WO2022229597A1

WO2022229597A1 - Haircare appliance

Info

Publication number: WO2022229597A1
Application number: PCT/GB2022/050979
Authority: WO
Inventors: Yuen LEOW; Weifu YU; Clement TAN; Xinyi Li; Gaudencio TEVES III; Stephen WOOLAGHAN; Kishan AMRATIA; Jack Thompson; Brian Weeks; Teng Lee KHOO
Original assignee: Dyson Technology Limited
Priority date: 2021-04-30
Filing date: 2022-04-19
Publication date: 2022-11-03
Also published as: GB202106250D0; US20240237800A1; CN117241698A; GB2606227A; GB2606227B

Abstract

A haircare appliance includes a pressure sensor for generating a pressure signal indicative of air pressure within an airflow path, the pressure sensor being upstream of an airflow generator. A controller is configured to estimate, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked. When the estimated blockage factor exceeds a blockage warning threshold, a warning indicative of a partial blockage is output. When the estimated blockage factor exceeds a critical threshold, the critical threshold being higher than the blockage warning threshold, a power output of at least one component of the haircare appliance is turned off or reduced.

Description

HAIRCARE APPLIANCE

FIELD OF INVENTION

The present invention relates to a haircare appliance.

BACKGROUND

Haircare appliances are generally used to treat or style hair, and some haircare appliances may treat or style hair using airflow along with heat. Such haircare appliances are typically held by a user and moved relative to the hair to obtain desired treatment or styling.

SUMMARY OF INVENTION

According to a first aspect, there is provided a haircare appliance comprising an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path, the pressure sensor being upstream of the airflow generator. The haircare appliance also comprises a controller configured to: receive the pressure signal; estimate, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked; when the estimated blockage factor exceeds a blockage warning threshold, output a warning indicative of a partial blockage; and when the estimated blockage factor exceeds a critical threshold, the critical threshold being higher than the blockage warning threshold, turn off or reduce a power output of at least one component of the haircare appliance.

The use of such thresholds may allow for a safer haircare appliance and/or an improved user experience.

The haircare appliance may include an air filter for filtering air entering the airflow path, the amount by which the airflow path is blocked at least partly comprising an amount by which the filter is blocked.

The controller may be configured to: based on the pressure signal, determine an ambient air pressure prior to the airflow generator reaching an operating speed; based on the pressure signal, determine a dynamic air pressure after the airflow generator reaches the operating speed; and estimate the blockage factor at least partly based on a difference between the ambient pressure and the dynamic air pressure. For example, controller may be configured to determine the ambient air pressure prior to a drive signal being supplied to the airflow generator. This may improve reliability of blockage factor estimation.

The haircare appliance may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path; and the controller may be configured to: receive information indicative of a currently selected setting; and estimate the blockage factor at least partly based on the received information indicative of a currently selected setting. This may improve accuracy of blockage factor estimation.

Turning off or reducing a power output of at least one component of the haircare appliance may comprise turning off or reducing a power output of the airflow generator, which may improve safety and/or reliability of the appliance.

The haircare appliance may include an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in characteristic of the airflow as it exits the airflow path, wherein the controller is configured to estimate the blockage factor at least partly taking into account an impact of the change in airflow characteristic caused when the airflow accessory is attached. This may improve accuracy of blockage factor estimation where such an accessory may be in use.

The controller may be configured to: identify an airflow accessory that is attached; and determine, based the identified airflow accessory, a correction factor for use in estimating the blockage factor. For example, the controller may be configured to look up, in a memory, the correction factor, based on the identified accessory. This may improve accuracy of blockage factor estimation where such an accessory may be in use.

The haircare appliance may comprise a sensor for identifying the airflow accessory that is attached.

The correction factor may be stored by the accessory, and the controller may be configured to read the correction factor from the accessory.

According to a second aspect, there is provide a method comprising: generating a pressure signal indicative of air pressure within an airflow path of a haircare appliance upstream of an airflow generator; estimating, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked; when the estimated blockage factor exceeds a blockage warning threshold, outputting a warning indicative of a partial blockage; and when the estimated blockage factor exceeds a critical threshold, the critical threshold being higher than the blockage warning threshold, turning off or reducing a power output of at least one component of the haircare appliance.

The use of such thresholds may allow for a safer haircare appliance and an improved user experience.

The amount by which the airflow path is blocked may at least partly comprise an amount by which an air fdter in the airflow path is blocked.

The method may comprise: based on the pressure signal, determining an ambient air pressure prior to the airflow generator reaching an operating speed following startup; based on the pressure signal, determining a dynamic air pressure after the airflow generator reaches the operating speed; and estimating the blockage factor at least partly based on a difference between the ambient pressure and the dynamic air pressure. For example, the method may comprise determining the ambient air pressure prior to a drive signal being supplied to the airflow generator. This may improve reliability of blockage factor estimation.

The haircare appliance may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, and the method may comprise: receiving information indicative of a currently selected setting; and estimating the blockage factor at least partly based on the received information indicative of a currently selected setting. This may improve accuracy of blockage factor estimation.

The haircare appliance may include an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in characteristic of the airflow as it exits the airflow path, and the method may comprise estimating the blockage factor at least partly taking into account an impact of the change in airflow characteristic caused when the airflow accessory is attached. This may improve accuracy of blockage factor estimation where such an accessory may be in use.

The method may include identifying an airflow accessory that is attached; and determining, based the identified airflow accessory, a correction factor for use in estimating the blockage factor. For example, the method may comprise looking up, in a memory, the correction factor, based on the identified accessory.

The method may comprise using a sensor to identify the airflow accessory that is attached.

The correction factor may be stored by the accessory, and the method may include reading the correction factor from the accessory.

According to a third aspect, there is provided a haircare appliance comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path, the pressure sensor being upstream of the airflow generator. The haircare appliance comprises a controller configured to: receive the pressure signal; determine, based at least partly on the pressure signal, that the airflow generator is operating incorrectly to cause the air to move upstream; and upon determining that the airflow generator is operating incorrectly to cause the air to move upstream, stop the airflow generator.

Stopping the airflow generator in this manner may reduce the change of damage to the haircare appliance.

The controller may be configured to, after stopping the airflow generator upon determining that the airflow generator is operating incorrectly to cause the air to move upstream, restart the airflow generator. This may improve the user experience, because it is not necessary for the user to react to the airflow generator stopping.

The controller is configured to restart the airflow generator a predetermined time after stopping the airflow generator. The controller may optionally be configured to detect that the airflow generator has come to a complete stop before restarting the airflow generator. This may increase the chances of the airflow generator starting to rotate in the correct direction when it is restarted.

The controller may be configured to: based on the pressure signal, determine an ambient air pressure prior to the airflow generator reaching an operating speed following startup; based on the pressure signal, determine a dynamic air pressure after the airflow generator reaches the operating speed; and determine that the airflow generator is operating incorrectly to cause the air to move upstream at least partly based on a difference between the ambient pressure and the dynamic air pressure. This may provide a robust way of identifying that the airflow generator is operating incorrectly.

The controller may be configured to determine the ambient air pressure prior to a drive signal being supplied to the airflow generator. This may improve reliability of identifying that the airflow generator is operating incorrectly.

The haircare appliance may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path; and the controller may be configured to: receive information indicative of a currently selected setting; and determine that the airflow generator is operating incorrectly to cause the air to move upstream at least partly based on the received information. This may improve accuracy of identifying that the airflow generator is operating incorrectly.

According to a fourth aspect, there is provided a method comprising: generating a pressure signal indicative of air pressure within an airflow path of a haircare appliance upstream of an airflow generator; determining, based at least partly on the pressure signal, that the airflow generator is operating incorrectly to cause the air to move upstream; and upon determining that the airflow generator is operating incorrectly to cause the air to move upstream, stopping the airflow generator.

The method may comprise, after stopping the airflow generator upon determining that the airflow generator is operating incorrectly to cause the air to move upstream, restarting the airflow generator. This may improve the user experience, because it is not necessary for the user to react to the airflow generator stopping.

The method may comprise restarting the airflow generator a predetermined time after stopping the airflow generator. The method may optionally comprise detecting that the airflow generator has come to a complete stop before restarting the airflow generator. This may increase the chances of the airflow generator starting to rotate in the correct direction when it is restarted.

The method may comprise, based on the pressure signal, determining an ambient air pressure prior to the airflow generator reaching an operating speed following startup; based on the pressure signal, determining a dynamic air pressure after the airflow generator reaches the operating speed; and determining that the airflow generator is operating incorrectly to cause the air to move upstream at least partly based on a difference between the ambient pressure and the dynamic air pressure. This may provide a robust way of identifying that the airflow generator is operating incorrectly.

The method may comprise determining the ambient air pressure prior to a drive signal being supplied to the airflow generator. This may improve reliability of identifying that the airflow generator is operating incorrectly.

The haircare appliance may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, and the method may comprise: receiving information indicative of a currently selected setting; and determining that the airflow generator is operating incorrectly to cause the air to move upstream at least partly based on the received information.

According to a fifth aspect, there is provided a haircare device comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path, the pressure sensor being disposed upstream of the airflow generator. The haircare appliance comprises a controller configured to, while the airflow generator is active to move the air downstream through the airflow path: receive the pressure signal; identify, based at least partly on the pressure signal, a drop in air pressure within the airflow path; and determine, based at least partly on the identified drop in air pressure, that there is an at least partial blockage of an outlet of the airflow path. The controller is configured to, upon determining that there is an at least partial blockage of an outlet: turn off or reducing a power output of at least one component of the haircare device; or output a warning indicative of the at least partial blockage of the outlet.

Identifying a drop in pressure and turning off or reducing a power output, or outputting a warning, may allow for a safer haircare appliance and/or an improved user experience.

The controller may be configured to identify the drop in the air pressure based on at least one change in the air pressure signal over time. Allowing for a change in pressure signal over time, such as a threshold time, may help reduce the chance of transient air pressure changes causing undesirable behaviour.

The controller may be configured to: based on the pressure signal, determine an ambient air pressure prior to the airflow generator reaching an operating speed; based on the pressure signal, repeatedly determine a dynamic air pressure after the airflow generator reaches the operating speed; and identify the drop in air pressure based at least partly on a change in a difference between the ambient air pressure and the dynamic air pressure. This may improve reliability of partial blockage identification.

The controller may be configured to determine the ambient air pressure prior to a drive signal being supplied to the airflow generator. This may improve reliability of partial blockage identification.

The controller may be configured to: based on the pressure signal, determine a first dynamic air pressure while the airflow generator is at an operating speed; based on pressure signal, determine a second dynamic air pressure while the airflow generator is at the operating speed; and identify the drop in air pressure based at least partly on a difference between the first dynamic air pressure and the second dynamic air pressure. This may improve reliability of the partial blockage identification.

The haircare device may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path; and the controller may be configured to: receive information indicative of a currently selected setting; and determine, based at least partly on the information indicative of the currently selected setting, that there is the at least partial blockage of an outlet of the airflow path. This may improve reliability of the partial blockage identification. The haircare device may comprise an accessory capable of being removably atached at or adjacent to an outlet of the airflow path, atachment of the accessory causing a change in a characteristic of the airflow as it exits the airflow path, and the controller may be configured to: determine whether the accessory is atached; and determine, based at least partly on the determination of whether the accessory is atached, that there is the at least partial blockage of an outlet of the airflow path. This may improve reliability of the partial blockage identification when an accessory may be attached.

The haircare device may comprise a plurality of the accessories, and the controller may be configured to: determine which of the accessories is atached; determine, based at least partly on the determination of which of the accessories is atached, that there is the at least partial blockage of an outlet of the airflow path. This may improve reliability of the partial blockage identification depending upon which accessory is atached.

The haircare device may comprise a sensor for identifying which accessory is attached.

The controller may be configured to: determine, based at least partly on the identified drop in air pressure being present for at least a threshold period, that there is the at least partial blockage of an outlet of the airflow path. This may help reduce the chance of transient incidents causing undesirable behaviour.

Turning off or reducing a power output of at least one component of the haircare device may comprise turning off or reducing a power output of: the airflow generator; and/or at least one heating element of the haircare device, the at least one heating element being for heating air within the airflow path.

The controller may be configured to: initially output the warning indicative of the at least partial blockage of the outlet; subsequently turn off or reduce the power output of the at least one component of the haircare device in the event the outlet remains at least partly blocked following the warning.

According to a sixth aspect, there is provided a method performed by a haircare device, the method comprising: generating a pressure signal indicative of air pressure within an airflow path of the haircare device upstream of an airflow generator; identifying, based at least partly on the pressure signal, a drop in air pressure within the airflow path; and determining, based at least partly on the identified drop in air pressure, that there is an at least partial blockage of an outlet of the airflow path. The controller is configured to, upon determining that there is an at least partial blockage of an outlet: turn off or reduce a power output of at least one component of the haircare device; or output a warning indicative of the at least partial blockage of the outlet.

Identifying the drop in the air pressure may be based on determining at least one change in the air pressure signal overtime.

The method may comprise: based on the pressure signal, determining an ambient air pressure prior to the airflow generator reaching an operating speed; based on the pressure signal, repeatedly determining a dynamic air pressure after the airflow generator reaches the operating speed; and identifying the drop in air pressure based at least partly on a change in a difference between the ambient air pressure and the dynamic air pressure.

The method may comprise determining the ambient air pressure prior to a drive signal being supplied to the airflow generator.

The method may comprise: based on the pressure signal, determining a first dynamic air pressure while the airflow generator is at an operating speed; based on pressure signal, determining a second dynamic air pressure while the airflow generator is at the operating speed; and identifying the drop in air pressure based at least partly on a difference between the first dynamic air pressure and the second dynamic air pressure.

The haircare device may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, and the method may comprise: receiving information indicative of a currently selected setting; and determining, based at least partly on the information indicative of the currently selected setting, that there is the at least partial blockage of an outlet of the airflow path.

The haircare device may comprise an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in a characteristic of the airflow as it exits the airflow path, and the method may comprise: determining whether the accessory is attached; and determining, based at least partly on the determination of whether the accessory is attached, that there is the at least partial blockage of an outlet of the airflow path.

The haircare device may comprise a plurality of the accessories, and the method may comprise: determining which of the accessories is attached; determining, based at least partly on the determination of which of the accessories is attached, that there is the at least partial blockage of an outlet of the airflow path.

The method may comprise: determining, based at least partly on the identified drop in air pressure being present for at least a threshold period, that there is the at least partial blockage of an outlet of the airflow path.

The method may comprise: initially outputting the warning indicative of the at least partial blockage of the outlet; subsequently turning off or reducing the power output of the at least one component of the haircare device in the event the outlet remains at least partly blocked following the warning.

According to a seventh aspect, there is provided a haircare device comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path. The haircare appliance may comprise: an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in a characteristic of the airflow as it exits the airflow path; and a controller configured to: receive the pressure signal; identify, based at least partly on the pressure signal, a change in air pressure within the airflow path; and determine, based at least partly on the identified change in air pressure, that the accessory has been detached.

Determining that the accessory has been detached may allow for a safer haircare appliance and/or an improved user experience. The controller may be configured to identify the change in the air pressure based on at least one change in the air pressure signal over time. Allowing for a change in pressure signal over time, such as a threshold time, may help reduce the chance of transient air pressure changes causing undesirable behaviour.

The controller may be configured to: based on the pressure signal, determine an ambient air pressure prior to the airflow generator reaching an operating speed; based on the pressure signal, repeatedly determine a dynamic air pressure after the airflow generator reaches the operating speed; and identify the change in air pressure based at least partly on a change in a difference between the ambient air pressure and the dynamic air pressure. This may improve reliability of accessory detachment identification.

The controller may be configured to determine the ambient air pressure prior to a drive signal being supplied to the airflow generator. This may improve reliability of accessory detachment identification.

The controller may be configured to: based on the pressure signal, determine a first dynamic air pressure while the airflow generator is at an operating speed; based on pressure signal, determine a second dynamic air pressure while the airflow generator is at the operating speed; and identify the change in air pressure based at least partly on a difference between the first dynamic air pressure and the second dynamic air pressure. This may improve reliability of accessory detachment identification.

The haircare device may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path; and the controller may be configured to: receive information indicative of a currently selected setting; and determine, based at least partly on the information indicative of the currently selected setting, that the accessory has been detached. This may improve reliability of accessory detachment identification.

The haircare device may comprise a plurality of the accessories, and the controller may be configured to: determine which of the accessories is attached; and determine, based at least partly on the identified change in air pressure and which of the accessories was determined to be attached, that the accessory has been detached. This may improve reliability of accessory detachment identification. The haircare device may comprise a sensor for identifying which accessory is attached.

The controller may be configured to: determine, based at least partly on the identified change in air pressure being present for at least a threshold period, that the accessory has been detached. This may help reduce the chance of transient incidents causing undesirable behaviour.

The haircare device may include a sensor for sensing that an accessory has been attached, the controller being configured to: sense, using the sensor, that the accessory has been attached, prior to determining, based at least partly on the identified change in air pressure, that the accessory has been detached. This may allow for a safer haircare appliance and/or an improved user experience

The sensor may be for identifying which of a plurality of attachments has been attached.

The controller may be configured to: upon determining that the accessory has been detached: turn off, or adjust a power output of, at least one component of the haircare device; and/or output a warning indicating that accessory has been detached. This may allow for a safer haircare appliance and/or an improved user experience.

Turning off or reducing a power output of at least one component of the haircare device may comprise turning off or reducing a power output of: the airflow generator; and/or at least one heating element of the haircare device, the at least one heating element being for heating air within the airflow path. This may allow for a safer haircare appliance and/or an improved user experience.

The controller may be configured to: initially output the warning indicating that the accessory has been detached; subsequently turn off or reduce the power output of the at least one component of the haircare device in the event the accessory remains detached following the warning. This may allow for a safer haircare appliance and/or an improved user experience.

According to an eighth aspect, there is provided a method performed by a haircare device, the haircare device comprising an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in a characteristic of the airflow as it exits the airflow path the method comprising: generating a pressure signal indicative of air pressure within an airflow path of the haircare device upstream of an airflow generator; identifying, based at least partly on the pressure signal, a change in air pressure within the airflow path; determining, based at least partly on the identified change in air pressure, that the accessory has been detached.

The method may comprise identifying the change in the air pressure based on at least one change in the air pressure signal over time.

The method may comprise: based on the pressure signal, determining an ambient air pressure prior to the airflow generator reaching an operating speed; based on the pressure signal, repeatedly determining a dynamic air pressure after the airflow generator reaches the operating speed; and identifying the change in air pressure based at least partly on a change in a difference between the ambient air pressure and the dynamic air pressure.

The method may comprise: based on the pressure signal, determining a first dynamic air pressure while the airflow generator is at an operating speed; based on pressure signal, determining a second dynamic air pressure while the airflow generator is at the operating speed; and identifying the change in air pressure based at least partly on a difference between the first dynamic air pressure and the second dynamic air pressure.

The haircare device may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, and the method may comprise: receiving information indicative of a currently selected setting; and determining, based at least partly on the information indicative of the currently selected setting, that the accessory has been detached.

The method of any preceding claim, wherein the haircare appliance comprises a plurality of the accessories, and the method comprises: determining which of the accessories is attached; and determining, based at least partly on the identified change in air pressure and which of the accessories was determined to be attached, that the accessory has been detached.

The method may comprise determining, based at least partly on the identified change in air pressure being present for at least a threshold period, that the accessory has been detached. The method may comprise: sensing, using a sensor, that the accessory has been attached, prior to determining, based at least partly on the identified change in air pressure, that the accessory has been detached. The method may also comprise identifying, using the sensor, which of a plurality of accessories has been attached.

The method may comprise, upon determining that the accessory has been detached: turning off, or adjusting a power output of, at least one component of the haircare device; and/or outputting a warning indicating that the accessory has been detached.

According to a ninth aspect, there is provided a haircare device comprising an airflow path, the airflow path having disposed within it: a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path; an airflow generator for moving air downstream through the airflow path; a heater for heating the air; and a temperature sensor for generating a temperature signal indicative of a temperature of air heated by the heater. The haircare device includes a controller configured to receive at least the pressure signal and the temperature signal, and configured to: estimate, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked; calculate a temperature correction factor to apply to the temperature signal, based on at least the blockage factor.

This may allow more accurate tracking of temperature.

The haircare device may include an air filter for filtering air entering the airflow path, the amount by which the airflow path is blocked at least partly comprising an amount by which the filter is blocked.

The haircare device may comprise a selectable airflow speed setting that controls a rate at which the air generator moves air through the airflow path, wherein the controller is configured to calculate the temperature correction factor based on at least the selected airflow speed setting. This may allow more accurate tracking of temperature with changes in airflow. The airflow speed setting may be user- selectable.

The controller may be configured to apply the temperature correction factor to the temperature signal. The controller may be configured to apply the temperature correction factor to the temperature signal only when the blockage factor exceeds a threshold. This may allow more accurate tracking of temperature depending upon blockage factor.

The temperature correction factor may be determined based on a formula that includes as an input a variable based on an airflow speed. This may allow more accurate tracking of temperature depending upon airflow speed.

The temperature correction factor may be determined based on the following formula:

DT = a + b. B% + c.Qset where: DT is the temperature correction factor; B% is the blockage factor; Qset is an airflow speed setting, and a, b and c are coefficients determined empirically for the haircare device. This provides relatively accurate tracking of temperature depending based upon blockage factor.

According to a tenth aspect, there is provided a method of determining a temperature correction factor to apply to a temperature signal generated by a temperature sensor downstream of a heater within an airflow path of a haircare device, the temperature signal being indicative of a temperature of air heated by the heater, the method comprising: estimating, based at least partly on a pressure signal indicative of air pressure within the airflow path, a blockage factor corresponding to an amount by which the airflow path is blocked; and calculating a temperature correction factor to apply to the temperature signal, based on at least the blockage factor.

The amount by which the airflow path is blocked at least partly comprises an amount by which an air filter, for filtering air entering the airflow path, is blocked.

The haircare device may have a selectable airflow speed setting, and the method may comprise calculating the temperature correction factor based at least partly on a current selected airflow speed setting.

The method may comprise applying the temperature correction factor to the temperature signal, and may optionally comprise applying the temperature correction factor to the temperature signal only when the blockage factor exceeds a threshold. The method may comprise determining the temperature correction factor based on a formula that includes as an input a variable based on an airflow speed.

The method may comprise determining the temperature correction factor based on the following formula:

DT = a + b. B% + c.Qset where: DT is the temperature correction factor; B% is the blockage factor; Qset is an airflow speed setting, and a, b and c are coefficients determined empirically for the haircare device.

According to an eleventh aspect, there is provided a haircare appliance comprising a barometer chip for measuring air pressure, the barometer chip having a power supply input and an enable input, the power supply input and the enable input being electrically coupled to a signal line, such that a control signal appearing on the signal line both powers up and enables the barometer chip.

The haircare appliance may comprise a processor, the processor comprising an output pin electrically coupled to the signal line, the processor being configured to output the control signal via the output pin.

The barometer chip may be positioned to sense the air pressure within an airflow path of the haircare appliance.

Optional features of aspects of the present invention may be equally applied to other aspects of the present invention, where appropriate.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a perspective view of an embodiment of a haircare appliance;

Figure 2 is a schematic view illustrating internal components of the haircare appliance of Figure 1 ; Figure 3 is a schematic longitudinal section of a heater housing of the haircare appliance of Figures 1 and 2;

Figure 4 shows a method for processing a blockage of the haircare appliance of Figures 1-3; Figure 5 is a graph showing a relationship between pressures at normal and high restriction due to blockage, related to the method of Figure 4;

Figure 6 shows a method for controlling operation of an airflow generator forming part of the haircare appliance of Figures 1-3;

Figure 7 is a method for identifying a partial blockage based on a drop in pressure, performed by the haircare appliance of Figures 1-3;

Figure 8 is a method of determining whether an accessory is detached, performed by the haircare appliance of Figures 1-3;

Figure 9 is a graph showing a relationship between air exit temperature and a signal from a thermistor, related to the method of Figure 8;

Figure 10 is a method of calculating a temperature correction factor, performed by the haircare appliance of Figures 1-3; and

Figure 11 is a schematic view of a barometer connected to a processor.

DETAILED DESCRIPTION

A haircare appliance, generally designated 10, is shown schematically in Figures 1 and 2. The haircare appliance 10 in the embodiment of Figures 1 and 2 is a hairdryer, although it will be appreciated that some of the teachings discussed herein may be applied to other types of haircare appliance, for example hair straighteners or hair curlers or the like.

The haircare appliance 10 comprises a circuitry housing 12, a heater housing 14, and an electrical cable 16 extending from the circuitry housing 12 to the heater housing 14. The circuitry housing 12 defines an enclosure that houses a number of electronic components as will be described hereinafter, and the electronic components within the circuitry housing 12 are coupled to corresponding electronic components within the heater housing 14 by wires held within the electrical cable 16. Whilst referred to as wires, it will be appreciated that each wire may comprise more than one electrically conducting filament, for example as is the case with a braided wire, with the overall structure of multiple filaments being considered a wire. A power connector 15 in the form of a plug is coupled to the opposite side of the circuitry housing 12 to the electrical cable 16. The power connector 15 is configured to interact with an AC mains power supply, for example via a mains socket (not shown), to provide electrical current to the haircare appliance 10 in use. The heater housing 14 defines a hollow, generally elongate, handle that is intended to be grasped by a user in use. As seen in Figure 1, the heater housing 14 comprises a conical end portion 18 and a wall 20 extending upwardly from the conical end portion 18, such that a first end 22 of the heater housing 14 is generally cylindrical in form. The heater housing 14 has a second end 24 distal from the first end 22, and the heater housing 14 is curved such that the second end 24 is angled relative to the first end 22. An air inlet 26 is located at the first end 22 of the heater housing 14 on the wall 20, and takes the form of a plurality of apertures, for example in a mesh-like structure. An air outlet 28 is located at the second end 24, and comprises an aperture through which air may flow in use.

A user interface 30 is formed on the wall 20, and may take the form of a plurality of buttons, a touchscreen, or a combination thereof. User interface 30 allows a user to input various desired settings that are used by the other components of the haircare appliance 10 to control heat and fan settings, and may also provide visual and/or audible feedback, as described in more detail below.

A heater 32 and an airflow generator 34 are disposed within the heater housing 14.

Turning to Figure 2, the internal components and functional features of the haircare appliance 10 will be described in more detail. The skilled person will appreciate that the components and features are set out in schematic form, and that the relative positions and sizes of those components and features of the actual appliance may vary from what is illustrated in Figure 2.

Power connector 15 supplies, in use, AC mains power into circuitry housing 12. The AC mains power is supplied to a mains filter 36, which filters the AC mains power. Operation of the mains filter 36 is described in more detail below.

The AC output of the mains filter 36 is supplied to the input of an AC-to-DC converter 38. The AC- to-DC converter 38 converts the incoming AC voltage to DC, outputting various DC voltages as required by different components of the haircare appliance 10, as described in more detail below.

One output of the converter 38 is a DC power supply to a fan motor controller 40. Fan motor controller 40 receives control signals as described in more detail below, and outputs a fan motor drive signal to an electromagnetic compatibility (EMC) filter 42. The EMC filter 42 outputs the filtered fan motor drive signal to a fan motor 44. The EMC filter filters out harmonics generated by the fan motor 44, in use. The fan motor 44 forms part of the airflow generator 34, as described in more detail below.

Fan motor 44 may take the form of, for example, a V9 Dyson Digital Motor by Dyson Technology Limited. The V9 Dyson Digital Motor is a single-phase motor. Use of a single-phase motor may reduce the number of wires required to extend from circuitry housing 12 to heater housing 14 compared to, for example a similar arrangement where a three-phase motor is utilised by the airflow generator 34 within heater housing 14. Alternatively, a three-phase motor may be used to obtain a smaller and/or lighter heater housing 14.

The output of mains filter 36 also supplies the filtered AC mains power to heater housing 14 via electrical cable 16. Circuitry housing 12 also includes a relay 46, for selectively switching live circuit 47 of the AC mains power. Control of relay 46 is described in more detail below.

Several of the features and components of the haircare appliance 10 are implemented in a microcontroller unit (MCU) 48, as described in more detail below. The MCU 48 includes a processor, memory, and other components necessary to implement the features and components described herein. Although the example describes the use of a haircare appliance 10 having a single MCU 48 disposed within heater housing 14, it will be appreciated that the MCU 48 may be located within circuitry housing 12. Alternatively, implementation of the features and components of the haircare appliance 10 may be distributed across two or more processors, located within circuitry housing 12, heater housing 14, or both. Additional supporting circuitry, such as communications and power, are omitted for clarity. An example of a suitable MCU is the ARM Cortex-M0+.

User interface 30 allows a user to set a target temperature 50 and a fan speed 52. Target temperature 50 and fan speed 52 may each be selectable from a relatively small number of options (e.g., high, medium and low settings for each of target temperature 50 and fan speed 52). Alternatively, either or both of the target temperature 50 and fan speed 52 may be selected in a more granular way. For example, target temperature may be chosen as a specific temperature in degrees C or F, to a resolution of, say, 5, 10 or 20°. Similarly, fan speed 52 may be chosen as a specific airflow, such as in litres per second. Target temperature 50 and fan speed 52 are stored within MCU 48. They may be stored persistently or reset to default values at each start-up of the haircare appliance 10.

Fan speed 52 is provided as an input to fan motor controller 40 and to a control block 54 within MCU 48, and target temperature 50 is supplied to control block 54, as described in more detail below.

As described in more detail below in relation to Figure 3, heater housing 14 includes an air pressure sensor in the form of a barometer 58. Barometer 58 provides a raw pressure signal to pressure processing circuitry 60, which includes scaling and filtering circuitry that processes the raw pressure signal before outputting it as a pressure value. Such circuitry is well known to the skilled person and so will not be described in more detail. The pressure value is provided as an input to MCU 48, where it is used as described below. The pressure value may be, for example, the instantaneous pressure value based on the raw pressure signal from barometer 58. Alternatively, the pressure value may be low-pass filtered to reduce the impact of, for example, noise or spurious short-term pressure changes.

Barometer 58 can be configured to receive a power input from the power supply and an enable signal from MCU 48. The power input may be supplied separately from the enable signal.

However, there is an advantage in at least some implementations for the power input and enable signal to be tied together and connected to a pin of MCU that outputs a control signal. Optionally, a smoothing capacitor may be used. Since barometer 58 is in the airflow of haircare appliance 10, it may potentially be bumped by a foreign article entering the airflow path or affected by moisture. Connecting both the power supply and enable signal of the barometer 58 to an output pin of the MCU 48 reduces the possibility of other electronics components being affected by circuit damage caused by physical disruption to barometer 58. For example, when barometer 58 is not supplied with a separate power supply, it cannot cause a short of the power supply to 0V if it is damaged or affected by moisture.

In addition, MCU 48 may be configured to provide an error signal to a user in such a scenario, based on MCU 48 no longer receiving a signal from barometer 58.

As described in more detail below in relation to Figure 3, heater housing 14 includes an air exit temperature (AET) sensor 84. AET sensor 84 provides a raw temperature signal to AET processing circuitry 86, which includes scaling and filtering circuitry that processes the raw temperature signal before outputting it as a temperature value. Such circuitry is well known to the skilled person and so will not be described in more detail. The temperature value may be, for example, the instantaneous temperature value based on the raw signal from AET sensor 84. Alternatively, the temperature value may be low-pass fdtered to reduce the impact of, for example, noise or spurious short-term temperature changes.

The temperature value is provided as an input to an AET buffer 88, as described in more detail below. AET buffer 88 provides a buffered temperature value as an input to MCU 48, where it is used as described in more detail below.

Heater housing 14 includes a heater temperature sensor 90, positioned to sense a temperature of heater 32. Heater temperature sensor 90 provides a raw temperature signal to heater temperature processing circuitry 92, which includes scaling and filtering circuitry that processes the raw temperature signal before outputting it as a temperature value. Such circuitry is well known to the skilled person and so will not be described in more detail. The temperature value is provided as an input to a heater temperature buffer 94, as described in more detail below. Heater temperature buffer 94 provides a buffered temperature value as an input to MCU 48, where it is used as described in more detail below.

Pressure processing block 62 within control block 54 processes the pressure and temperatures value as described in more detail below, and outputs control information to a power controller 64 within control block 54. Target smoothing block 66 processes the target temperature 50 as described in more detail below, and outputs power target information to power controller 64. Based on the received control information and power target information, power controller 64 outputs a power control signal to a current controller 68.

The AC power supply provided from circuitry housing 12 to heater housing 14 via electrical cable 16 is supplied as an input to a voltage sensing circuit 70. Voltage sensing circuit 70 may comprise, for example, an analogue to digital converter for sampling a voltage of the AC power supply and converting it to a numerical value that can be used by MCU 48. The output voltage sensing circuit 70 is provided to an RMS voltage calculator 72, which determines an RMS voltage of the AC power supply, as described in more detail below. The calculated RMS voltage is provided as an input to current controller 68. The calculated RMS voltage is also provided as an input to a voltage check block 73. Voltage check block 73 determines whether the calculated RMS voltage is above a threshold (or, alternatively, below a threshold, or between two thresholds), and outputs a gate control signal to the converter 38, as described in more detail below.

Current controller 68 uses the RMS voltage and power control signal to determine a desired power output, which may be in the form of an instantaneous or average desired current, power, or combination thereof. The desired output is provided as an input to a TRIAC pattern calculator 74. TRIAC pattern calculator 74 uses the desired output to generate a suitable TRIAC drive pattern. For example, the TRIAC pattern calculator 74 may use a burst-fire control scheme, a phase angle control scheme, or a combination thereof, to generate a TRIAC drive pattern to control current flow to heater elements, as described in more detail below. The TRIAC drive pattern is provided as an input to TRIAC drive signal generator 76.

The AC power supply provided from circuitry housing 12 to heater housing 14 via electrical cable 16 is also supplied as an input to a zero-crossing detection circuit 78. The zero-crossing detection circuit 78 determines zero-crossing points of the AC power supply, as described in more detail below, and provides them as an input to a delay compensation block 80 within MCU 48. The delay compensation block 80 determines a suitable delay compensation value and provides this as an input to TRIAC drive signal generator 76.

TRIAC drive signal generator 76 converts the TRIAC drive pattern into suitable TRIAC drive signals and applies appropriate delay compensation, as described in more detail below. The TRIAC drive signals are output from MCU 48 and provided as an input to TRIAC drive circuit 82.

The AET temperature and heater temperature are also provided as inputs to overheat protection circuitry 96. Overheat protection circuitry 96 operates to determine when the AET temperature and/or heater temperature exceed various thresholds, and provides overheat control signals to TRIAC drive circuit 82 so that appropriate action can be taken, as described in more detail below.

TRIAC drive circuit 82 outputs TRIAC drive signals to TRIACs 98, and the TRIACs 98 are also coupled to receive the AC power supply, as described in more detail below. Although three TRIACs are illustrated, the skilled person will appreciate that any suitable number of TRIACs may be driven by the TRIAC drive signals.

Each TRIAC 98 drives a heater element 100 within heater 32. Each heater element 100 may take the form of, for example, a resistive trace on a heat-resistant substrate, such as a resistive wire wound around an insulating scaffold. Alternative types of heater can use a heater track printed onto a polyamide sheet such as Kapton or a ceramic heater coupon having an embedded heater track formed from a trace made from an electrically conductive material such as but not limited to tungsten. In order to dissipate heat from the ceramic heater coupon cooling fins may be provided. Each heater element 100 is exposed to air flowing through an air flow path of the haircare appliance 10, as described in more detail below.

Figure 3 shows a simplified schematic and partially sectioned view of the heater housing 14 and some of the components it contains. Many of the features and components described in relation to Figures 1 and 2, including the bend in heater housing 14, have been omitted for clarity.

Figure 3 shows schematically an air flow path 102 defined within heater housing 14. Airflow generator 34 comprises the fan motor 44 and an axial impeller 104. Fan motor 44 drives impeller 104 to generate airflow. Air is initially sucked through air inlet 26, as shown by an air-in arrow 106. The air passes through an inlet filter 108, which filters particles such as dust and hair from the air before it passes into the airflow path 102. In use, resistance offered by inlet filter 108 causes a reduced pressure region 110 between inlet filter 108 and impeller 104. Pressure sensor 58 is disposed within this region, to allow sensing of pressure changes as described in more detail below.

Air moves through impeller 104 and past motor 44, cooling motor 44 as it passes. The air is then heated as it passes through heater 32. The temperature of heater 32 is monitored by heater temperature sensor 90, as described in more detail below. Air then passes AET sensor 84, before exiting outlet 28 as shown by an air-out arrow 110.

Haircare appliance 10 may be used with one or more optional detachable accessories, such as a flow- accelerating accessory 160 as shown in Figure 3. Accessory 160 may be releasably attached at or adjacent air outlet 28 to control the shape, direction and speed, for example, of the airflow. Haircare appliance 10 includes a sensor or scanner, such as ID sensor 162, that allows an attached airflow accessory to be identified.

An attached airflow accessory 160 may be identified in any of a number of ways. For example, the accessory 160 may include an identifier that can be sensed or scanned by corresponding ID sensor 162.

The identifier may take the form of a circuit that can communicate the identifier. For example, the identity can be encoded by an identifier in the form of an RFID or near field communication (NFC) device 163 disposed in or on a portion of the accessory. In that case, ID sensor 162 takes the form of a corresponding RFID/NFC scanner provided on or in the haircare appliance 10. The RFID/NFC scanner can include any necessary antenna(s), one example of which encircles the air exit so that it interacts with the RFID/NFC device 163 when airflow accessory 160 is attached.

The identifier may, alternatively or in addition, take the form of a scannable image, that may be printed, embossed, engraved, 3-D-printed, or otherwise disposed in a scannable form onto or into a surface of the airflow accessory 160. The scannable image may take the form of, for example, a QR-code, a barcode, alphanumeric text, or any other suitable form of machine-readable image. The ID sensor 162 takes the form of a corresponding sensor or scanner, located in or on the heater housing 14 (or a main housing, in the event the haircare accessory is not formed of separate circuitry housing 12 and heater housing 14). The ID sensor 162 may operate optically (whether or not in the visible spectrum), ultrasonically, or electromagnetically, or based on any other suitable technology, or combination of such technologies.

The identifier may alternatively, or in addition, take the form of a physical shape or shapes that encode an identifier. For example, one or more raised ribs, lands, fingers, or recessed portions on the accessory can interact with a corresponding tongue, pin, tang, lever, or other physical element that is connected to, for example, a switch on heater housing 14, such as a physical, optical or electromagnetic switch.

The identifier may alternatively, or in addition, take the form of a magnetic or electromagnetic portion that can be sensed by a corresponding magnetic- or electromagnetic-sensitive switch or sensor.

Whatever approach is taken to identifying an attached airflow accessory, in general, installation of the accessory 160 onto the heater housing 14 results in the ID sensor 162 or scanner being positioned adjacent the identifier 163 (or the structure or mechanism by which the identifier is encoded). The scanner or sensor can then sense or scan the identifier value, allowing the haircare appliance 10 to identify the attached accessory 160.

The identifier can be, for example, an index, the haircare appliance 10 having a memory that stores a table mapping each index to information that allows airflow calculations to take into account the attached accessory. For example, the information may comprise a correction factor related to the identified accessory, allowing the airflow calculations to be suitably corrected for the impact of the attached accessory. Alternatively, the identifier may directly encode the information. For example, the identifier may store a number representative of a correction factor related to the accessory.

The identifier can encode multiple bits, representing several potential accessories and/or indices, allowing a correction factor to be used that best corresponds to a particular accessory that is attached. Alternatively, the identifier may effectively encode a single bit of information, allowing the haircare appliance 10 to identify the simple presence or absence of an accessory. This enables a single correction factor to be applied for all accessories, if attached. Although this may be limiting where multiple possible accessories are possible, simple presence/absence detection has the benefit of simplicity and potentially higher reliability.

Pressure processing block 62 within MCU 48 receives a pressure values from pressure processing circuitry 60. These values may be sampled with an internal analogue to digital converter (not shown) that converts an analogue pressure value into a numerical value that can be processed by pressure processing block 62. Alternatively, pressure processing circuitry 60 may include an analogue to digital converter (not shown), in which case the pressure values may take the form of numerical values input directly to MCU 48 and provided to pressure processing block 62. Either way, the pressure values may be received or sampled at a sufficiently high rate to allow for effective performance for whichever of the following pressure-based processes are performed by pressure processing block 62.

Many of the following pressure processing methods can be implemented based on relative, rather than absolute, air pressure. To determine a relative air pressure, an ambient air pressure may be determined prior to the airflow generator 30 reaching an operating speed following start-up. The exact timing is a compromise that balances a delay in starting the airflow generator 34 against the need for the ambient air pressure to be determined before a significant change in pressure is caused by the airflow generator. One option is to determine the ambient air pressure immediately prior to a motor drive signal being supplied to the airflow generator 34 (as described in more detail elsewhere).

Once the ambient air pressure has been determined, a dynamic air pressure may be determined after the airflow generator 34 reaches operating speed. The airflow generator reaching operating speed may be determined in any of a number of ways, based on one or more factors such as elapsed time, feedback signals from fan motor 44, changes in air pressure after the airflow generator 34 starts being driven, and any other way that will be apparent to the skilled person.

The dynamic air pressure is repeatedly determined, and subtracted from the ambient air pressure (which is determined only once at the beginning of the process). The result is a DR value that can be used as an input to the pressure processing methods described below.

Turning to Figure 4, there is shown a first pressure processing method 142 that can be implemented by pressure processing block 62. Based on the received pressure signal DR, pressure processing block 62 can estimate 144, at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path 102 is blocked.

The blockage factor may relate to any of a number of blockage types that may impact airflow path 102. One type of blockage is that arising from inlet filter 108 becoming clogged with dust and other detritus over time. As the blockage of inlet filter 108 increases, airflow is increasingly impeded. To account for this impedance, the airflow generator 34 may need to be driven harder to achieve similar airflow. Alternatively, or in addition, heater 32 may need to reduce its output to allow for correct air temperature at outlet 28, given the lower airflow due to the impedance.

Other blockages that may affect the estimated blockage factor include, for example wholly or partly covering air inlet 26 or air outlet 28, and a foreign object or material finding its way inside airflow path 102 and causing a total or partial blockage. The haircare appliance 10 may monitor changes in the blockage factor over time to assist in determining what blockage type has occurred. For example, if the blockage factor gradually increases over a relatively long period of time (e.g., several minutes or hours, possibly over many usage sessions of the haircare appliance), it may be concluded that the blockage relates to incremental blockage of inlet filter 108 due to dust, etc. Alternatively, if the blockage factor increases sharply (e.g., over seconds or fractions of a second), it may be concluded that the blockage relates to something that has more suddenly blocked the air inlet 26 or air outlet 28.

The blockage factor may be expressed in, for example, percentage terms. However, the complex relationship between changes in pressure, airflow and temperature in a haircare appliance 10 means that the blockage factor may be a nominal and/or relative factor defined for the specific haircare appliance 10.

A first assessment 146 is made as to whether the estimated blockage factor exceeds a blockage warning threshold. If the answer is “yes”, haircare appliance 10 outputs 148 a warning. The warning may take any suitable form. For example, an LED (not shown) or other visual display may light up, blink or otherwise visually indicate that the blockage warning threshold has been exceeded. A message may appear on a display (not shown) stating that the blockage warning threshold has been exceeded. An audible buzzer, tone, speech, or other sound may be output to audibly indicate that the blockage warning threshold has been exceeded. The fan motor 44 may be pulsed, or its output otherwise modulated in a way that a user will notice, to audibly and/or tactilely indicate that the blockage warning threshold has been exceeded. These and/or any other form of warning may be used, singly or in combination.

A second assessment 150 is then made as to whether the estimated blockage factor exceeds a critical warning threshold. If the answer is “yes”, haircare appliance 10 turns off or reduces a power output 151 of at least one component of the haircare appliance 10. The at least one component may include one or both of, for example, fan motor 44 and heater 32. Reducing the power output of heater 32 may, for example, lower a temperature of the air exiting air outlet 28, which will reduce the chance of damage to the haircare appliance 10 or the surrounding environment. Reducing the power output of fan motor 44 may reduce a chance of fan motor 44 being damaged by the partial blockage.

The answer to first assessment 146 is “no”, the method returns to blockage-estimating step 144.

Although the first pressure processing method 142 is shown as first and second sequentially-performed assessments 146 and 150, the skilled person will appreciate that the assessments may be made in any suitable order, or may be combined into a single assessment that simultaneously or sequentially applies the different thresholds. Applying a single assessment means that the step 151 of turning off or reducing power to at least one component of the haircare appliance 10 may be performed as soon as the critical blockage threshold is exceeded. This avoids the potential for delay that might occur if an output warning was generated in step 148 prior to assessing whether the critical threshold had been exceeded in assessment 150.

Optionally, any assessment of the estimated blockage factor against one or more thresholds may take into account one or more time periods. For example, a partial or even critical blockage may be ignored if it happens for only a short time. A different time period may be applied to different thresholds. For example, it may be important to turn off or reduce power if the critical threshold is exceeded more quickly than if only the warning threshold is exceeded.

Although the first pressure processing method 142 makes assessments against first and second thresholds, the skilled person will appreciate that more than two thresholds may be assessed. For example, in addition to the thresholds described in first pressure processing method 142, one or more additional thresholds may be assessed and acted upon. For example, an intermediate threshold between the first and second thresholds in method 142 may be assessed. This allows for a further level of warning. For example, if the threshold is exceeded in the first assessment, an LED may blink. If the intermediate threshold is exceeded in a further assessment, the fan motor 44 may be pulsed to indicate a higher level of urgency. The critical threshold can then be assessed 150 as described above. Any number of other additional assessments and thresholds may be applied, as desired.

The currently selected fan speed 52 may have an impact on estimation of the blockage factor. Accordingly, where the haircare appliance 10 has at least two selectable settings in the form of selectable fan speeds 52 that control at least a rate at which the airflow generator moves air through the airflow path, the method can optionally comprise estimating the blockage factor at least partly based on the currently selected fan speed.

For example, Figure 5 shows a graph 152 of various DR values plotted against each of four selectable fan speeds Ql, Q2, Q3, and Q4. Upper line 154 links the DR values for ordinary operation, where there is no blockage (i.e., blockage factor = 0). Middle line 156 links the DR values representing the warning threshold. Lower line 158 links the DR values representing the critical threshold. It will be observed that the respective slopes of the lines 154, 156 and 158 are different from each other, representing the complex interaction of pressure, airflow and fan speed setting. It will be appreciated that graph 152 is somewhat stylised, and that the lines linking the various DR values may not be straight.

The values of DR in ordinary operation (i.e., blockage factor = 0) may be established by testing and/or modelling of one or more haircare appliances 10. Testing may be performed on, e.g., pre-production or production models.

The critical threshold may also be determined based on tests and/or modelling, and may be based on an analysis of one or more of the components that may be affected by a partial or complete blockage, and/or the impact of a partial or complete blockage on the surroundings or user, in use. For example, fan motor 44 may be capable of running indefinitely even with full blockage of the inlet or outlet, in which case the impact of such blockage on fan motor 44 would not be taken into account in determining the critical threshold. If, alternatively, fan motor 44 is at risk of overheating if there is insufficient cooling airflow, then measurements and/or calculations may be made to determine a minimum necessary airflow. Similar calculations may be made for heater 32.

Thresholds may be stored in atable, for example, within memory of MCU 48. Alternatively, thresholds may be determined mathematically. For example, a threshold may be determined using an equation such as a* flowrate + b, where a and b are empirically-derived constants.

Optionally, haircare appliance 10 may include an accessory, such as accessory 160 in Figure 3, capable of being removably attached at or adjacent to the air outlet 28. Attachment of the accessory causes a change in characteristic of the airflow as it exits the airflow path through air outlet 28. For example, an attached air-concentrating accessory may cause a relatively lower pressure at pressure sensor 58 relative to that when the air-concentrating accessory is not attached, or a less impeding accessory is attached.

Method 142 may therefore optionally estimate the blockage factor at least partly taking into account an impact of the change in airflow characteristic caused when the airflow accessory is attached. This may be achieved by, for example, identifying an airflow accessory that is attached and determining, based the identified airflow accessory, a correction factor for use in estimating the blockage factor, as described above. Turning to 6, there is shown a second pressure processing method 164 that can be implemented by pressure processing block 62. Based on the received pressure signal DR, pressure processing block 62 can determine 166, based at least partly on the pressure signal, that airflow generator 134 is operating incorrectly to cause the air to move upstream. In this context, “operating incorrectly” can include the fan motor 44 operating the impeller 104 in reverse, or the fan motor not operating to move the airflow as expected. Motor reversal may be a higher risk when the fan motor 104 is single phase.

When it is determined that airflow generator 134 is operating incorrectly, airflow generator 134 is stopped 168.

Optionally, airflow generator 134 may be restarted. Airflow generator 134 may be restarted after it comes to a complete stop. It may be determined that fan motor has come to a complete stop in any suitable manner, such as by analysing electrical signals from fan motor 44, or by use of a separate movement sensor that detects when impeller 104 has stopped rotating. Alternatively, the pressure signal itself may be analysed to determine when the fan motor 44 has come to a complete stop.

Turning to Figure 7, there is shown a third pressure processing method 168 that can be implemented by pressure processing block 62, when pressure sensor 58 is disposed upstream of the airflow generator 34. In this case, and based on the received pressure signal DR, pressure processing block 62 can identify 170, based at least partly on the pressure signal, a drop in air pressure within airflow path 102.

It is then determined 172, based at least partly on the identified drop in air pressure, that there is an at least partial blockage of an outlet of the airflow path 102. The partial blockage may be determined as described above in relation to Figures 4 and 5.

Upon determining 172 that there is an at least partial blockage of an outlet, a further step 174 involves:

Turning off at least one component of haircare appliance 10, or reducing its power output; and/or

Outputting a warning indicative of the at least partial blockage of the outlet. The turning off (or power reduction) of the component, and/or the output of the warning, can be as described above in relation to Figures 4 and 5.

Step 170 can involve identifying the drop in the air pressure based on at least one change in the air pressure signal over time. For example, based on the pressure signal, a first dynamic air pressure may be determined while the airflow generator is at an operating speed, and then a second dynamic pressure may be determined, also while the airflow generator is at the operating speed. The drop in air pressure can then be based at least partly on a difference between the first dynamic air pressure and the second dynamic air pressure.

As with the first pressure processing method 142, the haircare appliance may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, and the at least partial blockage of an outlet of the airflow path may be determined taking into account the impact of the currently selected setting.

Also as with the first pressure processing method, determining that there is at least partial blockage of the outlet of the airflow path 102 may be based at least partly on a determination of whether an accessory is attached.

Turning off or reducing a power output of at least one component of the haircare appliance can comprise turning off or reducing a power output of: the airflow generator; and/or at least one heating element, such as the heater 32 of haircare appliance 10.

Third method 168 may include initially outputting the warning indicative of the at least partial blockage of the outlet, and subsequently turning off or reducing the power output of the at least one component of the haircare appliance in the event the outlet remains at least partly blocked following the warning.

Turning to Figure 8, there is shown a fourth pressure processing method 176 that can be implemented by pressure processing block 62. Based at least partly on the pressure signal, a change in air pressure within the airflow path is determined 178. It is then determined 180, based at least partly on the identified change in air pressure, that an accessory (such as accessory 160) has been detached. In this context, determining that an accessory has been “detached” means that such detachment has taken place while the appliance is in use (i.e., while the airflow generator 34 is operating). This may be because, for example, a user has removed a detachable accessory (such as accessory 160) or because the accessory has broken, fallen off, or been knocked off.

Where pressure sensor 58 is disposed upstream of airflow generator 34, a drop in air pressure may suggest that the accessory has been detached. Where airflow generator 34 is disposed downstream of airflow generator 34, a drop in air pressure may similarly suggest that the accessory has been detached.

Especially where haircare appliance 10 is designed for use only when a suitable accessory is in place, it may be important to prevent the haircare appliance 10 from operating if the accessory is no longer present. In such an arrangement, there will generally be an initial check to confirm that a suitable accessory is in place, followed by the implementation of fourth pressure processing method 176. The initial check may involve analysing the pressure signal, as described above, for example.

Alternatively, the initial check may involve the use of a sensor or scanner, such as ID sensor 162, to identify an attached accessory 160. The use of the pressure signal in fourth pressure processing method 176 can allow the sensor or scanner to be disabled during ongoing operation of haircare appliance 10 once the initial check is complete. This may be particularly advantageous when the scanner or sensor is susceptible to noise caused by, e.g., electrical, magnetic or vibration-based interference, such as electrical noise generated by fan motor 44 in use. Turning off the ID sensor 162 may also reduce power consumption and the generation of electrical interference, especially if the pressure signal is being generated for other purposes anyway.

Fourth processing method 176 may involve identifying the change in the air pressure based on at least one change in the air pressure signal over time, as described above in relation to other pressure processing methods.

As was also described above in relation to other pressure processing methods, the change in air pressure may be identified based at least partly on a change in a difference between the ambient air pressure and the dynamic air pressure. Alternatively, or in addition, the change in air pressure may be based at least partly on a difference between the first and second dynamic air pressures. As with the first pressure processing method 142, the haircare appliance may have at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, and determining that an accessory has been detached may be determined taking into account the impact of the currently selected setting.

Also as with previously described pressure processing methods, determining that an accessory has been detached may be based at least partly on a determination of whether an (and/or which) accessory is attached.

As with previously described pressure processing methods, fourth pressure processing method 176 may only determine that the accessory has been detached when the change in pressure has been present for a threshold time period. This can be to avoid, for example, premature action based on the accessory only briefly being detached.

After determining that the accessory has been detached, at least one component of the haircare appliance 10 may be turned off, or have its power adjusted 181. For example, the power supplied to heater 32 may significantly be reduced, or stopped entirely, to reduce the chance of a user accidentally being burned. Alternatively, or in addition, power supplied to fan 44 may be reduced, or stopped entirely, to reduce the chance of accidental contact with the fan 44. Alternatively, or in addition, power supplied to any device component or circuit accessible within airflow path 102 may have power supplied to it reduced, or stopped entirely.

Alternatively, or in addition, a warning indicating that the accessory has been detached may be output 181.

Optionally, fourth pressure processing method 176 can involve initially outputting the warning indicating that the accessory has been detached, and subsequently turning off or reducing the power output of the at least one component of the haircare appliance in the event the accessory remains detached following the warning.

While the pressure processing methods above have been described in terms of the method steps taken to implement them, the skilled person will appreciate that those steps may be performed by a controller, such as MCU 48, forming part of a haircare appliance, such as haircare appliance 10. As such, the above-described embodiments also cover apparatus claims corresponding to all described methods, including optional and alternative aspects.

Returning to Figure 2, AET sensor 84 senses a temperature of air exiting airflow path 102. Depending upon the position of AET sensor 84 within the airflow path, the actual temperature measured may vary from the actual temperature of the air across the cross-sectional area of air outlet 28 (determined by, for example, averaging and air temperature across the cross-sectional area).

For example, AET sensor 84 in Figures 1 and 3 is shown positioned to one side of airflow path 102. Due to, for example, incomplete mixing of air within airflow path 102 before exit and the relative position of heater 32 within airflow path 102, AET sensor 84 may under- or over-estimate the actual air temperature. This is illustrated in the graph 188 of Figure 9, which plots the temperature signal from AET sensor 84 against actual air temperature. Upper line 190 shows the relationship between the temperature signal and the actual air temperature at a relatively low airflow rate, and lower line 192 shows the relationship between the temperature signal and the actual air temperature at a relatively high airflow rate. It will be noted that upper line 190 is both slightly steeper, and vertically offset, relative to lower line 192.

It is possible to calibrate the relationship between the temperature measured by AET sensor 84 and that of the airflow as a whole. However, the problem may be exacerbated if there is a partial blockage that reduces airflow. This may be, for example, due to the inlet fdter 108 becoming clogged with dust over time.

To address this issue, Figure 10 shows a method 182 of determining a temperature correction factor. The correction factor is applied to the temperature signal output by AET buffer 88. Method 182 begins by estimating 184 a blockage factor, based at least partly on a pressure signal indicative of air pressure within the airflow path 102, such as the pressure signal provided by pressure processing circuitry 60.

The blockage factor corresponds to an amount by which the airflow path is blocked, and may be determined in accordance with any of the methods described above in relation to the first, second, third and fourth pressure processing methods 142, 164, 168, and 176. In particular, the amount by which the airflow path is blocked at least partly comprises an amount by which an air filter, such as inlet filter 108, is blocked. A temperature correction factor is then calculated 186, based on at least the blockage factor.

Where appliance 10 has two or more selectable airflow speed settings (as described above in relation to other aspects), the temperature correction factor may be calculated based at least partly on a current selected airflow speed setting.

The temperature correction factor may then be applied to the temperature signal from AET buffer 88. Optionally, the temperature correction factor is applied to the temperature signal only when the blockage factor exceeds a threshold. The threshold can correspond to, for example, a 40% blockage. Optionally, the temperature correction factor is applied to the temperature signal only when the blockage factor is below a further threshold. The further threshold can correspond to, for example, a 75% blockage. Blockages above the second threshold may be interpreted as representing a blockage significant enough that temperature compensation is not the appropriate response. In that case, another action or actions may be taken, such as warning the user, turning off the haircare appliance 10, and the like, as discussed in more detail above.

The temperature correction factor may be based on a formula that includes as an input a variable based on an airflow speed. The variable may be, for example, a currently selected airflow speed setting, or an implied speed corresponding to the currently selected airflow speed setting.

The temperature correction factor may be calculated based on, for example, the following formula: AT = a + b.B% + c.Q_set where:

AT is the temperature correction factor;

B% is the blockage factor;

Qset is an airflow speed setting; and a, b and c are coefficients determined empirically for the haircare appliance.

Airflow speed setting Q_set may, for example, be measured in litres/second. For example, there may be three possible airflow speed settings, such as 6 L/s, 9 L/s and 13 L/s.

Examples of coefficients a, b and c for one haircare appliance are: a = -26.183376 b = 0.321128 c = 1.280488

However, the coefficients will typically be determined based on modelling and/or testing of particular haircare appliances.

Although not shown in Figure 2, circuitry housing 12 can also include a voltage sensing circuit similar to voltage sensing circuit 70, and a further microprocessor, for sensing AC mains supply voltage at the circuitry housing. The sensed voltage can be used, for example, to prevent the haircare appliance from turning on if the voltage is outside an acceptable range. Alternatively, or in addition, the voltage can be monitored for temporary power loss, such as in a brown-out or similar situation. If, in use, the voltage drops below a critical level for more than some predetermined period, operation of the haircare appliance 10 may be halted for safety. An example period would be 20ms, although other periods may be selected based on circumstances. More generally, the skilled person will appreciate that there may be a different distribution of components between circuitry housing 12 and heater housing 14 than that shown. Optionally, circuitry housing 12 can incorporate power connector (i.e., plug) 15, such that circuitry housing 12 can be directly plugged into a power socket. Alternatively, all of the components may be disposed within a heater housing, without the use of a separate circuitry housing such as circuitry housing 12.

While haircare appliance 10 has been described as a hairdryer, it will be appreciated that many of the teachings discussed herein may be applied to other types of haircare appliance, such as hair straighteners, hair curlers, and the like, for example.

Claims

1. A haircare appliance comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path, the pressure sensor being upstream of the airflow generator; and a controller configured to: receive the pressure signal; estimate, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked; when the estimated blockage factor exceeds a blockage warning threshold, output a warning indicative of a partial blockage; and when the estimated blockage factor exceeds a critical threshold, the critical threshold being higher than the blockage warning threshold, turn off or reduce a power output of at least one component of the haircare appliance.

2. The haircare appliance of claim 1, including an air filter for filtering air entering the airflow path, the amount by which the airflow path is blocked at least partly comprising an amount by which the filter is blocked.

3. The haircare appliance of claim 1 or 2, wherein the controller is configured to: based on the pressure signal, determine an ambient air pressure prior to the airflow generator reaching an operating speed based on the pressure signal, determine a dynamic air pressure after the airflow generator reaches the operating speed; and estimate the blockage factor at least partly based on a difference between the ambient pressure and the dynamic air pressure.

4. The haircare appliance of claim 3, wherein the controller is configured to determine the ambient air pressure prior to a drive signal being supplied to the airflow generator.

5. The haircare appliance of any preceding claim, wherein: the haircare appliance has at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path; and the controller is configured to: receive information indicative of a currently selected setting; and estimate the blockage factor at least partly based on the received information indicative of a currently selected setting.

6. The haircare appliance of claim 5, wherein turning off or reducing a power output of at least one component of the haircare appliance comprises turning off or reducing a power output of the airflow generator.

7. The haircare appliance of any preceding claim, including an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in characteristic of the airflow as it exits the airflow path, wherein the controller is configured to estimate the blockage factor at least partly taking into account an impact of the change in airflow characteristic caused when the airflow accessory is attached.

8. The haircare appliance of claim 7, wherein the controller is configured to: identify an airflow accessory that is attached; and determine, based the identified airflow accessory, a correction factor for use in estimating the blockage factor.

9. The haircare appliance of claim 8, wherein the controller is configured to look up, in a memory, the correction factor, based on the identified accessory.

10. The haircare appliance of any one of claims 7 to 9, comprising a sensor for identifying the airflow accessory that is attached.

11. The haircare appliance of any one of claims 7 to 10, wherein the correction factor is stored by the accessory, and the controller is configured to read the correction factor from the accessory.

12. A method comprising: generating a pressure signal indicative of air pressure within an airflow path of a haircare appliance upstream of an airflow generator; estimating, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked; when the estimated blockage factor exceeds a blockage warning threshold, outputting a warning indicative of a partial blockage; and when the estimated blockage factor exceeds a critical threshold, the critical threshold being higher than the blockage warning threshold, turning off or reducing a power output of at least one component of the haircare appliance.

13. The method of claim 12, the amount by which the airflow path is blocked at least partly comprising an amount by which an air filter in the airflow path is blocked.

14. The method of claim 12 or 13, comprising: based on the pressure signal, determining an ambient air pressure prior to the airflow generator reaching an operating speed; based on the pressure signal, determining a dynamic air pressure after the airflow generator reaches the operating speed; and estimating the blockage factor at least partly based on a difference between the ambient pressure and the dynamic air pressure.

15. The method of claim 14, comprising determining the ambient air pressure prior to a drive signal being supplied to the airflow generator.

16. The method of any one of claims 12 to 15, wherein the haircare appliance has at least two selectable settings that control at least a rate at which the airflow generator moves air through the airflow path, the method comprising: receiving information indicative of a currently selected setting; and estimating the blockage factor at least partly based on the received information indicative of a currently selected setting.

17. The method of claim 16, wherein turning off or reducing a power output of at least one component of the haircare appliance comprises turning off or reducing a power output of the airflow generator.

18. The method of any one of claims 12 to 17, wherein the haircare appliance includes an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in characteristic of the airflow as it exits the airflow path, the method comprising estimating the blockage factor at least partly taking into account an impact of the change in airflow characteristic caused when the airflow accessory is attached.

19. The method of claim 18, comprising: identifying an airflow accessory that is attached; and determining, based the identified airflow accessory, a correction factor for use in estimating the blockage factor.

20. The method of claim 19, comprising looking up, in a memory, the correction factor, based on the identified accessory.

21. The method of any one of claims 18 to 20, comprising using a sensor to identify the airflow accessory that is attached.

22. The method of any one of claims 18 to 21, wherein the correction factor is stored by the accessory, and the method comprising reading the correction factor from the accessory.

23. A haircare appliance comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path, the pressure sensor being upstream of the airflow generator; and a controller configured to: receive the pressure signal; determine, based at least partly on the pressure signal, that the airflow generator is operating incorrectly to cause the air to move upstream; and upon determining that the airflow generator is operating incorrectly to cause the air to move upstream, stop the airflow generator.

24. A method comprising: generating a pressure signal indicative of air pressure within an airflow path of a haircare appliance upstream of an airflow generator; determining, based at least partly on the pressure signal, that the airflow generator is operating incorrectly to cause the air to move upstream; and upon determining that the airflow generator is operating incorrectly to cause the air to move upstream, stopping the airflow generator.

25. A haircare appliance comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path, the pressure sensor being disposed upstream of the airflow generator; and a controller configured to, while the airflow generator is active to move the air downstream through the airflow path: receive the pressure signal; identify, based at least partly on the pressure signal, a drop in air pressure within the airflow path; determine, based at least partly on the identified drop in air pressure, that there is an at least partial blockage of an outlet of the airflow path; and upon determining that there is an at least partial blockage of an outlet: turning off or reducing a power output of at least one component of the haircare appliance; or outputting a warning indicative of the at least partial blockage of the outlet.

26. A method performed by a haircare appliance, the method comprising: generating a pressure signal indicative of air pressure within an airflow path of the haircare appliance upstream of an airflow generator; identifying, based at least partly on the pressure signal, a drop in air pressure within the airflow path; determining, based at least partly on the identified drop in air pressure, that there is an at least partial blockage of an outlet of the airflow path; and upon determining that there is an at least partial blockage of an outlet: turning off or reducing a power output of at least one component of the haircare appliance; or outputting a warning indicative of the at least partial blockage of the outlet.

27. A haircare appliance comprising: an airflow path, the airflow path having disposed within it: an airflow generator for moving air downstream through the airflow path; and a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path; and an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in a characteristic of the airflow as it exits the airflow path; a controller configured to: receive the pressure signal; identify, based at least partly on the pressure signal, a change in air pressure within the airflow path; and determine, based at least partly on the identified change in air pressure, that the accessory has been detached.

28. A method performed by a haircare appliance, the haircare appliance comprising an accessory capable of being removably attached at or adjacent to an outlet of the airflow path, attachment of the accessory causing a change in a characteristic of the airflow as it exits the airflow path the method comprising: generating a pressure signal indicative of air pressure within an airflow path of the haircare appliance upstream of an airflow generator; identifying, based at least partly on the pressure signal, a change in air pressure within the airflow path; determining, based at least partly on the identified change in air pressure, that the accessory has been detached.

29. A haircare appliance comprising an airflow path, the airflow path having disposed within it: a pressure sensor for generating a pressure signal indicative of air pressure within the airflow path; an airflow generator for moving air downstream through the airflow path; a heater for heating the air; and a temperature sensor for generating a temperature signal indicative of a temperature of air heated by the heater; the haircare appliance including a controller configured to receive at least the pressure signal and the temperature signal, and configured to: estimate, based at least partly on the pressure signal, a blockage factor corresponding to an amount by which the airflow path is blocked; calculate a temperature correction factor to apply to the temperature signal, based on at least the blockage factor.

30. A method of determining a temperature correction factor to apply to a temperature signal generated by a temperature sensor downstream of a heater within an airflow path of a haircare appliance, the temperature signal being indicative of a temperature of air heated by the heater, the method comprising: estimating, based at least partly on a pressure signal indicative of air pressure within the airflow path, a blockage factor corresponding to an amount by which the airflow path is blocked; and calculating a temperature correction factor to apply to the temperature signal, based on at least the blockage factor.

31. A haircare appliance comprising a barometer chip for measuring air pressure, the barometer chip having a power supply input and an enable input, the power supply input and the enable input being electrically coupled to a signal line, such that a control signal appearing on the signal line both powers up and enables the barometer chip.