JP2891959B2 - Ink ribbon 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 apparatus for a printer which performs printing by striking through an ink ribbon, and more particularly to an ink ribbon cassette containing an ink ribbon mounted on a reciprocating carriage.
The present invention relates to an ink ribbon device of a printer in which driving of an ink ribbon and switching of a printing position of the ink ribbon are performed by one stepping motor.

[0002]

2. Description of the Related Art FIG. 6 is a plan view showing an example of a conventional ink ribbon device, and FIG. 7 is a sectional view taken along line AA of FIG.

[0003] In an ink ribbon device of a printer that performs printing by striking through an ink ribbon, an ink ribbon cassette containing the ink ribbon is mounted on a reciprocating carriage, and the driving of the ink ribbon and the printing position of the ink ribbon are performed. The conventional ink ribbon device of the printer in which the switching between the two is performed by one stepping motor is shown in FIG.
When the ink ribbon is driven, the sun gear 43 meshing with the motor gear 42a connected to the shaft of the stepping motor is rotated by rotating the stepping motor. When the sun gear 43 rotates, the planetary gear 44 held by the swing arm 45 coupled to the shaft with the sun gear 43 by the frictional force of a sun gear spring (not shown, see FIG. 1) and meshing with the sun gear 43 also swings. The arm 45 rotates about the axis of the sun gear 43 together with the arm 45. Therefore, when the motor gear 42a rotates counterclockwise, the sun gear 43 rotates clockwise, and the planetary gear 44 also rotates the sun gear 43a.
, And moves to a position where it meshes with a drive gear 55 for driving an ink ribbon in an ink ribbon cassette (not shown). When the planetary gear 44 meshes with the drive gear 55, the planetary gear 44 stops rotating around the axis of the sun gear 43, and the planetary gear 44 rotates counterclockwise by the clockwise rotation of the sun gear 43. Then, the drive gear 55 is rotated clockwise to drive the ink ribbon.

Conversely, when the stepping motor 42 (motor gear 42a) rotates clockwise, the sun gear 43 rotates counterclockwise and the planetary gear 44
5, and rotates counterclockwise about the axis of the sun gear 43. Therefore, the engagement between the planetary gear 44 and the drive gear 55 is disengaged, and the drive gear 55 is not rotated.

As shown in FIGS. 6 and 7, when the stepping motor 42 rotates, the one-way gear 47 meshing with the motor gear 42a also rotates. When the motor gear 42a rotates counterclockwise and the one-way gear 47 rotates clockwise, the one-way clutch 48 mounted on the one-way gear 47 does not operate.
The camshaft 49 serving as the rotation shaft of the one-way gear 47 does not rotate, and accordingly, the cam 54 mounted on the upper portion of the camshaft 49 does not rotate.

Conversely, when the motor gear 42a rotates clockwise and the one-way gear 47 rotates counterclockwise (arrow B), the one-way clutch 48 operates to transmit the rotation of the one-way gear 47 to the camshaft 49. For,
The cam shaft 49 rotates to rotate the cam 54. Since the camshaft 49 is coupled to the cam 54 and a position (eccentric position) off the center thereof as shown in FIG.
When the camshaft 49 rotates, the cam 54 performs a so-called eccentric motion. Since the outer peripheral surface of the cam 54 is always in contact with the upper and lower inner wall surfaces 40a of the outer frame of the cam follower 40, and the cam follower 40 is held so as to be slidable only in the vertical direction (arrow C direction). When the 54 rotates, the cam follower 40 slides in the direction of arrow C. Accordingly, the ink ribbon cassette (not shown, see FIG. 1) mounted on a cassette holder (not shown, see FIG. 2) integrated with the cam follower 40 is moved up and down (in the direction of arrow C) to determine the printing position of the ink ribbon. Perform a switch.

As shown in FIG. 6, two upper projections 54b are provided in the peripheral portion of the upper surface of the cam 54 at both ends in diameter with respect to the cam shaft 49 (see FIG. 5). ). These upper projections 54b are provided with the cam followers 40.
The cam spring 50 presses into the groove 40b provided on the lower surface of the central portion of the cam. In the groove 40b,
A slope 40c is formed along the rotation direction of the cam 54 in the direction of the arrow B (the slope is not formed in the direction opposite to the direction of the arrow B, and the side surface of the upper protrusion 54b and the side surface of the groove 40b contact each other. Do). Accordingly, when the cam 54 rotates, the upper surface of the upper protrusion 54b slides on the slope 40c and comes into contact with the lower surface of the central portion of the cam follower 40, and the cam shaft 49 is pushed downward by the cam follower 40.
In order to perform this operation smoothly, one-way clutch 4
When the clutch 8 is operating, the one-way clutch 48 slips vertically with respect to the camshaft 49.

[0008]

As described above, in the conventional ink ribbon device, when the stepping motor rotates in the counterclockwise direction, the one-way gear runs idle and the rotation of the one-way gear is not transmitted to the camshaft. Despite this, the minute vibration generated when the stepping motor rotates is transmitted to the one-way gear, which is transmitted to the camshaft via the one-way clutch to drive the cam minutely. There is a problem that the position is slightly shifted.

Also, when the printing position of the ink ribbon is switched, the one-way clutch 48 does not slip vertically with respect to the camshaft 49 even if the cam 54 rotates. There is also a disadvantage that switching operation failure may occur without coming off the groove.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional ink ribbon device, to prevent the printing position of the ink ribbon from being shifted, and to prevent the malfunction at the time of switching the printing position of the ink ribbon. It is an object of the present invention to provide an ink ribbon device in which the ink ribbon is prevented.

[0011]

According to the present invention, there is provided an ink ribbon device comprising: a stepping motor; a sun gear for transmitting rotation of the stepping motor; a swing arm coupled to a shaft of the sun gear by a spring pressure; A planetary gear held by a swing arm and meshing with the sun gear; and a sun gear driven by meshing with the planetary gear rotating about the sun gear axis together with the swing arm when the stepping motor rotates in one direction. A drive gear driven by the planetary gears to drive the transport movement of the ink ribbon;
A one-way gear having a one-way clutch coupled to the stepping motor and transmitting the rotation of the stepping motor when the stepping motor rotates in a direction opposite to the one direction; and And a cam follower that switches a printing position of an ink ribbon in an installed ink ribbon cassette by performing a parallel motion by rotating the slide cam, and holding the one-way clutch. A first shaft and a second shaft protruding downward from the lower surface of the slide cam are provided, and one of the first shaft and the second shaft is hollow, and the other is The shaft is inserted into the hollow portion of the one shaft so that both can slide vertically, and the first And a protrusion is provided on one of the second shafts, a notch is provided on the other shaft, and the protrusion and the notch are engaged to rotate the first shaft. The transmission is performed to the second shaft, and further, a play is provided between the protrusion and the notch.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention.
FIG. 2 is a side view of a main part of the printer having the embodiment of FIG. 1,
3 is a cross-sectional view taken along the line HH of FIG. 1 in a state where the ink ribbon is driven, FIG. 4 is a cross-sectional view taken along the line HH of FIG. 1 in a state where the printing position of the ink ribbon is switched, and FIG. FIG. 7A is a diagram showing a relationship between a cam and a camshaft, and FIG.
4B is a front view of the slide cam, FIG. 5B is a bottom view of the slide cam, FIG. 5C is a front view of the camshaft, and FIG. 5D is a plan view of the camshaft.

In FIG. 2, a carriage 1 mounts an ink ribbon cassette 8 accommodating a print head 2 and an ink ribbon 7, and moves the platen 3 and the print head while moving in a left-right direction (a direction perpendicular to the plane of FIG. 2). Printing paper 5 conveyed between feed rollers 2 and 3 by feed rollers 4a and 4b
Is printed via the ink ribbon 7. The card holder 6 is mounted on the carriage 1 and presses the printing paper 5 against the platen 3 so that the printing paper 5 does not rise from the platen 3 during printing.

When the printer having the present ink ribbon device inputs print data from a host device, the print head 2 moves the built-in print pins via the ink ribbon 7 while moving in the horizontal (row) direction by the carriage 1. The printing is performed by hitting the printing paper 5 on the platen 3.

The ink ribbon device is provided above the print head 2 of the carriage 1. When the ink ribbon cassette 8 is mounted on the cassette holder 9, the ink ribbon 7 is driven by the stepping motor 12 and the ink ribbon 7 is transferred to the ink ribbon 7. The print position is switched (by moving the ink ribbon 7 by a certain amount in the direction of arrow D, for example, the print colors of the ink ribbon, which are black and red, are switched).

As shown in FIG. 1, the ink ribbon device of the present embodiment comprises a cassette holder 9 for mounting an ink ribbon cassette 8 and inner wall surfaces 10a of upper and lower frames of a cam follower 10 mounted on the cassette holder 9. 1
A slide cam 11 for switching the printing position on the ink ribbon 7 by moving the cam follower 10 by a fixed amount in the direction of arrow D in contact with the outer surface of the cam cam 19 and a cam shaft 19 serving as a rotation axis of the slide cam 11. The vehicle includes a one-way gear 17, a motor gear 12 a that meshes with the one-way gear 17, and a stepping motor 12 that drives the motor gear 12 a. Motor gear 1
The sun gear 13 meshes with 2a, and the planetary gear 14 meshes with the sun gear 13. The planetary gear 14 has its rotating shaft held by a swing arm 15 mounted on the shaft of the sun gear 13.
Rotates, the sun gear 13 together with the swing arm 15
Perform a pivoting movement about the axis of. The sun gear spring 16 is mounted between the sun gear 13 and the swing arm 15, and applies a frictional force to the sun gear 13 to rotate the swing arm 15 together with the sun gear 13. When the planetary gear 14 rotates with the swing arm 15 and comes to the meshing position, the drive gear 25 stops the rotational movement about the axis of the sun gear 13 and rotates the planetary gear 14 by meshing with the sun gear 13. The ink ribbon 7 in the ink ribbon cassette 8 (see FIG.
Drive) circulatory movement.

When the stepping motor 12 rotates counterclockwise, the sun gear 13 rotates clockwise, and the planetary gear 14 also rotates clockwise about the rotation axis of the sun gear 43 together with the swing arm 15. Therefore, planetary gear 1
4 meshes with the drive gear 25, and rotates the drive gear 25 in the counterclockwise direction (the direction of arrow E).

Conversely, when the stepping motor 12 rotates clockwise, the sun gear 13 rotates counterclockwise,
The planetary gear 14 and the swing arm 15 together with the sun gear 43
Rotate counterclockwise about the axis of. The engagement between the planet gear 14 and the drive gear 25 is released, and the drive gear 25 does not rotate.

The one-way gear 17 has a one-way clutch 18 (see FIG. 3) fixed thereto, and
When the stepping motor 12 rotates in the counterclockwise direction, the rotation is not transmitted to the camshaft 19 only when is rotated clockwise. In this way, the switching of the printing position on the ink ribbon 7 and the driving of the ink ribbon 7 are performed by one stepping motor 12.

FIG. 3 is a sectional view taken along the line HH of FIG. 1 in a state where the ink ribbon is driven.

As shown in FIG. 3, a one-way clutch 18 is fixed to the center of the one-way gear 17, and a hollow camshaft 19 is inserted into the one-way clutch 18, and the one-way clutch 18 is one-way clutch 18. The rotation of the one-way gear 17 is transmitted to the camshaft 19 only when the gear 17 rotates counterclockwise (the stepping motor 12 rotates clockwise). The one-way clutch 18 is held by a bush 21b, and the bush 21b is fixed to a guide 22b. In the hollow camshaft 19, the slide cam 1 is provided.
Slide cam shaft 11c protruding downward from the lower surface of
A slide cam extension shaft 11d protruding further downward from the lower end of the cam shaft 19 penetrates, and the slide cam extension shaft 11d can move up and down in the camshaft 19. The slide cam shaft 11c is rotatably held by a bush 21a fixed to a guide 22a. A cam spring 20 is provided between the slide cam 11 and the guide 22a. The cam spring 20 pushes the slide cam 11 toward the cam follower 10.

FIG. 5 shows an upper end of the camshaft 19.
(C) As shown in (d), two notches 19a having an opening angle of 50 degrees are provided at both ends of the diameter of the camshaft 19, and correspondingly, the notch 19a of the slide cam 11 is provided. At the lower end of the slide cam shaft 11c, as shown in FIGS. 5A and 5B, a protrusion 11e having a divergence angle of 30 degrees.
Are provided at both ends of the diameter of the slide cam shaft 11c. Therefore, when the slide cam extension shaft 11d is inserted into the camshaft 19, the projection 11e of the slide cam shaft 11c is fitted into the notch 19a of the camshaft 19, so that the slide cam shaft 11c 19
It is possible to freely rotate in the camshaft 19 by the difference in angle between a and the projection 11e. In order to detect the fixed position of the printing position switched by the rotation of the slide cam 11, as shown in FIG.
Is provided with a sensor 23. The sensor 23 detects a fixed position by detecting a lower protrusion 11a provided on the lower surface of the slide cam 11 as shown in FIG.

When the ink ribbon is in a driving state, the stepping motor 12 rotates counterclockwise, so that the planetary gear 14 rotates clockwise about the axis of the sun gear 43 together with the swing arm 15 and the drive gear 25 rotates. Mesh with. At this time, since the one-way gear 17 rotates clockwise, the one-way clutch 18 does not act, and thus the rotation of the one-way gear 17 is not transmitted to the camshaft 19, and the slide cam 11 remains stopped.

In this state, when a slight vibration is generated in the rotation of the stepping motor 12 and the stepping motor 12 rotates minutely in the opposite direction, the minute rotation in the opposite direction is transmitted to the camshaft 19 via the one-way clutch 18. The camshaft 19 also rotates slightly, but the notch 19a at the upper end of the camshaft 19 and the slide cam 11
Since there is play between the slide cam shaft 11c and the protrusion 11e at the lower end of the slide cam shaft 11c, the minute rotation of the cam shaft 19 is not transmitted to the slide cam 11. Therefore, the cam follower 10
Is not driven to move the ink ribbon cassette 8 mounted via the cassette holder 9, so that the printing position of the ink ribbon 7 does not shift.

FIG. 4 is a sectional view taken along the line HH of FIG. 1 in a state where the printing position of the ink ribbon is switched.

When the printing position of the ink ribbon is switched, the stepping motor 12 rotates clockwise, so that the planetary gear 14 rotates counterclockwise about the axis of the sun gear 43 together with the swing arm 15. Therefore, the engagement between the planetary gear 14 and the drive gear 25 is disengaged, and the ink ribbon is not driven. At this time, since the one-way gear 17 rotates counterclockwise, the one-way clutch 18 operates to transmit the rotation of the one-way gear 17 to the camshaft 19. The rotation of the camshaft 19 is controlled by the notch 19a at the upper end of the camshaft 19 and the projection 11 at the lower end of the slide camshaft 11c of the slide cam 11.
e, the slide cam shaft 11c of the slide cam 11
The slide cam 11 rotates to move the cam follower 10 (in the direction of arrow D in FIG. 1). After the slide cam 11 is rotated by 180 degrees and the printing position of the ink ribbon is switched, when the slide cam 11 further attempts to rotate, the slide cam 11 fitted in the groove 10 b provided on the lower surface of the cam follower 10. Of the upper protrusion 11b slips off the slope 10c provided in the groove 10b and comes off the groove 10b, and the upper surface of the upper protrusion 11b comes into contact with the lower surface of the cam follower 10, so that the slide cam 11, that is, the slide cam shaft 11c Compresses the cam spring 20 and moves down to hold the printing position where the ink ribbon is switched. At this time, the slide cam shaft 11c
Since the slide camshaft 11c can be freely moved up and down in the hollow camshaft 19, the lowering operation of the slide camshaft 11c
9 and therefore does not affect the one-way clutch 18. Therefore, one-way clutch 1
Even if the upper and lower parts 8 do not perform a vertical slip operation, a printing position switching operation defect does not occur.

[0028]

As described above, in the ink ribbon apparatus of the present invention, the shaft for transmitting the rotation of the one-way gear to the slide cam is divided into upper and lower parts, one shaft being hollow and the other shaft being hollow. The two shafts are inserted into the shaft to allow relative movement in the vertical direction.A protrusion is provided on one of the two shafts, and a notch is provided on the other shaft. By transmitting the rotation of the shaft to the other shaft, there is an effect that it is possible to prevent a printing position switching operation failure when the printing position of the ink ribbon is switched. Further, by providing play between the projection and the notch, there is also an effect that it is possible to prevent a shift in the printing position of the ink ribbon due to a minute vibration in the rotation of the stepping motor.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a side view of a main part of the printer having the embodiment of FIG. 1;

FIG. 3 is a sectional view taken along line HH of FIG.
It is a line sectional view.

FIG. 4 is a cross-sectional view taken along line HH of FIG. 1 in a printing position switching state of the ink ribbon.

5A and 5B are diagrams showing a relationship between a slide cam and a camshaft according to the embodiment of FIG. 1, wherein FIG.
(B) is a bottom view of the slide cam, (c) is a front view of the camshaft, and (d) is a plan view of the camshaft.

FIG. 6 is a plan view showing an example of a conventional ink ribbon device.

FIG. 7 is a sectional view taken along line AA of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 2 Print head 3 Platen 4a, 4b Feed roller 5 Printing paper 6 Card holder 7 Ink ribbon 8 Ink ribbon cassette 9 Cassette holder 10, 40 Cam follower 10a, 40a Inner wall surface 10b, 40b Groove 10c, 40c Slope 11 Slide cam 11a Lower projection Part 11b / 54b Upper projection 11c Slide cam shaft 11d Slide cam extension shaft 11e Projection 12.42 Stepping motor 12a / 42a Motor gear 13,43 Sun gear 14,44 Planetary gear 15,45 Swing arm 16 Sun gear spring 17,47 One way gear 18.48 one-way clutch 19.49 camshaft 19a notch 20.50 cam spring 21a.21b bush 22a.22b guide 23 sensor 2 · 55 drive gear 54 cam

Claims (2)

(57) [Claims] 1. A stepping motor, a sun gear for transmitting rotation of the stepping motor, a swing arm coupled to a shaft of the sun gear by spring pressure, and a planetary gear held by the swing arm and meshing with the sun gear. When the stepping motor rotates in one direction, the planetary gear that rotates about the sun gear axis together with the swing arm when driven by the sun gear is driven by the planetary gear driven by the sun gear to rotate the ink ribbon. A one-way gear having a one-way clutch coupled to the stepping motor for driving a conveying motion and transmitting the rotational motion of the stepping motor when the stepping motor rotates in a direction opposite to the one direction; , The rotation of the one-way gear An ink ribbon device comprising: a slide cam that rotates when rotation is transmitted; and a cam follower that switches a printing position of an ink ribbon in an ink ribbon cassette mounted by performing a parallel motion by the rotation of the slide cam. A first shaft held by a one-way clutch and a second shaft projecting downward from the lower surface of the slide cam are provided, and one of the first shaft and the second shaft is hollow. And, the other shaft is inserted into the hollow portion of the one shaft so that both are slidable in the up and down direction, a projection is provided on one of the first shaft and the second shaft, A notch provided on the other shaft, wherein the protrusion and the notch are engaged to transmit rotation of the first shaft to the second shaft. . 2. The ink ribbon device according to claim 1, wherein a play is provided between the protrusion and the notch.