Abstract:
A timing circuit establishes pulse repetition rate and pulse width and cooperates with a pulse generating output circuit which delivers to an organ a series of stimulating pulses at one of several available pulse energy levels. Low voltage d-c sources are used for driving the timing and output circuits. The output circuit is adapted to selectively double or triple the source voltage and raise the output pulse amplitude to above the response threshold of the organ with an adequate margin of safety. Interaction between the pulse timing and output circuits is minimized. An externally operable magnetic reed switch is used to transfer the stimulus pulse generator from the doubler to the tripler mode.
Abstract:
A cooking appliance for inductively heating a cooking utensil comprises a flat induction heating coil mounted beneath a nonmetallic support with a substantially unbroken utensil supporting surface. The induction heating coil is driven with an ultrasonic frequency wave generated by a static power conversion circuit typically formed of a rectifier and an inverter. The inverter is a series capacitor commutated sine wave inverter with a variable output frequency, variable input voltage, or variable commutating components to adjust the utensil heating level. The inverter is also controlled in on-off mode by a utensil temperature sensor.
Abstract:
An implantable body organ stimulator such as an electronic cardiac pacer has a magnetic reed switch and a switch operator embedded in its encapsulation. The state of the reed switch may be changed to alter any one of several functional characteristics of the stimulator with a switch operator which controls the operating state. The operator comprises a magnet which is movable between two positions in a guide tube which is adjacent the reed switch. The magnet may be urged from one position to another with a needle that enters the interior of the guide tube through an aperture in a plate that is embedded in the encapsulation. Means are provided in one embodiment for preventing restoration of the magnet to its original position.
Abstract:
The output circuit of an electric stimulator is connected to an organ such as the heart through a coupling capacitor. A semiconductor switch is triggered with a short pulse so that it partly discharges the capacitor and stimulates the organ. Immediately following the turn off of the first switch, a second switch is activated to recharge the capacitor to its initial state during which time reverse current is delivered momentarily to the heart. In one embodiment, after the first switch turns off to terminate the discharge of the capacitor which stimulates the heart, the current through the heart is reversed immediately by recharging the capacitor through a diode which is connected to a supply line and is in series with the capacitor and the heart. Turn-off of the first switch starts the diode conducting heavily. A high input impedance detector determines whether there is a natural electric signal on the organ and turns on a generator which provides the trigger pulse if there is no natural signal. The circuit is arranged so that the detector and output circuit present a high impedance to the organ.
Abstract:
Paralleled sets of batteries are used to supply power to an implantable electric organ stimulator stimulus signal generator. Each set has a device having the characteristics of a diode connected in series with it. The diodes have different forward voltage characteristics. One preferred set of batteries supplies current initially and the others do not deliver current unless the preferred battery is near depletion or unless there is a high current drain from the batteries. In one embodiment, a mild but perceptible physical sensation is produced to warn a patient of impending battery depletion.
Abstract:
A body organ stimulator such as an electronic cardiac stimulator has the customary connector for attaching intra-cardiac catheter leads or myocardial leads to operate the stimulator in a bipolar mode. Set in the resin encapsulation of the stimulator or in an adapter is an indifferent electrode plate which connects internally of the device with one of the connector terminals. The plate in the stimulator or the adapter is dipped in medical grade silicone sealant. An insulating label or strip is then superposed over the sealant coated plate and it is dipped and cured again. At the time of implantation, the physician has the option of stripping the label to expose the plate so the stimulator may be operated in the unipolar mode or leave the strip in place for operation in the bipolar mode.
Abstract:
The pacing pulse rate of a body implanted standby heart pacer is selectively controlled with a remote rate control device. The pacer has a coil which transmits a signal to the device whenever a natural heartbeat occurs or when an artificial stimulus is delivered to the heart. The same coil receives signals from the remote control device, and, if these signals are faster than the set rate of the pacer, the remote rate control will establish the rate of the pacer. The pacer paces the heart, when it requires artificial stimulation, at whatever rate the remote control is set. Signals radiated from the pacer are sensed by the remote rate control and are used to inhibit the remote transmitter for a specific period after each natural beat so there can be no competition between natural and artificial heart stimuli.