JPH01184650A - Tape carrying controller - Google Patents

Abstract

PURPOSE:To prevent the separation of a tape from a rotating cylinder at the time of changing a tape speed by applying the tape speed information of a tape supply side through the impedance of a tape supply side to the servo driving loop of a capstan shaft at the time of changing the tape speed. CONSTITUTION:At the time of changing the tape speed according to a mode switching, switches 57, 58 are respectively turned on and off for a constant time. The speed information according to the difference between the take up side and the supply side tape speeds by a FG head passing a comparator 55 and speed detectors 41 and 24, 47 and 54 is supplied to an amplifier 32, the rotation of the capstan shaft 46 is servo-controlled to make the tape speed of the supply side and the take up side coincide. Accordingly, the tape speed information of this tape supply side is applied to the servo driving loop of the capstan shaft, thereby, the generation of a phenomenon for separating the tape from the rotating cylinder 45 at the time of changing the tape speed is prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a tape conveyance control device in a video tape recorder, and in particular, to a tape conveyance control device for a video tape recorder, and particularly to a tape conveyance control device for preventing tape peeling from a rotating cylinder that occurs when the tape speed changes. Concerning tape transport control devices.

(Prior Art) Conventionally, a tape running system in a video tape recorder (VTR) is shown in FIG. During recording and playback, the tape 2 of the cassette 1 is supplied from the supply side rail 3, and the tape 2 of the cassette 1 is fed from the tape guide 4. Full width erase head 5. Supply side impedance roller 6, supply side loading post 7, rotating cylinder 80, winding side port-ding post 99, winding side impedance roller 10. Audio erase head 11. Audio control head 12. Pinch 0-ra 13, Kisebustan shaft 14. The tape passes through the tape guide 15 and is wound onto the take-up reel 16.

In the above tape running system, the capstan 'N114 and the pinch row 513 are used to run the tape wound on the reel at a constant speed.

Conventional capstan motor control is performed using a control circuit shown in FIG. In FIG. 3, reference numeral 41 is the head of a frequency oscillator (hereinafter referred to as FG head) provided on the capstan, 42 is a control head, 43 is a tape, 44 is a supply impedance roller, 45 is a rotating cylinder, and 46 is a cap The stun axis is shown. The rotational speed of the capstan flywheel is extracted as a pulse signal with a frequency proportional to the speed at FG head node 1, and this is sent to amplifier 2.
After being amplified by 1, the waveform is shaped by a Schmitt circuit 22, the frequency is divided by a predetermined frequency division ratio by a frequency divider 23, and the signal is supplied to a speed detector 24 to obtain a speed detection output. - side, control head 4
The control pulse from 2 (hereinafter referred to as CTL pulse) is amplified by an amplifier 26, shaped into a waveform by a Schmitt circuit 27, divided into a fixed ratio by a frequency divider 28, and then output from a reference generator 29 by a phase comparator 30. The phase is compared with the reference pulse to obtain the phase detection output. Then, the speed detection output and the phase detection output are passed through a filter 25.degree. 31.33, mixed by an amplifier 32, and the mixed output is supplied as an error voltage to a drive amplifier 34 to control the capstan motor.

By the way, in the above tape running system, the tape is transported by a capstan motor and the tape winding motor is carried out by a motor, so if the tape speed changes (for example, when the CU
E (rewind) → PB (play), FF (fast forward) → CUE
(rewinding)), if the tape speed suddenly slows down, the capstan motor will not be able to fully feed the tape fed from the supply reel, resulting in peeling (non-contact) between the rotating cylinder and the tape, causing the video head to The playback screen may become distorted because the signal cannot be picked up sufficiently. In addition, the tape a fed out from the supply reel when the tape speed changes also changes depending on the tape winding position on the reel, but the capstan motor cannot respond to such changes, and if the degree of tape peeling is large, Not only did the playback screen become distorted, but the tape was sometimes given 1flf13.

This is because capstan motor control is performed by a control system as shown in Figure 3, speed control is based on capstan FG pulses, phase control is based on CTL pulses, and the supply side reel As mentioned above, when the tape speed changes, separation may occur between the rotating cylinder and the tape, which may disrupt the playback screen or damage the tape. There was a problem that occurred.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned problems, and it is an object of the present invention to provide a tape transport control device that can control a capstan motor so that tape peeling does not occur when the tape speed changes. be.

The tape conveyance control device of the present invention adds an FG to the impedance roller on the supply side, provides means for speed detecting the FG pulse obtained from the FG, and further compares the speed detection output with the speed detection output by the FG of the capstan motor. Comparing means is provided, and when the tape speed changes, the output of the comparing means is outputted in place of the phase detection output by the CTL pulse of the normal capstan control loop using the switching means, and is used as information on the tape feeding on the supply side. The structure is such that feedback is provided to the capstan motor.

(Function) In the present invention, information on the tape R sent out from the supply reel is fed back to the capstan drive side when the tape speed changes, and when the tape feed speed from the supply reel is faster than the tape feed speed of the capstan shaft. In this case, the rotation speed of the capstan motor can be increased, and in the opposite case, the motor speed can be controlled to be slowed down. As a result, even when the tape speed changes, the tape feeding speed is the same on the tape supply side and the winding side, and peeling between the rotating cylinder and the tape does not occur.

(Example) The present invention will be described below based on the example shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of the tape transport control device of the present invention.

In this figure, the same parts as in FIG. 3 are given the same reference numerals. The difference from Fig. 3 is that a frequency oscillator (FG) (shown as FG head node 7 in the figure) is added to the impedance roller 44 on the supply side, which is attached to prevent tape vibration, and that the FG pulse is processed. Amplifier 51. Schmitt circuit 529 frequency division 'a53. Speed detection 3
54. Comparator 55. Filter 56. switches 57 and 5
This is the point where 8 was set. Note that the speed detection output of the speed detector 54 is inputted to one input terminal of the comparator 55, and the speed detection output of the speed detection Va24 is inputted to the other input terminal. Switch 57 connects phase comparator 30 and filter 3
The switch 58 is connected between the filter 56 and the filter 31, and the switches 57 and 58 are operated in an on/off manner in reverse to each other. The other configurations are the same as in FIG. 3.

Next, the operation will be explained.

In normal times when the tape speed is stable, the switch 57 is on and the switch 58 is off. The operation at this time is the same as that shown in FIG.

That is, the rotational speed of the capstan flywheel is extracted by the FG head 1 as a pulse signal with a frequency proportional to the speed, amplified by the amplifier 21, waveform-shaped by the Schmitt circuit 22, divided by the frequency divider 23, and then the speed is The signal is supplied to the wave detector 24 to obtain a speed detection output. On the other hand, control head 4
The CTL pulse from 2 is amplified by an amplifier 26, shaped by a Schmitt circuit 27, divided by a frequency divider 28, and then compared in phase with a reference pulse from a reference generator 29 in a phase comparator 30. Obtain the detection output. Then, the speed detection output and the phase detection output are filtered to filter 25.31.3.
3 and mixed by an amplifier 32, and the mixed output is supplied to a drive amplifier 34 to control the capstan motor.

Next, when the tape speed changes (mode transition), the switch 58 is turned on for a certain period of time and the switch 57 is turned off. At this time, the rotational speed of the impedance roller is extracted as a pulse signal with a frequency proportional to the speed by the FG head node 7, amplified by the amplifier 51, waveform-shaped by the Schmitt circuit 52, and divided by the frequency divider 53. , speed detector 5
4 to obtain the speed detection output. The speed detection output of this speed detector 54 and the speed detection output from the speed detector 24 based on the capstan FG pulse are compared by a comparator 55, and the speed detection output from the speed detector 54 is compared with the speed detection output from the speed detector 24 based on the capstan FG pulse. If the tape feeding speed) is faster than the tape feeding speed of the capstan, the comparator 55 applies a high-level comparison output to the child terminal of the amplifier 32 through the filter 56.31, thereby increasing the error voltage supplied to the drive amplifier 34. , the rotational speed of the capstan flywheel is increased, and in the opposite case, the comparator 55 outputs a low-level comparison output to lower the error voltage supplied to the drive amplifier 34 to lower the rotational speed of the capstan flywheel. Make it.

[Effects of the Invention] As described above, according to the present invention, tape feeding from the supply reel is fed back to the capstan 11110 loop. The peeling of the tape that occurs on the other hand is eliminated, the screen disturbance can be eliminated, and the tape is not damaged.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the tape transport control device of the present invention, FIG. 2 is a plan view showing a tape transport system of a VTR, and FIG. 3 is a block diagram showing a conventional tape transport control device. . 21.26.51...Amplifier, 22.26.52...Schmitt circuit, 23.28.
53... Frequency divider, 24.54... Speed detector, 25.31.33.56... Filter, 29... Reference generator, 32... Amplifier, 41.47... FG head node 42...CTL head, 43...tape, 44...
・Impedance roller, 45...Rotating cylinder, 46...Capstan shaft,
55... Comparator. Agent Patent Attorney Nori Chika Ken

Claims (1)

[Claims] A first frequency oscillator that generates a pulse signal with a frequency proportional to the rotational speed of the capstan motor, and a DC voltage that corresponds to the frequency by detecting the pulse signal from the first frequency oscillator. a detection means for detecting a control pulse recorded on the tape; and a phase detection means for comparing the phase of the control pulse from this detection means with a reference pulse to obtain a DC voltage corresponding to the phase difference. a second frequency oscillator that generates a pulse signal with a frequency proportional to the rotational speed of the supply side impedance roller; and a second frequency oscillator that detects the pulse signal from the second frequency oscillator and obtains a DC voltage corresponding to the frequency. Comparing means for comparing the output of the second speed detection means with the output of the first speed detection means and obtaining a comparison output according to the magnitude relationship; and phase detection of the phase detection means. It selectively switches and outputs the comparison output between the output and the comparison output of the comparison means, and when the tape speed changes, it switches to the comparison output for a certain period of time, and when the tape speed is in a stable state, it switches to the phase detection output. a switching means; a mixing means for mixing the speed detection output of the first speed detection means and the output from the switching means to obtain an error voltage for capstan motor control; and an output of the mixing means for controlling the capstan motor. 1. A tape conveyance control device comprising: a drive means for controlling the rotation of the tape conveyance control device.