JPH0630943B2 - Ink ribbon feeder - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ribbon driving device such as a printer / typewriter that employs a reciprocal printing method and a ribbon cassette fixing method. The present invention relates to an ink ribbon feeding device for driving an ink ribbon stored in a cartridge in one direction.

[Prior art]

The reciprocal printing method in which the printing head is driven to perform printing on both the forward and backward paths of a carriage such as a printer and a typewriter has an advantage that the printing time is about half that of the one-way printing method. In addition, the ribbon cassette fixing method, in which the printing ribbon cassette is separated from the carriage and only the printing ribbon is sent in one direction, has a larger ribbon cassette size than the ribbon cassette moving method in which the printing ribbon cassette is mounted on the carriage and reciprocates. Since more ribbons can be accommodated, the life of the ribbon can be extended, and the weight of the carriage can be reduced. Therefore, the carriage drive motor can be downsized.

A conventional example of this system is Japanese Patent Publication No. 58-191182.
In other words, the print head is fixed to the carriage and the ribbon cassette is supported by the frame to accommodate the ink ribbon.

The carriage is moved in the printing direction by the pulse motor via the timing belt. The movement of the timing belt is related to a driven pulley, a gear integrally provided with the driven pulley, a planetary gear having two large and small gears rotatably supported by a planetary lever by a gear shaft, and a ribbon cassette. It is composed of a gear body or the like having two types of gears having different ends and having matching ends.

The ink ribbon feeding roller is constantly driven via the ink ribbon driving means, and the ink ribbon is fed between the ink ribbon feeding roller and the ink ribbon holding roller. Therefore, the ink ribbon is fed in a fixed direction by the movement of the planetary lever and the planetary gear, even if the rotation direction of the pulse motor for driving the carriage is reversed, that is, whether the carriage moves left or right. .

[Problems to be solved by the invention]

Although the conventional example has been described above, in a printer that performs reciprocal printing, the ribbon feeding direction is the same due to the action of the planetary lever and the planetary gear when the carriage moves back and forth in order to prevent the print from fading. Is sending the ink ribbon at a constant speed.

However, in such a conventional example, the relative speed of the ribbon differs depending on the reciprocating direction of the carriage, and the relative speed of the ribbon in the forward path (right direction) of the carriage 1 is higher than that in the backward path (left direction). As a result, the usage state of the ink ribbon is not uniform, and although some portions can be used sufficiently, other portions cannot be used, and the cost of the ink ribbon as a whole tends to be high.

Further, the relative speed of the ribbon in the forward direction of the carriage is affected by the ribbon speed due to the sliding resistance of the ribbon generated in the print head portion and the ribbon mask portion (the rigidity and friction coefficient of the ribbon itself also change in a high temperature environment). Therefore, the relative speed of the ink ribbon on the carriage forward path fluctuates along with the disturbance of the uniform speed of the carriage due to the fluctuation of the load due to the sliding resistance, and the print content of the print medium becomes faint at a certain part or prints after repeated use The problem of reduced printing accuracy, which causes defects, has not been solved.

The present invention has been made in view of the above problems, and provides an ink ribbon feeding device that reduces the relative speed of the ribbon when the carriage moves in the anti-ribbon feeding direction to improve the ribbon usage efficiency and the printing accuracy. The purpose is to provide.

[Means for solving problems]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an ink ribbon feed so that the ribbon velocity U _R <carriage velocity U _C is satisfied and the relative velocity of the ribbon is slowed when the carriage 1 moves in the anti-ribbon feed direction. It is characterized in that the gear ratio of the gears (11c, 12) of the driving means is selected.

EXAMPLES The present invention will be described below.

FIG. 1 is a perspective view of the periphery of an ink ribbon drive device embodying the present invention. Reference numeral 1 denotes a carriage, which slides in the left-right direction along two carriage guide shafts 2 and 3 whose both ends are supported by a frame (not shown). Four
Is a printing head and is fixed to the carriage 1. The timing belt 5, which is engaged with the carriage 1 at the bottom 1a of the carriage 1, has an endless shape, and one end is connected to the timing pulley 6 on the driven side and the other end is connected to the carriage motor 8 via the timing pulley 7 on the driving side. It is designed to be driven by a pulse motor (hereinafter referred to as a carriage motor). Further, the gear 9 formed integrally with the timing pulley 6 has a large-diameter gear 11 rotatably supported by a gear shaft 11a fixed to a planetary gear support plate 10.
Large-diameter gear 1 of planetary gear 11 having b and small-diameter gear 11c
It meshes with 1b. 12 is a first driven gear,
It comprises a large diameter gear 12a and a small diameter gear 12b, and the small diameter gear 12b meshes with an ink ribbon drive gear 13 formed integrally with the ink ribbon drive shaft 13a. The ink ribbon drive gear 13 meshes with the small diameter gear 14b of the third driven gear 14 including the large diameter gear 14a and the small diameter gear 14b. The large diameter gear 14a of the third driven gear 14 is the large diameter gear 1
5a and the small diameter gear 15b mesh with the small diameter gear 15b of the second driven gear 15.

As described above, the ink ribbon feeding drive means includes the planetary gear 11, which is rotatably supported by the gear shaft 11a fixed to the gear 9 and the planetary gear support plate 10, the first driven gear 12, and the ink ribbon drive gear 13. , Second and third driven gears 15/1
It is attached to a substrate 16 composed of four. 2 and 3 show the relationship of the ink ribbon feeding drive means. The planetary gear support plate 10 can rotate in a horizontal plane with a shaft 6a, which is the same as that of the timing pulley 6, as a rotation center, as shown in FIGS.

Reference numeral 10 a is a protruding guide piece provided on the planetary gear support plate 10 and slides on the substrate 16 as the planetary gear support plate 10 rotates. The tip of the ink ribbon drive shaft 13a engages with a recess (not shown) of a protrusion 18a provided at the bottom of the ribbon feed roller 18 in the ink ribbon cassette 17 to constantly urge the ribbon feed roller 18 to rotate. . Therefore, the ribbon 19 is composed of the ribbon feeding roller 18 and the ribbon pressing roller 2
0, and the ribbon 19 is connected endlessly, so that the ribbon 19 is folded and stored in the main body of the ink ribbon cassette 17. In addition, 21 is a ribbon mask.

[Work]

When the timing belt 5 is driven so that the carriage 1 moves leftward, that is, in the direction A in the figure, the planetary gear 1 is rotated by the counterclockwise rotation (hereinafter CCW) of the gear 9.
1 rotates to mesh with the large diameter gear 11b and the large diameter gear 15a of the second driven gear 15. The movement of the small diameter gear 15 causes the ink ribbon drive gear 13 to rotate CCW.
It is transmitted to the ink ribbon drive gear 13 via b, the large diameter gear 14a, and the small diameter gear 14b.

When the timing belt 5 is driven so that the carriage 1 moves to the right, that is, the direction B in the figure, the gear 9
The small diameter gear 11c of the planetary gear 11 meshes with the large diameter gear 12a of the first driven gear 12 by the clockwise rotation (hereinafter, referred to as CW). The movement is transmitted to the ink ribbon drive gear 13 via the small diameter gear 12b so as to rotate the ink ribbon drive gear 13 in CCW.

Therefore, when the timing belt 5 is driven so as to move the carriage 1 leftward (A direction) and rightward (B direction), the ink ribbon drive gear 13 is
Since the CCW rotates, the ribbon 19 is the ribbon feed roller 1.
8 and the ribbon pressing roller 20 and is fed in a fixed direction indicated by a solid arrow in the figure.

Here, the correlation between the relative speed of the ribbon, that is, the speed of the carriage 1 and the speed of the ribbon 19 will be described. Now, the ribbon speed _{U R} (mm / sec) carriage velocity _{U C} (mm /
Second), the relative speed of the ribbon on the ribbon 19 is as follows depending on the moving direction of the carriage 1.

A direction (backward) the value by the traveling time of U _C -U _R B direction (forward path) during running becomes U _C + _{U R} drive direction are different.

For example, at 180CPS, the carriage speed is When it does not move the ribbon in the forward i.e. U ribbon used ranges by the relative rates of _{R =} 0 is _{(U C -U R) x T} = 457.2 × 926 × 10 -6 = 0.42mm where T is the dot impact cycle 926 μsec in time
When the wire diameter d = 0.3 mm, the ribbon unused area = 0.12 mm, that the case where state carriage moves, a U _R> 0 since a defective feeding ribbon ribbon slack is generated by Yes turning the ribbon is necessary.

Therefore, although the ribbon use areas overlap in the return direction, the ribbon speed U _R min at which the ribbon use areas on the return path start to overlap is Accordingly, the ribbon speed of overlapping regions U R _'> U _R min becomes and the speed at which completely overlaps U
_{Since R} max = U _C , U _C > U _R Therefore, even when U _R = 0, the ribbon can be unused in the forward path, and therefore, the ribbon slack is prevented as a condition for giving the ribbon speed. A slow speed is enough for the outbound trip.

Therefore, in order to use the ribbon 19 efficiently, it is necessary to satisfy the ribbon speed U _R <carriage speed U _C and slow the U _R as a setting condition when the carriage 1 is in the forward path. I will give you an explanation. That is, the conventional ribbon speed forward 100 mm / S, the ribbon speed forward 30 mm / S, when the return path 100 mm / S ribbon use range of the return path 100 mm / S The present invention is (U _C ± U _R) XT From (+ is the outbound path,
-Is the return path), Becomes

Therefore, slowing down the speed of the ribbon 19 during traveling of the carriage 1 in the anti-ribbon feed direction is a reduction in its relative speed, and as a result, the ribbon 19 can be used efficiently.

Further, the sliding resistance of the ribbon 19 is generated by the rigidity of the ribbon and the frictional resistance of the sliding portions of the print head 4 and the ribbon mask 21 and the like, and greatly affects the speed of the ribbon 19. In particular, since the relative speed on the outward path is larger than that on the return path, and the frictional resistance is also larger, the speed of the ribbon 19 (U
_R ) is slowed down and the relative speed is reduced, so that the fluctuation due to the sliding resistance is reduced, the print content of the print medium becomes light at a certain portion, and the printing accuracy is lowered with repeated use. To be done.

Further, in a high-low temperature environment, the carriage motor 8 cannot follow the speed due to a considerable load (sliding resistance) fluctuation due to the reciprocating motion of the carriage 1, and the carriage motor 8 requires a large torque margin. Speed U
_{Since R} is slowed down and the increase in load due to ribbon traveling is suppressed as much as possible, there is an advantage that the step-out phenomenon is not induced even if the capacity of the carriage motor is not increased.

〔The invention's effect〕

As described above, the ink ribbon feeding device according to the present invention feeds the ink ribbon so that the relative velocity of the ribbon is slowed when the carriage moves in the anti-ribbon feeding direction while satisfying the ribbon velocity U _R <carriage velocity U _C. Since the gear ratio of the gears of the driving means is selected, printing is performed due to the waste of the ribbon due to the difference in the relative speed of the ink ribbon and the fluctuation of the load due to the increase of the relative speed and the sliding resistance of the ink ribbon in the carriage forward path. Problems such as the print content of the medium being lightened at a certain portion and the print accuracy being lowered with repeated use were alleviated, and ribbon use efficiency and print accuracy were improved.

Further, since the ribbon speed is slowed down and the load increase due to the ribbon running is suppressed as much as possible, there is a practical effect that the step-out phenomenon that the speed cannot be followed is not induced even if the capacity of the carriage motor is not increased.

[Brief description of drawings]

FIG. 1 is a perspective view of the periphery of an ink ribbon drive device embodying the present invention. FIG. 2 is a partial perspective view of the ink ribbon feeding drive means embodying the present invention, and FIG. 3 is a partial sectional view taken along the line AB in FIG. 2 embodying the present invention.

Claims (1)

[Claims] 1. A timing pulley 6, 7 and a timing pulley 6, 7 driven by forward and reverse rotations of a carriage motor 8.
Between the timing belt 5 and the carriage 1 having the print head 4 which reciprocates left and right by engaging the timing belt 5 and the timing belt 5, one of the timing pulleys 6 and 7, and the ink ribbon drive shaft 13a. And an ink ribbon drive shaft 13 which is disposed between the two and is connected by a gear to feed the ink ribbon drive shaft in the same direction.
and a ribbon cassette 17 which is supported by a frame with a ribbon feed roller 18 which engages the a, always in the ink ribbon feeding device for printing on the print medium through the ribbon 19 to Okugyo in a certain direction, the ribbon velocity U _R < The gear ratio of the gears (11c, 12) of the ink ribbon feed drive means is selected so as to satisfy the carriage speed U _C and slow the relative speed of the ribbon when the carriage 1 moves in the anti-ribbon feed direction. Ink ribbon feeder.