JPS5834683A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reproduce excellent still pictures in a short time, by switching the capstan motor from the normal speed rotation to the low speed rotation when the pose switch is switched from the running condition to the stopping condition. CONSTITUTION:When a pose switch P.SW is off, an electric power is supplied to a speed control circuit 1 through a transistor Q1 because the Q-output of a flip flop FF1 becomes low and the Q'-output of the FF1 becomes high, and a capstan motor CMo is controlled to the normal rotation by the control circuit 1. When the pose switch is switched from the off condition to the on condition, the speed control circuit 1 does not work because the transistor Q1 is turned off, and the operating condition of the capstan motor CMo is switched to the low speed rotation. When a drop-out pulse DOP which represents a lack of the reproduced signal from a magnetic tape is detected at a flip flop FF2 and the detected signal coincides with a prescribed phase (30Hz PG) of the drum rotation, the capstan motor CMo is stopped.

Description

[Detailed description of the invention] The present invention relates to a magnetic reproducing device capable of obtaining a static-1 image.

Conventionally, the so-called helical scan type scans a magnetic tape in a direction tilted with respect to the running direction of the magnetic tape using a rotating head, records a video signal on the magnetic tape, and extracts the video signal from the tape for playback. When obtaining a still image in a magnetic recording/reproducing apparatus, the tape is stopped and the rotary head repeatedly scans the same portion of the magnetic tape to obtain the still image. However, when the above-mentioned scanning is performed using a rotating head, since the adjacent video signals are also scanned, some gaps occur in the playback signal obtained from the rotating head, and the gaps appear as so-called noise par on the static playback screen. I end up. A good still image can be obtained by fixing the noise bar at the bottom of the playback screen or near the vertical synchronization signal.

A configuration conventionally used for the above purpose is shown below.

The configuration of sg1 is to detect a control signal recorded on the magnetic tape after the normal playback/quiet playback switch (hereinafter referred to as the pause switch) is switched to the still playback side, and detect the control signal. After a predetermined time delay, the capstan motor is configured to switch from rotation for normal playback running to rotation stop to obtain a still image.

The idea behind the above configuration is to adjust the delay time based on the time it takes for the magnetic tape to actually stop after the capstan motor is switched to a stop, but changes in the inertial mass due to tape load and temperature, etc. Therefore, it is necessary to change the delay time. .

As an improvement on the first proposal described above, there is a method in which the delay time described above is controlled by the amount of tape wound around the reel.

Furthermore, when the pause switch is turned on, the tape running speed is switched from the normal playback speed to a low speed, and when the noise bar and the vertical synchronization signal match, the capstan motor is stopped.

According to this idea K, the time from when the tape is switched from low-speed running to stopped until the tape actually stops being fed can be made sufficiently small, which has the advantage of not being affected by tape load, temperature, etc. . However, it takes several seconds from when the pause switch is turned on until the tape actually stops, depending on the timing between the pause switch being turned on and one frame of the playback signal, and the time it takes to obtain static playback is unstable. The reproduced images during that time were also unsightly.

The present invention provides an improved magnetic reproducing device in view of the above points.

Embodiments according to the present invention will be described below with reference to the drawings.

The fgI diagram shows an outline of control in an embodiment according to the present invention.

When the pause switch is switched from running to stopped during normal playback, a control signal is first detected from the recording tape. The capstan motor for moving the recording tape is switched from normal running rotation to low speed rotation when a control signal is detected. Next, play Eirin Signal Processor M
The capstan motor is stopped at the time when a pulse (hereinafter referred to as DOP) obtained from path A (B) and obtained by detecting a drop in the reproduced signal matches a pulse obtained from a predetermined phase of the co-rotating head.

The above control can be realized, for example, by the circuit shown in FIG. In the same figure, p@ is a switch that turns 0N10FF by a pose switching member (not shown), and is turned on when in a pose and turned off when in normal mode.・FF1. FF2 is a D type flip-flop. N1°N2 are inverters. Mo 1 is a 6-man team and gate. Ql-
Qs is an NPN) transistor.

Q4 is a PNP transistor. C@MO is the capsmage monitor set. ω is a speed control circuit for controlling the speed of the capstan motors according to the outputs of rotation detectors of the capstan motors C and MO (not shown). CTL is a pulse obtained from the reproduction output of a control signal recorded on a magnetic tape.

DOP is a dropout detection pulse. ! 0HzP
G is a pulse representing the rotational phase of the drum to which the rotary head is attached.

The operation of the embodiment having the above configuration will be explained with reference to the waveform diagram in FIG.

Now switch P・8 is turned OFF. 4 Waveform f in Figure 6, R input of flip-flop jF1 is H2Q
The output beam is Q, the output (C) is H,) transistor Q1 is ON, power is supplied to the speed control circuit α) NT, and the capstan motor C-Mo is controlled to the specified rotation speed for normal regeneration. . The output (g) of the controller AI is L, and the transistor Q5 is OFF. Both circuits C0NT switch their outputs between H and L to control the speed, and by changing the duty ratio of the △ pulse, the transistors Q2. The ON/OFF duty ratio of Q4 is changed to control the power supply to the capstan motor C@MO to control its speed.

In this embodiment, switching between activation and deactivation of the speed control circuit is carried out by energizing and de-energizing the speed control circuit power supply.
There is no problem in keeping the output at L.

At time t1, switch P@SW changes from OFF to ON.
, the D input of flip-flop FF1 becomes H, R
The input becomes L, but at time t2 when the CTL pulse is input to the C input, the Q and Q outputs maintain their outputs, and the capstan motor CIIMO is controlled to the normal reproduction speed. In this embodiment, a speed control circuit based on a pulse width control is used. At time t2, the 7-lip frog F4 inverts its output (@waveform (C)' in Figure 6), Ql turns OFF, speed control 1 becomes inactive, and transistor Q2 turns OFF and does not repeat ON and OFF. When the Q output of flip-flop FF1 changes from H to L, the ordinary power of flip-flop FF2 becomes L, but the output is not inverted until time t3. Therefore, its Q output (f) is H, and the waveform obtained by differentiating the 30 Hz P G (d) with a differentiating circuit consisting of a capacitor C9 and a resistor R appears at the output (g) of the analogue AI.

Therefore, the transistor Q2 is OFF, but the transistor Q5 is turned 0N10FF according to the output of the antagonist 1.
Repeating this, the base input (h) of the transistor Q4 becomes as shown in Fig. 6. When the waveform (h) is H, the transistor Q4 is OFF, and when it is L, the transistor Q4 is ON. From ON/OFP K, the capstan motor repeatedly stops feeding intermittently, and as a result, the tape can be run at a sufficiently low speed.Flip-flop F with DOP (e) as D input
F2 is triggered by the rise of 30Hz PG, and at time t5, when the D input (e) is H, the C input (d) changes from L to H, its output is inverted, and the Q output changes from H to L. Therefore, the low AI output (g) remains low even if the CR circuit repeats high and low, and the transistor Q3 becomes 0Fk1.
, transistor Q4 is also OFF and capstan motor Ca
Ma stops. In a normal magnetic recording/playback device, there is an oscillator that serves as a reference, and the phase difference between the oscillation signal and the CTL is kept constant, and the phase difference between the oscillation signal and the rotational phase detection pulse of the drum is kept constant, allowing tracking and compatibility. However, in this embodiment, the switch P is switched to ONL, and then the capstan motor CIIMO is switched from normal rotation to low speed rotation in synchronization with this CTL. Although the time from 11 to t2 varies by a maximum of 1/30 sec each time the SW is turned on, the time from t2 to 13 can be made to be approximately the same each time. Also, by changing the time constant of CR, t2
The time interval between t2 and tS is changed, and the time between t2 and tS can be adjusted to some extent.Also, as shown in FIG. By switching the C/MO from normal driving to low speed driving, an additional 12~13
It is possible to shorten the time between. The timing chart is shown in FIG. In FIG. 4, CaY~(
b7 corresponds to waveforms (a) to (hl) in FIG. 6, respectively,
M.M is formed by a predetermined time delay l1, for example, a mono multivibrator.

Next, in Figure @6, time t! From now on, switch p in Fig. 2
When @sw changes from ON to OFF, time t4) The flip-flop FFI becomes H, and the Q output becomes Ll.
The Q output (C) is turned on by transistor Q1 due to Hl, and the output (g) of A1 is always L, and the capstan motor C@M (l is rotated at a constant speed by the speed control circuit again, and is in the normal regeneration state. becomes.

In this embodiment, C of flip-flop) k)
C'['L pulse was used as input, but as mentioned above, CT
L, ): Ram's rotational phase detection pulse also maintains a constant phase difference with the reference oscillation signal, similar to CTL, so it is possible to use a 50Hz PG signal instead of the CI horn at the C input of flip-flop FF1. It is obvious that the effect will not change at all.

As described in detail above, according to the present invention, after the pause switch is set to ONL, when σL, By switching from playback speed to slow playback speed and further switching the capstan motor from slow rotation to stop when the dropout detection pulse coincides with a predetermined phase of drum rotation, this eliminates some of the drawbacks of the conventional method. However, after switching the pause button, it is possible to obtain a good still playback image within a short time.

[Brief explanation of the drawing]

FIG. 1 is a flow circuit of the operation mode of the present invention. FIG. 2 is a control circuit diagram of one embodiment of the present invention. FIG. 6 is a timing chart of FIG. 2. FIG. 4 is a timing chart of another embodiment. ...Flip-flop CsMo...Capstan motor applicant Canon Corporation

Claims (1)

[Scope of Claims] A magnetic reproducing device that scans a magnetic tape with a rotating head to derive a video signal from the magnetic tape, comprising: a first device that causes the magnetic tape to run slower than during normal reproduction;
a first detecting means for detecting a lack of a reproduced signal from the magnetic tape which has been switched to slow running by the first controlling means; A magnetic reproducing device comprising: second detection means for detecting coincidence with a signal obtained from rotation; and means for stopping running of the magnetic tape in response to coincidence detection by the second detection means.