The lubricity, durability and anti-corrosive properties of metal evaporated tape(HE tape) for digital VCR were investigated. To improve reliability of the ME tape, Diamond-Like Carbon (DLC) film and lubricant were applied as protective layers on a Co-O magnetic layer. The newly developed HE tape has superior durability for the consumer -use and has been accepted as the standard tape of the consumer-use digital VCR. We investigated on the effects of lubricants, carbon films and surface roughness on the ME tape.

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Obliquely deposited Co-O thin film with diamond-like-carbon(DLC) protective layer (digital ME tape) has newly developed. It has 5dB higher output and 4dB higher CNR than conventional Hi-8 ME tape at a recording density of 100kBPI. Other recording properties such as ATF over-write characteristics and impulse response were found suitable for high density digital recording. The durability in enviromental conditions was tested by Hi-8 VTR in still mode and running mode, and it was found enough for consumer use VTR. Its archivability was found superior to conventional Hi-8 MP tape.

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A new measurement of nonlinear magnetic transition shifts ε_1 and ε_2 employing dipulse response is proposed; In magnetic recording, ε_1 and ε_2 are caused by magnetic transition shifts with the shortest reversal interval T_<min> and 2T_<min> earlier respectively. Using this measurement, ε_1 and ε_2 versus amplitude, shortest reversal interval, and frequency response of the recording current are measured. As a result, ε_1 and ε_2 are increased by over the 50% of the optimum recording current and have a good correlation with reproduced voltage, and are also increased under the 0.5μm and 0.25μm of T_<min> respectively, and reach a minimum value at a certain level of suppression with respect to the recording current in low frequency regions. Recording and playback equalizations are studied using the 8-14 channel coded signal. It is found that recording equalization can be performed by shifting the reversal points of the recording signal so that nonlinear magnetic transition shifts equal zero, and also playback equalization can be performed approximately by emphasizing the amplitude and delaying the phase of the reproduced signal in middle and high frequency regions compared to low frequency regions.

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We studied a viterbi decoding for consumer-use digital VTR. We built the proto-type viterbi decoding circuit adapting to reproducing bit rate of 42Mbps, and evaluated the error characteristics using this circuit. As the result, we confirmed the byte error rate of viterbi decoding was reduced to 1/10 to 1/30 as compare with the bit by bit decoding.

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This paper describes a study of an automatic equalizer for reducing the errors of the detected data. The automatic equalizer controlls the equalizing characteristics to minimize equalized error which is gotton by M times accumulative addition of the difference between the expected signal level and the detected signal level at detecting points. This automatic equalizer can realize the precise control of the equalizing characteristics very quickly by studying the method of calculating the equalized error and the method of changing the tap coefficient.

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