FIELD OF THE INVENTION

The invention relates to a styling device comprising a functional unit configured to perform a styling action on an item to be styled during use of the styling device, and further comprising a heating arrangement configured to heat the functional unit, and a processor configured to control operation of the styling device, wherein the processor is configured to apply a temperature control algorithm after the heating arrangement has been operated to initially heat up the functional unit to a temperature in an operational range of temperatures, the temperature control algorithm being designed to operate the heating arrangement to keep the temperature of the functional unit in the operational range of temperatures.

BACKGROUND OF THE INVENTION

A practical example of a styling device is an automatic hair curler. In this respect, it is noted that WO 2017/029382 Al discloses an automatic hair curler comprising a handle, a housing, a barrel element, a heater to heat the barrel element, a hair winder component rotatable around the barrel element, a driving device to drive the hair winder component, and a hair curling cavity having an opening at an upper end being formed between an inner surface of the hair winder component and an outer surface of the barrel element. An upper end of the housing has a notch which extends downwardly from a top end face of the housing, and which communicates with the opening of the hair curling cavity. Further, hair wrapping portions are provided on the hair winder component to wrap the hair around the barrel element when the hair winder component is rotating. In operation, hair is placed in the notch provided in the housing and can enter the hair curling cavity from the notch, and hair can be wrapped around the barrel element when the hair winder component rotates so that an automatic curling can be realized.

Conventionally, an automatic hair curler relies on an internal temperature sensor and a microprocessor to control the temperature of the barrel element. However, once a hair tress is loaded around the barrel element, the temperature of the barrel element will drop significantly, and it will take some time before the internal temperature sensor detects the temperature drop and signals the microprocessor to compensate for the heat loss by powering up the heater which serves to heat the barrel element. During this period, the hair tress is exposed to less heat than desired, and as a consequence, it will take longer before the desired styling effect of the hair tress is reached. In practical cases, it may take more than 7 seconds before the internal temperature sensor reacts to the sudden temperature drop due to hair loading, and it may take more than 3 seconds after the heater is powered up before the heat is transferred onto the outer surface of the barrel element. Therefore, from the moment that a hair tress is wound around the barrel element and a curling cycle is initiated, the hair tress will be subjected to less and less heat in a first instance, and a person using the hair curler, who will hereinafter be referred to as user, needs to wait for a significantly longer time as compared to a theoretical case in which the temperature of the barrel element is continuously at an operational level as envisaged, and/or needs to increase the temperature setting in order to obtain the desired styling effect. The temperature drop referred to may be as large as 10°C, for example.

It is an object of the invention to provide a way of barrel element temperature control whereby it is possible to prevent a situation in which an increase of the duration of the hair curling action and/or the temperature setting relative to the theoretical value(s) is necessary in order to achieve the desired curling effect. More generally speaking, it is an object of the invention to provide a way of operating the heating arrangement of a styling device such that the extent to which effectiveness of a styling action can be reduced due to initial contact or proximity of the item to be styled to the functional unit is lessened.

SUMMARY OF THE INVENTION

The invention provides a styling device comprising a functional unit configured to perform a styling action on an item to be styled during use of the styling device, and further comprising a heating arrangement configured to heat the functional unit, and a processor configured to control operation of the styling device, wherein:

- the processor is configured to apply a temperature control algorithm after the heating arrangement has been operated to initially heat up the functional unit to a temperature in an operational range of temperatures, the temperature control algorithm being designed to operate the heating arrangement to keep the temperature of the functional unit in the operational range of temperatures,

- the temperature control algorithm includes a feedforward control procedure involving an action of operating the heating arrangement at a percentage of its full power, and

- the temperature control algorithm is configured to initiate the feedforward control procedure when the processor receives input indicating that a styling action is to be performed.

The invention introduces a feedforward control procedure to compensate for expected heat loss on the functional unit of a styling device, triggered by input indicating that a styling action is to be performed. The processor of the styling device, which may be a microprocessor in practical cases, is configured to use such input to start powering up the heating arrangement at an appropriate level of power. In this process, different from what is known in the art, there is no need to wait for a temperature sensor to react to an initial temperature drop at the functional unit. Instead, the heating arrangement is automatically operated such that a temperature of the functional unit is put to a level that is sufficiently high to compensate for heat loss resulting from initial contact or proximity of the item to be styled to the functional unit, so that effectiveness of the styling action is preserved by realizing a more steady styling temperature, and both the duration of the styling action and the temperature of the functional unit can be kept within acceptable limits. In the context of the invention, the appropriate level of power at which the heating arrangement is operated in the feedforward control procedure is a percentage of its full power, which may be a fixed percentage of its full power throughout the entire time that the feedforward control procedure is executed. Advantageously, the percentage is chosen in relation to factors including an expected value of the initial temperature drop, the operational range of temperatures, and the time that is available to operate the heating arrangement in this anticipatory fashion.

A hair curler as described in the foregoing normally comprises a start winding button which is to be depressed by a user at the moment that a hair tress has been properly placed in the notch provided in the housing and it is intended to initiate a hair curling action, and which is to be kept depressed throughout the hair curling action. When the invention is applied in the context of the hair curler, the event of the processor receiving input indicating that a styling action is to be performed is initiated as soon as the user depresses the start winding button. At that point, without waiting for input from the internal temperature sensor, the feedforward control procedure is initiated, as a result of which the barrel element is heated by the heating arrangement at higher power than in conventional cases, namely at a percentage of full power of the heating arrangement. As a result, the temperature of the barrel element is put to such a level that the temperature drop resulting from contact of the hair to the barrel element does not cause the temperature to get so low that the hair curling action is significantly hampered, so that the hair tress to be curled can be exposed to heat more closely related to the temperature setting specified by the user. In that way, in comparison to the conventional situation, it is achieved that the time that a hair tress needs to be kept in the hair curler for obtaining the desired styling result is shortened, and that the user does not get anxious about the styling result and does not feel the need to set a higher temperature.

It is practical if the temperature control algorithm is configured to terminate the feedforward control procedure when an operational time period after initiation of the feedforward control procedure has expired, or earlier when the input indicating that a styling action is to be performed is removed before that time. For example, when the styling device according to the invention is a hair curler as suggested earlier, it may be so that the feedforward control procedure is terminated after a number of seconds from the start, e.g., 6 seconds, or earlier when the user releases the start winding button. In respect of the latter possible criterion, it is possible to have a delay period so that the feedforward control procedure is only terminated when the start winding button remains released during such a delay period.

It may be advantageous if the level of power at which the heating arrangement is operated is adapted to the level of the operational range of temperatures of the functional unit. In other words, it may be advantageous if the temperature control algorithm is configured to determine the percentage of full power of the heating arrangement in dependence on a level of the operational range of temperatures of the functional unit. In this respect, it is especially preferred if the temperature control algorithm is configured to apply a relation between the percentage of full power of the heating arrangement and the level of the operational range of temperatures of the functional unit according to which the percentage decreases as the level of the operational range of temperatures increases, so that a lower percentage of full power is chosen when the temperature of the functional unit needs to be higher and problems of overheating are avoided under all circumstances, and the percentage increases as the level of the operational range of temperatures decreases. An example of a default percentage is 80%, an example of a percentage which may be chosen at a higher temperature level is 70%, and an example of a percentage which may be chosen at a lower temperature level is 90%.

In the foregoing, the practical possibility of a hair curler comprising a start winding button is addressed, wherein it is indicated that the start winding button is to be kept depressed throughout a hair curling action. Generally speaking, in a practical embodiment, the styling device comprises a user interface configured to enable a user to provide the processor with input, including the input indicating that a styling action is to be performed, wherein it may be so that the user interface is configured to provide the processor with the input indicating that a styling action is to be performed as long as the user interacts with the user interface.

In order to guarantee safety of use of the styling device according to the invention, it is proposed to let the action of operating the heating arrangement at a percentage of its full power be a conditional action, in which case it may be practical if the processor is configured to determine, e.g., via a suitable sensor, that despite the processor being provided with input indicating that a styling action is to be performed, an item to be styled is absent, and to prevent initiation of the action of operating the heating arrangement at a percentage of its full power if that is found to be true, indeed. The conditional action may also be implemented in the following manner:

- the feedforward control procedure further involves a preceding action of obtaining a value which is representative of an actual temperature of the functional unit and determining whether the value is inside or outside of a safety range of values, and

- the temperature control algorithm is configured to only initiate the action of operating the heating arrangement at a percentage of its full power when during the preceding action the value is found to be inside of the safety range of values.

Thus, it is proposed to check the actual temperature of the functional unit in order to decide whether it is safe to initiate the action of operating the heating arrangement at a percentage of its full power. In this way, a potential overheating risk involved in feedforward control is eliminated. In this context, it may be practical if the styling device comprises a temperature sensing arrangement, and if the temperature control algorithm is configured to operate the temperature sensing arrangement to provide the value which is representative of an actual temperature of the functional unit. In the case of the styling device being an auto curler, the internal temperature sensor of the auto curler may be used in the process of performing the safety check. Without the safety check, there is especially a risk of overheating if the user depresses the start winding button in a situation that there is no hair present in the housing of the auto curler. In respect of the safety range of values, it is noted that this range may include the operational range of temperatures plus all lower temperatures plus higher temperatures in a limited additional range, such as an additional range of 5°C, which does not alter the fact that the invention covers other options as well.

Optionally, the temperature control algorithm includes a feedback control procedure besides the feedforward control procedure defined and explained in the foregoing, as follows:

- the temperature control algorithm further includes a feedback control procedure involving an action of monitoring a value which is representative of an actual temperature of the functional unit, determining whether the value is in, below or above an operational range of values, and operating the heating arrangement as long as the value is found to be below the operational range of values, and

- the temperature control algorithm is configured to execute the feedback control procedure as a default, to initiate the feedback control procedure when the feedforward control procedure is terminated, and to terminate the feedback control procedure when the feedforward control procedure is initiated.

In this way, it is achieved that when the temperature control algorithm is applied, a conventional way of maintaining the temperature of the functional unit is realized outside of the times that the feedforward control procedure is executed, which conventional way relies on monitoring a value which is representative of an actual temperature of the functional unit and operating the heating arrangement as long as the value is found to be below the operational range of values.

In practical cases, the styling device according to the invention comprises a unit configured to provide a warning signal to a person, wherein the processor is configured to activate the unit when a time period during which the input indicating that a styling action is to be performed is received exceeds a maximum. In this way, a situation in which the item to be styled is subjected to the styling action for a period of time which is longer than necessary is avoided, which is especially advantageous if the styling action is of such a nature that eventually harm is done to the item to be styled when the styling action is continued after a safe time period has passed. In any case, having the warning functionality adds to ease of use of the styling device and contributes to the user’s perception of quality and reliability of the styling device.

The invention covers numerous types of styling devices, including a hair-styling device in which the functional unit is configured to perform a styling action on at least a portion of a person’s hair. As suggested earlier, the styling device according to the invention may particularly be an automatic hair curler comprising a rotatable hair winder component configured to engage on a hair tress, wherein the functional unit comprises a barrel element encompassed by the hair winder component. In the context of such a hair curler, it is a practical possibility that the input indicating that a styling action is to be performed is generated when the hair winder component is activated to rotate.

The above-described and other aspects of the invention will be apparent from and elucidated with reference to the following detailed description of an automatic hair curler comprising a barrel element around which a hair tress is to be wound, a heater to heat the barrel element, and a microprocessor which is programmed to control the temperature of the heater in such a way that a temperature-reducing effect of contact of a hair tress to be curled to the barrel element is anticipated, which helps in keeping the temperature of the barrel element in an operational range of temperatures so that an effective hair curling action can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in greater detail with reference to the figures, in which equal or similar parts are indicated by the same reference signs, and in which:

Fig. 1 diagrammatically shows a perspective view of an automatic hair curler according to an embodiment of the invention;

Fig. 2 diagrammatically shows a perspective view of a portion of the hair curler; and

Fig. 3 diagrammatically shows a perspective view of a barrel element of the hair curler, with a top cover removed so that the interior of the barrel element can be seen.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 shows an automatic hair curler 100 which is designed to be used for performing a curling action on hair, and which comprises the following components:

- a handle 10 for enabling a user to hold the hair curler 100 in her/his hand;

- a housing 20 having a hair tress supporting surface 21 for the root of a hair tress to sit on and a notch 22 constituting a hair tress inlet for the tip of a hair tress to be retracted into the housing 20;

- a hair winder component 30 for retracting a hair tress into the housing 20;

- a motor 31 configured to rotate the hair winder component 30 about a rotation axis R extending in longitudinal direction;

- a barrel element 40 which is generally shaped like a hollow cylinder having a circular periphery and which is thereby suitable for a hair tress to wind around;

- a microprocessor 50 mounted on a circuit board which is installed inside the handle 10;

- a heater 60 configured to heat the barrel element 40, which is arranged to be controlled by the microprocessor 50, and which is mounted on an adapter 61 arranged to contact an inner surface of the barrel element 40 to thereby realize conductive heat transfer from the heater 60 to the barrel element 40;

- a user interface 70 in the handle 10, including a start winding button 71 for the user to signal the motor 31 of the hair winder component 30 through the microprocessor 50 to start winding a hair tress into the housing 20 and around the barrel element 40 by rotating the hair winder component 30; and

- a temperature sensor 80 mounted inside the barrel element 40 to provide a temperature signal for the microprocessor 50 to feedback control the temperature of the barrel element 40 by operating the heater 60.

The hair curler 100 is an example of a styling device according to the invention, wherein the barrel element 40 functions as a functional unit and the combination of the heater 60 and the adapter 61 is a practical embodiment of a heating arrangement configured to heat the functional unit. A view of the portion of the hair curler 100 which is located on top of the handle 10 is provided by Fig. 2, whereas in Fig. 3, the heater 60, the adapter 61 and the temperature sensor 80 as located inside the barrel element 40 can be seen. In Fig. 1, the motor 31 of the hair winder component 30 and the microprocessor 50 are represented by dashed rectangles.

Because it is expected that a hair tress is inserted in the notch 22 of the housing 20 when the start winding button 71 is depressed by the user, and that in the seconds following such action by the user, a predictable hair loading will be introduced to an outer surface of the barrel element 40, an amount of heat loss can be predicted. The microprocessor 50 is programmed to operate the heater 60 in such a way that a situation in which said amount of heat loss drastically reduces effectiveness of the hair curling action, at least during the first seconds of said action, is avoided. In particular, the microprocessor 50 is programmed to feedforward control the temperature of the barrel element 40 upon initial depression of the start winding button 71. In terms of a temperature control algorithm to be applied by the microprocessor 50 after the heater 60 has been operated to initially heat up the barrel element 40 to a temperature in an operational range of temperatures, the fact is that the temperature control algorithm includes a feedforward control procedure involving an action of operating the heater 60 at a percentage of its full power, which feedforward control procedure is initiated when the user depresses the start winding button 71. Executing the feedforward control procedure results in immediate compensation of the heat loss resulting from contact of the hair to the barrel element 40. The percentage is chosen in relation to the predicted amount of heat loss, so that the resulting temperature of the barrel element 40 is well in or at least close to the operational range of temperatures. In the present example, the user interface 70 includes a button 72 for enabling the user to choose a temperature setting of the hair curling action, wherein it is to be noted that the operational range of temperatures as applied to the temperature of the barrel element 40 is directly related to said temperature setting.

In view of the foregoing, the hair curler 100 is operated as follows. An initial position of the hair winder component 30 is such that the notch 22 is free to receive a hair tress. The user holds the handle 10 of the hair curler 100 in one hand, inserts a hair tress through the notch 22 with the other hand, and depresses the start winding button 71 with a finger of the first hand to start a hair curling action. The hair winder component 30 will start rotating around the barrel element 40 for a defined number of revolutions and thereby force the length of the hair to wind around the barrel element 40. Once the start winding button 71 is depressed, the microprocessor 50 will be signaled to trigger the feedforward control procedure of the temperature control algorithm. It is practical if the feedforward control procedure starts with checking the loading of hair in the hair curler 100. In the present example, this can be done by checking the actual temperature at the temperature sensor 80. In that case, only if said temperature is within a safety range, which may be a range of temperatures including temperatures below the temperature setting and temperatures up to 5°C higher than the temperature setting, for example, the heater 60 is powered with a percentage of its full power during a period of time, such as with 80% of its full power for 6 seconds. The heat generated in this way is sufficient to compensate for the predicted heat loss due to the loading introduced by the hair tress onto the barrel element 40. Information about an amount of heat loss following from an introduction of a hair tress to the outer surface of the barrel element 40 is determined during tests which are performed during the development stage of the hair curler 100, and the programming of the microprocessor 50 is designed on the basis of the outcome of such tests. For example, a test barrel element which is similar to the actual barrel element 40 of the hair curler 100 is equipped with a number of thermocouples, e.g., three thermocouples, and a data logger is connected to the thermocouples, so that it is possible to accurately monitor the temperature at the outer surface of the barrel element 40, and to perform the following sequence of steps for different temperature settings:

- heat up the test barrel element until a steady state temperature according to the temperature setting is reached,

- activate the data logger to record the temperature from the thermocouples,

- wrap a hair tress around the test barrel element,

- keep the hair tress on the test barrel element for a limited time period such as a time period of 10 seconds,

- unload the hair tress and complete the test.

In this way, it can be seen how the temperature at the outer surface of the barrel element 40 develops over time. This information is useful in a process of determining the particulars of the feedforward control procedure and programming the microprocessor 50 accordingly. Advantageously, accuracy of the outcome of the tests is increased by repeating each of the different tests a number of times and averaging the values found during the repeated tests.

The user keeps the start winding button 71 depressed throughout the entire hair curling action. The hair curler 100 is equipped with a unit configured to signal the user (not shown), which unit is controlled by the microprocessor 50 on the basis of a timer functionality. In particular, the microprocessor 50 is configured to activate the unit when a certain amount of time has passed after the start winding button 71 is initially depressed, e.g., 8 seconds, so that the user may know when the hair curling action is completed and the start winding button 71 can be released. The signal can be in a beeping sound format from a built-in speaker, or in a vibration feedback format generated from a built-in haptic motor, or in a visual format such as blinking light. In the present example, the user interface 70 includes a button 73 for enabling the user to choose a time duration of the hair curling action and to thereby set the moment at which the unit is activated. When the hair curling action is terminated, the user is supposed to remove the curled hair tress from the hair curler 100.

In the present example, besides the hair winding button 71, the temperature setting button 72 and the time setting button 73, the user interface 70 includes a button 74 by means of which the user can set the direction of rotation of the hair winder component 30.

The duration of the feedforward control procedure can normally be shorter than the duration of the hair curling action. Once the feedforward control procedure is completed, conventional feedback control of the temperature of the barrel element 40 is applied. This may be done in any suitable way. In the present example, this involves use of the built-in temperature sensor 80 by the microprocessor 50 to monitor the temperature of the barrel element 40 and to control the power of the heater 60 to keep the temperature of the barrel element 40 to be around the temperature setting. This feedback control of the heater 60 can put the hair curler 100 in an idling state until the start winding button 71 is depressed again, which will trigger the feedforward control again. If the start winding button 71 is released before the complete time period of the feedforward control procedure has passed, the feedforward control procedure is aborted and the feedback control procedure is initiated at that point. An occasion at which the feedback control procedure is continued despite of the start winding button 71 being depressed is when it follows from the safety check described earlier that the actual temperature of the barrel element 40 is outside of the safety range.

According to a sophisticated possibility, the feedforward procedure is unique for each setting, wherein when a higher temperature setting is selected, the power of the heater 60 is set to be lower, and when a lower temperature setting is selected, the power of the heater 60 is set to be higher. For example, a default percentage of full power of the heater 60 is 80%, a lower percentage of full power of the heater 60 is 70%, and a higher percentage of full power of the heater 60 is 90%. The duration of the feedforward control procedure can be the same under all circumstances, wherein 6 seconds may be a practical example, as suggested earlier.

It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, and that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. It is intended that the invention be construed as including all such amendments and modifications insofar they come within the scope of the claims or the equivalents thereof. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The invention is not limited to the disclosed embodiments. The drawings are schematic, wherein details which are not required for understanding the invention may have been omitted, and not necessarily to scale.

Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached claims. In the claims, the word “comprising” does not exclude other steps or elements, and the indefinite article “a” or “an” does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Elements and aspects discussed for or in relation with a particular embodiment may be suitably combined with elements and aspects of other embodiments, unless explicitly stated otherwise. Thus, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The terms “comprise” and “include” as used in the present text will be understood by a person skilled in the art as covering the term “consist of’. Hence, the term “comprise” or “include” may in respect of an embodiment mean “consist of’, but may in another embodiment mean “contain/have/be equipped with at least the defined species and optionally one or more other species”.

Notable aspects of the invention are summarized as follows. In the field of performing a styling action on an item to be styled, a styling device such as a hair curler 100 is provided which is of the type comprising a functional unit 40, a heating arrangement 60, 61 configured to heat the functional unit 40, and a processor 50 configured to control operation of the styling device. A temperature control algorithm as applied by the processor 50 after the heating arrangement 60, 61 has been operated to initially heat up the functional unit 40 to a temperature in an operational range of temperatures includes a feedforward control procedure involving an action of operating the heating arrangement 60, 61 at a percentage of its full power, which is beneficial to effectiveness of the styling action as this helps to prevent the temperature of the functional unit 40 from initially dropping to a level which is significantly lower than envisaged as a result of initial contact or proximity of the item to be styled to the functional unit 40. All that the controller 50 needs to trigger the feedforward control procedure is receipt of input indicating that a styling action is to be performed, and throughout the action of operating the heating arrangement 60, 61 at a percentage of its full power, there is no need for input about an actual temperature of the functional unit 40.