Special Photocell Or Electron Tube Circuits Patents (Class 250/214R)
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Patent number: 5340980Abstract: A microwave oscillator is shown to include an oscillator having an output and a control port and a feedback circuit disposed between the output and the control port of the oscillator. The feedback circuit includes a modulated laser, having an input and an output, the input responsive to a portion of a signal from the output of the oscillator and a photo detector having an input and an output, the input of the photo detector responsive to a signal from the output of the modulated laser delayed by a predetermined amount of time. The feedback circuit further includes a detector having a first and a second input and an output, the first input of the detector responsive to a signal from the output of the photo detector, the second input responsive to a portion of the signal from the output of the oscillator shifted in phase to be in phase quadrature with the signal at the first input of the detector and the output of the detector coupled to the control port of the oscillator.Type: GrantFiled: December 31, 1992Date of Patent: August 23, 1994Assignee: Raytheon CompanyInventors: Michael J. Bianchini, Richard A. Michalik, John A. Chiesa, Joanne Mistler
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Patent number: 5329111Abstract: An image input device photoelectrically reads a document and outputs digital data. This image reader includes a first voltage generating circuit for generating a first voltage for setting an upper limit of contrast, a second voltage generating circuit for generating a second voltage for setting a lower limit of contrast, and an A/D converter for converting an input analog signal to a digital signal in accordance with the first and second voltages. At least one of the voltages generated by the first voltage generating circuit and second voltage generating circuit is variable.Type: GrantFiled: June 26, 1992Date of Patent: July 12, 1994Assignee: Omron CorporationInventors: Shinya Sonoda, Atsushi Noda, Hiroki Tabata, Masashi Sugimoto, Junji Hiraishi
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Patent number: 5329115Abstract: An optical receiver circuit for receiving optical signals is described incorporating a photodetector, two coupling capacitors for coupling each side of the photodetector to respective inputs of a transimpedance amplifier, two current mirror circuits for detecting current on each side of the coupling capacitor and injecting equivalent current to the other side of the other capacitor which is at the input of the transimpedance amplifier, two low pass filters, two current sources and a transimpedance amplifier having two inputs. An optical receiver for receiving optical signals is described incorporating a photodetector having one side coupled to a reference voltage, a current source, a coupling capacitor, a transimpedance amplifier, and a circuit for injecting AC current to the input of the amplifier from the voltage developed across the photodetector.Type: GrantFiled: April 29, 1993Date of Patent: July 12, 1994Assignee: International Business Machines CorporationInventor: Peter Jean-Woo Lim
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Patent number: 5321254Abstract: A light-receiving and amplifying device includes a plurality of photodiodes and amplifier circuits which receive inputs from anodes of the photodiodes. There is provided a first current mirror circuit for outputting a second current having the same magnitude as that of a first current which is a sum of currents flowing through cathodes of the photodiodes. Further provided is a second current mirror circuit which receives the second current from the first current mirror circuit and receives divided currents each having an even magnitude from the anodes of the photodiodes. An AC operation range of the light-receiving and amplifying device is widened in a simple manner at a low cost without significant dimensional increase of the device.Type: GrantFiled: May 26, 1993Date of Patent: June 14, 1994Assignee: Sharp Kabushiki KaishaInventors: Naruichi Yokogawa, Naonori Okabayashi, Koichi Hanafusa
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Patent number: 5319191Abstract: An amplitude-shift-keyed (ASK) receiver is described for use in receiving infrared ASK modulated carrier signals wherein a delayed version of a demodulated pulse os compared with a stretched version and a dynamic threshold signal to reproduce binary data pulses. The dynamic threshold signal is further compared with the stretched version to derive an indication of the amplitude of the incident optical carrier. An embodiment illustrating use of the ASK receiver in an infrared communication system is described.Type: GrantFiled: March 25, 1993Date of Patent: June 7, 1994Assignee: K & M Electronics, Inc.Inventor: James W. Crimmins
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Patent number: 5313057Abstract: A non-selective photoreceiver for frequency-modulated optical signals and optically using the receiver. The photoreceiver includes a laser operating under longitudinal multimode conditions, such as a FABRY-PEROT-type laser operating in a longitudinal multimode. The photoreceiver can function around any one of the longitudinal modes of the laser in overlapping frequency ranges, providing a wide overall band of operation. The plurality of modes reduces the selectively of the photoreceiver. The invention is also related to an optical link, which is either unidirectional using a photoreceiver as described above, or using two subassemblies each having a photoreceiver according to the invention, each photoreceiver being able to operate in an emission or a reception mode.Type: GrantFiled: November 30, 1992Date of Patent: May 17, 1994Assignee: France Telecom Etablissement Autonome de Droit PublicInventor: Hisao Nakajima
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Patent number: 5304814Abstract: A sensor circuit and method for detecting the presence of a substance having a flow that can be turned on and off, such as ink in an ink ejecting print head, has means for turning on and off the flow of the substance at a predetermined frequency. An optical sensor has a light path that is at least partially interrupted by the substance when the flow is turned on. The optical sensor is biased to operate within a range in which the sensor produces an output, even though the light path is only partially interrupted by the substance. An integrator integrates the output of the sensor, and a high gain amplifier amplifies the integrated signal to provide a sensor circuit output signal. When the substance at least partially interrupts the light path, the integrated output signal indicates its presence.Type: GrantFiled: February 26, 1993Date of Patent: April 19, 1994Assignee: Xerox CorporationInventor: Roger G. Markham
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Patent number: 5304794Abstract: The present invention utilizes the internal photovoltaic effect of a GaAs SFET to mix an RF modulated optical signal with a microwave signal. As those skilled in the art will readily recognize, a GaAs MESFET generically comprises an n layer of GaAs (channel) deposited on semi-insulating GaAs (substrate). Source, gate and drain electrodes are then formed on the channel with the gate acting as a Schottky barrier. In this standard MESFET, the difference in doping between the channel and substrate produces a potential barrier. It has been found that when the device is illuminated, the potential barrier is reduced in the region between the source and the gate and drain and the gate. This reduced potential barrier allows more drain current to flow from the device. It has been found that this drain current photoresponse is highly non-linear with respect the gate voltage applied to the device and therefore, it may be used to mix RF modulated optical signals with microwave signals.Type: GrantFiled: May 25, 1993Date of Patent: April 19, 1994Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Steven A. Malone, Arthur C. Paolella
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Patent number: 5296697Abstract: A variable impedence photodiode detector circuit for use in detecting signals in the infrared (IR) includes circuitry to maintain a constant reverse bias voltage on the photodetector to maintain the best signal transfer characteristics regarding frequency response, analog bandwidth, sensitivity, output current range, and signal-to-noise ratio over an operating range from total darkness to maximum daylight. A series current source varies the current to the photodiode in response to variations in detector impedence.Type: GrantFiled: August 10, 1992Date of Patent: March 22, 1994Assignee: ParkerVision, Inc.Inventor: Charlie D. Moses, Jr.
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Patent number: 5286968Abstract: The invention relates to a device for multichannel analog detection of a signal to be detected having a very good signal/noise ratio. It incorporates a modulator (53) producing a modulated signal S(P); means of synchronous attenuation (54) of variable phase .PHI. producing an attenuated modulated signal; a multipoint receiver (52) receiving the modulated-attenuated signal and producing for each point a primary analog signal; an integrator producing for each point a value V(P,.PHI.) resulting from the integration over N periods of the primary analog signal; means of reading, of digitizing and of storing the values V(P,.PHI.) for a given .PHI. value; a phase sequencer giving .PHI. the values .PHI..sub.0 +i2.pi./n successively where i is an integer varying from 1 to n; a digital processing unit making it possible to obtain data representative of S(P) from the values V(P,.PHI.). It is particularly well adapted to the detection of a luminous flux with an array of photodiodes.Type: GrantFiled: March 10, 1992Date of Patent: February 15, 1994Assignee: Centre National de la Recherche Scientifique (CNRS)Inventors: Daniele Fournier, Francois Charbonnier, Philippe Gleyzes, Albert-Claude Boccara
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Patent number: 5281805Abstract: An optical latch circuit is used for an optical-input section in a processor chip having a plurality of processor units each of which includes a processing section and an optical-input section. The optical input section includes a two-dimensional array, or matrix, of optical latch circuits. The optical latch circuit comprises a photodiode, coupled to a differential amplifier circuit having two CMOS circuits and a latch switch; a PMOS transistor of one of the CMOS circuits receives a control voltage from an auto-zero negative feedback circuit to produced threshold values by itself; and a PMOS transistor of the other CMOS circuit receives a control voltage from an optical-input stabilizing circuit, complementary to the auto-zero negative feedback circuit. The optical input of the photodiode is latched and amplified by turning on and off the latch switch in synchronism with the control clock, for transmission of digital electrical signals to input gates in the processing section.Type: GrantFiled: November 18, 1992Date of Patent: January 25, 1994Assignee: Nippon Sheet Glass Co., Ltd.Inventor: Donald J. Sauer
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Patent number: 5270533Abstract: A stabilization biasing circuit is provided for an avalanche photodiode. The stabilization biasing circuit allows for a wide range of light levels to be inputted to the avalanche photodiode, while the avalanche photodiode operates under extreme temperatures. The stabilization biasing circuit also provides for an automatic gain control, thereby enabling the electrical output signal of an avalanche photodiode to be relatively constant over a large range of inputted light levels and temperatures. Absence of optical input is identified as an increase in diode noise due to avalanche breakdown.Type: GrantFiled: June 23, 1992Date of Patent: December 14, 1993Assignee: Smiths IndustriesInventor: Gerald F. Pulice
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Patent number: 5270553Abstract: An optical beginning-of-tape detection device with automatic threshold adjustment. In a first embodiment, at two different locations on a tape, a comparator threshold is varied until the comparator switches states. The two locations are sufficiently far apart to guarantee that at least one measurement is not at the beginning-of-tape indication area. The greater of the two thresholds is used, with a predetermined offset for noise margin. In a second embodiment, the threshold is continuously adjusted through a diode across the comparator inputs. The threshold is initialized by moving the tape sufficiently far to guarantee that at some time during initialization the sensor is not at the beginning-of-tape indication area.Type: GrantFiled: December 22, 1992Date of Patent: December 14, 1993Assignee: Hewlett-Packard CompanyInventor: Kevin L. Miller
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Patent number: 5262635Abstract: A technique that corrects photodetector non-linearity without increasing the noise level in the detector signal. The detector is coupled to a preamplifier characterized by the absence of positive feedback, and the preamplifier signal is communicated to a linear amplifier whose output signal is then digitized. The digitized signal is then transformed according to stored calibration information that is representative of the non-linear characteristic of the photodetector. The transformed digitized value thus exhibits a linear characteristic as a function of the intensity of the light source. A number of embodiments perform the correction in hardware before digitizing the signal.Type: GrantFiled: May 12, 1992Date of Patent: November 16, 1993Assignee: Bio-Rad Laboratories, Inc.Inventor: Raul Curbelo
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Patent number: 5260560Abstract: A photoelectric transfer device comprises a light-absorbing layer which absorbs incident light to generate carriers a multiplying layer which multiplies the carriers and a light-shielding layer provided between the photoabsorbing layer and the multiplying layer.Type: GrantFiled: August 20, 1992Date of Patent: November 9, 1993Assignee: Canon Kabushiki KaishaInventors: Masato Yamanobe, Shigetoshi Sugawa
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Patent number: 5252820Abstract: A photoelectric conversion circuit which can detect only signal light from applied light, to avoid influence by disturbance light. An anode of a photodiode (1) is grounded and an input end of a tuning circuit (5) is connected to its cathode through an input terminal (3). An output end of the tuning circuit (5) is connected to an output terminal (4) through an amplifier (6). The output terminal (4) is grounded through a load resistor (7). The tuning circuit (5) is tuned with the frequency of signal light included in light (2) which is applied to the photodiode (1). A photoelectric conversion current caused by disturbance light is removed in the tuning circuit (5), so that only a photoelectric conversion current caused by signal light is detected. Switching devices are connected to the photodiode for providing current from the photodiode to the input terminals of the amplifier.Type: GrantFiled: February 18, 1992Date of Patent: October 12, 1993Assignee: Mitsubishi Denki Kabushiki KaishaInventor: Kohji Shinomiya
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Patent number: 5247187Abstract: A measuring instrument and a method of measuring including providing an illumination arrangement having a plurality of independent illumination sources, a specimen region for conducting a specimen illuminated by the illumination arrangement, a measuring arrangement detecting radiation influenced by the specimen in the specimen region, the illumination arrangement having a plurality of independent aluminum sources which are energized by separate leads and separate switch elements that are operable to selectively operate either individually or in common for a linearity check.Type: GrantFiled: September 18, 1992Date of Patent: September 21, 1993Assignee: AVL Gesellschaft fuer Verbrennungskraftmaschinen und Messtechnik mbH, Prof. Dr.Dr.h.c. Hans ListInventors: Martin Ponticelli, Karl Simbuerger
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Patent number: 5227639Abstract: A converter circuit provides an output signal of polarity opposite that of an input signal having a DC component and a low frequency periodic component in response to presence of that input signal. Current is transferred from a first capacitor to a second to accomplish this conversion. The circuit has particular application in a flame sensing interface circuit using a sensor of the infrared radiation generated by the flame to change the impedance of the sensor. By use of the circuit, the output of an infrared sensing amplifier imitates the output of a conventional flame rod sensor, and provides an output signal compatible with the output of a flame rod to the input to a flame signal processor.Type: GrantFiled: October 6, 1992Date of Patent: July 13, 1993Assignee: Honeywell Inc.Inventor: Paul E. Sigafus
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Patent number: 5214275Abstract: Disclosed is an optically activated microwave switch (10) which includes a field-effect transistor (12) that is switched between conducting and nonconducting states by a photodiode (14) that is connected between the field-effect transistor gate and drain electrode and a photodiode (16) that is connected between the field-effect transistor gate and source electrode. The circuit is configured and arranged for switching unbiased sinusoidal microwave signals of a frequency as high as approximately 10 gigahertz. A cascade arrangement of switches (10) provides increased signal handling capability in situations in which a single switch cannot be employed. Monolithic integrated circuit realizations of both single stage and cascaded stage arrangements are disclosed in which the semiconductor substrate is GaAs, the field-effect transistors are metal-semiconductor field-effect transistors and the photodiodes are interdigitated metal-semiconductor-metal devices.Type: GrantFiled: September 30, 1991Date of Patent: May 25, 1993Assignee: The Boeing CompanyInventors: James L. Freeman, Sankar Ray
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Patent number: 5212378Abstract: An optical receiver includes a light-receiving element, a bias circuit, an output circuit, and a damping resistor. The light-receiving element converts an optical signal into an electrical signal. The bias circuit applies a DC bias voltage to the light-receiving element. The output circuit outputs, from an output terminal, a voltage corresponding to an optical current generated by the light-receiving element. The damping resistor is connected between the light-receiving element and the output terminal in the output circuit and has a resistance set to serve as a critical damping condition in combination with a junction capacitance and a lead inductance of the light-receiving element.Type: GrantFiled: November 8, 1991Date of Patent: May 18, 1993Assignee: NEC CorporationInventor: Yoshihiro Uda
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Patent number: 5206500Abstract: A photodetector receives an optical signal and converts it an electrical signal. A pulse stretcher converts the electrical signal into a first signal which is characterized by having an increased pulse width relative to the electrical signal. A noise averager converts the electrical signal into a second signal which is representative of the average noise component of the electrical signal. A threshold reference is generated as a linear function of the potential difference between the first signal and the second signal. A first comparator compares the magnitude of the first signal and the threshold reference signal and generates a first logic output which is true if the magnitude of the first signal is greater than the magnitude of the threshold reference signal.Type: GrantFiled: May 28, 1992Date of Patent: April 27, 1993Assignee: Cincinnati Microwave, Inc.Inventors: Lawrence G. Decker, Janet R. Poston, Edward F. Hume
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Patent number: 5194727Abstract: An avalanche photodiode quenching circuit (20) incorporates an avalanche photodiode (APD) (22) and a first comparator (C1) responsive to reduction in APD voltage. The comparator (C1) is arranged to activate an APD quench circuit (38) in response to APD avalanche initiation. The circuit (20) also includes a second comparator (C2) arranged to reset the first comparator input (N2) in response to a further reduction in APD voltage caused by initiation of quenching. The second comparator (C2) is also connected to a monostable circuit (48) arranged to latch the first comparator output response to resetting. The monostable circuit (48) maintains the first comparator output level constant until the APD (22) has recharged.Type: GrantFiled: February 20, 1992Date of Patent: March 16, 1993Assignee: The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern IrelandInventors: Martin Johnson, Robin Jones
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Patent number: 5194728Abstract: A driver circuit for an ultraviolet detector (UV) tube discriminates between firing of the UV tube in response to ultraviolet radiation impinging on it and a high resistance short between its output terminals. A capacitor charged on half cycles of AC power applied to the circuit discharges partially when the UV tube fires. This charge is transferred to a second capacitor to create a voltage displaced from ground. Each time the UV tube fires, the steep wave front generated thereby is passed by a high pass filter to a switch which momentarily grounds the voltage on the second capacitor through a resistor. The rapid change in the switch element's voltage signifies the presence of ultraviolet radiation on the UV tube.Type: GrantFiled: December 5, 1991Date of Patent: March 16, 1993Assignee: Honeywell Inc.Inventor: Scott M. Peterson
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Patent number: 5185520Abstract: A sheet overlapping detecting method includes the following steps. A predetermined level value V.sub.os is set as the level of a light emission signal. On the basis of a value V.sub.ik of a light reception signal obtained upon light reception based on light emission corresponding to a light emission signal having a predetermined level value V.sub.os, an optimum value V.sub.od corresponding to the input value V.sub.k is calculated in accordance with a prestored V.sub.ik -V.sub.od characteristic table. The calculated optimum value V.sub.od is set as the level of the light emission signal to drive the light-emitting device. On the basis of a value V.sub.ik of a corresponding light reception signal, a change value V.sub.1-2 corresponding to the input value V.sub.ik is calculated in accordance with a prestored V.sub.ik -V.sub.1-2 chararcteristic table. A determination level V.sub.L is calculated in accordance with the following equation:V.sub.L =V.sub.1 -(V.sub.1-2)1/2where V.sub.Type: GrantFiled: June 13, 1990Date of Patent: February 9, 1993Assignee: Komori CorporationInventor: Yoshiaki Kurata
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Patent number: 5175427Abstract: A optoelectronic circuit arrangement, for instance for thermal viewing equipment, comprises a plurality of independent photodetector elements, whose signals are combined by multiplexers. The multiplexer output is connected with the common input of a switched integrator, which applies integrated signals to an output switch device, steps being taken to ensure that the multiplexer is at all times electrically separated from the output of the output switch device. For this purpose the integrator has at least one channel with three electronic switching members which in a cyclic sequence perform the operations of "integration", "output of integral value to output" and "erase integral value".Type: GrantFiled: October 10, 1990Date of Patent: December 29, 1992Assignee: Steinheil Optronik GmbHInventor: Gerhard Krause
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Patent number: 5170035Abstract: A circuit for controlling current flow in an instrumentation loop includes a light sensor receiving impinging light and delivering a signal varying with the intensity of the impinging light. The signal is amplified and produces a reference signal which is a current signal of about four milliamperes in the absence of incoming light and about twenty milliamperes in maximum light. A voltage controlled current driver presents an impedance to current flow through the loop which varies with the reference signal and with the intensity of the incoming light. The sensor includes a mounting plate, a photodetector mounted on the mounting plate, a filter mounted over the photodetector, and a diffuser mounted on the mounting plate forming a dome over the filter and photodetector. The diffuser disperses incoming light before the incoming light impinges the photodetector. The filter blocks infrared light thereby blue enchancing impinging light to approximate the light sensitivity response of a human eye.Type: GrantFiled: November 28, 1990Date of Patent: December 8, 1992Inventors: Lee R. Webster, Robert H. Richardson
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Patent number: 5168154Abstract: An electrical quenching circuit for detecting, and quenching, avalanches in an avalanching device (5), comprises a TTL comparator (14) having one of its inputs (24) fed with a predetermined potential via a potential divider (18,20) and a voltage reference (22). When a switchable current source (6) is in its low impedance state, and when the device (5) is quiescent, diodes (10 and 16) conduct and input (12) is held at the potential of the voltage reference (22). Comparator (14) is in one stable state. Variations in the voltage reference affect both comparator inputs substantially equally. When the device (5) avalanches, the current from source (6) is diverted through the device and the diodes (10 and 16) cease to conduct. The potential at comparator input (12) falls and, at a critical value, switches the comparator to its other stable state. This is indicated by a pulse on line (34). The output on line (28) switches current source (6) into its high impedance state and quenches the avalanche in the device (5).Type: GrantFiled: October 28, 1991Date of Patent: December 1, 1992Assignee: Kidde-Graviner LimitedInventor: Phillip E. Harley
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Patent number: 5162646Abstract: Embodiments disclose an adjustable filter (cf voltage-controlled bandwidth) having photoconductors whose resistance is adjusted by variable-intensity radiation source means, with a related feedback loop to compensate for thermal changes.Type: GrantFiled: June 19, 1991Date of Patent: November 10, 1992Assignee: Unisys Corp.Inventors: Bruce H. Williams, Valjean P. Snyder, Patrick S. Grant
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Patent number: 5155353Abstract: A monolithic integrated circuit using MOSFETs operatively configured in weak channel inversion made wherein pulses of light by interest are identified by identifying levels of light signal that exceed a threshold difference between a detected light level signal and a noise light level signal.Type: GrantFiled: August 14, 1991Date of Patent: October 13, 1992Assignee: Tandberg DataInventor: Per O. Pahr
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Patent number: 5134304Abstract: The present invention relates to a photoelectric switch which has a light projecting means that projects light pulses as a result of a pulse signal and a light receiving means that receives the light pulses and outputs a light receiving signal. In one arrangement an enhanced voltage of about two times the supply voltage is applied to a light projecting element, such as an LED, thereby making it possible to provide a photoelectric switch which operates at a reduced power supply voltage. By providing a composite LED drive voltage the drop in supply voltage, inherent in conventional photoelectric switches when the output circuit is activated (thereby reducing the voltage to the light emitting element) does not inhibit operation.Type: GrantFiled: May 15, 1991Date of Patent: July 28, 1992Assignee: Fuji Electric Co., Ltd.Inventors: Kiyoshi Tanigawa, Ken-Ichi Sakanoue
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Patent number: 5130526Abstract: The invention relates to a circuit array for an optical Schmitt trigger in which an optical input signal is converted into an electrical output signal by means of a light-sensitive receiver element, an amplifier stage, a Schmitt trigger stage and an output stage.It is provided in accordance with the invention that the amplifier stage contains a transimpedance amplifier stage, a differential amplifier stage, a first reference network and a compensating element, that the Schmitt trigger stage comprises a differential amplifier stage, a second reference network and a positive-feedback network, and that the output signal is emitted at the circuit output of the output stage.Type: GrantFiled: March 1, 1991Date of Patent: July 14, 1992Assignee: Telefunken electronic GmbHInventors: Peter Mischel, Bernhard Schuch, Ulrich Wicke
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Patent number: 5122651Abstract: A device for measuring a luminance of a fluorescent screen of a cathode ray tube includes a photoelectric conversion device for receiving light from the fluorescent screen and converting the light to electrical energy, an integral device for integrating the electrical energy, a measurement device for measuring the glowing interval time of the cathode ray tube, and a control device for controlling the integral device so as to integrate the electric energy for a general integral time corresponding to the interval time. Also, this device has a calculation device for calculating an offset integrated electrical energy corresponding to a bias component of the photoelectric conversion device, another calculation device for calculating a true integrated electrical energy by subtracting the offset integrated electrical energy from the measured general integrated electrical energy.Type: GrantFiled: July 10, 1990Date of Patent: June 16, 1992Assignee: Minolta Camera Kubushiki KaishaInventors: Hiroshi Furukawa, Yoshihiro Okui, Kazuhiko Naruse
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Patent number: 5117118Abstract: A photoelectric switch is adapted for us as either a transmission type or a reflection type switch. To provide an integrated circuit for the photoelectric switch and to minimize input/output pins, multiple functions are assigned to each input/output pin. Such functions are provided via first to fourth integrated circuit input/output pins, i.e., the first pin serves functions in the supply of a detection output and a self-diagnosing output; the second pin supports a circuit for driving a projection type LED and a circuit for turning the LED off; the third pin supports a circuit for reversing a stable indication output and an operation indicating output; and the fourth pin supports a circuit for amplifying a received photo-signal and for controlling the mode of combination of photoelectric signals from a pair of photo-diodes.Type: GrantFiled: October 13, 1989Date of Patent: May 26, 1992Assignees: Astex Co., Ltd., Takenaka Electronic Industrial Co., Ltd.Inventor: Toshifumi Fukuyama
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Patent number: 5103084Abstract: Embodiments disclose an adjustable filter (cf voltage-controlled bandwidth) having photoconductors whose resistance is adjusted by variable-intensity radiation source means, with a related feedback loop to compensate for thermal changes.Type: GrantFiled: June 15, 1989Date of Patent: April 7, 1992Assignee: Unisys Corp.Inventors: Bruce H. Williams, Valjean P. Snyder, Patrick S. Grant
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Patent number: 5091640Abstract: The invention provides an oscillatory suppression circuit (54) for use in a photosensor loop circuit (10) employing a phototransistor (14). The oscillation suppression circuit (54) prevents oscillation in the photosensor loop circuit (10) caused by detected unmodulated high frequency light. The oscillatory suppression circuit (54) includes a resistor (58) and a capacitor (62) connected in series, and also connected in parallel with a base resistor (38) of a feedback transistor (26). The oscillatory suppression circuit (54) adds a small amount of phase advance to a feedback circuit (50). This small phase advance counteracts any additional negative phase shift produced when intense light pluses are detected by the phototransistor (14) and amplified by the high gain of the feedback circuit (50).Type: GrantFiled: June 24, 1991Date of Patent: February 25, 1992Assignee: Square D CompanyInventors: Colin V. Cornhill, Charles K. Carlin
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Patent number: 5091641Abstract: Optoelectric front-end comprising a photodiode which is not grounded and which drives a bipolar transistor acting as a feedback amplifier between the base and the emitter thereof, so that the d.c. arrangement of the transistor will cause no further noise to develop.Type: GrantFiled: November 27, 1990Date of Patent: February 25, 1992Assignee: AT&T Bell LaboratoriesInventor: Pieter W. G. Duijves
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Patent number: 5087808Abstract: A combined optical power and noise meter for measuring both optical power and optical noise includes a detector housing and a photodiode which is disposed in the detector housing. The resistence of the photodiode changes continually in response to the application of optical power thereon. A current to voltage converter applies a bias voltage to the photodiode and transforms an output current therefrom in order to obtain a power voltage which is proportional to the optical power. A first voltage meter is electrically coupled to the current to voltage converter in order to display the power voltage. A noise measuring circuit measures noise in the output voltage of the current to voltage converter and processes the output voltage in order to obtain a noise voltage which is proportional to the optical noise. A divider divides the noise voltage by the power voltage in order to obtain an optical noise to optical power voltage which is proportional to the ratio of optical noise to optical power.Type: GrantFiled: February 26, 1991Date of Patent: February 11, 1992Inventor: Edwin A. Reed
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Patent number: 5086219Abstract: A computer vision edge-detection circuit uses two independent resistive networks to smooth the voltages supplied by an array of logarithmic photoreceptors. The voltages on the two networks are substracted and exclusive-or circuitry is used to detect zero-crossings. In order to facilitate thresholding of the edges, an additional current is computed at each node indicating the strength of the zero-crossing. This is particularly important for robust real-world performance where there will be many small zero-crossings induced by noise. Implementation of the present invention using analog VLSI techniques makes it feasible, and, in fact, practical to provide a large plurality of such photoreceptors on a single integrated circuit chip. Such chips can provide image acquisition and edge-detection with noise elimination in one chip in real time.Type: GrantFiled: November 30, 1990Date of Patent: February 4, 1992Assignee: California Institute of TechnologyInventors: Christof Koch, Wyeth Bair
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Patent number: 5068526Abstract: A photoelectric conversion device comprises a first voltage source for providing a first predetermined voltage, a photoconductive cell having a first end connected to the first voltage source and a second end, the photoconductive cell being provided so as to receive an optical radiation and having a resistance that is changed in response to the optical radiation supplied to the photoconductive cell, a load resistance having a first end connected to the second end of the photoconductive cell and a second end, a second voltage source connected to the second end of the load resistance for providing thereto a second predetermined voltage that is different from the first predetermined voltage, and threshold detection circuit having an input terminal connected to the second end of the photoconductive cell, wherein the threshold detection circuit has a threshold level and produces a first output signal having a first level when an input signal supplied to the input terminal has a level below the threshold level whilType: GrantFiled: September 12, 1990Date of Patent: November 26, 1991Assignee: Ricoh Company, Ltd.Inventor: Akihiko Hiroe
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Patent number: 5066121Abstract: In a method of measuring the flash duration of a flash unit, the momentary light intensity is converted into an electrical signal that is determined and stored, and that is delayed by at least that time interval that exists between the beginning of the flash curve and the maximum thereof. The stored maximum is compared with the delayed signal, with the flash duration being determined from the signal obtained thereby. As a result, at the maximum of the intensity/flash duration curve, the information concerning the rising leg of this curve is still available. The apparatus comprises a sensing element for the flash intensity, with the sensing element being followed by a time-lag element and a peak detector, the outputs of which are connected to a comparator, the output of which is connected to a time-interval measuring circuit.Type: GrantFiled: September 29, 1989Date of Patent: November 19, 1991Assignee: Bron Elektronik AGInventor: Jean-Francois Bernhard
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Patent number: 5055670Abstract: A document sensing apparatus includes a phototransistor (12) for generating a first or second voltage depending on whether or not, respectively, a document is present at a sensing location, and a capacitor (36) for providing a second voltage whose peak value is determined by said second value. A voltage comparator (30, 38, 40) compares said first and second voltages and provides an output signal indicative of the presence of a document at the sensing location if said first voltage is less than a predetermined fraction of said second voltage. A microprocessor (44) controls the operation of a circuit (71-1) which provides, as necessary, a charging current to said capacitor (36) so that, while a document is present at the sensing location, said second voltage is prevented from falling by a significant amount, thereby preventing problems occurring if a document remains at the sensing location for a prolonged period due to a feeding irregularity.Type: GrantFiled: September 17, 1990Date of Patent: October 8, 1991Assignee: NCR CorporationInventor: Douglas L. Milne
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Patent number: 5037198Abstract: 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.Type: GrantFiled: July 16, 1990Date of Patent: August 6, 1991Assignee: Eastman Kodak CompanyInventor: Michael J. Gaboury
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Patent number: 5034601Abstract: A photoelectric switch is adapted for use as either a transmission type or a reflection type switch. To provide an integrated circuit for the photoelectric switch and to minimize input/output pins, multiple functions are assigned to each input/output pin. Such functions are provided via first to fourth integrated circuit input/output pins, i.e., the first pin serves functions in the supply of a detection output and a self-diagnosing output; the second pin supports a circuit for driving a projection type LED and a circuit for turning the LED off; the third pin supports a circuit for reversing a stable indication output and an operation indicating output; and the fourth pin supports a circuit for amplifying a received photo-signal and for controlling the mode of combination of photoelectric signals from a pair of photo-diodes.Type: GrantFiled: July 11, 1990Date of Patent: July 23, 1991Assignees: Astex Co., Ltd., Takenaka Electronic Ind. Co., Ltd.Inventor: Toshifumi Fukuyama
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Patent number: 5030822Abstract: A photoelectric switch is adapted for use as either a transmission type or a reflection type switch. To provide an integrated circuit for the photoelectric switch and to minimize input/output pins, multiple functions are assigned to each input/output pin. Such functions are provided via first to fourth integrated circuit input/output pins, i.e., the first pin serves functions in the supply of a detection output and a self-diagnosing output; the second pin supports a circuit for driving a projection type LED and a circuit for turning the LED off; the third pin supports a circuit for reversing a stable indication output and an operation indicating output; and the fourth pin supports a circuit for amplifying a received photo-signal and for controlling the mode of combination of photoelectric signals from a pair of photo-diodes.Type: GrantFiled: July 11, 1990Date of Patent: July 9, 1991Assignees: Astex Co., Ltd., Takenaka Electronic Industrial Co., Ltd.Inventor: Toshifumi Fukuyama
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Patent number: 5025169Abstract: A sensor in IC formation has a light emitting means, and a light receiving means disposed for receiving a faint pulsed light generated by scattering of light emitted from the light emitting means, in which a switching means capable of short-circuiting between sensor circuit lines is provided for being triggered by a counter means operated in response to an output from the light receiving means, and constituent elements of respective components of the sensor including the said means and capable of being formed in the IC are formed as integrated circuits on a dielectric isolation substrate, whereby electric isolation of the respective elements can be made complete irrespective of light irradiation to realize effective interelement junction and isolation.Type: GrantFiled: October 18, 1989Date of Patent: June 18, 1991Assignee: Matsushita Electric Works, Ltd.Inventors: Masao Arakawa, Tomizo Terasawa, Masanobu Ogawa, Hironori Kami
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Patent number: 5019704Abstract: A control loop comprising a control section, a set value/actual value comparator and a controller is expanded for ultraprecision measurements in such a way that, to detect measurement signals, the control variable connection between the controller output and the control section input is guided via a measured value transducer and, to evaluate and display the measured value, the correcting variable output of the controller is additionally connected to an evaluating circuit.Type: GrantFiled: December 12, 1989Date of Patent: May 28, 1991Assignee: BASF AktiengesellschaftInventors: Clifton Zimmermann, Heribert Kuerten, Helmut Lewin
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Patent number: 5013904Abstract: A single-chip integrated photodetector including a photodiode for detecting intensity of light and a photo-device for detecting the intensity of the light, which are connected in series, in which ON- and OFF-levels of the photo-device are determined by trigger level and holding current thereof. A current source device having hysteresis characteristics may be also connected to a photodiode, in series, instead of a photo-device to output first or second determined current values when a voltage applied from the photodiode is lower or higher than a certain voltage.Type: GrantFiled: November 7, 1988Date of Patent: May 7, 1991Assignee: Nissan Motor Co., Ltd.Inventor: Hideo Muro
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Patent number: 5008526Abstract: There is provided by this invention a photodetector and circuitry connected thereto wherein separate outputs are produced for low frequency and high frequency signals of the light impinging on the photodetector.Type: GrantFiled: October 2, 1989Date of Patent: April 16, 1991Assignee: McDonnell Douglas CorporationInventor: Samuel I. Green
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Patent number: 5008525Abstract: In a measuring device including a magnetic-optic current transformer (2) defining an optical path having an input (4) and an output (6) and having an optical transmission characteristics such that the relation between optical energy supplied to the input (4) and optical energy arriving at the output (6) is a function of an electrical parameter being monitored, an electrically driven photoemitter (8) disposed for supplying optical energy to the optical path input (4), a photodetector circuit (10, 12) optically coupled to the optical path output (6) for producing an electrical signal representative of the optical power arriving at the output (6), and a control circuit (14,16) connected between the photodetector circuit (10,12) and the photoemitter (8) for controlling the light energy supplied by the photoemitter (8) and forming with the transformer (2) a high pass filter having a corner frequency, the control circuit (14,16) is composed of an amplifier (20) and a first compensation unit (24,26) connected to forType: GrantFiled: August 3, 1989Date of Patent: April 16, 1991Assignee: ABB Power T & D Company, Inc.Inventor: Carlo F. Petronio
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Patent number: 5008531Abstract: A light identifying system includes a photoelectric conversion unit for receiving a pulsed light from a light emitting part on a light receiving part to generate a light reception signal that varies in magnitude according to the quantity of the received light. A peak holding circuit has a time constant that is long compared with the pulse interval of the pulsed light. The peak holding circuit stores a peak value of the light reception signal for its time constant. The peak value is divided by a constant for application to a comparator. The comparator compares it with the light reception signal as a threshold. A peak value of the light reception signal is held, and the peak value thus held is specified as a threshold to the light reception signal, therefore in the unlikely event of decrease in the quantity of emitted light due to a secular change or of decrease in the quantity of received light due to mist and oil film, the threshold decreases accordingly.Type: GrantFiled: August 15, 1989Date of Patent: April 16, 1991Assignee: Chinon Kabushiki KaishaInventors: Shoichi Ono, Atsuhito Kobayashi