Abstract: An alumina sintered body containing, as impurities, sodium oxide, potassium oxide, silicon oxide, calcium oxide, ferric oxide and titanium oxide in a total amount in the range from 100 to 10000 ppm, in which a total amount of the sodium oxide and potassium oxide based on the total amount of the impurities is not more than 4 wt. %. In the manufacture of the sintered body, its starting powder is admixed with at least an acid compound to produce metal salts by a reaction of the acid compound with metals contained in the starting powder and the resulting metal salts are removed.

Abstract: A process for producing 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester having a high purity from 1,4-cyclohexanedione-2,5-di(carboxylic acid alkyl ester) at high yields for a short period of time; a process for producing quinacridone of which the byproduct content is small, from the above 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester; and a process for producing quinacridone of which the particle diameter is adjusted as desired, from the above 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester without adding a step of forming a pigment.

Abstract: An apparatus for measuring displacement information of a target object includes an illumination system, a photodetector, and an adjusting member. The illumination system causes a beam from a light source to be incident on the target object. The photodetector receives and detects light from the target object upon incidence of the beam from the illumination system on the target object. The displacement information of the target object is measured upon detection of the light by the photodetector. The adjusting member changes a light-receiving state of the light on the photodetector.

Abstract: A Doppler velocimeter determines a state of noise generation in a detection signal including a Doppler signal component based on comparison by a preceding/succeeding-signal comparator for comparing the detection signals before and after passing through a band-pass filter for cutting noise adjusted to the frequency of the detection signal, and/or includes a filter circuit for determining passage/interruption of the detection signal after passing through the band-pass filter from a relationship between the count value of a first counter, in which the output of a first frequency multiplier for multiplying the frequency of the detection signal by N is made to be a clock signal and a leading edge in the detection signal is made to be a reset trigger, and a leading edge in the detection signal, and/or includes an error signal generator for generating an error detection signal by detecting a periodic error in the detection signal after passing through the band-pass filter from a relationship between the count value

Abstract: Disclosed is a frequency shifter for shifting a frequency of incident light beams. The frequency shifter has an electro-optic element for making incident the light beam whose frequency is to be shifted, an electrode unit disposed on the electro-optic element, an electric charge imparting circuit for imparting an electric charge to the electrode unit and a discharging circuit for discharging the electric charges accumulated in the electrode unit. Disclosed also is an apparatus, having the frequency shifter, for optically measuring relative displacement data to a measured object.

Abstract: Dielectric circuit components such as a dielectric strip, dielectric blocks and dielectric ring inserted between conductive plates are molded from a thermoplastic material. As the thermoplastic material, thermoplastic resin is used which has a dielectric constant not greater than 2.4. The dielectric circuit components may be injection-molded from an injection-moldable high polymer material which contains fluorine and has a melting point not greater than 300.degree. C.

Abstract: An optical device, and an apparatus for detecting displacement information of an object using the optical device, include an electrooptical device for shifting a frequency of an incident beam by applying a voltage thereto and an optical system for converging the beam at least in a plane including an application direction of the voltage and traveling direction of the beam, and for decreasing a degree of change of the diameter of the converged beam at least in the plane so as to reduce the diameter of the beam incident on the electrooptical device at least in the application direction.

Abstract: An apparatus for measuring information about displacement of an object includes a light source having the wavelength of its emitted light beam varied by a temperature change, a diffraction grating for diffracting the light beam from the light source, an optical system having first and second lens systems for deflecting the diffracted light beam from the diffraction grating and applying it to the object, a photodetector for detecting scattered light subjected to a Doppler shift from the object to which the diffracted light beam is applied, the information about the displacement of the object being measured based on a Doppler signal obtained by detection of the scattered light by the photodetector, and a mounting mechanism for restricting the positional relation between the first and second lens systems, the mounting mechanism varying the spacing between the first and second lens systems by a temperature change.

Abstract: A frequency shifter is capable of controlling the adverse influences of electric noise caused by the voltage applied to electrooptical elements of a frequency shifter. The frequency shifter modulates the phase of the luminous flux entering the electrooptical elements by applying a voltage to the electrooptical elements; the shifter is provided with a shield for electrically shielding the circuit for generating the voltage to be applied to the electrooptical elements and the electrooptical elements from an external circuit.

Abstract: A radar module includes a high-frequency signal generator comprising upper and lower parallel conductive plates, at least one dielectric rod held between the parallel conductive plates, a metal diode mount held between the parallel conductive plates, a gunn diode member mounted on a side of the diode mount, and a printed-circuit board mounted on the side of the diode mount in covering relationship to the gunn diode member and having a bias supply circuit on its surface for supplying a bias voltage to the gunn diode member. One terminal of the gunn diode member extends through a through hole defined in the printed-circuit board, is exposed in the vicinity of the surface of the diode mount, and is connected to the bias supply circuit.

Abstract: A ceramic material is a calcined article obtained by calcining a molded ceramic article and in which the pores of the calcined article are impregnated with a substance which can be removed at a temperature lower than a sintering temperature for the molded ceramic article. A method for manufacturing a ceramic product includes the steps of calcining a molded ceramic article, impregnating the open pores of the calcined ceramic article with a substance which can be removed at a temperature lower than a sintering temperature for the calcined ceramic article, mechanically machining the ceramic article to impart a desired shape thereto, removing the substance from the ceramic article, and then sintering the ceramic article. Large-sized ceramic products having a high strength and an excellent shape accuracy and having complex shapes can be manufactured at low costs.

Abstract: This invention has as its object to provide a frequency tracking method, a frequency control apparatus (tracking apparatus) using this method, and a Doppler velocity meter using the same, which easily and quickly allow the center frequency of a band pass filter to coincide with the frequency of an input signal even when an input signal suffers from a large level drift.

Abstract: A radar system allows switched use of an FM-CW radar mode and a phase difference radar mode, the FM-CW radar mode being designed for use in sensing a target at a medium and long distance away and the phase difference radar mode being designed for use in sensing a target at a short distance away, whereby a target at an extremely short to long distance away can be sensed with high accuracy.

Abstract: An NRD guide circuit is assembled by arranging, on a lower conductive plate, a positioning member of a material (e.g., foaming styrol resin, foaming urethane or the like) having a dielectric constant smaller than that of a dielectric strip, followed by placing such component parts of the NRD guide circuit as a dielectric strip at a position delimited by the positioning member, whereafter an upper conductive plate is secured thereto.

Abstract: A process for producing 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester having a high purity from 1,4-cyclohexanedione-2,5-di(carboxylic acid alkyl ester) at high yields for a short period of time; a process for producing quinacridone of which the byproduct content is small, from the above 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester; and a process for producing quinacridone of which the particle diameter is adjusted as desired, from the above 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester without adding a step of forming a pigment.

Abstract: An apparatus for detecting information relating to displacement of an object on which a grating scale is affixed. The apparatus includes a beam-emitting system for irradiating the grating scale with a beam. The apparatus also includes a light-detecting element having a light-receiving surface. A grating portion is integrally formed on at least a part of the light-receiving surface for detecting a beam from the grating scale which is irradiated by the beam from the beam-emitting system. Information relating to displacement of the object is detected on the basis of the detection by the grating portion of the light-detecting element.

Abstract: A plurality of radar devices are provided on and along the periphery of a vehicle for monitoring in different directions. While sequentially switching the radar device to be used for the monitoring operation in response to a transmission-enable signal, a processing device detects, for each direction, presence of and distance to an obstacle or object on the basis of a phase difference (time difference) between signals transmitted and received via the corresponding radar device. Thus, the processing device causes an image display device to show the detected conditions around the vehicle and also causes a sound synthesizer to output a sound message to call the vehicle operator's attention.

Abstract: A process for producing highly pure 6,13-dihydroquinacridone, which is a suitable intermediate for effectively producing a quinacridone pigment, for a short period of time at high yields, the process comprising providing a cylindrical reactor, providing an atmosphere free of oxygen in the cylindrical reactor, heating the cylindrical reactor so that the temperature of at least a surface of an inner wall of a cylinder of the cylindrical reactor is in the range of from 250.degree. to 400.degree. C.

Abstract: A Doppler velocimeter includes an illuminating system for projecting a light beam for measurement onto an object to be measured at a predetermined working distance, and a light-receiving system for receiving light from the object illuminated with the light beam by the illuminating system. Information relating to a speed of the object is detected by a Doppler shift of the light received by the light-receiving system. The Doppler velocimeter further includes a changing device for changing the working distance of the illuminating system.

Abstract: A power separating apparatus in an automobile comprises first detecting means for generating a first electric signal having a predetermined voltage level when an engine is actuated, second detecting means for generating a second electric signal having a predetermined voltage level when a rotated device is not actuated, determining means for generating a failure signal indicating a failure of the rotated device depending upon a condition of logical product of the first electric signal and the second electric signal when the rotated device should be actuated, and means for controlling an electromagnetic clutch to separate the rotated device from the driving belt on the basis of the failure signal.