Output pulse compensation for therapeutic-type electronic devices

Abstract

Pulse compensation is disclosed for electronic devices capable of producing a pulse output signal suitable for therapeutic purposes with pulse compensation being automatically provided upon sensing of a change in she conditions being monitored. The electronic device, which preferably includes a microcomputer, has externally accessible pulse width and intensity controls for determining the width and amplitude of pulses then being delivered. Upon each sensing of a change in a monitored condition capable of causing user discomfort or possible injury, the intensity of the pulses then being delivered is quickly reduced and then gradually increased toward the full intensity requested by the intensity control. Pulse compensation is also provided when the pulse width is varied by the pulse width control to thereby automatically cause a corresponding change in the range of intensities of the pulses then delivered, based upon a nerve fiber strength-duration curve or the pulses, to thereby maintain the stimulation capability of the pulses substantially constant at a percentage of intensity as determined by the intensity control.

What is claimed is: 
     
       1. An electronic device for providing output pulses .Iadd.to a user .Iaddend.for therapeutic purposes, said device comprising: electronic controller means .Iadd.for .Iaddend.providing control pulses;   voltage supply means .Iadd.for .Iaddend.providing a voltage output;   pulse output means including transistor means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses for therapeutic purposes having an intensity .Iadd.level .Iaddend.and .Iadd.a .Iaddend.pulse width subject to change due to the occurrence of predetermined condition variations; and   said electronic controller means including sensing means connected with said transistor means for sensing saturation of said transistor means indicative of the occurrence of . .a.!. .Iadd.one of the .Iaddend.predetermined condition . .variation.!. .Iadd.variations .Iaddend.capable of causing user discomfort while said output pulses are being provided, and, responsive thereto, said electronic controller means causing intensity compensation of said output pulses by causing the intensity .Iadd.level .Iaddend.of said output pulses to be quickly reduced to a predetermined intensity level and then, upon completion of said reduction, causing the intensity level of said output pulses to be gradually increased toward the intensity level of said output pulse existing immediately prior to sensing of the occurrence of said predetermined condition variation.   
     
     
       2. The device of claim 1 wherein said electronic controller means allows the intensity level of said output pulses to be gradually increased over a predetermined period of time .Iadd.toward said prior existing level .Iaddend.unless said electronic controller means senses the occurrence of . .a.!. .Iadd.one of the .Iaddend.predetermined condition . .variation.!. .Iadd.variations .Iaddend.capable of causing user discomfort during said predetermined time period of gradual increase of the intensity level of said output pulses. 
     
     
       3. The device of claim 1 wherein said electronic controller means includes micro-computer means for causing generation of said control pulses and for effecting said intensity compensation of said output pulses. 
     
     
       4. An electronic device for providing output pulses for therapeutic purposes, said device comprising: electronic controller means .Iadd.for .Iaddend.providing control pulses;   voltage supply means .Iadd.for .Iaddend.providing a voltage output;   pulse output means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses for therapeutic purposes having an intensity and .Iadd.a .Iaddend.pulse width . .subject to change due to the occurrence of predetermined condition variations.!..Iadd., said intensity being variable within a range of intensities, wherein the range of intensities has a maximum intensity that is based on the pulse width in a strength-duration curve relationship and wherein said intensity equals a variable percentage of the maximum intensity.Iaddend.;   pulse width control means for varying the .Iadd.pulse .Iaddend.width of said output pulses;   intensity percentage control means for varying the percentage of .Iadd.the maximum .Iaddend.intensity . .of.!. .Iadd.for .Iaddend.said output pulses; and   said electronic controller means including sensing means for sensing a predetermined condition variation . .establishing.!. .Iadd.that is indicative of .Iaddend.a change in the .Iadd.pulse .Iaddend.width of the output pulses . .by said pulse width control means.!., and, responsive thereto, causing a corresponding . .and predetermined.!. change in the range of intensities . .of said output pulses.!. based upon . .a.!. .Iadd.said .Iaddend.strength-duration curve . .applicable to said output pulses, said.!. .Iadd.and causing a .Iaddend.change in the . .range of intensities.!. .Iadd.intensity .Iaddend.of said output . .pulses being.!. .Iadd.pulse .Iaddend.in a manner such that .Iadd.the intensity of the output pulse is substantially maintained at .Iaddend.the percentage of .Iadd.the maximum .Iaddend.intensity as . .established.!. .Iadd.varied .Iaddend.by said intensity percentage control means . .is substantially maintained.!..   
     
     
       5. The device of claim 4 wherein .Iadd.each of said output pulses delivers a charge that has a resulting capability to stimulate nerve fiber, and .Iaddend.said electronic controller means causes said corresponding . .and predetermined.!. change in the range of intensities . .of said output pulses.!. to be such that .Iadd.the resulting capability to stimulate nerve fiber of .Iaddend.the charge . .delivered per pulse.!. of said output pulses is maintained substantially constant. 
     
     
       6. In an electronic device for providing output pulses .Iadd.having a variable intensity level .Iaddend.for therapeutic purposes and having output means for producing said pulses that includes a transistor with a drain .Iadd.having a drain voltage.Iaddend., output pulse compensation means comprising first means including sensing means connected with said output means for sensing the drain voltage of said transistor indicative of a change in at least one predetermined condition being then monitored and sample and hold means connected with said sensing means whereby said sample and hold means receives the sensed drain voltage of said transistor, and second means connected with said sample and hold means for causing a rapid decrease in the intensity level of said output pulses upon sensing of said change in at least one predetermined condition being then monitored, said second means, upon completion of said rapid decrease in intensity level, then causing the intensity level of said output pulses to be thereafter gradually increased over a predetermined time period toward the intensity level of said output pulses existing immediately prior to said rapid decrease. 
     
     
       7. The device of claim 6 wherein said compensation means causes said rapid decrease in the intensity level of said output pulses in response to a predetermined change condition capable of causing user discomfort or possible injury. 
     
     
       8. The device of claim 6 wherein said sample and hold means includes capacitor means for storing a voltage indicative of said sensed change in said predetermined condition being then monitored. 
     
     
       9. The device of claim 6 wherein said compensation means causes said gradual increase in the intensity level of said output pulses over a period of about two seconds. 
     
     
       10. An electronic device for providing output pulses for therapeutic purposes, said device comprising: electronic controller means .Iadd.for .Iaddend.providing control pulses;   voltage supply means for providing a voltage output;   pulse output means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses .Iadd.having an intensity level .Iaddend.for therapeutic purposes, said pulse output means including transistor means .Iadd.having a drain with a drain voltage.Iaddend.; and   said electronic controller means including sample and hold means connected with said transistor means for sensing the drain .Iadd.voltage .Iaddend.of said transistor means and capacitor means for storing a voltage indicative of said drain .Iadd.voltage.Iaddend., said electronic controller means receiving said voltage stored at said capacitor means and, responsive to . .a.!. .Iadd.an amount of .Iaddend.stored voltage indicative of the occurrence of a predetermined condition variation, causing intensity compensation of said output pulses by rapidly decreasing the intensity level of said output pulses and thereafter gradually increasing the intensity level of said output pulses over a predetermined period of time toward the intensity level of said output pulses existing immediately prior to said rapid decrease in intensity level.   
     
     
       11. The device of claim 10, wherein said transistor means is an analog control output transistor, and wherein said sample and hold means includes a gate transistor connected between said analog control output transistor and said capacitor means. 
     
     
       12. In an electronic device for providing . .a pulse.!. output . .signal.!. .Iadd.pulses .Iaddend.for therapeutic purposes . .with.!..Iadd., each of said output pulses having a pulse width and intensity, .Iaddend.said electronic device having pulse width control means for varying the pulse width of said . .pulse.!. output . .signal.!. .Iadd.pulses .Iaddend.and intensity . .percentage.!. control means for varying the . .percentage of.!. intensity of said output pulses, . .pulses.!. .Iadd.to produce a charge for each output pulse that has a resulting capacity to stimulate nerve fiber pulse .Iaddend.width compensation means comprising: .Iadd.intensity percentage control means for variably setting a percentage of a maximum intensity for the intensity of the output pulses, wherein said maximum intensity is defined by a strength-duration curve relationship between pulse width and intensity for nerve fiber stimulation capability such that there is a range of intensities limited by the maximum intensity for a pulse width; .Iaddend.   sensing means for sensing a change in the pulse width . .of said pulse output signal.!. by said pulse width control means and providing an output indicative thereof; and   electronic means for causing a change in the .Iadd.intensity and in the .Iaddend.range of intensities of said . .pulse.!. output . .signal.!. .Iadd.pulses .Iaddend.responsive to said output from said sensing means, with said change in the .Iadd.intensity and in the .Iaddend.range of intensities of said . .pulse.!. output . .signal.!. .Iadd.pulses .Iaddend.being in a manner such that .Iadd.the intensity of said output pulses is substantially maintained at .Iaddend.the percentage of .Iadd.maximum .Iaddend.intensity .Iadd.in the range of intensities .Iaddend.as . .established.!. .Iadd.varied .Iaddend.by said intensity percentage control means . .is substantially maintained.!., and with said change in the range of intensities of said pulse output signal being based upon . .a.!. .Iadd.the .Iaddend.strength-duration curve applicable to said . .delivered.!. .Iadd.output .Iaddend.pulses . .of said pulse output signal to thereby maintain.!. .Iadd.such that the resulting capability to stimulate nerve fiber of .Iaddend.the charge . .delivered per.!. .Iadd.for each .Iaddend.pulse . .of said pulse output signal.!. .Iadd.is maintained .Iaddend.substantially constant.   
     
     
       13. The pulse width compensation means of claim 12 wherein said electronic means of said pulse width compensation means is a part of a micro-computer controlled by a predetermined algorithm. 
     
     
       14. The pulse width compensation means of claim 13 wherein said electronic device is a TENS-type unit, and wherein said preselected algorithm follows a mathematical formula of I=19.6/(1-e.sup.(-0.00305×PW-0.0664)), where I is current and PW is pulse width. 
     
     
       15. An electronic device for providing output pulses for therapeutic purposes, .Iadd.each of which output pulses has a pulse width and intensity to produce a charge for each output pulse that has a resulting capability to stimulate nerve fiber, .Iaddend.said device comprising: pulse width control means .Iadd.for varying the pulse width of said output pulses, wherein the intensity of the output pulses is variable within a range of intensities, and wherein the range of intensities has a maximum intensity that is based on the pulse width in a strength-duration curve relationship.Iaddend.;   . .amplitude.!. .Iadd.intensity .Iaddend.percentage control means .Iadd.for varying the percentage of the maximum intensity for said output pulses.Iaddend.;   controller means connected with said pulse . .with.!. .Iadd.width .Iaddend.control means and said . .amplitude.!. .Iadd.intensity .Iaddend.percentage control means, said controller means providing control pulses.Iadd., .Iaddend.each . .pulse.!. of which .Iadd.control pulses .Iaddend.has a width and an . .amplitude.!. .Iadd.intensity .Iaddend.determined by said pulse width control means and said . .amplitude.!. .Iadd.intensity percentage .Iaddend.control means;   high voltage supply means for providing a high voltage output;   pulse output means for receiving said control pulses and said high voltage output and, responsive thereto, providing output pulses for therapeutic purposes; and   said controller means also providing pulse compensation for causing a change in the range of intensities . .of said output pulses.!. responsive to a variation in said pulse width of said output pulses . .effected by said pulse width control means.!., with said change in the range of intensities . .of said output pulses.!. being based upon . .a.!. .Iadd.said .Iaddend.strength-duration curve . .applicable to said delivered output pulses to thereby maintain.!. .Iadd.relationship such that the resulting capability to stimulate nerve fiber of .Iaddend.the charge . .delivered per pulse.!. .Iadd.for each .Iaddend.of said output pulses .Iadd.is maintained .Iaddend.substantially constant and . .with the.!. .Iadd.causing a .Iaddend.change in the range of intensities of said output pulses responsive to variation in pulse width . .being.!. in a manner such that .Iadd.the intensity of each output pulse is substantially maintained at .Iaddend.the percentage of .Iadd.the maximum .Iaddend.intensity . .established.!. .Iadd.as varied .Iaddend.by said . .amplitude.!. .Iadd.intensity .Iaddend.percentage control means . .is substantially maintained.!. so that the intensity . .level delivered.!. within said range of intensities is such that the . .delivered.!. charge .Iadd.that stimulates nerve fiber .Iaddend.remains unchanged by a change in .Iadd.pulse width by .Iaddend.said pulse width control means.   
     
     
       16. The device of claim 15 wherein said device provides output pulses to a plurality of output channels, and wherein said pulse compensation is provided for each of said output channels. 
     
     
       17. The device of claim 16 wherein said device includes a separate . .amplitude.!. .Iadd.intensity percentage .Iaddend.control means for each of said output channels, with each of said . .amplitude.!. .Iadd.intensity percentage .Iaddend.control means providing a separate percent of intensity control for each said channel. 
     
     
       18. A method for providing output pulses for therapeutic purposes, said method comprising: providing control pulses;   providing a voltage output;   providing an output .Iadd.means .Iaddend.having transistor means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses having an intensity .Iadd.level .Iaddend.and a pulse width subject to change due to the occurrence of predetermined condition variations;   sensing the occurrence of saturation of said transistor means indicative of . .a.!. .Iadd.one of the .Iaddend.predetermined condition . .variation.!. .Iadd.variations .Iaddend.capable of causing user discomfort while said output pulses are being provided; and   utilizing said sensed occurrence of said predetermined condition variation to cause intensity compensation of said output pulses by causing the intensity .Iadd.level .Iaddend.of said output pulses to be quickly reduced to a predetermined intensity level and then upon completion of said reduction, causing the intensity level of said output pulses to be gradually increased toward the intensity level of said output pulses existing prior to sensing of the occurrence of said predetermined condition variation.   
     
     
       19. The method of claim 18 wherein said method includes allowing the intensity level of said output pulses to be gradually increased over a predetermined period of time .Iadd.toward said prior existing level .Iaddend.unless the occurrence of . .a.!. .Iadd.one of the .Iaddend.predetermined condition . .variation.!. .Iadd.variations .Iaddend.capable of causing user discomfort is sensed during said predetermined time period of gradual increases of the intensity level of said output pulses. 
     
     
       20. A method for providing output pulses for therapeutic purposes, said method comprising: providing control pulses;   providing a voltage output;   receiving said control pulses and said voltage output and, responsive thereto, providing output pulses having an intensity and pulse width . .subject to change due to the occurrence of predetermined condition variations.!. .Iadd.that produces a charge that has a resulting capability to stimulate nerve fiber, said intensity being variable within a range of intensities, wherein the range of intensities has a maximum intensity that is based on the pulse width in a strength-duration curve relationship and wherein said intensity equals a variable percentage of the maximum intensity.Iaddend.;   . .providing pulse width control means for.!. varying the .Iadd.pulse .Iaddend.width of said output pulses;   . .providing intensity percentage control means for.!. varying the percentage of .Iadd.the maximum .Iaddend.intensity . .of.!. .Iadd.for .Iaddend.said output pulses; and   sensing of a predetermined condition variation . .established by varying.!. .Iadd.that is indicative of a variation in .Iaddend.the .Iadd.pulse .Iaddend.width of the output pulses . .by said pulse width control means.!., and responsive thereto, causing . .the.!. .Iadd.a .Iaddend.corresponding . .and predetermined.!. change in the range of intensities . .of said output pulses.!. based upon . .a.!. .Iadd.said .Iaddend.strength-duration curve . .applicable to said output pulses, said.!. .Iadd.and causing a .Iaddend.change in the . .range of intensities.!. .Iadd.intensity .Iaddend.of said output pulses . .being.!. in a manner such that .Iadd.the intensity of the output pulses are substantially maintained at .Iaddend.said percentage of .Iadd.the maximum .Iaddend.intensity as . .established.!. .Iadd.varied .Iaddend.by said intensity percentage control means . .is substantially maintained.!..   
     
     
       21. The method claim 20 . .wherein said provided pulse compensation causes.!. .Iadd.including to step of causing .Iaddend.said corresponding . .and predetermined.!. change in the range of intensities of said output . .pulse.!. .Iadd.pulses .Iaddend.to be such that .Iadd.the resulting capability to stimulate nerve fiber of .Iaddend.the charge . .delivered.!. per .Iadd.output .Iaddend.pulse . .of said output pulses.!. is maintained substantially constant. 
     
     
       22. A method for providing output pulse compensation in an electronic device providing output pulses .Iadd.having a variable intensity level .Iaddend.for therapeutic purposes and having output means that includes a transistor with a drain .Iadd.having a drain .Iaddend.voltage, said method comprising: providing sensing means for sensing the drain .Iadd.voltage .Iaddend.of said transistor of said output means indicative of a change in at least one predetermined condition being then monitored;   providing sample and hold means for receiving the sensed drain voltage of said transistor indicative of said change in said predetermined condition then being monitored; and   causing a rapid decrease in the intensity level of said output pulses upon sensing of said change in said predetermined condition and then, upon completion of said decrease of intensity level, gradually increasing the intensity level of said output pulses over a predetermined time period toward the intensity level of said output pulses existing immediately prior to said rapid decrease.   
     
     
       23. The device of claim 22 wherein said method includes causing said rapid decrease in the intensity level of said output pulses in response to a predetermined changed condition capable of causing user discomfort or possible injury. 
     
     
       24. The method of claim 22 wherein said gradual increase in the intensity level of said output pulses occurs over a period of about two seconds. 
     
     
       25. A method for providing pulse width compensation in an electronic device providing output pulses for therapeutic purposes, .Iadd.wherein each of the pulses has an intensity and a pulse width that produces a charge that has a resulting capability to stimulate nerve fiber, .Iaddend.said method comprising: establishing a percentage of .Iadd.maximum .Iaddend.intensity .Iadd.of the output pulses .Iaddend.within a range of intensities.Iadd., wherein the range of intensities has a maximum intensity that is based on the pulse width in a strength-duration curve relationship and wherein the intensity equals the established variable percentage of the maximum intensity.Iaddend.;   . .sensing.!. .Iadd.determining .Iaddend.a change in the .Iadd.pulse .Iaddend.width of the output pulses . .being then delivered.!.;   determining a new range of intensities .Iadd.with a new maximum .Iaddend.based upon . .a.!. .Iadd.said .Iaddend.strength-duration curve .Iadd.relationship .Iaddend.for said output pulses that corresponds to said change in pulse width; and   providing output pulses having changed pulse width with said output pulses having said established percentage of .Iadd.maximum .Iaddend.intensity within said . .then determined.!. range of intensities of said output pulses maintained . .to thereby also maintain.!. .Iadd.such that the resulting capability to stimulate nerve fiber of .Iaddend.the charge . .delivered per pulse.!. of said output pulses .Iadd.is maintained .Iaddend.substantially constant.   
     
     
       26. The method of claim 25 wherein said method includes changing the percentage of . .the amplitude.!. .Iadd.maximum intensity .Iaddend.of said delivered pulses independent of any said pulse width change of said delivered pulses. 
     
     
       27. The method of claim 25 wherein said electronic device is a TENS type unit, and wherein said change of said range of intensities follows the mathematical formula of I=19.6/(1-e.sup.(-0.00305×PW-0.0664)), where I is current and PW is pulse width.