JPH05225657A - Preventive mechanism for tape detachment in magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain a stable tape running by providing a friction material to keep a small gap against a guide roller. CONSTITUTION:A magnetic tape 15 is guided into a V-shaped groove 19' of a receptacle 19 under the state hooked with the guide roller 7 by the movement of a guide roller base 5. As a result, the tape 15 runs through the circumferential side of a head drum. When a sag is generated in the tape due to some disturbance of harmony or other, the tape is going to get over the outer circumference of a lower flange part of roller 7 but can not exceed the flange part of roller 7 for further movement as it is abutted to the friction material 22, and also a coefficient of friction of the friction material 22 is large, therefore, the tape is never slid and is prevented from detachment. By this procedure, the tape 15 is stably held and prevented from falling off from the drum 3, then the stable running is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed to prevent a magnetic tape from being separated from a guide roller in the reproducing apparatus or displaced from a predetermined position during use by inserting a cassette into the magnetic recording and reproducing apparatus. The present invention relates to a tape detachment prevention device for a magnetic recording / reproducing device.

[0002]

2. Description of the Related Art Conventional VTR (video tape recorder)
Is configured as shown in FIG. That is, the cassette 23
When inserted into the magnetic recording / reproducing apparatus, a supply reel stand 11 and a take-up reel stand 12 which are fitted into the supply reel 1 and the take-up reel 2 in the cassette 23, respectively, are provided in the reproducing apparatus, and are fitted to each other. Is configured to. Then, the magnetic tape 15 stretched over the side surface of the cassette is hooked on the guide rollers 7 and 8 on the two guide roller bases 5 and 6 which are provided so as to slide in the reproducing apparatus, and The head drum 3 pivotally mounted on the drum base 16 is guided. The guide roller bases 5 and 6 are guided to both sides of the drum base 16 by two guide grooves 17 and 18 formed on the left and right sides of the drum base 16, and the guide roller bases 5 and 6 move. The guide roller shaft 5'is received in the V-shaped groove 19 'of one of the receivers 19, 20 fixedly provided on the upper end surfaces of the guide grooves 17, 18 at the end of the guide groove. At that time, a space between both guide rollers of the magnetic tape 15 is wound around the outer circumference of the head drum 3, and the magnetic tape 15 is straightened by the tilt pins 9 and 10 so as to follow the tilt of the head drum shaft. Then, by rotating the supply reel base 11 and the take-up reel base 12,
Assuming that the reels 1 and 2 fitted in the respective reels rotate in the directions determined by the operation modes, and the magnetic tape 15 is fed in the direction of arrow a (FIG. 4), the head drum 3 also rotates in the direction of arrow b. ..

[0003]

However, in the above structure, when the rotation speeds of the supply reel bases 11 and 12 do not match, that is, the supply reel base 11 is braked by the brake 13 so as to have a constant speed. As a result, the feeding speed of the magnetic tape fluctuates according to the change in the winding diameter of the magnetic tape on the supply reel 1. Therefore, when a large slack 15 'is produced on the magnetic tape 15 at the outer peripheral portion of the guide roller 7, as shown in FIG. As shown by the chain line in FIG. 6, it may go down beyond the lower collar portion 7'of the guide roller 7. In this case, it is impossible to escape from this state and return to the original state, and the magnetic tape When the slack is reduced, that is, when the tension is increased, the magnetic tape is damaged by the guide roller 7, its lower flange portion 7'and the step. Similarly, the outer peripheral portion of the head drum 3 is also damaged by the expansion and contraction of the magnetic tape at the step in the helical lead 4 portion of the head drum 3. Therefore, an object of the present invention is to improve the drawbacks in the above-mentioned conventional example and prevent the magnetic tape from falling off the guide roller even if the magnetic tape sags.

[0004]

When a cassette is inserted into a magnetic recording / reproducing apparatus, a drum base for guiding and guiding the magnetic tape to a guide roller for guiding the magnetic tape to a predetermined position in the magnetic recording / reproducing apparatus. A friction material is provided on the upper side of the magnetic tape while keeping a small clearance.

[0005]

When the magnetic tape sags at the guide roller portion, when the magnetic tape is going to lower due to the friction material facing the guide roller, the magnetic tape comes into contact with the friction material to prevent this, and the magnetic tape is always kept at the guide roller. It is held in place on the outer circumference.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the embodiments shown in the drawings. As shown in FIGS. 1 to 3, a support base of a head drum 3 provided in a magnetic recording / reproducing apparatus, that is, a drum base 16 is provided. Guide grooves 17 and 18 are provided on both sides of the head drum 3 with the head drum 3 interposed therebetween, and guide rollers 7 and 8 and inclined pins are erected on the upper surfaces in the guide grooves 17 and 18 as in the conventional example. The guide roller bases 5 and 6 are slidably mounted along the guide grooves 17 and 18, and the inner ends of the guide grooves 17 and 18 are V-shaped grooves 19 opened in the direction of the guide rollers 7 and 8. The guide roller shaft receivers 19 and 20 having ', 20' are fixedly provided on the upper surface of the drum base 16, and the upper end surface of one of the receivers 19 is provided with natural rubber or synthetic rubber at a position facing the outside of the guide roller 7. Friction material 2
When the guide roller base 5 enters the guide groove 17 and the guide roller shaft 5'inscribes or approaches the V-shaped groove 19 'of the receiver 19, The friction material 22 is provided on the circumferential side of the guide roller 7 on the guide roller shaft.
Is trying to respond. The most ideal state of the relationship between the guide roller 7 and the friction material 22 is such that the line connecting the peripheral edges of the upper and lower flanges of the guide roller 7 and the side surface of the friction material 22 on the roller side substantially coincide with each other. is there. Further, in the above, no friction material was particularly provided on the upper end of the receiving member 20, but the shaft of the guide roller 8 was inscribed or approached the V-shaped groove 20 ′ of the receiving member 20 as described above, if necessary. At this time, a friction material may be provided so as to face the guide roller 8.

Next, the operation of the above construction will be described. When the cassette is inserted into the magnetic recording / reproducing apparatus as shown in FIG. 4 of the conventional example, the magnetic tape 15 is moved by the guide roller bases 5 and 6, and the guide roller 7 is moved. , 8 is guided by the V-shaped grooves 19 ', 20' of both receivers 19, 20 while being hooked. As a result, the magnetic tape 15 runs through the peripheral side portion of the head drum 3. Therefore, if slack is generated in the tape in FIG. 1 due to some disturbance of harmony while the magnetic tape is running, the magnetic tape will try to move beyond the outer periphery of the lower flange portion of the guide roller 7, but will move further. Then, it cannot come in contact with the friction material 22 and go over the flange portion of the guide roller, and since a friction material having a large friction coefficient is used, if it is connected to a tape, it cannot slide further and is prevented from falling off. To be done. By thus stably holding the magnetic tape at the guide roller portion, it is possible to prevent the magnetic tape from falling off the helical lead 4 of the head drum 3 as shown in FIG.

[0008]

Since the present invention is constructed as described above, even if the magnetic tape sags due to the disturbance of the harmony of the rotation of both reels while the magnetic tape is running, the flange of the guide roller and the head drum Since the magnetic tape does not drop off from the helical lead, stable running of the tape can be promoted and the tape is not damaged due to the drop, and a highly reliable magnetic recording / reproducing apparatus can be provided.

[Brief description of drawings]

FIG. 1 is an enlarged vertical side view of an essential part of the present invention.

FIG. 2 is a simplified diagram showing a state of the above magnetic tape.

FIG. 3 is an enlarged perspective view of the above head drum.

FIG. 4 is a perspective view showing a tape traveling path of a conventional magnetic recording / reproducing apparatus.

FIG. 5 is a simplified diagram showing a state of the same magnetic tape.

6 is an enlarged vertical sectional side view taken along line XX of FIG.

[Explanation of symbols]

 5,6 Guide roller base 7,8 Guide roller 16 Drum base 17,18 Guide groove 19,20 Receiver 19 'V-shaped groove 21 Protrusion 22 Friction material

Claims (1)

[Claims] 1. A magnetic tape 2 from the inserted cassette.
In a magnetic recording / reproducing apparatus in which points are engaged with a guide roller and taken out, and two points of the magnetic tape are guided to predetermined positions on the drum base via the outer peripheral portion of the head drum and fixedly held. A tape detachment prevention mechanism for a magnetic recording and reproducing apparatus, characterized in that a protrusion covered with a friction material is erected on the outer side of the guide roller with a small gap maintained between the magnetic tape and the guide roller.