Abstract: A device for automatically detecting a proper focusing state of an image-forming optical system e.g. for a photographic camera such as a single-lens reflex camera and the like, comprises a mechanism for splitting a beam of light incident through the optical system. The device does not depend intrinsically upon a current state of polarization of the incident light-beam.The mechanism for splitting a beam of light comprises a two-component lens arrangement which divides the incident beam of light into two beams of light, and a phase-shifting plate behind one of the components for lengthening the effective optical path of one of the split beams with respect to the other split beam. A first a second array of light-sensing elements is provided for receiving both of the split beams of light for evaluating and comparing the sharpness and other characteristics of the two beams of light.

Abstract: A photosensor apparatus for detecting focal position or the like, which uses a plurality of light-receiving elements arranged in a matrix array, is disclosed. Simultaneous light integration is started with respect to all the light-receiving elements, while all the outputs of the light-receiving elements are progressively scanned immediately after the start of the simultaneous light integration. When at least one of the outputs reaches a first reference level, all the outputs are held. If at least one of the held outputs is above a second reference level of a different level, check as to whether all the outputs are below the second reference level is repeatedly done for progressively reducing light integration periods until all the outputs of the light-receiving elements are at a fixed level.

Abstract: A light beam splitter for splitting a light beam from a focusing lens to obtain two split light beams incident on respective light receiving elements, as a pair, wherein a total reflection film is formed to one side of a substantial boundary surface constituted by a plane containing the optical axis of said focusing lens so that said light beam is split into two by said total reflection film, and said pair light receiving elements are disposed such that the split light beam transmitted through a region free from said total reflection film is received by one of the light receiving elements while the split light beam reflected in a region where said total reflection film is situated is received by the other light receiving element.

Abstract: A method of focus detection is disclosed, in which at least two pairs of light receiving element rows are arranged with respect to a photographing lens, and light splitters, each of which wave front splits the light flux from the photographing lens into two light fluxes, are provided for the respective light receiving element rows in the light receiving element row pairs. Light intensity distributions detected by the light receiving element rows at least between two light receiving element row pairs are compared to determine whether an image forming plane is in pre- or post-focus or in focus. Contrast signal values of the object image detected from the light receiving element rows between the light receiving element rows of at least one of the light receiving element row pairs are compared to determine whether the image forming plate is in pre- or post-focus or in focus. The result of at least either comparison is used for focus adjustment.

Abstract: A light beam splitter includes a splitter lens a light flux splitter, in which a splitter lens is disposed such that a light beam, having passed through substantially one half of the light emission area of a focusing lens defined by a substantial border line constituted by a straight line passing through the center of the light emission area and dividing the area into two regions, is incident on light receiving elements in one of two light receiving element arrays and a light beam having passed through the other region is incident on light receiving elements in the other light receiving element array individually corresponding to the first-mentioned light receiving elements.

Abstract: An apparatus for comparing analog signals delivered from a number of light detecting elements with analog signals delivered from a digital-analog converter by means of a plurality of comparator circuits whose output analog signals are supplied as write enable signals to a plurality of digital memories which are controlled by means of digital signals delivered from a central control circuit such that an illumination intensity information of each picture element is read out as the digital signal in the digital memories, thereby obtaining a signal of detecting a focal point of cameras or the like optical devices.

Abstract: A focus detection system is provided in which an image of an object is projected onto an array comprising a plurality of light acceptor elements, formed by photoelectric elements, to cause them to produce photoelectric signals in accordance with the distribution of light intensity of the image. The photoelectric signals are converted into digital equivalents, and an absolute magnitude of a difference between digital signals of adjacent elements is calculated. These absolute magnitudes are arranged in the sequence of their magnitude, and a given number of them is accumulated, starting from the largest one. The accumulated value is utilized as the value of an evaluation function which indicates the sharpness of the image.

Abstract: A method of comparing analog signals delivered from a number of light detecting elements with analog signals delivered from a digital-analog converter by means of a plurality of comparator circuits whose output analog signals are supplied as write enable signals to a plurality of digital memories which are controlled by means of digital signals delivered from a central control circuit such that an illumination intensity information of each picture element is read out as the digital signal in the digital memories, thereby obtaining a signal of detecting a focal point of cameras or the like optical devices.

Abstract: An automatic microfilm retrieval system for retrieving contents of a dictionary or the like recorded on a microfilm and displaying them on a screen is disclosed. Said microfilm includes a retrieval cord and divided into a plurality of unit regions to be displayed on said screen at the same time and further includes a cord added to each of said unit regions and representing an index word whose contents are included in each of said unit regions. A plurality of said unit regions are assembled into a plurality of groups. To each of said groups are added cords representing first and last index words included in each of said groups. Provision is made of a subtracter which functions to compare said cords read out by a reading head with key inputs obtained by depressing keys provided on a key board and control movements of a movable stage holding said microfilm thereon, thereby retrieving said microfilm.

Abstract: A device for modulating the intensity of light rays generated from a gas laser in which an input modulating signal is supplied to a switching element included in a modulating current supply source connected across a gas laser discharge tube to control the discharge current and hence modulate the laser light output. The gas laser discharge tube is eventually subjected to the influence of a magnetic field so as to stabilize the laser light output and modulating characteristic.