Abstract: According to the present invention, a photomultiplier tube is used with a high-speed feedback mechanism to continuously modulate the gain of the tube in response to the size of the input signal. The gain of the tube and the anode current are independently converted to ideal logarithms. These signals are then subtracted from one another to reconstruct a true logarithmic representation of the optical signal. This log-light-level signal has a higher dynamic range and faster temporal response than has previously been achieved by other methods.

Abstract: A circuit is provided for adjusting an operating point of an opto-electronic element having a saturation voltage and which constitutes a component of a receiver for alternating light useful signals and which generates current during a short-circuit operation and voltage during a no-load operation. The circuit comprises a resistive circuit connected in parallel with the opto-electronic element for adjusting the operating point of the opto-electronic element below the saturation voltage for the compensation of constant light signals. The resistive circuit includes an automatic control resistor which changes its resistance as a function of voltage when a specific voltage below the saturation voltage is exceeded for loading the opto-electronic element until the specific voltage is essentially reached.

Abstract: An improved photodetector integrator circuit is provided having a photodetector, such as a photodiode, which produces photocurrent responsive to incident illumination. The photodetector is coupled to an integrator stage which converts the photocurrent into voltage and integrates the voltage over an integration period to provide an output signal. A window comparator in the circuit receives the output signal from the integrator stage and compares the output signal to a first threshold and a second threshold to provide, as a measurement signal, a pulse having a width which corresponds to the time interval over which the output signal increases from the first threshold to the second threshold. In the window comparator, the second threshold is greater than the first threshold.

Abstract: An optoelectronic device for measuring the ground contact time and position of a body within a preset region, having a first measurement bar, which includes one or more infrared light beam transmitters, and a second measurement bar, which is arranged opposite and parallel to the first bar and includes one or more receivers, the number whereof is equal to the number of transmitters present in the first bar. The first and second bars are connected one another by means of an electrical line and form a measurement area therebetween.

Abstract: Corrective factors are applied so as to remove anomalous features from the signal generated by a photoconductive detector, and to thereby render the output signal highly linear with respect to the energy of incident, time-varying radiation. The corrective factors may be applied through the use of either digital electronic data processing means or analog circuitry, or through a combination of those effects.

Abstract: A toner depositing amount measuring apparatus for measuring the amount of toner deposited on a photosensitive drum includes a light source for irradiating the surface of the photosensitive drum with light and a photoelectric converting section for receiving the reflected light and converting the received reflected light into an electric signal. A logarithmic calculation is applied to the output signal of the photoelectric converting section in a logarithm-compressing section. The temperature characteristics of the logarithm-compressing section are compensated for in a temperature compensating section. The amount of the toner deposition is calculated in a toner depositing amount calculating section based on a difference between the data during non-deposition of the toner and the data during deposition of the toner, the data being obtained from the logarithm-compressing section.

Abstract: A photometering circuit comprises a photo-diode, an operational amplifier, a feedback diode and a latch releasing transistor. In a circuit utilizing a PNP transistor, for example, a cathode of the photo-diode is connected to a non-inverting input terminal of an operational amplifier and a reference potential, an anode of the photo-diode is connected to an inverting input terminal of the operational amplifier and an anode of the feedback diode, a cathode of the feedback diode is connected to an output terminal of the operational amplifier, a base of the PNP transistor is connected to the reference potential and a collector of the PNP transistor is connected to the inverting input terminal of the operational amplifier.

Abstract: A corrective factor is applied so as to remove anomalous features from the signal generated by a photoconductive detector, and to thereby render the output signal highly linear with respect to the energy of incident, time-varying radiation. The corrective factor may be applied through the use of either digital electronic data processing means or analog circuitry, or through a combination of those effects.

Abstract: A measuring device comprises a detector (1) for a quantity x to be measured, which detector is adapted to produce two signals I.sub.1 and I.sub.2 which relate to x as x=(I.sub.1 -I.sub.2)/(I.sub.1 +I.sub.2). The device further comprises a processing circuit (3) which includes a first and a second logarithmic converter (9, 11) whose inputs receive input signals V.sub.1 and V.sub.2 which are proportional to the first and the second measuring signal I.sub.1, I.sub.2, respectively. The outputs of the logarithmic converters are connected to first and second inputs (12A, 12B) of a subtractor circuit (13) which produces at its output (14) an output signal U(x) which depends on the quantity x to be measured. If a subtractor circuit is used which is adapted to determine the hyperbolic tangent of the difference between the signals logV.sub.1 and logV.sub.2 present at its two inputs (12A, 12B), the relationship between u(x) and x will be linear.

Abstract: The semiconductor optical position sensing device comprises an optical position sensing element having two electrodes for generating two photoelectric currents changeable according to an optical position between the two electrodes, two current mirror circuits for converting the two photoelectric currents into two currents respectively; two transistors for converting the two currents into two voltages, respectively; two source followers; and a differential circuit connected between the two transistors via the two source followers, respectively, for differentially generating an optical position current signal on the basis of the two converted voltages. Further, the two source followers are composed of four parallel connected JFETs diagonally arranged close to each other in mutual intersectional positional relationship with respect to each other. Additionally, the two constant current sources are composed of four similarly-arranged JFETs.

Abstract: A semiconductor photo-sensor comprising a photo-sensor area for converting an optical signal to an electrical signal, and a signal processing circuit for processing the electrical signal. The photo-sensor area and the signal processing circuit are formed on one semiconductor substrate.

Abstract: A method for the analysis of blood platelet aggregations consists in that concurrently two parameters are measured the mean intensity and the RMS deviation of intensity of the light flux which had been passed through a blood sample (I2) from said means intensity, which is caused by fluctuations of the amount of blood platelets or their aggregations in the optical channel (I0), which are used to find the mean radius and concentration of blood platelets in the blood sample (I2) being tested. The apparatus also comprises a source (6) of the light flux, a photoreceiver (I1), units (I7 and I9) to form the mean intensity and the RMS deviation of current intensity from the means intensity, and a unit (20) for determination of parameters of a blood platelet aggregation.

Abstract: Optical sensor line of amorphous or polycrystalline photo-electric material having a plurality of sensor elements. An optical sensor line of amorphous or polycrystalline photo-electric material having a plurality of sensor elements, whereby it is provided that a non-linear element is allocated to each sensor element as a converter that converts the photo-current (i.sub.ph) of the associated sensor and which is proportional to the quantity of light incident on the sensor into a signal voltage (u.sub.s) that is at least approximately proportional to the logarithm of the photo-current (i.sub.ph).

Abstract: A photosensor, or an image sensor made of many such photosensors, including a plurality of photosensor pixels each having a logarithmic converter. The logarithmic converter converts source charges that are produced by a photoreceptor (or a photodiode) and proportional to the amount of the incident light into signal charges logarithmically proportional to the source charges whose amount does not grow so rapid as the amount of source charges grows. Owing to the logarithmic converter, the dynamic range of the photosensor (or image sensor) has a very wide dynamic range.

Abstract: A compressed analog signal strength indicator that produces a light signal proportional in intensity to the relative alignment of an associated photoelectric transmitter and photoelectric receiver pair is disclosed. A sensor (10) detects a light signal (18) received from the associated photoelectric transmitter and produces an electrical signal. A nonlinear circuit (12) compresses the electrical signal and supplies an output to a peak hold circuit (13), which controls the current flow to an indicator (14). A threshold detection loop, which includes: a demodulator (15); an integrator (16); and, a comparator (17), senses the amplified signal of sensor (10) and produces a noticeable step increase in the brightness of the indicator (14) when the light signal (18) is first detected by the sensor (10).

Abstract: A position sensor has a photosensitive element including a pn junction formed between first and second electrodes for providing first and second photocurrents varying in dependence on the position of an illuminated spot between the first and second electrodes, and a processing circuit including an current converting circuits for producing first and second detection currents corresponding to the first and second photocurrents, a first sum current equal to a sum of the first detection current and twice the second detection current and a second sum current equal to a sum of the second detection current and twice the first detection current, a logarithmic converting circuit for producing first, second, third and fourth voltages which are in logarithmic relationships with the first detection current, the first sum current, the second sum current and the second detection current, respectively, differential circuits for producing first and second differential output currents from a difference between the first and s

Abstract: A light measuring circuit including a light sensing device for sensing light and producing a signal representative of the light sensed, a compressing circuit for compressing the signal, a capacitor having one terminal connected to a predetermined voltage, a charging circuit responsive to the compressing circuit for charging the capacitor, a detecting circuit for responding to the voltage level of the capacitor, a switch for shorting the capacitor when closed for initiating charge of the capacitor by opening, and a delay circuit coupled to one of the charging circuits and the switch for delaying the onset of charge of the capacitor.

Abstract: A circuit containing a photodiode for determining when there is sufficient illumination for an optical device to operate having provision for compensating signal variations due to temperature-dependent operation of the photodiode by supplying logarithmic means with an input from a potentiometer connected to a temperature-dependent distributor circuit.

Abstract: There is provided a photoelectric switch in which a beam reflected by an object to be detected is received in a trigonometric manner so that any failure in the distance measurement of the object can be prevented with employment of ordinary amplification circuit for received-light signals without enlarging the figure of the dynamic range of the circuit. In the switch, a circuit for comparing the ratio of the received-light signals to a predetermined operational level includes means for setting the nearest limit point for a set range of a detecting area to be farther than an intersection of the projected light beam with a line connecting centers of light-receiving lens and received-light detecting element so that the detection of the object can be made even when the dynamic range of the amplification circuit is saturated, whereby the presence of the object in the detecting area can be always discriminated even upon the dynamic range saturation of the amplification circuit.

Abstract: An attenuation measuring system includes a transmitter for generating and transmitting a signal from a first position to a second position, and a receiver adapted to receive the signal at the second position. One of the transmitter and the receiver includes a simple log converter circuit which permits the conversion of an analog signal to a digital signal, so that a time uniform train of pulses is developed, the pulses decreasing in amplitude by equal decibel values. The receiver includes a counter which is counted down from a preset value. The count of the counter is a direct measurement of the loss through a coupling medium between the transmitter and the receiver. The analog-to-digital conversion can be accomplished in either the transmitter or the receiver. When embodied in the receiver, the attenuation meter also can function as an optical power meter.

Abstract: A light-operated proximity detector is described in which reflected light intensity from a surface whose proximity to the detector is to be gauged is translated directly into a signal proportional to the distance of the detector from the surface. A phototransistor is used to sense the reflected light and is connected in a detector circuit which maintains the phototransistor in a saturated state. A negative feedback arrangement using an operational amplifier connected between the collector and emitter of the transistor provides an output at the output of the amplifier which is linearly proportional to the proximity of the surface to the detector containing the transistor. This direct proportional conversion is true even though the light intensity is varying with the proximity in proportion to the square of the inverse of the distance. The detector may be used for measuring the distance remotely from any target surface.

Abstract: A photometric apparatus for a camera comprises a reference voltage circuit; an operational amplifier including a photoelectromotive element for photometry, an output terminal of said reference voltage circuit and an input terminal of said amplifier being connected through an impedeance element to a voltage divider tap of a battery; and a switching circuit for switching said reference voltage circuit to an operable condition as well as for changing set resistors which apply a bias current to said operational amplifier, in synchronism with a shutter releasing operation.

Abstract: A photometric circuit comprises an operational amplifier including a plurality of differential amplifiers, a constant current bias circuit for supplying a constant current bias to the differential amplifiers, and a bias control switching circuit which selectively connects the constant current bias circuit to one of the plurality of differential amplifiers in response to an external signal. A plurality of photoelectric transducer elements, used for purpose of photometry, are connected to differential inputs corresponding to the plurality of differential amplifiers, and the transducer element is selectively enabled for photometry in accordance with the external signal.

Abstract: Disclosed is a temperature compensation system for light measuring circuits. Said system compensates for the change, over temperature, of the output of the light measuring circuit by applying a bias source with a predetermined temperature coefficient. The system is designed so the bias voltage source is derived from the V.sub.BE (base to emitter voltage) difference between a pair of transistors, which difference is generated by the difference of current density at the junction of the pair of transistors obtained by flowing a pair of currents with a constant ratio independent of temperature.

Abstract: An auto strobe control circuit comprising a flash stopping signal generating circuit for measuring the luminance of an object exposed to light emitted from a flash tube by a photometric circuit, sending the obtained photometric value, film sensitivity information and aperture information to an operational amplifier to subject them to an arithmetic operation, and generating a flash stopping signal when the value calculated by the arithmetic operation, reaches a predetermined light amount. The photometric circuit essentially consists of a photoelectromotive force type light receiving element and a log-conversion diode connected in series with a constant-voltage circuit, and a temperature compensation circuit connected with the log-conversion diode. The photometric value is sent from a connection point between the light receiving element and the log-conversion diode to the operational amplifier. A voltage follower is positioned between the temperature compensation circuit and the log-conversion diode.

Abstract: A light quantity control device for controlling the quantity of light emitted from a light source supplied with a.c. power through a bidirectional switching element is disclosed which comprises an integrating circuit for integrating an electric signal corresponding to the quantity of emitted light to produce a light quantity signal varying in accordance with a change in quantity of emitted light and another integrating circuit for integrating the light quantity signal with a predetermined period to produce an exponentially rising signal for every predetermined period, and in which the output of the latter integrating circuit is compared with a reference value to obtain a control signal having a duration time corresponding to the results of comparison, and the switching element is controlled by the control signal to perform a phase control for the a.c. power.

Abstract: The invention provides apparatus for measuring the rate of flow of liquid being circulated in a closed loop system by a pump using a bolus of indicator injected suddenly into the system upstream of the pump and a sampling station downstream of the pump. The apparatus includes signal means for location at the sampling station to provide an electrical signal proportional to the indicator passing this station. The electrical signal has an increasing portion, a decaying exponential portion, and a distorted portion caused by recirculation of the indicator in the system. A signal analyzer is coupled to the signal means to receive the electrical signal and includes a wave generator sensitive to the exponential portion and including extrapolation means for providing a portion of the exponential curve lost by interference by recirculation. The signal analyzer provides an output signal corresponding to the increasing portion, the exponential portion, and the portion provided by the extrapolation means.

Abstract: In an automatic electronic flash light device, a light measuring circuit includes an operational amplifier, a photosensor connected between the positive and negative inputs of the operational amplifier and a diode for log-compression connected in a feedback circuit of the operational amplifier. The output of the light measuring circuit is thus log-compressed and the log-compressed output is applied to an operational circuit which gives an output for controlling exposure.

Abstract: A double beam optical null spectrophotometer having sample and reference optical beam paths, a detector common to both paths, and an attenuator feedback loop from the detector for adjusting the position of an optical attenuator in the reference beam path to balance the energy in the two paths. The slider of an attenuator transmitting potentiometer follows the position of the optical attenuator and a signal level sensitive impedance network connected to the slider calibrates the potentiometer such that an output signal therefrom indicates the true transmittance of a sample in the sample beam path over a range of transmittance values from zero to one hundred percent transmittance.

Abstract: A photoelectric current log-compression circuit includes a log-conversion diode, a photodiode and an operational amplifier for log-compression. In the negative feedback circuit of the operational amplifier is inserted a thermistor to control the amplification degree of the operational amplifier according to the current flowing through the log-conversion diode. Further, a forward voltage of a temperature compensating diode biased with a constant current is applied to the reference voltage of the operational amplifier.

Abstract: This invention has particular utility in the field of absorption spectrophotometry or colorimetry, and is particularly applicable, when incorporated in such type of equipment, as a sample detector to enable direct readings to be taken in concentration or absorbance of sample fluids or the like.

Abstract: A light emitting diode is driven by an input signal and electromagnetically coupled to a photodiode. The photodiode is connected to a high impedance load across which is obtained a signal linearly related to but electrically isolated from the input signal.