GB2303066A

GB2303066A - Magnetic therapy system

Info

Publication number: GB2303066A
Application number: GB9513969A
Authority: GB
Inventors: Kathryn Naylor
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-07-08
Filing date: 1995-07-08
Publication date: 1997-02-12
Also published as: GB9513969D0; GB2303066A9

Abstract

Apparatus for administering magnetic therapy comprises a chair 10 having at least one coil 20, 22 built into the back and/or seat thereof and is provided with a control panel 26 capable of producing an alteration in the magnetic field(s) applied.

Description

MAGNETIC THERAPY SYSTEM This invention relates to a magnetic therapy system and in particular relates to such a system built into a chair.

Magnetic therapy is known and used in the treatment of certain injuries, and for pain relief, particularly of muscular pain.

It has been proposed to locate electric coils within a mattress to give magnetic therapy to a supine patient. However, often this is not convenient, particularly where treatment during the day time is required.

The invention seeks to provide an apparatus for administering magnetic therapy improved in the above respects.

According to the present invention there is provided an apparatus for administering magnetic therapy which comprises a chair having at least one coil built into the back and/or seat thereof and being provided with a control panel for controlling the magnetic field.

Preferably, each of the back and seat portions of the chair are provided with coils and, more advantageously, a pair of coils.

Conveniently, the control panel is located in an arm of the seat and may be concealed by a flap or the like.

The coils are preferably connected to a digitally controlled square wave generator. The latter may be fully programmable from the control panel giving digital control over the frequency, intensity and pulse width of the wave form, together with a digital timer for length of treatment. The frequency range will generally vary between 1 and 100 hertz, with frequencies in the range of 2 to 50 hertz being preferred.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic elevational view of a chair in accordance with the invention; Figure 2 is a diagram of a square wave form; and Figure 3 is a similar view to figure 2 showing a different pulse width.

Referring to the drawings, and in particular figure 1, it can be seen that a chair generally designated 10 comprises a seat portion 12 and back portion 14 with arms 16,18. Within the seat portion 12 are located a pair of coils 20. A pair of coils 22 is located within the back portion 14.

The arm 18 has a hinged flap portion 24 which can be lifted back (as illustrated in the figure) to reveal a control panel 26.

In use, the patient sits in the chair and sets the control panel to the desired intensity and length of treatment as will be described more fully hereinafter.

A square wave form is generated preferably using CMOS integrated circuit technology to generate and control a precise square wave. A variable RC Schmitt oscillator having digital presetable frequency and pulse width controls may be provided.

An intensity control determines the wave form height. A timer, also using an RC oscillator to generate a clock signal, is also present which drives a digital counter to produce accurate repeatability of the timing function. On/off control may be by a dedicated flip flop circuit with an interlock to prevent changes to the settings being made while the equipment is in operation. The output may be controlled by a 20A bipolar transistor, darlington driven, which feeds output circuits which in turn are connected to the coils 20,22.

The coils 20,22 are preferably constructed from a polyester enamel wire wound into an oval formation and covered with a tough PVC coating. Power may be supplied by a twin fused torroidal isolating transformer through a full wave, push-pull rectifier with smoothing capacitors. CMOS supply is via a 12 volt integrated voltage regulator.

In clinical use, pulsed magnetic fields are derived by the pulse generator supplying a time varying current to the coils 20,22. Ideally, the coils are positioned facing one another at 1800 with the damaged tissue or extremity between them.

However, in practice, it has been found that the coils can be laid flat side by side to cover larger areas and still produce the desired healing effect. The generator of the invention may employ treatment frequencies of 50, 25, 17, 12, 10, 8, 5, 4, 3, and 2 hertz generated from a quartz crystal oscillator giving a high degree of accuracy and repeatability. The square wave so produced can be divided using a pulse width control thereby giving additional flexibility when determining the intensity of treatment. The pulse width control provides a fine tuning mechanism and allows the therapist to optimise the treatment for individual patients. This can be determined empirically or by calculation as set out below.

a) Fundamental pulse width. (tf) By definition frequency F=l/t Hz where t is the interval between pulses as show in figure 2.

In the generator of the invention time t(on) = t(off), therefore: t(on) = 1/2F = t(off) (seconds) t(on) then is the fundamental pulse width at any set frequency i.e. tF.

b) Pulse width (tPW) The set pulse width control value "n" will determine the final pulse width applied to the magnetic field coils and can be shown to be:tPW = tF * n/10 where n 5 set pulse width value as shown on the front panel.

c) Relaxation period (tR) The relaxation period tR is the period between pulses as shown in figure 3.

If t s the interval between pulses and tPW is the final pulse width, then the relaxation period is:tr = t - tPW ExamDles 1. For a set FREQUENCY of 50Hz and set PULSE WIDTH of 2, the final applied pulse width and relaxation period can be determined as follows.

Front (a) t = 1/F 8 1/50 t 0.02 seconds s 20ms (milliseconds) tF = 1/2F - 1/100 = 0.01 seconds = lOms (milliseconds) From (b) the final pulse width is tPW = tF * n/10 therefore, tPW = 10 * 2/10 = 2ms and from (c) the relaxation period is tR = t - tPW = 20 - 2 - 18ms 2.For a set FREQUENCY of 10 Hz and a set pulse width of 5 then, t = 1/f - 1/10 = 0.1 secs - lOOms tF = 1/2F = 1/20 = 50ms therefore, tPW = tF * n/10 = 50 * 5/10 5 25ms and tR = t - tPW = 100 - 25 = 75ms Although frequency and pulse width control are the major factors for successful treatment, two other factors must be considered.

1. INTENSITY: The intensity control varies the amplitude of the pulse produced and therefore the magnitude of magnetic field produced. In general terms the greater the amplitude the greater the depth of penetration of the magnetic field into the tissue and also the greater the looping currents generated within the tissue. This setting therefore requires careful consideration dependent on the injury site and the nature of the injury.

2 TIME: The time control is the elapsed treatment time and in general terms is set low for ACUTE injuries and high for CHRONIC injuries.

The magnetic field system of the invention therefore allows considerable flexibility of control and hence has wide application in many forms of injury.

As a good general treatment rule, when a low frequency (2 - 8 Hz) is used, blood flow to the treated areas will be restricted and inflammation and swelling will be reduced much more rapidly than by natural means. When this stage has been passed the middle frequency range (10 - 17 Hz) is used to accelerate the healing process. The higher frequencies (25 - 50 Hz) act to dilate the blood vessels and increase the circulation and deliver more oxygen to the affected parts.

Magnetic field intensity and treatment time will always be a compromise dependent on the injury site and the nature of the injury. It is sometimes, for instance, worth considering lower intensities and longer treatment times especially for the more chronic injuries.

The apparatus of the invention provides a convenient way of treating patients in comfort without requiring them to lie down.

Claims

1. Apparatus for administering magnetic therapy which comprises a chair having at least one coil built into the back and/or seat thereof and being provided with a control panel for controlling the magnetic field.

2. Apparatus according to Claim 1, wherein each of the back and seat portions of the chair are provided with coils.

3. Apparatus according to Claim 2, wherein each of the back and seat portions of the chair are provided with a pair of coils.

4. Apparatus according to any of the preceding Claims, wherein the control panel is located in an arm of the seat and may be concealed by a flap or the like.

5. Apparatus according to any of the preceding Claims, wherein the coils are connected to a digitally controlled square wave generator.

6. Apparatus according to Claim 5, wherein the square wave generator is fully programmable from the control panel giving digital control over the frequency, intensity and pulse width of the wave form, together with a digital timer for length of treatment.

7. Apparatus according to Claim 5 or Claim 6 wherein the frequency range is between 1 and 100 hertz.

8. Apparatus according to Claim 7, wherein the frequency range is between 2 and 50 hertz.

9. Apparatus substantially as herein described and illustrated in the accompanying drawings