JPH0113430B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper feeding mechanism, and more particularly to a paper feeding mechanism that can feed paper in both forward and reverse directions without slack.

Generally speaking, printers use two types of paper.

In other words, paper without holes (regular paper) that does not have special holes for paper feeding, such as rectangular or square cut sheets or roll paper containing long paper.
This is paper with holes for paper feeding, which has sprocket holes on both sides of the paper. Note that in the case of paper with holes, there are perforations at regular intervals, and there are two types: fan-hold paper, which is folded back at the perforations, and paper with holes, which is rolled up. FIGS. 1 and 2 show a paper feeding mechanism that is equipped with a friction paper feeding means and a pin feed paper feeding means and is capable of feeding both plain paper and perforated paper.

FIG. 1 shows the case of feeding the plain paper 1, in which the pinch rollers 2 and 3 of the friction paper feeding means press the plain paper 1 against the platen 4, which is the friction paper feeding roller. Pinch roller 2 is pressed with strong force to obtain a large driving force, but pinch roller 3
The plain paper 1 is pressed against the platen 4 with a very weak force that does not sag on the front surface 6 of the print head 5. FIG. 2 is a diagram showing the case of feeding the perforated paper 7, in which the pinch roller 2 is released from pressure contact with the platen 4 by a release lever (not shown). However, the pinch roller 3 is in contact with the platen 4 via the perforated paper 7, which is exactly the same as in the case of normal paper. Reference numeral 9 is a paper cutter whose tooth tip faces at a distance l from the front surface 6 of the head. The platen 4 and the pin feed roller 8 of the pin feed paper feeding means always operate in conjunction with each other, but the amount of feed by the platen 4 is made larger than the amount of feed by the pin feed roller 8. This is because, if the feed amount is kept exactly the same, the perforated paper 7 will become slack between the pin feed roller 8 and the platen 4, and if this is too severe, a paper jam will occur.
The reason is explained below. The nominal pitch of the pin is usually 12.7 mm, so the hole pitch of the paper is also processed to 12.7 mm, but due to the physical properties of paper, it can easily expand or contract by about 0.1 mm due to the effects of temperature and humidity. If the pitch becomes 12.6 mm, the amount of feed by the pin feed roller 8 will decrease. On the other hand, since the amount of tension by the platen 4 is 12.7 mm, tension is applied to the perforated paper 7 between the pin feed roller 8 and the platen 4. However, since the pinch roller 3 pushes the platen 4 with a weak force, the perforated paper 7 slides against the platen 4, and the paper can be fed without any problem. On the other hand, when the hole pitch of the paper is 12.8 mm, a slack is created between the platen 4 and the pin feed roller 8 by 0.1 mm per pitch. Although 0.1 mm is a small amount, this amount is cumulative, so if you feed 100 pitches, it becomes 10 mm, causing a paper jam. Therefore, conventionally, the feed amount by the platen was changed to the pin feed roller 16.
It was set to about 1/100 larger than the feed amount.

With this setting, the hole pitch of the paper will be reduced.
No paper jam occurs even when stretched to 12.827mm. However, if it were to stretch beyond this point, a paper jam would still occur, and even if paper of normal dimensions was used, there was a drawback that the feed pitch would be different when using regular paper and perforated paper. In other words, the paper feed rate of printers is usually standardized to 1/6 inch (4.23 mm) or 1/4 inch (6.35 mm), so when printing on regular paper with this printer, it is approximately 1% faster than other printers. The value will be different. If you try to reduce this to 0.5%, you will have to suppress the elongation of perforated paper to within 0.5%, resulting in unusable paper.

Further, in such a paper feeding mechanism, if the paper is fed in the opposite direction, the correct tension is not applied to the paper, which often causes a jam.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and aims to provide a paper feeding mechanism that can accurately feed paper in both forward and reverse directions without slack.

3 and 4 are cross-sectional views of the center of the paper feeding mechanism according to this embodiment. Figure 3 shows the case when ordinary paper is being fed. A print head (wire dot head) 6 faces a platen 4, which is a friction paper feed roller of a print head of a friction paper feed means, via an ink ribbon 10 and a plain paper 1. The pin feed roller 8 constitutes a pin feed paper feeding means;
Reference numeral 1 denotes a rubber roller which is a second friction paper feeding roller of the friction paper feeding means.

The platen 4, pin feed roller 8 and rubber roller 11 are driven by a common pulse motor 12 as shown in FIG. A gear 13 integrated with the output shaft of the pulse motor 12 meshes with a gear 14 and further rotates gears 15 and 16. Here, the platen 4 is adjusted so that the amount of paper fed by the platen 4 and the pin feed rollers 8, 8' are exactly equal.
The rotation ratio of the pin feed rollers 8 and 8' is set, and a rotation of one row of the pulse motor provides a circumferential movement of 4.23 mm for both. Gear 15 rotates gear 18 via intermediate gear 17. A one-way clutch 19 using a ratchet mechanism or the like is built into the gear 18, and the pulse motor 12 rotates the rubber roller 11 in the forward direction, but cannot rotate it in the reverse direction. The rotation ratio when the rubber roller 11 rotates in the forward direction is set so that the paper feed amount is approximately 10% larger than the paper feed amount by the platen 4 and pin feed rollers 8, 8', and 1
Obtain a circumferential movement of 4.65 mm for the rotation of a row.

Referring again to FIG. 3, the pinch roller 2 is pushing the platen 4 through the plain paper 1 with a strong force.
On the other hand, the pinch roller 3 pushes the platen 4 through the plain paper 1 with a very weak force. Rubber roller 11 is used to feed the plain paper 1 in the forward direction (direction A).
rotates at a peripheral speed higher than that of the platen 4, so the plain paper 1 is always under tension between the pressure contact point 20 of the pinch roller 2 and the platen 4, and the pressure contact point 21 of the rubber roller 11 and the pinch roller 3. It's summery. However, since the pressure applied by the pinch roller 3 is set to be much smaller than that of the pinch roller 2, the plain paper 1 may slip on the rubber roller 11 side. Therefore, the plain paper 1 can be accurately fed 4.23 mm in the forward direction per line. Furthermore, even if the paper is set with slack between the pressure contacts 20 and 21 due to this tension, the slack can be removed by slightly feeding the paper, and staining of the paper by the ink ribbon 10 can be prevented.

Furthermore, when the plain paper 1 is fed in the opposite direction (direction B), the one-way clutch 19 prevents the rubber roller 11 from rotating and applies frictional force to the paper.
As expected, tension is applied between the pressure contacts 20 and 21, and the plain paper 1 slips on the rubber roller 11 side, so the plain paper 1 does not sag even when being fed in the reverse direction, and is fed exactly 4.23 mm per line. This makes it possible to backfeed in large quantities without causing paper jams.

FIG. 4 is a diagram showing a case where perforated paper 7 is being fed.

In this case, the pinch roller 2 is released from pressure contact with the platen 4 by a release lever (not shown). When the perforated paper 7 is fed in the forward direction (direction A), the pin feed rollers 8, 8' feed the perforated paper 7 by exactly 4.23 mm per line. In this case, the platen 4 does not apply any feeding force to the paper. Rubber roller 1
1 has a faster circumferential speed than the pin feed rollers 8 and 8' and pulls the perforated paper 7, so the paper 7 has a tensile force between the point where it is locked to the pin 28A of the pin feed roller 8 and the pressure contact point 21. is given. Since the perforated paper 7 cannot slide against the pin feed rollers 8 and 8', it will slide against the rubber roller 11, and in the end, the perforated paper 7 is fed exactly 4.23 mm in the positive direction per line. . Further, the tensile force of the rubber roller 11 is set to such an extent that the perforated paper 7 does not slacken between the locking point of the pin 28A and the pressure contact point 21, and the perforated paper 7 does not tear from the hole. When the perforated paper 7 is fed in the reverse direction, the rubber roller 11 is not rotated by the one-way clutch 19, so tension is still applied to the paper between the pressure contact point 21 and the pin 8A, and the paper is transferred to the rubber roller 1.
It is accurately reversed by 4.23mm while sliding against 1.

In this embodiment, a so-called tightening spring clutch may be used as the one-way clutch 19, and in this case, the rubber roller 11 is not rotated by the motor because the power of the pulse motor 12 is not transmitted when the paper is fed in the reverse direction. However, when the paper is back-fed, it will follow the paper and rotate without rubbing. Further, at this time, the rubber roller 11 rotates with a slight resistance force, which imparts tension to the paper, but in order to further increase this tension, the rotation of the rubber roller 11 may be restricted by other spring means or the like.

FIG. 6 shows another embodiment according to the invention. In this example, compared to the embodiment according to FIG. 4, a pin feed tractor 22 is used instead of a roller as the pin feed member. It goes without saying that the difference between the tractor and the rollers has no effect on the effects of the present invention. Furthermore, in FIGS. 3 and 4, the platen 4 also serves as the first friction paper feed roller, which is the main feed roller for plain paper, and as a platen for printing, but in the embodiment shown in FIG. Platen 23
is a fixed member made of metal, and a feed roller 24 is separately provided as a first friction paper feed roller. In the case of perforated paper 7, the pinch roller 2 is released from the roller 24, and in the case of ordinary paper, it is strongly pressed against the roller 24, thereby achieving exactly the same effect as the embodiment shown in FIGS. 3 and 4. It is something.

As described above, the present invention has the following effects.

(b) The paper feed pitch is uniform and accurate paper feed is possible when using either plain paper or perforated paper.

(b) Paper jam will not occur even if perforated paper expands or contracts by more than 1% due to temperature and humidity.

(c) Regardless of whether paper with holes or regular paper is used, paper can be fed in the reverse direction accurately without slack, and no problems occur even when the feed amount is extremely large.

(d) Even if the printing paper is not properly set and has slack at the printing position, simply feeding the paper in either the forward or reverse direction will remove the slack and eliminate stains on the paper caused by ink ribbons, etc.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of a conventional example, Figures 3 to 5 are an embodiment of the present invention, and Figure 3 is a sectional view of the paper feeding mechanism when using plain paper. , 4th
The figure is a cross-sectional view of the paper feeding mechanism when using perforated paper, FIG. 5 is an explanatory view of the rotational force transmission mechanism, and FIG. 6 is an explanatory view of another embodiment. 1... Plain paper, 2, 3... Pinch roller, 4,
23...Platen, 7...Perforated paper, 8...Pin feed roller, 10...Ink ribbon, 11...
Rubber roller, 12... Pulse motor, 22...
Pin feed tractor, 24...Feed roller.

Claims (1)

[Claims] 1. In a paper feeding mechanism capable of feeding both perforated recording paper with sprocket holes and non-perforated recording paper without sprocket holes, a pin feed mechanism for feeding the perforated recording paper, and a paper feeding mechanism of the pin feed mechanism. a first friction paper feed roller that rotates at the same circumferential speed as the speed and feeds the non-perforated recording paper; and a first friction paper feed roller that is closer to the recording paper discharge side than the pin feed mechanism and the first friction paper feed roller. A second friction paper feed roller which is provided and rotates at a faster circumferential speed than the first friction paper feed roller presses against the first friction paper feed roller with a strong pressure contact force, and the pressure contact and release of the pressure contact are performed. a possible first pinch roller; a second friction paper feed roller;
a one-way clutch provided on the friction paper feed roller of the invention, which rotates the second friction paper feed roller when the recording paper is fed in the forward direction and does not rotate when the recording paper is fed in the reverse direction; Both recording paper and non-perforated recording paper are fed under tension by the second friction paper feed roller rotated by the second pinch roller and the one-way clutch when paper is fed in the forward direction; A paper feeding mechanism characterized in that when paper is fed in the opposite direction, the paper is fed under tension by the second pinch roller and the second friction paper feeding roller which is not rotated by the one-way clutch.