JPS6025007A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a noise due to the elongation and contraction of a tape by providing another heat before the 1st heat which records and reproduces a sound signal, and arranging those two heads so that the 1st heat rushes to the tape in the remaining period of the waving of the tape due to the rushing of the other head. CONSTITUTION:Heads HA1 and HA2 are provided a specific size behind heads HV1 and HV2. Further, steps (h) which are about one pitch or more than of a slanting track on the tape T so that the heads HA1 and HA2 are on the supply side of the tape T. Consequently, the tape T elongates firstly owing to the rushing of the heads HV1 and HV2, but oscillates at the same time and the heads HA1 and HA2 rush while the oscillation remains; the heads HV1 and HV2 contact the tape T without striking the tape T and perform recording or reproduction without any elongation of the tape T. Therefore, no noise is generated even in the reproduction by another VTR of similar constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus that has a helical scan type head device and performs FM modulation on audio signals to record and reproduce them on diagonal tracks on a tape.

W-Scenery Technology and Its Problems The applicant of the present application previously proposed a new video tape recorder (VTR) with improved audio signal characteristics.

That is, as shown in FIG. 1, two rotating magnetic heads I
(vl and HV2 are installed with an angular spacing of approximately 180°, and two rotating magnetic heads HAI and HA2 are installed adjacent to the heads HV1 and HV2, respectively, with an angular spacing of approximately 180°.
Can be installed with an angular spacing of 0°. Further, the heads H7u and HA2 are installed on the rotational direction X side from the heads Hv and HV2 so as to precede the heads Hv and HV2, respectively. Further, the magnetic tape T is run in the Y direction obliquely along the tape guide drum (4) over an angular range of about 180''.

As shown in FIG. 2, the azimuth angles (inclination angles relative to the direction perpendicular to the scanning direction , θV2# is 7°. Also, the gap between heads HA1 and I (82).

Azimuth angles θA1 and θA2 of gAl and gA2 are made different from each other. Generally, the crosstalk ratio due to azimuth loss can be expressed as λ, where Cx is the crosstalk, λ is the recording wavelength of the signal, W is the track width, and θ is the relative azimuth angle. Gap g/u of head HAt and H^2
The azimuth angles θA1 and θA2 of gA2 are ・Head H
In the relationship between A1 and HA2, HAl and Hvt, and HA2 and HV2, for example, if tanθ in equation 11 is 1
The above settings are made so that almost no crosstalk occurs between them. For example, θAi#
-45°, θA2 # + 45°. Also, gaps gA1 and gA between these heads HA1 and HA2
2 is made wider than the widths of the gaps gvz and gv2 of the heads Hyz and HV2. For example, head Hvl
and the width of the gap gVi and gv2 of HV2 is 0.3μ
In contrast, the widths of the gaps gAx and gA2 between the heads HA1 and HA2 are approximately 1.5 to 2.0 μm.

Normally, in magnetic recording, it is possible to record on the magnetic layer of a magnetic tape to a depth that is approximately half the gap width of the magnetic head. Furthermore, when considering reproduction, the longer the recording wavelength, the deeper recording can be made in the magnetic layer. The width of gaps gΔ1 and gA2 of heads HAl and HA2 is
The gap between vz and HV2 is made wider than gvz and gv2 because the signals recorded by heads HAI and HA2 are recorded deeper into the magnetic layer of the magnetic tape than the signals recorded by heads HVi and HV2. be.

In addition, the heads HVI, HV2.1 (At, HA2, for example, are rotated once in one frame.
A1, Hvt and heads HA2, HV2 are configured to alternately scan the magnetic tape T every field. At this time, the heads HA1 and HA2 each have a head Hv
The magnetic tape T is scanned prior to Z and HV2. .

When recording in this device, heads Hv1 and HV2
The normal method low-pass conversion color signal CI) and modulated luminance signal y
A composite signal of ph is provided. Further, the heads HAt and HA2 are supplied with a composite signal of modulated audio signals ALFH and ARPM obtained by FM modulating the audio signal in a predetermined band, respectively. Therefore, as shown in FIG. 3, on the magnetic tape T, a recording trunk T1 by the heads HAl and Hvt and a recording track T2 by the heads HA2 and H1/2 are sequentially formed alternately for each field. The recording trunks T1 and T2 contain a composite signal of the low frequency conversion color signal CD and the modulated luminance signal YFM, and the modulated audio No. 46 ALFM.
, Al composite signals are recorded in an overlapping manner at different recording azimuths. Immediately, in Fig. 4 A, go to head H 1 and H.
This figure shows the recording trunk T1 by Vl, but when observing this cross section, as in Figure B, first, the head IAI modulates the audio signals ALF11 and ARPH.
The synthesized signal is recorded deeply on the magnetic Jm (Ta) of the magnetic tape T, and then the head Hvi converts the low frequency conversion color signal CD and the variable KH! A composite signal of the luminance signal YFM is shallowly recorded on the magnetic layer (Ta). The same applies to trunk T2. In FIG. 4B, (Tb) is the base.

Also, during playback, 1 to head H, Hvl and head H
A2 and HV2 are arranged to scan recording trunks T1 and T2, respectively. Therefore, heads HAt and HA2
Then, modulated audio signals A are obtained from recording tracks T1 and T2, respectively.
A composite signal of LFH% ARpn is reproduced. Furthermore, the heads HV1 and HV2 have recording tracks T1 and T, respectively.
2, a composite signal of the low frequency converted color signal CD and the modulated luminance signal YFt+ is reproduced.

FIG. 5 shows an example of a specific circuit configuration. In the figure, (100
V) is a video signal recording circuit, and terminal (11)
is supplied with a video signal SV. This video signal Sv
is supplied to a low-pass filter (12) to obtain a luminance signal Y, which is supplied to an FM modulator (14) through a pre-emphasis circuit (13). FM modulator (14)
In this example, the luminance signal Y is FM-modulated so that the white peak is 4.8 MHz and the sync tip is 3.6 M1lz, and a modulated luminance signal yps is obtained. This modulated luminance signal YFM is band-limited through a bypass filter (15), further amplified by an amplifier (16), and then
It is supplied to a combiner (17).

Further, the video signal Sv supplied to the terminal (11) is supplied to a bandpass filter (18) to obtain a color signal C, which is supplied to a frequency converter (19). This frequency converter (19) is supplied with a conversion signal from an oscillation circuit (20), and the carrier frequency is, for example, 688 k 11
A low frequency conversion color signal CD of z is obtained.

This low-pass conversion color signal CI is a low-pass filter (21)
After being band-limited by the amplifier (22) and further amplified by the amplifier (22), the signal is supplied to the combiner (17).

The composite signal of the modulated luminance signal Y FM and the low frequency conversion color signal CD obtained from the synthesizer (17) is connected to the selector switch (23).
and head HV1 through the rotary transformer (24).
It is also supplied to the head 1]v2 through the changeover switch (25) and the rotary lance (26). The changeover switches (23) and (25) are connected to the R side during recording, and are connected to the P side during playback.

(100A) is an audio signal recording circuit, and the terminal (
30L) and (30R) are supplied with the first audio signal (left signal for stereo, main signal for dual audio) AL and second audio signal (right signal for stereo, sub signal for dual audio) AR. .

The first audio signal AL is supplied from a terminal (30L) to an FM modulator (32L) through a compression circuit 11!3 (31L) constituting a noise reduction circuit. In this FM modulator (32L), the first audio signal AL
is FM-modulated, for example, with a carrier frequency of 1.35M1lz and a frequency deviation of ±75KHz, and the modulated audio signal ALF
H is obtained. This modulated audio signal ALFRL is passed through a low-pass filter or a node noise filter (33L) for removing disturbance harmonics and is supplied to a ζ synthesizer (34). Further, the second audio signal AR is supplied from the terminal (30R) to the FM modulator (32R) through the compression circuit (31R) that constitutes the noise reduction circuit. At number 111, the first audio signal AR is F'M modulated, for example, with a carrier frequency of 1.50 Ml1z and a frequency deviation of ±75 kHz to obtain a single modulated audio signal ARFM. No.A
RF M has a low-pass filter for removing harmonics)
The synthesizer (3
4).

In the synthesizer (34), the modulated audio signals ALFN, A
RFM is synthesized. This composite signal is then sent to the amplifier (
36), and the signal from this amplifier (3, 6) is amplified by a changeover switch (39) and a rotary transformer (40).
This signal is supplied to the head HA1 through the changeover switch (41) and the rotary transformer (42).

The changeover switches (39) and (41) are set to R during recording.
When playing, it is connected to the P side.

When recording, selector switches (23), (25), (39)
(41) are respectively switched to the P side, so as mentioned above, the head 1 (VL and HV2 has a low frequency conversion color signal C,
) and the Y group of variable 111i1 luminance signals is provided. Moreover, the modulated audio signal A is sent to the heads HAt and HA2.
A combined signal or cancellation signal of LFM and ARPH is supplied. Therefore, as shown in FIG.
A recording trunk T1 by t and a recording track T2 by heads HA2 and Hv2 are sequentially formed. '' (200V) is 6 circuits of video signal reproduction thread.

As described above, the low-frequency conversion color signal CD & Luminance signal Y
The combined signal of the group is supplied to the °ζ switch circuit (51) through an amplifier (501). Further, as described above, the composite signal of the low frequency converted color signal C[) and the modulated luminance signal YFM reproduced from the recording track T2 at the throat Hv2 is supplied to the Sui-Sochi circuit (51) through the amplifier (502). Ru. The sui-nochi circuit (51) has a terminal (51a)
A switching control signal Sa obtained according to the rotational position of the head I (vz and HV2) is supplied to Uli, and the switching is controlled.Then, from this switch circuit (51),
Composite signals re-tempered by heads Hv1 and HV2 are obtained alternately for each field.

The synthesized signal obtained from this switch circuit (51) is supplied to a bypass filter (52), and the Hensha 14 luminance signal Y song is obtained from this no.lamda. This modulated luminance signal YFM is supplied to the FM demodulator (54) through the limiting circuit (53).
4), the luminance signal Y is obtained. This luminance signal Y is supplied to the 'ζ combiner (56) through a de-emphasis circuit (55).

Further, the composite signal obtained from the switch circuit (51) is supplied to a low-pass filter (57), and a low-pass converted color signal C8 is obtained from this low-pass filter (57). This low frequency converted color signal C, is supplied to a frequency converter (58). This frequency converter (58) is supplied with a conversion signal from an AFPC circuit (automatic frequency and phase control circuit) (59), and the low frequency converted color signal C, has a carrier frequency of, for example, 3.
．． 58 MIIz color signal Ci is converted. This color signal C
a synthesizer (56) through a bandpass filter (60);
supplied to

In the synthesizer (56), the luminance signal Y and the color signal C are synthesized, and a video signal Sv is obtained at the output terminal (61).

(200A) is a circuit for reproducing audio signals. As described above, the modulated audio signals ALFM, ARP! are reproduced by the head 1181 from the recording trunk TI. The composite signal of 1 is passed through an amplifier (70+), and the center frequency is approximately 1.35.
The signal is supplied to a band-pass filter (71Lz) whose center frequency is approximately 1.50 Ml1z, and is also supplied to a band-pass filter ('71Rt) whose center frequency is approximately 1.50 Ml1z. A modulated audio signal ALFM is obtained from the bandpass filter (71Lt), which is supplied to an FM demodulator (73L1) through a limiter circuit (72Lz). This FM
A first audio signal AL is obtained from the demodulator (73L1), and is supplied to one terminal of the switch circuit (74L). Further, a modulated audio signal ARFM is obtained from the bandpass filter (71R1), and this is transmitted to the limiter circuit (71R1).
2R1) to the FM demodulator (73R1). This FM? The second audio signal A is sent from the summer controller (73Rt).
, which is supplied to one terminal of the switch circuit (74R).

In addition, as described above, from the recording track T2, the head HA
The synthesized signal of the modulated audio signal ALFHs ARFM reproduced in step 2 is passed through an amplifier (702) to a bandpass filter (71L) with a center frequency of approximately 1.35MHz.
2), and the center frequency is approximately 1,50M.
Hz bandpass filter (71R2). A modulated audio signal ALFM is obtained from the bandpass filter (71L2'), and this is transmitted to the limiter circuit (72L2').
? ) is supplied to the FMf summer frequency generator (73L2). This FM demodulator ('/3L2) outputs the first audio signal A.
L is obtained and supplied to the other terminal of the switch circuit (74L). In addition, a band pass filter (71R2
), a modulated audio signal ARFM is obtained, which is passed through a limiter circuit (72R2) to a ζFM demodulator (73R2).
supplied to From this FM demodulator (73R2), the second
Audio signal AR is obtained and this is the switch circuit (74R)
is supplied to the other terminal of

A switching control signal Sa is supplied from a terminal (74La) to the switch circuit (74L), and the switching is controlled according to the rotational positions of the heads HAI and I-I A2. That is, during one field period when the head HΔ1 is scanning the recording trunk T1, the terminal is switched to one terminal, and during the other one field period when the head HA2 is scanning the recording trunk T2, the terminal is switched to the other terminal. Therefore, from this switch circuit (741), the FM demodulator (73L)
The first audio signals AL obtained from t) and (73L2) are obtained alternately for each field, and are supplied to an output terminal (76L) through an expander (75L) constituting a noise reduction circuit.

Further, the switching control signal Sa is also supplied to the switch circuit (74R) from the terminal (74Ra), and the switch circuit (74L)
), the switching is controlled in the same way as Therefore, from this switch circuit (74R), the second audio signal AR obtained from the FM demodulators (73R1) and (73R2) is obtained alternately for each field, and this is transmitted to the expander (75R) that constitutes the noise reduction circuit. ) through the output terminal (76R
).

However, in the above-mentioned device, head I (8t, HA2
When the head contacts (rushes into) the tape T for the first time, the tape T stretches due to the collision of the head. If recording is performed in this state, when each diagonal trunk is viewed consecutively, the elongated portion shown in Figure 6A will become shorter when the tape T returns to its original position, and the recording of this portion will become shorter. As shown in FIG. 6B, the recording signal becomes denser and the frequency of the recording signal becomes higher.

This phenomenon is not a problem when recording and reproducing on the same VTR because expansion and contraction occurs in almost the same state, but when recording and playing on the same VTR,
When playback is performed with TR, the position of expansion and contraction changes due to the deviation of the entry points of heads HA1 and HA2, and the above-mentioned frequency increases, or conversely, the correctly recorded portion is expanded, resulting in a decrease in frequency, etc. As shown in Figure C, noise occurs in the FM demodulation output.) And this noise is 50 or 601 degrees depending on the rotation of head HA1°HA2.
It has a periodicity of 1z, and this quotient harmonic component becomes especially harsh in the range of about 1kllz or less.

Note that in conventional recording of only video signals, this portion is outside the effective screen, so no problem occurs.

OBJECTS OF THE INVENTION In view of these points, the present invention provides a simple structure that prevents noise from occurring due to expansion and contraction of the tape.

Summary of the Invention The present invention has a helical scan type head device;
In a recording and reproducing apparatus that performs FM modulation on an audio signal and records and reproduces it on diagonal tracks on a tape, another head is provided preceding the head on which the audio signal is recorded and reproduced, and at least the head on which the audio signal is recorded and reproduced is provided. A recording/reproducing apparatus characterized in that the above-mentioned - and other heads are arranged so that the above-mentioned - and other heads are arranged so that the above-mentioned - and the other heads plunge into the tape during a residual period of vibration caused by the entry of the preceding other heads, According to this method, the structure is simple and no noise is generated due to expansion and contraction of the tape.

In FIG. 7 of the embodiment, the head HAX and HA2 are the heads Hvt.

After HV2, e.g. 0.5-1 m5 at normal rotation speed
Provided at the position where the ec is to be placed behind. Furthermore, as shown in Figure 8, tape T is placed between heads HAI and Hvx, and between HA2 and HV2.
A step of about one pitch or more in the upper diagonal track is provided so that the heads HAt and HA2 are on the tape T supply side.

As a result, the head Hvx is attached to the tape T first.

The collision of HV2 causes elongation, but at the same time the tape T vibrates, and while this vibration remains, head HA1. This head HA1. HA2 moves the tape T without colliding with the tape T.
The head HA11 H^2 records and reproduces the tape T without elongation.

Therefore, recording and reproduction are performed without expanding or contracting the tape T, and there is no risk of noise occurring even if reproduction is performed with another VTR having the same configuration.

Furthermore, when performing deep recording as described above, by providing the step kl as described above, recording is first performed by heads HAI and HA2 on tape T, and then recording is performed by heads HVi' and HV2. It becomes like this.

Note that the step is 1. to head H. HA2 may perform recording a plurality of tracks in advance. Further, in this case, by providing a step with an extra ten track pitches, the head HV1. which is formed wider than the head HAt+ HA2 during reproduction. HV2 no longer straddles three deep-recorded trunks, and noise due to crosstalk of deep-recorded signals can be minimized.

Furthermore, head HA1. Hvt and HA2. The spacing of HV2 is 0.5 to 1m5e at normal rotation speed as mentioned above.
c is optimal, which is, for example, 5.c with a rotation of 6011z.
This corresponds to an angular spacing of 4 to 10.8 degrees.

As a result of the simulation, an improvement in noise of about 3 (18) was confirmed.

Furthermore, when frequency multiplexing an FM audio signal between a luminance signal and a chroma signal and recording and reproducing it using a set of rotating heads, the same effect can be obtained by providing a ``ζ dummy head'' in front of the head. I can do it.

Effects of the Invention According to the present invention, it is possible to prevent noise caused by expansion and contraction of the tape from occurring with a simple configuration.

[Brief explanation of the drawing]

Figures 1 to 6 show the new VT proposed earlier by the applicant.
The diagrams for explaining R, FIGS. 7 and 8 are configuration diagrams of an example of the present invention. HAt and HA2 are recording and reproducing heads for FM audio signals;
Hvl and HV2 are other heads, r is a tape, and h is a step. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] It has a helical scan type head device, and the audio signal is F
In a recording and reproducing apparatus that performs M modulation and performs recording and reproducing on diagonal tracks on a tape, another head is provided preceding the head indicated by ``C1'' on which the audio signal is recorded and reproduced, and at least the preceding head on the tape is provided with another head. 1. A recording/reproducing apparatus characterized in that the above-mentioned - and other heads are arranged so that the above-mentioned - and the other heads enter the tape during a residual period of vibration caused by the entry of the other heads.