JPS60132478A - Intermittent feed system of tape - Google Patents

Abstract

PURPOSE:To attain the accurate frame feed reproduction with low cost and the reproduction at a low speed by using the track jump pulse of a piezoelectric element to stop a slow feed of a tape. CONSTITUTION:An electronic switch 15 is turned on and off in a proper repetitive cycle by a speed control circuit 14. When the switch 15 is turned on, a head switch pulse sets a motor ON memory 19 and an electronic switch 21 is connected. In this case, the output of an FG1-up 17 is converted by a speed detecting circuit 24 into the voltage proportional to the speed of a magnetic tape 1. Then a capstan motor 6 is driven in the acceleration direction by a capstan drive circuit 23 through a revolving direction switching circuit 22. Thus the motor 6 is accelerated and revolved at a fixed speed to feed the tape 1. Then the piezoelectric drive voltage is changed to produce a track jump. Therefore a brake memory 20 is set and the circuit 22 is actuated. Thus the motor 6 is set under a reverse brake state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is capable of recording by mounting a video head on a movable actuator that uses a piezo element or some other element that can achieve an effect equivalent to it, and moving this 5Hah actuator up and down. The present invention relates to an intermittent tape feeding system that can be used in a magnetic recording/reproducing device that realizes noise-free reproduced images at a tape speed lower than the tape speed.

Conventional configuration and its problems In order to achieve low-speed playback, it is necessary to rotate the capstan motor at a low speed, but this is generally very difficult. In other words, the load characteristics (rotational speed change/load change) realized by the speed control system are limited by the inertia of the capstan and the FG frequency. Therefore, if the speed becomes low, the FG frequency increases and the achievable load characteristics deteriorate. Moreover, since the rotational speed itself is decreasing, the load rotational speed change rate (rotational speed change rate/load change) further deteriorates. Furthermore, in general, the lower the speed, the greater the friction and the greater the load, so stable low-speed rotation becomes more difficult as the speed becomes lower.

Therefore, for low-speed reproduction below a certain level, it is necessary to perform intermittent feeding by repeating rotation and stopping.

If you simply want to play back sound at a low speed, you can perform intermittent forwarding at an appropriate ratio depending on the playback speed. However, considering the cost of frame-advance playback, this requires that the tape be accurately fed one frame at a time. If the number of frame feeds is small, even inaccuracies can be corrected to some extent by the movement of the movable actuator, but if we consider a large number of continuous frame feeds, it cannot be corrected by the movement of the movable actuator, and the tape feed itself is It is necessary to keep it for exactly one frame.

Conventionally, as a standard for accurately feeding the tape equivalent to one frame, a method of detecting a control signal recorded on the tape or a method of counting the number of teeth of a gear stand FG has been used. There are problems such as:

In other words, in the method of using the control signal on the tape, in order to obtain a sufficient control output (Repe) Vf,
It is necessary to increase the tape speed in the forwarding part of the intermittent forwarding to a certain extent, which leads to a large change in the relative speed of the video head between the stop part and the forwarding part.
Image shaking occurs on one screen. This restriction can be solved by using a control head such as a chisel head, but the recording head and the reproducing head are located in different locations, resulting in an increase in cost.

Also, in the method of counting the number of teeth on the capstan FG,
It is necessary to count accurately, including starting from a stopped state, and if the amount that the motor advances from issuing a stop command after counting the number of FG teeth to stopping varies due to load changes, etc., an error will occur, and one frame This method has drawbacks such as inaccurate feeding and inability to handle a large number of continuous frame feeds.

As described above, although low-speed playback is possible in the conventional system, accurate frame-by-frame playback is difficult to achieve.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to provide a nine-tape inter-tape insertion/retraction system that enables accurate frame-by-frame playback at low cost and also enables low-speed playback. shall be.

Structure of the Invention In order to achieve the above-mentioned object, the Q1 intermittent transmission system of the present invention uses a speed command means to start a capstan motor via a capstan drive circuit, and a movable motor on which a video head is mounted. The brake is applied to the capstan motor instantaneously or after a predetermined period of time has passed after the actuator has performed the track jumping operation at least once a predetermined number of times.

That is, during the feeding period during intermission and withdrawal, as the tape moves, the movable actuator moves so as to obtain a noiseless image, so the height gradually changes. And when this height change becomes equal to one frame,
The actuator moves 1 to the next frame 9. By stopping the intermittent transmission based on the track transition information of the movable actuator for realizing this noiseless image (l-), accurate l-frame transmission becomes possible. Since the tape feed f) is controlled by information from the movable actuator, it does not have the drawbacks of conventional methods that use control signals or capstan FG, and is the cheapest and most reliable method. .

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of a main part of a VTR employing an intermittent tape feed system according to an embodiment of the present invention, and this embodiment is an embodiment for the VB2 or β system. In Figure 1, (1) is a magnetic tape, (2) is a cylinder, (
3) is a piezo element, (5) is a two-phase FG, (6) is a capstan motor, (7) is a herad switch pulse generation circuit, (8) is a head amplifier, (9) is a height search circuit, α
Q is the still pattern generation circuit, aη is the moving pattern generation circuit, @ is the piezo drive circuit, (2) is the 7-jump processing circuit, 04) is the nuvede control circuit, αG is the first electronic switch, 0Q is the Rotation direction detection circuit, αη is the first FG aan, a barrel is the jg2 FG amplifier, QIU
Motor on memory, 翰 is brake memory,? υ is the second
The electronic switch (goods) is the rotation direction switching circuit, ■ is the capstan drive circuit, and (c) is the speed detection circuit.

■In the S or β method, since the pilot signal is not recorded on the first rack of the videotape, the piezo element (3) carrying the video head built into the cylinder (2) is compatible with the track trajectory at the time of methylation. A still pattern to be detected, a movement pattern to correct the movement line of the magnetic tape (1), and a search output using the head amplifier output to align the head on the piezo element (3) with the recording track are piezoelectric. The signals are combined and applied by the drive circuit @. These waveforms are generated by two methyl patterns corresponding to the two heads in the methyl pattern generation circuit O*.
In addition, the two movement patterns corresponding to the two heads are determined by the two-phase FG (
5) is amplified by the first FG amplifier αη and counted by the moving pattern generation circuit Uυ, and the search output is obtained by amplifying the video head output by the head amplifier (8) to obtain the maximum is output so that the video head output is obtained. Here, the height search has a slow response, but since it always operates so that the output of the video head mounted on the piezo element (3) is maximized, the movement pattern generated by counting the number of FG teeth can be determined. Even if it is not perfect for the reasons described in the conventional example, it is possible to overcome this effect and achieve complete noiseless reproduction.

As for the movement pattern, when the amount of movement of the magnetic tape (1) is equivalent to one frame, it is necessary to move to the adjacent track of 17V, which is 6D, which means that the output of the piezo drive circuit @ is transferred to the track jump processing circuit α. After the piezo drive voltage increases or decreases by more than 17V, reset the movement pattern generation circuit 0u at a time when the piezo element (3) is not in contact with the magnetic tape (1). This is achieved by

Next, the intermittent feed processing section of the magnetic tape (1) will be explained. The speed control circuit 041 turns on and off the first electronic switch αQ at an appropriate repetition period. When the first electronic switch αG is turned on, the head switch pulse sets the motor-on memo') LlCJ and the second electronic switch eυ is connected. At this time, the output of the first FG amplifier Q'i) is the speed detection circuit ■
The capstan drive circuit (A) drives the capstan motor (6) in the acceleration direction through the rotation direction switching circuit (A).

When the capstan motor (6) is accelerated and rotates at a constant speed and the magnetic tape (1) is fed, the piezo drive voltage changes as described above, and a track skipping operation is performed. When this track jumping operation is performed, the brake memory wire is set, the rotational direction detection circuit wire is activated, and the capstan motor (6) enters the reverse braking state.

When the speed of the capsun motor (6) decreases and begins to reverse, two FG outputs (31
The rotation direction detection circuit qQ detects the reversal of the capstan motor (6), and the motor-on memory Ql and brake memory ) is reset, the second electronic switch feυ is turned off, and the capstan motor (6) is stopped. Since the above-mentioned one frame transmission is performed by the speed control circuit a< every time the first electronic frame Q5 is turned on, the speed can be varied from one frame transmission to continuous low speed playback.

Figure 2 is an operation timing chart of the circuit block shown in Figure @1, where (al is the head switch pulse, (1))
is the first nutill pattern, (C) is the second methyl pattern, (dl is the first movement pattern, tel is the second movement pattern, (flld) rack jump pulse, (gl is the capstan motor current, (hl is the rotation direction detection output. In this example, the tape speed in the constant speed section during intermittent feeding is 115 of the normal speed, and the repeating average speed is 1/10
It becomes. Here, the first and second still patterns (b) and (c) are used to correct the difference in track locus between normal playback and still playback for each head, and apply a voltage equivalent to one field. It has an amplitude.

The first and second movement patterns (d) and (e) are for correcting the amount of tape movement, and change each time the capstan feeds the magnetic tape (1). The two heads are reset at a timing when the element (3) does not come into contact with the magnetic tape (1), and the capstan motor (6) enters the brake mode. Also in this brake section, the magnetic tape (1) As the movement progresses slightly, the movement pattern changes by this amount, but there is no adverse effect.Furthermore, imperfections in the movement pattern due to FG count errors are covered by a height search waveform (not shown).

In this way, in the slow playback method that uses the piezo element (3), tape feeding, which had a problem in the past, can be stopped at low cost by using the track jump pulse of the piezo element (3). and can be completely resolved.

Although the above embodiment has been described using the piezo element (3), any method such as magnetic means can be used as long as a movable actuator can be realized.

Further, in the above embodiment, the capstan motor (6) is stopped every time a track jump pulse (fl) is generated, but it may be stopped after an arbitrary number of pulses are obtained.

Alternatively, the operation may be stopped at a certain timing after the track jump pulse (f) is output.

Furthermore, since the present invention only requires a track jump pulse, it can be applied to any piezo drive method.
Naturally, the present invention can also be applied to a type that uses a pilot signal.As described in detail, the present invention allows accurate frame-by-frame playback at low cost, and also allows accurate low-speed playback.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of the main parts of a magnetic recording and reproducing apparatus that employs an intermittent tape feeding method in an embodiment of the present invention.
FIG. 2 is a timing chart showing the operation of the circuit shown in FIG. 1. (1)...Magnetic tape, (2)...Cylinder, (3
)...Piezo element, (5)...2 phase FG, (6
)... Capstan motor, (7)... Head switch pulse generation circuit, +81... Head amplifier, (9
1...Height search circuit, uG...Still pattern generation circuit, Uυ...Movement pattern generation circuit, @...Piezo drive circuit, L13...Track jump processing circuit, En...Speed control Circuit, (1G...first inlet switch, Q119...rotation direction switching circuit,
Beam...first FG amplifier, (to)...second FG
Ang, 4...Motor on memory, (A)...Brake memory, ■υ...Second Genko switch, (4)
...Rotation direction switching circuit, (c)...Cagnutand figure circuit, (to)...Speed detection circuit agent Yoshihiro Morimoto

Claims (1)

[Claims] ■ The speed command means starts the capstan motor via the capstan drive circuit, and after the movable actuator on which the video head is mounted has performed a predetermined number of track jump operations, the speed command means instantly starts the capstan motor via the capstan drive circuit, and then instantly Intermittent tape feeding method 9 in which the brake is applied to the capstan motor after a predetermined period of time has elapsed.