JPH0516662Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Purpose of the invention] (Field of industrial application) The present invention is a tape recorder, particularly a friction drive system in which the tape is moved by friction between the capstan and the tape without using a pinch roller. Regarding the tension servo of a reel-to-reel tape recorder with a transport.

(Prior Art) FIG. 3 shows an example of a friction drive type tape transport.

In this type of tape transport, a tape 50 wound around a reel 4 mounted on a supply side reel stand 2 passes through a roller 10, a guide roller 8, a guide pin 7, a guide pin 6, a capstan 5, and a roller 9. It is adapted to be wound onto a reel 3 mounted on a reel stand 1 on the take-up side.

The servo system on the supply side is composed of a tension detection means for detecting the tension of the tape 50, a motor drive circuit 18, and a motor 20. The tension detection means is rotatable around a roller 10 and a shaft 12. Tension arm 14, spring 22,
A position sensor 16 detects the position of the tension arm 14. The spring 22 is set so that a predetermined tape tension is applied when the tension arm 14 is at the center of its movable range (hereinafter referred to as
The center of the tension arm's movable range is the set position,
The tape tension at that time is referred to as the tension setting value). The output of the position sensor 16 is input to the motor drive circuit 18, and the output of the motor drive circuit 18 is
A motor 20 directly connected to the reel stand 2 is driven.

The servo system on the take-up side is installed in exactly the same way, with roller 9, tension arm 13, and position sensor 1.
5 and a tension detection means consisting of a spring 21;
It is composed of a motor drive circuit 17 and a motor 19.

Then, when the tension arm 14 lowers, that is, when the tape tension becomes weaker than the set value, the servo system on the supply side operates the motor 20.
attempts to wind up the tape 50, and conversely, when the tension arm 14 rises, that is, when the tape tension becomes stronger than the set value, the motor 20
is adapted to operate so as to weaken the force with which the tape 50 is wound.

The above operation is exactly the same for the servo system on the take-up side, and each servo system operates independently. Through this operation, the tape tension is maintained at the set value, and the tape 50 travels as the capstan 5 rotates due to friction with the capstan 5.

(Problems to be Solved by the Invention) In the friction drive type transport described above, when the capstan 5 is rotated at high speed in the direction in which the reel 3 winds the tape 50,
Even if the tape 50 is running at a constant speed, the motor 19 on the winding side needs to generate torque to deal with shaft friction and air resistance due to rotation, and the increase in weight of the reel 3 due to the tape 50 being wound. Therefore, the motor drive circuit 17 needs to output an output higher than that in the stopped state. However, since the gain of the motor drive circuit 17 is finite, the torque cannot be compensated for unless the tension arm 13 falls below the set position. Ideally, the gain of the motor drive circuit 17 is infinite, and if the gain is infinite, the motor drive circuit 17 will be able to control the tension arm 13 with respect to the target tension of the tape. Drive the motor so that the detected tensions match perfectly. However, the gain of the motor drive circuit 17 is actually finite, and as a result, the tension detected by the tension arm 13 does not completely match the target tension of the tape, resulting in an error. However, this means that the input to the motor drive circuit 17 is increasing, and as the position of the tension arm 13 is lowered, it means that the tape tension on the winding side is weaker than the set value.

On the other hand, on the feeding side, back tension is applied to the tape due to resistance in the tape running system such as friction against rotation, so the motor 2
0 requires the torque to be reduced by that amount,
As mentioned above, since the gain of the motor drive circuit 18 is finite, the tension arm 14 rises above the normal position, which means that the tape tension on the feeding side becomes stronger than the set value.

Therefore, in a friction drive type transport as described above, when the tape is run at a very high speed, the deviation of the tension arms 13 and 14 from the set position becomes large, and in severe cases, the tension Since the arm 13 needs to be lowered significantly, there is a problem in that the tape tension on the take-up side becomes too weak, causing the tape 50 and the capstan 5 to slip.

As described above, the reason why the tension arms 13 and 14 are biased when driving the motors 19 and 20 is that the gain of the servo system is finite. The deviation can be reduced by increasing the gain of the servo system, but increasing the gain of the servo system tends to make the operation unstable, so simply increasing the gain of the servo system does not solve the above problem. No.

The purpose of the present invention is to solve the above-mentioned problems and to prevent the tension arm from deviating from the set position even when the tape is running at high speed.

[Structure of the idea]

(Means for solving the problem) In order to achieve the above object, the present invention includes a rotational speed detection means for detecting the rotational speed of the motor, and an output from the rotational speed detection means and an output from the tension detection means. A drive voltage correction means is provided for adjusting the drive voltage of the reel motor.

(Function) Since the present invention has the above configuration, it functions as follows.

That is, when the tape runs, the rotational speed of the motor is detected by the rotational speed detection means, and the driving voltage correction means increases the driving voltage of the motor of the tape take-up reel in accordance with the rotational speed. Since the drive voltage of the motor of the sending reel is reduced, the torque of the motor of the take-up reel increases and the torque of the motor of the sending reel decreases.

Therefore, even when the tape is running at high speed, the tension arm does not deviate from the set position, and slips between the tape and the capstan do not occur, so that a stable tape running condition can be obtained.

(Example) The illustrated embodiment will be described below.

FIG. 1 is a block diagram showing an embodiment of the present invention, and parts similar to those of the conventional device shown in FIG. 3 are given the same reference numerals.

In FIG. 1, 36 is a slit plate directly connected to the shaft of the motor 20, and 38a and 38b are photo sensors.The slit plate 36 and the photo sensors 38a and 38b constitute rotation detection means for the motor 20. ing. The slit plate 36 rotates together with the shaft of the motor 20, and the photo sensors 38a, 38
b outputs a two-phase clock signal by the rotation of this slit plate 36.

24 is a direction determination circuit which inputs the two-phase clock output from the photo sensors 38a and 38b, determines the rotational direction of the motor 20 (that is, the rotational direction of the reel 4) based on this signal, and outputs the determination signal. Output.

Reference numeral 26 denotes an FV converter, which together with the rotation detecting means constitutes a rotation speed detecting means for the motor 20. This FV converter 26 outputs a voltage that is a signal of the rotational speed of the motor 20 according to the frequency of the output pulse of the photo sensor 38a.

32 and 34 are switches, only one of which is turned on in response to the output of the direction determining circuit 24, and 30 is an inverting amplifier. These switches 32, 34 and the inverting amplifier 30 constitute a polarity selection section. This polarity selection section inputs the output of the photo sensor 38a constituting the rotational speed detection means and the output of the direction determination circuit 24, and based on the output from the direction determination circuit 24, the reel 4 moves in the direction of arrow a. If the reel 4 is rotating in the direction of arrow b, turn the switch 32 ON and switch 34 OFF; if the reel 4 is rotating in the direction of arrow b, turn the switch 32 OFF,
Turn on switch 34. The output of the polarity selection section is added to the output of the position sensor 16 by an adder 28 and then connected to the motor drive circuit 18.

The above is the configuration of the supply side, but the take-up side is also exactly the same, and in addition to the conventional servo system, there is a slit plate 35 and a photo sensor 37.
A rotation detecting means for the motor 19 consisting of the switches 31 and 37b, an FV converter 25, a direction determining circuit 23, a polarity selecting section consisting of the switches 31 and 33 and an inverting amplifier 29, and an adder 27 are provided.

Next, the operation on the supply side will be explained.

First, when the tape 50 is not running, the photo sensors 38a, 3 of the rotational speed detection means are
Since there is no output from 8b, there is no difference from the conventional example described above.

Next, consider a case where the tape 50 is running in a direction in which the reel 4 rotates in the direction of arrow a in the figure.
ON, and switch 34 is turned OFF.

Therefore, the output of the photo sensor 38a is
The FV converter 26 converts the voltage into a voltage according to the frequency of the pulse, which is added to the output of the position sensor 16 by the adder 28, and the motor drive circuit 1
8, thereby causing the motor 20 to increase the force for winding up the tape 50, that is, the torque in the direction of arrow a.

Conversely, when the tape 50 is running in the direction in which the reel 4 rotates in the direction of arrow b, the polarity selection means turns off the switch 32 and turns off the switch 34.
Set to ON. Therefore, the photo sensor 38a
The output of
Since it is added to the output of the position sensor 16 through 0 and inputted to the motor drive circuit 18, the input state is substantially subtracted, and the winding force of the motor 20 is further reduced.

The above operation is exactly the same on the take-up side. As a result, for example, when the tape 50 is running in the direction in which the reel 4 rotates in the direction of arrow b, the motor 1 of the take-up reel 3
As the torque of the tension arms 13 and 14 increases, the torque of the motor 20 of the sending reel 4 decreases, so that even when the tape 50 is running at high speed, the tension arms 13 and 14 do not deviate from their set positions, and the tape 50 And capstan 5 never slips.

Next, it will be explained with reference to FIG. 2 that the above-described operation reduces the deviation of the tension arms 13, 14 from the set positions.

FIG. 2 shows the output of the motor drive circuit with respect to the position of the tension arm, 39 shows the position-output relationship in the case of the conventional device when the tape 50 is in a stopped state, and 40 shows the position-output relationship in the case of the conventional device in which the tape 50 is in a stopped state. This shows the position-output relationship when the tape is traveling in the direction in which it is wound. As can be seen from graph 39, in the case of the conventional device, when the tension arm is in the center position, the output of the motor drive circuit is P ₀ , which applies the set tension to the tape.
In order to obtain an even stronger output P ₁ , the tension arm must be shifted by φ ₁ from its position in the stopped state. On the other hand, according to the embodiment of the present invention, in order to obtain the above-mentioned output P ₁ , as can be seen from graph 40, the tension arm only needs to be in the center even when the tape is running. . Moreover, as can be seen from these graphs 39 and 40, the output of the motor drive circuit of this embodiment, that is, the gain, in response to changes in the position of the tension arm does not change at all compared to the conventional one, so the servo system is unstable. There is no such thing as

The graph in Figure 2 is an explanation of the operation on the winding side, but on the sending side, the characteristic 40 is translated in parallel to the origin, resulting in a characteristic 40', so the operation is equivalent to the above case. It is.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above-described embodiment and can be modified as appropriate within the scope of the gist of the present invention.

[Effect of idea]

As detailed above, according to the present invention, even when the tape is running at high speed, the output voltage of the tension arm is corrected according to the tape running speed, so that the tension arm does not move away from the set position. As a result, there is no change in the tension of the tape, so slips between the tension arm and the capstan roller do not occur, resulting in a stable tape running condition.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is an explanatory diagram of the same operation as above, and FIG. 3 is a block diagram of a tape transport of a conventional friction drive. 1, 2...Reel stand, 3, 4...Reel, 5...
...Capstan, 6,7...Guide pin, 8...
Guide rollers, 9, 10...Rollers, 11, 12
...Axis, 13, 14...Tension arm, 1
5, 16... Position sensor, 17, 18... Motor drive circuit, 19, 20... Motor, 21, 22
... Spring, 23, 24 ... Direction discrimination circuit, 25,
26...FV converter, 27, 28...adder,
29, 30...inverting amplifier, 31, 32, 33,
34...Switch, 35, 36...Slit plate,
37a, 37b, 38a, 38b...sensor.

Claims (1)

[Claims for Utility Model Registration] (1) In a tape recorder where the running speed of the tape is determined by the rotation of a capstan, a motor for driving a reel wound with tape, a tension detection means for detecting the tension of the tape,
a rotational speed detection means attached to the motor to detect the rotational speed of the motor; and a signal from the rotational speed detection means to be added to a signal from the tension detection means when the motor rotates in the winding direction. and a drive voltage correction means that subtracts the voltage when rotating in the feeding direction, and a motor drive circuit that drives the motor so that the tension of the tape becomes a preset value based on the signal from the drive voltage correction means. A tape recorder comprising: (2) The rotational speed detection means includes a slit plate directly connected to the shaft of the motor, a photo sensor that outputs a two-phase clock signal by the rotation of the slit plate, and a photo sensor that outputs a two-phase clock signal according to the frequency of the output pulse of the photo sensor. The tape recorder according to claim 1, which is comprised of an FV converter that outputs a voltage that is a signal of the rotational speed of the motor in response to the signal. (3) The driving voltage correction means includes a direction determining circuit that determines the rotation direction of the motor based on the output signal from the rotational speed detecting means and outputs a determination signal thereof, and a direction determining circuit that determines the rotation direction of the motor based on the output signal from the rotation speed detecting means and outputs a determination signal from the direction determining circuit.
Utility model registration claim 1 comprising a polarity selection unit equipped with an inverting amplifier having a switch that is turned on and off, and an adder that adds the output from the polarity selection unit to the output from the tension detection means. The tape recorder according to item 1 or 2.