JPS6346504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a helical scan type magnetic recording/reproducing device, and more particularly to a magnetic recording/reproducing device that can be miniaturized.

PRIOR ART Currently, efforts are being made to make current home VTRs even more compact without changing the recording pattern on the magnetic tape. One of the ideas for miniaturizing VTRs is to wrap the magnetic tape around the guide drum at approximately 270 degrees, rather than the current approximately 180 degrees, and to install four video heads at 90 degree intervals.
There is an idea to reduce the diameter of the guide drum to 2/3 of the current diameter and reduce the diameter of the guide drum to achieve a smaller VTR.

To ensure compatibility with current models,
In addition to matching the video signal recording patterns on the tape, it is also necessary to match the length of the tape along the tape path from the tape guide drum to the control head with the standard length so that the tracking servo is performed in the same way. There is. Therefore, even if the diameter of the guide drum is small as mentioned above, as long as the tape is wound symmetrically around the guide drum, the guide drum should be kept at some distance from the tape cassette so that the tape length up to the control head mentioned above is the standard length. This poses a problem in that it is difficult to effectively achieve miniaturization.

Means for Solving the Problems Therefore, it is an object of the present invention to provide a magnetic recording and reproducing device that solves the above problems, and has a structure in which the magnetic recording and reproducing apparatus is arranged such that the tape guide drum is located on the entrance side and on the tape guide drum in the tape running direction. In a magnetic recording and reproducing apparatus, the magnetic tape is pulled out from a tape cassette and wound approximately 270 degrees around the tape guide drum by an entrance tape guide that guides the magnetic tape on the exit side and an exit tape guide. The exit-side tape guide moves such that the latter movement distance is greater than the former movement distance, and the amount of wrapping of the magnetic tape around the tape guide drum on the exit-side tape guide side is greater than the amount on the entrance-side tape guide side. The tape is wound asymmetrically around the tape guide drum so that the amount of winding is larger than that of the tape guide drum.

Embodiment FIGS. 1 and 2 are a plan view and a side view, respectively, of a magnetic recording and reproducing apparatus according to the present invention in a recording and reproducing mode.

In this magnetic recording and reproducing apparatus 1, 2 is a small tape guide drum, and 3 is a small tape cassette, which are arranged close to each other. Further, a group of tape guide poles is also arranged near the small tape guide drum 2. As a result, the device 1 is significantly smaller in size than conventional devices. In addition, this device 1 has a structure in which a small tape guide drum 2 has four video heads arranged at 90 degree intervals, and a magnetic tape 4 is moved by tape guide poles.
The magnetic tape 4 is wound over approximately 270 degrees over 180 degrees, and the video head operates by sequentially switching the angular range over the tape attachment angle as one unit of operation. The structure is such that a track pattern is formed, that is, the structure is compatible with current devices.

The small tape cassette 3 is smaller than the standard tape cassette, and consists of a cassette housing 7 having a supply reel 5 and a take-up reel 6, and a lid 8 on the front surface of the cassette housing 7. This small tape cassette 3 is
The lid 8 is rotated around the upper bottle 9 to a horizontal position and is installed in an open state. Here, since the small tape guide drum 2 is assembled at a lower height than the reference plane of the device, as will be described later,
Opened lid 8 of attached small tape cassette 3
is located at a position somewhat higher than the top surface of the small tape guide drum 2, and the opened lid 8 of the small tape cassette 3 is slightly raised above the top surface of the small tape guide drum 2, so that a part of the lid 8 is slightly higher than the top surface of the small tape guide drum 2 in the top view. The tape guide drum 2 is placed over the top surface of the tape guide drum 2, that is, in close proximity to the small tape guide drum 2.
Further, with the small tape cassette 3 mounted, the tape guide (loading) pole, capstan 10, etc. are relatively fitted into the small tape cassette 3.

When a recording/playback operation is performed, the tape loading mechanism (not shown) operates and the tape guide pole moves along the trajectory.
The magnetic tape 4 moves along L ₁ and L ₂ to the final position shown by the solid line in FIG.
The tape is pulled out and loaded onto a predetermined tape path. That is, the magnetic tape 4 is pulled out from the supply reel 5, and the tension pole 11 and the guide pole 1
2. It is attached to the full-width erasing head 13, the impedance roller 14, and the guide roller 15, so that the running direction can be changed by about 90 degrees. Further, the magnetic tape 4 is spirally attached to the circumferential surface of the small tape guide drum 2 between the guide poles 16 and 17 over approximately 270 degrees. While the magnetic tape 4 is running while being attached to the small tape guide drum 2, the video head is
It rotates over 270 degrees to form one track on the magnetic tape 4, and video signals are recorded and reproduced. Further, the direction of the magnetic tape 4 is changed by about 180 degrees by a guide roller 18 so that it faces diagonally downward to the right in FIG.
0, attached to the audio control head 21, guided by the guide pole 22, held and driven by the pinch roller 23 and the capstan 10, enters the small tape cassette 3, and is taken up on the take-up reel 6. .

Here, the guide pole 12 on the entrance side of the small tape guide drum 2 in the tape running direction only moves to a position slightly beyond the left side of the small tape guide drum 2, and the tape guide pole 17 on the exit side moves only to a position slightly beyond the left side of the small tape guide drum 2. After passing the right side of the small tape guide drum 2, it further rotates about 90 degrees along the circumferential surface of the drum and moves to a position opposite to the small tape cassette 3. As a result, the magnetic tape 4 is released from the small tape guide drum 2 at a position substantially on the back side of the small tape cassette 3, that is, at a position far away from the small tape cassette 3.
The length of the tape along the tape path from this tape attachment release position to the take-up reel can be increased. However, even if the small tape guide drum 2 is disposed close to the small tape cassette 3, the tape length L from the tape splicing release position to the control head cannot be adjusted by making the tape path into a complicated shape. The predetermined value (79.244
mm), making the device 1 compatible with standard devices also in terms of the arrangement of the control head.

The tape path around the small tape guide drum will now be described with reference to FIGS. 3 and 4. Figure 4 is a view from the Y-axis side in Figure 3 showing the position and inclination of the guide pole;
A line 24 in the figure is the center line (generating line) of the tape 4. Of the tape passes loaded as above,
A tape path 25A on the supply reel side from just before the guide pole 16 and a tape path 25B on the take-up reel side from the vertical guide pole 20 are the magnetic tape 4.
This is a tape path that runs on the tape running height plane (reference plane) P in the small cassette 3 parallel to the deck plane in a posture perpendicular to the deck plane. Tape path 25C in the guide drum circumferential attachment section from guide pole 16 to guide pole 17
(A section between points A and F on the generatrix 24 in FIG. 4) is a tape path that gradually descends from the reference plane P as it progresses in the tape running direction, and the tape path 2 reaches from the guide roller 18 to the guide pole 19.
5D (section of point G-I of bus line 24 in Figure 4)
As it progresses in the tape running direction, it rises obliquely on a substantially straight line, recovers its height position, and finally becomes a tape path that coincides with the reference plane P.

In particular, the tape path 25C on the circumferential surface of the small tape guide drum 2 is formed through a point C where the center of the tape is lowered by the dimension ΔZ than the reference plane P, and is directed downward. Since the magnetic tape 4 is attached at a position lower than the reference surface P on the circumferential surface of the small tape guide drum 2, the height h from the reference surface P to the top surface of the small tape guide drum 2 is smaller than that of the conventional case. The tape cassette 3 is assembled so that the height of the top surface is kept low relative to the height of the attached tape cassette 3. As a result,
The height of the top surface of the small tape guide drum 2 is lower than the lower surface of the open lid 8 of the attached small tape cassette 3, and the lid 8 of the small tape cassette 3 overlaps with the small tape guide drum 2. It is installed in a positional relationship extremely close to the small tape guide drum 2.

Next, the inclination directions and functions of each guide pole and guide roller will be explained.

First, the small tape guide drum 2 is
It is inclined at an angle α (≒6°) in the arrow-X axis direction with respect to the axis.

The guide pole 16 on the inlet side of the small tape guide drum 2 in the tape running direction guides the magnetic tape 4 at the height of the reference plane P, and the magnetic tape 4 is placed on the incline of the small tape guide drum 2. This is to guide it toward the circumferential surface.

The inclination angle β, the inclination direction γ, and the tape winding angle ε of the guide pole 16 are determined by the following equations.

Here, φ is the inclination angle of the track on the magnetic tape,
θ is 1/2 of the tape wrapping angle on the drum that exceeds 180 degrees.

When calculating by substituting α = 6°, φ = 6°, and θ = 10° into each of the above equations, the guide pole 16 is inclined at β = 6° in the -X axis direction, and the tape is tilted at ε = 100°. It becomes a pole wrapped around. Note that this guide pole 16 is a tape oblique incidence pole in which the tape generatrix is obliquely incident when the tape is used as a reference, and cannot have a rotating roller structure, but is a cylindrical member.

Also, the midpoint C of the circumferential surface of the small tape guide drum 2
The descending dimension of the tape busbar relative to the reference plane P at △Z
is expressed by the following formula.

△Z=K _R・R+Kl・l+Kr・r However, K _R = sinα・cosθ−(π/2+θ)cosα・tanφ Kl=−cosα・sinφ−sinα・cosφ・sinθ Kr=−sinβ・(ε−sinε) R: radius of the small tape guide drum 2 r: radius of the guide pole 16 l: distance from the point where the tape is away from the guide pole 16 to point B. When calculating by substituting specific numerical values for each variable in the above formula, △Z=2.5 mm. Incidentally, the inclination angle α and the descending dimension △Z of the tape guide drum 2 are as follows:
When the inclination angle α is increased, the descending dimension ΔZ becomes smaller, resulting in a relationship in which the effect of lowering the drum height is reduced.

Next, looking at the guide pole group on the exit side with respect to the small tape guide drum 2 in the tape running direction, the guide pole 17 is inclined at an angle α ₁ (approximately 29 degrees) in the -X axis direction for simplicity. The tape has an angle ε ₁
(60°) If it is wrapped around guide pole 1
The slope S ₁ along the tape running path away from 7 and toward the guide roller 18 is determined as follows.

That is, the direction cosine perpendicular to the slope S ₁ is The inclination direction γs ₁ of the inclined surface S ₁ is tanγs ₁ =
m _s1 /l _s1 and the inclination angle αs ₁ are expressed as cos αs ₁ =ns1. Note that βs is expressed as α ₁ − (φ + α), and specifically, approximately
It is 29 degrees. When calculating by substituting specific numerical values for each variable in the above equation, the inclination direction (γs ₁ ) of the inclined surface S ₁ is −37°11′, and the inclination angle (αs ₁ ) is 24°46′.

The guide roller 18 is provided perpendicularly to the inclined surface _S1 , and its axis is orthogonal to the generatrix of the tape 4 entering and exiting, and the surrounding roller portion rotates in the direction of the arrow as the tape runs. It is configured to do this. As a result, even if the wrapping angle around the guide roller 18 is large, the tape 4 passes through this portion without a substantial increase in tension. That is,
The guide roller 18 functions to change the running direction of the tape 4 by approximately 180 degrees without increasing the tape running load. Further, this guide roller 18 is arranged at a position relatively close to the small tape guide drum 2. In addition, the guide pole 17 has the function of directing the tape away from the tape guide drum 2 so as to be attached to the guide roller 18 orthogonally thereto.

The guide pole 19 is for converting the tape that has come out from the guide roller 18 and runs parallel to the slope _S1 into a running path that is parallel to the take-up side deck surface _S0 , which is a horizontal plane. In this example,
Since the direction of the tape after passing through the guide pole 19 is determined to be the -Y-axis direction, the angle θ may be set to (90°-γs ₁ )=52°49'.
Further, the guide pole 19 is inclined at an angle β ₂ in the −Y-axis direction. The angle β ₂ is tan β ₂ = tan
It is expressed as (α/2)/cosθ, which is 19°57′. Furthermore, the relationship between the guide pole 19 and the tape height can be determined by changing the position of the guide pole 19 on the plan view, so that the tape length l of the tape that comes out from the guide roller 18 and reaches the guide pole 19 in an upward direction is determined. ₁
This is a relationship in which the length of the tape is changed and the height position of the tape is varied. In this embodiment, the guide pole 19
is disposed at a position relatively far away from the guide roller 18 and relatively close to the tape guide drum 2 so as to guide the tape at the height of the reference plane P.

As a result, the magnetic tape 4 has no tension difference in the width direction, and the tape running load is made comparable to that of a standard recording/reproducing device.
It can run attached to the tape guide drum 2 over about 270 degrees.

In addition, the small tape cassette 3 is installed so that its front surface is not parallel to the -X axis direction, which is the inclination direction of the tape guide drum 2, but is intentionally inclined at an angle κ with respect to the X axis. A small tape guide drum 2, a tape guide system, a fixed head, etc. are all incorporated between surfaces S ₂ and S ₃ that extend the left and right sides of the tape cassette forward. This makes the apparatus 1 even more compact than when the small tape cassette 3 is arranged parallel to the direction of inclination of the small tape guide drum 2.

Effects As described above, according to the magnetic recording/reproducing apparatus of the present invention, even when the guide drum is of a small diameter and is disposed close to the cassette mounting section, the distance from the guide drum to the control head is small. The tape length along the tape path can be adjusted without making the tape path between them a specially curved tape path.
This makes it possible to maintain compatibility with current equipment even if the guide drum is placed close to the cassette loading section. It has the advantage of being able to realize an ultra-compact device with

[Brief explanation of drawings]

1 and 2 are a plan view and a side view, respectively, of an embodiment of the magnetic recording/reproducing apparatus according to the present invention, and FIG. 3 is an enlarged view showing the arrangement and inclination of the tape guide member around the tape guide drum. The plan view and FIG. 4 are views seen from the Y-axis side in FIG. 3. 1... Magnetic recording and reproducing device, 2... Small tape guide drum, 3... Small tape cassette, 4...
Magnetic tape, 10... Capstan, 13... Full width erase head, 16, 17, 19... Guide pole, 18... Guide roller, 20... Vertical guide pole, 21... A/C head, 25D... Tape path.

Claims (1)

[Claims] 1. It has a small guide drum with a diameter that is 2/3 of the guide drum of a standard magnetic recording and reproducing device on which magnetic tape is wound approximately 180 degrees, and has an entrance to the small guide drum in the tape running direction. In a magnetic recording and reproducing apparatus, the magnetic tape is pulled out from a tape cassette by an entrance tape guide and an exit tape guide that guide the magnetic tape on the side and exit side, and wound approximately 270 degrees around the small guide drum. The guide and the exit-side tape guide move such that the movement distance of the latter is greater than the movement distance of the former, and the amount by which the magnetic tape is wound around the small guide drum on the exit-side tape guide side is the same as the entrance-side tape. The magnetic tape is wound asymmetrically around the tape guide drum so that the amount of winding is larger than the amount of winding on the guide side, and the tape length from the exit position of the small guide drum to the control head is determined by the standard magnetic recording/reproducing method. 1. A magnetic recording/reproducing device characterized by having a configuration identical to that of the device.