Abstract: Safety device composed of a radiation emitter, a radiation receiver disposed for receiving radiation which is produced by the emitter and which traverses a radiation path between the emitter and the detector, the detector producing an output signal representative of the quantity of radiation received by the detector, and an electronic circuit coupled to the detector for analyzing the output signal produced by the detector and identifying a reduction in the magnitude of the output signal as a result of an obstruction in the radiation path, wherein the emitter and the detector are mounted on a cooking appliance in a manner which allows extraneous radiation in the vicinity of the cooking appliance to traverse the radiation path.

Abstract: A trigger circuit including a light source supplying a first beam of light having a first frequency, a frequency altering device positionable to receive the first beam of light. The frequency altering device receiving the first beam of light and transmitting a second beam of light having a second frequency. A frequency sensitive component operable in response to the second beam of light having the second frequency, the frequency sensitive component being positioned to receive the second beam of light and provide a trigger signal. A trigger coupled to receive the trigger signal and, upon receipt of the trigger signal, triggering the system. A light filter can be included to transmit the light of the second frequency.

Abstract: An inexpensive, miniaturized and thin image reading apparatus reads various types of images, such as fingerprints. The apparatus includes a transparent substrate. A light-emitting unit emits light to pass through the transparent substrate and to be applied to a subject pressed against the substrate. A plurality of light-receiving units are disposed on the substrate in the vertical and horizontal directions with intervals therebetween and receive the light which is emitted from the light-emitting unit and is reflected from the subject. A reading device reads an image of the subject in accordance with the amount of light received by the light-receiving units.

Abstract: A light level sensor for use in controlling the switching of artificial lighting. The sensor comprises a photoelectric transducer which provides an output signal at a level which is significant of the illumination level of incident light. An A-D converter and a microprocessor are located in circuit with the transducer for detecting the level of the transducer output signal and for any cyclic variation of the transducer output signal resulting from cyclic variation of the level of incident light. Further circuit means are provided for generating a sensor output signal if either (a) the level of the transducer output signal is below a predetermined level or (b) the level of the output signal is above the predetermined level and, at the same time, cyclic variations occur in the level of the transducer output signal.

Abstract: A method and apparatus for measuring very low light signals including integrating a signal from a photo diode, avalanche photo diode, photomultiplier tube or the like, digitally sampling the integrator output more than two times during each integration period, fitting a curve to the multiple digitized readings to calculate the integration slope for each integration period and determining the original signal from the calculated integration slope.

Abstract: The present invention relates to an electronic shelf display device which includes an optical device and an ambient light detector circuitry. The electronic shelf display device includes an independent power source, and a housing. The electronic shelf display device also includes a processor disposed in the housing, and a display device supported by the housing and coupled to the processor. The display device is capable of displaying information to a user. The optical device is coupled to the processor for at least receiving optical communications. The ambient light detector circuitry is also coupled to the processor. The processor is operative to regulate the power state of the electronic shelf display device based on ambient lighting conditions determined by the ambient light detector circuitry. By having the optical device include the ambient light detector, only one port is required for receiving light by the electronic shelf display device thus resulting in substantial space savings.

Abstract: A wafer sensing apparatus for sensing whether a wafer is inserted in a wafer cassette. The wafer sensing apparatus includes a light emitting device for emitting light of a predetermined wavelength toward the inside of a wafer cassette, a light sensing device, positioned opposite to the light emitting device, for sensing the emitted light, and an optical filter device for passing light corresponding only to the predetermined wavelength of light emitted from the light emitting device. The light sensing device is not affected by interference light from outside sources that can cause a faulty wafer sensing function, since the interfering light is reflected or absorbed by the optical filter device. Equipment malfunctions caused by faulty sensing from the light sensing device are prevented, thereby improving the equipment operating efficiency.

Abstract: An ambient light filter includes light emitting circuitry and optical detection circuitry. The detection circuitry is positioned to detect light from the emitting circuitry. A microprocessor is provided to separately control the light emitting circuitry and the optical detection circuitry. The microprocessor determines whether light from the emitting circuitry has been detected by removing a measured component equivalent to the ambient light present at the optical detection circuitry.

Abstract: A method for operating an optical light sensor for the detection of objects present in the monitored region in which light signals are transmitted into the monitored region in specific time intervals. The transmitted light signals and also the interference signals which occur are received and are evaluated for the detection of objects present in the monitored region, with the transmission reception of the light signals, and also the reception of the interference signals, respectively taking place in time sequential frame intervals. In the absence of an interference signal within a frame interval the transmission of the light signal takes place at the end of the frame interval defining a normed transmission timepoint for the respective light signal. On the occurrence of an interference signal within a frame interval the transmission of the next light signal is delayed timewise relative to its normed transmission timepoint. Furthermore a light sensor of this kind is described.

Abstract: An agricultural implement for spraying herbicide on weeds in a field without spraying herbicide on bare soil includes a photodetector circuit. The photodetector circuit includes a photodetector and an active filter. The photodetector is not AC coupled in parallel with an inductor/capacitor resonant circuit which tunes the active filter. As a result, changes in photodetector capacitance due to changes in ambient lighting conditions are not impressed across the resonant inductor/capacitor circuit and therefore do not adversely change the frequency and phase characteristics of the photodetector circuit.

Abstract: A continuously active artificial light source, such as a light-emitting diode (LED), is supported in a housing that also contains a photocell, and is directed at the operating detection surface of the photocell. A light-transmitting diffuser, such as made of translucent plastic, covers the detection surface of the photocell and allows ambient light to pass to the surface, which thereby detect a combination of external ambient light and light from the artificial source. The light source thereby biases the photocell, so that, in normal operation, the photocell produces an output voltage that does not exceed a predetermined value. The predetermined value is set at a level approximating the output voltage measured during total darkness outside the photocell housing. If an open-circuit condition occurs, the voltage of the photocell will exceed that predetermined value, thus permitting the checking circuit to recognize a faulty photocell.

Abstract: A first light receiving portion and a second light receiving portion are provided on the upper surface of a moving body having driving wheels at an interval of a prescribed distance in a plane. The first light receiving portion and the second light receiving portion rotate around the axis in the vertical direction. On the other hand, a first light emitting portion and a second light emitting portion are provided on the side face of a station serving as a reference station at an interval of a prescribed distance in a plane. The first and second light receiving portions carry out sampling while rotating, so that the quantity of light reception is changed according to the directivities of the first and second light receiving portions. When the peaks of the directivities of the first and second light receiving portions match the direction of the first light emitting portion or the second light emitting portion, the quantity of light reception is maximized.

Abstract: The present invention relates to an apparatus and a method for detecting pulses of light energy from at least two fields of view. A first detector having a first bias detects a pulse received at a first point in time. A second detector having a second bias, different from the first bias, detects a pulse received at a second point in time. A processor compares an output of the first detector with a first threshold to produce a signal representing receipt of a pulse from a first field of view. The processor also compares an output of the second detector with a second threshold, different from the first threshold, to produce a signal representing receipt of a pulse from a second field of view. Because the detectors are biased with different biases, the detected pulses are easily distinguished. Thus, multiple fields of view can be detected without complex hardware. The detectors can be biased with opposite polarities so that background noise is cancelled out.

Abstract: There is provided a photosensor having a photoelectric converter for converting incident light into a photoelectric current, and a function of removing noise light from imaging light including noise light and reflected from an object to be photographed. A plurality of photosensors each having the arrangement are used as an image sensor. A single photosensor having the arrangement or a plurality of photosensors each having the arrangement are used as a distance sensor. There is provided a photosensor in which a storage unit stores electric quantity corresponding to fixed light, and electric quantity corresponding to reflected light in the state wherein electric quantity stored in the storage unit is reproduced by a reproduction unit is introduced, and the difference therebetween is reproduced as an electric signal. A single photosensor having the arrangement or a plurality of photosensors each having the arrangement are used as a distance sensor.

Abstract: The light selected by a selection circuit 3 at a light emitting side and emitted from a light emitting element 1 such as a LED is converted to a specifically modulated light by an oscillation circuit 11. The light received by a light receiving element 2 such as a phototransistor at the receiving side is amplified by an amplifier circuit 6, and a detection circuit 12 detects whether a specifically modulated light is received. The H/L detection circuit 13 determines the presence/absence of a light interruption to produce a signal of either H (high level) or L (low level). Also, the signal from the oscillator 11 of the emission side is received by the receiving side and compared with the received signal to determine whether the same signal as emitted from the emitting element has been actually received.

Abstract: A device and method for efficiently synthesizing diverse molecular products on substrates. A parent vessel 200 contains a suspension of substrates. The suspension is pressurized with argon and transferred to a plurality of reaction vessels 201-209 in one or more reaction vessel banks where monomer addition reactions take place. Optionally, the substrates may be tagged with a tag monomer. A vortexing motor 300 vortexes the contents of reaction vessels 201-209 during monomer addition reactions to enhance synthesis. After the desired monomer and/or tag monomer addition reaction, the suspension is pressurized with argon and transferred back to parent vessel 200 for mixing. Thereafter, the suspension may be pressurized with argon and reallocated among reaction vessels 201-209 for further synthesis.

Abstract: A photoelectric switch having a rectifier for converting a received AC voltage to a DC voltage, a transparent cover having a user friendly finger rest surface, means for generating a pulsed infrared beam across the finger rest surface, means responsive to the breaking of the pulsed infrared beam by an operator placing at least one finger on the finger rest surface to actuate a relay to generate an output signal, and means for disabling the actuation of the relay in response to the operator removing his finger from the finger rest surface restoring the continuity of the pulsed infrared beam. The photoelectric switch includes fault protection circuits which disable the relay when the AC voltage is below a predetermined voltage, when the ambient infrared background illumination exceeds a predetermined value, or when the means for generating a pulsed infrared beam fails to generate the beam.

Abstract: A multi-axis light beam type sensor with a simple fail-safe sensor system which stops when the sensor system is abnormal (logic value "0") is provided. The construction is such that scanning output signals for synchronously driving respective light emitting elements (LD) and light receiving elements (PD) positioned facing each other are generated using shift registers. A normal or abnormal condition of the scanning output signals is judged based on an output of the light transmission side shift register (5), using an addition operation in a scanning output signal checking circuit (9). Moreover, coincidence or non coincidence of last stage outputs of the respective shift registers of the light transmission and light reception sides, is determined by a coincidence detecting circuit (10).

Abstract: Compensation and health monitoring techniques and devices for fiber optic intensity modulated sensors provide automatic adjustment of light intensity in order to maintain continuous calibration of the fiber optic sensors in the presence of undesirable environmental or handling conditions. These undesirable conditions may arise from such factors as fiber bending, optical connector mechanical and thermal instabilities, extreme temperatures at sensors, and changes in optical coupling between optical sources (e.g., light emitting diodes) and detectors (e.g., PIN photodiodes) and the optical fibers. Through light intensity normalization, the new techniques enable a continuous calibrated sensor output and sensor health monitoring by continuous or intermittent observation of the light emitting diode current.

Abstract: A touchless switch using a single detector to measure ambient energy and reflected energy. The detector can detect objects in both the normal unsaturated ambient energy state or when ambient energy is saturating the detector. Discrimination between toggle motion and motion which is not intended to indicate a switch toggle operation is also provided. The detector and the emitter are mounted to a circuit board which is then mounted within a housing which has a window that allows passage of ambient energy and reflected energy. A barrier between the detector and the emitter blocks energy from being directly transmitted from the emitter to the detector. The barrier may be inserted into a groove in the window to prevent energy from the emitter from being reflected off of the inner surface of the window to the detector. Accidental triggering by ambient energy is prevented by requiring that the reflected energy be detected for a minimum amount of time.

Abstract: An apparatus for detecting obstructions includes a plurality of emitters for radiating beams of energy, a plurality of detectors for providing detector signals in response to the beams of energy radiated by the plurality of emitters and a controller for determining if the beams of energy are obstructed by analyzing the detector signals and implementing a dynamic detection threshold. The controller generates an average beam strength and current beam strength from which said controller means determines if an obstruction is present by determining if the current beam strength is within a predetermined range of the average beam strength.

Abstract: A photoelectric switch includes a light emitting section emitting pulse light so that intensity of the emitted pulse light is sequentially increased. A light detecting section detects the pulse light emitted by the light emitting section. A light detection signal indicative of the received light is amplified and then integrated. A high-level light detection signal is delivered by the light detecting section when an integral value is equal to or above a threshold. A determination circuit delivers a first detection signal when a duration of the light detection signal is equal or above a predetermined values. The determination circuit further delivers a stable operation signal when a set time period is reached. The light detecting section is integrated into one-chip configuration.

Abstract: A coin hopper having an optical-electrical coin sensor with a light source and a light detector is provided. The coin hopper includes a coin transport disc, a coin trough, and a coin payout chute. The coin sensor is secured to the hopper and is proximally located to the coin payout chute. The sensor is configured such that the light detector is substantially adjacent the coin transport disc and the light source is spaced apart from the coin transport disc. The sensor is operatively connected to the coin hopper control circuitry which shuts down the hopper after the appropriate number of coins is dispensed. The hopper may also include circuitry which, in conjunction with the light source, provides a pulsed or intermittent beam of light.

Abstract: Environmental variations in ambient light and temperature are eliminated in arrangements for and methods of detecting objects in areas exposed to such variations by generating a differential measurement value indicative of the difference between two signals derived from two light sources, both signals being affected in the same way and extent by the environmental variations.

Abstract: A lighting system having an electric lamp controlled by an infrared remote controller. The remote controller incorporates a commercially available transmitter and receiver which reliably functions in the presence of infrared noise having frequencies at and about the carrier frequency of the transmitted signal. The remote controller receiver outputs a demodulated signal and a filter acts on the demodulated signal to remove noise present in the demodulated signal caused by the electric lamp by comparing measured time intervals between leading and trailing edges of the demodulated signal to predetermined values defining data elements.

Abstract: A system for measuring angular relationships of wheels of a vehicle includes a radiation source mounted with respect to a first wheel for providing a radiation signal, an image detector having an active array of pixels mounted with respect to a second wheel for receiving an image from the radiation source and for producing an output in response to the radiation signal, and a radiation detector disposed in the path of the radiation from the radiation source for detecting the presence of the radiation signal. A controller is responsive to the presence of the radiation signal to activate the image detector to receive the image from the radiation source and determine an alignment angle of a wheel of the vehicle from the output of the image detector. A mask is mounted between the radiation source and the detector for defining an image of the radiation source upon the detector, the mask preferably having at least three slits therein.

Abstract: A photodetector circuit is disclosed which can extract a carrier frequency signal from an optical beam. A photodiode is back-biased by a voltage supply, and the capacitance of the photodiode is dependent on the value of its back-bias potential. The photodiode is connected in parallel resonance with an inductor, and the parallel resonant combination is connected to the input of an inverting amplifier having a feedback capacitor. This feedback capacitor causes a capacitive component to appear in the input impedance of the amplifier which combines with the photodiode capacitance and the inductor to provide a parallel resonant tank circuit. The amplifier has a change in gain versus change in power supply characteristic. By selecting the value of the feedback capacitor, changes in the capacitive component of the input impedance are equal and opposite to changes in the capacitance of the photodiode, and the resonant frequency of the tank circuit is thereby essentially unaffected by changes in the supply voltage.

Abstract: Ambient light and temperature fluctuations are suppressed in an optical receiver system by feeding the output of a photodiode directly to one input of a differential amplifier and, via a low pass filter, to another input of the amplifier. Reductions in amplitude in an optical information signal are automatically compensated.

Abstract: A method and apparatus for highlighting returns from optically augmented targets includes in one embodiment a receiver, a viewing device coupled to the receiver and first and second illuminators. The first illuminator is arranged on axis with the receiver and the second illuminator is placed off-axis therefrom. Means are provided for switching on alternately the illuminators such that returns of the first illuminator through retroreflection from high quality optical targets will enter the receiver, while retroreflection returns of the off-axis illuminator will not enter the receiver; therefore the retroreflected returns from high quality optical targets will appear to flicker when seen on the viewing device and thus be highlighted above the rest of the scene.

Abstract: A method and system for on-site measurement of strobe light intensity on an aircraft is disclosed, including the steps of orienting a photometric sensor toward the strobe light on the aircraft to be measured and determining the distance between the strobe light and the sensor. When the strobe light is operated, the photometric sensor detects light intensity based on transmittance from the strobe light. The detected light intensity is correlated with the distance between the sensor and the strobe light to generate a data reading representing an estimate of light intensity emanating from the strobe light. Each of these steps is repeated to determine additional data readings representing estimates of light intensity for the same light. The data is then stored in a memory storage means, such as a computer, and then processed to determine the average value of light intensity for the strobe light.

Abstract: Disclosed is a picture information memory device, including a picture information memory means for generating electric charges corresponding to the intensity of write-in light incident thereon, and for holding the generated electric charges as polarized charges, an exposing means for exposing the picture information memory means to light from an object, and an alternating-current bias voltage applying means for applying an alternating-current bias voltage having a desired frequency to the picture information memory means, whereby electric charges generated by the portion of the object light the intensity of which varies at the same frequency as that of the alternating-current bias voltage, are selectively accumulated from the entirety of electric charges generated by the object light incident on the picture information memory means, and held as the polarized charges in the picture information memory means.

Abstract: A six-pole band-pass filter system and circuit configured for optimal permance in an associated infrared search and track (IRST) system which outputs data in an analog format is disclosed. The key to the successful operation of the filter is its matching to the impulse response of the associated IRST system. By adjusting certain components in the filter, it can operate as an optimal, linear, one-dimensional device to detect unresolved targets against a severely cloud-cluttered background.

Abstract: A print paper detecting circuit for installation on a printer, to detect whether a print paper is supplied at a predetermined position along a paper path by using an optical sensor composed of a light emitting diode and phototransistor. The circuit detects the existence of the print paper according to the detection of light which is emitted from the light emitting diode, which is reflected from the print paper, and which arrives at the phototransistor. According to one embodiment, circuit has a current amplifier and a gain reducing circuit. The current amplifier feeds a pulse current which is greater than the normal constant current to the light emitting diode while the gain reducing circuit reduces the output of the output voltage.

Abstract: An image sensing apparatus includes a sensing device for receiving a light signal, performing a photoelectric conversion and storing information, and a control device for changing the saturation level of the electric charge storable by the sensing device. The saturation level of the electric charge is changed by the control device so as to be comparatively small in an earlier part of a unit-light storage interval which forms one picture, and larger in a latter part of the interval.

Abstract: A light curtain system having a series of light emitting diodes is arranged to produce a beam of light which is modulated at about 40 KHz. The light is broadcast across a physical space in which intrusion detection is desired and received by respectively arranged photo diodes. Each of the light emitting diodes is connected in parallel to a single modulated power supply. Each photo diode produces an electrical signal having a magnitude which is proportional to the amount of light incident thereon. The signal produced by each photo diode is sequentially sampled and then compared to a reference value. If an intrusion in the respective region of the light curtain has occurred, the magnitude of the sampled signal will be less than the reference value providing indicia of an intrusion. Upon such a detection, the light curtain system provides indicia of the intrusion such that consequential remedial action in response thereto may be performed.

Abstract: In a signal processing circuit, a height arithmetic circuit obtains a measured value of a height of an object by using the principle of triangulation from a second light receiving signal which is transmitted from a second photodetector of position detecting type thereto. An error arithmetic circuit acquires a measurement error by using the principle of triangulation from a first light receiving signal which is transmitted from a first photodetector of position detecting type thereto. A correction circuit calculates a correct height of the object by subtracting an output signal of the error arithmetic circuit from an output signal of the height arithmetic circuit.

Abstract: A technique for performing background suppression in photodiode detectors is disclosed. A first detector measures the light emitted by the source to be measured and the background light, while a second detector simultaneously measures the background light only. The value measured by the second detector is subtracted from the value measured by the first detector, and the difference represents the portion of the first detector's measured value which is attributable to the source to be measured.

Abstract: A noise resistant laser system for machine alignment comprised of a semiconductor laser for producing a narrow collimated beam; a photodetector target for receiving the beam and producing four trains of output pulses which are indicative of the horizontal and vertical displacements of the laser beam from the center of the target; a crystal controlled oscillator for generating pulses at a frequency which is distinguishable from the frequencies of noise generated by industrial power supplies, industrial lighting and their harmonics; a closed loop control circuit for pulsing the laser at the distinguishable frequency; and a sample and hold circuit for sorting out components due to the beam displacement and suppressing components due to the industrial power supplies, industrial lighting and their harmonics. The closed loop control circuit is comprised of an interrupter, a feedback control circuit and a laser current control circuit.

Abstract: A method and apparatus for determining the strength and proximity of a pulsed-laser radar signal is provided. A photodetector detects signals and provides the signals to a decision network. The decision network evaluates the signals and generates an output pulse when a detected signal is a valid signal according to predetermined criteria implemented in the decision network. A processor is coupled to the decision network for counting output pulses. A threat indicator is driven by the processor in proportion to the output pulse count.

Abstract: A method for determining the amplified spontaneous emission noise of an optical circuit, such as an optical amplifier, in the presence of an optical signal includes applying a pulsed optical signal of prescribed intensity to an input of an optical circuit under test, and detecting an output signal from the optical circuit slightly after the pulsed optical signal is switched from on to off. The output signal immediately after the optical signal is switched off represents the amplified spontaneous emission noise of the optical circuit in the presence of an optical signal of the prescribed intensity. In a first embodiment, an optical spectrum analyzer is used for detecting the output signal. In a second embodiment, the output signal is passed through a narrow band optical filter to a photodetector. An electrical spectrum analyzer displays the detected waveform. When necessary, the observed output signal is extrapolated to a time immediately after the optical signal is switched off.

Abstract: An apparatus (10) includes at least one detector circuit (12) having circuitry (14) for canceling background radiation, a signal amplifier stage (16) adapted to receive and amplify a signal from the detector circuit (12) and a plurality of discrete frequency detection circuits (18), the discrete frequency detection circuits having a common input (20) and a plurality of outputs (22).

Abstract: An apparatus for providing an indication of the operational stability of a photoelectric control unit. The system separately measures photoelectric operating margin and background noise affecting the control unit. A stability figure is generated as a function of the operating margin and background noise in accordance with fuzzy logic techniques. An indication of the level of this stability figure is provided to the operator of the unit.

Abstract: A dosing dispenser for flowable material, including a container having a erial introducing aperture and an outlet through which material can pass by gravity, an electrically operated valve having a nozzle coupled to the outlet, for controlling the passage of material therethrough, an electromagnetic radiation emitter located in close proximity to the nozzle, for emitting a controlled radiation beam in the vicinity of the nozzle and an electromagnetic radiation detector located adjacent to the emitter and responsive to radiation emitted from the emitter and reflected by a body placed along the emitted radiation path. The emitter and detector are affixed in a radiation directing and shielding housing, for determining the directivity of the emitted and reflected radiation. There is also provided an electronic control circuit for controlling the valve in response to detected radiation reflected by the body placed along the emitted radiation path.

Abstract: 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.

Abstract: An image sensing apparatus includes a sensing device for receiving a light signal, performing a photoelectric conversion and storing information, and a control device for changing the saturation level of the electric charge storable by the sensing device. The saturation level of the electric charge is changed by the control device so as to be comparatively small in an earlier part of a unit-light storage interval which forms one picture, and larger in a latter part of the interval.

Abstract: A modulated light beam obstacle detector for use as a safety mechanism in an automatic closure operator which must operate in varying ambient light conditions. If the obstacle detector senses the interruption of the light beam, the motion of the door is arrested or reversed. The obstacle detector uses an auxiliary light source connected in a feedback circuit to maintain a constant background illumination on the light detector and thereby hold the light detector in conduction at all times. In this manner, the presence of the light beam can be sensed regardless of the ambient light conditions.

Abstract: A device for detecting the marker dye band which is used to monitor the progression of biological macromolecules in gel electrophoresis. This device mounts external to the gel box, and utilizes a single light detector and a pair of AC activated light sources. The light sources produce reflected or transmitted light signals which, when balanced at the detector, cancel. When marker dye is absent the light signals are balanced, and no signal is detected. When marker dye is present at a specific detection point within the gel, the light reflected (or transmitted) is no longer balanced and a signal is detected.

Abstract: Methods and apparatus are disclosed for broadening the bandwidth of a radiation detector and diminishing heat generated noise generated within the detector in order to enhance detectivity. The improved performance is achieved by applying a pulsed bias to the detector which consists of a sequence of waveforms which reduces the duty cycle of the detector in comparison to a detector subjected to a constant bias. A sophistication of this use of a pulsed bias is the utilization of a swept bias which employs a sequence of waveforms having gradual rise-times which further reduces unwanted detector noise and enhances detectivity.

Abstract: A power supply circuit for a liquid crystal welding lens or shutter develops a relatively low voltage AC signal for driving or powering the liquid crystal shutter to the clear state and two relatively higher or larger magnitude AC electrical signals for initially driving the shutter to the dark state and then for maintaining the shutter in the dark state; a variable frequency circuit for varying the frequency of the driving signal to the shutter to minimize power usage in the dark state and to avoid flicker in the clear state; and power saving and battery level indicator features are included.

Abstract: A print paper detecting circuit for installation on a printer, to detect whether a print paper is supplied at a predetermined position along a paper path by using an optical sensor composed of a light emitting diode and phototransistor. The circuit detects the existence of the print paper according to the detection of light which is emitted from the light emitting diode, which is reflected from the print paper, and which arrives at the phototransistor. According to one embodiment, circuit has a current amplifier and a gain reducing circuit. The current amplifier feeds a pulse current which is greater than the normal constant current to the light emitting diode while the gain reducing circuit reduces the output of the output voltage.