JPH021714Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a VTR tape sag prevention device that prevents the tape from sagging during unloading. The loading disk is driven so that the tape does not slack even if the reel motor stops during unloading.

Generally, a VTR in which a capstan drive system and a reel drive system are configured separately and each is provided with an independent motor is configured as shown in Figure 1.
During loading, the tape 3 from the supply reel 2 of the cassette 1 passes through the pin 4 of the tension lever and is wound around the cylinder 5 containing the rotary head, between the capstan 6, the pinch roller 7 and each tape guide 8, 9. , 10 and is wound onto the take-up reel 11 of the cassette 1. The capstan flywheel 12 of the capstan 6 is rotated by a capstan motor 13 via a belt 14, and the take-up reel 11 and the supply reel 2 are rotated by a reel motor 15 through a belt 16, a slip mechanism 17, a belt 18 and It is rotated via rollers 19 and the like. Note that 20 is a loading disk.

By the way, when unloading with the VTR eject switch, the capstan motor 13
This is done by operating the loading disk 20 via the capstan flywheel 12, and winding the tape 3 between the reels 2 and 11 at this time is done by driving the capstan motor 13 and driving the loading disk 20. This is done by driving the motor 15 and rotating the take-up reel 11 via the slip mechanism 17. However, at this point, for example, the reel motor 15 breaks down and the take-up reel 1
1 does not wind up the tape 3, the tape 3 becomes slack.

Therefore, in the conventional tape sagging prevention device, a large number of grooves are formed at equal intervals on the outer periphery of the reel stand, these are detected by a photocoupler, and the detection signal is inputted to the input terminal I shown in FIG. When the reel stand is stopped, that is, when no pulse signal due to the rotation of the reel stand is input to the input terminal I, the auto-stop circuit 21 is operated. That is, when a pulse signal is input to the input terminal I, the pulse signal is input to the base of _{the first transistor Q 1 via} the first capacitor C ₁ and the first resistor R 1. Q ₁ is turned on, current from the power supply + ^B flows to the first transistor Q ₁ via the third resistor R ₃ , and no current flows to the base of the second transistor Q ₂ , so the second transistor Q ₂ is off. Next, when the reel stand stops and the pulse signal is no longer input from the input terminal I, the first transistor Q ₁ is turned off and the third
The current through the resistor R ₃ flows into the second capacitor C ₂ ,
The second capacitor _C2 starts charging, and the collector potential of the first transistor _Q1 is gradually increased.
When this collector potential becomes larger than the sum of the Zener voltage of the voltage regulator diode D and the base-emitter voltage of the second transistor _Q2 , the current passing through the third resistor _R3 and the voltage regulator diode D increases to the second transistor Q2. The current flows from the base of transistor Q ₂ to the emitter, turns on the second transistor Q ₂ , and the power supply + ^B
A current flows from the terminal through the fifth resistor _R5 to the second transistor _Q2 . Therefore, the second transistor
An auto-stop circuit 21 connected to the collector of _Q2 detects rotation and stoppage of the reel stand, and when the stop of the reel stand is detected, the auto-stop circuit 21 operates to prevent the tape 3 from slacking. Note that R ₂ and R ₄ are a second resistor and a fourth resistor for switching the first and second transistors Q ₁ and Q ₂ , respectively.
It is resistance.

However, the rotation speed of the reel stand is very slow,
Until the pulse signal is input to the input terminal I due to the rotation of the reel stand and the second transistor _Q2 is turned off.
Some time (about 2 seconds if it is long during standard driving)
Therefore, it is necessary to prohibit input to the auto-stop circuit 21 during this period. That is, if the reel stand is not rotating for about two seconds after starting unloading, the tape 3 will become slack.

This invention was made with the above points in mind, and the capstan motor 13 is driven only when the reel motor 15 is rotating during unloading.
This will be explained in detail with reference to FIG. 3 showing an embodiment.

In FIG. 3, 22 is a reel motor control circuit, 23 is a capstan motor control circuit, and 24 is a frequency generator serving as rotation detection means for the reel motor 15. When the reel motor 15 is driven to rotate, a constant frequency signal is generated. occurs. A detection circuit 25 detects the output of the frequency generator 24. Q ₃ is controlled to open and close by the reel motor control circuit 22
The third PNP type transistor, _Q4 , is an NPN whose opening and closing are controlled by the capstan motor control circuit 23.
_Q5 is a fifth transistor of NPN type whose opening/closing is controlled by the detection circuit 25.
Q ₆ is a PNP type sixth transistor for driving control of the capstan motor 13, which is turned on when the fifth transistor Q ₅ is turned on, and the sixth and fourth transistors Q ₆ and Q ₄ are connected to the power supply + ^B and the cap. Stun motor 13
is established between.

Next, the operation of the embodiment will be explained.

When unloading from the loading state by operating the ejection switch of the VTR, first, the control output of the reel motor control circuit 22 is
The voltage is input to the base of the transistor _Q3 , the third transistor _Q3 is turned on, power supply voltage is supplied from the power supply + ^B to the reel motor ₁₅ through the third transistor Q3, and the reel motor 15 rotates. At this time, the control output from the capstan motor control circuit 23 is input to the base of the fourth transistor _Q4 , but since the sixth transistor _Q6 is off,
No current flows through the fourth transistor _Q4 , and the capstan motor 13 is in a stopped state. and,
Due to the rotation of the reel motor 15, the frequency generator 2
When a signal with a constant frequency is generated at 4, this signal output is detected by the detection circuit 25, and the detection circuit 25 outputs a detection output. This output is the sixth resistor
The current flows into the base of the fifth transistor Q5 through _R6 , turning on the fifth transistor _{Q5 ,} and the current flowing from the power supply + ^B between the emitter and base of the sixth transistor _Q6 flows through the seventh resistor _R7. At the same time, the current flows to the fifth transistor _Q5 , and at the same time, the sixth transistor _Q6
is turned on, and the power supply voltage is applied to the sixth and fourth transistors.
The signal is supplied to the capstan motor 13 via Q ₆ and Q ₄ , and the motor 13 starts rotating, and the loading disk 20 starts driving.

Therefore, according to the embodiment, the capstan motor 13 that drives the loading disk 20 can be rotated only after the reel motor 15 rotates, so the reel motor 15 is not stopped during unloading. Even if the tape 3 is used, the tape 3 does not slacken, and the drawbacks of the conventional method can be solved.

As described above, the present invention provides independent motors for the capstan drive system and the reel drive system, and when unloading, the capstan motor drives the loading disk.
The reel motor rotates the take-up reel via a slip mechanism to wind the tape.
A tape sagging prevention device for a VTR includes a reel motor control circuit that supplies a control output to the reel motor to drive the reel motor during unloading, and a rotation detection signal when the reel motor control circuit detects rotation of the reel motor. a capstan control circuit that outputs a control output for driving the capstan motor to the capstan motor; and a capstan control circuit that outputs a control output for driving the capstan motor; Since the opening/closing means is closed only when the reel motor is rotating in response to a detection signal and supplies the control output of the capstan control circuit to the capstan motor, the capstan drives the loading disk only when the reel motor is rotating. The pushstand motor can be rotated during unloading.
The tape will not slack even if the reel motor stops.

[Brief explanation of the drawing]

FIG. 1 is a mechanical diagram of a VTR, and FIGS. 2 and 3 are circuit diagrams of a tape sag prevention device for a VTR. FIG. 2 is a conventional example, and FIG. 3 is an embodiment of this invention. 3...Tape, 11...Take-up reel, 13...
... Capstan motor, 15 ... Reel motor,
17...Slip mechanism, 20...Loading disk, 24...Frequency generator, _Q6 ...Sixth transistor.

Claims (1)

[Scope of Claim for Utility Model Registration] Motors are provided independently in the capstan drive system and reel drive system, and during unloading,
In a VTR tape sagging prevention device in which a capstan motor drives a loading disk and a reel motor rotates a take-up reel via a slip mechanism to wind up the tape, when unloading, the reel motor a reel motor control circuit that supplies a control output to the reel motor to drive the reel motor; a rotation detection circuit that outputs a rotation detection signal when the reel motor control circuit detects rotation of the reel motor; and a rotation detection circuit that outputs a rotation detection signal to drive the capstan motor. a capstan control circuit that outputs a control output to the capstan motor, and a capstan control circuit provided between a power source and the capstan motor,
A tape sag prevention device for a VTR, comprising an opening/closing means that is closed only when the reel motor is rotating in response to a detection signal from the rotation detection circuit to supply a control output of the capstan control circuit to the capstan motor.