JPS6349307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape loading device, and particularly to a rotating head type VTR (video tape recorder), in which a magnetic tape is pulled out from a cassette and the pulled out magnetic tape is loaded into a cylinder equipped with a rotating head. The present invention relates to a magnetic tape loading device for winding a tape.

First, a conventional magnetic tape loading device will be explained with reference to FIGS. 1 to 10.

In FIG. 1, 1 is a base, 2 is a loading arm, and 3 is a shaft, which is supported by a bearing (not shown) fixed to the base 1. This shaft 3 and the arm 2 are Mechanically fixed. 4 is a fulcrum fixed on the arm 2, and 5 is a block connected to the fulcrum 4. A shaft 6 passes through the block 5 and is fixed to the block 5. 7 is a magnetic tape guide pin provided at an angle with respect to the base 1; 8 is a magnetic tape guide roller provided perpendicularly to the base 1;
It is fixed to the shaft 6. Furthermore, base 1
has an arc-shaped long hole 1a centered on the shaft 3.
is provided, and the shaft 6 fixed to the block 5 engages with this elongated hole 1a.

The tape loading device, as shown in FIG. 2, is formed by the arrangement shown in FIG. 1 and another set of arrangements more similar to that shown in FIG. In Fig. 2, 9 is an arm corresponding to 2, 10 is a shaft corresponding to 3,
11 is a fulcrum corresponding to 4, 12 is a block corresponding to 5, 13 is a pin corresponding to 7, and 14 is a roller corresponding to 8, and this roller 14 is fixed to a shaft (not shown) corresponding to 6. The shaft is located on the shaft 1 provided on the base 1.
It engages with a long hole 1b centered at 0. 15,
Reference numeral 16 denotes a stopper block fixed on the base 1, and when the blocks 5 and 12 rotating around the shafts 3 and 10 come into contact with the blocks 15 and 16, respectively, the positions of the blocks 5 and 12 and their inclination angles are changed. , regulates the direction of inclination. Furthermore, shaft 3,
10 is connected to a link drive device (not shown), and blocks 5, 12 are connected to arms 2, 9.
is driven by its link drive. In FIGS. 3 to 5, 17 is a cylinder installed obliquely on the base 1, 18 is a cassette containing a magnetic tape, and 19 is a magnetic tape, which is fixed on the blocks 5 and 12. The pins 7, 13 and rollers 8, 14 are provided to face the magnetic tape 19.

In FIG. 3, the pins 7, 13 and rollers 8, 14 fixed to the blocks 5, 12 are located below, and the cassette 18 containing the magnetic tape 19 can be freely attached and detached. After the cassette 18 has been installed on the base 1 as shown in FIG. 13 and roller 14 are the shaft 1
Rotate counterclockwise around 0, and cassette 1
A magnetic tape 19 built into the magnetic tape 8 is connected to pins 7 and 13 and rollers 8 and 8 that face the magnetic tape.
14, and is wound around the cylinder 17 as shown in FIG. 4, and as shown in FIG. The operation ends. Place magnetic tape 19 into cassette 1
8 and when the cassette 18 is removed from the base 1, each component moves in the opposite direction to that at the time of loading and returns to the initial state shown in FIG. By the way, in this magnetic tape loading device, in order to run the magnetic tape smoothly and effortlessly, the rollers 8, 14 and pins on the blocks 5, 12 are moved only when the tape loading operation is completed, in which the blocks 5, 12 are in contact with the blocks 15, 16. The relative positions of 7, 13 and cylinder 17, the inclinations and inclination directions of cylinder 17 and pins 7, 13 with respect to base 1 are determined so as to satisfy the three conditions (a), (b), and (c) listed below. There is. As shown in FIG. 6, the cylinder 17 is tilted in the negative X direction about a tilt axis that passes through the center of the cylinder and faces in the Y-axis direction. θ is the winding angle of the magnetic tape 19 with respect to the cylinder 17, and θ=190 degrees at the end of tape loading. 7a, 7b, 8a, 8b, 1
3a, 13b, 14a, 14b, 17a, 17b
are the tangents of the pins 7, 13, rollers 8, 14, cylinder 17, and magnetic tape 19, respectively, and 1
7c is a generatrix of the cylinder that intersects the tilt axis of the cylinder 17. 19a is the center line of the magnetic tape 19, and 7c, 13c, and 17d are tangent lines 7a, 13b, and generatrix 17 to the center line 19a, respectively.
This is the intersection with c. In Fig. 6, (a) pins 7, 13, rollers 8, 14, cylinder 1
7, there is no twist in the magnetic tape 19;
In other words, tangents 8b and 7a, 7b and 17a, 1
The two tangent lines of 7b and 13a, and the two tangent lines of 13b and 14a form respective planes, (b) Intersection points 7c, 13c, and 17d with respect to base 1
(c) The magnetic tape 19 between the cassette 18 and the pin 7 and between the cassette 18 and the pin 13 runs parallel to the base 1, and the normal line of the magnetic tape surface to the base 1. A mode that satisfies the condition of being parallel is now being realized.

However, in the conventional magnetic tape loading device configured as described above, when loading the magnetic tape 19, "head cut" and "lead running over" phenomena are extremely likely to occur, and there is a risk of damaging the magnetic tape. In addition, we will explain in advance what kind of phenomena ``head cutting'' and ``lead riding over'' are.

FIG. 7 explains the "head cutting" phenomenon, and 20 is a video head fixed to the cylinder 17, which protrudes from the surface of the cylinder 17 by about 50 μm. When the magnetic tape 19 is wound around the cylinder 17 as shown, the magnetic tape 19
The edge portion contacts the video head 20, which is rotating at high speed in the direction of the arrow. This is a phenomenon in which the magnetic tape 19 is cut by a video head.
In other words, it is called "head cutting." This "head cut" is an accident that damages the extremely thin video head 20 or the edge of the magnetic tape 19, and can be said to be a fatal phenomenon for VTRs.

FIG. 8 explains the "lead riding up" phenomenon, and 17e is a lead for a magnetic tape guide that is machined to protrude at right angles from the running surface 17f of the magnetic tape 19 in the cylinder 17.
The state in which the magnetic tape 19 comes off the running surface 17f and rides on the tape 7e is called "leat running over".
It is called. When this “lead jump” occurs,
The sharp surface of the lead 17e contacts the magnetic tape 19, and the stress of the magnetic tape is concentrated in this area. Therefore, depending on the tape tension, the magnetic tape may
Extremely susceptible to damage. FIG. 9 explains the occurrence of both the above-mentioned "head cut" and "lead riding up" phenomena. In the figure, β is the incident angle of the magnetic tape 19 with respect to the cylinder 17, and η is the inclination angle of the lead 17e with respect to the cylinder 17. be. This inclination angle η is determined at the time of processing the lead 17e, and remains fixed thereafter.

At the initial stage of loading the magnetic tape, the magnetic tape 19 stored in the cassette 18 is attached to the pins 7 and 1.
3. It is pulled out by the rollers 8 and 14, moves parallel to the base 1, and comes into contact with the cylinder 17. And the tape incidence angle β is initially
7, and becomes smaller as loading of the magnetic tape progresses, and at the end of loading, β=
η. It is observed that the magnetic tape 19 is rotating counterclockwise around the intersection 17d as shown by the arrow, and a "lead run-up" phenomenon occurs at section A in the figure, and a "head cut" phenomenon occurs at section B. can occur. Note that this "lead running over" and "head cutting" are expressed by the following equation.

△H ₁ = rθ/2tanβ−H/2cosβ …(1) △H ₂ = |rθ/2(tanβ−tanη) +H/2(1/cosβ−1/cosη) | …(2) However, △H ₁ represents "head cut", △ _H2 represents "lead riding up", r is the radius of the cylinder 17, θ is the winding angle of the magnetic tape, β is the incident angle of the magnetic tape with respect to the cylinder 17, and η is the lead 1
7e is the tilt angle, and H is the magnetic tape width.

In FIG. 10, "head cutting" ΔH ₁ is the edge of the magnetic tape 19 on the tangent 17a between the cylinder 17 and the magnetic tape 19 and the video head 20.
"Lead running over" ΔH ₂ indicates the distance between the lead 17e and the magnetic tape edge on the tangent 17b.

As can be seen from equations (1) and (2) above, "head cutting"
△H ₁ , “lead riding up” △H ₂ , cylinder 1
7, the cylinder radius r, the magnetic tape incidence angle β with respect to the cylinder 17, the lead inclination angle η, and the magnetic tape width H. For example, the VHS format currently available on the market
In a VTR, the incident angle β with respect to the cylinder changes from 12.83 degrees to 5.93 degrees, and at this time, ``lead riding'' occurs, but ``head cutting'' does not occur. On the other hand, in a new standard VTR with a cylinder radius of 20 mm, tape width of 8 mm, and lead angle of 4.8 degrees, the incident angle β with respect to the cylinder changes from 15 degrees to 4.8 degrees.
Not only “lead riding” but also “head cutting” △H ¹
The maximum value reaches approximately 4 mm. In this way, with conventional tape loading devices, "lead running over" always occurs, and with VTRs of different tape widths, "head cutting" occurs, which can lead to damage to the video head.
This caused problems with reliability.

Therefore, the main object of the present invention is to provide a magnetic tape loading device that can completely prevent damage to the magnetic tape and magnetic head.

Another object of the present invention is to realize such a magnetic tape loading device simply and inexpensively.

In summary, the present invention includes a base, a cylinder provided at an angle with respect to the base, and two sets of magnetic tape pulling means for pulling out a magnetic tape from a cassette and winding it around the cylinder. A bit head is fixed to the base, and a magnetic tape guide lead having an inclination angle η is protruded, and the magnetic tape pulling means is connected to a first magnetic tape guide means provided perpendicularly to the base. and a second magnetic tape guide means provided at an angle with respect to the base,
The present invention relates to a magnetic tape loading device in which the magnetic tape is pulled out from a cassette by the magnetic tape pulling means, and the magnetic tape is wound and loaded onto a cylinder at an incident angle of β. The cylinder angle continuously changing means continuously changes the inclination angle of the cylinder while the magnetic tape is being loaded, and the incident angle β of the magnetic tape and the inclination angle η of the magnetic tape guide lead are adjusted by the magnetic tape. The tape is characterized in that it can be held evenly at all times while loading the tape, and head cutting and lead riding can be prevented.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 11 shows only the configuration of the main part of the present invention, and other configurations are shown in FIGS. 1 to 5, for example.
This is the same as the conventional one shown in the figure. In FIG. 11, reference numeral 21 is an L-shaped plate consisting of a cylinder mounting portion 21a located below the base 1 and a vertical portion 21b extending vertically through the base 1. 22 is a shaft mechanically fixed to the vertical portion 21b. A bearing 23 rotatably holds the shaft 22, and is fixed to the upper surface of the base 1. The plate 21 to which the cylinder 17 is fixed is rotatable about the bearing 23. Note that the center of the bearing 23 passes through the intersection 17d shown in FIG.
7 is provided so as to be parallel to the tilt axis.
25 is an L-shaped metal fitting fixed to the plate 21. 2
6 is a drive link that engages with the metal fitting 25 to rotate the plate 21 and the cylinder 17;
Only a part of it is shown. Here, the drive link 26 is connected to a link drive device that drives the shafts 3 and 10 (see FIG. 2), and receives a predetermined drive by the link drive device.

Next, the operation of the present invention will be explained.

At the beginning of tape loading shown in FIG. 3, cylinder 17
is set at the same inclination angle as the lead inclination angle η by the drive link 26 which rotates the cylinder, and the direction of the inclination angle is set in the direction of the angle X shown in FIG. After the cassette 18 is mounted on the base 1, the magnetic tape 19 is pulled out by the pins 7, 13 and rollers 8, 14 and comes into contact with the cylinder 17. During this time, the inclination angle of the cylinder does not change. The magnetic tape 19 in contact with the cylinder 17 is further connected to the pin 7,
13, it is wound around the cylinder 17 by the rollers 8 and 14 as shown in FIG. 4, and reaches the final state shown in FIG. During this time, cylinder 17
is rotated about the bearing 23 by a drive link 26 connected to the link drive device of the shafts 3 and 10 in accordance with the movements of the pins 7 and 13 and the rollers 8 and 14, and the tilt angle of the cylinder is precisely controlled. is controlled by this driving link. FIG. 12 shows an example of changes in the tilt angle of the cylinder during loading. In FIG. 12, the horizontal axis shows the loading state of the magnetic tape, A is the loading start point of the magnetic tape, B is the contact start point of the magnetic tape with the cylinder, C is the period during which the magnetic tape is wound around the cylinder, and D is the magnetic tape loading state. Indicates the end of loading.

In the present invention, the inclination angle of the cylinder is not constant but variable during loading of the magnetic tape. And, such a variable is the above-mentioned "head cut",
The relationship is set to prevent "lead riding".

The values of “head cut” △H ₁ and “lead riding up” △H _{2 expressed by equations (1) and (2} ) above are
FIGS. 13 and 14 are graphs using the winding angle θ of the tape around the cylinder and the incident angle β of the tape against the cylinder as variables.

In Figures 13 and 14, the cylinder radius r = 20 mm,
When the magnetic tape width H = 8 mm and the lead inclination angle η = 4.8 degrees, the horizontal axis is the winding angle θ of the magnetic tape, and the vertical axis is "head cut" △H ₁ and "lead riding up" △H ₂ . △H ₁ and △H ₂ in each case where the value of the incident angle β of the magnetic tape is changed.
The characteristics of θ are shown below.

In Figure 13, if it is positive, "head cut"
If it is negative, it means that the "head cutting" phenomenon is not occurring, and if the incident angle β with respect to the cylinder is 4.8 degrees or less, the "head cutting" phenomenon does not occur.

Also, from Figure 14, when the incident angle β is 4.8 degrees, △
It can be seen that H ₂ coincides with the horizontal axis, indicating that the "lead riding up" phenomenon does not occur, but this can also be seen from the fact that in equation (2) above, if β = η, △H ₂ = 0. .

Therefore, if the incident angle .beta. of the tape 19 with respect to the cylinder 17 is always made equal to the inclination angle .eta. of the lead 17e during tape loading, the phenomena of "head cut" and "lead running over" can be completely prevented. on the other hand,
The incident angle β of the tape is pins 7, 13, rollers 8, 1
Since it is uniquely determined by the relative position of pins 7 and cylinder 17, taking this relationship into consideration,
3. By connecting the driving device driving the rollers 8 and 14 to the driving link 26, the value of the tape incidence angle β can be maintained at the lead inclination angle η.

In the above embodiment, the tape incidence angle β on the cylinder can be determined indirectly from the positional information of the pins 7, 13 and the rollers 8, 14. Alternatively, the tape incidence angle β may be directly determined. This optical means is shown in FIG. 27, the light receiving element 28 such as CDS is a light emitting element such as an LED, and the amount of light reaching the light receiving element 27 changes depending on the position of the end surface of the magnetic tape 19 located between the light receiving element 27 and the light emitting element 28. The voltage (current) of the element 27 changes, and the position of the magnetic tape can be measured. Of course,
The positional relationship of the light receiving and light emitting elements may be reversed.
Further, instead of this optical means, a capacitance sensor may be used to measure the position of the tape, and the angle of incidence β of the magnetic tape may be determined. Furthermore, a magnetic sensor may be used. The incident angle β can be easily determined if at least two end face positions of the magnetic tape 19 are known. In the case of measurement using these optical means or electric means, there is an advantage that the inclination angle of the cylinder during loading of the magnetic tape can be easily and precisely set.

Note that the drive link 26 is separated from the link drive device for the shafts 3 and 10, and the drive link 26 is configured to be automatically variably controlled by the output of measurement by the optical means or electric means. Good too.

As described above, according to the present invention, while loading a magnetic tape, the inclination angle of the cylinder is changed so that the tape incident angle β on the cylinder and the lead inclination angle η are always equal to each other. “Lead rides up”
This method is extremely effective because no phenomenon occurs and no damage is caused to the magnetic tape or video head. Moreover, the structure is simple, just providing a means for changing the inclination of the cylinder so as to maintain the above-mentioned relationship β=η, and therefore it has the effect of providing a highly reliable magnetic tape loading device at low cost. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a partial configuration of a conventional magnetic tape loading device. FIG. 2 is a plan view of a state in which two of the configurations shown in FIG. 1 are combined. FIG. 3 is a plan view showing a state before loading a magnetic tape in a conventional magnetic tape loading device. FIG. 4 is a plan view showing the apparatus of FIG. 3 during loading of a magnetic tape.
FIG. 5 is a plan view showing the apparatus shown in FIG. 3 in a state in which the magnetic tape has been completely loaded. Figure 6, Figure 7, Figure 8,
FIGS. 9 and 10 are explanatory diagrams of a conventional magnetic tape loading device. FIG. 11 is a diagram showing the configuration of main parts of a magnetic tape loading device embodying the present invention. Figures 12, 13 and 14 are
It is a figure explaining a figure. FIG. 15 is a diagram showing a partial configuration of another embodiment of the present invention. In the figure, 1 is a base, 7 and 13 are pins (second magnetic tape guide means), 8 and 14 are rollers (first magnetic tape guide means), 17 is a cylinder, 17e is a lead, 18 is a cassette, and 19 is a cylinder. is a magnetic tape, 26 is a drive link, 27 is a light receiving element,
28 indicates a light emitting element.

Claims (1)

[Scope of Claims] 1 A base, a cylinder provided at an angle with respect to the base, and two sets of magnetic tape drawing means for drawing out a magnetic tape from a cassette and winding it around the cylinder, the cylinder A video head is fixed to the base, and a magnetic tape guide lead having an inclination angle η is protruded, and each of the magnetic tape pull-out means has a first magnetic tape provided perpendicularly to the base. a tape guide means and a second magnetic tape guide means provided at an angle with respect to the base, the magnetic tape pull-out means pulls out the magnetic tape from the cassette, and the magnetic tape is drawn into the cylinder at an incident angle of β. A magnetic tape loading device for winding and loading the magnetic tape, further comprising cylinder angle continuously variable means for continuously changing the inclination angle of the cylinder during loading of the magnetic tape, the incident angle β of the magnetic tape and the magnetic tape guide A magnetic tape loading device characterized in that the inclination angle η of the lead is always kept equal during loading of the magnetic tape, thereby preventing head cutting and lead riding. 2. The magnetic tape loading device according to claim 1, wherein the cylinder angle continuously variable means sets the inclination angle of the cylinder according to the movement position of the magnetic tape pull-out means. 3. The cylinder angle continuously variable means includes a light emitting element or a light receiving element disposed inside the cylinder and a light receiving element or light emitting element disposed outside the cylinder on the optical axis of the light emitting element or light receiving element. A patent claim characterized in that it has a plurality of optical measuring means for measuring the end face position of the magnetic tape located between the light emitting element and the light receiving element, and the inclination angle of the cylinder is set based on the measurement output. The magnetic tape loading device according to item 1. 4. The cylinder angle continuously variable means includes means for measuring the position of the end surface of the magnetic tape in contact with the outer peripheral surface of the cylinder using a plurality of capacitance sensors arranged at different positions close to the outer peripheral surface of the cylinder. 2. The magnetic tape loading apparatus according to claim 1, wherein the inclination angle of the cylinder is set based on the output of the measuring means. 5. The cylinder angle continuously varying means includes means for measuring the position of the end surface of the magnetic tape in contact with the outer peripheral surface of the cylinder using a plurality of magnetic sensors arranged at different positions close to the outer peripheral surface of the cylinder. 2. The magnetic tape loading device according to claim 1, wherein the inclination angle of the cylinder is set based on the output of the measuring means.