Patent Description:
A practical example of a styling device is an automatic hair curler. In this respect, it is noted that <CIT> 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 <NUM> seconds before the internal temperature sensor reacts to the sudden temperature drop due to hair loading, and it may take more than <NUM> 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 <NUM>, for example. From <CIT>, a styling device according to the preamble of claim <NUM> is known.

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.

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 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., <NUM> 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 <NUM>%, an example of a percentage which may be chosen at a higher temperature level is <NUM>%, and an example of a percentage which may be chosen at a lower temperature level is <NUM>%.

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:.

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 <NUM>, 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:.

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.

<FIG> shows an automatic hair curler <NUM> which is designed to be used for performing a curling action on hair, and which comprises the following components:.

The hair curler <NUM> is an example of a styling device according to the invention, wherein the barrel element <NUM> functions as a functional unit and the combination of the heater <NUM> and the adapter <NUM> is a practical embodiment of a heating arrangement configured to heat the functional unit. A view of the portion of the hair curler <NUM> which is located on top of the handle <NUM> is provided by <FIG>, whereas in <FIG>, the heater <NUM>, the adapter <NUM> and the temperature sensor <NUM> as located inside the barrel element <NUM> can be seen. In <FIG>, the motor <NUM> of the hair winder component <NUM> and the microprocessor <NUM> are represented by dashed rectangles.

Because it is expected that a hair tress is inserted in the notch <NUM> of the housing <NUM> when the start winding button <NUM> 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 <NUM>, an amount of heat loss can be predicted. The microprocessor <NUM> is programmed to operate the heater <NUM> 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 <NUM> is programmed to feedforward control the temperature of the barrel element <NUM> upon initial depression of the start winding button <NUM>. In terms of a temperature control algorithm to be applied by the microprocessor <NUM> after the heater <NUM> has been operated to initially heat up the barrel element <NUM> 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 <NUM> at a percentage of its full power, which feedforward control procedure is initiated when the user depresses the start winding button <NUM>. Executing the feedforward control procedure results in immediate compensation of the heat loss resulting from contact of the hair to the barrel element <NUM>. The percentage is chosen in relation to the predicted amount of heat loss, so that the resulting temperature of the barrel element <NUM> is well in or at least close to the operational range of temperatures. In the present example, the user interface <NUM> includes a button <NUM> 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 <NUM> is directly related to said temperature setting.

In view of the foregoing, the hair curler <NUM> is operated as follows. An initial position of the hair winder component <NUM> is such that the notch <NUM> is free to receive a hair tress. The user holds the handle <NUM> of the hair curler <NUM> in one hand, inserts a hair tress through the notch <NUM> with the other hand, and depresses the start winding button <NUM> with a finger of the first hand to start a hair curling action. The hair winder component <NUM> will start rotating around the barrel element <NUM> for a defined number of revolutions and thereby force the length of the hair to wind around the barrel element <NUM>. Once the start winding button <NUM> is depressed, the microprocessor <NUM> 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 <NUM>. In the present example, this can be done by checking the actual temperature at the temperature sensor <NUM>. 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 <NUM> higher than the temperature setting, for example, the heater <NUM> is powered with a percentage of its full power during a period of time, such as with <NUM>% of its full power for <NUM> 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 <NUM>.

Information about an amount of heat loss following from an introduction of a hair tress to the outer surface of the barrel element <NUM> is determined during tests which are performed during the development stage of the hair curler <NUM>, and the programming of the microprocessor <NUM> 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 <NUM> of the hair curler <NUM> 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 <NUM>, and to perform the following sequence of steps for different temperature settings:.

In this way, it can be seen how the temperature at the outer surface of the barrel element <NUM> develops over time. This information is useful in a process of determining the particulars of the feedforward control procedure and programming the microprocessor <NUM> 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 <NUM> depressed throughout the entire hair curling action. The hair curler <NUM> is equipped with a unit configured to signal the user (not shown), which unit is controlled by the microprocessor <NUM> on the basis of a timer functionality. In particular, the microprocessor <NUM> is configured to activate the unit when a certain amount of time has passed after the start winding button <NUM> is initially depressed, e.g., <NUM> seconds, so that the user may know when the hair curling action is completed and the start winding button <NUM> 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 <NUM> includes a button <NUM> 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 <NUM>.

In the present example, besides the hair winding button <NUM>, the temperature setting button <NUM> and the time setting button <NUM>, the user interface <NUM> includes a button <NUM> by means of which the user can set the direction of rotation of the hair winder component <NUM>.

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 <NUM> is applied. This may be done in any suitable way. In the present example, this involves use of the built-in temperature sensor <NUM> by the microprocessor <NUM> to monitor the temperature of the barrel element <NUM> and to control the power of the heater <NUM> to keep the temperature of the barrel element <NUM> to be around the temperature setting. This feedback control of the heater <NUM> can put the hair curler <NUM> in an idling state until the start winding button <NUM> is depressed again, which will trigger the feedforward control again. If the start winding button <NUM> 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 <NUM> being depressed is when it follows from the safety check described earlier that the actual temperature of the barrel element <NUM> 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 <NUM> is set to be lower, and when a lower temperature setting is selected, the power of the heater <NUM> is set to be higher. For example, a default percentage of full power of the heater <NUM> is <NUM>%, a lower percentage of full power of the heater <NUM> is <NUM>%, and a higher percentage of full power of the heater <NUM> is <NUM>%. The duration of the feedforward control procedure can be the same under all circumstances, wherein <NUM> 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 drawings are schematic, wherein details which are not required for understanding the invention may have been omitted, and not necessarily to scale.

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".

Claim 1:
A styling device (<NUM>) comprising a functional unit (<NUM>) configured to perform a styling action on an item to be styled during use of the styling device (<NUM>), and further comprising a heating arrangement (<NUM>, <NUM>) configured to heat the functional unit (<NUM>), and a processor (<NUM>) configured to control operation of the styling device (<NUM>), wherein:
- the processor (<NUM>) is configured to apply a temperature control algorithm after the heating arrangement (<NUM>, <NUM>) has been operated to initially heat up the functional unit (<NUM>) to a temperature in an operational range of temperatures, the temperature control algorithm being designed to operate the heating arrangement (<NUM>, <NUM>) to keep the temperature of the functional unit (<NUM>) in the operational range of temperatures,
- the temperature control algorithm includes a feedforward control procedure involving an action of operating the heating arrangement (<NUM>, <NUM>) at a percentage of its full power,
- the temperature control algorithm is configured to initiate the feedforward control procedure when the processor (<NUM>) receives input indicating that a styling action is to be performed, characterized in that
- 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.