Abstract: An operator adjusted lateral gain control (LGC) structure for an ultrasound imaging system, which may already include an operator adjusted time gain compensation (TGC) gain control structure. The LGC structure enables an operator to adjust the gain of one or more scan lines independently of the gain of at least one other scan line, said gain as a result of the LGC control being substantially constant along said one or more scan lines.

Abstract: A transducer assembly, suitable for medical examinations, for generating an apodized sector shaped beam of energy. A transducer in the form of a crystal, has a ring-like structure on its face which apodizes the signal produced by the transducer by providing a greater amount of attenuation at the transducer's periphery than at the transducer's center.

Abstract: A constant power circuit for causing a constant power level to be dissipated by a load when an overpower condition is detected. The overpower condition is detected by measuring the voltage across and current drawn by the load in accordance with a programmed load value and determining whether the sum of the measured current and voltage exceeds the power limit for the load. In a preferred embodiment, the sum of the voltage and current is compared to a linear piecewise approximation of a constant power curve in the current-voltage plane, the curve representing the power limit for the load for the range of current and voltage magnitudes in which the load circuit may safely operate. When an overpower condition is detected, the power is dissipated by the load at a constant power level defined by the constant power limit by oscillating the power level within a hysteresis band about the constant power limit.

Abstract: Disclosed herein is a method of labeling room temperature vulcanizable silicon polymers at the "T" junction branch points by utilizing cross-linkers of the formula D-SiX.sub.3, wherein X is a leaving group and D is a complex organic molecule useful as a dye, fluorophore, or indicator.

Abstract: This invention provides an improved circuit for dynamically controlling a predetermined characteristic of each input channel of a system having a plurality of input channels to achieve a desired characteristic profile with predetermined time variances in channel aperture size and/or focal point depth. More particularly, the invention dynamically controls the gain of each input channel to maintain a desired apodization profile. A plurality of basic time varying functions (basis functions) are generated, such functions being, for example, a constant, a ramp, a parabola an exponential or the like, and at least selected ones of the basis functions are combined by appropriately weighting the functions and adding the weighted functions to obtain a desired control signal. The control signal which has the desired dynamic gain characteristic for the given channel is then applied to control a gain-controllable amplifier for such channel.

Abstract: A method and apparatus are provided for gain control in a Doppler or other scan system which projects a plurality of scan lines at a given angle to determine velocity of movement of a predetermined medium at the angle. A training line is generated at the angle of the scan lines, the training line being utilized to determine portions of the scan line which are in a flow medium of interest, such as blood, and portions of the scan line which are in clutter. Information from the training line is then utilized to control the gain of the scan lines so that the gain is substantially maximized when scan lines are in the flow medium, while being reduced so as not to saturate the system in general, and A/D converters in particular, when in clutter. When an image line is utilized in the system, this line may also function as the training line.

Abstract: A power supply control circuit which enables the constant current and constant voltage feedback loops to be compensated independent of each other. In accordance with the invention, an inner feedback loop has been added which is local to the output stage so as to allow a constant voltage feedback loop to see a closed loop transfer function of the inner feedback loop that mimics an output for a constant voltage preferred output stage even though a constant current preferred output stage is used. As a result, load impedance variations that would have affected the loop gain of the constant voltage feedback loop affect the loop gain of the inner feedback loop only. The inner feedback loop is disposed such that it is automatically disabled by the constant current feedback loop when the power supply enters the constant current mode and hence allows the constant current and constant voltage modes to be decoupled from one another.

Abstract: A circuit for heartbeat detection derives the heartbeat frquency from ultrasonic signals reflected from the heart and frequency-shifted due to the Doppler effect. The circuit allows for the automatic determination of the distance between the heart and an ultrasonic transducer located on the body of the patient, so that the evaluation of the reflected ultrasonic signals can be limited to a small body range and spurious signals from other ranges can be suppressed. The circuit comprises at least two channels which are enabled by a transmitting/receiving control circuit during receiving intervals for receiving and further processing the reflected ultrasonic signals. The receiving intervals of the different channels are time shifted toward one another so that the respectively received ultrasonic signals originate from different depth ranges within the body.

Abstract: This invention provides a method and apparatus for controlling the type of information displayed at each display pixel on the video monitor of a video display system. A number of video RAMs are provided which number is at least equal to the number of different types of information. A bitmap is stored for each type of information in the video RAMs in interspersed fashion, a selected number of bits for select display pixels of the bitmap for a given type of information being simultaneously stored in said RAMs, followed for each RAM by the selected number of bits for the same selected display pixels for the bitmap of at least one other information type. No more than one bitmap bit for a given display pixel is stored in any video RAM. The addressing of the RAMs for read out of the bitmap is shifted so that bits for the same display pixels for all of the bitmaps are simultaneously read out from the RAMs.

Abstract: Apparatus for calculating the delay coefficients to be used for the transducer of a linear array at successive focal points along each radial line of a sector along which ultrasonic pulses are transmitted comprising a plurality of clocked accumulators connected in series, the accumulators being preloaded with appropriate combination of the coefficients of the successive terms of a series expressing an approximation of the formula, D=R-.sqroot.(X-Xo).sup.2 +Yo.sup.2 where R is the distance of a focal point from a given point in the sector, X is the number of the accumulator from the origin and Xo, Yo are the coordinates of the focal point.

Abstract: This invention provides a method for fabricating ultrasonic transducer arrays and various transducer arrays produced utilizing such methods. The method includes the steps of cutting a block of piezoelectric material to form a plurality of wafers, each wafer being of a predetermined thickness; forming the wafers into a spaced parallel array with a center-to-center spacing between the wafers substantially equal to one-half of the object wavelength (as this term is defined in the specification); and causing the space between the wafers to be filled with a substance having an acoustic impedance which differs from that of the piezoelectric material by an amount such that the reflection coefficient between the piezoelectric material and the substance is greater than 0.9. The predetermined thickness of the wafers may be equal to one-half the piezoelectric wavelength and the substance between the wafers may be formed at least mostly of air.

Abstract: Disclosed is a process for the preparation of a composite including a room temperature vulcanizing silicone rubber and a chemically resistant polyester film which may be polyethylene terephthalate. The composite has particular utility as a part of medical equipment, for example as a component in an ultrasonic transducer. The susceptibility of the composite bond so formed to chemical challenge in the user environment is reduced or eliminated.

Abstract: This invention relates to a method and apparatus for automatically controlling scan line direction in a linear array ultrasonic Doppler scanning system. More particularly, this system determines an ideal scan line angle and point of origin for a given sample volume having fluid flow in a given direction. The system then determines left and right limiting angles for the given sample volume taking into account the geometry of the viewing area relative to the sample volume and the maximum steering angle of the transducers of the transducer array being utilized. Where, because of pulse repetition rate considerations, a maximum depth from the sampling aperture of the linear array to the sample volume exists, this maximum depth is also taken into account in determining the limiting angles.

Abstract: The intensity profile of an ultrasound beam in an ultrasound imaging system is adjusted by driving the individual piezoelectric crystals with drive signals having adjustable pulse durations. The duration of the drive pulse determines the frequency spectrum of the pulse and therefore determines the amplitude of the emitted ultrasound wave. The pulse durations may be selected such as to compose a desired profile of the ultrasound beam.

Abstract: The median value of data values at the intersections of each of a plurality of coordinates of one type with a plurality of coordinates of another type are respectively derived and the median of the data values thus selected is used as the display value at any of the intersections.

Abstract: This invention provides an ultrasonic transducer system which utilizes a reconfigurable delay line to perform a variety of processing functions. In particular, for a preferred embodiment, the delay line utilized to sum the outputs of transducer elements is reconfigurable to provide serial processing of image scan lines while providing parallel processing of Doppler color flow scan lines. More particularly, the echo signals generated in response to the packet of color flow lines utilized to generate color flow information are applied in a predetermined way to two separate portions of the delay line, the portions of the delay line having different delay profiles, the resulting outputs being focussed to slightly different points in the image and thus providing color flow packets for two separate points in response to the transmission of a single packet of color flow lines. This results in a substantial enhancement of the system frame rate.

Abstract: Signs or indicia are printed or otherwise formed at locations on the last portion of a recording strip that indicate the amount of recording that can occur after each location. The indication can be in the number of pages, length of paper or time.

Abstract: This invention relates to a circuit for detecting the phase of an AC signal of frequency f. The signal is applied to two mixers one of which mixes the AC signal with a first signal of frequency f to generate a signal I and the other of which mixes the AC signal with a second signal of frequency f which is 90 degrees out of phase with the first signal to generate a signal Q. The I and Q signals are digitized and the log of the absolute value of each of the digitized signals is generated. The log generating function may for example be performed with a table-look-up memory. One log value, for example log I, is substracted from the other log value and the Arctan of the antilog of this difference is then generated. The Arctan function may also be generated using a table-look-up memory. The resulting Arctan value is indicative of the phase of the AC signal.

Abstract: Probes, preferably optical probes for the invasive measurement of blood parameters consist of a plurality of sensors (or at least one sensor and a stabilizing core, or at least one single sensor), (11,17), each of these sensors (11,17) having a diffusion zone with a selective membrane (15) and all together surrounded by a stabilizing sheath (18); this sheath (18) is to be fastened on the sensor(s) (11,17) by a glue (22). A method is described for manufacturing such probes. This method includes the steps of covering the selective membrane (15) by a hardenable and soluble cover material (21), in particular a silicate, then fastening said sheath (18) on the sensors (11,17) by glue (22)--which cannot reach the selective membranes (15) as they are just covered by the cover material (21)--and then dissolving said cover material (21). This method guarantees that the selective membranes (15) are free of glue (22) after the manufacturing process.

Abstract: Circuitry for reducing side to side jitter in an ultrasound imaging system using a transducer which is mechanically scanned back and forth to cover the area to be imaged. The circuitry includes a filter circuit for providing a correction signal to be added to the transducer position signal. The filter circuit provides a phase lead proportional to the rate of change of the transducer movement. This signal is scaled by a factor which varies linearly as the depth being imaged changes. The correction signal compensates for delays through the transducer positioning and driver circuitry and for depth dependant delays resulting from the movement of the transducer during the scanning operation.