JPH0227394Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a power transmission device used in a magnetic tape winding drive path of a magnetic recording/reproducing device or the like.

Conventional Structure and Problems Therein FIG. 1 shows a tape running system of a conventional VHS type VTR. Reference numeral 31 denotes a cassette half, which houses a supply reel 32 and a take-up reel 33. 1st
The state shown in the figure is the playback mode, and the cassette half 3
The tape 34 pulled out from the tape 34 is wound around each travel regulation post, and is wrapped around a cylinder 35 having a video head.
The belt is wound around the shaft, pressed between the capstan shaft 36 and the pinch roller 37, and sent out at a constant speed by the rotational torque transmitted from the capstan motor 38 to the belt 39 and flywheel 40.
Further, the tape 34a sent out from the capstan shaft 36 rotates the take-up reel stand 44 in the direction of the arrow using the reel motor 41 as a driving source via the motor pulley 42 and the idler 43, and is fitted onto the take-up reel stand 44. The winding reel 33 is rotated and the film is wound up. At this time, the rotational torque of the take-up reel stand 44 is kept stable and appropriate by electrically controlling the reel motor 41. Next, reverse playback mode (runs the tape in the opposite direction to playback,
To explain the mode in which the screen is viewed in reverse, the capstan motor 38 rotates in the opposite direction to playback, and the tape 34 pressed between the capstan shaft 36 and the pinch roller 37 is sent out in the direction of the dotted arrow. The reel motor 41 rotates in the direction of the dotted arrow,
The idler 43 is moved to the position indicated by the two-dot chain line using a suitable means, and the supply reel stand 45 is rotated in the direction of the dotted line arrow. As a result, the supply reel 32 fitted on the supply reel stand 45 is attached to the fed tape 3.
4 will be rolled up. The winding torque of the supply reel stand 45 in this case is such that, as can be seen from FIG. In order to maintain stable and sufficient contact with the reel (not shown), it is usually necessary to set the torque to be larger than the take-up reel stand 44 torque in the regeneration mode. This setting is also controlled by electrically switching the circuit.

The above explanation is an example of the multifunctionality of recent VTRs, which include not only normal recording and playback functions, but also fast forwarding,
Rewind playback, slow playback, reverse playback, static playback, etc. have already been performed. However, as explained above, there are conditions for winding the tape appropriately in each mode, so a drive system using a dedicated reel motor as shown in Figure 1 is required, and it must be switched using an electric circuit. There is also a need for control.

As mentioned above, this method requires an expensive motor to drive the reel, and has many problems in terms of cost and reliability, such as a complicated circuit, and has limitations such as being unable to be applied to low-priced products. .

Purpose of the invention The present invention solves the above-mentioned conventional problems, and provides a power transmission device that can change the torque of the take-up reel table with a simple mechanism without the need for a dedicated motor or complicated control circuit. The purpose is to provide.

Structure of the Invention In order to achieve the above object, the power transmission device of the present invention includes a pulley having a disc-shaped disc part and a cylindrical part above and below the disc part, which is rotatably attached to a spindle, and a friction member mounted above the disc part. A first clutch disk is provided on the cylindrical portion above the disk portion and has a gear portion on the outer periphery, and a compression spring is provided on the upper portion of the first clutch disk, and a thrust receiving plate that receives upward spring pressure is rotatably provided. an output pulley which also serves as a thrust receiving member is fixed to the cylindrical portion above the disk portion, and a first friction clutch is attached above the disk portion by pressing the first clutch disk to the friction member using the compression spring force. On the other hand, a second clutch disk is provided on the lower side of the disk via a friction member, and is rotatable in the cylindrical portion of the lower side of the disk and has a gear portion on the outer periphery. A thrust receiving plate that receives spring pressure is rotatably provided, a thrust receiving member is fixed to the cylindrical portion below the disk, and the second clutch disk is crimped to the friction member by the force of the compression spring. Second
forming a friction clutch, the first and second
A switching gear formed with a gear portion that can simultaneously mesh with the outer peripheral gear portion of the clutch disk is disposed so as to be able to rotate and separate from the outer peripheral gear portion of the first and second clutch disks, and A driving gear is disposed that always meshes with the outer peripheral gear portion of the second clutch disk to transmit power, and when the switching gear is separated from the outer peripheral gear portion of the first and second clutch disks, the first or second clutch disk The friction torque set by the friction clutch is transmitted to the output pulley, and when the switching gear is in contact with the outer peripheral gear portions of the first and second clutch disks, the friction torque is transmitted by the first and second friction clutches. The configuration is such that a composite torque of each set torque is output.

DESCRIPTION OF EMBODIMENTS The drawings (second
This will be explained based on FIGS.

Reference numeral 1 denotes a chassis board, and a support shaft 2 is embedded in this chassis board 1. A pulley 4 is rotatably fitted onto the support shaft 2, and is held by a washer 14 and an E-ring 15 with an appropriate clearance in the thrust direction. The pulley 4 is provided with a disc-shaped disc part 4a, and a main felt 9 and a sub-felt 10 are attached as friction members above and below the disc part 4a. Reference numerals 8 and 11 denote a main disk gear and a sub-disk gear which are provided above and below the disk portion 4a so as to sandwich the main felt 9 and the sub-felt 10, and these gears are rotatably attached to the cylindrical portions above and below the disk portion 4a of the pulley 4. It is fitted onto the outside, and a gear is formed on its outer periphery. A compression spring 7 and a thrust receiving plate 6 are provided on the main disc gear 8, and an output pulley 5, which also serves as a receiving thrust force, is press-fitted and fixed to the pulley 4. Also, a compression spring 12 and a thrust receiving plate 26 are provided under the sub-disk gear 11 in a similar manner, and a thrust stopper 13 is press-fitted and fixed to the pulley 4.

With the above configuration, the main disc gear 8 and the sub disc gear 11 have upper and lower compression springs 7 and 12, respectively.
The main felt 9 and sub felt 10 attached above and below the disc portion 4a of the pulley 4 are crimped by the friction coefficients μ _M , μ _S between each felt and each disc gear, the effective radii of each felt R _M , R _S , Friction torque determined by the upper and lower compression spring pressures P _M and P _S (T _M = μ _M × R _M × P _M , T _S = μ _M × R _S × P _S )
Friction clutches are formed on the upper and lower sides to transmit the Reference numeral 22 designates an intermediate pulley having a gear portion 22a that meshes with the outer peripheral gear portion of the main disc gear 8, and a V-groove portion 22b to which power is transmitted via a belt 23 from an appropriate drive source (for example, the capstan motor in FIG. 1). have. The support shaft 3 is an intermediate pulley 22
The gear part 22a of the main disc gear 8 and the gear part of the main disc gear 8 are implanted on the chassis base plate 1 with an appropriate distance between the pitches so that they always mesh smoothly.
The intermediate pulley 22 is rotatably fitted onto the support shaft 3,
It is held by a washer 24 and an E-ring 25 with an appropriate clearance in the thrust direction. The switching gear 19 is rotatably held by a support shaft 20 implanted on the switching lever 21 with an appropriate vertical thrust, and is connected to the outer peripheral gears of the main disc gear 8 and the sub disc gear 11. It has a gear part 9a that can mesh with both parts at the same time. Further, the switching lever 21 is configured so that the switching gear 19 can freely come into contact with and separate from the gear portions of the main disc gear 8 and sub disc gear 11. Reference numeral 16 denotes an idler, to which a rubber ring 16a is fitted, and is rotatably held by a support shaft 17 implanted in an idler arm 18 with an appropriate thrust. This idler 16 is similar to the idler 43 in FIG. The idler arm 18 is configured so that the idler 16 can be pressed onto and removed from the output pulley 5 and the supply reel stand 27 or the take-up reel stand 28 by suitable means.

Next, to explain the operation, in the state shown in FIG. 2, the driving force transmitted from the drive source (such as the capstan motor in FIG. 1) through the belt 23 is transferred to the main disc gear that meshes with the gear portion 22a of the intermediate pulley 22. Rotate 8. Since the main felt 9 is interposed between the main disc gear 8 and the disc portion 4a of the pulley 4 to form a friction clutch, the output pulley 5 fixed to the pulley 4 has T _M =μ _M A main clutch torque of ×R _M ×P _M is output, and the take-up reel stand 28 is driven with a constant torque via the idler 16. This is the regeneration mode, and the torque of the take-up reel stand 28 can be freely determined by arbitrarily setting the friction coefficient μ _M , the effective radius R _M of the main felt 9, and the pressing force _PM of the compression spring 7.

When switching to another mode to increase the winding torque, as shown in FIG.
It also comes to a position where it meshes with the gear part. In this state, the driving force transmitted to the main disc gear 8 is transferred to the sub disc gear 11 via the switching gear 19.
The main clutch torque T _M and the sub-clutch torque (T _S = μ _S ×
R _S ×P _S ) is output, and the take-up reel stand 28 or the supply reel stand 27 is driven with a constant torque via the idler 16. As described above, this torque can also be freely determined by arbitrarily setting the effective radius R _S of the friction coefficient μ _S of the sub-felt 10 and the pressing force P _S of the compression spring 12.

As explained above, in this embodiment, it is possible to switch the output torque in two stages by connecting and separating the switching gear 19. Also, disk gear,
By providing a plurality of switching gears, it is possible to easily switch the output torque to multiple stages.

Effects of the invention As described above, according to the invention, a drive system that transmits winding torque appropriate for multi-function mode can be created without using a dedicated reel motor for tape winding drive or a complicated torque switching control circuit. can provide,
This can reduce costs and significantly improve reliability.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan view of the tape running system of a conventional VHS VTR, Figs. 2 to 4 show an embodiment of the present invention, Fig. 2 is a longitudinal sectional view, and Fig. 3 is a switching gear section. FIG. 4 is a schematic plan view of the main parts. 1... Chassis board, 2, 3... Support shaft, 4...
Pulley, 4a... Disc part, 5... Output pulley, 6... Thrust receiving plate, 7... Compression spring, 8
...Main disc gear, 9...Main felt, 10...Sub felt, 11...Sub disc gear, 12...Compression spring, 13...Thrust stopper, 16...Idler, 16a...Rubber ring, 17 ... Support shaft, 18 ... Idler arm,
19...Switching gear, 19a...Gear portion, 20...
Support shaft, 21...Switching lever, 22...Intermediate pulley, 22a...Gear portion, 22b...V groove portion, 23
...Belt, 26...Thrust receiving plate, 27...
Supply reel stand, 28...take-up reel stand.

Claims (1)

[Scope of utility model registration request] A pulley having a disc-shaped disc part and a cylindrical part above and below the disc part is rotatably attached to a support shaft, and a gear is rotatably attached to the cylindrical part above the disc part via a friction member on the upper side of the disc part, and a gear is attached to the outer periphery of the disc part. A compression spring is provided on the upper part of the first clutch disk, and a thrust receiving plate which receives upward spring pressure is rotatably provided, and an output pulley which also serves as a thrust receiving member is provided on the cylindrical part above the disk part. is fixed, and the first clutch disk is pressed against the friction member by the compression spring force, thereby forming a first friction clutch on the upper side of the disk portion, and on the other hand, a first friction clutch is formed on the lower side of the disk via the friction member. A second clutch disk is provided in the cylindrical portion on the side and is rotatable and has a gear portion on the outer periphery, a compression spring is provided at the lower part of the second clutch disk, and a thrust receiving plate which receives downward spring pressure is provided in a freely rotatable manner, A thrust receiving member is fixed to the cylindrical portion of the cylindrical portion, and a second clutch disk is crimped to the friction member by a compression spring force to form a second friction clutch below the disk, and the first and second clutch disks are connected to each other. A switching gear formed with a gear portion that can simultaneously mesh with the outer peripheral gear portion of the clutch disk is disposed so as to be able to be freely connected to and separated from the outer peripheral gear portion of the first and second clutch disks, and A driving gear is disposed that always meshes with the outer gear portion of the clutch disk to transmit power, and when the switching gear is separated from the outer gear portion of the first and second clutch disks, the first or second friction clutch is disposed. The friction torque set by the friction torque is transmitted to the output pulley, and when the switching gear is in contact with the outer gear portions of the first and second clutch disks, the friction torque is set by the first and second friction clutches. A power transmission device configured to output a composite torque of each torque.