WO2015156715A1

WO2015156715A1 - Tattoo machine power control device and a method of controlling a tattoo machine

Info

Publication number: WO2015156715A1
Application number: PCT/SE2014/050439
Authority: WO
Inventors: Christian Johansson
Original assignee: Ink Machines Sweden Ab
Priority date: 2014-04-10
Filing date: 2014-04-10
Publication date: 2015-10-15

Abstract

A tattoo machine power control device (14) is arranged for controlling the power applied to a tattoo machine(12). The tattoo machine power control device (14) comprises an electrical interface (44) adapted for detachable connection of the tattoo machine power control device (14) to a tattoo machine (12).The tattoo machine power control device (14) is adapted to receive a signal (S2) indicating the present rpm of the tattoo machine (12) and to adjust the power applied to the tattoo machine (12) based on a desired rpm.

Description

TATTOO MACHINE POWER CONTROL DEVICE AND A METHOD OF CONTROLLING A TATTOO MACHINE

Field of the invention

The present invention relates to a tattoo machine power control device and a method of controlling a tattoo machine.

Background of the invention

Typically, a tattoo system comprises a controller unit, one or several hand-held tattoo machines connected to the controller unit, and a foot pedal connected to the controller unit for starting and stopping the tattoo

machine(s). The controller unit typically has a user interface for setting and displaying the drive voltage supplied to the tattoo machine(s). An example of a control unit can be found in US 7,969,715.

A tattoo artist wants to find an optimum voltage to be supplied to the tattoo machine when applying ink to the skin of a human being or an animal. However, since the toughness of the skin varies, also for the same individual, and also other parameters may vary, it is often difficult to find such an optimum voltage that provides efficient application of ink to the skin without unduly damaging the skin.

Summary of the invention

It is an object of the present invention to solve, or at least mitigate, parts or all of the above mentioned problems.

This object is achieved by means of a tattoo machine power control device for applying power to a tattoo machine, wherein the tattoo machine power control device comprises an electrical interface adapted for detachable connection of the tattoo machine power control device to a tattoo machine, wherein the tattoo machine power control device is adapted to receive a signal indicating the present rpm of the tattoo machine and to adjust the power applied to the tattoo machine based on a desired rpm.

An advantage of this tattoo machine power control device is that it provides for better control of the tattooing process. The tattoo artist may select a desired rpm, and the power control device adjusts the power applied to the tattoo machine to obtain an rpm that is relatively close to the desired rpm also when the conditions of the tattooing process varies, due to, for example, variations in the toughness of the skin, the number of needles attached to the tatoo machine, the depth at which the tattoo artist applies the ink into the skin, and the speed at which the tattoo artist moves the needles over the skin surface. By the present tattoo machine power control device the rpm and the torque are separated, and the rpm is kept relatively constant at that rpm which is desired, while the torque is adjusted to obtain that desired rpm. This means that the tattoo artist can work at that rpm which is considered best for the tattooing process in question, and the power is adjusted to maintain that rpm, meaning that the torque varies.

Furthermore, by means of the present tattoo machine power control device it becomes possible to perform the tattooing process at a relatively low rpm and still at a high torque. This makes it possible to effectively bring the ink into the skin with a low number of skin penetrations. Thereby, the trauma to the skin is reduced compared to traditional tattooing process. The reduced trauma to the skin is an advantage, because it makes the skin healing process quicker.

Still further, since the tattoo machine power control device is adapted for detachable connection to the tattoo machine it is also possible for use in retrofit applications, meaning that the tattoo machine power control device can be connected to an old tattoo machine and thereby provide to that old tattoo machine the new functionality of obtaining control of the rpm.

A yet further advantage of the present tattoo machine power control device is that it makes it possible to design tattoo machines with smaller, and thereby light weight, motors, because the tattoo machine power control device provides for controlling the power and for increasing the torque by, e.g., increasing the voltage when needed.

According to one embodiment the tattoo machine power control device is adapted for receiving a current signal indicating the electric current drawn by a tattoo machine motor of a tattoo machine, and for using said current signal as an indirect indication of the present rpm of the tattoo machine. An advantage of this embodiment is that the current signal is often easily available without requiring any extra equipment. Hence, measuring the electric current is cheap and adds little or no complexity to the power control device. The electric current drawn by the motor is also a relevant and quick indication of the actual present rpm of the motor.

According to one embodiment the tattoo machine power control device comprises a tattoo machine controller unit which is adapted for being connected via a connecting wire to a tattoo machine in a detachable manner, wherein the controller unit comprises at least one processor for adjusting the power supplied from the controller unit to the tattoo machine based on a desired rpm. An advantage of this embodiment is that the tatto machine can be supplied with power from the tattoo machine controller unit via the wire, and that the tattoo machine controller unit also controls the rpm of the tatto machine. Thereby, an old tattoo machine can be given the new functionality of controlled rpm by detachably connecting it, via the wire that is anyway supplying the power, to the tattoo machine controller unit. Hence, no upgrade of the tattoo machine in itself is needed, since the processor adapted for the rpm adjustment is arranged in the tattoo machine controller unit which is detachably connected to the tattoo machine via the wire.

According to one embodiment the tattoo machine power control device comprises a tattoo machine power supply which is adapted for detachable connection to a tattoo machine and which comprises at least one battery adapted for supplying power to the tattoo machine and at least one processor for controlling the power supplied from the at least one battery to the tattoo machine based on a desired rpm. An advantage of this embodiment is that the tattoo machine can be moved more freely by the tattoo artist, since it is not necessary to have a cable connection. The tattoo machine power control device is detachably connected to the tattoo machine and comprises both the at least one battery supplying the power to the tattoo machine and also the processor that adjusts the power supplied from the battery to the tattoo machine to obtain the control of the rpm. This provides for very quick control of the power applied to the tattoo machine, and thereby a quick response to any changes in the rpm, since the at least one battery and the processor are both located in the same device, which is connectable to the tattoo machine. According to a preferred embodiment, the tattoo machine power control device may have the form of a battery pack comprising at least one battery and additionally the processer adapted for controlling the rpm. This embodiment provides for a particularly efficient and quick upgrade of an existing tattoo machine, without any rebuild thereof, by providing the functionality of rpm adjustment.

According to one embodiment the tattoo machine power supply is adapted for wireless communication with a tattoo machine controller unit and for receiving from the tattoo machine controller unit a signal indicating the desired rpm. An advantage of this embodiment is that the tattoo machine power supply can be made relatively simple and with low weight, for example in the form of a battery pack which is detachably connectable to a tattoo machine, while all kinds of settings can be made on the tattoo machine controller unit, which is typically a stationary unit, and then be transmitted to the tattoo machine power supply. This makes the tattoo machine power supply have low weight, meaning that the tattoo machine with a tattoo machine power supply detachably connected thereto gets a low weight and becomes easy to handle for a tattoo artist.

According to one embodiment the processor adapted for controlling the power applied to a tattoo machine is adapted for being directly connectable to the tattoo machine. An advantage of this embodiment is that the control becomes much quicker compared to the case of the processor being indirectly connected to the tattoo machine via, for example, a wireless communication.

According to one embodiment the tattoo machine power control device is adapted to control the voltage applied to the tattoo machine. An advantage of this embodiment is that control of the voltage provides for efficient and simple adjustment of the rpm to the desired rpm.

According to one embodiment the tattoo machine power control device is adapted for being set to at least a first compensation setting and a second compensation setting, wherein the power control device is adapted to react more aggresively to deviations in the rpm when in the first compensation setting (HIGH) compared to when in the second compensation setting (LOW). An advantage of this embodiment is that the tattoo artist can select, according to personal preferences, how quickly the rpm is to be returned to the rpm set- point in a situation, for example, when the friction increases because the tattoo artist gradually forces the needles attached to the tattoo machine deeper into the skin.

According to a further aspect of the present invention there is provided a tattoo system which comprises a tattoo machine power control device according to any one of the above embodiments, and a tattoo machine comprising a rotary electric motor. An advantage of this tattoo system is that it provides for very good possibilities of controlling the rpm, and still can include a relatively cheap and simple tattoo machine, since the necessary intelligence is included in the tattoo machine power control device which is detachably connectable to the tattoo machine.

According to a still further aspect of the present invention there is provided a method of controlling the power applied to a tattoo machine. This method comprises:

detachably connecting a tattoo machine power control device to the tattoo machine,

applying power to the tattoo machine by means of the power control device,

measuring, directly or indirectly, an rpm of the tattoo machine, comparing the measured rpm to an rpm set-point, and

adjusting, when the measured rpm deviates from the rpm set-point, the power applied by the tattoo machine power control device to the tattoo machine with the aim of getting the measured rpm closer to the rpm set-point.

An advantage of this method is that it provides for an efficient manner of controlling a tattoo machine such that ink can be effectively entered into the skin with a low number of skin penetrations, which reduces the trauma to the skin. Furthermore, the present method can also be applied to old tattoo machines, without requiring any rebuild thereof, which makes it possible to provide such old tattoo machines with the new functionality of controlling the rpm, without requiring any rebuilds of the tattoo machines. According to one embodiment the step of adjusting the power applied by the tattoo machine power control device to the tattoo machine is performed automatically and continuously during operation of the tattoo machine. An advantage of this embodiment is that the rpm of the tattoo machine is adjusted very quickly to changes in the friction to which the needles of the tattoo machine are exposed.

According to one method embodiment said step of measuring, directly or indirectly, an rpm of the tattoo machine involves measuring a present electric current drawn by a rotary electric motor of the tattoo machine as an indirect measure of the present rpm of the tattoo machine. This is an efficient and simple manner of measuring the present rpm of the tattoo machine.

According to one method embodiment said steps of comparing the measured rpm to an rpm set-point, and adjusting, when the measured rpm deviates from the rpm set-point, the power applied by the tattoo machine power control device to the tattoo machine with the aim of getting the measured rpm closer to the rpm set-point, are performed by the tattoo machine power control device being detachably connected to the tattoo machine. An advantage of this embodiment is that efficient, quick and reliable control of the rpm is obtained. Brief description of the drawings

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein:

Fig. 1 is a diagrammatic view in perspective of a tattoo system;

Fig. 2 is a schematic block diagram of a tattoo machine controller unit;

Fig. 3 is a schematic block diagram of a tattoo machine power supply;

Fig. 4a is a diagrammatic view in perspective of a tattoo machine and a tattoo machine power supply prior to connecting;

Fig. 4b is a diagrammatic view in perspective of the tattoo machine and tattoo machine power supply of Fig. 4a when being detachably connected; Fig. 5 is a diagrammatic view in perspective illustrating the docking of a tattoo machine power supply to a tattoo machine controller unit;

Fig. 6 is a schematic block diagram of how a power controller controls the tattoo machine;

Fig. 7 is diagram illustrating a method of controlling the power supplied to a tattoo machine; and

Fig. 8 is a diagrammatic view in perspective illustrating how the tattoo machine controller unit is connected to a tattoo machine via a wire.

Detailed description of the exemplary embodiments

Fig. 1 illustrates an exemplary tattoo system 10, which comprises a first hand-held tattoo machine 12a and a second hand-held tattoo machine 12b. The first tattoo machine 12a is provided with a first tattoo machine power supply 14a, and the second tattoo machine 12b is provided with a second tattoo machine power supply 14b. Each of the two power supplies 14a-b is configured as a battery pack, which is attached to the respective tattoo machine 12a-b. The first power supply 14a is electrically connected to the first tattoo machine 12a for providing the first tattoo machine 12a with electrical power, whereas the second power supply 14b is electrically connected to the second tattoo machine 12b for providing the second tattoo machine 12b with electrical power. The system 10 further comprises a tattoo machine controller unit 16, which may be used for controlling either of the two tattoo machines 12a-b by transmitting control commands to the respective power supplies 14a-b. The controller unit 16 also communicates with a foot pedal 18, which allows a tattoo machine operator to transmit foot pedal commands, e.g. for starting or stopping the tattoo machines 12a-b, to the controller unit 16.

The controller unit 16 comprises a battery pack charging station 20, which allows charging battery packs to be connected to tattoo machines, and a user interface panel 22, which allows an operator to modify and review settings of the controller unit 16 and/or power supplies 14. The user interface panel 22 is provided with a display 24 and a keypad 26. In order to allow a plastic bag to be slipped over the user interface panel 22 from above, the panel 22 is attached to the battery pack charging station 20 by a support post 27, and held upright at a distance from the battery pack charging station 20.

Turning now to Fig. 2, the controller unit 16 is provided with a wireless transceiver 28 for wirelessly communicating with each of the power supplies 14a-b and the foot pedal 18, e.g. by radio or infrared communication. In order to warrant operation also in the case where there is no clear line of sight between e.g. the power supplies 14a-b and the controller unit 16, it is preferred that the communication takes place over a radio interface. A short- range radio interface may be preferred in order to avoid interference with other wireless systems. In particular, ZigBee provides low latency and long battery life, and is therefore particularly well suited for communication between the controller unit 16 and the foot pedal 18 and power supplies 14a- b. The controller unit 16 also comprises a processor 30 and a memory 32. The processor 30 may be configured to process operator commands received from the foot pedal 18 and/or user interface panel 22; update the memory 32 with tattoo machine controller unit settings; generate control commands to be transmitted to power supplies 14a-b; and update the display 24 with control setting information. The processor may also control the battery pack charging station 20, and receive information from the battery pack charging station 20 as well as from any power supply connected to the charging station 20 via a docking interface 21 .

Even though the controller unit 16 may communicate with any or all of the power supplies 14a-b, it is configured to allow the operator to control only one of the power supplies 14a-b at a time. The power supply to be controlled by the operator is called the currently active power supply. In the exemplary system overview of Fig. 1 , the first power supply 14a is the currently active power supply, to which the controller unit 16 is configured to transmit control commands received via the user interface panel 22 or from the foot pedal 18. The second power supply 14b is, in Fig. 1 , in a dormant state. For the purpose of routing control commands to the correct power supply 14a-b, the memory 32 is configured to maintain a list of devices recognized by the tattoo machine controller unit 16. The processor 30 is configured to maintain the list updated with information indicating which of the power supplies 14a-b is the currently active tattoo machine power supply to be controlled by the tattoo machine controller unit 16. When the controller unit 16 receives an operator command from e.g. the foot pedal, the processor 30 accesses the memory 32 and identifies which of the power supplies 14a-b is the currently active power supply, and then automatically routes the foot pedal command to the currently active power supply 14a via the wireless transceiver interface 28. The processor 30 may also generate control messages based on input from the user interface panel 22 and transmit to the currently active power supply 14a. Such control messages may comprise voltage and/or current settings for the electrical power to be supplied by the currently active power supply 14a to the tattoo machine 12a, and/or rpm settings for the reciprocating motion of the tattoo needle. The processor 30 may also update status information on the display 26 (Fig. 1 ) based on input from the foot pedal 18, the key pad 24, the battery pack charging station 20, and/or any of the power supplies 14a-b recognized by the controller unit 16.

An operator may trigger a dormant power supply 14b to wirelessly transmit an activation signal to the controller unit 16. When the activation signal has been received by the controller unit 16, the processor 30 updates the list of recognized devices in the memory 32 to indicate that the activating tattoo machine power supply 14b, i.e. the source of the activation signal, is the currently active tattoo machine power supply to be controlled by the tattoo machine controller unit 16. Thereafter, the first power supply 14a will no longer be the currently active power supply and may enter the dormant state. The de-activating power supply 14a may enter dormant state based on e.g. a time-out, during which no commands are received from the controller unit 16, or based on a de-activation signal transmitted from the controller unit 16 to the de-activating power supply 14a. The controller unit 16 may optionally confirm to the activating power supply 14b that it is now the currently active power supply by transmitting an activation response signal to the activating power supply 14b. The controller unit may also, optionally, transmit any configuration information stored in the memory 32 to the activating power supply 14b. Such configuration information may comprise voltage and/or current settings for the electrical power to be supplied by the activating power supply 14b to the tattoo machine 12b, and/or rpm settings.

Fig. 3 schematically illustrates functional blocks of a tattoo machine power supply 14, such as any of the previously illustrated power supplies 14a-b. The power supply 14 comprises a wireless transceiver 34 for communicating with the controller unit 16, a processor 36, a memory 38, a sensor 40 for detecting the interaction of an operator with the power supply 14, and a power controller 42 for controlling the provision of electrical power from a power source to a tattoo machine, such as any of the tattoo machines 12a-b, via an electrical interface 44. The power controller may, by way of example, be configured as a DC/DC converter unit controlled by the processor 36, or a transistor or switch for on/off regulation. As will be illustrated further below, the electrical interface 44 may be configured as a set of electrical contact terminals. The electrical power source may, by way of example, be a cable connected to an AC or DC voltage source or, as is illustrated in Fig. 3, one or several batteries 46. The sensor 40 may, by way of example, be any type of motion sensor, such as an accelerometer, for detecting when the operator moves the power supply 14. Thereby, the processor 36 may automatically detect when the operator lifts a tattoo machine provided with the power supply 14 from a table, and may

automatically activate the power supply 14 and the associated tattoo machine.

The power supply 14 may initially be in a dormant state. When the sensor 40 detects a user interaction, the processor 36 generates an activation signal, which is wirelessly transmitted to the controller unit 16 via the transceiver 34. The power supply may then enter an active state, in which it is responsive to commands from the controller unit 16 and/or the foot pedal 18. The active state may be entered either directly, or in response to an activation response received from the controller unit 16. When the power supply is in active state, the processor 36 may, based on control signals received from the controller unit 16 or the foot pedal 18, trigger the power controller 42 to supply power from the power source 46 to the tattoo machine via the interface 44. Voltage, current and/or rpm settings governing the power provision may be obtained from the memory 38, and/or from the controller unit 16 via the wireless transceiver 34. Fig. 4a illustrates a tattoo machine 12 and a power supply of battery pack type 14. The tattoo machine 12 is electrically powered and of rotary type, i.e. driven by a rotary electric motor 48, the motion of which is converted to oscillatory tattoo needle motion via a transmission arrangement 50. The motor 48 is located in a motor housing portion 52 of a tattoo machine chassis 54. The motor 48 may be configured to operate on DC electrical power, which may be provided via a pair of terminals 56. An RCA connector 58 provides an auxiliary means of supplying power to the tattoo machine 12, e.g. via an RCA cable (not shown) from a controller unit 16.

The power supply 14 is provided with an electrical interface 44 having a pair of terminals 60 mating with the terminals 56 of the tattoo machine 12, and a third terminal 62 to be described further below. The terminals 60 are located in a recess 64 in the housing 66 of the power supply 14. The recess 64 is shaped to receive the motor housing 52, such that the power supply 14 may be slipped onto the motor housing 52 of the tattoo machine 12 in the manner illustrated by an arrow in Fig. 4b. When the power supply 14 is mounted on the tattoo machine 12, the terminals 60 of the power supply 14 are in electrical contact with the mating terminals 56 of the tattoo machine 12. As has been explained hereinbefore, the power supply 14 may have an identity for the purpose of identifying itself vis-a-vis the controller unit 16. According to an embodiment, the power supply 14 may read an identity of the tattoo machine 12 upon connection to the tattoo machine 12, and use that tattoo machine identity for identifying itself vis-a-vis the controller unit 16. Such a tattoo machine identity may be read by the power supply 14 by communicating with the tattoo machine 12 via the electrical interface 44, or by using an optional RFID tag reader provided in the power supply 14, which may read the identity of an RFID tag (not illustrated) attached to the tattoo machine 12. The tattoo machine identity may be stored in the memory 38 of the power supply 14, and communicated to the controller unit 16 by the wireless transceiver 34 when the power supply 14 is activated. Such an embodiment may have the advantage that any control settings, such as voltage and RPM, are associated with the tattoo machine 12 rather than with the tattoo machine power supply 14.

In the view of Fig. 4b, the tattoo machine 12 is illustrated provided with a tube 68 enclosed by a handgrip 70. The tattoo machine 12 is configured to vertically reciprocate a needlebar 72, which extends through the tube 68, such that the needlebar 72 is axially moved along the tube 68 in an oscillating manner. A lower end 74 of the needlebar 72 may be provided with one or several tattoo needles, which are to penetrate the skin tissue of a human or animal to be tattooed, and release thereinside the ink that will form the body artwork.

The power supply 14 is provided with a pair of batteries 46, which are located on opposite sides of the motor 48 when the power supply 14 is mounted onto the tattoo machine 12.

Turning now to Fig. 5, the power supply 14 may be docked with the battery pack charging station 20 of the controller unit 16. The battery pack charging station 20 has four docking interfaces 21 allowing simultaneous docking and charging of four power supplies. In the illustrated view, two of the docking interfaces are occupied, and hidden, by docked power supplies 14. Each docking interface 21 comprises a pair of charging terminals 76 for mating with the terminals 60 (Fig. 4a) of the power supply 14, for charging the batteries 46, and a third, communication terminal 78 for mating with the third terminal 62 of the power supply 14. The communication terminal 78 allows communication between the power supply 14 and the controller unit 16. The terminals 76, 78 are located on a protrusion 80 shaped so as to extend into the recess 64 of a power supply 14 when docked. A power supply 14 may be docked by lowering it over the protrusion 80 such that the terminals 60, 62 mate with the terminals 76, 78 respectively. When docking a power supply 14, the controller unit 16 identifies whether the power supply 14 is in the list of devices recognized by the controller unit. If not, the controller unit

automatically adds an identity of the docked power supply 14 to the list. By way of example, each identity may be formed by one or several digits, characters, or binary codes uniquely representing the respective power supply 14. The identity may be received from or assigned to the power supply 14 via the communication terminal 78. Thereby, power supplies 14 may automatically be paired with the controller unit 16 by placing them in the charging station 20. The controller unit 16 may also automatically start charging the batteries 46 of a power supply 14 when placed in the charging station 20.

For maximum versatility, the controller unit may also be provided with connectors 82 for connecting legacy, wired tattoo machines and foot pedals.

Fig. 6 illustrates how the power controller 42 of the power supply 14, which is illustrated in more detail in Fig. 3 hereinabove, controls the power supplied to the motor 48 of the tattoo machine 12, which has been described in more detail hereinbefore with reference to, e.g., Figs. 4a-4b. The power supply 14 is detachably connected to the tatto machine 12 and may be removed for charging as described hereinabove with reference to Fig. 5.

First, the wireless transceiver 34 of the power supply 14 receives a signal from the controller unit 16. The signal contains information about the intended voltage that the tattoo artist has entered on the user interface panel 22.

The intended voltage that is entered on the panel 22 by the tattoo artist is, in fact, an indication of the rpm at which the tattoo artist wants the motor 48 of the tattoo machine 12 to operate to give the desired penetration frequency of the needles mounted to the needle bar 72. For example, a setting entered on the keypad 26 of the panel 22 and shown on the display 24 of "6.5 Volt" may correspond to an intended rpm of 4000 rpm, a setting of "8.5 Volt" may correspond to 5000 rpm, and a setting of "10 Volt" may correspond to 6000 rpm, etc. As alternative to entering the intended voltage on the panel 22, the tattoo artist could also enter directly an intended rpm. However, due to the history in the technical area of tattoo machines, many tattoo artists are more acquainted to voltage than to rpm, and therefore has a better

understanding of what, e.g., a setting of "6.5 Volt" means in terms of needle penetration frequency, than what e.g., a setting of "4000 rpm" means in terms of needle penetration frequency. It will be appreciated that the panel 22 could be adapted for setting any type of parameter that indicates in a manner that is meaningful to the tattoo artist at what rate the needles attached to the needle bar 72 are to penetrate the skin. Examples of such parameters include "voltage", "rpm", "needle penetration frequency in Herz", "relative needle penetration frequency value in the range 1 - 10", etc.

For example, the tattoo artist may have entered an intended voltage of "6.5 Volt" on the user interface panel 22. This intended voltage of "6.5 Volt" may, for example, correspond to an rpm value of 4000 rpm. The information about the intended voltage, which is in fact an intended rpm value, is received by the power supply 14 transceiver 34 which forwards this information to the processor 36 of the power supply 14. The processor 36 sends a start power signal S1 to the power controller 42 to the effect that a voltage of 6.5 Volt is to be applied with the intention of operating the motor 48 of the tattoo machine 12 at an rpm of 4000 rpm. The power controller 42 then applies the voltage of 6.5 Volt from the batteries 46, via the electrical interface 44 to the rotary electric motor 48, which starts to drive the needlebar 72 with needles attached to its lower end 74.

The present electric current, in m Ampere, drawn by the motor 48 is measured by the power controller 42, and information about the present electric current is sent to the processor 36 in a feed-back electric current signal S2. The processor 36 analyses the present electric current, as indicated by the signal S2, and compares it to a set point for the electric current, for the applied voltage of 6.5 Volt. If the present electric current is higher than the set point, this is taken as an indication that the motor 48 runs at a lower than intended rpm, because the needlebar 72 with the needle or needles attached thereto is exposed to a high friction. The reason for the high friction could, for example, be that the skin of the human or animal that is to be tattooed is relatively tough, that a large number of needles are attached to the needle bar 72, and/or that the tattoo artist applies the ink deep into the skin, and/or moves the lower end 74 of the needle bar 72 quickly over the skin surface. The processor 36 is adapted to respond to such a detected reduction in the rpm by increasing the voltage above the set point of 6.5 Volt to compensate for the high friction. Hence, the processor 36 may send a power signal S3 to the power controller 42 to the effect that a voltage of, e.g., 8.5 Volt is to be applied. An increase in the voltage from 6.5 Volt to 8.5 Volt increases the torque generated by the motor 48 which means that the motor 48 gets a possibility to operate at the desired rpm of 4000 rpm also at the higher friction to which the needles attached to the needle bar 72 are exposed. The power controller 42 applies this voltage of 8.5 Volt to the motor 48, and sends again the feed-back signal S2 indicating the present electric current. The processor 36 analyses the present current, as indicated by the new signal S2, and compares it to a set point for the current, for the applied voltage of 8.5 Volt, to determine if the intended rpm has been restored: If the rpm, as indicated by the measured current in mAmpere, has still not been restored, the processor 36 may send a further signal S3 to the power controller 42 to the effect that a voltage of, e.g., 9 Volt is to be applied. If the rpm, as indicated by the measured current in mAmpere, has been restored, then the processor 36 may send a further signal S3 to the power controller 42 to the effect that the voltage of, e.g., 8.5 Volt is to be maintained. Finally, if the rpm, as indicated by the measured current in mAmpere, is higher than the set point, then the processor 36 may send a further signal S3 to the power controller 42 to the effect that the voltage is to be reduced to, e.g., 7.5 Volt.

Hence, the rotary electric motor 48 functions as a sensor, sensing by the needlebar 72 the friction to which the needles working the skin are exposed. The friction is, as mentioned above, influenced by, among other things, the toughness of the skin of the human or animal that is to be tattooed, the number of needles attached to the needle bar 72, the depth at which the tattoo artist applies the ink into the skin, and the speed at which the tattoo artist moves the lower end 74 of the needle bar 72 over the skin surface. The information from the motor 48 is the present electric current drawn, and this is measured by the power controller 42 and is forwarded, in the signal S3, to the processor 36. The processor 36 compares the measured current to a set point for the current, and determines which voltage would be expected to be suitable to make the motor 48 operate at the intended rpm, in this example 4000 rpm, given the present friction. The processor 36 sends a signal S3 containing the desired voltage to the power controller 42, and the power controller 42 sets the voltage applied to the motor 48 accordingly. Thereby, the processor 36 controls the voltage applied to the motor 48 to such a level that the desired rpm, in this case 4000 rpm, corresponding to a selected setting, in this case the setting "6.5 Volt", is achieved also when needles mounted to the needlebar 72 works at varying friction.

By means of the present tattoo machine power supply 14 it becomes possible to perform the tattooing process at a relatively low rpm and still at a high torque. This makes it possible to effectively bring the ink into the skin with a low number of skin penetrations. Thereby, the trauma to the skin is reduced compared to traditional tattooing process. The reduced trauma to the skin is an advantage, because it makes the skin healing process quicker.

According to an optional embodiment, the panel 22 of the controller unit 16 could include also the possibility of selecting how agressively the processor 36 is to compensate for variations in the friction, as detected by the motor 48. These compensation settings available for the panel 22 could, for example, be "LOW", "MEDIUM" and "HIGH". The selected compensation setting, "LOW, "MEDIUM" or "HIGH", would be sent via the wireless transceiver 28 of the controller unit 16 to the wireless transceiver 34 of the machine power supply 14, and then be stored in the memory 38, and be used by the processor 36 when controlling the voltage applied to the tattoo machine 12. For example, in the "HIGH" setting, the processor 36 would send signals S3 to the power controller 42 with the intention of always having a constant rpm, very close to the set point for the rpm. In the "MEDIUM" setting, the processor 36 would controll the power in a less aggressive manner, and would accept that the rpm temporarily drops below the set point rpm. In the "LOW" setting, the processor 36 would controll the power in a defensive manner, and would accept that the rpm drops below the set point rpm for rather long periods of time, before ordering an increase in the voltage. The tatto artist can thereby select, depending on personal preferences, whether the rpm is to be kept as close to the set point as possible, by entering the "HIGH" setting, or if the rpm should be allowed to drop to some extent when the needles are forced deeper into the sking, by entering the "LOW" setting, with "MEDIUM" setting being an intermediate between these two extremes.

Fig. 7 illustrates a method of controlling the power applied from the batteries 46 of the tattoo machine power supply 14 to the motor 48 of the tattoo machine 12.

In an initializing step STO a tattoo machine power supply 14 is detachably connected to the tattoo machine 12.

In a first step ST1 a certain voltage, as entered by the tattoo artist on the panel 22 of the tattoo machine controller unit 16 and forwarded wireless to the tattoo machine power supply 14, is applied to the motor 48. According to one example, the set voltage could be "6.5 Volt", and the tattoo artist may desire to obtain the rpm corresponding to that setting. For example, the desired rpm could be 4000 rpm, and at a voltage of 6.5 Volt and with the needles attached to the needle bar 72 being exposed to a low friction that voltage may correspond to a current of 50 mA.

In a second step ST2 the electric current drawn by the motor 48 is measured. Hence, the motor 48 functions as a sensor sensing the friction to which the needles attached to the needle bar 72 are exposed during the tattooing process.

In a third step ST3 the measured current is compared to a set-point for the current. The set-point may, for example, correspond to a current that would result in the desired rpm that corresponds to the selected voltage which the tattoo artist has entered on the panel 22. At a voltage of 6.5 Volt the set- point for current at that voltage could, for example, be 50 mA. If the measured current is lower than the set-point, for example if the measured current is 40 mA, then the method proceeds to step ST4a. If the measured current is equal to the set-point, for example if the measured current is 50 mA, then the method proceeds to step ST4b. Finally, if the measured current is higher than the set-point, for example if the measured current is 120 mA, then the method proceeds to step ST4c.

In step ST4a the voltage applied by the power supply 14 is reduced, for example the voltage may be reduced to 6.0 Volt to reduce the rpm to the desired rpm of 4000 rpm. Hence, for a situation of low friction, a combination of a voltage of 6.0 Volt and a current of 40 mA may be that combination that provides the desired rpm of 4000 rpm, and this information is available to the processor 36 from, e.g., information stored in the memory 38. The method then proceeds to step ST2 for a new measurement of the current, and step ST3 where the measured current is compared to a set-point, which set-point is a specific one connected to the present voltage of 6 Volt.

In step ST4b the voltage applied by the power supply 14 is maintained constant, since the present current and the corresponding rpm is at its desired level. The method then proceeds to step ST2 for a new measurement of the current, and step ST3 where the measured current is again compared to the set-point.

In step ST4c the voltage applied by the power supply 14 is increased, for example the voltage may be increased to 8 Volt to increase the rpm to the desired rpm of 4000 rpm. Hence, for a situation of high friction, a combination of a voltage of 8.0 Volt and a current of 120 mA may be that combination that provides the desired rpm of 4000 rpm, and this information is available to the processor 36 from, e.g., information stored in the memory 38. The method then proceeds to step ST2 for a new measurement of the current, and step ST3 where the measured current is compared to a set-point, which set-point is a specific one connected to the present voltage of 8 Volt.

It will be appreciated that the control of the rpm with the intention of adjusting the power to account for variations in the friction to which the needles attached to the needle bar 72 are exposed with the intention of obtaining a relatively constant rpm can be achieved also in other manners than the above described. For example, the processor 36 may work according to different known process control algoritms, for example PI or PID regulation schemes, with the intention of controlling voltage to keep the rpm of the motor 48 relatively constant at the set rpm during the tattooing process.

Preferably, the steps ST2 to ST4(a, b,c) of controlling the power applied by the tattoo machine power control device 14 to the tattoo machine 12 are performed automatically and continuously during operation of the tattoo machine 12. Fig. 8 illustrates an alternative embodiment in which the tattoo machine 12 is detachably connected to the tattoo machine controller unit 16 by means of a connecting wire 84. The connecting wire 84 comprises at one end 85 thereof an electrical interface in the form of a tattoo machine connector 86 which is adapted for connection to the RCA connector 58 of the tattoo machine 12, shown hereinbefore with reference to Fig. 4a. The other end 88 of the connecting wire 84 is connected to one of the connectors 82 of the tattoo machine controller unit 16. In this embodiment there are no power supplies 14 in use, but the tattoo machine 12 is connected by the wire 84 to the tattoo machine controller unit 16. The tattoo machine controller unit 16 will, in this embodiment, handle the tasks that are handled by the power supply 14 in the embodiment described in Fig. 6. Hence, the processor 30, see Fig. 2, of the controller unit 16 will receive information from the tattoo machine 12 about the present electric current in mAmpere. The measured current will be compared to a set-point for the current at the voltage setting that the tattoo artist has entered on the panel 22. The processor 30 will then control the voltage applied to the tattoo machine 12 via the connecting wire 84 with the intention of keeping the rpm of the tattoo machine at that value, e.g. 4000 rpm, which would correspond to the selected voltage of, e.g., "6.5 Volt", in accordance with principles similar to those described hereinabove with reference to Figs. 6 and 7.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

Hereinbefore it has been described, with reference to Figs. 6-8, how the present current is measured and is used as an indirect measure of the current rpm of the motor 48. It will be appreciated that it is also possible to measure the rpm of the motor 48 directly. This could, for example, be achieved by mounting an rpm sensor to the motor or some of the rotary parts of the motor. For example, it would be possible to measure the rpm from the collector of the motor 48. Hereinbefore it has been described that the voltage is varied to vary the torque of the motor 48 when the needles attached to the needle bar 72 are exposed to a varying friction. It will be appreciated that it is possible to also use other control principles, and to control other variables, to vary the power of the motor 48 as the friction varies.

Hereinbefore it has been described that the processor which handles the adjustment of the rpm is the processor 38 located in the tattoo machine power supply 14 when such power supply 14 is connected to the tattoo machine 12, and is the processor 30 located in the tattoo machine controller unit 16 when the tattoo machine controller unit 16 is connected, via the wire 84, to the tattoo machine 12. It would also be possible, but would normally result in a considerably slower adjustment of the rpm of the tattoo machine 12, to use the processor 30 of the tattoo machine controller unit 16 for controlling the power controller 42 of the power supply 14 by wireless communication. It would, hence, normally be preferred that the processor 30, 38 adapted for controlling the rpm is directly connected to the tattoo machine 12, and not via wireless communication.

Claims

A tattoo machine power control device for applying power to a tattoo machine, c h a r a c t e r i z e d in the tattoo machine power control device (14, 16) comprising an electrical interface (44, 86) adapted for detachable connection of the tattoo machine power control device (14, 16) to a tattoo machine (12), wherein the tattoo machine power control device (14, 16) is adapted to receive a signal (S2) indicating the present rpm of the tattoo machine (12) and to adjust the power applied to the tattoo machine (12) based on a desired rpm.

A power control device according to claim 1 , wherein the tattoo machine power control device (14, 16) is adapted for receiving a current signal (S2) indicating the electric current drawn by a tattoo machine motor (48) of a tattoo machine (12), and for using said current signal (S2) as an indirect indication of the present rpm of the tattoo machine (12).

A power control device according to any of the preceding claims, wherein the tattoo machine power control device comprises a tattoo machine controller unit (16) which is adapted for being connected via a connecting wire (84) to a tattoo machine (12) in a detachable manner, wherein the controller unit (16) comprises at least one processor (30) for adjusting the power supplied from the controller unit (16) to the tattoo machine (12) based on a desired rpm.

A power control device according to any of the preceding claims, wherein the tattoo machine power control device comprises a tattoo machine power supply (14) which is adapted for detachable connection to a tattoo machine (12) and which comprises at least one battery (46) adapted for supplying power to the tattoo machine (12) and at least one processor (38) for controlling the power supplied from the at least one battery (46) to the tattoo machine (12) based on a desired rpm.

A power control device according to claim 4, wherein the tattoo machine power supply (14) is adapted for wireless communication with a tattoo machine controller unit (16) and for receiving from the tattoo machine controller unit (16) a signal indicating the desired rpm.

A power control device according to any one of claims 3-5, wherein the processor (30, 38) adapted for controlling the power applied to a tattoo machine (12) is adapted for being directly connectable to the tattoo machine (12).

A power control device according to any one of the preceding claims, wherein the tattoo machine power control device (14, 16) is adapted to control the voltage applied to the tattoo machine (12).

A power control device according to any one of the preceding claims, wherein the tattoo machine power control device (14, 16) is adapted for being set to at least a first compensation setting and a second compensation setting, wherein the power control device (14, 16) is adapted to react more aggressively to deviations in the rpm when in the first compensation setting (HIGH) compared to when in the second compensation setting (LOW).

A tattoo system, c h a r a c t e r i z e d in comprising a tattoo machine power control device (14, 16) according to any one of the preceding claims, and a tattoo machine (12) comprising a rotary electric motor (48).

10. A method of controlling the power applied to a tattoo machine (12), the method comprising: - detachably connecting a tattoo machine power control device (14, 16) to the tattoo machine (12),

- applying power to the tattoo machine (12) by means of the power control device (14, 16),

- measuring, directly or indirectly, an rpm of the tattoo

machine (12),

- comparing the measured rpm to an rpm set-point, and

- adjusting, when the measured rpm deviates from the rpm set-point, the power applied by the tattoo machine power control device (14, 16) to the tattoo machine (12) with the aim of getting the measured rpm closer to the rpm set-point.

1 1 . A method according to claim 10, wherein the step of adjusting the power applied by the tattoo machine power control device (14, 16) to the tattoo machine (12) is performed automatically and continuously during operation of the tattoo machine (12).

12. A method according to any one of claims 10-1 1 , wherein said step of measuring, directly or indirectly, an rpm of the tattoo machine (12) involves measuring a present electric current drawn by a rotary electric motor (48) of the tattoo machine (12) as an indirect measure of the present rpm of the tattoo machine (12).

13. A method according to any one of claims 10-12, wherein said step of detachably connecting a tattoo machine power control device

(14, 16) to the tattoo machine (12) involves detachably connecting a tattoo machine power control device in the form of a battery pack (14) to the tattoo machine (12).

14. A method according to any one of claims 10-13, wherein said

tattoo machine power control device (14) receives by wireless communication an rpm set-point from a tattoo machine controller unit (16).

15. A method according to any one of claims 10-14, wherein said steps of comparing the measured rpm to an rpm set-point, and adjusting, when the measured rpm deviates from the rpm set-point, the power applied by the tattoo machine power control device (14, 16) to the tattoo machine (12) with the aim of getting the measured rpm closer to the rpm set-point, are performed by the tattoo machine power control device (14, 16) being detachably connected to the tattoo machine (12).