Hair styling appliance

Abstract

A hair styling appliance comprising an optical sensor configured to make two or more measurements of light received from a section of hair being styled by the hair styling appliance, and a processor configured to determine a speed of movement of the section of hair relative to the hair styling appliance based on the two or more measurements.

Description

[0001] HAIR STYLING APPLIANCE

[0002] BACKGROUND

[0003] Hair styling appliances are generally used to treat or style hair. Some hair styling appliances are typically held by a user and moved relative to the hair to obtain a desired treatment or styling.

[0004] SUMMARY

[0005] According to a first aspect, there is provided a hair styling appliance comprising: an optical sensor configured to make two or more measurements of light received from a section of hair being styled by the hair styling appliance; and a processor configured to determine a speed of movement of the section of hair relative to the hair styling appliance based on the two or more measurements.

[0006] In this way, the hair styling appliance can determine a speed of movement of a section of hair being styled or treated by the hair styling appliance relative to the hair styling appliance. This information may be useful for the user, because the speed at which the hair styling appliance is moved relative to the hair can vary the styling performance and / or vary the risk of damaging the hair, e.g., due to overheating.

[0007] Optional features will now be set out.

[0008] The measurements of light received may be measurements of intensity of light.

[0009] The processor may be configured to determine a speed of movement of hair relative to a surface of the hair styling appliance. The surface may be a surface for contacting the section of hair during styling by the hair styling appliance.

[0010] The two or more measurements may be sequential measurements of the optical sensor. For example, the two or more measurements may be consecutive measurements (i.e., a first measurement and a second measurement immediately following the first measurement). Alternatively, the two or more measurements may be non-consecutive measurements (i.e., a first measurement and a later measurement, with intermediate measurements between the first and later measurements). The two or more measurements may be separated from one another by a time delay.

[0011] The hair styling appliance may further comprise a light source configured to illuminate the section of hair being styled by the hair styling appliance, wherein the light received from the section of hair comprises light emitted from the light source, and reflected or attenuated by the section of hair.

[0012] By providing a light source at the hair styling appliance, the measurements made by the optical sensor may be more accurate, and thus the determined speed of movement of the section of hair relative to the hair styling appliance may be more accurate, e.g., compared to if ambient light is received from the section of hair being styled.

[0013] The light source may comprise one or more LEDs, and / or one or more lasers, for example.

[0014] The hair styling appliance may perform a straightening, curling, styling and / or drying function.

[0015] The hair styling appliance may be a conduction hot plate hair straightener, a hot air straightener, a hot air styler, a hot air dryer, a hair formulation / liquid / mist / steam dispensing device, a hairbrush, a dielectric RF / MF hair straightener, or a radiative FIR hair straightener or dryer.

[0016] The hair styling appliance may comprise a main body and a reversibly connectable hair treatment attachment. The optical sensor may be positioned in or on the attachment. Alternatively, the optical sensor may be positioned in or on the main body. At least part of the processor may be positioned in the main body. At least part of the processor may be positioned in the attachment.

[0017] The two or more measurements may comprise at least a first image and a second image. The second image may be taken sequentially to the first image. The processor may be configured to determine a speed of movement of the section of hair relative to the hair styling appliance by: comparing the first and the second images; and determining a speed of movement of the section of hair across the optical sensor in at least one direction based on a comparison of the first and second images.

[0018] The sequential images may be consecutive images, or non-consecutive images.

[0019] The optical sensor may comprise one or more of a CMOS sensor, a camera, and / or an array of photosensors.

[0020] The hair styling appliance may further comprise a hair treatment element configured to treat the section of hair. The processor may be configured to control an output of the hair treatment element based on the determined speed of movement of the section of hair relative to the hair styling appliance.

[0021] By controlling the output of the hair treatment element based on the determined speed of movement of the section of hair relative to the hair styling appliance, styling of the hair by the hair treatment element may be modified based on the determined speed.

[0022] The hair treatment element may comprise a heater for heating the section of hair, a blower for generating and directing an airflow towards the section of hair, a dispenser for dispensing fluid and / or vapor towards the section of hair, and / or a mechanical actuator for varying the clamp force and / or crimping action of the hair styling appliance and / or moving / vibrating the section of hair for detangling and / or friction reduction.

[0023] Accordingly, the output of the heater, blower, dispenser, and / or mechanical actuator may be controlled or modified based on the determined speed of movement of the section of hair.

[0024] The heater may be a conduction, dielectric (RF / MF), FIR radiation or fan-forced convection heater, for example.

[0025] Controlling the output of a heater may include controlling the temperature of the heater, for example. Controlling the output of a blower may include varying the direction and / or velocity of the airflow. Controlling the output of the dispenser may include varying the dispensing rate. Controlling the output of the mechanical actuator may include varying hair clamping forces and / or tension along the section of hair, e.g., at predetermined displacement intervals. For example, the tension may be varied based on the determined speed of the section of hair relative to the hair styling appliance, and / or the clamp force may be altered (e.g., alternated) based on a determined displacement to control a crimp spacing, for example. Controlling the output of the mechanical actuator may include controlling (e.g., triggering) a hair vibrating action to aid detangling and / or reduce friction, e.g., based on a detected motion change distinctive of a snag (e.g., sudden reduction in speed of section of hair relative to the hair styling appliance), or processing of one or more (low resolution) images to identify tangles.

[0026] The processor may be configured to control the output of the hair treatment element by controlling the power supplied to the hair treatment element based on the determined speed of movement of the section of hair relative to the hair styling appliance.

[0027] Controlling the power supplied to the hair treatment element may include changing, e.g., increasing or decreasing, the power supplied, and / or switching the power on or off, for example.

[0028] The processor may be configured to output a feedback signal for providing user feedback related to the determined speed of the section of hair relative to the hair styling appliance.

[0029] In this way, the user may be made aware of the information related to the determined speed of the section of hair relative to the hair styling appliance. The user may then adjust their use of the hair styling appliance, to achieve their preferred styling performance and / or to reduce the risk of hair damage, e.g., due to overheating if the user is moving the hair styling apparatus relative to the section of hair too slowly such that the section of hair may overheat.

[0030] The hair styling appliance may itself provide the user feedback. Accordingly, the hair styling appliance may comprise a feedback element configured to provide visual, audible and / or haptic feedback to a user based on the feedback signal output from the processor.

[0031] In this way, the user may receive the user feedback directly from the hair styling appliance.

[0032] The feedback element may comprise one or more LEDs, display screens, speakers, and or vibration motors, for example. The processor may be configured to compare the determined speed of movement of the section of hair relative to the hair styling appliance to at least one predefined threshold, and to output the feedback signal based on the comparison of the determined speed and the at least one predefined threshold.

[0033] The processor may be configured to compare the determined speed of movement of the section of hair relative to the hair styling appliance to a plurality of predefined thresholds and to output the feedback signals based on the comparison of the determined speed and the plurality of predefined thresholds.

[0034] The predefined thresholds may be predefined against different velocity levels, and used to constrain feedback states to specific velocity ranges, for example. The predefined thresholds may include a degree of hysteresis and / or time-based filtering to smooth transitions between feedback states.

[0035] In this way, the user may be provided with information indicating that the measured velocity is within a predefined range of velocities, for example.

[0036] The hair styling appliance may further comprise a communication element for communicatively coupling with an external device. The processor may be configured to output the signal for providing user feedback to the external device, for display to the user thereon.

[0037] In this way, the user feedback may be provided via the external device.

[0038] The external device may be a mobile device, tablet, or computer, for example.

[0039] The processor may be configured to determine a two-dimensional velocity of the section of hair relative to the hair styling appliance based on at least two measurements of the optical sensor. Accordingly, the speed of the section of hair relative to the appliance lengthways along a hair tress in the section of hair, and also perpendicular to the length of the hair tress, may be determined. This may be useful in providing further information to the user about the use of the hair styling appliance. The hair styling appliance may further comprise an optical component (e.g., one or more lens) for directing, distributing, focussing and / or magnifying the light received from the section of hair at the optical sensor.

[0040] This may improve the accuracy of the measurements taken by the optical sensor, and thus the accuracy of the determined speed of movement of the hair relative to the hair styling appliance.

[0041] The processor may be configured to determine a direction of the relative movement between the section of hair being styled and the hair styling appliance, and / or an angle of one or more strands of hair in the section of hair relative to the hair styling appliance, based on at least two measurements of the optical sensor.

[0042] For example, the direction of the relative movement between the section of hair being styled and the hair styling appliance may be determined based on two orthogonal measurements of the displacement of a pixel feature between two images. For example, if a pixel feature moves from (x,y) to (x+dx, y+dy), then the displacement in two orthogonal directions can be calculated as dx and dy. The direction / angle of the relative movement may then be calculated using trigonometry. The direction of the relative movement between the section of hair and the hair styling appliance can be calculated as the orientation of the image frames relative to the hair styling appliance is known (as the optical sensor is fixed relative to the hair styling appliance.)

[0043] To determine an angle of one or more strands of hair in the section of hair, edge points of hair strands may be emphasised by applying a predefined threshold to an image of the section of hair (e.g., a measurement by the optical sensor of the light received from the section of hair being styled). The predefined threshold may be applied based on pixel intensity. One or more lines may then be extracted using one or more machine learning, pattern recognition, or image processing feature extraction techniques. For example, the “Hough transform” method may be used to identify lines in the image by determining, based on an extent to which neighbouring pixels (of a given edge point) conform to a straight-line formula (e.g., y = mx + c). As the orientation of the image frame relative to the hair styling appliance is known (as the optical sensor is fixed relative to the appliance) trigonometry may be used to provide the angle of the strands based on the gradient of detected line(s).

[0044] A strand-to-stand alignment metric may be calculated by applying statistical analysis to all the line angles identified in the image. A type of hair (e.g., curly or straight) may also be determined from the extracted lines, e.g., by measuring a deviation of edge points along the detected straight lines. Less deviation from the detected straight lines may indicate straighter hair, for example.

[0045] The processor may be configured to determine whether hair is present at the hair styling appliance for styling based on at least one measurement of the optical sensor.

[0046] The processor may be configured to determine whether hair is present at the hair styling appliance by (i) comparing the determined speed to a predefined threshold and determining that hair is present when the speed meets the predefined threshold, and / or (ii) comparing an intensity of the light received at the optical sensor to a predefined threshold and determine that hair is present when the intensity meets the predefined threshold.

[0047] The hair styling appliance may provide user feedback to the user based on the determination as to whether hair is present at the hair styling appliance. An output of the hair treatment element may also be controlled based on the determination as to whether or not hair is present at the hair styling appliance.

[0048] The processor may be configured to determine a start and / or end of styling of the section of hair based on a plurality of measurements by the optical sensor.

[0049] For example, when the processor determines a change from high speed to low speed, the processor may determine the end of styling of the section of hair, e.g., pass end. When the processor determines a change from low speed to high speed, the processor may determine the start of styling of the section of hair e.g., pass start. The processor may be configured to control the power supplied to the hair treatment element based on a determined start and / or end of styling. The processor may be configured to provide user feedback to the user based on the determination as to whether hair is present at the hair styling appliance. The optical sensor may be orientated and / or positioned on the hair styling appliance such that at least a portion of the section of hair being styled by the hair styling appliance is within a field of view of the optical sensor.

[0050] The light source may be orientated and / or positioned on the hair styling appliance such that at least a portion of the section of hair being styled by the hair styling appliance is within the field of illumination, FOI, of the light source.

[0051] The hair styling appliance may further comprise a time-of-flight and / or proximity sensor for determining a distance between the hair styling appliance and the section of hair being styled. Additionally / altematively, the hair styling appliance may comprise an inertial sensor for determining the orientation and / or motion of the hair styling appliance, e.g., relative to the Earth. Inertial sensors may include accelerometers and / or gyroscopes for example. Measurements from the inertial sensor may be used to improve accuracy and / or to provide additional spatial referencing.

[0052] The processor may be configured to determine the speed of movement of the section of hair relative to the hair styling appliance based also on the determined distance between the hair styling appliance and the section of hair being styled.

[0053] BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure l is a schematic diagram of a hair styling appliance;

[0055] Figure 2a and Figure 2b are perspective views of embodiments of the hair styling appliance of Figure 1;

[0056] Figure 3 is a perspective of another embodiment of the hair styling appliance of Figure 1;

[0057] Figure 4 is a perspective view of another embodiment of the hair styling appliance of

[0058] Figure 1;

[0059] Figure 5 is a perspective view of another embodiment of the hair styling appliance of

[0060] Figure 1;

[0061] Figure 6 is a perspective view of another embodiment of the hair styling appliance of

[0062] Figure 1; Figure 7a and Figure 7b show section views of the hair styling appliance of Figure 6, wherein the section views indicate an airflow path through the hair styling appliance;

[0063] Figure 8 is a perspective view of another embodiment of the hair styling appliance of Figure 1;

[0064] Figure 9 is a perspective view of another embodiment of the hair styling appliance of Figure 1;

[0065] Figure 10 is an enlarged view illustrating an optical sensor of a hair styling appliance such as the hair styling appliance shown in Figures 2a, 2b, 3, and 4;

[0066] Figure 11 is an enlarged view illustrating an optical sensor of a hair styling appliance such as the hair styling appliance of Figures 5, 6, 8 and 9;

[0067] Figure 12a and Figure 12b illustrate the calculation, by a processor of a hair styling appliance, of measurements made by an optical sensor of the hair styling appliance;

[0068] Figure 13 illustrates a further calculation, by a processor of a hair styling appliance, of measurements made by an optical sensor of the hair styling appliance; and

[0069] Figure 14 shows example images captures by an optical sensor of a hair styling appliance.

[0070] DETAILED DESCRIPTION

[0071] A hair styling appliance, generally designated 10, is shown schematically in Figure 1. The hair styling appliance 10 may perform a straightening, curling, drying, styling, treatment and / or detangling function on a user’s hair. For example, the hair styling appliance 10 may be a hair straightener, hairdryer, hair curler, hairbrush, or the like. Although not shown in Figure 1, the hair styling appliance 10 may comprise an attachment reversibly connectable to a main body. In these examples, the main body may be usable with multiple different attachments, each having a different styling function.

[0072] The hair styling appliance 10 comprises an optical flow sensing system 12 for detecting a speed of movement of the user’s hair relative to the hair styling appliance 10, and more particularly relative to a surface of the hair styling appliance, as the user’s uses the hair styling appliance 10 to style their hair. In the example of a hair straightener, the user may draw or feed a section of hair between two heater platers and the optical flow sensing system 12 may determine a speed of movement of the section of hair relative to one of the two heater platers. Active components of the hair styling appliance 10, such as the optical flow sensing system 12, are powered by a power source 14. The power source 14 may be internal to the hair styling appliance 10, and may be, for example, a rechargeable battery in the hair styling appliance 10. Alternatively / additionally the hair styling appliance may be powered by an external power source. In these examples, the hair styling appliance may be connectable to an external power source by a wire or cable. In examples, with an internal power source, the internal power source may be recharged, with power from an external power source, by a wire or cable. The power source 14 may also provide power to other components of the hair styling appliance, e.g. components external to the optical flow sensing system 12, including active hair treatment elements such as heaters or motors etc.

[0073] The optical flow sensing system 12 comprises control electronics 16 for controlling and supplying power to other components of the optical flow sensing system 12. In particular, the control electronics 16 control a light source 18 and an optical sensor 20 of the optical flow sensing system 12. The light source 18 may be driven by an illumination driver 22, as shown in Figure 1.

[0074] The light source 18 may comprise one or more LEDs and / or one or more lasers, and is for illuminating the section of hair, or a portion of the section of hair, being styled by the hair styling appliance 10.

[0075] The optical sensor 20 may comprise one or more of a CMOS sensor, a camera, and / or an array of photosensors, such as the picture element array shown in Figure 1. The optical sensor 20 is configured to measure a property of light emitted from the light source 18, and reflected from or attenuated by the section of hair being treated. The optical sensor 20 may measure an intensity of light received from the section of hair, for example.

[0076] The hair styling appliance may comprise a plurality of optical sensors 20, which may be positioned in an array for example. In this way, the probability of hair being within a field of view (FOV) of one or more of the optical sensors is increased.

[0077] A processor 24, such as the Digital Signal Processing (DSP) module shown in Figure 1, is configured to determine a speed of movement of the user’s hair relative to the hair styling appliance 10, based on two or more measurements made by the optical sensor 20. The two or more measurements may be sequential, e.g., consecutive measurements of the optical sensor 20. The control electronics 16 may control the optical sensor 20 to capture or measure the light reflected or received from the user’s hair periodically, for example.

[0078] The two or more measurements may comprise at least a first image, such as image 302 shown in Figure 12a, and a second image, such as image 304 shown in Figure 12b. By comparing the first image 302 and the second image 304, the processor 24 can determine a speed of movement of the section of hair across the optical sensor in at least one direction based on the comparison of the first and second images 302, 304.

[0079] As illustrated in the example of Figures 12a and 12b, the processor 24 can identify a feature 306 (or a plurality of features) in the first image 302. The processor 24 can then identify the same feature 306 (or plurality of features) in the second image 304, and then determine the displacement of the feature(s) between the two images. Using information related to the time between the capture of the two images 203, 304, which may be determined by an oscillator or clock 26, and the displacement of the feature(s) between the two images, the processor 24 can determine a speed of movement of the user’ s hair relative to the hair styling appliance 10.

[0080] The processor 24 may determine a velocity of the hair relative to the hair styling appliance in 2 dimensions based on the comparison between the two images. Accordingly, both the speed and the directi on / angle of movement of the hair styling appliance 10 relative to the hair may be determined. This is illustrated in the example of Figure 13. The images may be defined in two-dimensional space in x and y, and may be assigned a time t, determined by oscillator 26. A feature in a first image, e.g., image frame 1 in Figure 13, may be identified by the processor 24, and assigned x and y coordinates based on its position within the image array. The feature in the first image is also assigned a time t based on the time the image was measured or collected by the optical sensor 20. The same feature in the second image, e.g., image frame 2 in Figure 13, may be identified by the processor 24, and the location of the feature determined within the image array, e.g., as x+dx, y+dy. The feature in the second image is assigned a time t+dt based on the time the image was measured or collected. Then, the processor 24 can calculate the 2-D displacement of the feature between the two images as (dx, dy). The direction of movement of the section of hair relative to the hair styling appliance can then be calculated using trigonometry. Using also the difference in time between the two images as dt, the 2-D velocity of the feature relative to the optical sensor 20 can be calculated (using velocity = distance / time). The 2-D velocity of movement of the user’s hair relative to the hair styling appliance 10 can then be inferred from the speed of movement of the feature of the hair relative to the optical sensor 20, as the optical sensor 20 is fixed relative to the hair styling appliance.

[0081] As set out above, the relative speed, and direction / angle of movement between the hair and the hair styling appliance may be determined by the processor 24, based on at least two measurements of the optical sensor.

[0082] The processor 24 may also determine whether hair is present at the hair styling appliance for styling based on at least one measurement of the optical sensor. For example, the processor may determine using object recognition or classification techniques whether hair is present in an image captured by the optical sensor 20. Altematively / additionally, the processor 24 may determine whether hair is present by comparing a measurement (e.g., intensity) of light received at the optical sensor to a predefined threshold, and determine that hair is present when the intensity meets the predefined threshold.

[0083] Figure 14 illustrates example images of the hair obtained by an optical sensor. The images in Figure 14 are split into pairs a), b) and c), wherein the upper images are higher resolution images of the same section of hair as the lower images.

[0084] From e.g. any one of these images in Figure 14, the processor may be configured to determine that hair is present at the hair styling appliance 10 for styling, based on an identification of one or more elongate strands of hair in the image, for example.

[0085] The processor 24 may also determine whether hair is present at the hair styling appliance for styling based on two measurements of the optical sensor 20, and in particular the determined relative speed of movement of the hair relative to the optical sensor 20. In particular, the processor 24 may compare the determined speed to a predefined threshold, and determine that hair is present when the speed meets the predefined threshold.

[0086] The processor 24 may also determine a start and / or end of styling of the section of hair, e.g. a pass start or a pass end, based on a plurality of measurements by the optical sensor. For example, when the processor determines a change from high speed to low speed, the processor may determine the end of styling of the section of hair, e.g., pass end. A pass end may be determined when hair is no longer determined to be present at the hair styling appliance. When the processor determines a change from low speed to high speed, the processor may determine the start of styling of the section of hair e.g., pass start. A pass start may be determined when hair is introduced, and therefore first determined to be present, at the hair styling appliance.

[0087] The processor may also be configured to determine a duration of styling of the section of hair (e.g., pass length), based on a plurality of measurements of the optical sensor. The pass length may be determined based on the determined pass start and pass end, for example. The processor may be configured to determine a position of the hair styling appliance relative to a length of hair tress, based on the determined pass start, and the determined relative speed of movement, for example. A length of the hair tress may also be determined by the processor, based on the determined pass start, the determined pass end, and the time taken between these two measurements (which may be determined by the oscillator / clock 26).

[0088] The hair styling appliance 10 may also comprise one or more optical components 28 (e.g., lenses) positioned in the light path from the light source 18 to the section or hair being treated, and / or in the light path from the section of hair being treated to the optical sensor 20. The optical components may be for directing, distributing, focussing and / or magnifying the light directed from the light source 18 to the hair and / or from the hair to the optical sensor 20. In some examples, an optical component, such as a lens, may be positioned between the light source 18 and the hair for distributing the emitted light. An optical component, such as a lens, may be positioned between the hair and the optical sensor 20 for focussing or magnifying the light reflected back towards the optical sensor.

[0089] The direction of the emitted light from the light source 18 may create a substantially incident illumination of a surface of the hair relative to the optical sensor 20, e.g. to increase / emphasise shadowing / highlights and produce a large brightness contrast in the images acquired by the optical sensor 20. This may be achieved by angling the components of the optical flow sensing system 12, and / or by directing the light through the one or more optical components 28. Optical components may not be necessary if the light source 18 comprises one or more lasers, as lasers inherently provide a narrower illumination spot / tighter focus with higher intensity than LEDs.

[0090] Information related to the determined speed of movement of the hair relative to the hair styling appliance 10 may be stored in storage 30. Information related to the determination about whether hair is present at the hair styling appliance may also be stored. Information related to the pass start / end, pass length, position of appliance along hair tress, length of hair tress, and total number of passes may be stored in storage 30. This information may be stored in combination, e.g., pass speed plotted against position of appliance on tress may be useful to indicate if the operator is moving the appliance too fast on the roots, for example.

[0091] This data may then be provided as feedback to the user and / or used to control one or more functions of the hair styling appliance 10 in a closed loop control system, for example.

[0092] To provide user feedback, the processor may output a feedback signal for providing user feedback related to the determined speed of the section of hair relative to the hair styling appliance, to a user interface, or feedback element, 32 of the hair styling appliance 10.

[0093] Feedback element 32 may provide visual, audible and / or haptic (e.g., tactile) feedback to the user based on the information related to the determined speed of movement of the hair. For providing visual feedback, the hair styling appliance 10 may comprise one or more LEDs and / or display screens, e.g., LCD display screens, for example. The LED may be RGB LEDs configured to emit light of different colours. For providing audible feedback, the hair styling appliance 10 may comprise one or more speakers, and for providing haptic (e.g., tactile) feedback, the hair styling appliance 10 may comprise one or more vibration motors.

[0094] The feedback provided may indicate if the determined speed of movement of the hair styling appliance 10 relative to the hair, or the determined direction of movement, meets one or more predefined criteria and / or if the determined speed of movement of the hair styling appliance 10 relative to the hair, or the determined direction of movement, does not meet one or more predefined criteria. The feedback element may provide feedback only when the determined speed of movement is outside of the predefined range, e.g., as an alert.

[0095] For example, the feedback element 32 may indicate that the determined speed of movement of the hair styling appliance is within a predefined range, and the pass speed is thus “Good”, by providing a first feedback state. The feedback element 32 may indicate that the determined speed of movement of the hair styling appliance is outside of a predefined range, by providing different feedback. For example, if the pass speed is too fast (e.g., above an upper threshold of the predefined range), the feedback element 32 may provide a second feedback state, and if the pass speed is too slow (e.g., below a lower threshold of the predefined range) the feedback element 32 may provide a third feedback state. The first, second and third feedback states may be different; e.g., LEDs emitting different colours, different flashing patterns, different sounds, different vibration patterns.

[0096] For example, if the feedback element comprises an LED, the LED may indicate that the determined speed of movement is “good” by emitting green light. The LED may indicate that the determined speed of movement is too fast by emitting orange light, and the LED may indicate that the determined speed of movement is too slow by red light. Alternatively / additionally, different LEDs may emit light in response to the detection that the determined speed of movement is within or outside (e.g., above or below) the predefined range.

[0097] Accordingly, the feedback element 32 can indicate to the user whether they need to increase, decrease or maintain the movement of the hair relative to the hair styling appliance 10. In this way, styling performance can be improved, the risk of damage to the hair may be reduced, and more efficient product usage can be encouraged. This may be particularly important for users who find it difficult to find and / or maintain and optimal pass speed (e.g., relative speed between the hair to be treated and the hair styling appliance), especially if a product is new to them or requires a different pass speed than products they have used in the past.

[0098] In some examples, e.g., where the feedback element 32 comprises a display screen, the display screen may display the determined speed or direction of movement of the hair relative to the hair styling appliance 10 itself. The predefined thresholds and ranges may be stored in storage 30. The predefined thresholds and / or ranges mat incorporate a degree of hysteresis or time-based filtering to smooth transitions between feedback states.

[0099] Instead of, or additionally to, providing user feedback via the feedback element 32 of the hair styling appliance itself, user feedback may be provided by a connected external device. Such external devices include mobile device, tablets and / or computers for example.

[0100] Accordingly, the hair styling appliance 10 may comprise a communication element 34 for communicatively coupling with an external device. The communication element may be a wireless transceiver configured to wirelessly communicate with the external device (mono- or bi-directionally), to transmit the information related to the determined speed of movement of the hair relative to the hair styling appliance 10 to the external device for display thereon. The external device may provide the information to the user visually, haptically, and / or audibly. In other embodiments, the communication between the communication element 34 and the external device may be a wired connection.

[0101] User feedback may also be provided to the user based on the information related to the determination about whether hair is present at the hair styling appliance, the determined pass start / end and / or pass length, or other information detected by the processor as described above. This user feedback may be provided in a corresponding manner to as described above. For example, an LED may flash red to indicate an incorrect hair feed angle for an intended curling style output and / or helix tightness.

[0102] As mentioned above, information or data related to the determined speed of movement of the hair relative to the hair styling appliance 10, information related to the determination about whether hair is present and the determines pass start / end and / or path length may be stored in storage 30. This data may be processed to generate historical and / or statistical produce usage information. This historical and / or statistical product usage information may then be provided to the user as user feedback, e.g., via the feedback element 32, and or via the communication element 34 and external device.

[0103] As mentioned above, the information related to the determined speed of movement of the hair relative to the hair styling appliance 10 can be used in the control of one or more functions of the hair styling appliance 10. The information related to the determination about whether hair is present at the hair styling appliance can also be used in this control.

[0104] The hair styling appliance 10 may comprise a hair treatment element 36 for treating the section of hair. An output of the hair treatment element 36 may be controlled, for example via a power controller 38, based on the information related to the determined speed of movement relative to the hair styling appliance 10, which may be stored in storage 30.

[0105] The hair treatment element 36 may comprise one or more of a heater for heating a section of hair, a blower or fan for generating and directing an airflow towards the section of hair, a dispenser for dispensing fluid and / or vapor towards the section of hair, and / or an actuator for vibrating the hair styling appliance 10, for example.

[0106] The heater may be a conduction, dielectric (RF / MF), FIR radiation or fan-forced convection heater, for example.

[0107] The power controller 38 may control the output of the hair treatment element 36 by controlling the power supplied, from power source 14, to the hair treatment element 36, based on the information related to the determined speed of movement relative to the hair styling appliance 10, the information related to the determination as to whether hair is present at the hair styling appliance 10, the determined pass start, pass end and / or pass length, and / or any of the other detected properties of the movement / hair described above. Controlling the output may include increasing or decreasing the power supplied, and / or switching the power on or off.

[0108] Controlling the output of a heater may include increasing or decreasing the temperature of the heater depending on the determined speed of movement. For example, the temperature could be increased as the determined speed of movement increases, and / or decreased as the determined speed of movement decreases. The applied power could be varied according to the determined temperature to maintain a constant amount of heat supplied to the hair. This may reduce the user skill required to achieve preferred styling results.

[0109] The application of energy to the hair, in particular with hair-heating technologies such as FIR or dielectric may be gated such that power is only supplied to the hair if it is determined that hair is moving relative to the hair styling appliance 10. For example, the output of the heater may be controlled such that power to the heater is switched off or reduced when the hair is stationary with respect to the hair styling appliance (and thus the determined relative speed of movement is zero or negligible), when the determined relative speed of movement is too low (and thus below a predefined threshold speed), and / or when no hair is present. This may avoid disrupting the hair on the approach towards the hair, and also results in a more energy efficient appliance.

[0110] Controlling the output of a heater may include varying the intensity of electromagnetic irradiation (e.g., IR light or microwave / radio frequency fields).

[0111] The power supplied to the other hair treatment elements may be controlled in a corresponding manner.

[0112] Controlling the output of a blower / fan may include varying the direction and / or velocity of the airflow. For example, the direction of airflow could be controlled depending on a detected orientation of the air styling appliance relative to the air; e.g., to ensure that airflow is always directed towards the tops of the hair rather than the roots.

[0113] Alternatively / additionally, airflow may be prevented (e.g., turned off) when the processor determines that the hair styling appliance is moving relative to the hair in the wrong direction, e.g. from tip to root.

[0114] Controlling the output of a dispenser may include varying the dispensing rate and / or diffusion / concentration / profile of an emission. For example, a rate of formulation dispensing (e.g., colourants, bleaches, relaxers, conditioners or styling aids) or water (e.g., mist or steam spray) to the hair may be controlled.

[0115] The output of the hair treatment element 36 may be controlled based on the stored historical and / or statistical produce usage information. For example, the power supplied to the hair treatment element 36 may be controlled based on a user’s average relative speed of movement to better suit the user, e.g., increm ent / decrem ent heater power levels based on average pass length or average speed. This information may also be used to make predictive changes to the output of the hair treatment element 36, e.g., to increase heat towards the tips of the hair. The image(s) of the hair acquired by the optical sensor may undergo additional processing techniques. In particular, the processor 24 may determine angle of the section of hair relative to the hair styling appliance, strand alignment / straightness, damage, shine, type and / or colour of the hair based on one or more measurements of the optical sensor. This further information may be provided to the user as user feedback, in a corresponding manner to as described above and / or used in the control of the hair styling appliance, as described above.

[0116] Figure 14 illustrates how these properties can be determined from both high-resolution camera images (e.g., the upper images in Figure 14) and low-resolution optical flow sensor images (e.g., the lower images in Figure 14).

[0117] In particular, from both the upper high-resolution image and lower low-resolution image labelled a) in Figure 14, it can be determined that the hair has a dark colour, with low alignment, having mixed angled (e.g., coil hair type), and with thick hair strands. From both the upper high-resolution image and lower low-resolution image labelled b) in Figure 14, it can be determined that the hair has a dark colour, with high alignment, a shallow positive angle, and thick hair strands. From both the upper high-resolution image and lower low-resolution image labelled a) in Figure 14, it can be determined that the hair has a light colour, is highly aligned, has a steep negative angle, and fine / narrow strands.

[0118] To determine an angle of one or more strands of hair in the section of hair relative to the hair styling appliance, edge points of hair strands may be emphasised by applying a predefined threshold to an image of the section of hair (e.g., a measurement by the optical sensor of the light received from the section of hair being styled). The predefined threshold may be applied based on pixel intensity. One or more lines may then be extracted using one or more machine learning, pattern recognition, or image processing feature extraction techniques. For example, the “Hough transform” method may be used to identify lines in the image by determining, based on an extent to which neighbouring pixels (of a given edge point) confirm to a straight-line formula (e.g., y = mx + c). As the orientation of the image frame relative to the hair styling appliance is known (as the optical sensor is fixed relative to the appliance) trigonometry may be used to provide the angle of the strands based on the gradient of detected line(s). A strand-to-stand alignment metric may be calculated by applying statistical analysis to all the line angles identified in the image.

[0119] A type of hair (e.g., curly or straight) may also be determined from the extracted lines, e.g., by measuring a deviation of edge points along the detected straight lines. Less deviation from the detected straight lines may indicate straighter hair, for example.

[0120] Although not shown in Figure 1, the hair styling appliance 10 may comprise a time-of- flight or proximity sensor, which may be used in combination with the optical sensor 20 to apply a correction factor for calibrating relative speed measurements to an offset distance between the optical sensor 20 and the hair. This may be particularly useful when the offset distance between the optical sensor 20 and the hair is unconstrained relative to the hair styling appliance, and thus highly variable during use, for example, with a hair dryer.

[0121] The hair styling appliance 10 may comprise an inertial sensor, which may include one or more accelerometers and / or gyroscopes (not shown in Figure 1). The inertial sensor may be used in combination with the optical sensor 20 to improve measurement accuracy and / or to provide additional spatial referencing. For example, the inertial sensor may be able to detect extreme or sudden movement speeds more accurately (e.g., compared to the optical sensor 20), and / or may provide real-world spatial reference points to the relative motion between the section of hair and the hair styling appliance 10.

[0122] For example, a signal from the optical sensor 20 may be subject to interruptions, e.g., due to hair not being in front of the optical sensor 20, varying distance between the section of hair and the optical sensor 20, or other factors. In order to improve the quality of position (and / or speed of movement) data determined, measurements from the optical sensor 20 may be combined with measurements from the inertial sensor. The measurements from the inertial sensor may include acceleration data in 6 degrees of freedom, in particular angular acceleration on the xy, yz, and xz planes, and linear acceleration in the x, y and z directions. The combination of x, y and z acceleration (from gravity) and the first integral of the angular xy, yz, and xz angular accelerations can be used to precisely track the orientation of the hair styling appliance 10 relative to the Earth. Gravity may be considered a proxy for absolute down. Additionally, the use of magnetic field strength may be used to provide an additional source of absolute position. The magnetic field strength may be at least in part a measure of the Earth’s magnetic field but could also combine other local magnetic field sources. The combination of the first integral of x, y and z data and the determined speeds / velocities from the optical sensor 20 may provide an improved determined of the speed / velocity of the hair styling appliance 10. This may be further integrated to provide an indication of the hair styling appliance’s absolute location. A Kalman filter may be used to combine the sensor readings.

[0123] The optical sensor may be positioned proximally to the treated hair surface in use, and orientated such that the tress / section of hair undergoing treatment is within a field of view (FOV) of the optical sensor 120. The light source may also be positioned proximally to the treated hair surface in use, and orientated such that the tress / section of hair undergoing treatment is within a field of illumination (FOI) of the light source.

[0124] As mentioned above, the hair styling appliance 10 may be a hair straightener, such as hair straightener 110a-l lOd shown in Figures 2a, 2b, 3 and 4, respectively. In use, hair is fed between two arms 140 to apply treatment (e.g., heat). The arms 140 may be movable relative to one another, allowing the application of a clamping force to the hair positioned between the arms 140.

[0125] The optical sensor 20 and / or light source 18 may be located within a clamping or treatment portion of the hair styling appliance 10.

[0126] The hair styling appliance 10 may be a conduction hot plate straightener, such as the hair straighteners 110a, 110b shown in Figures 2a and 2b, respectively. As such, the hair treatment element 36 may comprise one or more conduction / hot plates 142. The one or more conduction / hot plates 142 form one or more clamping surfaces. Each arm 142 may have an opposing conduction / hot plate, such that when the arms 142 are clamped together with hair therebetween, the hair is clamped between the two conduction / hot plates 142.

[0127] The hair styling appliance 10 may be a dielectric heater straightener, such as hair straightener 110c shown in Figure 3. As such the hair treatment element may comprise one or more electrode tracks 144 for dielectric heating. The electrode track(s) 144 may be positioned on one or more clamping surfaces. The hair styling appliance 10 may be an IR heater straightener, such as hair straightener 1 lOd shown in Figure 4. As such the hair treatment element may comprise an IR emitter 146, e.g., a plurality of tungsten halogen bulbs / lamps. The IR emitter 146 may be positioned on one or more clamping surfaces.

[0128] The optical sensor 20 and / or light source may be positioned adjacent to the clamping surface, see e.g., Figure 2a where a plurality of optical sensors 20 are located adjacent to one of the conduction / hot plates 142 along one arm 140 of the straightener, and Figures 3 and 4 where a plurality of optical sensors are located adjacent to the electrode track 144 / IR emitter 146. Although not shown in Figures 2a, 3 and 4, the light sources 18 may be positioned on the other arm (and the measured light is thus attenuated light through the hair), or the light sources 18 may be positioned adjacent to the optical sensors 20 (and the measured light is thus light reflected from the hair).

[0129] The optical sensor and / or light source may be positioned within the hair clamping surface, see e.g., Figure 2b where a single optical sensor 20 is positioned within a conduction / hot plate 142. The optical sensor 120 and / or light source may be centred within the conduction / hot plate, for example.

[0130] The optical sensor(s) 20 and / or light source 18 may be flush with the hair clamping surface, such that they form part of the hair clamping surface. Alternatively, the optical sensor(s) 20 and / or light source 18 may be recessed from the hair clamping surface to avoid direct contact with the hair.

[0131] The offset distance between the section of hair and the optical sensor(s) 20 may be substantially constrained. In hair straighteners, this may be provided by the two arms clamping together to hold the hair at a fixed distance from the optical sensor 20. In these examples, the hair may be held against a window (transmissive to the wavelength of light used for illuminating the hair) positioned at a fixed distance from the optical sensor 20. The hair may be held a fixed difference away by recessing the optical sensor 20 / light source 18 from the hair clamping surface, as described above. Providing the optical sensor a fixed distance away from the window can ensure that FOI and FOV overlap. If the offset distance is not constrained, inclusion of a time of flight or proximity sensor may be useful, as described above.

[0132] When the hair styling appliance is a hair straightener comprising two arms, the optical flow sensing system 12 may perform an additional function of determining whether the arms are in a closed state or an open state, as well as for detecting presence of the hair. This information may be fed back to the user as user feedback, or used to control the hair styling appliance 10, in a corresponding manner to as described above.

[0133] The hair styling appliance may be a hair styler such as a hair curler, for example hair curlers 160a and 160b shown in Figures 5 and 6, respectively. Figures 5 and 6 show different types of hair curler comprising a blower for styling hair, e.g., wrapping hair around a hair-contact barrel 162. The optical sensor 20 and light source 18 may be positioned at a surface of the hair-contact barrel 162. The hair-contact barrel may comprise a plurality of optical sensors 20, as shown in Figure 5. With some hair curlers, such as hair curler 160b, the user may be able to adjust the direction of airflow.

[0134] Figures 7a and 7b show cross-sections of a hair curler 160b comprising a blower for styling hair, e.g., wrapping hair around the hair-contact barrel 162. The direction of airflow is shown by arrows 164, with the direction of airflow in Figure 7b being the opposite to that in Figure 7a. A valve 166 may be provided for redirecting the airflow. The valve 166 may be actuated in response to hair movement direction, for example.

[0135] The hair styling appliance may be a hair styler such as a hairbrush, for example the hairbrushes 180a and 180b shown in Figures 8 and 9, respectively. The hairbrush may be a barrel brush, such as barrel brush 180a shown in Figure 8, or a paddle brush, such as paddle brush 180b shown in Figure 9. The hairbrush 180a, 180b may comprise a plurality of brush bristles 182 extending from a main body 184, wherein the bristles 182 act to detangle the hair. The bristles 182 may also hold the hair against the main body 184, and thus against the optical sensor 20. The hairbrush 180a, 180b may comprise an actuator 186 e.g., for vibrating the hairbrush 180a, 180b as a detangling aid, or a fluid-dispensing system for example. The hairbrush 180a, 180b may comprise a heater for heating the hair, and / or a blower for styling the hair. An enlarged view of an optical sensor 20 and light source 18 arrangement 200 is shown in Figure 10. This arrangement 200 may be the optical sensor and light source arrangement in a hair straightener, for example. It may also be an arrangement for another type of hair styling appliance 10 such as a hair curler, dryer, or brush, but this may have one or more modifications, as described below.

[0136] The optical sensor 20 is positioned adjacent to the light source 18 within sensor casing 202. The light source in the example shown in Figure 10 is a laser, e.g., a Vertical-cavity Surface-emitting Laser (VCSEL). The optical sensor 20 in the example shown in Figure 10 is a CMOS. The casing 202 may be supported and electrically connected to a PCB 212.

[0137] The optical sensor 20 and light source 18 may be positioned behind two separate windows 204 in the casing 202 in order to prevent cross-talk and / or to offer different wavelength filtering.

[0138] During use, and as shown in Figure 10, a section of hair 208, comprising a hair tress with a plurality of hair strands, is positioned between two hair contact surfaces 210a, 210b, which act as clamping surfaces. The hair is thus clamped in positioned relative to the optical sensor 20 and light source 18. In other examples where the hair styling appliance 10 does not comprise two clamping surfaces, only one contact surface 210a may be present. The section of hair 208 may be held against the contact surface 210a, e.g., by an airflow from a blower, or by one or more brush bristles, for example.

[0139] The light source 18 and optical sensor 20 may be positioned behind a window 214, or a gap, in the contact surface 210a in order to have line of sight through the contact surface 210a. A window 214 may help to control the offset between the hair and the optical sensor 20 and / or prevent ingress of hair into the gap.

[0140] An example of an arrangement 250 of an optical sensor 20 and light source 18 in a hair styling appliance 10, which has only one contact surface 210a, is shown in Figure 11. As described above, optical components 28 may be positioned in the optical paths of the light source 18 and optical sensor 20, as shown in Figure 11.

[0141] In some examples, the optical flow sensing system 12 may measure the speed of movement of the section of hair relative to the hair styling appliance using other non- contact sensing technologies such as Laser Doppler Velocimetry. Laser Doppler Velocimetry sensors may measure the emitted laser light relative to a shifted phase modulation of the reflected light.

[0142] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0143] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0144] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0145] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0146] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0147] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

CLAIMS1. A hair styling appliance comprising: an optical sensor configured to make two or more measurements of light received from a section of hair being styled by the hair styling appliance; and a processor configured to determine a speed of movement of the section of hair relative to the hair styling appliance based on the two or more measurements.

2. A hair styling appliance according to claim 1, wherein the hair styling appliance further comprises a light source configured to illuminate the section of hair being styled by the hair styling appliance, wherein the light received from the section of hair comprises light emitted from the light source, and reflected or attenuated by the section of hair.

3. A hair styling appliance according to any preceding claim, wherein the hair styling appliance performs a straightening, curling, styling and / or drying function.

4. A hair styling appliance according to any preceding claim, wherein: the two or more measurements comprise at least a first image and a second image, the second image taken sequentially to the first image; and the processor is configured to determine a speed of movement of the section of hair relative to the hair styling appliance by: comparing the first and the second images; and determining a speed of movement of the section of hair across the optical sensor in at least one direction based on a comparison of the first and second images.

5. A hair styling appliance according to any preceding claim, wherein the optical sensor comprises one or more of a CMOS sensor, a camera, and / or an array of photosensors.

6. A hair styling appliance according to any preceding claim, further comprising a hair treatment element configured to treat the section of hair, wherein the processor isfurther configured to control an output of the hair treatment element based on the determined speed of movement of the section of hair relative to the hair styling appliance.

7. A hair styling appliance according to claim 6, wherein the hair treatment element comprises a heater for heating the section of hair, a blower for generating and directing an airflow towards the section of hair, and / or a dispenser for dispensing fluid and / or vapor towards the section of hair.

8. A hair styling appliance according to claim 6 or claim 7, wherein the processor is configured to control the output of the hair treatment element by controlling the power supplied to the hair treatment element based on the determined speed of movement of the section of hair relative to the hair styling appliance.

9. A hair styling appliance according to any preceding claim, wherein the processor is configured to output a feedback signal for providing user feedback related to the determined speed of the section of hair relative to the hair styling appliance.

10. A hair styling appliance according to claim 9, wherein the hair styling appliance further comprises a feedback element configured to provide visual, audible and / or haptic feedback to a user based on the feedback signal output from the processor.

11. A hair styling appliance according to claim 9 or claim 10, wherein the processor is configured to compare the determined speed of movement of the section of hair relative to the hair styling appliance to at least one predefined threshold, and to output the feedback signal based on the comparison of the determined speed and the at least one predefined threshold.

12. A hair styling appliance according to any of claims 9-11, further comprising a communication element for communicatively coupling with an external device, and wherein the processor is configured to output the signal for providing user feedback to the external device, for display to the user thereon.

13. A hair styling appliance according to any preceding claim, wherein the processor is configured to determine a two-dimensional velocity of the section of hair relative to the hair styling appliance based on at least two measurements of the optical sensor.

14. A hair styling appliance according to any preceding claim, further comprising an optical component for directing, distributing, focussing and / or magnifying the light received from the section of hair at the optical sensor.

15. A hair styling appliance according to any preceding claim, wherein the processor is configured to determine a direction of the relative movement between the section of hair being styled and the hair styling appliance, and / or an angle of one or more strands of hair in the section of hair being styled relative to the hair styling appliance, based on at least two measurements of the optical sensor.

16. A hair styling appliance according to any preceding claim, wherein the processor is configured to determine whether hair is present at the hair styling appliance for styling based on at least one measurement of the optical sensor.

17. A hair styling appliance according to any preceding claim, wherein the processor is configured to determine a start and / or end of styling of the section of hair based on a plurality of measurements by the optical sensor.

18. A hair styling appliance according to any preceding claim, wherein the optical sensor is orientated and / or positioned on the hair styling appliance such that at least a portion of the section of hair being styled by the hair styling appliance is within a field of view of the optical sensor.

19. A hair styling appliance according to any preceding claim, further comprising a time-of-flight and / or proximity sensor for determining a distance between the hair styling appliance and the section of hair being styled.

Images