Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Reexamination Certificate
1999-03-17
2001-01-30
Kim, W. Chris (Department: 2753)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
C360S051000, C360S068000
Reexamination Certificate
active
06181495
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a data recording apparatus, and more particularly, is suitably applicable to a data recorder for recording digital record data on a magnetic tape with a helical scanning system using a rotational drum.
2. Description of the Related Art
As a data recorder, there is that which the ID-1 format, which has been standardized by America National Standards Institute (ANSI), is applied to.
In this ID-1 format, only recording format for record data and footprint, such as track length, track width and track angle of a magnetic tape and recording wavelength, has been prescribed, but rotational rate of a rotational drum (speed of a recording head), running speed of a magnetic tape, the number of recording heads, and others are not especially prescribed.
Therefore, in this kind of data recorder, it is able to perform variable-speed controlling of multiplying relative speed of the recording head relative to the recording track direction of the magnetic tape by 1/1, 1/2, 1/4, 1/8, 1/16, 1/24, etc., so that it is able to record/reproduce the record data with a desired transfer rate between about 100 Mbps/channel to about 4.2 Mbps/channel, for instance.
Therefore, this kind of data recorder is broadly utilized for such uses that observation data is recorded and reproduced, keeping the pace with the transfer rate of analyzing apparatuses; as an example, observation data that is obtained from an artificial satellite and that is having relatively fast transfer rate is recorded in real time and, on the other hand, the recorded observation data is reproduced at a slower transfer rate than that of recording, and, as an another example, observation data that is obtained from astronomic observation, monitoring of road status (occurrence of a traffic accident, a traffic backup and others), etc., and that is having relatively slow transfer rate is recorded at the original transfer rate and, on the other hand, the recorded observation data is reproduced at a faster transfer rate than that of recording.
By the way, in this kind of data recorder, it is able to cause the rotational head to rotate at a relatively high speed and to secure a relative velocity between the recording head and the magnetic tape, so as to utilize the recording capability of short wavelength of the magnetic tape to its maximum, so that high density recording and high transfer rate can be realized, and, in this way, it is able to enhance the recording rate for 1 channel to about 100 Mbps as stated above.
However, in the case where the record data has been recorded at about 100 Mbps in this manner, the permeability of the recording head (if the frequency becomes high because of high transfer rate, the permeability lowers) and the frequency characteristics of the recording amplifier and others equipped within the data recorder would reach to their limits.
In this kind of data recorder, it is able to lower the recording rate to, for instance, 4.2 Mbps or so by rotating the rotational head at a relatively low speed, and the permeability of the recording head and the frequency characteristics of the recording amplifier and others of this case become ideal status, within the region having sufficient margin.
In this kind of data recorder, there was such a problem that if the transfer rate is relatively high, under the influences of the permeability of the recording head and the frequency characteristics of the recording amplifier and others, the edge portion of the waveform pattern of the recording current corresponding to the record data dulls, that is, a lowering phenomenon of the high-frequency component occurs, and rising of the amplitude occurs in the vicinity of the maximum frequency of the recording current due to the resonance in the circuit of the output side of recording amplifier including the recording head, so that the frequency characteristic of this recording current changes. As a result of this, if the transfer rate differs, then the quantities of delaying of the phase of short wavelength relative to the phase of long wavelength in the magnetization pattern that has been recorded on the magnetic tape on the basis of the recording current. That is, if the quantity of so-called peak shift differ and the transfer rate differs, the magnetization patterns do not coincide.
By the way, as a data recorder that solves such a problem, heretofore, there is that which is constituted using a linear first recording amplifier (which has been disclosed by this applicant in Japanese Patent Laid Open No.07800/92) for equalizing high-frequency-component highlighting operations that is comprised of plural filters to which frequency characteristics have been set, according to transfer rate, and a linear second recording amplifier (which has been disclosed by this applicant in Japanese Patent Laid Open No.067359/92) for equalizing band limitations that is comprised of plural filters to which frequency characteristics have been set, according to transfer rate.
In this case, this data recorder passes a record signal through a filter of the first recording amplifier corresponding to its transfer rate and hereby previously highlight the high-frequency component of the edge portion so as to equalize the high-frequency-component highlighting operation in the case where the transfer rate differs, and also passes the record signal through a filter of the second recording amplifier corresponding to its transfer rate and hereby restrain the amplitude of the high-frequency component from rising in the band of the vicinity of the maximum frequency so as to limit it and equalize limitation of the band in the case where the transfer rate differs.
However, since such a data recorder employs class A amplifiers whose efficiencies are about 50% as the first and the second recording amplifiers, the consumed power becomes relatively large, and radiation plates for radiating heat generated in the class A amplifiers are needed, and so the configuration of the whole data recorder is complicated and enlarged—that has been the problem.
So, as a data recorder for solving the problem that arises from employing such linear first and second recording amplifiers and for varying frequency characteristics of the recording current in accordance with the transfer rate, there is that which is constituted as shown in
FIG. 1
(which has been disclosed by this applicant in Japanese Patent Laid open No.287804/95).
That is, in this data recorder
1
shown in
FIG. 1
, digital data D
1
that is supplied from the exterior at the stated transfer rate and input clock signal CK
1
corresponding to the digital data D
1
are inputted to a signal processing circuit
2
.
This signal processing circuit
2
exposes the record data D
1
to the stated recording signal processing to produce record data D
2
shown in FIG.
2
A and then sends this data to an edge extracting circuit
4
of a recording amplifier
3
that is comprised of a switching amplifier, and besides converts the input clock signal CK
1
into the first clock signal CK
2
having the stated period T shown in FIG.
2
B and then sends this to the edge extracting circuit
4
.
The edge extracting circuit
4
, which operates on the basis of this first clock signal CK
2
, detects the time at which the record data D
2
rises to the logical level [1] and also the time at which it falls to the logical level [0], and then, on the basis of this detection result, generates a timing signal ES that is showing the position to highlight its high-frequency component previously, in expectation of lowering of the high-frequency component of the edge portion. Then, the edge extracting circuit
4
sends the record data D
2
to the first switching unit
5
, and sends the timing signal ES to the second switching unit
6
.
In this connection, the timing signal ES is synchronized with the first clock signal CK
2
, and raises to the logical level [1] during only the period T of the first clock signal CK
2
from the time at which the record data D
2
r
Makise Tetsuro
Yoshida Teruyuki
Frommer William S.
Frommer Lawrence & Haug LLP.
Kim W. Chris
Sony Corporation
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