JPH06150453A - Reel driving device and vtr provided with the same - Google Patents

Abstract

PURPOSE:To evade the occurrence of tape damage, etc., by deciding an abnormality in the change of loss torque with the passage of time. CONSTITUTION:A change-over switch 33 is connected to (a) side, and a reel motor 3 is rotated at constant rotating speed in a state that no tape is loaded. A current MIs flowing through the motor 3 can be detected by a control signal SCs from a speed servo circuit 23. The current MIs is in proportion to the loss torque MTs, and since the aging change of the loss torque MTs can recognized by comparing with a current MIsr detected similarly on a manufacturing line, the abnormality in the loss torque MTs can be decided from the current MIs. When the current MIs exceeds a prescribed range, it is decided that the abnormality occurs in the loss torque MTs. When the abnormality is decided, the constant of an approximate equation which computes a current I is set agains, or a VTR is controlled so as to go down when tape tension F is controlled so as to be kept constant by connecting the change-over switch 33 to (b) side and making the current I in accordance with the a tape winding diameter R flow on the motor 3 by a current servo circuit 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reel driving device and a VTR having the reel driving device.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a tape traveling system of a known VTR and shows a loading state. In the figure, 1 is a reel stand on the supply side, 2 is a reel stand on the take-up side, 3 is a reel motor, 4 is a swing gear for transmitting the driving force of the reel motor 3 to the reel stands 1 and 2, and 5 is a swinging gear. A drum, 6 is a capstan, 7 is a pinch roller, and 8 is a tape. The reel base 2 on the take-up side has a torque limiter utilizing, for example, friction coupling between the drive source and the drive destination, and is configured to prevent the tape 8 from being subjected to excessive tension F. There is.

When the tape 8 is run in the forward direction (FWD), by rotating the reel motor 3 clockwise, the swing gear 4 is engaged with the reel base 2 on the winding side, and the reel base 2 is clocked. It will be rotated around. On the other hand, when the tape is run in the reverse direction (RVS), by rotating the reel motor 3 counterclockwise (CCW), the swing gear 4 meshes with the reel base 1 on the supply side, and the reel base 2 moves. It will rotate counterclockwise.

By keeping the tape tension F at the P portion constant while the tape is running, a good head output can be obtained and the tape damage due to the tape guide or the like can be prevented to improve the reliability of the tape path. be able to.

Conventionally, in order to keep the tape tension F constant, the forward (FWD) system tape tension control is performed by a mechanical tension regulator, and the reverse (RVS) system tape tension control drives the reel stand. It has been proposed to use a current servo system that controls the current flowing through the reel motor 3 according to the tape winding diameter.

As is well known, since the current I flowing through the reel motor 3 and the torque generated by the motor are in a proportional relationship, if the tape winding diameter (radius) is R, the tape tension is F, and the torque generated by the reel stand is Tr. , The relationship of Formula 1 is satisfied.

[0007]

[Equation 1]

Considering mechanical loss and electrical loss, it can be expressed as shown in Equation 2. Where K1, K
2, A and B are constants, and A = K1 × F and B = K2. The mechanical loss includes a loss of the reel motor 3, a loss of the swing gear 4 that transmits the driving force from the reel motor 3 to the reel bases 1 and 2, a loss of the reel bases 1 and 2 and the like, and a current detection circuit as an electrical loss. There is an error etc.

[0009]

[Equation 2]

As is clear from the equation (2), in order to make the tape tension F constant, the motor current should be changed according to the tape winding diameter R. Tape winding diameter R
Is calculated from the reel rotation period and the tape speed as described in Japanese Patent Publication No. 58-17992. That is, if the tape winding diameter of the supply reel is RS, its rotation cycle is TS, the tape winding diameter of the take-up reel is RT, its rotation cycle is TT, the tape speed is V, and the total area of the tape 8 and the reel hub is AA, The relational expression of Equation 3 can be obtained. Although detailed description is omitted, the tape winding diameters RS and RT can be calculated from these relational expressions if the reel rotation periods TS and TT and the tape speed V are known.

[0011]

[Equation 3]

FIG. 5 shows a tape tension control device for controlling the tape tension F to be constant by controlling the current I flowing through the reel motor 3 for driving the reel base 1 in the reverse system according to the tape winding diameter R. There is.

In the figure, 11 is a microcomputer (hereinafter referred to as "microcomputer"). This microcomputer 1
1 is supplied with frequency signals SFG and TFG from a frequency generator (not shown) attached to the reel stand 1 on the supply side and the reel stand 2 on the winding side, and is also attached to the capstan 6. Frequency generator (not shown)
The frequency signal CFG from is supplied. Then, the microcomputer 11 obtains the reel rotation cycles TS and TT from the frequency signals SFG and TFG, and also obtains the frequency signal CFG.
By obtaining the tape speed V, the tape winding diameters RS and RT are calculated.

In the microcomputer 11, the tape winding diameter Rs of the supply reel 1 is used as the tape winding diameter R, and the tape winding diameter R
The current I (see the equation 2) corresponding to is calculated, and the calculated value is supplied to the PWM modulation circuit 12 in the microcomputer 11 as the control signal SCi. A PWM signal corresponding to the control signal SCi is output from the PWM modulation circuit 12, and the PWM signal is smoothed by the low pass filter 13 and then supplied to the constant current drive circuit 14. As a result, the current I corresponding to the tape winding diameter R is applied to the reel motor 3 that drives the reel base 1.
Is controlled so that the tape tension F becomes constant.

[0015]

By the way, as described above, when the tape tension F is controlled to be constant by applying a current I corresponding to the tape winding diameter R calculated by the equation 2 to the reel motor 3, When there is a mechanical loss such as the loss of the reel bases 1 and 2 related to the constant B of 2, the loss of the reel motor 3, the loss of the swinging gear 4, that is, when the loss torque changes with time,
The tape tension F cannot be controlled constantly. That is, when the loss torque increases, the tape tension F becomes small and a good head output cannot be obtained. On the other hand, when the loss torque decreases, the tape tension F becomes large and the tape is damaged by the tape guide or the like.

Therefore, the present invention provides a reel drive device capable of determining an abnormality due to a change in loss torque over time, and a VTR capable of avoiding inconveniences such as occurrence of tape damage due to an abnormality in loss torque.

[0017]

According to a first aspect of the present invention, there is provided a reel drive device, in which a reel motor for driving a reel base without a tape is rotated at a constant rotation speed to detect a current flowing through the reel motor. Means and torque determining means for determining whether the loss torque is abnormal based on whether or not the current detected by the current detecting means is within a predetermined range.

A VTR according to a second aspect of the present invention is a VTR having the reel drive device of the first aspect of the present invention, in which an operation prohibiting means for prohibiting an operation such as recording / reproducing when the torque determining means determines that the loss torque is abnormal. Is provided.

A VTR according to a third aspect of the present invention is a VTR having the first reel drive device, wherein cassette loading prohibiting means for prohibiting loading of the tape cassette is provided when the torque determining means determines that the loss torque is abnormal. It will be.

[0020]

In the first aspect of the invention, the current detected by the current detecting means is proportional to the loss torque, and this detected current changes with the aging of the loss torque. Therefore, the torque determination means can determine the loss torque abnormality based on whether or not the detected current is within a predetermined range. here,
The predetermined range can be determined based on, for example, a current detected in a similar state on the manufacturing line.

In the second and third aspects of the invention, when the loss torque is abnormal, the operation such as recording / reproducing is prohibited or the loading of the tape cassette is prohibited.
It is possible to avoid occurrence of tape damage due to abnormal loss torque.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, the frequency signal RFG output from the frequency generator 21 is amplified and waveform-shaped by the sensor amplifier 22, and then the speed servo circuit 31 of the microcomputer 11 is used.
Is supplied to. The speed servo circuit 31 is for controlling the rotation speed of the reel motor 3 to be constant. The speed servo circuit 31 detects the rotation speed of the reel motor 3 from the frequency signal RFG, and outputs a control signal SCs for controlling the current I flowing through the reel motor 3 so that the rotation speed becomes equal to the set value. It The control signal SCs is supplied to the fixed terminal on the side a of the changeover switch 33.

Reference numeral 32 is a current servo circuit for controlling the tape tension F to be constant by causing a current corresponding to the tape winding diameter R to flow through the reel motor 3. From the current servo circuit 32, the calculated value of the current I (see the equation 2) according to the tape winding diameter R is output as the control signal SCi. The control signal SCi is supplied to the fixed terminal on the b side of the changeover switch 33.

The changeover switch 33 is connected to the b side when the tape tension F is controlled to be constant in the reverse system,
On the other hand, when determining the loss torque abnormality, it is connected to the side a. The output signal of the changeover switch 33 is the PWM modulation circuit 12
The PWM modulation circuit 12 outputs a PWM signal corresponding to the output signal of the changeover switch 33.

The present example is constructed as described above, and the other parts are constructed similarly to the example of FIG.

In the present example, when the tape tension F is controlled to be constant in the reverse system, the changeover switch 33 is switched to the b side, so that the current I (see Formula 2) corresponding to the tape winding system R in the reel motor 3 is shown. ) Is controlled so that the tape tension F becomes constant as in the example of FIG.

When it is determined that the loss torque is abnormal, the changeover switch 33 is changed over to the "a" side, so that the reel motor 3 is controlled to rotate at a constant rotation speed. In this case, as shown in FIG. 3, the reel motor 3 is rotated counterclockwise with no tape (unloading state). 3, parts corresponding to those in FIG. 4 are shown with the same reference numerals.

In this state, the control signal SCs corresponds to the current I flowing through the reel motor 3, so that the current MIs is detected from the control signal SCs. The current MIs thus detected is proportional to the loss torque MTs obtained by adding the loss torque RL of the reel motor 3, the loss torque KL of the swing gear, and the loss torque SL of the supply-side reel stand 1 (see Formula 4). .

[0030]

[Equation 4]

Therefore, for example, when the constants A and B (see Formula 2) in the manufacturing line are set, by comparing with the current MIsr detected in the same state, the change over time of the loss torque MTs can be known, and the loss torque MTs can be known. The abnormality of can be judged.

In this example, when the current MIs detected as described above exceeds the range of MIsr-Δia to MIsr + Δia, that is, the current I corresponding to the tape winding diameter R is calculated by the formula (2). If the tape tension F deviates from the target value and tape damage or the like may occur when controlling the tension F to be constant, it is determined that the loss torque MTs is abnormal.

When the deviation of the current MIs from the current MIsr is small and the change over time of the loss torque MTs is small, a constant of the equation 2 is set according to the magnitude and direction of the deviation so that the tape tension F is controlled to a target value. B is reset. When the deviation is large and the loss torque MTs changes with time, the VTR system is shut down. That is, (MIsr−Δib) ≦ MIs <(MIs
r−Δia), (MIsr + Δia) <MIs ≦ (MIsr +
When Δib), the constant B is reset and MI
When s <(MIsr−Δib), (MIsr + Δib) <MIs, the VTR is system down (see FIG. 2). As the system down of the VTR, it is possible to prohibit operations such as recording and reproduction, and prohibit loading of the tape cassette. The warning may be given visually or audibly.

Thus, in this example, the loss torque M
An abnormality due to a change with time of Ts can be favorably determined. Then, when the change with time of the loss torque MTs is small, the constant B of Formula 2 is reset, so that the current I corresponding to the tape winding diameter R is calculated by the formula of Formula 2 so that the tape tension F becomes constant. Even if the loss torque MTs changes over time during control, the tape tension F can be set as a target value. Further, when the loss torque MTs changes significantly with time, the system of the VTR is shut down, so that the occurrence of tape damage or the like due to an abnormality in the loss torque MTs can be favorably avoided.

Although the above embodiment focuses on the supply reel side, the abnormality of the loss torque MTT on the take-up reel side can be similarly determined. That is, there is no tape (unloading state)
Thus, the reel motor 3 is rotated clockwise.

In this state, the control signal SCs corresponds to the current I flowing through the reel motor 3, so that the current MIt is detected from the control signal SCs. The current MIt thus detected is proportional to the loss torque MTt obtained by adding the loss torque RL of the reel motor 3, the loss torque KL of the swing gear, and the loss torque TL of the reel base 2 on the winding side (see Formula 5). ).

[0037]

[Equation 5]

Therefore, for example, in the manufacturing line, by comparing with the current MItr detected in the same state, it is possible to know the change over time of the loss torque MTt, and it is possible to determine the abnormality of the loss torque MTt.

For example, the current M detected as described above
When It exceeds the range of MItr−Δia to MItr + Δia, that is, when there is a risk of tape damage due to a change in loss torque MTt, loss torque M
It is assumed that Tt is abnormal. When it is determined that the loss torque MTt is abnormal as described above, for example, VT
The system of R is shut down, and the occurrence of tape damage is avoided.

[0040]

According to the first aspect of the present invention, the current detected by the current detection means is proportional to the loss torque, and this detection current changes with the lapse of time of the loss torque. It is possible to satisfactorily determine the abnormality of the loss torque based on whether or not is within a predetermined range, and it is possible to avoid the occurrence of tape damage or the like due to the abnormality of the loss torque.

According to the second and third inventions, when the loss torque is abnormal, the operation such as recording and reproducing is prohibited,
Alternatively, since loading of the tape cassette is prohibited, it is possible to avoid occurrence of tape damage due to abnormal loss torque.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining abnormality determination of loss torque.

FIG. 3 is a diagram showing a tape running system of a VTR without a tape (unloading state).

FIG. 4 is a diagram showing a tape traveling system (loading state) of a VTR.

FIG. 5 is a configuration diagram showing a tape tension control device.

[Explanation of symbols]

 1 Reel Side on Supply Side 2 Reel Side on Winding Side 3 Reel Motor 4 Swing Gear 5 Drum 6 Capstan 7 Pinch Roller 8 Tape 11 Microcomputer 12 PWM Modulation Circuit 13 Low Pass Filter 14 Constant Current Drive Circuit 21 Frequency Generator 22 Sensor amplifier 31 Speed servo circuit 32 Current servo circuit 33 Changeover switch

Claims (4)

[Claims] 1. A current detecting means for detecting a current flowing through the reel motor by rotating a reel motor for driving a reel stand without a tape at a constant rotation speed, and a current detected by the current detecting means is predetermined. A reel drive device, comprising: torque determination means for determining abnormality of loss torque depending on whether or not the torque is within a range. 2. The reel drive device according to claim 1, wherein the reel base has a torque limiter between a drive source and a drive destination. 3. A VTR having the reel drive device according to claim 1, further comprising operation prohibiting means for prohibiting an operation such as recording / reproducing when the torque determining means determines that the loss torque is abnormal. 4. A VTR having the reel drive device according to claim 1, further comprising cassette loading prohibiting means for prohibiting loading of a tape cassette when the torque determining means determines that the loss torque is abnormal.