JPH0425152B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] 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 a recording paper, the present invention relates to an ink ribbon drive device for a printer. The present invention relates to an ink ribbon drive device for a printer that obtains driving force from reciprocating motion through a drive lever, pawl, and ratchet.

<Prior Art> 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
6 is rotated in direction B, the ink ribbon can only be driven once every two lines in bidirectional printing, and the amount of ink ribbon feed is small even in unidirectional printing. The disadvantage is that the same spot on the ribbon is struck many times, and the ink density 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.

<Purpose> The present invention eliminates these drawbacks.The purpose of the present invention is to increase the feed amount of the ink ribbon with the same drive lever stroke as the conventional one, eliminate ink shading on the left and right sides of the recording paper, and improve the quality of the paper. An object of the present invention is to provide an ink ribbon drive device for a printer that can obtain high printing quality.

<Example> The present invention will be explained below with reference to the drawings.

FIG. 1 is a perspective view of one embodiment of the present invention, and FIG.
3 are partial views showing the operating state. A drive lever 4 is supported on a frame 3 so that it can swing left and right, and a ratchet 5 is supported rotatably. A slope 6 that meshes with the teeth of the ratchet 5
a, a first feed pawl 6 having an escape slope 6b and moving in the same direction as the drive lever is connected to the drive lever 4;
It is rotatably supported on the shaft. An auxiliary drive lever 10 is rotatably supported on the frame 3 by a fulcrum shaft 8, and has one end engaged with the drive lever 4 via a drive pin 9 fixed to the drive lever 4.
A second feed pawl 7 has a slope 7a that engages with the tooth pattern of the ratchet 5 and a slope 7b that escapes at the other end.
is rotatably supported and moves in the opposite direction to the drive lever 4. The first feeding claw 6 and the second feeding claw 7
are biased in the direction of engagement with the ratchet 5 by pawl springs 11 and 12, respectively. A carriage 2 carrying a printing head 1 is reciprocated from side to side by an external means (not shown), and at this time prints on recording paper (not shown) via an ink ribbon 13. The ink ribbon 13 obtains energy from the reciprocating motion of the carriage 2, and the drive lever 4 uses the first feed pawl 6 on the outward path, the second feed pawl 7 on the return path, and
The ink ribbon is then driven via a ratchet 5 and an ink ribbon feed roller 14. The operation of the above embodiment will be explained in detail using FIGS. 2 and 3. When the carriage 2 carrying the print head 1 is moved in the direction of arrow A by an external means (not shown), 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 arrow A. Further, the first feed pawl 6 rotatably supported by the drive lever 4 moves in the A direction, and the second feed pawl 7 rotatably supported by the auxiliary drive lever 10 moves in the direction A. 10 is rotatably supported on the frame 3 by a fulcrum shaft 8, and is engaged by the drive lever 4 and a drive pin 9, so that it rotates around the fulcrum shaft 8, and as a result, the direction of movement of the drive lever 4 Move in the opposite direction of arrow A′. At this time, the ratchet 5 is
The first feed pawl 6, which is biased toward 5 rotates in the direction of arrow B. Next, when the carriage 2 moves in the direction of arrow A', the drive lever 4 is moved within the trajectory of the carriage 2, as described above.
Because of the protrusion 4b, the drive lever 4 also engages with the carriage 2 and moves in the direction of arrow A'. On this occasion,
Similarly to the above, the first feed pawl 6 moves in the direction of arrow A' like the drive lever 4, and the second feed pawl 7 moves in the direction of arrow A opposite to the drive lever 4. The first feed pawl 6 has a slope 6 that escapes from the tooth profile of the ratchet 5.
b. Since the second feed pawl 7 engages with the engaging slope 7a, the ratchet 5 rotates in the direction of arrow B in the same manner as described above. The rotational force of the ratchet 5 operating in this manner is transmitted via the ink ribbon feed roller 14 shown in FIG. 1 to drive the ink ribbon 13.

With the structure described above, the ink ribbon can be fed on both the outward and return paths of the carriage, and the ink ribbon can be fed twice as much as the conventional example with the same drive lever stroke as the conventional example. can. Furthermore, during unidirectional printing, the ink ribbon is fed twice per line, and during bidirectional printing, the ink ribbon is fed once per line. For this reason,
Good print quality with no shading on the left and right sides of the recording paper was obtained for both unidirectional and bidirectional printing.

FIG. 4 shows another embodiment of the present invention, in which a drive lever 34 is pivotally supported on a frame 43 so as to be able to swing left and right, and the frame 43 and the drive lever 34 are connected via a return spring 16. engaged. Ratchet 5, first feed pawl 6, fulcrum shaft 8,
The drive pin 9, the auxiliary drive lever 10, the second feed pawl 7, and the pawl springs 11 and 12 are constructed in the same manner as in the previous embodiment. 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, the carriage 2
begins to move in the direction of arrow A', drive lever 3
4 is connected to the frame 43 by the return spring 16, and as the carriage 2 moves, it begins to move in the direction of arrow A' due to the force of the return spring 16.
By moving the drive lever 34 in the direction of arrow A', the ratchet 5 is moved in the direction of arrow B as in the previous embodiment.
Rotate in the direction.

With the above structure, it is possible to obtain twice the ink ribbon feed amount as in the conventional example with the same drive lever stroke as in 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 provide the engaging portions on only one side and obtain the same ink ribbon feed amount as in the previous embodiment.

<Effects> As described above, the present invention includes a first lever member that moves in the direction of movement of the carriage, a shaft that is rotatably supported by the first lever member, and one end that is rotatably supported by the first lever member via a shaft. a second lever member that is connected to the first lever member and swings in the direction of movement of the first lever member, the other end forming a free end that swings in the opposite direction to the first lever member; a first pawl that is rotatably supported by the first lever member and that engages with the teeth of the ratchet when the carriage moves in one direction; a second pawl that is supported by the second pawl and engages with the teeth of the ratchet when the carriage moves in the opposite direction; and a spring that biases the first and second pawls in a direction to engage the ratchet. It has a member. Therefore, the ratchet can be rotated via the first pawl and second pawl on both the forward and return trips of the carriage, and twice the ink ribbon feeding amount can be obtained with the same stroke as the conventional drive lever. Therefore, good print quality without ink shading at the left and right edges of the recording paper can be obtained in both unidirectional and bidirectional printing.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention;
3 are diagrams showing the operating state of one embodiment according to the present invention, FIG. 4 is a plan view of another embodiment according to the present invention, and FIG. 5 is a plan view of a conventional example. 1... Print head, 2, 22... Carriage,
3, 43... Frame, 4, 24, 34... Drive lever, 5, 25... Ratchet, 6, 7, 26
...Feed claw, 8...Fully shaft, 9...Drive pin, 1
0... Auxiliary drive lever, 11, 12, 28... Claw spring, 13... Ink ribbon, 14... Ink ribbon feed roller, 15... Ink ribbon cassette, 16, 32... Return spring.

Claims (1)

[Scope of Claims] 1. An ink ribbon for a printer comprising a carriage carrying a print head and moving back and forth, a ratchet that receives power from the carriage to rotate, and a roller driven by the ratchet to feed the ink ribbon. The drive device includes: a frame that rotatably supports the ratchet; a first lever member that contacts the carriage at least at one of the turning points of the reciprocating movement of the carriage and is capable of reciprocating in the direction of movement of the carriage; It is rotatably supported on a shaft erected in the frame, one end is connected to the first lever member about the shaft, and swings in the moving direction of the first lever member, and the other end is connected to the first lever member. a second lever member forming a free end that swings in the opposite direction to the first lever member; and a second lever member that is rotatably supported by the first lever member and moves in the same direction as the first lever member. a second pawl that is rotatably supported by the free end of the second lever member and moves in a direction opposite to the first lever member; a spring member that is negatively biased in the direction of engagement with the ratchet, and the first pawl has a slope that engages with the teeth of the ratchet when the first lever member moves in one direction; a sloped surface that escapes the teeth of the ratchet when the member moves in the opposite direction; the second pawl has a slope that engages the teeth of the ratchet when the second lever member moves in one direction; and a sloped surface that escapes the teeth of the ratchet when the second lever moves in the opposite direction, and the first pawl and the second pawl are arranged on the forward and backward paths of the first lever member. An ink ribbon drive device for a printer, characterized in that the ink ribbon is meshed with the ratchet, and alternately rotates the ratchet during the outward and return passes to feed the ink ribbon.