massager

Abstract

Massage device with a handpiece (1), a massage head (4) connected to the handpiece (1) so as to be rotatable about an axis (6), a motor (8) driving a rotary movement of the massage head (4), a power supply for supplying the motor (8) with a PWM-modulated, adjustable operating voltage and a load measuring device which is coupled to the power supply for detecting the load of the motor (8) in order to vary the supply voltage in the same direction as the detected load, characterized in that the power supply is designed to vary the pulse voltage of the PWM-modulated operating voltage with the detected load.

Description

[0001] The present invention relates to a massage device comprising a handpiece, a massage head connected to the handpiece for rotation about an axis, and a motor driving the rotation of the massage head. Such a massage device is known, for example, from EP 1 009 354 B1.

[0002] This well-known massage device is used for treatments within the framework of matrix rhythm therapy, which, in simple terms, aims to return the vibrational behavior of muscle and connective tissue, which has become out of tune due to stress, pollutants, and the like, to a physiological frequency of approximately 10 Hz. One approach to achieving this goal is to initially operate the massage head at a frequency close to the out-of-tune frequency of the tissue being treated in order to synchronize it with the massage head, and then gradually detune both together toward the physiological frequency.

[0003] Massage devices with a frequency display, which even an inexperienced user can use to see whether they are working at a desired frequency, are known per se, e.g. from EP 1 040 812 B1. Here, a frequency display is integrated into a power supply unit that is separate from the handpiece of the massage device and connected to it via a power cable. This makes it difficult to note and take the frequency into account during treatment, as the person performing the treatment has to look away from the body surface being treated and towards the power supply unit. Continuous consideration of the frequency during treatment is therefore hardly possible. However, this is of essential importance, particularly in the context of matrix rhythm therapy, and until now had to be provided by the therapist using haptic and acoustic feedback.

[0004] One problem with controlling the movement frequency of the massage head is that when a DC motor is used to drive the massage head, the movement frequency depends heavily on the motor load. This results from the inertia and elasticity of the body tissue moved by the massage head during treatment. The harder the massage head is pressed, the deeper its effect reaches, and the greater the driven mass and the resulting torque acting on the massage head. Precisely controlling the frequency under these conditions requires a high degree of practice and concentration on the part of the practitioner.

[0005] While it would be possible in principle to use an AC motor instead of a DC motor, whose speed is closely coupled to the frequency of an AC supply voltage, this would require the practitioner to constantly have one hand on a frequency controller to adjust the speed, which is extremely cumbersome during treatment.

[0006] EP 2 903 582 B1 discloses a massage device according to the preamble of claim 1.

[0007] The object of the present invention is to create a massage device which allows the movement frequency of the massage head to be varied depending on the load, but at the same time makes it easier for the practitioner to maintain a desired frequency.

[0008] The object is achieved by a massage device having the features of claim 1. By thus counteracting an increased load with an increased motor power, the dependence of the speed on the load can be reduced, and maintaining a desired speed is made easier.

[0009] A permanent magnet DC motor is particularly suitable as a motor.

[0010] The variation in operating voltage could be so significant that an increase in load leads to an increase in speed. A smaller increase in voltage is preferred, as it more closely corresponds to the practitioner's intuition. This is calculated so that an increase in load still leads to a slowing of the motor, but to a lesser extent than with a conventional, non-load-controlled power supply. This not only reduces the device's sensitivity to unavoidable load fluctuations, but also increases the range within which the pressure exerted by the massage head on the patient's body surface can be varied without the motor becoming blocked.

[0011] A simple way to determine the motor load is to measure a current flowing through the motor; this current increases with the load and reaches a maximum when the motor stalls.

[0012] The frequency of the PWM modulation should not fall below 20 Hz, preferably 50 Hz, so that the individual pulses do not become noticeable as irregularities in the movement of the massage head. On the other hand, the frequency should not exceed 500 Hz, preferably 200 Hz, to avoid becoming noticeable as an annoying high-frequency noise.

[0013] If the duty cycle of the PWM-modulated operating voltage is limited to below 100%, preferably below 90%, even if the load is large enough to block the motor, a shaking of the massage head may remain noticeable, indicating that the motor is operating.

[0014] Preferably, the power supply is configured to never reach a 100% duty cycle; in particular, a maximum duty cycle of 80-90% is preferred. This way, the pauses between voltage pulses are long enough that, when the motor is stalled, a vibration is felt, allowing the user to immediately detect whether the motor is stalled or switched off. On the other hand, the motor's achievable power is only barely noticeably reduced compared to a 100% duty cycle.

[0015] Preferably, a controller is provided that allows the practitioner to arbitrarily adjust the duty cycle of the PWM-modulated operating voltage. This allows a higher power level to be selected for the treatment of deep tissue, e.g., on extremities, than for facial muscles, which form only a thin layer above the underlying bone.

[0016] A frequency indicator for showing a frequency of the rotary movement can be provided on the handpiece to show the practitioner at any time whether he is working in the correct frequency range and, preferably, also in which direction he must change the load in order to achieve the desired frequency range.

[0017] To ensure that the frequency display is always clearly visible, regardless of its orientation relative to the practitioner's eye, an alphanumeric display is less appropriate. A non-graphical coding of the frequency information is preferred, particularly through a variable color, brightness, or flashing frequency.

[0018] The frequency display should be able to show at least three different states, each corresponding to a correct frequency, a frequency that is too low, and a frequency that is too high. These three states are generally sufficient to allow the practitioner to determine whether they are working at the correct frequency and how they should correct it if necessary. In the simplest case, however, two different states may suffice, each corresponding to the correct or an incorrect frequency; the practitioner can generally make the decision whether an incorrect frequency is too high or too low without difficulty.

[0019] When used in matrix rhythm therapy, a frequency interval corresponding to the correct frequency should contain a frequency of 10 Hz.

[0020] In such a context, it is also conceivable to make the boundaries between correct, too high and / or too low frequency variable during the course of a treatment; thus, after a practitioner has determined the actual frequency of the tissue based on its influence on the movement of the massage head and has adjusted the massage head to the actual frequency, he or she can specify a ramp as the correct frequency, which, starting from the actual frequency, approaches the target frequency during the course of the treatment.

[0021] In a massage head known per se and used in matrix rhythm therapy, the circumferentially variable property of the treatment surface is its radius, which allows the practitioner to vary the amplitude of a movement transmitted from the treatment head to the body surface by rotating the massage device around the axis.

[0022] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. They show: Fig. 1 a view of a handpiece with a massage head mounted thereon in a view from the radial direction to the axis of the massage head; Fig. 2 a section through the handpiece and the massage head in axial direction; Fig. 3 a section in radial direction along the plane III-III Fig. 2; Fig. 4 an exemplary relationship between the scanning frequency of the light sources and the oscillation frequency of the massage head; Fig. 5 shows an axial section through part of a handpiece according to a second embodiment of the invention, Fig. 6 a cross section through the handpiece along the plane VI-VI_from Fig. 5; Fig. 7 is a block diagram of the massager; Fig. 8 exemplary relationships between load and operating voltage.

[0023] The Fig. The handpiece 1 shown in Figure 1 has an elongated housing with a cylindrical section 2 and a truncated cone-shaped tapered section 3 adjoining the cylindrical section 2, from whose small base a shaft 5 carrying a massage head 4 emerges. The truncated cone-shaped section 3 is slanted, i.e. its small base is offset radially from the large base to an axis 6 of the shaft 5 in order to accommodate an electric motor 8 (see Figure 1) in the cylindrical section 2 concentrically to its longitudinal axis 7. Fig. 2) and to be able to accommodate an eccentric gear 9 in the frustoconical section 3, which converts the rotation of the electric motor 8 into an oscillating pivoting movement of a reduced frequency compared to the rotation of the motor 8.

[0024] At an end of the housing facing the massage head 4, here approximately in a transition area between the cylindrical section 2 and the frustoconical section 3, a translucent ring 10 is provided, the surface of which forms a band of light-emitting points on the surface of the handpiece 1, encircling the axis 6 or 7. The ring 10 can, for example, be a molded body made of translucent, preferably diffusely scattering plastic, which is preferably contoured on its inner side to refract passing light and scatter it in different directions.

[0025] In this embodiment, the housing, including the ring 10, is preferably a continuous tubular assembly into which the motor 8, the circuit boards, the planetary gear, etc. are inserted in the axial direction.

[0026] The massage head 4 is mounted eccentrically on the shaft 5. It preferably has the shape known from EP 1 009 354 B1, with a treatment surface 11 extending in an arc around the axis 6 in the form of one or two mirror-image Fibonacci spirals. Due to the spiral shape of the treatment surface 11, when the practitioner rotates the handpiece 1 about its axis 7, the radius of that section of the treatment surface 11 that touches a body surface to be treated changes, and thus the amplitude of the oscillation of that section, without the practitioner having to access the massage device's controls.

[0027] A DC motor is particularly suitable as motor 8, as its speed is highly variable depending on the applied operating voltage and load. This allows the practitioner to influence the oscillation frequency without having to operate a controller on the massage device, simply by changing the pressure exerted on the treated body surface or by changing the radius between the part of the treatment surface 11 in contact with the body surface and the axis 6. For example, a permanent magnet DC motor with carbon brushes can be considered.

[0028] The more pressure the massage head 4 exerts on the body surface, the deeper its effect reaches, and consequently the greater the mass of body tissue that follows the oscillating movement of the massage head 4. Therefore, when the DC motor is supplied with a constant operating voltage, the oscillation frequency decreases sharply with increasing pressure and increases with decreasing pressure. Increasing the radius leads to greater acceleration of the tissue moving back and forth in frictional contact with the treatment surface, and since the effect of the movement reaches deeper into the tissue, the greater its amplitude, the greater the mass of the moving tissue. Therefore, changing the radius also influences the oscillation frequency.

[0029] A control loop can be provided that regulates the operating voltage of motor 8 inversely to the motor load in order to reduce the dependence of the oscillation frequency on the motor load compared to an uncontrolled motor, but not to completely eliminate it. Embodiments of such a control loop will be described in more detail later.

[0030] In the presentation of the Fig. 2, the housing of the massage device is shown cut away on a side facing the massage head in order to show the motor 8 and the eccentric gear 9. The eccentric gear 9 can be of any known design; here it comprises a reduction stage 12, e.g., a planetary gear, whose sun gear 13 is seated on a shaft 14 of the motor 8 concentric with the longitudinal axis 7, and a pin 16 mounted eccentrically to the axis 7 at an output, e.g., a planet carrier 15 of the planetary gear. The pin 16 engages in a radial slot of a fork 17 mounted on the shaft 5, thus converting the rotary movement of the motor 8 into an oscillation of the massage head 4.

[0031] One in Fig. 3, the circuit board 18 shown in plan view is arranged in the housing between the motor 8 and the eccentric gear 9. The shaft 14 of the motor 8 extends through a central opening in the circuit board 18. Light sources 19, in particular LEDs, are distributed along the circumference of the circuit board. The circuit board 18 also carries a speed sensor 20. The speed sensor 20 can be of a type known per se, e.g., an inductive sensor or a Hall sensor directly exposed to a rotating magnetic field of the motor 8; however, other sensor types are also conceivable, such as a capacitive sensor that responds to the approach of a planetary gear shaft 21 of the planet carrier 15 or an extension of the pin 16 that projects toward the circuit board 18.

[0032] It is also conceivable to provide a speed sensor which does not detect a physical movement, but merely spectrally analyses the current flow through the motor 8 and identifies a frequency with which this varies as the rotational frequency of the motor 8.

[0033] An evaluation circuit, also located on the circuit board 18, compares the measurement result of the speed sensor 20 with a target value corresponding to an oscillation frequency of the massage head 4 of 10 Hz and, based on the comparison result, controls the light sources 19 to form a frequency display 24.

[0034] The light sources 19 are staggered closely enough around the circumference of the circuit board 18 that one or more are always visible to the practitioner through the ring 10, regardless of how the massage device is rotated about its longitudinal axis 7.

[0035] The type of control can vary. There can be three different control states, e.g., continuously off, flashing, and continuously on, which can be arbitrarily assigned to the possible comparison results: oscillation frequency too low, oscillation frequency in sufficient agreement with the target value, and oscillation frequency too high. Since the practitioner knows which operating state of the light sources 19 corresponds to which comparison result, they immediately know whether they need to increase the treatment pressure or increase the radius of the effective part of the treatment area 11 to reduce the frequency, whether they can maintain the current treatment conditions, or whether they need to reduce the pressure or radius to achieve a higher oscillation frequency.

[0036] A further simplified version provides only two different states: continuously on at the correct frequency, and flashing at frequencies that are too high or too low. As long as the frequency range assessed as correct is not too narrow, the practitioner has no problem determining whether an incorrect frequency is too high or too low; the "continuously off" state can then indicate that the device is switched off.

[0037] Particularly when LEDs are used as light sources 19, the comparison result can also be signaled using LEDs of different colors. For example, it is possible to mount LEDs in two of the three primary colors red, green, and blue in pairs around the circumference of the circuit board 18 and to operate the LEDs in the first of the two colors when the oscillation frequency is below the target value, to operate the LEDs in the second color when the oscillation frequency is above the target value, and to operate both simultaneously when the frequency is within the target range. This way, operation at the correct frequency can be intuitively recognized, even by a user who does not know which color is assigned to which frequency range, because it is brighter than in the other two operating states. For example, the first color can be blue, the second yellow; in this case, operation at the correct oscillation frequency can be recognized by the green glow of the ring 11.

[0038] According to a further development, the LEDs are operated intermittently with a duty cycle that is as in Fig. 4, the closer the measured frequency is to the target frequency, the greater the intensity. The duty cycle of the LEDs of the first color begins to gradually increase from zero or a value significantly less than 1 at a frequency f0, which is significantly lower than the target frequency fs and can be equal to zero, while the LEDs of the second color remain off. The ring 10 shines in the first color with a brightness that increases the closer the measured frequency gets to the target frequency fs. Shortly before the target frequency fs is reached, at a frequency fs-ε, the LEDs of the second color are also switched on, and the color changes. If the frequency rises above fs+ε, the LEDs of the first color quickly lose intensity, and the color changes again. The duty cycle of the LEDs of the second color slowly decreases as the frequency continues to rise.Based on the color and brightness of the ring 11, the practitioner can not only determine whether the oscillation frequency of the massage head is too high or too low, but also how far it deviates from the target value.

[0039] If the light sources 19 are sufficiently closely spaced around the circumference of the circuit board 18, there is another way to visualize the agreement or deviation of the measured frequency from the target frequency. This can be achieved by switching adjacent light sources on and off with a slight time offset, thus creating the impression of a light circulating around the circumference. Here, the direction of rotation and speed can each encode the sign and the magnitude of the deviation, i.e., a stationary light indicates the correct frequency, and the faster the light rotates clockwise or counterclockwise, the greater the measured frequency deviates upwards or downwards from the target frequency.

[0040] In this embodiment, LEDs in two different colors can also be used to illuminate the ring 10 in three different colors, as described above, depending on whether the measured frequency is too high, correct, or too low.

[0041] Instead of a continuous ring 10, several translucent windows can of course also be distributed in the housing along the circumference of the circuit board 18. Preferably, the windows are each arranged radially beyond one of the light sources 19, as seen from the longitudinal axis 7.

[0042] The measured oscillation frequency can also be used as an input variable for a control circuit 22, which controls the operating voltage of the electric motor 8. The control circuit 22 is designed to reduce the operating voltage if the target frequency is exceeded or to increase it if it is undershot, thus reducing the dependence of the oscillation frequency on the load, but by no means eliminating it entirely. Because the oscillation frequency fluctuates less depending on the pressure and the radius of the effective part of the treatment area 11, it is easier for the practitioner to maintain a constant desired treatment frequency.

[0043] Fig. Figure 1 shows a control element 23, in this case a rotary knob, on the end face of the handpiece opposite the massage head. This allows the operating voltage of the electric motor 8 to be influenced in order to vary the power of the electric motor 8, at which the target frequency of 10 Hz is set. Thus, a higher operating voltage can be set for the treatment of deep tissue, such as on a thigh, than for thin muscle layers, such as on a patient's head. The control of the operating voltage via the control element 23 can be combined with that via the control circuit 22.

[0044] Fig. 5 and Fig. 6 show a handpiece 1 of a massage device according to a second embodiment of the invention in a partial longitudinal section and a cross section along the plane VI-VI from Fig. 5. The external shape of the housing is essentially the same as in the first embodiment, with a - in Fig. 5 only partially shown - section 2 of constant cross-section and a conical section 3 tapered towards the massage head 4. The housing here comprises two groove-shaped shells 25, 26 elongated in the direction of a longitudinal axis 7 of the motor 8, each of which forms a part of each section 2 or 3. A dashed line 27 in Fig. 5 illustrates the course of longitudinal edges of the switches 25, 26 which are connected to one another. This housing construction allows the motor 8, the components and circuit boards driven by it to be first mounted in the shell 25 and, after completion of this assembly, the housing to be closed by placing the shell 26 on top.

[0045] At the rear end of the housing (not shown), the shells 25, 26 can be pivotally connected; then, to close the housing, a sleeve 28 is sufficient, which is placed on the front tips of the shells 25, 26 surrounding the shaft 5.

[0046] The components to be mounted in the shell 25 include a carrier body 29, which fills a large part of the conical section 3 and in its Fig. 5 lower area forms or encloses a bearing 30 of the shaft 5. On an upper side of the carrier body, a mounting surface for a printed circuit board 31 is formed. The printed circuit board 31 runs in the section of the Fig. 5 parallel to shell 26.

[0047] The circuit board 31 is equipped with operating and display elements, e.g. one or more switches 32 and light sources 19, typically LEDs. The at least one switch 32 serves to switch the motor on or off; alternatively, a switch 32 can also be used - instead of the operating element 23 of the Fig. 2 - serve to gradually adjust the power of the motor 8. The switches 32 are preferably arranged opposite openings in the shell 26 so that they can be mechanically actuated by finger pressure.

[0048] The at least one light source 19 is arranged opposite a weak point of the shell 26, so that light emitted by it becomes visible through the weak point, although the shell 26 is opaque elsewhere.

[0049] Fig. Figure 6 illustrates the assembly of the massage device: the shell 25 has ribs 34 that project inward in a plane parallel to the section plane and support the motor 8. Fingers 35, which extend from below into the shell 26 as an extension of the ribs 34, lock the motor 8 into the shell 25 and support a circuit board 36 extending above the motor.

[0050] Fig. Figure 7 schematically shows the circuit layout of the massager. A transformer-rectifier unit 37 is connected to the lighting network and converts its AC voltage into a DC voltage Vcc, the level of which is controlled by the voltage applied to a signal input 38.

[0051] The transformer-rectifier unit 37 may comprise a transformer not shown in the figures outside the handpiece 1, which is connected to the handpiece 1 via a supply cable 43 (see Fig. 1, Fig. 2) and a detachable plug connection on the housing of the handpiece 1 and converts the mains voltage into a safe low voltage for transmission on the supply cable 43.

[0052] One in Fig. According to the exemplary embodiment outlined in Figure 7, the transformer-rectifier unit 37 within the handpiece 1 comprises a rectifier 44 for generating a direct voltage of 10-20V, an accumulator 45 fed by the rectifier 44, which enables operation of the handpiece 1 without a connected supply cable 43, and a direct-voltage converter 33, the output voltage of which is controlled via the signal input 38.

[0053] The DC voltage is applied to a PWM modulator 39, which generates a PWM-modulated operating voltage V PWM for the motor 8. The duty cycle of the operating voltage V PWM can be adjusted on the control element 23 or one of the switches 32 between a minimum value, which is preferably dimensioned to cause the massage head 4 to oscillate at a frequency of approximately 10 Hz in the load-free state, without contact with the patient's body, and a maximum value which should not exceed 90%.

[0054] The motor 8 is connected in series with a measuring resistor 40, so that at a circuit node 41 between the motor 8 and the measuring resistor 40 a synchronous to the operating voltage V PWM pulsed measuring voltage proportional to the current I through the motor 8 is present. The pulse voltage V M , ie the voltage value of the measuring voltage reached during a PWM pulse depends on the duty cycle of the operating voltage VPWM essentially independent. It represents a measure of the motor load, ie, the power applied to move the patient's tissue, and is applied to the signal input 38 of the transformer-rectifier unit 37 to control its output voltage Vcc.

[0055] To determine the pulse voltage V M In order to have a constant voltage level available at the signal input 38, a sampling circuit 42 with a diode arranged in series and a capacitor between the signal input 37 and ground can be provided between the circuit node 41 and the signal input 37.

[0056] If the output voltage Vcc remains constant and the measuring voltage V Mincreases, this indicates an increase in the motor load, and to counteract a slowdown of the motor 8, the transformer-rectifier unit 37 reacts by increasing Vcc. This increase leads to a proportional increase in the measuring voltage V M . To prevent this increase from causing an increase in Vcc, the transformer-rectifier unit 37 also detects its own output voltage Vcc and controls the latter according to the ratio I / Vcc or, equivalently, V M / Vcc.

[0057] The relationship between Vcc and I / Vcc can be described as Fig.8, increase linearly until a maximum output voltage of unit 37 is reached; this can be approximated by a step function. Non-linear relationships are also possible; for example, it may be useful to initially provide a relatively steep increase in the output voltage Vcc with the load at low load in order to almost completely suppress a load-related speed decrease of motor 8, but at high load, a weaker increase that lets the user feel when the motor is approaching its performance limit.

[0058] A sensor 46 is arranged on a movable part of the motor 8 to detect its rotation. An evaluation circuit 47 determines a rotation frequency based on the signals from the sensor 46 and controls at least one light source 19 according to this frequency.

[0059] The at least one light source 19 can, as described above, indicate the frequency of the massage head by flashing in different patterns.

[0060] If two light sources 19 are present which are clearly distinguishable from one another for a practitioner, for example by a marking being applied adjacent to them on the shell 26, or by them being spaced apart from one another in the longitudinal direction of the handpiece 1, a frequency which is too low can also be indicated by only a first of the light sources 19 lighting up continuously, a frequency which is too high can be indicated by only a second of the light sources 19 lighting up continuously, and a correct frequency can be indicated by both lighting up simultaneously. List of reference symbols 1 handpiece 2 cylindrical section 3 truncated conical section 4 massage heads 5 Wave 6 axis 7 Longitudinal axis 8 Electric motor 9 Eccentric gear 10 rings 11 treatment area 12 reduction stages 13 Sun gear 14 Wave 15 planet carriers 16 cones 17 fork 18 circuit boards 19 Light source 20 speed sensor 21 Planetary gear shaft 22 Control loop 23 Control element 24 Frequency display 25 bowls 26 bowl 27 Line 28 sleeve 29 carrier bodies 30 warehouses 31 circuit board 32 switches 33 DC-DC converters 34 rib 35 fingers 36 circuit board 37 Transformer-rectifier unit 38 Signal input 39 PWM modulator 40 measuring resistor 41 circuit nodes 42 sampling circuit 43 supply cables 44 rectifiers 45 accumulator 46 Sensor 47 Evaluation circuit

Claims

[1] Massage device with a handpiece (1), a massage head (4) connected to the handpiece (1) so as to be rotatable about an axis (6), a motor (8) driving a rotary movement of the massage head (4), a power supply for supplying the motor (8) with a PWM-modulated adjustable operating voltage and a load measuring device which is coupled to the power supply for detecting the load of the motor (8) in order to vary the supply voltage in the same direction as the detected load, characterized by that the power supply is configured to vary the pulse voltage of the PWM-modulated operating voltage with the detected load. [2] Massage device according to claim 1, characterized by that the variation of the supply voltage with the load is such that the speed of the motor (8) decreases with increasing load. [3] Massage device according to claim 1 or 2, characterized by that the load measuring device is designed to measure a current flow through the motor. [4] Massage device according to claim 1, 2 or 3, characterized by that the modulation frequency of the PWM-modulated operating voltage is at least 20 Hz, preferably at least 50 Hz and / or at most 500 Hz, preferably at most 200 Hz. [5] Massage device according to one of claims 1 to 4, characterized by that the power supply is configured to adjust the duty cycle of the PWM-modulated supply voltage independently of the sensed load. [6] Massage device according to one of claims 1 to 5, characterized by that the duty cycle of the PWM-modulated supply voltage is limited to less than 100%, preferably less than 90%. [7] Massage device according to one of claims 1 to 6, characterized by a controller that can be used to adjust the duty cycle of the PWM-modulated supply voltage. [8] Massage device according to one of the preceding claims, characterized bythat a frequency display is provided for displaying a frequency of the rotary movement on the handpiece (1). [9] Massage device according to claim 8, characterized by that the frequency display is encoded by a variable color, brightness or flashing frequency. [10] Massage device according to claim 8 or 9, characterized by that the frequency display supports three different states, each corresponding to a correct frequency, a frequency that is too low and a frequency that is too high, or two different states, each corresponding to a correct frequency and an incorrect frequency. [11] Massage device according to claim 10, characterized by that a frequency interval corresponding to the correct frequency contains a frequency of 10 Hz. [12] Massage device according to one of the preceding claims, characterized by that the frequency display is provided adjacent to an end of the handpiece (1) facing the massage head (4). [13] Massage device according to one of the preceding claims, characterized by that the massage head (4) has a treatment surface (11) extending around the axis (6) with a radius that is variable along its circumference.

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