JP2001113778A - Clutch mechanism of printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism which facilitates adjusting a ribbon tension in a thermal transfer printer. SOLUTION: The mechanism includes a shaft coupled to an ink ribbon, a knob coupled to the shaft, a clutch plate for generating a torque by friction to the knob, a spring for applying a pressing force to the clutch plate, and a pressing member coupled to the knob for adjusting the pressing force of the spring. A compression amount of the spring is changed over along an inclined grooved cam formed to the pressing member, whereby the pressing force applied to the clutch is adjusted. The torque generated by the clutch mechanism is thus adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch for generating a ribbon tension in a thermal transfer printer or the like using a line thermal head, and more particularly to a clutch mechanism having a torque adjusting mechanism.

[0002]

2. Description of the Related Art A conventional clutch mechanism is disclosed in
As shown in Japanese Patent Publication No. 7, a mechanism for adjusting a torque by rotating a pressing member with respect to a shaft is provided. As shown in FIG. 5, as a further improvement, a knob for adjusting the amount of compression is provided with these grooves on a continuous helical curved surface so that the amount of compression of the spring can be adjusted to improve operability. There is something that measures.

[0003]

In the conventional clutch mechanism, when adjusting the torque according to the ribbon width, the conventional clutch mechanism rotates while holding the ribbon with one hand and pressing the knob with the other hand. Therefore, an operation of selecting the groove and changing the compression amount of the spring was required. For this reason, it is necessary to use both hands for torque adjustment, and one hand has to directly press the ink ribbon with a hand, so that there is a problem that the hand is stained. In the knob shown in FIG. 5, when setting the ribbon, it is necessary to turn the knob to wind up the ribbon. At this time, if a torque exceeding a certain level is applied, the knob rotates with respect to the shaft and the groove rotates. And the torque setting changes. An object of the present invention is to provide a clutch mechanism that can easily adjust torque with one hand.

[0004]

In order to solve the above-mentioned problems, a shaft connected to an ink ribbon, a knob connected to the shaft, a clutch plate that generates friction and friction with the shaft, and a clutch plate And a pressure member coupled to the knob to adjust the pressing force of the spring.

[0005]

By pressing and sliding the pressing member, the compression amount of the spring is switched along the inclined groove cam provided on the pressing member, and the pressing force applied to the clutch is adjusted. The torque generated by the clutch mechanism is adjusted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The ink ribbon 13 is shown in FIG. As shown in FIG. 4, a projection provided on the bobbin 9 inserted into the ribbon holder 11 and a hole (not shown) provided on the ribbon holder 11a are coupled so as to transmit power, and the shaft 11b is connected. It is held by being fitted into the bearing 12. After the paper tube is similarly inserted into the ribbon holder on the winding side 14, the ribbon holder 11 is fitted into the bobbin 9 and the bearing 12 and attached. FIG. 2 is a partial perspective view showing one embodiment of the present invention, showing a state where a ribbon is mounted.

FIG. 1 is an exploded perspective view showing one embodiment of the present invention on the ribbon winding side. A pin serving as a stopper is attached to the shaft 8 at substantially the center, and both ends are D-shaped.
The bobbin 9 and the knob 5 are configured to be cut and rotate integrally with the shaft 8. Gear 7 on shaft 8
Is rotatably mounted, and power for winding the ribbon is transmitted to the gear 7 from power transmission means (not shown).
This power is transmitted to the knob 5 via the clutch plate 6, and the torque is transmitted to the bobbin 9 by the shaft 8. The clutch plate 6 transmits the torque given by the gear 7 to the knob 5 within the range of the friction torque. This friction torque is generated by the pressing force of the spring 4. The pressing member 2 and the plate 3 are connected by a parallel pin 1 with a degree of freedom remaining using a hole 8a provided in the shaft 8, and generate a pressing force on the spring 4 as a stopper of the spring 4. By pressing and sliding on the pressing member 2,
A stepped grooved cam 2a that can adjust the distance between the parallel pin 1 and the plate 3 is provided. Thus, when the pressing member 2 is slid in the direction perpendicular to the parallel pin 1, the amount of compression of the spring 4 changes, and the pressing force generated by the spring 4 can be adjusted. Thereby, the ribbon winding torque can be adjusted.

The groove cam 2a is 1 inch, 2 inch, so that a winding torque corresponding to the ribbon width is transmitted in advance.
Four stages for h, 3 inch and 4 inch are provided, and the transmission torque of the clutch can be switched. The pressing member 2 is engraved with numbers 2b from 1 to 4 above the groove cam 2a, and these are set to numbers corresponding to the ribbon width. Here, the engraved number may be provided on the knob 5 side. The side surface 2c in the sliding direction of the pressing member 2 has an R shape, and prevents the pressing member 2 from rotating around the parallel pin 1 when the pressing member 2 is slid while being pressed.

[0009]

According to the mechanism of the present invention, the torque can be adjusted only by pushing the knob-shaped pressing member, the operation can be performed with one hand, and the hand is stained as in the conventional mechanism. Not even. Further, since the knob does not double as the pressing member, there is no danger that the torque setting will change even if the knob is turned when winding the ribbon. Since a number corresponding to the ribbon width is stamped on the pressing member, a transmission torque suitable for the ribbon width can be easily selected. In the present embodiment, only the take-up side clutch has been described. However, if the supply side clutch is similarly configured and the gear 7 is fixed, back tension to the ribbon can be added.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of the present invention.

FIG. 2 is an external view of the present invention.

FIG. 3 is an external view of the present invention.

FIG. 4 is a diagram for explaining mounting of an ink ribbon.

FIG. 5 is a perspective view showing a conventional clutch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Parallel pin 2 Pressing member 3 Plate 4 Spring 5 Knob 6 Clutch plate 7 Gear 8 Shaft 9 Bobbin 11 Ribbon holder 12 Bearing

Claims (3)

[Claims] A shaft that transmits torque, a first clutch plate rotatably provided on the shaft, and a second clutch plate that rotates in connection with the shaft and transmits torque to the shaft by friction. A pressure member provided with a groove cam for adjusting a compression amount of the spring by sliding in one direction, and a groove cam of the pressure member. And a locking member that is engaged with the shaft and that is attached to the shaft. 2. A clutch mechanism for a printer according to claim 1, wherein a numerical mark is provided on said pressing member, and said mark matches a position of said groove cam with a ribbon width to be used. 3. A side surface of the pressing member in a sliding direction is R.
2. The clutch mechanism for a printer according to claim 1, wherein the clutch mechanism has a shape.