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Title:
PROGRAMMABLE HAIR TRIMMING SYSTEM
Document Type and Number:
WIPO Patent Application WO/2015/068068
Kind Code:
A1
Abstract:
A programmable hair trimming system is disclosed, comprising a tracking system for detecting the position of a hair trimming device in relation to a client's head, a computer system for relating said position to a previously generated hair length profile data file and automatically and dynamically adjusting a length regulation mechanism of said hair trimming device according to the hair trimmer position data and the hair length profile data file, wherein the tracking system comprises one or more cameras and sensors such as accelerometers and/or gyroscopes and/or magnetometers for detecting the position, orientation and motion of both said hair trimming device and a client's head.

Inventors:
LAURITSEN KLAUS (NL)
Application Number:
IB2014/065495
Publication Date:
May 14, 2015
Filing Date:
October 21, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
KONINKL PHILIPS NV (NL)
International Classes:
B26B19/38; A45D24/36
Domestic Patent References:
WO2013096572A12013-06-27
WO2013096572A12013-06-27
Foreign References:
DK201200292A12013-11-02
US20110018985A12011-01-27
US20090303320A12009-12-10
Attorney, Agent or Firm:
COOPS, Peter et al. (AE Eindhoven, NL)
Download PDF:
Claims:
Claims

A programmable hair trimming system comprising a hair trimming device (1), a tracking system (4,5,6,7,8,9, 10,11, 12, 14,41) for detecting the position of a position reference point (22) of said hair trimming device (1) in relation to the head (23) of a person on whom a hair trimming is being performed, wherein the tracking system comprises one or more cameras for detecting the position of a client's head (23) and the system's hair trimming device (1), a computer system (4, 5) for relating the position of said position reference point (22) to a previously generated hair length profile data file (39) containing one or more position points (24, 25) on said head (23) with associated position point trimming lengths (38) and dynamically calculating local trimming lengths (26) between said position point trimming lengths (38) and dynamically controlling a length regulation mechanism (19) of said hair trimming device (1) according to said trimming lengths (26, 38).

2. A hair trimming system according to claim 1, wherein the hair trimming device (1) further comprises a number of sensors such as accelerometers and/or gyroscopes and/or magnetometers (15) for detecting the movement of the hair trimming device (1). A hair trimming system according to claim 1 or 2, wherein a connected ear sensor (41) comprises a number of sensors such as accelerometers and/or gyroscopes and/or magnetometers (15) for detecting the movement of and movement of the client's head (23).

4. A hair trimming system according to any of the previous claims,

wherein the hair trimming device (1) further comprises an area for storing and charging one or more in-ear sensors (41). 5. A hair trimming system according to any of the previous claims,

wherein the hair trimming device (1) further comprises a fixed distance between its user grip area (28) and its distance comb (21).

6. A hair trimming system according to any of the previous claims,

wherein said hair trimming system comprises an embedded computer system (40), arranged to perform one or more of the following tasks:

- store a hair length profile data file (39);

- receive a live stream of images from integrated (12) and external cameras (5, 6, 7, 8, 9, 10, 11, 14) monitoring the positions of a client's head (23) and the system's hair trimming device (1);

- calculate the position of a hair trimming position reference point (22) in relation to the client's head (23);

- calculate a trimming length (26) from said stored and received data;

- control a length adjusting mechanism (19) of said hair trimming device (1);

- transmit audio information to a speaker (42) in an in-ear ear sensor unit (41);

- communicate with an external computer system (4).

7. A hair trimming system according to any of the previous claims, wherein said hair trimming system comprises an external computer system (4) arranged to perform one or more of the following tasks:

- store a hair length profile data file (39);

- receive a live stream of images from integrated (5) and external cameras (6, 7, 8, 9, 10, 11, 12, 14) monitoring the positions of a client's head (23) and the system's hair trimming device (1);

- calculate the position of a hair trimming position reference point (22) in relation to the client's head (23);

- calculate a trimming length (26) from said stored and received data;

- communicate with a length adjusting mechanism (19) of said hair trimming device (1);

- transmit audio information to a speaker (42) in an in-ear ear sensor unit

(41);

8. A hair trimming system according to any of the previous claims,

wherein the hair length profile data file (39) format comprises a list of individual position points (20, 26) on a client's head (23) with accompanying trimming lengths.

9. A hair trimming system according to any of the previous claims,

wherein an external computer system (4) is arranged to allow its user to retrieve, modify, visualize and store a number of hair length profile data file (39).

10. A hair trimming system according to any of the previous claims,

wherein an external computer system (5) is arranged to allow its user (2) to monitor the progress of a hair trimming session performed by a connected hair trimming system.

Description:
Title

Programmable hair trimming system Field of the invention

The present invention relates to a programmable hair trimming system, which can be programmed to adjust its hair trimming length according to the monitored positions of both a hair trimming device and the head of the person, whose hair is being trimmed.

Description of the related art Hair trimming devices commercially available use either a replaceable or a manually adjustable comb unit in order to control the distance from the trimmer's cutting point to the client's head and thus the hair trimming length.

Using these devices, it is virtually impossible to create neither a smooth fading between different hair lengths, nor a repeatable end result if more than one length setting is applied. They have thus a limited use for other than short and even length haircuts, and, without a distance comb, for

removing hair typically at a person's ears and neck area. WO2013096572A1 describes a hair cutting system, including a head-mounted positioning structure with various positioning interfaces. The cutting device of WO2013096572A1 is detecting its position relative to this positioning structure. According to WO2013096572A1, the hair cutting device is to be moved in a manner similar to traditional manual hair cutting, where a lock of hair is lifted by the trimmer from the head in a combing manner. When the hair cutting device has been moved as far from the head as a predefined hair cut profile indicates, the hair cutting device of WO2013096572A1 activates its cutting mechanism and cuts the hair.

A drawback of the WO2013096572A1 traditional cutting principle is that a user must constantly move the trimming device to a new area, then lift the trimming devicer away from the client's head until a lock of hair is cut, and then repeat this procedure over and over again. This procedure is tedious asit only cut sone lock at a time, and potentially unergonomic as a motorized trimmer is heavier than a pair of scissors.

A further drawback of the device and cutting method according to

WO2013096572A1 is that a person can not perform a haircut himself in a comfortable way, especially on the back of his head.

A further drawback of WO2013096572A1 is the usage of a "flat" 2D model of the users scalp in order to describe a clients head and hair area. This requires a complicated adaption for various head shapes and sizes, with the same inevitable map projection errors as known from cartography, where a sphere / globe is transformed to a 2D plane. WO2013096572A1 mentions an alternative polar reference system including monitored distance to a centre point, which is unnecessarily complicated.

Brief description of the invention

It is an object for the present invention to provide a hair trimming system that eliminates at least some of the drawbacks of WO2013096572A1 and makes it possible for a person to cut his own hair in a pre-programmed and repeatable fashion as easily as with a standard non-programmable hair

trimmer currently on the market.

The present invention relates to a programmable hair trimming system

comprising a hair trimming device, a tracking system for detecting the position of a position reference point of said hair trimming device in relation to the head of a person on whom a hair trimming is being performed, wherein the tracking system comprises one or more cameras for detecting the position of a client's head and the system's hair trimming device; a computer system for relating the position of said position reference point to a previously generated hair length profile data file containing one or more position points on said head with associated position point trimming lengths and dynamically calculating local trimming lengths between said position point trimming lengths and dynamically controlling a length regulation mechanism of said hair trimming device according to said trimming lengths.

This makes it possible to perform a hair trimming with a pre-defined, repeatable length-blending result just as easy as with a traditional fixed- length hair trimmer currently on the market.

In an embodiment of the invention, the hair trimming device further comprises a number of sensors such as accelerometers and/or gyroscopes and/or magnetometers for detecting the movement of the hair trimming device.

This makes it possible to track the movement of the trimming device with additional precision.

In an embodiment of the invention, the hair trimming system further comprises a connected ear sensor unit comprising sensors such as accelerometers and/or gyroscopes and/or magnetometers for detecting the movement of the client's head.

This makes it possible to track the movement of the client's head with additional precision. In an embodiment of the invention, the hair trimming device further comprises an area for storing and charging one ore more in-ear sensors.

This makes it possible to store and charge small in-ear sensors in a single unit that is easy to transport in a hygienic way, without the need of separate chargers for the sensor units.

In an embodiment of the invention, the hair trimming device comprises a fixed distance between its user grip area and its distance comb.

This layout allows the person who is holding said hair trimming device to focus on guiding the device on the surface on the client's head, while the hair trimming length adjustment is performed automatically by the motorized length regulation mechanism of the hair trimming device.

In an embodiment of the invention, the hair trimming system comprises an embedded computer system, arranged to perform one or more of the following tasks: Store a hair length profile data file; Receive a live stream of images from integrated and external cameras monitoring the positions of a client's head and the system's hair trimming device; Calculate the position of a hair trimming position reference point in relation to the client's head; Calculate a trimming length from said stored and received data; Control a length adjusting mechanism of said hair trimming device; Transmit audio information to a speaker in an in-ear ear sensor unit; Communicate with an external computer system.

This allows for performing a hair trimming session using said hair trimming system, without the use of an external computer system.

In another embodiment of the invention, the hair trimming system comprises an external computer system arranged to perform one or more of the following tasks: Store a hair length profile data file; R live stream of images from integrated and external cameras monitoring the positions of a client's head and the system's hair trimming device; Calculate the position of a hair trimming position reference point in relation to the client's head; Calculate a trimming length from said stored and received data;

Communicate with a length adjusting mechanism of said hair trimming device; Transmit audio information to a speaker in an in-ear ear sensor unit.

This allows for using the processing power of an external computer system, thus reducing the additional cost of the hair trimming system.

In an embodiment of the invention, the data file format used for storing a hair length profile comprises a list of position points on a client's head with accompanying desired trimming lengths.

This allows for a small data file size that can easily be modified and stored, and for using a hair length profile data file on various compatible hair trimming systems.

In an embodiment of the invention, said hair length profile data file can be retrieved, modified, visualized and stored on an external computer system.

This allows a user to pre-program a desired hair length profile data file before a hair trimming session is initiated.

In an embodiment of the invention, the progress of an on-going hair trimming session can be monitored on a connected external computer system.

This allows for a user to identify which areas on a client's head that has been covered so far during the hair trimming session. Using an optical tracking system to detect and and identify appearance and features of the client's head eliminates the need for mounting guides and sensors to the client's head.

Using a movement/orientation-based tracking system including sensors such as accelerometers and/or gyroscopes and/or magnetometers adds further data and stability to the position calculation in cheap and reliable way, integrated in the trimming device and/or in one or more small ear-mounted tracking devices, similar in shape and carrying comfort to standard bluetooth headsets. In a situation where the optical system loses line of sight or other gaps in the optical position tracking occurs, these sensors can provide information about the movement of the trimmer until visual contact is established again, thus reducing the risk of an interrupted trimming session.

The present invention differs from the above-mentioned WO2013096572A1 in the usage of a trimming device that adapts it's trimming length dynamically and automatically, where the user guides the hair trimming device on the surface of the client's head, thus allowing a person to perform a hair trimming himself.

If the hair trimming system comprises an external computer system and one or more sensors such as accelerometers and/or gyroscopes and/or magnetometers, the hair trimming system then transmits sensor data to the external computer system, which then transmits calculated trimming length data from to the hair trimming unit, which then dynamically and automatically engages its length regulation mechanism in order to adjust its trimming length.

To the end user, a trimming device according to the current invention will be just as easy to use as a standard non-programmable hair trimmer, with the added benefit of a pre-programmed, repeatable haircut with smooth length blending.

In an embodiment of the invention, the tracking system comprises of a number of cameras, with one or more cameras placed in the trimmer itself, one or more cameras placed on the client on whom a hair trimming is being performed, one or more cameras placed on an optional assisting person performing the hair trimming, one or more cameras placed beside, below or above the client, one or more cameras placed in a device like a mobile phone, tablet computer, laptop or desktop PC with an integrated or connected camera unit.

This layout with multiple cameras allows for additional tracking precision as well as minimising the risk of an interrupted session due to lost line-of-sight between camera and trimming device.

This also allows a client on whom a hair trimming is being performed to move his head freely during a hair trimming session, especially bending his head forward for easy access to the neck hair area.

In the situation where the user and client is the same person, audio feedback regarding session status, current trimming lengths, battery levels, guidance regarding the movement of the hair trimming device and other relevant information can be provided to the client via the ear sensor unit. If the hair trimming system comprises an embedded computer system, this layout allows for a user to monitor the trimming session without the need for an external monitoring device. The ear sensor units can be fitted with mechanical noise cancelation features as in standard earplugs, and/or be added active noise cancelation features known typically from industrial and hunting equipment, thus reducing the annoyance of the trimmer's noise during a hair trimming session.

Using in-ear sensor placement is likely to be accepted by users, as a similar form factor and placement is well known from standard bluetooth headsets.

In an embodiment of the invention, the progress of an on-going hair trimming session can be monitored on a connected external computer system.

This allows for a user to identify which areas on a client's head that has been covered so far during the hair trimming session.

The drawing

In the following, a few embodiments of the invention are described and explained in more detail with reference to the drawing, where fig. 1 illustrates schematically an overall system setup with an external computer system, a number of connected cameras, a hair trimming device moved on the head of a client by a user according to an embodiment of the invention, fig. 2A illustrates schematically a hair trimming device layout with a fixed distance between its user grip area and its distance comb according to an embodiment of the invention, fig. 2B illustrates schematically an in-ear sensor with a mechanical movement detection unit according to an embodiment of the invention, fig. 3 illustrates schematically a longitude vector index of position point data with a 360° coordinate grid according to an embodiment of the invention, fig. 4&5 illustrate schematically a latitude vector index of position point data with a 360° coordinate grid according to an embodiment of the invention, fig. 6 illustrates schematically a placement of centred and symmetric position points according to an embodiment of the invention, fig. 7 illustrates schematically calculated local trimming lengths between position point lengths according to an embodiment of the invention, fig. 8 illustrates schematically calculated smooth Bezier local trimming lengths between position point lengths according to an embodiment of the invention, fig. 9 illustrates schematically calculated linear local trimming lengths between position point lengths according to another embodiment of the invention, fig. 10 illustrates schematically a calculation of the lower length limit for shorter adjacent hair in order to avoid longer hair being trimmed involuntarily at an offset position according to an embodiment of the invention, fig. 11 illustrates schematically a primary hair area following potential movements of a client's head according to an embodiment of the invention, fig. 12 illustrates schematically areas with different trimming lengths and their overlapping area when using interchangeable distance combs according to another embodiment of the invention, fig. 13 illustrates schematically the start-up area where the hair trimming device is placed by the user before guiding the device into the primary hair area according to an embodiment of the invention, fig. 14 illustrates schematically same-length contour lines according to an embodiment of the invention, and fig. 15 illustrates schematically the modification of position point lengths on an external computer system according to an embodiment of the invention.

Detailed description of the invention

In the following descriptions, the term "user" describes the person holding and guiding the hair trimming device during a hair trimming session, and/or operating an integrated and/or connected external computer system.

The term "client" describes the person on whom a hair trimming is being performed.

These can be multiple persons or the same person. System layout:

Fig. 1 illustrates an embodiment of the invention, where the position and orientation of both a client's head (23) and a hair trimming device (1) are monitored by a number of integrated and external cameras and/or sensors such as accelerometers and/or gyroscopes and/or magnetometers.

In an embodiment of the invention, a live stream om images and/or sensor data is transmitted to an external computer system (4) or embedded computer system (40) placed in the systems hair trimming device (1). One or two additional head-tracking in-ear sensors with sensors such as accelerometers and/or gyroscopes and/or magnetometers can monitor the movement and orientation of the client's head and thus provide the computer system (4, 40) with additional data for increased position calculation.

As the hair trimming system is monitoring the position of the hair trimming device (1) as well as the client's head (23), it is provided with sufficient data for its computer system (4, 40) to calculate the position of the hair trimming position reference point (22) in relation to the client's head (23).

This hair trimming position reference point (22) is compared by the computer system (4, 40) to a previously generated hair length profile data file (39) that allows for the dynamic calculation of local trimming length (26) on the client's head (23) at the current position.

The calculated local trimming length (26) is transmitted, wired or wirelessly, to the hair trimming device's (1) length regulation mechanism (19), which dynamically and automatically adjusts the hair trimming length accordingly.

The invention is characterized by utilizing a general data file format and separate hair trimming hardware. This allows for the same data file to be used by hardware with various features, i.e. cutting point design, optional vacuum, grid resolution, wired / wireless and trimming length adjusting mechanism design, different position tracking systems such as radio -, electromagnetic -, infrared -, acoustic -, & sonar-based systems.

Hair length profile (HLP) data file (39) creation and modification procedure:

A HLP data file (39) contains a set of position points (24, 25), each with an accompanying trimming length between zero mm and a maximum length determined by a hair trimming device's adjustment travel length.

The number of position points (24, 25) for a HLP data file (39) is small enough to allow for smooth calculated local trimming lengths (26), while maintaining the resolution needed for local length variation, preferably four to eight centred position points (24) and two to six pairs of symmetric position points (25).

Each position point (24, 25) is characterized by its X coordinate, fig. 3, and its Y coordinate, fig. 4&5, which X and Y coordinates correspond to longitude and latitude coordinates, respectively, in the geographic coordinate system of a globe. A position point (24, 25) can thus be considered as a 3D vector direction with origin at a virtual centre inside a client's head (23).

The centred position points (24) all have an X value of 0° or 180°, while the symmetric position points (25) all have a mirrored twin point with similar Y value and an X value of three-hundred-and-sixty degrees minus the opposite point's X value. The symmetric position points (25) can optionally be replaced by individual position points (not shown) without a mirrored twin point on the opposite side of the client's head (23).

Using this globe-like analogy for the HLP data file structure allows for a very simple and universal description of the position points (24.25), that can be used by various clients, regardless of their head shape and size.

In an embodiment of the invention, a HLP modification system can present a number of default HLP data files (39) for the user (2) to choose from, including images of possible hair styles based on the HLP data file (39). The HLP modification system can be used on an external computer system (4) independently and prior to a hair trimming session.

In another embodiment of the invention, the user (2) enters length values at a number of points on the client's head (23) into the HLP modification system. These values can be based on manually measured hair lengths on the client's head whilst having a desired hair length.

During this manual procedure, the HLP modification system can show to the user (2) where values need to be added in order to generate a useable HLP data file (39).

The HLP modification system software allows the user (2) to modify the HLP data file (39) by selecting a position point (24, 25) and then adjust its accompanying trimming length. The length selectable at any position point (24, 25) is limited by the maximum travel distance of the length regulation mechanism (19) of the hair trimming device (1) to be used.

The limit for local length variation is given by the equation

Ly > sqr(Lx 2 - D 2 ) where Ly is the minimum length of a hair at the distance D from a longer hair with the length Lx, fig. 10.

If the trimming length setting at Ly is shorter that given by said equation, longer Lx hair could be trimmed involuntarily at the Ly position.

The HLP modification system prevents the user (2) from adjusting a position point trimming length (38) with too much local variation according to said equation.

The length setting for the neck hair area (34) is automatically set to a similar length as at the closest position point (24, 25), as this area not necessarily follows the position monitored features of the client's head (23) when this is moved / twisted / bend.

The fade shape between position points (24, 25) is by default adapted to a smooth Bezier curve connection angle (31), fig. 8, and can be modified by the user (2) towards a sharp connection angle (32), fig. 9.

The user (42) can choose to modify any number of position points (24, 25).

The updated HLP data file (39) can be displayed by the HLP modification system by visualizing the position lengths (38) and the calculated local trimming lengths (26) in a "hedgehog" style, and/or a terrain style with illustrated contour lines (29) with similar trimming length, and/or colours indicating various trimming lengths.

The updated HLP data file (39) can be illustrated by the HLP modification system by showing a number of hairstyles possible with the currently selected HLP data file (39).

A live stream from any of the connected cameras can be used to visualize the client's face with the selected HLP data file (39) applied on an external screen and/or the ecternal computer system (4).

The updated HLP data file (39) and potential hairstyles can be displayed by the HLP modification system in combination with images of the client's head from the system's various cameras for a more realistic preview of the potential end result.

The updated HLP data file (39) can be stored in an external computer system (4), and/or in a database accessible via connected computers i.e. the internet, and/or on local media i.e. USB memory devices, and/or portable devices such as mobile telephones.

A number of HLP data files (39) can be stored in the embedded computer system (40) placed in either the hair trimming device for optional usage without an external computer system (4).

Hair trimming procedure:

Prior to a trimming session, the user (2) selects which HLP data file (39) to use. In an embodiment of the invention, the HLP data file (39) can be selected on an interactive display (17) on the hair trimming device (1) and/or on a connected external computer system (4).

The user (42) places the hair trimming device (1) in the start-up area (30) on the client's head (23), with contact detected by a pressure sensitive sensor in the hair trimming device (not shown). The hair trimming system detects and confirms the placement in the start-up area (25) as well as the trimmer/head contact via said pressure sensitive sensor, and starts the trimming motor (16) automatically.

During a hair trimming session, the user (42) guides the hair trimming device (1) on the surface of the client's head (23) in the same way, as he would use a commercially available hair trimming device with a preselected distance comb length.

The hair trimming procedure progress can be monitored visualized using an external computer system (4).

The external computer system (4) can display the current position of the hair trimming position reference point (22) on the client's head (23), including a visualization of the area on the client's head (23) covered so far during the current session.

The hair trimming visualization system can assist the user (2) in moving the hair trimming device (1) perpendicular to contour lines (29) with the same trimming height, typically from a start-up area (30) towards the top of the client's head (23), in order to prevent that a hair trimming device (1) with a wide cutting point (27) trims off too much hair.

Information about i.e. the current hair trimming length, data signal strength and battery levels can be displayed on the external computer system (4). If, for whatever reason, the connection between the tracking system's cameras (5, 6, 7, 8, 9, 10, 11, 12, 14) and/or sensors (15) and the computer system (4, 40) is interrupted, and/or line-of-sight is blocked for a critical number of connected cameras, and/or the user (2) moves the hair trimming device (1) too fast for the computer system (4, 40) to calculate and transmit the current calculated local trimming length (26) to the hair trimming device's (1) length regulation mechanism (19), and/or the transmission of the current calculated local trimming length (26) from the external computer system (4) to the hair trimming device (1) is interrupted, and/or the hair trimming device (1) is lifted from the client's head (23), and/or the mechanical sensors in the hair trimming device and/or optional in-ear sensor registers a movement too fast for the system to calculate and/or adjust the length regulation mechanism accordingly; then the trimming motor of the trimming mechanism (20) is automatically shut off, and/or the length regulation mechanism (19) is moved to its maximum trimming length.

In order to minimize the size and weight of the moving parts, a heavy trimmer motor should be at a fixed position (not illustrated) inside the hair trimming device (1), and the length regulation mechanism (19) should only move a minimum of mass, including the cutting point (27). This allows for a quick and responsive length regulation performance with minimal battery tear and wear. In another embodiment of the invention, a moveable distance comb (21) is used, whilst the cutting point (27) is fixed in the hair trimming device (1).

This is similar to the layout of most of today's commercially available hair trimmers and would allow for a cheap and well-known production setup, but also requires that the user (2) constantly applies both sufficient pressure on the client's head (23) in order to keep the distance comb (21) touching the surface of client's head (23), and at the same time not using too much force that could prevent the distance comb (27) from increasing the trimming distance / "pushing the client's head (23) away".

In an embodiment of the invention, one or more cameras (12) integrated in the hair trimming device (1) are positioned in a manner that allows these cameras to have visual contact with the hair trimming position reference point (22) while the user (2) is holding the hair trimming device (1) at the dedicated user grip area (28).

In an embodiment of the invention, the design of the cutting point (27) mechanism is similar to hair trimming devices commercially available, with a horizontally moving shearing blade moving in parallel to a static blade.

In another embodiment of the invention, the layout of the cutting point (27) contains a rotating cutting system, similar to other hair trimming devices commercially available.

In another embodiment of the invention, the hair trimming device (1) is connected to a vacuum unit (not shown) as applied by a number of commercially available hair trimming devices, which assists the distance comb (21) in lifting the hair perpendicular to the client's head (23). This reduces the need for trimming the current area multiple times, as more hair is likely to be trimmed the first time the hair trimming device (1) is passing an area.

A connected vacuum unit could also remove trimmed-off hair and thus reduce the need for cleaning of both the hair trimming device (1) and the client (3) afterwards.

The vacuum can be generated by an external system collecting the hair clippings, or a vacuum generator integrated in the hair trimming device (1) itself, including a reservoir for collecting hair clippings. In another embodiment of the invention, a hair-thinning attachment (not shown) can be engaged at the cutting point (27), as applied by a number of commercially available hair trimming devices.

This hair-thinning attachment reduces the amount of hair that is caught at the cutting point (27), and thus provides an end result with a more fluffy and random appearance, which can be desirable for some clients.

As the previously mentioned hair trimming visualization system can display the area covered during the current trimming session, the user (2) can monitor which areas has been trimmed and/or thinned out so far during the current hair trimming / thinning session. This is especially useful when the user (2) and client (3) is the same person.

In another embodiment of the invention, the distance comb (21) is interchangeable, thus making it possible for using the hair trimming system for hairstyles with longer lengths than the travel length of the length regulation mechanism (19).

I.e. if the length regulation mechanism (19) has a travel distance of thirty mm, one distance comb (21) could cover zero-to-thirty mm trimming lengths, and another could be used on twenty-to fifty mm lengths.

If these replaceable distance combs (21) are to be used during the same hair trimming session, an external computer system (4) can show the user which areas to trim with the current distance comb (19), fig. 12. The hair trimming device (1) will automatically shut off its trimmer mechanism (20), if the user involuntarily moves a short length distance comb from its intended area (37) via an overlapping trimming length area (36) and into an area with longer hair (35). In another embodiment of the invention, the user (2) can temporarily modify the selected HLP data file (39) by adjusting all position point trimming lengths (38) with a chosen percentage, and/or a chosen distance. The user (2) can also temporarily modify the selected HLP data file (39) by adding one or more ad-hoc position points and/or by modifying one or more position points (24, 25).

In another embodiment of the invention, the user (2) can manually adjust the length regulation mechanism (19), and thus use the hair trimming device (1) as the manually adjustable hair trimming devices commercially available, without the need for additional external computer systems and cameras.

It should be noted that the described embodiments are exemplary only and are not in any way meant to limit the scope of protection, which is defined by the claims listed here below.

List of reference numbers

1. Hair trimming device

2. User

3. Clint

4. External computer system

5. Camera integrated in external computer system

6. Head-mounted camera

7. Body-mounted camera on client

8. External camera

9. External camera

10. Body-mounted camera on user

11. Necklace-type camera on user

12. Camera integrated in hair trimming device 13. Position point

14. Wrist-type camera on user

15. Accelerometer / Gyroscopes / Magnetometers

16. Battery

17. Wireless transmitter

18. Length regulation motor

19. Length regulation mechanism

20. Trimmer mechanism

21. Distance comb

22. Hair trimming position reference point 23. Client's head

24. Centred position point

25. Symmetric position point

26. Calculated local trimming length

27. Cutting point

28. User grip area

29. Contour lines

30. Start-up area 31. Smooth Bezier curve connection angle

32. Sharp connection angle

33. Primary hair area

34. Neck hair area

35. Longer hair area

36. Overlapping trimming length area

37. Shorter hair area

38. Position point trimming length

39. Hair length profile data file

40. Embedded computer system

41. Ear sensor

42. Speaker / Replaceable earbud