JPS63247955A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the need for mechanical adjustment and to enable stable loading and unloading of a tape by controlling the driving of a loading motor so as to minimize the absolute value of the difference in the output level detected by the number of revolutions of a reel base at the time of taking in and out of the tape of a cassette cape and the reference value. CONSTITUTION:The pulse in the frequencies corresponding to the number of revolutions is outputted from a pulse generator 22 with the turning of the winding reel 21 turning at the time of taking in and out of the tape of a cassette tape and converted into a DC current by a frequency-voltage converting circuit 24. This DC voltage is compared with the reference value by a differential amplifier 26 to detect the level difference, a loading motor 12 is subjected to feedback control via a driving circuit 29 so that the level difference absolute value may become min. and its number of revolutions are almost held constantly. A stable tape loading and unloading are thus executed even with the variation in the load of the loading motor without doing mechanical adjustment, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a magnetic recording and reproducing device used in video tape recorders, 8 mm video, digital audio tape recorders, and the like.

``Prior Art'' In a video tape recorder or the like, when a cassette tape is loaded, a loading motor is driven, and the rotational force of the loading motor pulls out the magnetic tape from the cassette tape and attaches it to a rotating head. That is, loading is performed. Further, during unloading, that is, when the loaded magnetic tape is removed from the rotary head and stored in a cassette tape, the loading motor is driven in reverse. FIG. 2 shows the state in which the magnetic tape Ia of the cassette tape L is attached to the rotary head 2, 3 to 9 are posts that hold the magnetic tape 1a, IO is a capstan that sends the magnetic tape la,
A pinch roller 11 presses the magnetic tape 1a against the capstan IO. 2 is a loading motor, which is driven by direct current during loading and unloading operations. 13 and 14 are gears that transmit the power of the loading motor 12. 15 is
This is a loading gear, which receives power transmitted from the motor 12 via gears 13 and 14, and loads or removes the magnetic tape la from the rotary head 2. (i.e. perform loading/unloading). Next, the drive circuit 16 shown in FIG. 3 is a circuit that drives the loading motor 12 based on the signal RD instructing loading/unloading and the signal MO instructing motor on/off, and the signal MO is "l". signal, and if signal RD is “1” signal, motor 1
A power supply voltage V cc (DC voltage) is applied to the terminal 12a of No. 2, and a ground potential is applied to the terminal 12b. As a result, the motor 12 rotates normally, and loading is performed. Also, when the signal MC is "l" and the signal RD is "0", the motor I
Connect @potential to the terminal 12a of 2, and connect the power supply voltage V to the terminal 12b.
cc is applied to each.

This causes the motor 12 to rotate in reverse, and unloading is performed. Furthermore, when the signal MC is “0”, the signal R
Regardless of the value of D, the power supply to the motor 12 is turned off. In this case, of course, the motor 12 is not driven.

"Problems to be Solved by the Invention" By the way, in the conventional device described above, the loading motor 12 is controlled in an open loop, and therefore,
The rotational speed of the motor 12 changes greatly due to load fluctuations during loading/unloading, variations in mechanical deck adjustment, etc., and in some cases, the motor 12 may stop. Further, during loading/unloading, the time during which the motor 12 is rotating changes significantly due to load fluctuations, and the mechanical switch that opens and closes upon completion of loading or unloading may not operate normally.

The present invention has been made in view of the above circumstances, and its object is to use magnetic recording technology that can control the rotational speed of a loading motor driven during loading/unloading operations to be almost constant even when there are load fluctuations. The purpose is to provide a playback device.

``Means for Solving the Problems'' The present invention provides a magnetic recording and reproducing apparatus in which loading and unloading of a cassette tape is performed by the rotational force of a loading motor. a detection means; a second detection means for detecting a level difference between the output of the first detection means and a set value; and motor driving means for driving the loading motor so that the absolute value of is a minimum value.

"Effect" Case during loading/unloading, I)
, the same number * of the tape reel is proportional to the rotation speed of the loading motor. Therefore, according to the above-described configuration, the rotation speed of the loading motor can be controlled in a closed loop during loading/unloading.
Therefore, even if the load fluctuates, the rotational speed can be kept almost constant.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the same members as those described in the prior art are given the same reference numerals and the description thereof will be omitted. FIG. 1 is a driving circuit diagram of a loading motor 12 used in a magnetic recording/reproducing apparatus according to the present invention. In this figure, 21 is a take-up reel;
During loading/unloading, this take-up reel 21 is driven to rotate. Note that in this case, the supply reel (path shown) does not rotate. 22 is a pulse generator that generates a pulse signal P with a frequency proportional to the number of rotations of the take-up reel 21, the output of which is amplified by an amplifier 23 and supplied to an F/V (frequency/voltage) conversion circuit 24. Ru. As the above-mentioned pulse generator 22, for example, an optical type including a light emitting element and a light receiving element is used. In this case, the pulse generator 22 is arranged opposite to the back side of the reel 21, and the back side of the reel 21 is painted alternately black and white at equal central angles, and is white.

Signals with different levels are obtained due to the difference in reflectance of black and the like. The F/V conversion circuit 24 is a circuit that generates a voltage proportional to the frequency of the pulse signal P. That is, the output voltage Vl of this F/V conversion circuit 24 becomes a voltage proportional to the number of rotations of the take-up reel 21. 25 is a switch, which is open when the signal MC is an “L” signal (during loading or unloading), and the signal MO is “L”;
0" signal, it is closed. 26 is a differential amplifier, which connects the voltage V1 supplied via the switch 25 and the resistor 2.
7. The voltage difference between the voltage V ref and the voltage at the connection point of the variable resistor 28 is amplified and output to the drive circuit 29 . Here, the variable resistor 28 is for setting the rotation speed of the loading motor 12.

When both the signal MC and the signal RD are "L", the drive circuit 29 applies a positive voltage to the terminal 12a of the loading motor I2 and a ground potential to the terminal 12b, thereby causing the loading motor 12 to rotate normally.

By rotating the loading motor 12 forward, the cassette tape is loaded. Further, when the signal MC is "[" and the signal RD is "0", a ground potential is applied to the terminal 12a, and a positive voltage is applied to the terminal 12b. This results in
The loading motor 12 is reversed, and the cassette tape is unloaded. In this case, drive circuit 2
9 controls the output voltage according to the output voltage Va of the differential amplifier 26.

That is, when the voltage Va is 0, the set voltage V ref
A DC voltage determined according to the voltage Va is output to the loading motor 12, and when the voltage Va is positive, the output voltage is increased according to the value of the same voltage Va, and when the voltage Va is negative, the output voltage is increased according to the absolute value of the same voltage Va. to reduce the output voltage. In addition, the signal MC
When is "0", the loading motor 12 is not driven.

In the above configuration, when the rotation speed of the loading motor 12 increases beyond the set value due to load fluctuations, the rotation speed of the reel 21 increases accordingly, and the output voltage v1 of the F/V conversion circuit 24 increases. Therefore, the output voltage Va of the differential amplifier 26 decreases, and the output voltage of the drive circuit 29 decreases. As a result, the rotation speed of the loading motor 12 decreases and returns to the set value. Conversely, loading motor 12
When the rotation speed of the reel 21 decreases below the set value, the rotation speed of the reel 21 decreases, the output voltage Vl of the F/V conversion circuit 24 decreases, and the output voltage Va of the differential amplifier 26 increases. output voltage increases. As a result, the rotation speed of the loading motor 12 increases and returns to the set value.

Although the switch 25 is shown in the above embodiment, the loading motor itself may be used only for loading/unloading operations and may be omitted. but,
Since this motor may be used for other mode switching, etc., it is described here to separate it from this. Further, although the REF signal is obtained from the differential amplifier after F/V conversion, it goes without saying that the same result can be achieved even if another control signal superimposition circuit or the like is used. Furthermore, although a reel sensor detection circuit 23 is included, if the level can be increased, the same effect can be achieved by using resistance division.

"Effects of the Invention" As explained above, according to the present invention, the rotation speed of the loading motor can be controlled in a closed loop during loading/unloading. It can be kept constant. As a result, the following advantages are obtained.

■Even if the load on the loading motor changes during loading/unloading, stable loading/unloading can be performed.

■Mechanical adjustment related to loading/unloading becomes more difficult as the set becomes smaller, but this mechanical adjustment is no longer necessary.

■If you take into account the cost of mechanical adjustment, it will also be cheaper.

[Brief explanation of the drawing]

FIG. 1 is a drive circuit diagram of the loading motor 12 used in the magnetic recording and reproducing apparatus according to the present invention, FIG. 2 is a diagram showing the loading state of the magnetic tape Ia in a video tape recorder, and FIG. 3 is a diagram of the loading motor 12
FIG. 2 is a conventional drive circuit diagram. 1...Cassette tape, 12...Loading motor, 21...Take-up reel, 2
2...Pulse generator, 24...F/V conversion circuit, 26...Differential amplifier, 29...
drive circuit.

Claims (1)

[Claims] (a) Magnetic recording and playback in which loading and unloading of the tape in a cassette is performed by winding it around a cylinder drum having a head etc. that records and plays back signals using the rotational force of a loading motor. In the apparatus, (b) a first detection means for detecting the number of rotations of the reel stand that rotates when the cassette tape is taken in and out, and obtaining a frequency signal; (c) a frequency signal output of the first detection means is converted into a DC component; (d) an output of the second detection means during the loading or unloading period of the cassette tape; a motor driving means for driving the loading motor so that the absolute value of the level becomes a minimum value.