JPS63237252A - Video tape recorder - Google Patents

Abstract

PURPOSE:To prevent the sag of a tape at the time of acceleration and to prevent the damage of the tape by delaying the rise of a capstan and setting it to agree with the rise of a reel on a winding side when the travel speed of the tape is accelerated due to a change in the rotational speed of the capstan. CONSTITUTION:When the key device 2 of a video tape recorder is instructed from a still mode to a three-fold reproduction mode by the operation of a user, it sequentially changes stepwise at the time to of a control signal SCCA from a servo micro computer 3, and a change is terminated in a prescribed time. The rotational speed of the capstan motor 7 is changed with the prescribed time from a time T0 and the rise is delayed. A frequency generator 40 is integrally fitted to the rotation axis of a reel motor 10, and a frequency signal SFG from the generator 40 is supplied to the computer 3. The changed speed of the control signal SCCA is controlled based on the signal SFG and the sag of the tape at the time of acceleration can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to video tape recorders.

[Summary of the invention]

The present invention provides a video tape recorder in which, when the tape running speed is accelerated due to a change in the rotational speed of the capstan,
By delaying the rise of the capstan so that it substantially coincides with the rise of the take-up reel, the tape is prevented from sagging and, in turn, damage to the tape is prevented.

[Conventional technology]

FIG. 3 shows a drive system for a capstan motor and a reel motor of a video tape recorder (VTR).

In the figure, (1) is a main microcomputer (hereinafter referred to as main microcomputer) provided in the VTR;
This is for controlling the operation of R.

A key device (2) is connected to this main microcomputer (1),
The operation of the VTR is controlled according to the user's operation of the key device (2).

Further, (3) is a servo microcomputer (hereinafter referred to as a servo microcomputer). The servo microcomputer (3) is supplied with command data instructing the rotational speed of the capstan, that is, the capstan motor, from the main microcomputer (1). And this servo microcontroller (3)
From then on, a control signal 5CC corresponding to the command data is sent.
A is output.

Control signal s cCA from this servo microcomputer (3)
is converted into an analog signal by a D/A converter (4), and then supplied to the base of an NPN transistor (6) via an amplifier (5). The collector of this transistor (6) is connected to the power supply terminal B, and its emitter is grounded via the capstan motor (7). Therefore, a current corresponding to the control signal SCC^ is caused to flow through the capstan motor (7) by the transistor (6), and the control signal SC
It is made to rotate at a speed corresponding to c8.

Further, the main microcomputer (1) outputs a control signal 5CR1+ that controls the rotation of the reel motor, and this control signal 5CR1+ is outputted from the main microcomputer (1).
CRtz is supplied via an amplifier (8) to the base of an NPN transistor (9). This transistor (9)
The collector is connected to the power supply terminal B, and its emitter is grounded via the motor (10). Therefore, a current corresponding to the control signal SC is passed through the reel motor (10) by the transistor (9), and a current corresponding to the control signal s
It is made to rotate at a speed corresponding to cR.

[Problem that the invention seeks to solve]

By the way, in recent years, the accuracy and performance of the capstan motor (7) have improved, and the range of variable speed of the tape by changing the rotational speed of the capstan has become wider (for example, from still mode to 8x playback mode). It is possible to adjust the tape running speed.

In such a VTR, when the tape running speed is rapidly accelerated due to a change in the rotational speed of the capstan, the rise of the take-up reel lags behind the rise of the capstan due to inertia, causing slack in the tape. arises,
As a result, there was an inconvenience that the tape was damaged.

For example, at time to, the user's key device (2)
When the still mode is instructed to change to the 8x playback mode by the operation of (7), therefore, the rotational speed of the capstan is as shown in Figure B.
changes rapidly. Also, at this time, the main microcomputer (1) outputs a control signal 5CRI2 at time 0, which controls the reel motor (10) and therefore the take-up side and reel to rotate, but its rise is faster than that of the capstan. There was a problem that the tape sent out by the capstan was not sufficiently wound up by the take-up reel, resulting in slack in the tape. In particular, when the tape on the take-up reel is irregularly wound, the start-up of the take-up reel becomes even slower, which increases the amount of slack in the tape, which may lead to damage to the tape.

FIG. 5 shows an example of the mechanical parts of a VTR, in which (11) is a tape guide drum, (12) is a capstan, (13) is a movable pinch roller, and (14) is an audio signal eraser. The magnetic head (15) is a magnetic head for recording and reproducing control pulses and a magnetic head for recording and reproducing audio signals. (16) to (23) are tape guides, among which (17), (18), (21), (2
2) and (23) are moving tape guides, and the others are fixed tape guides. Also, (25) is a tape cassette,
(26) is the supply side reel, and (27) is the take-up side reel.

Further, (30) is a magnetic head for reproducing control pulses, which is also used as an erasing magnetic head for erasing the entire width of the magnetic tape T. In such a mechanical part,
During recording and playback, the magnetic tape T is pulled out from the tape cassette (25) and is moved from (26) to (16) to
(30)→(17)→(11)−(14)→(15)→
(12)→(23)→(22) −(21)→(18)
The tape is wound around the tape guide drum (11) and travels through the path →(19) →(20) →(27). Therefore, the tape slack mentioned above is
This especially occurs at the arrow P portion.

In view of these points, the present invention is intended to prevent tape sagging and damage to the tape as described above.

[Means for solving problems]

According to the present invention, when the tape running speed is accelerated due to a change in the rotational speed of the capstan, the rise of the capstan is delayed to substantially match the rise of the take-up reel.

[Effect]

In the above configuration, the rise of the capstan is made to substantially coincide with the rise of the take-up reel, so the tape sent out by the capstan is sufficiently wound up by the take-up reel.
This can prevent the tape from becoming sagging.

〔Example〕

An embodiment of the present invention will be described below. In this example, the drive system of the capstan motor and reel motor is the third
It is assumed to be the same as the example shown.

In this example, when a mode in which the tape running speed is increased is instructed by the user's operation of the key device (2), the control signal 5CcA from the servo microcomputer (3) is
is made to change sequentially at a predetermined speed. This rate of change is uniformly determined, for example, assuming that the tape on the take-up reel is in a certain irregular winding state, and the rise of the capstan motor (7), and thus the capstan, is the same as the rise of the take-up reel. The speed is set to match.

For example, at time to, the user's key device (2)
When the 8x speed playback mode is instructed from the still mode by the operation of Finish changing. The rotational speed of the capstan motor (7), and hence the capstan, is changed over a predetermined period of time from time to, as shown in FIG. Fg, the rise is delayed.

In this example, the user's key device (2)
When a mode in which the tape running speed is increased is instructed by the operation of , the control signal SCc^ from the servo microcomputer (3) is made to change sequentially at a predetermined speed, and the capstan motor (7), Therefore, the rise of the capstan is made to coincide with the rise of the take-up reel.

Therefore, according to this example, the tape sent out by the capstan is sufficiently wound up by the take-up reel, and it is possible to prevent the tape from becoming slack, thereby preventing damage to the tape. .

In the above-described embodiment, the rate of change of the control signal SCC^ is uniformly determined on the assumption that the tape on the take-up reel is in a certain disordered state. When the tape is wound, it is impossible to prevent the tape from becoming slack.

Therefore, in order to solve this problem, as shown in FIG. and this frequency signal SFG
Based on this, the rate of change of the control signal SCc^, that is, the rise of the capstan motor (7) may be controlled.

By the way, it is conceivable to interpose a still mode when switching between the forward playback mode and the reverse playback mode, but in this case, the still mode becomes the playback mode in which the tape running speed is increased, so this is not suitable throughout the present invention. be.

〔Effect of the invention〕

According to the present invention described above, when the tape running speed is accelerated due to a change in the rotational speed of the capstan, the rise of the capstan is delayed and made to substantially coincide with the rise of the take-up reel, so that the tape running speed during acceleration is delayed. It is possible to prevent the tape from sagging and, in turn, to prevent damage to the tape.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining one embodiment of the present invention, Fig. 2 is a diagram showing another embodiment of the invention, Fig. 3 is a diagram showing an example of a motor drive system, and Fig. 4 is a diagram showing an example of a motor drive system. FIG. 5, which is a diagram for explaining the same, is a diagram showing the mechanical part of the VTR. (11 is the main microcomputer, (2) is the key device,
(3) is a servo microcomputer, (7) is a capstan motor, and (lO) is a reel motor.

Claims (1)

[Scope of Claims] A video tape recorder characterized in that when the tape running speed is accelerated due to a change in the rotational speed of the capstan, the rise of the capstan is delayed to substantially coincide with the rise of the take-up reel.