JPH11331772A - Digital video tape recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a failure due to a step-out in a very short time by allowing an input signal to acquire internal synchronism fast by making an input synchronizing signal acquire the synchronism with a track synchronizing signal and resetting a track number, when acquisition is fixed. SOLUTION: Image data of one frame are formed as (n) tracks on a magnetic recording medium by making a scan by a rotary head (n) times (n>1). A synchronism control part 1 performs PLL control, based upon the input synchronizing signal (a) as a reference to output the frame synchronizing signal (b) and track synchronizing signal (c) as internal reference signals whose phases are locked thereto, and they are even used as a reference signal for a drum servo. The synchronism control part 1 switches the acquisition mode from a frame mode to a track rise mode in an error generating process and resets the track number to zero, when the acquisition of the track synchronizing signal (c) is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital video tape recorder, and more particularly to a digital video tape recorder.

[0002]

2. Description of the Related Art In recent years, consumer digital video tape recorders have become widespread, and cassette-type digital video cassette recorders have been born. By the way, in the conventional method, according to the digital I / F format,
The frame frequency of the digital signal processing system is set to a reference value (NT
In the case of SC system, it can be operated only within the range of ± 1%, so the PLL (Phase Lock) of the frame synchronization signal
In the case of pulling in only with ed Loop), the worst case took about 1.5 seconds. In order to prevent this long pull-in time, there has been a method of temporarily resetting the internal frame reference signal. However, in this case, since the reference signal of the drum servo becomes discontinuous at the time of resetting, the rotation of the drum ( If this is done during the REC pause, for example, the worst case takes less than one second to follow the drum servo, and normal recording cannot be performed until this time is over, so the recording signal is substantially pulled in. Time was not improving.

[0003]

As described above, in a conventional digital video tape recorder, when internal synchronization with an input signal is disrupted, it takes a time in seconds to resynchronize.

The present invention solves this problem, and when the synchronization of the input signal is disrupted during the rotation of the drum, the internal synchronization is rapidly introduced into the input signal by a relatively simple method.
It is an object of the present invention to realize a digital video tape recorder capable of solving a failure due to synchronization failure in a short time.

[0005]

In order to achieve the above object, the present invention provides a rotary head, a digital signal processing means for adjusting recording timing by the rotary head and encoding input video data, and A synchronizing means for synchronizing the frame synchronizing signal of the signal processing means and the input synchronizing signal of the input video data, wherein n pieces of image data of one frame are n times (n> 1) by scanning the rotating head In a digital video tape recorder formed as a track on a magnetic recording medium, the synchronizing means causes a pull-in of a track synchronizing signal with respect to the input synchronizing signal, and resets a track number when the pull-in is fixed. , And synchronizing the frame synchronization signal with the input synchronization signal.

In the digital video tape recorder, the synchronization means always monitors which track the frame synchronization signal is on, and immediately resets the frame synchronization signal if the frame synchronization signal is not in the pull-in range before or after the track to be pulled-in. Thereafter, the frame synchronization signal is synchronized with the input synchronization signal by causing a track synchronization signal to be pulled into the input synchronization signal.

Further, in this digital video tape recorder, the synchronizing means causes a pull-in of a frame synchronizing signal with respect to the input synchronizing signal, and thereafter resets a track number when an arbitrary track synchronizing signal is approached. Thus, the frame synchronization signal is synchronized with the input synchronization signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital video tape recorder (hereinafter, referred to as DVTR) according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the present invention, a case of an NTSC DVTR with a drum rotation frequency of 150 Hz will be described as an example.

FIG. 1 is a block diagram showing the configuration of the present DVTR, FIG. 2 shows a tape recording pattern of the DVTR, and FIG. 3 shows the head configuration of the drum of the DVTR. FIG. 4 shows the relationship between the signals of the respective units. 1, 1 is a synchronization control unit,
2 is a digital signal processing circuit, 3 is a drum control unit, 4 is an A / D unit, 5 is a waveform shaping circuit, 6 is a recording amplifier, 7 is a drum, and 8 is a head driver.

As can be seen from FIG. 3, in this DVTR, scanning is sequentially performed by the opposing heads E and O, and two tracks are written per rotation of the drum. Since one frame is formed by ten tracks, one frame on the tape corresponds to five rotations of the drum. Therefore, the relationship between the frame reference signal (b) of the signal processing system and the reference signal of the drum servo, that is, the drum synchronization signal (d) is as shown in FIG.

First, the signal flow will be described with reference to FIG.
The input video signal is converted into a digital signal by an A / D unit 4, passes through a digital signal processing unit 2, passes through a recording amplifier 6, and is recorded on a magnetic tape as a recording medium by a head attached to a drum 7. On the other hand, after the synchronization signal passes through the waveform shaping circuit 5, it is supplied to the synchronization control unit 1 and the digital signal processing unit 2.

The synchronization control unit 1 uses the input synchronization signal (a) as a reference to generate a PLL (Phase Locked L).
oop) control, and outputs a frame synchronization signal (b) and a track synchronization signal (c), which are internal reference signals locked in phase with the control. The track synchronization signal (c) is used as a reference pulse for digital signal processing, and is also used as a reference signal for drum servo as described above. The drum controller 3 compares the servo reference with the rotation detection pulse (e) of the drum 7 to perform drum servo, and drives the drum driver 8 with the drive pulse (f).

By the way, the digital signal processor 2
There are different types of memories (memory A21, memory B22).
Memory A is written with the input synchronization signal (a) and read with the internal frame reference signal (b). The memory B is read by the drum synchronization signal (d) after being written by the internal frame reference signal (b). Therefore, if the phase relationship between the respective synchronization reference signals deviates beyond a certain margin, overtaking occurs in the memory and video data is destroyed. Such a situation is expected to occur at the time of mode transition or line input, but it is naturally necessary to escape from such a state as soon as possible.

It is an object of the present invention to quickly restore synchronization when the internal synchronization with an external input signal is disturbed, as described above, and to minimize the failure state of the system.

First, a method of generating an internal synchronization signal according to the present invention will be described. FIG. 5 shows a block diagram of the internal synchronization signal generation circuit. This corresponds to the synchronization control unit 1 in FIG. This block can be realized by either analog or digital. However, digital is easier to realize, so the case of digital will be described here.

First, the operation when the track synchronization signal output is free-run will be described. The track pulse generator 13 outputs a pulse of the track synchronization signal (c) whose level changes to H / L at 300 × 1000/1001 (Hz). FIG. 6 shows the relationship between the synchronization signal and each process. As shown in FIG. 6, a track pulse (track synchronization signal c)
The processing is performed at the edge of, the time of the next edge,
And the level (H or L). Therefore, the time of each edge is determined when outputting the immediately preceding edge. This period is given by a counter clocked by the crystal oscillation. In this state, of course, the track pulse is not synchronized with the input synchronization signal (a).

Next, a case where PLL control is performed to synchronize with an input synchronization signal will be described. The input synchronization signal enters the phase comparator 11 as a reference. This is compared with the edge of the track synchronization signal (c) output from the track pulse generator 13 to calculate a phase difference, which is passed to the error generator 12.

FIG. 6 shows the relationship between the error generation processing and the synchronization signal. As actual processing, the rising edge time data (j) stored in the RAM in the track pulse generation processing
And the time data of the reference edge is obtained. The error generation unit 12 performs an integration operation for absorbing a frequency shift of the reference signal from the standard NTSC signal and a limiter process for defining upper and lower limits of the frequency to generate an error value. The generated error value is sent to the track pulse generating unit 13 and added to the fixed track period (300 × 1000/1001 Hz), so that the phase difference between the output track synchronization signal and the reference is eliminated. The frequency of the pulse is moved to synchronize the input synchronization signal with the track synchronization signal (c).

The error pattern when the track synchronization signal is fixed and the phase of the reference signal is changed is shown in FIG.
(K). In the case of FIG. There is a lock point at the rising edge of track 0, where the error just becomes zero.

If the track synchronization signal is generated in such a manner as to be locked to the input synchronization signal, the frame synchronization signal is naturally determined by numbering (numbering) the tracks. That is, the track N in FIG.
o. No. is assigned to the track by the generation unit 14. No.
The rising edge of track 0 corresponds to the rising edge of the frame synchronization signal (b).

The above is the operation of the synchronization control unit 1 at the normal time. Next, the operation at the time of high-speed pull-in, which is the gist of the present invention, will be described. FIG. 8 shows a control timing relationship in the high-speed pull-in mode. When entering the high-speed pull-in mode, a high-speed pull-in start trigger is set by, for example, a microcomputer that controls the mode. When this flag is set, the pull-in mode is switched from 30 Hz (frame) to 150 Hz (track rising) during the error generation processing.
As an actual process, the limiter is released so that an error pattern as shown in FIG. By doing so, the pull-in point is normally only at the rising edge of the track 0, but all five rising edges are the pull-in points.

In the case of FIG. Since the rising edge of the six tracks is the nearest pull-in point, the pull-in operation is performed so that the edge of the input synchronization (REF) signal (a) comes here. As can be seen from FIG. 0
Since the phase difference is much smaller than that of pulling in the track, the pulling operation is completed quickly.

On the other hand, input synchronization (R
EF) The phase difference between the signal (a) and the rising edge of the track pulse (h) is monitored, and when this becomes smaller than a certain level, a reset enable flag is set. When both this flag and the high-speed pull-in start trigger are raised, the track No. in the track pulse generation processing is set. Generator 14
With the reset enable (p), the track No. Reset. By doing so, from the next frame, the edge of the input synchronization (REF) signal (a) and the track No. The rising edge of 0 (ie, the beginning of the frame) will be locked.

FIGS. 9 and 10 show that two types of numbering reset patterns are generated depending on the context of the two processes. That is, if the track pulse generation processing of the edge to be pulled in comes after the error generation processing, the next track is reset to 0 as shown in FIG. 9, and if not, the next track is set to 1 as shown in FIG. Set to. High-speed attraction is realized by performing processing in the above-described procedure.

While the invention of claim 1 of the present invention has been described above, the inventions of claims 2 and 3 will also be briefly described. FIG. 11 shows the processing timing of the method of claim 2. When the high-speed pull-in start trigger is raised, the reset enable flag (p) is raised in the error generation processing that comes first. When this flag is set, the track number is generated in the next track pulse generation processing. Reset. In the error generation processing, the reset enable flag (p) is set, and the pull-in mode is switched to 150 Hz. When the phase difference from the input synchronization (REF) signal (a) is reduced to a certain level or less (where the lock flag (s) is raised in FIG. 11), the mode is returned to 30 Hz, and the processing is terminated.

The processing of the second aspect is different from that of the first aspect. 1) The reset start condition is information (reset enable) indicating that the pull-in to the rising edge has been completed to some extent in the first aspect. However, in the second aspect, a high-speed pull-in start trigger is raised and a reset instruction is issued immediately in the first error generation processing to perform a reset operation. 2) The return from the 150 Hz pull-in to the 30 Hz pull-in is at the end of reset in claim 1, but is at the end of pull-in (when the lock flag is set) in claim 2. It becomes two points.

[0027] Claim 3 is based on claim 1 and has a frequency of 150 Hz.
The only difference is that the pull-in is continued at 30 Hz, and the track number is reset when approaching an arbitrary track synchronization signal.
Other processes are the same as those of the first aspect. The processing is facilitated by the amount that the switching of the pull-in is not performed.

By performing the above, when the synchronization of the input signal is disturbed while the drum is rotating,
For example, when the synchronizing signal on the playback device is disturbed during variable-speed playback while waiting for dubbing, or when the line input signal is disturbed due to channel switching or variable-speed playback on the partner tuner during recording standby, etc. By promptly pulling the internal synchronization into the external synchronization signal, it is possible to start recording quickly. By setting this mode to a line input in which the synchronization signal is often disturbed, even if the synchronization of the input signal is disturbed during recording, the failure can be relieved in a short time.

[0029]

As described above, according to the first aspect of the present invention, there is provided a rotary head, digital signal processing means for adjusting recording timing by the rotary head and encoding input video data, and A synchronizing means for synchronizing the frame synchronizing signal of the signal processing means with the input synchronizing signal of the input video data; In a digital video tape recorder formed as a track on a magnetic recording medium, the synchronizing means causes the input synchronizing signal to be pulled in by a track synchronizing signal, and resets the track number when the pulling in is fixed, thereby achieving frame synchronizing. The signal is synchronized with an input synchronization signal. Thus, a digital video tape recorder that can synchronize the frame synchronization signal with the input synchronization signal in about one-fifth of the pull-in time as compared with the conventional method, and can solve the failure due to the synchronization failure in a short time. Can be realized.

In this digital video tape recorder, the synchronizing means always monitors which track the frame synchronizing signal is on, and immediately resets the frame synchronizing signal if the frame synchronizing signal is not in the pull-in range before or after the track to be pulled-in. A frame synchronization signal is synchronized with the input synchronization signal by causing a track synchronization signal to be pulled into the input synchronization signal. As a result, the frame synchronization signal can be synchronized with the input synchronization signal in a pull-in time which is about 1/5 of the conventional method, and the failure due to the synchronization disturbance can be solved in a short time as in the case of the first aspect. And a digital video tape recorder capable of performing such operations. Particularly for a line input in which the synchronization signal is often disturbed, the synchronization is constantly monitored, which is more effective.

Further, in this digital video tape recorder, the synchronizing means causes a pull-in of a frame synchronizing signal to the input synchronizing signal, and thereafter, resets a track number when approaching an arbitrary track synchronizing signal. Thus, the frame synchronization signal is synchronized with the input synchronization signal. As a result, the frame synchronization signal can be synchronized with the input synchronization signal in about one-fifth of the pull-in time as compared with the conventional method, and since there is no need to switch the pull-in clock of the PLL, the synchronization is disturbed by simpler processing. Can be resolved in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital video tape recorder in which the present invention is implemented.

FIG. 2 is an explanatory diagram showing a tape recording pattern of the digital video tape recorder of FIG.

FIG. 3 is a diagram showing a configuration of a head of the digital video tape recorder of FIG. 1;

FIG. 4 is a diagram showing a relationship between signals of respective parts of the digital video tape recorder of FIG. 1;

FIG. 5 is a block diagram of an internal synchronization signal generation circuit of each section of the digital video tape recorder of FIG. 1;

FIG. 6 is a diagram showing a relationship between a synchronization signal and each processing in one embodiment of the digital video tape recorder of the present invention.

FIG. 7 is a diagram showing a relationship between a synchronization signal and an error signal in the embodiment of FIG.

FIG. 8 is a diagram illustrating a relationship between processing timings in a high-speed pull-in mode according to the embodiment of FIG. 6;

FIG. 9 is a diagram showing a timing of a reset process in the embodiment of FIG. 6;

FIG. 10 is a diagram showing a timing of a reset process in the embodiment of FIG. 6;

FIG. 11 is a diagram illustrating a relationship between processing timings in a high-speed pull-in mode according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Synchronization control part, 2 ... Digital signal processing circuit, 3 ... Drum control part, 4 ... A / D part, 5 ... Waveform shaping circuit, 6 ... Recording amplifier, 7 ... Drum, 8 ... Head driver.

Claims (3)

[Claims] 1. A rotary head, digital signal processing means for adjusting recording timing by the rotary head and encoding input video data, and a frame synchronization signal of the digital signal processing means and input synchronization of the input video data. A digital video tape recorder, comprising: synchronizing means for synchronizing with a signal, wherein one frame of image data is formed as n tracks on a magnetic recording medium by n (n> 1) scans of the rotating head. The synchronizing means synchronizes the frame synchronizing signal with the input synchronizing signal by causing a pull-in of a track synchronizing signal with respect to the input synchronizing signal, and resetting a track number when the synchronizing is fixed. A digital video tape recorder characterized by the above-mentioned. 2. A rotary head, digital signal processing means for adjusting recording timing by the rotary head and encoding input video data, and a frame synchronization signal of the digital signal processing means and input synchronization of the input video data. A digital video tape recorder, comprising: synchronizing means for synchronizing with a signal, wherein one frame of image data is formed as n tracks on a magnetic recording medium by n (n> 1) scans of the rotating head. The synchronization means always monitors which track the frame synchronization signal is on, and immediately resets the frame synchronization signal if it is not in the pull-in range before and after the track to be pulled-in. By causing the signal to be pulled in, the frame synchronization signal is matched with the input synchronization signal. Digital video tape recorders, characterized in that to synchronize Te. 3. A rotary head, digital signal processing means for adjusting recording timing by the rotary head and encoding input video data, and a frame synchronization signal of the digital signal processing means and input synchronization of the input video data. A digital video tape recorder, comprising: synchronizing means for synchronizing with a signal, wherein one frame of image data is formed as n tracks on a magnetic recording medium by n (n> 1) scans of the rotating head. The synchronizing means causes the input synchronizing signal to be pulled in by a frame synchronizing signal, and then resets a track number when the input synchronizing signal is near an arbitrary track synchronizing signal, thereby synchronizing the frame synchronizing signal with the input synchronizing signal. A digital video tape recorder characterized by synchronizing with a signal.