Logarithmic Patents (Class 356/223)
  • Patent number: 8492682
    Abstract: A micro heater includes a first electrode, a second electrode, a first carbon nanotube, and a second carbon nanotube. The first carbon nanotube extends from the first electrode. The second carbon nanotube branches from the second electrode. The first carbon nanotube and the second carbon nanotube intersect with each other to define a node therebetween.
    Type: Grant
    Filed: December 30, 2010
    Date of Patent: July 23, 2013
    Assignees: Tsinghua University, Hon Hai Precision Industry Co., Ltd.
    Inventors: Xue-Shen Wang, Qun-Qing Li, Shou-Shan Fan
  • Patent number: 7756569
    Abstract: It is the object of a method for measuring the vessel diameter of optically accessible blood vessels to measure vessel diameters of optically accessible blood vessels in a simple manner based on digital images and with high accuracy even when the vessel diameter is on an order of magnitude at which the determination of the diameter by image point counting is associated with an unacceptably high error. According to the invention, the vessel diameter is determined photometrically from the logarithmized ratio of the intensities of the reflection of the vessel-free environment of the blood vessel and of the reflection of the blood vessel, which intensities are determined in a first monochromatic image.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: July 13, 2010
    Assignee: IMEDOS GmbH
    Inventors: Martin Hammer, Walthard Vilser
  • Patent number: 7345669
    Abstract: A photometric device of liquid crystal display and a liquid crystal display in which photometry can be performed without relying upon manpower and the liquid crystal plane is shielded only at the time of photometry. The photometric device comprises a liquid crystal display part, a bezel surrounding the four sides of the liquid crystal display, a shaft part provided at the corner part of the bezel and fixed rotatably thereto, a movable part having the end part thereof connected to the shaft part, and a sensor part provided in the liquid crystal display part at the other end part of the movable part.
    Type: Grant
    Filed: March 28, 2003
    Date of Patent: March 18, 2008
    Assignee: Eizo Nanao Corporation
    Inventors: Mitsuo Ohashi, Ikufumi Honda
  • Patent number: 5773816
    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.
    Type: Grant
    Filed: October 7, 1996
    Date of Patent: June 30, 1998
    Assignee: Lucid Technologies Inc.
    Inventor: Scott R. Grodevant
  • Patent number: 5548398
    Abstract: An illuminant discriminator distinguishes a range of separate illuminants, including high efficiency fluorescent lighting, by modifying the frequency response of a signal output from a photodetector. A switchable high pass filter coupled to the photodetector has a first filter section with a first cutoff characteristic selected to pass signal components due to various types of lighting including high efficiency lighting, and a second section with second cutoff characteristic that separates out the high efficiency components. The high pass output is processed by a log amplifier to develop flicker frequency harmonics that are distinguished as to source illuminant by comparator stages. Undersampling artifacts due to high efficiency lighting are present in the mixed illuminant spectrum when the first filter section is operative, and positively identified as high efficiency lighting when the second section is operative.
    Type: Grant
    Filed: November 22, 1994
    Date of Patent: August 20, 1996
    Assignee: Eastman Kodak Company
    Inventor: Michael J. Gaboury
  • Patent number: 5272518
    Abstract: Apparatus for monitoring, converting and calibrating the spectra displayed by a colored object, using wavelength dispersion provided by a variable wavelength filter. The apparatus may serve as a spectrophotometer, as a colorimeter, or as a spectroradiometer or other device that monitors and calibrates a light signal by decomposition of the signal into a wavelength distribution. The apparatus may also be used as part of a feedback network to monitor and correct colors displayed by a color monitor, color printer, color scanner or other similar peripheral device controlled by a computer that is part of the network.
    Type: Grant
    Filed: December 17, 1990
    Date of Patent: December 21, 1993
    Assignee: Hewlett-Packard Company
    Inventor: Kent D. Vincent
  • Patent number: 5233517
    Abstract: Early glaucoma detection by a system and a method of fast Fourier transform analysis of digitized eye fundus images is disclosed. In this system, a red-free photograph of the eye fundus is first converted to digital form, and then the topography is further studied by taking sectional views, each of which is restated as a waveform. Each waveform represents the outline of the hills and valleys or "landscape" of the eye fundus and has a low signal-to-noise ratio. The noise is filtered out by taking adjacent slices and averaging the waveform signals thereof. Optionally, linear regression and window functions are used to eliminate trend and endpoint effects. This reduced digitized data is now the RNFL image in spatial frequency components. Using a fast Fourier transform function to calculate the power spectrum at each spatial frequency, the waveform is graphically represented on a printer/plotter.
    Type: Grant
    Filed: April 30, 1990
    Date of Patent: August 3, 1993
    Inventor: Lawrence F. Jindra
  • Patent number: 5115124
    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.
    Type: Grant
    Filed: March 5, 1991
    Date of Patent: May 19, 1992
    Assignee: Canon Kabushiki Kaisha
    Inventors: Kazuhiko Muto, Takahiro Shirai, Tsunenori Yoshinari
  • Patent number: 5025146
    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).
    Type: Grant
    Filed: July 31, 1989
    Date of Patent: June 18, 1991
    Assignee: Siemens Aktiengesellschaft
    Inventors: Peter Kleinschmidt, Gerhard Mader
  • Patent number: 4914468
    Abstract: A light measuring device calculates and displays a proper exposure condition even when the combination of shutter speed and aperture is predetermined by using a flashlight component and a measured light data.
    Type: Grant
    Filed: March 22, 1988
    Date of Patent: April 3, 1990
    Inventors: Kazuhiko Naruse, Yoshio Yuasa
  • Patent number: 4838698
    Abstract: An extinct type detector which detects and determines a concentration or density of a gas or vapor in a space on the basis of an attenuation of light due to the gas or vapor present within the space.The detector of this feature of the invention operates in such a way that the light emitting device is periodically driven to effect light emission, the first and the second photodetector devices receive the light from said light emitting device, the first and second storage means corresponding to the first and the second photodetector devices, respectively, cumulatively store the outputs from the respective photodetector devices, a difference in cumulative storage values between the first and the second storage means is detected to determine a concentration and density of the gas or vapor within the detecting space based on the detected difference.
    Type: Grant
    Filed: March 31, 1987
    Date of Patent: June 13, 1989
    Assignee: Hochiki Corp.
    Inventors: Hiromitsu Ishii, Takashi Ono
  • Patent number: 4808811
    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.
    Type: Grant
    Filed: October 9, 1987
    Date of Patent: February 28, 1989
    Assignee: Canon Kabushiki Kaisha
    Inventors: Tosiyuki Kumakura, Hiroyuki Kataoka, Kouichi Ohmori
  • Patent number: 4660075
    Abstract: A color information detecting device comprising a plurality of color detecting apparatus for detecting respective different color lights from each other, converting apparatus for producing an output in non-linear relation to the input signal, changeover apparatus for selectively applying the outputs of the color detecting apparatus to the converting apparatus, apparatus for coinciding a number of successive outputs of the converting apparatus, and computing apparatus for computing the coincided signals from the coincidence apparatus. The device also includes a first constant current source for applying current of a prescribed intensity and a second constant current source for supplying current of another intensity equal to the prescribed intensity times the intensity of the current supplied from the first source which are included so that another mode can operate. The outputs of the first and second constant current sources are selectively applied to the converting apparatus.
    Type: Grant
    Filed: October 25, 1984
    Date of Patent: April 21, 1987
    Assignee: Canon Kabushiki Kaisha
    Inventors: Seiji Hashimoto, Shinji Sakai
  • Patent number: 4639134
    Abstract: To amplify an input current present at the input of a circuit arrangement with a feedback-coupled operational amplifier, two virtually equal potentials are built up in two different current paths with a common summing point. By means of the potentials, a current flow is produced for each current path. The current flow in one current path is determined by the input current, and the current in the second current path determined by a suitable choice of the impedances on the first and second current paths. The current in the second current path is greater by a multiple than the current in the first current path.
    Type: Grant
    Filed: June 5, 1984
    Date of Patent: January 27, 1987
    Assignee: Ernst Leitz Wetzlar GmbH
    Inventor: Walter Bletz
  • Patent number: 4518258
    Abstract: A color analyser measuring the light intensities of at least three different colors within the spectrum of the incident light, and relating these measurements to values programmmed before. Those color components of the incident light that have to be influenced in order to conform to the preprogrammed relations are indicated by means of a color star, consisting of three rows of light sources (23, 24, 25) of appropriate colors. While influencing the color of the light with correction filters the operator views the change simultaneously at the color star. It is indicated in such a way that the light sources of the color star are extinguished as soon as the preprogrammed relations between the colors are satisfied, notwithstanding the absolute value of light intensity. An automatic exposure time meter is built in, also controlling an electronic timer (32).
    Type: Grant
    Filed: June 19, 1981
    Date of Patent: May 21, 1985
    Inventor: Harmen Broersma
  • Patent number: 4498753
    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.
    Type: Grant
    Filed: September 16, 1983
    Date of Patent: February 12, 1985
    Assignee: Olympus Optical Co., Ltd.
    Inventor: Kazunori Mizokami
  • Patent number: 4492858
    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.
    Type: Grant
    Filed: June 7, 1982
    Date of Patent: January 8, 1985
    Assignee: Olympus Optical Co., Ltd.
    Inventor: Kazunori Mizokami
  • Patent number: 4465354
    Abstract: A system disclosed is for calculating a light information value, such as an f/stop number, which is determined by a number of light sources such as strobes. The system calculates an optimum f/stop number for each of the strobes as the strobes are fired one after another and, at the same time, calculates after each firing of the strobe an optimum f/stop number for the strobes which have been fired. The optimum f/stop number for the plurality of strobes fired at the same time is displayed.
    Type: Grant
    Filed: July 28, 1982
    Date of Patent: August 14, 1984
    Assignee: Minolta Camera Kabushiki Kaisha
    Inventor: Yoshio Yuasa
  • Patent number: 4442381
    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.
    Type: Grant
    Filed: August 30, 1982
    Date of Patent: April 10, 1984
    Assignee: Fuji Photo Optical Co., Ltd.
    Inventor: Saburo Numata
  • Patent number: 4433914
    Abstract: Disclosed herein are system and apparatus for providing an indication of proper photographic exposure for lighting conditions which include both flash and continuous light sources. An optical sensor provides a signal representative of instantaneous existing lighting conditions either to a logarithmic amplifier for continuous lighting condition measurement or to an integrator controlled by a timer for flash ambient lighting condition measurement. A sample and hold circuit receives the integrator output and provides the same to the logarithmic amplifier which is calibrated with respect to the optical sensor. The logarithmic amplifier supplies either continuous or flash exposure indicia to a display, which may comprise either a digital display or a motorized dial. An accessory program input is provided between the logarithmic amplifier and the display to receive compensating signals from optical accessories that may be mated to the optical sensor.
    Type: Grant
    Filed: September 14, 1979
    Date of Patent: February 28, 1984
    Assignee: Vivitar Corporation
    Inventor: Kenneth J. Curran
  • Patent number: 4390258
    Abstract: A photometric circuit includes a differentiator arranged in cascade connection with an integrating circuit including an integrating capacitor which directly integrates a photocurrent produced by a photoelectric transducer element which is used for photometry. In this manner, a photocurrent output is derived from the integrated output from the integrating circuit.
    Type: Grant
    Filed: November 30, 1981
    Date of Patent: June 28, 1983
    Assignee: Olympus Optical Co. Ltd.
    Inventor: Kazunori Mizokami
  • Patent number: 4338033
    Abstract: A densitometer comprising a recorder so adapted as to be capable of recording a set of analytical data obtained with a photometric system twice at a definite recording interval, an index arranged at a position apart by a distance equal to said recording interval from the recording pen of said recorder, a switch for setting boundary point and another switch commanding erasure of boundary point, said densitometer being so adapted as to permit setting and erasing boundary point by using the first recorded densitogram and said index.
    Type: Grant
    Filed: June 2, 1980
    Date of Patent: July 6, 1982
    Assignee: Inoue-Japax Research Incorporated
    Inventors: Yutaka Kato, Ryo Fujimori
  • Patent number: 4332469
    Abstract: An improved light intensity measuring device includes a temperature compensating logarithmic amplifier that changes photodetector currents which have been converted from AC to DC to a voltage which drives an analog to digital converter. The resulting digital signals are displayed. For differential or absolute measurements, a second, identical, logarithmic amplifier channel is employed and both are coupled to a differential amplifier. A standard reference current applied to one channel provides an "absolute" measurement of the signal applied to the other channel or a second signal may be compared to the first.
    Type: Grant
    Filed: March 14, 1980
    Date of Patent: June 1, 1982
    Assignee: Photodyne, Inc.
    Inventor: Paul H. Wendland
  • Patent number: 4309604
    Abstract: Disclosed is a solid state wavelength detection system responding to output signals derived from a photoelectric semiconductor device. The photoelectric semiconductor device comprise at least two PN junctions formed at different depth from the surface of the semiconductor substrate. A deeper PN junction develops an output signal related to longer wavelength component of the light impinging thereon. A shallower PN junction develops an output signal related to shorter wavelength component of the impinging light. These two output signals are logarithmically compressed and compared with each other. Difference of the logarithmically compressed output signals represents the wavelength information of the impinging light.
    Type: Grant
    Filed: July 24, 1979
    Date of Patent: January 5, 1982
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Toshihumi Yoshikawa, Zempei Tani, Akira Aso, Hitoshi Kawanabe
  • Patent number: 4306807
    Abstract: In the disclosed system, a light measuring circuit having a logarithmical amplifier, is constructed to produce pulses at a frequency corresponding to the output of the light measuring circuit. Pulses are counted during a time interval corresponding to the temperature characteristic of the light measuring circuit so as to obtain a count value corresponding to the light input free of the influence of temperature.
    Type: Grant
    Filed: June 4, 1979
    Date of Patent: December 22, 1981
    Assignee: Canon Kabushiki Kaisha
    Inventors: Toshio Sakane, Tokuichi Tsunekawa
  • Patent number: 4249825
    Abstract: Glaucoma and other diseases may be detected by the analysis of angiograms to determine ocular blood flow. Using rapid sequence photography an ocular image is recorded on successive film frames. To determine the optical density of the film at selected image sites, the image position on the frames being subject to change from frame to frame, each frame is initially positioned manually at a starting position relative to a density sensing system. Then, X-Y stepping motors move the film under control of a digital processor to position the film frame at each selected image site. A detector is insensitive to light from a viewing optical system because of a filter included in that system. A crosshair image-point indicator is included on a filter in the viewing system.
    Type: Grant
    Filed: May 14, 1979
    Date of Patent: February 10, 1981
    Assignee: The Trustees of Boston University
    Inventor: Jerrold M. Shapiro
  • Patent number: 4247186
    Abstract: A photometric circuit for a camera including a first operational amplifier with a photo-electric element connected between its inverted and non-inverted input terminals and, a logarithmic compression diode connected between the output terminal and the inverted input terminal of the first operational amplifier, thus providing a voltage corresponding to the logarithmic value of the brightness of an object to be photographed at the output terminal of the first operational amplifier.A second operational amplifier has a plurality of temperature compensating commonly polarized diodes connected in parallel between its inverted input terminal and the output terminal. A first constant voltage is applied to the non-inverted input terminal of the second operational amplifier while a second constant voltage is applied through a resistor to the inverted input terminal of the second operatonal amplifier, thereby providing temperature-compensation of the output voltage of said first operational amplifier.
    Type: Grant
    Filed: June 19, 1979
    Date of Patent: January 27, 1981
    Assignee: Canon Kabushiki Kaisha
    Inventors: Masanori Uchidoi, Hiroshi Aizawa, Kazunobu Urushibara, Nobuyuki Suzuki, Masami Shimizu
  • Patent number: 4241279
    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.
    Type: Grant
    Filed: February 9, 1979
    Date of Patent: December 23, 1980
    Assignee: Fuji Photo Optical Co., Ltd.
    Inventor: Saburo Numata
  • Patent number: 4229108
    Abstract: In a preferred embodiment of the present invention, an optical densitometer is provided having an improved output scale resolution. An output scale reading from 0.000 to 4.000, having a resolution to 0.001, is obtained by improved method and apparatus for obtaining the reference operating characteristics for "zero-mode" parameters. An analog reference anode signal is formed by making adjustments in a generally antilogrithmic relationship to the difference between the reference anode signal being generated and the anode signal produced under the zero-mode conditions. The antilogrithmic relationship improves scale resolution near the zero point and increases densitometer stability during a subsequent measurement cycle. The combination analog reference anode signal generating circuit and an improved exponential characteristic selection circuit enables the improved output resolution and accuracy to be obtained.
    Type: Grant
    Filed: June 8, 1978
    Date of Patent: October 21, 1980
    Assignee: Graphic Arts Manufacturing Company
    Inventor: Warren Childers
  • Patent number: 4229107
    Abstract: In a preferred embodiment of the present invention, method and apparatus are provided for converting an input light intensity representing an optical density to a standard industry scale reading. A photomultiplier tube is operated with a constant anode current corresponding to a reference, or "white" sample, and the dynode voltages varied to obtain the constant anode current. The resulting dynode voltage forms a signal linearly related to the input light intensity. A reference exponential characteristic is selected from an envelope of such characteristics, the selected characteristic cooperating with the photomultiplier tube characteristics. The exponential characteristic envelope may be conveniently formed by resistor-capacitor decay circuits with charging and discharging characteristics compatible with the range of photomultiplier tube parameters to be accommodated, where the envelope curve boundaries cross at a selected reference point.
    Type: Grant
    Filed: June 8, 1978
    Date of Patent: October 21, 1980
    Assignee: Graphic Arts Manufacturing Company
    Inventor: Warren Childers
  • Patent number: 4207533
    Abstract: An economical Cds photoresistor is connected to the input of an operational amplifier. Logging diodes are connected in a feedback configuration with the operational amplifier through a galvanometer meter. The log of the ratio of the input currents to the operational amplifier is independent of supply voltage thereby permitting the use of a wide tolerance battery supply. The input of the operational amplifier and the meter are referenced to a voltage divider. A feedback connection regulates meter current independently of meter resistance that varies strongly with ambient temperature changes. Light-emitting diodes provide regulation against battery voltage variation, light for meter scale illumination, and an inherent, unfailingly diagnostic battery-check response.
    Type: Grant
    Filed: April 12, 1978
    Date of Patent: June 10, 1980
    Inventor: John I. Smith
  • Patent number: 4199753
    Abstract: An integrated circuit employing a photo-diode activates an alarm when an intruder causes a change in the ambient light patterns by more than about 5% in an area under surveillance. The circuit includes a voltage regulator for supplying a back bias voltage to the photo-diode which voltage is substantially purged of noise that may be superimposed on the main d.c. supply voltage conductors. The regulator circuit includes a modified current-mirror type current source and a V.sub.BE -multiplier circuit providing a log-log noise transfer function.
    Type: Grant
    Filed: February 15, 1978
    Date of Patent: April 22, 1980
    Assignee: Sprague Electric Company
    Inventor: Walter S. Gontowski, Jr.
  • Patent number: 4184151
    Abstract: A circuit system designed to realize fully digitalized automatic exposure controls is provided in which the read-in brightness information is logarithmically compressed directly into a digital quantity without the aid of any diode element that exhibits a logarithmic characteristic. This enables full utilization of the merits of digitalization while affording further advantages including increased stability against temperature and voltage variations.
    Type: Grant
    Filed: March 3, 1977
    Date of Patent: January 15, 1980
    Assignee: Nippon Electric Co., Ltd.
    Inventor: Shigehisa Iwata
  • Patent number: 4166696
    Abstract: A photometer for providing a measurement of shutter speed or aperture setting corresponding to a preselected value of the other comprises a photodiode supplying a voltage proportional to the logarithm of the measured light intensity. This voltage controls the frequency of an oscillator supplying pulses to a counting circuit during a time interval set by a timer.
    Type: Grant
    Filed: April 29, 1977
    Date of Patent: September 4, 1979
    Assignee: Pignons S.A.
    Inventor: Charles L. Rochat
  • Patent number: 4125330
    Abstract: Photometric apparatus for use as a color analyser or color temperature meter or graphic arts photometer has a logarithmic photometer, means for storing the analogue output of the photometer combined with a reference signal, and means for comparing the stored signal with a subsequent photometer output signal connected by a different reference signal. In a color analyser or color temperature meter switchable color filters are provided with automatic switching of the reference signals in accordance with the color section.
    Type: Grant
    Filed: December 11, 1975
    Date of Patent: November 14, 1978
    Assignee: Electrical Instrumentation Co. Ltd.
    Inventor: Felix Schild
  • Patent number: 4099885
    Abstract: A digital exposure meter display circuit for a camera includes a first oscillator 1 whose output controls the charging of an integrating capacitor 28 from a constant current source 3. When the capacitor charge reaches the level of a reference voltage from source 7, as detected by a first comparator 6, a counter 10 is enabled and begins to register clock pulses from a second oscillator 8 through an AND gate 31. When the capacitor charge subsequently reaches the output level of a light measuring circuit 4, which is proportional to the apex value of the sensed object brightness, a second comparator 5 disables the AND gate and enables an LED display 12 supplied with the decoded counter value.
    Type: Grant
    Filed: November 12, 1976
    Date of Patent: July 11, 1978
    Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
    Inventors: Masahiro Kawasaki, Eiichi Tano
  • Patent number: 4072962
    Abstract: A metering device comprises a photoelectric converter circuit for generating a first voltage corresponding to the brightness of a subject to be photographed. The converter circuit includes a photoelectric converter element and a first conductor element for logarithmically converting the output of the photoelectric converter element. The device further comprises a voltage generating circuit including a second semiconductor element and a current source for flowing a current proportional to an absolute temperature to a resistor connected in series to the second semiconductor element. The voltage generating circuit is effective to generate a second voltage comprising the sum of the voltages generated in the resistor and the second conductor element. The difference beween the first and the second voltage is put out by a differential amplifier.
    Type: Grant
    Filed: June 29, 1976
    Date of Patent: February 7, 1978
    Assignee: Nippon Kogaku K.K.
    Inventor: Osamu Maida
  • Patent number: 4051490
    Abstract: An exposure meter circuit includes a photo diode 2 and associated components 1, 3-6 for producing a first logarithmically compressed voltage V.sub.1 proportional to the apex value B.sub.v of the sensed brightness level. The temperature characteristic of the transistor 1 coupled to the diode 2 is compensated for by developing a second logarithmically compressed voltage V.sub.2 and subtracting V.sub.1 from it in an operational amplifier 9. The voltage V.sub.2 is produced by a transistor 11 whose base is coupled to the cathode of a light emitting diode 13 and whose collector output is returned to the power supply through a diode wired transistor 12. The temperature characteristic of the LED is the same as that of a transistor, whereby compensation is realized.
    Type: Grant
    Filed: November 10, 1976
    Date of Patent: September 27, 1977
    Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
    Inventor: Masahiro Kawasaki
  • Patent number: 4047819
    Abstract: Apparatus for measuring the optical density of a sample includes a dual beam spectrophotometer producing sample and reference signals which are compared with the discharge curve of a resistive-capacitive circuit to provide start-stop signals, the time interval between the two signals being indicative of optical density. Embodied within this linearization means is a novel method of correcting for nonlinearities due to stray light. The start and stop signals are used to drive a linear ramp generator, the stop signal terminating the ramp at an analog signal level indicative of optical density.
    Type: Grant
    Filed: April 10, 1975
    Date of Patent: September 13, 1977
    Assignee: Smith Kline Instruments, Inc.
    Inventor: Paul R. Goldberg
  • Patent number: 4045142
    Abstract: In a metering device for cameras comprising an operational amplifier, a photodiode connected between the positive and the negative input terminal of the operational amplifier, and a logarithmic conversion diode connected between the negative input terminal and the output terminal of the operational amplifier, the electric charge stored in the capacity present in the photodiode due to noise may be discharged to a capacitor which is adapted to reduce its potential in synchronism with the output potential drop of the operational amplifier.
    Type: Grant
    Filed: April 29, 1976
    Date of Patent: August 30, 1977
    Assignee: Nippon Kogaku K.K.
    Inventor: Sakuji Watanabe
  • Patent number: 4029421
    Abstract: This invention relates to a digital exposure meter in which brightness information is digitized and exposure factors such as film sensitivity are converted to digital values to perform digital computation. Accordingly, an exposure value, average exposure value, aperture value or shutter time is derived while a computer having various operation functions being controlled in sequence by sequence control means.
    Type: Grant
    Filed: October 16, 1975
    Date of Patent: June 14, 1977
    Assignee: Canon Kabushiki Kaisha
    Inventors: Nobuaki Sakurada, Nobuhiko Shinoda, Yukio Mashimo, Tadashi Ito, Fumio Ito
  • Patent number: 3992113
    Abstract: Photometer circuitry includes a capacitor discharge means for establishing a time period related to the light absorption properties of a test sample. The time period is used, in conjunction with a frequency generator to drive a digital counter to provide a digital indication of light absorption.
    Type: Grant
    Filed: April 21, 1975
    Date of Patent: November 16, 1976
    Inventors: Bruno Egli, Manser Niklaus
  • Patent number: 3977011
    Abstract: An automatic exposure control system for regulating one or more variable photographic parameters. The light level of a scene is evaluated using a photosensitive voltage source. A differential amplifier with a non-linear negative feedback is provided to allow one or more inexpensive linear potentiometers to be used to enter the aperture value and film sensitivity information into the system. Based on these parameters, the system automatically controls the camera shutter speed.
    Type: Grant
    Filed: March 6, 1975
    Date of Patent: August 24, 1976
    Assignee: Minolta Camera Kabushiki Kaisha
    Inventor: Motonobu Matsuda