Abstract: A feedback cancellation system for a hearing aid or the like adapts a first filter in the feedback path that models the quickly varying portion of the hearing aid feedback path, and adapts a second filter in the feedback path that is used either as a reference filter for constrained adaptation or to model more slowly varying portions of the feedback path. The second filter is updated only when the hearing aid signals indicate that an accurate estimate of the feedback path can be obtained. Changes in the second filter are then monitored to detect changes in the hearing aid feedback path. The first filter is adaptively updated at least when the condition of the signal indicates that an accurate estimate of physical feedback cannot be made. It may be updated on a continuous or frequent basis.

Abstract: The present invention combines audio compression and feedback cancellation in an audio system such as a hearing aid. The feedback cancellation element of the present invention uses one or more filters to model the feedback path of the system and thereby subtract the expected feedback from the audio input signal before hearing aid processing occurs. The hearing aid processing includes audio compression, for example multiband compression. The operation of the audio compression element may be responsive to information gleaned from the feedback cancellation element, the feedback cancellation may be responsive to information gleaned from the compression element, or both.

Abstract: Apparatus for increasing color resolution and quality in digital imaging systems temporally modulates red, green and blue light, detects all three colors at each pixel, and band pass filters the detected light to extract values for red, green and blue at each pixel. A detector which preserves the modulation, such as a complementary metal oxide semiconductor detector is used. Alternatively, if an integrating detector array such as a charge coupled device (CCD) is used, the three illumination sources are switched on and off sequentially, and the detector array switches to different integrating circuits for each color. Measurement of the range provides full color, three-dimensional, image data.

Abstract: Circuitry is provided to compensate for distortion introduced into the output signal of a delta sigma digital to analog converter (DAC) by the power output stage of the amplifier. Such distortion is not consistent for a given output data value or short series of data values, but must be either measured and corrected in real time or must be corrected in real time based upon a sophisticated model of the system that predicts the distortion. Correction is applied to one or more feedback loops in the delta sigma converter. Distortion caused by fluctuations in the power supply voltage may also be modeled and corrected in real time.

Abstract: A micro-size LED-like optical element has an n-contact, a p-contact, and an optical active structure connected between the n-contact and the p-contact for generating light when forward biased and for detecting light when reverse biased. The optical active structure has a diameter of about 20 &mgr;m or smaller. When the the optical active structure is forward biased, it forms a micro-size LED (&mgr;LED). When the optical active structure is reverse biased, it forms a micro-size detector (&mgr;detector). An array of the micro-size optical active structures may be used as a minidisplay, a detector, or a sensor (when each structure is separately wired), or as a hyperbright LED (when the structures are wired to turn on and off simultaneously). Alternatively, a hyperbright LED may be obtained by forming a plurality of micro-size holes extending into an LED wafer.

Abstract: A multibit data converter has an output parallel unit element converter fed by a multibit signal, and noise shaping dynamic element matching (DEM) apparatus for selectively activating units in the converter. The DEM apparatus includes a plurality of noise shaping components. Each components has as an input one signal to the converter, and each includes a first integrator having as its input the input to the component, and a second integrator having as its input the output of the first integrator, and forms one or more component outputs. A signal in the second integrator is clipped. A vector quantizer orders the component outputs and activates converter elements according to the ordering.

Abstract: Distortion and noise in high power digital PWM amplifiers is reduced by measuring the difference between the desired output signal and the actual output signal on a pulse by pulse basis. This analog error is converted into a digital signal with an analog to digital converter (ADC). The digital error signal is then used to correct the feedback of the delta sigma modulator in real time. Preferably, more than one moment of the modulator signal is corrected via the feedback. Preferably, the predictable error of the circuitry which is known a priori is also corrected by correcting the delta sigma modulator feedback. A specialized ADC allows the loop delay to be low, without compromising accuracy.

Abstract: A tunable interference add/drop filter system combines an interference filter or the like with a mirror attached adjacent to the filter at an angle under 180° to form a reflector assembly. The reflector assembly is rotated to tune the filter system. The dropped output passes through the filter, while the passed output reflects off of the filter and the mirror. The direction of the passed output beam is a fixed angle from the input beam, and the beam is translated sideways by a fixed amount, no matter how much the reflector assembly is rotated. Thus the dropped output (or complementary output) can be retained. A null state switch prevents light from reaching the filter while the filter system is tuning.

Abstract: In a delta sigma analog to digital converter, generally comprising a noise shaping filter element fed into a multilevel quantizer, the output of which is the output of the delta sigma modulator and is also fed through a digital to analog converter array in a feedback loop to the noise shaping filter, dynamic element matching circuitry is included in the quantizer, in a reference path. The quantizer includes dynamic element matching circuitry for shaping the usage of the elements of the quantizer. Specifically, reference voltages are switched to specific comparators according to control signals from switch control circuitry.

Abstract: The digital amplifier of the present invention comprises a delta sigma noise shaper feeding a pulse wave modulator (PWM) which drives a load such as a speaker. The amplifier includes circuitry to measure the voltage coming out of the power supply in the circuit, and using this measurement as a control signal to modify the feedback path and direct path of the noise shaper, in order to correct the pulse width output to compensate for the varying power supply voltages. The amplifier may also include circuitry to correct for the nonlinear effects of pulse wave modulation, by correcting the feedback applied to one stage of the noise shaper such that it is nontrivially different from the feedback applied to another stage.

Abstract: A school organizer capable of magnetically attaching to a desk includes a main back portion, which is formed of a single piece of fabric, which is folded in half and sewn to form a top compartment for magnets, a main compartment for markers and paper, and a bottom compartment for pencils and the like. The fabric piece is folded up vertically and a vertical seam is sewn to form the main compartment. A snap holds the main compartment closed. Then the doubled fabric is folded upward again, toward the front, and two vertical seams are sewn along the sides to form the bottom compartment. Another snap is used to hold the bottom compartment closed. Four seams form a closed top compartment for holding the magnets in place. The organizer further includes a sewn on front pocket portion, which is formed of a single piece of cloth sewn to the front of the main portion. A bottom seam, together with a series of vertical seams, form several pockets between the front portion and the main portion.

Abstract: The present invention provides apparatus and methods which allow music synthesis and audio processing tasks to dynamically scale from a default processor to additional processors in a heterogeneous array of processors in a manner transparent to the user. A router running on one of the processors in the array knows or estimates the load on each processor, and dynamically allocates processing tasks based upon the current load on each processor and its capacity. Processing parameters are shared between all the audio processors to ensure that perceived audio quality is independent of where a task is running.

Abstract: Apparatus for adaptively reducing dead time in a switching circuit includes overlap detection circuitry for measuring the dead time/overlap of the switches, and control circuitry for setting the dead time to the optimum level (generally the minimum possible dead time without any overlap occurring). The dead time/overlap may be detected by measuring the current through the switches, the current into the power supply, the voltage waveform at the switch point, or the average voltage waveform at the switch point. The dead time may be controlled by utilizing delay elements prior to the drivers, or by utilizing circuitry to control the driver timing.

Abstract: A switching output stage for Class D amplifiers and the like utilizes a floating power supply providing a relative positive output voltage VP at a first line and a relative negative output voltage VM at a second line. Two switches are connected in parallel across the two lines. The first switch has a common to ground and switches between VP and VM, and the second switch has a common to a low pass output filter and switches between VP and VM. The input to the filter can take on three values, VP, VM, and 0. The input VP to the filter is achieved by switching the first switch to VM and the second switch to VP, and the input VM to the filter is achieved by switching the first switch to VP and the second switch to VM. The input 0 to the filter may be achieved by switching both the first switch and the second switch either to VP or to VM.

Abstract: A digital hearing aid applies clipping to the processed digital signal after at least part of the interpolation of the signal has occurred. The clipping may be incorporated into the output demodulation stage of the hearing aid. The final stages of interpolation may also be incorporated into the demodulation stage.

Abstract: A flow cytometer for detecting target particles such as microorganisms including biological cells and viruses as well as molecular species. The flow cytometer includes a detection system involving a CCD having a time delay integration capability to thereby increase the signal from the target particle and decrease the noise detected by the CCD. Calibration particles can be included in the sample stream of the flow cytometer for coordinating the readout of the CCD with the rate of flow of the sample stream to improve the detection capability of the CCD. Statistical analysis techniques can also be used to determine the rate of flow of target particles in the sample stream to thereby coordinate the readout rate of the CCD with the rate of flow of the target particles.

Abstract: A renewable energy flashlight comprises a housing and a barrel located within the housing. A wire coil wraps around the barrel, between the barrel and the housing. A magnet oscillates within the barrel when the flashlight is shaken, generating an alternating current in the coil. Two springs at either end of the barrel cause the magnet to recoil when the magnet strikes the springs. As an alternative, rebound magnets oriented to repel the charging magnet may be installed within the barrel at either end, to cause the magnet to recoil from the ends. An electronics assembly within the housing includes a capacitor for storing charge, a rectifier connected to the capacitor, and means for conducting current flowing in the coil to the rectifier, to charge the capacitor. An LED is connected to the capacitor by means of a switch, and lights up when the switch is switched on.

Abstract: Feedback cancellation apparatus uses a cascade of two filters along with a short bulk delay. The first filter is adapted when the hearing aid is turned on in the ear. This filter adapts quickly using a white noise probe signal, and then the filter coefficients are frozen. The first filter models parts of the hearing-aid feedback path that are essentially constant over the course of the day. The second filter adapts while the hearing aid is in use and does not use a separate probe signal. This filter provides a rapid correction to the feedback path model when the hearing aid goes unstable, and more slowly tracks perturbations in the feedback path that occur in daily use. The delay shifts the filter response to make the most effective use of the limited number of filter coefficients.

Abstract: The mechanism comprises a bracket, to which are mounted a fixed roller shaft and a rotatable brake shaft. The roller shaft has a roller which runs in the door track. A cylindrical torsion spring is positioned on the brake shaft. One end of the spring is anchored to the brake shaft. The other end of the spring is connected to a tensioning ring, so that the tension of the spring can be adjusted. The tensioning ring is disengagably secured to the bracket. An arm protrudes from the brake shaft. The lift cable for the door extends through an eye carried by the arm. As long as the cable is taut, the brake shaft is prevented from turning. At its outer end, the brake shaft carries a cam member with braking teeth. The teeth are positioned to bite into the exterior surface of the track if the cable breaks and the spring rotates the brake shaft.

Abstract: In a hearing aid having feedback cancellation, a voltage regulator is provided to regulate the voltage from the hearing aid battery to the class D output. Feedback cancellation processing dynamically models the entire acoustic feedback path from the hearing aid processing to microphone, including the gain of the output stage. The gain of the output stage varies with the voltage of the battery, and the battery voltage depresses when a loud signal is processed by hearing aid, so the voltage regulator prevents the output stage gain from varying with time.