JP2902858B2 - Fade-out method in DCC system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plurality of tracks extending in the longitudinal direction of a signal recording tape, in which one auxiliary track records various sub-codes and a plurality of other audio tracks. The present invention relates to a DCC (digital compact cassette) system having a multi-channel head for recording audio signals.

[0002]

2. Description of the Related Art As described in, for example, "Nikkei Electronics", September 134, pp. 134-141, a DCC is used for a cassette tape having substantially the same shape as an analog compact cassette player. The audio signal is digitally recorded, and the digitized audio signal is data-compressed by a high-efficiency encoding called a PASC system, and is recorded on an 8-channel audio track of a magnetic tape. In the DCC, signals such as time information and music number information are recorded on an auxiliary track of one channel of the magnetic tape.

FIG. 2 shows a head assembly (27) mounted on the DCC. The recording thin film multi-head (6) and the recording thin film multi-head (9) each having nine channels correspond to one side of the width direction of the magnetic tape (22). A reproduction thin film multi-head (7) is arranged. The recording thin film multi-head (6) has an auxiliary head chip (23) at the top and eight audio head chips (24) at the bottom, and the reproducing thin film multi-head (7) has
The upper stage has an auxiliary head chip (25), and the lower stage has eight audio head chips (26).

[0004] The head assembly (27) is provided with a pair of head chips (28) and (29) for reproducing analog signals corresponding to the other one side area of the magnetic tape (22). By inverting the head assembly (27) by 180 degrees,
It is possible to perform recording and reproduction on both the A side and the B side of the magnetic tape (22).

[0005] In the DCC standard, subcodes such as a marker ID, a sector marker, and a future marker are defined as additional information in addition to time information and music number information. There are a label ID indicating a section, a sector marker ID indicating a program area, and the like. Sector markers include a reverse marker, a next marker, a home marker, a stop marker, a use-again marker, and the like. There is a mute marker and a fade marker.

The user can realize various recording and reproducing operations by recording these markers and IDs on a magnetic tape.

[0007]

However, at present, it is premised that various markers and IDs are manually recorded by the user. Therefore, the user must be familiar with the functions of the various markers and IDs beforehand. A recording operation must be performed in a timely manner to record a desired marker or ID. This is extremely complicated and difficult for ordinary users.

On the other hand, in a conventional analog audio tape recorder, when dubbing and recording an audio signal reproduced from another audio device such as a CD or DAT on a magnetic tape, as shown in FIG. The recording level is gradually reduced (attenuation). As a result, at the time of signal reproduction, the reproduction level is automatically reduced to zero when the tape approaches the end.

In order to realize such a fade-out operation, in a conventional audio tape recorder, when recording a signal, the remaining tape amount is measured by a rotation period detecting sensor provided coaxially with the tape take-up reel, and the remaining tape amount is measured. When the amount became equal to or less than a certain value, the attenuation process was started.

However, in this method, an error is unavoidable in the measurement of the tape remaining amount by the rotation period detecting sensor, so that the tape position (point B) where the reproduction level becomes zero as shown in FIG. May also shift forward. As a result, for example, during the auto-reverse operation, the time of the silent reproduction state E in the process of shifting from the side A to the side B becomes longer, and the user is uncomfortable.

On the other hand, in the DCC, a fade-out operation can be realized by using the above-described fade marker. However, as described above, the recording position of the marker must be determined by the user and the recording operation must be performed. However, problems similar to those of the conventional audio tape recorder remain.

An object of the present invention is to provide a fade-out method that can realize an accurate fade-out operation without requiring a user's judgment or operation in a DCC system.

[0013]

According to the fade-out method in the DCC system according to the present invention, when an audio signal supplied from an external audio device is recorded on a tape,
First, after recording the audio signal to the end of the tape without applying attenuation, the tape is rewound from the end by a tape length corresponding to the time t required to change the attenuation level for the audio signal from the minimum value to the maximum value, A fade marker is recorded at the tape position where the tape is rewound.

[0014]

The time t required to change the attenuator level from the minimum value to the maximum value is known in advance, and the tape length corresponding to the time t can be determined, for example, from the frequency generator attached to the capstan motor. Accurate measurement can be performed by counting the pulses, and the tape rewind control based on the measurement can be easily performed by a microcomputer or the like.

The operation of automatically recording a fade marker at the tape position rewound by the length of the tape can be easily realized by a microcomputer or the like.

In the case where a DCC recorded by the above-mentioned fade-out method is reproduced, when a fade marker is detected, the attenuate level changes from the minimum value to the maximum value from that point on, and the signal reproduction level gradually decreases. At the same time, the playback level becomes the lowest and the tape reaches the end.

[0017]

According to the fade-out method in the DCC system according to the present invention, an accurate fade-out operation can be realized without requiring a user's judgment or operation, and a silent reproduction state during an auto-reverse operation is avoided. You can do it.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. First, the circuit configuration of the DCC system will be described with reference to FIG.

An information signal such as an audio signal is supplied to an input terminal.
The signal is input from (1) to the A / D conversion circuit (2) and converted into a digital signal. The digital signal is supplied to a well-known PASC processing circuit (3), where data compression and high-efficiency encoding are performed.

The digital signal output from the PASC processing circuit (3) is input to the digital signal processing (4), where interleaving, addition of an error correction code, and addition of a subcode are performed. After 5), the signal is transmitted to the recording thin film multi-head 6 as a recording signal for 9 channels. Then, a signal is recorded on the magnetic tape (22) by the recording thin film multi-head (6).

The 9-channel signal reproduced from the magnetic tape (22) by the reproducing thin film multi-head (7) is supplied to an equalizer circuit (9) via a reproducing amplifier (8), and subjected to waveform equalization. , A PLL clock for extracting data is generated.

The output of the equalizer circuit (9) is sent to a digital signal processing circuit (10) and subjected to processing such as error correction. The processed signal is further supplied to a PASC processing circuit (11), and after being expanded in time axis and decoded, becomes an original digital signal.

The digital signal is converted to an analog signal via a D / A conversion circuit (12) and output from an output terminal (13) to a subsequent circuit.

The DCC magnetic tape (22) is a reel motor.
Winding and rewinding are performed by (14) and (17), and the tape is conveyed by capstan motors (15) and (16). The rotation of the capstan motors (15) and (16)
It is controlled by a motor control circuit (18).

A control circuit for controlling the entire system
(19) is equipped, and according to the information from the key input terminal (20) and the mechanical switch input terminal (21), the motor control circuit
(18), a control signal is issued to each mechanism such as the reel motors (14) and (17) and the tape running system.

Further, a code generation / decoding circuit (30) for generating and decoding sub-codes such as various markers and IDs is provided, and sub-codes are generated according to data exchange with the control circuit (19). The sub-code is sent to the digital signal processing circuit (4) or decoded from the digital signal processing circuit (10).

Here, the control circuit (19) and the code generation / decoding circuit (30) can be constituted not only by dedicated hardware but also by a microcomputer.

FIG. 3 shows the structure of main data recorded on eight tracks of the magnetic tape. One tape frame is composed of 32 data blocks and an inter-frame gap.
(IFG). The tape block has a header (3
Symbols) and a body (48 symbols), and one symbol is 10 bits. Further, one header is divided into a synchronization pattern, a frame address and a block address (“Nikkei Electronics”, supra).

FIG. 4 shows the data structure of the sub-code recorded on the auxiliary track. In order to suppress errors, the bit rate is reduced to 1/8 of that of the main data. Here, the various markers and IDs described above are recorded in the body of each tape block.

When the recording mode is set according to the operation key signals of the operation input terminals (20) and (21) and the mechanism detection signal at the time of recording, recording on the surface A is performed based on the control of the control circuit (19). Occasionally, the tape (22) runs in the forward direction at the normal 1 × speed, and the recording thin film multi-head
(6) scans the upper half of the tape (22). On the other hand, when recording on the side B, the magnetic tape (22) runs in the reverse direction at 1 × the speed of the standard mode, the head assembly is reversed, and the recording thin film multi-head (6) is moved below the tape (22). Scan half.

At this time, the sub-code generated by the code generation / decoding circuit (30), that is, various IDs such as LABEL indicating the head of each song, markers, and time information are sent to the digital signal processing circuit (4). , Track number, etc., and sub-code information with error correction code
It is supplied to the recording thin film multi-head (6) via (5) and is recorded on the auxiliary track of the magnetic tape (22).

FIG. 5 shows a procedure for dubbing and recording an audio signal reproduced by another audio device such as a CD or DAT on the A side of a tape. In addition, B
The same dubbing recording can be performed on the surface.

First, an audio signal is recorded to the end of the tape without performing attenuation (attenuation processing). Thereafter, the capstan motor (15) or (16) is reversed, and the tape is rewound from the end by the tape length corresponding to the time t required to change the attenuation level for the audio signal from the minimum value to the maximum value.

At this time, the tape rewinding amount is measured by counting pulses from a frequency generator (not shown) attached to the capstan motors (15) and (16). When the tape rewind amount reaches the tape length corresponding to the time t required to increase the attenuation level from the minimum value to the maximum value, a fade marker is recorded on the auxiliary track of the tape.

When reproducing the A side of the magnetic tape on which the audio signal and the fade marker are recorded in this manner, as shown in FIG. 6, the attenuator starts from the time when the fade marker is detected (point A). The level increases from the minimum value to the maximum value, the signal reproduction level gradually decreases, and the signal level becomes zero at the tape end position.

The operation of increasing the attenuation level from the minimum value to the maximum value based on the detection of the fade marker can be easily performed by, for example, gain adjustment by digital signal processing.

Accordingly, even during the auto-reverse operation for reproducing the side B after the reproduction of the side A, the silent reproduction state is avoided, and the user does not have to feel unpleasant.

The description of the above embodiments is for the purpose of illustrating the present invention and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a DCC system according to the present invention.

FIG. 2 is a perspective view of a head assembly provided in the DCC.

FIG. 3 is a diagram illustrating a data structure of main data.

FIG. 4 is a diagram illustrating a data structure of sub data.

FIG. 5 is a flowchart illustrating a fade-out method according to the present invention.

FIG. 6 is a diagram illustrating changes in a recording level and a reproduction level according to the present invention.

FIG. 7 is a diagram illustrating a change in a recording level and a problem of a fade-out operation in the related art.

[Explanation of symbols]

 (22) Magnetic tape (6) Recording thin film multi-head (7) Reproduction thin film multi-head (30) Code generation / decoding circuit

Claims (1)

(57) [Claims] 1. A plurality of sub-codes are recorded on one auxiliary track of a plurality of tracks extending in the longitudinal direction of a signal recording tape, and audio signals are recorded on other plural audio tracks. In a DCC (Digital Compact Cassette) system equipped with a multi-channel head, when recording an audio signal supplied from an external audio device on a tape, first record the audio signal to the end of the tape without applying attenuation, and then record the audio signal. The tape is rewound from the end by the tape length corresponding to the time t required to change the attenuation level for the signal from the minimum value to the maximum value, and a fade marker is recorded at the rewound tape position. From the time of detection of the fade marker, set the attenuation level to the minimum value. Fade-out method in DCC system and changing to the maximum value.