JPH07130144A - Vtr - Google Patents

Abstract

PURPOSE:To eliminate the deterioration of image quality and drop-out of the central part of reproduced images by operation of an erasing head at the time of after-recording. CONSTITUTION:Signals from heads 8A, 8b are supplied through a reproduction processing circuit 14 for video signals and a mask processing circuit 15 to a field memory 16. The erasing head 8E is operated by an erasing control signal from a computer 9 for control and is supplied by the mask control signal made wider in width than the erasing control signal to a mask signal generating circuit 20. Further, a writing control signal is supplied to the field memory 16 and writing in the field where the mask control signal is not generated is executed. Reading out is executed in the field where the mask control signal is generated. As a result, the signals are directly taken out in the period when the processing by the mask processing circuit 15 is not executed and the signals read out of the field memory 16 are taken out to a video output terminal 18 in the period when the processing is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a VTR in which a magnetic tape is wound around a rotary drum in a range larger than the recording range of a video signal, and a PCM signal is recorded / reproduced in the range of the extraly wound magnetic tape. It is about.

[0002]

2. Description of the Related Art For example, in a so-called 8 mm VTR, it is stipulated that a magnetic tape is wound around a rotating drum in a range larger than a recording range of a video signal, and a PCM signal is recorded / reproduced in the range of the extraly wound magnetic tape. ing. In such a VTR, after-recording of, for example, an audio signal can be performed on the PCM signal, and the PC can be reproduced while reproducing the video signal from the recording range of the video signal.
For example, a PCM audio signal is recorded in the recording range of the M signal.

In such an apparatus, when the recording / reproducing head of one of the recording / reproducing heads starts to record the PCM audio signal by the other recording / reproducing head when the reproduction of the video signal reaches the latter half of the track. The PCM audio signal from the recording / reproducing head crosstalks to one recording / reproducing head, and the reproduced signal of the video signal is significantly deteriorated.
Therefore, conventionally, the reproduction signal of the video signal of one recording / reproducing head after the recording of the PCM audio signal is started by the other recording / reproducing head is masked so that the deteriorated video signal is not output. Was being done.

However, in the above-mentioned apparatus, it is considered that the erasing head on the rotating drum is used to erase the recording range of the PCM signal and then record the PCM signal. In that case, in the above-mentioned device, during the operation period of the erasing head, the reproduction of the video signal by the recording / reproducing head corresponds to the central portion of the track, and the image quality of the central portion of the reproduced image deteriorates. Further, when the reproduction signal of this portion is masked as described above, the video signal is masked over a wide range, and the range where the reproduction signal can be obtained becomes extremely small. Further, the central portion of the reproduced image is masked, resulting in extremely poor visibility.

[0005]

The problem to be solved is to perform after-recording with a PCM signal in the case where the PCM signal is recorded after the recording range of the PCM signal is erased by using the erasing head on the rotating drum. The image quality of the central portion of the reproduced image is deteriorated, and the central portion of the reproduced image is masked, resulting in extremely poor visibility.

[0006]

The first means of the present invention is to provide at least two recording / reproducing heads 8A and 8B on the rotating drum 7 and one erasing head for erasing two tracks at a time. 8E is provided, and the magnetic tape 9 is wound around the rotary drum in a range larger than the recording range of the video signal, and the PCM signal is recorded / reproduced in the range of the extraly wound magnetic tape. When the PCM signal is recorded while the video signal is reproduced by the recording / reproducing head, the recording range of the PCM signal is erased by the erasing head and the recording is performed while the erasing head is operating. The VTR is characterized in that the reproduction signal from the reproduction head is replaced with the reproduction signal from the recording / reproduction head one field before and is output.

A second means according to the present invention is the VTR described in the first means, which has a field memory 16 and outputs a reproduction signal of one field from the recording / reproducing head during a period in which the erasing head is not operating. This is a VTR which is written in the field memory, and the written reproduction signal of one field is read and replaced during the operation of the erasing head.

A third means according to the present invention is the VTR according to the second means, in which the replacement is performed for the entire field in which the erase head operates.

A fourth means according to the present invention is the VTR according to the second means, wherein the replacement is performed only during the operation of the erase head.

[0010]

According to this, the reproduction signal from the recording / reproducing head during the operation of the erasing head is replaced with the reproduction signal from the recording / reproducing head one field before, and is output. It is possible to obtain a reproduced image with good visibility without deterioration of image quality and loss of the central portion of the reproduced image.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, first, during normal recording, a video signal from a video input terminal 1 is a video signal recording processing circuit 2.
And the processed signal is supplied to the channel changeover switches 3a and 3b. The audio signal from the audio input terminal 4 is supplied to the encoder circuit 5 for the PCM signal, and the encoded signal is supplied to the switches 3a and 3b. The signals from these switches 3a and 3b are supplied to recording / reproducing changeover switches 6a and 6b, respectively.
Signals from these switches 6a and 6b are supplied to recording / reproducing heads 8A and 8B provided on the rotary drum 7, respectively.

The heads 8A and 8B are the rotary drum 7
They are provided on the upper side and face each other by 180 degrees. The magnetic tape 9 is wound around the rotary drum 7 in a range larger than 180 degrees, and a video signal is recorded as one field in one track in the range of 180 degrees, and the PCM is recorded in the extra wound range. The signal is recorded.

Further, an erasing head 8 is attached to the rotary drum 7.
Only one E is provided at a 90 degree position between the heads 8A and 8B. This erase head 8E has an erase signal generation circuit 10
The erase signal is supplied to erase the recorded track. The erasing head 8E includes heads 8A and 8B.
A step is provided to the magnetic tape 9 in advance, and an erasing width of two tracks is provided so that two tracks are erased for each rotation of the rotary drum 7. There is.

During normal reproduction, the heads 8A, 8B
Signals from the recording / playback selector switch 6a,
6b, and the signals from these switches 6a and 6b are supplied to the channel selector switches 11a and 11b, respectively.
b. The signal from this switch 11a is PC
The M signal decoder circuit 12 supplies the decoded audio signal to the audio output terminal 13.

The signal from the switch 11b is also supplied to the video signal reproduction processing circuit 14. The video signal reproduced by the processing circuit 14 is supplied to the field memory 16 through the mask processing circuit 15. Then, the signal from the field memory 16 is taken out to the video output terminal 18.

In this device, when the PCM signal is after-recorded, the recording / reproducing changeover switches 6a and 6b are switched to the reproducing side when the heads 8A and 8B are in contact with the recording range of the video signal. The recording side of the PCM signal is switched to the recording side. This allows after-recording of the PCM signal.

Here, such control is carried out by the control computer 19 in synchronization with the servo system (not shown) by applying a servo of the entire apparatus with a reproduction signal. That is, in this apparatus, the control computer 19 outputs a switching signal that is inverted for each field as shown in A of FIG. 2, for example, and the switches 6a and 6b are controlled by this switching signal.

In the control computer 19, B in FIG.
A vertical synchronizing signal as shown in is generated. Then, an erasing control signal corresponding to the period in which the erasing head 8E is in contact with the recording range of the PCM signal is formed from the synchronizing signal, as shown in C of FIG. When supplied, the erase head 8E is operated.

In the control computer 19, D in FIG.
A mask control signal having a width wider than that of the erase control signal described above is formed. This signal is supplied to the mask signal generation circuit 20.

Further, the above-mentioned vertical synchronizing signal is supplied to the mask signal generating circuit 20. As a result, the mask generation circuit 20 generates a signal corresponding to the period in which the other recording / reproducing head 8B is in contact with the recording range of the PCM signal from the vertical synchronizing signal. A mask signal as shown by E in FIG. 2 is generated by this signal and the mask control signal described above. This signal is the mask processing circuit 1
5 is supplied.

Further, from the control computer 19, FIG.
A write control signal as indicated by F is output and this signal is supplied to the field memory 16. As a result, in the field memory 16, a signal is directly extracted and written in a field in which a mask control signal is not generated, and reading is performed in a field in which a mask control signal is generated. This field memory 16
The signal read from is output to the video output terminal 18.

Therefore, in this apparatus, for example, in the track on the magnetic tape 9 as shown in FIG. 3, one recording / reproducing head 8A is in contact with the other recording / reproducing head 8B in the recording range a of the PCM signal. Erasing head 8E in a range b in which the
The mask signal (E in FIG. 2) is formed in a period corresponding to a range c in which one recording / reproducing head 8A is in contact with each other.

In this case, the erasing head 8E has 1
Since two tracks are erased each time, the above range c is generated once every two tracks (two fields). Therefore, the reproduction signal of the field in which the mask signal in the range c is not generated is written in the field memory 16. By replacing the reproduction signal with the signal read from the field memory 16 during the field in which the mask signal is generated, it is possible to obtain the reproduction signal with the masked range reduced.

That is, for example, a reproduction signal as shown in FIG. 4A is extracted from the mask processing circuit 15,
The mask range of the range c is replaced with the reproduction signal by the signal read from the field memory 16 to form the reproduction signal as shown in B of FIG.

Thus, according to the above apparatus, the reproduction signal from the recording / reproducing head in operation of the erasing head is replaced with the reproduction signal from the recording / reproducing head one field before, and the reproduced signal is output. It is possible to obtain a reproduced image with good visibility without deteriorating the image quality of the central part or missing the central part of the reproduced image.

The replacement of the reproduced signal may be performed only in the range c of the mask signal in units of horizontal scanning lines, or may be replaced in units of fields, so-called field skip.

Further, the present invention is an apparatus in which a track is divided into a plurality of areas and each of them can be after-recorded, and is applied to all the apparatuses provided with an erasing head for erasing a plurality of tracks. it can.

[0028]

According to the present invention, the reproduction signal from the recording / reproducing head during operation of the erasing head is replaced with the reproduction signal from the recording / reproducing head one field before, and the reproduced signal is output. It has become possible to obtain a reproduced image with good visibility without deteriorating the image quality of the central part and missing the central part of the reproduced image.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of a VTR according to the present invention.

FIG. 2 is a diagram for explaining the explanation.

FIG. 3 is a diagram for explaining the explanation.

FIG. 4 is a diagram for explaining the explanation.

[Explanation of symbols]

 1 video input terminal 2 video signal recording processing circuit 3a, 3b channel selection switch 4 audio input terminal 5 PCM signal encoder circuit 6a, 6b recording / reproduction switching switch 7 rotary drum 8A, 8B recording / reproduction head 8E erasing head 9 magnetic tape 10 Erase signal generation circuits 11a and 11b Channel changeover switch 12 PCM signal decoder circuit 13 Taken out to an audio output terminal 13. 14 video signal reproduction processing circuit 15 mask processing circuit 16 field memory 18 video output terminal 19 control computer 20 mask signal generation circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04N 5/7826 5/91 H04N 5/782 A 7734-5C 5/91 M 7734-5C N

Claims (4)

[Claims] 1. A rotary drum is provided with at least two recording / reproducing heads and one erasing head for erasing two tracks at a time, and a magnetic tape is used in a range larger than a recording range of a video signal. In a VTR which is wound around the rotary drum and which records and reproduces the PCM signal in the range of the magnetic tape which is additionally wound, recording the PCM signal while reproducing the video signal by the recording and reproducing head. In this case, the erasing head erases the recording range of the PCM signal, and the reproduction signal from the recording / reproducing head during the operation of the erasing head is changed to the reproduction signal from the recording / reproducing head one field before. The VTR is characterized in that it is replaced with and output. 2. The VTR according to claim 1, further comprising a field memory, wherein a 1-field reproduction signal from the recording / reproducing head during a period in which the erasing head is not operating is written into the field memory, and is written. A VTR for reading and reproducing the reproduced signal of one field during the operation of the erasing head. 3. The VTR according to claim 2, wherein the replacement is performed for the entire field in which the erase head operates. 4. The VTR according to claim 2, wherein the replacement is performed only while the erase head is operating.