JPH0377069B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink ribbon drive device for a printer, and more specifically, in a serial printer in which a carriage carrying a print head performs printing by reciprocating across recording paper, the present invention relates to an ink ribbon drive device for a printer. The driving force is obtained through the drive lever, pawl, and ratchet. The present invention relates to an ink ribbon drive device for a printer.

Conventionally, the ink ribbon drive device of this type of printer has a head carriage 2, as shown in FIG.
2, the drive lever 24 only on the outward path (direction of arrow A);
The pulling claw 26 rotates in the directions of arrows C and D, and the pulling claw 2
Since the ratchet 25 that engages with the ink ribbon 6 was rotated in the B direction, the ink ribbon could only be driven once every two lines during bidirectional printing, and the ink ribbon was not fed as much during unidirectional printing. The disadvantage is that the same spot is struck many times, and the density of the ink differs on the left and right sides of the recording paper depending on the direction in which the ink ribbon is fed, making it impossible to obtain good print quality. As a method for eliminating the above-mentioned drawbacks, there is a method of extending the stroke of the drive lever 24 in the direction of arrow A;
One possible method is to increase the lever ratio of the drive lever 24, but in the former case, there is a possibility that the load when driving the ink ribbon will be applied to the print head 1 during printing, and in that case, printing will be adversely affected. Furthermore, in the latter case, as the lever ratio increases, the load applied to the carriage increases, which adversely affects printing. Furthermore, both of them have the disadvantage that the area occupied by the drive lever increases due to the increase in the amount of movement of the drive lever, resulting in a disadvantage in terms of space.

The present invention eliminates these drawbacks, and its purpose is to increase the amount of ink ribbon feed with the same drive lever stroke as in the past, eliminate ink shading on the left and right sides of the recording paper, and improve print quality. An object of the present invention is to provide an ink ribbon drive device for a printer that can obtain the following properties.

The ink ribbon drive device for a printer according to the present invention is an ink ribbon drive device for a printer in which a carriage equipped with a print head moves back and forth in the horizontal direction with respect to recording paper, and prints via the ink ribbon. A drive lever that is slidably supported and is reciprocated by coming into contact with the carriage at at least one of the turning points of the reciprocating stroke of the carriage, and a drive lever that is rotatably supported by the frame and drives an ink ribbon feed roller that drives the ink ribbon to be conveyed. a ratchet, which is swingably supported on the drive lever, and a pull pawl, which is formed with a slope that engages with the tooth profile of the ratchet on the forward path and a slope that escapes the tooth profile on the return path;
The drive lever is equipped with a pushing pawl formed with a slope that escapes the tooth profile of the ratchet on the outward path and a slope that engages with the tooth profile on the return trip, and an elastic member that biases the pulling pawl and the pushing pawl in a direction to engage the ratchet. The mechanism is characterized in that the pulling pawl and the pushing pawl move back and forth as a result of the operation, and the ratchet is rotationally driven to convey the ink ribbon.

Hereinafter, the present invention will be explained using the drawings.

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is a plan view thereof, and Fig. 3 is a partial view showing the operating state. Similarly, the ratchet 5 is rotatably supported. It has slopes 6a, 7a that engage with the tooth profile of the ratchet 5 and slopes 6b, 7b that escape, and a pull pawl 6 that engages with the tooth profile of the ratchet 5 on the outward path and escapes on the return path, and a push pawl 7 that engages on the forward path and engages on the return path. It is freely supported by the drive lever 4. The pulling pawl 6 and the pushing pawl 7 have the same shape, and the pawl spring 8 holds the ratchet 5.
is biased in the direction of engagement. Print head 1
Carriage 2 equipped with external means (not shown)
The ink ribbon 1 moves back and forth from side to side.
0 on recording paper (not shown).
Generally, when printing in this type of printer, a carriage 2 carrying a print head 1 moves back and forth over a fixed distance to print. The ink ribbon 10 receives energy from the reciprocating motion of the carriage 2 and is driven via a drive lever 4, a pull pawl 6 on the forward path, a push pawl 7 on the return path, a ratchet 5, and an ink ribbon feed roller 9. The operation of the above embodiment will be explained in detail using FIGS. 2 and 3. By external means (not shown) the print head 1
When the carriage 2 carrying the carriage 2 moves in the direction of the arrow A, since the protrusion 4a of the drive lever 4 is within its trajectory, the drive lever 4 also engages with the carriage 2 and moves in the direction of the arrow A. Further, the pull claw 6 and the push claw 7, which are rotatably supported by the drive lever 4, also move in the direction of arrow A. At this time, the pull pawl 6, which is urged to engage with the ratchet 5 by the pawl spring 8, engages with the slope 6a that meshes with the tooth profile of the ratchet 5, and the push pawl 7 engages with the slope 7b that escapes from the tooth profile. Since it is engaged, the ratchet 5 is indicated by arrow B.
Rotate in the direction. In other words, the pull pawl 6 rotatably supported by the drive lever 4, which engages with the carriage 2 and moves in the direction of arrow A, moves the ratchet 5 in the direction of arrow A with the inclined surface 6a that engages with the tooth profile of the ratchet 5. shall be. Since the ratchet 5 is rotatably supported by the frame 3, the force for moving it in the direction of arrow A is converted into the force for rotating the ratchet 5 in the direction of arrow B, so that the ratchet 5 rotates in the direction of arrow B. At this time, the push pawl 7 is pressed against the ratchet 5.
Since the tooth profile of the ratchet 5 is engaged with the escaping slope 7b, the ratchet 5 moves in the direction of arrow A while escaping the teeth of the ratchet 5. Next, when the moving direction of the carriage 2 is in the direction of the arrow A', the protrusion 4b of the drive lever 4 is within the trajectory of the carriage 2, so the drive lever 4 also engages with the carriage 2 and moves in the direction of the arrow A'.
Move in direction A′. At this time, contrary to the above, the pull pawl 6 supported by the pawl spring 8 to engage with the ratchet 5 engages with the slope 6b that escapes from the tooth profile of the ratchet 5, and the push pawl 7 engages with the slope 6b that engages with the tooth profile. It is engaged at 7a. Therefore, the ratchet 5 rotates in the direction of arrow B in the same manner as described above. In other words, the push pawl 7 is rotatably supported by a drive lever 4 that engages with the carriage 2 and moves in the direction of arrow A'.
attempts to move the ratchet 5 in the direction of arrow A' with the slope 7a that meshes with the tooth profile of the ratchet 5.
Since the ratchet 5 is rotatably supported by the frame 3, the force for moving it in the direction of arrow A' is converted into the force for rotating the ratchet 5 in the direction of arrow B, so that the ratchet 5 rotates in the direction of arrow B. At this time, the pulling pawl 6 is attached to the ratchet 5 of the ratchet 5.
Since it engages with the slope 6b that escapes the tooth profile of the ratchet 5, it moves in the direction of arrow A' while escaping the teeth of the ratchet 5. The rotational force of the ratchet 5 operating in this manner is transmitted through the ink ribbon feed roller 9 shown in FIG. 1 to drive the ink ribbon 10.

With the above structure, the carriage 2 engages with the drive lever 4 at two locations, the end of the forward path and the end of the return path, and feeds the ink ribbon 10. Therefore, the ink ribbon can be fed twice as much as in the conventional example with the same drive lever stroke as in the conventional example. Also, for unidirectional printing, 1
The ink ribbon is fed twice per line, and when printing in both directions, the ink ribbon is fed once per line. Therefore, good print quality with no shading on the left and right sides of the recording paper can be obtained in both unidirectional and bidirectional printing.

Further, the pulling pawl 6 and the pushing pawl 7 may be provided with a slope that engages with the tooth profile of the ratchet 5 and a slope that escapes only on the side that engages with the ratchet 5, but as in this embodiment, by providing slopes on both sides. , parts can be standardized and costs can be reduced.

FIG. 4 shows another embodiment of the present invention, in which a drive lever 14 is pivotally supported on a frame 13 so as to be able to swing left and right, and is engaged with the frame 13 via a return spring 12. . The ratchet 5, pulling pawl 6, and pushing pawl 7 are supported in the same manner as described above.
When the carriage 2 moves in the direction of arrow A, it operates in the same manner as in the previous embodiment and rotates the ratchet 5 in the direction of arrow B. Next, when the carriage 2 begins to move in the direction of arrow A', the drive lever 14 is connected to the frame 13 by the return spring 12, so as the carriage 2 moves, the force of the return spring 12 causes the drive lever 14 to move in the direction of arrow A'. start. Drive lever 14
By moving in the direction of arrow A', the ratchet 5 is rotated in the direction of arrow B as in the previous embodiment.

With the above structure, it is possible to obtain an ink ribbon feed amount twice that of the conventional example with the same drive lever stroke as the conventional example.

Further, even when it is not possible to provide the engaging portions on both sides due to space constraints, it is possible to obtain the same amount of ink ribbon feed as in the embodiments described above even if the engaging portions are provided only on one side.

Furthermore, even in printers that are structured so that the carriage returns to the home position from the place where printing has finished, without making a reciprocating movement over a fixed distance,
As the carriage returns to its home position, it engages with the drive lever and feeds the ink ribbon. Further, when the carriage moves away from the home position to perform printing, the drive lever is moved by the force of the return spring to feed the ink ribbon. Therefore, it is possible to obtain an ink ribbon feed amount equivalent to that of the above embodiment.

As explained above, the present invention moves the drive lever left and right within the trajectory of the carriage carrying the print head during reciprocating movement, and
On both return trips, the ratchet can be rotated via the pull and push pawls, making it possible to obtain twice the amount of ink ribbon feed with the same drive lever stroke as in the conventional example, and to increase the amount of ink on the left and right sides of the recording paper. It is possible to provide an ink ribbon drive device for a printer that can obtain good print quality without shading.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention, FIGS. 2 and 3 are a plan view and a partial view of the embodiment of FIG. Embodiment FIG. 5 shows a plan view of a conventional example. 1... Print head, 2, 22... Carriage,
3, 13, 23...frame, 4, 14, 24...
...Drive lever, 5...Ratchet, 6...Retraction pawl, 8...Claw spring, 9...Ink ribbon feed roller, 10...Ink ribbon, 11...Ink ribbon cassette, 12...Return spring, 33... Reverse stop.

Claims (1)

[Scope of Claims] 1. In an ink ribbon drive device of a printer in which a carriage equipped with a print head moves back and forth in the horizontal direction with respect to recording paper and prints via an ink ribbon, the carriage is slidable on the frame of the printer. Supported by
a drive lever that comes into contact with the carriage and is reciprocated at at least one of the turning points of the reciprocating stroke of the carriage; and a ratchet that is rotatably supported by the frame and that drives an ink ribbon feed roller that transports and drives the ink ribbon. , a pulling pawl that is swingably supported by the drive lever and has a slope that engages with the tooth profile of the ratchet in the outward path and a slope that escapes the tooth profile in the outward path; a pushing pawl formed with a slope that escapes the tooth profile of the ratchet on the return path and a slope that engages with the tooth profile on the return path, and an elastic member that biases the first pulling pawl and the pushing pawl in a direction to engage the ratchet; An ink ribbon drive device for a printer, wherein the reciprocating movement of the drive lever causes the pull pawl and the push pawl to reciprocate, and the ratchet is rotationally driven to convey the ink ribbon.