAIGHTENER AND TEMPERATURE CONTROL

SYSTEM FOR HAIR STRAIGHTENER", and U. S . Provisional Patent

Application No . 63/192963, filed on May 25, 2021 and titled

"HAIR CURLER, TEMPERATURE CONTROL SYSTEM, AND METHOD FOR

CONTROLLING HAIR CURLER", the disclosures of each of which are hereby incorporated by reference in their entirety.

BACKGROUND

[ 0002 ] The present disclosure relates generally to hair styling apparatus and, more particularly, to a hair straightener and a hair curler, and a temperature control system for a hair straightener and a hair curler

[ 0003 ] Many conventional hair styling apparatus include one or more heating elements and a control system for supplying electrical current to the heating elements . For example, a hair straightener generally includes first and second arms having one or more heat plates energized by one or more heating elements .

Other hair styling apparatus such as a hair curler may include one or more heat plates energized by one or more heating elements . [0004] It is often desirable for a hair styling apparatus to provide a consistent styling operation each time the hair styling apparatus is used. However, each person's hair has unique characteristics such as thickness, moisture content, and color that may affect performance of the hair styling apparatus during a hair styling operation. In addition, a user's manner of operating the hair styling such as a movement speed of the hair styling apparatus or how long the user maintains the hair styling apparatus in contact with the hair may affect performance of the hair styling apparatus. As a result, the temperature of the heat plates or heat assemblies may vary significantly during a hair styling operation and the hair styling apparatus may provide very different hair styling experiences based on operating parameters and hair characteristics.

[0005] Some hair styling apparatus include temperature control systems that regulate temperature of the heating assemblies based on a target temperature. The target temperature may be selected to provide a desired styling effect to hair and/or prevent damage to the hair during a styling operation. However, the temperature control systems may be slow to attain the desired temperature, may overshoot the desired temperature, and/or may not maintain the temperature of the heating assemblies within a precise range of the target temperature during styling operations. As a result, the hair styling apparatus may not provide the desired styling effect and/or hair may be damaged during a styling operation. [0006] There is a need, therefore, for a control system for a hair styling apparatus that provides customized control of the heating assemblies based on the characteristics of the hair being styled and the user's manner of operating the hair styling apparatus. In addition, there is a need for a temperature control system that more quickly attains and more effectively maintains a target temperature during a hair styling operation.

SUMMARY

[0007] In one embodiment, a hair straightener generally comprises first and second arms, a heating assembly, at least one sensor, and a controller. The arms are pivotably coupled to each other for selective, pivotal movement relative to each other to selectively configure the hair straightener between an opened position and a closed position. The hair straightener is arranged to receive hair between the first and second arms. The heating assembly is attached to at least one of the first and second arms and configured to deliver heat to the hair clamped between the first and second arms. The heating assembly includes a heating element. The sensor is configured to detect at least one temperature of the heating assembly. The controller is in communication with the sensor and is configured to energize the heating element in accordance with a first temperature set point to deliver heat to hair during a first hair styling operation. The controller is also configured to determine an estimated hair temperature of the hair received between the first and second arms based on the at least one temperature. The controller is further configured to compare the estimated hair temperature and a desired hair temperature profile and determine a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile. The controller is configured to energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

[0008] In another embodiment, a temperature control system for a hair styling apparatus generally comprises a memory and a processor communicatively coupled to the memory. The hair styling apparatus has a heating assembly configured to deliver heat to hair. The memory is configured to store a first temperature set point and temperatures of the heating assembly received from a sensor. The processor is configured to retrieve from the memory the first temperature set point and at least one temperature received from the sensor, energize a heating element of the heating assembly in accordance with the first temperature set point to deliver heat to hair during a first hair styling operation, determine an estimated hair temperature of the hair based on the at least one temperature received from the sensor, compare the estimated hair temperature and a desired hair temperature profile, and determine a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile. The processor is also configured to energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

[0009] In another embodiment, a method for controlling a hair styling apparatus including a heating assembly includes energizing a heating element of the heating assembly in accordance with a first temperature set point to deliver heat to hair during a first hair styling operation. The method also includes receiving, at a controller, a signal relating to a temperature of the heating assembly during the first hair styling operation. The method includes determining, at the controller, an estimated hair temperature during the first hair styling operation based on the temperature of the heating assembly. The method further includes comparing the estimated hair temperature and a desired hair temperature profile and determining, at the controller, a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile. The method also includes energizing the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation

[0010] In another embodiment, a hair curler generally comprises a handle, a body, a heating assembly, a sensor, and a controller. The body is attached to the handle and has a hair contact surface. The hair curler is arranged for hair to be positioned on the body. The heating assembly is housed within the body in thermally conductive relationship with the hair contact surface to deliver heat to the hair positioned on the body. The heating assembly includes a heating element. The sensor is positioned to detect a temperature of the heating assembly or the hair. The controller is in communication with the sensor and is programmed to energize the heating element in accordance with a first temperature set point of the heating assembly to deliver heat to hair during a first hair styling operation. The controller is also programmed to determine a curl profile of the hair based on the temperature of the heating assembly or the hair. The curl profile includes at least one of a curl temperature and a curl time for the first hair styling operation. The controller is programmed to compare the curl profile to a desired curl profile. The desired curl profile includes at least one of a desired curl temperature for comparison to the curl temperature and a desired curl time for comparison to the curl time. The controller is further programmed to determine a second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile, and energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

[0011] In another embodiment, a temperature control system for a hair curler generally comprises a memory and a processor communicatively coupled to the memory. The memory is configured to store a temperature of the heating assembly or the hair. The processor is programmed to energize a heating element of the heating assembly in accordance with a first temperature set point of the heating assembly to deliver heat to hair during a first hair styling operation, retrieve from the memory the temperature of the heating assembly or the hair, and determine a curl profile of the hair based on the temperature of the heating assembly or the hair. The curl profile includes at least one of a curl temperature and a curl time for the first hair styling operation. The processor is programmed to compare the curl profile to a desired curl profile. The desired curl profile includes at least one of a desired curl temperature for comparison to the curl temperature and a desired curl time for comparison to the curl time. The processor is programmed to determine a second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile, and energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

[0012] In another embodiment, a method for controlling a hair curler including a body and a heating assembly includes energizing a heating element of the heating assembly in accordance with a first temperature set point of the heating assembly to deliver heat to hair positioned on the body during a first hair styling operation. The method also includes receiving, at a controller, a signal relating to a temperature of the heating assembly or the hair and determining, at the controller, a curl profile of the hair. The curl profile includes at least one of a curl temperature and a curl time for the first hair styling operation. The method further includes comparing the curl profile to a desired curl profile. The desired curl profile includes at least one of a desired curl temperature for comparison to the curl temperature and a desired curl time for comparison to the curl time. The method also includes determining, at the controller, a second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile, and energizing the heating element in accordance with the second temperature set point to deliver heat to hair positioned on the body during a second hair styling operation.

BRIEF DESCRIPTION

[0013] Figure 1 is a perspective view of an embodiment of a hair straightener in an open position;

[0014] Figure 2 is a perspective view of the hair straightener of Figure 1 in a closed position;

[0015] Figure 3 is a top view of the hair straightener of Figure 1;

[0016] Figure 4 is a bottom view of the hair straightener of Figure 1;

[0017] Figure 5 is a right side view of the hair straightener of Figure 1, illustrating a user interface of the hair straightener;

[0018] Figure 6 is a left side view of the hair straightener of Figure 1;

[0019] Figure 7 is a front view of the hair straightener of Figure 1;

[0020] Figure 8 is a perspective view of a first arm of the hair straightener of Figure 1;

[0021] Figure 9 is a perspective view of a second arm of the hair straightener of Figure 1; [0022] Figure 10 is a sectional view of the hair straightener of Figure 1, taken along line 10-10 shown in Figure

3;

[0023] Figure 11 is a sectional view of the hair straightener of Figure 1, taken along line 11-11 shown in Figure

3;

[0024] Figure 12 is a partially schematic side view of the straighter of Figure 1 being used in a styling operation to style hair received between arms of the straightener;

[0025] Figure 13 is a schematic block diagram of a temperature control system for operating the straightener of Figure 1;

[0026] Figure 14 is a flow chart illustrating an embodiment of a method for controlling the straightener of Figure 1;

[0027] Figure 15 is a chart illustrating average temperatures of the straightener of Fig. 1;

[0028] Figure 16 is a chart illustrating operation of a temperature control system during styling operations;

[0029] Figure 17 is an enlarged perspective view of a portion of an embodiment of a straightener, the straightener including a first sensor coupled to a top of a heating assembly and second sensors mounted to heating surfaces of the heating assembly; [0030] Figure 18 is an enlarged perspective view of a portion of an embodiment of a straightener, the straightener including a first sensor housed within a heating assembly and second sensors mounted along edges a heating surface of the heating assembly.

[0031] Figure 19 is a perspective view of an embodiment of a hair curler;

[0032] Figure 20 is a top view of the hair curler of Figure 19;

[0033] Figure 21 is a bottom view of the hair curler of Figure 19;

[0034] Figure 22 is a right side view of the hair curler of Figure 19, illustrating a user interface of the hair curler;

[0035] Figure 23 is a left side view of the hair curler of Figure 19;

[0036] Figure 24 is a front view of the hair curler of Figure 19;

[0037] Figure 25 is a sectional view of the hair curler of Figure 19, taken along line 25-25 shown in Figure 20;

[0038] Figure 26 is a sectional view of the hair curler of Figure 19, taken along line 26-26 shown in Figure 20;

[0039] Figure 27 is a schematic block diagram of a temperature control system for operating the hair curler of Figure 19; [0040] Figure 28 is a flow chart illustrating an embodiment of a method for controlling the hair curler of Figure 19 based on a desired hair temperature;

[0041] Figure 29 is a flow chart illustrating an embodiment of a method for controlling the hair curler of Figure 19 based on a desired curl time;

[0042] Figure 30 is a perspective view of the hair curler of Figure 19 being using in a styling operation to style hair positioned on a body of the hair curler;

[0043] Figure 31 is a chart illustrating operation of a temperature control system during styling operations;

[0044] Figure 32 is a flow chart illustrating an embodiment of a method for controlling the hair curler of Figure 19;

[0045] Figure 33 is a perspective view of an embodiment of a hair styling apparatus, the hair styling apparatus including a clamp; and

[0046] Figure 34 is a perspective view of an embodiment of a hair styling apparatus, the hair styling apparatus including positionable arms.

[0047] Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0048] Referring now to the drawings, and in particular to Figs. 1-2, a heated hair styling appliance according to one embodiment is illustrated in the form of a hair straightener and is indicated generally by the reference numeral 100. Some aspects of the embodiments described herein may also be useful on other hair styling appliances such as, for example, hair curling irons, hair dryers, heated hair combs, etc.

[0049] The illustrated hair straightener 100 comprises a pair of arms (namely, a first arm 102 and a second arm 104) that are hingedly connected together for pivoting movement relative to each other between an opened position (Fig. 1) and a closed position (Fig. 2). When in the closed position, the first and second arms 102, 104 collectively define a handle 106 for a user to grasp and manipulate the straightener 100.

[0050] Referring to Figs. 3-11, each of the first and second arms 102, 104 includes a heating assembly 108 comprising a hair contact plate 110 having a contact surface 112 for contacting hair and a heating element 114 housed within the arm in thermally conductive relationship with the contact plate 110 for heating the contact plate 110. In the example, the heating elements 114 comprise positive temperature coefficient (PTC) thermistors. The PTC thermistors have a resistance that increases as the temperature increases. As a result, the heating elements 114 have a current draw that is inversely related to temperature (i.e., the current draw decreases as the temperature increases) and provide a quick heating time at lower temperatures and provide more stable temperature behavior at higher temperatures. Also, the heating elements 114 are relatively inexpensive and reliable. In other embodiments, the heating assemblies 108 may include any suitable heating elements 114.

[0051] The straightener 100 is configured to deliver heat to the hair and style (e.g., straighten or curl) the hair during a hair styling operation. As described in more detail herein, the straightener 100 is configured to account for unique characteristics of the user and/or the hair to provide a customized styling operation. For example, the straightener 100 delivers heat to the hair to heat the hair to a precise temperature based on an operating parameter of the straightener 100 and/or characteristic of the hair.

[0052] The heating element 114 of each arm 102, 104 is suitably connected to the power supply of the straightener 100 such that, during operation of the straightener 100, electrical current is supplied to the heating element 114 to heat the contact plate 110. For example, in the illustrated embodiment, the hair straightener 100 includes a cord 116 that is connectable to an external power source. In some embodiments, the straightener 100 may include a battery and/or any other suitable power source.

[0053] As shown in Figs. 5 and 6, the straightener 100 includes a first end 120 and a second end 122. The arms 102,

104 extend along a longitudinal axis 124 from the first end 120 to the second end 122 when the straightener 100 is in the closed position. In the illustrated embodiment, the cord 116 extends outward from the first end 120 of the straightener 100. In addition, the arms 102, 104 are hingedly connected together at the first end 120 by a hinge 126. For example, the arms 102,

104 may be pivoted about the hinge 126 to allow hair to be positioned between the arms 102, 104. The illustrated hinge 126 includes a bias mechanism (e.g., a spring 138 shown in Fig. 9) to bias the straightener 100 towards the open position or the closed position.

[0054] The straightener 100 may include a sensor (not shown) to detect when the straightener 100 is moved between the open and closed positions. For example, the sensor may comprise a Hall-effect sensor that provides a signal when the first and second arms 102, 104 are moved relative to each other.

[0055] The illustrated straightener 100 includes a lock 128 configured to lock the straightener 100 in the closed position and/or the open position. For example, the lock 128 may secure the straightener 100 in the closed position to facilitate a user holding the straightener 100 tightly on the hair received between the arms 102, 104 during a styling operation. In some embodiments, the lock 128 may comprise a slide that moves along the longitudinal axis 124 of the straightener 100 and selectively prevents pivoting movement of the first and second arms 102, 104 relative to each other. In other embodiments, the lock 128 may include a hook, a latch, or any other suitable lock mechanism.

[0056] Fig. 8 is a perspective view of the first arm 102 of the hair straightener 100. The first arm 102 includes a first arm housing 130 that encloses a portion of the heating assembly 108 (shown in Fig. 11) of the first arm 102. The hair contact plate 110 of the heating assembly 108 extends through an opening in the housing 130 and along a portion of the extension of the first arm 102 between the first end 120 and the second end 122 of the straightener 100. In the illustrated embodiment, the hair contact plate 110 is planar. The hair contact plate 110 is arranged to contact and deliver heat to hair received between the first and second arms 102, 104.

[0057] The first arm 102 includes a user interface 132 disposed on the housing 130 between the hair contact plate 110 and the first end 120. In the illustrated embodiment, the user interface 132 includes buttons 133 to allow the user to change operating settings of the straightener 100 (e.g., to change modes of the straightener 100). In some embodiments, the user interface 132 includes a display, a touchscreen, and/or any other input/output devices. The user interface 132 of the illustrated embodiment is disposed on a surface of the housing 130 that faces the second arm 104 and orientated at an angle relative to the hair contact plate 110. Accordingly, the user interface 132 may be easier for a user to operate while the user grasps the handle 106 of the straightener 100. In other embodiments, the user interface 132 may be at a different location on the hair straightener 100.

[0058] The first arm 102 includes at least a portion of the hinge 126 that pivotably attaches the second arm 104 to the first arm 102. For example, the first arm housing 130 of the first arm 102 includes a hinge bracket 135 that defines openings 137 for pivotably attaching the second arm 104 to the first arm 102. [0059] Fig. 9 is a perspective view of the second arm 104 of the hair straightener 100. The second arm 104 includes a second arm housing 134 that encloses a portion of the heating assembly 108 (shown in Fig. 11) of the second arm 104. The hair contact plate 110 of the heating assembly 108 extends through an opening in the housing 134 and along a portion of the extension of the second arm 104 between the first end 120 and the second end 122 of the straightener 100. The hair contact plate 110 of the second arm 104 is planar and extends parallel to the hair contact plate 110 of the first arm 102 when the straightener 100 is in the closed position. The hair contact plate 110 of the second arm 104 is arranged to contact and deliver heat to hair received between the first and second arms 102, 104.

[0060] The second arm 104 includes at least a portion of the hinge 126 that pivotably attaches the second arm 104 to the first arm 102. For example, the housing 134 of the second arm 104 includes pins 136 that are received in the openings 137 in the housing 130 of the first arm 102 to form the hinge 126 and pivotably attach the first and second arms 102, 104 together.

In addition, the straightener 100 includes a spring 138 located between the first arm 102 and the second arm 104 and arranged to bias the straightener 100 toward the opened position.

[0061] Referring now to Figs. 10 and 11, the heating assemblies 108 are mounted to and at least partially housed within the housings 130, 134. The heating assembly 108 associated with one or both of the arms 102, 104 includes a temperature sensor 140, 142 for gauging the temperature of the respective heating assembly 108. For example, in one embodiment, the temperature sensor 140, 142 may be used to gauge the temperature of each respective heating element 114 and provide temperature readings to a temperature control system.

The temperature readings may be adjusted to estimate the temperature of the contact plates 110 to account for the temperature of the contact plates 110 and more particularly the contact surfaces 112 of the contact plates typically being lower than the temperature of the heating elements 114. In the example, the temperature sensor 140 is used for determining the temperature of the contact plates 110 relative to a set point and the temperature sensor 142 is used for determining an estimated temperature of the hair. In accordance with one suitable embodiment, the heating assemblies 108 are controlled together (e.g., to operate at the substantially the same temperature).

[0062] At least one of the temperature sensors 140, 142 may comprise a negative temperature coefficient (NTC) thermistor and/or a positive temperature coefficient (PTC) thermistor. Any suitable temperature sensor may be used in addition to or instead of a thermistor without departing from the scope of this disclosure. For example, in some embodiments, the temperature sensors 140, 142 may comprises a NTC thermistor, a PTC thermistor, a resistance temperature detector (RTD), and/or a thermocouple.

[0063] In the illustrated embodiment, the second arm 104 includes a first temperature sensor 140 disposed within the housing 134 and mounted to the heating element 114 of the second arm 104. The first temperature sensor 140 is a NTC thermistor and is arranged to measure the temperature of the heating element 114. For example, the first temperature sensor 140 is positioned and constructed to quickly conduct thermal energy generated by or removed from the heating element 114 and provide a quick response time to temperature changes of the heating element 114. The first arm 102 includes a second temperature sensor 142 mounted to and extending along the hair contact plate 110. The second temperature sensor 142 is a NTC thermistor and is arranged to measure the temperature of the hair contact plate 110 and/or hair on the hair contact plate 110. For example, the second temperature sensor 142 includes a sensor strip that conducts thermal energy from the hair contacting the hair contact plate to the NTC thermistor. In the example, the second temperature sensor 142 is thermally isolated from the hair contact plate 110 and the heating element 114. The NTC thermistors of the first and second temperature sensors 140, 142 are less expensive and are simpler to operate than other temperature sensors. For example, a temperature of the NTC thermistors can be determined using a voltage divider.

[0064] A control system 144 is carried by the straightener 100 and is operatively connected to each temperature sensor 140, 142. In one embodiment, the control system 144 comprises an analog-to-digital converter (ADC) 146, a processor 148, and a memory 150 for storing instructions to be executed by the processor 148. Alternatively, the control system 144 may include any suitable processing device or combination of processing devices. The control system 144 is configured to operate the straightener 100 by controlling each heating assembly 108 during operation of the straightener 100, as described in detail herein.

[0065] Fig. 12 illustrates the straightener 100 being used for a styling operation for hair 152. The hair 152 has a length 154 measured from a proximal end 156 to a distal end 158 of the hair 152. The straightener 100 is configured to clamp the hair 152 between the arms 102, 104 such that the hair 152 extends across the hair contact plates 110 in a direction substantially perpendicular to the longitudinal axis 124 (shown in Fig. 1). The heating assemblies 108 are configured to deliver heat to the hair 152 positioned between the arms 102, 104. The straightener 100 is configured to be moved along the length 154 of the hair 152 or a portion thereof during a styling operation. As used herein, the term "styling operation" refers to heating a section of hair to provide a desired style effect to the section of hair. The illustrated straightener 100 delivers heat to the hair 152 and styles the hair 152 as the straightener 100 is moved along the length of the hair 152. For example, the straightener 100 is configured to straighten the hair 152. In some embodiments, the straightener 100 may be configured to perform other styling operations such as curling the hair 152. For example, in some embodiments, at least one of the arms 102, 104 may be shaped (e.g., curved) to allow for a curling operation. In some embodiments, the straightener 100 may include multiple heating zones, a cooling zone, and/or any other feature which allows the straightener 100 to straightener, curl, or otherwise style the hair in a desired manner. [0066] During operation, the straightener 100 is activated and the heating assemblies 108 are energized to heat up the hair contact plates 110. The straightener 100 is clamped onto the hair 152 such that the first and second arms 102, 104 sandwich the hair 152 therebetween. Heat is delivered to the hair 152 via the hair contact plates 110 during a styling operation. The straightener 100 may be clamped onto the hair at or near the proximal end 156 of the hair 152. The straightener 100 is moved along the length of the hair 152 toward the distal end 158. When the straightener 100 is at or near the distal end 158 of the hair 152, the straightener 100 may be opened and the hair 152 released. Alternatively the straightener 100 may be moved past the distal end 158 such that the straightener 100 slides off of the hair 152. The user may then gather another section of the hair 152 for another styling operation.

[0067] In some embodiments, the temperature of the hair contact plate 110 initially decreases as the hair 152 is positioned between the arms 102, 104 of the straightener 100 and the hair styling operation is started. The decrease in temperature is likely because the hair 152 removes heat from the hair contact plate 110 and the straightener 100 has a lag until the heating assembly can catch up to the temperature being transferred to the hair. The temperature of the hair contact plate 110 and the estimated temperature of the hair increases as the straightener 100 approaches the distal end 158 of the hair 152 because the temperature control system energizes the heating elements 114 to accommodate the heat transfer to the hair 152 during the styling operation. [0068] The straightener 100 may adjust a temperature set point of the heating assemblies 108 during operation of the straightener 100. For example, as described in detail herein, the straightener 100 may use proportional-integral-derivative (PID) methodology and predictive learning to more accurately and effectively adjust the average temperature of the hair contact plate 110.

[0069] The temperature profile of a styling operation may vary based on the speed at which the straightener 100 is moved through the hair. The different movement speeds of the styling apparatus provided by the user generates different temperature profiles of the hair and can provide different styling effects on the hair. For example, a styling operation in which a user moves the straightener 100 along the hair at a slower speed will provide an average temperature that is higher than an average temperature of a styling operation in which the user moves the straightener 100 along the hair at a faster speed.

[0070] The temperature profile of a styling operation may vary based on the amount of hair that is positioned between the arms 102, 104 of the straightener 100. The different amounts of hair positioned between the arms of the straightener 100 generate different temperature profiles during the styling operation and can provide different styling effects on the hair. For example, a temperature profile of a styling operation when a first section of hair is positioned in the straightener 100 has an average temperature that is lower than an average temperature of a temperature profile of a styling operation when a second section of hair that has less mass or a smaller cross-section than the first section of hair is positioned in the straightener 100 because the smaller amount of hair provides a lower heat load for the straightener 100.

[0071] With reference now to Fig. 13, a temperature control system that may be used with the straightener 100 is indicated generally at 300. The temperature control system 300 includes an integrated controller 302 that may be implemented, for example, using the control system 144 (shown in Fig. 10).

[0072] When used with the hair straightener 100 having hinged arms 102, 104 (shown in FIG. 1), the integrated controller 302 may be communicatively coupled to a monitoring device 304. The monitoring device 304 is operable to assess whether the straightener 100 is in a closed position (i.e., with the arms 102 and 104 and more particularly the contact plates 110 proximate one another and in some instances substantially contacting one another) or in an open position (i.e., with the arms 102 and 104 substantially spaced apart from one another). For example, the straightener 100 is shown in a partially opened position in Fig. 1 and a closed position in Fig. 2.

[0073] The monitoring device 304 may be any device (e.g., an electro-mechanical monitoring device) capable of monitoring whether the straightener 100 is in the closed position or in the open position. For example, the monitoring device 304 in accordance with one embodiment comprises a) a Hall effect sensor 303 (shown in FIG. 10) in one arm (e.g., the first arm 102) and b) a corresponding magnet 305 (shown in FIG. 10) disposed in the other arm (e.g., the second arm 104). In one particularly suitable embodiment, the sensor and corresponding magnet are located approximately midway along each respective arm 102, 104 (e.g., between the hinge and the respective heating assembly 108). In other embodiments, a momentary push button type switch may be used to monitor the opened and closed position of the arms 102, 104. Other suitable monitoring devices may be used to monitor the open and closed position of the arms 102, 104 without departing from the scope of this disclosure.

[0074] In addition, the control system 300 includes a sensing device 306 communicatively coupled to the integrated controller 302 and configured to detect one or more of an operating parameter of the hair straightener or a characteristic of the hair. For example, the sensing device 306 includes the temperature sensors 140, 142 mounted to the heating assemblies 108 of the first and second arms 102, 104, as illustrated in Fig. 11. In the example embodiment, the sensing device 306 is configured to monitor a temperature of the heating element 114 and/or the hair contact plate 110 of each arm 102, 104.

[0075] Referring to Figs. 10, 11, and 13, when used with the hair straightener 100, the integrated controller 302 controls a temperature of the heating elements 114 of the heating assemblies 108 to deliver heat to the hair received between the first and second arms 102, 104. In particular, the integrated controller 302 controls the temperature of the heating elements 114 by regulating electrical current to the heating elements 114 based on a temperature set point. The temperature set point may be determined based on at least one of an operating parameter of the hair straightener 100 or a characteristic of the hair. Accordingly, the integrated controller 302 facilitates operating the straightener 100 in a manner that is customized for the user and/or the hair being styled. As a result, the straightener 100 may provide an improved styling experience for individuals in comparison to apparatus that do not account for an individual's manner of operating the apparatus or hair characteristics.

[0076] For example, the integrated controller 302 receives information including at least one operating parameter of the straightener 100 and/or a characteristic of the hair from the sensing device 306 and/or the monitoring device 304. Operating parameters of the straightener 100 include, for example and without limitation, movement speed of the straightener 100, amount of hair styled during a single styling operation, temperature of the heating assemblies 108, an inferred or estimated temperature of the hair, and a position of the arms 102, 104. Characteristics of the hair include, for example and without limitation, temperature, thickness, moisture content, and color. In the example embodiment, the integrated controller 302 receives a signal from the monitoring device 304 indicating the position of the straightener 100, a signal from the sensor 140 indicating the temperature of the heating element 114, and a signal from the sensor 142 indicating the temperature at the hair contact surface 112. Based on the received signals, a hair temperature prediction system 307 of the integrated controller 302 determines a predicted temperature profile of the hair positioned between the first and second arms 102, 104 during a styling operation. [0077] The hair temperature prediction system 307 provides the predicted temperature profile to an artificial intelligence ("AI") system 308 which determines a temperature set point based on the predicted temperature profile and/or information from the sensing device 306. The AI system 308 may utilize machine learning in which the AI system learns from multiple iterations to better predict and regulate operating parameters of the straightener 100. For example, the AI system 308 may incrementally adjust a temperature set point based on information from successive styling operations or passes through a user's hair until the temperature profile of the user's hair resembles a desired temperature profile.

[0078] The AI system 308 provides the determined temperature set point to a temperature regulation module 310.

The temperature regulation module 310 regulates the heating assemblies 108 of the first and second arms 102, 104 based on the determined temperature set point received from the AI system 308. The temperature set point and operation of the temperature regulation module 310 may be adjusted for each pass along the hair until a desired temperature profile is met. One or more of the temperature set points may be stored in the memory and retrieved by the temperature regulation module 310 when the straightener 100 is powered on, when a mode of the straightener 100 is selected, and/or when a new hair styling operation begins. In some embodiments, the temperature regulation module 310 may comprise a proportional-integral-derivative controller (PID controller), PI controller, and/or a P controller which determines and corrects errors between the determined temperature profile and the desired temperature profile in a continuous feedback loop.

[0079] The monitoring device 304 is communicatively coupled to The AI system 308 and the temperature regulation module 310. The integrated controller 302 may identify the start of a first styling operation (e.g., a pass along a length of hair) when the monitoring device 304 indicates that the straightener 100 is closed. The integrated controller 302 may identify the end of the first styling operation when the monitoring device 304 indicates that the straightener 100 is opened. The integrated controller 302 may identify additional styling operations based on subsequent opening and closing cycles of the straightener 100.

[0080] In some embodiments, the temperature regulation module 310 operates the straightener 100 in accordance with an opened protocol or a closed protocol. The temperature regulation module 310 determines to use the opened protocol or the closed protocol based on an indication from the monitoring device 304. For example, the straightener 100 accounts for the effect of increased thermal losses to the information if the monitoring device 304 indicates that the straightener 100 is in the opened position.

[0081] Also, the AI system 308 determines the amount of time that the straightener 100 is in the closed position and/or other operation manners of the user based on the information from the monitoring device 304. The AI system 308 disregards styling operations that are outside of predetermined parameters such as the amount of time that the straightener 100 is in the closed position.

[0082] Fig. 14 is a flow chart illustrating an embodiment of a method 400 for controlling the straightener 100. With reference to Figs. 1, 13, and 14, the method 400 may be implemented, for example by the integrated controller 302, to operate the straightener 100 during styling operations. In some embodiments, the straightener 100 includes different modes of operation that are selectable by a user. For example, the user may select a manual mode in which the temperature regulation module 310 operates in accordance with one or more fixed temperature set points to maintain the temperature of the heating assemblies 108 at the user selected value and/or within a range of temperature values. The straightener 100 may also include a style adapt mode in which the straightener 100 adjusts operation of the straightener 100, using the AI system 308, based on an operating parameter and/or hair characteristics to provide a customized styling operation for the user. In the example, the straightener 100 includes two or more style adapt modes which allow multiple users to utilize the styling device and each have their own style adapt mode that is customized to their styling performance and/or for a single user to utilize different style adapt modes for different styling operations.

In some embodiments, the straightener 100 includes profiles or modes for multiples users, different style uses or techniques, different hair properties (e.g., wet and dry profiles), higher styling performance during operation, and/or hair protection or health. [0083] In the method 400, the user initiates 402 the style adapt mode. For example, the user may select, using the user interface 132, the style adapt mode from a menu of options. In some embodiments, the straightener 100 automatically initiates the style adapt mode when the straightener 100 is powered on. In embodiments that default to the style adapt mode, the user may make a selection to switch the straightener 100 out of the style adapt mode.

[0084] The straightener 100 may be simpler to use than other styling apparatus that require the user to make multiple selections and/or input information into the straightener 100 for a styling operation. For example, the user may simply turn on the straightener 100 and the straightener 100 automatically adjusts during styling operations based on the operating parameters and/or hair characteristics to provide a customized styling operation without the user having to select or input operating parameters and/or characteristics.

[0085] In the method 400, the temperature regulation module 310 commences 404 a temperature control algorithm and regulates electrical current to the heating assemblies 108 to energize the heating elements 114. For example, the temperature regulation module 310 may regulate the temperature of the heating assemblies 108 based on feedback from sensors and a duty cycle. In particular, the integrated controller 302 may receive temperature readings from NTC sensors, such as sensors 140, 142. The integrated controller 302 monitors the temperature of the heating assemblies 108 and determines 408 if the heating assemblies 108 are preheated (i.e., the temperature of the hair contact surface 112 is above a threshold value). The integrated controller 302 monitors the temperatures (e.g., receives reading of the temperatures continuously or periodically) of the heating assemblies 108 until the heating assemblies 108 reach the threshold value. The straightener 100 may alert 410 the user if the straightener 100 is preheated. The alert may comprise a light, a display message, an audible indication, a vibratory indication, and/or any other suitable indication.

[0086] After determining 408 that the straightener 100 is preheated, the integrated controller 302 determines 412 if hair has been positioned between the first and second arms 102, 104 to start a styling operation. For example, the integrated controller 302 may identify a start of a hair styling operation when the integrated controller 302 receives a signal from the monitoring device 304 that the first and second arms 102, 104 are moved relative to each other to switch the straightener 100 from the open position to the closed position. The integrated controller 302 may identify that the hair styling operation has stopped when the integrated controller 302 receives a signal from the monitoring device 304 that the first and second arms 102, 104 are moved relative to each other to switch the straightener 100 from the closed position to the open position.

[0087] The integrated controller 302 may collect and evaluate temperature readings received when the straightener 100 is in the closed position. For example, the integrated controller 302 may receive at least four temperature readings per second. In other embodiments, the integrated controller 302 may receive any number of temperature readings per second that permits the integrated controller 302 to control the straightener 100 as described herein, including more or fewer than four temperature readings per second. In some embodiments, the integrated controller 302 may account for a delay between when the temperature readings are measured and when the temperature readings are received at the integrated controller 302. For example, the integrated controller 302 may not receive temperature until an amount of time greater than 0 after the straightener 100 is closed or the integrated controller 302 may disregard temperature readings until after the threshold time. Also, to account for the delay, the integrated controller 302 may continue to collect temperature readings for an amount of time greater than 0 after the straightener 100 is opened. For example, the time delay may be at least 0.5 seconds or at least 1 second.

[0088] The integrated controller 302 may determine 414 a surface NTC temperature of the hair contact surface 112 and a rate of change of the surface temperature (e.g., a derivative of the surface NTC temperature) for a styling operation. The surface NTC temperature may be determined based on values from the second sensor 142. The rate of change of the surface temperature may be determined by calculating a derivative of the surface temperatures provided by the monitoring device 304 during a styling operation.

[0089] The hair temperature prediction system 307 of the integrated controller 302 calculates 416 a hair temperature profile for the styling operation. The hair temperature profile may include an estimated average temperature for the hair styling operation, a maximum hair temperature during the styling operation, and/or a minimum hair temperature during the styling operation. The hair temperature prediction system 307 may determine the estimated hair temperature based on values of the temperature of the hair straightener 100 (e.g., the temperature at the hair contact surface 112). For example, the hair temperature prediction system 307 may use equation (1), below, to determine the temperature profile based on a surface temperature of a surface of the heating assembly and a rate of change of the surface temperature.

Where T_hair is the estimated temperature of hair, f(X,Y) is an empirical function, T_surface is the temperature at the hair contact surface, and (dT_surface/dt)_min is the minimum rate of change of the temperature at the hair contact surface.

[0090] For example, the integrated controller 302 determines the time at which the rate of change of the hair contact surface has the largest absolute value and records the temperature, the derivative of the temperature at the hair contact surface, and the time from when the hair styling operation started. The temperature prediction system 307 determines the hair temperature for the styling operation based on the following equation:

Where Thair is the estimated temperature of hair, T_surface is the temperature at the hair contact surface and (dT_surface/dt)min is the rate of change of the temperature at the hair contact surface, and TI is the elapsed time at which the rate of change of the hair contact surface has the largest absolute value.

[0091] In some embodiments, the estimated temperature of the hair is averaged with temperatures from previous styling operations. For example, a total average temperature may be calculated using equation (2).

Where N is the number of styling operations, T_aN is the average temperature for the respective styling operation, and T_{a_total} is the average temperature for N number of styling operations. In some embodiments, the hair temperature prediction system 307 uses the average estimated hair temperature from multiple styling operations as the estimated hair temperature for the hair profile and the AI system 308 compares the average estimated hair temperature to the desired temperature.

[0092] Ihe memory 150 may store the hair temperature profiles for each styling operation. The stored hair temperature profiles may include minimum values, maximum values, and average temperatures. In some embodiments, the memory 150 stores a limited a number of temperature profiles and the integrated controller 302 determines a total average temperature for an estimated hair temperature profile based on a selected number of styling operations. For example, in some embodiments, the total average temperature is determined based on no more than twenty hair styling operations. In further embodiments, the total average temperature is determined based on no more than sixteen hair styling operations. As a result, the integrated controller 302 may be quicker to adapt if operating parameters or hair characteristics change. For example, the straightener 100 may adjust to a new user within a single use of the straightener 100 because a user typically utilizes the straightener 100 for more than sixteen styling operations during a single use.

[0093] The AI system 308 compares 418 the estimated hair temperature to one or more desired hair temperature values. For example, the integrated controller 302 may compare an average temperature of a hair styling operation or a total average temperature of multiple styling operations to a target temperature. In some embodiments, the target temperature may be in a range of about 40° Celsius (C) to about 250° C. In some embodiments, the target temperature may be based at least partially on a user selection.

[0094] The AI system 308 is configured to adjust or maintain a temperature set point based on the comparison of the estimated hair temperature and the desired hair temperature value(s). For example, the desired hair temperature value(s) may include an upper threshold value and a lower threshold value or a single value. The integrated controller 302 is configured to increase 420 the temperature set point of the heating assembly 108 if the integrated controller 302 determines 422 that the estimated hair temperature is less than the lower threshold value. For example, the integrated controller 302 may be configured to increase the temperature set point of the heating assembly 108 by a predetermined gain value multiplied by the difference between the desired hair temperature and the estimated hair temperature. The predetermined gain value is a positive value greater than zero and is multiplied by the actual difference between the measured temperature and the target temperature. The gain value can be increased to provide convergence within less passes or decreased to make the system slower to change and, therefore, more stable. For example, a gain value less than one would provide an adjustment that is less than the actual difference between the target temperature and the measured temperature. A gain value less equal to one would provide an adjustment that is equal to the actual difference between the target temperature and the measured temperature. A gain value greater than one would provide an adjustment that is greater than the actual difference between the target temperature and the measured temperature.

[0095] The integrated controller 302 is configured to maintain 424 the same temperature set point of the heating assembly 108 if the integrated controller 302 determines 426 that the estimated hair temperature is equal to the desired temperature. The integrated controller 302 is configured to decrease 428 the temperature set point of the heating assembly if the integrated controller 302 determines that the temperature profile is greater than the upper threshold value. For example, the integrated controller 302 may be configured to decrease the temperature set point of the heating assembly 108 by a predetermined gain value multiplied by the difference between the estimated hair temperature and the desired hair temperature. In some embodiments, the integrated controller 302 compares the estimated hair temperature to a single desired hair temperature value and increases or decreases the temperature set point based on any differences between the estimated hair temperature and the desired temperature value.

[0096] In some embodiments, the temperature profile 430 includes maximum and minimum temperatures reached during the styling operation. The integrated controller 302 may be configured to adjust the temperature set point based on a comparison of the maximum and minimum temperatures to the desired temperature profile which may include upper and lower limits. In some embodiments, the integrated controller 302 may compare the maximum and minimum temperatures to the upper and lower limits. The integrated controller 302 may use the comparison of the maximum and minimum temperatures and the upper and lower limits to adjust a temperature set point determined from a comparison of the estimated average hair temperature and the desired hair temperature. For example, the integrated controller 302 may compare the minimum temperature to a lower limit (e.g., 140°C) and increase the temperature set point if the minimum temperature is below the lower limit. The integrated controller 302 may compare the maximum temperature to an upper limit (e.g., 220° C) and decrease the temperature set point if the maximum temperature exceeds the upper limit. In some embodiments, the integrated controller 302 is configured to adjust the temperature set point if the maximum or minimum temperature is outside the upper and lower limits even if the average temperature matches the target temperature.

[0097] The integrated controller 302 is configured to operate the heating assemblies 108 in accordance with the determined temperature set point for one or more subsequent hair styling operations. For example, after the temperature set point is determined based on the initial hair styling operation, the method 400 returns to determining 412 if hair has been positioned between the first and second arms 102, 104. The integrated controller 302 identifies the start of a second styling operation when the first and second arms 102, 104 are clamped on a second section of hair. The integrated controller 302 operates in accordance with the second temperature set point for the second styling operation.

[0098] The integrated controller 302 may calculate 416 a second estimated temperature of the hair during the second hair styling operation, compare 418 the second estimated hair temperature profile and the desired hair temperature profile, and determine a second temperature set point of the heating assembly based on the comparison of the second temperature profile and the desired hair temperature.

[0099] The integrated controller 302 is configured to operate the heating assembly in accordance with the determined second temperature set point for a third hair styling operation. For example, the integrated controller 302 energizes the heating element in accordance with the second temperature set point to deliver heat to hair received between the first and second arms 102, 104 during the third hair styling operation. The integrated controller 302 may repeat steps of the method 400 to determine a third temperature set point.

[00100] The integrated controller 302 is configured to repeat steps of the method 400 and determine temperature set points for any number of hair styling operations. Accordingly, the integrated controller 302 is configured to continually adjust operation of the straightener 100 to match and maintain a desired temperature profile. Moreover, one or more of the determined temperature set points may be stored in the memory 150 and retrieved by the integrated controller 302 when the style adapt or other modes are activated. Accordingly, the straightener 100 may utilize the most recent determined temperature set point to provide a customized styling operation even when the straightener 100 powers off or switches modes between styling operations. As a result, the user is not required to select a specific user profile or input characteristics when starting a styling operation.

[00101] In some embodiments, the integrated controller 302 may disregard information from one or more hair styling operations if the temperature profiles for the styling operations are outside of preset parameters. Accordingly, the integrated controller 302 may reduce errors for invalid data points. For example, the integrated controller 302 may disregard a temperature profile from a styling operation that has a duration greater than or less than a range of time values. In some embodiments, the range of time values include preset values stored in the memory 150. In further embodiments, the range of time values are determined by the integrated controller 302 based on the average time for previous styling operations.

[00102] The method 400 provides a continuous feedback loop in which a temperature set point is determined based on each hair styling operation and the straightener 100 provides hair styling operations that are customized for individual operating parameters and/or hair characteristics.

[00103] Fig. 15 includes a chart 500 illustrating average temperatures of the straightener 100 (shown in Fig. 1) and operating parameters of the straightener 100. The chart 500 includes a first curve 502 representing a target temperature of the hair contact plate, a second curve 504 representing a measured temperature of the hair contact plate 110, and a third curve 506 representing a duty cycle of the heating assembly 108. The temperature control system 300 continuously adjusts the duty cycle of the heating assembly 108 during styling operations to cause the second curve 504 to converge with the first curve 502. As used herein, the phrase "duty cycle" refers to a ratio of the time that current is provided to the time that the current is off during a single cycle. The duty cycle at which the electrical current is provided to the heating element 114 may relate to a temperature control set point for the heating assembly 108. The duty cycle is controlled by regulating the alternating current (AC) waves or cycles that are provided to the heating assembly 108. For example, the temperature control system 300 regulates the number of AC cycle that are provided to the heating assembly 108 to correspond to the duty cycle (e.g., the heating assembly 108 receives 10 AC cycles per 100 AC cycles if the duty cycle is 10%). The temperature control system 300 may space the AC current provided to the heating assembly 108 to provide a uniform or even distribution of the AC current. Notably, the temperature control system 300 causes the measured temperature to reach the target temperature more quickly than other systems and maintains the actual temperature within 1° C precision of the target temperature because the temperature control system 300 uses PID, PI, or P control.

[00104] Fig. 16 illustrates operation of the temperature control system 300 (shown in Fig. 13) to control an operating temperature of the straightener 100 (shown in Fig. 1) during multiple styling operations 600, 602, 604, 606, 608, 610, 612, 614, 616, 618. For example, during a first styling operation 600, the integrated controller 302 of the temperature control system 300 operates the straightener 100 in accordance with a first temperature set point 620. The first temperature set point is used to control the heating element 114 and may be determined based on the target temperature for the hair contact plate 110 and/or the hair. For example, the first temperature set point may be calculated for the heating element 114 to provide sufficient heat for the hair contact plate 110 and/or the hair to reach the desired temperature. The first temperature set point may be stored in the memory 150 and be retrieved by the processor 148 when the straightener 100 is powered on. The first temperature set point may be a preset default value or may be determined based on one or more previous styling operations.

[00105] The heating element 114 heats the hair contact plate 110 up to the first temperature set point 620 when the straightener 100 is powered on. The temperature of the hair contact plate 110 may initially decrease when the hair is positioned between the arms 102, 104 of the straightener 100 for the first styling operation 600. The straightener 100 may operate in accordance with the first temperature set point during the first styling operation 600. For example, the straightener 100 may energize the heating elements 114 to increase temperature of the hair contact plate 110 based on the first temperature set point 620. The first styling operation 600 ends when the straightener 100 is opened and the hair is released.

[00106] The temperature of the hair contact plate 110 and/or the estimated hair temperature during the styling operation is compared to a target temperature 622 and the integrated controller 302 may adjust the temperature set point 620 to a second temperature set point 624 based on the comparison. For example, the temperature set point may be increased if the temperature of the hair is less than the target temperature 622. The temperature set point may be decreased if the temperature of the hair is greater than the target temperature. The temperature set point is adjusted by a value determined based on the actual difference between the measured temperature and the target temperature. For example, the AI system 308 (shown in Fig. 13) may use a gain value to incrementally adjust the temperature set point based on a difference between the target temperature and an estimated temperature.

[00107] During a second styling operation 602, the temperature control system 300 operates the straightener 100 in accordance with the second temperature set point 624 that was determined based on the first styling operation 600. As shown in Fig. 16, the second temperature set point 624 is greater than the first temperature set point 620 because the hair temperature during the first styling operation 600 is less than the target temperature 622.

[00108] The temperature of the hair during the second styling operation 602 is compared to the target temperature 622 and the second temperature set point 624 is adjusted to determine a third temperature set point 626 based on the comparison. For example, the third temperature set point 626 is greater than the second temperature set point 624 because the hair temperature during the second styling operation 602 is less than the target temperature 622.

[00109] During the third styling operation 604, the temperature control system 300 operates the straightener in accordance with the third temperature set point 626 that was determined based on the second styling operation 602. The temperature of the hair during the third styling operation 604 is compared to the target temperature 622 and the third temperature set point 626 is adjusted to determine a fourth temperature set point 628 based on the comparison. For example, the fourth temperature set point 628 is greater than the third temperature set point because the measured temperature during the third styling operation 604 is less than the target temperature.

[00110] During the fourth styling operation 606, the temperature control system 300 operates the straightener 100 in accordance with the fourth temperature set point 628 that was determined based on the third styling operation 602. The temperature of the hair during the fourth styling operation 606 is compared to the target temperature 622 and the fourth temperature set point 628 is adjusted to determine a fifth temperature set point 630 based on the comparison. For example, the fifth temperature set point 630 is substantially equal to the fourth temperature set point 628 because the hair temperature during the fourth styling operation is substantially equal to the target temperature 622.

[00111] During the fifth and sixth styling operations 608, 610, the temperature control system 300 operates the straightener 100 in accordance with fifth and sixth temperature set points 630, 632 that are equal to the fourth temperature set point 628 because the hair temperatures during the fourth and fifth styling operations 606, 608 match the target temperature 622.

[00112] The temperature of the hair during the sixth styling operation 610 is different from the target temperature 622 due to a technique or operating parameter change. Accordingly, the sixth temperature set point 632 is adjusted to determine a seventh temperature set point 634. For example, the seventh temperature set point 634 is greater than the sixth temperature set point 632 because the hair temperature during the sixth styling operation 610 is less than the target temperature 622.

[00113] During the seventh styling operation 612, the temperature control system 300 operates the straightener 100 in accordance with the seventh temperature set point 634 that was determined based on the sixth styling operation 610. The temperature of the hair during the seventh styling operation 612 is compared to the target temperature 622 and the seventh temperature set point 634 is adjusted to determine an eighth temperature set point 636 based on the comparison. For example, the eighth temperature set point 636 is greater than the seventh temperature set point 634 because the hair temperature during the seventh styling operation 612 is less than the target temperature 622.

[00114] During the eighth styling operation 614, the temperature control system 300 operates the straightener 100 in accordance with the eighth temperature set point 636 that was determined based on the seventh styling operation 612. The temperature of the hair during the eighth styling operation 614 is compared to the target temperature 622 and the eighth temperature set point 636 is adjusted to determine a ninth temperature set point 638 based on the comparison. For example, the ninth temperature set point 638 is substantially equal to the eighth temperature set point 636 because the hair temperature during the eighth styling operation 614 is substantially equal to the target temperature 622.

[00115] During the ninth and tenth styling operations 616, 618, the temperature control system 300 operates the straightener 100 in accordance with ninth and tenth temperature set points 638, 640 that are equal to the eighth temperature set point 636 because the hair temperatures during the eighth and ninth styling operations 614, 616 match the target temperature 622.

[00116] Referring back to Figs. 1, 12, and 16, during operation of the straightener 100, a user activates the straightener 100 using the user interface 132 and the temperature regulation module 310 energizes the heating elements 114 of the heating assemblies 108 to heat the hair contact plates 110. When the straightener 100 is preheated, the user may position a section of the hair 152 between the arms 102, 104 and start a hair styling operation. The heating assemblies 108 are configured to deliver heat to the hair 152 positioned between the arms 102, 104. The straightener 100 is configured to be moved along the length 154 of the hair 152 or a portion thereof during the styling operation. The illustrated straightener 100 delivers heat to the hair 152 and styles the hair 152 as the straightener 100 is moved along the length of the hair 152. The temperature regulation module 310 energizes the heating element 114 based on a first temperature set point to attempt to attain a desired temperature of the hair. For example, the temperature regulation module 310 regulates a duty cycle of the heating element 114.

[00117] The user may open the straightener 100 when the first hair styling operation is complete. Based on temperature readings from the sensing device 306 during the first styling operation, the hair temperature prediction system 307 determines an estimated hair temperature of the hair 152. For example, the hair temperature prediction system 307 determines the estimated hair temperature based on surface temperatures of the hair contact plate 110 received from the sensor 142 and a rate of change of the surface temperatures. The AI system 308 compares the estimated hair temperature and a desired hair temperature profile and determines a second temperature set point. [00118] After completing the first styling operation, the user may gather another section of the hair 152 for another styling operation and clamp the straightener 100 onto the hair 152. The temperature regulation module 310 energizes the heating element 114 in accordance with the second temperature set point to deliver heat to the hair 152. After the second styling operation is complete, the temperature prediction system

307 determines an estimated hair temperature and the AI system

308 compares the estimated hair temperature and the desired hair temperature profile. The AI system 308 may determine a third temperature set point based on the comparison of the estimated hair temperature and the desired hair temperature profile.

[00119] The straightener 100 may be used to style a third section of hair using the third temperature set point for a third styling operation. The integrated controller 302 automatically adjusts operation of the straightener 100 during successive styling operations to customize operation of the straightener 100 to accommodate unique characteristics of the hair or operating manners of the user. Accordingly, the user is able to use the straightener 100 for customized styling operations without the user having to select or input characteristics or user profile information. Suitably, the user only needs to activate the straightener 100 using the user interface 132 or, in some embodiments with touch or motion sensors, simply grasping and positioning the straightener 100 for use and the straightener 100 automatically provides customized styling operations. [00120] Fig. 17 is an enlarged perspective view of a portion of an embodiment of a straightener 700. The straightener 700 is similar to the straightener 100 except the straightener 700 includes a first sensor 702 coupled to a top of the heating assembly 108 of the second arm 104 and second sensors 704 mounted to the hair contact plates 110 of the heating assemblies 108 of the first and second arms 102, 104.

The first sensor 702 may be used to monitor the temperature of the heating assembly 108. For example, the first sensor 702 is used to measure and regulate to the set temperature of the hair contact plate 110, and the second sensors 704 are used to predict the hair temperature for a pass or styling operation.

The straightener 700 includes two 704 sensors for symmetry and to account for movement of the straightener 700 along the hair in either direction. As a result, the straightener 700 may be simpler to manufacture and provide more direct measurements of the heating assembly 108 than other straighteners because the first sensor 702 is directly mounted to a top of the heating assembly 108. In addition, the heating elements 114 on both heating plates 110 are closer to the contact surfaces 112 to provide faster heating of the contact surfaces 112 because the sensors 704 are positioned along a side of the heating plates 110 instead of in a stacked arrangement.

[00121] The second sensors 704 may be mounted within grooves extending along transversely spaced edges of the hair contact surface 112 of the heating assembly 108. Accordingly, the second sensors 704 may provide accurate measurements of the temperature of the hair contact plates 110 and allow the temperature control system 300 to account for variations on the sides of the hair contact plates 110.

[00122] Fig. 18 is an enlarged perspective view of a portion of an embodiment of a straightener 800. The straightener 800 is similar to the straightener 100 except the straightener 800 includes a first sensor 802 housed within the heating assembly 108 of the second arm 104 and second sensors 804 extending along edges of the hair contact surface 112 of the heating assembly 108 of the first arm 102, 104 and the heating plates 110 include slots 803. For example, the second sensors 804 may be mounted along the hair contact surface 112 using brackets 806. The brackets 806 may be constructed of a metal such as stainless steel or any other suitable material. The first sensor 802 may be used to monitor the temperature of the heating assembly 108. The second sensors 804 may be used to monitor temperatures of the hair contact surface 112. The second sensors 804 provide symmetry for the temperature measurements and allow the straightener 800 to be moved along the hair in either direction.

[00123] The slots 803 are parallel to the second sensors 804 and are positioned to thermally isolate the second sensors 804 from the bulk of the hair contact plate 110. Accordingly, the straightener 800 is able to have a decreased offset between the heating element 114 and the hair contact surface 112.

[00124] Embodiments of hair styling apparatus and temperature control systems for hair styling apparatus described previously with respect to Figs. 1-18 provide customized hair styling operations that are based on individual hair characteristics or a manner of operating the hair styling apparatus. The control systems may control a hair temperature more precisely than prior control systems and provide customized operation because the controls systems utilize operating parameters or characteristics of hair determined from one or more styling operations. Moreover, the control systems may utilize computer learning and/or PID control to adjust operating parameters more quickly and precisely to a desired operating parameter.

[00125] Referring now to the drawings, and in particular to Figs. 19-26, a heated appliance according to another embodiment is illustrated in the form of a hair curler and is indicated generally by the reference numeral 1900. Some aspects of the embodiments described herein may also be useful on other hair styling appliances such as, for example, hair straighteners, hair dryers, heated hair combs, etc.

[00126] The illustrated hair curler 900 comprises a handle 902 and a body 904 extending from the handle 902. The hair curler 900 is configured for hair to be wrapped around the body 904. For example, the body 904 includes a hair contact surface 906 extending along and about a longitudinal axis 908 and arranged to contact hair wrapped around the body 904. In the illustrated embodiment, the body 904 and the hair contact surface 906 are frustoconical. In other embodiments, the body 904 and the hair contact surface 906 may be cylindrical.

[00127] As shown in Figs. 20 and 21, the hair curler 900 includes a first end 910 and a second end 912. The handle 902 and the body 904 extend along the longitudinal axis 908 from the first end 910 to the second end 912. In some embodiments, the hair curler 900 may include a clamp (e.g., clamp 1506 shown in Fig. 33) or one or more positionable arms (e.g., arms 1602, 1604 shown in Fig. 34) for securing hair against the body 904. For example, a clamp may be pivotably connected to the body 904 and be positionable relative to the body 904 to secure hair against the body 904.

[00128] In the illustrated embodiment, the hair curler 900 includes a hair detection sensor 914 to detect when hair is wrapped around the body 904. For example, the hair detection sensor 914 may comprise a contact switch and a gate signal that produces a signal when the hair contacts the contact switch. In the example embodiment, the hair detection sensor 914 is incorporated into the temperature sensor 932 and the presence of hair on the body 904 is determined based on a temperature drop measured by the temperature sensor 932. The hair curler 900 may include other sensors such as a capacitive touch sensor, a pressure sensor, a temperature sensor, a motion sensor, etc. without departing from some aspects of the disclosure. For example, in some embodiments, the hair curler 900 may detect the amount of hair that is wrapped around the body 904 and/or the number of rotations of the body 904 to wrap the hair around the body. For example, in some embodiments, the hair curler 900 may include a temperature sensor that is configured to detect a change in temperature of the hair contact surface 906 of the body 904 and determine the amount of hair that is positioned on the body 904 based on the change in temperature. In further embodiments, the hair curler 900 may include a motion sensor that detects motion or rotation of the body 904 of the hair curler 900 to determine the amount of hair that is wrapped around the body 904. In some embodiments, the hair curler 900 may include a sensor positioned to detect if the hair curler 900 is moved between opened and closed positions to insert hair into the hair curler 900. For example, a position sensor may be positioned between arms (e.g., the arms 1602, 1604 of the hair styling apparatus 1600 shown in Fig. 34) or on a hinge (e.g., the hinge 1510 of the hair styling apparatus 1500 shown in Fig. 33) to detect when the hair curler 900 receives hair.

[00129] As seen in Fig. 22, the hair curler 900 includes a user interface 916 disposed on the handle 902 between the body 904 and the first end 910. In other embodiments, the user interface 916 may be at a different location on the hair curler 900. The user interface 916 includes buttons 918 to allow the user to change operating settings of the hair curler 900 (e.g., to change modes of the hair curler 900) and a display 919. In some embodiments, the user interface 916 includes a speaker, a touchscreen, and/or any other input/output devices.

[00130] The hair curler 900 includes a stand 920 attached to the handle 902 and arranged to support the hair curler 900 in conjunction with the handle 902 such that the body 904 is spaced from a surface supporting the hair curler 900.

The stand 920 extends radially outward from the handle 902 and has a relatively flat edge that is configured to rest on the surface.

[00131] Referring to Figs. 25 and 26, the hair curler 900 includes a heating assembly 922 including one or more heating elements 924 housed within the body 904 in thermally conductive relationship with the hair contact surface 906 for heating the hair contact surface 906. In the illustrated embodiment, the heating assembly 922 includes a positive temperature coefficient "PTC" heating element 924. For example, the heating element 924 generates heat when electrical current is provided to the heating element 924. The amount of heat generated by the heating element 924 depends on characteristics such as material, resistance, amount of current, etc. The temperature of the heating element 924 may be regulated to a value less than a maximum value of the heating element 924 by cycling the electrical current provided to the heating element 924 according to a duty cycle. As used herein, the phrase "duty cycle" refers to a ratio of the time that current is provided to the time that the current is off during a single cycle. The duty cycle at which the electrical current is provided to the heating element 924 may relate to a temperature control set point for the heating assembly 922. The heating assembly 922 may include other heating elements without departing from some aspects of the disclosure.

[00132] Accordingly, the hair curler 900 is configured to deliver heat to the hair wrapped around the body 904 and style (e.g., curl) the hair during a hair styling operation. As used herein, the term "styling operation" refers to heating a section of hair to provide a desired style effect to the section of hair. For example, the illustrated hair curler 900 delivers heat to hair wrapped around the body 904 to curl the hair.

[00133] As described in more detail herein, the hair curler 900 is configured to account for unique characteristics of the hair and/or operating parameters to provide a customized styling operation. For example, the hair curler 900 is configured to adjust a temperature set point of the heating assembly 922 based on a comparison of a measured curl profile and a desired curl profile to provide a desired curl temperature and/or a desired curl time for a styling operation.

[00134] The heating element 924 is suitably connected to a power supply (not shown) of the hair curler 900 such that, during operation of the hair curler 900, electrical current is supplied to the heating element 924 to heat the hair contact surface 906. For example, in the illustrated embodiment, the hair curler 900 includes a cord 926 that is connectable to an external power source (not shown), such as an outlet providing alternating current (AC) power. In the illustrated embodiment, the cord 926 extends outward from handle 902 at the first end 910 of the hair curler 900. In some embodiments, the hair curler 900 may include a battery and/or any other suitable AC or direct current (DC) power source.

[00135] The heating assembly 922 is mounted to and at least partially housed within the body 904 and/or the handle 902. The heating assembly 922 includes a first temperature sensor 930 positioned to measure the temperature of the heating assembly 922 and a second temperature sensor 932 positioned to measure a temperature of at least one of the hair contact surface 906 and hair positioned on the body 904. For example, in one embodiment, the first temperature sensor 930 may be used to measure the temperature of the heating element 924 and provide temperature readings to a temperature control system.

In the illustrated embodiment, the first temperature sensor 930 is disposed within the body 904 and mounted to the heating element 924. The second temperature sensor 932 is mounted to and extends along at least a portion of the hair contact surface 906. Specifically, the second temperature sensor 932 is attached to or incorporated into the hair detection sensor 914 on the body 904 and detects a temperature of the hair. The second temperature sensor 932 is thermally isolated from the hair contact surface 906 and the heating element 924 and is arranged to measure a temperature of the hair wrapped around the body 904.

[00136] The temperature sensors 930, 932 may comprise at least one of a negative temperature coefficient (NTC) thermistor and/or a positive temperature coefficient (PTC) thermistor. For example, in the example embodiment, the first temperature sensor 930 is a NTC thermistor and is arranged to measure the temperature of the heating element 924. The second temperature sensor 932 is a NTC thermistor and is arranged to measure the temperature of the hair contact surface 906 and/or the temperature of the hair on the hair contact surface 906. The NTC thermistors of the first and second temperature sensors 930, 932 are less expensive and are simpler to operate than other temperature sensors. For example, a temperature of the NTC thermistors can be determined using a voltage divider. Any suitable temperature sensor may be used in addition to or instead of a thermistor without departing from the scope of this disclosure. For example, in some embodiments, the temperature sensors 930, 932 may comprises a NTC thermistor, a PTC thermistor, a resistance temperature detector (RTD), and/or a thermocouple.

[00137] A control system 934 is carried by the hair curler 900 and is operatively connected to each temperature sensor 930, 932. In one embodiment, the control system 934 comprises an analog-to-digital converter (ADC) 936, a processor 938, and a memory 940 for storing instructions to be executed by the processor 938. Alternatively, the control system 934 may include any suitable processing device or combination of processing devices. The control system 934 is configured to operate the hair curler 900 by controlling the heating assembly 922 during operation of the hair curler 900, as described in more detail herein.

[00138] With reference now to Fig. 27, a temperature control system that may be used with the hair curler 900, the hair styling apparatus 1500, and the hair styling apparatus 1600 is indicated generally at 1000. The temperature control system 1000 includes a controller 1002 that may be implemented, for example, using the control system 934 (shown in Fig. 25).

[00139] The controller 1002 is communicatively coupled to a monitoring device 1004. The monitoring device 1004 is operable to assess if hair is wrapped around or otherwise positioned on the body 904 (shown in Fig. 19). The monitoring device 1004 may be any device (e.g., an electro-mechanical monitoring device) capable of detecting the presence of hair on the body 904. For example when used with the hair curler 900, the monitoring device 1004 includes the hair detection sensor 914 and is configured to electromechanically detect the presence of hair on the body 904. In other embodiments, the monitoring device 1004 may include a temperature sensor such as the temperature sensor 932 and be configured to determine the presence of the hair based on a change in heat load of the body 904. Other suitable monitoring devices may be used to monitor the presence of hair without departing from the scope of this disclosure. In other embodiments, the controller 1002 is not communicatively coupled to a monitoring device.

[00140] In addition, the control system 1000 includes a sensing device 1006 configured to detect one or more of an operating parameter of the hair curler 900 or a characteristic of the hair. Operating parameters of the hair curler 900 include, for example and without limitation, amount of time the hair curler 900 is held in contact with hair, amount of hair styled during a single styling operation, amount and location of hair on the body 904 of the hair curler 900, and temperature of the heating assembly 922. Characteristics of the hair include, for example and without limitation, temperature, thickness, moisture content, and color. For example, the sensing device 1006 includes the temperature sensors 930, 932 mounted within the body 904, and the sensing device 1006 is configured to monitor a temperature of the heating element 924, a temperature of the hair contact surface 906, and/or a temperature of hair contacting the hair contact surface 906. In other embodiments, the sensing device 1006 may include different or additional sensors for detecting other operating parameters of the hair curler 900 or other characteristics of the hair, such as a moisture sensor, an optical sensor for detecting hair color, and the like.

[00141] Referring to Figs. 25-27, when used with the hair curler 900, the controller 1002 controls a temperature of the heating element 924 of the heating assembly 922 to deliver heat to the hair wrapped around the body 904. In particular, the controller 1002 controls the temperature of the heating element 924 by regulating electrical current to the heating element 924 based on a temperature set point. The temperature set point may be determined based on a curl temperature and/or a curl time of at least one hair styling operation. Accordingly, the controller 1002 facilitates operating the hair curler 900 in a manner that is customized for the user and/or the hair being styled. As a result, the hair curler 900 may provide an improved styling experience for individuals in comparison to apparatus that do not account for an individual's manner of operating the apparatus or hair characteristics.

[00142] For example, the controller 1002 includes a curl profile system 1008 that provides a curl profile including a curl time and/or a curl temperature. In the example embodiment, the controller 1002 receives a signal from the monitoring device 1004 that indicates the presence of the hair on the body 904, a signal from the first temperature sensor 930 that indicates the temperature of the heating element 924, and a signal from the second temperature sensor 932 that indicates the temperature at the hair contact surface 906. Based on the received signals, the controller 1002 determines the estimated temperature of the hair wrapped around the body 904. In the example embodiment, the controller 1002 monitors the temperature of the hair contact surface 906 and a rate of change of the temperature. The controller 1002 estimates that the hair temperature is equal to the temperature of the hair contact surface 906 when the rate of change of the temperature is zero or less than a threshold value. In further embodiments, the controller 1002 may determine the estimated hair temperature based on a function of the surface temperature and the rate of change of the surface temperature. Other embodiments may use any other suitable technique for determining the estimated hair temperature.

[00143] The curl profile system 1008 determines a curl time based on a start time and an end time of the styling operation. For example, the controller 1002 may identify the start of a styling operation (e.g., curling a length of hair) when the monitoring device 1004 indicates that hair is positioned on the body 904. The controller 1002 may identify the end of the styling operation when the monitoring device 1004 indicates that the hair is no longer on the body 904, when the hair has reached a desired temperature, and/or when a curl time limit is reached.

[00144] The curl profile system 1008 provides the curl profile to an artificial intelligence ("AI") system 210 which determines the temperature set point for the heating assembly 922 based on the curl profile and/or information from the sensing device 1006. The AI system 1010 may utilize machine learning in which the AI system learns from multiple iterations to better predict and regulate operating parameters of the hair curler 900. For example, the AI system 1010 may incrementally adjust a temperature set point based on information from successive styling operations until the curl profile of the styling operation resembles a desired curl profile.

[00145] The AI system 1010 provides the determined temperature set point to a temperature regulation module 1012. The temperature regulation module 1012 regulates the heating assembly 922 based on the determined temperature set point received from the AI system 1010. The temperature set point and operation of the temperature regulation module 1012 may be adjusted for each styling operation until a measured curl profile approaches or matches a desired curl profile. One or more of the temperature set points may be stored in the memory and retrieved by the temperature regulation module 1012 when the hair curler 900 is powered on, when a mode of the hair curler 900 is selected, and/or when a new hair styling operation begins. In some embodiments, the temperature regulation module 1012 may comprise a proportional-integral-derivative controller (PID controller), a PI controller, and/or a P controller which determines and corrects errors when controlling the duty cycle of the heating element 924 in a continuous feedback loop.

[00146] Fig. 28 is a flow chart illustrating an embodiment of a method 1100 for controlling the hair curler 900. With reference to Figs. 19, 27, and 28, the method 1100 may be implemented, for example by the controller 1002, to operate the hair curler 900 during styling operations. In some embodiments, the hair curler 900 includes different modes of operation that are selectable by a user. For example, the user may select a manual mode in which the temperature regulation module 1012 operates in accordance with one or more fixed temperature set points to maintain the temperature of the heating assembly 922 at the user selected value and/or within a range of temperature values. The hair curler 900 may also include at least one style adapt mode in which the hair curler 900 adjusts operation of the hair curler 900 using the AI system 1010 based on an operating parameter and/or hair characteristics to provide a customized styling operation for the user. In some embodiments, the hair curler 900 includes a first style adapt mode which includes profile information determined for a first user and a second style adapt mode which includes profile information determined for a second user. The hair curler 900 may operate in the first and second style adapt modes to learn and adapt to the unique characteristics or operating manners of the first and second users. Accordingly, two or more users may use the hair curler 900 without the hair curler 900 having to relearn or adjust to the user each time the first or second user operates the hair curler 900. Also or alternatively, the multiple style adapt modes allow a single user to utilize different style adapt modes for different styling operations. In some embodiments, the hair curler 900 includes profiles or modes for multiples users, different style uses or techniques, different hair properties (e.g., wet and dry profiles), higher styling performance during operation, and/or hair protection or health.

[00147] In the method 1100, the user initiates 1102 the style adapt mode. For example, the user may select, using the user interface 916, the style adapt mode from a menu of options. In some embodiments, the hair curler 900 automatically initiates the style adapt mode when the hair curler 900 is powered on. In embodiments that default to the style adapt mode, the user may make a selection to switch the hair curler 900 out of the style adapt mode.

[00148] The hair curler 900 may be simpler to use than other styling apparatus that require the user to make multiple selections and/or input information into the hair curler 900 for a styling operation. For example, the hair curler 900 may automatically retrieve customized settings from previous styling operations and/or adjust during styling operations based on curl profiles to provide a customized styling operation when the style adapt mode is activated without the user having to select or input operating parameters and/or characteristics.

[00149] In the method 1100, when the style adapt mode is initiated, the controller 1002 commences 1104 a temperature control algorithm and regulates electrical current to the heating assembly 922 to energize the heating element 924. For example, the controller 1002 regulates the temperature of the heating assembly 922 based on feedback from sensors, such as the first and second temperature sensors 930, 932, and a duty cycle of the heating element 924 of the heating assembly 922. In particular, the controller 1002 receives temperature readings from NTC sensors. The controller 1002 monitors the temperature of the heating assembly 922 and the duty cycle and determines 1106 if the heating assembly 922 is preheated (i.e., the temperature of the hair contact surface 906 is equal to or greater than a predetermined preheat temperature). The controller 1002 monitors the temperatures (e.g., receives reading of the temperatures continuously or periodically) of the heating assembly 922 until the heating assembly 922 reaches the threshold value. The hair curler 900 alerts 1108 the user when the hair curler 900 is preheated. For example, the alert may comprise a light, a display message, an audible indication, a vibratory indication, and/or any other human cognizable alert.

In other embodiments, the hair curler 900 does not provide a user cognizable alert when the hair curler 900 is preheated.

[00150] After determining 1106 that the hair curler 900 is preheated, the controller 1002 determines 1110 if hair has been positioned around the body 904 to start a styling operation. The controller 1002 identifies a start of a hair styling operation when the controller 1002 receives a signal from the monitoring device 1004 that hair has been detected on the body 904. In the illustrated embodiment, the monitoring device 1004 sends a signal to the controller 1002 to identify a start of the hair styling operation when the hair detection sensor 914 detects hair against a switch of the hair detection sensor 914 on the hair contact surface 906 and/or when the monitoring device 1004 detects a decrease in the temperature of the hair contact surface 906.

[00151] The curl profile system 1008 collects and evaluates temperature readings received during the styling operation. For example, the controller 1002 may receive at least four temperature readings per second. In other embodiments, the controller 1002 may receive any number of temperature readings per second that permits the controller 1002 to control the hair curler 900 as described herein, including more or fewer than four temperature readings per second. The curl profile system 1008 determines 1112 a surface NTC temperature of the hair contact surface 906 and a rate of change of the surface temperature (e.g., a derivative of the surface NTC temperature) for a styling operation. The surface NTC temperature may be determined based on values received from the temperature sensor 932. The rate of change of the surface temperature may be determined by calculating a derivative of the surface temperatures provided by the monitoring device 1004 during a styling operation.

[00152] The curl profile system 1008 compares the rate of the change of the surface temperature to a threshold value (e.g., the controller 1002 may determine if the rate of change is zero or less than one). If the rate of change is less than or equal to the threshold value, the controller 1002 determines 1114 that the styling operation is complete and records the associated surface temperature as a curl temperature for the styling operation. In some embodiments, the curl profile system 1008 determines the curl temperature using a look-up table or empirical data that correlates actual hair temp and the surface temperature. In some embodiments, the controller 1002 includes a threshold value such as a minimum curl time that must be met before the controller 1002 determines that the styling operation is complete based on the rate of change of the surface temperature. The controller 1002 may include a maximum threshold value such as a maximum curl time that will trigger completion of the hair styling operation even if the rate of change of the surface temperature does not indicate a completed styling operation. [00153] The hair curler 900 provides 1116 an indication such as audible indication, a visual indication, a tactile indication, or any other suitable indication when the controller 1002 determines that the styling operation is complete (e.g., a "curl ready" indication). In further embodiments, the hair curler 900 may deactivate the heating assembly 922 or decrease a temperature of the heating assembly 922 when the controller 1002 determines that the styling operation is complete. In some embodiments, the hair curler 900 may not provide a user cognizable alert when the styling operation is complete.

[00154] The curl profile system 1008 stores curl profiles for each styling operation on the memory 940. The stored curl profile for each styling operation includes a curl temperature. In some embodiments, the curl temperature is an average of curl temperatures determined from the respective styling operation and one or more previous styling operations. The average curl temperature may be determined based on a predetermined number of styling operations. For example, in some embodiments, the average curl temperature for a curl profile is determined based on no more than twenty hair styling operations. In further embodiments, the average curl temperature for a curl profile is determined based on no more than sixteen hair styling operations. As a result, the controller 1002 may be quicker to adapt if operating parameters or hair characteristics change. For example, the hair curler 900 may adjust to a new user within a single use of the hair curler 900 because a user typically utilizes the hair curler 900 for more than sixteen styling operations during a single use.

In the example, the curl profile system 1008 is configured to determine the average curl temperature based on no more than five hair styling operations. Accordingly, the curl profile system 1008 is quick to adjust, reduces calculation time, and reduces the amount of required memory.

[00155] The AI system 1010 of the controller 1002 compares 1118 the curl profile to a desired curl profile. For example, the controller 1002 may compare the curl temperature for a single styling operation or the average curl temperature of multiple styling operations to a desired curl temperature.

In some embodiments, the desired curl temperature may be in a range of 40° C to 250° C. In some embodiments, the desired curl temperature may be determined based at least partially on a user selection.

[00156] The AI system 1010 of the controller 1002 is programmed to adjust or maintain a temperature set point based on the comparison of the determined curl profile and the desired curl profile. For example, the AI system 1010 is configured to increase 1120 the temperature set point of the heating assembly 922 if the AI system 1010 determines 1122 that the determined curl temperature is less than the desired curl temperature. For example, the AI system 1010 is configured to increase the temperature set point of the heating assembly 922 by a predetermined gain value multiplied by the difference between the desired curl temperature and the determined curl temperature. For example, the predetermined gain value is a positive value greater than zero and is multiplied by the actual difference between the determined curl temperature and the desired curl temperature to prevent overshoot. The gain value can be increased to provide convergence within less passes or decreased to make the system slower to change and, therefore, more stable. For example, a gain value less than one would provide an adjustment that is less than the actual difference between the desired curl temperature and the determined curl temperature. A gain value less equal to one would provide an adjustment that is equal to the actual difference between the desired curl temperature and the determined curl temperature. A gain value greater than one would provide an adjustment that is greater than the actual difference between the desired curl temperature and the determined curl temperature.

[00157] The AI system 1010 is configured to maintain

1124 the same temperature set point of the heating assembly 922 if the AI system 1010 determines 1126 that the determined curl temperature is equal to the desired curl temperature. The AI system 1010 is configured to decrease 1128 the temperature set point of the heating assembly 922 if the AI system 1010 determines 1130 that the determined curl temperature is greater than the desired curl temperature. For example, the AI system 1010 is configured to decrease the temperature set point of the heating assembly 922 by a predetermined gain value multiplied by the difference between the determined curl temperature and the desired curl temperature. In the example embodiment, the gain value is greater than zero. In other embodiments, the gain value may be one, less than one, greater than one, or the gain value may not be used.

[00158] The temperature regulation module 1012 of the controller 1002 is programmed to operate the heating assembly 922 in accordance with the determined temperature set point for one or more subsequent hair styling operations. For example, after the temperature set point is determined based on the initial hair styling operation, the method 1100 returns to determining 1110 if hair has been positioned on the body 904 of the hair curler 900. The controller 1002 identifies the start of a second styling operation when a second section of hair is positioned around the body 904 of the hair curler 900. The temperature regulation module 1012 operates the heating assembly 922 in accordance with the second temperature set point for the second styling operation.

[00159] After the second styling operation is completed, the controller 1002 may determine 1114 a second curl temperature for the second hair styling operation, compare 1118 the second curl temperature and the desired curl temperature, and determine a second temperature set point of the heating assembly 922 based on the comparison of the second temperature profile and the desired hair temperature.

[00160] The temperature regulation module 1012 is configured to operate the heating assembly 922 in accordance with the determined second temperature set point for a third hair styling operation. For example, the temperature regulation module 1012 of the controller 1002 energizes the heating element 924 in accordance with the second temperature set point to deliver heat to hair positioned on the body 904 during the third hair styling operation. The controller 1002 may repeat steps of the method 1100 to determine additional temperature set points during subsequent styling operations. [00161] The controller 1002 is programmed to repeat steps of the method 1100 and determine temperature set points for any number of hair styling operations. Accordingly, the controller 1002 is programmed to continually adjust operation of the hair curler 900 to match and maintain a desired temperature profile. Moreover, one or more of the determined temperature set points may be stored in the memory 940 and retrieved by the controller 1002 when the style adapt or other modes are activated. Accordingly, the hair curler 900 may utilize the most recent determined temperature set point to provide a customized styling operation even when the hair curler 900 powers off or switches modes between styling operations. As a result, the user is not required to select a specific user profile or input characteristics when starting a styling operation.

[00162] In some embodiments, the controller 1002 may disregard information from one or more hair styling operations if the temperature profiles for the styling operations are outside of preset parameters. For example, the controller 1002 may disregard styling operations that have a curl time less than a minimum threshold or a curl time greater than a maximum threshold. In some embodiments, the minimum and maximum thresholds include preset values stored in the memory 940. In further embodiments, the minimum and maximum thresholds are determined by the controller 1002 based on average curl times for previous styling operations. Accordingly, the controller 1002 may reduce errors for invalid data points. [00163] The method 1100 provides a continuous feedback loop in which a temperature set point is determined based on each hair styling operation and the hair curler 900 provides hair styling operations that are customized for operating parameters and/or hair characteristics.

[00164] Fig. 29 is a flow chart illustrating an embodiment of a method 1200 for controlling the hair curler 900. With reference to Figs. 19, 27, and 29, the method 1200 may be implemented, for example by the controller 1002, to operate the hair curler 900 during styling operations. In the method 1200, the user initiates 1202 the style adapt mode and the controller 1002 starts 1204 a temperature control algorithm and regulates electrical current to the heating assembly 922 to energize the heating element 924. For example, the controller 1002 may regulate the temperature of the heating assembly 922 based on feedback from sensors and a duty cycle of the heating element 924 of the heating assembly 922. In particular, the controller 1002 may receive temperature readings from NTC sensors such as the first and second temperature sensors 930, 932. The controller 1002 monitors the temperature of the heating assembly 922 and determines 1206 if the heating assembly 922 is preheated (i.e., the temperature of the hair contact surface 906 is above a preset preheat temperature). The controller 1002 monitors the temperatures (e.g., receives reading of the temperatures continuously or periodically) of the heating assembly 922 until the heating assembly 922 reaches the threshold value. The hair curler 900 alerts 1208 the user when the hair curler 900 is preheated by providing a user cognizable alert. [00165] After determining 1206 that the hair curler 900 is preheated, the controller 1002 determines 1210 if hair has been positioned around the body 904 and starts 1212 a curl timer for the duration of the styling operation. For example, the controller 1002 identifies a start time for the curl timer when the controller 1002 receives a signal from the monitoring device 1004 that hair has been detected on the body 904 and/or when the monitoring device 1004 detects a decrease in the temperature of the hair contact surface 906.

[00166] The sensing device 1006 measures an operating parameter of the heating assembly 922 or a characteristic of the hair and provides information to the controller 1002. For example, the second sensor 932 measures 1214 temperatures of the hair contact surface 906 during the styling operation and provides temperature readings to the temperature curl profile system 1008. For example, the temperature curl profile system 1008 of the controller 1002 may receive at least four temperature readings per second. In other embodiments, the controller 1002 may receive any number of temperature readings per second that permits the controller 1002 to control the hair curler 900 as described herein, including more or fewer than four temperature readings per second.

[00167] The curl profile system 1008 determines 1216 an estimated hair temperature based on a surface NTC temperature of the hair contact surface 906 received from the second temperature sensor 932. For example, the estimated hair temperature may be calculated using an empirically developed model that relates the surface NTC temperature to an estimated hair temperature. In the example, the curl profile system 1008 monitors the surface NTC temperature of the hair contact surface 906 and records the minimum surface temperature for a pass. The minimum temperature of the hair contact surface 906 indicates the time at which the hair contact surface 906 is at equilibrium with the hair. After equilibrium is reached, the temperature of the hair contact surface 906 is used to determine the hair temperature. For example, the surface temperature is calculated using the following equation: where T_surface is the surface temperature, T_sensor is a temperature measured by a sensor such as the second temperature sensor 932,

C is a constant value, and 0 is an offset. In other embodiments, the curl profile system 1008 may use a look-up table to determine the estimated hair temperature based on the surface NTC temperature. In further embodiments, the curl profile system 1008 receives signals from a sensor that directly measures the temperature of the hair.

[00168] The curl profile system 1008 of the controller 1002 compares 1218 the estimated hair temperature to a desired hair temperature. If the estimated hair temperature is less than the desired hair temperature, the curl profile system 1008 continues to receive temperature readings and determines 1216 estimated hair temperatures. If the curl profile system 1008 determines 1220 that the estimated hair temperature is greater than or equal to the desired hair temperature, the curl profile system 1008 stops 1222 the curl timer and records the duration between the start and stop times as a curl time for the styling operation. In some embodiments, the curl profile system 1008 compares the curl time to a threshold value such as a minimum curl time that must be met before the curl profile system 1008 determines that the styling operation is complete based on the estimated hair temperature. The curl profile system 1008 may compare the curl time to a maximum threshold value and trigger completion of the hair styling operation if the curl time is equal to or greater than the maximum threshold even if the estimated hair temperature does not indicate a completed styling operation. In the illustrated embodiment, the hair curler 900 provides a user cognizable alert 1224 such as audible indication, a visual indication, a tactile indication, or any other suitable indication when the curl time is recorded and the styling operation is complete (e.g., a "curl ready" indication).

[00169] The curl profile system 1008 stores a curl profile for the styling operation on the memory 940. The curl profile includes the curl time for the styling operation. In some embodiments, the stored curl profiles may include an estimated hair temperature and/or the curl temperature. In some embodiments, the memory 940 stores a number of curl profiles and the curl profile system 1008 determines an average curl time based on a predetermined number of styling operations. For example, in some embodiments, the curl profile includes an average curl time determined based on no more than twenty hair styling operations. In further embodiments, the average curl time is determined based on no more than sixteen hair styling operations. [00170] The AI system 1010 compares 1226 the curl time of the curl profile to a desired curl time. For example, the controller 1002 compares the curl time of a single hair styling operation or an average curl time of multiple styling operations to the desired curl time. In some embodiments, the desired curl time may be in a range of about one second to about ninety seconds. In the example, the desired curl time is less than twenty seconds. A curl time outside the set limits is disregarded as a user mistake and/or an operating error. In some embodiments, the desired curl time may be determined based at least partially on a user selection.

[00171] The AI system 1010 is configured to adjust or maintain a temperature set point based on the comparison 1226 of the determined curl time and the desired curl time. For example, the controller 1002 is programmed to increase 1228 the temperature set point of the heating assembly 922 if the controller 1002 determines 1230 that the determined curl time is greater than the desired curl time. For example, the controller 1002 is programmed to increase the temperature set point of the heating assembly 922 by a predetermined gain value multiplied by the magnitude of the difference between the desired curl time and the determined curl time. The controller 1002 is programmed to maintain 1232 the same temperature set point of the heating assembly 922 if the controller 1002 determines 1234 that the determined curl time is equal to the desired curl time. The controller 1002 is programmed to decrease 1236 the temperature set point of the heating assembly 922 if the controller 1002 determines 1238 that the determined curl time is less than the desired curl time. For example, the controller 1002 is programmed to decrease the temperature set point of the heating assembly 922 by a predetermined gain value multiplied by the difference between the desired curl time and the determined curl time. In the example embodiment, the gain value is greater than zero. In other embodiments, the gain value may be one, less than one, or the gain value may not be used. In the example, the gain value is unit less because the gain value is used to convert temperature differences to temperature values (i.e., the gain value represents 1° C/1° C). The gain value may have other conversion units such as 1° C/second in embodiments that use a time based approach or other operating parameter to determine the adjustment to the temperature set value.

[00172] The controller 1002 is programmed to operate the heating assembly 922 in accordance with the determined temperature set point for one or more subsequent hair styling operations. For example, after the temperature set point is determined based on the initial hair styling operation, the method 1200 returns to determining 1210 if hair has been positioned on the body 904 of the hair curler 900 and the controller 1002 starts 1212 a curl timer if hair is positioned on the body 904. The controller 1002 operates in accordance with the determined temperature set point for the second styling operation, determines a second curl profile, compares the second curl profile to the desired curl profile, and determines a second temperature set point of the heating assembly 922 based on the comparison of the second curl profile and the desired curl profile. [00173] The controller 1002 is programmed to operate the heating assembly in accordance with the determined second temperature set point for a third hair styling operation. For example, the controller 1002 energizes the heating element in accordance with the second temperature set point to deliver heat to hair positioned on the body 904 during the third hair styling operation. The controller 1002 may repeat steps of the method 1200 to determine a third temperature set point. The controller 1002 is programmed to repeat steps of the method 1200 and determine temperature set points for any number of hair styling operations. In some embodiments, the controller 1002 may disregard information from one or more hair styling operations if the curl times for the styling operations are outside of preset parameters. For example, the controller 1002 may disregard styling operations that have a curl time less than a minimum threshold or a curl time greater than a maximum threshold. Accordingly, the controller 1002 may reduce errors for invalid data points.

[00174] Fig. 30 illustrates the hair curler 900 being using for a styling operation for hair 942. The hair curler 900 is configured for the hair 942 to be wrapped around the body 904 such that the hair 942 forms a curl around the hair contact surface 906 and extends around the longitudinal axis 908. The heating assembly 922 is configured to deliver heat to the hair 942 wrapped around the body 904. The hair curler 900 delivers heat to the hair 942 for a curl time and styles the hair 942.

For example, the hair curler 900 is configured to curl the hair 942. In some embodiments, the hair curler 900 may be configured to perform other styling operations. [00175] Referring to Figs. 19, 27, and 30, during operation, the hair curler 900 is activated and the controller 1002 energizes the heating element 924 of the heating assembly 922 to heat up the hair contact surface 906. The hair 942 is wrapped around the body 904 and heat is delivered to the hair 942 via the hair contact surface 906 during a styling operation. For example, a proximal end 948 of the hair 942 is positioned on the body 904 of the hair curler 900 and the hair curler 900 is held in position while the hair 942 is wrapped around the body 904. After completion of the styling operation, the hair 942 may be unwrapped from the body 904. For example, the hair curler 900 may provide a "curl ready" indication to the user when the styling operation is complete. The user may then gather another section of the hair 942 for another styling operation.

[00176] The controller 1002 determines a curl profile for each styling operation for the hair 942 and compares the curl profile to a desired curl profile. The controller 1002 adjusts operation of the hair curler 900 based on the comparison of the curl profile and the desired curl profile. For example, the controller 1002 adjusts a temperature set point of the heating assembly 922 based on a comparison of a curl time for the hair 942 during the styling operation and a desired curl time and/or a comparison of a curl temperature for the hair 942 during the styling operation and a desired curl temperature.

The controller 1002 increases or decreases the temperature set point after the styling operation if the curl time does not match the desired curl time and/or the curl temperature does not match the desired curl temperature. Accordingly, the controller 1002 operates the heating assembly 922 to account for unique operating parameters and/or hair characteristics to provide a curl profile that is closer to a desired curl profile than hair curlers that do not account for unique operating parameters and/or hair characteristics.

[00177] Fig. 31 illustrates operation of the temperature control system 1000 (shown in Fig. 27) to control an operating temperature of the hair curler 900 (shown in Fig. 19) during multiple styling operations 1300, 1302, 1304, 1306, 1308, 1310, 1312, 1314, 1316, 1318. For example, during a first styling operation 1300, the integrated controller 1002 of the temperature control system 1000 operates the hair curler 900 in accordance with a first temperature set point 1320. The first temperature set point is used to control the heating element 924 and may be determined based on the target temperature for the body 904 and/or the hair. For example, the first temperature set point may be calculated for the heating element 924 to provide sufficient heat for the body 904 and/or the hair to reach the desired temperature. The first temperature set point may be stored in the memory 940 and be retrieved by the processor 938 when the hair curler 900 is powered on. The first temperature set point may be a preset default value or may be determined based on one or more previous styling operations.

[00178] The heating element 924 heats the body 904 up to the first temperature set point 1320 when the hair curler 900 is powered on. The temperature of the body 904 may initially decrease when the hair is positioned on the body 904 of the hair curler 900 for the first styling operation 1300. The hair curler 900 may operate in accordance with the first temperature set point during the first styling operation 1300. For example, the hair curler 900 may energize the heating element 924 to increase temperature of the body 904 based on the first temperature set point 1320. The first styling operation 1300 ends when the hair is removed from the body 904 and/or a selected curl time has elapsed.

[00179] The temperature of the body 904 and/or the estimated hair temperature during the styling operation is compared to a target temperature 1322 and the integrated controller 1002 may adjust the first temperature set point 1320 to a second temperature set point 1324 based on the comparison. For example, the temperature set point may be increased if the temperature of the hair is less than the target temperature 1322. The temperature set point may be decreased if the temperature of the hair is greater than the target temperature. The temperature set point is adjusted by a value determined based on the actual difference between the measured temperature and the target temperature. For example, the AI system 1010 (shown in Fig. 27) may use a gain value to incrementally adjust the temperature set point based on a difference between the target temperature and an estimated temperature.

[00180] During a second styling operation 1302, the temperature control system 1000 operates the hair curler 900 in accordance with the second temperature set point 1324 that was determined based on the first styling operation 1300. As shown in Fig. 31, the second temperature set point 1324 is greater than the first temperature set point 1320 because the hair temperature during the first styling operation 1300 is less than the target temperature 1322.

[00181] The temperature of the hair during the second styling operation 1302 is compared to the target temperature 1322 and the second temperature set point 1324 is adjusted to determine a third temperature set point 1326 based on the comparison. For example, the third temperature set point 1326 is greater than the second temperature set point 1324 because the hair temperature during the second styling operation 1302 is less than the target temperature 1322.

[00182] During the third styling operation 1304, the temperature control system 1000 operates the hair curler 900 in accordance with the third temperature set point 1326 that was determined based on the second styling operation 1302. The temperature of the hair during the third styling operation 1304 is compared to the target temperature 1322 and the third temperature set point 1326 is adjusted to determine a fourth temperature set point 1328 based on the comparison. For example, the fourth temperature set point 1328 is greater than the third temperature set point because the measured temperature during the third styling operation 1304 is less than the target temperature.

[00183] During the fourth styling operation 1306, the temperature control system 1000 operates the hair curler 900 in accordance with the fourth temperature set point 1328 that was determined based on the third styling operation 1302. The temperature of the hair during the fourth styling operation 1306 is compared to the target temperature 1322 and the fourth temperature set point 1328 is adjusted to determine a fifth temperature set point 1330 based on the comparison. For example, the fifth temperature set point 1330 is substantially equal to the fourth temperature set point 1328 because the hair temperature during the fourth styling operation is substantially equal to the target temperature 1322.

[00184] During the fifth and sixth styling operations 1308, 1310, the temperature control system 1000 operates the hair curler 900 in accordance with fifth and sixth temperature set points 1330, 1332 that are equal to the fourth temperature set point 1328 because the hair temperatures during the fourth and fifth styling operations 1306, 1308 match the target temperature 1322.

[00185] The temperature of the hair during the sixth styling operation 1310 is different from the target temperature 1322 due to a change in technique by the user or operating parameter change. Accordingly, the sixth temperature set point 1332 is adjusted to determine a seventh temperature set point 1334. For example, the seventh temperature set point 1334 is greater than the sixth temperature set point 1332 because the hair temperature during the sixth styling operation 1310 is less than the target temperature 1322.

[00186] During the seventh styling operation 1312, the temperature control system 1000 operates the hair curler 900 in accordance with the seventh temperature set point 1334 that was determined based on the sixth styling operation 1310. The temperature of the hair during the seventh styling operation 1312 is compared to the target temperature 1322 and the seventh temperature set point 1334 is adjusted to determine an eighth temperature set point 1336 based on the comparison. For example, the eighth temperature set point 1336 is greater than the seventh temperature set point 1334 because the hair temperature during the seventh styling operation 1312 is less than the target temperature 1322.

[00187] During the eighth styling operation 1314, the temperature control system 1000 operates the hair curler 900 in accordance with the eighth temperature set point 1336 that was determined based on the seventh styling operation 1312. The temperature of the hair during the eighth styling operation 1314 is compared to the target temperature 1322 and the eighth temperature set point 1336 is adjusted to determine a ninth temperature set point 1338 based on the comparison. For example, the ninth temperature set point 1338 is substantially equal to the eighth temperature set point 1336 because the hair temperature during the eighth styling operation 1314 is substantially equal to the target temperature 1322.

[00188] During the ninth and tenth styling operations 1316, 1318, the temperature control system 1000 operates the hair curler 900 in accordance with ninth and tenth temperature set points 1338, 1340 that are equal to the eighth temperature set point 1336 because the hair temperatures during the eighth and ninth styling operations 1314, 1316 match the target temperature 1322.

[00189] Notably, the temperature control system 1000 causes the measured temperature to reach the target temperature more quickly than other systems and maintains the actual temperature within 1° C precision of the target temperature because the temperature regulation module 1012 uses proportional-integral-derivative (PID) control, PI control, or P control.

[00190] Fig. 32 is a flow chart illustrating an embodiment of a method 1400 for controlling the hair curler 900 (shown in Fig. 19), the hair styling apparatus 1500 (shown in Fig. 33), or the hair styling apparatus 1600 (shown in Fig. 34). For example, referring to Figs. 25-27, and 32, the method 1400 includes energizing 1402 the heating element 924 of the heating assembly 922 in accordance with a first temperature set point of the heating assembly 922 to deliver heat to hair positioned on the body 904 during a first hair styling operation. For example, the first temperature set point may be retrieved by the controller 1002 from the memory 940. The first temperature set point may be a default value stored in the memory during assembly of the hair curler 900 or a value determined from one or more styling operations.

[00191] The method 1400 also includes receiving 1404, at the controller 1002, a signal relating to a temperature of the heating assembly 922 or the hair. For example, in some embodiments, the controller 1002 may receive a signal from the sensing device 1006 that includes a temperature of the hair or a temperature of the hair contact surface 906. In some embodiments, the controller 1002 is programmed to estimate a temperature of the hair based on the temperature of the hair contact surface.

[00192] The method includes determining 1406, at the controller 1002, a curl profile of the hair. The curl profile includes at least one of a curl temperature and a curl time for the first hair styling operation. For example, in some embodiments, the curl profile includes a curl temperature that is determined based at least partly on a surface temperature of the hair contact surface 906. In some embodiments, the curl profile includes a curl time in addition to or instead of a curl temperature. The controller 1002 may receive a signal from the monitoring device 1004 that indicates if hair is positioned on the body 904 and the controller 1002 may determine a curl start time based on the signal from the monitoring device 1004. The controller 1002 may determine a curl time based on the curl start time and a curl end time determined based at least partly on the temperature of the hair, the temperature of the hair contact surface, and/or a rate of change of the temperature of the hair or hair contact surface. In some embodiments, the curl profile includes a curl temperature and does not include a curl time. In other embodiments, the curl profile includes a curl time and does not include a curl temperature. In further embodiments, the curl profile includes a curl temperature and a curl time. In some embodiments, the curl temperature and/or the curl time are determined based on an average of the curl temperatures or curl times for two or more styling operations to prevent the hair curler 900 from over adjusting due to a single abnormal styling operation.

[00193] The method 1400 further includes comparing 1408 the curl profile to a desired curl profile. The desired curl profile includes at least one of a desired curl temperature and a desired curl time. For example, the curl temperature may be compared to the desired curl temperature to determine if the curl temperature is equal to, greater than, or less than the desired curl temperature. Additionally or alternatively, the curl time may be compared to the desired curl time to determine if the curl time is equal to, greater than, or less than the desired curl time. In some embodiments, the desired curl profile includes a desired curl temperature and does not include a desired curl time. In other embodiments, the desired curl profile includes a desired curl time and does not include a desired curl temperature. In further embodiments, the desired curl profile includes a desired curl temperature and a desired curl time.

[00194] Also, in the illustrated embodiment, the method 1400 includes determining 1410, at the controller 1002, a second temperature set point of the heating assembly 922 based on the comparison of the curl profile and the desired curl profile. In some embodiments, the desired curl temperature and/or the desired curl time includes a range of threshold values for comparison to the curl temperature and/or the curl time. For example, if the curl profile includes a curl time and the desired curl profile includes a desired curl time, the controller 1002 may determine the second temperature set point of the heating assembly 922 by increasing the first temperature set point of the heating assembly if the curl time is greater than an upper threshold, and decreasing the first temperature set point of the heating assembly if the curl time is less than a lower threshold. If the curl profile includes a curl temperature and the desired curl profile includes a desired curl temperature, the controller 1002 may determine the second temperature set point of the heating assembly 922 by increasing the first temperature set point of the heating assembly 922 if the curl temperature is less than a lower threshold, and decreasing the first temperature set point of the heating assembly 922 if the curl temperature is greater than an upper threshold.

[00195] The method 1400 includes energizing 1412 the heating element 924 in accordance with the second temperature set point to deliver heat to hair positioned on the body 904 during a second hair styling operation. Steps of the method 1400 may be repeated for any number of hair styling operations to determine temperature set points for the hair styling operations and operate the hair curler 900 in accordance with the determined temperature set points.

[00196] Referring to Fig. 33, a heated appliance according to one embodiment is illustrated in the form of a hair styling apparatus and is indicated generally by the reference numeral 1500. The illustrated hair styling apparatus 1500 comprises a handle 1502, a body 1504 extending from the handle 1502, and a clamp 1506. The hair styling apparatus 1500 is configured for hair to be wrapped around the body 1504. For example, the body 1504 includes a hair contact surface 1508 arranged to contact hair wrapped around the body 1504. In the illustrated embodiment, the body 1504 and the hair contact surface 1508 are cylindrical.

[00197] As seen in Fig. 33, the clamp 1506 is pivotably connected to the body 1504 by a hinge 1510 and is positionable relative to the body 1504 to secure hair against the body 1504. For example, the clamp 1506 is positionable between an opened position (shown in Fig. 33) in which hair may be inserted between the clamp 1506 and the body 1504 and a closed position in which the clamp 1506 secures the hair on the body 1504. The hair styling apparatus 1500 may include a monitoring device including a sensor positioned to detect if the hair styling apparatus 1500 is moved between the opened and closed positions to insert hair into the hair styling apparatus 1500. For example, a sensor may be positioned on the hinge 1510 to detect when the clamp 1506 is moved relative to the body 1504.

[00198] Referring to Fig. 34, a heated appliance according to one embodiment is illustrated in the form of a hair styling apparatus and is indicated generally by the reference numeral 1600. The illustrated hair styling apparatus 1600 comprises a body 1601 including a pair of arms 1602, 1604 positionable between an opened position in which hair may be inserted between the arms 1602, 1604 and a closed position in which the arms 1602, 1604 are configured to style the hair between the arms 1602, 1604. For example, the arms 1602, 1604 may provide a wave or partial curl effect for the hair. At least one of the arms 1602, 1604 forms a handle 1606 of the hair styling apparatus 1600 that is arranged for a user to grasp.

[00199] As seen in Fig. 34, the arms 1602, 1604 are pivotably connected together by a hinge 1608. The hair styling apparatus 1600 may include a monitoring device including a sensor positioned at the hinge 1608 or at least partly between the arms 1602, 1604 to detect if the hair styling apparatus 1600 is moved between the opened and closed positions to insert hair into the hair styling apparatus 1600.

[00200] Embodiments of hair styling apparatus and temperature control systems for hair styling apparatus described previously with respect to Figs. 19-33 provide customized hair styling operations that account for individual hair characteristics or a manner of operating the hair styling apparatus. The control systems may control a curl temperature and/or a curl time more precisely than prior control systems and provide customized operation because the controls systems account for operating parameters or characteristics of hair determined from one or more styling operations. Moreover, the control systems may utilize computer learning and/or proportional-integral-derivative (PID), PI, or P control to adjust operating parameters more quickly and precisely to a desired operating parameter.

[00201] When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including", and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[00202] As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1. A hair straightener comprising: first and second arms pivotably coupled to each other for selective, pivotal movement relative to each other to selectively configure the hair straightener between an opened position and a closed position, wherein the hair straightener is arranged to receive hair between the first and second arms in the closed position; a heating assembly attached to at least one of the first and second arms and configured to deliver heat to the hair received between the first and second arms, the heating assembly including a heating element; at least one sensor configured to detect at least one temperature of the heating assembly; and a controller in communication with the sensor, the controller configured to: energize the heating element in accordance with a first temperature set point to deliver heat to hair during a first hair styling operation; determine an estimated hair temperature of the hair received between the first and second arms based on the at least one temperature; compare the estimated hair temperature and a desired hair temperature profile; determine a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile; and energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

2. The hair straightener of claim 1, wherein the at least one temperature includes a surface temperature of a surface of the heating assembly, wherein the controller is configured to determine the estimated hair temperature based on the surface temperature and a rate of change of the surface temperature.

3. The hair straightener of claim 1, wherein the desired hair temperature profile includes an upper threshold value and a lower threshold value.

4. The hair straightener of claim 3, wherein the controller is configured to increase the second temperature set point of the heating assembly if the estimated hair temperature is less than the lower threshold value, and decrease the second temperature set point of the heating assembly if the estimated hair temperature is greater than the upper threshold value.

5. The hair straightener of claim 1, wherein the heating assembly includes a hair contact plate that is heated by the heating element, wherein the at least one sensor comprises a temperature sensor configured to detect a temperature at a surface of the hair contact plate, and wherein the at least one temperature received from the at least one sensor includes a plurality of surface temperatures of the hair contact plate received from the temperature sensor.

6. The hair straightener of claim 5, wherein the controller is configured to determine a rate of change of the surface temperatures, and wherein the estimated hair temperature is determined based on the surface temperatures and the rate of change of the surface temperatures.

7. The hair straightener of claim 6, wherein the controller is configured to determine the rate of change of the surface temperatures by calculating a derivative of the surface temperatures received from the temperature sensor.

8. The hair straightener of claim 1, wherein the controller is configured to: determine a second estimated hair temperature of the hair during the second hair styling operation; compare the second estimated hair temperature and the desired hair temperature profile; and determine a third temperature set point of the heating assembly based on the comparison of the second estimated hair temperature and the desired hair temperature profile.

9. The hair straightener of claim 8, wherein the desired hair temperature profile includes an upper threshold value and a lower threshold value, and wherein the controller is configured to increase the second temperature set point of the heating assembly if the second estimated hair temperature is less than the lower threshold value, and decrease the second temperature set point of the heating assembly if the second estimated hair temperature is greater than the upper threshold value.

10. The hair straightener of claim 8, wherein the controller is configured to operate the heating assembly in accordance with the determined third temperature set point for a third hair styling operation.

11. The hair straightener of claim 1 wherein the at least one sensor comprises a positive temperature coefficient thermistor.

12. The hair straightener of claim 1 wherein the at least one sensor comprises a negative temperature coefficient thermistor.

13. The hair straightener of claim 1, further comprising a monitoring device coupled to the controller and operable to monitor movement of the first and second arms between the opened and closed positions of the hair styling apparatus.

14. A temperature control system for a hair styling apparatus having a heating assembly configured to deliver heat to hair, the control system comprising: a memory configured to store a first temperature set point and temperatures of the heating assembly received from a sensor; and a processor communicatively coupled to the memory and configured to: retrieve from the memory the first temperature set point and at least one temperature received from the sensor; energize a heating element of the heating assembly in accordance with the first temperature set point to deliver heat to hair during a first hair styling operation; determine an estimated hair temperature of the hair based on the at least one temperature received from the sensor; compare the estimated hair temperature and a desired hair temperature profile; determine a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile; and energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

15. The temperature control system of claim 14, wherein the processor is configured to determine the estimated hair temperature based on a surface temperature of a surface of the heating assembly and a rate of change of the surface temperature.

16. The temperature control system of claim 14, wherein the desired hair temperature profile includes an upper threshold value and a lower threshold value.

17. The temperature control system of claim 16, wherein the processor is configured to increase the temperature set point of the heating assembly if the estimated hair temperature is less than the lower threshold value, and decrease the temperature set point of the heating assembly if the estimated hair temperature is greater than the upper threshold value.

18. The temperature control system of claim 14, wherein the at least one temperature received from the sensor includes surface temperatures of a contact plate of the heating assembly.

19. The temperature control system of claim 18, wherein the processor is configured to determine a rate of change of the surface temperatures, and wherein the estimated hair temperature is determined based on the surface temperatures and the rate of change of the surface temperatures.

20. The temperature control system of claim 19, wherein the processor is configured to determine the rate of change of the surface temperatures by calculating a derivative of the surface temperatures received from the sensor.

21. The temperature control system of claim 14, wherein the processor is configured to: determine a second estimated hair temperature of the hair during the second hair styling operation; compare the second estimated hair temperature and the desired hair temperature profile; and determine a third temperature set point of the heating assembly based on the comparison of the second estimated hair temperature and the desired hair temperature.

22. The temperature control system of claim 21, wherein the desired hair temperature profile includes an upper threshold value and a lower threshold value, and wherein the processor is configured to increase the third temperature set point of the heating assembly if the second estimated hair temperature is less than the lower threshold value, and decrease the third temperature set point of the heating assembly if the second estimated hair temperature is greater than the upper threshold value.

23. The temperature control system of claim 21, wherein the processor is configured to operate the heating assembly in accordance with the determined third temperature set point for a third hair styling operation.

24. The temperature control system of claim 14 wherein the memory is configured to store a maximum value and a minimum value of a plurality of temperatures received from a sensor during the first hair styling operation, wherein the desired hair temperature profile includes an upper limit and a lower limit, and wherein the processor is configured to compare the maximum value to the upper limit and compare the minimum value to the lower limit.

25. A method for controlling a hair styling apparatus, the hair styling apparatus including a heating assembly, the method comprising: energizing a heating element of the heating assembly in accordance with a first temperature set point to deliver heat to hair during a first hair styling operation; receiving, at a controller, a signal relating to a temperature of the heating assembly during the first hair styling operation; determining, at the controller, an estimated hair temperature during the first hair styling operation based on the temperature of the heating assembly; comparing the estimated hair temperature and a desired hair temperature profile; determining, at the controller, a second temperature set point of the heating assembly based on the comparison of the estimated hair temperature and the desired hair temperature profile; and energizing the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

26. The method of claim 25, wherein determining the estimated hair temperature during the first hair styling operation comprises determining the estimated hair temperature based on a surface temperature of a surface of the heating assembly and a rate of change of the surface temperature.

27. The method of claim 25 further comprising: increasing the second temperature set point of the heating assembly if the estimated hair temperature is less than a lower threshold value; and decreasing the temperature set point of the heating assembly if the estimated hair temperature is greater than an upper threshold value.

28. The method of claim 25 further comprising determining a second estimated hair temperature; comparing the second estimated hair temperature and the desired hair temperature profile; and determining a third temperature set point of the heating assembly based on the comparison of the second estimated hair temperature and the desired hair temperature profile.

29. The method of claim 28 further comprising energizing the heating element in accordance with the third temperature set point to deliver heat to hair during a third hair styling operation.

30. A hair curler comprising: a handle; a body attached to the handle and having a hair contact surface, wherein the hair curler is arranged for hair to be positioned on the body; a heating assembly housed within the body in thermally conductive relationship with the hair contact surface to deliver heat to the hair positioned on the body, the heating assembly including a heating element; a sensor positioned to detect a temperature of the heating assembly or the hair; and a controller in communication with the sensor, the controller programmed to: energize the heating element in accordance with a first temperature set point of the heating assembly to deliver heat to hair during a first hair styling operation; determine a curl profile of the hair based on the temperature of the heating assembly or the hair, wherein the curl profile includes at least one of a curl temperature and a curl time for the first hair styling operation; compare the curl profile to a desired curl profile, wherein the desired curl profile includes at least one of a desired curl temperature for comparison to the curl temperature and a desired curl time for comparison to the curl time; determine a second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile; and energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

31. The hair curler of claim 30, wherein the controller is programmed to determine the second temperature set point by: increasing the first temperature set point of the heating assembly if the curl temperature is less than the desired curl temperature; and decreasing the first temperature set point of the heating assembly if the curl temperature is greater than the desired curl temperature.

32. The hair curler of claim 30, wherein the controller is programmed to determine the second temperature set point by: increasing the first temperature set point of the heating assembly if the curl time is greater than the desired curl time; and decreasing the second temperature set point of the heating assembly if the curl time is less than the desired curl time.

33. The hair curler of claim 30, wherein the controller is programmed to monitor a surface temperature of a surface of the hair contact surface and a rate of change of the surface temperature, and determine the curl temperature based on the surface temperature when the rate of change of the surface temperature is less than or equal to a threshold value.

34. The hair curler of claim 33, wherein the threshold value is 0.

35. The hair curler of claim 30, wherein the controller is programmed to determine an estimated hair temperature based on a surface temperature of the hair contact surface, compare the estimated hair temperature to a threshold curl temperature, and determine the curl time based on a time that the estimated hair temperature meets or exceeds the threshold curl temperature.

36. The hair curler of claim 30, wherein the controller is programmed to: determine a curl start time when hair is positioned on the body and the heating assembly is energized to deliver heat to the hair positioned on the body; determine a curl end time when an estimated hair temperature is at or above a threshold curl temperature; and determine the curl time based on the curl start time and the curl end time.

37. The hair curler of claim 36 further comprising a monitoring device communicatively coupled to the controller, wherein the controller is programmed to determine if the hair is positioned on the body based on a signal received from the monitoring device.

38. The hair curler of claim 37 wherein the monitoring device comprises a contact switch and a gate signal that produces or stops producing a signal when the hair contacts the contact switch.

39. The hair curler of claim 37, wherein the monitoring device comprises a temperature sensor operable to detect a surface temperature of the body, wherein the controller is programmed to determine if hair is positioned on the body based on the surface temperature of the body.

40. The hair curler of claim 30, wherein the controller is programmed to: determine a second curl profile of the hair during the second hair styling operation; compare the second curl profile to the desired curl profile; and determine a third temperature set point of the heating assembly based on the comparison of the second curl profile and the desired curl profile.

41. The hair curler of claim 40, wherein the controller is programmed to operate the heating assembly in accordance with the determined third temperature set point for a third hair styling operation.

42. The hair curler of claim 30, wherein the desired curl profile includes a lower threshold and an upper threshold for the desired curl temperature, wherein the controller is programmed to determine the second temperature set point by: increasing the first temperature set point of the heating assembly if the curl temperature is less than the lower threshold; and decreasing the first temperature set point of the heating assembly if the curl temperature is greater than the upper threshold.

43. The hair curler of claim 30, wherein the desired curl profile includes an upper threshold and a lower threshold for the curl time, wherein the controller is programmed to determine the second temperature set point by: increasing the first temperature set point of the heating assembly if a curl time is greater than the upper threshold; and decreasing the first temperature set point of the heating assembly if the curl time is less than the lower threshold.

44. The hair curler of claim 30, wherein the controller is programmed to determine the curl temperature for the first hair styling operation based on an average of an estimated hair temperature for the first hair styling operation and at least one other hair styling operation.

45. The hair curler of claim 30, wherein the controller is programmed to determine the curl time for the first hair styling operation based on an average curl time for the first hair styling operation and at least one other hair styling operation.

46. The hair curler of claim 30 wherein the sensor comprises a negative temperature coefficient thermistor.

47. The hair curler of claim 30 further comprising a monitoring device communicatively coupled to the controller and operable to detect if hair is positioned on the body, wherein the monitoring device comprises a contact switch and a gate signal that produces or stops producing a signal when the hair contacts the contact switch.

48. The hair curler of claim 30 further comprising a monitoring device communicatively coupled to the controller, the monitoring device comprising a temperature sensor operable to detect a surface temperature of the body, wherein the controller is programmed to determine if hair is positioned on the body based on the surface temperature of the body.

49. A temperature control system for a hair curler, the hair curler having a body and a heating assembly configured to deliver heat to hair positioned on the body, the temperature control system comprising: a memory configured to store a temperature of the heating assembly or the hair; and a processor communicatively coupled to the memory and programmed to: energize a heating element of the heating assembly in accordance with a first temperature set point of the heating assembly to deliver heat to hair during a first hair styling operation; retrieve from the memory the temperature of the heating assembly or the hair; determine a curl profile of the hair based on the temperature of the heating assembly or the hair, wherein the curl profile includes at least one of a curl temperature and a curl time for the first hair styling operation; compare the curl profile to a desired curl profile, wherein the desired curl profile includes at least one of a desired curl temperature for comparison to the curl temperature and a desired curl time for comparison to the curl time; and determine a second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile; and energize the heating element in accordance with the second temperature set point to deliver heat to hair during a second hair styling operation.

50. The temperature control system of claim 49, wherein the desired curl profile includes an upper threshold and a lower threshold for the curl time, and wherein the processor is programmed to determine the second temperature set point by: increasing the first temperature set point of the heating assembly if the curl time is greater than the upper threshold; and decreasing the first temperature set point of the heating assembly if the curl time is less than the lower threshold.

51. The temperature control system of claim 49, wherein the desired curl profile includes an upper threshold and a lower threshold for the desired curl temperature, and wherein the processor is programmed to determine the second temperature set point by: increasing the first temperature set point of the heating assembly if the curl temperature is less than the lower threshold; and decreasing the first temperature set point of the heating assembly if the curl temperature is greater than the upper threshold.

52. The temperature control system of claim 49, wherein the processor is programmed to: monitor an operating temperature of the hair curler; determine a rate of change of the operating temperature; compare the rate of change to a threshold value; determine the operating temperature of the hair curler when the rate of change of the operating temperature is less than or equal to the threshold value; and determine an estimated hair temperature based on the operating temperature of the hair curler when the rate of change of the operating temperature is less than or equal to the threshold value.

53. The temperature control system of claim 52, wherein the threshold value is 0.

54. The temperature control system of claim 49, wherein the processor is programmed to: determine a curl start time when hair is positioned on the body and the heating assembly is energized to deliver heat to the hair positioned on the body; determine a curl end time when an estimated hair temperature is at or above a threshold curl temperature; and determine the curl time based on the curl start time and the curl end time.

55. The temperature control system of claim 54 further comprising a monitoring device communicatively coupled to the processor, wherein the processor is programmed to determine if hair is positioned on the body based on a signal received from the monitoring device.

56. A method for controlling a hair curler, the hair curler including a body and a heating assembly, the method comprising: energizing a heating element of the heating assembly in accordance with a first temperature set point of the heating assembly to deliver heat to hair positioned on the body during a first hair styling operation; receiving, at a controller, a signal relating to a temperature of the heating assembly or the hair; determining, at the controller, a curl profile of the hair, the curl profile including at least one of a curl temperature and a curl time for the first hair styling operation; comparing the curl profile to a desired curl profile, wherein the desired curl profile includes at least one of a desired curl temperature for comparison to the curl temperature and a desired curl time for comparison to the curl time; determining, at the controller, a second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile; and energizing the heating element in accordance with the second temperature set point to deliver heat to hair positioned on the body during a second hair styling operation.

57. The method of claim 56 further comprising determining the curl temperature based on a surface temperature of a hair contact surface of the hair curler and a rate of change of the surface temperature.

58. The method of claim 56, wherein determining the second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile comprises: increasing the first temperature set point of the heating assembly if the curl time is greater than an upper threshold for the curl time; and decreasing the first temperature set point of the heating assembly if the curl time is less than a lower threshold for the curl time.

59. The method of claim 56, wherein determining the second temperature set point of the heating assembly based on the comparison of the curl profile and the desired curl profile comprises: increasing the first temperature set point of the heating assembly if the curl temperature is less than a lower threshold for the curl temperature; and decreasing the first temperature set point of the heating assembly if the curl temperature is greater than an upper threshold for the curl temperature.