JPS6096969A - Video tape recorder - Google Patents

Abstract

PURPOSE:To control a tape shift speed and to obtain a easy-to-see reproducing picture by dividing the control pulse in frequency at the double speed for the ordinary reproduction at the time of high speed reproduction and by comparing the division results in phase with a pulse synchronized to the rotation of a rotation magnetic head. CONSTITUTION:A video tape recorder 1 is of a helical scanning system, and the signal is recorded on a magnetic tape wound to a supply reel 3. A pair of rotation magnetic heads 4a and 4b are arranged to a head drum 4 where the tape 2 passes, and the heads 4a and 4b are rotated at the prescribed period so that they can be touched slidably to the tape 2 alternately. A control head 8 is installed between the drum 4 and a capstan 6, the control pulse of the tape 2 is read and the pulse is added to a tape shift control device 10 together with the head switch pulse from a pulse generation equipment 9. The control pulse is divided in frequency at the double speed for the ordinary reproduction at the high speed reproduction at a frequency dividing circuit 13, and the division results are compared in phase with a pulse synchronized to the rotation of heads 4a and 4b, and the shift speed of the tape 2 is controlled with the device 10.

Description

TECHNICAL FIELD The present invention relates to a video tape recorder in which the running speed of a magnetic tape during special +4 playback can be controlled with high precision.

BACKGROUND ART The running control of the magnetic tape in a video tape recorder is very precise, and during normal playback, 4'll of control pulses recorded on the magnetic tape are read, and the tape running is controlled in synchronization with these control pulses. On the other hand, apart from fast-forwarding, in which the tape is fed at a speed 70 times faster than during raw playback, conventional tape drive systems The rotating magnetic head drive system was being driven with no relation to Vr. For this reason, quick motion images may not show movement at a uniform speed, or it may be difficult to distinguish between movements, and as a result, it is difficult to find the desired tape position.
There are drawbacks such as a strong sense of strangeness when looking at peaks and valleys recorded over a long period of time using armor time.

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks, and consists of frequency-dividing a control pulse at a speed ratio relative to normal reproduction during high-speed reproduction, and comparing the phase of the frequency division result with a pulse synchronized with the rotation of a rotating magnetic head. To provide a video tape recorder which is configured to control the tape feed speed, thereby controlling the magnetic tape feed speed with high precision even during high-speed playback such as picture search, and making it possible to obtain easy-to-see playback images. What is the purpose of doing?

In order to achieve this object, the present invention divides the frequency of a control pulse indicating the tape advance position read from the magnetic tape by a double speed ratio of the normal playback speed during playback, and synchronizes it with the rotation of the rotating magnetic head. A frequency divider circuit whose frequency division operation is reset by the pulse generated by the frequency divider, an integration circuit which integrates the output of the frequency divider circuit, and a control circuit which controls the feeding speed of the magnetic tape according to the integrated output of the integration circuit? The structure [7] is a weak line.

According to the present invention, a control pulse indicating a tape feed position recorded on a magnetic tape is frequency-divided by the proportional speed ratio to the normal reproduction speed σb during high-speed reproduction of the magnetic tape, and this frequency-divided output is applied to the rotating magnetic head. By comparing the phase with the pulse synchronized with the rotation, the tape feeding speed during high-floor playback can be reduced to 1 l.
Since the ilJ 1illll+lq configuration prevents fluctuations in tape feeding speed even when the magnetic tape is being fed at . It is possible to perform 4JT recording of one motion image, which allows you to accurately find the desired tape position even in moving images, and to shorten long-time recordings without causing any discomfort. It has excellent effects such as being able to see far away in a short amount of time.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figures 01B/-2 are schematic circuit diagrams each showing an embodiment of a video recorder according to the present invention. FIGS. 3(A) to 3(G) 11: are signal waveform diagrams for explaining the operation of each part of the video tape recorder shown in FIG. 1. FIG.

In FIG. 1, the video tape recorder/ is configured to record signals on a magnetic tape 2 using a helical scan method, and the magnetic tape 2 wound around a supply reel 3 is wound over a predetermined angle range in a head drum trap. Next up is Pinch Roller! It is taken up by the take-up reel 7 between the and the cab stan. Inside the head drum, a pair of rotating magnetic heads a and b alternately record magnetic tape and 2VC.
Like attaching 1. ? (Rotates at a frequency of 7 Hz. Also, a control head l is provided at an intermediate position between the head drum and the cab stand 6 to read the control pulses recorded on the control track of the magnetic tape λ. It is connected to a tape feed control device io along with a pulse generator 9 and the like that outputs head switching pulses in synchronization with the rotation of the tape controller io.

The tape feed control device 10 is the above-mentioned control head!
and controls the rotational speed of the take-up reel 70 during raised bed playback based on the pulse generator signal,
The rotational speed of the motor 7a directly connected to the take-up reel 7 is controlled in accordance with the control pressure obtained by superimposing the error voltage from the tape feed control device O on the constant voltage supplied from the terminal 20. Ru.

This tape feed control device tO+i, a human power amplifier circuit connected to the pulse generator d and the control head r
2, and the output of the human power amplifier circuit //, /2 is
The signal is supplied to a clock input terminal and a reset input terminal of a frequency divider circuit 13 each consisting of a binary counter. In the case of this embodiment, since the intention is to control the tape speed in r times speed playback during picture search, as shown in FIG.
Of the λ frequency dividing output terminals QI to 212 frequency dividing output terminals Q12 of the frequency dividing circuit 13, an integrating circuit /g is connected to the Q4 output terminal which outputs the clock frequency divided by 16. The integrator circuit ll/ consists of a transistor Tr1 and a capacitor C connected between its base and collector, and a transistor Tr2, which is turned on by a search signal during high-floor playback, is connected between the base of the transistor TrI and the Q4 output terminal. It is. Integral circuit/g Ic 11, jill (,
An output amplifier circuit 15 as one circuit is connected, and the transmission speed of the reel motor 7a is controlled in accordance with the error 4 pressure which is the output of this output amplifier circuit.

Here, the Q of the frequency divider circuit/3 when f times the speed of 11 is generated.

When focusing on Q4 output Itako, when 76 control pulses supplied to the clock input terminal are counted, a signal having a pulse width equal to control pulses/A is output from the Q4 output terminal.

However, as shown in FIG. 3(A) or 3, in reality, when one control pulse is counted, the head cutting signal shown in FIG. 3(F) that is supplied to the reset input terminal Since the frequency divider circuit 13 is reset by the negative pulse, the output pulse width of the Q4 output terminal is
As shown in the figure, it will be very short. In other words,
The output of the Q4 output terminal represents the speed deviation of the double-speed tape feeding speed when compared with the head resetting pulse as a reference.The larger the speed deviation, the larger the output pulse width of the q4 output terminal.

Therefore, the output pulse of the Q4 output terminal is integrated by the next-stage integrating circuit/uvc, and an error voltage having a peak value corresponding to the output pulse width is generated at the capacitor C as shown in FIG. It appears as a terminal voltage.

After this error voltage is amplified by the output amplifier circuit 1, it is superimposed on the constant voltage supplied from the terminal 20, and a control voltage for controlling the rotational speed is supplied to the reel motor 7a. Therefore, for example, the larger the output pulse width of the Q4 output terminal of the frequency divider circuit /3, the more the rotational speed of the reel motor 7a exceeds the normal 1x playback speed. The rotation of the reel motor 7a is suppressed by the control voltage. Also, if the output pulse width of the Q output terminal is small, the error voltage is also small,
When the rotation restriction on the reel motor 7a is relaxed and the tape feeding speed exactly matches the t times speed, the error voltage is also made zero.

As explained above, the tape recorder/
According to, the tape feed position jl recorded on the magnetic tape λ
By frequency-dividing the control pulse shown by the double speed ratio to the normal playback speed during high-speed playback of the magnetic tagco, and comparing the phase of this frequency-divided output with the pulse synchronized with the rotation of the rotating magnetic heads a and 41b, the control pulse during high-speed playback is Since the tape feed speed is controlled, even when the magnetic tape λ is fed at high speed to find the part you want to see, such as during picture search, fluctuations in the tape feed speed are prevented and the speed remains constant during high-speed playback. It is possible to playback quick motion images, which allows you to accurately locate the desired tape position even with a single moving image, and allows you to play back long-time recorded content in a short time without causing any discomfort. You can see it from a distance.

[Brief explanation of the drawing]

1 and 2 are a schematic circuit groove bottom diagram and a main part circuit diagram showing an embodiment of the video tape recorder of the present invention, and FIG.
Figures (Page 1) are signal waveform diagrams for explaining the operation of each part of the video tape recorder shown in Figure 1. /...video tape recorder, co...magnetic tape,
4ta, 4tb... Rotating magnetic head, 7a... Reel motor, ♂... Control head, Ri... Pulse generation? 5, io...tape feed control device, /3.
...Branch circuit, /l...Integrator circuit, /, D...Output circuit 〇Patent applicant Nippon Tonkei Home Electronics Co., Ltd.7. Yi

Claims (1)

[Claims] Frequency division in which the control pulse indicating the tape feed position read from the magnetic tape is divided by the speed ratio of the normal playback speed of 1 m during playback, and the frequency division operation is reset by a pulse synchronized with the rotation of the rotating magnetic head. 1. A video tape recorder comprising: a circuit; an integrating circuit for integrating the output of the frequency dividing circuit; and a control circuit for controlling the feeding speed of a magnetic tape in accordance with the integrated output of the integrating circuit.