JP2963616B2 - Printing equipment ribbon drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ribbon driving device for a printing apparatus which drives an ink ribbon in one direction by using a reciprocating motion of a carriage on which a print head is mounted as a driving source.

[0002]

2. Description of the Related Art In a printing apparatus using a ribbon cassette, there is a ribbon driving apparatus that drives an ink ribbon in one direction by using a reciprocating motion of a carriage on which a print head is mounted as a driving source. One example is shown in FIGS. A carriage 4 is held on a carriage shaft 3 laid on the opposed frames 1 and 2 so as to be able to reciprocate. A dot printer head 6, which is a print head facing the platen 5, is mounted on the carriage 4.
A ribbon cassette 7 is detachably mounted. Also,
A belt 8 partially fixed to the carriage 4 is wound around a plurality of pulleys 9, and one of these pulleys 9 is driven by a motor (not shown) capable of rotating forward and reverse, thereby driving the carriage 4 back and forth. A carriage driving mechanism 10 is provided.

[0003] At both ends of the carriage shaft 3, deformed shafts (not shown) fitted to the eccentric bushes 11 and 12 rotatably held on the frames 1 and 2 while being prevented from rotating are formed. The one eccentric bush 12 is connected to a motor 15 via gears 13 and 14. A printing gap adjusting mechanism 16 is formed by the deformed shafts formed at both ends of the carriage shaft 3, the eccentric bushes 11 and 12, the gears 13 and 14, and the motor 15. That is, the print gap drive mechanism 16
The rotation of the motor 15 is transmitted to the eccentric bushes 11, 12 and the carriage shaft 3, and the displacement of the axis of the carriage shaft 3 at this time adjusts the printing gap between the platen 5 and the dot printer head 6. is there. At the time of printing, the reaction force due to the collision between the needle (not shown) of the dot printer head 6 and the platen 5 acts on the carriage 4 regardless of the change of the printing gap.
A plate 17 for receiving a contact portion (not shown) formed at a part of the rear end of the carriage 4 is stretched between the frames 1 and 2.

Further, a left end of the rack 18 is held by the left frame 1 so as to be displaceable in a direction of coming into contact with and separating from the platen 5, and a gap between the right frame 2 and the right end of the rack 18 is provided. A spring 19 is stretched. Also,
The carriage 4 has a ribbon drive shaft 20 for feeding an ink ribbon (not shown) of the ribbon cassette 7 in one direction.
, An input gear 21 meshed with the rack 18, and a gear transmission mechanism 22 that transmits the rotation of the input gear 21 to the ribbon drive shaft 20. Input gear 21 is rack 1
8 has a large-diameter portion 21a and a small-diameter portion 21b. The gear transmission mechanism 22 includes a switching lever 23 whose rotation direction switches on the rotation axis of the input gear 21 in accordance with the rotation direction of the input gear 21, and an input gear rotatably supported at both ends of the switching lever 23. Two planetary gears 24, 25 always meshed with the small diameter portion 21b of 21 and transmission gears 26, 27 meshed with one of the planetary gears 24, 25 according to the rotation direction of the switching lever 23. Is formed. The transmission gears 26 and 27 are meshed with each other, and the transmission gear 27 is formed integrally with the ribbon drive shaft 20.

When the carriage 4 is driven and moved by the carriage driving mechanism 10, the input gear 21 rolling on the rack 18 moves clockwise in accordance with the moving direction of the carriage 4. Alternatively, the switching lever 23 rotates counterclockwise, and the switching lever 23 rotates clockwise or counterclockwise according to the rotation direction of the input gear 21. Thereby, the planetary gear 24 meshes with the transmission gear 26, or the planetary gear 25 meshes with the transmission gear 27. When the planetary gear 24 meshes with the transmission gear 26, an even number of transmission gears 26 and 27 are arranged in a power transmission path from the planetary gear 24 to the ribbon drive shaft 20, and the planetary gear 25 is connected to the transmission gear 27.
When meshing with the ribbon drive shaft 20
An odd number of transmission gears 27 are arranged in the power transmission path leading to. As described above, when the input gear 21 rotates, the power transmission path to the ribbon drive shaft 20 is divided into two systems depending on the direction of rotation, but the number of transmission gears in the transmission path for each system is determined to be odd and even. Therefore, even if the rotation direction of the input gear 21 is switched, the ribbon drive shaft 20 is always driven in a fixed direction.

The ribbon drive shaft 20, the input gear 21, and the gear transmission 22 are mounted on the carriage 4 via a holder 28 shown in FIG.
That is, the holder 28 includes a plurality of locking claws 29 that are locked to the carriage 4, a stud 30 that rotatably holds the input gear 21 and the switching lever 23, and a rotatable transmission gear 26. A stud 31 for holding the
Stud 3 for rotatably holding the ribbon drive shaft 20
2 are integrally formed. Further, a groove (not shown) into which a protruding piece 33 formed at the end of the holder 28 is slidably fitted is formed on the back surface of the rack 18.

As shown in FIG. 3, assuming that the minimum value of the print gap is G1 and the maximum value is G2, the print gap adjustment width (movement width of the carriage 4 in the direction of contact with and separation from the platen 5) G is (G2−G2). G1). In a model in which the type of paper thickness is small, the print gap adjustment width G is 0.1
In many cases, the eccentric bush 11, 1 mm is sufficient.
There is also a model that adopts a structure in which 2 is manually rotated.
In such a model, since the movement width (G) of the carriage 4 is small, the change in the meshing state between the rack 18 and the input gear 21 is small. Therefore, even when the rack 18 is fixedly provided, the rotation can be transmitted to the ribbon drive shaft 20 without any trouble by the combination of the rack 18 with the module m = 1 and the input gear 21.

In a model in which the printing gap is automatically set, the thickness of the paper is detected by a paper sensor (not shown), and the detection signal is used to drive the motor 15 as described above. In such a model, the carriage 4 is temporarily displaced to the home position farthest from the platen 5, and then the carriage 4 is advanced to the platen 5 side according to the thickness of the paper. If the print gap adjustment width G (G2-
G1) is required to be about 2.5 to 3 mm. In this case, the module m between the rack 18 and the input gear 21 becomes large, and when the rack 18 is fixed, when the carriage 4 is advanced most to the platen 5 side, the rack 18 and the input gear 2
3 and 4 in order to increase the backlash between them and hinder the power transmission to the ribbon drive shaft 20.
As shown in FIG. 3, the rack 18 is supported to be elastically displaced in the
By fitting the projection 33 of the holder 28 fixed to the groove in the back surface of the rack 18, even if the carriage 4 is displaced in the direction of coming and going with respect to the platen 5 by adjusting the print gap, the carriage 4 and the rack 18 The relative position does not change.

As described above, even if the carriage 4 is displaced in the direction of contact or separation with respect to the platen 5 by adjusting the printing gap, the conventional example shown in FIG. is there. Hereinafter, the conventional example will be described. 3 and 4 are denoted by the same reference numerals, and description thereof is omitted. In this example, the input gear 34 meshed with the planetary gears 24 and 25 is used.
And a pulley 35 are integrally formed and rotatably provided on the carriage 4, and both ends of a rope 36 wound around the pulley 35 are fixed to the left and right frames 1 and 2.

In such a structure, the pulley 35 and the input gear 34 are rotated by reciprocatingly driving the carriage 4 by the carriage driving mechanism 10, and the input gear 34
Is transmitted to the ribbon drive shaft 20 by the gear transmission mechanism 22. In this case, even if the carriage 4 is displaced in the direction of coming and going with respect to the platen 5 when adjusting the print gap,
Since the rope 36 bends under tension, the pulley 35 and the ribbon drive shaft 20 can be reliably rotated using the reciprocating motion of the carriage 4 as a driving force.

[0011]

As shown in FIG. 5,
The structure in which the input gear 34 and the pulley 35 are rotated by the rope 36 is such that the rope 36 is wound around the pulley 35 in the final assembly process, and then the end of the rope 36 is
In addition, it is difficult to adjust the tension of the rope 36, which increases the manufacturing cost.

FIGS. 3 and 4 show an input gear 21.
The tooth tip of the rack 18 faces the platen 5 side in relation to the direction of the rotation axis. Therefore, in order to reduce the backlash between the input gear 21 and the rack 18 when the carriage 4 is moved toward and away from the platen 5 when adjusting the printing gap, the rack 18 can be elastically displaced independently. Need to support. Accordingly, the rack 18 is formed as a single unit separately from the plate 17 and the frames 1, 2 and the like for supporting the carriage 4 receiving the reaction force from the platen 5 at the time of printing, and parts for supporting the rack 18 are also required. And As a result, there is a problem that the number of parts and the number of assembly steps increase.

[0013]

SUMMARY OF THE INVENTION The present invention provides a carriage driving mechanism for reciprocally driving a carriage holding a print head, a ribbon cassette, and a rotatable ribbon drive shaft for feeding an ink ribbon of the ribbon cassette along a platen. A print gap adjustment mechanism that adjusts a print gap between the print head and the platen by displacing the carriage in the direction of coming and going with respect to the platen,
The carriage is provided with an input gear that rotates with a rotation axis parallel to the rotation axis of the ribbon drive shaft. The input gear is rotatably supported by a switching lever that is displaced in accordance with the rotation direction of the input gear, and is always rotatable by the input gear. At least one meshed planetary gear and a plurality of transmissions arranged in odd or even numbers in a power transmission path divided into two systems to selectively transmit the rotational force of the planetary gear to the ribbon drive shaft. A gear transmission mechanism having gears is provided on the carriage, and a rack having a large number of teeth whose tips are directed in a direction perpendicular to the direction in which the carriage approaches and separates from the platen and the longitudinal direction of the platen is arranged in parallel with the platen. The rack having a tooth width equal to or greater than a value obtained by adding a moving width of the carriage in the direction of contacting and separating from the platen to a thickness of the rack A rotating direction changing gear having a meshed spur gear portion and transmitting reciprocating rotation of the spur gear portion to the input gear is rotatable with respect to the carriage with a rotation axis parallel to a direction in which the carriage approaches and separates from the platen. Is a ribbon driving device of a printing device provided in the printer.

[0014]

When the carriage is moved along the rack, the rotation of the rotation direction changing gear rolling on the rack is transmitted to the ribbon drive shaft via the input gear and the gear transmission mechanism. In this case, the direction of the tip of the teeth of the rack is orthogonal to the direction in which the carriage moves toward and away from the platen and the longitudinal direction of the platen, and the rotation axis of the rotation direction changing gear is parallel to the direction in which the carriage moves toward and away from the platen. Since the tooth width of the spur gear portion of the rotation direction changing gear is set to be equal to or greater than the thickness of the rack plus the width of movement of the carriage in the direction of contact with and separation from the platen, the carriage is moved to the platen in order to change the printing gap. , The meshing state between the spur gear portion of the rotation direction changing gear and the rack can be maintained constant. Thus, even when the print gap adjustment width is large, the rack can be fixedly held.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 3 to 5 are denoted by the same reference numerals, and description thereof is omitted. A rack 37 is fixedly provided in parallel with the platen 5, and the rack 37 has a large number of teeth 38. The carriage 4 is provided with a rotation direction changing gear 39 rotatably. The rotation direction changing gear 39 has a spur gear portion 40 meshed with the rack 37 and a crown gear 41 meshed with the large diameter portion 21a of the input gear 21. Crown gear 4
1 transmits the rotation of the rotation direction changing gear 39 to the large-diameter portion 21a of the input gear 21 by changing the rotation direction to the orthogonal direction, and is used when the large-diameter portion of the input gear 21 is a bevel gear. May use a rotation direction changing gear having a bevel gear that meshes with the bevel gear. When the large diameter portion of the input gear 21 is a face gear, a rotation direction changing gear having a spur gear meshing with the face gear may be used.

The direction of the tip of the teeth 38 of the rack 37 is determined in the direction in which the carriage 4 approaches and separates from the platen 5 and in the direction orthogonal to the longitudinal direction of the platen 5. Platen 5 of carriage 4
And the spur gear portion 40 of the rotation direction changing gear 39 has a tooth width
The tooth width is determined to be greater than or equal to the thickness of the carriage 7 plus the moving width of the carriage 4 in the direction of contact and separation with the platen 5. In other words, by displacing the carriage 4 in the direction of coming and going with respect to the platen 5 for adjusting the printing gap, even if the relative position between the rack 37 and the rotation direction changing gear 39 changes, the meshing state of the two does not change. Has been made.

Next, as shown in FIG. 2, a stud 30 for rotatably holding the input gear 21 and the switching lever 23 and a transmission gear 26 are mounted on a holder 42 mounted on the carriage 4 by a locking claw 29. A stud 31 for rotatably holding, a stud 32 for rotatably holding the ribbon drive shaft 20, and a crown gear 4 of the rotation direction changing gear 39.
A U-shaped notch 43 for rotatably holding the outer peripheral surface of No. 1;
A U-shaped notch 45 for rotatably holding a shaft 44 protruding from one end of the rotation direction changing gear 39 is formed.

In such a configuration, when the carriage 4 is moved along the rack 37 by the carriage driving mechanism 10, the rotation of the rotation direction changing gear 39 rolling on the rack 37 causes the rotation of the crown gear 41 to the input gear 21. Is transmitted to the large diameter portion 21a. The operation of transmitting the rotation of the input gear 21 to the ribbon drive shaft 20 is the same as the operation described in the conventional example. The state shown in FIG. 1 is G1 where the printing gap is the minimum. That is, the carriage 4 is in a state of being closest to the platen 5 side. In this state, the upper part of the spur gear portion 40 of the rotation direction changing gear 39 meshes with the rack 37. In this state, when the carriage 4 is farthest from the platen 5 in order to set the printing gap to the maximum G2, the lower part of the spur gear unit 40 meshes with the rack 37.

As described above, even when the relative position between the rack 37 and the rotation direction changing gear 39 changes by displacing the carriage 4 in the direction of coming and going with respect to the platen 5 for adjusting the printing gap, the spur gear Since the meshing state between the portion 40 and the rack 37 can be kept constant, the rack 37 can be fixedly held even when the print gap adjustment width is large. Thus, as shown in FIG. 3, it is not necessary to use a component for supporting the rack 18 so as to be displaceable by the spring 19 or the like, and the rack 37 can be formed integrally with other components. In this embodiment,
In order to support the carriage 4 which receives a reaction force from the platen 5 during printing, a part 46 of the holder 42 displaced integrally with the carriage 4 may be supported by the rack 37 itself as shown in FIG. In this case, the plate 37a and the rack 37 can be formed integrally to reinforce the rack 37. Of course, the rack 37 can be formed integrally with the left and right frames 1 and 2. By doing so, the number of parts and the number of assembly steps can be reduced.

Further, since the rack 37 in this embodiment is formed by sheet metal working, the cost of the mold can be reduced as compared with a resin molded product. Since the cross section is formed in an L-shape, it is possible to increase rigidity and prevent warpage or the like.

Further, the gear transmission mechanism 22 in the present embodiment
Has been described using two planetary gears 24 and 25 in the same manner as in the prior art, but two power transmission paths from the input gear 21 to the ribbon drive shaft 20 are switched by the displacement of one planetary gear, and Even if the number of transmission gears arranged in the power transmission path is determined to be odd and even for each system,
The ribbon drive shaft 20 can always be driven in only one direction.

[0022]

According to the present invention, when the carriage is moved along the rack, the rotation of the rotation direction changing gear rolling on the rack is transmitted to the ribbon drive shaft via the input gear and the gear transmission mechanism. By doing so, the ink ribbon can be fed in one direction. In this case, the direction of the tip of the teeth of the rack is perpendicular to the direction in which the carriage moves toward and away from the platen and the longitudinal direction of the platen, and the rotation axis of the rotation direction changing gear is rotated. Is parallel to the direction in which the carriage moves toward and away from the platen, and the tooth width of the spur gear portion of the rotation direction changing gear is determined to be equal to or greater than the thickness of the rack plus the width of movement of the carriage in the direction of moving toward and away from the platen. Therefore, even if the carriage is displaced in the direction of coming and going with respect to the platen in order to change the print gap, the engagement between the spur gear portion of the rotation direction changing gear and the rack The ribbon feeding can be performed normally while keeping the state constant, so that the rack can be fixedly held even when the print gap adjustment width is large. There is no need to use components that support displacement.
The rack can be formed integrally with other components, thereby reducing the number of components and the number of assembly steps.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of the present invention.

FIG. 2 is an exploded perspective view of a part thereof.

FIG. 3 is a front view showing an example of the related art.

FIG. 4 is an exploded perspective view of a part thereof.

5A and 5B show another example of the related art, in which FIG. 5A is a plan view showing a state in which an input gear is driven by a rope, and FIG. 5B is a front view showing the entire configuration.

[Explanation of symbols]

 Reference Signs List 4 carriage 5 platen 6 print head 7 ribbon cassette 10 carriage drive mechanism 16 print gap adjustment mechanism 21 input gear 22 gear transmission mechanism 23 switching lever 24, 25 planetary gear 26, 27 transmission gear 37 rack 39 rotation direction changing gear 40 spur gear section

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 23/02 B41J 19/20 B41J 25/308 B41J 33/14

Claims (1)

(57) [Claims] A carriage driving mechanism for reciprocatingly driving a carriage holding a print head, a ribbon cassette, and a rotatable ribbon drive shaft for feeding an ink ribbon of the ribbon cassette along a platen, and attaching the carriage to the platen. A print gap adjusting mechanism that adjusts a print gap between the print head and the platen by displacing the print head in the direction in which the print head and the platen are moved away from each other, and the carriage has a rotation axis parallel to the rotation axis of the ribbon drive shaft. A rotating input gear, at least one planetary gear rotatably supported by a switching lever displaced in accordance with the rotation direction of the input gear and constantly meshed with the input gear; and a power transmission system divided into two systems. Odd or even numbers are arranged in the path to selectively transmit the rotational force of the planetary gear to the ribbon drive shaft. A gear transmission mechanism having a plurality of transmission gears is provided on the carriage, and the rack having a large number of teeth whose teeth are directed in a direction in which the carriage approaches and separates from the platen and a direction perpendicular to the longitudinal direction of the platen is provided on the carriage. And a spur gear portion meshed with the rack having a tooth width equal to or greater than the thickness of the rack plus the width of movement of the carriage in the direction of contact and separation with respect to the platen. A printing method, wherein a rotation direction changing gear for transmitting the reciprocating rotation of the lever gear portion to the input gear is rotatably provided on the carriage with a rotation axis parallel to a direction in which the carriage approaches and separates from the platen. Equipment ribbon drive.