Abstract: A feedforward amplifier combines an input signal delayed by a delay circuit with an output signal by a combiner; down-converts the output of the combiner to a low frequency by a frequency converter; extracts a distortion component from the output of the frequency converter; measures the distortion component by a power detector; and controls a second vector regulator of a distortion canceling loop by a controller such that the distortion component measured becomes minimum.

Abstract: A feedforward amplifier combines an input signal combined by a first error rejection loop with an error component and a first pilot signal detected by a second error detection loop, thereby canceling out the error component and the first pilot signal residual in the input signal.

Abstract: Conventional distortion compensation circuits have addressed the problem that their distortion compensation amount is greatly reduced at levels other than the designed power level. The present invention provides a distortion compensation circuit that comprises: a vector adjuster; a linearizer; a linear signal extraction path for extracting part of an input signal from the input side of the vector adjuster; a nonlinear signal extraction path for extracting part of an output signal from the output side of the amplifier; a level detector for detecting a combined power level of the signals from the linear signal extraction path and the nonlinear signal extraction path; and a control circuit for adjusting a bias of the linearizer in accordance with the detected combined power level, electrically adjusting the linearizer so that the power detected by the level detector is minimized, and adjusting the vector adjuster so that the power detected by the level detector is minimized every time the linearizer is adjusted.

Abstract: A feedforward amplifier combines an input signal delayed by a delay circuit with an output signal by a combiner; down-converts the output of the combiner to a low frequency by a frequency converter; extracts a distortion component from the output of-the frequency converter; measures the distortion component by a power detector; and controls a second vector regulator of a distortion canceling loop by a controller such that the distortion component measured becomes minimum.

Abstract: A radio transmitter includes a gain compensation controller that derives the gain variation of the power amplifier from its bias voltage determined in response to its desired output power level, and that derives the control voltage of at least one of variable gain amplifiers from the gain variation. A variable gain amplifier gain controller applies the control voltage to the variable gain amplifier, thereby compensating for the gain variation of the power amplifier. The radio transmitter can solve a problem of a conventional radio transmitter in that it is unavoidable for the power amplifier to bring about the gain variation when its bias voltage is varied in response to the output power level.

Abstract: A feedforward amplifier which includes a distortion detector, a distortion eliminator, an error power extractor, a first level detector and a first controller. The error power extractor extracts output error power due to variations in the distortion eliminator by combining the output signal from the distortion eliminator with the signal from a first linear signal path in the distortion detector in opposite phases. The first level detector detects the output error power extracted by the error power extractor, and the first controller controls a first variable attenuator and a first phase shifter which are interposed in the distortion eliminator such that the output error power is maintained at zero.

Abstract: Articles having a diamond-like protective film formed thereon, each comprising a substrate of a material selected from the group consisting of alloys containing at least Co, Ni, or Fe, ceramics, and glass and which has only a slight affinity for a diamond-like thin film, an Mo film formed on the substrate, and a diamond-like thin film formed further thereon. Such articles are manufactured by a method which comprises holding a grid made of Mo close to the surface of the substrate, bombarding the grid and the substrate surface with a bombarding gas consisting of inert gas atoms of Ar or the like, thereby removing contaminants from the surface and depositing Mo atoms on the substrate surface to form an Mo film thereon, ionizing a low-molecular-weight hydrocarbon or a feed gas capable of producing a low-molecular-weight hydrocarbon upon decomposition or reaction, and then accelerating the resulting ions and depositing the same on the Mo film to form a diamond-like film thereon.

Abstract: A protectively coated article comprises a substrate of a material selected from the group consisting of alloys containing at least Co, Ni, or Fe, ceramics, and glass and which has only a slight affinity for a diamond-like thin film, an intermediate carbon layer formed on the substrate, the intermediate layer having a hardness Hv in the range from 1000 to 5000 kg/mm2, or harder than the substrate but less hard than a diamond-like thin film to be formed thereon, and a diamond-like thin film formed further thereon. The interposition of the intermediate layer permits the diamond-like thin film to be bound securely to a substrate surface which has a slight affinity for the film.

Abstract: A magnetic recording medium possessing excellent electromagnetic characteristics, corrosion resistance, durability, abrasion resistance and lubricity, has an undercoat layer, a ferromagnetic metal layer, a protective layer and a lubricating layer formed in this order on a non-magnetic substrate, or has an undercoat layer, a ferromagnetic metal layer, an intercepting layer, a protective layer and a lubricating layer formed in this order on a non-magnetic substrate, wherein the protective layer is a plasma-polymerized hydrogen-containing carbon film having a refractive index of 1.90 or more and a contact angle of less than 80 degrees, the film thickness of the protective layer or the total film thickness of the protective layer and the intercepting layer is 30 to 150 .ANG., the undercoat layer, as well as the intercepting layer, is a film formed of silicon oxide represented by SiOx (x=1.8-1.

Abstract: The present invention improves the adhesive property by pretreating under uniform conditions the substrate surface of metal, ceramics or glass etc. with a poor adhesive property, by accelerating ions under an electric field to the substrate in advance of a diamond-like film forming process. In light of the fact that a diamond-like film forming process by ionized deposition uses thermal electron ionization means and an electric potential is applied to a grid to accelerate ionized hydrocarbon ions, the present invention could attain the aimed purpose by ionizing and then accelerating a bombardment gas such as argon as a pretreatment process in the same apparatus.

Abstract: A wear-resistant protective film for thermal printing heads comprising Si, O, and N as principal constituent elements, contains additionally at least one alkaline earth metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Ra. Preferably, the film has a composition SiM.sub.x O.sub.y N.sub.z in which M stands for an alkaline earth metal, x is 0.01-0.5, y is 0.1-2.0, and z is 0.2-1.8.

Abstract: A method of producing a wear-resistant protective film for a thermal head comprises depositing a wear-resistant protective film by sputtering on a thermal head which includes a substrate, and a heat-developing layer and a pair of electrodes formed on either the substrate or a heat-regenerative layer formed thereon. A layer of the wear resistant protective film is formed under a RF larger bias and another layer without a bias or with a smaller bias. Good step coverage is obtained by the RF sputter layer of the wear-resistant and the protective film prevents the intrusion of water that can cause cracking, and the layer formed under no or smaller bias reduces internal stresses and inhibits the development of cracks due to internal stresses as well as the cracking by RF sputtering.

Abstract: Articles protectively coated with a diamond-like thin film firmly bonded to the substrates are obtained by forming an intermediate layer composed of an amorphous mixture of silicon and carbon on a substrate of a material which has only a slight affinity for such a diamond-like thin film, and forming a diamond-like thin film further thereon.

Abstract: A diamond-like thin film formed on a substrate, with the peripheral region tapered toward the edge, satisfying the dimensional relation100<b/a<10,000where a is the thickness of the film portion where the slope starts and b is the length of the slope. An apparatus for producing the film comprises a source for feeding a low-molecular-weight hydrocarbon or a feed gas capable of affording a low-molecular-weight hydrocarbon upon decompositon or reaction, means for ionizing the gas, a substrate held opposite to the ionizing means, and a mask member located between the ionizing means and the substrate. The apparatus and process using the apparatus are characterized in that the distance between the mask member and the substrate is fixed so as to obtain a diamond-like thin film satisfying the above-mentioned dimensional relation.

Abstract: Diamond-like thin films having high uniformity and high crystallinity are produced by introducing a hydrocarbon material gas into a chamber, ionizing the gas, and depositing the ionized gas on a substrate. The gas is ionized by thermionic emission from two or more files of hot cathodes, each file having a plurality of filaments arranged at substantially uniform intervals in a linear or zigzag line configuration. Each file of hot cathodes is surrounded separately by an anode at a substantially uniform distance from a respective file of the filaments.

Abstract: A highly corrosion-resistant rare-earth-iron magnet has a paraxylylene polymer film or a chloropara-xylylene polymer film formed thereon. The substrate magnet surface has a roughness Ra of no more than one micron. The magnet has a plasma polymer film formed beforehand or afterwards. The plasma polymer film has a protective film consists of only carbon and hydrogen, with a refractive index decreasing from the boundary surface between the film and the magnet toward the exposed surface. The protective coating has a thickness about three times the surface roughness of the substrate magnet.

Abstract: In a process for producing a diamond-like film which comprises introducing a hydrocarbon feed gas or a feed gas capable of producing a hydrocarbon on decomposition or reaction into a vacuum, ionizing the gas, and depositing the same on a substrate to form a diamond-like film thereon, the hydrocarbon gas is passed through a plasma exciter prior to the introduction into the vacuum. An apparatus for practicing the process comprises a plasma exciter means located on a passage through which the hydrocarbon gas is introduced into the vacuum.

Abstract: A mold including a cavity the inner surface of which is at least partly coated with a layer selected from a diamond-like film and layers of fluorine and fluorine compounds. The mold is manufactured by a method which comprises placing at least a part of the mold which constitutes the surface portion of the mold cavity in a vacuum film-forming chamber, introducing a hydrocarbon gas into the chamber, ionizing the gas, and then evaporating it onto a desired surface portion of the mold, thus forming a diamond-like film over the mold portion. The mold portion is surface-treated by ionizing a low-molecular-weight fluorine compound into a plasma, forming a fluorine polymer film from the plasma on at least a part of the cavity surface, while applying a bias voltage to the plasma.

Abstract: In a magnetic recording medium wherein a metal thin film magnetic layer and an overcoat are formed on a nonmagnetic substrate, durability is improved when the overcoat comprises a plasma-polymerized film and a topcoat of an organic fluorine compound; a plasma-polymerized film, a protective carbon film, and a topcoat of an organic fluorine compound; a plasma-polymerized film containing C, F and H; or a plasma-polymerized organometallic film and a fluorine or silicon-containing topcoat. Oxidation of the upper surface of the magnetic layer with a plasma is also effective.

Abstract: In a magnetic recording medium wherein a metal thin film magnetic layer and an overcoat are formed on a nonmagnetic substrate, durability is improved when the overcoat comprises a plasma-polymerized film and a topcoat of an organic fluorine compound; a plasma-polymerized film, a protective carbon film, and a topcoat of an organic fluorine compound; a plasma-polymerized film containing C, F and H; or a plasma-polymerized organometallic film and a fluorine or silicon-containing topcoat. Oxidation of the upper surface of the magnetic layer with a plasma is also effective.