JP2616938B2 - Rotating head type recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a rotary head type digital audio tape recorder (hereinafter, referred to as R-DAT) and the like, and uses pulse code modulation (hereinafter, referred to as PCM). A rotary head type recording / reproducing apparatus configured to record / reproduce a digital signal such as audio signal or the like formed on a recording medium by using a rotary head mounted on a drum to form a track oblique to the longitudinal direction thereof. It is about.

[Prior art] In a conventional general R-DAT, two heads having different azimuth angles are mounted on a rotating drum at a rotation angle of about 180 °, and the two heads are attached to the drum by these two heads. The digital signal is recorded and reproduced by forming tracks one by one alternately on a tape wound about 90 °. The rotation of the drum at this time is controlled so as to be phase-synchronized with a drum reference signal obtained by dividing the frequency of a master clock generated by a crystal oscillator or the like. For example, when the diameter of the drum is a standard 30 mm, the drum reference signal is a signal of about 33 Hz.

By the way, in R-DAT, after-recording for reproducing the PCM audio signal area and rewriting the contents of the sub-code area while outputting the reproduced sound, or when new recording is performed following the already-recorded track, the connection is established. Recording is performed. In such a case, it is important to prevent abnormal recording from occurring or noise from being generated in the reproduced sound at the switching point between the recording mode, the reproduction mode, and the after-recording mode.

[Problems to be Solved by the Invention] As described above, in the case of the conventional general rotary head type recording / reproducing apparatus, the rotational phase of the drum at the switching point between the recording mode, the reproducing mode, and the after-recording mode, There were problems such as abnormal speed and noise in abnormal recording and playback sound due to irregularities in speed.

The present invention has been made in order to solve the above problems, and without causing disturbance of the rotation phase of the drum,
It is an object of the present invention to provide a rotary head type recording / reproducing apparatus which can smoothly switch between modes.

[Means for Solving the Problems] A rotary head type recording / reproducing apparatus according to the present invention uses a rotary head mounted on a drum to transmit a digital signal to a rack formed obliquely on a recording medium with respect to its longitudinal direction. In a rotary head type recording / reproducing apparatus configured to perform recording / reproduction, a signal processing means for performing encoding / decoding, and a control means for controlling rotation of the rotary drum so as to be phase-synchronized with a drum reference signal, A timing control means for generating a drum reference signal to be supplied to the control means and an operation mode switching signal of the signal processing means, wherein the operation mode switching signal is used to switch the rotation mode when switching between a recording mode and a reproduction mode. The operation mode of the signal processing means is changed to the recording mode while keeping the rotation phase of the drum and the phase of the drum reference signal constant. The switching is performed at different timings corresponding to the respective playback modes.

[Operation] According to the present invention, at the time of switching between the recording mode, the reproduction mode, and the after-recording mode, the phase of the operation mode switching signal for the signal processing is changed while maintaining the phase of the drum reference signal constant. Since the switching is controlled in accordance with the mode, the rotation phase of the drum is not disturbed, and the mode is switched smoothly.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a rotary head type recording / reproducing apparatus according to one embodiment of the present invention. In FIG. 1, (1) is a rotary drum, and (2a) and (2b) are rotary heads. They are mounted on the rotating drum (1) with different azimuth angles. (3) is a magnetic tape as a recording medium, which is wound around the rotating drum (1) in a rotation angle range of about 90 ° and travels. (4) is a head switching switch for selectively connecting one of the two heads (2a) and (2b). (5) is a recording / reproduction switching switch, which is switched by recording / reproduction.

(6) is a reproduction amplifier, (7) is a demodulation and synchronization detection circuit, (8) is a data bus, (9a) and (9b) are RAM1 and RAM.
2, (10) is a correction and encoding circuit, (11) is a RAM address generation circuit, (12) is a correction circuit, (13) is a D / A converter, (14a) and (14b) are audio signal output terminals, (15
a) and (15b) are audio signal input terminals, (16) is A / D
Converter, (17) modulation and synchronization signal addition circuit,
(18) is a recording amplifier, (19) is a timing control circuit,
(20) is a servo control circuit, (21) is a drum motor, (2)
2) is a drum pulse generator, (23) is a key input terminal for giving commands such as recording and stop from outside, and (24) is a micro computer, which controls the entire system.

Next, the recording / reproducing operation of the entire apparatus having the above configuration will be schematically described.

The audio signals supplied to the input terminals (15a) and (15b) during recording are converted into PCM signals by the A / D converter (16), and are transferred to the RAM1 (9a) or RA1 via the data bus (8).
Written to M2 (9b). This PCM signal is read from RAM1 (9a) or RAM2 (9b) and applied to a correction and encoding circuit (10), where an error correction code is generated and added, and then RAM1 (9a) or RAM2 (9b). ) Is stored in a predetermined area. Thereafter, the PCM audio signal and the error correction code are read from RAM1 (9a) or RAM2 (9b), and are applied to the modulation and synchronization signal adding circuit (17) via the data bus (8).
, Is subjected to 8-10 modulation, and a synchronization signal and a block address signal are added. Then, this signal is supplied to a recording / reproducing switch (5) via a recording amplifier (18), and further distributed to two heads (2a) and (2b) by a head switching switch (4). The data is recorded on the magnetic tape (3) by the heads (2a) and (2b).

Also, at the time of reproduction, the head (2a),
The signal reproduced by (2b) is amplified by a reproduction amplifier (6) via a head switching switch (4) and a recording / reproducing switching switch (5) and input to a demodulation and synchronization signal detection circuit (7). You. The reproduction clock is extracted in the demodulation and synchronization signal detection circuit (7), and after the synchronization signal is detected and 10-8 demodulated and returned to the original PCM signal, the RAM1 (RAM) is connected via the data bus (8). 9a) or
Written to RAM2 (9b). This signal is subjected to error detection and error correction by a correction and encoding circuit (10),
PC read from RAM1 (9a) or RAM2 (9b) and supplied to correction circuit (12)
The M signal is corrected by means such as mean value interpolation, and then D
After being converted back to an analog signal by the / A converter (13), it is separated into a right channel and a left channel and output from the audio output terminals (14a) and (14b). In both the recording and reproduction, the RAM address is given by a RAM address generation circuit (11) for reading and writing signals to and from RAM1 (9a) and RAM2 (9b).
The write address to is generated based on the reproduced block address signal given from the demodulation circuit (7).

On the other hand, the servo control circuit (20) receives a drum reference signal (hereinafter, referred to as a DRF signal) from the timing control circuit (19), and further receives a signal (22) from a pulse generator (22) for obtaining one pulse per drum rotation. Hereinafter, a DPG signal is obtained, the phase is compared with the DRF signal, and the rotation of the drum motor (21) is controlled by the error signal.

In addition, the key input terminal (23) is used for recording mode from outside,
A mode such as a reproduction mode is input, and this is received by the microcomputer (24), and a command of each mode is given to the timing control circuit (19). This timing control circuit (1
In 9), based on the master clock generated by the crystal oscillator and the clock obtained by dividing the master clock, a clock signal for controlling the timing of each circuit is generated in addition to the DRF signal described above.

Next, the operation at the time of switching from the reproduction mode to the recording mode will be described with reference to FIG.

FIG. 2A shows a signal recorded or reproduced by two heads (2a) and (2b).
Is a positive azimuth angle track signal, and (B) is a negative azimuth angle track signal. FIG. 2B shows a DRF signal having a frequency of about 33 HZ obtained from the timing control circuit (19). The phase of this DRF signal and the DPG signal shown in FIG. Servo is applied to synchronize.

Now, it is the reproduction mode at first, and when a command to switch to the recording mode is given from the microcomputer (24) to the timing control circuit (19) at the timing shown in FIG. The timing is reset, and the signal processing unit such as the correction and coding circuit (10) is switched from the reproduction mode to the recording mode at the timing shown in FIG.

FIGS. 2 (h) and (i) show RAM1 (9a) and RAM2 (9b)
The two RAMs (9a) and (9b) alternately perform an operation in which one of the RAMs (9a) and (9b) performs a write error correction process while the other reads and supplies the read signal to the correction circuit (12). Do it. Switching between the operations of the two RAMs (9a) and (9b) is performed by a memory switching signal (hereinafter, referred to as an MSL signal) shown in FIG. 2 (g). Processing is performed based on a head switching signal (hereinafter, referred to as an HSL signal) shown in FIG.
Switching of the AM address is performed.

During playback, as shown in FIGS. 2 (h) and (i), RA
M (9a) and (9b) store the reproduced PCM signal for one track, correct the error for each track, read out during the next rotation of the drum, and generate it during the rotation of the drum during recording. The stored PCM signal is stored in the RAMs (9a) and (9b) and then encoded and recorded for each track, so that the phases of the MSL signal and the HSL signal are 90 ° in the reproduction mode and the recording mode. It differs by the rotation angle. So this MS
The L signal and the HSL signal are each switched to a state in which the phase is advanced by 90 ° at the time of transition to the recording mode shown in FIG. 2 (e), and from that point, the mode transits to the RAM operation mode of the recording mode. However, at this point, the tape (3)
Since a signal to be recorded is not prepared on the upper side and a signal to be recorded after one rotation of the drum is prepared, an amplifier recording / reproduction switching signal for starting recording on the tape is as shown in FIG. 2 (j). At the timing shown, the mode is switched to the recording mode, which is supplied to the switching switch (5) to start the actual recording.

Next, the operation at the time of switching from the recording mode to the reproduction mode will be described with reference to FIG.

As in the case of switching from the reproduction mode to the recording mode described above, so that the phases of the DPG signal and the DRF signal are synchronized,
The drum is controlled and the DRF signal is always in a fixed phase. Then, at the timing shown in FIG. 3 (d), for example, in the first recording mode, a command to switch to the reproduction mode is given from the microcomputer (24) to the timing control circuit (19). The timing control circuit (19) switches the correction and encoding circuit (10) from the encoding operation to the correcting operation at the timing shown in FIG. 3 (e), and rotates the phases of the MSL signal and the HSL signal by 90 °. The signal processing unit is switched from the recording mode to the reproduction mode by switching to be delayed by an angle. At the same time, as shown in FIG. 3 (j), the amplifier recording / reproduction switching signal is also switched to the reproduction mode, so that the reproduction signal is started to be written to the RAM from this point.

In the above description of the embodiment, switching between the recording mode and the reproduction mode has been described.
The same applies to the switching between the after-recording mode in which only the audio signal area is recorded and the reproduction mode.

[Effects of the Invention] As described above, according to the rotary head type recording / reproducing apparatus according to the present invention, the rotary head mounted on the drum forms the digital data on the track formed obliquely to the longitudinal direction on the recording medium. In a rotary head type recording / reproducing apparatus configured to record / reproduce a signal, signal processing means for performing encoding / decoding, and control means for controlling rotation of the rotary drum so as to be phase-synchronized with a drum reference signal And a timing control means for generating a drum reference signal supplied to the control means and an operation mode switching signal of the signal processing means. When the operation mode switching signal is switched between a recording mode and a reproduction mode,
The operation mode of the signal processing means is switched at different timings corresponding to the recording mode and the reproduction mode, respectively, while keeping the rotation phase of the rotary drum and the phase of the drum reference signal constant. When switching, there is no disturbance in the rotation phase and speed of the drum,
Therefore, there is an effect that the mode switching can be performed favorably and smoothly without abnormal recording at the time of mode switching or noise mixing in reproduced sound.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a rotary head type recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining operation timing when switching from a reproducing mode to a recording mode, and FIG. FIG. 4 is a signal waveform diagram illustrating operation timing when switching from a recording mode to a reproduction mode. (1) ... drum, (2a), (2b) ... rotating head,
(9a), (9b): RAM, (10): Correction and coding circuit, (11): RAM address generation circuit, (19): Timing control circuit, (20): Servo control circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A rotary head type recording / reproducing apparatus configured to record / reproduce a digital signal on a track formed on a recording medium obliquely to its longitudinal direction by a rotary head mounted on a drum. Signal processing means for performing decoding and decoding; control means for controlling the rotation of the rotary drum so as to synchronize the phase with the drum reference signal; drum reference signals supplied to the control means and operation modes of the signal processing means Timing control means for generating a switching signal, wherein the operation mode switching signal is configured to keep the rotation phase of the rotary drum and the phase of the drum reference signal constant when switching between the recording mode and the reproduction mode. Switching the operation mode of the signal processing means at different timings corresponding to the recording mode and the reproduction mode, respectively. A rotary head type recording / reproducing apparatus characterized in that it can be obtained.