JPS60114092A - Signal processing device - Google Patents

Abstract

PURPOSE:To perform always stable reload of a signal by demodulating signals reproduced from a reproducing head at each signal reproducing system provided corresponding to the reproducing head, stably reproducing synchronizing signals and clock signals, giving these signals to a time axis correction device after selecting the signals for each signal reproduction system and without depending on the phase gap at head changeover point. CONSTITUTION:Selection control of signal reproduction systems 17a and 17b by a control circuit 25 is conducted based on tachometer signals generated, for example, by cylinder rotation which rotates and drives the above-mentioned heads 15a and 15b and based on horizontal synchronizing signals obtained from reproduced signals, and by setting its changeover timing, by which the signals are reproduced through two magnetic heads 15a and 15b, combined by connecting the independently processed signals as continuous signals through a selector circuit 24, supplied to a time axis correction device 26, and outputted after being time/corrected based on the synchronizing and clock signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a signal processing device that can easily and effectively perform time axis correction of a reproduced signal in a segmented scan type VTR.

[Technical background of the invention and its problems]

When magnetically recording a video signal consisting of a wide frequency band component, conventionally, the rotary head temperature VTR' ((using the above-mentioned video fl! For example, as schematically shown in FIG. The video signal is recorded while forming a signal track obliquely in the width direction of the magnetic tape 2 using the magnetic heads 3a and 3b which rotate at high speed. It is determined based on the frequency of the vertical synchronizing signal of the video signal. For example, in the case of a consumer 2-head helical type VTR using the NTSC system, the rotational speed of the cylinder 10 is determined to be 29.97 revolutions/second, and the frequency is 59.97Hz
The two heads 3h and 3b are synchronized with the vertical synchronization signal.
The video signals are recorded one field at a time by switching alternately.

However, recently, attempts have been made to record and reproduce wider band video signals with even higher quality, and as a result, it has become necessary to further increase the relative speed. The relative speed of the lever is, therefore, horizontally proportional to the diameter of the rotary cylinder 1 and its rotational speed. However, if the diameter of the rotating cylinder is increased, the moment of inertia increases accordingly, and there are mechanical problems such as an increase in the size of the device. Therefore, the rotational speed of the rotary cylinder 1 is increased exclusively.

By the way, when the rotational speed of the rotary cylinder 1 (magnetic heads Ja, Jb) is increased in this way, video No. 48 is divided into one field at a time as described above, and the magnetic heads 3a and Jb are switched to generate a signal. It becomes impossible to record.

In other words, it is necessary to further divide the video signal of the L field portion in time and record the signal while switching between the magnetic heads 3m and 3bk''Z.In this way, the signal recording performed is as follows. This method is called a segmented scan method, and is distinguished from the method described above in which heads are switched for each field.

According to this segmented scan method, video signals for one field are temporally divided and recorded on a plurality of tracks by switching heads. At this time, in order to ensure continuity of the signal at the time of normal head switching, the same signal is simultaneously recorded by the two magnetic heads 3&, 3b during a predetermined time width of the upper bC head switching. When reproducing the signal, two magnetic heads Ja are used as shown in FIG.

By switching the signals lN-1 and lN-2 individually reproduced by 3b at their overlapping portions, continuous signals are produced.

In this way, it is theoretically possible to smoothly connect the signals recorded in temporal divisions.

However, in reality, due to changes in tape tension, tape expansion and contraction, tape vibration, changes in contact pressure between the tape and the head, etc., the head switching timing during signal recording and the head switching timing during signal reproduction may differ. There is almost no perfect match. For this reason, for example, as shown in Figure 3, which shows the phase relationship of horizontal synchronization signals, there is a shift in the phase of the signals reproduced by the two heads, resulting in a problem in which the h1 skew phenomenon occurs in the reproduced video. Ta. Incidentally, although this type of misalignment also occurred in the non-segmented scan method described above, it did not pose a problem because the head switching time was during the vertical retrace period.

Although the skew Q 14 can be removed using a time base corrector such as a digital time base corrector, the discontinuity in the signal waveform due to the phase shift at the time of switching the heads cannot be removed. This brings about the following major problems for VTRs.

Jail, the video signal is 5
rJIJ (Since it is recorded as No. ij, the phase shift at the time of switching the head appears as a large switching noise. Also, when performing time base correction in this type of segmented VTR, the horizontal synchronization signal Since the phase information of the video signal for a period is given, it is necessary to switch the head on the front porch side.However, because the head is switched on the front porch side, which is short in time, this causes a large noise. When this occurs, the synchronization separator provided in the signal adjuster and time base corrector is seriously affected, resulting in the problem that the reproduction operation of the VTR becomes unstable.

Further, the large phase change that occurs at the time of head switching has a large impact on the separation of the synchronization signal from the reproduced signal and the reproduction of the clock signal. For this synchronization signal separation and clock signal regeneration, a phase-locked loop circuit with a flywheel effect is usually used to absorb the slow phase fluctuations of the reproduced signal, and this circuit also has four This is done by giving it a sensory characteristic. However, since the above-mentioned phase-locked loop circuit essentially does not follow a sudden change in the input signal, it is difficult to obtain a clock signal that correctly represents the phase of the reproduced signal within the period consisting of the switching point of the head. For this reason, using such a lock signal does not allow the above-mentioned time base correction to be performed correctly.

For the above reasons, the instability of synchronization separation caused by head switching performed on the front porch side of the horizontal synchronization signal, and the inability to effectively utilize the phase-locked loop circuit, ultimately make it difficult to stabilize the time base correction. It was also difficult to do so.

In order to solve this KfAk problem, conventionally it has been considered to prepare an independent signal reproduction system for each reproduction head, but the ff1ti6!4 system has become large-scale, and it also requires expensive and costly time axis correction. Requires a large number of containers, etc.
There was a problem with practicality.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to improve segmented scan mV.
It is an object of the present invention to provide a highly practical signal processing device that can easily and effectively correct the time axis of a reproduced signal in a TR without being affected by phase shifts in head switching time.

[Summary of the invention]

The present invention provides a signal processing device in which a signal recorded in a temporally divided manner by a plurality of recording heads is sequentially reproduced by a reproduction head corresponding to the recording head to restore the original signal. It consists of a post-modulator that demodulates the reproduced signal, and a synchronization signal separator and a clock signal regenerator that extract the interleaved signal and the clock signal from the reproduced signal. The I+ times signal synchronization signal and the clock signal obtained by these square raw silks are selected for each of the signal reproduction systems in synchronization with the reproduction switching timing of the reproduction head, and this is applied to the time axis. This is applied to a corrector to correct the time axis and output it.

〔Effect of the invention〕

Thus, according to the present invention, in contrast to the playback head (No.
These after reproducing each issue stably? Since it is selected for each signal reproduction system and applied to the time axis corrector, the time axis correction can be performed stably and effectively. Moreover, the stable signal obtained by each signal reproduction system is selected for each reproduction system and time axis correction is performed in common by one time axis corrector, so the configuration is simple and highly practical. . Then, the tremendous effect of always being able to restore a stable signal without being affected by the phase shift at the time of head switching is diminished.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic diagram of the main parts of the apparatus according to the embodiment, and shows an example in which the apparatus is applied to a two-head segmented VTR. The video signal to be recorded is transmitted through a modulator 1, for example to an FM signal.
After being modulated by υM, it is given to two recording amplifiers 12m and 12b and amplified to the level (i and bell) necessary for recording.Then, the amplified distribution signal (FM antiharmonic wave) is Magnetic head 13rs, 1 driven to rotate at high speed
3b, and are alternately recorded on the magnetic tape 14 while drawing a predetermined locus. These magnetic heads 13h, 13
It goes without saying that the alternating recording of signals by B is performed by simultaneously recording the same signals in an overlapping manner at the time of head switching as described above.

On the other hand, the signals recorded on the magnetic tape 14 in this manner are transmitted to a reproducing magnetic head 15a having the same relationship as the magnetic heads 13a and 1.3b.

15b. In addition, this recording head and P)
It is also possible to use a common head for cattle, and use the same head by switching it depending on the recording mode and the reproduction mode. Therefore, these magnetic heads 15a'', 15
The signal reproduced via the bf is transmitted to the reproduction bottle width devices 16a, 16.
After being transmitted through the bf to a signal level necessary for signal processing, the signals are sent to signal reproduction systems 17a and 17b provided corresponding to the respective magnetic heads 15a and 15b, respectively.

Each of these signal reproduction systems 17a.

17b inputs the reproduced modulated color signal wave that has been equalized and corrected by the miJ reproduction amplifiers 16a and 16b, and
a demodulator 18 that obtains a video signal from it, 4 t, a synchronization signal separation circuit 19 that separates and extracts a synchronization signal from the video signal demodulated by this post-modulator 18, and a synchronization signal separation circuit 19 that separates and extracts a synchronization signal from the video signal demodulated by this post-modulator 18; It is constituted by a clock signal regeneration circuit 20 that regenerates the clock signal of the inter-instrument signal from the clock signal.

Such signal reproducing systems 17a and 17b independently reproduce each signal reproduced by the magnetic heads 15a and 15b. Sub-picture signals, synchronization signals, and clock signals are included.

Selector circuit 241-1 consisting of an image 1ζ signal selector 21, a synchronization signal selector 22, and a clock signal selector 23
．． , under the control of the selector control circuit 25, the demodulator 11 (selects the i signal, the synchronization signal, and the clock signal for each yJIJ signal re-signal regeneration system 17ab, and performs time-coaxial correction on each of the selected signals; It is given to 26 people.

A signal reproducing system 17a based on the control circuit 25.

The selection control of the magnetic head 17b is, for example, the magnetic head 15a,
The switching timing is set based on the tachometer fi generated by the rotation of the cylinder that rotationally drives 15b and the horizontal synchronization signal obtained from the reproduction signal. As a result, the two magnetic heads 15a,
The respective signals that have been reproduced through the respective signals 15b and subjected to independent signal processing are connected as a continuous signal through the selector circuit 24, and then provided to the time axis corrector 26. The time axis corrector 26 corrects the time axis of the rear video signal based on the synchronization signal and the clock signal, and then outputs the signal.

According to the device configured in this way, the following effects that cannot be expected from conventional devices can be achieved. That is, since the reproduction signal switching process is performed on the demodulated signal, the occurrence of switching noise can be reduced to a negligible level.

In other words, if the switching process is performed at the stage of a quiet signal, the discontinuous waveform caused by the phase shift of the modulated wave will appear as large noise due to its demodulation. Additionally, when the switching point is set to the front porch, the noise occurs near the leading edge of the horizontal synchronizing signal, which tends to cause malfunctions in signal processing. By performing the switching process, the phase shift of the demodulated signal does not become noise, so that the above-mentioned conventional problems are not caused. In addition, since synchronization signal separation is performed before switching processing is performed, the synchronization signal and clock signal can be extracted stably, and time axis correction can be performed inexpensively using these stable synchronization signals and clock signals. It can be carried out.

Since the clock signal is regenerated before the switching process, a phase-locked loop having a flywheel effect can be used for this clock signal regeneration process, and the effect of easily stabilizing the operation is lost. .

As shown in FIG. 5, the operation of each signal reproduction system is made more stable during the overlap period of each signal reproduction system, and then the reproduction signal is switched to perform time axis correction. The above time axis correction can be performed stably. In other words, only the stable reproduction number 48 indicated by the arrow h in FIG. Since time axis correction is performed on the video signal below, the effect is tremendous.

Note that the present invention is not limited to the embodiments described above. For example, signal recording using segmented scanning.
The number of magnetic heads used for reproduction may be three or more. Further, the number of time divisions of the signal, for example, the number of divisions of the video signal for 1 fields defined by the vertical synchronization signal, may be determined according to the specifications. In short, the present invention can be practiced with various hairstyles without departing from the gist thereof.

[Brief explanation of drawings]

Fig. 1 is a diagram schematically showing the basic configuration of a rotary head type VTR, Fig. 2 is a diagram showing the processing form of a reproduced signal, Fig. 3 is a diagram showing a phase shift, and Fig. 4 is an embodiment of the present invention. FIG. 5 is a schematic diagram of the example apparatus, and FIG. 5 is a diagram for explaining signal processing of the example can manufacturing 4. 14...Magnetic tape, 151I, 15b...Magnetic head, 17a, 17b...Signal reproduction system, 18...Post-adjuster, 19...Sync signal separator, 20...Clock signal reproduction 24... Selector circuit, 25... Selector control circuit, 26... Time axis corrector.

Claims (2)

[Claims] (1) A signal written on a recording medium in a temporally divided manner using a plurality of recording heads is sequentially reproduced by a reproduction head corresponding to the recording head to restore the signal recorded on the recording medium. In the signal processing device, a signal processing device is provided corresponding to each of the plurality of playback heads, and detects a synchronization signal from the demodulated signal, and a signal processing device that detects the signal reproduced from the recording medium by each of the playback heads. A plurality of signal reproduction systems consisting of a synchronization signal separator that extracts the synchronization signal and a clock signal regenerator that regenerates the clock signal from the extracted synchronization signal, and demodulated signals, synchronization signals, and clock signals output from these signal reproduction systems, respectively. a selector that selects each of the signal reproduction systems in synchronization with the reproduction switching timing of the 1σ reproduction head; and a time axis correction of the demodulated signal, synchronization signal, and clock signal from the signal reproduction system selected through this selector. What is claimed is: 1. A signal processing device comprising: a time axis corrector for outputting a signal. (2) Signals that are recorded in a temporally divided manner on a recording body using a plurality of recording heads are the same signals that are simultaneously recorded by overlapping the switching timings of the recording heads. The signal processing device according to item 1.