JP3352602B2 - Paper feed mechanism - Google Patents

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 used for a printer or the like and suitable for feeding a paper by sandwiching the paper between a paper feed roller and a pressure roller.

[0002]

2. Description of the Related Art One line of recording is performed while a carriage on which a recording head is mounted is moved along a platen, and after this one line of recording is performed, a sheet of paper is conveyed and the next line is recorded. A printer that performs predetermined printing by repeating printing is used as an output device such as a computer or a word processor. Such a printer or the like uses a paper feed mechanism for feeding paper.

Next, an example of a printer having a paper feed mechanism will be described with reference to FIG. 5. A platen 2 in the form of a flat plate is disposed at the center of a frame 1 of the printer so that the recording surface thereof is substantially perpendicular. A carriage shaft 3 is disposed below and in front of the platen 2 of the frame 1 in parallel with the platen 2. In addition, the frame 1
A flange-like guide portion 4 is formed on the front edge, and the carriage shaft 3 and the guide portion 4
A carriage 5 is reciprocally mounted along the carriage shaft 3 and the guide portion 4. A thermal head 6 which is opposed to the platen 2 and which can be freely moved toward and away from the platen 2 by a drive mechanism (not shown) is attached to the tip of the carriage 5. A ribbon cassette (not shown) for guiding the ink ribbon between the thermal head 6 and the platen 2 is detachably mounted. Further, on the upper surface of the carriage 5, a take-up bobbin 7 for taking up the ink ribbon of the ribbon cassette and a delivery bobbin 8 on the delivery side are provided.
And are respectively arranged.

A paper insertion slot 9 for inserting a recording paper (not shown) is formed behind the platen 2, and the paper inserted from the paper insertion slot 9 is further inserted into the paper insertion slot 9. A paper feed roller 10 for transporting to the front (recording section) of the platen 2 is provided. This paper feed roller 1
0, a pressure roller 11 that is pressed against the paper feed roller 10 is rotatably disposed. On one side surface of the frame 1, there is provided a paper coaxially mounted with the paper feed roller 10. The feed gear 12 is arranged to protrude.
A motor gear 15 of a paper feed motor 14 is connected to the paper feed gear 12 via a plurality of transmission gears 13.
When the paper feed motor 14 is driven to rotate, the paper feed roller 10 is rotated via the motor gear 15, the transmission gears 13 and the paper feed gear 12, respectively. 11 is conveyed while nipping the sheet inserted between the sheet.

In such a printer, paper is inserted from the paper insertion slot 9, the paper is sandwiched between the paper feed roller 10 and the pressure roller 11, and the paper feed roller 10 is driven by a paper feed motor 14. The carriage 5 is conveyed to a recording start position in a direction orthogonal to the moving direction of the carriage 5 by rotating the carriage 5, and the carriage 5 is pressed against the platen 2 with the thermal head 6 pressed against the platen 2 via the ink ribbon and the paper. The recording element of the thermal head 6 is selectively energized and driven based on the image information while moving along the line 2, and the ink, which is the colorant, is partially transferred to the sheet to perform desired recording. Then, each time one row of printing is completed, the sheet is conveyed, and the next row of printing is performed.

By the way, in the conventional paper feeding mechanism,
The paper feed roller 10 has a rubber roller body mounted on the outer periphery of a cylindrical metal core body.
Has a configuration in which a rubber roller body is mounted on the outer periphery of a cylindrical metal core body similarly to the paper feed roller 10, and the pressure roller 11 is pressed against the paper feed roller 10. Thus, a paper feeding mechanism is configured.

[0007]

In the case where the paper feed roller 10 and the pressure roller 11 each have a rubber core body attached to the outer periphery of a metal core as in the prior art, they are pressed against each other. The paper feed roller 10
And the roller body of the pressing roller 11 is elastically deformed, and the radius of each of the rollers 10 and 11 is changed.
However, there is a problem that an accurate conveyance amount of paper cannot be obtained. Further, the elastic deformation of the roller main body of the paper feed roller 10 and the pressing roller 11 may not be performed uniformly in the axial direction of the rollers 10 and 11, which may cause skew of the paper. Further, since the surfaces of both rollers 10 and 11 are formed of rubber, the grip force for sandwiching the paper is reduced, and the paper slips. In this respect, an accurate transport amount of the paper cannot be obtained. Was.
Therefore, the paper feed roller 10 and the pressing roller 11
In the case where white streaks or black streaks occur between lines of recording on paper, or when overlapping recording such as color recording,
There is a problem that a shift occurs in the recording position and a recorded image of good quality cannot be obtained.

[0008]

As resolving means for solving the above problems BRIEF SUMMARY OF THE INVENTION, the outer peripheral surface of the metal shaft which cross section is a circular, the outer peripheral surface of the metal shaft, a line at predetermined intervals a plurality of teeth are formed on and the metal shafts
And face each other with the teeth facing in opposite directions.
By cutting up with two punches, the height is 30 ~
The paper feed roller having a 90 μm projection was formed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the paper feed mechanism according to the present invention will be described with reference to FIGS.
FIG. 2 is an explanatory view of a paper feed mechanism of the present invention, FIG. 2 is an enlarged view of a main part of a paper feed roller of the paper feed mechanism of the present invention, and FIG. FIGS. 4A and 4B are explanatory views for explaining the biting of the paper between the paper feed roller and the pressure roller according to the paper feed mechanism of the present invention.

The paper feed mechanism according to the present invention is used, for example, in a printer as shown in FIG. 5, but the description in FIG. 5 is as described above, and the description is omitted here. And the paper feed mechanism of the present invention
1 and 2, the paper feed roller 20
Is a column-shaped metal shaft 2 having a circular cross section.
A plurality of protrusions 22 formed by partially protruding the metal shaft 21 itself are formed on the outer peripheral surface of one. The plurality of protrusions 22 are formed in a staggered manner at predetermined intervals in the axial direction and the circumferential direction of the metal shaft 21, and a plurality of protrusions 22 are formed in the axial direction of the metal shaft 21. A plurality of regions 23 are formed at intervals in the axial direction.

Further, said shape of each projection 22, formed in a substantially dome shape, comprising quarter spherical Toka et which is connected with the vertical plane 22a which faces the roller rotating direction to the vertical plane 22a as shown in FIG. 2 Each projection 22 has a height T of 30 to 90 μm and a pitch P1 of 0.2 in the circumferential direction.
−0.6 mm, and the axial pitch P2 is 0.6−
1.8 mm. That is, the paper feed roller according to the present invention
The plurality of protrusions of the roller 20 have a
The axial pitch is widened. Furthermore, the projections 22 field vertical plane 22a of the hemispherical dome shape is oriented in the direction of rotation of the respective paper feed roller 20, the direction of the vertical plane 22a of the plurality of projections 22 of the same row in the axial direction is the same direction ing. The directions of the vertical planes 22a of the projections 22 in the two rows located next to each other are opposite to each other, and the alignment of the projections 22 in the clothing row is staggered as described above.

The pressing roller 25 disposed so as to press against the paper feed roller 20 has a columnar shape with a circular cross section, and is formed of a material (for example, nylon) having a hardness of 60 to 90 degrees. The pressing roller 25 is disposed for each area 23 formed by the group of the protrusions 22. The width of the pressing roller 25 is slightly smaller than the width of the area 23. , Paper feed roller 20
The paper feed roller 20 and the pressure contact roller 25 constitute a paper feed mechanism for nipping and feeding the paper 30 such as paper or OHP.

Next, a method of manufacturing the paper feed roller 20 according to the present invention will be described with reference to FIG. 3. As shown, both ends of the punch 26 are stoppers 26a.
After working at the time of pressing, the stopper 26a comes into contact with the outer peripheral portion of the metal shaft 21 to obtain dimensional accuracy. When the teeth 27 of the punch 26 come into contact with the metal shaft 21, the surface of the metal shaft 21 is cut and raised to form a slipper-like processed portion including the cut-out recess 22 b and the projection 22. It becomes a dome-shaped projection. The metal shaft 21 may have a solid cylindrical shape or a hollow cylindrical shape as long as its outer peripheral surface is circular.

As shown in the figure, the teeth 27 of the punch 26 are formed in a row at a predetermined interval, and have a predetermined height so as to cut into the metal shaft 21 at a predetermined depth. One row of projections 22 is formed by one press working, but two punches 26 are provided facing each other so that the direction of the teeth 27 is reversed with the metal shaft 21 interposed therebetween. Since the positions of the teeth 27 on the two punches 26 are shifted in the axial direction of the metal shaft 21, the projections 22 are processed in two rows simultaneously (not shown). When the processing for one row is completed, the metal shaft 21 is rotated by a predetermined angle, and the next row is processed. The rotation of the metal shaft 21 at this predetermined angle is caused by another punch 26
Is formed so that the projection 22 in the opposite direction can be formed.

After one round of press working,
The formed projections 22 are formed with the direction of the vertical plane 22a between the rows reversed, and are arranged in a staggered arrangement for each row. When one round of machining is performed, the metal shaft 21
Is moved in the axial direction by a predetermined distance to form a projection 22 at a position facing the next pressure roller 25 in the same manner as described above.
By repeating this operation, the paper feed roller 20 on which the desired protrusion 22 is formed is obtained.

Further, as shown in FIG. 4, the paper 30 is conveyed by the frictional force of the projection 22 of the paper feed roller 20 until the leading end of the paper 30 is sandwiched between the paper feed roller 20 and the pressing roller 25. You. After the paper 30 is sandwiched between the paper feed roller 20 and the pressure roller 25, the leading end of the protrusion 22 of the paper feed roller 20 bites into the paper 30 to obtain a conveying force. When the protrusion 22 is provided on the metal shaft 21 in this manner, the paper feed roller 20 is not elastically deformed, and an accurate transport amount of the paper 30 can be obtained. Further, according to the experiment, in the case of OHP, since the surface is harder than paper, the tip of the projection 22 is hard to bite, and the grip force and the skew at the time of feeding the paper are equal to the pitch P1 of the projection 22 in the circumferential direction. It has been found that the direction pitch P2 is greatly affected. As a result of the experiment, when the pitch P1 in the circumferential direction of the projection 22 is set to 0, 2-0, and 6 mm, and the pitch P2 in the axial direction is set to 0, 6-1, and 8 mm, the skew is extremely small. The result that OHP conveyance with a good grip force was possible was obtained.

When the pitches P1 and P2 deviate from the values of the pitches P1 and P2 and become narrower, the load applied to one projection 22 is dispersed and becomes smaller.
Insufficient bite amount cannot be obtained and the axial pitch P
If the number 2 is large, the number of protrusions 22 that bite into the sheet is insufficient, and the grip force is insufficient. Further, if the pitch P1 in the circumferential direction is large, the amount of deflection of the OHP between the protrusions 22 increases, and the paper feed ( OHP) becomes unstable.

According to an experiment, the height of the projection 22 has a great influence on the paper feed.
When the height T of the sheet 2 is 30 to 90 μm, both the paper and the OHP do not damage the sheet 30 and have an appropriate bite amount into the sheet 30.
Reliable initial insertion (cueing) of paper between the five spaces can be performed. If the height T deviates from the value of the height T and the height T is low, the paper 30 is not only the protrusion 22 but also the paper feed roller 20.
And the load is dispersed, so that the protrusion 22 does not sufficiently dig into the paper 30.
If the height T is high, the leading end of the paper 30 is caught on the protrusion 22, and the paper feed roller 20 and the pressing roller 2
The paper 30 cannot be sent to the contact portion with the 5,
Insufficient paper feed not only prevents cueing, but also paper 30
When the paper is fed by pressing the paper, the paper 30 is damaged by the protrusion 22.

[0019]

According to the paper feed mechanism of the present invention, a predetermined time
Cutting with a punch with multiple teeth formed in a row at intervals
Accordingly, by the height to form a plurality of projections of 30-90Myuemu, without elastically deforming protrusions themselves to work hardening, and moderate amount of biting into the paper is obtained, and accurate reliable paper feed The transport amount is obtained, and the cueing of the sheet is ensured . Also, by adopting such a configuration, no skewing of the sheet, in which a recorded image of good quality can be obtained. Also, the plurality of protrusions are located between the metal shafts in the axial direction.
A paper feed roller provided in a plurality of areas at intervals,
By providing a plurality of pressure rollers that press against the paper feed roller, and by pressing the pressure rollers individually for each region of the protrusion group, the pressure of the protrusions against the paper can be reduced,
Eliminating the skew during transport , and rotating the individual pressing rollers without being affected by each other, enables more reliable paper feeding. Also, the plurality of protrusions, with respect to the pitch in the circumferential direction,
By widening the pitch in the axial direction , the skew is extremely small, and the paper can be transported reliably with an appropriate grip force.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram relating to a paper feeding mechanism of the present invention.

FIG. 2 is an enlarged view of a main part of a paper feed roller according to the paper feed mechanism of the present invention.

FIG. 3 is an explanatory view of manufacturing a paper feed roller according to the paper feed mechanism of the present invention.

FIG. 4 is an explanatory diagram for explaining the biting of the paper between the paper feed roller and the pressing roller according to the paper feed mechanism of the present invention.

FIG. 5 is an explanatory diagram of a printer to which the paper feeding mechanism of the present invention is applied.

[Explanation of symbols]

 Reference Signs List 20 paper feed roller 21 metal shaft 22 protrusion 22a vertical plane 22b recess 23 area 25 pressure roller 30 paper T protrusion height P1 circumferential pitch of protrusion P2 pitch of protrusion in axial direction

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 5/06 B41J 13/076 B65H 27/00 G03G 15/00

Claims (1)

(57) [Claims] The outer peripheral surface of the 1. A metal shaft section has a circular shape, the outer peripheral surface of said metal shaft, across and the metal shaft plurality of teeth are formed in a row at predetermined intervals its
A paper feed roller having a projection with a height of 30 to 90 [mu] m formed by cutting and raising with two punches provided opposite to each other so that the directions of the teeth are reversed. Paper feed mechanism.