Abstract: A scan head for an ultrasound imaging device has a body that encloses a number of ultrasound transducers and controlling electronics. The electronics are sealed in the body of the scan head. The scan head has a fan that is configured to remove heat caused by the operation of the electronics. The motor is magnetically controlled and has controlling electronics that are sealed in the body of the scan head. In one embodiment, an airflow channel surrounds the electronics in the scan head and the fan is configured to move air through the airflow channel. In another embodiment, the electronics are thermally coupled to a heat exchanger heat via a conductive substrate and the fan is configured to move air over the heat exchanger.

Abstract: The use of power-efficient transmitters to establish acoustic wave energy having low undesirable harmonics is achieved by adjusting the transmitter output waveform to minimize the undesirable harmonics. In one embodiment, both the timing and slope of the waveform edges are adjusted to produce the desired output waveform having little or no second harmonics. In the embodiment, output waveform timing adjustments on the order of fractions of the system clock interval are provided. This then allows for very fine control of a coarsely produced waveform. In one embodiment, the user can select the fine tuning to match the transmitter output signal to a particular load transducer.

Abstract: A scan head for an ultrasound imaging device has a body that encloses a number of ultrasound transducers and controlling electronics. The electronics are sealed in the body of the scan head. The scan head has a fan that is configured to remove heat caused by the operation of the electronics. The motor is magnetically controlled and has controlling electronics that are sealed in the body of the scan head. In one embodiment, an airflow channel surrounds the electronics in the scan head and the fan is configured to move air through the airflow channel. In another embodiment, the electronics are thermally coupled to a heat exchanger heat via a conductive substrate and the fan is configured to move air over the heat exchanger.

Abstract: The use of power-efficient transmitters to establish acoustic wave energy having low undesirable harmonics is achieved by adjusting the transmitter output waveform to minimize the undesirable harmonics. In one embodiment both the timing and slope of the waveform edges are adjusted to produce the desired output waveform having little or no second harmonics. In the embodiment, output waveform timing adjustments on the order of fractions of the system clock interval are provided. This then allows for very fine control of a coarsely produced waveform. In one embodiment, the user can select the fine tuning to match the transmitter output signal to a particular load transducer.

Abstract: The use of power-efficient transmitters to establish acoustic wave energy having low undesirable harmonics is achieved by adjusting the transmitter output waveform to minimize the undesirable harmonics. In one embodiment, both the timing and slope of the waveform edges are adjusted to produce the desired output waveform having little or no second harmonics. In the embodiment, output waveform timing adjustments on the order of fractions of the system clock interval are provided. This then allows for very fine control of a coarsely produced waveform. In one embodiment, the user can select the fine tuning to match the transmitter output signal to a particular load transducer.

Abstract: An analog to digital converter for input signals having a low frequency component (such as DC) upon which is superimposed an AC component, the magnitude of the AC component being less than or equal to one-half the span of the analog to digital converter.

Abstract: An analog to digital converter for input signals having a low frequency component (such as DC) upon which is superimposed an AC component, the magnitude of the AC component being less than or equal to one-half the span of the analog to digital converter.

Abstract: A method and apparatus for monitoring an electrocardiograph waveform, and for returning an electrocardiograph trace to the middle of a display, such as a chart recorder strip. The monitoring circuit includes an amplifier and a switch for switching the frequency response curve of the monitoring circuit. In a first position, the switch causes the monitoring circuit to have a slow frequency response curve, which allows for accurate monitoring of ECG waveforms. In a second position, the switch causes the monitoring circuit to have a fast frequency response curve, which allows the amplifier of the monitoring circuit to quickly be brought out of saturation. The amplifier of the monitoring circuit becomes saturated when a defibrillation or pace pulse has been applied to a patient who is being monitored. The switch is controlled by a pulse waveform control signal that is provided by a microprocessor.

Abstract: A differential lead impedance comparison apparatus (10) senses lead impedance and compensates for patient-to-patient and electrode variability. A bridge circuit (12) is connected to one end of electrode conductors (22, 24 and 26) in an ECG Leads I configuration. The other end of the conductors (22, 24 and 26) are connected to a patient (18) via electrodes (RA, LA and LL). Leads formed in part by RA, LA and LL and the respective conductors (22, 24 and 26) have lead impedances (R.sub.b, R.sub.a, and R.sub.c). Constant current sources (11, 12 and 13) are connected to the conductors (22, 24 and 26) and supply constant AC currents (I.sub.1, I.sub.2 and I.sub.3). A first bridge output voltage (V.sub.M) is produced by I.sub.1 and a combination 32 of R.sub.a, R.sub.b, and R.sub.c. A second bridge output voltage (V.sub.P) is produced by I.sub.2 and a combination 34 of R.sub.a, R.sub.b, and R.sub.c. A differential amplifier circuit (14) differentially amplifies the V.sub.M and V.sub.

Abstract: A differential lead impedance comparison apparatus (10) senses lead impedance and compensates for patient-to-patient and electrode variability. A bridge circuit (12) is connected to one end of electrode conductors (22, 24 and 26) in an ECG Leads I configuration. The other end of the conductors (22, 24 and 26) are connected to a patient (18) via electrodes (RA, LA and LL). Leads formed in part by RA, LA and LL and the respective conductors (22, 24 and 26) have lead impedances (R.sub.b, R.sub.a, and R.sub.c). Constant current sources (I1, I2 and I3) are connected to the conductors (22, 24, and 26) and supply constant AC currents (I.sub.1, I.sub.2 and I.sub.3). A first bridge output voltage (V.sub.M) is produced by I.sub.1 and a combination 32 of R.sub.a, R.sub.b, and R.sub.c. A second bridge output voltage (V.sub.P) is produced by I.sub.2 and a combination 34 of R.sub.a, R.sub.b, and R.sub.c. A differential amplifier circuit (14) differentially amplifies the V.sub.M and V.sub.