JPH04235072A - Medium feed mechanism - Google Patents

Abstract

PURPOSE:To obtain a medium feed mechanism which can prevent a failure in feeding printing paper caused by the contact of a fold line, such as a perforation line, with a presser roller and extend a printing area of the printing paper with respect to a medium feed mechanism in which a plurality of presser rollers supported by a common arm are arranged on two or more different positions in the peripheral direction of a platen. CONSTITUTION:A paper feed mechanism consists of a first roller rotated by a drive source and a second roller which elastically comes into pressure contact with the first roller to rotate as a follower by the rotation of the first roller. A medium having fold lines is clamped between the first roller and the second roller to be fed. The second roller consists of a plurality of rollers which come into pressure contact with the first roller at different positions in the peripheral direction thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a medium feeding mechanism that presses a medium on a platen of a printer with a press roller and transports the medium by rotation of the platen, and particularly relates to a common medium. The present invention relates to a medium feeding mechanism in which a plurality of presser rollers supported by an arm are arranged at a plurality of different positions in the outer circumferential direction of a platen. [0002] Recently, printers such as wire dot printers have been used as output devices for personal computers, word processors, etc., and continuous paper, which is folded in a zigzag pattern along perforations, is widely used. [0003] In such a printer, the printing paper set on the platen is held down by a pressure roller, but when the fold at the perforation position passes the position of the pressure roller during page feeding, the fold hits the pressure roller and the feed is disturbed. This causes the printing paper to slacken, resulting in a decrease in printing quality, which forces printing to start from a position that is far away from the crease, which limits the printing range.There is a need for a mechanism to solve this problem. . 2. Description of the Related Art FIGS. 5A and 5B show an internal side view and a perspective view of essential parts of a wire dot printer. Figure 5
As shown in (a), the wire dot printer is housed in a housing 1 having a front cover 2, and is supplied with printing paper 3a from the outside (in this case, it has perforations at the page boundaries, and prints in a zigzag pattern at the perforations). folded continuous paper)
a tractor 4 that transports the paper, a platen 5a, a print head 6, a paper guide 7 that guides the print paper 3a from the bottom of the platen 5a to the front of the print head 6, and a press roller R.
1, R2, a press roller R3 that presses the printing paper 3a against the surface of the platen 5a above the print head 6, a separator 8 that separates the printing paper 3a from the platen 5a behind the press roller R3 and guides it to the outside, and an ink ribbon 9.
a ribbon cassette 9 that supplies 0 to the front of the print head 6;
A carrier 10 is mounted with a print head 6a and a ribbon cassette 9 and moves parallel to the platen 5a, that is, in a direction perpendicular to the drawing. [0005] The tractor 4 and the platen 5a are powered by a motor M1.
The printing paper 3a is transferred in conjunction with the carrier 10.
is moved by a motor (not shown). With such a configuration, the printing paper 3a transported by the tractor 4 is moved by the paper guide 7 and the pressing rollers R1, R.
2 is wound around the platen 5a, and held down by the press roller R3 at the set position.While the carrier 10 moves, a wire magnet (not shown) of the print head 6 is driven, and the ink of the ink ribbon 90 is released by the impact of the tip of the wire. is transferred onto the printing paper 3a and printing is performed. [0006] When printing for one line is completed, the printing paper 3a
is fed line feed, the moving direction of the carrier 10 is reversed, and printing is performed in the same manner. When one page has been printed,
The printing paper 3a is fed by a new page and printing is continued. [0007] Here, to explain the structure of the press roller R3, as shown in FIG. The arms 12a, 12b are rotatably held at their upper ends, and the lower ends of the arms 12a, 12b are rotatably supported by an apparatus frame (not shown). The pressing roller R3 can move its pressing position according to the size of the printing paper 3a. The arms 12a, 12b are biased in the direction of arrow D, that is, in the direction of the platen 5a, by a toggle spring (not shown), and when the printing paper 3a is set on the platen 5a, the arms 12a, 12b
When rotated in the direction of the platen 5a, the presser roller R
3 presses the platen 5a via the printing paper 3a, and the printing paper 3a is transported by driving the platen 5a and the tractor 4. When the arms 12a, 12b are rotated in the direction of arrow E and retracted from the platen 5a, they are pressed against a stopper (not shown) by a toggle spring and held at the retracted position. [0010] According to the above conventional method, as printing progresses, the printing paper 3a is page-fed, and a crease such as a perforation passes through the position of the presser roller R3 that presses the platen 5a. When pressing roller R3, the fold collides with the presser roller R3, causing resistance to the feed and causing it to slip.Also, when the presser roller R3 is pushed up by the crease, the presser becomes incomplete and irregular feed occurs, causing the printing head after the crease to 6. The printing paper on the front side loosens, and sometimes the left and right pressure rollers R3 do not allow the paper to pass through the folds evenly, causing the printing paper 3a to loosen unevenly and degrade print quality. There is a problem in that printing has to be started from the starting point, which limits the printing range. [0011] The present invention can prevent irregular feeding of the printing paper due to the folds of the printing paper coming into contact with the presser roller.
It is an object of the present invention to provide a media feeding mechanism capable of widening the printing range of printing paper. Means for Solving the Problems FIG. 1 shows a diagram of the basic configuration of the present invention. In the figure, 3 is a medium, 14 is a drive source, 5 is a first roller rotated by the drive source 14, 15 is in elastic pressure contact with the first roller 5, and is rotated by the rotation of the first roller 5. The second rollers 16 and 17, which sandwich and convey the medium 3 between them and the first roller 5, constitute the second roller 15, and are pressed against the first roller 5 at different positions in the outer circumferential direction. There are multiple rollers. Therefore, the first roller 5 and the second roller 15
A plurality of rollers 16 and 17 are configured to sandwich and convey the medium 3 between them. [Operation] The first roller 5 and the second roller are driven by the drive source 14.
When the medium 3 is conveyed while being sandwiched between the plurality of rollers 16 and 17 of the roller 15, if the medium 3 has an uneven part, for example, a crease at the perforation position, the uneven part is transferred to the plurality of rollers 1.
6, 17, for example, even if the first roller 5 reaches the position of the roller 16 and hits the roller 16, the rollers 16, 17 are pressing at multiple points in the outer circumferential direction of the first roller 5, so there will be resistance to the feeding. Even if the roller 16 is pushed up by the uneven portion, the roller 17 is fed without slipping.
Since the medium 3 is pressed against the first roller 5 by
The medium 3 is conveyed normally and no feeding disturbance occurs, the medium 3 is prevented from loosening, and printing quality can be ensured, so that there is no need to limit the printing range of the medium 3. [Embodiment] An embodiment of the present invention will be explained with reference to FIGS. 2 and 3. The same reference numerals indicate the same objects throughout the figures. [0016] Printing paper 3a, platen 5a,
The motor M1 and the pressing roller 15a are connected to the continuous medium 3, the first roller 5, the drive source 14, and the second roller 15 in FIG.
corresponds to each. FIG. 2 shows a main part configuration diagram in which the present invention is applied to the wire dot printer described in the conventional example. As shown in the perspective and side views of FIGS. 2(a) and 2(b), the pressing roller 15a is connected to the roller 16a.
, 16b and rollers 17a, 17b. Rollers 16a, 16b and rollers 17a, 17b
are held by holding members 18a and 18b, respectively, with their axes shifted and not facing each other in parallel, and holding member 18a
, 18b are provided with notches 19a, 19b, and the support shaft 11a (corresponding to the support shaft of claim 2) is provided with an engaging protrusion 13, so that the rollers 16a, 17a and the rollers 16b, 17b are provided in the rotating direction. is rotatably attached to the support shaft 11a by a predetermined angle so as to be able to press the surface of the platen 5a evenly. Further, it is attached so as to be movable in the axial direction according to the size of the printing paper 3a. Also, rollers 16a, 16b and roller 1
7a and 17b come into contact with each other at different positions in the outer circumferential direction of the platen 5a. That is, in a normal state, they contact each other at positions equidistant from the imaginary line connecting the axis of the support shaft 11a and the axis of the platen 5a. The support shaft 11b has arms 12A, 1 at both ends.
2B, and the lower ends of the arms 12A, 12B are rotatably supported by a device frame (not shown). Further, the arms 12A, 12B are biased in the direction of arrow D, that is, in the direction of the platen 5a, by a toggle spring (not shown), and when the printing paper 3a is set on the platen 5a, the arms 12A, 12B are biased toward the platen 5a.
When rotated in the direction a, the press roller 15a presses the platen 5a via the printing paper 3a. When the arms 12A, 12B are rotated in the direction of arrow E and retracted from the platen 5a, they are held in the retracted position by a toggle spring. Since it has such a configuration, the operation will be explained next with reference to FIG. First, the printing paper 3a is set on the platen 5a, printing progresses by the printing head 6, and when the page feed is performed, the convex part of the fold of the printing paper 3a touches the roller 1.
6a, 16b, the folds push up the rollers 16a, 16b, as shown in FIG. Therefore, the printing paper 3a is normally fed without slipping, and the printing paper 3a is prevented from becoming loose in front of the print head 6. Furthermore, as shown in FIG. 3(b), when the fold of the printing paper 3a moves forward and hits the rollers 17a, 17b, the rollers 17a, 17b are pushed up by the fold, and the holding members 18a, 18b are moved in the opposite direction. After a slight rotation, the rollers 16a and 16b press the platen 5a, and the printing paper 3a is similarly fed normally. Also, rollers 16a, 16b and roller 1
By arranging 7a and 17b in a shifted position so as not to face each other in parallel, the printing paper 3a is held down over a wide range in the width direction, thereby further contributing to normalization of feeding. In this way, when the fold of the printing paper 3a passes the pressing roller 15a, the rollers 16a, 16b and the rollers 17a, 17b are pressed at different positions in the outer peripheral direction of the platen 5a, so that the printing paper 3a
This eliminates disturbances in the feeding of the printing paper 3a, and there is no need to limit the printing range by separating the printing start position from the crease in order to ensure printing quality when changing pages of the printing paper 3a, and the printing range can be expanded. In the above example, the roller 1 of the presser roller 15a
Although the case where the rollers 6a, 16b and the rollers 17a, 17b are arranged at different positions so as not to face each other in parallel has been described, as shown in FIG. It is also possible to use the pressure roller 15b configured as shown in FIG. Furthermore, in the above example, the rollers 16a, 16b
A case has been described in which the rollers 17a and 17b are configured to contact the platen 5a at positions equidistant on both sides with respect to the imaginary line connecting the axis of the support shaft 11a and the axis of the platen 5a. It is also possible to have a configuration in which the contact is made at a position other than the contact position. [0027] As explained above, according to the present invention, since the second roller is constituted by a plurality of rollers having different axes, a plurality of rollers are formed at different positions in the outer circumferential direction of the first roller. Since the rollers are in pressure contact, when the fold of the medium passes the second roller, even if it hits one of the rollers and is pushed up, the other roller is in pressure contact with the first roller, so there is no slipping of the medium. This has the effect of eliminating feeding irregularities and preventing slack in the medium.

[Brief explanation of the drawing]

[Figure 1] Principle configuration diagram of the present invention

[Figure 2] Block diagram showing an embodiment of the present invention

[Figure 3]
Explanatory diagram of the example

[Figure 4] Explanatory diagram showing different embodiments

[Figure 5] Configuration diagram showing a conventional example

[Figure 6] Diagram explaining the problems of the conventional example

[Explanation of symbols]

Claims (3)

[Claims] Claims: 1. A first roller (5) rotated by a drive source (14); and a first roller (5) that is in elastic pressure contact with the first roller (5) and is driven by the rotation of the first roller (5). a rotating second roller (15), and between the first roller (5) and the second roller (15) a medium (
3), the second roller (15) is composed of a plurality of rollers (16, 17) that press against the first roller (5) at different positions in the outer circumferential direction. A media feeding mechanism characterized by: 2. The second roller (15) is supported by a support shaft at a position other than the center of the plurality of rollers (16, 17), and is located between the center of the support shaft and the first roller (5).
) at positions equidistant on both sides of the imaginary line connecting the centers of
2. The medium feeding mechanism according to claim 1, wherein the plurality of rollers (16, 17) of the roller (15) are configured to press against the first roller (5), respectively. 3. The second roller (15) is provided at a plurality of locations in the longitudinal direction of the first roller (5), and the plurality of rollers (16, 17) are arranged at opposing positions, respectively. 3. The medium feeding mechanism according to claim 1 or 2, wherein the medium feeding mechanism is arranged in a staggered manner.