JPH1179461A - Paper feeding mechanism of printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate paper feeding dislocation, and feed paper with high accuracy by uniformly and elastically arranging a small roller on a paper feeding roller in the width direction of a recording paper sheet. SOLUTION: In a paper feeding mechanism 7, a small roller 9 is held in a tip part of a holder 10, and a rotary shaft 9a composed of a metallic bar is arranged in its rotational center. A pair of roller members 9b (which are composed of a material such as rubber and whose external shape is a circular shape) using the rotary shaft 9a as the rotational center are fixed to the rotary shaft 9a. In the rotary shaft 9a, both end parts are formed so as to project outward from the roller members 9b, and the almost central part vicinity of the small roller 9 sandwiched between the roller members 9b is exposed. Both end parts of the rotary shaft 9a are movably held in the direction orthogonal to a paper feeding roller 8, and the rotary shaft 9a in the vicinity of an almost central part of the small roller 9 is elastically energized by the holder 10, and the small roller 9 elastically presses the paper feeding roller 8. Therefore, paper feeding accuracy of a recording paper sheet can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed mechanism for a printer capable of improving the paper feed accuracy of recording paper by uniformly pressing small rollers on the paper feed roller of the printer.

[0002]

2. Description of the Related Art In a paper feed mechanism of a conventional printer, as shown in FIG. 6, a small roller 22 composed of a rotating shaft 22a and a rubber roller 22b is rotatably held on an arm 21a of a holder 21. . The rubber roller 22 b is elastically contacted with the paper feed roller 24 by the action of a spring 23 that elastically urges the holder 21. The holder 21 is attached to a rotatable support shaft 25. Further, the recording paper P transported in the direction of arrow A by the paper transporting means (not shown) provided on the upstream side of the holder 21 is elastically clamped between the paper feed roller 24 and the rubber roller 22b. The paper feed roller 24 is conveyed to a platen (not shown) on the downstream side by the clockwise rotation.

The rubber roller 22b is formed in a slender shape as shown in the front view of FIG. 7, and a rotating shaft 22a protruding from both ends thereof is rotatable in a holding groove 21b formed in the arm 21a of the holder 21. Is held in. The bottom of the holding groove 21b presses both ends of the rotating shaft 22a, and the rubber roller 22b is pressed against the paper feed roller 24.

A printer using the conventional paper feed mechanism having the above-described configuration is widely used as an output device such as a computer or a word processor. Such printers are increasingly required to improve the quality of their printed images, and to meet this demand, it has been essential to improve the paper feed accuracy. In order to improve the paper feeding accuracy, the paper feeding roller 24 is formed of a cylindrical metal rod, and a plurality of projections (not shown) are formed on the surface of the paper feeding roller 24 by pressing or the like. Fine ceramic particles (not shown) are fixed to the surface of the feed roller 24 with an adhesive or the like, and the small roller 22 is elastically urged to the paper feed roller 24 to grip the recording paper P against the paper feed roller 24. Printers with improved image quality have been proposed. By using such a paper feed roller 24, the paper feed accuracy can be improved, and the printing quality can be improved.

[0005]

However, even if the above-described paper feed roller 24 is used, a paper feed deviation may occur near the left and right ends in the width direction of the recording paper P. Print image may not be obtained.
It has been found that the cause is that the small roller 22, which is elastically pressed against the paper feed roller 24 and rotates following the rotation of the paper feed roller 24, is not uniformly pressed against the paper feed roller 24. That is, if the holder 21 has a dimensional variation or a twist due to a variation in processing conditions at the time of the forming process, one of the left and right ends of the elongated rubber roller 22b shown in FIG. It was found that a hitting hit phenomenon occurred. As shown in FIG. 8, such a one-sided contact phenomenon is caused by dimensional variation of the holder 21 and
Alternatively, due to twisting or the like, in an extreme case, the small roller 22 is inclined with respect to the paper feed roller 24,
One side of “b” is strongly pressed by the paper feed roller 24, and a concentrated load is applied to the recording paper P in the strongly pressed portion. In the extreme case, the rubber roller 22b on the other side has a gap with the paper feed roller 24 so that the recording paper P is
May rise from the surface. When the recording paper P is conveyed by rotating the paper feed roller 25 in such a state, there is a problem that the paper feed shift occurs on the left and right sides of the small roller 22.

On the other hand, the recording paper P on which a concentrated load is applied to one side of the rubber roller 22b due to the one-side contact phenomenon of the small roller 22, is formed on the surface of the paper feed roller 24 in order to improve the paper feed accuracy described above. In some cases, there is a problem that a plurality of fine holes are formed by the protrusions or ceramic particles (not shown). Further, the recording paper P on which a concentrated load is applied to one side of the rubber roller 22b may have a streak-like impression at the end of the rubber roller 22b.
Appearance sometimes became poor. According to the present invention, the small roller 2 is attached to the paper feed roller 24 in the width direction of the recording paper P.
2 can evenly contact with each other, eliminate the above-mentioned paper feed deviation, perform high-precision paper feed, and always obtain a stable and high-quality print image. To provide a feed mechanism

[0007]

As a first means for solving the above-mentioned problems, a paper feed mechanism of a printer according to the present invention comprises a rotatable paper feed roller, a small roller for elastically pressing the paper feed roller, and A holder for rotatably holding the small roller, wherein both ends of the small roller are held by the holder so as to be movable in a direction orthogonal to the paper feed roller, and the small roller is an outer small roller. The holder is elastically biased in the vicinity of substantially the center to elastically press the paper feed roller.

Further, as a second means for solving the above-mentioned problem, the small roller is constituted by a rotating shaft and a pair of roller members fixed to the rotating shaft, and the rotating shaft has both ends at the two ends. The rotation shaft is formed so as to protrude outward from the roller member, and the rotation shaft is exposed near a substantially central portion of the small roller sandwiched between the pair of roller members, and both ends of the rotation shaft are orthogonal to the paper feed roller. The small roller is movably held in the holder, and the small roller is configured to elastically urge the rotation shaft near the center of the small roller by the holder.

As a third means for solving the above-mentioned problems, a spring member for elastically urging the small roller toward the paper feed roller is provided on the holder, and both ends of the rotary shaft are provided on the holder. , And a second arm portion that elastically urges the rotation shaft near the center of the small roller.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A paper feed mechanism of a printer according to the present invention will be described with reference to FIGS. First, as shown in the perspective view of the main part of FIG. 5, a flat platen 1 is disposed substantially horizontally inside a main body (not shown) of the thermal transfer printer. A guide shaft 2 is bridged on both sides of a main body case (not shown) of the thermal transfer printer in a direction parallel to the platen 1.

On the upper side facing the platen 1, a thermal head 3 in which a plurality of heating elements (not shown) which can be freely moved toward and away from the platen 1 is arranged.
The carriage 4 is provided so as to be movable along the platen 1. The carriage 4 is provided with a take-up bobbin 4a rotatably driven by a motor or the like (not shown) and a rotatable supply bobbin 4b, each of which extends vertically from the surface of the carriage 4. The thermal head 3 is protected by a head cover 4c protruding from the carriage 4. Also,
A belt 5 for reciprocating the carriage 4 along the platen 1 is wound around a pulley (not shown) on the back surface of the carriage 4. Further, behind the platen 1, a plurality of paper feed mechanisms 7 of the present invention supported by a support shaft 6 are provided. The paper feed mechanism 7 includes a paper feed roller 8
And a small roller 9 and a holder 10 for holding the small roller 9. The holder 10 has a spring member 11 for elastically urging the small roller 9 toward the paper feed roller 8.
Are arranged.

The carriage 4 is provided with a rotatable pipe-shaped lift gear 12 protruding therefrom. Also,
A cassette mounting table 13 movably mounted on the carriage 4 and detachably mounting a ribbon cassette (not shown) is provided, and the lift gear 12 engages with a screw hole 13 a provided in the cassette mounting table 13. When the lift gear 12 is rotated, the cassette mounting table 13 is movable in a direction orthogonal to the moving direction of the carriage 4. The cassette mounting table 13 has a fixed claw 1
3b, 13c, 13d and a movable claw 13e are formed,
Different types of ribbon cassettes can be detached and replaced.

The paper feed mechanism 7 of the printer of the present invention used in the above-described thermal transfer printer will be described in detail. First, as shown in FIG. 1, the paper feed mechanism 7 of the printer according to the present invention comprises a small roller 9 held at the tip end of a holder 10 and a rotating shaft 9 made of a metal rod or the like at the center of rotation.
a is provided. The rotating shaft 9a has a pair of roller members 9b, 9b having the rotating shaft 9a as a center of rotation.
However, it is made of a material such as rubber and has a circular outer shape and is fixed. Both ends of the rotating shaft 9a protrude outward from the pair of roller members 9b, 9b, and the rotating shaft 9a is located near a substantially central portion of the small roller 9 sandwiched between the pair of roller members 9b, 9b. Is exposed. The holder 10 holds both ends of the rotating shaft 9a so as to be movable in a direction orthogonal to the paper feed roller 8, and the small roller 9
The rotation shaft 9a in the vicinity of the substantially central portion is elastically urged by the holder 10 so that the small roller 9 elastically presses the paper feed roller 8.

The holder 10 is made of a resin material or the like, and has a pair of first arm portions 10 for holding both ends of the rotary shaft 9a, as shown in FIG.
a, 10a and a second arm portion 10b which elastically urges a rotating shaft 9a near a substantially central portion of the small roller 9 sandwiched between the pair of first arm portions 10a, 10a. A pair of first arms 10a, 10a is formed with a holding groove 10c, which is vertically long and has an opening on the lower side of the paper feed roller 8 as shown in FIG. This holding groove 10c
The opening side is formed narrower than the shaft diameter of the rotating shaft 9a,
By pushing both ends of the rotating shaft 9a into the opening of the holding groove 10c, the small roller 9 is snap-engaged with the holding groove 10c and held rotatably.
Further, the rotating shaft 9 held in the vertically long holding groove 10c.
Both ends of “a” are freely movable in a direction orthogonal to the paper feed roller 8.

Further, on the tip side of the second arm portion 10b,
As shown in FIG. 3, a substantially U-shaped concave portion 10d is formed in a state where the paper feed roller side 8 at the lower side in the figure is opened. The concave portion 10d is formed to be wider than the diameter of the rotary shaft 9a, and the bottom surface of the concave portion 10d abuts on the rotary shaft 9a where the vicinity of the substantially central portion of the small roller 9 is exposed. It is to be energized. When the small roller 9 presses the paper feed roller 8 by the second arm 10d as shown in FIG.
The bottom surface of the holding groove 10c of the arm portions 10a, 10a and the rotating shaft 9a
A gap having a dimension B is formed at both ends, and both ends of the rotating shaft 9a are held by holding grooves 10c which can freely move in a direction orthogonal to the paper feed roller 8. A pair of support arms 10e and 10e are formed at the base of the holder 10 on the side facing the pair of first arms 10a and 10a, and each of the support arms 10e and 10e has a D-shaped support. A hole 10f is formed. The support hole 10f is inserted into the rotatable support shaft 6 of the thermal transfer printer, and the holder 10 is instructed to be rotatable by the support shaft 6. Further, the spring member 11 is attached to the pin 10g, and the small roller 9 is elastically urged by the second arm portion 10b of the holder 10, and the small roller 9 elastically presses the paper feed roller 8.

The recording paper P sent to the paper feed mechanism 7 of the present invention as described above is fed to the paper feed roller 8 and the small rollers 9.
When the paper feed roller 8 rotates clockwise, it is conveyed to the downstream platen (not shown), and when the paper feed roller 8 rotates counterclockwise, the recording paper P returns to the upstream side. You can do it. Further, both ends of the rotating shaft 9a held in the holding grooves 10c of the pair of first arms 10a are held so as to be movable in the vertical direction, and the small roller 9 is elastic only by the second arm 10c of the holder 10. Since the small roller 9 is urged, the small roller 9 is held by the holder 10 so as to be movable in a seesaw shape with the second arm 10b as a pressing fulcrum. Therefore, even if the holder 10 is twisted or the like at the time of manufacturing, the twist is absorbed by the clearance of the dimension B formed between the rotation shaft 9a and the holding groove 10c, so that the small roller 9 has The pair of roller members 9b, 9b can evenly press the outer peripheral surface of the paper feed roller 8 without any gap without causing any one-sided contact phenomenon.

Although not shown in the drawings as a modification of the present invention, the roller-saving roller 9 is formed by only one roller member 9b without the rotating shaft 9a, and the raw roller 9 comprising the one roller member 9b is formed. The outer peripheral portions of both ends of the small roller 9 are movably held by a holder 10 in a direction orthogonal to the paper feed roller 8, and the vicinity of the substantially central portion of the small roller 9 is slidable by the holder 10, for example, a room ring shape The small roller 9 is elastically urged.
May press the paper feed roller 8. In the embodiments of the present invention, a thermal transfer printer has been described as an example. However, the paper feeding mechanism of the printer of the present invention is not limited to a thermal transfer printer, but may be applied to other printers such as an ink jet printer. Is possible

[0018]

In the paper feed mechanism of the printer according to the present invention, both ends of the small roller are held by the holder so as to be movable in a direction perpendicular to the paper feed roller, and the small roller is moved by the small roller. The holder is elastically urged in the vicinity of the central portion to resiliently press the paper feed roller. Therefore, even if a dimensional variation or twisting occurs in the holder, the small roller is evenly pressed against the paper feed roller. This can prevent the small roller from hitting one side.
Therefore, a high-precision paper feed can be obtained, and a paper feed mechanism of a printer capable of printing high-quality images can be provided.
In addition, since the small rollers are evenly pressed against the paper feed roller, no small roller pressure marks are generated on the recording sheet, and the appearance of the recording sheet after recording is not deteriorated.

Further, in the present invention, the small roller is constituted by a rotating shaft and a pair of roller members fixed to the rotating shaft, and the rotating shaft has both ends protruding outward from the pair of roller members. At the same time, the rotation shaft is exposed near the center of the small roller sandwiched between the pair of roller members, and both ends of the rotation shaft are held by the holder so as to be movable in a direction perpendicular to the paper feed roller. Since the small roller is configured to elastically urge the rotation shaft near the center of the small roller by the holder, the small roller can be evenly pressed against the paper feed roller, and the paper feed deviation can be reduced. Can be prevented.

Further, in the present invention, a spring member for elastically urging the small roller toward the paper feed roller is provided on the holder.
A pair of first arms for holding both ends of the rotating shaft and a second arm for elastically biasing the rotating shaft near the center of the small roller are formed on the holder. Can be held by a pair of first arms so as to be movable in a direction orthogonal to the paper feed roller.
Elastic bias is applied only to the arm. Therefore, to provide a paper feed mechanism of a printer that does not cause a small roller singularity phenomenon, can prevent a fine hole from being formed on a recording sheet, and can print a high-quality image. Can be.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a paper feed mechanism of a printer according to the present invention.

FIG. 2 is a cross-sectional side view of a main part illustrating a first arm of a paper feeding mechanism of the printer of the present invention.

FIG. 3 is a cross-sectional side view of a main part illustrating a second arm of the paper feeding mechanism of the printer according to the invention.

FIG. 4 is a sectional front view of a main part of a paper feeding mechanism of the printer of the present invention.

FIG. 5 is a schematic perspective view of an example in which the paper feeding mechanism of the printer of the present invention is used in a thermal transfer printer.

FIG. 6 is a side view of a paper feed mechanism of a conventional printer.

FIG. 7 is a front view of a main part of a paper feeding mechanism of a conventional printer.

FIG. 8 is a schematic front view illustrating a problem of a paper feeding mechanism of a conventional printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platen 2 Guide shaft 3 Thermal head 4 Carriage 5 Belt 6 Support shaft 7 Paper feed mechanism 8 Paper feed roller 9 Small roller 9a Rotating shaft 9b Roller member 10 Holder 10a 1st arm part 10b 2nd arm part 10c holding groove 10d concave part 10e Support arm 10f Support hole 10g pin 11 Spring member 12 Lift gear 13 Cassette mounting table 13a Screw hole 13b-13d Fixed claw 13e Movable claw

Claims (3)

[Claims] 1. A paper feed roller comprising: a rotatable paper feed roller; a small roller for pressing the paper feed roller; and a holder for rotatably holding the small roller. The holder is movably held in the direction perpendicular to the holder, and the small roller is elastically urged by the holder in the vicinity of a substantially central portion of the small roller to elastically press the paper feed roller. Paper feed mechanism of the printer. 2. The small roller includes a rotating shaft and a pair of roller members fixed to the rotating shaft. The rotating shaft has both ends formed to protrude outward from the pair of roller members. The rotation shaft is exposed near the center of the small roller sandwiched between the pair of roller members, and holds both ends of the rotation shaft in the holder so as to be movable in a direction orthogonal to the paper feed roller. 2. The paper feed mechanism according to claim 1, wherein the roller is configured to elastically bias a rotation shaft near a central portion of the small roller by the holder. 3. A pair of first arms for holding both ends of the rotating shaft on the holder, wherein a spring member for elastically urging the small roller toward the paper feed roller is provided on the holder. 3. A paper feed mechanism for a printer according to claim 1, wherein a second arm portion for elastically biasing the rotation shaft near a substantially central portion of the roller is formed.