Patent Description:
It is known to provide personal care devices with the ability or functionality to capture digital impressions (e.g. images) of a feature or part of a user during use. For example, Intra-Oral Scanner (IOS) devices use projected light (e.g. laser or structured light) and an image sensor to capture images of the dentogingival tissues. These images can be processed to create a three-dimensional (3D) model of the scanned surface. Data provided by IOS can therefore be useful for oral care, including the detection of common dental pathologies such as caries, tooth discoloration, misalignment. Also, it may be advantageous to capture and compare repeated IOS images, to enable identification of changes in dentogingival tissues over time for example.

Because personal care devices, such as electric brushing or shaving devices, are used on a regular (e.g. daily) basis, they may provide a suitable vehicle to regularly capture images of a part of a user. Accordingly, there is trend to integrate cameras or imaging sensors into personal care devices, such as toothbrushes for example. However, because a main usage characteristic of such a personal care device may be its vibration or cyclical/periodic movement, images acquired by an image capture device integrated with a personal care device are typically distorted and/or blurred by the movement/vibration of the device.

Although image stabilization techniques are known for portable handheld devices (e.g. smart phone, digital photo cameras, etc.), such techniques are only designed and optimized for low frequency (e.g. <<NUM>), erratic (e.g. non-periodic, random, etc.) user-induced motions. Because a personal care device (such as a toothbrush) typically moves or vibrates at a much higher periodic frequency (e.g. ><NUM>-<NUM>), there remains a need to stabilize the image capture process and/or make the image acquisition process robust to device movements/vibrations generated by a personal care device.

<CIT> discloses an electrical hand-held device for body treatment, having a treatment part for performing at least one electrically operated body treatment function, and having a handle body for holding the hand-held device. which further includes an electronic component for controlling the at least one electrically operated body treatment function.

According to examples in accordance with an aspect of the invention, there is provided a personal care device comprising:.

Proposed concepts thus aim to provide schemes, solutions, concepts, designs, methods and systems pertaining to aiding and/or improving image acquisition from a vibratory personal care device having an image capture device the image of which is influenced by the device vibration. This may either be a camera fixed rigidly to the vibrating device which may then vibrate with the device. Alternatively the camera sensor itself may be situated in a stationary part of a device (e.g. a brush handle) whilst the optical system of the device (like an optical fiber, the imaging lens of the optical system) are subject to the device vibrations. In particular, embodiments of the invention propose identifying a target part (e.g. low velocity/motion part) of the vibration cycle based on a sensed operating parameter of the personal care device, and then controlling the image capture device based on the identified target part of the vibration cycle. Through control of the image capture device according to a target part of the vibration cycle, improved images (e.g. images exhibiting less blur and/or distortion) may be obtained. In this way, improved images may be obtained from a vibratory personal care device.

In particular, it is proposed that, to reduce or minimize distortions in images acquired from vibrating personal care device (in use), timing and/or settings of the image capture device may be adapted based on the vibration cycle. For instance, a timing of image data capture by the image capture device may be synchronised with the target part of the vibration cycle, thus ensuring the image data capture only occurs during a preferred or optimal part of the vibration cycle.

It is also proposed to determine the target part of the vibration cycle by sensing operation of the personal care device. By way of example, a movement and/or a drive signal of the vibratory means may be monitored and then analysed to determine a period/portion of the vibration cycle which exhibits low/zero motion of the personal care device.

In other words, embodiments propose to adapt image capture based on one or more sensed operating parameters of the personal care device, so as to provide images of improved quality and/or enable the use of simpler/cheaper image capturing devices. Embodiments may therefore facilitate stable and high-quality image acquisition during tooth brushing. Such embodiments may be particulalry relevant to teledentistry propositions, for example, by enabling improved imaging of a user's tooth, gum, tongue, etc. For instance, images obtained by proposed embodiments may aid dental care treatments and/or decision making. Accordingly, embodiments may be used in relation to dental treatment selection so as to support a dental care professional when selecting treatment for a subject.

Further, embodiments may facilitate image-based diagnostics, superior location sensing, therapy planning (e.g. orthodontics, aligners) and/or dental treatment monitoring.

By being integrated into the normal brushing regimen of a user (instead of using separate devices such as smart phones, dental endo-scopes or handheld intraoral scanners, embodiments may support improved dental care. Improved image-based dental care may therefore be provided by proposed concepts.

It has been realized that by controlling image capture device based on target part of the vibration cycle of the personal care device, higher quality images (in terms of reduced blur and/or distortion) may be obtained, thus aiding oral/dental care decision making.

Embodiments may therefore provide the advantage that decision making in selecting an oral care treatment can be improved through the use of images captured by a virbatory personal care device. For example, embodiments may enable a larger number of oral care treatment options to be available (e. g through the provision of more and/or improved information about a subjectt's oral health).

The image capture device may comprise an illumination device configured, in use, to illuminate a part of the user's oral cavity. The control unit may then also be adapted to control the image capture device to synchronise a timing of illumination with the target part of the vibration cycle. This will help to ensure adequate lighting conditions for reducing image blur and/or distortion whilst ensuring sufficient total illumination. It may also help to reduce power consumption by restricting illumination to only occur at certain times. That is, activation of the illumination device for unnecessary time periods where for example during the high speed motion and thus harder to capture bright and clear images in that period may be avoided.

In some embodiments, the image capture device may comprise a camera, and the control unit may be adapted to synchronise signal acquisition from the camera with the target part of the vibration cycle. Embodiments may thus be employed in conjunction with different types of image capture devices, including, for example, global shutter cameras or free-running rolling shutter cameras that are out of synchronisation with vibration of the personal care device (and the image capture device). For example, by timing exposure or data acquisition of/from the camera based on the target part of the vibration cycle, image data that is sharp and clear may be acquired. This image data may be combined with image data from different portions of different frames of the camera, thus facilitating construction of a single high quality image (from a plurality of captured frames).

In an exemplary embodiment, the control unit may be adapted to control the image capture device to synchronise a timing of image capture with the determined target part of the vibration cycle. For instance, the start/beginning of an exposure window (i.e. the timing of the start of the exposure period) may be aligned with the timing of a low angular velocity of the personal care device during its vibration cycle. Such a concept of synchronizing image capture with a low velocity period/window in the vibration cycle of the personal care device may further reduce blur and/or distortion in captured images.

In some embodiments, the control unit may be configured to generate a timestamp based on the target part of the vibration cycle, the timestamp being configured to identify a timing of the target part of the vibration cycle. Embodiments may thus provide a concept for identifying the timing of the target part of the vibrations, thereby assisting synchronisation with the target part of the vibration cycle. Such a concept is particularly useful in combination with free running image capture devices.

In some embodiments, the control unit may also be configured to control an exposure parameter of the image capture device based on the target part of the vibration cycle. For instance, the exposure parameter may comprise an exposure duration of the image capture device, and the control unit may then be adapted to set the image capture exposure duration. In this way, exposure of the image capture device may be set to be fast enough relative to the camera vibration to reduce or minimise image distortion or bur. That is, the image capture exposure time may be set to be less than or equivalent to the duration/period of minimal motion of the personal care device.

In an embodiment, the vibratory means may comprise a vibrator, and the sensor arrangement may comprise a drive sensor adapted to sense a drive signal of the vibrator. The control unit may then be adapted to determine the target part of the vibration cycle based on a time period when then sensed drive signal meets a predetermined drive signal requirement. For instance, the sensed drive signal may be representative of a drive current or voltage of the vibrator, and the predetermined drive signal requirement may be that the magnitude of the drive current or voltage cross a threshold value. For example the drive current may exceed a threshold, the drive voltage may fall below a threshold, etc. In this way, sensing of the drive signal may be employed to determine the target part of the vibration cycle (e.g. identify the timing of a low velocity period within the vibration cycle). Simple voltage or current monitoring techniques may therefore be employed to accurately identify the timing(s) of low velocity of the personal care device.

In some embodiments, the sensor arrangement may comprise a movement sensor adapted to sense an angular velocity of a part of the personal care device. The control unit may then be adapted to determine the target part of the vibration cycle based on a time period when the sensed angular velocity meets a predetermined velocity requirement. For instance, the predetermined velocity requirement may be that the magnitude of the sensed angular velocity does not exceed a threshold value. Thus, movement/motion sensing concepts may be employed to determine the target part of the vibration cycle (e.g. identify the timing of a low velocity period within the vibration cycle). Simple movement sensing techniques and/or apparatus may therefore be employed to accurately identify the timing(s) of low velocity of the personal care device.

In an embodiment, the sensor arrangement may comprise a hall sensor adapted to sense a magnetic field at a part of the personal care device. The control unit may then be adapted to determine the target part of the vibration cycle based on a time period when then sensed magnetic field meets a predetermined magnetic field requirement. Sensing of the magnetic field may thus be employed to determine the target part of the vibration cycle (e.g. identify the timing of a low velocity period within the vibration cycle). Existing hall sensors that are already integrated within conventional personal care devices may therefore be leveraged to provide new and/or extended functionality, for example.

In other embodiments, the sensor arrangement comprises a vibration sensor adapted to sense an acceleration or excursion of a vibration of a part of the personal care device. The control unit may then be adapted to determine the target part of the vibration cycle based on a time period when the magnitude of the sensed vibration meets a predetermined acceleration or excursion requirement. For instance, the predetermined acceleration or excursion requirement may be that the acceleration of the sensed vibration exceeds a vibration threshold value. Similarly the low speed is usually associated with the extremities of the motion, whereby the predetermined acceleration or excursion requirement may be that the excursion of the sensed vibration exceeds a vibration threshold value. Thus, vibration sensing concepts/apparatus may be employed to determine the target part of the vibration cycle (e.g. identify the timing of a low velocity period within the vibration cycle). Existing and/or simple vibration sensing techniques and/or apparatus may therefore be employed to accurately identify the timing(s) of low velocity of the personal care device.

Whilst the above is also relevant for a vibration sensor adapted to sense an acceleration or excursion positioned on the brush head it is clearly possible that the sensor is positioned in a brush handle. This may result in a more complex motion of the vibration sensor. However in this case also determining the low velocity periods will be possible using other predetermined requirements of the acceleration and/or excursion, which whilst complex will in general remain periodic in nature.

The personal care device may comprise a toothbrush, and may preferably comprise an oral care device (such as an electric toothbrush) that is adapted to vibrate in use. In other embodiments, the personal care device may comprise a mouthpiece, shaver, or skin cleansing device that is adapted to vibrate in use. One or more proposed concept(s) may therefore be employed in a range of different personal care devices. Embodiments may therefore have wide application in the field of personal care devices (and image capture and/or processing concepts for images captured by vibratory personal care devices).

According to another aspect of the invention, there is provided a method of controlling a personal care device, wherein the personal care device comprises: an image capture device adapted, in use, to capture images of one or more features of a user; vibratory means adapted to vibrate the personal care device so that, in use, the personal care device vibrates with a vibration cycle having a vibration frequency; and a sensor arrangement adapted to sense an operating parameter of the personal care device, and wherein the method comprises: determining a target part of the vibration cycle based on the sensed operating parameter; and controlling the image capture device based on the determined target part of the vibration cycle.

According to yet another aspect of the invention, there is provided a computer program comprising computer program code means which is adapted, when said computer program is run on a computer, to implement a method according to proposed embodiment.

Thus, there may also be provided a computer system comprising: a computer program product according to proposed embodiment; and one or more processors adapted to perform a method according to a proposed concept by execution of the computer-readable program code of said computer program product.

The invention proposes concepts for aiding and/or improving image acquisition from a vibratory personal care device having an image capture device. In particular, embodiments may provide a system, device and/or method which identifies a target part of the vibration cycle based on an operation of the personal care device. Control of the image capture device is then undertaken according to the identified target part of the vibration cycle. Through such control of the image capture device, improved images (e.g. images exhibiting less blur and/or distortion) may be obtained.

In particular, it is proposed that, to reduce or minimize distortions in images acquired from a vibrating personal care device, the image capture device may be adapted according to the vibration cycle of the vibrating personal care device (in use). More specifically, it has been realised that one or more parts of the vibration cycle may be better suited to image capture, for example due to exhibiting reduced motion/movement. It has further been realised that the timing(s) of such a part of the vibration cycle preferred (or optimal) for image capture may be determined based on operating parameters of the personal care device. Examples of such operating parameters include: vibrator/motor current or voltage; magnetic field; device motion; and angular velocity of a part of the personal care device. Simple detection of an operation of the personal care device to determine a preferred, optimal or target timing of image capture may therefore be employed, thus enabling improved or optimised image capture.

In other words, embodiments propose to adapt image acquistion to the vibration of the personal care device, so as to provide images of improved quality.

Embodiments may therefore facilitate stable and high-quality image acquisition during tooth brushing. Such embodiments may be particulary relevant to teledentistry propositions, for example, by enabling improved imaging of a user's tooth, gum, tongue, etc. For instance, images obtained by proposed embodiments may aid dental care treatments and/or decision making. Accordingly, embodiments may be used in relation to dental treatment selection so as support a dental care professional when selecting treatment for a subject.

Referring to <FIG>, there is shown a simplified schematic block diagram of an electric toothbrush <NUM> according to a proposed embodiment. The electric toothbrush <NUM> comprises vibratory means <NUM> (specifically, a motor) that is adapted, in use, to vibrate a brush head <NUM> of the electric toothbrush <NUM> (with a frequency of about <NUM>).

The electric toothbrush <NUM> also comprises an image capture device <NUM> (e.g. digital camera) that is adapted, in use, to capture images of one or more oral features of a user. The electric toothbrush <NUM> is also provided with a sensor arrangement <NUM> that is adapted to sense an operating parameter of the personal care device, and a control unit <NUM> that is adapted to control the image capture device based on the target part of the vibration cycle.

More specifically, the motor <NUM> is configured to cause the brush head <NUM> to repeatedly rotate clockwise then anti-clockwise by around <NUM>°-<NUM>° from a rest position in a periodic manner. In this way, the brush head <NUM> vibrates with a periodic vibration waveform.

By way of further illustration, <FIG> depicts a graph showing an exemplary variation in angle θ (of displacement) and angular velocity of the brush head <NUM> over time as the brush head <NUM> vibrates. The variation in displacement angle θ of the brush head <NUM> is depicted by the solid line, whereas the variation in angular velocity v of the brush head <NUM> is depicted by the dashed line.

It is seen from the variations depicted in <FIG> that 'low speed' periods <NUM>, i.e. time periods wherein the magnitude of angular velocity v of the brush head <NUM> is below a threshold value Vth, can be identified. More specifically, it is seen that, when the magnitude of the displacement angle θ reaches a maximum value, such that the gradient of displacement angle θ variation changes polarity (i.e. when the solid line changes direction), the angular velocity v of the brush head <NUM> is near-zero. It is proposed that these low speed periods <NUM> provide the most appropriate opportunities for image capture using an image capture device that may have limited speed and exposure tuning capabilities. Accordingly, embodiments are based on the concept(s) that timing and/or settings of the image capture device may be adapted according to the vibration cycle of the brush <NUM>. For instance, one or more exposure settings of the image capture device <NUM> may be controlled based on the vibration cycle of the brush <NUM>. That is, embodiments propose to adapt image acquistion to the vibration of the personal care device, so as to provide images of improved quality.

<FIG> depicts graphs showing the variations in motor signals and motor current for the variations of brush head <NUM> shown in <FIG>. The motor control signal is a (substantially) square wave signal. It is seen that the motor signal is "on" during the low speed periods <NUM> (e.g. when reversing the rotation angle movement direction of the brush head). From the bottom graph of <FIG>, it is seen that the current is also related to the angular velocity: a high current peak represents the reversing of the rotation angle movement direction and getting it up to speed again; and a following (substantially) flat phase represents where the speed is kept constant;.

Often in electronic drive arrangements, a peak in drive current is associated with a small dip in the drive voltage. For this reason also the drive voltage may be advantageously used to identify low speed periods.

In this example it is realised that the low speed period is related to the motor "on" signal, and the period of no speed is related to the peak current.

Accordingly, it is proposed that an operating parameter of the personal care device can be sensed/monitored to determine a timing of preferred, optimal or target period of image capture, such as the timing of the low speed periods <NUM> of the vibration cycle. As shown in <FIG>, the operating parameter may comprise the motor <NUM> current (or signal) and, for this reason, the sensor arrangement <NUM> of the embodiment of <FIG> comprises a drive sensor adapted to sense a drive signal of the vibrator, wherein the sensed drive signal is representative of a drive current or voltage of the vibrator.

Referring back to the embodiment of <FIG>, the control unit <NUM> is adapted to determine the target part of the vibration cycle based on a time period when the sensed drive signal meets a predetermined requirement. Specifically, the predetermined requirement is that the magnitude of the drive current or voltage cross a threshold value. For example the drive current may exceed a threshold, the drive voltage may fall below a threshold etc. In this way, the target part of the vibration cycle is design to coincide with a low speed period <NUM> of the vibration cycle.

The control unit <NUM> is then adapted to control the image capture device <NUM> based on the target part of the vibration cycle. Specifically, in this example, the control unit is adapted to control the image capture device <NUM> to synchronise a timing of image capture with the target part (i.e. low speed period <NUM>) of the vibration cycle. The image capture device <NUM> is thus controlled so that image capture is synchronised with the low speed periods <NUM>, thereby reducing an amount of movement that may cause blurring and/or distortion in a captured image.

To aid reduction in the exposure duration that is required to capture an adequately exposed image, the image capture device <NUM> of the embodiment of <FIG> comprises illumination devices <NUM> (e.g. LEDs, lasers) that are configured, in use, to illuminate a part of the user's oral cavity. That is, where the sensitivity (e.g. ISO) and/or the lens aperture of the image capture device <NUM> may be fixed and/or limited, a reduction in the required length of exposure to capture an adequate amount of light may be obtained through illumination of the user's oral cavity by the illumination devices <NUM>. Further, the control unit <NUM> of this exemplary embodiment is adapted to control the image capture device <NUM> to synchronise a timing of illumination by the illumination devices <NUM> with the vibration cycle. For instance, the illumination by the illumination devices <NUM> may be synchronised with the low speed periods <NUM>. This may help to reduce or minimise power consumption whilst still ensuring suitable illumination to facilitate a reduced/shortened exposure duration of the image capture device <NUM> during the low speed periods. In other embodiments, however, the illumination devices <NUM> may be controlled to provide continuous illumination, e.g. illumination may be provided by the illumination devices <NUM> for the duration of the vibration cycle.

Although the embodiment of <FIG> has been described as employing a brush head <NUM> that repeatedly rotates clockwise then anti-clockwise by around <NUM>°-<NUM>° from a rest position in a periodic manner, it will be appreciated that other embodiments may employ a brush head that vibrates in a different manner. For instance, alternative embodiments may comprise a brush head that rotates or that shakes (left and right, or up and down) repeatedly, i.e. repeatedly displaces (laterally or vertically) in opposite directions from a rest position. Such embodiments will still exhibit a cyclical vibration pattern having variations in displacement and velocity over time that form periodic waveforms as depicted in <FIG>, and thus have repeating 'low speed' periods that are identifiable (e.g. according to the drive parameters and/or control of the vibratory means).

That is, although the proposed concept(s) have been described above with reference to rotating / angular motion of the vibrating part of the personal care device, the proposed concept(s) may be employed in other vibratory personal care devices exhibiting repetitive vibratory motion. Also, in case of multi-dimensional motion, periods of low/zero speed may be identified with respect to multiple dimensions and used to control one or more exposure parameters of the image capture device.

Also, although the embodiment of <FIG> employs a concept of identifying periods of low or no angular velocity by monitoring the motor drive signal (e.g. drive current or voltage), other parameters of the personal care device may be monitored to identify the vibration cycle (and thus infer the target part of the vibration cycle). Examples of other parameters that may be monitored include: magnetic field; device motion; and angular velocity of a part of the personal care device. Simple detection of an operation of the personal care device to determine a preferred, optimal or target timing of image capture may therefore be employed, thus enabling improved or optimised image capture.

Simply by way of example, in a modified version of the embodiment of <FIG>, the sensor arrangement comprises a movement sensor that is adapted to sense an angular velocity of a part of the personal care device. Such a sensor can be a gyroscope, compass or other angular sensing device. The sensor arrangement may also comprise an accelerometer/vibration sensor positioned in the handle of the personal care device for determining the frequency of motion and phase. The control unit is then adapted to determine the target part of the vibration cycle based on a time period when then sensed angular velocity meets a predetermined velocity requirement. For instance, the predetermined velocity requirement may be that the magnitude of the sensed angular velocity does not exceed a velocity threshold value, thus identifying the low speed periods <NUM> of the vibration cycle by sensing an angular velocity of a part of the personal care device.

In another example, the sensor arrangement may comprise a hall sensor that is adapted to sense a magnetic field at a part of the personal care device. The control unit may then be adapted to determine the target part of the vibration cycle based on a time period when then sensed magnetic field meets a predetermined magnetic field requirement. Thus, an existing hall sensor that is already integrated within a conventional personal care device may be leveraged to provide new, improved and/or extended functionality.

Referring to <FIG>, there is shown a simplified schematic block diagram of a mouthpiece <NUM> according to another embodiment. The mouthpiece <NUM> is adapted to be inserted into a user's mouth and vibrate (in use) for oral cleaning purposes.

The mouthpiece <NUM> comprises vibratory means <NUM> (specifically, an electric motor) that is adapted, in use, to cause the mouthpiece to vibrate with periodic vibration waveform (having a frequency in the range of <NUM>-<NUM>).

The mouthpiece <NUM> also comprises an image capture device <NUM> positioned in the tray of the mouthpiece and adapted, in use, to capture images of one or more oral features of the user. A flash LED <NUM> is also provided in the tray of the mouthpiece for illuminating the oral cavity of the user, in use. The image capture device <NUM> and LED <NUM> are configured to be controlled by a control unit (i.e. controller) <NUM> of the mouthpiece.

In particular, the control unit <NUM> is configured to control an exposure parameter of the camera <NUM> and activation the flash LED <NUM> based on a target part of the vibration cycle of the mouthpiece <NUM>. For determining a target part of the vibration cycle of the mouthpiece <NUM>, the mouthpiece <NUM> comprises a sensor arrangement <NUM> that is adapted to sense an operating parameter of the oral care. Specifically, in this example, the sensor arrangement <NUM> comprises an accelerometer and gyroscope for detecting variations in displacement and velocity of the mouthpiece <NUM>. Information about the detected variations in displacement and velocity of the mouthpiece <NUM> is provided to the control unit <NUM> and, based on this information, the control unit <NUM> determines a target part of the vibration cycle of the mouthpiece <NUM>.

As already explained above with reference to the embodiment of <FIG>, the control unit <NUM> determines a target part of the vibration cycle (e.g. a period of 'low speed/velocity' of the mouthpiece <NUM>, i.e. time period wherein the magnitude of velocity of the mouthpiece <NUM> is below a predetermined threshold value). The control unit <NUM> then controls the camera so that image capture is timed to occur during the target part of the vibration cycle (e.g. during identified periods of 'low speed/velocity' of the mouthpiece <NUM>).

However, it is noted that, in this embodiment, the image capture device <NUM> comprises a rolling shutter camera configured to operate at an image capture frame rate. With respect to such a rolling shutter camera, trade-offs in operating characteristics may be required. For example, rolling shutter cameras may be more cost effective (e.g. cheaper) but may take longer for a full image capture depending on the acquisition settings and/or capabilities. An 'exposure period" is then considered to be the time period for which the rolling shutter camera is acquiring image data. For instance, image data may be acquired by the rolling shutter camera <NUM> for half of a frame, thus resulting in the effective exposure duration being half the period of the rolling shutter camera frame. Similarly the image data may be acquired by the rolling shutter camera <NUM> for one tenth of a frame, thus resulting in the effective exposure duration being one tenth of the period of the rolling shutter camera frame. Accordingly, the control unit <NUM> is thus further adapted to control an exposure parameter taking account of the frame rate of the rolling shutter camera.

In this example, a first exposure parameter comprises a start of exposure timing (i.e. the time at which image data being capture by the rolling shutter camera is commenced/started), and the control unit <NUM> is adapted to control the start of capture of image data by the rolling shutter to be synchronised with the vibration cycle. Specifically, the control unit <NUM> is adapted to synchronise the start of image data capture from the rolling shutter camera with the low speed periods of the vibration cycle (identified based on information from the sensor arrangement <NUM>). In this way, the image capture device <NUM> is controlled so that image data capture is synchronised with the low speed periods, thus reducing an amount of movement that may cause blurring and/or distortion in a captured image.

Furthermore, in this example, a second exposure parameter comprises an exposure duration of the image capture device <NUM> (i.e. length of image data capture from the rolling shutter camera), and the control unit <NUM> is adapted to set the image data capture duration to be less than or equal to a target exposure duration value. By way of example, the target exposure duration value may be determined based on a parameter of the periodic vibration waveform and a resolution parameter of the camera. For instance, the at least one resolution parameter may comprise one or more of: sensor pixel width; sensor pixel length; sensor spacing; and sensor density. In this way, the exposure duration may be set to an optimum value relation to the imaging sensor exposure shift during specific moments of motion, so as to prevent image exposure across multiple sensor elements/pixels. That is, an exposure duration of the image capture device may be set to be fast enough relative to the camera vibration to reduce or minimize image distortion or blur. This may, for example, result in a total image capture exposure duration being less than or equal to an eighth of the period of the vibration waveform. Even more preferably, the image capture exposure duration may be less than or equal to a tenth of the period of the vibration waveform of the mouthpiece <NUM>.

Moreover, for the case of a rolling shutter camera for example, it may be even more preferable to limit the exposure duration further on a line-by-line basis to be equivalent to less than one pixel shift on the image capture device - that is, the shift of the image during motion that is within the pixel resolution. In this way, the total exposure duration may be shared (i.e. divided) across all rows of the camera sensor, so that light is incident on the sensor for short pulsed exposure period per row, with the cumulative total duration of all of the pulses adding up to the total exposure duration. This may be implemented by exposing each row of the sensor to incident light for a fraction of the exposure duration or by pulsing an illumination source for fraction of the exposure duration with the pulsing synchronized with the row exposure time of each row of the rolling shutter camera sensor. Here, reference to pixel may encompass a single sensing element of an image sensor or a sensing element (single sensor) of an image sensor array. That is, a pixel may be thought of as being a single element of a sensed image, wherein the sensed image is formed from a plurality of sensed elements (i.e. pixels).

As an example, with the distance to the object fixed, and motion fixed, the pixel shift speed may be calculated. For instance, if the image capture device has a sensor with <NUM>*<NUM> pixels, the image area captured being <NUM> wide, and motion image shift being <NUM> left and <NUM> right with a vibration period of <NUM>. Movement will thus be <NUM> in ½ period (<NUM>), and <NUM> is covered by <NUM>/<NUM>* <NUM> = <NUM> pixels. A single pixel image movement takes <NUM>/<NUM> = <NUM>. Allowing for ½ a pixel shift during exposure would result in an exposure time of <NUM>. Thus, a total exposure time is the number of rows in the image times the line exposure time i.e.<NUM> x <NUM> = <NUM>. In such a manner, the short pulsed exposure periods are distributed evenly across the entire frame period and exposure is optimized for and during the low speed motion periods.

In other cases like high framerates and special camera's where per line or per pixel the exposure can be adjusted, an optimum per pixel, line or frame could be set during the image acquisition and in relation to the ideal moments of capture where for example the speed of motion is low.

That is, for image acquisition using a rolling shutter camera <NUM>, it is proposed to adapt the exposure duration to be fast relative to the camera vibration, e.g. effective exposure time (i.e. image data acquisition time by the rolling shutter camera <NUM>) is adapted to be, at most, equivalent to the duration/period of minimal motion of the mouthpiece <NUM>.

Referring to <FIG>, illustrations are provided to demonstrate a proposed concept of synchronising data capture with a target part of the vibration cycle and the reconstructing a single, higher quality image from the captured data. In particular, <FIG> illustrate the concept employed in conjunction with a free rolling camera and synchronised flash (i.e. pulses of illumination synchronized with the target part of the vibration cycle).

<FIG> illustrates the object being imaged, specifically teeth of a user.

<FIG> shows a captured image frame with the personal care device vibrating at <NUM> and no compensation (i.e. not employing the proposed concept(s) of this invention).

<FIG> shows a captured image with the personal care device vibrating at <NUM> and a synchronised flash (i.e. pulses of illumination synchronized with the target part of the vibration cycle of the personal care device). From <FIG> it can be seen that lines of image data are acquired, wherein the captured lines comprise sharp, blue free data captured during low speed periods of the vibration cycle.

<FIG> shows a reconstruction image that is reconstructed from the captured lines of image data (from different captured image frames). A full image may then be reconstructed from image data acquired from multiple different frames of the rolling shutter camera.

Conversely, <FIG> illustrate the concept employed in conjunction with a free rolling camera and continuous illumination.

<FIG> shows a captured image with the personal care device vibrating at <NUM> and continuous illumination, wherein lines of image data are identified as being captured during the target part of the vibration cycle of the personal care device. These indicated lines comprise sharp, blue free data captured during low speed periods of the vibration cycle.

<FIG> shows a reconstruction image that is reconstructed from the selected lines of image data (from different captured image frames).

It will be appreciated that the rolling shutter camera can be free running and out of synchronization with vibration of the personal care device (and thus the image data capture frequency). A full image may then be reconstructed from image data acquired from multiple different frames of the rolling shutter camera.

From the above description of various concepts and embodiments, it will be appreciated that there is proposed a method of controlling a personal care device, wherein the personal care device comprises: vibratory means adapted to vibrate the personal care device so that, in use, the personal care device vibrates with a vibration cycle having a vibration frequency; an image capture device adapted, in use, to capture images of one or more oral features of a user; and a sensor arrangement adapted to sense an operating parameter of the personal care device. The method comprises: determining a target part of the vibration cycle based on the sensed operating parameter; and controlling the image capture device based on the determined target part of the vibration cycle. Such a method may be employed in a processing system or computer, and such a system/computer may be integrated with a vibratory personal care device.

<FIG> illustrates an example of a computer <NUM> within which one or more parts of an embodiment may be employed. Various operations discussed above may utilize the capabilities of the computer <NUM>. For example, one or more parts of a system for providing a subject-specific user interface may be incorporated in any element, module, application, and/or component discussed herein. In this regard, it is to be understood that system functional blocks can run on a single computer or may be distributed over several computers and locations (e.g. connected via internet), such as a cloud-based computing infrastructure.

The computer <NUM> includes, but is not limited to, PCs, workstations, laptops, PDAs, palm devices, servers, storages, and the like. Generally, in terms of hardware architecture, the computer <NUM> may include one or more processors <NUM>, memory <NUM>, and one or more I/O devices <NUM> that are communicatively coupled via a local interface (not shown). The local interface can be, for example but not limited to, one or more buses or other wired or wireless connections, as is known in the art. The local interface may have additional elements, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communications. Further, the local interface may include address, control, and/or data connections to enable appropriate communications among the aforementioned components.

The processor <NUM> is a hardware device for executing software that can be stored in the memory <NUM>. The processor <NUM> can be virtually any custom made or commercially available processor, a central processing unit (CPU), a digital signal processor (DSP), or an auxiliary processor among several processors associated with the computer <NUM>, and the processor <NUM> may be a semiconductor based microprocessor (in the form of a microchip) or a microprocessor.

The software in the memory <NUM> may include one or more separate programs, each of which comprises an ordered listing of executable instructions for implementing logical functions. The software in the memory <NUM> includes a suitable operating system (O/S) <NUM>, compiler <NUM>, source code <NUM>, and one or more applications <NUM> in accordance with exemplary embodiments. As illustrated, the application <NUM> comprises numerous functional components for implementing the features and operations of the exemplary embodiments. The application <NUM> of the computer <NUM> may represent various applications, computational units, logic, functional units, processes, operations, virtual entities, and/or modules in accordance with exemplary embodiments, but the application <NUM> is not meant to be a limitation.

If the computer <NUM> is a PC, workstation, intelligent device or the like, the software in the memory <NUM> may further include a basic input output system (BIOS) (omitted for simplicity). The BIOS is a set of essential software routines that initialize and test hardware at startup, start the O/S <NUM>, and support the transfer of data among the hardware devices. The BIOS is stored in some type of read-only-memory, such as ROM, PROM, EPROM, EEPROM or the like, so that the BIOS can be executed when the computer <NUM> is activated.

When the computer <NUM> is in operation, the processor <NUM> is configured to execute software stored within the memory <NUM>, to communicate data to and from the memory <NUM>, and to generally control operations of the computer <NUM> pursuant to the software. The application <NUM> and the O/S <NUM> are read, in whole or in part, by the processor <NUM>, perhaps buffered within the processor <NUM>, and then executed.

The proposed image capture and/or processing methods, may be implemented in hardware or software, or a mixture of both (for example, as firmware running on a hardware device). To the extent that an embodiment is implemented partly or wholly in software, the functional steps illustrated in the process flowcharts may be performed by suitably programmed physical computing devices, such as one or more central processing units (CPUs) or graphics processing units (GPUs). Each process - and its individual component steps as illustrated in the flowcharts - may be performed by the same or different computing devices. According to embodiments, a computer-readable storage medium stores a computer program comprising computer program code configured to cause one or more physical computing devices to carry out an encoding or decoding method as described above when the program is run on the one or more physical computing devices.

Storage media may include volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, optical discs (like CD, DVD, BD), magnetic storage media (like hard discs and tapes). Various storage media may be fixed within a computing device or may be transportable, such that the one or more programs stored thereon can be loaded into a processor.

To the extent that an embodiment is implemented partly or wholly in hardware, the blocks shown in the block diagrams of <FIG> and <FIG> may be separate physical components, or logical subdivisions of single physical components, or may be all implemented in an integrated manner in one physical component. The functions of one block shown in the drawings may be divided between multiple components in an implementation, or the functions of multiple blocks shown in the drawings may be combined in single components in an implementation. Hardware components suitable for use in embodiments of the present invention include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). One or more blocks may be implemented as a combination of dedicated hardware to perform some functions and one or more programmed microprocessors and associated circuitry to perform other functions.

If a computer program is discussed above, it may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Claim 1:
A personal care device comprising:
an image capture device (<NUM>) adapted, in use, to capture images of one or more features of a user;
vibratory means (<NUM>) adapted to vibrate the personal care device so that, in use, the personal care device vibrates with a vibration cycle having a vibration frequency;
a sensor arrangement (<NUM>) adapted to sense an operating parameter of the personal care device; and
a control unit (<NUM>) adapted to determine a target part of the vibration cycle based on the sensed operating parameter and to control the image capture device based on the target part of the vibration cycle.