Abstract: Electronic devices are typically coupled together to operate as systems that require the communication of data between two or more devices. Many of these devices includes a communications circuit, such as receiver, transmitter, or transceiver for this purpose. A typical component in these communication circuits is the phase-lock loop, a circuit that in receiver circuits determines the timing of pulses in a received data signal and in transmitter circuits clocks the data out at a predetermined rate. One problem with phase-lock loops and thus the receiver and transmitter circuits that incorporate them is that they are generally tuned, or tailored, to operate at a certain frequency. This means that one cannot generally use a receiver or transmitter circuit having phase-lock loops tuned for one frequency to communicate at another frequency. The inability to communicate at other frequencies limits the usefulness of not only the receiver and transmitter circuits but also their electronic devices.

Abstract: A two-wire industrial process control transmitter includes a sensor, at least two integrated circuits, and a level shift circuit. The first integrated circuit contains the analog measurement circuit that includes a sensor detection circuit and the analog portion of a digital-to-analog convertor. The second integrated circuit contains the digital system circuit that includes a modem and the digital portion of the analog-to-digital convertor. The first and second ICs may be powered at different voltage levels to maximize the power of the analog circuit and improve resolution. Alternatively, the ICs may be powered at the same voltage level, but the digital circuits are divided among several stacked dies to minimize the voltage for each digital circuit. In either case, the level shifting circuit shifts the voltage level between the analog and digital circuits.

Abstract: A mapping circuit coupled to the integrator circuit of a delta-sigma converter to map the analog input range of the integrator to the analog out-put range of the sensor. The integrator circuit provides an integrator output to a controller to generate a digital output, which is in a digital output range representing the analog input range. A sensor input circuit includes a sensor having an analog sensor output range. The mapping circuit is coupled to the integrator circuit and is responsive to control signals from the controller to map the analog input range of the integrator to the analog output range of the sensor.

Abstract: An illuminant discriminator distinguishes a range of separate illuminants, including high efficiency fluorescent lighting, by modifying the frequency response of a signal output from a photodetector. A switchable high pass filter coupled to the photodetector has a first filter section with a first cutoff characteristic selected to pass signal components due to various types of lighting including high efficiency lighting, and a second section with second cutoff characteristic that separates out the high efficiency components. The high pass output is processed by a log amplifier to develop flicker frequency harmonics that are distinguished as to source illuminant by comparator stages. Undersampling artifacts due to high efficiency lighting are present in the mixed illuminant spectrum when the first filter section is operative, and positively identified as high efficiency lighting when the second section is operative.

Abstract: A photodiode amplifier includes an input stage having a first pair of transistors connected as a differential pair to have a low input impedance and a current source connected into the input stage to bias the pair of transistors. A photodiode is connected into the input stage across the transistors so as to provide differential effect to current flowing through the transistors. By means of such connection, the photodiode is presented with low input impedance, its time constant is accordingly lowered, and the system response of the photodiode amplifier is extended into higher frequencies. The photodiode amplifier is of particular use in an illuminant discriminator capable of distinguishing a range of separate illuminants, including high efficiency fluorescent lighting within the passband of the photodiode amplifier.

Abstract: A line frequency is determined by interleaved sampling of ambient light to obtain analog voltage samples at predetermined sampling rates associated with two or more line frequencies. Where there are two line frequencies, one method separates the first samples by a time period at least equal to an analog-to-digital conversion time, and less than the earliest time when a sample associated with one line frequency would coincide with a sample from the other. There are n samples per flicker frequency period and Q samples for each line frequency are taken. In a second method, a first common sample is taken for all line frequencies, and a condition characterized by simultaneous samples for different line frequency sample groups triggers a common sample for all line frequencies. For both methods, digital sample values one through Q-1 for each group are operated on to obtain a result, and then two through Q are similarly operated on to obtain a second result.

Abstract: There are disclosed electronic imaging systems employing CCD imaging units and one or more unique analog signal processors (ASP's). Each ASP receives color-component image signals from the CCD unit and provides respective output image signals, such as red, green and blue color components, having proper white balance for combining into a full color image. The dark background or zero level of the output image signals is referenced to a common "dark" reference voltage to minimize dark background variations in the combined color image regardless of the gain setting of the ASP or ASP's. Each ASP is substantially identical and has a unique architecture which facilitates its implementation as an integrated circuit. The ASP has a dynamic range of substantially better than 8-bits and provides for a wide range of signal sample rates (e.g., 1 to 40 MHz).

Abstract: In a solid state image sensor, such as a CCD image sensor having lateral antiblooming protection, the level of which is controlled by an overflow gate voltage forming a barrier, the storage of electrons in the photodiode junction region of the sensor is eliminated by removing the barrier and allowing the charge to flow from the sensor's photodiode junctions into the overflow region. The charge flow is then detected as a function of the instantaneous light impinging on the photodiodes. The physical connections of the overflow gates are selected to form zones. Since the charge flow now represent the instantaneous light intensity, higher frequency components are detected than that limited by the sensor sampling rate. An amplifier is connected to sense the charge flow from each zone. With the range of light intensity being large the amplifier is provided with a logarithmic feed back element. This element provides compression of a signal representing the sensed charge flow.

Abstract: In the present invention there is provided a plurality of photosensitive elements arranged in a symmetrical pattern around a central circular area. The area surrounding the central area is formed of a square area having the circular area at its center with the square area divided into four equal quadrants. The next area is rectangular in shape and surrounds the second area. The rectangular area is formed in four equal sections with each of the corners of the square area lying along two adjacent edges of the rectangular areas. A selection means is provided for selecting the output signal from any one the photodiodes or for selecting the output signals from any combination of two or more of the photodiodes so as to accentuate the responsiveness of the light meter to a selected area or feature of the image to be photographed.

Abstract: The present invention is an apparatus and an associated method for determining the dominant scene illuminant which apparatus is more reliable and accurate than previous illuminant detectors. Mixed illuminant detection has been added to the choice of illuminant categories, to take care of the cases where one illuminant is not dominant and color correction is best handled by printing algorithms. A new boundary condition has been devised to eliminate detection errors seen when fluorescent illumination mixes with certain quantities of daylight causes a tungsten reading. The apparatus incorporates a thresholding technique to improve over existing art. The apparatus is comprised of a means for converting illuminate light into corresponding electrical signals. The electrical signals are then directed to a log amplifier wherein they are compressed to approximately form a signal having one term equal to the log of the DC term plus a ratio of the dominant AC components to the DC components.

Abstract: In the present invention a matrix array of organic electroluminescent storage display elements along with row and column selection circuitry are used to select the particular display elements within the matrix to be illuminated. Interposed between the column and row selection electronics are a plurality of memory cells receiving as inputs bit values that correspond to the desired intensity requested from a display element. The memory cells output activation signals which drive corresponding MOS switches each of which in turn is parallel connected as part of a current driver source feeding a single display element. Activation of one or more of the MOS switches provides a controlled amount of current to be applied to the display element to in turn provide a related amount of light from the display element.

Abstract: The present circuit is intended for use in providing CCD phase clocks. It has the benefit of reduced crossover currents which in turn reduces power consumption and device size requirements.The circuit is comprised of a pair of folded cascode CMOS amplifier input stages, a pair of bipolar output stages containing vertical NPN transistors, and 2 PMOS sense transistors for each output stage for reducing the crossover current which occurs when switching output stages. These sense transistors reduce the power consumption of the circuit and the size of the transistors necessary for the output.The input stage has the capability of operating from TTL or ECL signal inputs by selecting an input reference voltage. The folded cascode configuration also provides the level shifting necessary for inputs to the output stage's NPN transistors.

Abstract: The present invention is an apparatus for discriminating among various types of illuminants such as fluorescent light, tungsten light and natural daylight. The apparatus is comprised of an analog portion and a digital portion. The analog portion functions to convert incident light into a conditioned analog signal. The digital portion utilizes an analog-to-digital converter and a microprocessor to perform a Fourier series analysis on one or more of the harmonics of the illuminant signal. The microprocessor compares the amplitudes of the harmonics against the amplitudes of known illuminant sources to identify the source.