JPH06187698A - Tape tension controller - Google Patents

Abstract

PURPOSE:To obtain a tape tension controller detecting and controlling the tape tension without providing a mechanical detecting mechanism such as a tape tension detecting arm. CONSTITUTION:An FG signal is detected from a motor 2 driving a reel 4 on a tape feeding side, and a load current is detected from the motor 2 through an A/D converter 11, then the tape winding diameter rs of the reel 4 is calculated according to a fixed tape traveling speed and the FG signal. The tape tension in the midst of tape traveling is calculated basing on the calculated tape winding diameter rs and the detected load current Is. A microcomputer 1 is provided, which controls voltage impressed on the motor 2 basing on the result obtained by comparing the calculated tape tension with previously set target tape tension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape tension control device incorporated in a recording / reproducing device using a cassette tape such as a VTR (video tape recorder) or a DAT (digital audio tape).

[0002]

2. Description of the Related Art Among devices using cassette tapes such as VTRs and DATs, in a consumer high-end model or a commercial device, a direct drive system is adopted as a reel drive system to perform fine reel drive control. It is possible. A conventional tape tension control device in that case will be described below.

A conventional tape tension control device has a tape tension detecting arm, and this arm is brought into contact with a tape running between a supply reel (it becomes a reel on the tape feeding side during Play) and a head drum. It is provided in. The arm moves with a small force,
The strength of the tape tension is represented by its movement. The movement of the arm is detected, for example, by converting it into light intensity. Specifically, a light emitting element and a light receiving element (for example, C
dS) is provided to face each other, and a light shielding plate for changing the amount of light passing from the light emitting element to the light receiving element is provided. The light shielding plate is interlocked with the arm to move the arm. The intensity of light received by the element is converted.

CdS, which is a light receiving element, changes its resistance value depending on the intensity of received light, and this resistance value change is detected as a voltage value change. This detected voltage value is fed back and compared with the reference voltage (target value), and as a result of the comparison,
If it is determined that the tape tension is lower than the target value, the voltage applied to the reel drive motor is increased to increase the back torque of the supply reel. On the other hand, if the tape tension is determined to be higher than the target value, the reel drive motor. The control is performed so that the voltage applied to the supply reel is reduced to reduce the back torque of the supply reel.

[0005]

However, in the above-described conventional tape tension control device, an extra member (for example, a post) must be inserted in the tape running path in order to bring the arm into contact with the running tape. I won't. Therefore, the number of parts is increased, the mechanism is complicated, and the tape running load is increased. Further, if the tape is greatly loosened due to some trouble, the tape may be entangled with the tape tension detection mechanism and may be scratched.

In view of the above circumstances, it is an object of the present invention to provide a tape tension control device which detects the tape tension and controls the tape tension without a mechanical detection mechanism such as a tape tension detection arm.

[0007]

In order to solve the above-mentioned problems, a tape tension control device of the present invention comprises means for detecting an FG signal from a motor for driving a reel on the tape feeding side, and the reel drive motor. Means for detecting load current, constant tape running speed and FG
A means for calculating the tape winding diameter of the reel on the tape feeding side based on the signal, a means for calculating the tape tension during tape running based on the calculated tape winding diameter and the detected load current, and this calculated And a means for controlling a voltage applied to the reel drive motor based on a comparison result between the tape tension and a preset target tape tension.

[0008]

According to the above construction, since a mechanical member such as a tape tension detecting arm is unnecessary, an increase in the number of parts and a complicated mechanism can be avoided, and the tape running load can be reduced. Further, even if the tape is greatly loosened due to some trouble, there is no possibility of scratching the tape.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments thereof. FIG. 1 is a system configuration diagram of a tape tension control device, in which 1 is a microcomputer,
2 is a supply reel drive motor, 3 is a take-up reel drive motor, 4 is a supply reel, 5 is a take-up reel, 6 is a tape,
7, 8 are D / A (digital / analog) converters, 9, 1
Reference numeral 0 is a motor drive circuit, 11 and 12 are A / D (analog / digital) converters, and 13 to 16 are amplifiers.

The D / A converters 7 and 8 D / A convert the control voltage output from the microcomputer 1 and convert the analogized control voltage into the motor drive circuits 9 and 10.
To enter. The motor drive circuits 9 and 10 drive the motors 2 and 3 based on the input control voltage.

The FG signals from the supply reel drive motor 2 and the take-up reel drive motor 3 are sent to the amplifiers 14 and 15 respectively.
The signal is amplified and shaped by and is input to the microcomputer 1. Further, the load currents from the supply reel drive motor 2 and the take-up reel drive motor 3 are amplified by the amplifiers 13 and 16, and further A / A
The signals are A / D converted by the D converters 11 and 12 and then input to the microcomputer 1.

The microcomputer 1 receives the FG signal (f _FG ) from the supply reel drive motor 2 and the tape running speed (V _S : constant) at the time of Play (that is, when the supply reel 4 is on the tape feeding side). The tape winding diameter (r _S ) of the supply reel 4 is calculated by using the calculated tape winding diameter (r _S ) and the load current (I) detected from the supply reel drive motor 2 via the A / D converter 11. based on the _S) calculates the tape tension during tape travel (T _S), on the basis of the comparison result between the calculated tape tension (T _S) between the target tape tension which is preset (T _O) The control voltage is changed.

The tape tension (T _S ) is calculated by formulating Equation 5 based on Equations 1 to 4 below.

[0014]

[Formula 1] V _S = r _S · ω _S = 2π · r _S · f _S = 2π · r _S · f _FG / N Note that the relationship of f _FG = f _S × N is established. (V _S : tape running speed) (r _S : winding diameter) (ω _S : angular velocity of supply reel) (f _S : rotation cycle of supply reel) (N: FG magnetization number) (f _FG : FG cycle)

Here, the equation of motion of the supply reel for a certain winding diameter is as follows.

[0016]

[Formula 2] J _S · ω _S = T _S · r _S −Q _S (J _S : reel inertia) (T _S : tape tension) (Q _S : reel back torque)

The relationship between the reel back torque Q _S and the load current I _S of the supply reel drive motor is as follows.

[0018]

[Formula 3] Q _S = K _S · I _S (I _S : load current of supply reel drive motor) (K _S : torque constant of supply reel drive motor)

Then, in the above formula 2, the tape 6
Runs at a constant speed by the capstan, so ω _S is considered to be substantially 0 at a certain moment, and the following formula 4 is approximately established.

[0020]

[Equation 4] T _S · r _S −Q _S = 0

The equation for obtaining the tape tension T _S from the above equations 1 to 4 is given by the following equation 5.

[0022]

[Formula 5] T _S = Q _S / r _S = K _S · I _S · 2π · f _FG / V _S · N

FIG. 2 is a block diagram showing a schematic configuration of the tape tension control device. The target value T _O is calculated by comparing T _S calculated by the above formula 5, the difference (deviation) is multiplied by the gain constant G, and the value is added to the initial control voltage E ₀ to obtain the control amount (control Output as voltage E _S.
The control amount E _S is converted into an analog signal (voltage) by the D / A converter 7, and this voltage is supplied to the drive circuit 9 to control the reel drive motor 2.

Specifically, if it is determined as a result of the above comparison that the tape tension is smaller than the target value, the voltage applied to the supply reel drive motor 2 is increased to increase the back torque of the supply reel 4. If it is determined that the tape tension is larger than the target value, control is performed such that the voltage applied to the supply reel drive motor 2 is lowered to reduce the back torque of the supply reel 4. The initial control voltage E ₀ is measured so as to have a predetermined tension in advance and is stored as data in the storage unit of the microcomputer 1 (it may be a value at a certain winding diameter). Of course, the known quantities such as V _S , N and K _S are also stored in the storage unit of the microcomputer 1.

According to the above construction, since no mechanical member such as a tape tension detecting arm is required, an increase in the number of parts and complication of the mechanism can be avoided, and the tape running load can be reduced. Further, even if the tape is greatly loosened due to some trouble, there is no possibility of scratching the tape 6.

The tape 6 is used for playing or reverse Play.
At y, etc., the capstan runs at a constant speed, but in addition, the tape running speed may be controlled to be constant during rewinding or fast-forwarding. The tape tension of this invention can be detected.

In the above description, the case where the supply reel 4 serves as the tape delivery side reel has been described. For example, at the time of reverse play, the take-up reel 5 serves as the tape delivery side reel, so that the take-up reel drive motor. For 3 as well, load current detection and FG cycle detection are performed, and reverse P
The tape tension can be controlled even when the tape is laid.

[0028]

As described above, according to the present invention, it is possible to eliminate various drawbacks such as an increase in the number of parts, a complicated mechanism, an increase in tape running load, and a scratch on the tape due to some trouble.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a tape tension control device of the present invention.

FIG. 2 is a schematic block diagram of a tape tension control device of the present invention.

[Explanation of Codes] 1 Microcomputer 2 Supply reel drive motor 3 Take-up reel drive motor 4 Supply reel 5 Take-up reel 6 Tape 7,8 D / A converter 9,10 Motor drive circuit

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[Procedure amendment]

[Submission date] April 14, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

[Formula 2] J _S · β _S = T _S · r _S −Q _S (J _S : reel inertia) (T _S : tape tension) (Q _S : reel back torque) (β _S : supply reel angle acceleration)

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

Then, in the above formula 2, the tape 6
Runs at a constant speed by the capstan, so β _S is considered to be approximately 0 at a certain moment, and the following formula 4 is approximately established.

Claims (1)

[Claims] 1. A means for detecting an FG signal from a motor for driving a reel on the tape feeding side, a means for detecting a load current from the reel driving motor, and a tape feeding by a constant tape running speed and the FG signal. Means for calculating the tape winding diameter of the reel on the side, means for calculating the tape tension during tape running based on the calculated tape winding diameter and the detected load current, and the calculated tape tension and preset values. Means for controlling the voltage applied to the reel drive motor on the basis of the result of comparison with the target tape tension.