Abstract: A power transmission shaft performs a fuse-like function when excessive torque is applied to a power input side. The power transmission shaft includes: a main shaft connected to a power device; flanges connected to the power device and provided at both sides of the main shaft; and a flexible coupling extending in the radial direction of the main shaft. The power transmission shaft includes a power shutoff unit which shuts off power by breaking the main shaft or the flanges when torque greater than a predetermined level is applied. When excessive torque is applied to the power input side, the power transmission shaft performs a fuse-like function with respect to the excessive torque, thereby enhancing safety, preventing sparks from occurring at the time of the breakage, facilitating the production thereof, and effectively preventing vibration while sufficiently supporting the speed or load in the event of a high rotation rate.

Abstract: A power transmission shaft which alleviates phenomenon in which stress is concentrated on a specific portion of a diaphragm to improve fatigue life span. The power transmission shaft connects a power apparatus and includes a flexible coupling, which is configured by a hub unit positioned inside in a radial direction. A rim unit is positioned outside in a radial direction of the hub unit. A flexible diaphragm unit is positioned between the hub unit and the rim unit. The thickness in the axial direction of the flexible diaphragm unit, from the hub unit toward the rim unit, becomes thinner then thicker to have a minimum thickness interval. The flexible diaphragm unit has a contoured first side on one side in the axial direction and a contoured second side on the other side. The first side has a first inflection point and the second side has a second inflection point.

Abstract: A clutch apparatus for an electric valve actuator, in which, where a manual handle is operated by an operator in a state that a power supply is stopped in a main motor, a coupling state between the manual handle and the main motor is released and the main motor is separately driven during a re-supply of the power, whereby preventing a safety accident of the operator of the manual handle.

Abstract: Disclosed is a clutch apparatus for an electric valve actuator, in which, where a manual handle is operated by an operator in a state that a power supply is stopped in a main motor, a coupling state between the manual handle and the main motor is released and the main motor is separately driven during a re-supply of the power, whereby preventing a safety accident of the operator of the manual handle.

Abstract: An aluminum head drum for use in a video cassette recorder is coated with a protective layer comprising diamond-like carbon. The protective layer of diamond-like carbon is obtained using a plasma-enhanced chemical vapor deposition method and has a thickness ranging from 0.3 .mu.m to 2.0 .mu.m. The protective layer has a varying mechanical hardness, wherein the mechanical hardness has a maximum value at a region of the protective layer coming in contact with the aluminum head drum, decreases smoothly and continuously and reaches an minimum value at a region of the protective layer coming in contact with atmosphere. Micro-Vicker's hardness of the region of the protective layers coming in contact with a video tape is 1.5-2.0 times that of the magnetic substance constituting the video tape.

Abstract: A pinch roller type tape drive assembly which is one of the elements composing a tape driving system of a VCR and ensures stable running of a tape. The pinch roller type tape drive assembly has a capstan for rotating at a constant velocity and a pinch roller which self-aligns, for pressing a tape against the capstan so as to drive the tape at the constant velocity together with the capstan. When the pinch roller is pressed against the capstan, an annular self-aligning member disposed between an inner sleeve and an outer sleeve is compressed in the direction of the contact point of the capstan and the pinch roller toward a pinch roller shaft, thereby holding the gap between the capstan and the pinch roller.

Abstract: A rotary of a head drum assembly for a VCT in which the structure thereof is simple, thereby facilitating the manufacture thereof, and which can prevent cross-talk of the video signals by forming magnetic conjunctions only between corresponding rotor and stator coils. The rotary transformer comprises a transformer stator having a stator body which is mounted on a lower drum of the head drum assembly and has at least two stator channels formed on a surface thereof, and stator coils respectively wound and attached in the stator channels, and a transformer rotor having rotor bodies which are mounted on an upper drum of the head drum assembly and have recesses formed on opposite surfaces thereof, and rotor coils respectively wound on the rotor bodies, the rotor bodies being substantially I-shaped and being disposed spaced apart from the stator channels by a distance, the rotor coils being electrically connected to magnetic heads respectively.

Abstract: Disclosed is a head drum assembly for a VCR having a simple structure and high reliability. Provided is a shaft including a vertical groove extending from an upper portion to a lower portion of the shaft, a slanted groove extending from a lower end portion of the vertical groove to a maximum height that the shaft reaches, and a thrust cap inserted onto an upper end portion of the shaft by pressure. A lower drum is inserted into a lower end portion of the shaft by pressure and has a stator transfromer installed at the inner upper portion of the lower drum. An upper drum has at least two video heads installed at an outer bottom portion of the upper drum, and has a rotor transformer corresponding to the stator transformer at an inner bottom portion of the upper drum. A motor for imparting a driving force to the upper drum and for rotating the upper drum is provided. Bearing supporting effect can be obtained by using oil having low viscosity.

Abstract: Disclosed is a lubricating apparatus which can compensate for the radial load and the thrust load of the shaft. The lubricating apparatus includes a housing formed at an inner portion thereof with a pair of lubricant containing grooves, a journal bearing inserted into the housing, and lubricating pads having a lubricant therein. The lubricating pads are inserted into the lubricant containing grooves. A head drum assembly for a video cassette recorder is also disclosed. The assembly has a lower drum, an upper drum, a motor for generating a driving force, a shaft for transferring the driving force of the motor to the upper drum, and a bearing rotatably supporting the shaft. By compensating the radial load and thrust load of the shaft, jittering and wow-fluttering can be prevented while recording a screen information on a magnetic tape or reproducing the screen information from the magnetic tape.

Abstract: A head drum assembly is provided with a flange fixed around a rotating shaft and including an upper abutment stopper for preventing an inner ring of an upper ball bearing from moving up with respect to the rotating shaft and a pre-loading sleeve having a sleeve portion fixed around the rotating shaft in a press-fit relationship therewith, the sleeve portion having a lower abutment stopper for pre preventing an inner ring of a lower ball bearing from moving down with respect to the rotating shaft.

Abstract: Disclosed is a head drum assembly of a video cassette recorder which can support the radial load and the thrust load of the shaft. The head drum assembly includes a lower drum, an upper drum, a motor for generating a rotational force, a shaft for transferring the rotational force of the motor to the upper drum, a housing formed at an inner portion thereof with lubricant containing grooves, lubricating pads for containing the lubricant and being inserted into the lubricant containing grooves, bearings inserted into the housing, and a shield plate disposed between the bearing and the upper drum, for preventing the evaporation of the lubricant of the bearing. The radial load and thrust load of the shaft are effectively supported, a long term lubrication can be achieved by the prevention of the evaporation of lubricant in the bearing, and jittering and wow-fluttering can be prevented while recording a video information onto a magnetic tape or reproducing the video information from the magnetic tape.

Abstract: A head drum assembly has an upper drum having at least two video heads at an outer bottom portion thereof, and a rotor transformer at an inner bottom portion of the upper drum. A lower drum is formed on a boss and has a cylindrical shape with the same diameter as that of the upper drum. The lower drum is positioned under the upper drum. The boss is formed by bending a deck upwardly. A lead line for leading a magnetic tape is formed on the outer periphery of the lower drum. A stator transformer corresponding to the rotor transformer is positioned on a main PCB. A shaft is integrally formed on a main chassis and is installed in the center portion of the upper drum. A motor for rotating the upper drum relative to the shaft is provided. The manufacturing and the structure of the head drum assembly is simple.

Abstract: A head drum assembly for use in a VCR includes a rotating shaft with a diamond-like carbon ("DLC") coating; a rotary drum fitted tightly around the rotating shaft; a stationary drum, fitting around the rotating shaft, and incorporating a set of DLC coated bearing surfaces; and an axial thrust bearing means. Such a head drum assembly allows smooth rotation by using herring-bone shaped grooves or protrusions in conjunction with DLC coatings in the appropriate bearing surfaces.

Abstract: A head drum assembly of a VCR is disclosed which can prevent Jitter and Wow-flutter of signals while recording and reproducing signals and can additionally supply a lubricant. A bearing housing in which lubricant containing groove is formed is integrally formed with a lower drum. Two journal bearings are mounted on the inner side of the bearing housing and support and lubricate a shaft which drives an upper drum. The lubricant in each of the lubricant containing grooves flows into a clearance between the outer surface of the shaft and the inner surface of each of journal bearings along a path formed by the lubricant containing groove, slits, and the lubricating groove, so that an oil film is formed between the shaft and the inner surface of each of the journal bearings. The lubricant can be additionally supplied through lubricant supplying holes.

Abstract: A head drum assembly for use in a VCR includes a rotary drum, a stationary drum, a motor assembly, and a plurality of piezoelectric bearings. The novel head drum assembly allows smooth rotation by using piezoelectric bearings in the appropriate bearing surfaces. In addition, the head assembly eliminates problems present in conventional head assemblies such as irregular rotation due to damaged ball bearings, lubricant contamination of the heads, and manufacturing difficulties due to the use of ball bearings and lubricant.

Abstract: Disclosed is a rotary head drum having a simplified structure, and a method for manufacturing thereof. An upper drum having at least two video heads formed at an outer bottom portion thereof is installed. A shaft is installed in the center portion of the upper drum. A deck portion on which said upper drum is installed, is vertically and upwardly bent by press working into cylinder shape having a shorter diameter than the upper drum. Then, a lower drum is formed on the outer portion of the deck by outsert molding under the upper drum at a predetermined distance apart from the upper drum. A number of complicated processes and assembling process for fixing the lower drum on the deck can be omitted. Thus, the obtained head drum has a simplified structure with less elements and has good quality.

Abstract: A head drum assembly for use in a video cassette recorder includes a rotating shaft, a rotary drum coupled with the rotating shaft, a stationary drum attached to the rotating shaft under the rotary drum, a rolling bearing disposed between the rotating shaft and the upper part of the stationary drum, and a sliding bearing disposed between the rotating shaft and the lower part of the stationary drum.

Abstract: An upper drum assembly for use in a video cassette recorder includes an upper drum having an inner part with a top surface and an outer side surface with one or more head windows, the inner part thereof being provided with recesses, one or more openings and one or more through holes, one or more heads, the head having a head chip joined to a head base, one or more first screws, one or more second screws and one or more nut caps, each of the nut caps having a fixed part provided with a first tapped hole corresponding to the through hole in the upper drum, a body part provided with a second tapped hole, and a stepped part. Each of the nut caps is fitted onto the upper drum in such a way that the body part therein is fitted into one of the openings, the fixed part therein is placed on the top surface of the inner part of the upper drum, and the stepped part is placed into the corresponding recess.

Abstract: An optical tape reading/recording apparatus comprises a transparent hollow drum and a pinch roller for guiding a running optical tape, the optical tape retained between the drum and the pinch roller and a scanning device for scanning the optical tape closely contacted on a spherical lateral surface of the hollow drum.