JPH05166297A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the flicker at the time of reproducing a still picture. CONSTITUTION:In the magnetic recording and reproducing device for multichannel dividing recording of one field or one frame of a video signal by using plural magnetic heads, identification information SI for reproducing a still picture is added to the video signal to be recorded, and at the time of reproducing, when this identification information SI is detected, the regenerative video signal is outputted by using a time and space filter 50. Since variations between the channels are averaged by using the time and space filter 50, the flicker is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus suitable for application to a high definition analog VTR or the like, and more particularly to a magnetic recording / reproducing apparatus provided with countermeasures against flicker during still reproduction.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus such as an analog VTR for high definition uses a rotary magnetic head apparatus as shown in FIG.

In the figure, reference numeral 60 is a rotary drum (or rotary disk), and magnetic heads (Ha, Hb) for recording and reproducing are arranged close to each other so that two-channel recording can be performed on the rotary drum 60. And (Hc, H
d) is arranged so as to maintain the respective intervals of approximately 180 °.

By rotating the rotary drum 60 at a double speed, the magnetic tape 61 shown in FIG. 7 has 1125/2 video signals in one field in four tracks 62a-62.
Division recording (2 segment recording) is performed over d. Therefore, for example, the track 62a is recorded by the magnetic head Ha and the track 62b is recorded by the magnetic head Hb. That is, this magnetic recording / reproducing apparatus employs 1-field 2-segment 2-channel recording.

[0005]

When still reproduction is performed by using this magnetic recording / reproducing apparatus, the operation shown in FIG.
Still images are reproduced using the video signals divided and recorded on the tracks 62a to 62d. Therefore, when the rotary magnetic head device as shown in FIG. 6 is used, the number of magnetic heads used during reproduction is four.

By the way, the magnetic heads Ha to Hd used in such a rotary magnetic head device usually have variations in reproduction sensitivity, S / N and the like. Fluctuates, which appears as flicker when a still image is reproduced.
If there is flicker, the image becomes difficult to see.

Therefore, the present invention solves such a conventional problem and proposes a magnetic recording / reproducing apparatus in which flicker is reduced even during still reproduction so that a reproduced image can be easily viewed.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a magnetic recording / reproduction is carried out in which a video signal of one field or one frame is divided into multiple channels by using a plurality of magnetic heads. In the device,
At the time of still reproduction, the multi-channel split recording video signal is output through a spatio-temporal filter for flattening.

[0009]

In the reproducing system 10P shown in FIG. 1, during the still reproduction, the changeover switch 38 is automatically changed over as shown by the broken line to supply the deshuffled reproduced video signal to the spatiotemporal filter 50. Since the spatiotemporal filter 50 is a processing circuit for averaging the reproduction output level between fields, the level difference between fields is reduced by passing this spatiotemporal filter 50. Therefore, even if there is a difference in the output level between the magnetic heads, the flicker becomes inconspicuous.

In order to switch the changeover switch 38 to the spatiotemporal filter 50 side during still reproduction, identification information SI ("(") indicating that the video signal used for still reproduction is used corresponding to the video signal used for still reproduction. 1 ”,
The binary information or code of "0" is added and recorded. At the time of still reproduction, it is switched to the spatiotemporal filter 50 side by the output that detects the identification information SI.

Alternatively, in the still reproduction mode, the change-over switch 38 is switched to the broken line shown in the figure based on the mode signal output from the system controller (not shown), and the output path using the space-time filter 50 is closed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where an example of the magnetic recording / reproducing apparatus according to the present invention is applied to the above-mentioned magnetic recording / reproducing apparatus for recording / reproducing a high-definition signal will be described in detail with reference to the drawings.

As described above, the present invention uses the spatio-temporal filter 50 during still reproduction to average the video signals. FIG. 1 exemplifies the case of using the still reproduction identification information SI as means for detecting the still reproduction state.

FIG. 1 shows an example of a reproduction system 10P of an analog VTR configured to record and reproduce a high-definition signal HD, and FIG. 2 shows the recording system 10R. For convenience of description, the recording system 10R of FIG. 2 will be described.

In FIG. 2, the luminance signal Y and the pair of color difference signals PB (= BY) and PR (= RY) are band-limited by low-pass filters 1, 2 and 3, respectively, and then A / D converter. It is converted into a digital signal by 4, 5, 6. Digitized luminance signal Y and a pair of color difference signals P
B and PR are time-division-compression-multiplexed in a time-division-multiplexing circuit (TCI encoder) 7 so that the color-difference signals are compressed and a pair of color-difference signals are line-sequentially converted into a luminance signal Y.
Are multiplexed into.

When two channels of video signals are recorded,
For example, in the A channel, the color difference signal PB is compressed on the time axis to form a compressed color difference signal, and this and the luminance signal Y are line-sequentially time division multiplexed to generate a video signal. In the B channel, the color difference signal PR is time-axis compressed to form a compressed color difference signal, and this and the luminance signal Y are line-sequentially line-sequentially time-axis multiplexed to generate a video signal. Then, the shuffling circuit 8 performs shuffling processing on each channel.

The video signals SA and SB which have been subjected to the time division multiplexing processing and the shuffling processing are D / A converters 11 and 12.
After being converted into an analog signal in, the band is limited by the low pass filters 13 and 14. Then, after being supplied to the FM modulators 15 and 16 of the next stage and subjected to FM modulation so as to be suitable for recording, dedicated magnetic heads Ha and Hb (Hc and Hd) are used via recording amplifiers 17 and 18. 2 channels are recorded.

In the present invention, the recording amplifiers 17, 1
A changeover switch 20 is provided in the front stage of 8, and
Identification information SI indicating that it is a video signal for still reproduction
Is added. When recording a video signal for still reproduction, the changeover switch 20 is changed over as shown by a broken line based on the control signal CTL from the system controller 22, and the identification information SI is inserted and recorded in the video signal.

When the recording system as shown in FIG. 7 is adopted, the tape format of the track 62a is as shown in FIG. In the figure, reference numerals 65 and 66 are audio signal recording areas, 67 is an index signal ID recording area, and 68 is a video signal recording area. A guard region 69 is formed between these regions. In this example, the above-mentioned identification information SI is added and recorded as one of the index signal IDs in the recording area 67.

FIG. 1 shows a reproducing system 10P. The video signal reproduced by the magnetic heads Ha to Hd described above is supplied to the FM demodulators 30 and 31, and the video signal is FM demodulated, and also supplied to the A / D converters 34 and 35 via the low-pass filters 32 and 33. After being converted to a digital signal, the deshuffling circuit 36 performs deshuffling processing.

The deshuffled video signal is an index signal ID detection circuit 37 and a changeover switch 3.
Time division separation circuit (TCI decoder) via 8 respectively
By being supplied to 40, the luminance signal Y and the color signal C are separated. The luminance signal Y is converted into an analog signal by the D / A converter 41. The color signal C is separated into a pair of color difference signals by the vertical filter 42, and each is converted into an analog signal by the D / A converters 43 and 44.

The above-mentioned detection circuit 37 detects the presence or absence of the index signal ID, in particular the identification information SI added thereto. When the identification information SI is not detected, the changeover switch 38 does not operate with the detection output SD at that time,
The switching state shown by the solid line is retained.

However, when the identification information SI is detected, the reproduced video signals SA and SB at that time are used as the video signals for still reproduction, and the changeover switch 38 is shown by the broken line depending on the detection output SD at that time. Can be switched to. Then, the video signals SA and SB of each channel are supplied to the time division separation circuit 40 through the space-time filter 50.

Since the spatio-temporal filter 50 averages the video signals SA and SB between fields, as will be described later, the level difference between the reproduced video signal of the first field and the reproduced video signal of the second field is reduced. The processing that becomes scarce is executed.

FIG. 4 shows a specific example of the spatiotemporal filter 50. The reproduced video signals SA and SB supplied to the terminal 51 are halved in level by the coefficient unit 52 and output to the adder 53 in the subsequent stage. To be done. Input playback video signal SA, SB
Is further supplied to the first delay circuit 54 and delayed by (1 field-1 horizontal period (1H)). This first
And the delayed output of 1H by the second delay circuit 55.
The delayed second delayed output is supplied to the switch 56 and is alternately selected in a field unit. The switching state shown by the solid line is the first field, and the switching state shown by the broken line is the second field.
The field.

The selected delay output is attenuated to 1/4 by the second coefficient unit 57 and then supplied to the adder 53. Similarly, the selected delay output is supplied to the third delay circuit 58 and further delayed by 1H. The third delay output is made 1/4 by the coefficient unit 59 and then supplied to the adder 53.

Therefore, after all, the output of the coefficient multipliers 52, 57, and 59 is added from the adder 53, so that the video signals SA and SB of the two channels are averaged in each field by this addition processing. It will be output (filtered). A specific example of the averaging process will be described with reference to FIG.

In the figure, CH indicates channels A and B. Although the first field is from the 1st line to the 562nd line, the effective line is shown from the 41st line in the figure considering that it is the 41st line. The line of the first field is represented by a solid line. A broken line indicates a line of the second field (563 lines to 1125 lines, and the effective line is shown as 603 lines as above) in interlaced relation with the first field.

When the video signal of the first field is input to the input terminal 51, for example, the video signal of the 43rd line is input, the delay circuit 54 outputs 1H from 1 field.
The previous video signal, that is, the video signal of the 606th line is output, and the video signal of the 605th line is output from the second delay circuit 55. Similarly, the video signal of the 605th line is output from the third delay circuit 58.

In the first field, the switch 56 is switched as shown by the solid line, so that in the first field, the first field = 1/2 × 43 lines + 1/4 × 606.
A video signal obtained by averaging the video signals over the preceding and following three lines including the 43 lines such as the line + 1/4 × 605 lines with the weights as described above is output. At this time,
Like the video signal of the 43rd line (spatiotemporal filter 50
Output).

On the other hand, in the second field, the lines corresponding to 43 lines are 605 lines as shown in FIG. Then, the lines output from the delay circuits 54, 55 and 58 are as shown in FIG. And switch 5
Since 6 is switched as shown by the broken line, the adder 53
The video signal of the second field output from the second field is: second field = 1/2 × 605 lines + 1/4 × 43
A video signal obtained by averaging the video signals over three lines before and after the 605 line centering on the 605 line, such as line + 1/4 × 42 line, with the above-mentioned weights is output. At this time, it is used as a video signal of the 605th line (output of the spatiotemporal filter 50) as shown in FIG. 605 line is 4
The line is one field away from the three lines.

Therefore, even if the reproduction output level difference occurs due to the variation between the channels due to such addition processing, the averaging processing is performed, so that the output level difference between the fields is small. Become. Note that similar processing is performed on the other illustrated lines, but the description thereof will be omitted.

In the above-described embodiment, the identification information SI for still reproduction is added to the video signal for recording, and when the identification information SI is detected during reproduction, the reproduction video signal is output using the spatiotemporal filter 50. Is configured to be.

The means for selecting the spatiotemporal filter at the time of still reproduction is not limited to this. For example, at the time of still reproduction, the changeover switch 38 is controlled by the mode signal for still reproduction obtained from the system controller 22 to control the reproduction output path. You may make it switch to the spatial filter 50 side.
Therefore, in this case, the identification information SI is not required.

In the above description, two-channel recording was illustrated as an example of multi-channel recording, but the present invention is not limited to this. The present invention can be applied to other than the VTR for high definition signals.

[0036]

As described above, according to the present invention, in a magnetic recording / reproducing apparatus in which a video signal of one field or one frame is divided into multiple channels by using a plurality of magnetic heads, multi-channel recording is performed during still reproduction. The divided and recorded video signal is output through a space-time filter for flattening.

Conventionally, flicker occurs in a reproduced image due to variation between channels, but according to the present invention, the flicker can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a system diagram of a reproducing system showing an example in which a magnetic recording / reproducing apparatus according to the present invention is applied to a high-definition analog VTR.

FIG. 2 is a system diagram showing an example of a recording system when the magnetic recording / reproducing apparatus according to the present invention is applied to a high definition analog VTR.

FIG. 3 is a diagram showing an example of a track pattern.

FIG. 4 is a system diagram showing an example of a space-time filter.

FIG. 5 is a diagram illustrating the operation of a space-time filter.

FIG. 6 is a conceptual diagram of a rotary magnetic head device.

FIG. 7 is a diagram of a track pattern when this rotary magnetic head device is used.

[Explanation of symbols]

 10R recording system 10P reproducing system 7 time division multiplexing circuit 20 changeover switch 21 identification information addition circuit 22 system controller 37 index signal detection circuit 38 changeover switch 40 time division separation circuit 50 spatiotemporal filter 54, 55, 58 delay circuit 52, 57, 59 Coefficient unit Ha to Hd Magnetic head

Claims (3)

[Claims] 1. A magnetic recording / reproducing apparatus in which a video signal of one field or one frame is recorded in multiple channels by using a plurality of magnetic heads, and the video signal recorded in multiple channels is flattened during still reproduction. A magnetic recording / reproducing apparatus characterized in that the data is output through a spatio-temporal filter that is changed to a digital format. 2. A reproduction signal is output by adding identification information for still reproduction to a video signal and recording the reproduction signal when the reproduction information is detected. Item 1. The magnetic recording / reproducing apparatus according to item 1. 3. During still reproduction, the reproduction output path is switched to the spatiotemporal filter side by the mode signal obtained from the system controller, and the reproduction video signal is output through this spatiotemporal filter. Magnetic recording / reproducing device.