JP2651295B2 - Ink ribbon switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ribbon switching device used for a color printer.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
0 is provided on the carrier 51 holding the ribbon cassette 52 so as to be displaceable by urging the ribbon plate 53 holding the ribbon cassette 52 in one direction orthogonal to the moving direction of the carrier 51. Rotating cam 54
A cam follower 55 attached to the ribbon plate 53 is brought into contact with the cam 54, and the cam 54 is rotated to displace the ribbon plate 53 together with the ribbon cassette 52.
No., published in Japanese Unexamined Patent Publication No.

[0003]

In the invention described in FIG. 5, the camshaft 57 holding the cam 54 receives the urging force of the ribbon plate 53 via the cam follower 55, and is easily bent. Also, the carrier 51 is a carrier shaft 5
Therefore, if the parallelism between the cam shaft 57 and the carrier shaft 56 is not maintained accurately, the relative position of the ribbon plate 53 with respect to the carrier 51 changes depending on the position of the carrier 51. Accordingly, the camshaft 57 must be made thicker, and it is difficult to adjust the parallelism between the carrier shaft 56 and the camshaft 57, which causes an increase in cost.

[0004]

According to the present invention, there is provided a carrier holding a print head and being reciprocally movable, and a carrier holding a ribbon cassette and being displaceable in a direction orthogonal to the moving direction of the carrier. And a rotating shaft connected to the driving unit and held with an axis parallel to the moving direction of the carrier, fixed to the rotating shaft in the rotating direction and slidable in the axial direction. A drive gear fitted into the carrier, a contact portion provided on the carrier and abutting on a thrust surface of the drive gear, and held on the carrier so as to be engaged with the drive gear and rotatable in a direction orthogonal to the rotation axis. And a power conversion mechanism for converting the rotational movement of the driven gear into an axial movement of the driven gear and transmitting the converted movement to the cassette mount.

[0005]

When the carrier moves, the driving gear is pushed by the contact portion of the carrier and moves along the rotation axis, so that the driven gear is always meshed with the driving gear. Thus, when the rotation shaft is rotated, the rotation is transmitted from the driving gear to the driven gear, and the rotational movement of the driven gear is converted by the power conversion mechanism and transmitted to the cassette mounting table, thereby switching the color of the ink ribbon. . Further, due to the backlash at the meshing portion between the driving gear and the driven gear, the pressure acting on the meshing portion between the driving gear and the driven gear can be reduced, and the bending of the rotating shaft can be prevented. Further, even if the parallelism of the rotation axis with respect to the moving direction of the carrier is incorrect, the fluctuation of the shift position of the cassette mounting base due to the change of the position of the carrier can be absorbed by the backlash of the meshing portion between the driving gear and the driven gear. . Therefore, it is possible to improve the switching accuracy of the ink ribbon without performing a complicated adjustment operation.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. As shown in FIG.
The carrier shaft 2 and the rotating shaft 3 are arranged in parallel and are rotatably held. A print head (not shown) is mounted on a carrier 4 slidably held on a carrier shaft 2, and a cassette mount 6 for detachably holding a multicolor ribbon cassette 5 is supported on a spindle. 7, the carrier 4 is rotatably held in a direction orthogonal to the moving direction of the carrier 4.

A gear 8 is fixed to the end of the rotary shaft 3, and a gear 10 which is driven by a forward / reverse rotatable motor 9 as a driving unit is meshed with the gear 8. Also,
The rotary shaft 3 has a square cross-sectional shape except for bearings at both ends, and a drive gear 11 of a bevel gear is fitted to the rotary shaft 3 so as to be slidable in the axial direction. This drive gear 11
Has a cylindrical portion 12 protruding from both ends thereof and having a circular outer peripheral surface. A flange 13 is formed at an end of the cylindrical portion 12. A driven gear 14 meshed with a drive gear 11 is rotatably held on the carrier 4 with a vertical axis. The driven gear 14 is also a bevel gear. Further, the carrier 4 is provided with a power conversion mechanism 15 for converting the rotational movement of the driven gear 14 into a vertical movement and transmitting the same to the cassette mounting base 6. The power conversion mechanism 15 includes a helical cam 16 formed integrally with the driven gear 14, and a pin 17 protruding from an end of the cassette mount 6 and engaging with the helical cam 16. FIG.
As shown in FIG. 1, the spiral cam 16 has flat surfaces 18 at a plurality of positions which support the pins 17 at right angles to the axis thereof, and these flat surfaces 18 are connected by slopes 19.

Further, the carrier 4 is formed with abutting portions 21 which are opposed to each other and abut against the outer surface of the thrust surface 20 of the driving gear 11. An inverted U-shaped notch 22 to be fitted is formed. Two protruding portions 23 are formed close to each other on the outer periphery of the driving gear 11, and a protruding portion 24 locked between these protruding portions 23 is formed on the outer periphery of the driven gear 14.

In such a configuration, the carrier 4 is guided and driven by the carrier shaft 2 during printing. The drive device of the carrier 4 is a known device that converts the rotational motion of a forward / reverse rotatable motor into linear motion by a belt or a wire and transmits the linear motion to the carrier 4. When the carrier 4 moves, the drive gear 11 moves along the rotation shaft 3 with its thrust surface 20 being pushed by the contact portion 21 of the carrier 4, so that the driven gear 14 is always meshed with the drive gear 11. Thus, when the rotating shaft 3 is rotated by the motor 9, the rotation is transmitted from the driving gear 11 to the driven gear 14, and the helical cam 16 is driven. The cassette mount 6 has a pin 17 formed by a spiral cam 16 by a spring (not shown) or its own weight.
, So that the helical cam 16
The cassette mounting base 6 is rotated about the support shaft 7 by the rotational motion of. Therefore, by stopping the motor 9 in a state where the pins 17 are in contact with any of the flat surfaces 18, the desired ink application surface of the ink ribbon of the ribbon cassette 5 can be opposed to the print head. Also, due to the backlash at the meshing portion between the driving gear 11 and the driven gear 14, the pressure acting on the meshing portion between the driving gear 11 and the driven gear 14 can be reduced, and the bending of the rotating shaft 3 can be prevented. Further, the rotation axis 3 with respect to the moving direction of the carrier 4
Even if the parallelism is incorrect, the change in the shift position of the cassette mount 6 due to the change in the position of the carrier 4 can be absorbed by the backlash of the meshing portion between the drive gear 11 and the driven gear 14. Therefore, it is possible to improve the switching accuracy of the ink ribbon without performing a complicated adjustment operation.

Further, a motor 9 for driving the driven gear 14
Need not be mounted on the carrier 4, circuit components, flexible cables, connectors, and other circuit components mounted on the carrier 4 can be minimized only for the print head. As a result, there is no need to use the carrier 4 properly for a mono-color printer or a color printer,
Further, the capacity of the motor for driving the carrier 4 can be reduced.

Here, in order to control the switching operation of the cassette mount 6, it is necessary to determine the excitation phase of the motor 9 when the cassette mount 6 is at the home position. The motor 9 is rotated until the position 23 is at the top dead center, the excitation phase of the motor 9 at this time is stored, and the driven gear 1 is moved between the projections 23 of the drive gear 11 to be stopped.
4 is engaged with the cassette mounting table 6 in this state.
By adjusting the pin 17 to a desired flat portion 18 of the helical cam 16, the home position can be easily adjusted. By driving the motor 9, the protrusion 23 of the drive gear 11 moves in a vertical plane.
The protrusion 24 of the driven gear 14 deviates from the vertical plane forming the rotation locus of the protrusion 23 and is separated from the protrusion 23 without any problem.

In the above embodiment, a bevel gear is used for the drive gear 11 and the driven gear 14. However, as shown in FIG. 4, a similar purpose can be achieved by using a worm drive gear 25 and a worm wheel driven gear 26. Can be achieved. It goes without saying that a worm wheel may be used as the drive gear and a worm may be used as the driven gear.

[0013]

According to the present invention, a carrier holding a print head and being reciprocally movable and a ribbon cassette are attached to the carrier so as to be displaceable in a direction perpendicular to the moving direction of the carrier. A cassette mounting base, a rotating shaft connected to the driving unit and held with an axis parallel to the moving direction of the carrier, and fitted to the rotating shaft in the rotating direction and slidably fitted in the axial direction. A drive gear, a contact portion provided on the carrier and abutting on a thrust surface of the drive gear, and a driven gear meshed with the drive gear and held on the carrier so as to be rotatable in a direction orthogonal to the rotation axis. And a power conversion mechanism for converting the rotational movement of the driven gear into an axial movement of the driven gear and transmitting the converted movement to the cassette mounting base. When the rotating shaft is rotated, the rotation is transmitted from the driving gear to the driven gear when the rotating shaft is rotated. The rotational motion of the driven gear is converted by the power conversion mechanism and transmitted to the cassette mount, and the color of the ink ribbon is switched.
Due to the backlash at the meshing portion between the driving gear and the driven gear, the pressure acting on the meshing portion between the driving gear and the driven gear can be reduced, and the bending of the rotating shaft can be prevented. Even if the parallelism of the shaft is incorrect, the change in the shift position of the cassette mount due to the change in the position of the carrier can be absorbed by the backlash of the meshing portion between the drive gear and the driven gear.
There is an effect that the switching accuracy of the ink ribbon can be improved without performing a complicated adjustment operation.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view thereof.

FIG. 3 is an exploded perspective view thereof.

FIG. 4 is a perspective view showing another example of the driving gear and the driven gear.

FIG. 5 is a side view showing a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 rotating shaft 4 carrier 5 ribbon cassette 6 cassette mount 9 drive unit 11 drive gear 14 driven gear 15 power conversion mechanism 20 thrust surface 21 contact part 25 drive gear 26 driven gear

Continuation of the front page (56) References JP-A-61-230971 (JP, A) JP-A-50-54414 (JP, A) Jpn.

Claims (1)

(57) [Claims] 1. A carrier holding a print head and held reciprocally and a cassette mounting table holding a ribbon cassette and displaceably attached to the carrier in a direction orthogonal to a moving direction of the carrier. A rotating shaft connected to a driving unit and held with an axis parallel to the moving direction of the carrier, and a driving gear fixed to the rotating shaft in the rotating direction and slidably fitted in the axial direction. A contact portion provided on the carrier and abutting on a thrust surface of the drive gear; a driven gear meshed with the drive gear and rotatably held on the carrier in a direction orthogonal to the rotation axis; An ink ribbon switching device, comprising: a power conversion mechanism for converting a rotational movement of a gear into an axial movement of the driven gear and transmitting the converted movement to the cassette mount.