Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-07-23
2001-07-24
Hirsch, Paul J. (Department: 3732)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C128SDIG001, C604S153000, C604S154000, C604S891100
Reexamination Certificate
active
06264634
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an implant-type chemical supply device that is implanted in a body, for gradually supplying chemicals to the affected part.
2. Description of the Related Art
An implant-type chemical supply device that supplies chemicals to the affected part is generally made up of a chemical tank, a pump unit, a drive control circuit for the pump unit, and a battery for operation of the device, and supplies the chemicals within the chemical tanks to the affected part through a tube.
The pump unit is structured in such a manner that a part of the tube connected to the chemical tank is U-shaped, and rollers on both ends of an actuating lever are in contact with the tube at a predetermined pressure. The actuating lever is rotationally driven by a step motor to extrude chemicals within the tube in the same direction, and the chemicals are supplied to the affected part by this pressure.
The step motor is driven in such a manner that a dividing signal obtained by sequentially dividing an oscillation signal from an oscillating circuit by a frequency dividing circuit is converted by a pulse synthesizing circuit into two signals which are, for example, 10 msec in pulse width, 62.5 msec in period and 31.25 msec in phase difference, whereby inversion pulses of a current whose flowing direction is changed every 31.25 msec are supplied to a coil of the step motor, and a rotor magnetized to two polarities is sequentially rotated every 180 degrees.
By the way, a drive pulse width (10 msec in the above example), a coil resistance, the number of winding of the coil, the dimensions of the respective portions of the step motor, etc., are designed in such a manner that the step motor can be driven stably even in any predicted circumstances with which the device may encounter. The predicted circumstances include a case in which at least only one roller is pressed for rotating while the roller is pressed against the tube, and a case in which at least two rollers are pressed against the tube. The rollers are redesigned as to rotate while the maximum number of rollers is pressed against the tube. Further, because the step motor is so designed as to be driven stably even if the circumstances such as the hardness of the tube, the viscosity of chemicals or the like are different, a drive pulse having an effective power of a certain level or more is supplied to the coil of the step motor even when a large output torque is not required.
Therefore, in the case where the step motor is low in load, a useless energy is supplied to the step motor from the battery, resulting in reduction of the lifetime of the battery.
SUMMARY OF THE INVENTION
The present invention has been made to solve the problems with the conventional device, and therefore an object of the present invention is to provide an implant-type chemical supply device in which a step motor is driven according to pulses corresponding to a load state of a pump unit that supplies chemicals, so that power consumption can be lowered to thereby elongate the lifetime of the battery.
In order to achieve the above object, according to the present invention, there is provided an implant-type chemical supply device, comprising: a supply tube for supplying chemicals from a chemical tank; a pump unit having an actuating lever which is rotated by a step motor and has rollers on both ends thereof so that the rollers are arranged in contact with the halfway of the supply tube, for extruding the chemicals within the supply tube by the rollers to supply the chemicals; a waveform synthesizing circuit for producing drive pulse groups each having a different effective power; a drive circuit for supplying any one of the drive pulse groups to the step motor in synchronism with a time signal; a detection circuit for generating a non-rotation signal when an induced voltage developed in the drive coil within the step motor by free oscillations of the step motor is equal to or less than a given value after the drive pulse is supplied to the step motor; and a control circuit for controlling the drive circuit so that the drive pulse having an effective power larger by one in magnitude than that of the drive pulse during non-rotation is supplied to the step motor when the non-rotation signal is generated, and the drive pulse having an effective power smaller by one in magnitude than that of the past drive pulse during non-rotation is supplied to the step motor when no non-rotation signal is generated for a predetermined period of time.
Also, according to the present invention, there is provided an implant-type chemical supply device, comprising: a supply tube a part of which is disposed in the form of an arc to form an arcuate portion; a pump unit for supplying chemicals from a chemical tank having an actuating lever which is rotated by a step motor and has rollers on both ends thereof so that the rollers are arranged to be in contact with the arcuate portion of the supply tube only in a range of predetermined angles when the actuating lever is rotated, for extruding the chemicals within the supply tube by the rollers to supply the chemicals; a waveform synthesizing circuit for producing drive pulse groups each having a different effective power; a drive circuit for supplying any one of the drive pulse groups to the step motor in synchronism with a time signal; a detection circuit for generating a non-rotation signal when an induced voltage developed in the drive coil within the step motor by free oscillations of the step motor is equal to or less than a given value after the drive pulse is supplied to the step motor; a timer circuit for outputting a light-load signal indicative of a period of time when the rollers are apart from the supply tube in response to the non-rotation signal; and a control circuit for controlling the drive circuit so that the drive pulse having a larger effective power is supplied to the step motor when no light-load signal is outputted, and the drive pulse having a smaller effective power is supplied to the step motor when the light-load signal is outputted.
In the case where any one of the drive pulse groups is supplied to the step motor, when the non-rotation signal is outputted, the drive pulse having the effective power larger by one. On the other hand, when no non-rotation signal is outputted, the drive pulse having the effective power smaller by one. As a result, the drive pulse having an appropriate effective power suited for the load of the step motor is outputted so that the step motor is operated with the minimum power consumption, thereby being capable of remarkably elongating the lifetime of the battery.
Also, in the structure in which the light-load signal is obtained by the timer circuit, since the drive pulse small in effective power and the drive pulse large in effective power are simply and surely changed over regardless of the presence/absence of the non-rotation signal, the effective power of the drive pulse can be properly changed according to a periodic change in the load of the actuating lever without being adversely affected by a noise signal or the like.
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patent: 4565600 (1986-01-01), Jeensalute et al.
patent: 4714462 (1987-12-01), DiDomenico
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patent: 5352201 (1994-10-01), Jemmott
patent: 5514103 (1996-05-01), Srisathapat et al.
patent: 5752930 (1998-05-01), Risk et al.
patent: 5814019 (1998-09-01), Steinbach et al.
Adams & Wilks
Hirsch Paul J.
Seiko Instruments Inc.
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