GB2308725A

GB2308725A - Tensioning the capstan timing belt of a VCR

Info

Publication number: GB2308725A
Application number: GB9626990A
Authority: GB
Inventors: Seong-Ick Ahn
Original assignee: Daewoo Electronics Co Ltd
Current assignee: WiniaDaewoo Co Ltd
Priority date: 1995-12-29
Filing date: 1996-12-27
Publication date: 1997-07-02
Also published as: JPH09198745A; GB9626990D0; KR100211874B1; KR970050607A

Description

CAPSTAN MOTOR ASSEMBLY FOR A VCR The present invention relates to a video cassette recorder, and more particularly to a capstan motor assembly for a video cassette recorder which can effectively drive reel tables.

Generally, a video cassette recorder (hereinafter, simply referred to VCR) is a device for recording an image and/or an audio signal onto a magnetic tape running along a running system or for reproducing signals recorded in the magnetic tape. The magnetic tape is wound around a pair of reels provided in a cassette, and when the cassette is loaded into a deck of a tape recorder according to a loading mechanism, the pair of reels are respectively mounted on a take-up reel table and a supply reel table installed on the deck. After that, the take-up reel table and the supply reel table are rotated by a capstan motor, thereby carrying out selected running operations such as playing, recording, fast forwarding and rewinding.At this time, the magnetic tape is drawn out from one reel and is wound around the other reel according to the rotating directions of the take-up reel table and the supply reel table.

FIG. 4 shows an internal structure of a conventional VCR 500.

As shown in FIG. 4, VCR 500 has a base 510. Installed in a front portion of an upper surface of base 510 are a supply reel table 512 and a take-up reel table 514, which are positioned at a predetermined distance apart from each other so as to receive a supply reel and a take-up reel of a cassette, respectively. Supply reel table 512 is integrally formed at its lower portion with a first gear 522, and take-up reel table 514 is integrally formed at its lower portion with a second gear 524. Provided in a rear portion of the upper surface of base 510 are a head drum 505, which is fixedly installed with a certain inclination, and a mode motor assembly 507 for controlling the operating modes of VCR 500. In addition, a capstan motor 520 for driving both supply reel table 512 and take-up reel table 514 is installed on a bottom of base 510.

An idler assembly 516, which moves in the left or right direction according to a rotating direction of capstan motor 520 so as to rotate supply reel table 512 or take-up reel table 514, is disposed between supply reel table 512 and take-up reel table 514. Idler assembly 516 is pivotably coupled to a center gear 552 mounted on the upper surface of base 510. Disposed below and coaxially with center gear 552 is a friction gear 550 having a predetermined frictional torque.

Capstan motor 520 is integrally formed at its upper surface with a first pulley 533.

First pulley 533 is connected to second pulley 540, which is positioned at a predetermined distance apart from first pulley 533 by a belt 535. Second pulley 540 is provided at its upper surface with a gear portion 545, which is in mesh with a first intermediate gear 518 being engaged with friction gear 550.

In order to transfer the rotational force of capstan motor 520 to supply reel table 512 or take-up reel table 514 through idler assembly 516, second and third intermediate gears 532 and 534, which are in mesh with each other, are interposed between idler assembly 516 and first gear 522 of supply reel table 512. In addition, fourth and fifth intermediate gears 542 and 544, which are in mesh with each other, are interposed between idler assembly 516 and second gear 524 of take-up reel table 514.

The driving mechanism of conventional VCR 500 having the above structure is as follows.

When capstan motor 520 rotates in the clockwise direction, the clockwise directional driving force of capstan motor 520 is transferred to center gear 552 by way of first pulley 533, second pulley 540, first intermediate gear 518, and friction gear 550 so that idler assembly 516 moves towards take-up reel table 514 and is engaged with fourth intermediate gear 542. As a result, second gear 524 integrally formed at the lower portion of take-up reel table 514 is driven by fourth and fifth intermediate gears 542 and 544, so a magnetic tape 501 wound around the supply reel of the cassette is drawn out from the supply reel and moves along a tape running route, thereby winding around the take-up reel of the cassette.

In addition, when capstan motor 520 rotates in the counter-clockwise direction, the counter-clockwise directional driving force of capstan motor 520 is transferred to center gear 552 by way of first pulley 533, second pulley 540, first intermediate gear 518, and friction gear 550 so that idler assembly 516 moves towards supply reel table 512 and is engaged with third intermediate gear 534. As a result, first gear 522 integrally formed at the lower portion of supply reel table 512 is driven by second and third gears 532 and 534, so magnetic tape 501 which has been wound around the take-up reel of the cassette is drawn out from the take-up reel and moves along the tape running route and winding around the supply reel of the cassette.

However, conventional VCR 500 constructed as mentioned above has following the disadvantages.

Firstly, since belt 535 for connecting first and second pulleys 533 and 540 of capstan motor 520 is generally made by a rubber, belt 535 can become expanded or hardened when it has been used for a long time. In either of these cases, belt 535 does not reliably transfer the rotational force of capstan motor 520 to the reel tables or, in an extreme case, belt 535 is cut off.

Furthermore, when impurities such as dust are collected between belt 535 and first and second pulleys 533 and 540, belt 535 slips while running on first and second pulleys 533 and 540. In this case, a frictional force between belt 535 and first and second pulleys 533 and 540 is reduced, so the driving efficiency of capstan motor 520 is reduced.

The present invention has been made to solve the problems of the prior art, and accordirigly, it is an object of the present invention to provide a capstan motor assembly for a VCR which can effectively drive reel tables.

To accomplish the above object of the present invention, there is provided a capstan motor assembly for a video cassette tape recorder having a base on which a supply reel table and a take-up table are mounted, the capstan motor comprising: a capstan motor for driving the supply reel table or the take-up table, the capstan motor being mounted on a bottom of the base, the capstan motor rotating in clockwise or counter-clockwise directions; a first timing gear integrally formed at an upper surface of the capstan motor; a second timing gear positioned at a first predetermined distance apart from the first timing gear; a timing belt for connecting the first and second timing gears to each other; and a first means for tensioning the timing belt.

According to a preferred embodiment of the present invention, the first means includes a frame which is fixed to the bottom of base and is positioned at a predetermined distance apart from the timing belt, first and second connecting rods which are spaced at a predetermined distance apart from each other, a second means for rotatably supporting the timing belt, and a third means for biasing the second means towards the timing belt. First ends of the first and second connecting rods are respectively coupled to upper portions of the frame. Second ends of the first and second connecting rods respectively extend to a first position corresponding to a second position of the timing belt. The second means is disposed between the first and second connecting rods.

The second means includes a cylindrical roller provided with an engagement portion which is rotatably engaged with the timing belt. In addition, the third means includes first and second tension springs. The first tension spring is disposed between the second end of the first connecting rod and a first position in a front lower wall of the U-shaped frame. The second tension spring is disposed between the second end of the second connecting rod and a second position in the front lower wall of the U-shaped frame.

The driving mechanism of the VCR having the capstan motor assembly according to the present invention is as follows.

When the capstan motor rotates in the clockwise direction, the clockwise directional driving force of the capstan motor is transferred to the second timing gear by way of the first timing gear and the timing belt. At this time, since the cylindrical roller applies a predetermined pressure to the timing belt, the timing belt can be reliably engaged with the first and second timing gears, so the driving efficiency of the capstan motor improves.

Then, the driving force of the capstan motor is transferred to an idler assembly by way of a plurality of intermediate gears so that the idler assembly moves towards the take-up reel table and transfers the driving force of the capstan motor to the take-up reel table. As a result, a magnetic tape wound around the supply reel of the cassette is drawn out from the supply reel and moves along a tape running route and thereby winding around the take-up reel of the cassette.

In addition, when the capstan motor rotates in the counter-clockwise direction, the idler assembly moves towards the supply reel table and transfers the driving force of the capstan motor to the supply reel table. As a result, the magnetic tape which has been wound around the take-up reel of the cassette is drawn out from the take-up reel and wound around the supply reel of the cassette.

As described above, the capstan motor assembly according to the present invention can apply a pressure to the timing belt by means of the tensioning apparatus while the driving mechanism is being carried out, so the timing belt is reliably engaged with first and second timing gears, and thereby the driving force of the capstan motor is effectively transferred to the supply reel table or the take-up table.

Further, since the travelling of the timing belt is guided by the engagement portion of the cylindrical roller, the timing belt does not separate from the first and second timing gears while it travels along the first and second gears.

Furthermore, since the driving force of the capstan motor is transferred to the supply reel table or to the take-up reel table through the timing belt, the VCR having the capstan motor assembly has a long life as compared with the life of the conventional VCR having a rubber belt.

The above object and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings, in which: FIG. 1 is a perspective view showing an inner structure of a VCR according to one embodiment of the present invention; FIG. 2 is a bottom view of the VCR shown in FIG. 1, for illustrating a capstan motor assembly according to one embodiment of the present invention; FIG. 3 is a perspective view showing a tensioning apparatus coupled to a timing belt of a capstan motor assembly according to one embodiment of the present invention; and FIG. 4 is a perspective view showing an inner structure of a conventional VCR.

Hereinafter, the preferred embodiment of the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1 shows an internal structure of a VCR 100 having a capstan motor assembly 200 according to the present invention.

As shown in FIG. 1, VCR 100 has a base 110. Installed in a front portion of an upper surface of base 110 are a supply reel table 112 and a take-up reel table 114, which are positioned at a predetermined distance apart from each other so as to receive a supply reel and a take-up reel of a cassette, respectively. Supply reel table 112 is integrally formed at its lower portion with a first gear 122, and take-up reel table 114 is integrally formed at its lower portion with a second gear 124. Provided in a rear portion of the upper surface of base 110 are a head drum 105, which is fixedly installed with a certain inclination, and a mode motor assembly 107 for controlling the operating modes of VCR 100. In addition, capstan motor assembly 200 according to the present invention is installed on a bottom of base 110 so as to drive supply reel table 112 or take-up reel table 114.

Referring to FIG. 2, capstan motor assembly 200 includes a capstan motor 210 which rotates in a clockwise or counter-clockwise direction according to an operating mode, a first timing gear 220 integrally formed at an upper surface of capstan motor 210, a second timing gear 240 positioned at a predetermined distance apart from first timing gear 220, a timing belt 230 for connecting first and second timing gears 220 and 240 to each other, and a tensioning apparatus 300 for tensioning timing belt 230.

As is well known, timing belt 230 is formed at its inside with a plurality of teeth in such a manner that it can be engaged with first and second timing gears 220 and 240.

FIG. 3 shows tensioning apparatus 300 coupled to timing belt 230. As shown in FIG.

3, tensioning apparatus 300 comprises a frame 310 which is fixed to the bottom of base 110 and which is positioned at a predetermined distance apart from timing belt 230. According to the preferred embodiment of the present invention, frame 310 has a substantially U-shape, and one side wall of frame 310 is fixed to the bottom of base 110 by a fastening means such as welding.

Tensioning apparatus 300 further comprises a first connecting rod 320 and a second connecting rod 322, which are disposed in opposition to each other and are respectively hinged to inner side walls of U-shaped frame 310, comprises a cylindrical roller 330 which is disposed between first connecting rod 220 and second connecting rod 322 and is rotatably coupled to timing belt 230, and comprises first and second tension springs 324 and 326 for biasing cylindrical roller 330 towards timing belt 230.

First ends of first and second connecting rods 320 and 322 are respectively attached to the upper inner walls of U-shaped frame 310 by a pair of first coupling pins 312, and second ends of first and second connecting rods 320 and 322 respectively extend to a position corresponding to the position of timing belt 230 and are coupled to the outside walls of cylindrical roller 330 by a pair of second coupling pins 334.

Cylindrical roller 330 is formed with an engagement portion 332 which is rotatably engaged with timing belt 230 in order to permit timing belt 230 to stably rotate. According to other embodiment of the present invention, a spherical roller can be used instead of cylindrical roller 330.

First tension spring 324 is disposed between the second end of first connecting rod 320 and a front lower wall of U-shaped frame 310, and second tension spring 326 is disposed between the second end of second connecting rod 322 and the front lower wall of U-shaped frame 310. They are fixedly positioned at the above positions by a fastening means such as welding. Since cylindrical roller 330 is forced towards timing belt 230 by the biasing force of first and second tension springs 324 and 326, cylindrical roller 330 applies a predetermined pressure to timing belt 230. Accordingly, even when it has been used for a long time, timing belt 230 can be securely engaged with first and second timing gears 220 and 240 so that the driving force of capstan motor 210 can be effectively transferred to supply reel table 112 or take-up reel table 114.

Referring again to FIG. 1, an idler assembly 116, which moves in the left or right direction according to a rotating direction of capstan motor 210 so as to rotate supply reel table 112 or take-up reel table 114, is disposed between supply reel table 112 and take-up reel table 114. Idler assembly 116 is pivotably coupled to a center gear 152 mounted on the upper surface of base 110. Disposed below and coaxially with center gear 152 is a friction gear 150 having a predetermined frictional torque. Second timing gear 24'0 is provided at its upper surface with a third gear 145 which is in mesh with a first intermediate gear 118 being engaged with friction gear 150.

In order to transfer the rotational force of capstan motor 210 to supply reel table 112 or take-up reel table 114 through idler assembly 116, second and third intermediate gears 132 and 134, which are in mesh with each other, are interposed between idler assembly 116 and first gear 122 of supply reel table 112. In addition, fourth and fifth intermediate gears 142 and 144, which are in mesh with each other, are interposed between idler assembly 116 and second gear 124 of take-up reel table 114.

The driving mechanism of VCR 100 having capstan motor assembly 200 according to the present invention is as follows.

When capstan motor 210 rotates in the clockwise direction, the clockwise directional driving force of capstan motor 210 is transferred to second timing gear 240 by way of first timing gear 220 and timing belt 230. At this time, the travelling of timing belt 230 is guided by engagement portion 332 of cylindrical roller 330 so that timing belt 230 does not separate from first and second timing gears 220 and 240. In addition, since cylindrical roller 330 applies the predetermined pressure to timing belt 230, timing belt 230 can be reliably engaged with first and second timing gears 220 and 240, so the driving efficiency of capstan motor 210 improves.

Then, the driving force of capstan motor 210 is transferred to center gear 152 by way of third gear 145 formed at the upper surface of second timing gear 240, first intermediate gear 118, and friction gear 150 so that idler assembly 116 moves towards take-up reel table 114 and is engaged with fourth intermediate gear 142. As a result, second gear 124 integrally formed at the lower portion of take-up reel table 114 is driven by fourth and fifth intermediate gears 142 and 144, so a magnetic tape 101 wound around the supply reel of the cassette is drawn out from the supply reel and moves along a tape running route, thereby winding around the take-up reel of the cassette.

In addition, when capstan motor 210 rotates in the counter-clockwise direction, the counter-clockwise directional driving force of capstan motor 210 is transferred to center gear 152 by way of first timing gear 220, second timing gear 240, first intermediate gear 118, and friction gear 150. At this time, since capstan motor 210 rotates in the counter-clockwise direction, idler assembly 116 moves towards supply reel table 112 and is engaged with third intermediate gear 134. As a result, first gear 122 integrally formed at the lower portion of supply reel table 112 is driven by second and third gears 132 and 134, so magnetic tape 101 which has been wound around the take-up reel of the cassette is drawn out from the take-up reel and moves along the tape running route, thereby winding around the supply reel of the cassette.

As described above, the capstan motor assembly according to the present invention can apply a pressure to the timing belt by means of the tensioning apparatus while the driving mechanism is being carried out, so the timing belt is reliably engaged with the first and second timing gears, and thereby the driving force of the capstan motor is effectively transferred to the supply reel table or the take-up table.

Furthermore, since the driving force of the capstan motor is transferred to the supply reel table or to the take-up reel table through the timing belt, the VCR having the capstan rnotor assembly has a longer life than the conventional VCR having a rubber belt.

Although the preferred embodiment of the invention has been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiment, but various changes and modifications can be made within the spirit and scope of the invention as defined by the appended claims.

Claims

CLAIMS:

1. A capstan motor assembly for a video cassette tape recorder having a base on, which a supply reel table and a take-up table are mounted and a capstan motor for driving the supply reel table or the take-up table, the capstan motor being mounted on a bottom of the base, the capstan motor rotating in clockwise and counter-clockwise directions, characterized by comprising: a first timing gear integrally formed at an upper surface of the capstan motor; a second timing gear positioned at a first predetermined distance apart from the first timing gear; a timing belt for connecting the first and second timing gears to each other; and a first means for tensioning the timing belt.

2. The capstan motor assembly as claimed in claim 1, characterized in that the first means includes a frame which is fixed to a bottom of the base and is positioned at a second predetermined distance apart from the timing belt, first and second connecting rods which are spaced at a third predetermined distance apart from each other, a second means for rotatably supporting the timing belt, and a third means for biasing the second means towards the timing belt, first ends of the first and second connecting rods being respectively coupled to upper portions of the frame, second ends of the first and second connecting rods respectively extending to a first position corresponding to a second position of the timing belt, the second means being disposed between the first and second connecting rods.

3. The capstan motor assembly as claimed in claim 2, characterized in that the second means includes a cylindrical roller.

4. The capstan motor assembly as claimed in claim 3, characterized in that the cylindrical roller is rotatably coupled to the second ends of the first and second connecting rods.

5. The capstan motor assembly as claimed in claims 3 or 4, characterized in that the cylindrical roller is provided with an engagement portion which is rotatably engaged with the timing belt.

6. The capstan motor assembly as claimed in any one of claims 2 to 5, characterized in that the frame has a substantially U-shape, one outside wall of the frame being welded to the bottom of the base.

7. The capstan motor assembly as claimed in any one of claims 2 to 6, characterized in that the first ends of the first and second connecting rods are respectively hinged to upper inner walls of the U-shaped frame by a pair of first coupling pins.

8. The capstan motor assembly as claimed in any one of claims 3 to 7, characterized in that the second ends of the first and second connecting rods are respectively coupled to outside walls of the cylindrical roller by a pair of second coupling pins.

9. The capstan motor assembly as claimed in any one of claims 6 to 8, characterized in that the third means includes first and second tension springs, the first tension spring being disposed between the second end of the first connecting rod and a third position in a front lower wall of the U-shaped frame, the second tension spring being disposed between the second end of the second connecting rod and a fourth position in the front lower wall of the U-shaped frame, the third position being spaced at a fourth predetermined distance apart from the fourth position.

10. A capstan motor assembly constructed and arranged substantially as herein described with reference to or as shown in the accompanying drawings.