WO2014068414A1 - Skin treatment device having a skin detector - Google Patents

Skin treatment device having a skin detector Download PDF

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Publication number
WO2014068414A1
WO2014068414A1 PCT/IB2013/058277 IB2013058277W WO2014068414A1 WO 2014068414 A1 WO2014068414 A1 WO 2014068414A1 IB 2013058277 W IB2013058277 W IB 2013058277W WO 2014068414 A1 WO2014068414 A1 WO 2014068414A1
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WO
WIPO (PCT)
Prior art keywords
skin
sensor elements
sensor
treatment device
sensor element
Prior art date
Application number
PCT/IB2013/058277
Other languages
French (fr)
Inventor
Mario Arnold Lutschounig
Dieter Johann Maier
Original Assignee
Koninklijke Philips N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips N.V. filed Critical Koninklijke Philips N.V.
Publication of WO2014068414A1 publication Critical patent/WO2014068414A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/06—Radiation therapy using light
    • A61N5/0613—Apparatus adapted for a specific treatment
    • A61N5/0616—Skin treatment other than tanning
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/06—Measuring instruments not otherwise provided for
    • A61B2090/064—Measuring instruments not otherwise provided for for measuring force, pressure or mechanical tension
    • A61B2090/065—Measuring instruments not otherwise provided for for measuring force, pressure or mechanical tension for measuring contact or contact pressure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/06—Radiation therapy using light
    • A61N2005/0626—Monitoring, verifying, controlling systems and methods
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/06—Radiation therapy using light
    • A61N2005/0635—Radiation therapy using light characterised by the body area to be irradiated
    • A61N2005/0643—Applicators, probes irradiating specific body areas in close proximity

Definitions

  • This invention relates to skin treatment devices comprising a skin detector.
  • a skin treatment device with a skin detector is, e.g., disclosed in the United
  • the skin proximity sensor comprises a window, surrounded by a bezel with a plurality of capacitive sensors.
  • Control circuitry is coupled to the capacitive sensors to observe changes in capacitance due to (lack of) skin contact.
  • the bezel comprises three capacitive sensors distributed around a circular orifice.
  • the skin proximity sensor may cause an incorrect interpretation of the signals from the capacitive sensors. For example, it may indicate skin contact when the orifice is actually not covering the skin or vice versa. Typically, when the treatment application area is nearly fully covered by skin, this may be wrongly interpreted as full coverage. Especially with a skin treatment device using high power light sources this may result in undesirable safety risks because of powerful light beams not impinging on a skin to be treated but, e.g., on a human or animal eye.
  • An additional aspect that is important when developing a skin treatment device having a suitable skin detector is to reduce complexity. Complex skin detectors are more susceptible to failure and increase manufacturing costs.
  • a skin treatment device for treating a portion of a skin in accordance with a first aspect of the invention comprises an application area and a skin detector.
  • a treatment is provided through the application area to the portion of the skin.
  • the skin detector is for detecting whether the application area has a predefined desired position with respect to the skin.
  • the skin detector comprises a first set of a plurality of first sensor elements, a second set of at least one second sensor element and a control circuit comprising a first input and a second input.
  • the first sensor elements and the at least one second sensor element are arranged around the application area.
  • the first sensor elements are coupled to the first input to obtain a first detection signal and the at least one second sensor element is coupled to the second input to obtain a second detection signal.
  • the at least one second sensor element is arranged in between two neighboring first sensor elements.
  • the control circuit comprises a decision circuit for supplying an activating signal to activate the skin treatment device if the first detection signal indicates that all first sensor elements have predefined desired positions with respect to the skin and the second detection signal indicates that the at least one second sensor element all have predefined desired positions with respect to the skin.
  • the skin treatment device according to the invention makes it possible to obtain improved skin detector accuracy without significantly increasing its complexity.
  • the first sensor elements share the first input of the control circuit, the number of separate sensor elements surrounding the application area and, hence, the skin detector accuracy increase without requiring a more complex (and more expensive) control circuit and more extensive wiring.
  • the skin detector of the skin treatment device according to the invention is particularly suitable for
  • the skin detector may still comprise one or more sets with a single sensor element.
  • the predefined desired positions of the sensor elements may relate to relative positions of the sensor elements with respect to the skin in x, y and z dimensions.
  • the predefined desired positions may also relate to a specific distance of the sensor elements from the skin, or to a distance from the skin that must be within a certain interval.
  • the at least one second sensor element is arranged in between two neighboring first sensor elements, which means that two neighboring first sensor elements are not directly adjacent to each other. At least one second sensor element is arranged in between them, and one or more other sensor elements of another set may also be arranged in between two neighboring first sensor elements.
  • the sensor elements are arranged around the application area and two first sensor elements are neighbors when, looking along the direction of the edge of the application area, no other first sensor element is in between the first sensor elements.
  • the sensor elements are arranged around the application area, which means that they have a mechanical arrangement corresponding with a loop around the application area.
  • the sensor elements of a single set are coupled to a single input of the control circuit.
  • the term 'coupled' means that the sensor elements may be coupled directly via an electrical connection to the single input, however, it may also mean that all sensor elements, or a single sensor element of the set, are indirectly coupled to the input, for example via an intermediate electrical component or circuit.
  • the sensor elements of a single set may be arranged in a series or in a parallel arrangement and the series or parallel arrangement is connected to the input, or the sensor elements may be connected to an intermediate sub-circuit which adapts the signals provided by the sensor elements towards a signal suitable for reception by the input of the control circuit.
  • the first sensor elements are contact sensors for sensing contact with the skin
  • the at least one second sensor element is a contact sensor for sensing contact with the skin.
  • the decision circuit is configured for supplying the activating signal if the first detection signal indicates that all the first sensor elements contact the skin and the second detection signal indicates that the at least one second sensor element all contact the skin.
  • the skin treatment device prevents that the skin treatment device is activated without the application area being in contact with the skin. That is to say, if all the sensor elements are in contact with the skin, the skin treatment device has the required contact with the skin, which means that the application area has a required position with respect to the skin.
  • this embodiment provides safe operation of the skin treatment device.
  • the detection of contact with the skin does not directly imply that the application area is in full contact with the skin. If the application area and the skin detector are in the same plane, the detection of full contact implies that the application area is in full contact with the skin when the sensor elements are well distributed around the application area.
  • the first sensor elements and/or the at least one second sensor element comprise capacitive, inductive or resistive sensors comprising an electrically conductive area for cooperating with the skin to determine whether the first sensor elements and/or the at least one second sensor element are in contact with the skin.
  • the conductive areas of the first sensor elements are electrically coupled to the first input and/or the conductive areas of the at least one second element are electrically coupled to the second input.
  • capacitive, inductive or resistive sensor elements are effective and efficient means to detect whether the skin detector is in contact with the skin. They are relatively cheap and allow the manufacture of a relatively cheap skin detector without reducing the accuracy of the skin detector.
  • the first sensor elements comprise mechanical switches arranged in series and/or the at least one second sensor element comprises a mechanical switch.
  • the mechanical switches are, for example, closed when the sensor elements are in contact with the skin. Only when all mechanical switches of the first sensor elements are closed, the first detection signal indicates that all switches are closed.
  • the first sensor elements and/or the at least one second sensor element are selected from the group of a light sensor, a physical pressure sensor, a gas pressure sensor, a gas flow sensor and/or a heat conductivity sensor.
  • a physical pressure sensor may be a piezoelectric element that provides an electrical signal upon being pressed, or may be a touch sensor with, for example, a relay that makes or breaks an electrical contact upon being (com)pressed.
  • a gas pressure sensor or a gas flow sensor may be used, for example, in a situation where a gas flow is maintained through openings in a housing of the skin treatment device.
  • a gas may be supplied or a vacuum may be supplied.
  • a light sensor may sense specific characteristics of skin, such as a color, a reflectance and/or diffusion of light.
  • the light may be environmental light, or the light sensor comprises a light emitter for emitting light towards the skin.
  • the decision circuit is configured to supply the activating signal only if the first detection signal indicates that all first sensor elements have predefined desired positions with respect to the skin and the second detection signal indicates that the at least one second sensor element all have predefined desired positions with respect to the skin. If the activating signal is only provided in this specific situation, it is prevented that the skin treatment device starts its operation when at least one of the sensor elements is not at the predefined desired position.
  • the second set of the skin detector comprises a plurality of second sensor elements and all second sensor elements are coupled to the second input to obtain the second detection signal.
  • the second set also comprises a plurality of second sensor elements, the accuracy of the skin detector of the skin treatment device increases without an increase of the complexity of the system, i.e. without a control circuit comprising more than two inputs being required.
  • the application area has multiple sides and each sensor element of each set of sensors elements is arranged along a different side of the application area.
  • the application area may, e.g., be rectangular or triangular.
  • the first sensor elements and the second sensor elements are arranged alternatingly around the application area.
  • the accuracy of the skin detector is not significantly increased.
  • the skin detector further comprises a third set comprising at least one third sensor element, and a fourth set comprising at least one fourth sensor element, wherein the at least one third sensor element and the at least one fourth sensor element are also arranged, together with the first sensor elements and the second sensor elements, around the application area.
  • the control circuit further comprises a third input and a fourth input, wherein the at least one third sensor element is coupled to the third input to obtain a third detection signal and the at least one fourth sensor element is coupled to the fourth input to obtain a fourth detection signal.
  • the decision circuit is configured to supply the activating signal if the first detection signal indicates that all first sensor elements have predefined desired positions with respect to the skin, the second detection signal indicates that all second sensor elements have predefined desired positions with respect to the skin, the third detection signal indicates that the at least one third sensor element all have predefined desired positions with respect to the skin, and the fourth detection signal indicates that the at least one fourth sensor element all have predefined desired positions with respect to the skin.
  • the activating signal is generated if all detection signals indicate that all sensor elements have predefined desired positions with respect to the skin.
  • each set is coupled to a separate input of the control circuit, a more accurate skin detector is obtained.
  • the sensor elements of the third set and of the fourth set may be equal to the first sensor elements and the second elements of the previously discussed embodiments.
  • a sequence of sensor elements is formed by one of the first sensor elements, one of the second sensor elements, the at least one third sensor element, another one of the first sensor elements, another one of the second sensor elements and the at least one fourth sensor element.
  • the arrangement of the sensor elements according to this embodiment being a relatively small amount of sensor elements, results in a relatively high accuracy to detect whether the sensor elements have predefined desired positions with respect to the skin.
  • Such an arrangement is, for example, advantageous when the application area is rectangular.
  • the rectangular application area comprises a first and a third side which are shorter than a second and a fourth side.
  • the at least one third sensor element is provided on the first side.
  • the third side is opposite the first side and the at least one fourth sensor element is provided on the third side.
  • the one of the first sensor elements and the one of the second sensor elements are provided on the second side.
  • the second side is opposite the fourth side and the another one of the first sensor elements and the another one of the second sensor elements are provided on the fourth side.
  • the third set comprises a plurality of third sensor elements and all third sensor elements are coupled to the third input to obtain the third detection signal.
  • the fourth set comprises a plurality of fourth sensor elements and all fourth sensor elements are coupled to the fourth input to obtain the fourth detection signal. If the third set and the fourth set have also more than one sensor element, the skin detector of the skin treatment device is better capable of detecting whether the sensor elements (and, thus, the application area) have predefined desired positions with respect to the skin. Furthermore, in line with earlier discussed advantages, although the amount of sensor elements is relatively large, the control circuit comprises only four inputs and, as such, the skin treatment device does not become unnecessarily complex.
  • a sequence of sensor elements comprises at least one sub-sequence, wherein the at least one sub-sequence comprises one first sensor element, one second sensor element, one third sensor element and one fourth sensor element.
  • the sequence of sensor elements may comprise a plurality of sub- sequences and each such sub-sequence may comprises at least one sensor element of each set of sensor elements. This arrangement of sensor elements around the application area significantly increases the accuracy of the skin detector device.
  • the skin treatment device is activated when the decision circuit generates the activating signal.
  • the treatment is only applied via the application area when the application area has a predefined desired position with respect to the skin. This enhances the efficacy of the treatment and the safe use of the skin treatment device.
  • Figure 1 schematically shows a skin detector
  • Figure 2a shows an electronic scheme of a standard skin detector
  • Figure 2b shows exemplary signals as detected by the skin detector of figure
  • Figure 3 a shows an electronic scheme of a standard skin detector in contact with skin
  • Figure 3b shows exemplary signals as detected by the skin detector of figure
  • Figure 4a shows another electronic scheme of a standard skin detector in contact with skin
  • Figure 4b shows exemplary signals as detected by the skin detector of figure
  • Figure 5 a shows an electronic scheme of a skin detector with sensor elements
  • Figure 5b shows exemplary signals as detected by the skin detector of figure 5a
  • Figure 6a shows an electronic scheme of a skin detector having sensor elements and being in contact with skin
  • Figure 6b shows exemplary signals as detected by the skin detector of figure
  • Figure 7a shows another electronic scheme of a skin detector having sensor elements and being in contact with skin
  • Figure 7b shows exemplary signals as detected by the skin contact detector of figure 7a
  • Figure 8 shows an electronic scheme of a skin contact detector with four sensor elements
  • Figure 9 shows an electronic scheme of a skin detector with twelve sensor elements
  • Figure 10 shows a specific configuration of sensor elements around an application area
  • Figure 11 schematically shows a skin treatment device comprising a skin contact detector.
  • FIG. 1 schematically shows a (stand, known) skin detector 10.
  • the detector comprises a sensor PCB (printed circuit board) 14 with at least one sensor plate, housed in an application housing 15 which is to be applied to a human or animal skin 90.
  • the sensor plate is coupled to an input of a control circuit 11 via an input line 13.
  • Other input lines 13 may be provided for coupling additional sensor plates to corresponding inputs of the control circuit 11.
  • multiple sensor plates are used, they are preferably arranged on one and the same PCB 14 and their input lines 13 may be combined into a single bus connecting the PCB to the control circuit 11.
  • multiple PCBs 14 are provided, each PCB 14 comprising one or more sensor plates and its own connection with the control circuit 11.
  • the control circuit 1 1 is operative to measure a skin response signal from the sensor plate. Based on the measured skin response signal, the control circuit 11 generates a skin contact signal indicating whether the sensor plate is or is not in contact with skin 90.
  • the sensor plate is provided adjacent to an application area 91, and it must be detected whether this application area is in contact with the skin 90.
  • the skin detector 10 is typically used in a shaving or skin rejuvenation device that is used for applying a treatment to this application area 91.
  • the treatment may, e.g., involve cutting hair or light-based skin rejuvenation.
  • the skin detector 10 preferably uses multiple sensor elements arranged around the application area 91.
  • Figure 2a shows an electronic scheme of a (known) standard skin detector.
  • the detector comprises four sensors 16 SI, S2, S3 and S4.
  • the sensors 16 are provided around the application area 91 for which the presence of skin contact is to be determined.
  • Each sensor 16 has its own input line 13 for connecting to the control circuit 11.
  • the four input lines 13 may be combined in a single input bus.
  • Figure 2b shows exemplary skin response signals as detected by the skin detector of figure 2a when there is no skin at the application area 91.
  • the skin response signals are detected by the control circuit 11.
  • all four sensors SI, S2, S3 and S4 give a skin response signal at a quiescent level 21 which is well below a skin contact threshold level 22.
  • the control circuit 11 receives the skin response signals and determines that there is no skin contact.
  • Figure 3 a shows an electronic scheme of the standard skin detector 10 of figure 2a, but now in contact with skin 90.
  • the skin contact 90 covers only part of the application area 91. Only at the sensors SI and S2, the skin detector 10 is in contact with the skin 90.
  • Figure 3b shows exemplary signals as detected by the skin detector of figure 3 a.
  • the full skin contact of the sensors SI and S2 results in the corresponding skin response signals being well above the skin contact threshold level 22.
  • the skin response signals from the two sensors S3 and S4 that are not at all in contact with the skin 90 are still at the quiescent level 21.
  • the control circuit Based on the four skin response signals, the control circuit generates a skin contact signal.
  • the skin contact signal may only indicate a skin contact when all four skin response signals are above the skin contact threshold level 22 or also when only one, two or three skin response signals are above the threshold. For optimum safety, it is preferred to only indicate skin contact when all four skin response signals are above the threshold 22. In the situation shown in Figure 3a, with only two out of four skin response signals being above the skin contact threshold level 22, the skin contact signal may also indicate a partial contact.
  • Figure 4a shows another electronic scheme of the standard skin detector of figure 2a when in contact with skin 90.
  • the application area 91 is almost completely covered by skin. Only a small area at the bottom left of the application area is not covered by skin 90.
  • the sensors S3 and S4 are partly covered by skin 90.
  • Figure 4b shows exemplary signals as detected by the skin detector 10 of figure 4a. The only partly covered sensors S3 and S4 give a response that is slightly lower than the response of the fully covered sensor elements SI and S2. However, all four skin response signals are above the skin contact threshold 22 and the control circuit will thus generate a skin contact signal indicating a full skin contact. From a safety perspective this may not be a desirable result.
  • a laser beam passing through the uncovered application area 91 may still be harmful.
  • adjusting the threshold level 22 might seem an obvious solution. Increasing the threshold level 22 would, however, reduce the sensitivity of the skin detector and may result in the skin sensor not being able to detect all genuine full skin contacts.
  • a skin treatment device 100 according to the first aspect of the invention is shown which is in contact with skin 90.
  • the skin treatment device 100 applies a treatment via an application area 130 of the skin treatment device 100 to a portion of skin 90 of a human or an animal.
  • a skin detector 10 is provided close to and, in an embodiment, around the application area. Later in this section of the application, the skin treatment device 100 is discussed. In subsequent figures, embodiments of the skin detector 10 are discussed.
  • FIG. 5a schematically shows an electronic scheme of a skin detector with sensor elements 56 according to the invention.
  • the skin detector comprises a control circuit 11, a first set of sensor elements 56 1A, IB, a second set of sensor elements 56 2A, 2B, a third set of sensor elements 56 3A, 3B and a fourth set of sensor elements 56 4A, 4B.
  • the sensor elements 56 are arranged around the application area 91.
  • the sensor elements 56 of a single set are coupled via electrical connections 13 to a single input of the control circuit 11 for generating, for each set of sensor elements, a detection signal.
  • the sensor elements 56 are used to detect whether each one of the sensor elements 56 has a predefined position with respect to skin, for example, whether they are in contact with the skin or whether they have a specific distance with respect to the skin. Unless mentioned otherwise, in the following part of this application, it is assumed that the predefined desired position is a position where the sensor element 56 is in contact with skin - but, in all embodiments one may read instead of "in contact with the skin" "at a predefined distance from the skin”.
  • the control circuit 11 comprises a decision circuit 12 which supplies an activating signal to the skin treatment device if the first detection signal indicates that all sensor elements 56 1A, IB have predefined desired positions with respect to a skin, the second detection signal indicates that all second sensor elements 56 2 A, 2B have predefined desired positions with respect to a skin, the third detection signal indicates that all third sensor elements 56 3A, 3B have predefined desired positions with respect to a skin, and the fourth detection signal indicates that all fourth sensor elements 56 4 A, 4B have predefined desired positions with respect to a skin.
  • the activating signal may be used by the skin treatment device to activate its primary treatment operation.
  • At least one sensor element 56 2B of the second set of sensor elements is arranged in between two neighboring sensor elements 56 1 A, IB of the first set.
  • the skin detector becomes more accurate. This is further discussed in the context of Figure 7a and 7b.
  • sensor elements of other sets are also arranged in an interwoven configuration, which means that two sensor elements of one set are not directly adjacent to each other when the sensor elements are arranged in a sequence of sensor elements provided along the circumference of the application area 91.
  • the skin treatment device comprises a skin detector and an application area 91 for applying the treatment to a portion of the skin.
  • the skin detector comprises a control circuit 11 comprising a first input and a second input.
  • the skin detector further comprises a fist set of a plurality of first sensor elements 56 1A, IB coupled to the first input and a second set of at least one second sensor element 56, 2A coupled to the second input. All sensor elements 56 are arranged around the application area 91, and in between two neighboring first sensor elements 56 1A, IB there is provided a second sensor element 56 2B.
  • the control circuit 1 1 comprises a decision circuit 12 for supplying an activating signal for activating the skin treatment device if the first sensor elements 56 1A, IB and the at least one second sensor element 56, 2B all have predefined desired positions with respect to the skin.
  • Figure 5b shows exemplary detection signals as detected by the skin detector of figure 5 a. Because there is no skin contact, all four skin response signals are at the quiescent level 21.
  • Figure 6a shows an electronic scheme of the skin detector of figure 5 a with sensor elements 56 in contact with skin 90. Like in Figure 3b, only part of the application area 91 is in contact with the skin 90. Sensor elements IB, 2B, 1A and 2A are in contact with the skin 90. Sensor elements 4B, 3B, 4A and 3A are not in contact with skin.
  • Figure 6b shows exemplary detection signals as detected by the skin detector of Figure 6a.
  • the sensor elements 1A and IB are coupled to a common input line 13, and, thus, to a single input of the control circuit 11. Both sensor elements contribute to the first skin response signal exceeding the skin contact threshold level 22. The same holds for the combined detection signal of sensor elements 2 A and 2B.
  • the other sensor elements are not covered by skin 90 and the corresponding skin response signals are thus at the quiescent level 21. In this situation, the response signals are similar to the skin response signals of the similar situation elucidated with reference to figure 3b.
  • FIG. 7a shows exemplary detection signals as detected by the skin detector of Figure 7a.
  • the sensor elements 1A and IB are coupled to a common input line 13, and thus to a single input of the control circuit 11 , and both contribute to the first detection signal exceeding the skin contact threshold level 22. The same holds for the combined detection signal of sensor elements 2A and 2B.
  • the partly covered sensor elements 3 A and 4B provide a detection signal slightly below the skin response signals from the fully covered sensor elements 1A, IB, 2A and 2B.
  • the uncovered sensor elements 3B and 4A do not provide any contribution to the detection signal at all.
  • the combined result then is that the third and fourth combined detection signals are well below the skin contact threshold level 22, which makes it possible to distinguish this almost full skin contact from a full skin contact. Using only the four sensor elements of figures 4a and 4b, this would not be possible.
  • Figure 8 shows an electronic scheme of a skin detector with four sensor elements 56.
  • Sensor elements 1A and IB are jointly coupled to a single input of the control circuit 11 by one input line 13 and so are the sensor elements 2 A and 2B.
  • this one can provide a similar accuracy while requiring only two input lines 13 to be connected to the control circuit 11. Consequently, a simpler and cheaper control circuit 1 1 may be used without compromising accuracy.
  • Figure 9 shows an electronic scheme of a skin detector with twelve sensor elements 56.
  • each set of sensor elements comprises three sensor elements 56 which are jointly coupled to a single input of the control circuit via one and the same input line (input lines and control circuit not shown).
  • those sensor elements 56 that are coupled to the same input lines are interspersed by other sensor elements 56 of another set.
  • FIG 10 schematically shows another embodiment of the skin detector of a skin treatment device.
  • the skin treatment device comprises a rectangular application area 91.
  • a fourth sensor element 56, 4 of a fourth set At the opposing shorter sides of the rectangular application area 91 there are provided, at a first side, a fourth sensor element 56, 4 of a fourth set and, at a second side, a sensor element 56, 3 of a third set of sensor elements.
  • At the longer opposing sides of the rectangular application area 91 there are provided, at each side, one sensor element 56 2A, 2B of the second set of sensor elements and one sensor element 56 1A, IB of the first set of sensor elements.
  • the sensor elements of the first set are coupled to the first input II of a control circuit 1 1
  • the sensor elements of the second set are coupled to the second input 12 of the control circuit 1
  • the sensor elements of the third set are coupled to the third input 13 of the control circuit 11
  • the sensor elements of the fourth set are coupled to the fourth input 14 of the control circuit 11.
  • the control circuit 11 comprises the decision circuit 12.
  • FIG 11 schematically shows a skin treatment device 100 which comprises one of the skin detectors 10 as described above.
  • the skin treatment device 100 is configured to be in a predefined desired position with respect to the skin 90 before being activated.
  • an application area 130 of the skin treatment device needs to be in this predefined desired position.
  • the treatment is provided to the skin 90 via the application area 130.
  • the predefined position is a position in which the application area 130 is in contact with the skin 90.
  • the skin treatment device 100 may e.g. be a shaving device or a skin rejuvenation device.
  • the skin treatment device 100 comprises a light source 101 for producing a light beam 120 for treating the skin 90.
  • Optical elements like lenses 102 and mirrors 103 may be provided for focusing the light beam 120 at the skin area to be treated.
  • the light source 101 and the operation of the skin treatment device 110 is controlled by a device control circuit 110, which is coupled to the control circuit 11 of the skin detector 10.
  • the control circuit 11 comprises a decision circuit 12 which is configured to decide whether the application area 130 is in contact with the skin 90.
  • the light source 101 is operated in dependence on the activating signal from the decision circuit 12 of the skin detector 10.
  • both control circuits 1 1, 110 are integrated into a single control circuit for operating both the skin detector 10 and the skin treatment device 100 as a whole.
  • the skin treatment device 100 is operated such that the light beam 120 for treating the skin 90 is only provided if the skin detector detects full skin contact.
  • the skin treatment device uses light for obtaining a therapeutic effect.
  • other means may be used to provide therapy to a portion of the skin which occupies the predefined desired position with respect to the application area.
  • the skin treatment device may apply heat, or a gas, or, in another embodiment, mechanical forces to the top layer of the skin.

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Abstract

A skin treatment device is provided which comprises a skin detector and an application area 91 for applying the treatment to a portion of a skin. The skin detector comprises a control circuit comprising a first input and a second input. The skin detector further comprises a fist set of a plurality of first sensor elements 56,1A, 1B coupled to the first input and a second set of at least one second sensor element 56, 2A coupled to the second input. All sensor elements 56 are arranged around the application area 91 and the second sensor element 56 2B is arranged in between two neighboring first sensor elements 56, 1A, 1B. The control circuit 11 comprises a decision circuit 12 which supplies an activating signal to activate the skin treatment device if the first sensor elements 56,1A, 1B and the at least one second sensor element 56, 2B all have predefined desired positions with respect to the skin.

Description

SKIN TREATMENT DEVICE HAVING A SKIN DETECTOR
FIELD OF THE INVENTION
This invention relates to skin treatment devices comprising a skin detector.
BACKGROUND OF THE INVENTION
A skin treatment device with a skin detector is, e.g., disclosed in the United
States patent application, published as US 2009/0043294 Al . Said application describes a dermatologic treatment device with a skin proximity sensor. The skin proximity sensor comprises a window, surrounded by a bezel with a plurality of capacitive sensors. Control circuitry is coupled to the capacitive sensors to observe changes in capacitance due to (lack of) skin contact. When no skin is sensed, operation of the dermatologic treatment device is inhibited. In an embodiment of said skin proximity sensor, the bezel comprises three capacitive sensors distributed around a circular orifice.
When such a proximity sensor lacks accuracy or sensitivity, the skin proximity sensor may cause an incorrect interpretation of the signals from the capacitive sensors. For example, it may indicate skin contact when the orifice is actually not covering the skin or vice versa. Typically, when the treatment application area is nearly fully covered by skin, this may be wrongly interpreted as full coverage. Especially with a skin treatment device using high power light sources this may result in undesirable safety risks because of powerful light beams not impinging on a skin to be treated but, e.g., on a human or animal eye.
An additional aspect that is important when developing a skin treatment device having a suitable skin detector is to reduce complexity. Complex skin detectors are more susceptible to failure and increase manufacturing costs.
OBJECT OF THE INVENTION
It is an object of the invention to provide a skin treatment device with a simple skin detector having improved detection accuracy. SUMMARY OF THE INVENTION
A skin treatment device for treating a portion of a skin in accordance with a first aspect of the invention comprises an application area and a skin detector. A treatment is provided through the application area to the portion of the skin. The skin detector is for detecting whether the application area has a predefined desired position with respect to the skin. The skin detector comprises a first set of a plurality of first sensor elements, a second set of at least one second sensor element and a control circuit comprising a first input and a second input. The first sensor elements and the at least one second sensor element are arranged around the application area. The first sensor elements are coupled to the first input to obtain a first detection signal and the at least one second sensor element is coupled to the second input to obtain a second detection signal. Looking along a direction of an edge of the application area, the at least one second sensor element is arranged in between two neighboring first sensor elements. The control circuit comprises a decision circuit for supplying an activating signal to activate the skin treatment device if the first detection signal indicates that all first sensor elements have predefined desired positions with respect to the skin and the second detection signal indicates that the at least one second sensor element all have predefined desired positions with respect to the skin.
The skin treatment device according to the invention makes it possible to obtain improved skin detector accuracy without significantly increasing its complexity.
Because the first sensor elements share the first input of the control circuit, the number of separate sensor elements surrounding the application area and, hence, the skin detector accuracy increase without requiring a more complex (and more expensive) control circuit and more extensive wiring.
As will be elucidated below with reference to, e.g., figure 7, the skin detector of the skin treatment device according to the invention is particularly suitable for
distinguishing an application area fully covered by skin from an application area nearly fully covered by skin. A mere splitting up of sensors into two or more sensor elements would not result in the same advantages. The joint connection of multiple sensor elements to a common input of the control circuit would counteract most of the advantageous changes resulting from the splitting up of the sensors. However, by spatially separating the sensor elements, distributing them around the application area and interspersing the sensor elements of the first set with sensor elements of the second set, the chance of incorrectly detecting the application area to be fully covered by skin is considerably reduced. It is to be noted that, in addition to the first set of split-up first sensor elements, the skin detector may still comprise one or more sets with a single sensor element. The advantages of the current invention are already obtained when only one or a few sets comprising more than one sensor element is or are present and when at least one sensor element of a different set is arranged in between two neighboring sensor elements of the first set.
It is to be noted that the predefined desired positions of the sensor elements may relate to relative positions of the sensor elements with respect to the skin in x, y and z dimensions. Thus, the predefined desired positions may also relate to a specific distance of the sensor elements from the skin, or to a distance from the skin that must be within a certain interval.
According to the invention, looking along the direction of the edge of the application area, the at least one second sensor element is arranged in between two neighboring first sensor elements, which means that two neighboring first sensor elements are not directly adjacent to each other. At least one second sensor element is arranged in between them, and one or more other sensor elements of another set may also be arranged in between two neighboring first sensor elements. The sensor elements are arranged around the application area and two first sensor elements are neighbors when, looking along the direction of the edge of the application area, no other first sensor element is in between the first sensor elements.
The sensor elements are arranged around the application area, which means that they have a mechanical arrangement corresponding with a loop around the application area.
It is further to be noted that the sensor elements of a single set are coupled to a single input of the control circuit. The term 'coupled' means that the sensor elements may be coupled directly via an electrical connection to the single input, however, it may also mean that all sensor elements, or a single sensor element of the set, are indirectly coupled to the input, for example via an intermediate electrical component or circuit. For example, the sensor elements of a single set may be arranged in a series or in a parallel arrangement and the series or parallel arrangement is connected to the input, or the sensor elements may be connected to an intermediate sub-circuit which adapts the signals provided by the sensor elements towards a signal suitable for reception by the input of the control circuit.
In an embodiment of the skin treatment device according to the invention, the first sensor elements are contact sensors for sensing contact with the skin, and the at least one second sensor element is a contact sensor for sensing contact with the skin. In this embodiment, the decision circuit is configured for supplying the activating signal if the first detection signal indicates that all the first sensor elements contact the skin and the second detection signal indicates that the at least one second sensor element all contact the skin.
Especially when the skin treatment device needs to be in contact with the skin, the skin treatment device according to this embodiment prevents that the skin treatment device is activated without the application area being in contact with the skin. That is to say, if all the sensor elements are in contact with the skin, the skin treatment device has the required contact with the skin, which means that the application area has a required position with respect to the skin. When, for example, the skin treatment device emits light on the skin through the application area and this light must not be transmitted to the eyes of a person, this embodiment provides safe operation of the skin treatment device. It is to be noted that, if the application area is provided within a recess of the skin treatment device and the skin detector protrudes from the skin treatment device, the detection of contact with the skin does not directly imply that the application area is in full contact with the skin. If the application area and the skin detector are in the same plane, the detection of full contact implies that the application area is in full contact with the skin when the sensor elements are well distributed around the application area.
In a further embodiment of the skin treatment device according to the invention, the first sensor elements and/or the at least one second sensor element comprise capacitive, inductive or resistive sensors comprising an electrically conductive area for cooperating with the skin to determine whether the first sensor elements and/or the at least one second sensor element are in contact with the skin. In this embodiment, the conductive areas of the first sensor elements are electrically coupled to the first input and/or the conductive areas of the at least one second element are electrically coupled to the second input. Such capacitive, inductive or resistive sensor elements are effective and efficient means to detect whether the skin detector is in contact with the skin. They are relatively cheap and allow the manufacture of a relatively cheap skin detector without reducing the accuracy of the skin detector.
In a further embodiment of the skin treatment device according to the invention, the first sensor elements comprise mechanical switches arranged in series and/or the at least one second sensor element comprises a mechanical switch. The mechanical switches are, for example, closed when the sensor elements are in contact with the skin. Only when all mechanical switches of the first sensor elements are closed, the first detection signal indicates that all switches are closed.
Optionally, the first sensor elements and/or the at least one second sensor element are selected from the group of a light sensor, a physical pressure sensor, a gas pressure sensor, a gas flow sensor and/or a heat conductivity sensor. Each such sensor may be used according to principles known to those skilled in the art. For example, the physical pressure sensor may be a piezoelectric element that provides an electrical signal upon being pressed, or may be a touch sensor with, for example, a relay that makes or breaks an electrical contact upon being (com)pressed. A gas pressure sensor or a gas flow sensor may be used, for example, in a situation where a gas flow is maintained through openings in a housing of the skin treatment device. A gas may be supplied or a vacuum may be supplied. In either case the gas flow (or pressure) will suddenly change upon the sensor contacting the skin. A light sensor may sense specific characteristics of skin, such as a color, a reflectance and/or diffusion of light. The light may be environmental light, or the light sensor comprises a light emitter for emitting light towards the skin.
In a further embodiment of the skin treatment device according to the invention, the decision circuit is configured to supply the activating signal only if the first detection signal indicates that all first sensor elements have predefined desired positions with respect to the skin and the second detection signal indicates that the at least one second sensor element all have predefined desired positions with respect to the skin. If the activating signal is only provided in this specific situation, it is prevented that the skin treatment device starts its operation when at least one of the sensor elements is not at the predefined desired position.
In a further embodiment of the skin treatment device according to the invention, the second set of the skin detector comprises a plurality of second sensor elements and all second sensor elements are coupled to the second input to obtain the second detection signal. When the second set also comprises a plurality of second sensor elements, the accuracy of the skin detector of the skin treatment device increases without an increase of the complexity of the system, i.e. without a control circuit comprising more than two inputs being required.
In a further embodiment of the skin treatment device according to the invention, the application area has multiple sides and each sensor element of each set of sensors elements is arranged along a different side of the application area. The application area may, e.g., be rectangular or triangular. When the different sensor elements of each set are situated on different sides of the application area, the detection signal provided at the associated input of the control circuit will only exceed a detection threshold when all sensor elements of the set and, thus, large parts of the application area, are covered by skin.
In a further embodiment of the skin treatment device according to the invention, looking along the direction of the edge of the application area, the first sensor elements and the second sensor elements are arranged alternatingly around the application area. As discussed previously, when sensor elements of a single set are arranged directly adjacent to each other, the accuracy of the skin detector is not significantly increased. By arranging the sensor elements of the first set and of the second set in an alternating configuration, the accuracy is increased.
In a further embodiment of the skin treatment device according to the invention, the skin detector further comprises a third set comprising at least one third sensor element, and a fourth set comprising at least one fourth sensor element, wherein the at least one third sensor element and the at least one fourth sensor element are also arranged, together with the first sensor elements and the second sensor elements, around the application area. In this embodiment, the control circuit further comprises a third input and a fourth input, wherein the at least one third sensor element is coupled to the third input to obtain a third detection signal and the at least one fourth sensor element is coupled to the fourth input to obtain a fourth detection signal. The decision circuit is configured to supply the activating signal if the first detection signal indicates that all first sensor elements have predefined desired positions with respect to the skin, the second detection signal indicates that all second sensor elements have predefined desired positions with respect to the skin, the third detection signal indicates that the at least one third sensor element all have predefined desired positions with respect to the skin, and the fourth detection signal indicates that the at least one fourth sensor element all have predefined desired positions with respect to the skin. In other words, the activating signal is generated if all detection signals indicate that all sensor elements have predefined desired positions with respect to the skin.
By using more sets of sensor elements, wherein each set is coupled to a separate input of the control circuit, a more accurate skin detector is obtained. It is to be noted that the sensor elements of the third set and of the fourth set may be equal to the first sensor elements and the second elements of the previously discussed embodiments.
In a further embodiment of the skin treatment device according to the invention, looking along the direction of the edge of the application area, a sequence of sensor elements is formed by one of the first sensor elements, one of the second sensor elements, the at least one third sensor element, another one of the first sensor elements, another one of the second sensor elements and the at least one fourth sensor element.
The arrangement of the sensor elements according to this embodiment, being a relatively small amount of sensor elements, results in a relatively high accuracy to detect whether the sensor elements have predefined desired positions with respect to the skin. Such an arrangement is, for example, advantageous when the application area is rectangular. The rectangular application area comprises a first and a third side which are shorter than a second and a fourth side. The at least one third sensor element is provided on the first side. The third side is opposite the first side and the at least one fourth sensor element is provided on the third side. The one of the first sensor elements and the one of the second sensor elements are provided on the second side. The second side is opposite the fourth side and the another one of the first sensor elements and the another one of the second sensor elements are provided on the fourth side.
In a further embodiment of the skin treatment device according to the invention, the third set comprises a plurality of third sensor elements and all third sensor elements are coupled to the third input to obtain the third detection signal. In this
embodiment, the fourth set comprises a plurality of fourth sensor elements and all fourth sensor elements are coupled to the fourth input to obtain the fourth detection signal. If the third set and the fourth set have also more than one sensor element, the skin detector of the skin treatment device is better capable of detecting whether the sensor elements (and, thus, the application area) have predefined desired positions with respect to the skin. Furthermore, in line with earlier discussed advantages, although the amount of sensor elements is relatively large, the control circuit comprises only four inputs and, as such, the skin treatment device does not become unnecessarily complex.
In a further embodiment of the skin treatment device according to the invention, looking along the direction of the edge of the application area, a sequence of sensor elements comprises at least one sub-sequence, wherein the at least one sub-sequence comprises one first sensor element, one second sensor element, one third sensor element and one fourth sensor element. The sequence of sensor elements may comprise a plurality of sub- sequences and each such sub-sequence may comprises at least one sensor element of each set of sensor elements. This arrangement of sensor elements around the application area significantly increases the accuracy of the skin detector device.
In a further embodiment of the skin treatment device according to the invention, the skin treatment device is activated when the decision circuit generates the activating signal. In other words, the treatment is only applied via the application area when the application area has a predefined desired position with respect to the skin. This enhances the efficacy of the treatment and the safe use of the skin treatment device.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
It will be appreciated by those skilled in the art that two or more of the above- mentioned options, implementations, and/or aspects of the invention may be combined in any way deemed useful.
Modifications and variations of the system, the method, and/or of the computer program product, which correspond to the described modifications and variations of the system, can be carried out by a person skilled in the art on the basis of the present description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Figure 1 schematically shows a skin detector,
Figure 2a shows an electronic scheme of a standard skin detector,
Figure 2b shows exemplary signals as detected by the skin detector of figure
2a,
Figure 3 a shows an electronic scheme of a standard skin detector in contact with skin,
Figure 3b shows exemplary signals as detected by the skin detector of figure
3 a,
Figure 4a shows another electronic scheme of a standard skin detector in contact with skin,
Figure 4b shows exemplary signals as detected by the skin detector of figure
4a,
Figure 5 a shows an electronic scheme of a skin detector with sensor elements, Figure 5b shows exemplary signals as detected by the skin detector of figure 5a,
Figure 6a shows an electronic scheme of a skin detector having sensor elements and being in contact with skin,
Figure 6b shows exemplary signals as detected by the skin detector of figure
6a, Figure 7a shows another electronic scheme of a skin detector having sensor elements and being in contact with skin,
Figure 7b shows exemplary signals as detected by the skin contact detector of figure 7a,
Figure 8 shows an electronic scheme of a skin contact detector with four sensor elements,
Figure 9 shows an electronic scheme of a skin detector with twelve sensor elements,
Figure 10 shows a specific configuration of sensor elements around an application area, and
Figure 11 schematically shows a skin treatment device comprising a skin contact detector.
It should be noted that items denoted by the same reference numerals in different Figures have the same structural features and the same functions, or are the same signals. If the function and/or structure of such an item have already been explained, there is no necessity for repeated explanation thereof in the detailed description.
The Figures are purely diagrammatic and not drawn to scale. Particularly for clarity, some dimensions are exaggerated strongly. DETAILED DESCRIPTION OF THE INVENTION
Figure 1 schematically shows a (stand, known) skin detector 10. The detector comprises a sensor PCB (printed circuit board) 14 with at least one sensor plate, housed in an application housing 15 which is to be applied to a human or animal skin 90. The sensor plate is coupled to an input of a control circuit 11 via an input line 13. Other input lines 13 may be provided for coupling additional sensor plates to corresponding inputs of the control circuit 11. When multiple sensor plates are used, they are preferably arranged on one and the same PCB 14 and their input lines 13 may be combined into a single bus connecting the PCB to the control circuit 11. Alternatively, multiple PCBs 14 are provided, each PCB 14 comprising one or more sensor plates and its own connection with the control circuit 11. The control circuit 1 1 is operative to measure a skin response signal from the sensor plate. Based on the measured skin response signal, the control circuit 11 generates a skin contact signal indicating whether the sensor plate is or is not in contact with skin 90.
The sensor plate is provided adjacent to an application area 91, and it must be detected whether this application area is in contact with the skin 90. The skin detector 10 is typically used in a shaving or skin rejuvenation device that is used for applying a treatment to this application area 91. The treatment may, e.g., involve cutting hair or light-based skin rejuvenation. The skin detector 10 preferably uses multiple sensor elements arranged around the application area 91.
Figure 2a shows an electronic scheme of a (known) standard skin detector.
The detector comprises four sensors 16 SI, S2, S3 and S4. The sensors 16 are provided around the application area 91 for which the presence of skin contact is to be determined. Each sensor 16 has its own input line 13 for connecting to the control circuit 11. The four input lines 13 may be combined in a single input bus.
Figure 2b shows exemplary skin response signals as detected by the skin detector of figure 2a when there is no skin at the application area 91. The skin response signals are detected by the control circuit 11. In this situation with no skin at the application area 91, all four sensors SI, S2, S3 and S4 give a skin response signal at a quiescent level 21 which is well below a skin contact threshold level 22. The control circuit 11 receives the skin response signals and determines that there is no skin contact.
Figure 3 a shows an electronic scheme of the standard skin detector 10 of figure 2a, but now in contact with skin 90. The skin contact 90 covers only part of the application area 91. Only at the sensors SI and S2, the skin detector 10 is in contact with the skin 90. Figure 3b shows exemplary signals as detected by the skin detector of figure 3 a. The full skin contact of the sensors SI and S2 results in the corresponding skin response signals being well above the skin contact threshold level 22. The skin response signals from the two sensors S3 and S4 that are not at all in contact with the skin 90 are still at the quiescent level 21. Based on the four skin response signals, the control circuit generates a skin contact signal. Depending on the application, the skin contact signal may only indicate a skin contact when all four skin response signals are above the skin contact threshold level 22 or also when only one, two or three skin response signals are above the threshold. For optimum safety, it is preferred to only indicate skin contact when all four skin response signals are above the threshold 22. In the situation shown in Figure 3a, with only two out of four skin response signals being above the skin contact threshold level 22, the skin contact signal may also indicate a partial contact.
Figure 4a shows another electronic scheme of the standard skin detector of figure 2a when in contact with skin 90. Now the application area 91 is almost completely covered by skin. Only a small area at the bottom left of the application area is not covered by skin 90. In addition to the sensors SI and S2, also the sensors S3 and S4 are partly covered by skin 90. Figure 4b shows exemplary signals as detected by the skin detector 10 of figure 4a. The only partly covered sensors S3 and S4 give a response that is slightly lower than the response of the fully covered sensor elements SI and S2. However, all four skin response signals are above the skin contact threshold 22 and the control circuit will thus generate a skin contact signal indicating a full skin contact. From a safety perspective this may not be a desirable result. For example, a laser beam passing through the uncovered application area 91 may still be harmful. Looking at figure 4b, adjusting the threshold level 22 might seem an obvious solution. Increasing the threshold level 22 would, however, reduce the sensitivity of the skin detector and may result in the skin sensor not being able to detect all genuine full skin contacts.
In Figure 11, a skin treatment device 100 according to the first aspect of the invention is shown which is in contact with skin 90. The skin treatment device 100 applies a treatment via an application area 130 of the skin treatment device 100 to a portion of skin 90 of a human or an animal. A skin detector 10 is provided close to and, in an embodiment, around the application area. Later in this section of the application, the skin treatment device 100 is discussed. In subsequent figures, embodiments of the skin detector 10 are discussed.
Figure 5a schematically shows an electronic scheme of a skin detector with sensor elements 56 according to the invention. The skin detector comprises a control circuit 11, a first set of sensor elements 56 1A, IB, a second set of sensor elements 56 2A, 2B, a third set of sensor elements 56 3A, 3B and a fourth set of sensor elements 56 4A, 4B. The sensor elements 56 are arranged around the application area 91. The sensor elements 56 of a single set are coupled via electrical connections 13 to a single input of the control circuit 11 for generating, for each set of sensor elements, a detection signal. The sensor elements 56 are used to detect whether each one of the sensor elements 56 has a predefined position with respect to skin, for example, whether they are in contact with the skin or whether they have a specific distance with respect to the skin. Unless mentioned otherwise, in the following part of this application, it is assumed that the predefined desired position is a position where the sensor element 56 is in contact with skin - but, in all embodiments one may read instead of "in contact with the skin" "at a predefined distance from the skin". The control circuit 11 comprises a decision circuit 12 which supplies an activating signal to the skin treatment device if the first detection signal indicates that all sensor elements 56 1A, IB have predefined desired positions with respect to a skin, the second detection signal indicates that all second sensor elements 56 2 A, 2B have predefined desired positions with respect to a skin, the third detection signal indicates that all third sensor elements 56 3A, 3B have predefined desired positions with respect to a skin, and the fourth detection signal indicates that all fourth sensor elements 56 4 A, 4B have predefined desired positions with respect to a skin. The activating signal may be used by the skin treatment device to activate its primary treatment operation.
As shown in Figure 5 a, at least one sensor element 56 2B of the second set of sensor elements is arranged in between two neighboring sensor elements 56 1 A, IB of the first set. By spatially separating the sensor elements 56 1 A, IB of the first set by at least one sensor element of another set, the skin detector becomes more accurate. This is further discussed in the context of Figure 7a and 7b. In the embodiment of Figure 5 a, sensor elements of other sets are also arranged in an interwoven configuration, which means that two sensor elements of one set are not directly adjacent to each other when the sensor elements are arranged in a sequence of sensor elements provided along the circumference of the application area 91.
The skin treatment device according to the invention may be summarized as follows: The skin treatment device comprises a skin detector and an application area 91 for applying the treatment to a portion of the skin. The skin detector comprises a control circuit 11 comprising a first input and a second input. The skin detector further comprises a fist set of a plurality of first sensor elements 56 1A, IB coupled to the first input and a second set of at least one second sensor element 56, 2A coupled to the second input. All sensor elements 56 are arranged around the application area 91, and in between two neighboring first sensor elements 56 1A, IB there is provided a second sensor element 56 2B. The control circuit 1 1 comprises a decision circuit 12 for supplying an activating signal for activating the skin treatment device if the first sensor elements 56 1A, IB and the at least one second sensor element 56, 2B all have predefined desired positions with respect to the skin.
As will be elucidated below with reference to figures 6a to 7b, the use of a plurality of sensor elements in one set of sensor elements and the use of an interwoven configuration helps to improve the accuracy. Figure 5b shows exemplary detection signals as detected by the skin detector of figure 5 a. Because there is no skin contact, all four skin response signals are at the quiescent level 21.
Figure 6a shows an electronic scheme of the skin detector of figure 5 a with sensor elements 56 in contact with skin 90. Like in Figure 3b, only part of the application area 91 is in contact with the skin 90. Sensor elements IB, 2B, 1A and 2A are in contact with the skin 90. Sensor elements 4B, 3B, 4A and 3A are not in contact with skin. Figure 6b shows exemplary detection signals as detected by the skin detector of Figure 6a. The sensor elements 1A and IB are coupled to a common input line 13, and, thus, to a single input of the control circuit 11. Both sensor elements contribute to the first skin response signal exceeding the skin contact threshold level 22. The same holds for the combined detection signal of sensor elements 2 A and 2B. The other sensor elements are not covered by skin 90 and the corresponding skin response signals are thus at the quiescent level 21. In this situation, the response signals are similar to the skin response signals of the similar situation elucidated with reference to figure 3b.
The advantages of the skin detector according to the invention become clear when considering the situation shown in Figure 7a, where a larger part of the application area 91, but not all of it, is covered by skin 90. Sensor elements IB, 2B, 1A and 2A are
completely covered, sensor elements 4B and 3A are partly covered and sensor elements 3B and 4 A are not covered at all. The skin contact shown in Figure 7a is similar to the skin contact shown in Figure 4a. The resulting detection signals in this situation with 8 sensor elements are however different when using the skin detector of Figure 7a instead of the detector of Figure 4a. Figure 7b shows exemplary detection signals as detected by the skin detector of Figure 7a. The sensor elements 1A and IB are coupled to a common input line 13, and thus to a single input of the control circuit 11 , and both contribute to the first detection signal exceeding the skin contact threshold level 22. The same holds for the combined detection signal of sensor elements 2A and 2B. The partly covered sensor elements 3 A and 4B provide a detection signal slightly below the skin response signals from the fully covered sensor elements 1A, IB, 2A and 2B. The uncovered sensor elements 3B and 4A do not provide any contribution to the detection signal at all. The combined result then is that the third and fourth combined detection signals are well below the skin contact threshold level 22, which makes it possible to distinguish this almost full skin contact from a full skin contact. Using only the four sensor elements of figures 4a and 4b, this would not be possible.
Figure 8 shows an electronic scheme of a skin detector with four sensor elements 56. Sensor elements 1A and IB are jointly coupled to a single input of the control circuit 11 by one input line 13 and so are the sensor elements 2 A and 2B. Compared to the skin detector of, e.g., Figure 2a, this one can provide a similar accuracy while requiring only two input lines 13 to be connected to the control circuit 11. Consequently, a simpler and cheaper control circuit 1 1 may be used without compromising accuracy.
Figure 9 shows an electronic scheme of a skin detector with twelve sensor elements 56. Here each set of sensor elements comprises three sensor elements 56 which are jointly coupled to a single input of the control circuit via one and the same input line (input lines and control circuit not shown). Like in the previous examples, those sensor elements 56 that are coupled to the same input lines are interspersed by other sensor elements 56 of another set.
Figure 10 schematically shows another embodiment of the skin detector of a skin treatment device. The skin treatment device comprises a rectangular application area 91. At the opposing shorter sides of the rectangular application area 91 there are provided, at a first side, a fourth sensor element 56, 4 of a fourth set and, at a second side, a sensor element 56, 3 of a third set of sensor elements. At the longer opposing sides of the rectangular application area 91 there are provided, at each side, one sensor element 56 2A, 2B of the second set of sensor elements and one sensor element 56 1A, IB of the first set of sensor elements. The sensor elements of the first set are coupled to the first input II of a control circuit 1 1 , the sensor elements of the second set are coupled to the second input 12 of the control circuit 1 1, the sensor elements of the third set are coupled to the third input 13 of the control circuit 11 and the sensor elements of the fourth set are coupled to the fourth input 14 of the control circuit 11. The control circuit 11 comprises the decision circuit 12.
Figure 11 schematically shows a skin treatment device 100 which comprises one of the skin detectors 10 as described above. The skin treatment device 100 is configured to be in a predefined desired position with respect to the skin 90 before being activated. In particular, an application area 130 of the skin treatment device needs to be in this predefined desired position. The treatment is provided to the skin 90 via the application area 130. In the example of Figure 11, the predefined position is a position in which the application area 130 is in contact with the skin 90. The skin treatment device 100 may e.g. be a shaving device or a skin rejuvenation device. The skin treatment device 100 comprises a light source 101 for producing a light beam 120 for treating the skin 90. Optical elements like lenses 102 and mirrors 103 may be provided for focusing the light beam 120 at the skin area to be treated. The light source 101 and the operation of the skin treatment device 110 is controlled by a device control circuit 110, which is coupled to the control circuit 11 of the skin detector 10. The control circuit 11 comprises a decision circuit 12 which is configured to decide whether the application area 130 is in contact with the skin 90. The light source 101 is operated in dependence on the activating signal from the decision circuit 12 of the skin detector 10. Optionally, both control circuits 1 1, 110 are integrated into a single control circuit for operating both the skin detector 10 and the skin treatment device 100 as a whole. Preferably, the skin treatment device 100 is operated such that the light beam 120 for treating the skin 90 is only provided if the skin detector detects full skin contact. It is to be noted that in the example of Figure 11 the skin treatment device uses light for obtaining a therapeutic effect. In other embodiments, other means may be used to provide therapy to a portion of the skin which occupies the predefined desired position with respect to the application area. For example, the skin treatment device may apply heat, or a gas, or, in another embodiment, mechanical forces to the top layer of the skin.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:
1. A skin treatment device (100) for treating a portion of a skin, the skin treatment device (100) comprising
an application area (91, 130) through which a treatment is provided to the portion of the skin,
- a skin detector (10) for detecting whether the application area (91, 130) has a predefined desired position with respect to the skin (90), the skin detector (10) comprising a) a first set of a plurality of first sensor elements (1A, IB, 1C), b) a second set comprising at least one second sensor element (2 A, 2B, 2C), c) a control circuit (11) comprising a first input (II) and a second input (12), wherein
the first sensor elements (1A, IB, 1C) and the at least one second sensor element (2A, 2B, 2C) are arranged around the application area (91, 130),
the first sensor elements (1A, IB, 1C) are coupled to the first input (II) to obtain a first detection signal and the at least one second sensor element (2A, 2B, 2C) is coupled to the second input (12) to obtain a second detection signal,
looking along a direction of an edge of the application area (91 , 130), the at least one second sensor element (2A, 2B, 2C) is arranged in between two neighboring first sensor elements (1A, IB, 1C),
the control circuit (11) comprises a decision circuit (12) for supplying an activating signal for activating the skin treatment device (100) if the first detection signal indicates that all first sensor elements (1A, IB, 1C) have predefined desired positions with respect to the skin (90) and the second detection signal indicates that the at least one second sensor element (2 A, 2B, 2C) all have predefined desired positions with respect to the skin (90).
2. A skin treatment device (100) as claimed in claim 1, wherein
the first sensor elements (1A, IB, 1C) are contact sensors for sensing contact with the skin (90),
the at least one second sensor element (2A, 2B, 2C) is a contact sensor for sensing contact with the skin (90),
the decision circuit (12) is configured for supplying the activating signal if the first detection signal indicates that all the first sensor elements (1A, IB, 1C) contact the skin (90) and the second detection signal indicates that the at least one second sensor element (2A, 2B, 2C) all contact the skin (90).
3. A skin treatment device (100) as claimed in claim 2, wherein
the first sensor elements (1 A, IB, 1C) and/or the at least one second sensor element (2A, 2B, 2C) comprise capacitive, inductive or resistive sensors comprising an electrically conductive area for cooperating with the skin (90) to determine whether the first sensor elements (1A, IB, 1C) and/or the at least one second sensor element (2A, 2B, 2C) are in contact with the skin, the conductive areas of the first sensor elements (1 A, IB, 1C) being electrically coupled to the first input (II) and/or the conductive areas of the at least one second sensor element (2A, 2B, 2C) being electrically coupled to the second input (12).
4. A skin treatment device (100) as claimed in claim 2, wherein the first sensor elements (1A, IB, 1C) comprise mechanical switches being arranged in series and/or the at least one second sensor element (2 A, 2B, 2C) comprises a mechanical switch.
5. A skin treatment device (100) as claimed in claim 1, wherein the decision circuit (12) is configured to supply the activating signal only if the first detection signal indicates that all first sensor elements (1A, IB, 1C) have predefined desired positions with respect to the skin (90) and the second detection signal indicates that the at least one second sensor element (2 A, 2B, 2C) all have predefined desired positions with respect to the skin (90).
6. A skin treatment device (100) according to claim 1, wherein the second set comprises a plurality of second sensor elements (2A, 2B, 2C) and all second sensor elements (2A, 2B, 2C) are coupled to the second input (12) to obtain the second detection signal.
7. A skin treatment device (100) according to claim 6, wherein the application area (91, 130) has multiple sides and each sensor element (56) of each set of sensor elements is arranged along a different side of the application area (91, 130).
8. A skin treatment device (100) according to claim 6, wherein, looking along the direction of the edge of the application area (91, 130), the first sensor elements (1A, IB, 1C) and the second sensor elements (2A, 2B, 2C) are arranged alternatingly around the application area (91, 130).
9. A skin treatment device (100) according to claim 6, wherein
the skin detector (10) further comprises
d) a third set comprising at least one third sensor element (3, 3 A, 3B, 3C), e) a fourth set comprising at least one fourth sensor element (4, 4A, 4B, 4C), - the at least one third sensor element (3, 3A, 3B, 3C) and the at least one fourth sensor element (4, 4A, 4B, 4C) are also arranged around the application area (91, 130),
the control circuit (11) further comprises a third input (13) and a fourth input (14), the at least one third sensor element (3, 3A, 3B, 3C) is coupled to the third input (13) to obtain a third detection signal and the at least one fourth sensor element (4, 4A, 4B, 4C) is coupled to the fourth input (14) to obtain a fourth detection signal,
the decision circuit (12) is configured to supply the activating signal if the first detection signal indicates that all first sensor elements (1A, IB, 1C) have predefined desired positions with respect to the skin (90), the second detection signal indicates that all second sensor elements (2A, 2B, 2C) have predefined desired positions with respect to the skin (90), the third detection signal indicates that the at least one third sensor element (3, 3A, 3B, 3C) all have predefined desired positions with respect to the skin (90), and the fourth detection signal indicates that the at least one fourth sensor element (4, 4A, 4B, 4C) all have predefined desired positions with respect to the skin (90).
10. A skin treatment device (100) according to claim 9, wherein, looking along the direction of the edge of the application area (91, 130), a sequence of sensor elements is formed by one of the first sensor elements (1 A), one of the second sensor elements (2A), the at least one third sensor element (3), another one of the first sensor elements (IB), another one of the second sensor elements (2B) and the at least one fourth sensor element (4).
11. A skin treatment device (100) according to claim 9, wherein
the third set comprises a plurality of third sensor elements (3, 3A, 3B, 3C) and all third sensor elements (3, 3A, 3B, 3C) are coupled to the third input (13) to obtain the third detection signal, the fourth set comprises a plurality of fourth sensor elements (4, 4A, 4B, 4C) and all fourth sensor elements (4, 4A, 4B, 4C) are coupled to the fourth input (14) to obtain the fourth detection signal.
12. A skin treatment device (100) according to claim 1 1, wherein, looking along the direction of the edge of the application area (91, 130), a sequence of sensor elements (56) comprises at least one sub-sequence, the at least one sub-sequence comprising one first sensor element (1A, IB, 1C), one second sensor element (2A, 2B, 2C), one third sensor element (3, 3A, 3B, 3C) and one fourth sensor element (4, 4A, 4B, 4C).
13. A skin treatment device (100) as claimed in 1, wherein the skin treatment device (100) is activated when the decision circuit (12) generates the activating signal.
PCT/IB2013/058277 2012-10-31 2013-09-04 Skin treatment device having a skin detector WO2014068414A1 (en)

Applications Claiming Priority (2)

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US201261720467P 2012-10-31 2012-10-31
US61/720,467 2012-10-31

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US20070198004A1 (en) * 2002-05-23 2007-08-23 Palomar Medical Technologies, Inc. Photocosmetic device
EP1923014A1 (en) * 2006-11-16 2008-05-21 Matsushita Electric Works, Ltd. Optical hair removing device
US20090043294A1 (en) 2003-02-25 2009-02-12 Spectragenics, Inc. Capacitive Sensing Method and Device for Detecting Skin
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JP2010148685A (en) * 2008-12-25 2010-07-08 Moritex Corp Skin observation apparatus

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070198004A1 (en) * 2002-05-23 2007-08-23 Palomar Medical Technologies, Inc. Photocosmetic device
US20090043294A1 (en) 2003-02-25 2009-02-12 Spectragenics, Inc. Capacitive Sensing Method and Device for Detecting Skin
EP1923014A1 (en) * 2006-11-16 2008-05-21 Matsushita Electric Works, Ltd. Optical hair removing device
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