JPH07210929A - Running drive device for magnetic tape - Google Patents

Abstract

PURPOSE:To minimize the damage of a tape by detecting that the twining of magnetic tape round a capstan is generated, when the input level from a detecting head is decided as less than a predetermined level. CONSTITUTION:When the output of a comparator 44 is in the state of H-level, the output level of a sound recording/reproducing head 5 at the spot where the decrease of the output level is detected by the detecting head 8 of the FF side, is regarded as equal to the output level of the head 8 or below at the same spot, and the decision is made that the twining state of the tape is generated. Then, the driving of the running drive device 2 is once stopped, and a capstan motor 53 is driven for the inverse rotation during the predetermined time. When the output of a comparator 46 at the FF side is in the state of H-level, the magnetic tape 3 is come into contact with the head 8 by a specific pressure, and the decision is made that the twining state is released. Thus, the twining state is prevented from developing since the driving of each motor is stopped when the twining is not released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape traveling drive device which is preferably used for preventing winding of a magnetic tape in a tape recorder.

[0002]

2. Description of the Related Art In a reproducing state of a cassette tape recorder loaded with a cassette tape containing a magnetic tape, the rotation speed of the reel stand on the winding side is the speed at which the magnetic tape is driven by a capstan and a pinch roller. The magnetic tape is set to be wound up on the reel on the winding side at a speed slightly higher than that of the take-up side, and the magnetic tape on the downstream side of the capstan in the traveling direction of the magnetic tape has a structure that does not cause slack.

However, when the rotational speed of the reel stand on the take-up side is undesirably lowered or when the tape recorder is regenerated with the magnetic tape on the reel on the take-up side sagging, Since the winding speed of the reel is slower than the speed at which the capstan and the pinch roller are driven to run, slack occurs in the magnetic tape on the downstream side of the capstan. At this time, the slack magnetic tape may be wound around the capstan, and the magnetic tape may be greatly damaged.

The detection of winding that occurs in this way is
In a typical conventional technique, the rotation of the magnet provided on the reel on the winding side is stopped based on a pulse generated from a magnetic detection element provided adjacent to the reel, and rotation of the reel is stopped by winding the magnetic tape. This is achieved by detecting abnormal rotation of the reel on the winding side, such as reverse rotation of the reel due to being wound up.

However, since the shaft diameter of the capstan is considerably smaller than the reel diameter on the winding side, the magnetic tape is already wound around the capstan when the reel rotation stop or reverse rotation is detected. Is inevitable.

In order to solve such a problem, a method of detecting slack using a tension sensor is disclosed in Japanese Patent Laid-Open No.
77203. FIG. 6 is a plan view schematically showing a cassette tape recorder 60 including the tension sensor 65. The cassette tape recorder 60 generally includes a recording / reproducing head 61, a capstan 62, a pinch roller 63, a reel base 64, and a tension sensor 65. The recording / playback head 61, the erasing head 66, and the tension sensor 65 are attached to a head base 67, and the head base 67 is attached to the magnetic tape 70 in the arrow direction indicated by reference numeral 68. By moving closer and farther,
The recording / reproducing state or the stopped state on the magnetic tape 70 is set. A magnetic tape 70 is sandwiched between the capstan 62 and the pinch roller 63. The magnetic tape 70 is driven by a capstan motor (not shown) to rotate the magnetic tape 70, and a reel base 64 (not shown) drives a reel motor. By being driven to rotate by, it is wound up by the hub 74 on the winding side. In the normal reproduction state, the magnetic tape 70 travels on the track indicated by the solid line 73, that is, on the downstream side of the pinch roller 63 in the running direction of the magnetic tape 70 indicated by the arrow 71 without sagging. The magnetic tape 70 delivered from the pinch roller 63 and the capstan 62 is wound up on the reel base 64 on the winding side.

For the above-mentioned reason, the magnetic tape 70 is moved along the locus indicated by the two-dot chain line 69 in FIG.
When the slack occurs, the swing shaft 65a of the tension sensor 65 swings counterclockwise by an angle θ in response to a change in the traveling path of the magnetic tape 70, as indicated by the two-dot chain line 72 in the figure. It moves dynamically. When it is determined that the value of the angle θ detected by the detection element 65b realized by a Hall element or an optical sensor that detects the displacement amount of the swing shaft 65a exceeds a predetermined value, automatic stop (not shown) is performed. The circuit operates and stops the playback operation.

In this way, the magnetic tape 70 is prevented from being wound around the capstan 62.

[0009]

SUMMARY OF THE INVENTION In the above-mentioned prior art,
The slack of the magnetic tape 70 is detected by the detection circuit from the swing shaft 65a of the tension sensor 65 through the detection element 65b. The time from the occurrence of slack to the detection of entrainment depends on the length of the swing shaft 65a and the detection element 65b.
It depends on the response performance of. Therefore, it is necessary to use the Hall element, the optical sensor, or the like as the detection element in order to increase the detection accuracy of the winding, and the apparatus becomes expensive.

Further, it is difficult to provide the tension sensor 65 having a large occupied space in the vicinity of the pinch roller 63 having a small space, and furthermore, from the opening window for the pinch roller 63 in the cassette half to the swing shaft 65a. It is difficult to face such a displacing member.

It is an object of the present invention to provide a magnetic tape running drive device capable of detecting slack of a magnetic tape at an early stage and preventing winding of the magnetic tape around a capstan.

[0012]

In the present invention, the control means is
The magnetic tape runs by driving the capstan motor to run the magnetic tape at a predetermined speed, and also driving the reel motor to wind the magnetic tape through the capstan and pinch rollers on the reel that is the winding side. In the drive device, a detection head provided near the downstream side of the capstan in the running direction of the magnetic tape and a first comparison means for comparing the output level of the detection head with a predetermined level are provided, and the control means is provided. When the input level from the detection head is determined to be less than a predetermined level in the first comparing means, it is detected that the magnetic tape is wrapped around the capstan. It is a traveling drive device.

Further, the present invention relates to a reproducing head, a second comparing means for comparing an output level of the reproducing head with a predetermined level, and a distance between the reproducing head and the detecting head for an output of the second comparing means. A delay means for delaying the running time of the magnetic tape corresponding to the difference is provided, and the control means determines that the input level from the detection head is less than a predetermined level by the first comparison means, and the second comparison means. When it is determined that the input level from the reproducing head is equal to or higher than a predetermined level, the occurrence of wrapping of the magnetic tape around the capstan is detected.

Further, when the winding is detected, the control means of the present invention reverses the capstan motor for a predetermined time, and when the winding is not canceled by this, driving of each motor is stopped. It is characterized by

[0015]

According to the present invention, the control means drives the capstan motor to run the magnetic tape at a predetermined speed, and drives the reel motor to move the reel to the winding side to the capstan and the pinch roller. Let's wind the magnetic tape through. A detection head is provided in proximity to the downstream side of the capstan in the traveling direction of the magnetic tape, and the detection head reads the magnetic signal recorded on the magnetic tape. In the first comparison means, the output level of the detection head is compared with a predetermined level, and when it is determined that the output level of the detection head is less than the predetermined level, the control means It is judged that the traveling path of the magnetic tape changed due to the magnetic tape being wrapped around the capstan, and the detection head signal was no longer output. In this way, the winding of the magnetic tape around the capstan is detected.

Therefore, it suffices to provide the detection head in the vicinity of the capstan, and the size and cost of the structure can be reduced. Further, the detection speed can be further improved as compared with the configuration using the reel pulse as described above.

Preferably, in the second comparing means,
The output level of the reproducing head is compared with a predetermined level. The output of the second comparing means is delayed by the delay means by the running time of the magnetic tape corresponding to the distance difference from the reproducing head to the detecting head. In the first comparing means, it is determined that the output level of the detection head is less than a predetermined level, and in the second comparing means,
When it is determined that the output level of the reproducing head is equal to or higher than the predetermined level, the control means detects the winding of the magnetic tape around the capstan.

Therefore, only the portion of the magnetic tape where the signal of a predetermined level or higher is recorded is the object of the winding detection, and the erroneous detection at the non-signal portion can be prevented.

Further preferably, the control means is
When wrapping is detected, the capstan motor is rotated in the reverse direction for a predetermined time, and if the wrapping is not resolved by this, driving of each motor is stopped to prevent the wrapping from expanding.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic plan view showing a traveling drive device 2 of a cassette tape recorder 1 according to an embodiment of the present invention. A half of the cassette tape 4 containing the magnetic tape 3 is shown by a chain double-dashed line, and a part of its internal structure is shown by a solid line. The traveling drive device 2 has an auto-reverse function, and roughly includes a recording / playback head 5, an erasing head 6, and
7 and a head base 10 to which the FF side detection head 8 and the FR side detection head 9 according to the present invention are attached, capstans 11 and 12, pinch rollers 13 and 14, reel shafts 15 and 16, and the like. It

When the cassette tape 4 is loaded in the cassette tape recorder 1, the reel shafts 15 and 16 are fitted into the hubs 17 and 18 of the cassette tape 4, respectively, and at the same time, the capstans 11 and 12 are formed on the case. Insert into the through hole. A recording / reproducing head 5 is attached to a central portion of the head base 10 in the width direction, and the recording / reproducing head 5 is erased in sequence on the downstream side of the magnetic tape 3 indicated by an arrow 21 in the running direction of the recording / reproducing head 5. Head 6, FF side detection head 8
The erasing head 7 and the FR side detecting head 9 are also arranged in this order on the upstream side in the traveling direction 21. The detection heads 8 and 9 face between the pinch rollers 13 and 14, the capstans 11 and 12, and the reel shafts 15 and 16, respectively.

When a reproducing button (not shown) is operated, the head base 10 is displaced closer to the cassette tape 4, and the recording / reproducing head 5, the erasing heads 6, 7 and the detecting head 8,
9. The pinch roller 13 contacts the magnetic tape 3, respectively. The magnetic tape 3 is pinched and supported by the capstan 11 and the pinch roller 13, and the reel shaft 15 on the winding side.
Then, the capstan 11 is rotationally driven in the direction of the arrow 21 by the motors 55 and 53 (shown in FIG. 3), and is wound onto the hub 17 on the winding side. In this way, the magnetic tape 3 can be reproduced.

When the rotation speed of the take-up reel shaft 15 is reduced or stopped, or when the magnetic tape 3 wound around the take-up hub 17 is slack from the beginning, the capstan 11 is used. The speed at which the hub 17 on the winding side winds up the magnetic tape 3 is slower than the speed at which the pinch roller 13 and the pinch roller 13 feed the magnetic tape 3. Therefore, as shown in FIG. Slack occurs in the magnetic tape 3.

When the slack is generated in the half of the cassette tape 4, even if the reel shaft 15 rotates, the rotational force is consumed to eliminate the slack, and the tension applied to the magnetic tape 3 for winding up. Disappears. When the cassette tape recorder 1 is brought into a reproducing state in such a state, the magnetic tape 3 fed from the pinch roller 13 surrounds the outer peripheral surface of the capstan 11 and eventually the capstan 11.
Will be wrapped around.

In the case where the cassette tape recorder 1 is mounted on a vehicle, if the magnetic tape 3 is wound around the capstan 11, the device must be removed and repaired, which is very troublesome.

FIG. 3 is an electric block diagram of the traveling drive device 2. In the reproducing state of the cassette tape recorder 1 when the magnetic tape 3 is driven in the direction in which the magnetic tape 3 is wound around the hub 17 and is driven in the forward direction, the magnetic signal recorded on the magnetic tape 3 is recorded by the recording / reproducing head 5. Read. The recording / reproducing head 5 has head cores 31 and 32 so that magnetic signals can be read from the respective tracks of the magnetic tape 3 in the forward and reverse directions. The head cores 31 and 32 convert the magnetic signal into an electric signal and output it as a reproduction signal to the channel switching circuit 33. The channel switching circuit 33 selects and outputs the electric signal from the head core 31 or 32 corresponding to the forward / reverse traveling drive, and supplies it to the equalizer amplifier 35.

Equalizer amplifier 35 used here
Is for flattening the frequency characteristic and expanding the dynamic range when reproducing the magnetic signal recorded on the magnetic tape 3. The AC signal restored by the equalizer amplifier 35 is supplied to the head amplifier 37.
Thus, the voltage is amplified to a voltage sufficient as an input for the main amplifier and output. This AC signal is output from the head amplifier 37 as an audio signal via the audio output terminal 38.

The reproduced signals from the head cores 31 and 32 are both given to the rectifier circuit 42. Rectifier circuit 42
Is configured to include a diode, a capacitor, etc., and after rectifying and smoothing the AC playback signal into a DC signal,
This DC signal is output to the non-inverting input terminal of the comparator 44.

The comparator 44 has a reference voltage from the reference voltage source 40 applied to its inverting input terminal and the rectification circuit 42.
It is an arithmetic unit that compares the output voltage of the above with the output voltage of, and selects and outputs a binary signal according to the comparison result. The reference voltage of the reference voltage source 40 is set corresponding to a predetermined magnetic signal level, and the comparator 44 includes head cores 31 and 3.
When the reproduction signal level from 2 is above the reference voltage, a high level output is derived, and when it is below the reference voltage, a low level output is derived.

When the magnetic tape 3 is running in the normal direction, the reproduction signal from the magnetic tape 3 is detected not only by the recording / reproducing head 5 but also by the FF side detection head 8. FF
The side detection head 8 converts the magnetic signal recorded on the magnetic tape 3 into an electric signal, and supplies the electric signal to the rectifier circuit 45 via the equalizer amplifier 41. The rectifier circuit 45 converts the electric signal into a DC signal and then outputs the DC signal to the non-inverting input terminal of the FF side comparator 46.

Further, in the reproduction state of the tape recorder 1 during the reverse running drive in which the magnetic tape 3 is driven in the direction in which it is wound around the hub 18, the recording / reproducing head 5 and the FR side detection head 9 together with the magnetic tape 3 are used. The magnetic signal of is detected. The magnetic signal detected by the FR-side detection head 9 is applied to the non-inverting input terminal of the FR-side comparator 48 as a DC signal via the equalizer amplifier 43 and the rectifier circuit 47 in the same process as in the normal rotation driving described above. Is entered. The reference voltage from the reference voltage source 40 is applied to the inverting input terminals of the comparators 46 and 48.

The output from the comparator 44 is the delay circuit 5
It is input via 0 to the signal processing circuit 51 realized by a microcomputer or the like. The delay circuit 50 is for recording /
The time W corresponding to the distance difference between the reproducing head 5 and the detecting head 8 or 9 located on the downstream side in the traveling direction of the magnetic tape 3.
Only, the output of the comparator 44 is delayed. In addition, the comparator 46,
The output of 48 is directly given to the signal processing circuit 51.

The signal processing circuit 51 includes the comparators 44,
The winding determination is performed according to the comparison result of 46 and 48, and the drive signal is given to the drive circuit 52 according to the determination result. The drive circuit 52, which is a control means, responds to the drive signal by driving the capstan motors 5 on the FF side / FR side respectively.
Drive currents are output to the motors 3, 54 and the reel motors 55, 56 to control the capstan motors 53, 54 and the reel motors 55, 56.

FIG. 4 is a timing chart for explaining the winding detection operation by the signal processing circuit 51 when the traveling drive device 2 is driven in the normal direction. FIG. 4 (1) is a diagram showing a recording state of the magnetic tape 3, and FIG.
The magnetic signal of the magnetic tape 3 detected by the reproducing head 5 is shown, and FIG. 4 (5) shows the magnetic signal detected by the FF side detection head 8.

Reference marks TrA, Tr in the magnetic tape 3
In each track shown by B, an area in which a magnetic signal shown by hatching is recorded and an area in which a magnetic signal not hatched is not recorded are sequentially formed along the traveling direction 21. ing. When the magnetic signal recorded on the track TrA is reproduced by the core 31 of the recording / reproducing head 5, an output as shown in FIG. 4 (2) is obtained corresponding to the presence or absence of the magnetic signal. When this output is level discriminated by the comparator 44, it becomes as shown in FIG. 4C, and thus an output corresponding to the presence or absence of a magnetic signal can be obtained. The output of the comparator 44 is delayed by the time W in the delay circuit 50 and input to the signal processing circuit 51, as shown in FIG.

On the other hand, the FF side detection head 8 uses the recording / recording
It is arranged on the downstream side in the running direction 21 of the magnetic tape 3 by a distance corresponding to the time W from the reproducing head 5, and therefore the output reproduced from the track TrA is as shown in FIG.
As shown in (5), the output is delayed by the time W. This output is level discriminated by the comparator 46, converted into a signal indicating the presence or absence of a magnetic signal as shown in FIG. 4 (6), and input to the signal processing circuit 51.

The signal processing circuit 51 transfers data to the capstan 11 of the magnetic tape 3 during the period when the magnetic signal is detected by the FF side detection head 8 before time t2 and at times t3 to t4 in FIG. 4 (6). It is judged that no winding has occurred.

Even if the magnetic signal is no longer detected as shown between the times t2 and t3, if the delay output of the detection result of the recording / reproducing head 5 shown in FIG. It is determined that winding does not occur and no magnetic signal is recorded.

On the other hand, as shown after time t4, although no magnetic signal is detected from the detection result of the FF side detection head 8, a magnetic signal is detected from the delayed output of the detection result of the recording / reproducing head 5. 4 (7), the winding detection flag is set to 1 to drive the capstan 11 in the reverse rotation direction, and
The reel bases 17 and 18 are driven to eliminate the winding. After that, the wrapping is detected again as described above, and when the wrapping is eliminated, the flag is reset to 0.

FIG. 5 is a flow chart showing the winding detection operation of the magnetic tape 3 by the signal processing circuit 51 as described above. In step s1, as a result of the comparison between the output level of the FF side detection head 8 in the FF side comparator 46 and the predetermined level, the output level is equal to or higher than the predetermined level, that is, the output of the FF side comparator 46 is at the high level. In some cases, the normal playback state, ie magnetic tape 3
Is determined to be in contact with the FF side detection head 8 at a prescribed pressure, and step s1 is repeated.

On the other hand, when the output level is less than the predetermined level, that is, when the output of the FF side comparator 46 is at the low level, the magnetic tape 3 detects the FF side detection head 8.
It is determined that the recording / playback head 5 located on the upstream side in the running direction 21 of the magnetic tape 3 is judged to have risen, that is, it is possible that slack has occurred. To be judged.

As a result of the judgment in step s2, when the output level is less than the predetermined level, that is, when the output of the comparator 44 is low level, the detection results of the heads 8 and 5 coincide with each other, therefore The decrease in the output level in step s1 is accompanied by the decrease in the level of the magnetic signal recorded on the track TrA, is judged to be a normal reproduction state, and the process returns to step s1.

On the other hand, when the output level is equal to or higher than the predetermined level in step S2, that is, the output of the comparator 44 is high level, the FF side detection head 8 lowers the output level in step s1. It means that the output level of the recording / playback head 5 at the point where the detection is detected is equal to or higher than the output level of the FF side detection head 8 at the same point, it is determined that the winding has occurred, and the process proceeds to step s3.

In step s3, the drive of the traveling drive device 2 is temporarily stopped, and in step s4, the capstan motor 53 is reversely driven for a predetermined time.

In step s5, as a result of comparison between the output level of the FF side comparator 46 and the predetermined level, the output level is equal to or higher than the predetermined level, that is, the output of the FF side comparator 46 is high level. , The magnetic tape 3 is in contact with the FF side detection head 8 at a prescribed pressure,
It is determined that the winding has been released, and the process returns to step s1.

However, when the output level is less than the predetermined level, that is, when the output of the FF side comparator 46 remains at the low level, the magnetic tape 3 is separated from the FF side detection head 8 due to winding. Is determined to continue and the operation ends.

When the magnetic tape 3 is traveling in the direction opposite to the traveling direction 21, the FR side detection head 9 and the core 32 of the recording / reproducing head 5 are used to detect the winding around the capstan 12. .

As described above, in this embodiment, the capstan 1 of the magnetic tape 3 is used by using the relatively small detecting heads 8 and 9.
Since the winding around 1 and 12 is detected, the occupied space of the structure for detecting winding around the head base 10 of the detection heads 8 and 9 is smaller than that when the tension sensor as described in the section of the prior art is used. The cost can be reduced while the size can be reduced. Further, since the detection of winding around by the detection heads 8 and 9 has better response performance than the detection based on the rotation pulse of the reel shafts 15 and 16,
Winding can be detected quickly, and damage to the magnetic tape 3 can be minimized.

It should be noted that the opposite track T is attached to the detection heads 8 and 9.
A core for detecting each of rB and TrA is provided, a signal is not recorded on the magnetic tape 3, and the detection head 8,
Track T based on the detection result of 9 and the recording / playback head 5
When the detection results of rA and TrB are the same, the winding determination may be performed by further utilizing the detection results of the opposite tracks TrB and TrA by those cores.

Further, as described above, the detection heads 8 and 9 have equalizer amplifiers 41 and 43 and a rectification circuit 4, respectively.
5, 47 and comparators 46 and 48 are provided, the recording / playback head 5 is another example of this embodiment.
Similarly, a channel switching circuit is provided to detect the detection heads 8,
By selectively extracting the output from 9, the equalizer amplifier, the rectifier circuit, and the comparator can be omitted in one system.

[0051]

As described above, according to the present invention, since the detection head is used for detecting the winding of the magnetic tape around the capstan, the winding head is wound as compared with the conventional tension sensor. It is possible to reduce the size and cost of the structure for detection.

Further, the winding detection by the detection head has a better response performance than the detection by the reel rotation pulse, so that the winding can be detected quickly and the damage of the magnetic tape can be minimized. Can be stopped.

Further, preferably, in the detection by the detection head, since it is detected in advance by the reproducing head whether or not a signal of a predetermined level is recorded at a corresponding portion on the magnetic tape, it is possible to detect at a portion where no signal is recorded. It is possible to prevent erroneous detection of.

Still more preferably, when the winding is detected, the capstan motor is rotated in the reverse direction, and when the winding is not eliminated, the drive of each motor is stopped, so that the expansion of the winding is prevented. You can

[Brief description of drawings]

FIG. 1 is a cassette tape recorder 1 according to an embodiment of the present invention.
It is a top view which simplifies and shows the traveling drive device 2 of FIG.

FIG. 2 is a plan view showing a state where the magnetic tape 3 is slack in the cassette tape recorder 1. FIG.

FIG. 3 is an electric block diagram of the traveling drive device 2.

FIG. 4 is a timing chart for explaining a winding detection operation during forward rotation driving by the signal processing circuit 51 of the driving device 2.

FIG. 5 is a flowchart showing a wrap detection operation shown in FIG.

FIG. 6 is a plan view showing a simplified principle of detecting the slack of a magnetic tape of the related art using a tension sensor.

[Explanation of symbols]

 1 cassette tape recorder 2 running drive device 3 magnetic tape 5 recording / playback head 8 FF side detection head 9 FR side detection head 11, 12 capstan 44, 46, 48 comparator 50 delay circuit 51 signal processing circuit

Claims (3)

[Claims] 1. A control means drives a capstan motor to run a magnetic tape at a predetermined speed, and drives a reel motor to apply a magnetic tape through a capstan and a pinch roller to a reel on a winding side. In a running drive device for a magnetic tape to be wound up, a detection head provided in proximity to a downstream side of the capstan in the running direction of the magnetic tape, and a first comparison for comparing an output level of the detection head with a predetermined level. The control means detects that the magnetic tape is wound around the capstan when the first comparison means determines that the input level from the detection head is less than a predetermined level. A drive device for a magnetic tape, characterized in that 2. A second comparing means for comparing the output level of the reproducing head with a predetermined level in relation to the reproducing head, and an output of the second comparing means corresponding to a difference in distance from the reproducing head to the detecting head. Delaying means for delaying the running time of the magnetic tape is provided, and the control means determines that the input level from the detection head is less than a predetermined level by the first comparing means, and the reproducing head by the second comparing means. 2. The running drive of the magnetic tape according to claim 1, wherein the occurrence of wrapping of the magnetic tape around the capstan is detected when it is determined that the input level from the magnetic tape is equal to or higher than a predetermined level. apparatus. 3. The control means, when the winding is detected, reverses the capstan motor for a predetermined time, and when the winding is not canceled by this, driving of each motor is stopped. The traveling drive device for a magnetic tape according to claim 1 or 2.