JPH06101105B2 - Video signal recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a baseband signal and an MU in an HD-TV, for example.
The present invention relates to a video signal recording / reproducing device capable of recording / reproducing an SE signal together.

[Prior Art] The HD-TV [high-definition television] method is the most powerful method for improving the quality of television images. In addition, as a method of band compression of this HD-TV video signal for transmission, MUSE [multiple sub-Nyquist sam
pling encoding] method has been developed. Then, record such HD-TV baseband signal and MUSE signal.
Currently, some VTR [video tape recorder] have already been proposed.

Proposed VTRs for recording HD-TV baseband signals include, for example, "Wideband Recording Technolog".
y for High-Definition Baseband VCRS "(1978 IEEE
Vol.CE-33 No.3) is available.

This VTR has a rotating drum rotation speed of 5400 rpm, which is three times that of a conventional home VTR, in order to record and reproduce a video signal in which the luminance signal is band-limited to 20 MHz and the color signal is band-limited to 5 MHz. It uses a segment recording method that divides into one segment and records on different tracks. In addition, each of these divided tracks has an additional 2
The recording frequency is narrowed by dividing the book into two channels for two-channel recording.

Since the MUSE signal is compressed to about half the band of the above baseband signal, for example, the number of rotations of the rotary drum is set to twice that of a conventional home VTR, and one field is divided into two segments for one channel. A VTR for recording is proposed. The VTR of the MUSE signal enables recording for a longer time than the case of the baseband signal.

[Problems to be Solved by the Invention]

However, these HD-TV baseband signals are recorded.
The VTR, which records the VTR and the MUSE signal, has been developed as a separate device that targets only the respective video signals.

Therefore, conventionally, high-quality recording is possible, but a VTR for baseband signal recording that has a short recording time is used, or long-time recording is used only for recording MUSE signals targeted for satellite broadcasting. There is a problem in that it is necessary to select whether or not to use the available VTR, and it is not possible to record / reproduce both with a single device.

This is also a common problem when a wide band video signal and a narrow band video signal can be selected in a certain system.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, a video signal recording / reproducing apparatus according to the present invention is a video signal recording / reproducing apparatus for helically recording a video signal on a video tape by a magnetic head on a rotating drum. A recording track adjacent to a recording track formed on a video tape by the first magnetic head and having a magnetic gap opposite to that of the first magnetic head is formed at the same rotation of the rotary drum. A magnetic tape having a reverse magnetic gap with respect to the first magnetic head and a second magnetic head disposed at a position where the first magnetic head rotates when the rotary drum rotates forward. The third recording track, which is adjacent to the recording track formed above, is arranged at a position where the recording track can be formed at the next rotation of the rotary drum.
One or more sets of magnetic heads including the above magnetic head are provided on the rotating drum, and the second magnetic head and the third magnetic head are switched to combine with the first magnetic head. When the second magnetic head is used, the traveling speed of the video tape is set high, and when the third magnetic head is used, the head switching unit that determines the magnetic head to be used and the switching of the magnetic head by the head switching unit is used. Is provided with tape speed switching means for reducing the running speed of the video tape.

[Action]

The head switching unit switches the second magnetic head and the third magnetic head by operation or by detecting a recording / reproducing signal to determine a magnetic head to be used in combination with the first magnetic head. At this time, even if either the second magnetic head or the third magnetic head is combined,
The magnetic gap has the opposite azimuth angle with respect to the magnetic head. When the tape speed switching means uses the second magnetic head, the traveling speed of the video tape is set to a high speed when the tape speed switching means uses the second magnetic head, and when the third magnetic head is used, the video speed is changed. Reduce the tape running speed.

Then, when the second magnetic head is used, the first magnetic head
It is possible to simultaneously form two recording tracks adjacent to each other on the video tape running at a high speed by the magnetic head and the second magnetic head. Therefore, it is possible to record a video signal having a wide band on two channels in azimuth.

When the third magnetic head is used, recording tracks adjacent to each other on the video tape running at a low speed by the first magnetic head and the third magnetic head are alternately arranged for each rotation of the rotary drum. Can be formed. Therefore,
Using the same device, it is possible to record a narrow band video signal in one channel in azimuth.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

This embodiment shows a video signal recording / reproducing apparatus for recording / reproducing an HD-TV baseband signal and a MUSE signal by a so-called 1.5 head system.

The HD-TV baseband signal requires a band of 20 MHz or more, which is about five times that of the current NTSC video signal in order to obtain a high-quality image. Therefore, in order to record such a baseband signal, the relative speed between the magnetic head and the video tape must be 2 to 3 times higher than that of a conventional home VTR, and the drum rotation speed must be 3600 to 7200 rpm. Bandwidth needs to be increased. It is also necessary to divide the track into two-channel recording to narrow the recording band of each track by half. Here, if the band of the baseband signal is 24 MHz, the band per channel becomes 12 MHz due to the two channels. And the recording method of VTR is generally FM
This is a modulation method, and the carrier center frequency is 18 MHz.
Therefore, if the deviation (frequency deviation) is ± 2 MHz, the recording band in this case is 16 to 20 MHz.

The required band of the MUSE signal is reduced to about half by band-compressing the baseband signal. Therefore, this MU
In order to record the SE signal, it suffices to have a recording band for one channel in the case of the baseband signal.

As a result, in order to record the HD-TV video signal, the baseband signal may be recorded in two channels and the MUSE signal may be recorded in one channel.

The arrangement of the magnetic heads 2 and 3 on the rotary drum 1 in the video signal recording / reproducing apparatus of this embodiment is shown in FIGS. 2 and 3.

As shown in FIG. 2, the magnetic head 2b is arranged behind the magnetic head 2a by 5.45 ° and the magnetic head 2c is arranged behind the magnetic drum 2a by 20 °. The magnetic head 3a is arranged 90 ° behind the magnetic head 2a. In contrast to this magnetic head 3a, the magnetic head 3b
Are arranged at a rear of 5.45 °, and the magnetic head 3c is arranged at a rear of 20 °. Here, the rotary drum 1 has a diameter of 76 mm.
And is rotated at a speed V _H of 3600 rpm by a motor (not shown).

Further, as shown in FIG. 3, the magnetic head 2b has a relative height of 27.83 μm above the rotating drum 1 with respect to the magnetic head 2a, and the magnetic head 2c has a relative height below 1.49 μm. Has height. The magnetic head 3a is the magnetic head 2a.
In contrast, it has a relative height of 2.9695 mm above. The magnetic head 3b is located above the magnetic head 3a by 27.83.
It has a relative height of μm, and the magnetic head 3c is 1.49μ downward.
It has a relative height of m.

Further, when the azimuth angle of the magnetic gap 6 in the magnetic head 2a is positive, the azimuth angle of the magnetic gap 6 in the magnetic heads 2b and 2c is set to the opposite negative. If the azimuth angle of the magnetic gap 6 in the magnetic head 3a is positive, the azimuth angle of the magnetic gap 6 in the magnetic heads 3b and 3c is also set to the opposite negative.

The magnetic heads 2a to 2c are a set of magnetic heads for forming the main track 8 in the so-called 1.5 head system described later. The magnetic heads 3a to 3c are a set of magnetic heads for forming the auxiliary track 9 in the 1.5 head system described later. It is preferable that these magnetic heads 2 and 3 are arranged as close to each other as possible within each set, and it is suitable that they are integrated heads.

The rotary drum 1 on which the magnetic heads 2 and 3 are arranged in this way
As shown in FIG. 2, a video tape 7 running in the same direction as the rotating direction of the rotating drum 1 is helically wound around the. The video tape 7 is guided by the supply side guide pole 4 and the winding side guide pole 5 and is wound around the rotary drum 1 so that the effective winding angle θ _v is 312 °.

On the video tape 7, as shown in FIG. 4, the magnetic head 2 of the rotary drum 1 forms a main track 8 and the magnetic head 3 forms an auxiliary track 9. Here, with respect to the video tape 7, the track lead angles θ ₀ of the main track 8 and the auxiliary track 9 have the following relationship. However, the recording lengths of the main track 8 and the auxiliary track 9 are L ₁ and L ₂ , respectively, and the effective recording widths of these tapes are W ₁ and W ₂ .

θ ₀ = sin ^-1 (W ₁ / L ₁ ) = sin ^-1 (W ₂ / L ₂ ). Also, the recording length L ₁ · L _{2 of the} main track 8 and the auxiliary track 9
Is dependent on the winding angle of the video tape 7 around the rotary drum 1 and is expressed by the following equation. However, the rotary drum 1 shown above
Let D be the diameter of. The effective winding angle θ _v is 312 ° as described above, and the auxiliary winding angle θ _v0 is 48 °.

L ₁ = π · D (θ _v / 360 °) L ₂ = π · D (θ _v0 / 360 °) As a result of the above, the main track 8 and the auxiliary track 9 enable recording over the entire circumference of the rotary drum 1. According to the so-called 1.5 head system, a video signal is recorded / reproduced for one field while the rotary drum 1 makes one revolution, and one frame is recorded / reproduced for two revolutions.

The structure of the control unit for controlling the magnetic heads 2 and 3 and the video tape 7 will be described with reference to FIG.

The video signal is input to the signal processing circuit 11 for recording, and is output from the signal processing circuit 11 and reproduced. The signal processing circuit 11 processes the video signal.
This is a circuit that performs signal processing such as A / D conversion and adding a synchronization signal to it. The signal processing circuit 11 is connected to the magnetic heads 2 and 3 of the rotary drum 1 via a head switching circuit 12 and a head amplifier 13. Then, the video signal processed by the signal processing circuit 11 is the head switching circuit.
12 is sent to the magnetic heads 2 and 3 via the head amplifier 13 and the video signal reproduced by the magnetic heads 2 and 3 is sent to the signal processing circuit 11 via the head amplifier 13 and the head switching circuit 12. It is like this. The head switching circuit 12 is a circuit that switches between the magnetic head 2b and the magnetic head 2c in the magnetic head 2 and also switches between the magnetic head 3b and the magnetic head 3c in the magnetic head 3.
Then, the head switching circuit 12 causes the magnetic heads 2a and 2b to
And the combination of the magnetic heads 3a and 3b are selected, the video signals divided into two channels are respectively supplied to the magnetic head 2a.
To the magnetic head 2b at the same time, and to the magnetic head 3a and the magnetic head 3b at the same time. Further, when the combination of the magnetic heads 2a and 2c and the magnetic heads 3a and 3c is selected by the head switching circuit 12, the video signal of one channel is output to the magnetic head 2a every one rotation of the rotary drum 1.
To the magnetic head 2c, and to the magnetic head 3a and the magnetic head 3c alternately. This operation is the same during reproduction. The head amplifier 13 is a circuit that amplifies a video signal and controls an optimum current.

The video signal from the signal processing circuit 11 is a signal selection circuit.
It will be sent to 14 as well. The signal selection circuit 14 is
This is a circuit that determines whether the video signal sent is a baseband signal or a MUSE signal, and outputs a signal to the head switching circuit 12 and the head amplifier 13 in accordance with this. The signal selection circuit 14 can also be configured by a hardware-like changeover switch that switches between the case of the baseband signal and the case of the MUSE signal by operation. The head switching circuit 12 performs the switching based on the signal from the signal selection circuit 14.

The speed control circuit 15 is a circuit that controls the running speed of the video tape 7 based on the signal from the signal selection circuit 14. The output of this speed control circuit 15 is the capstan motor.
Connected to 16. The capstan motor 16 is a motor that drives the capstan 18, and the video tape 7 is
The capstan 18 and the pinch roller 17 allow the vehicle to travel at a constant speed.

The operation of the video signal recording / reproducing apparatus having the above configuration will be described with reference to FIG.

At the time of recording and reproducing the video signal, the signal selection circuit 14 determines whether the signal is a baseband signal or a MUSE signal. Then, in response to this, the head switching circuit 12 switches the magnetic heads 2 and 3, and the speed control circuit 15 controls the running speed of the video tape 7.

When the video signal is a baseband signal, the head switching circuit 12 causes the magnetic heads 2a and 2b and the magnetic heads 3a and 3a
3b is selected, and the speed control circuit 15 increases the running speed of the video tape 7. Therefore, in this case, a track pattern as shown in FIG. 5A is formed on the video tape 7. That is, the main tracks 8a and 8b adjacent to each other are simultaneously formed by the magnetic heads 2a and 2b, and the auxiliary tracks 9a and 9b adjacent to each other are simultaneously formed by the magnetic heads 3a and 3b. Then, during one rotation of the rotary drum 1, one field is the main tracks 8a and 8b and the auxiliary track 9a.
・ It is composed of 2 tracks each of 9b, and it becomes 2 channel recording. Further, in the magnetic head 2a and the magnetic head 2b and the magnetic head 3a and the magnetic head 3b, since the magnetic gap 6 has the opposite azimuth angle, the main track 8a and the main track 8b and the auxiliary track 9a and the auxiliary track 9b. Guard bandless recording is possible, and the video tape 7 can be effectively used.

If the video signal is a MUSE signal, the head switching circuit
The magnetic heads 2a and 2c and the magnetic heads 3a and 3c are selected by 12, and the speed control circuit 15 reduces the running speed of the video tape 7. Therefore, in this case, a track pattern as shown in FIG. 5B is formed on the video tape 7. That is, when the main track 8a is formed by the magnetic head 2a, the next rotation of the rotary drum 1 forms the adjacent main track 8c by the magnetic head 2c. When the auxiliary track 9a is formed by the magnetic head 2a, the auxiliary track 9c adjacent thereto is formed by the magnetic head 3c in the next rotation of the rotary drum 1. Therefore,
In this case, one field is formed by one track each of the main track 8a or main track 8c and the auxiliary track 9a or auxiliary track 9c, and one-channel recording is performed. Further, in the magnetic head 2a and the magnetic head 2c and the magnetic head 3a and the magnetic head 3c, since the magnetic gap 6 has the opposite azimuth angle, the main track 8a and the main track 8c and the auxiliary track 9a and the auxiliary track 9c. Guard bandless recording is possible, and the video tape 7 can be effectively used.

The magnetic head 2c selected for this MUSE signal
Is disposed at a position delayed by 20 ° with respect to the magnetic head 2a, the main track 8c causes a delay of 20 ° in terms of signal phase with respect to the main track 8a. Therefore, in the case of this MUSE signal, it is necessary to delay the video signal by a line memory or the like and adjust this delay.

Table 1 shows the specifications for the above baseband signal and MUSE signal. However, in all cases, the track patterns are arranged in _H (α _H = 1.5).

As described above, the video signal recording / reproducing apparatus of the present embodiment records a wideband video signal in two channels without deteriorating the image quality, and records a narrowband video signal in one channel. It is possible to record for a long time.

When recording not only video signals but also PCM audio signals, 4 channels are recorded with 16-bit quantization for baseband signals and 4 channels with 8-bit quantization for MUSE signals. The fact that recording can be performed is similar to the above case.

Further, in the present embodiment, the so-called 1.5 head system video signal recording / reproducing apparatus has been described, but it is also possible to carry out other systems, and the drum diameter and the head mounting dimension are not limited to the above. . Further, the present invention is not limited to the case of HD-TV, and can be similarly performed when a wide band video signal and a narrow band video signal can be selected in another system.

〔The invention's effect〕

As described above, the video signal recording / reproducing apparatus according to the present invention is a video signal recording / reproducing apparatus for helically recording a video signal on a video tape by the magnetic head on the rotating drum. The magnetic gap has a reverse azimuth angle with respect to the magnetic head, and
With respect to the first magnetic head and the second magnetic head arranged at a position where the recording track adjacent to the recording track formed on the video tape by the first magnetic head can be formed at the same rotation of the rotating drum. The magnetic gap has an opposite azimuth angle, and a recording track adjacent to the recording track formed on the video tape by the first magnetic head when the rotating drum is rotated forward is formed when the rotating drum is rotated next time. A set of one or more magnetic heads including a third magnetic head arranged at a position obtained as described above is provided on the rotating drum, and the second magnetic head and the third magnetic head are switched. According to the above, the head switching means that determines the magnetic head to be used in combination with the first magnetic head, and the magnetic head switching by the head switching means, When the second magnetic head is used, the traveling speed of the video tape is high, and when the third magnetic head is used, the tape speed switching means for lowering the traveling speed of the video tape is provided. There is.

As a result, when the second magnetic head is used,
Two recording tracks adjacent to each other are simultaneously formed on the video tape running at a high speed by the first magnetic head and the second magnetic head. Further, when the third magnetic head is used, the first magnetic head and the third magnetic head alternate recording tracks adjacent to each other on the video tape running at a low speed every rotation of the rotary drum. Will be formed.

Therefore, according to the present invention, a wide band video signal and a narrow band video signal can be recorded and reproduced by one device,
The user can appropriately select whether to give priority to the image quality or the recording time.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a block diagram of a control unit of a video signal recording / reproducing apparatus, FIG. 2 is a plan view of a rotary drum, and FIG. Is a layout view showing the positional relationship of the magnetic head, FIG. 4 is a front view of a video tape showing a track pattern formed by the magnetic head, and FIG. 5 (a) shows a track pattern when a baseband signal is recorded. Front view of videotape, No. 5
FIG. 6B is a front view of the video tape showing the track pattern when the MUSE signal is recorded. 1 is a rotating drum, 2a and 3a are magnetic heads (first magnetic head), 2b and 3b are magnetic heads (second magnetic head), 2c and
3c is a magnetic head (third magnetic head), 6 is a magnetic gap, 7 is a video tape, 8 is a main track (recording track), 9 is an auxiliary track (recording track), and 12 is a head switching circuit (head switching means). , 15 are speed control circuits (tape speed switching means).

Claims (1)

[Claims] 1. A video signal recording / reproducing apparatus for helically recording a video signal on a video tape by a magnetic head on a rotating drum, comprising: a first magnetic head and an azimuth having a magnetic gap opposite to that of the first magnetic head. A second magnetic head having an angle and arranged at a position where a recording track adjacent to a recording track formed on the video tape by the first magnetic head can be formed at the same rotation of the rotating drum;
The magnetic gap has an azimuth angle opposite to that of the first recording head, and the recording track adjacent to the recording track formed on the video tape by the first magnetic head is rotated when the rotary drum rotates forward. One or more sets of magnetic heads each including a third magnetic head arranged at a position that can be formed at the time of the next rotation of the drum are provided on the rotating drum, and the second magnetic head and the third magnetic head are provided. A head switching unit that determines a magnetic head to be used in combination with the first magnetic head by switching the magnetic head of
With the switching of the magnetic heads by the head switching means, the traveling speed of the video tape is made high when the second magnetic head is used, and the traveling speed of the video tape is made low when the third magnetic head is used. And a tape speed switching means for controlling the video signal recording / reproducing apparatus.