JPH04305852A - Magnetic reproducing device - Google Patents

Abstract

PURPOSE:To obtain a magnetic reproducing device capable of performing the tracking control of a market signal preferentially in a market signal display mode and of surely reproducing the market signal and to improve the convenience of using of a video tape recorder. CONSTITUTION:In this magnetic reproducing device especially such as the video tape recorder. etc., which reproduces a video signal from a recording track formed obliquely on a magnetic tape sequentially. it is possible to perform the tracking control of the market signal preferentially by switching the sample- and-hold time t 11 of a tracking error signal SER when the marker signal recorded with the video signal is reproduced, and to surely reproduce the marker signal.

Description

[Detailed description of the invention]

0001

[Table of Contents] The present invention will be explained in the following order. Industrial application field Conventional technology (Figure 5) Problems to be solved by the invention (Figures 5 to 8) Means for solving the problems (Figure 2) Effect (Figure 2) Example (1) Example of the example Configuration (FIGS. 1 to 4) (2) Operation of the embodiment (3) Effects of the embodiment (4) Effects of the invention of other embodiments

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic reproducing apparatus, and is particularly suitable for application to a video tape recorder which reproduces video signals from recording tracks sequentially formed diagonally on a magnetic tape.

0003

2. Description of the Related Art Conventionally, in this type of video tape recorder, a digital audio signal is recorded in a partial area of a recording track, and a time code etc. can be recorded between the recording areas of the digital audio signal and video signal. What has been done is proposed.

That is, as shown in FIG. 5, in a video tape recorder, an audio signal recording area PCM and a video signal recording area VD are formed in the longitudinal direction of recording track 1 (FIG. 5(A)), and the audio signal recording area VD is formed in the longitudinal direction of recording track 1 (FIG. 5(A)). Area P
Recording of the digital audio signal is completed 3 [H] minutes before the boundary of the CM and video signal recording area VD (represented by the symbol pcm).

Furthermore, in the video tape recorder, recording of the video signal is started after 3.8 [H] have elapsed from the boundary between the audio signal recording area PCM and the video signal recording area VD (represented by the symbol vd), and the audio signal is recorded. A predetermined area is secured between the recording area PCM and the video signal recording area VD.

Furthermore, in the video tape recorder, recording of the digital audio signal is completed and the recording time is 2.6.
After 5 [H] has elapsed, a marker signal ma (FIG. 5(B)) is recorded for a period of 1.5 [H], thereby recording a time code and the like on the magnetic tape 1. That is, in a video tape recorder, during playback, a window signal ea (FIG. 5(C)) that rises before and after the marker signal ma is formed, and the playback signal is taken in based on the window signal ea, so that the playback signal is Extract marker signal ma.

Here, the marker signal ma (FIG. 5(D)) is
A period of 1.26 [H] from the beginning is allocated to the header portion, and a search signal for cueing etc. is recorded as necessary.

On the other hand, the following 0.2 of the marker signal ma
The period 4 [H] is allocated for recording data such as time code (represented by the symbol dm), and 5 blocks of 8-bit data with a code start marker sm and a code end marker em placed before and after each are allocated. (Fig. 5(E)).

The five blocks of data include time code data, recording date and time, etc., which are sequentially and alternately recorded in frame units. As a result, even when variable speed playback is performed, for example, data such as time code, recording date and time, etc. can be played back without omission.

0010

[Problems to be Solved by the Invention] However, in this type of video tape recorder, ATF (automatic
Tracking control is performed using a tracking control method (trackfinding), thereby effectively avoiding deterioration in the quality of reproduced images due to tracking errors.

For this reason, as shown in FIG. 6, in the conventional tracking control system, a tracking error signal is detected at approximately the center (represented by symbol O) of the area where the video signal vd is recorded, and the tracking error signal is The tracking is controlled based on the .

As shown in FIG. 7, when reproducing at -1x speed, for example, the magnetic head scans diagonally across the recording track, so that the magnetic head scans the recording track on which the pilot signals of frequencies f1 and f4 are recorded. The reproduced signal SP obtained through the magnetic head at the scanning period (Fig. 7
In (A)), frequencies f2 and f4 and frequency f at the scanning start end and scanning end of the recording track, respectively.
The pilot signals 1 and f3 are reproduced, and the signal level of each pilot signal changes depending on the relative position of the magnetic head with respect to the recording track.

For this reason, in conventional tracking control, the reference signal SREF for tracking error detection (FIG. 7(B)) is sequentially switched according to the playback speed, and
The error signal SER is sampled at time t1 when the magnetic head scans approximately the center O of the video signal recording area (FIG. 7(C)). Furthermore, in video tape recorders,
The sampled tracking error signal SER is output to the capstan drive circuit at a predetermined time t2, and the tracking error signal SER is outputted to the capstan drive circuit at a predetermined time t2.
Tracking control is performed so that the tracking error signal detected in is set to 0 level.

[0014] Accordingly, in conventional tracking control, tracking control is performed with priority given to the video signal vd even when the video signal is played back at -1 times the speed, for example.

However, in this case, for example, in the magnetic head HB having a negative azimuth angle, the recording track TB having the same azimuth angle can be scanned at the central portion O of the recording track, whereas the scanning start and the end of the scanning of the recording track At the end, recording tracks TB with different azimuth angles are scanned. For this reason, in the video signal, noise areas (represented by hatching) appear at the top and bottom of the display screen, as shown in Figure 8.
It is possible to effectively avoid deterioration in image quality by reproducing the image in its original state.

However, since the marker signal ma is reproduced by magnetic heads having different azimuth angles, the azimuth loss becomes large and there is a problem that the reproduced signal cannot be reliably demodulated. Therefore, when variable speed playback is performed in, for example, editing work, the conventional tracking control system has the problem that the time code and the like that have been recorded with great effort cannot be used.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a magnetic reproducing device that can reliably reproduce marker signals even during variable speed reproduction.

[0018]

[Means for Solving the Problems] In order to solve the above problems, in the present invention, recording tracks TA and TB are sequentially formed diagonally in the longitudinal direction of the magnetic tape 1, and the recording tracks TA and TB are formed obliquely in the longitudinal direction of the magnetic tape 1, respectively, to provide an audio signal pcm, a marker signal ma, and a video signal. In a magnetic reproducing device 2 that reproduces the magnetic tape 1 and outputs an audio signal pcm, a marker signal ma, and a video signal vd, the magnetic head is 6 is the predetermined timing t1, t1 for scanning the recording tracks TA, TB.
1, tracking error detection circuits 12, 14, 16, 18, 20, and 22 detect tracking error signals SER for the recording tracks TA and TB of the magnetic head 6; tracking control circuits 4, 24, 26, 30, and 32 that control the traveling speed of the magnetic head 1 to perform tracking control; a video signal processing circuit 8 that reproduces and outputs the video signal SV output from the magnetic head 6; an audio signal processing circuit 8 that reproduces and outputs the audio signal SO output from the magnetic head 6; and a marker signal m output from the magnetic head 6;
tracking error detection circuits 12, 14, 16,
18, 20, and 22 are areas where the video signal vd is recorded by detecting the tracking error signal SER at timing t1 when the magnetic head 6 scans the area where the video signal vd is recorded in the video signal reproduction mode. In the marker signal reproduction mode, the area where the marker signal ma is recorded is tracked by the magnetic head 6.
By detecting the tracking error signal SER at the scanning timing t11, tracking control is performed centering on the area where the marker signal ma is recorded.

[0019]

[Operation] In the video signal reproduction mode, the timing t when the magnetic head 6 scans the area where the video signal vd is recorded.
If the tracking error signal SER is detected in step 1 and tracking control is performed centering on the area where the video signal vd is recorded, the tracking control can be performed with priority given to the video signal vd.
In the marker signal reproduction mode, timing t11 when the magnetic head 6 scans the area where the marker signal ma is recorded.
If the tracking error signal SER is detected and the tracking is controlled centering on the area where the marker signal ma is recorded, the tracking can be controlled with priority given to the marker signal ma. It is also possible to reliably reproduce the marker signal ma.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Configuration of the Embodiment In FIG. 1, 2 indicates a video tape recorder as a whole, and by controlling the rotational speed of the capstan 4,
Tracking control is performed by controlling the running speed of the magnetic tape 1.

That is, in the video tape recorder 2, the reproduced signal SP obtained through the magnetic head 6 is outputted to the reproduced signal processing circuit 8, where the reproduced signal SP is demodulated to produce a video signal SV and an audio signal SO. Output.

When demodulating the reproduced signal SP, the reproduced signal processing circuit 8 outputs the reproduced signal SP to the marker signal processing circuit 10 at a predetermined timing, whereby the marker signal processing circuit 10 demodulates the marker signal ma. It is made to be obtained. A low pass filter circuit (LPF) 12 extracts a pilot signal for tracking control from the reproduced signal SP and outputs it to a multiplication circuit 14.

The multiplication circuit 14 receives a predetermined reference signal SREF.
and the pilot signal, and outputs the multiplied signal to bandpass filter circuits (BPF) 16 and 18.

Here, the bandpass filter circuits 16 and 1
8 separates the signal components of the multiplication signal for the preceding and following recording tracks by band-limiting the multiplication signal, and then performs envelope detection on the separated signal components.

The subtraction circuit 20 subtracts the envelope detection outputs output from the bandpass filter circuits 16 and 18,
As a result, a tracking error signal SER is generated and output to the sample hold circuit (S/H) 22.

The sample and hold circuit 22 samples and holds the tracking error signal SER at a predetermined timing, and outputs the sample and hold result to the selection circuit 24.

Here, the selection circuit 24 directly inputs the output signal of the sample-and-hold circuit 22 into one contact, and inputs the output signal of the sample-and-hold circuit 22 through the inverting amplifier circuit 26 into the other contact. Furthermore, selection circuit 2
4 switches the contacts based on the control signal output from the system control circuit 28, thereby selectively outputting the tracking error signal SER or its inverted signal, thereby eliminating the so-called backlash that may occur during tracking control. It is designed to effectively avoid locking.

The capstan drive circuit 30 is connected to the selection circuit 2.
4 is taken in at a predetermined timing, and the rotation of the capstan motor is controlled based on the output signal.

Thus, in the video tape recorder 2, the running speed of the magnetic tape 1 sandwiched between the capstan 4 and the pinch roller 32 is controlled based on the tracking error signal, and tracking can be controlled reliably. .

The system control circuit 28 controls a predetermined operator 3.
In response to the operation 4, the operation mode of the video tape recorder 2 as a whole is switched. Furthermore, the system control circuit 28
outputs the time code data etc. output from the marker signal processing circuit 10 to the display section 36 as needed, thereby displaying the time code data etc. on the display section 36.

Further, the system storage circuit 28 switches to the video signal display mode when a predetermined operator 34A is turned on. In this state, the system control circuit 28 outputs control signals to the sample and hold circuit 22, the selection circuit 24, and the capstan drive circuit 30, thereby causing the video tape recorder 2 to operate at the same timing as in the prior art, as described above with reference to FIG. Tracking and control.

As a result, in the video tape recorder 2, in the video signal display mode, the video signal vd
Tracking control is given priority.

On the other hand, when the system control circuit 28 enters the marker signal reproduction mode, the system control circuit 28 controls the sample and hold circuit 2.
2 and the capstan drive circuit 30, thereby giving priority to the marker signal ma and performing tracking control. That is, as shown in FIG. 2, the system control circuit 28 switches the sampling and holding time t11 of the tracking error signal SER, and thereby outputs the tracking error signal at the timing when the magnetic head 6 scans the area where the marker signal is recorded. Sample and hold the SER.

That is, as shown in FIG. 3, the marker signal m
In the area where a is recorded, the magnetic head 6 with the same azimuth angle
When the recording track TB is held so as to scan the corresponding recording track TB, the reproduced signal SP obtained through the magnetic head 6 during variable speed reproduction of, for example, -1x speed (FIG. 2(A)
)), the timing at which the frequency of the pilot signal changes is held at a position shifted from that in the normal reproduction state.

Here, the system control circuit 28 outputs a control signal to a reference signal reproducing circuit (not shown), for example, -1
When performing variable speed playback at double speed, the reference signal SRE whose frequency changes in the order of f1 and f4 in synchronization with the rotation period of the rotating drum.
F (FIG. 2(B)) is generated.

[0037] As a result, when playing at the -1x speed,
When the magnetic head 6 is held so as to scan the recording track TB with the same azimuth angle in the area where the marker signal ma is recorded, the tracking error signal SER (FIG. 2(C)
), the signal level changes in the shape of a triangular wave. Therefore, the system control circuit 28 outputs a control signal to the sample and hold circuit 22 at the time t11 when the magnetic head 6 scans the area where the marker signal ma is recorded, and thereby samples and holds the tracking error signal SER at the time t11. do.

In practice, the timing at which the tracking error signal SER is sampled and held is generated based on the switching pulse signal synchronized with the rotation of the rotating drum. By sampling and holding the tracking error signal SER at a timing of 9200 [μsec] from the signal change point, tracking control can be performed with priority given to the video signal, whereas in this embodiment, the tracking error signal SER is sampled and held at a timing of 9200 [μsec] from the signal change point.
By capturing the marker signal at a timing of [μsec], it was possible to perform tracking control with priority given to the marker signal ma.

By giving priority to the marker signal ma in tracking control, the marker signal ma can be reliably reproduced and the efficiency of editing work etc. can be improved.

Furthermore, at this time, in this embodiment,
By switching the sample hold timing according to the user's desired operation mode, it is possible to obtain a reproduced image without noise in the center of the screen in the video signal reproduction mode, for example, whereas in the marker signal reproduction mode, it is possible to obtain a reproduced image without noise in the center of the screen. As shown in FIG. 3, a reproduced image with a lot of noise in the center of the screen can be obtained.

[0041] Therefore, easy-to-see images can be reproduced as needed, and the usability of the video tape recorder 2 can be improved.

(2) Operation of the Embodiment In the above configuration, the reproduction signal SP obtained through the magnetic head 6 is multiplied by the reference signal SREF in the multiplication circuit 14 after the pilot signal is extracted by the low-pass filter circuit 6. be done.

As a result, the pilot signal is separated into signal components of the preceding and following recording tracks by the bandpass filter circuits 16 and 18, respectively, and then subjected to envelope detection, and the subtraction circuit 20 generates the tracking error signal SE.
Converted to R. The tracking error signal SER is sampled and held at a predetermined timing by the sample and hold circuit 22, and the sample and hold result is outputted to the capstan drive circuit 30.

As a result, the running speed of the magnetic tape 1 changes according to the rotational speed of the capstan 4, and the signal level sampled and held by the sample and hold circuit 22 becomes 0.
Tracking is controlled to match the level.

In this state, the sample hold circuit 22
In the video signal display mode, the tracking error signal SER is sampled and held at the timing when the magnetic head 6 scans the approximately central portion O of the area where the video signal vd is recorded, and thereby the tracking control is performed with priority given to the video signal vd. Can be done.

On the other hand, in the marker signal reproduction mode, the sample and hold circuit 22 samples and holds the tracking error signal SER at the timing when the magnetic head 6 scans the area where the marker signal ma is recorded. Tracking control can be performed with priority given to the marker signal ma, and the marker signal ma can be reliably reproduced.

(3) Effects of the embodiment According to the above configuration, in the marker signal display mode,
By switching the sample and hold timing of the tracking error signal SER and sample and hold the tracking error signal SER at the timing when the magnetic head 6 scans the area where the marker signal ma is recorded, tracking is performed with priority given to the marker signal ma. The marker signal ma can be reliably reproduced. Therefore, the usability of the video tape recorder can be improved accordingly in editing work and the like.

(4) Other Embodiments In the above-mentioned embodiments, when playing back at -1x speed, the sample and hold timing is switched between the video signal display mode and the marker signal display mode. The invention is not limited to this, but the sample and hold timing can be switched in various variable speed reproduction modes to reliably reproduce the marker signal.

Further, in the above-described embodiment, a case was described in which data such as time code data and recording date and time were recorded as the marker signal ma, but the present invention is not limited to this, and various data can be recorded as necessary. It can be widely applied when

[0050]

As described above, according to the present invention, in the marker signal display mode, by switching the sample and hold timing of the tracking error signal to perform tracking control, it is possible to perform tracking control with priority given to the marker signal. Thus, it is possible to obtain a magnetic reproducing device that can reliably reproduce the marker signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a video tape recorder according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation.

FIG. 3 is a schematic diagram showing the scanning locus of the magnetic head.

FIG. 4 is a schematic diagram showing the displayed image.

FIG. 5 is a signal waveform diagram for explaining recording of a marker signal.

FIG. 6 is a schematic diagram showing a scanning locus of a conventional magnetic head.

FIG. 7 is a signal waveform diagram for explaining the operation.

FIG. 8 is a schematic diagram showing the displayed image.

[Explanation of symbols]

1...Magnetic tape, 2...Video tape recorder, 8...
...Reproduction signal processing circuit, 12...Low pass filter circuit,
14... Multiplication circuit, 16, 18... Band pass filter circuit, 22... Sample hold circuit, 28... System control circuit.

Claims (1)

[Claims] 1. A magnetic tape in which recording tracks are sequentially formed obliquely in the longitudinal direction of the magnetic tape, and audio signals, marker signals, and video signals are sequentially recorded in predetermined areas of each of the recording tracks. In a magnetic reproducing device that reproduces and outputs the audio signal, the marker signal, and the video signal, a tracking error signal of the magnetic head with respect to the recording track is detected at a predetermined timing when the magnetic head scans the recording track. a tracking error detection circuit for controlling the running speed of the magnetic tape based on the tracking error signal, and a tracking control circuit for controlling the tracking by controlling the running speed of the magnetic tape, and reproducing and outputting the video signal output from the magnetic head. an audio signal processing circuit that reproduces and outputs the audio signal output from the magnetic head; and a marker signal processing circuit that reproduces and outputs the marker signal output from the magnetic head. The above tracking error detection circuit includes:
In the video signal reproduction mode, tracking is controlled centering on the area where the video signal is recorded by detecting the tracking error signal at the timing when the magnetic head scans the area where the video signal is recorded; In the marker signal reproduction mode, tracking control is performed centering on the area where the marker signal is recorded by detecting the tracking error signal at the timing when the magnetic head scans the area where the marker signal is recorded. A magnetic reproducing device featuring: