Neuromuscular stimulator

Abstract

A dual channel neuromuscular stimulator. Pulses developed by a pulse generator are transmitted alternately on both channels to involuntarily contract muscles. The stimulator has variable on/off cycling capability to provide flexibility in meeting the stimulation needs of patients and has output current adjustments and other variable parameter settings to achieve optimum neuromuscular stimulation. To enhance patient comfort, the stimulation output of the stimulator can be slowly "ramped up" to its full stimulation power to allow the increase in stimulation to occur at various rates to accommodate the differing characteristics of different muscle groups. A jack is provided to permit the stimulation to be controlled by an external switch operated by a clinician to coordinate stimulation of various muscle groups with voluntary muscle contraction by the patient. The jack can also be connected to a heel operated switch to stimulate muscle groups to allow certain disabled persons to walk normally. The balanced biphasic output waveform of the stimulator has a zero net DC component to minimize the possibility of skin rash developing from stimulation.

What is claimed is: 
     
       1. A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   rate control means coupled to said oscillator means for altering the repetition rate of said oscillator means;   inverter means, coupled to receive the output of said oscillator means, for producing a periodic output signal having a polarity opposite to that of the periodic output signal produced by said oscillator means;   treatment timer means for generating a first logic signal after a predetermined treatment time interval;   treatment timer control means coupled to said treatment timer means for establishing the predetermined treatment time of said treatment timer means;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   first cycler control means completed to said cycler means for setting the predetermined "on" time interval of said cycler means;   second cycler control means coupled to said cycler means for setting the predetermined "off" time interval of said cycler means;   external switch means;   plug means operatively connected to said external switch means;   accessory jack means constructed and arranged for receiving said plug means and for providing a third logic signal when said plug means is inserted in said jack means and said external switch means is in a particular condition or when said plug is not inserted in said jack;   momentary contact switch means for producing a fourth logic signal when said momentary .[.on.]. .Iadd.contact .Iaddend.switch means is actuated;   first and second ramp generator circuit means connected to receive said first, second, third and fourth logic signals and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of either of said first, second, third or fourth logic signals;   first and second ramp generator control means coupled respectively to said first and second ramp generator circuit means for independently altering the rate of change of the output ramp signals of said first and second ramp generator circuit means;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said .[.second.]. .Iadd.first .Iaddend.ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the inverted periodic output signal of said inverter means and for producing a fixed amplitude pulse signal having a pulse width increasing at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively and for producing a balanced biphasic constant current output signal; and   first and second output circuit control means for adjusting the current amplitude of the output pulses of said first and second output circuits respectively.   
     
     
       2. The invention of claim 1 wherein said rate control means is constructed and arranged for altering the repetition rate of said oscillator means between 3 and 50 pulses per second. 
     
     
       3. The invention of claim 1 wherein said treatment timer control means is constructed and arranged for establishing the treatment time of said treatment timer means at 15, 30 or 60 minutes or continuous. 
     
     
       4. The invention of claim 1 wherein said first cycler control means is constructed and arranged for setting predetermined "on" time intervals between 2 and 25 seconds. 
     
     
       5. The invention of claim 1 wherein said second cycler control means is constructed and arranged for setting predetermined "off" time intervals between 2 and 50 seconds. 
     
     
       6. The invention of claim 1 wherein said first and second ramp generator control means are constructed and arranged for varying the rate of increase of said first and second output ramp circuits from first to second levels between 0.5 and 8 seconds. 
     
     
       7. The invention of claim 1 wherein said first and second output circuit control means is constructed and arranged for adjusting the amplitude of the output pulses between 30 and 100% of a maximum output current. 
     
     
       8. The invention of claim 7 wherein said first and second output circuit means are constructed and arranged to provide a maximum constant output current between 90 and 100 milliamps over a load impedance range of 100 to 1,000 ohms. 
     
     
       9. A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   inverter means coupled to receive the output of said oscillator means, for producing a periodic output signal having a polarity opposite to that of the periodic output signal produced by said oscillator means;   treatment timer means for generating a first logic signal after a predetermined treatment time interval;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   external switch means;   plug means operatively connected to said external switch means;   accessory jack means constructed and arranged for receiving said plug means and for providing a third logic signal when said plug means is inserted in said jack means and said external switch means is in a particular condition or when no plug is inserted in said jack;   momentary contact switch means for producing a fourth logic signal when said momentary .[.on.]. .Iadd.contact .Iaddend.switch means is actuated;   first and second ramp generator circuit means connected to receive said third and fourth logic signals and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of said first, second, third or fourth logic signals;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said .[.second.]. .Iadd.first .Iaddend.ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the inverted periodic output signal of said inverter means and for producing a fixed amplitude pulse signal having a pulse width increasing at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width; and   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively and for producing an output signal.   
     
     
       10. A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   treatment timer means for generating a first logic signal after a predetermined treatment time interval;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   external switch means;   plug means operatively connected to said external switch means;   accessory jack means constructed and arranged for receiving plug means and for providing a third logic signal when said plug means is inserted in said jack means and said external switch means is in a particular condition or when no plug is inserted in said jack;   momentary contact switch means for producing a fourth logic signal when said momentary .[.on.]. .Iadd.contact .Iaddend.switch means is actuated;   first and second ramp generator circuit means connected to receive said third and fourth logic signals and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of said first, second, third or fourth logic signals;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said .[.second.]. .Iadd.first .Iaddend.ramp generator circuit means reaches the signal level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively and for producing an output signal; and   further means operatively coupled to said first and second pulse width circuit means and said oscillator means for causing said first and second pulse width circuit means to produce said first and second output pulse signals alternately at the predetermined repetition rate of said oscillator means.   
     
     
       11. A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   inverter means, coupled to receive the output of said oscillator means, for producing a periodic output signal having a polarity opposite to that of the periodic output signal produced by said oscillator means;   treatment timer means for generating a first logic signal after a predetermined time interval;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   logic means connected to receive said first and second logic signals and provide a third logic signal when either said first or said second logic signals are received;   first and second ramp generator circuit means connected to receive said third logic signal and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of said third logic signal;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said .[.second.]. .Iadd.first .Iaddend.ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the inverted periodic output signal of said inverter means and for producing a fixed amplitude pulse signal having a pulse width increasing at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width; and   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively and for producing an output signal.   
     
     
       12. A muscle stimulator comprising: output enabling means for producing an enabling signal to enable generation of output pulses by said stimulator;   interval timing means connected to receive the enabling signal fromm said output enabling means and for generating repetitive bursts of pulse initiating signals, the time duration of each burst of pulse initiating signals being a first predetermined time interval and the time interval separating said bursts of pulse initiating signals being a second predetermined time interval, said interval timing means including means for independently adjusting said first and said second time intervals;   further timing means connected to receive pulse initiating signals from said interval timing means and for producing output signals having fixed pulse amplitude and a pulse width increasing from zero to a selected value over a third predetermined time interval, upon receipt of the first initiating signal in a burst of pulse initiating signals; and   an output circuit connected to receive the output signal from said further timing means and for producing output pulses suitable for stimulation of muscle tissue. .Iadd.   
     
     
       13.  A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   rate control means coupled to said oscillator means for altering the repetition rate of said oscillator means;   treatment timer means for generating a first logic signal after a predetermined treatment time interval;   treatment timer control means coupled to said treatment timer means for establishing the predetermined treatment time of said treatment timer means;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   first cycler control means coupled to said cycler means for setting the predetermined "on" time interval of said cycler means;   second cycler control means coupled to said cycler means for setting the predetermined "off" time interval of said cycler means;   external switch means;   plug means operatively connected to said external switch means;   accessory jack means constructed and arranged for receiving said plug means and for providing a third logic signal when said plug means is inserted in said jack means and said external switch means is in a particular condition or when said plug is not inserted in said jack;   momentary contact switch means for producing a fourth logic signal when said momentary contact switch means is actuated;   first and second ramp generator circuit means connected to receive said first, second, third and fourth logic signals and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of either of said first, second, third or fourth logic signals;   first and second ramp generator control means coupled respectively to said first and second ramp generator circuit means for independently altering the rate of change of the output ramp signals of said first and second ramp generator circuit means;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said first ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the periodic output signal of said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively and for producing a balanced biphasic constant current output signal; and   first and second output circuit control means for adjusting the current amplitude of the output pulses of said first and second output circuits respectively. .Iaddend. .Iadd.   
     
     
       14.  The invention of claim 13 wherein said rate control means is constructed and arranged for altering the repetition rate of said oscillator means between 3 and 50 pulses per second. .Iaddend. .Iadd.15. The invention of claim 13 wherein said treatment timer control means is constructed and arranged for establishing the treatment time of said treatment timer means at 15, 30 or 60 minutes or continuous. .Iaddend. 
     
     
        .Iadd.16.  The invention of claim 13 wherein said first cycler control means is constructed and arranged for setting predetermined "on" time intervals between 2 and 25 seconds. .Iaddend. .Iadd.17. The invention of claim 13 wherein said second cycler control means is constructed and arranged for setting predetermined "off" time intervals between 2 and 50 seconds. .Iaddend. .Iadd.18. The invention of claim 13 wherein said first and second ramp generator control means are constructed and arranged for varying the rate of increase of said first and second output ramp circuits from first to second levels between 0.5 and 8 seconds. .Iaddend. .Iadd.19. The invention of claim 13 wherein said first and second output circuit control means is constructed and arranged for adjusting the amplitude of the output pulses between 30 and 100% of a maximum output current. .Iaddend. .Iadd.20. The invention of claim 19 wherein said first and second output circuit means are constructed and arranged to provide a maximum constant output current between 90 and 100 milliamps over a load impedance range of 100 to 1,000 ohms. .Iaddend. .Iadd.21. A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   treatment timer means for generating a first logic signal after a predetermined treatment time interval;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   external switch means;   plug means operatively connected to said external switch means;   accessory jack means constructed and arranged for receiving said plug means and for providing a third logic signal when said plug means is inserted in said jack means and said external switch means is in a particular condition or when no plug is inserted in said jack;   momentary contact switch means for producing a fourth logic signal when said momentary contact switch means is actuated;   first and second ramp generator circuit means connected to receive said third and fourth logic signals and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of said first, second, third or fourth logic signals;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said first ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the periodic output signal of said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width; and   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively   
     
     
        and for producing an output signal. .Iaddend. .Iadd.22.  A muscle stimulator comprising, in combination: oscillator means for producing a periodic output signal at a predetermined repetition rate;   treatment timer means for generating a first logic signal after a predetermined time interval;   cycler means for repetitively producing a second logic signal which remains at a first logic level for a predetermined "on" time interval and a second logic level for a predetermined "off" time interval;   logic means connected to receive said first and second logic signals and provide a third logic signal when either said first or said second logic signals are received;   first and second ramp generator circuit means connected to receive said third logic signal and for producing first and second output ramp signals changing from a first to a second level at first and second predetermined rates, subsequent to receipt of said third logic signal;   first pulse width circuit means coupled to receive the ramp signal from said first ramp generator circuit means and to receive the periodic output signal from said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasing at a rate proportional to the rate of change of the ramp signal from said first ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said first ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width;   second pulse width circuit means coupled to receive the ramp signal from said second ramp generator circuit means and to receive the periodic output signal of said oscillator means and for producing a fixed amplitude pulse signal having a pulse width increasng at the rate of change of said ramp from said second ramp generator circuit means at the predetermined repetition rate of said oscillator means until the output signal of said second ramp generator circuit means reaches the second level and the pulse width of the pulse signal reaches a predetermined pulse width; and   first and second output circuit means connected to receive the pulse outputs of said first and second pulse width circuit means respectively and for producing an output signal. .Iaddend.