JPH01190086A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the multilayer-recording of a video signal and a sound signal even with a small cylinder by arranging four video heads and four voice heads at the prescribed positions of the small cylinder and giving a suitable level difference between the video heads and the voice heads. CONSTITUTION:Video heads 1-4 are fitted to a rotating cylinder 9, and voice heads 5-8 are arranged between them. An angle theta between a video head and a voice head, which is the closest voice head to the video head, from the center of the cylinder 9 is set to 22 deg.<=theta<=67.5 deg.. Further, the positional relations between the video head and the voice head to trace the same track is set so that the voice head can be positioned before the video head at 90n+theta deg. in an ordinary mode, and the voice head can be positioned before the video head at (3n+1)+theta deg. (n=0, 1,2) in a double speed mode. Moreover, the level difference between the video head and the voice head is set so that the voice head can come to the upper part of the cylinder within the range from theta (n+theta/90)TEP to (n+theta/270+4/3)TEP-16mum (TEP is a track pitch in a triple mode.) for the video head in the wiring end edge of the head (lower side).

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording and reproducing device for recording and reproducing video and audio signals, and particularly to a magnetic recording and reproducing device that is effective as a compact camera-integrated video tape recorder. It is a device.

(Prior Art) In a video tape recorder (hereinafter referred to as VTR),
FM audio multiplexing systems have been widely put into practical use to improve the quality of audio signals (IIIFi). For example, in the VHS format, a method is adopted in which an audio-only head is provided in addition to the video head to reduce crosstalk between the video signal and the audio signal. In this format,
Since it uses a multilayer recording method that records audio deeply, the following conditions are required.

■Overwrite and erase the audio signal with the video signal at least once.

(2) In the standard mode (S P), the audio track width is set to 10 μm or more and 29 μm or less on one side from the center of the video head, and the video and audio azimuths are in opposite directions. (
Audio azimuth: 30° relative to video azimuth ±6″) In the 3x mode (E P), the opposing audio track width within the video track is 16 μm or more, and the video and audio azimuths are in the same direction.

(Video azimuth ±61' to audio azimuth ±30'
”) ■The time difference between video and audio should be 1/30 sec (2 fields) or less. (The time difference between audio and video on the same track is 0 to 2 fields in SP mode, 1 to 3 fields in EP mode) The matters are described in 1IiFi VH3VTR System Development (Miura, et al. MR83-20 Hitachi), and the matters marked with ■ are in Drart, Addltlonal part t.
o IEC Pub, 774 (May 30.1986)
It is described in.

On the other hand, the normal cylinder diameter T (VH3 is Φ41.3
VHS-C movies have also been commercialized that record and playback using alternately four video heads mounted on a cylinder (hereinafter referred to as a small cylinder) with a diameter of
Multi-layer recording of video signals and audio signals using this method has not been realized until now because it is difficult to simply apply the head arrangement method for ordinary cylinders.

(Problem to be Solved by the Invention) Therefore, recording and reproducing audio signals in VH8-C movies using small cylinders had no choice but to use linear audio tracks, but even if the tape speed was slow, variations in tape speed ( There was a problem in that the sound quality deteriorated significantly due to large amounts of wow and flutter (wow and flutter) ◎ Therefore, this invention was developed to improve the sound quality by recording multiple layers of video and audio signals in a camera-integrated VTR using a small cylinder. An object of the present invention is to provide a magnetic recording/reproducing device that can realize high quality.

[Structure of the Invention (Means for Solving the Problems)] This invention has four audio heads mounted on a small cylinder and four audio heads arranged at predetermined positions. This method determines the appropriate position of the audio head that traces the same track, and also provides an appropriate level difference between the video head and the audio head.

(Function) By the above means, depending on the step set between the video head and the audio head and the distance that the tape travels during the time from when the audio head traces until when the video head traces, both SP and EP modes are set. In this case, the relationship between the video track and the audio track can satisfy the above-mentioned conditions (1) to (3), and multilayer recording of video signals and audio signals is possible.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing the arrangement of heads within a cylinder in one embodiment of the present invention. 1 to 4 are video heads, which are attached to a rotating cylinder 9. Audio heads 5-8 are arranged between video heads 1-4. A and B shown on each head indicate the azimuth direction. The angle from the center of the cylinder 9 to the audio head closest to the video head is θ.

The positional relationship between the video head and audio head when tracing the same track is θSP [degrees] in SP mode, and θEP in EP mode.
If you are ahead by [degrees], θSP = 9 0
n 10 [degrees (n = 0, 1, 2,
-5) θCP= 90 m10 [degrees] (n -Q
, 1.2. -9) However, m−n must be an odd number.

Video and audio track deviation and SP in EP mode
Let L be the difference in deviation between the video and audio tracks in the SP mode. However, TEP is the track pitch in the SP mode (5
8μm), TEP is the track pitch in EP mode (19.3um), and since it is TSP-3TIEP, it is possible to use the old F of VH3 without increasing the track width of the head too much.
In order to satisfy 1ml, it is appropriate that L be within the following range.

Based on these conditions, the relationship between n and m and the range of θ are determined as follows.

rn-3n+1 (n=0, 1, 2) 0°≦θ≦6
7.5" Furthermore, the smallest value of n that will cause the head switching timing to be the same in SP mode and EP mode is 1. At this time, the positional relationship between the video head and audio head tracing the same track. becomes as follows.

θ5P-90n 10-90+θ (degrees) θEP-90 (3n+1) 101 360+θ (degrees) Next, the level difference between the video head and the audio head required from the recording pattern on the tape is determined.

FIG. 2 shows a recording pattern in SP mode, and FIG. 3 shows a recording pattern in EP mode. In the figure, 21 is an audio head, 22 is a video head, and 23 is a tape. Define each dimension with the following symbols.

Tv: Track width of video head, Ts: Track width of audio head, H: Step difference between video head and audio head (shown in Figure 4) A. Conditions in SP mode (Figure 2) After the video head traces Each θSP that the cylinder rotates until the audio head traces, and the distance x from the center of the video track to the edge of the audio track from the step H between the video and audio heads.

Find the conditional expression for y.

Therefore, ...(2) ...(3) B. Conditions in EP mode (Figure 3) The angle θEP of the cylinder rotation from when the video head traces until when the audio head traces, and the video and audio Based on the height difference H between the heads, the conditional expression for the width Z of the audio track included in the opposing video track is ≧16 if TS≧TEP. Comparing conditional expressions (1) and (5), θ is approximately Condition (1) becomes stricter when θ is larger than 22°, but considering the dimensions of the head base and cylinder, it is difficult to make θ smaller than 22° unless a double azimuth head is used.

Therefore, the conditions regarding θ and H when using a single 8 head can be summarized as follows.

22″≦θ≦67.5°...(7)
(8) From these, for example, if n-1 and θ-45°, the range of H is from 29 μm to 32 μm.

The conditions regarding the track width are, for example, if calculated as H-31 ± 1 μm, Tv range is 24 μm. Considering the variation in track width, TV-31 ± 1 μm.
If 5TS = 26±1 μm, the condition can be satisfied. The dimensions of the head installation at this time are as shown in Figure 4.

[Effects of the Invention] As described above, according to the present invention, even if a small cylinder is used, multilayer recording of video signals and audio signals is possible.
In particular, it is possible to provide a magnetic recording and reproducing device that achieves high quality audio in a small camera-integrated VTR.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of the arrangement of heads on a rotating cylinder of a magnetic recording/reproducing device according to the present invention; FIG. 2 is an explanatory diagram of a recording pattern in SP mode;
FIG. 3 is an explanatory diagram of a recording pattern in the EP mode, and FIG. 4 is an explanatory diagram of an example of head dimensions. 1~4,22.41...Video head, 5~8°21
．． 42...Audio head, 9,45...Rotating cylinder, 23...Tape, 43.44...Head base.

Claims (3)

[Claims] (1) When recording and playing video signals using two heads facing each other at 180 degrees, four video heads are mounted on a small cylinder with a diameter of (2/3) the cylinder diameter, and audio signals are recorded in multiple layers. Equipped with 4 audio heads for
A magnetic recording/reproducing device characterized in that the range of the central angle θ from the video head to the nearest audio head in the rotational direction is 22°≦θ≦67.5°. (2) The positional relationship between the video head and audio head when tracing the same track is that in normal mode, the audio head is 90n+θ (degrees) ahead of the video head, and in double speed mode, the audio head is 90(3n+1 degrees) ahead of the video head.
)+θ (degrees) (n=0, 1, 2). The magnetic recording/reproducing device according to claim 1. (3) The difference in level between the video head and the audio head is determined from (n+θ/90) TEP to (n+θ/
270 + 4/3) TEP - Range up to 16 μm (TEP
3. The magnetic recording/reproducing device according to claim 1, wherein the magnetic recording/reproducing device is arranged above the cylinder at a track pitch in the triple mode.