JPS5917023Y2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a read drive type magnetic recording and reproducing apparatus in which the tape running speed is kept constant by controlling, for example, the number of revolutions of a take-up reel.

In general, reel drive type magnetic recording and reproducing devices run the magnetic tape by transmitting the rotation of a small DC motor whose speed is controlled by an electronic governor circuit to a take-up reel shaft. The mechanism was relatively simple.

However, as the magnetic tape is wound onto the take-up reel, the diameter of the wound magnetic tape gradually increases.

As a result, the circumference of the magnetic tape wound on the take-up reel also increases.

The travel of the magnetic tape due to one rotation of the take-up reel is equal to the length of the circumference of the wound magnetic tape, so if the rotation of the take-up reel is constant, the length of the magnetic tape wound is As the diameter of the magnetic tape increases, the running speed of the magnetic tape increases (3 to 5 cm/5ec).

For this reason, the capstan drive method (2.4 cm/5
Compared to the magnetic recording and reproducing apparatus described in ec), the recording time is shorter even with the same length of magnetic tape, and the recording quality is also lower.

In addition, the capstan drive method uses a take-up reel to wind up the magnetic tape sent out by the capstan, so there are many moving parts, and the mechanical parts that prevent the magnetic tape from winding are complicated, leading to problems with reliability. Ta.

Furthermore, both types of magnetic tape were not compatible because of their different tape speeds.

This idea was developed based on the above circumstances, and its purpose was to be able to keep the running speed of the magnetic tape constant at all times, to be compatible with capstan drive type magnetic tapes, and to have a mechanical part. It is an object of the present invention to provide a read drive type magnetic recording/reproducing device which is simple and can improve reliability.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 1 shows a motor rotation control section of a read drive type magnetic recording and reproducing apparatus according to this invention. A reel 4 is provided.

The magnetic tape 5 is supplied from a supply roll 2 and wound up by a take-up roll 4.

Further, a first pulse generator 6 is provided near the supply reel shaft 1.

The first pulse generator 6 detects the rotation of the supply reel shaft 1 and generates pulses in accordance with the rotation.

On the other hand, a second pulse generator 7 is provided near the take-up reel shaft 3.

This second pulse generator 7 detects the rotation of the take-up reel shaft 3 and generates pulses corresponding to the rotation.

Here, the relationship between the pulses generated from the first pulse generator 6 and the second pulse generator 7 is shown in FIGS. 2 and 3.

In Fig. 2, the horizontal axis is the position of the tape wound on the take-up reel 4, and the vertical axis is the number of pulses per unit length of the tape (
Note that the above tape position is the thickness of the magnetic tape 5 wound on the take-up reel 4.

When the tape position is zero (0), it is assumed that the magnetic tape 5 is not wound on the take-up reel 4 but is wound on the supply reel 2, and then the magnetic tape 5 is taken up on the take-up reel 4. shall begin to be wound.

At this time, the number of pulses per unit tape length output from the first pulse generator 6 gradually increases, and becomes as shown in characteristic A.

On the other hand, the number of pulses per tape unit length output from the second pulse generator 7 gradually decreases and becomes as shown in characteristic B.

Note that 1 in FIG. 2 is the tape position where the magnetic tape 5 is completely wound on the winding wheel 4.

Here, the pulse waveforms of A and B having the characteristics shown in FIG. 2 are shown in FIG. 3.

In this embodiment, by making the number of pulses per rotation of the supply reel 2 larger than that of the take-up reel 4, the second
As shown in the figure, the number of pulses per unit tape length from the first pulse generator 6 is greater than the number of pulses per unit tape length from the second pulse generator 7 at any tape position.

Therefore, as the tape position approaches 1, the difference C in the number of pulses per unit tape length increases.

Then, as shown in FIG. 3, the pulse generation interval from the first pulse generation section 6 becomes shorter than the pulse generation interval from the second pulse generation section 7.

In this way, the pulses output from the first pulse generator 6 are supplied to the counting circuit 8.

This counting circuit 8 is a circuit that counts pulses supplied from the first pulse generator 6.

Further, the pulse output from the second pulse generator 7 is
The signal is supplied to the clear terminal of the counting circuit 8 via the delay circuit 9.

The count contents of the counting circuit 8 and the pulses from the second pulse generating section 7 are supplied to the control pulse generating section 10.

The control pulse generator 10 is a circuit that reads the count contents of the counter circuit 8 every time a pulse is supplied from the second pulse generator 7, and generates a pulse with a pulse width corresponding to the count contents.

The output end of the control pulse generator 10 is connected to the base of an NPN transistor 12 via a resistor 11, and this base is grounded via a capacitor 13.

The collector of the transistor 12 is connected to the DC power supply +
V, and its emitter is connected to the base of an NPN transistor 15 via a resistor 14.

The emitter of the transistor 15 is grounded via a resistor 16, and the collector is connected to the base of an NPN transistor 17 and to its own base via a capacitor 18.

The emitter of the transistor 17 is connected to the DC power supply +V and to its own base via a resistor 19, and the collector is grounded via a series resistor 20.21.

The connection point between the resistors 20 and 21 is connected to the connection point between the base of the transistor 15 and the resistor 14.

Further, the collector of the transistor 17 is grounded via a series body of a resistor 22 and a reel drive motor 23.

Here, as an electronic governor circuit, the resistors 20 to 22 and the motor 23 constitute a bridge circuit 24, each of which serves as a component arm.

Note that the motor 23 is a DC motor for driving the take-up reel 4 via the shaft 3.

The contact between the resistor 22 and the motor 23 is connected to the emitter of the transistor 15 via a diode 25 with the polarity shown.

Next, the operation in the above configuration will be explained.

For example, when DC power +V is supplied to the circuit shown in FIG. 1, the motor 23 starts rotating.

When the motor 23 rotates, the take-up reel 4 rotates and the supply reel 2 rotates, causing the magnetic tape 5 to rotate.
runs.

Then, the first pulse generator 6 detects the rotation of the supply reel shaft 1, generates a pulse corresponding to the rotation, and supplies it to the counting circuit 8.

Thereby, this counting circuit 8 counts the pulses supplied from the first pulse generator 6.

On the other hand, the second pulse generator 7 detects the rotation of the take-up reel shaft 3, generates pulses corresponding to the rotation, and supplies them to the spreading circuit 9 and the control pulse generator 10, respectively.

As a result, each time a pulse is output from the second pulse generator 7, the count contents of the counter circuit 8 are manually input to the control pulse generator 10, and then the second pulse generator is delayed by the delay circuit 9. The count contents of the counting circuit 3 are cleared by the pulse from 7.

Repeat this action.

Each time a pulse is supplied from the second pulse generator 7, the control pulse generator 10 detects the tape position by reading the count contents of the counting circuit 8, and generates a pulse with a pulse width according to the count contents. That is, a pulse is generated to indirectly control the terminal voltage applied to the motor 23 so that the tape speed is constant.

This generated pulse has a tenity factor T, /'r
The panus width T1 is changed according to the above-mentioned counting contents.

Here, T is the pulse repetition period.

In this way, when a pulse of duty factor T, /T is output from the control pulse generator 10, this pulse is passed through the resistor 11 whose time constant is set larger than the period of the pulse.
It is converted into an averaged DC voltage by the capacitor 13 and supplied to the base of the transistor 12.

As the magnetic tape 5 is wound onto the winding wheel 4, the count of the counting circuit 8 increases, and the pulse width T1 of the pulse output from the control pulse generator 10 becomes smaller (duty factor T, / T becomes smaller.

), the base voltage of the transistor 12 becomes smaller.

When this base voltage decreases, the base voltage of the transistor 15 also decreases, and the voltage between the base and emitter of the transistor 15 decreases relatively.

Therefore, the base current of transistor 17 decreases,
The collector current of transistor 17 also becomes smaller.

Then, the terminal voltage of the motor 23 decreases, and the rotational speed decreases.

When the rotation speed of the motor 23 decreases, the rotation speed of the take-up reel 4 also decreases, and the running speed of the magnetic tape 5 decreases.

In this way, as the magnetic tape 5 is gradually wound onto the take-up reel 4, the count of the counting circuit 8 increases. By reducing , the terminal voltage of the motor 23 decreases, thereby reducing the rotation speed of the take-up reel 4 directly connected to the motor 23.
As a result, the magnetic tape 5 is run at a constant speed.

With such a configuration, the first. Second pulse generator 6
, 7 and a counting circuit 8 to detect the rotation of the reel;
The control pulse generator 10 generates a pulse with a pulse width corresponding to the detected content, and the motor 23
By controlling the terminal voltage of the motor 23 and changing the rotation speed of the motor 23, the rotation speed of the take-up reel 4 is controlled. The running speed of the magnetic tape 5 can always be kept constant.

Also, as a result of this, the running speed of the magnetic tape 5 does not increase as the magnetic tape 5 is wound around the winding wheel 4, so the recording time can be increased as in the capstan drive system. , and the recording quality can also be made uniform.

Furthermore, since the tape speed is constant, compatibility with capstan drive type magnetic tape can be achieved.

Furthermore, compared to the capstan drive system, the mechanism is simpler and reliability can be improved.

As detailed above, according to this invention, a pulse corresponding to the rotation of one reel is generated from the second pulse generator,
As the other reel rotates, the first pulse generating section generates more pulses than the second pulse generating section regardless of the running position of the tape, and the pulses are output from the first pulse generating section. is counted by a counting circuit, and a control pulse is generated according to the counting contents of the counting circuit when the pulse is generated from the second pulse generating section, and by this control pulse, electrons are sent to the detection terminal of the bridge circuit forming the BANA circuit. Since the terminal voltage of the reel drive motor is controlled by changing the voltage, the running speed of the magnetic tape can always be kept constant regardless of the position of the tape wound on the reel. This allows longer recording times and uniform recording quality, is compatible with capstan drive type magnetic tape, has a simple mechanism, and improves reliability. A reel drive type magnetic recording and reproducing device can be provided.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention, and Fig. 1 shows the components of the motor rotation control section, and Figs. 2 and 3 show the pulses generated from the first pulse generation section and the second pulse generation section. It is a figure showing the relationship of numbers. 2... Supply reel, 4... Take-up reel, 5... Magnetic tape, 6... First pulse generator, 7... Second
8... Counting circuit, 9... Delay circuit, 10... Control pulse generating section, 17... Transistor (active element), 23... Reel drive motor,
24...Bridge circuit.

Claims (1)

[Scope of utility model registration request] An electronic governor that controls the speed of the motor by inserting a reel drive motor into a component arm of a bridge circuit and controlling an active element connected in series to the motor using a voltage obtained from a detection end of the bridge circuit. In a reel drive type magnetic recording and reproducing device having a circuit, a second knob generates a pulse according to the rotation of one of the knobs.
a first pulse generating section that generates pulses with a greater number of pulses than the second pulse generating section regardless of the running position of the tape according to the rotation of the other reel; A counting circuit that counts the pulses output from the second pulse generating section and is cleared by the output from the second pulse generating section, and is controlled according to the counting contents of the counting circuit when pulses are generated from the second pulse generating section. The motor is characterized by comprising a control pulse generating section that generates a pulse, and a control means that controls the terminal voltage of the motor by changing the detection terminal voltage of the bridge circuit using the control pulse from the control pulse generating section. magnetic recording and reproducing device.