JPH041403B2 - - Google Patents

Description

[Detailed Description of the Invention] Helical scan type VTRs with Ω windings have one magnetic head with a large wrap angle (approximately 340°) as shown in Figure 1, and two types as shown in Figure 2. There is also a magnetic head with a small wrap angle (around 180°). A VTR with a single magnetic head and a large wrap angle, as shown in Figure 1, has a large drum diameter;
Since a VTR with a small wrap angle and two magnetic heads as shown in the figure can have a small drum diameter, the VTR with the configuration shown in FIG. 2 is suitable for small-sized VTRs.

However, this type of VTR requires two rotating magnetic heads Ha and Hb, and in particular, in order to perform multi-channel multi-track recording, each magnetic head Ha,
When using a multi-head configuration as the Hb,
It becomes necessary to adjust the height between each magnetic head Ha and Hb and the mounting angle position. These adjustments are very complicated. Maintenance and inspection are also not easy.

In addition, in the configuration shown in FIG. 2, since the heights of the magnetic heads Ha and Hb are equal, for example, during still playback, the magnetic heads Ha and Hb scan only with the same head locus as shown in FIG. Only the signals can be played back. Therefore, the S/N ratio during still playback is low.

Furthermore, when trying to add dynamic tracking functions and editing functions for straight tracking in variable speed playback mode to this VTR, in addition to the above-mentioned magnetic heads Ha and Hb, a bimorph board etc. was used. Two playback heads and two erase heads for dynamic tracking must be mounted on the rotating drum. Since the rotary drum is a small diameter drum, the space in which these multiple heads must be installed is a problem. Position adjustment etc. are also troublesome.

Therefore, the present invention eliminates the above-mentioned drawbacks by devising a VTR having a wrap angle as shown in Figure 2 so that it can record and reproduce signals using a single magnetic head in a multi-head configuration. It is.

Therefore, in the present invention, a multi-magnetic head H _M having multi-gaps is provided on a rotating drum or a rotating disk 1, as shown in FIG. The wrap angle θ of tape 3 is 180° + α. The wrap angle α is provided for recording information different from video information, for example.

Figure 5 shows an example of the multi-magnetic head _HM used in this embodiment.As will be described later, this example uses a segment recording method in which the first half and second half of the video signal are recorded on separate tracks, and each video signal is Since this is a case in which recording is divided into two channels, four heads H ₁ to H ₄ are mounted and fixed on the same base 5. A specific example is shown in FIG.

In the figure, reference numeral 5 denotes a head base in the form of a flat plate, and on its upper surface 5a, four magnetic heads _H1 to _H4 each having a predetermined shape are stacked and combined as shown in the figure.
The heights of the magnetic heads H ₁ to _{H 4} are selected to increase successively from one side to the other, and the azimuth angles (positive azimuth) of the gaps g ₁ and g ₃ and the azimuth of the gaps g ₂ and g ₄ are selected. The angles (minus azimuth) are designed to be equal, so that the azimuth angles on each track T ₁ -T ₄ are different between adjacent tracks as shown.

With this multi-magnetic head H _M , you can
As shown in the figure, four tracks _T1 to _T4 are formed simultaneously. The azimuth angle of each magnetic head H ₁ to _{H 4} at that time is shown by a solid line.

In the present invention, a recording system 10 is constructed as shown in FIG. 8 in order to record video signals and the like on a tape 3 with a wrap angle θ of 180°+α using one multi-magnetic head _HM , and to be able to reproduce the video signals from the tape 3. First, the video signal S _N is supplied to the delay circuit 11 and delayed by 1/2 vertical period. Therefore, the delayed signal S _D and the current signal
The relationship with S _N is as shown in Figure 10. delayed signal
S _D is supplied to a pair of encoders 12 and 13,
In this example, it is converted to a digital signal. Furthermore, in this example, the delayed signal S _D is divided into two channels and recorded, so one encoder 12 outputs, for example, an n-bit digital signal related to the odd-numbered sampling output, and the other The encoder 13 outputs a digital signal related to even-numbered sampling outputs.

Similarly, the current signal S _N is also sent to a pair of encoders 14 and 15 to form a two-channel digital signal.
One encoder 14 outputs a digital signal related to odd-numbered sampling outputs, and the other encoder 15 outputs a digital signal related to even-numbered sampling outputs.

These two channels of digital signals are supplied to magnetic heads _H1 - _H4 through amplifiers 16-19, respectively, and are simultaneously recorded on predetermined tracks _T1 - _T4 .

Now, since the wrap angle .theta. of the tape 3 is approximately 180 degrees, signals are recorded only in the 1/2 vertical period period in which the magnetic heads _H1 to _H4 are in contact with the tape 3. Therefore, as shown in Figure 10, the current signal
Current signal S _N (second half video signal Sa ₂ , Sb ₂ ...) and delayed signal _SD (first half video signal Sa ₁ , Sb ₁ ...) existing in the second half of each vertical section based on S _N The signals are recorded simultaneously, and no signals are recorded in the first half. That is, the first half of each vertical section is a rest period, and only the second half is a signal recording period.

FIG. 9 shows an example of the reproduction system 20, in which the magnetic head H ₁
The digital signals corresponding to the video signals Sa ₁ , Sa ₂ , Sb ₁ . . . reproduced from ~H ₄ are sent to preamplifiers 21 to 24.
are supplied to decoders 25 to 26 via the decoders 25 to 26 to be decoded into odd and even sampling outputs, and each of these outputs is supplied to time base correction circuits (TBC) 30 to 33 to correct the time base. It is done.

The signals of each channel whose time axis has been corrected are supplied to the frame memory _{35 ,} and the channel signals inputted at the same timing are read out alternately. It is read out with a delay of one cycle. As a result, the same video signal as the input is output from the terminal 36.

As explained above, according to the present invention, one magnetic head H _M of a multi-head configuration is used, and the recording system 10 is configured as shown in FIG.
Even if the wrap angle of tape 3 is approximately 180 degrees, video signals can be reliably recorded and reproduced. Therefore, according to the present invention, the number of magnetic heads to be attached to the rotating drum 1 can be reduced, and since there is only one magnetic head, the height between the heads can be reduced compared to the case of the configuration shown in FIG. This eliminates all troublesome adjustments such as height adjustment and mounting angle position adjustment. Maintenance and inspection become easier.

Furthermore, in the multi-magnetic head H _M used in the present invention, since the magnetic heads H ₁ to _{H 4} have different heights, they travel on the track shown by the dashed line in FIG. 11 during still reproduction. Therefore, the shaded area becomes the reproduction area, and the reproduction section is wider than in the conventional example shown in FIG. This allows the S/
N can be improved.

Furthermore, in this VTR, rotating drum 1 has one
Since only one multi-magnetic head _HM is installed, there is enough space to install a playback head for dynamic tracking and an erase head for insert editing even with a small diameter drum.

Therefore, the present invention is extremely suitable for application to small-sized VTRs.

Note that the above example is an example of 2-channel 4-track recording, but in the case of 2-channel 2-track recording, a multi-magnetic head with two heads is used, and the recording/reproducing system shown in FIGS. 8 and 9 is used. You can use . In the case of two channels and six tracks, a multi-magnetic head with six magnetic heads is used. The video signals include a first delayed signal delayed by 1/3 vertical period, and a delayed signal delayed by 2/3 from the current signal.
A second delayed signal with a vertical period delay is formed, and the current signal at a time delayed by 2/3 vertical period from the current signal and the first signal are
and a second delayed signal are recorded over a period of 1/3 vertical period.

Furthermore, when recording a video signal by dividing it into two channels, the distribution of the signal to each channel is not limited to the above example. Alternatively, the luminance signal and the carrier color signal may be separated and recorded in their respective channels. Alternatively, the luminance signal and the carrier color signal may be separated from the beginning and then recorded on a predetermined channel using the method described above.

The signal may be recorded as an analog signal.

[Brief explanation of drawings]

Figures 1 and 2 are of helical scan type.
An explanatory diagram of a VTR, Fig. 3 is an explanatory diagram of a track pattern during still playback, and Fig. 4 is an explanatory diagram of a track pattern according to the present invention.
An explanatory diagram of an example of a VTR, Fig. 5 is a plan view of a magnetic head used in this, Fig. 6 is an enlarged front view thereof, Fig. 7 is an explanatory diagram of a track pattern, and Fig. 8 is an illustration of a signal recording system. FIG. 9 is a system diagram showing an example of the reproduction system, FIG. 10 is an explanatory diagram of the operation of FIG. 8, and FIG. 11 is an explanatory diagram of a track pattern similar to FIG. 3. H _M is the magnetic head, θ is the wrap angle, 11
is a delay circuit, and 35 is a frame memory.

Claims (1)

[Scope of Claims] 1. A video signal is divided into a predetermined division part, and each division part carries one series of temporally continuous information signals, which is wound around a rotary head device at a predetermined wrap angle. recorded on the tape by the rotary head of the rotary head device.
In a VTR, a delay of a predetermined number of units corresponding to the number of divisions is given to the information signal in units of time corresponding to one division, and the parallelized information signal has a number of sequences equal to the number of divisions. and one multi-magnetic head having a head gap number corresponding to the number of series of the parallelized information signals; A VTR characterized in that recording is performed on multiple tracks simultaneously in a section.