JP2000298897A - Intermediate gear and tape-driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate gear for using an inexpensive yoke plate. SOLUTION: A yoke plate 26 is attracted by a magnet plate 24 instead of the attraction of the magnet plate 24 by the yoke plate 26, the thickness of the yoke plate 26 is set to 0.19 mm or less, and the yoke plate 26 is exposed to the outside. Since no force is applied to the yoke plate 26 and the yoke plate 26 can be made thin, the magnetic flux of the magnet plate can be leaked to the extent that it can be detected by a magnetic sensor even if the yoke plate is formed by an inexpensive material with a small coercive force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate gear and a tape drive, and more particularly, to a digital video cassette (DVC), a video tape recorder, an 8 mm video tape recorder (8 mm VTR), and a digital audio tape recorder (DAT). The present invention relates to an intermediate gear and a tape driving device used for a tape driving unit of a cassette tape recorder or the like.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 61-63949 discloses that a hysteresis plate and a magnet plate are axially fixed to each other so as to face each other with a gap therebetween, and rotation is transmitted between them by a hysteresis torque. A reel base using a magnetic clutch is disclosed. It is also disclosed that a yoke plate is attached to a surface of the magnet plate opposite to the surface facing the hysteresis plate to increase the hysteresis torque.

On the other hand, Japanese Patent No. 2554009 also discloses that
A reel base using a similar magnetic clutch is disclosed. It is also disclosed that a magnetic sensor detects a magnetic flux emitted from a surface of the magnet plate opposite to a surface facing the hysteresis plate with a magnetic sensor to detect rotation.

Further, Japanese Patent No. 2588813 discloses a reel base using a similar magnetic clutch. Further, the yoke plate is positioned on the surface of the magnet plate opposite to the surface facing the hysteresis plate to increase the hysteresis torque and to reduce
It is disclosed that a material having a coercive force of [Oe] or more is used so that even if there is a yoke plate, the magnetic flux of the magnet plate leaks to an extent that can be detected by a magnetic sensor.

[0005]

SUMMARY OF THE INVENTION Japanese Patent Laid-Open No. 61-6394
No. 9 does not disclose the thickness or material of the yoke plate at all. Further, the yoke plate is concealed by the structure of the reel base, so that the magnetic sensor cannot be installed near the yoke plate. That is, no consideration is given to sensing the magnetic flux of the magnet plate with the magnetic sensor. On the other hand, in Japanese Patent No. 2554009, no yoke plate is used. That is, no consideration is given to how the magnetic sensor senses the magnetic flux of the magnet plate when the yoke plate is used. Further, in Japanese Patent No. 2588813, a yoke plate made of a material having a large coercive force is used, but such a material is expensive.

Accordingly, a first object of the present invention is to increase the hysteresis torque by using a yoke plate, and to leak the magnetic flux of the magnet plate to such an extent that the magnetic sensor can detect the yoke plate even if there is a yoke plate. Another object of the present invention is to provide an intermediate gear improved so that a yoke plate made of inexpensive material can be used. A second object of the present invention is to provide a tape drive using the intermediate gear.

[0007]

In a first aspect, the present invention provides a hysteresis plate (22) and a magnet plate (24, 2).
4 ') are coaxially fixed so that they face each other with a gap therebetween, and the hysteresis plate (22) and the magnet plates (24, 24') are provided with gears (23, G, 301) respectively.
And a gear (23) of the hysteresis plate (22) meshes with a first external gear, and the magnet plate (24,
24 ′) is meshed with the second external gear, so that the intermediate gear (200) transmitting rotation between the first external gear and the second external gear by hysteresis torque. , 300), wherein the hysteresis plate (22) of the magnet plate (24, 24 ′).
An intermediate gear having a yoke plate (26) having a thickness of 0.19 mm or less adsorbed by magnetic force on a surface opposite to the surface facing the yoke, and exposing the yoke plate (26) to the outside. (200, 300). In the intermediate gear according to the first aspect, a structure in which the magnet plate is attracted to the yoke plate (Japanese Patent No. 2588813) is used,
The yoke plate is attracted to the magnet plate. For this reason, no external force is applied to the yoke plate, and the mechanical strength may be weak, and the thickness can be reduced to 0.19 mm or less. As a result, even if the yoke plate is formed of an inexpensive material having a small coercive force, the magnetic flux of the magnet plate leaks to the extent that the magnetic sensor can detect it. Further, since the yoke plate is exposed to the outside, the magnetic sensor can be installed near the yoke plate. Furthermore, since the yoke plate is simply adsorbed to the magnet plate, it is necessary to change the thickness and material of the yoke plate by replacing it with a yoke plate of a different thickness or material, or by stacking multiple yoke plates and adsorbing them. Can be easily performed. Thus, adjustment for obtaining a desired torque value can be easily performed. Furthermore, the intermediate gear having the above configuration can make the yoke plate thinner,
The whole can be made thin.

[0008] In a second aspect, the present invention relates to an intermediate gear (200, 300) having the above configuration, wherein the yoke plate (2,
6) is one of a stainless steel plate, a magnetic alloy plate and a plated steel plate.
300). The intermediate gear according to the second aspect uses an inexpensive stainless steel plate, magnetic alloy plate, or plated steel plate, and can be manufactured at low cost. Stainless steel sheet
This is advantageous from the viewpoint of availability, price, and workability. The magnetic alloy plate is advantageous from the viewpoint of high magnetic permeability and high coercive force. Plated steel sheets are advantageous from the viewpoint of rust resistance.

In a third aspect, the present invention provides the intermediate gear (200) having the above-mentioned configuration, wherein the magnet plate (24) is provided.
Are formed by molding a part of the magnet plate (24) as a gear (G).
0). In the intermediate gear according to the third aspect,
Since a part of the magnet plate is formed into a gear, there is no need to manufacture the gear separately and mount it on the magnet plate, thereby reducing the number of parts and the number of assembling steps, and reducing the manufacturing cost.

[0010] In a fourth aspect, the present invention provides the intermediate gear (300) having the above structure, wherein the magnet plate (2) is provided.
4 ') is a magnet plate (24') to which an external gear (301) is fixed.
0). In the intermediate gear according to the fourth aspect,
The magnet plate and gear can be manufactured separately.

According to a fifth aspect, the present invention provides a reel motor (41), a take-up reel table (44R), a supply reel table (44L), and an intermediate gear (200). , The intermediate gear (200) swings toward the take-up reel table (44R) and the reel motor (4).
The rotation of 1) is transmitted to the take-up reel table (44R), and when the tape is rewound, the intermediate gear (200) swings toward the supply reel table (44L) to rotate the reel motor (41). In the tape drive (1200) provided with a mechanism for transmitting to the supply reel table (44L), the intermediate gear (200) includes a hysteresis plate (2).
2) and the magnet plate (24) are axially fixed so as to face each other with a gap therebetween, and the hysteresis plate (2) is
Gear (2) and the magnet plate (24).
3, G), and the gear (23) of the hysteresis plate (22) or the gear (G) of the magnet plate (24).
One of the gears is meshed with a motor gear (42) interlocked with the reel motor (41), and the other is selectively meshed with a gear of the take-up reel base (44R) or a gear of the supply reel base (44L). With this, rotation is transmitted by hysteresis torque between the motor gear (42) and the gear of the take-up reel table (44R) or the gear of the supply reel table (44L), and the magnet plate (24) The hysteresis plate (22).
A yoke plate (26) having a thickness of 0.19 mm or less is attracted by magnetic force to a surface opposite to the surface opposite to the above, and the yoke plate (26) is exposed to the outside. The present invention provides a tape driving device (1200) that performs the following. The tape drive according to the fifth aspect employs an intermediate gear having a structure in which the yoke plate is attracted to the magnet plate, instead of a structure in which the magnet plate is attracted to the yoke plate (Japanese Patent No. 2588813). For this reason, no external force is applied to the yoke plate, and the mechanical strength may be weak, and the thickness can be reduced to 0.19 mm or less. As a result, even if the yoke plate is formed of an inexpensive material having a small coercive force, the magnetic flux of the magnet plate leaks to the extent that the magnetic sensor can detect it. Further, since the yoke plate is exposed to the outside, the magnetic sensor can be installed near the yoke plate. Furthermore, since the yoke plate is simply adsorbed to the magnet plate, it is necessary to change the thickness and material of the yoke plate by replacing it with a yoke plate of a different thickness or material, or by stacking multiple yoke plates and adsorbing them. Can be easily performed. Thus, adjustment for obtaining a desired torque value can be easily performed. Further, the whole can be made thin.

According to a sixth aspect, the present invention provides a tape drive (1200) having the above-mentioned configuration, wherein the yoke plate (2)
A tape drive device (1) characterized in that a magnetic sensor (S) is installed in the vicinity of (6) and opposite to the magnet plate (24) via the yoke plate (26).
200). In the tape drive device according to the sixth aspect, the rotation of the magnet plate can be suitably detected by detecting the magnetic flux of the magnet plate leaking through the yoke plate with the magnetic sensor.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this.

First Embodiment FIG. 1 shows an intermediate gear 20 according to a first embodiment of the present invention.
0 is a sectional view. A hysteresis plate 22 is fixed to the rotating shaft 21 of the intermediate gear 200. A gear 23 is mounted around the hysteresis plate 22. A magnet plate 24 is rotatably mounted on the rotating shaft 21. A gear G is formed on the magnet plate 24 at the same time. The magnet plate 2
The upper surface of 4 is opposed to the lower surface of the hysteresis plate 22 with a gap. The width of the gap is adjusted by the washer 25. A disk-shaped yoke plate 26 is attracted to the lower surface of the magnet plate 24 by magnetic force.
The hysteresis plate 22 is made of martensitic stainless steel quenched material, Mn steel magnetic material, or Cr-Co.
Made of steel-based magnetic material. The magnet plate 24 is Nd
-Fe-B based magnet, Sm-Co based magnet or ferrite based magnet, and is a sintered magnet or a resin magnet. The yoke plate 26 is a ferritic, martensitic, precipitation hardening stainless steel plate, a magnetic alloy plate such as permalloy or permendur, or a plated steel plate such as an electrogalvanized steel plate. The thickness τ is 0.19 mm or less.

FIG. 2 shows the yoke plate 2 of the intermediate gear 200.
6 is a table showing the results of measuring the torque value and the surface magnetic force of the yoke plate 26 with respect to the thickness τ of No. 6; Since the surface magnetic force that can be sufficiently sensed by the magnetic sensor S is preferably 30 [Gauss] or more,
It is understood that the thickness of the yoke plate 26 should be set to 0.19 or less. It can also be seen that the torque value can be adjusted by changing the thickness of the yoke plate 26.

Returning to FIG. 1, the first gear meshing with the gear 23
When an external gear (not shown) is rotated by a motor (not shown), the gear 23 rotates the hysteresis plate 22. When the resistance is small, the magnet plate 24 rotates and the gear G also rotates due to the hysteresis torque.
Therefore, the second external gear (not shown) engaged with the gear G rotates. When the resistance to the rotation of the second external gear (not shown) increases, the magnet plate 24 does not rotate, and the hysteresis plate 22 idles.

The yoke plate 26 has a thickness τ of 0.19 m.
m or less, the magnetic flux of the magnet plate 24 is passed to the extent that the magnetic sensor S can sufficiently detect it. Thus, the magnetic sensor S can detect the rotation of the magnet plate 26.

According to the above-described intermediate gear 200, the yoke plate 26 is merely attracted to the magnet plate 24, so that no mechanical strength is required, and the thickness τ is 0.19 mm.
You can: For this reason, even if the yoke plate 26 is made of an inexpensive material, the magnetic flux of the magnet plate 24 passes through the magnetic sensor S enough to be sufficiently detected. Also, since the whole can be made thin, it is suitable as an intermediate gear installed in a space where there is no room. Also, the driven gear G is connected to the magnet plate 2
4, the number of parts and the number of assembling steps can be reduced, and the manufacturing cost can be reduced.

-Second Embodiment- FIG. 3 is a structural explanatory view showing a state in which a tape driving device 1200 according to a second embodiment of the present invention takes up a tape. The intermediate gear 200 is the intermediate gear 200 according to the first embodiment. When the reel motor 41 rotates forward to wind the magnetic tape T, the motor gear 42 rotates forward in conjunction therewith, and the hysteresis plate 22 of the intermediate gear 200 in which the gear 23 meshes with the motor gear 42 also rotates forward. . Then, the pendulum plate 43 supporting the intermediate gear 200 swings toward the take-up reel base 44R, and the gear G of the intermediate gear 200 meshes with the gear of the take-up reel base 44R. Since the gear G of the intermediate gear 200 rotates forward due to the hysteresis torque, the take-up reel base 44R rotates forward, and the magnetic tape T is wound around the take-up reel base 44R. At the end of tape winding, the rotation of the take-up reel base 44R is stopped with a force larger than the hysteresis torque, so that the gear G of the intermediate gear 200 stops, the magnet plate 24 stops, and the hysteresis plate 22 idles.

FIG. 4 is an explanatory diagram showing the state of the tape drive 1200 when the tape is rewound. When the reel motor 41 rotates in reverse to rewind the magnetic tape T, the motor gear 42 rotates in reverse in conjunction therewith, and the intermediate gear 20 in which the gear 23 meshes with the motor gear 42.
The zero hysteresis plate 22 also rotates in the reverse direction. Then, the pendulum plate 43 supporting the intermediate gear 200 is moved to the supply reel table 4.
It swings to the 4L side, and the gear G of the intermediate gear 200 meshes with the gear of the supply reel base 44L. Since the gear G of the intermediate gear 200 is reversely rotated by the hysteresis torque,
The supply reel base 44L rotates in the reverse direction, and the magnetic tape T is rewound on the supply reel base 44L. At the tape rewind end, the rotation of the supply reel base 44L is stopped with a force larger than the hysteresis torque.
Gear G stops, the magnet plate 24 stops, and the hysteresis plate 22 idles.

According to the tape drive 1200 described above,
By using the intermediate gear 200, the reel base 44
It is not necessary to incorporate a magnetic clutch in each of R and 44L, so that the configuration can be simplified and the whole can be thinned.

Third Embodiment FIG. 5 is a sectional view of an intermediate gear according to a third embodiment of the present invention. The intermediate gear 300 uses a magnet plate 24 'to which an external gear 301 is fixed, instead of the magnet plate 24 of the intermediate gear 200 according to the third embodiment. The material of the external gear 301 is, for example, an engineering plastic such as a polyacetal resin. According to the above-described intermediate gear 300, the external gear 301 can be easily exchanged, so that the gear pitch can be easily changed, and it is possible to support a wide range of applications. Further, maintainability for dealing with gear breakage and the like is improved.

[0023]

According to the intermediate gear and the tape drive of the present invention, the following effects can be obtained. (1) Since the yoke plate is simply attracted to the magnet plate, no external force is applied to the yoke plate, the thickness can be reduced, and even if the yoke plate is formed of an inexpensive material, the magnet plate can be used. Can be leaked to such an extent that the magnetic flux can be detected by the magnetic sensor. Further, since the yoke plate is exposed to the outside, the magnetic sensor can be installed near the yoke plate. Furthermore, it is possible to easily change the thickness and material of the yoke plate by replacing the yoke plate with a different thickness or material, or by stacking and adsorbing a plurality of yoke plates. Adjustment can be performed easily. (2) Since an inexpensive stainless steel plate, magnetic alloy plate or plated steel plate can be used, it can be manufactured at low cost. (3) If a part of the magnet plate is formed into a gear, the number of parts and the number of assembling steps can be reduced, and the manufacturing cost can be reduced. (4) The intermediate gear can be made thin as a whole, and is suitable for use in a space where there is not enough room. (5) The tape drive can be made thinner as a whole, and is suitable for use in recent thinned tape drives.

[Brief description of the drawings]

FIG. 1 is a sectional view of an intermediate gear according to a first embodiment of the present invention.

FIG. 2 is a table showing a result of measuring a torque value and a surface magnetic force with respect to a thickness of a yoke plate in the intermediate gear of FIG. 1;

FIG. 3 is an explanatory diagram illustrating a state of a tape driving device according to a second embodiment of the present invention when a tape is wound;

FIG. 4 is an explanatory diagram illustrating a state of a tape drive according to a second embodiment of the present invention when the tape is rewound.

FIG. 5 is a sectional view of an intermediate gear according to a third embodiment of the present invention.

[Explanation of symbols]

 24, 24 'magnet plate 22 hysteresis plate 26 yoke plate τ thickness of yoke plate S magnetic sensor 200, 300 intermediate gear 1200 tape drive

Claims (6)

[Claims] 1. A hysteresis plate (22) and a magnet plate (24, 24 ') are axially fixed to each other so as to face each other with a gap therebetween, and the hysteresis plate (22) and the magnet plate (24, 24') are fixed. 24 ') with gears (23,
G, 301), the gear (23) of the hysteresis plate (22) is meshed with a first external gear, and the gear (G, 301) of the magnet plate (24, 24 ') is connected to a second external gear. An intermediate gear for transmitting rotation by a hysteresis torque between the first external gear and the second external gear by meshing with the hysteresis plate of the magnet plate (24, 24 ′). On the surface opposite to the surface facing (22), a thickness of 0.1
An intermediate gear (200, 300) wherein a yoke plate (26) of 9 mm or less is attracted by magnetic force and the yoke plate (26) is exposed to the outside. 2. The intermediate gear (200, 3) according to claim 1,
(00), the intermediate gear (200, 300), wherein the yoke plate (26) is any one of a stainless steel plate, a magnetic alloy plate and a plated steel plate. 3. The intermediate gear (200) according to claim 1, wherein the magnet plate (24) comprises:
An intermediate gear (20) characterized in that a part of the magnet plate (24) is formed as a gear (G).
0). 4. The intermediate gear (300) according to claim 1, wherein the magnet plate (24 ′).
Is a magnet plate (2) to which an external gear (301) is fixed.
4 ′), the intermediate gear (300). 5. A reel motor (41), a take-up reel table (44R), a supply reel table (44L), and an intermediate gear (200). The rotation of the reel motor (41) is transmitted to the take-up reel table (44R) by swinging toward the take-up reel table (44R), and when the tape is rewound, the intermediate gear (200) is connected to the supply reel table. (44L) side to rotate the reel motor (41) to rotate the supply reel base (44L).
In the tape drive (1200) provided with a mechanism for transmitting the magnetic force to the motor, the intermediate gear (200) is coaxially fixed so that the hysteresis plate (22) and the magnet plate (24) face each other with a gap therebetween. A gear (23, G) is provided on each of the hysteresis plate (22) and the magnet plate (24), and a gear (23) of the hysteresis plate (22) or a gear (G) of the magnet plate (24) is provided. One of the motor gears (4) is linked to the reel motor (41).
2), and the other is selectively meshed with the gear of the take-up reel base (44R) or the gear of the supply reel base (44L), so that the motor gear (42) and the take-up reel base (44R) are engaged. ) Or the gear of the supply reel base (44L) for transmitting rotation by hysteresis torque, and a surface of the magnet plate (24) facing the hysteresis plate (22). On the opposite surface, a yoke plate (2
6) is attracted by magnetic force, and the yoke plate (2)
A tape drive (1200), characterized in that (6) is exposed to the outside. 6. The tape drive according to claim 5, wherein
00), a magnetic sensor (S) is provided near the yoke plate (26) and at a position facing the magnet plate (24) via the yoke plate (26). Tape drive (1200).