JPH03117187A - Vtr - Google Patents

Abstract

PURPOSE:To obtain an always excellent reproduction signal by selecting a ratio of multiple of speed of high speed reproduction as an even number in the case of high speed reproduction and obtaining a reproduction signal at a field skip at the high speed reproduction in the mode where a track pitch is smaller than a head width. CONSTITUTION:The high speed reproduction of a tape recorded in the SP mode is implemented similarly as a conventional method. while in the high speed reproduction of a tape recorded in the LP mode, a switch 12 is switched to the position of an RF switch circuit 11. Thus, when the moving speed of the tape 1 is an even number of multiple-speed, the envelope of the RF signal is as shown in figure B with respect to the changeover of the field as shown in figure A and the picture by the video signal of each field is as shown in figure C. On the other hand, a write enable terminal WE of a field memory 5 receives a signal equal to a head switching signal as shown in figure D and a reproduction signal subject to so-called field skip is extracted from an output terminal 9 as shown in figure E.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a VTR having a plurality of modes with different tape transport speeds.

[Summary of the invention]

The present invention relates to a VTR, and when playing back a tape in a mode where the track pitch is smaller than the head width at high speed, by setting the speed ratio to an even number and performing field skipping using image memory, good playback with fewer noise bars can be achieved. This allows the signal to be obtained.

[Conventional technology]

In consumer VTRs, there are standard (SP) modes in which tapes are transferred at standard transport speeds for recording and playback, and long-distance (LP) modes in which tapes are transported at slower than standard transport speeds for recording and playback. In some cases, a mode is provided.

In VTRs with such multiple modes, S
In the P mode, the track pitch is made larger than the head width, and a non-recorded portion resembling a so-called guard band is formed between the tracks. In the LP mode, the track pitch is made smaller than the head width, so that so-called overlapping recording is performed. ing.

In that case, when a tape recorded with the above-mentioned SP motor is played back at high speed, the RF multiplied signal taken out from the head, for example, as shown in Figure 3, the upper and lower envelopes change into a triangular waveform due to the influence of the above-mentioned unrecorded part. When this signal is displayed on a receiver, a wide noise bar as shown by diagonal lines in FIG. 4 appears on the screen.

Therefore, in the past, the tape transport speed was specified as an odd number multiple speed.
The noise bars appear at the same position in odd and even fields to reduce damage to the screen caused by the noise bars.

Incidentally, devices have been considered in which a VTR includes, for example, a one-field image memory and performs various special reproductions.

Therefore, in such a device with a built-in image memory, it may be possible to perform screen interpolation to further reduce damage to the screen during high-speed playback.

That is, FIG. 5 shows a configuration for this purpose. In the figure,
RF extracted from tape (1) by rotating head (2)
The signal is supplied to a video circuit (4) through a double signal head amplifier (3), and the video signal is demodulated. This demodulated video signal is supplied to a field memory (5). On the other hand, the RF multiplied signal from the head amplifier (3) is supplied to the envelope detection circuit (6), and this detection signal is sent to the switch (7).
The signal is supplied to the write enable terminal (WE) of the field memory (5) through the input signal. The video signal formed in this field memory (5) is sent to the buffer amplifier (8).
The signal is output to the playback signal output terminal (9) through the playback signal output terminal (9). In addition(
10) is a microcomputer (μmC0M) for system control, and this computer (10)
A write enable signal in the normal mode is supplied to the switch (7), and switching of the switch (7) is controlled by a signal from the computer (10).

In this apparatus, when performing high-speed playback of a tape recorded in the SP mode, for example, the transport speed of the tape (1) is specified to be an even number multiple speed.

As a result, in this device, the RF multiplied signal envelope for field switching (head switching signal) as shown in FIG. As shown in Figures C and D, the RF
By rewriting only the portion of the doubled signal envelope above a predetermined level, a reproduced signal in which noise bar portions are interpolated in alternating fields is taken out at the output terminal (9) as shown in FIG.

In this way, it is possible to obtain a reproduced signal without damaging the screen due to noise bars.

[Problem to be solved by the invention]

However, when trying to play back a tape recorded in LP mode at high speed with the above-mentioned device, since overlapping recording is performed in LP mode, the RF multiplied signal envelope at this time becomes as shown on the right side of Figure 7. The range of fluctuation is extremely small compared to the envelope in SP mode shown on the left.

For this reason, even if the envelope detection level is adjusted as shown in the figure, the detection becomes extremely unstable and accurate detection cannot be performed. Therefore, for example, as shown in Figure 8A, noise bars may remain without interpolation, or as shown in Figure 8B, the interpolated range is too wide and both fields are not rewritten and the image does not move. parts arise,
As a result, the screen of the reproduced signal becomes extremely deteriorated.

Note that if no interpolation is performed at all, the noise bar will be twice its original size at even speeds. Furthermore, if an attempt is made to switch to even-numbered speeds in SP mode and to odd-numbered speeds in LP mode, control of counters and the like becomes complicated, and the burden on system control and servo systems increases significantly.

This application was made in view of these points, and is intended to provide a simple configuration that allows a good reproduced signal to be obtained even in high-speed reproduction in LP mode.

[Means to solve the problem]

The present invention has a first mode (SP mode) in which the track pitch is thicker than the head width, and a second mode (LP mode) in which the track pitch is smaller than the head width.
In TR, when performing high-speed reproduction, the speed ratio of this high-speed reproduction is an even number, and when in the first mode (switch (
12) ) is image memory (field memory (5))
The position of the noise using the envelope detection circuit (
6)) is alternately interpolated to form a reproduction signal, and the second mode switching switch (12)) uses the image memory to perform field skip (RF switch times i?8 (11)). This is a VTR characterized in that a reproduced signal is formed using the following signals.

[Effect]

According to this, in high-speed playback mode in which the track pitch is smaller than the head width, the playback signal is obtained by field skipping, so even if high-speed playback is performed at even multiple speeds, the noise bar does not increase, and the system A good reproduction signal can always be obtained without putting a burden on the control or servo system.

〔Example〕

In FIG. 1, a head switching signal corresponding to the rotational phase of a rotary head (2) is detected by an RF switch circuit (11). Further, the signal from the envelope detection circuit (6) is supplied to the switch (7) through the switch (12), and the signal from the RF switch circuit (11) is supplied to the switch (7) through the switch (12).
12). Furthermore, switching of the switch (12) is controlled by a signal from the computer (10).

The rest is the same as the conventional device described above.

Therefore, in this apparatus, high-speed playback of a tape recorded in the SP mode is performed in the same manner as in the prior art.

On the other hand, in high-speed playback of a tape recorded in the LP mode, the switch 12) is switched to the RF switch circuit (11) side.

As a result, in this device, when the transport speed of the tape (1) is an even multiple speed, the RF signal envelope for field switching (head switching signal) as shown in FIG. 2A is as shown in FIG. 2B. The image based on the video signal of each field is as shown in FIG. On the other hand, as shown in the figure, a signal equivalent to the head switching signal is supplied to the write enable terminal (W'E) of the field memory (4). , a so-called field skipped reproduction signal is taken out from the output terminal (9) as shown in FIG.

Therefore, according to this device, in high-speed playback mode in which the track pitch is smaller than the head width, the playback signal is obtained by field skipping, so even if high-speed playback is performed at an even multiple speed, the noise bar will not increase. , it is possible to always obtain a good reproduction signal without putting a burden on the system control or servo system.

Note that the noise bar in the LP mode is originally thin, and even if the noise bar of one field appears, there is little damage to the screen.

Further, high-speed reproduction in the above-mentioned apparatus is performed, for example, at 10 times the forward speed and at 8 times the reverse direction.

Furthermore, in the above-described apparatus, the head switching signal can also be generated by a microcomputer (10) for system control.

In addition, in the above device, the field memory (5) is written by RF.
By synchronizing the double signal and performing successive output using the reference synchronization signal, skew correction during interpolation can also be performed at the same time.

〔Effect of the invention〕

According to this invention, in high-speed playback in a mode where the track pitch is smaller than the head width, the playback signal is obtained by field skipping, so even if high-speed playback is performed at even or several times the speed, the noise bar will not increase. This makes it possible to always obtain a good reproduction signal without putting any burden on the system control or servo system.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an example of a VTR according to the present invention, Figure 2 is an explanatory diagram for explaining the operation when playing back a tape recorded in LP mode at high speed, and Figure 3 is recorded in SP mode. 4 is a line diagram showing an example of a screen during high-speed playback, FIG. 5 is a block diagram of an example of a conventional device, and FIG. An explanatory diagram for explaining the operation when a tape recorded in SP mode is played back at high speed. Figure 7 shows the difference in the RF signal envelope when playing back a tape recorded in SP mode and LP mode at high speed. FIG. 8 is a diagram showing an example of a screen when a tape recorded in LP mode is played back at high speed. (1) is tape, (2) is rotating head, (3) (8)
is an amplifier, (4) is a video circuit, (5) is a field memory, (6) is an envelope detection circuit, (7012) is a switch, (9) is an output terminal, (10) is a microcomputer, (11) is an RF It is a switch circuit. Agent Hide Matsukuma Moriroa q scold & η

Claims (1)

[Claims] In a VTR having a first mode in which the track pitch is larger than the head width and a second mode in which the track pitch is smaller than the head width, when performing high-speed playback, the speed ratio of this high-speed playback is In the first mode, the position of the noise bar is alternately interpolated using the image memory to form a playback signal, and in the second mode, the image memory is used to perform field skipping. A VTR characterized in that it forms a reproduction signal.