Abstract: An apparatus and method for controlling recording and reproduction in a video cassette tape recorder are disclosed apparatus is capable of, in a recording mode, separating specific data for speed-varied reproduction from compressed digital video signals, recording them on designated tracks, recording position information of the designated tracks on a control track by an index head or recording position information of recording position-synchronized blocks at the starting portions of the designated tracks recorded with the specific data, and in a speed-varied reproduction mode, controlling a capstan servo speed so as to maintain the travel of a magnetic tape at a normal speed and periodically or non-periodically accelerate or decelerate it where specific data for varied-speed have been recorded periodically or non-periodically on predetermined portions of tracks, thereby making heads travel repeatedly at the normal speed and the high speed and thereby detect continuously the specific tracks for varied-speed.

Abstract: Tracking control apparatus and method for a digital/analog recording/playback system which is capable of recording and playing back a digital video signal as well as an analog video signal compatible with an existing VHS system. A tracking signal is recorded by first and second heads for the recording and playback of an analog video signal, and a digital video signal is recorded by third and fourth heads for the recording and playback of the digital video signal. The recorded tracking signal is played back by the first and second heads and the recorded digital video signal is played back by the third and fourth heads. The digital video signal is recorded on a portion of a tape wound at an angle of 180.degree. with respect to a head drum and the tracking signal is recorded on upper and lower 5.degree. portions adjoining the 180.degree.-wound portion of the tape. Therefore, a loss of the digital video signal can be avoided. This has the effect of obtaining a high picture quality.

Abstract: A recording apparatus for a high definition video cassette recorder, comprises a tape discriminator for checking for the presence of a hole on a specified position of a tape to discriminate whether the tape is of the normal-VHS type or the super-VHS type, a clock signal generator for generating a clock signal of a desired period in response to an output signal from the tape discriminator, a frequency divider for frequency-dividing the clock signal from the clock signal generator by an integer N, a first switch for selecting either the clock signal from the clock signal generator or the frequency divided clock signal in response to the output signal from the tape discriminator, a video data separator for separating intra-frame data and inter-frame data from an input digital video signal in response to the clock signal selected by the first switch and outputting the separated intra-frame data, a second switch for selecting either the input digital video signal or the intra-frame data from the video data separat

Abstract: An apparatus for recording and reproducing digital/analog video signals including a single head drum attached with heads for processing analog video signals and heads for processing digital video signals, and switches performing switching operations on the basis of the kind of input video signals. The head drum is variable in speed, depending on the kind of input video signals. In accordance with the apparatus, both analog and digital signals can be recorded and reproduced by a single recording unit and a single reproducing unit both capable of varying in characteristic, based on a video signal received thereto. This provides a reduction in manufacture cost and a light, thin, simple and compact construction of the existing VCRs.

Abstract: A variable bulge device for displacing bulges of a rotation head drum, capable of adjusting a protruded amount of a bulge used, depending on a rotation speed of the rotating head drum and the kind of a tape used. The device includes an operating member partially protruded at one end thereof through a bulge hole formed at a lower drum of the rotation head drum, the operating member having a variable bulge provided by the protruded end, and a drive unit for driving the operating member and thereby adjusting the protruded amount and position of the variable bulge.

Abstract: Diamond cutting tools such as a diamond core drill and a disk-shaped diamond saw which are used to grind and cut hard articles in order to bore or cut hard articles. The diamond cutting tools comprise a tool body and a diamond blade portion attached to an outer end of the tool body. The diamond blade portion has a plurality of outer cuts formed at an outer end thereof and a plurality of inner slots formed under and between the outer cuts and higher than the bottoms of outer cuts by a certain depth. The diamond cutting tools can carry out effectively boring or cutting work until the expensive diamond blade portion is completely worn away.

Abstract: An impedance roller for use in VCR which includes an inertia spring damper member defining a plurality of inertia masses and a plurality of elastic members connected to each other and disposed between a hub and a roller boss of the impedance roller for absorbing the vibration of the tape so as to reduce the longitudinal vibration component of the tape.

Abstract: A rotary head drum for a VCR using a fluid dynamic pressure bearing comprising a lower drum fixed to a base plate, a rotary shaft attached to the center of the lower drum, an upper drum fixed to a flange, a rotary head fixed to the upper drum to record and reproduce video signal in and from a magnetic tape, and a shaft housing including a guide groove, an air flowing groove having an air hole, a lubricant containing groove having a lubricant flowing hole, and a guide boss. The rotary shaft includes plurality lubricating grooves and a lubricant guide groove, so that the generation of the vibration and noise of conventional ball bearing when rotating the head drum, as a result it is possible to improve the Jitter and Wow-flutter of the video signal which effect upon the quality of the screen in recording or reproducing the video signal.

Abstract: A device for variably adjusting a moment of inertia of a drum of a videocassette recorder. The device comprises a plurality of inertial masses adapted to add a variable increment of a moment of inertia to a moment of inertia of the drum. In virtue of the possibility of varying the moment of inertria of the drum, it is possible to check the frame condition of the recorder, and thus, to obtain an optimum frame condition.