JPS61274975A - Clutch mechanism - Google Patents

Abstract

PURPOSE:To certainly transmit the rotation of a rotor to one direction to a drive shaft and to make it possible to certainly block the rotation of said rotor to the other direction, by providing a second spring clutch to a clutch mechanism along with a first spring clutch. CONSTITUTION:When a both-direction rotor 14 rotates to one direction, a first spring clutch 29 is clamped by the rotation of said rotor to transmit said rotation to a unidirectional rotor 28 and the drive shaft 25 rotating in integral relation to said rotor 28 is driven. At this time, a second spring clutch 24 temporarily stops the rotation of the drive shaft at a moment at first and performs the action of fastening the clamp of the first spring clutch 29. Contrarily, when the both-direction rotor rotates to the other direction, the first spring clutch 29 is loosened and the rotation thereof is not transmitted to the rotor 28 to prevent the rotation of the drive shaft 25. At this time, the second spring clutch 24 clamps the drive shaft 25 to perfectly stop the rotation thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a one-way clutch mechanism that transmits rotation in one direction of a rotating body rotating in both directions to a drive shaft and rotates the drive shaft in only one direction. It can be applied to ribbon feeding mechanisms in printing devices such as printers and typewriters.

Traditionally, for example, in the ribbon feeding mechanism of a printer, a cylindrical core (2) is erected on a carriage (1), and a compression spring (3) is inserted into the cylindrical core (2), as shown in Fig. 5. Insert the rear drive shaft (4) and
The central angle axis (5) was projected upward. On the other hand, a pulley (6) is attached to the outer periphery of the cylindrical core (2), and is rotatable on the carriage (1) about the cylindrical core (2). Moreover, a rotating body (7) is further attached on the pulley (6).

The aforementioned square shaft (5) was inserted through the central square hole of the rotating body (7), and was rotatable together with the drive shaft (4) about the cylindrical core (2). and.

A coil-shaped spring clutch (8) was attached to the outer periphery of the rotating body (7), and the lower end (8a) was fitted into the engagement hole (6a) of the pulley (6).

By the way, although one of the pulleys (6) is not shown, a belt for driving the carriage meshes with the pulley (6). and.

When the carriage (1) is moved in the printing direction, the movement is transmitted to the pulley (6) via the belt, and the pulley (6)
) to rotate. The rotation of the pulley (6) tightens the spring clutch (8), transmits the rotation to the rotating body (7), and turns the square shaft (5). Then, drive the winding member of the ribbon cassette installed on the cassette stand (9),
It winds up the ribbon. However, when one line of printing is completed and the carriage (1) is cleared, the movement is transmitted to the pulley (6) via the belt, causing the pulley (6) to rotate in the opposite direction. Rotation of the pulley (6) in the other direction loosens the spring clutch (8), causing slippage between the clutch and the rotating body (7), and the rotation is not transmitted to the rotating body (7). , the structure was such that the ribbon was not fed.

However, in such a conventional structure, the pulley (6
) rotates until the spring clutch (8) is tightened, so there is a drawback that even if the pulley (6) rotates, the rotation cannot be immediately transmitted to the square shaft (5). Similarly, since there is a time delay between the pulley (6) rotating in the other direction and the spring clutch (8) loosening, there is a drawback that it is not possible to immediately interrupt the rotational follow-up of the rotating body (7). Furthermore, when the pulley (6) rotates in the other direction, the spring clutch (8) and the rotating body (7) come into contact, and rotation transmission between them cannot be completely interrupted. There was a problem that the ribbon rotated little by little and the ribbon was rewound. For this reason, there are disadvantages in that ribbon feed jams occur and paper becomes smudged.

Therefore, an object of the present invention is to transmit the rotation in one direction of a rotating body that rotates in both directions to a drive shaft.

A one-way clutch mechanism that rotates the drive shaft in only one direction ensures that the clutch function can be performed reliably, and that the rotation of the rotating body in one direction is reliably transmitted to the drive shaft, and the rotation in the other direction is ensured. The purpose is to be able to reliably block rotation.

1-11 Therefore, the clutch mechanism according to the present invention includes a bidirectional rotating body such as a ribbon drive pulley (14) that rotates in both directions, and a coil-shaped first spring clutch (29) that is attached at one end to the rotating body. , a one-way rotating body (28) having a cylindrical outer surface (28a) around which the other end of the spring clutch is wound, and rotating in one direction coaxially with the rotating body;
and a drive shaft (25) that rotates integrally with the one-way rotating body at its rotation center.

One end is wrapped around the cylindrical outer surface of the drive shaft, and the other end (
24a) is characterized in that it is provided with a coil-shaped second spring clutch (24) whose side is fixed.

And when a bidirectional rotating body rotates in one direction,
The rotation tightens the first spring clutch (29) and transfers the rotation to the one-way rotating body (28) through the clutch.
A drive shaft (25) that transmits information to and rotates together with it.
*Drive. At this time, the second spring clutch (24
) serves to temporarily stop the rotation of the drive shaft (25) and hasten the tightening of the first spring clutch (29). On the other hand, when the two-way rotating body rotates in the other direction, the first spring clutch (29) is loosened to prevent the rotation from occurring between the clutch and the one-way rotating body (28). (28) and does not rotate the drive shaft (25). At this time,
The second spring clutch (24) is connected to the drive shaft (25).
) to completely stop its rotation.

By the way, FIGS. 1 to 4 show an embodiment in which the clutch mechanism according to the present invention is applied to a ribbon feeding mechanism of a printer. The printer shown in this embodiment uses the movement of a carriage to feed the ribbon, as shown in FIG. In other words, the symbol (10) in Figure 1 is the platen,
As is well known, the hook is rotatably extended between the left and right side plates (not shown) of the printer. A guide shaft (11) is disposed in front of the platen (10) and parallel to it, and similarly extends between the left and right side plates.The guide shaft (11) supports the carriage (12) and supports the carriage (12). 12) along the platen (10). The carriage (12) carries a print head (13), and as the carriage (12) moves, the platen (10)
The carriage (1
2) also includes a clutch mechanism (A) according to the present invention.

The ribbon driving pulley (14) of the clutch mechanism (A) is provided with a timing belt (15) having unevenness on both sides.
) to engage the unevenness on one side. The belt (15) is pushed by another pulley (16) mounted on the carriage (12),
It is devised to increase the amount of engagement with the ribbon drive pulley (14). The timing belt (15) is connected to the left and right drive pulleys (17) and the driven pulley (
18) Pass the hook between them, and attach each end to the carriage (12
). Thus, the rotation of the stepping motor (21) in both directions is transmitted to the drive pulley (17) through the engagement of the gears (19) and (20).

Now, the clutch mechanism (A) is constructed as shown in FIGS. 1 and 2. That is, a circular recess (12a) is formed in the carriage (12), and the lower part of the metal cylindrical core (23) is press-fitted into the recess (12a) and erected.

Then, a coiled second spring clutch (24) is wound around the cylindrical core (23) and the drive shaft (25
), and the lower end (24a) of the clutch is inserted into the locking hole (12b) made in the carriage (12) and fixed.

The drive shaft (25) is the second spring clutch (24)
A square shaft (27) is coaxially embedded in a cylindrical resin (26) with a flange around which the clutch (24) is wrapped, and the upper part of the clutch (24) hits the flange (26a), causing the drive shaft (25) to move elastically in the axial direction. support. Then, the upper part of the square shaft (27) projects upward. On the other hand, the aforementioned ribbon drive pulley (14) is attached to the outer periphery of the first cylindrical core (23),
The carriage (12) is centered around its cylindrical core (23).
It can be rotated freely at the top. At the same time, a one-way rotating body (28) is further attached to the pulley (14), and the aforementioned square shaft (27) is inserted into the central square hole of the rotating body (28) as in the past.
The drive shaft (25) and the drive shaft (25) can be rotated together around the cylindrical core (23). and,
On the cylindrical outer surface (28a) of the one-way rotating body (28).

A coil-shaped first spring clutch (29) is also attached here as well as in the conventional case. The clutch (29) is wound in the same direction as the second spring clutch (24), and has a lower end (
29a) into the engagement hole (14a) of the pulley (work 4). A cassette mounting table (30) is mounted on the carriage (12), and the structure is such that only the square shaft (27) projects upward from the mounting table. The mounting table (30)
On the top, there is a ribbon cassette (31) tr shown in FIG.
Attach. As shown in the figure, the ribbon cassette (31) stores, for example, a ribbon (33) wound around a feeding core (32), and then the ribbon is pulled out and tensioned between the feeding opening (34) and the drawing opening (35). After passing it, it is passed between the first winding member (36) and the pressure contact member (37) and wound around the winding core (38).

As described above, when the ribbon cassette (31) is mounted on the mounting table (30), the winding member (36)
) is connected to the tip of the square shaft (27), and the square shaft (27) is connected to the square shaft (27).
7) was transmitted to the winding member (36) so that the ribbon (33) could be wound up.

Therefore, in order to print now, the stepping motor (21
), the timing belt (15) is moved in the direction of the arrow in FIG. 3, and the carriage (12) is moved to the right in the same figure. Based on the movement of the belt (15), the ribbon of the clutch mechanism (A) Turn the drive pulley (L4),
The pulley is rotated in the direction of the arrow in FIG. Then, the first
The spring clutch (29) is tightened, and its rotation is transmitted to the one-way rotating body (28), which rotates the square shaft (27) to feed the ribbon.Therefore, the carriage (12) is moved and the ribbon is fed. While printing the print head (13)
Then, when the printing of - lines is completed, the stepping motor (21) is reversely driven, and the timing belt (15) is driven in the reverse direction. If the carriage (12) is moved in the direction opposite to the direction indicated by the arrow in Figure 3, the carriage (12) will move to the left in the figure. At this time, the ribbon drive pulley (14) of the clutch mechanism (A) is rotated counterclockwise in the figure based on the movement of the timing belt (15). Then, the first spring clutch (29) loosens, causing a slip between the clutch (29) and the one-way rotating body (28), and the rotation of the pulley (14) is caused by the one-way rotating body (28).
28) and does not rotate the drive shaft (27). Therefore, the carriage (12
) can be returned to the original printing start position.

In this case, when the pulley (14) rotates, the one-way rotating body (28) first follows and rotates, causing the square shaft (27) to rotate slightly, but this rotation causes the second spring clutch (24) to tighten. The rotation of the square shaft (27) will soon be completely stopped. Also, when the carriage (12) is moved to the right in Fig. 3 in order to return to the original printing start position and start printing again, the second spring clutch (24) first engages the square shaft (24) ) is prevented from rotating, the first spring clutch (29) can be tightened quickly, and the pulley (14) is immediately rotated to the one-way rotating body (28).
) can be transmitted.

Therefore, according to the present invention, only the rotation in one direction of a rotating body that rotates in both directions, such as the above-mentioned ribbon drive pulley, is transmitted to the drive shaft, and the rotation of the rotating body, such as the above-mentioned ribbon drive pulley, is transmitted to the drive shaft. For example, in a clutch mechanism that uses carriage movement to feed the ribbon, the conventional first
By providing a second spring clutch together with the spring clutch, the clutch function can be performed reliably, and the rotation of the two rotating bodies in one direction can be reliably transmitted to the drive shaft, while the rotation in the other direction can be reliably blocked. You can try to get it. Moreover, if the second spring clutch is made using a conventional compression spring, the above effects can be achieved without increasing the number of parts compared to the conventional one.

[Brief explanation of drawings]

1 to 4 show an embodiment in which the clutch mechanism according to the present invention is applied to a ribbon feeding mechanism of a printer, and a first embodiment of the clutch mechanism according to the present invention is shown.
The figure is a longitudinal sectional view of the clutch mechanism. FIG. 2 is an exploded perspective view thereof, FIG. 3 is a schematic diagram of the ribbon feeding mechanism, and FIG. 4 is a plan view showing the ribbon cassette used in the printer with the top cover removed. FIG. 5 is a longitudinal sectional view of a similar conventional latch mechanism.

Claims (1)

[Scope of Claims] 1. A bidirectional rotating body that rotates in both directions, a coil-shaped first spring clutch having one end attached to the rotating body, and a cylindrical outer surface around which the other end of the spring clutch is wound; A unidirectional rotating body that rotates in one direction coaxially with the rotating body, a drive shaft that rotates together with the unidirectional rotating body at the center of rotation, one end wrapped around the cylindrical outer surface of the drive shaft, and the other end wrapped around the cylindrical outer surface of the drive shaft. A clutch mechanism comprising: a fixed coil-shaped second spring clutch; 2. The clutch mechanism according to claim 1, wherein the second spring clutch also serves as a compression spring that biases the drive shaft in the axial direction. 3. The above-mentioned patent is applied to a ribbon feeding mechanism of a printer, transmits rotation to a bidirectional rotary body using a bending media member for driving a carriage such as a belt, and winds up a ribbon by rotating a drive shaft in one direction. A clutch mechanism according to claim 1. 4. The clutch mechanism according to claim 3, wherein the drive shaft is provided with a square shaft portion, and the square shaft portion is engaged with a ribbon winding member to rotate the member and feed the ribbon.