JPH08276629A - Pull-up roller assembly - Google Patents

Abstract

PURPOSE: To eliminate fine adjustment of the projection of a rib and to improve line feed accuracy even for a special paper. CONSTITUTION: An assembly has a pull-up roller frame 24, a pull-up roller cover 26 which is attached freely swingably to the frame 24, a roller 25 which is attached freely rotatably to the frame 24 and generates feed force in collaboration with a rib formed on the inner surface of the cover 26, and a gap adjustment means for adjusting the gap between the rib and the roller 25. Since constant feed force can be generated for paper 18 with optional thickness, troubles can be prevented, including clogging of a line feed pitch for thin paper, elongation of the line feed pitch for thick paper, press trace for copying paper, and hole deformations for continuous paper.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to pull-up roller assemblies.

[0002]

2. Description of the Related Art Conventionally, in a serial printer, a pull-up roller assembly is arranged above a platen so that the fed paper can be conveyed. FIG. 2 is a front view of a paper transport unit in a conventional serial printer, FIG. 3 is a sectional view of the paper transport unit in the conventional serial printer, FIG. 4 is a plan view of a pull-up roller assembly in the conventional serial printer, and FIG. Of the pull-up roller assembly in the serial printer of FIG. 6, FIG. 6 is a sectional view taken along line XX of FIG. 4, and FIG. 7 is a sectional view taken along line YY of FIG.

As shown in the drawing, the platen 11 is supported by the left and right walls of the main chassis 12 in FIG. 2, and the rotation from the line feed motor 13 meshes with the gear G1 and the gear G1. It is transmitted to the platen 11 via the gear G2. The front pressure roller 14 and the rear pressure roller 15 are rotatably arranged on the paper pan 17 so as to face the platen 11, and when the top paper route (single sheet) is selected and the rear paper route (continuous paper) is selected. The sheet 18 that is pressed against the platen 11 by the urging force of a spring (not shown) and is sandwiched between the sheet 18 and the platen 11 is conveyed by rotational friction.

The carriage 20 has a print head 2
1 and a ribbon protector 19 are mounted on the platen 11
Is opposed to. Then, by driving a spacing motor (not shown), the print head 21 can be moved left and right in FIG. 2 along the shaft 22 to perform printing. The ribbon protector 19 also moves together with the print head 21 to prevent the paper 18 from floating during printing.

Above the platen 11, 1
A roller pull-up roller assembly is provided. The pull-up roller assembly is usually a pull-up roller frame 24 fixed to the platen 11 and the main chassis 12, a roller 25 for feeding the paper 18, a rib for guiding the paper 18 and generating a feed force. Reference numeral 27 denotes a pull-up roller cover 26 formed on the inner surface, a gear G3 fixed to the shaft of the roller 25, and a gear G4 meshing with the gear G3 to adjust the gear ratio.

The pull-up roller cover 26, the roller 25, and the gears G3 and G4 are attached to the pull-up roller frame 24 to form a pull-up roller assembly, and are attached to the printer main body (platen 11 and main chassis 12). It Then, when the platen 11 is rotated, the gear G5 fixed to the platen 11 is rotated, and the gear G that meshes with the gear G5.
4 is rotated and gear G3 meshes with gear G4.
Is rotated. As a result, the rotation of the platen 11 is accelerated and transmitted to the roller 25.

Next, the operation of the pull-up roller assembly having the above construction will be described. First, the paper 18 is set on the top paper route, the rear paper route, or the bottom paper route, and when the suction signal is sent to the motor driver from the control unit (not shown), the line feed motor 1
3 is driven and the platen 11 is rotated. As a result, the rotation is transmitted to the roller 25 via the gears G3 to G5, and the paper 18 is set at the printing position.

Further, the paper 18 is set at the printing position,
When a print signal or a line feed signal is sent from the control unit to the motor driver, the line feed motor 13 is driven, the platen 11 is rotated by a fixed amount to perform a line feed operation, and the sheet 18 is conveyed. The paper 18 is conveyed in the direction of arrow A shown in FIG. 3 for the top paper route, in the direction of arrow B shown in FIG. 3 for the rear paper route, and in the direction of arrow C shown in FIG. 3 for the bottom paper route. It
Further, a tractor 51 for feeding continuous paper is arranged on the rear paper route.

When the leading edge of the sheet 18 reaches the gap g between the roller 25 and the rib 27 of the pull-up roller cover 26 as the platen 11 is moved, the sheet 18 is rotated at an increased speed. It is transported while being pulled by. Here, in order to generate the feed force by the pull-up roller assembly, as shown in FIG. 5, a portion where the rib 27 of the pull-up roller cover 26 and the roller 25 are overlapped is provided, and the rib 27 is used. Since it is necessary to reversely warp the paper 18 and strengthen the waist due to the frictional resistance and the rotational friction of the roller 25, the rib 27 at a portion of the roller 25 is made to protrude shortly so that the rib is provided between the roller 25 and the rib 27. A gap 27 is formed and a rib 27 is provided at a place where the roller 25 is not provided.
Is extended so that the roller 25 and the rib 27 overlap each other as shown in FIG.

Therefore, in order to generate an arbitrary feed force, it is important to set the gap g. Therefore, the pull-up roller cover 26 is attached to the pull-up roller frame 24 at the fulcrums P1 and P2,
Positioning is performed. In this case, the pull-up roller cover 26 does not move from the fixed position, so that the claw 1
The fulcrum P2 is fixed by 0.

[0011]

However, in the above-mentioned conventional pull-up roller assembly, the paper 1 is used.
Since the paper 18 is conveyed in a state in which 8 is warped backwards and the waist is strengthened, in order to generate an appropriate feed force, the rib 27 is projected at the stage of mold manufacturing of the pull-up roller cover 26. The amount needs to be fine-tuned.

Further, when a special paper 18 such as thin paper, thick paper, copy paper, etc. is used, an appropriate feed force cannot be generated, so that the line feed accuracy deteriorates. When the pull-up roller cover 26 is warped, the gap g changes. For example, when the gap g becomes narrower, the second and subsequent sheets 18 of the copy sheet are
Ribs 27 and the like may cause indentations, and in continuous paper, the feed force becomes too strong and the paper 18 is conveyed more than necessary, and sprocket of the tractor 51 causes hole scraping (deformation of holes). Resulting in.

On the other hand, when the gap g becomes wider,
The feed force becomes too weak and the line feed accuracy decreases. The present invention solves the problems of the conventional pull-up roller assembly described above, and it is not necessary to finely adjust the protrusion amount of the rib in the mold manufacturing stage of the pull-up roller cover, and even when a special paper is used, a line feed is performed. An object of the present invention is to provide a pull-up roller assembly capable of improving accuracy and easily adjusting the gap between the roller and the rib.

[0014]

Therefore, in the pull-up roller assembly of the present invention, a pull-up roller frame, a pull-up roller cover swingably arranged on the pull-up roller frame, and the pull-up roller cover are provided. A roller that is rotatably disposed on the up roller frame and that generates a feed force together with a rib formed on the inner surface of the pull-up roller cover, and a gap adjusting unit that adjusts a gap between the rib and the roller. .

[0015]

According to the present invention, as described above, in the pull-up roller assembly, the pull-up roller frame, the pull-up roller cover swingably disposed on the pull-up roller frame, and the pull-up roller. The frame has a roller that is rotatably arranged and that generates a feed force together with a rib formed on the inner surface of the pull-up roller cover, and a gap adjusting unit that adjusts a gap between the rib and the roller.

In this case, when the roller is rotated, a feeding force is generated by the rib and the roller, and the sheet is conveyed by the feeding force. Then, the gap adjusting means can easily narrow or widen the gap.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a first state diagram of a pull-up roller assembly according to the first embodiment of the present invention,
8 is a right side view of the pull-up roller assembly according to the first embodiment of the present invention, FIG. 9 is a left side view of the pull-up roller assembly according to the first embodiment of the present invention, and FIG. 10 is a first side view of the present invention. 2 is a second state diagram of the pull-up roller assembly in the above embodiment, FIG. 11 is an explanatory diagram of a gap in the first embodiment of the present invention, and FIG. 12 is a paper thickness and paper stiffness in the first embodiment of the present invention. Relationship with the strength of
FIG. 13 is a relationship diagram between the gap displacement and the stiffness of the paper in the first embodiment of the invention, FIG. 14 is a relationship diagram between the paper thickness and the feed force in the first embodiment of the invention, and FIG. FIG. 16 is a comparative diagram showing the relationship between the gap and the feed force of the conventional pull-up roller assembly, and FIG. 16 is a diagram showing the relationship between the gap and the feed force in the first embodiment of the present invention.
In FIG. 12, the horizontal axis represents the paper thickness and the vertical axis represents the paper 17.
15, the horizontal axis represents the gap displacement, the vertical axis represents the waist strength of the paper 17, the horizontal axis represents the paper thickness, and the vertical axis represents the feed force in FIG. 16 and 16, the horizontal axis represents the gap d and the vertical axis represents the feed force.

The one-roller type pull-up roller assembly is generally a pull-up roller frame 24 fixed to the platen 11 and the main chassis 12 (see FIG. 2) and a roller for feeding the paper 18 as shown in the figure. 25, a pull-up roller cover 26 having an inner surface formed with ribs 27 (see FIG. 4) for guiding the paper 18 and generating a feed force, a gear G3 fixed to a shaft (not shown) of the roller 25, and The gear G3
And a gear G4 for adjusting the gear ratio.

The pull-up roller cover 26, the roller 25, and the gears G3 and G4 are attached to the pull-up roller frame 24 to form a pull-up roller assembly, and are attached to the printer main body (platen 11 and main chassis 12). It Then, when the platen 11 is rotated, the gear G5 fixed to the platen 11 is rotated, and the gear G that meshes with the gear G5.
4 is rotated, and further the gear G3 meshing with the gear G4 is rotated. As a result, the rotation of the platen 11 is accelerated and transmitted to the roller 25.

Post fulcrums P4 are formed on both side surfaces of the pull-up roller cover 26 so as to project therefrom, while the pull-up roller frame 24 projects toward the pull-up roller cover 26 and has a support portion 24a and a claw. 28 is formed. Further, the support portion 24a and the claw 28 extend substantially parallel to each other, and a groove 29 having one end opened is formed between them, and the claw 28 is biased by the groove 29 and the post fulcrum P4 is held. It has become so.

The claw 28 has a base 28a and the base 2
8a, the tip portion 28b is formed at the tip of the tip portion 8a, and the tip portion 28b is slightly inclined toward the support portion 24a. On the other hand, a stopper 30 is formed in the supporting portion 24a by a stepped portion, and the width of the groove 29 on the opening side of the stopper 30 is wider and the width of the inner side of the stopper 30 is narrower.

Then, the pull-up roller cover 26
When is set, the post fulcrum P4 is pushed deeply into the groove 29 by the spring force of the claw 28 and abuts on the stopper 30. The position where the post fulcrum P4 contacts the stopper 30 is set as a reference position, and the pull-up roller cover 26 is positioned at the reference position.

Then, when the sheet 18 passes through the gap g,
Paper 18 including roller 25 and pull-up roller cover 26
The post fulcrum P4 moves in the groove 29 according to the thickness of the
Swing about 3. Next, the operation of the pull-up roller assembly having the above structure will be described. First, the paper 18 is set on the top paper route, the rear paper route, or the bottom paper route, and when a suction signal is sent from the control unit (not shown) to the motor driver, the line feed motor 13 is driven and the platen 11 is rotated. . As a result, the rotation is transmitted to the roller 25 via the gears G3 to G5, and the paper 18 is set at the printing position.

When the paper 18 is set at the print position and a print signal or a line feed signal is sent from the controller to the motor driver, the line feed motor 1
3 is driven, the platen 11 is rotated by a fixed amount to perform a line feed operation, and the sheet 18 is conveyed. When the leading edge of the paper 18 reaches the gap g, the paper 18 is conveyed while being pulled by the roller 25 that is rotated at an increased speed.

By the way, when the pull-up roller cover 26 is fixed to the pull-up roller frame 24, if the paper 18 is standard paper (standard paper thickness), the paper 18 can be conveyed normally. However, when the paper 18 is a thin paper, the gap g is apparently widened, so that the line feed pitch clogging occurs, and when the paper 18 is a thick paper, a copy paper, a continuous paper, etc. In addition, since the gap g is apparently narrowed, line feed pitch elongation, indentation, hole scraping, etc. occur.

However, in the present embodiment, the post fulcrum P4 can move in the groove 29. Therefore, when thin paper is used for the paper 18, the post fulcrum P4 is set to the inner side of the groove 29. The spring force of the pawl 28 to be moved becomes larger than the force to widen the gap g due to the strength of the waist of the paper 18. Therefore, as shown in FIG. 1, the post fulcrum P4 is located at the reference position, and the paper 18 can be conveyed while keeping the gap g constant.

On the other hand, when thick paper is used as the paper 18, the force to widen the gap g due to the stiffness of the paper 18 causes the claw 28 to move the post fulcrum P4 to the inner side of the groove 29. Greater than spring force. Therefore, as shown in FIG. 10, the post fulcrum P4 is the stopper 3
It moves away from 0 in the groove 29 in the direction of arrow D, that is, toward the opening side. At this time, the claw 28 is pushed in the direction of arrow E,
The pull-up roller cover 26 rotates about the post fulcrum P3 in the directions of arrows F and G. Then, the force to widen the gap g due to the strength of the waist of the paper 18 and the claw 2 to move the post fulcrum P4 to the inner side of the groove 29.
The paper 18 can be conveyed while maintaining the gap g as shown in FIG.

Further, without increasing the number of parts of the pull-up roller assembly, the paper 18 of any paper thickness can be obtained.
Since a constant feed force can be generated against, line feed pitch clogging when using thin paper, line feed pitch extension when using thick paper,
It is possible to prevent the occurrence of indentations when using copy paper and hole scraping when using continuous paper.

Therefore, the line feed accuracy can be improved. Further, it is not necessary to finely adjust the protrusion amount of the rib 27 at the stage of manufacturing the mold of the pull-up roller cover 26. By the way, the thickness of the paper 18 and the strength of the waist are shown in FIG.
When the paper thickness increases, the paper 18
The waist strength also increases. Also, gap displacement and paper 1
It has been experimentally known that there is a relationship as shown in FIG. 13 with the waist strength of No. 8, and when the gap displacement is large, the waist strength of the paper sheet 18 becomes large.

Therefore, if the spring force of the claw 28 and the inclination angle and shape of the tip end portion 28b are determined based on the paper thickness, the stiffness of the paper 18 and the gap displacement, a constant feed force is obtained regardless of the paper thickness. Can be generated. That is, in FIG. 14, L1 is a line indicating the feed force generated by the conventional pull-up roller assembly,
L2 is a line indicating the feed force generated by the pull-up roller assembly in this embodiment.

Looking at the feed force generated by the conventional pull-up roller assembly, when the paper thickness of the paper 18 is smaller than the standard paper thickness, the feed force becomes smaller than the design value, and the paper thickness is the standard paper. When the thickness is larger than the thickness, the feed force becomes larger than the design value. However, looking at the feed force generated by the pull-up roller assembly of this embodiment, the feed force is the design value even if the paper thickness of the paper 18 varies. Can be maintained at.

In FIG. 15, L3 is a line showing the feed force when thick paper is used as the paper 18 in the conventional pull-up roller assembly, and L4 is standard paper as the paper 18 in the conventional pull-up roller assembly. L5 is a line showing the feed force at this time, and L5 is a line showing the feed force when thin paper is used as the paper 18 in the conventional pull-up roller assembly.

As described above, in the conventional pull-up roller assembly, the variation AR2 in the feed force corresponding to the tolerance region AR1 of the gap g based on the warp of the pull-up roller cover 26 is large. On the other hand, in FIG. 16, L6 is a line indicating the feed force when the paper 18 is used in the pull-up roller assembly of this embodiment. In this case, no matter whether thick paper, standard paper or thin paper is used as the paper 18, the pull-up roller cover 2
The variation AR3 of the feed force corresponding to the tolerance region AR1 of the gap g based on the warp of 6 becomes small.

Therefore, it is possible to improve the line feed accuracy, relax the dimensional control for the warp of the pull-up roller cover 26, and reduce the cost. Next, a second embodiment of the present invention will be described. 17 is a first state diagram of the pull-up roller assembly according to the second embodiment of the present invention, and FIG. 18 is a second state diagram of the pull-up roller assembly according to the second embodiment of the present invention. It should be noted that members having the same structure as in the first embodiment are given the same reference numerals and the description thereof is omitted.

In this case, the post fulcrum P4 is formed so as to project on both side surfaces of the pull-up roller cover 26, while
The pull-up roller frame 24 is provided with a support portion 24a and a claw 33 that project toward the pull-up roller cover 26. Then, the support portion 24a and the claw 33
And a groove 65 having one end open at both ends is formed so as to hold the post fulcrum P4.

A stopper 30 is formed on the supporting portion 24a by a stepped portion, and the width of the groove 65 on the opening side of the stopper 30 is wider and the width on the inner side of the stopper 30 is narrower. A mounting portion 33a is formed at the tip of the claw 33 so as to project toward the opening of the groove 65, and the coil spring 35 is detachably disposed between the mounting portion 33a and the post fulcrum P4. The coil spring 35 urges the post fulcrum P4 toward the inner side of the groove 65.

Then, the pull-up roller cover 26
Is set, the post fulcrum P4 is pushed deeply into the groove 65 by the spring force of the coil spring 35,
Contact the stopper 30. The position where the post fulcrum P4 contacts the stopper 30 is set as a reference position, and the pull-up roller cover 26 is positioned at the reference position.

Then, when the sheet 18 passes through the gap g,
Corresponding to the thickness of the paper 18, the post fulcrum P4 has a groove 6
5, the pull-up roller cover 26 swings around the post fulcrum P3. In the pull-up roller assembly having the above structure, when thin paper is used as the paper 18, the spring force of the coil spring 35 that tries to move the post fulcrum P4 to the inner side of the groove 65 depends on the stiffness of the paper 18. It becomes larger than the force to widen the gap g.

Therefore, as shown in FIG. 17, the post fulcrum P4 is placed at the reference position, and the paper 18 can be conveyed while keeping the gap g constant. On the other hand, when thick paper is used as the paper 18,
The force to widen the gap g due to the strength of the waist is larger than the spring force of the coil spring 35 to move the post fulcrum P4 to the inner side of the groove 65.

Therefore, as shown in FIG. 18, the post fulcrum P4 moves away from the stopper 30 and moves in the groove 65 in the direction of arrow D, that is, toward the opening side. At this time, the pull-up roller cover 26 rotates in the directions of arrows F and G around the post fulcrum P3. Then, at a position where the force for widening the gap g due to the strength of the waist of the sheet 18 and the spring force of the coil spring 35 for moving the post fulcrum P4 to the inner side of the groove 65 are balanced, the gap g The paper 18 can be conveyed while maintaining the above.

In this case, not only the qualitative characteristics can be easily changed by replacing the coil spring 35, but also when the coil spring 35 is worn or the coil spring 35 is depressed, By replacing the coil spring 35,
The feed force can be generated again. Next, a third embodiment will be described in which the gap g can be manually changed depending on the paper thickness.

FIG. 19 is a first state diagram of the pull-up roller assembly according to the third embodiment of the present invention, and FIG. 20 is a second state diagram of the pull-up roller assembly according to the third embodiment of the present invention. 21 is a relationship diagram between the paper thickness and the feed force in the third embodiment of the present invention, and FIG. 22 is a relationship diagram between the gap and the feed force in the third embodiment of the present invention. 21, the horizontal axis represents the paper thickness, the vertical axis represents the feed force, and the horizontal axis represents the gap g in FIG.
Is plotted on the vertical axis.

The members having the same structure as in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this case, the pull-up roller cover 26
The post fulcrum P4 is formed so as to project to both side surfaces of the post, while the two claws 38 are formed on the pull-up roller frame 24 so as to project toward the pull-up roller cover 26. Then, the claws 38 extend substantially parallel to each other, a groove 67 having one end opened is formed between the claws 38, and the post fulcrum P4 is held at an arbitrary plurality of positions of the groove 67.

Therefore, a stopper 30 is formed by a stepped portion on the surfaces of the claws 38 facing each other, and the width of the groove 67 on the opening side of the stopper 30 is wider and on the back side of the stopper 30. Is narrowed. In addition, a plurality of stages of post accommodating receivers 38a are formed facing each other on the tip side of the stopper 30 of each claw 38.
4 can be held. In this embodiment, three stages of post housing receivers 38a are formed.

Then, the pull-up roller cover 26
And the operator pulls up the pull-up roller cover 26
Is pressed against the pull-up roller frame 24, the post fulcrum P4 is pushed deep into the groove 67, and the stopper 30
Abut. The post fulcrum P4 is the stopper 30.
Is set to a reference position, and the pull-up roller cover 26 is positioned at the reference position.

The gap g can be changed by holding the post fulcrum P4 in any one of a plurality of stages of the post accommodating receivers 38a corresponding to the thickness of the paper 18. When thin paper is used as the paper 18 in the pull-up roller assembly configured as described above, the post fulcrum P4 is placed at the reference position and the paper 18 is conveyed while keeping the gap g constant, as shown in FIG. be able to.

On the other hand, when thick paper is used as the paper 18, as shown in FIG. 20, the post fulcrum P4 is moved in the direction of the arrow D, that is, toward the opening side, and selected from the post accommodating receivers 38a of a plurality of stages. Hold by something.
At this time, the pull-up roller cover 26 has the post fulcrum P.
It rotates in the directions of arrows F and G about 3. Then, the paper 18 can be conveyed while maintaining the gap g.

Therefore, a substantially constant feed force can be generated regardless of the paper thickness. That is, FIG.
In the above, L7 is a line showing the feed force generated by the conventional pull-up roller assembly, and L8 is a line showing the feed force generated by the pull-up roller assembly in this embodiment.

In the conventional pull-up roller assembly, the feed force becomes smaller than the designed value when the paper thickness is smaller than the standard paper thickness, and the feed force becomes the designed value when the paper thickness is larger than the standard paper thickness. Although larger, the pull-up roller assembly of the present embodiment can maintain the feed force at the designed value even if the paper thickness varies.

In FIG. 22, L9 is the first line showing the feed force when the paper 18 is used in the pull-up roller assembly of this embodiment, and L10 is the paper 18 in the pull-up roller assembly of this embodiment. It is a 2nd line which shows the feed force at the time of using. In this case, since the post fulcrum P4 cannot be continuously moved within the groove 67, the feed force is the first line L9.
And the second line L10. Therefore, paper 1
Whether the sheet 8 is thick paper, standard paper or thin paper, the variation AR4 in the feed force corresponding to the tolerance region AR1 of the gap g based on the warp of the pull-up roller cover 26 is small.

Therefore, the line feed accuracy can be improved and the dimensional control for the warp of the pull-up roller cover 26 can be eased. Further, since a plurality of stages of post accommodating receivers 38a are formed, and the post supporting points P4 are held by the respective post accommodating receivers 38a, there is no change in the relationship between the gap displacement and the feed force, and the feed force is not changed. The characteristics are stable.

Next, a fourth embodiment of the present invention will be described. 23 is a sectional view of a pull-up roller assembly according to a fourth embodiment of the present invention, and FIG. 24 is a fourth embodiment of the present invention.
Of the pull-up roller assembly in the above embodiment
FIG. 25 is a second state diagram of the pull-up roller assembly according to the fourth embodiment of the present invention. Regarding the member having the same structure as the first embodiment,
The description will be omitted by giving the same reference numerals.

In this case, the post fulcrum P4 is formed so as to project from both side surfaces of the pull-up roller cover 26, and the cam post 47 is rotatably disposed so as to be eccentric with respect to the post fulcrum P4. On the other hand, pull-up roller frame 2
4, a support portion 24a and a claw 48 are formed so as to project toward the pull-up roller cover 26. And
The groove 7 having one end opened between the support portion 24a and the claw 48.
0 is formed.

A stopper 30 is formed by a stepped portion on the surfaces of the support portion 24a and the claw 48 which face each other, and a post accommodating receiver for accommodating the cam post 47 on the opening side of the groove 70 in the groove 70. 69
Is formed. In this case, the width of the groove 70 on the inner side of the stopper 30 is narrowed. Then, when the pull-up roller cover 26 is set, the cam post 47 is pushed into the post housing receiver 69 and abuts on the stopper 30. When the cam post 47 is rotated about the post fulcrum P4, the stopper 3 is rotated.
The distance between 0 and the cam post 47 changes. As a result, the pull-up roller cover 26 is swung about the post fulcrum P3.

When thin paper is used as the paper 18 in the pull-up roller assembly having the above-mentioned structure, FIG.
4, the cam post 47 is rotated so that the center of the cam post 47 is located above the post fulcrum P4. At this time, the position of the cam post 47 is set as a reference position. Therefore, the paper 18 can be conveyed while keeping the gap g constant.

On the other hand, when thick paper is used as the paper 18, as shown in FIG.
The cam post 47 is rotated in the direction to place the center of the cam post 47 below the post fulcrum P4. At this time, the pull-up roller cover 26 rotates in the directions of arrows F and G around the post fulcrum P3. Then, the paper 18 can be conveyed while maintaining the gap g.

Therefore, it is possible to generate a substantially constant feed force regardless of the paper thickness. In this way, when the thickness of the paper 18 changes, the cam post 47 can be rotated in accordance with the paper thickness to adjust the gap g. Further, since the post accommodating receiver 69 is formed and the post accommodating receiver 69 holds the post fulcrum P4 via the cam post 47, the relationship between the gap displacement and the feed force does not change, and the feed force does not change. The characteristics of are stable.

A scale display for indicating the reference position is provided on the claw 48, while an eccentric hole is provided at a position in the circumferential direction of the cam post 47 where the gap g has an appropriate value corresponding to the paper thickness. It is also possible to provide a graduation display of the rotating angle. It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0059]

As described above in detail, according to the present invention, in the pull-up roller assembly, the pull-up roller frame and the pull-up roller cover swingably arranged on the pull-up roller frame. A roller that is rotatably disposed on the pull-up roller frame and that generates a feed force together with a rib formed on the inner surface of the pull-up roller cover; and a gap adjusting unit that adjusts a gap between the rib and the roller. Have and.

Therefore, it is possible to generate a constant feed force for sheets of any thickness without increasing the number of parts. Therefore, the line feed pitch is clogged when thin paper is used, and when thick paper is used. It is possible to prevent line feed pitch expansion, indentation when using copy paper, and hole scraping when using continuous paper.

As a result, the line feed accuracy can be improved. Further, since the gap can be freely changed, it is possible to relax the dimensional control for the warp of the pull-up roller cover. Therefore, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a first state diagram of a pull-up roller assembly according to a first embodiment of the present invention.

FIG. 2 is a front view of a paper transport unit in a conventional serial printer.

FIG. 3 is a cross-sectional view of a paper transport unit in a conventional serial printer.

FIG. 4 is a plan view of a pull-up roller assembly in a conventional serial printer.

FIG. 5 is a diagram illustrating a sheet conveyance state of a pull-up roller assembly in a conventional serial printer.

6 is a sectional view taken along line XX of FIG.

7 is a sectional view taken along line YY of FIG.

FIG. 8 is a right side view of the pull-up roller assembly according to the first embodiment of the present invention.

FIG. 9 is a left side view of the pull-up roller assembly according to the first embodiment of the present invention.

FIG. 10 is a second state diagram of the pull-up roller assembly according to the first embodiment of the present invention.

FIG. 11 is an explanatory diagram of a gap according to the first embodiment of this invention.

FIG. 12 is a relationship diagram between the paper thickness and the stiffness of the paper in the first embodiment of the present invention.

FIG. 13 is a relationship diagram between the gap displacement and the waist strength of the sheet in the first embodiment of the invention.

FIG. 14 is a relationship diagram between the paper thickness and the feed force in the first embodiment of the present invention.

FIG. 15 is a comparative diagram showing the relationship between the gap and the feed force of the conventional pull-up roller assembly.

FIG. 16 is a relationship diagram between the gap and the feed force in the first embodiment of the present invention.

FIG. 17 is a first state diagram of the pull-up roller assembly according to the second embodiment of the present invention.

FIG. 18 is a second state diagram of the pull-up roller assembly according to the second embodiment of the present invention.

FIG. 19 is a first state diagram of the pull-up roller assembly according to the third embodiment of the present invention.

FIG. 20 is a second state diagram of the pull-up roller assembly according to the third embodiment of the present invention.

FIG. 21 is a diagram showing the relationship between the paper thickness and the feed force in the third embodiment of the present invention.

FIG. 22 is a relationship diagram between the gap and the feed force in the third embodiment of the present invention.

FIG. 23 is a sectional view of a pull-up roller assembly according to the fourth embodiment of the present invention.

FIG. 24 is a first state diagram of the pull-up roller assembly according to the fourth embodiment of the present invention.

FIG. 25 is a second state diagram of the pull-up roller assembly according to the fourth embodiment of the present invention.

[Explanation of symbols]

 24 Pull-up roller frame 25 Roller 26 Pull-up roller cover 28, 33, 48 Claw 29, 65, 67, 70 Groove 35 Coil spring 38a, 69 Post housing receiver 47 Cam post P3, P4 Post fulcrum g Gap

Claims (7)

[Claims] 1. A pull-up roller frame comprising:
(B) A pull-up roller cover that is swingably disposed on the pull-up roller frame, and (c) is rotatably disposed on the pull-up roller frame, and is formed on the inner surface of the pull-up roller cover. A pull-up roller assembly comprising: a roller that generates a feed force together with the rib; and (d) a gap adjusting unit that adjusts a gap between the rib and the roller. 2. The pull-up roller assembly according to claim 1, wherein the gap adjusting means adjusts the gap according to the paper thickness. 3. The gap adjusting means is formed on one of the pull-up roller frame and the pull-up roller cover, and on the other of the pull-up roller frame and the pull-up roller cover. 2. The pull-up roller assembly according to claim 1, comprising a groove that slidably supports and a biasing unit that biases the post fulcrum in the groove in a direction in which the gap becomes smaller. 4. The pull-up roller assembly according to claim 3, wherein the urging means is a claw that forms the groove. 5. The pull-up roller assembly according to claim 3, wherein the urging means is a coil spring arranged between the claw forming the groove and the post fulcrum. 6. (a) The gap adjusting means includes a post fulcrum formed on one of the pull-up roller frame and the pull-up roller cover, and a groove formed on the other of the pull-up roller frame and the pull-up roller cover. 2. The pull-up roller assembly according to claim 1, further comprising: (b) a plurality of post accommodating receivers for holding the post fulcrums formed in the groove. 7. (a) The gap adjusting means includes a post fulcrum formed on one of the pull-up roller frame and the pull-up roller cover, and a cam post rotatably arranged around the post fulcrum. A pull-up roller frame and a groove formed on the other side of the pull-up roller cover, and (b) a post accommodating receiver that rotatably receives the cam post is formed in the groove.
The pull-up roller assembly described in.