Abstract: In a relief valve of the type including a main valve unit incorporating a main valve member (poppet) adapted for engagement with a cylindrical member and a pilot valve unit for controlling a fluid pressure whereby an inlet port of the main valve unit is communicated with a control chamber of the pilot valve unit by an internal pilot passage through a choke formed in a seat member of the pilot valve unit, the choke is formed with an expanded portion having a closed end and through holes for directly communicating the expanded portion with the internal pilot passage and/or the cylindrical member is composed of a unitary-construction member formed with a plurality of flow paths communicated with one another.

Abstract: A spool of a valve main body is switched and driven by exciting a solenoid coil by supplying a DC or AC voltage. An intensity of the magnetism generated by the excitation of the solenoid coil is detected by a magnetic sensor. When a predetermined sensor output is obtained, an indicator lamp is lit to indicate that the spool has operated correctly. The intensity of the magnetism due to the DC excitation is detected by magnetoresistive devices. The intensity of magnetism due to the AC excitation is detected by a pickup coil or a current transformer.

Abstract: A strain detector which has a driven shaft for receiving a stress; a high magnetostrictive rate magnetic layer made of one of Co--B, Co--P, Co--Ni--B, Ni--Fe--P, and Co--Ni--P formed by electroless plating on the outer periphery of the driven shaft; and a detecting coil disposed through a gap on the periphery of the magnetic layer for detecting a variation in the permeability by a strain responsive to the stress of the magnetic layer, a method for manufacturing the strain detector which has the steps of forming a high magnetostrictive plating layer made of one of Co--B, Co--P, Co--Ni--B, Ni--Fe--P and Co--Ni--P by electroless plating on the periphery of the driven shaft; and selectively removing the plating layer to obtain a magnetic layer made of a plurality of magnetic pieces aligned in parallel at a predetermined angle with respect to the central axis of the driven shaft.

Abstract: A zoom lens comprises a first lens group having a positive refractive power and a second lens group having a negative refractive power sequentially from an object to be photographed. The first lens group comprises an aperture, a front group including at least two lens components having a positive refractive power, and a lens component which has a negative refractive power and an object-side lens surface of which has a concave surface directed toward an object side, and a rear group located nearer to an image than the aperture and including at least one lens component having a positive refractive power. The front group is located nearer to the object than the aperture and has a positive refractive power as a whole. The second lens group comprises at least one lens component having a positive refractive power and at least two lens components having a negative refractive power. A relative distance between the first and second lens groups is changed to perform zooming.

Abstract: An optical multiplex communication system in which n kinds of digital signals whose logical levels do not simultaneously become true, such as, pulse motor controlling pulses, are multiplexed through a single optical fiber line. The transmitting end generates n kinds of carrier clock signals of different frequencies by clock generating means, produces the respective logical products of the carrier clock signals and the digital signals and then produces a logical sum of the logical product outputs by logical circuits and converts the logical sum output to a light signal by a light transmitter, thereby delivering the light signal onto the single optical fiber line.

Abstract: Controlled variable table data, which consist of pulse number data corresponding to the maximum controlled variable of a fluid valve and divided into N divisions in each of which given pulse number data are set, are stored in a memory so that the sum of the given pulse number data in the N divisions may be equal to the number of pulses for giving a given controlled variable to the fluid valve. On the other hand, period table data, which consist of pulse interval data divided into divisions corresponding in number to the divisions of the controlled variable table data for determining a given control pattern, are stored in another memory.

Abstract: An external system for preparing information tables is connected by a connector to a digital valve control system which controls a digital valve by driving a pulse motor according to the information tables. The digital valve control system stores in the memory a first information table for determining the control amount for the digital valve and a second information table for determining the interval between the generation of motor driving pulses. The first information table for determining the control amount is fixedly stored in the memory and the second information table for determining the type of control pattern is stored in the memory which is capable of writing and reading the information which can be freely prepared, corrected and modified by the external system. The second information table is prepared by the keyboard of the external system, transferred to the digital valve control system and written in the memory.

Abstract: A poppet valve in which a poppet is slidable in a valve body and opens or closes a main valve path for pressurized fluid at one end. The pressurized fluid is conveyed to a back pressure chamber at the rear of the poppet either through a reduced flow path or through a valve arrangement between the surfaces of the poppet and a poppet spool slidable within the poppet. Either a control rod or the poppet spool moving relative to the poppet opens a flow path at the side of the back pressure chamber and the flow continues through a hollow in the spool or the control rod to an oil chamber away from the back pressure chamber where it is released to a tank.

Abstract: A zoom lens comprises, in the order from the object side, a first diverging group of lenses and a second convergent group of lenses. The first and second groups of lenses are movable along the optical axis to effect zooming. The first group comprises, in the order from the object side, a negative meniscus lens having its convex surface faced to the object side, a negative lens and a positive lens having its surface of larger curvature faced to the object side. The second group of lenses comprises, in the order from the object side, a positive lens, a positive lens formed by a single lens or a combination of cemented positive and negative lenses and functioning as an achromatic lens, a negative lens having its surface of larger curvature faced to the image side and a positive lens. The zoom lens satisfies certain conditions.

Abstract: A fast telephoto lens has a longer focal length of 300 to 400 mm, and an F-number of about 2.0 to 2.8, which does not utilize a floating mechanism, has a small deviation in aberration when the lens is focused on an object, and has a simple construction for shifting only one lens group. The fast telephoto lens is of internal focusing type and comprises positive, negative and positive lens groups from the object side, and only the negative (second) lens group is shifted to obtain an in-focus state.

Abstract: The driving speed of a hydraulic actuator is feedback controlled by adjusting an amount of fluid by a digital valve having a valve which is opened and closed by a pulse motor. For speed control, the deviation between a set speed of the actuator which is set by a speed setting device and a detection speed of the actuator which is detected by a speed sensor is obtained. A pulse signal of a frequency proportional to the magnitude of the deviation is generated. When the deviation is positive, the pulse motor is driven using the pulse signal as a CW command pulse. When the deviation is negative, the pulse motor is driven using the pulse signal as a CCW command pulse. The rotational amount of the pulse motor is the integral of the pulse frequency which is proportional to the deviation.

Abstract: A differential pressure regulator is arranged in series on the inflow side of a variable throttle for adjustment of a flow rate. An inlet pressure of the variable throttle is led into a primary pilot chamber of the differential pressure regulator. A constant flow control valve is provided in an oil passage connecting an oil passage on the inflow side of the differential pressure regulator with a secondary pilot chamber in order to allow a fluid of a constant flow rate to flow. The inflow side of a sequence valve is connected to the side of the secondary pilot chamber of the differential pressure regulator. The outflow side of the sequence valve is connected to the outlet side of the variable throttle or a tank. The inlet passage of the variable throttle is led into the primary pilot chamber of the sequence valve. An outlet pressure of the variable throttle is led into the secondary pilot chamber of the sequence valve. Further a check valve or a throttle is connected in parallel to the sequence valve.

Abstract: An image output apparatus prints an image of an original document and compares the printed image with the original document. Information representative of the original document operates a printing unit for printing an image of the original on a sheet of paper supplied from a paper feeding device. An image sensor senses the image on the printed paper and provides information representative thereof. The information from the image sensor is compared with the information supplied from the original document.

Abstract: A digital valve control apparatus for regulating opening of a digital valve by a pulse motor, comprising means for setting desired position and displacement speed of the pulse motor and means for selecting the set position and the set speed in response to instruction signals. While pulses having period corresponding to the set speed are produced by a frequency divider, the present position of the pulse motor is compared with the set position by a comparator. The pulses are fed to a counter which counts up or down to supply the output for driving the pulse motor until the comparator produces the coincident output.

Abstract: An image-forming apparatus equipped with an optical means, an electrostatic image-forming means and a control means. The optical means projects a scanned light beam to be controlled according to an image to be formed. The image-forming means receives the scanned light beam projected from the optical means and forms an image corresponding to the scanned light beam. The control means controls the optical means and the image-forming means.

Abstract: An image-forming apparatus equipped with an optical means, an electrostatic image-forming means and a control means. The optical means projects a scanned light beam to be controlled according to an image to be formed. The image-forming means receives the scanned light beam projected from the optical means and forms an image corresponding to the scanned light beam. The control means controls the optical means and the image-forming means.

Abstract: A light deflector comprising a rotating member provided with at least one light transmitting means having an input terminal and an output terminal. In this light deflector, with the rotation of the rotating member, a light beam put into the light transmitting means from the input terminal exits from the output terminal as a light beam to be rotatingly scanned about the rotating axis of the rotating member as a center.

Abstract: Displacement table data, which consist of pulse number data for N individual displacement divisions which altogether constitute a given rotational displacement of a pulse motor, are stored in a memory so that the sum of pulse numbers stored in the individual divisions may be equal to a given pulse number corresponding to the displacement of the pulse motor. Pulse period table data, which consist of pulse period data for determining the speed of the pulse motor for divisions corresponding in number to the number of divisions of the displacement table data, are stored in another memory. The pulse motor control is effected by causing generation of pulses corresponding in number to the pulse number data for the individual displacement divisions of the displacement table and having pulse periods for the individual divisions of pulse period table, and by executing the generation of pulses for the successive divisions.

Abstract: An electrostatic recording apparatus for recording, developing and fixing an image on a sheet of recording paper includes an electrostatic recording head and a roller for forming an electrostatic image on the sheet of recording paper while the latter travels between the electrostatic recording head and the roller. The electrostatic recording head and the roller are relatively movable toward each other for pressing the sheet of recording paper against the electrostatic recording head during a period of time in which the sheet of recording paper travels between the electrostatic recording head and the roller to allow the electrostatic recording head to form the electrostatic image on the sheet of recording paper. The electrostatic recording head and the roller are relatively displaceable away from each other during a period of time other than the above period of time.