JPS62132057A - Power transmission mechanism - Google Patents

Abstract

PURPOSE:To promote compactness, by rotatably supporting a two-forked turning arm to the main shaft of a driving gear and providing a pendulum gear, directly meshing with an output gear, while a pendulum gear, indirectly meshing with the output gear, in the respective branches of the arm. CONSTITUTION:A turning arm 21 is rotatably supported to a main shaft 20 of a driving gear 18, having two-forked branches 21a, 21b. The arm 21 rotatably supports a pendulum gear 33 to the branch 21b through a shaft 32 while a pendulum gear 30 to the branch 21a through a shaft 29. The pendulum gear 33 can be directly meshed with an output gear 19, while the pendulum gear 30 can be meshed with the output gear 19 through an intermediate gear 31. Accordingly, compactness can be promoted by enabling a distance between shafts of the driving and output gears to be decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power transmission mechanism, and more specifically, to a power transmission mechanism that uses a gear train to extract power from forward and reverse rotation of a drive gear as a unidirectional rotational output. It is related to the transmission mechanism.

[Prior Art] For example, in various printers, a carriage that moves along a platen is provided with a mechanism for winding up an ink ribbon.

Some of these winding mechanisms use a power transmission mechanism that meshes a drive gear provided on the carriage with a rack gear provided on the frame side of the device and transmits this rotational force to the ink ribbon feed roller. There is.

If the printer is of a type in which recording is performed entirely during the reciprocating movement of the carriage, the ink ribbon must be wound in the same direction during all the reciprocating movements of the carriage.

However, in the structure described above, the direction of rotation of the drive gear is reversed between forward and backward movements of the carriage.

Therefore, a mechanism is required that allows the ink ribbon to travel in a single direction regardless of which direction the drive gear is rotated.

An example of such a power transmission mechanism is shown in FIGS. 4 to 7.

4 to 7 show examples in which the present invention is applied to an ink ribbon feeding mechanism provided in a carriage of a printer.

In FIG. 4, the reference numeral 1 indicates a recording head, which is provided on the carriage 2. In FIG.

The carriage 2 is reciprocated along a guide shaft 3 and is attached to an endless timing belt 5 that is run by a motor 4.

A recording paper designated by reference numeral 6 is wound around a platen 7 arranged parallel to the guide shaft 3, and is pressed and fed by a pail roller 8 so as not to rise from the platen 7.

- On the other hand, a rack gear 10 is fixed to the frame side of the apparatus in parallel with the guide shaft 3, and a drive gear 9 is provided in an ink ribbon cassette 12 that is detachably attached to the carriage 2.
is meshing with the rack gear 10.

This drive gear 9 is rotated in both left and right directions as shown by arrows 11 as the carriage 2 moves back and forth.

Also, a feed roller 13 is provided in the ink ribbon cassette 12.
and a pinch roller 14 are provided, and the ink ribbon 16 is sandwiched between them and drawn in.

The feed roller 13 is always rotated clockwise as shown by arrow 15 and always feeds the ink ribbon 16 clockwise as shown by arrow 17.

A power transmission mechanism used in such an ink ribbon feeding mechanism is shown in FIGS. 5 to 7.

In FIGS. 5 to 7, the reference numeral 18 indicates a drive gear, which corresponds to the drive gear 9.

One end of a rotating arm 21 is rotatably supported on the support shaft 20 of the drive gear 18, and a pendulum gear 23 is rotatably supported on the pattern of the rotating arm 21 via a shaft 22.

On the other hand, as the rotating arm 21 rotates, the first and second idle gears 24 and 2 are moved to a position where the pendulum gear 23 can mesh with the rotating arm 21.
5 is rotatably supported.

The first idle gear 24 meshes with the output gear 19, and the second idle gear 25 meshes with the output gear 19 via an intermediate gear 26.

In addition, as shown in FIG. 7, the drive gear 18 and the rotating arm 2
1, and is supported by a retaining ring 27 so as not to fall off, and a spring 28 is elastically loaded between the rotating arm 21 and the casing of the ink ribbon cassette.

Next, the operation of the power transmission mechanism configured as above will be explained.

When the carriage 2 moves to the left in FIG. 4, the drive roller 18 is rotated counterclockwise as shown by arrow A, as shown in FIG.

Then, since the rotating arm 21 is pressed against the drive gear 18 by the spring 28, the rotating arm 21 is rotated counterclockwise in FIG.
The first idle gear 24 is rotated counterclockwise, and the output gear 19 is rotated clockwise.

The rotational direction of the gear train that transmits power at this time is indicated by arrow B-D.

The output gear 19 is integrated with the feed roller 13.

Note that, at this time, the intermediate gear 26 and the second idle gear 26 are idling.

On the other hand, when the carriage 2 is moved to the right in FIG. 4, the drive gear 18 is rotated clockwise as shown by arrow E in FIG.

Then, the rotating arm 21 is also rotated clockwise, the pendulum gear 23 separates from the first idle gear 24, meshes with the second idle gear 25, and rotates the output gear 19 in the direction of the arrow through the intermediate gear 26. Rotate to

The rotational direction of the drive transmission gear at this time is indicated by arrow F-H.

By providing the pendulum gear 23 as described above, the gear train for transmitting drive is switched, and the rotational direction of the output gear is unified.

[Problems to be Solved by the Invention] However, if the above-mentioned structure is adopted, a total of six gears are required including the drive gear and the output gear, which increases the installation space for these gears and reduces the size of the device. It is preventing the development of

In addition, the rotation range of the rotation arm 21 for moving the pendulum gear is between the axes of the drive gear and output gear, and the distance between the axes of the drive gear and output gear does not become small, which also contributes to miniaturization of the device. It is a hindrance.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, a bifurcated rotating arm is rotatably supported on the support shaft of the drive gear. First and second pendulum gears that mesh with the drive gear are rotatably supported on the branches of the movable arm, so that the first pendulum gear can directly mesh with the output gear, and the second pendulum gear is an intermediate gear. It was designed so that it could mesh with the output gear via.

[Function] When the above-described structure is adopted, the bifurcated rotating arm rotates in the same direction as the rotational direction of the drive gear according to the constraint point of the drive gear, and the first pendulum gear rotates in the output direction. The second pendulum gear is meshed directly with the gear, and the second pendulum gear is meshed with the output gear indirectly through the intermediate gear, so that the output gear can always rotate in a fixed direction.

Further, the number of intermediate gears can be reduced by one, the distance between the shafts of the drive gear and the output gear can be shortened, and the overall operating range can be reduced.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings. FIGS. 1 to 3 illustrate one embodiment of the present invention. In the figures, the same or corresponding parts as in FIG. 1 are denoted by the same reference numerals, and the explanation thereof will be omitted.

Figure 1 shows the state where it is mounted on the carriage side, and the second
The specific structure of the gear train is shown in FIG. 3 and FIG.

The rotating arm designated by the reference numeral 21 in each figure is connected to the drive gear 1.
The center is rotatably supported on the main shaft 20 of 8,
The branch 21a is divided into two branches.

21b.

A first pendulum gear 33 is rotatably supported on one branch 21b via a shaft 32, and meshes with the drive gear 18.

A second pendulum gear 30 is rotatably supported on the other branch 21a via a shaft 29, and a second pendulum gear 30 is rotatably supported on the other branch 21a.
It meshes with 8.

The first pendulum gear 33 can be rotated to a position where it can directly mesh with the output gear 19, and the second pendulum gear 30 is at a position where it can mesh with the output gear 19 via the intermediate gear 31.

Then, the feed roller 13 is fixed coaxially with the output gear 19.

Next, the operation of this embodiment configured as above will be explained.

First, when the carriage 2 moves to the left in FIG. 1, the drive gear 9 which also meshes with the rank gear 10 is rotated counterclockwise as shown in FIG. The second pendulum gear 30 is rotated counterclockwise by the frictional force between the second pendulum gear 30 and the intermediate gear 31,
The second pendulum gear 30 rotates in the direction of arrow B, the intermediate gear 31 rotates in the direction of arrow C, and the output gear 19 rotates in the direction of arrow C.

Accordingly, the feed roller 13 also rotates in the direction of the arrow, and the ink pump 16 is sent out in the direction of the arrow 17 as shown in FIG.

Note that at this time, the second pendulum gear 30 is rotated clockwise as shown by arrow B, so the pendulum gear 30 receives a force in the direction of meshing with the intermediate gear 31, causing the second pendulum gear 30 and the intermediate gear 30 to engage with each other. The rotational arm 21 remains in a fixed position without being disengaged from the gear 31.

During this time, the first pendulum gear 33 continues to idle.

On the other hand, when the carriage 2 moves to the right in FIG. 1, the drive gear 18 is rotated clockwise as shown by arrow E in FIG. 3.

Then, the rotating arm 21 is also rotated clockwise,
The first pendulum gear 33 also moves accordingly and meshes with the output gear 19 as shown in FIG.

As a result, the first pendulum gear 33 that meshes with the drive gear rotates in the direction of arrow F, and the output gear 19 rotates in the direction of arrow F.

That is, even if the rotational direction of the drive gear 18 is reversed, the rotational direction of the output gear 19 remains the same, and as a result, the ink ribbon is sent out in the same direction.

In this way, no matter which direction the drive gear rotates as the carriage moves, the output gear can always be rotated in the same direction, and the ink ribbon can be sent out in the same direction.

[Effect] As is clear from the above description, according to the present invention, a bifurcated rotary arm is rotatably supported on the main shaft of the drive gear, and each branch of the rotary arm is rotatably supported. The first pendulum gear that meshes directly with the output gear and the second pendulum gear that meshes with the output gear via an intermediate gear are rotatably supported. The distance between the shafts and the gear can be reduced, the number of gears can be omitted by one, and a power transmission mechanism with a simple structure and small size can be obtained.

[Brief explanation of drawings]

Figures 1 to 3 illustrate one embodiment of the present invention.
Fig. 1 is an explanatory diagram of the state mounted on a carriage, Figs. 2 and 3 are explanatory diagrams of the operation of the gear train, Figs. 4 to 7 are explanatory diagrams of the conventional structure, and Fig. 4 is a recording section. Figures 5 and 6 are diagrams explaining the operation of the gear train.
The figure is a longitudinal cross-sectional side view of the main part. 9.18... Drive gear 19... Output gear 21...
・Rotating arm 21a, 2lb...-branch 30...second
Pendulum gear 31 ... Intermediate gear 33 ... First pendulum gear Fig. 2

Claims (1)

[Claims] A drive gear that rotates in forward and reverse directions, a rotary arm that is rotatably supported on the same axis as the drive gear and has a bifurcated branch, and a rotary arm that is rotatably supported on one branch of the rotary arm. a first pendulum gear that is rotatably supported on the other branch of the rotating arm, meshes with the drive gear, and directly meshes with the output gear; a second gear which can mesh with the output gear via the
A power transmission mechanism characterized by comprising a pendulum gear.