JPS61239455A - Video tape recorder - Google Patents

Abstract

PURPOSE:To eliminate the inherent vibration and revolving variance of a head cylinder by rotating the head cylinder at all times with the revolving phase exactly equal to that of a recording mode. CONSTITUTION:The standard of a comparator 14 is changed according to a using head R or L and R' or L' respectively. The comparator 14 is reset by a waveform 52 through a reverse amplifier 13 and at the same time compares a charging waveform 53 with the standard of a signal 62 and then delivers an output 54. The waveform of the output 54 is recorded on a tape in the form of a waveform 55 by a recording amplifier 15. In other words, the recording waveform of a control signal is recorded with variation of the width between the rise and the fall according to the areas recorded by the head R or R'.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a head cylinder equipped with two video heads by wrapping 2,700 times of magnetic tape around a head cylinder equipped with four video heads arranged at equal intervals. On the other hand, the present invention relates to a video tape recorder that realizes the same track pattern as a video tape recorder in which magnetic tape is wound 180 degrees and its two video heads are used alternately.

BACKGROUND OF THE INVENTION In recent years, home video tape recorders have become increasingly compact, and the diameter of the rotary head cylinder has been reduced to allow the same track pattern as with conventional cylinder diameters.

A conventional video tape recorder using a small cylinder will be described below with reference to the drawings.

FIG. 3 shows a head cylinder and tape track pattern using a conventional small cylinder, and FIG. 4 is a diagram showing signals for switching each head at this time. In Fig. 3 (a), in the case of a small cylinder, the tape 1 is wound around the cylinder 2 in a 2,700 degree spiral, and the four video heads R2L, R', L/ are placed at positions shifted by 90 degrees. ,L.

They are arranged in the order of R/ and Ll. Furthermore, head R and R
/, L and Ll have the same azimuth angle, and the head R
and L have different azimuth angles. Of these four heads, the one in contact with the tape is sequentially and selectively used to record on the tape, so the tape track pattern is R, L, R/, as shown in Figure 3 (b). It is recorded at the beginning of L'. In Fig. 3 (b), R, L, R', and L' indicate the recording trajectories recorded by R, L, FLI, and Ll, respectively. , a signal that tells which head to use.
These signals A and B.

Heads R and L during high level periods of C and D, respectively.

)1/, i, / to enable use of heads corresponding to each azimuth. That is, the above A and B.

The signals C and D are created, for example, by creating a signal G indicating the rotational phase of the head H using the rotational phase detection device 3 and dividing this signal G into four parts. Further, during reproduction, the signals A, B, and C are synchronized in phase with the signal G from the rotational phase detection device 3.
, D signals are created, and by using this switching signal, each output of the heads R2L, R', and Ll is selectively taken out, thereby obtaining a continuous video signal.

In FIG. 4, F is a control signal recorded for servo use during reproduction in synchronization with the head selection signals A and C during recording. E is a control signal during reproduction, and the head corresponding to the recording azimuth runs according to this control signal.

In this way, a tape track pattern is realized in which R azimuth and L azimuth are alternately recorded in the same way as when recording with two heads.

Problems to be Solved by the Invention However, with only the above configuration, during playback, R azimuth tracks and L azimuth tracks can be distinguished by control signals, but tracks written with a large R head and tracks written with an R' head cannot be distinguished. , cannot be distinguished because the patterns are exactly the same. When extracting a signal from a recorded track and reproducing it, considering only the reproduced signal, R
and R' have the same azimuth, so there is no difference, but
When a track recorded with the R head is played back with the R' head, the rotational phase of the head cylinder is 18 during recording and playback.
Flip 0°. If the rotational phase of the head cylinder is the same during recording and playback, the inherent vibrations and rotational unevenness that the head cylinder has when rotating are canceled out, but if the rotational phase is shifted by 1800 degrees, the inherent vibration and rotational unevenness of the head cylinder will be significantly reduced. This has the problem that the image is greatly emphasized.

In view of the above-mentioned problems, the present invention provides a video tape recorder in which the same head is used during playback as during recording, thereby canceling out vibrations and uneven rotation of the head cylinder.

Means for Solving the Problems In order to solve the above-mentioned problems, the video tape recorder of the present invention has the following features:
The recording duty of the control signal for azimuth and L azimuth discrimination is changed and recorded every 1800 rotations of the head cylinder, and during playback, tracking control is performed using the rising pulse of the reproduction control signal, and the falling pulse is divided.
A means for determining the current phase of the tape with respect to the rotational phase of the head cylinder, and a means for adjusting the phase to the same as the recording phase when the head phase during playback is different from the recording track. It is something that

According to the present invention, with the above-described configuration, if the R head is used when recording, the R head is always running during reproduction! ,
, R/ head is prevented from playing, and the head cylinder can always be rotated at exactly the same rotational phase as when recording, and as a result, the inherent vibration and rotational unevenness of the head cylinder can be canceled out. It is something that can be done.

Embodiments Hereinafter, video tape recorders according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a recording head discrimination device for a video tape recorder according to an embodiment of the present invention. In FIG. 1, 11 is an amplifier for the recording control signal 51 applied to the terminal 24, 12 is a differentiation circuit, and 13 is an inversion amplifier for only the rising signal of the waveform differentiated by the differentiation circuit 12. , 14 is a comparator constituting a monomulti which is reset by the output signal of the inverting amplifier 13 and repeatedly charged. 23 is an OR gate which receives the input signals 63° and 64 of the input terminals 26 and 26. , 64 are both Hl
By switching the reference voltage of the comparator 14 between when it is gh and when it is not, the amount of delay, that is, the duty, of the mono-multiple circuit constituted by the comparator 14 is switched. 1
Reference numeral 6 denotes an amplifier for recording the output signal 54 of the comparator 14 on a tape by the control head 16.

17 is an amplifier after reproducing the control signal during reproduction, 18 is a waveform shaping amplifier for the rising side signal of the amplified waveform of the reproduction control signal 67, and 19 is a waveform shaping amplifier for the falling side signal. In the waveform shaping amplifier 2o, the falling side shaping output 6e of the waveform shaping amplifier 19 is applied to the clock input terminal CK, and the head switching signal 60 for the L' head applied to the terminal 27 is applied to the D input terminal. 21 is an inverting amplifier for the Q output of the D-type flip-flop 2o, and 22 is a relative position between the tape and the head with reference to the rising pulse of the reproduction control signal.
This is a conventionally known tracking control circuit for controlling the phase. That is, the tape is controlled so that the signal G indicating the rotational phase of the head cylinder and the reproduction control signal E match in phase.

The operation of the head discriminating circuit constituted by the circuit as described above will be described below with reference to FIG. 1, #g2. FIG. 2 is a timing diagram when the configuration shown in FIG. 1 is operated.

First, the recording waveform of the control signal is originally 61 in Figure 2.
Recording is performed so that the control signal rises at the beginning of recording by the R azimuth heads (R head and R' head). Since the rising portion of the control signal is used to control the tape feed phase during playback, the control signal is differentiated by a differentiating circuit 12 so as not to change the phase of the rising portion to obtain a waveform 62 in FIG. 2. On the other hand, in order to distinguish between the portion recorded by the R and L heads and the portion recorded by the R' and L' heads, the head switching signals 63 and 64 for using the R and L heads are OR gated. 23, and as shown in 62 in FIG.
change the reference voltage of That is, the head used is R
Alternatively, the reference of the comparator 14 is changed depending on whether the head is L or R' or L'. The comparator 14 is a comparator between the reference signal 62 and the waveform 53 in FIG. 2, which is reset and charged by the inverting amplifier 13 with the waveform 52 in FIG. Roll 64.

The waveform of the output 54 is transmitted to the recording amplifier 16 and is shown at 66 in FIG.
Record the waveform on tape. In other words, the recording waveform of the control signal is recorded with a width varying from the rising edge to the falling edge depending on whether the portion recorded by the R head or the portion recorded by the R' head.

Next, during playback, the playback control signal is transmitted to the amplifier 17.
The waveform 57 in FIG. 2 is obtained.

Add this to amplifiers 18 and 19, respectively, on the upper side.

Obtain the lower signal 58.59. Signal 68 enters phase control circuit 22 which drives the tape and controls the phase of tape travel. On the other hand, the signal 59 is input to the D type flip 70 knob 2o together with the head switching signal 60 for the L' head. L'
The head switching signal eo for the head is 55 in Fig. 2 during recording.
During reproduction, the pulse 59 in FIG. 2 is not in the Htgh section of the waveform 60 in FIG. 2 during playback.

Therefore, if there is no pulse 69 in FIG. 2 in the High section of the waveform 60 in FIG. 2, the output terminal of the inverting amplifier 21 will not become Low, so it will not affect the control circuit 22. However, when the R' head reproduces a track recorded in the R, the head switching signal 6o for the L/head comes to the phase 60' in FIG. At this time, since the recording signal duty of the control signal is changed, during reproduction, the High section of the signal 60' in FIG.
The Q output of the D-type flip-flop 2o, which tends to overlap with the pulse 59 in the figure, is a as shown in 61' in Figure 2.
Output i gh. At this time, the inverting amplifier 21 is set to Low.
Therefore, the control signal 68 input to the control circuit 22 is lost. control signal 5
If 8 is lost, the tape running phase cannot be controlled.
The tape running phase is disturbed.

Then, the tape phase is disturbed once and then returns to the normal phase. When the tape phase becomes a normal phase, it becomes a stable region that does not affect the control circuit 22 as described above.

Effects of the Invention As described above, the present invention records the control signal recording waveforms indicative of the rotational phases of two rotary heads having the same azimuth angle by changing the duty of each other, reproduces the control signal at the time of reproduction, and reproduces the control signal. By detecting the duty of the control signal, it is possible to control the two rotating heads during playback and the playback control signal so that they have the same phase relationship as during recording. The rotational phase of the head can be made the same during recording and playback, and vibrations and rotational irregularities inherent to the head cylinder can be canceled out.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the video tape recorder of the present invention, FIG. 2 is a timing diagram of the same embodiment, FIG. FIG. 4B is a diagram of the track pattern of the tape according to this, and FIG. 4 is a timing diagram of each head switching signal, etc. for the head cylinder incorporating the present invention. DESCRIPTION OF SYMBOLS 1... Rotating head cylinder, 2... Tape, 3... Rotating phase detection device, 12...
...Differentiating circuit, 13...Inverting amplifier, 14...
... Comparator, 16 ... Control recording amplifier, 16 ... Control head for recording and reproduction, 18 ... Rising side shaping amplifier, 19
...Fall side shaping inversion amplifier, 2o...
・D type flip 70 knob, 22... Tape running phase control circuit, 24... Control signal input terminal, 26... Head switching signal input terminal for R head, 26... ...Head switching signal input terminal for L head, 27...Head switching signal input terminal for L' head. Name of agent: Patent attorney Satoshi Nakao (Male) and 1 other person Figure 2 61'

Claims (1)

[Claims] first and second magnetic heads having a first head azimuth angle; and third and fourth magnetic heads having a second azimuth angle different from the first azimuth angle; The second and fourth magnetic heads are arranged on a head cylinder at equal intervals in that order, and a magnetic tape is wound around the head cylinder in a spiral shape and runs, and information signals are transmitted by sequentially selecting and using the magnetic heads. A signal indicating the rotational phase of the first and second magnetic heads is recorded on the magnetic tape as a control signal, and the control signal is a signal indicating the rotational phase of the first and second magnetic heads. A video tape recorder characterized in that the duty is different depending on whether the rotation phase is indicated.