SPECIFICATION Transcutaneous electronic nerve stimulatorThis invention relates to a device for thedelivering of an electric stimulus to a person for therapeutic purposes.
According to the present invention there isprovided a device for applying to a part of aperson for therapeutic purposes an electricaldischarge at a current low enough not todamage body tissue at a voltage high enough to stimulate a nerve.
In practice, a discharge energy of approximately 0,93mJ at a voltage of 8 to 12Kilovolts is employed. The duration of thedischarge is generally from 15 to 50 microseconds and is preferably about 20 microseconds. Although any suitable means for generating the electrical discharge may be employed for example a battery run pulse generator, employing a transistor circuit which through a transformer charges a capacitor,preferably the device according to the presentinvention employs a piezo-electric crystal, which when struck produces the momentaryelectrical discharge. The arrangement in which the piezo-electrical crystal is struck asharp blow is prefered since the crystal can therefore be overloaded for a short period as to produce a single discharge pulse which canbe then modified.If a naked spark is applied to the skin of a person, there is a tendency for the skin tissue to be damaged, thus it isprefered that the electrical discharge is modified by a special resistance capacitance network before it is conducted to the part of theperson destined to receive it by means of aconductor which has direct contact to theskin.
A referred embodiment of a device according to the present invention will now bedescribed by reference to the accompanyingdrawing in which Figs. 1 + 2 are respectively side elevations of a piezo-electric device for the employment in the device of the presentinvention andFig. 3 is a longitudinal section of an embodiment of the device of the present invention.
In Figs 1 + 2 of the drawings there is showna piezo-electric generator which is suitable for employment in a device according to thepresent invention. The main features of thepiezo-electric generator are the barrel portion containing a piezo-electric crystal and an impact mechanism which is arranged to be discharged by an axially inward movement of trigger (2). The electrical conductors (3 + 4) are arranged to carry the electrical impulse generated when the crystal is struck.
Fig. 3, the device of Figs. 1 + 2 is shownmounted within a housing (5) which has a chamber (6) in which the special resistorcapacitor network is held. On one end the conductor 3 is in electrical communication to the resistor-capacitor network, while on the other a rod with a rounded end 7 which is carried within the end portion 8.
In operation, the trigger 2 is pressed, which causes the piezo-electric crystal to be struck and to generate a momentary electrical discharge. This discharge is conveyed to the special resistor-capacitor network via 3 then via conductive member 7 from where it is conducted to the part of the person.
The special resistor-capacitor network can be adjusted as to alter the size of the discharged energy to the part of the person in accordance to the preference of the user although generally this is set at a commonly accepted preference.
It will be appreciated that by means of the device of the present invention a momentary energy discharge of a safe power and a relatively high speed may be readily delivered to any part of the body for therapeutic purposes.
For example with earlier described battery run pulse generators which wen attached to the skin, generate signals which after a while in some way relieve pain by interfering with the passage of pain signals along the nerve to the brain, the above described device uses a "one shot pulse" to achieve the same if lesser results. The advantages are that there are no special electrodes that need to be adherred to the skin, its size, making it highly portable and appart from the short pulse there are no repellent side effects which is commonly found with battery run devices.