JPS62171296A - Magnetic recording method - Google Patents

Abstract

PURPOSE:To improve the resolution of a recording picture by applying time base compression to a chrominance signal in an 8-mm VTR, recording the signal to a PCM audio recording area on a magnetic tape, expanding the lower side band of a luminance signal and recording the signal on a video signal recording area on the magnetic tape. CONSTITUTION:In recording a static picture or moving picture with high resolution, changeover switches 6, 11, 7 are turned respectively to the position of contacts a1, a2, a3. The chrominance signal Sc is subjected to nearly 1/5 time base compression by an A/D converter 16, a time axis compression circuit 17 and a D/A converter 18, after a reference signal is superimposed by a mixer 19, the result is FM-modulated by a modulator 20 and recorded on a pulse code modulation audio recording area Sp by a recording head 22 via a synthesizer 14 and a recording amplifier 21. A luminance signal SY is stored in a frame memory 8 for a prescribed time, a reference signal is added by the mixer 9, FM-modulated by the modulator 10 and transmitted through a band pass filter II-13 whose lower band is expanded sufficiently in comparison with the band pass filter I 12 and recorded on a video signal recording area SY by the recording head 22 via the synthesizer 14 and the recording amplifier 21.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Technical Field The present invention relates to a magnetic recording method, and particularly to a method capable of increasing the resolution of images.

b. Prior art and its problems Attempts have been made to record and reproduce still images using a helical scanning magnetic recording and reproducing device (hereinafter referred to as rVTRJ) for the purpose of recording and reproducing moving images. There are two main types:

l) Using a frame memory, etc., record the same signal for several frames or seconds under normal tape running conditions, and then playback with the tape stopped, or read the signal while the tape is running normally and store it in memory once. How to stop and play the tape after doing so.

ii) A method in which one frame is recorded while the tape is stopped, and playback is also performed while the tape is stopped. However, frame recording
For reproduction, a head with a step of one track pitch is required.

By the way, in the case of frame recording, a maximum of about 200,000 frames of still images can be recorded on a two-hour tape, and moving images and still images can be recorded in a mixed state.

For this reason, it is extremely difficult to efficiently search for a desired still image from a recorded tape.

In the case of videos, even if the amount of information per frame is small,
Sufficient image quality can be obtained by interpolating missing information between the previous and subsequent frames.

However, since the amount of information in still images is limited to one frame, there is a problem in that satisfactory image quality cannot be obtained under the same conditions as for moving images.

C2 Purpose This invention was made in view of the above background, and aims at improving at least the resolution of still images.

Therefore, in the present invention, in an 8 mm VTR that uses an 8 mm wide magnetic tape as a recording medium, the color signal is compressed on the time axis to perform pulse code modulation (PCM) on the 8 mm wide magnetic tape.
At the same time, the lower side wave band of the luminance signal is expanded and recorded in the video signal recording area of the 8 mm wide magnetic tape, thereby achieving the above object.

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

FIG. 1 is a block diagram showing an example of a recording circuit in an 8 mm VTR to which the present invention is applied.

In the figure, a composite color video signal (for example, NTSC signal) S
A luminance signal comb filter 4 is connected to the terminal 1 to which X is supplied.
and a color signal comb filter 5 are connected, and the output side of each of these filters 4 and 5 is connected to a changeover switch 6.7, respectively.
It is connected to the.

On the other hand, terminals 2 and 3 are directly connected to changeover switch 6.7, bypassing filters 4 and 5, respectively.

Contact a1 of changeover switch 6 is connected to modulator 10 via frame memory 8 and mixer 9, contact b□ is directly connected to modulator 10, and the output side of this modulator 10 is connected to changeover switch 6. The switch 11 connects it to the synthesizer 14 via a bandpass filter 112 on the contact b2 side or a bandpass filter l113 on the contact a2 side.

On the other hand, the contacts of the changeover switch 7 are connected to the frequency converter 15.
The contact a is connected to the synthesizer 14 through the A/D converter 169, the time axis compression circuit 17, and the D/A converter 18. Mixer 19. After passing through the modulator 20 and the modulator 20, the signal is connected to the combiner 14.

The synthesizer 14 is connected to a recording head 22 via a recording amplifier 21.

Next, FIG. 2 is a block diagram showing an example of a reproducing circuit.

The playback head 31 is connected to a changeover switch 33 via a playback amplifier 32.

Contact b4 of the changeover switch 33 is connected to the bypass filter I3.
4 and a low-pass filter 35, the output of each of these filters 34, 35 being connected via a demodulator 369 and a frequency converter 37 to a synthesizer 38, respectively.

Further, the contact a4 is connected to the bypass filter 40 or the demodulator 41 via the changeover switch 39, and the bypass filter lI40 connected to the contact b5 of the changeover switch 39 is connected to the time base collector 42 and the demodulator 41. It is connected to a combiner 38 via a combiner 36 .

The demodulator 41 connected to contact a of the changeover switch 39 is connected to the synthesizer 38 via an A/D converter 4/9 adjustment circuit (time base collector) 47.

Note that a memory 45 is connected to the 1-time axis expansion circuit 44.

e. Effect of the embodiment First, the operation of the recording circuit shown in FIG. 1 will be explained.

The composite color image signal sr is supplied to the terminal 1 as described above, but when the luminance signal Sv and the color signal SO are supplied separately as in the output of a television camera, the composite color image signal sr is supplied to the terminal 2. NJf1 signals S and / are supplied as color signals to terminal 3, respectively.

When a composite color video signal ST is input, the luminance signal comb filter 4 and the chrominance signal comb filter '5 separate the signal into a luminance signal SV and a chrominance signal So, which are then supplied to a changeover switch 6 and a changeover switch 7, respectively. Ru.

When performing normal video recording based on the 8mm standard, selector switches 6 and 11.7 are contacted, respectively. ,b,,b
, switch to the side.

The luminance signal SY is subjected to FM modulation by a modulator 1o via a changeover switch 6, and then supplied to a bandpass filter 112 via a changeover switch 11.

On the other hand, the color signal SO is supplied to the frequency converter 15 via the changeover switch 7 and subjected to low frequency conversion, and then superimposed on the luminance signal passed through the bandpass filter 112 by the synthesizer 14.

Then, this superimposed signal is amplified by the recording amplifier 21.
After being recorded, the recording head 22 records on an 8 mm width magnetic tape 23.

On the other hand, when recording high-resolution still images or moving images, the changeover switches 6, 11, and 7 are respectively switched to the contact at+821aff side.

The color signal So is sent to the A/D converter 1 via the changeover switch 7.
6 and is A/D converted, the time axis compression circuit 1
7, the time axis is compressed to approximately 115, and the signal is converted into an analog signal by the D/A converter 18.

Then, this analog signal is superimposed with a reference signal by a mixer 19, and then subjected to FM modulation by a modulator 20.

This FM-modulated color signal is then amplified by a recording amplifier 21 via a synthesizer 14, and then sent to a recording head 22.
The pulse code modulation audio recording area shown in Figure 3 (
PCM audio recording area) is recorded in SP.

On the other hand, the luminance signal SV is supplied to the frame memory 8 via the changeover switch 6 and held for a predetermined time, after which a reference signal is added by the mixer 9 and FM modulated by the modulator 10.

The FM-modulated luminance signal is then passed through a bandpass filter [13] whose lower band is sufficiently expanded compared to the bandpass filter 112 via a changeover switch 11, and then passed through a synthesizer 14 to a recording amplifier. 21, and recorded by the recording head 22 in the video signal recording area Sv shown in FIG.

Next, to explain the operation of the reproduction circuit shown in FIG. 2, the signal reproduced from the 8 mm wide magnetic tape 30 by the reproduction head 31 is amplified by the reproduction amplifier 32 and then supplied to the changeover switch 33. .

First, when reproducing a recorded signal based on the 8 mm VTR standard, the selector switch 33 is switched to the contact b4 side.

The reproduced signal is first supplied to a bypass filter 134 and a low-pass filter 35, where it is separated into a luminance signal and a color signal.

The luminance signal is demodulated by a demodulator 36, and the color signal is inversely converted (high frequency conversion) by a frequency converter 37, and then reproduced into a composite color video signal by a synthesizer 38.

On the other hand, when reproducing a signal recorded with high image quality, the selector switch 33 is switched to the contact a4 side. In this case, the color signal is first reproduced from the tape 30 by the reproduction head 31, amplified [1] by the re-amplifier 32, and supplied to the changeover switch 39 via the changeover switch 33. At this time,
Since the changeover switch 39 has been switched to the contact a5 side, this color signal is demodulated by the demodulator 41.

Next, the demodulated color signal is digitized by an A/D converter 43, then time-axis expanded, and the color signal for one field is temporarily held in the memory 45, and then D/A converted. vessel 46
is converted to an analog signal.

On the other hand, following the reproduction of the color signal, the luminance signal is reproduced.
The signal is reproduced from the tape 30 and supplied to the changeover switch 39 via the playback amplifier 32 and changeover switch 33. At this time, the changeover switch 39 is not switched to the contact position, so this luminance signal is limited to a predetermined band by the bypass filter [40, and the time axis is adjusted by the next stage time axis adjustment circuit 42. After being corrected, it is demodulated by a demodulator 36 and supplied to a combiner 38 .

The color signal converted into an analog signal by the above-mentioned D/A converter 46 is also time-base corrected by the time-base adjustment circuit 47, and this color signal is sent to the demodulator 3 by the synthesizer 38.
6, thereby synthesizing a composite color video signal.

As shown in FIG. 3, one frame of image is recorded on the A track 50A and B track 50B on the tape, and each track 50A, 50B has approximately 3
0″ section a = b PCM audio area SP and 1
It is formed from video signal recording areas Sv in sections b to C of 80°.

According to the above embodiment, at least when still image recording is performed, by compressing the time axis of one color signal and recording it in the PCM recording area SP, the lower side wave band of the luminance signal is adjusted to about 1.5 MHz, for example. It becomes possible to enlarge the image, and the resolution can theoretically be improved by about 120 lines.

Further, when recording a moving image, the 8 mm VTR standard is satisfied, but high resolution can be obtained by the above method if necessary.

f. Effects As described above, according to the present invention, in an 8 mm VTR using an 8 mm wide magnetic tape as a recording medium, one color signal is compressed in the time axis to create a PCM audio recording area on the 8 mm wide magnetic tape. At the same time, the lower sideband of the luminance signal is expanded and recorded in the video signal recording area of the 8 mm wide magnetic tape, so the resolution of the recorded image can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a recording circuit in an 8 mm VTR to which the present invention is applied. Fig. 2 is a block diagram showing an example of a reproducing circuit in an 8 mm VTR. Fig. 3 is a block diagram showing an example of a reproducing circuit in an 8 mm VTR. FIG. 3 is a track diagram showing a recording format on a tape. 1 to 3...Terminal 4...Luminance signal comb filter 5...
Color signal comb filter 6.7, 11, 33.39...Switch switch 8
...Frame memory 9.19...Mixer 10.20...Modulator 12...Band pass filter ■13...
・Band pass filter ■14.38...Synthesizer 15.37...Frequency converter 16.43...A/D converter 17...Time Axial compression circuit 18.46...D/A converter 21...Recording amplifier 22...Recording head 23.30...8mm width magnetic tape 31.・・・
... Reproduction head 32 ... Reproduction amplifier 34 ... Bypass filter I 35 ... Low pass filter 30.41 ... Demodulator 40 ...・Bypass filter■ 44...Time axis expansion circuit 45...Memory 42.47...Time axis adjustment circuit Patent applicant
Asahi Optical Industry Co., Ltd. Representative Toru Matsumoto

Claims (1)

[Claims] In an 8 mm magnetic recording/reproducing device using a 1.8 mm wide magnetic tape as a recording medium, a color signal is compressed in the time axis and recorded in a pulse code modulation audio recording area of the 8 mm wide magnetic tape, and a luminance signal is A magnetic recording method characterized in that the lower side wave band of the 8 mm wide magnetic tape is expanded and recorded in a video signal recording area of the 8 mm width magnetic tape.