JPS5922258A - Device for controlling driving of tape - Google Patents

Abstract

PURPOSE:To control tape speed and tape tension easily and precisely even in the high speed traveling state of the tape, by compensating loss torque corresponding to the turning speed of a reel motor on the feeding side by an output from a speed information detecting means for the feeding side reel motor. CONSTITUTION:When the inlet tension of a winding side reel is TT and the radius of the tape is RT, the generation torque phiT of the winding side reel motor is phiT=RT.TT. If the torque generation constant of the winding side reel motor is KTT, the current IT of the winding side reel motor is increased more than phiT=KTT.IT and the voltage of both the ends of a winding side reel motor current detecting element (resistor) 31 is raised. Therefore, the detected voltage is fed back to a servo circuit 32 of the feeding side reel motor, the current of the feeding side reel motor is reduced and the outlet tension of the feeding side reel is controlled so as to be almost fixed, so that the inlet tension on the winding side reel can be almost fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape 1 drive control device useful for tape recorders, and particularly to a tape drive control device that performs high-speed tape running of FF (fast forward) and REW (rewind) in a VTR using a reel motor. Regarding equipment.

Figure 1 shows a cassette type VTR0FF (fast forward).

FIG. 3 is a diagram showing a REW (rewind) tape running drive device. In FIG. 1, 1 indicates a tape cassette, and ? indicates magnetic tape. 3.4 is the supply side and take-up side reel shaft, which is the supply side and take-up side reel 5 of the tape cassette 1;
6. Reference numerals 7 and 8 indicate supply and take-up reel motors that directly drive the supply and take-up reel shafts 3 and 4, respectively. Magnetic chi 7' 21
d-F During F (fast forwarding), winding is carried out from the supply reel 5 through the posts 9 and 10, along the rotary head cylinder 11, along the audio head and control head by the intermediate post 12, and through the posts 13, 14 and 16. It is wound onto the take-up reel 6. 17 is the capstan shaft, 1
8 is a pinch roller. Reference numerals 19 and 20 indicate frequency generators that detect rotational speed information of the supply side and take-up side reel motors 7.8. The output signals of the frequency generators 19 and 20 are input to the supply side and winding side servo circuits 21 and 22, and the output of the supply side servo circuit 21 causes the supply side reel motor 7 to be driven by the output of the winding side servo circuit 22. The side reel motors 8 are controlled respectively.

During FF (fast forwarding), the speed of the reel motor 8 on the winding side is controlled so that the sum of the frequencies of the output signals of the frequency generators 19 and 20 on the supply side and winding side is constant, and the reel motor 7 on the supply side A constant motor current is applied to generate torque in the direction opposite to the rotational direction of the supply reel 5 so that an appropriate pack tension is applied to the supply reel 5. Still R
During EW (rewinding), the speed of the supply reel motor 7 is controlled so that the sum of the periods of the output signals of the supply and take-up frequency generators 19 and 20 is constant, and the take-up reel motor 8 is A constant motor current is passed in the opposite direction to the rotational direction of the take-up reel 6 so that an appropriate back tension is applied to the reel 2.

In the above conventional example, during FF (fast forwarding), a constant current ■s is passed through the supply reel motor 7 in the opposite direction to the rotation direction of the supply reel 5, so that the supply reel motor 7 generates Torque φS is the torque generation constant I of the supply side reel motor (if TS, then φ5−KTs°■s °°°°°° (1),
If the tape tension Ts at the exit from the supply reel 6 is wound on the supply reel and the radius of the tape is R8, then φ5 = Ts - R8 (2). Since the generated torque φS' is constant, the tape tension Ts at the outlet from the supply reel is the radius R8 of the tape wound on the supply reel.
As it passes through each post, the tape tension increases by e/lO (μ is the coefficient of friction of the tape, θ is the winding angle of the tape), and the tension at the entrance of the take-up reel 6 increases in inverse proportion to the decrease in . The tape tension TT becomes extremely large, increasing the load on the take-up reel motor 8, which may slow down the speed of the magnetic tape 2 or, in the worst case, prevent it from being wound. However, since the tape tension changes by the amount of the tape winding diameter of the supply reel 5 between the beginning and the end of winding, the tape tension changes by about three times, which is a drawback that the tape running condition does not improve.

The present invention solves these drawbacks and provides a tape drive control device that can easily and reliably control the tape speed and tape tension even when the tape is running at high speed.

An embodiment of the present invention will be described in detail below with reference to FIGS. 2 and 3.

FIG. 2 shows a block diagram of a tape drive control device for a tape recorder according to an embodiment of the present invention. In FIG. 2, 7 and 8 are supply side and take-up side reel motors, and 19
．． 20 is a frequency generator that detects rotational speed information of the supply side and take-up side reel motors 7.8. 30.31 is a reel motor current detection element (resistance) of the reel motor 7.8 on the supply side and take-up side, 32.33 is a servo circuit on the supply side and take-up side, and the frequency generator 19 is connected to the supply side servo circuit 32.
, 20 and the output signal of the reel motor current detection element 31 on the winding side are input, and the output signal of the frequency generators 19 and 20 and the output of the reel motor current detection element 30 on the supply side are input to the winding side servo circuit 33. Signals are input, and the outputs of the respective servo circuits 32,33 control the respective reel motors 7.8.

During FF (fast forwarding), the reel motor 8 on the winding side is connected to the frequency generator 19 on the supply side and the winding side. The speed is controlled so that the sum of the periods of the -20 output signals is constant. The supply reel motor 7 first causes a reel motor current corresponding to the loss torque of the supply reel motor itself to flow through the supply reel motor 7 so that torque is generated in the same direction as the rotation direction of the supply reel.

Figure 3 shows the relationship between motor loss torque and rotational speed. Even if the motor rotation speed is almost zero, motor loss torque φLO exists, and if the motor rotation speed increases to N1, the motor loss torque also becomes φLN. Therefore, the output signal of the frequency generator 19 of the supply reel motor 7 can compensate for the torque corresponding to the rotational speed of the supply reel motor 7. Next, a constant motor current IS is applied so as to generate torque in the direction opposite to the rotational direction of the supply reel so that an appropriate back tension is applied at the beginning of winding of the magnetic chi. By doing this, at the beginning of winding the magnetic tape, both the tension TS at the exit of the supply reel and the tension TT at the entrance of the take-up reel are optimized. but,
This one! As the magnetic tape is FF (fast forwarded), the radius R8 of the tape wound on the supply reel becomes smaller, so the tension Ts at the outlet of the supply reel decreases.
increases in inverse proportion to the tape radius R8, so TT=Ts-eμθ... According to the relationship (3), the inlet tension TT of the take-up reel also increases.
The generated torque φT of the take-up reel is φT"RT"T (4), where the radius of the tape wound on the take-up reel is RT.
If the take-up side reel motor current IT is the torque generation constant KTT of the take-up side reel motor, then φT-KTT゛■T
Since the voltage across the reel motor current detection element (resistance) 31 on the winding side increases, this detection voltage is applied to the servo circuit 3 of the reel motor on the supply side.
Returning to step 2, the supply side reel motor current flowing so that torque is generated in the opposite direction to the rotation direction of the supply side reel is reduced, and the tension at the outlet of the supply side reel is kept almost constant. By controlling in this manner, the tension at the inlet of the take-up reel can be kept almost constant. R.E.
During V (rewind), the relationship between the supply reel motor and the take-up reel motor during FF (fast forward) is simply reversed.

As described above, according to the present invention, the tape speed and tape tension can be easily and reliably controlled during high-speed tape running. There is an advantage that there is no need to provide an excessive margin for the torque of the reel motor.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a tape drive control circuit of a conventional VTR, Fig. 2 is a block diagram of a tape drive control circuit of a VTR which is an embodiment of the present invention, and Fig. 3 shows the rotational speed of the motor of the VTR. FIG. 3 is a characteristic diagram showing the relationship of loss torque. 7... Supply side reel motor, 8... Winding side reel motor, 19.20... Frequency generator, 30.31... Reel motor current Detection element, 3233...Φ... Servo circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (3)

[Claims] (1) Drive current detection means for detecting the drive current of the take-up reel motor of the pair of reel motors, speed and information detection means for detecting rotational speed information of the supply reel motor, and and a servo circuit, based on the output of the drive current detection means of the take-up reel motor and the output of the speed information detection means of the supply reel motor,
A tape drive control device that controls a servo circuit of the supply reel motor. (2) The servo circuit separates the loss torque of the supply reel motor into a part unrelated to the rotation speed of the motor and a proportional part, and uses the output of the speed information detection means of the supply reel motor to adjust the rotation speed of the supply reel motor. 2. The tape drive control device according to claim 1, wherein the tape drive control device compensates for loss torque accordingly. (3) The servo circuit controls the supply reel motor so that the tape tension on the take-up side is constant or the tension at the end of winding is weaker than the tension at the beginning of winding based on the output of the drive current detection means of the reel motor on the take-up side. A tape 1 drive control device according to claim 1, characterized in that: