Human and animal bodies are typically treated using drugs, invasive surgery and applied therapies such as physiotherapy. Such treatments can have side effects, be traumatic and costly. It has been discovered that magnetic fields can be used to treat human or animal bodies. In particular, an approach lu1own as Pulsed Magnetic Field Therapy (PMFT) is known in the art for relieving pain.

PMFT is the application of magnetic fields to an area of a human or animal body that is suffering from, for example acute or cl-ironic pain, wherein the magnetic field strength is varied over a period of time in a controlled manner. Since the magnetic field is constantly changing it interacts with the body by inducing small electrical currents in the body's tissue in the regions affected by the magnetic field.

Most existing devices for implementing PMFT use pulses of direct current to stimulate an electromagnet or coil to generate an electromagnetic field. Typically the frequency of the pulses is between 0.5 and 15Hz which is thought to be in accordance with natural frequencies of the human body. Some other devices that use a mains electricity supply that have an oscillation frequency in the range 50-60Hz.

Whilst the above devices provide some therapeutic effect by reducing pain, the magnetic fields generated by such devices are not optimised.

Accordingly the present invention seeks to provide an improved therapeutic device that is constructed and arranged to produce magnetic fields that provide an improved therapeutic effect by, for example, alleviating pain more effectively.

According to one aspect of the present invention there is provided a therapeutic device that includes means for producing electrical signals and a coil that is constructed and arranged to generate a magnetic field in response to energisation by the electrical signals, wherein

the means for producing the electrical signals is constructed and arranged to produce wave forms that include decaying pulses.

The therapeutic device can be used to treat human and animal bodies in particular to reduce the effects of pain. In operation the device is used to produce a varying magnetic field in the vicinity of the area of the body under treatment such that the magnetic field extends into the body to stimulate localised tissue.

Advantageously the means for producing electrical signals is constructed and arranged to produce pulses that decay exponentially.

Advantageously the means for producing electrical signals is constructed and arranged to produce pulses that have a duration in the range 1 to 5 milliseconds, and preferably a duration of approximately 3 milliseconds.

Advantageously the means for producing electrical signals is constructed and arranged to produce n number of pulses per second, wherein n is in the range 0.5 to 10, and n is preferably 1. 25 pulses per second.

Advantageously the means for producing electrical signals is constructed and arranged to produce wave forms having a frequency in the range 15KHz to 30KHz, and preferably having a frequency of approximately 23KHz.

Advantageously the means for producing electrical signals is constructed and arranged to produce wave forms having peak voltages in the range 5 to : : L 20 volts.

Advantageously the magnetic field generated has a field strength in the range 5 to 15 mT, and is preferably approximately 10 mT.

Preferably the therapeutic device is constructed and arranged to be a handheld device that is powered by at least one electrical cell and includes a direct current to alternating current converter.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which like references indicate equivalent features, wherein :

Figure 1 is an exploded general arrangement of an embodiment of a therapeutic device in accordance with the invention ; Figure 2 shows an example of a wave form used to excite a coil to produce a varying magnetic field ; and Figure 3 shows the wave form of Figure 2 on a smaller scaled time axis.

Figure 1 shows an embodiment of a therapeutic device in accordance with the current invention that includes a body 1, a first end cap 3, an on í off switch 5, an indicator light 7, electronic circuitry 9 and a second end cap 11.

The therapeutic device is a portable hand-held device having a mass of around 80 grams, a length of 193mm, a minimum diameter of 17mm and a maximum diameter of 28mm. The body 1 is made from an aluminium alloy tubing and has an internal cavity arranged to accommodate two electric cells. At one end of the body 1 the cavity includes an internal screw thread. The first end cap 3 is also made from an aluminium alloy and includes an external screw thread 13 that is complementary to the internal screw thread of the body 1.

The first end cap 3 can be removed from the body 1 to provide access to the cells located therein.

The electronic circuitry 9 is located in the internal cavity at the other end of the body 1. The second end cap 11 screws onto the body to protect the electronic circuitry. The second end cap 11 is made from nylon 66 because it is substantially inert. That is, the second end cap 11 does not react with the user's skin if the end cap 11 is brought into contact with the user's body, for example, during treatment.

The electronic circuitry 9 includes a direct current to alternating current (DC to AC) converter and a coil for generating an alternating magnetic field. The DC to AC converter is used to convert direct current from the cells into an alternating current having the desired wave form. The alternating current is used to energie the coil which generates a magnetic field. The magnetic field generated radiates outwards from the coil through the second end cap 11, and varies according to the wave form stimulating the coil.

Optionally, the coil may include a core made from a ferrous material such as iron or steel.

The wave form of the electrical signals that energise the coil includes exponentially decaying pulses. Typically, the wave form has a pulse frequency in the range 0.5 to l OHz, a peak voltage in the range i 5 to to-+ 20V, a pulse length in the range 1 to 5 milliseconds and an oscillation frequency in the range 15KHz to 30KHz. Figures 2 and 3 show the characteristics of a single pulse of a preferred wave form. The wave form has an oscillation frequency of 23KHz, a 12V peak voltage, a pulse length of 3 milliseconds and a pulse frequency of 1.25 Hz.

The indicator light 7 is arranged to be illuminated when the device is activated.

In use, a user positions the device such that the second end cap 11 is a few millimetres from the first area of the human/animal body to be treated. The device is preferably held adj acent exposed flesh but alternatively treatment can take place through light clothing. The user then energies the coil by switching the device on, causing a magnetic field to radiate from the coil into the body and stimulate the tissue in the localised area. The user slowly sweeps the device over the painful area maintaining the device a few millimetres away from the body. Because the magnetic field is constantly changing in a controlled and predictable way it induces electrical currents in the tissue. After a short period a subtle dragging effect is felt by the user. The effect has been described by users as"a pulling sensation like dull toothache',"a slight pricking sensation","a pleasant wanning or cooling sensation", "sensations running to other parts of the body"and"deqi-like effects remarkably similar to needling".

After the"dragging"effect diminishes or if the recipient is no longer aware of treatment effects the user moves the device to a second, or subsequent, area of the body that requires treatment. The process should be repeated until all areas of the body, requiring treatment have been so treated. In most instances the user is advised to treat a particular area for no longer than three minutes.

It has been found that treatment with the therapeutic device for only a few minutes a week can significantly relieve pain for many ailments. In particular, use of the therapeutic device has been found to relieve conditions such as arthritis (RA & OA), acute soft tissue injury, post-helpetic neuralgia, coccydynia, amputation pain, chronic back pain, headache, migraine, dental pain, dysmenorrhoea, heel pain, and dermatitis. This list is not exhaustive.

The most recent clinical trials suggest that PMFT induces one or more of the following effects to alleviate pain: vasodilatation, analgesia, anti-inflammatory effect, spasmolytic effect, healing acceleration and oedema reduction. However, the effects of PMFT on human and animal bodies is not fully understood at this time and therefore the invention is not to be construed as being limited to any one, or any combination, of the above effects.

Use of the device can be combined with other pain relieving techniques such as acupuncture, acupressure, chiropractic, osteopathy and physiotherapy. Knowledge of acupuncture points and techniques is not essential for obtaining pain relief however clinical experience suggests that superior results are frequently obtained when treatment includes the use of appropriate local and distant acupoint stimulation.

The device can be used exclusively for pain management, or it may be used as an alternative to needling (or other forms of stimulation) of acupoints when pain management is not the focus of treatment.

It will be appreciated that alterations can be made to the embodiment described above without departing from the spirit of the present invention. For example, a wave form can be used that has a different rate of decay, a longer/shorter pulse length, frequency of pulses or a higher/lower peak voltage.

Also, a larger non-portable therapeutic device, for example for whole body treatment, can be constructed and arranged to operate on the same principles as the portable device described herein.