Abstract: An implantable infusion pump possesses operational functionality that is, at least in part, controlled by software operating in two processor ICs which are configured to perform some different and some duplicate functions. The pump exchanges messages with an external device via telemetry. Each processor controls a different part of the drug infusion mechanism such that both processors must agree on the appropriateness of drug delivery for infusion to occur. Delivery accumulators are incremented and decremented with delivery requests and with deliveries made. When accumulated amounts reach or exceed, quantized deliverable amounts, infusion is made to occur. The accumulators are capable of being incremented by two or more independent types of delivery requests. Operational modes of the infusion device are changed automatically in view of various system errors that are trapped, various system alarm conditions that are detected, and when excess periods of time lapse between pump and external device interactions.

Abstract: An implantable cardiac stimulation device includes a system for detecting noise in an electrogram signal. The system for detecting noise generates an event signal when the electrogram signal exceeds a threshold. A timer times a refractory time period responsive to an event signal. During the refractory time period, a zero crossing detector generates a zero crossing signal when the electrogram signal transitions between positive and negative values. A counter counts the zero crossing signals during the time period and a comparator determines if the counter reached a predetermined count during the time period. If the counter exceeds a programmable count, a noise detection flag is set and the controller is alerted to the presence of noise in its input signal.

Abstract: A shapeable, weather-resistant anti-slip panel has a cut-resistant anti-slip coating on a rigid substrate and a pattern of cuttable lines; this enables the panel to be shaped by cutting the substrate along selected lines and overcomes the problem with known weather resistant anti-slip panels that the anti-slip coating particles, being very hard, make the anti-slip coating very difficult to cut or drill, as the coating readily and speedily blunts cutting tools.

Abstract: A collapsible protective plant cover comprises a pair of vertically spaced and coaxial support rings of spring steel. A tubular wall made of highly flexible sheeting is connected between the rings for protection from weather and animals. The tubular wall is sized for surrounding a plant with sufficient spacing therefrom. The top ring is spanned by a flexible top sheet. A small handle is attached across a small central hole on the top sheet. A stake is inserted into the ground near the center of the plant. The handle is supported on a hook positioned above the plant on the stake. The cover is entirely supported by the stake. The cover is easily removed from the plant and collapsed by twisting and coiling the rings on themselves. In a second embodiment, the top sheet is removable, and the tubular wall is supported on the stake by a pair of cords attached to the top ring.

Abstract: An adaptable plant protector includes a flexible shield and a pair of bendable supporting rods. The shield is comprised of a springy frame spanned by a flexible sheet, and rings attached around the sheet. The shield is supported over a plant by inserting the top ends of the rods through the rings, and the bottom ends into the ground. Each rod is provided with a stop at an intermediate position for supporting the shield off the ground. The rods may be positioned closer together for holding the shield in an arc shape, or farther apart for holding it flat. The rods can also be bent to support the shield in many different shapes and positions for protecting plants in a variety of landscaping and horticultural situations. Gardening staples may be used instead of the rods for attaching edges of the shield directly to the ground in some situations. In a second embodiment, the shield is comprised of a springy frame spanned by a coarse mesh. The bendable rods are inserted directly through the coarse mesh.

Abstract: A pool or spa sterilizing device is provided including a housing having an interior space. An ultra-violet tube is positioned in the interior space of the housing and is adapted to emit ultra-violet radiation upon the receipt of power. A power cord is included having a first end with a standard grounded power plug for being releasably connected with an alternating current receptacle and a second end electrically connected to the ultra-violet tube. As such, power is supplied to the ultra-violet tube upon the plug of the power cord being plugged into the current receptacle.

Abstract: Circuitry for reducing charge injection effects in an offset voltage compensation circuit for a switched-capacitor amplifier is provided. The switched-capacitor amplifier circuitry includes an operational amplifier having inverting and noninverting inputs and an output. An initialization circuit provides the inverting input with a voltage close to the offset voltage of the operational amplifier. A feedback circuit ensures that the voltage at the inverting input attains the offset voltage. In order to attenuate the effects of disengaging the feedback circuit after the input voltage attains the offset voltage, an attenuation circuit is provided. The attenuation circuit prevents the voltage at the inverting input from being affected by charge injection effects that arise when the feedback circuit is disengaged. The offset voltage compensation circuit may be used with switched-capacitor amplifiers configured as comparators, amplifiers, or successive approximation A/D converters.

Abstract: An implantable stimulation device has a sensing amplifier circuit for amplifying low amplitude cardiac signals, while maintaining low power, to produce an output signal having a low noise level. The sense amplifier circuit includes a two-stage amplifier, a bandpass filter, and a threshold detector. The first stage comprises a linear differential amplifier which has low gain, good common mode rejection, and a current consumption proportional to the gain. The second stage is a switched-capacitor amplifier which has a programmable gain and low current consumption. The noise content of the system is low and produced substantially entirely in the switched-capacitor amplifier.

Abstract: A system and method for measuring and storing parametric data pertaining to the operating characteristics of an implantable medical device are provided. The parametric data may include the impedance of a lead that is attached to a patient's heart, and the internal impedance of a battery used to power the implantable medical device. The parametric data may be measured and stored at predetermined time intervals, as indicated by a clock provided within the implantable medical device. In addition, the parametric data measurements may be synchronized with the occurrence of a cardiac event, such as the application of a stimulation pulse to the patient's heart. A plurality of measurements for each type of parametric data may be stored, so that when the parametric data are later retrieved and displayed on an external programmer/analyzer, trends in the data can be readily observed.

Abstract: During the telemetering of telemetry signals between an implantable medical device and an external programmer, the transmitter power of the implantable device is dynamically adjusted. The programmer measures the strength of the telemetry signals transmitted by the implantable device. A power control signal is generated as a function of the measured signal strength, and the transmitter power of the implantable device is set to a power level specified by the power control signal. For example, if the measured signal strength falls below a predetermined minimum signal strength threshold, power must be increased. This process is repeated until the measured signal strength satisfies a predetermined signal strength condition.

Abstract: A switched-capacitor, band-pass, programmable amplifier is used as a sense amplifier in an implantable cardiac pacemaker. Switching means are used to switchably connect various capacitors to the same amplifier circuits. Clock generator means are used to generate clock signals that are used to control the rate at which the switching means operates. By programmably selecting the switching rate to be a desired value, the band-pass characteristics and gain of the sense amplifier may be varied. When a pacemaker stimulation pulse occurs, the band-pass characteristics and/or gain of the sense amplifier, may also be automatically varied to improve amplifier recovery time. The rate at which the capacitors are switchably connected to the amplifier circuits, may be selected remotely, thereby allowing the band-pass characteristics to be programmable.

Abstract: A protected output switch for an implantable medical device, such as a pacemaker, is disclosed. Through this output switch, a stimulation pulse is delivered from an internal storage element to an output terminal. The output switch includes a first N-channel MOSFET switch having its source terminal connected to the internal storage element and its drain terminal connected to the output terminal. The gate terminal of the N-channel MOSFET switches is connected to approriate logic switching signals. Included as part of the output switch is a second N-channel MOSFET switch having its source terminal connected to the P-well terminal of the first N-channel MOSFET switch, its drain terminal connected to the internal storage element, and its gate terminal connected to the output terminal. This second switch serves to block any potentials, whether internal or external, from being applied to the base of a parasitic NPN bipolar transistor that exists within the output switch.

Abstract: An implantable AM receiver having a variable threshold which can detect signals above a changing noise level. An AM receiver is provided which provides a modulation envelope corresponding to the amplitude of a pulse-modulated RF signal radiated by an external device. A voltage signal is developed which is at least equal to the amplitude of the modulation envelope, but which decays at a predetermined rate if the modulation envelope drops to a value below the voltage signal. The voltage signal is then scaled to a predetermined percentage of a value corresponding to the value of the modulation envelope, and biased so that it cannot drop below a predetermined minimum level. The scaled voltage signal comprises the variable threshold and is compared by a comparator to the modulation envelope. If it is below the modulation envelope, the comparator outputs a voltage having a first state; if it is above the modulation envelope, the comparator outputs a voltage having a second state.