Abstract: The present invention relates to a process for preparing a polyethylene naphthalate possessed with high viscosity, characterized by sloving of various problems of the prior art by controlling the rate of the polycondensation reaction.Particularly, the present invention provides a process for preparing polyethylene naphthalate from an esterification reaction product of naphtalene dicarboxylic acid or an alkyl ester thereof and a diol, which comprises polycondensing the esterification reaction product in the presence of a polycondensation catalyst in two steps wherein the first step is carried out at a pressure ranging from 500 to 30 torr and the second step is carried out at a pressure ranging from 10 to 0.1 torr with controlling the reaction rate such that the differential increase of the intrinsic viscosity of the resultant polymer can satisfy the following equations:IV(t.sub.1)-IV(t.sub.0)<0.4 dl/g (1)IV(t.sub.2)-IV(t.sub.0)>0.3 dl/g (2)wherein: IV(t.sub.

Abstract: The present invention relates to a biaxially oriented polyester film comprising a metallic alkylbenzene sulfonate derivative of formula(I), polyethylene glycol and, optionally, bis(4-.beta.-hydroxyalkoxyphenyl) sulfones of formula(II), which has improved antistatic property, clarity, mechanical properties and heat resistance: ##STR1## wherein: R represents an optionally substituted C.sub.8-25 alkyl group;M represents an alkali or alkali earth metal;m is an integer of 100 or fewer; andn is an integer from 1 to 10.

Abstract: Disclosed herein is a method of producing a magnetooptical disk by way of depositing a recording layer, a protective layer, and a reflection layer on a transparent substrate. The inventive method features that the refractive index of the protective layer is subjected to a precise control by way of changing the flow rate of argon gas within the range of no greater than 100 SCCM while maintaining the flow rate of nitrogen gas substantially constant at a value within the range of 3 to 10 SCCM.

Abstract: An improved apparatus for automatically measuring the viscosity of a sample liquid is disclosed. The apparatus comprises a plurality of viscosimeter tubes mounted in a constant temperature bath, a plurality of vessels adapted for containing the sample liquid, a valve system for controlling the injection and the removal of the sample liquid into and from the viscosimeter tubes and the ascent and descent of the sample liquid in the viscosimeter tubes, a driving circuitry for the valve system, a photosensing device for sensing the meniscus of the liquid at predetermined indication marks of the viscosimeter tubes and a system of measuring the flow time of the sample liquid between two predetermined marks and computing the viscosity of the liquid based on the measured flow time.

Abstract: The present invention relates to improving a reel locking device which locks or releases a supply reel 2 and a take-up reel 2' while entering and leaving the teeth 4,4' formed in the circumference of the reel downs 3,3' of said supply and take-up reels installed in the inside of video tape cassette 1. In such a reel locking device, wings 12, 12' with locking jaws 13, 13' formed at the front ends are extended on both sides of the upper end of plate-shaped body 11 and a hinge axis 14 is formed at the lower end thereof and, in the lower part of said hinge axis 14, a elastic piece 15 whose lower end bends upward is formed and both ends of said axis 14 are united with hinge grooves 7, 7' formed in the lower side of the lock guide 6 of half down 5 so as to correspond to the curved elastic piece 15.

Abstract: An antistatic roll is provided for use in transferring and/or winding a continuous sheet of polymeric film. The roll comprises a cylindrical core made of an electrically conductive material which is provided with a pair of rotational shafts, each extending away from the opposite ends of the roll in an axial direction. A layer of dielectric material surrounds the core, which has a spiral groove formed on the outer circumference thereof at a substantially equal pitch. An elongate conductor is held within and extends along the spiral groove to gather static electricity from the roll and/or the polymeric film. Associated with the elongate conductor is a grounding arrangement to drain off the static electricity gathered therein.

Abstract: An optical recording medium is disclosed herein which comprises an antistatic and scratch-resistant metal oxide layer on the light incident side of a transparent substrate. The metal oxide layer has a light transmittance high enough to transmit at least a portion of the light beam therethrough and a sheet resistivity low enough to suppress the substrate from getting electrostatic. Such a metal oxide layer can be deposited either directly, or through an interfence layer, on the substrate with a thickness of 100 to 1,000 Angstrom.

Abstract: A process for preparing a magneto-optical recording medium is disclosed in which a recording layer is formed from a vertical magnetizing film made of amorphous metal having a magnetization facilitating axis in a vertical direction on a substrate material. A protective film layer of a metal or semi-metal oxide, nitride or sulphide as a main ingredient is formed on the recording layer in a vacuum chamber, and the surface energy of the protective film is raised by etching it with plasma. The close adhesion of a next applied photosetting resin layer is thereby improved.

Abstract: An improved digital audio tape cartridge has a pivotal lid with sidewalls formed to provide grooves which positively engage the jaws of wings of a tape reel hub locker so that the locked tape reel can be reliably released when the lid of the digital audio tape cartridge opens.

Abstract: In a video tape reel support spring, the present invention is an improvement on the support spring and is designed for both cost reduction and functional improvement. Its main feature is that a spring of equal width is provided, but a reinforcing means which can prevent its elasticity from weakening is provided and it is altered so as to enable its end to apply just the right pressure to the center boss.

Abstract: A novel automated filter cleaning system capable of removing contaminants clogging the filter disk without having to resort to the operator's manual operation is disclosed. The system comprises a turntable or filter magazine for holding the filter disks in a stacked condition, a first ultrasonic cleaner for applying an ultrasonic field to one side of the filter disk, a second ultrasonic cleaner for applying an ultrasonic field to the other side of the filter disk, a water injection cleaner for removing residual contaminants from the ultrasonically cleansed filter disk, a robotic carrier for transporting the filter disk from a particular station to another, and a controller for controlling the overall operation of the filter cleaning system. A method is also provided for cleaning the filter disk by a combined action of ultrasonic treatment and water injection.

Abstract: An automatic viscosity measuring device which measures sample levels, automatically fills a sample to a marked line by vacuum pressure, automatically counts the time for the sample to fall by a sensor in the upper and lower marked lines, finds intrinsic viscosity by concentration and then measures the degree of error from relative viscosity in the case of the Ostwald's viscosimeter, which automatically measures the viscosity of a high molecular material.

Abstract: The present invention relates to a flap which applies elastic pressure to the tape which runs in a Video Tape Cassette and its installing structure.The flap is formed by coating its both sides which use a PET(Polyethylene Terephthalate) film as the base with a composite containing a carbon black lubricant and a fitting method is adopted to install the flap.

Abstract: A lower reel plate structure for a video tape cassette which is characterized in that the lower reel plate is formed such that an extended portion is provided on the tops of a hub wall and a boss, a space formed between the hub wall and the boss is provided with a downward opening, and a step is provided along the whole peripheral edge where the hub wall and the extended portion join together.

Abstract: The present invention provides a support spring which may be used in connection with cassettes, and particularly video cassettes. The support spring has a central portion which is adapted to be fixed to an inside surface of the upper portion of a cassette. The spring also includes a supplementary piece joining the central portion with a pressing part and a bending part which also joins the central part with the pressing part, the bending part being shorter than the supplementary piece.

Abstract: Tape cartridge having a T-shaped brake lever or separable brake levers from the slider and forms needle-shaped ends at the ends of a T-shaped brake lever or separable brake levers and prevents the tape from being unwound by enabling the sawteeth parts to catch them but makes the positions of needle-shaped ends facing toward the sawteeth parts take their eccentric positions backward and inward contrary to the point where the former projections are located.

Abstract: The present invention relates to a lid locking device for a video cassette having upper and lower cases and a lid mounted on the cases for movement between an open position and a closed position. The lid locking device comprises a lid lock having a pivot for mounting the lid lock within the upper and lower cases for pivotal movement between a lid locking position and a lid releasing position. The device further comprises a rounded groove in the upper side of a spring support member of the lid lock, a square projection on the lid lock comprising a convex portion, and a convex portion of the cassette at a point corresponding to the square projection.

Abstract: In digital audio tape cartridge, the tape cartridge has an improved a slider locking device. The slider in which opening position locking holes and closing position locking holes are bored for the selective locking of locking projections, is engaged with the lower shell and the elastic piece of elastic locker makes in to "a both ends-fixed beam" with its both ends integrated with the lower shell and forms the locking projections in the middle part of elastic piece.The elasticity of the elastic piece of elastic locker which forms the slider locking device is maintained so properly that the slider locking action of elastic locker is achieved correctly and the cartridge enjoys a long life even when it is used for a long time.

Abstract: A flangeless-type reel holder for a device manufacturing reels of video film including a ring-type leaf spring fitted around the reel holder. The reel holder is fitted around a sleeve mounted on a drive shaft of the device, by means of a bearing interposed therebetween. The reel holder is directly coupled to the outer rim of the bearing. The outer diameter of the leaf spring fitted around the reel holder is larger than that of an annular rim of the reel holder so that the inner peripheral surface of a reel hub to be fitted around the reel holder can closely contact with the outer surface of the leaf spring.