JPH0524839Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is based on a gear transmission that allows, for example, a drive gear that reciprocates the carriage of a print head to rotate in forward and reverse directions, but that allows the ink ribbon to always be fed in a fixed direction. It is about the mechanism.

(Prior Art) For example, in a printer, the print head carriage is moved back and forth left and right by the reversal of the forward and reverse rotation of its drive gear, but the ink ribbon is always moved by the same drive source. Must be sent in the same direction.

Therefore, conventionally, one end of a switching lever is rotatably attached to the shaft of a motor for driving the ink ribbon feed of a printer, and a moving gear is rotatably supported at the other end of the lever, and the rotation direction of the driving gear is The switching lever is oscillated in accordance with the reversal of the ink ribbon, thereby causing the moving gear to select and mesh with either the driven gear for rotating the ink ribbon or the idler that rotates the driven gear. The driven gear was always rotated in a fixed direction.

(Problem to be solved by the invention) However, in the conventional ink ribbon feed gear mechanism, the switching lever is simply rotatably supported on the shaft of the drive gear, so the rotation direction of the drive gear cannot be adjusted. The swinging operation of the switching lever following the reverse reversal relies on the frictional force generated by the surface contact between the switching lever and the shaft of the drive gear, so although the operation is not necessarily reliable, Nakatsuta.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a gear transmission mechanism in which a switching lever reliably follows the forward and reverse rotation of a drive gear and swings.

(Means for Solving the Problems) The features of the present invention include a drive gear that is rotatably supported on a support plate and rotates in forward and reverse directions, a switching lever attached to the drive gear, and a switching lever attached to the switching lever. It is composed of a movable gear that is rotatably supported and always meshes with the drive gear, and a driven gear that is rotationally driven when the movable gear disengages from the mesh, and the shaft support of the switching lever is concentric with the drive gear. An elastic arm extending from the shaft support is frictionally connected to the drive gear and follows the drive gear in the rotational direction about the center of rotation of the drive gear. The driven gear is driven to rotate in a fixed direction by the movement of the moving gear caused by the displacement of the switching lever, which causes the moving gear to engage and disengage directly or indirectly through an idler. It is in the place where it is done.

(Function) When the drive gear rotates while reversing forward and reverse, the elastic arm of the switching lever is frictionally connected to the drive gear, so it reliably swings to follow the reversal movement of the drive gear. The movable gear pivotally supported by the switching lever can rotate the driven gear in a fixed direction by selecting either the driven gear or an idler that rotates the driven gear.

(Example) Next, an example in which the present invention is applied to an ink ribbon feed gear mechanism will be described.

As shown in Fig. 1, three support plates 1, 2, and 3, upper, middle, and lower, are arranged at predetermined intervals, and a reversible motor M is installed on the upper surface of this middle plate. In addition, the upper and lower plates are integrally formed with a shaft support means to be described later, and this shaft support means supports a carriage (not shown) to which a ribbon feed gear wheel train and a printer head are attached. ) is rotatably supported by a drive wheel train of a timing belt 6 that reciprocates left and right.

First, the drive wheel train of the timing belt 6 will be explained. The motor pinion 4 fixed to the drive shaft of the reversible motor M meshes with the belt pulley 5 as shown in the second figure. A timing belt 6, to which a carriage (not shown) for conveying the printer head is attached, is wound around the belt pulley 5.

Therefore, printing is performed while the printer head is moved back and forth via the belt 6 by driving the motor M in forward and reverse rotation.

Next, the feed gear mechanism for the ribbon 18 has the following configuration.

As shown in FIG. 2, an idler 8 meshes with the reduction gear 7 meshing with the belt pulley 5, and this idler 8 meshes with a drive gear 9.

The upper end surface of the drive gear 9 has a recess 9a (FIG. 1).
is formed, and the cylindrical shaft 9b of this drive gear
A shaft hole 10a formed in the shaft support of the switching lever 10 is rotatably fitted into the shaft hole 10a. Therefore, the switching lever 10 is pivotally supported by the drive gear 9 so as to be able to swing freely.

The switching lever 10 is integrally formed with two elastic arms 10b, 10b extending from its shaft support, and a sphere 1 is attached to the tip of the elastic arm.
0c and 10c are formed. The elastic arms 10b, 10b are inserted into the recess 9a of the drive gear 9, and the switching lever is connected to the elastic arms 10b, 10b.
It is frictionally joined to the inner surface of this recess of this drive gear via the spheres 10c, 10c of 0b.

Furthermore, a moving gear 1 is provided at both ends of the switching lever 10.
1 and 12 are rotatably supported, and this moving gear always meshes with the drive gear 9.

One of the moving gears 11 is a switching lever 10.
By swinging clockwise around the axis of the drive gear 9, the driven gear 13 meshes with the driven gear 13, causing the driven gear to rotate directly in conjunction with the other moving gear 1.
2 meshes with the idler 14 by counterclockwise rocking of the switching lever 10, and since this idler is always meshed with the driven gear 13, this driven gear is indirectly rotated in conjunction with it.

Of course, if one idler is interposed between the moving gear 11 and the driven gear 13, the same effect can be achieved by providing two idlers between the moving gear 12 and the driven gear 13. can be done,
This kind of thing is easy in terms of design,
Whether the interlock between the moving gear and the driven gear is direct or indirect,
The meaning includes all such design matters.

Furthermore, the driven gear 13 meshes with a ribbon drive wheel 15, and the upper end of this ribbon drive wheel becomes an engagement shaft 15a that fits into the shaft hole 16a of the ribbon drive roller 16 for feeding the ribbon 18 in the ribbon cassette 17. ing.

As shown in FIGS. 1 and 3, the shaft support means for the belt drive wheel train and the ribbon feed gear mechanism include a shaft bearing hole 30 in which the belt wheel 5 is rotatably supported in the lower plate 3; a shaft 31 that supports the shafts of the reduction gears 7 and 8;
31, a bearing shaft 33 for the shaft of the drive gear 9, two groove-shaped guide grooves 34, 3 along the outer periphery of this drive gear;
5. The shaft 37 passing through the shaft support hole 36 of the idler 14, the shaft hole of the driven gear 13, and the ribbon drive wheel 1
Shafts 38 that are inserted into the shaft holes of 5 and supported are integrally formed. Furthermore, bearing columns 1a, 1b, and 1c for bearing the driving gear 9, idler 14, and driven gear 15 are integrally formed on the upper plate 1.

Next, the operation of this embodiment will be explained.

The timing belt 6 is rotated by the rotational drive of the motor M via the motor pinion 4 and the belt pulley 5. At this time, since the motor changes the rotation direction between forward and reverse, the rotation direction of this belt also changes, and the printer The head moves back and forth to print.

At the same time, the ribbon is sent out in a fixed direction as follows.

In FIG. 2, when the motor pinion 4 rotates clockwise, the belt pulley 5, reduction gear 7, and idler 8
The drive gear 9 rotates counterclockwise via. Therefore, since the switching lever 10 follows and displaces the moving gears 11 and 12 in the counterclockwise direction centering on the axis of the driving gear 9, the moving gears 11 and 12 move toward the guide groove 34,
35, one moving gear 12 meshes with the idler 14, causing the driven gear 13 to rotate clockwise and the ribbon drive wheel 15 to rotate counterclockwise. At this time, the other moving gear 11 is the driven gear 13
(state shown in Figure 2).

Further, when the motor pinion 4 rotates counterclockwise, the drive gear 9 rotates clockwise. Therefore, the switching lever 10 is moved by the rotational force of the drive gear 9.
From the state shown in FIG.
2 moves in the guide grooves 34 and 35, one moving gear 11 meshes with the driven gear 13 and rotates the driven gear clockwise, and at the same time the other moving gear 12 disengages from the idler 14. . In this way, the moving gear 11 is always rotated clockwise, and the ribbon drive wheel 15 is also always rotated counterclockwise.

Note that the present invention uses two moving gears in the above embodiments.
However, it is also possible to provide one moving gear so that the ribbon is fed in the forward direction only when the drive gear rotates in either the forward or reverse direction. .

(Effects of the invention) As described above, according to the invention, not only is the shaft support of the switching lever swingably supported on the drive gear, but also the elastic arm of the switching lever is frictionally supported on the drive gear. Since they are connected, the rotating motion of the drive gear in both forward and reverse directions can always be followed reliably, and the driven gear can always be rotated in a fixed direction.

[Brief explanation of the drawing]

FIG. 1 is a vertically developed sectional view, FIG. 2 is a plan view of the gear mechanism, and FIG. 3 is a plan view of the lower plate. 1, 2, 3 ... support plate, 9 ... driving gear, 9b
...... shaft, 10... switching lever, 10a... shaft hole,
10b: elastic arm; 11, 12: moving gears; 13: driven gear; 34, 35: guide groove.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A support plate, a drive gear that is rotatably supported by the support plate and rotates in forward and reverse directions, a switching lever attached to the drive gear, and a switching lever that is rotatable on the switching lever. The switching lever is comprised of a moving gear supported by the drive gear, which is always in mesh with the drive gear, and a driven gear, which is rotationally driven when the drive gear disengages from the drive gear. The elastic arm extending from the shaft support is frictionally connected to the drive gear, so that the switching lever is rotated in the direction of rotation of the drive gear around the center of rotation of the drive gear. The driven gear follows the movement of the moving gear due to the displacement of the switching lever, and the moving gear engages and disengages directly or indirectly through an idler and rotates in a fixed direction. A gear transmission mechanism characterized by being driven. 2. The gear transmission mechanism according to claim 1 of the utility model registration, characterized in that two moving gears are provided on the switching lever. 3. Claims for Utility Model Registration Paragraph 1 states that the shaft of the movable gear is slidably inserted into a guide groove formed along the drive gear in a support plate surrounding the drive gear. A gear transmission mechanism featuring: