JPH0354787A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To stably count a tape traveling amt. by detecting a physical characteristic change on the outer circumferential surface of a roller to be in contact with a magnetic tape. CONSTITUTION:The outer circumferential surface of the guide roller 7 is provided with periodically different color tones of light and darkness, and the subject device is moreover provided with a light emitting element 10 for irradiating the outer circumferential surface of the guide roller 7 with its light and a light receiving element 11 for detecting the intensity of the light to be reflected. Then, the light emitted from the light emitting element 10 and reflected by the surface of the guide roller 7 is received by the light receiving element 11, and a magnetic traveling amt. is calculated with a difference in this light receiving amt. due to the light and darkness on the surface of the guide roller 7 as a reference signal. By this method, even when the magnetic tape is slackened to make its contact with the roller 7 intermittent, the detecting errors of the tape traveling amt. is comparatively diminished, thus promoting the display accuracy of the tape traveling amt. as a linear time counter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing apparatus, and more particularly to an improvement in means for detecting the amount of travel of a magnetic tape.

[Prior Art] A conventional magnetic recording/reproducing device will be described below with reference to the drawings.

Referring to FIGS. 3 and 4, a conventional magnetic recording and reproducing device for a VTR has a magnetic tape 2 that is helically wound around the outer periphery of a rotating drum 1 that rotates in the direction of arrow B and runs in the direction of arrow A. A magnetic head (not shown) attached to the outer periphery of the rotating drum 1 scans at a constant angle with respect to the running direction of the magnetic tape, thereby magnetically recording and reproducing video signals.

Magnetic tape 2 exiting the magnetic tape supply reel (not shown)
The magnetic tape 2 travels in the direction of arrow A in the figure, and first travels along an impedance roller 3 for keeping the traveling speed of the magnetic tape 2 constant, a guide roller 4, and an inclined pin 5 in that order.

After sliding on the rotating drum 1, the magnetic tape 2 further runs along the inclined pin 6 and the guide roller 7.
Thereafter, it slides into contact with an audio erasing head 8 and an audio/control head (hereinafter abbreviated as rA/C head) 9, and is wound onto a magnetic tape take-up reel (not shown).

In such a conventional magnetic recording/reproducing device, the reference signal for displaying the running amount of the magnetic tape 2 on a counter is obtained by reading control signals recorded at equal intervals on the magnetic tape 2 using the A/C head 9. I'm getting it by doing that. For example, fast forward. When the magnetic tape 2 runs at a magnetic tape running speed that is different from that during normal playback, such as during rewinding, the tape run can be adjusted by advancing or returning the counter number corresponding to the time that elapses during normal playback. Quantity is being detected. This is called a linear time counter.

[Issue to be Solved by the Invention] Since the conventional magnetic recording/reproducing device is configured as described above, the A/C head 9 with a small winding angle of the magnetic tape 2 has a reverse direction of magnetic tape running. When switching modes, the tape tension may loosen and contact with the magnetic tape 2 may become intermittent. In this case, the control signal is not read while the magnetic tape 2 is not in contact with the A/C head. Therefore, a large error may occur between the counter display of the magnetic tape running amount and the actual magnetic tape running amount.

Another problem is that the counter does not operate if no control signal is recorded on the magnetic tape.

Furthermore, a method of counting the amount of tape travel by detecting the rotational speed of a magnetic tape supply reel rather than by reading a control signal by an A/C head has existed for a long time. However, the winding diameter changes depending on the amount of magnetic tape wound on the reel, and even if the magnetic tape runs at a constant speed, its rotational speed changes, making it impossible to use it as a linear time counter. .

In order to solve the above-mentioned problems, the present invention is equipped with a magnetic counter equipped with a linear quim counter, which is capable of stable operation and can also count the amount of tape travel even when no control signal is recorded on the magnetic tape. The purpose is to obtain a recording/reproducing device.

[Means for Solving the Problems] In order to solve the above problems, the magnetic recording and reproducing device of the present invention has the following features:
It has a roller whose outer periphery is in contact with the magnetic tape so that it rotates at the same circumferential speed as the running speed of the magnetic tape, and whose physical properties change periodically in the circumferential direction on the outer circumferential surface at predetermined intervals.

Furthermore, a rotational speed detection means is provided which inputs a signal corresponding to the running speed of the magnetic tape by detecting a change in the periodic physical characteristics of the outer circumferential surface of the roller.

Furthermore, means is provided for converting this signal into a reference signal for running the magnetic tape and outputting the same.

[Function] According to the present invention, a control signal is recorded by converting an input signal corresponding to the rotation of a roller rotating at the same circumferential speed as the running speed of the magnetic tape into a reference signal for tape running and outputting the signal. It becomes possible to detect the traveling distance of the magnetic tape.

Furthermore, even if the tension on the magnetic tape is loosened and contact with the roller becomes intermittent, the roller continues to rotate due to inertia, so the detection error in tape running distance is smaller than in a method that reads control signals.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

The overall configuration of the magnetic recording/reproducing apparatus of this embodiment is almost the same as that of the conventional example shown in FIGS. 3 and 4.

That is, the magnetic recording and reproducing apparatus of this embodiment, with reference to FIG. Magnetic recording and reproduction of video signals is performed by scanning the magnetic tape (not shown) at a constant angle with respect to the running direction of the magnetic tape. Magnetic tape supply reel (
The magnetic tape 2 that has left the magnetic tape (not shown) travels in the eight directions shown by the arrows in the figure, first passing along an impedance roller 3 to keep the traveling speed of the magnetic tape 2 constant, a guide roller 4, and an inclined bin 5 in that order. Run. After the magnetic tape 2 has finished sliding on the rotating drum 1, it further runs along the inclined bin 6 and the guide roller 7, and then passes through the audio erasing head 8.
and slides into contact with an audio/control head (A/C head) and returns to a magnetic tape take-up reel (not shown).

This embodiment differs from the conventional example in that the outer circumferential surface of the guide roller 7 is provided with periodic differences in bright and dark tones, and furthermore, the outer circumferential surface of the guide roller 7 is provided with a light beam 10 that irradiates light, and a reflective The point is that a light receiving element 11 is provided to detect the intensity of the light.

When the magnetic tape 2 is run with the above configuration, the guide roller 7 rotates following the magnetic tape 2.

The light receiving cable 11 comes out from the light emitting element 10 and passes through the guide roller 7.
The traveling distance of the magnetic tape is calculated using the difference in the amount of received light due to the brightness and darkness of the surface of the guide roller 7 as a reference signal.

For example, the calculation formula is as follows.

L-π●D @p/d where p: Number of reference signals within a given time d: Number of bright and dark divisions D: Guide roller diameter L: Amount of tape travel within a given time Also, magnetic field per Ill time in the playback direction Assuming that the tape running amount, that is, the magnetic tape running speed is V, the elapsed distance T of reproduction 1,'7 can be determined from the magnetic tape running mL determined by the above equation as follows.

T = L / v In the above embodiment, the rotation speed of the guide roller 7 was detected to obtain a reference signal for tape running, but the impedance roller 3 may be provided with a rotation speed detection means.

The magnetic tape running reference signal obtained in this embodiment is obtained by detecting the rotational speed of the guide roller 7, which rotates at the same circumferential speed as the running speed of the magnetic tape 2, so the rotation of the magnetic tape take-up reel is Unlike the case of speed detection, there is no problem of errors caused by changes in the winding diameter of the magnetic tape.

In addition, even if the magnetic tape 2 loosens when changing modes between fast-forwarding and rewinding, and momentarily separates from the guide roller 7, causing intermittent contact, the guide roller 7 will still rotate at approximately the same circumferential speed due to inertia. Continue to do so.

Therefore, large reading errors that occur when reading control signals with an A/C head do not occur.

Furthermore, the magnetic tape running reference signal obtained in this way is particularly useful for high-speed FF/FF in so-called full loading, which is performed with the magnetic tape still wound around the rotating drum 1.
In REW, it can be effectively used for control to keep the running speed constant. In other words, accurate cueing and tape end detection using high-speed FF/REW become possible.

Further, in the above embodiment, the rotational speed of the guide roller 7 is detected by optical means, but other methods may also be used. For example, there is a method of attaching a magnetic material with a magnetic signal recorded on the outer circumference of the roller at a position that does not affect the magnetic tape and detecting this with a magnetic head.
It is also possible to obtain a signal corresponding to the running of the magnetic tape by forming periodic irregularities on the outer periphery of the roller and detecting the irregularities with a proximity switch. That is, magnetic tape 2
The same method can be achieved by applying periodic changes in physical properties that do not affect the running magnetic tape to the outer periphery of a roller that rotates at the same circumferential speed as the running speed of the roller, and by providing means for detecting changes in these physical properties. It is possible to obtain the following effects.

[Effects of the Invention] As described above, according to the present invention, the input signal corresponding to the rotation of the roller that rolls four times at the same circumferential speed as the running speed of the magnetic tape is converted into a reference signal for running the magnetic tape and output. This makes it possible to detect the running distance of a magnetic tape on which no control signal is recorded.

Furthermore, even if the magnetic tape becomes loose and comes into contact with the roller intermittently, the detection error in the amount of tape travel is relatively small.

Therefore, the accuracy of displaying the amount of tape travel as a linear time counter is improved, and it becomes an effective control means especially when performing accurate cueing operation in high-speed FF/REW during full loading.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing the main parts of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged perspective view showing a guide roller of the same embodiment. FIG. 3 is a plan view showing the main parts of a conventional magnetic recording/reproducing device, and FIG. 4 is a perspective view thereof. In the figure, 2 is a magnetic tape, 7 is a guide roller, and 10 is a magnetic tape.
1 is a light emitting element, and 11 is a light receiving element. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] A roller that rotates at the same circumferential speed as the running speed of the magnetic tape when its outer circumference comes into contact with the magnetic tape, and whose physical properties change periodically in the circumferential direction on the outer circumferential surface at predetermined intervals; A rotational speed detection means for inputting a signal corresponding to the running speed of the magnetic tape by detecting a change in the physical characteristics of the outer circumferential surface of the roller, and a means for converting this signal into a reference signal for running the magnetic tape and outputting the signal. A magnetic recording and reproducing device equipped with , .