JP3318764B2 - Recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus suitable for application to, for example, a helical scan type VTR.

[0002]

2. Description of the Related Art In a conventional helical scan type VTR, the recording current level of a rotary magnetic head is fixed after being adjusted to an optimum recording current (ORC) level at the time of shipment.

[0003]

However, if the gap depth and gap length change due to wear of the head due to aging, the optimum recording current level changes, which is a serious cause of image quality deterioration. For example, the relationship between the recording current level and the reproduction signal level at the time of shipment is as shown by a solid line a in FIG. 3 and the optimum recording current level is ia. The relationship with the level changes as shown by the broken line a 'in the figure, and the optimum recording current level moves to ia'.

Since the optimum recording current level differs depending on the magnetic tape, when the recording current level is fixed, the performance of the magnetic tape cannot be maximized.

Therefore, an object of the present invention is to enable recording at an optimum recording current level at all times.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a first area for recording by changing a recording current level at a predetermined rate on an inclined recording track and a first area for recording at a constant recording current level are provided. A second area for recording information of a recording current level is formed, and a reproduction signal from a first area recorded at a plurality of recording current levels is recorded based on the information of the recording current level reproduced from the second area. Each level is detected, and the recording current level during recording is controlled based on the detected output.

[0007]

In the above arrangement, the reproduction signal levels corresponding to a plurality of recording current levels changed at a predetermined rate are detected, and the optimum recording current level is determined from the detected output, and the recording current level during recording is optimized. The recording current level is set. Therefore, even when the magnetic head is worn due to a change over time or when the type of the magnetic tape is changed, recording at the optimum recording current level can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This example is an example applied to a helical scan type VTR, and an audio signal is recorded as a PCM audio signal together with an FM video signal on an inclined recording track.

In FIG. 1, 1 is a rotary head device, 2 is a tape guide drum, and 3A and 3B are rotary magnetic heads. The magnetic tape 4 is obliquely wound around the tape guide drum 2 over a range of approximately 221 °.

The heads 3A and 3B are arranged at an angular interval of 180 ° from each other, and each of them has one frame period (NTSC).
(1/30 second in the system). The heads 3A and 3B have different azimuth angles from each other.

For example, NTS supplied to the video input terminal 5
The video signal Vin of the C system is supplied to the FM modulator 6. F
A carrier (carrier) is supplied from the reference signal generator 21 to the M modulator 6, and FM modulation is performed.

The FM video signal output from the FM modulator 6 is supplied to a recording level adjuster 7. The recording level adjuster 7 controls the level of the FM video signal under the control of the CPU 8, thereby adjusting the recording current level.

The F level adjusted by the recording level adjuster 7
The M video signal is supplied to the heads 3A and 3B via the switch circuit 9 and the recording amplifier 10, and is recorded.

FIG. 2 shows a recording track pattern on the magnetic tape 4. Ta is a recording track formed by the head 3A, while Tb is a recording track formed by the head 3B. The above-described FM video signal is stored in the video signal recording area ARv (180) of each of the recording tracks Ta and Tb.
(Range of °) for each field.

The audio signal Ain supplied to the audio input terminal 11 is supplied to an audio processor 12 and converted into a PCM audio signal by recording signal processing. The PCM audio signal output from the audio processor 11 is supplied to the head 3A,
3B for recording.

This PCM audio signal is recorded on each recording track T
In the audio signal recording area ARa (range of 36 °) of a and Tb, one field is recorded (see FIG. 2).

Reference numeral 13 denotes an index processor. The processor 13 outputs an index signal such as a time code and recording current level data to be described later under the control of the CPU 8. The index signal output from the processor 13 is supplied to the heads 3A and 3B via the switch circuit 9 and the recording amplifier 10 and recorded.

This index signal is recorded in an index signal recording area ARi located between the areas ARv and ARa of the recording tracks Ta and Tb (see FIG. 2).
The time code indicates, for example, hours, minutes, seconds, and the absolute elapsed time of a frame.

A reproduction signal reproduced by the heads 3A and 3B from the tape 4 is supplied to a switch circuit 15 via a reproduction amplifier 14, and reproduced from the areas ARv, ARa and ARi of the recording tracks Ta and Tb. Signals are separated from each other.

Area AR output from switch circuit 15
The reproduced signal v (FM video signal) is supplied to the FM demodulator 16 and FM-demodulated. The video signal Vout output from the FM demodulator 16 is output to a video output terminal 17.

The reproduced signal in the area ARv is supplied to a detector 19, for example, where peak detection is performed. The detected output is converted into a digital signal by an A / D converter 20 and supplied to the CPU 8. This detection output is used when setting a recording current level at the time of recording as described later.

The reproduction signal (PCM audio signal) in the area ARa output from the switch circuit 15 is supplied to the audio processor 12 and subjected to reproduction signal processing. The audio signal Aout output from the audio processor 12 is output to an audio output terminal 18.

A reproduction signal (index signal) of the area ARi output from the switch circuit 15 is supplied to the CPU 8 via the processor 13. In CPU 8,
Various controls using this index signal are possible.

In the present embodiment, the recording level in the recording level adjuster 7 is adjusted as follows.

First, the reference signal generator 2 is output from the FM modulator 6.
1 is output as it is, and the level of this carrier is sequentially changed at a predetermined ratio by the recording level adjuster 7 under the control of the CPU 8, and is sequentially recorded in the areas ARv of the plurality of recording tracks Ta and Tb. You. At this time, the recording level data used for controlling the recording level adjuster 7 is generated by the processor 13 as an index signal, and is sequentially recorded together with the time code in the areas ARi of the recording tracks Ta and Tb. As described above, the area AR
Even if the recording level of the carrier wave recorded in v changes, the recording level of the recording level data recorded in the area ARa and the recording level of the time code index signal are kept constant.

Next, using the time code reproduced from the area ARi, for example, the tape 4 is rewound to the recording start time of the above-described carrier wave, and is reproduced until the recording end time.
Instead of rewinding the tape 4, reverse playback may be performed until the recording start time.

At the time of this reproduction, the CPU 8 detects and outputs the detection output of the reproduction signal of the area ARv supplied from the A / D converter 20 and the recording level data reproduced from the area ARi supplied from the processor 13. Is detected, the recording level data at which is the maximum.

The recording level adjuster 7 has a CPU 8
The control is fixed with the recording level data that maximizes the detection output detected in step (1). This means that the recording current level has been adjusted to the optimum recording current level.

The recording level adjustment by the recording level adjuster 7 described above is performed, for example, at predetermined time intervals, during a recording operation.
It is automatically performed at the time of tape exchange or user operation.

As described above, in the present embodiment, the recording current level is automatically adjusted so as to attain the optimum recording current level. Therefore, even when the head is worn out due to a change with time and the gap depth, the gap length and the like are changed, and the optimum recording current is changed, it is possible to prevent the image quality from deteriorating. Even when magnetic tapes having different optimum recording current levels are used, the performance of the magnetic tape can be maximized.

In the above embodiment, the carrier is recorded and reproduced in the video signal recording area ARv to adjust the recording current level. However, the CPU 8 controls the reference signal generator 21 to control the reference current. The signal generator 21 may generate a signal having a frequency different from that of the carrier, and record and reproduce the frequency signal in the area ARv to adjust the recording current level.

In the above embodiment, when adjusting the recording level in the recording level adjuster 7, the recording level data is recorded together with the time code in the index signal recording area ARi. If there is a correspondence between
Only the time code may be recorded. In this case, the time code also serves as the recording level data.

In the above embodiment, the reference signal (carrier) is recorded / reproduced in the video signal recording area ARv and the FM signal is recorded.
Although the recording current level of the video signal is adjusted, a reference signal may be recorded and reproduced in the audio signal recording area ARa to adjust the recording current level of the PCM audio signal.

Although the above embodiment is applied to a helical scan type VTR, the present invention can be similarly applied to other recording / reproducing apparatuses for recording / reproducing with a rotary head via an inclined recording track. .

Although different from the above-described embodiment, the frequency characteristics of recording and reproduction can be obtained by changing the frequency of the reference signal to be recorded in various ways and detecting the level of the reproduced signal in each case. In the reproduction system, adaptive equalization can be performed based on the frequency characteristics.

[0036]

According to the present invention, the recording current level is automatically adjusted so as to obtain the optimum recording current level. Therefore, the head wears due to the change with time, and the gap depth and the gap length are changed. Even when the recording current changes, it is possible to prevent deterioration in image quality and the like. Even when magnetic tapes having different optimum recording current levels are used, the performance of the magnetic tape can be maximized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment.

FIG. 2 is a diagram showing a recording track pattern.

FIG. 3 is a diagram showing a relationship between a recording current level and a reproduction signal level.

[Explanation of symbols]

 Reference Signs List 1 rotating head device 3A, 3B rotating magnetic head 4 magnetic tape 5 video input terminal 6 FM modulator 7 recording level adjuster 8 CPU 9, 15 switch circuit 11 audio input terminal 12 audio processor 13 index processor 16 FM demodulator 17 video output Terminal 18 Audio output terminal 19 Detector 21 Reference signal generator

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-245302 (JP, A) JP-A-3-242803 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/027

Claims (1)

(57) [Claims] 1. A first area for recording by changing the recording current level at a predetermined rate on a tilted recording track, and information on the recording current level of the first area at a constant recording current level. A second area is formed, and a level of a reproduction signal from the first area recorded at a plurality of recording current levels is detected based on the information on the recording current level reproduced from the second area. And a recording / reproducing apparatus for controlling a recording current level during recording based on the detection output.