JPS6125089Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape recording/reproducing apparatus, and particularly to a recording/reproducing apparatus using a parallel twin-axis cassette tape.

Conventional parallel loading will be explained based on FIG. 1. In the figure, 21 is a rotating cylinder, 22
is the entry side inclined post, 23 is the exit side inclined post, 24
25 is the entry guide post, 25 is the exit guide post,
26 and 27 are impedance rollers, 28 is a full width erasing head, 29 is an audio erasing/audio control head, 30 and 31 are tape height regulating posts, 3
2 is a tension post, 33 is a supply guide pin, 34 is a capstan, 35 is a pinch roller,
A indicates a cassette half, A1 a take-up reel, A2 a supply reel, and T a tape.

In the above configuration, in the parallel loading used in the VHS system, the entry side inclined post 22 and the exit side inclined post 23 are used to correct the tape level difference after being wrapped around the rotating cylinder 21, but in reality In this case, it is practically difficult to correct the level difference in the tape using only these two inclined posts, and therefore the rotary cylinder 21 is tilted back and forth by 13 degrees to correct the level difference.

As a means for tilting the rotating cylinder 21,
Methods have been taken such as using a cylinder base (pedestal) tilted at a predetermined angle, or using a die-cast chassis and making the mounting part of the rotating cylinder have an angle, but in any case, there is a slight misalignment of the angle. Since this has a large effect on the height deviation of the tape, it is necessary to tilt the rotating cylinder with high precision, with an angular tolerance within a few minutes.

On the other hand, regarding the outlet inclined post 23, FIG. 2 is a diagram for explaining the direction in which the outlet inclined post 23 falls. The direction and angle at which the tape 23 falls is determined by the composite vector γ of α and the falling angle β in a direction parallel to the tape l ₁ , and if this is not maintained, the tape l ₁ will be twisted. Furthermore, in order to make the tapes l ₃ and l ₄ have the same height and be parallel to the shear sea surface, in addition to α and β, the wrap angle δ to the inclined post must be taken into account, and all conditions are satisfied. α, β, and δ must be calculated to satisfy the above conditions. This calculation formula has been shown in literature (for example, Japanese Patent Application Laid-Open No. 52-134408), but since the tilted post is a combination of inclination angles in two directions, it is difficult to achieve precision in processing. This is difficult, and adjustment after installation is also extremely difficult because corrections must be made in two directions at the same time.

Furthermore, as a means of reducing the size and weight of the mechanism of a VTR, a method has been known in which the diameter of the cylinder is reduced by wrapping tape around a rotating cylinder at an angle of 270 degrees.

This involves placing the tape at 270 degrees in a rotating cylinder with four video heads spaced 90 degrees apart, as shown in Figure 3B.
If you wind it around ° and rotate it at 2700 rpm,
The cylinder diameter can be reduced to two-thirds of that of a conventional two-head 180° wrapping type cylinder as shown in Figure 3A, and it is also compatible with conventional formats. It is said that it will be done. Incidentally, FIG. 3C is a diagram showing the scanning order for the tape of each head in FIGS. 3A and 3B.

However, when parallel loading is performed using this method, there are the following drawbacks.

A: In order to meet the strict conditions mentioned above, the cylinder inclination angle: α must be set at around 35° (conventional
For VHS, the tape must be tilted at an extreme angle (around 13 degrees), and the tilted post also tilts significantly, making tape loading difficult. Furthermore, if the cylinder is tilted too much, the effective area occupied by the cylinder becomes large, and there is no point in making the cylinder smaller.

B. Since the tape is wound around the cylinder at 270 degrees, the tape tension ratio at the entrance and exit of the cylinder increases, and the angle of inclination of the inclined post is also large, so it becomes necessary to take more care than before with respect to the spread of the tape piece.

C. In order to wrap 270 degrees with a 2/3 diameter cylinder, loading will be difficult unless the inclined post, guide post, etc. are made approximately 1/2 of the conventional diameter. For this reason, higher machining precision and assembly precision than ever before is required.

The purpose of this invention is to eliminate the drawbacks of the conventional 2-head cylinder 180° wrap-around type VTR mentioned above, and to
An object of the present invention is to provide an optimal magnetic tape recording and reproducing device that can be used with a head cylinder that is wound 270 degrees.

The structure of the present invention will be explained with reference to FIGS. 4 to 7 together with its embodiments. In the figures, 1 is a rotary cylinder, 2 is an entry side inclined post, 3 is an exit side inclined post, and 4 is an entry side guide. Post, 5 is the exit guide post, 6 and 7 are impedance rollers, 8 is the full width erasing head, 9 is the audio erasing/audio/control head, 10 and 11 are the tape height regulating posts, 1
2 is a tension post, 13 is a supply guide pin, 14 is a capstan, 15 is a pinch roller,
A is a cassette half, A1 is a take-up reel, A2 is a supply reel, and T is a tape. These are the same as the conventional one shown in Fig. 1, but in the present invention, the rotating cylinder 1 is A dedicated step correction mechanism 16 is provided to correct the tape step, and the step correction mechanism 16 is placed at the rear of the capstan 14 with respect to the tape running direction, that is, It is arranged on the take-up reel A1 side.

Two independent tilted posts 17 and 18 are used as the step correction mechanism 16, and the tilted posts are tilted in the same direction and at the same angle, as shown in FIGS. 6 and 7.

The calculation formula is shown below.

(1) ^Tape level ^difference between AB and CD
^-1
(sin θ/θ tan η) + η} θ: Tape wrapping angle when the inclined post is viewed from direction A : Radius of the inclined post : Inclination angle of the inclined post (2) Tape level difference between BC X' = √ (-2) ² + (×) ² × cos {tan ^-
1
(l-2r/Ktanη)+η} l: Pitch between posts when the inclined post is viewed from direction B. k: Tape step difference greater than or equal to the length of the inscribed line of the two posts when the inclined post is viewed from direction A. The correction amount is D=2X+X'.

Next, an example of operation will be explained.

First, the tape T that has come out of the supply reel A2 passes through a post in the cassette half A and is passed parallel to the chassis surface to the supply guide pin 13, tension post 12, tape height regulation post 10, full-width erasing head 8, and The tape T passes through the pedance roller 6 and the entrance guide post 4 and reaches the entrance inclined post 2. The tape T, which is wound around the entrance inclined post 2 at a predetermined angle, forms an angle equal to the lead angle determined in the format and reaches the entrance inclined post 2. It leaves the post 2 and wraps around the upright rotating cylinder 1.

The tape T leaving the rotary cylinder 1 has a downward angle with respect to the chassis surface equal to the lead angle, but the exit inclined post 3 is given the same inclination angle and tape wrapping angle as the entry inclined post 2. If this is done, the tape T will become parallel to the chassis surface after being wrapped around the outlet inclined post 3.

The tape that is parallel to the chassis surface is connected to the exit guide post 5, the impedance roller 7, the audio eraser/
It passes through the audio/control head 9, the tape height regulating post 11, and reaches the capstans 14 and 15.

Here, the tape T exiting the capstan 14 and the pinch roller 15 is parallel to the chassis surface, but at a lower position than the supply reel A2. The tape level difference correction mechanism 16 corrects this level difference, and the tape T that has passed through the level difference correction inclined posts 17 and 18 becomes equal to the tape height that exits the supply reel A2, and reaches A1.

The magnetic tape recording and reproducing apparatus of the present invention has the following effects.

(A) Since the rotary cylinder is installed upright, there is no need for a cylinder base or the like for tilting the cylinder as in the past, making it easier to install the rotary cylinder in manufacturing.

(B) As mentioned in the conventional example, in parallel loading, parallelism correction and height correction with respect to the chassis surface are performed using a set of inclined posts for the tape wrapped around the cylinder at an angle. Therefore, the inclination angle and the direction of the inclination post are a combination of two vectors, making it extremely difficult to set.However, in the present invention, the inclination post adjacent to the rotating cylinder has a direction parallel to the chassis surface. Since only the degree correction is performed, the tilted post can only be tilted in one direction as shown in FIG. 5, which makes it extremely easy to design and manufacture.

For example, in Fig. 5, if the angle at which the tape is wrapped around the inclined post is 180°, then the tilting direction of the inclined post is the tape l ₁ direction, and if the inclination angle is taken as half of the lead angle, the tape is l _3. is parallel to the chassis surface and no twist occurs.

(C) Since the capstan is placed in front of the tape level difference correction mechanism, the tape level difference correction mechanism is removed from the tape tension and tape vibration transmission loop, which eliminates the drawbacks of the conventional one, and Therefore, even when the tape level difference correction mechanism is constructed with an inclined post as in the embodiment, high accuracy unlike the conventional inclined post is not required.

(D) As mentioned above, the present invention
(2-head, 180° wrapping type), the effect is fully demonstrated, but it is also possible to use a small cylinder (4-head, 180° winding type) that is compatible with such conventional formats.
This effect is particularly great for VTRs using a 270° wrap-around head, and can contribute to making VTRs smaller and lighter. That is, firstly, by placing the cylinder upright, tape loading becomes easier, and in terms of space, it is possible to take full advantage of the smaller size, and the depth direction can be reduced compared to conventional ones. .

Second, in the present invention, the tape correction means is divided into one for parallelism correction and one for height correction, and the height correction mechanism is removed from the tape tension loop. torque can be reduced.

Third, since the height correction mechanism is outside the tape tension, its diameter can be set arbitrarily.
Further, since the tilted post for parallelism correction has an inclination angle in only one direction, there is no need to reduce the diameter of the tilted post, and adjustment is easy.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams for explaining a conventional VTR. Figure 1 is a plan view showing the tape running system, and Figures 2 and 3 are plan views showing the relationship between the tape and the rotating cylinder. It is a diagram. 4 to 7 show an embodiment of the magnetic tape recording and reproducing apparatus according to the present invention, FIG. 4 is a plan view, FIG. 5 is a plan view showing the relationship between the tape and the rotating cylinder, and FIGS. FIG. 7 is an explanatory diagram for explaining the inclination angle of the inclined post for tape level difference correction. 1: Rotating cylinder, 2: Entrance side inclined post, 3:
Exit side inclined post, 4: Entrance side guide post, 5: Output side guide post, 14: Capstan, 16: Tape level difference correction mechanism, 17, 18: Inclined post for level difference correction.

Claims (1)

[Scope of utility model registration request] The rotary cylinder is arranged perpendicularly to the chassis surface, and is provided with a dedicated step correction mechanism for correcting tape steps, and the step correction mechanism is arranged behind the capstan in the tape traveling direction. A magnetic tape recording and reproducing device characterized by: