JP2000072300A - Paper feeder for printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder for a printer having no decrease in printed image quality even if printing is continued after the terminal end of a paper sheet is released from a paper feeding roller. SOLUTION: A paper feeder for a printer is implemented as follows: A paper sheet 8 is sent in a state applying backtension to a delivery roller 3 in a state grasping the paper sheet by both of a paper feeding roller 2 and a delivery roller 3. Printing is done even after the terminal end 10 of the paper feeder 8 is released from the paper feeding roller 2. Where, the shaft body 20 of the delivery roller 3 is formed of a high rigid body. The degree of the rigidity of the shaft body 20 is established in that releasing the terminal end 10 of the paper sheet 8 from the paper feeding roller 2 eliminates backtension to instantly return torsional deformation. But, the speed up rate of carrying the paper sheet caused by the instant return causes no adverse effect on printed image quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a paper feed roller disposed near an upstream side of a print head and a paper discharge roller disposed near a downstream side of the print head. The present invention relates to a paper feeder of a printer conveyed along a paper.

[0002]

2. Description of the Related Art A conventional printer of this type performs printing while feeding paper at a constant speed by a paper feed roller, and does not print after the end of the paper comes off the paper feed roller. It is formed to be. One side edge of the sheet is conveyed along a common reference position regardless of its size. Therefore, the position of the other end of the sheet differs depending on the sheet size. The paper discharge speed of the paper discharge roller is not the same as the paper feed speed of the paper feed roller, but is set to be faster than the paper feed speed by an increase rate s. The reason is that if both the paper feed roller and the paper discharge roller are holding the paper and the paper discharge speed of the paper discharge roller is lower than the paper feed speed of the paper feed roller, the paper will bend between the two rollers. As a result, the print image quality deteriorates, and the paper may be stained by touching the print head. When both the paper feed roller and the paper discharge roller are holding the paper, the paper transport speed is constant at the paper feed speed of the paper feed roller regardless of the paper discharge speed of the paper discharge roller. It is configured as specified. Therefore, a back tension is applied to the paper discharge roller, and the paper is conveyed in a tensioned state, that is, in a tensioned state.

[0003]

When the trailing end of the paper is released from the paper feed roller and the paper is released from the tension, the other end of the paper end portion depends on the size and rigidity of the paper. It may be slightly curved and deformed. This is because the other end is overhanged with respect to the discharge roller. Conventionally, this tendency has been observed in postcard and A4 size paper. Nevertheless, since the conventional printer does not print after the end of the paper has come off the paper feed roller, there is no particular inconvenience even if the curved deformation occurs. For this reason, conventionally, even if the other side edge of the sheet is curved, no considerable consideration has been given. However, a problem arises when printing is attempted to continue even after the end of the sheet has come off the paper feed roller. That is, in order to continue printing even after the end of the paper has come off the paper feed roller, the paper needs to be maintained in a flat posture even after the end of the paper has come off the paper feed roller. It is curved and deformed. For this reason, there is a problem in that the printed image quality is deteriorated in the portion printed after the paper feed roller is disengaged due to the curved deformation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeder for a printer in which the print quality does not deteriorate even if printing is continued after the end of the paper comes off the paper feed roller.

[0005]

In order to achieve the above object, the invention according to the first aspect of the present invention comprises a paper feed roller disposed near an upstream side of a print head and a paper feed roller disposed near a downstream side of the print head. One end of the paper is conveyed along a reference position, and back tension is applied to the paper discharge roller when both the paper feed roller and the paper discharge roller sandwich the paper. The paper is sent in the state,
In a paper feeder of a printer configured so that printing can be performed even after the end of the paper comes off the paper feed roller, the drive rollers serving as the paper discharge rollers are axially separated from each other by a common shaft. The drive rollers are all formed in the same width, and the position of the drive rollers is set at a position after the end of the paper is separated from the paper feed roller, and is at least a postcard and an A4 size. This is a position where the other end of the sheet with respect to the sheet can be maintained from below by the drive roller. According to the present invention, at least for a postcard and an A4 size sheet, the driving roller is arranged such that the other end of the sheet, which is different from the reference position side, can be maintained from below by the driving roller. Since the paper is arranged, the posture of the paper can be maintained in a flat state even after the trailing end of the paper comes off the paper feed roller, and the print quality does not deteriorate even if printing is continued as it is.

According to a second aspect of the present invention, in the first aspect of the present invention, in addition to the paper, a postcard for printing horizontally, a reciprocating postcard, an A5 size paper and a B5 size paper. The driving roller is disposed at a position where the posture can be maintained similarly. As a result, the posture can be similarly maintained for postcards, reciprocating postcards, A5 size paper, and B5 size paper when printing horizontally, so that printing is performed as it is after the end of these papers comes off the paper feed roller. The printing quality does not decrease even if the printing is continued.

According to a third aspect of the present invention, in the first or second aspect, a first driven roller paired with the driving roller and an upstream portion between the first driven roller and the first driven roller are provided. And a single second driven roller that is disposed slightly displaced to the side and does not form a pair with the driving roller. Due to the displaced arrangement of the second driven roller, the leading end of the sheet is easy to enter the discharge roller. That is, since the paper is in the cantilever state, the second driven roller has a function of deforming the other end of the paper from the top to the bottom, and there is a possibility that the curved deformation is amplified. On the other hand, in the present invention, the other end of the sheet can be maintained in a flat state from below, so that the deformation amplification effect of the second driven roller can be prevented, and a decrease in print image quality can be prevented.

According to a fourth aspect of the present invention, in the third aspect of the invention, a dedicated driven roller dedicated to the other end of the sheet is provided separately from the first driven roller and the second driven roller. It is characterized by having. Accordingly, the posture of the sheet can be maintained not only from the lower side but also from the upper side with respect to the other end of the sheet, so that the posture of the sheet that has come off the paper feed roller can be more reliably maintained.

According to a fifth aspect of the present invention, in the first aspect, the printer is an ink jet printer. Since the inkjet printer is capable of obtaining high-quality printed matter equivalent to a photograph, the problem of deterioration in print image quality is conspicuous, and the effect of the present invention is remarkable.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a main part of a printer according to an embodiment of the present invention, in which a part of a paper feeding device is omitted. FIG. It is a principal part longitudinal cross-sectional view which shows the state immediately after.

In the present embodiment, the printer is an ink jet printer, and the paper feed device of the ink jet printer includes, as shown in FIG. And a paper discharge roller 3 disposed near the downstream side of the head 1. The print head 1 is formed so as to be able to reciprocate in a direction perpendicular to the paper surface. The printer is formed so that printing can be performed even after the trailing end 10 of the paper 8 has come off the paper feed roller 2.
m, that is, up to 3 mm bottom margin. As shown in FIG. 1, a reference position 30 for sheet conveyance is provided at the right end of the figure, and one side end 40 of each sheet 8 is conveyed along the reference position 30.

The paper feed roller 2 is driven by a drive roller 4 which is driven by a drive source (not shown) via a gear (not shown).
The paper discharge roller 3 has a drive source common to the paper feed roller 2 and is driven by the drive roller 6 via a gear (not shown).
And the first driven roller 7. The drive roller 6
As shown in FIG. 1, a plurality of drive rollers 6, 6,... Are arranged so that a plurality of drive rollers 6, 6,. Is formed.

After the trailing end 10 of the paper 8 has come off the paper feed roller 2, at least the postcard 21 and the other end 41 of the A4 size paper 26 are driven by the drive roller 6 from below. The driving rollers 6, 6,... Are arranged at positions where the posture can be maintained. Further, in the present embodiment, in addition to the papers 21 and 26, a postcard 22, a reciprocating postcard 25, an A5 size paper 23 and a B5
The driving roller 6 is provided at a position where the posture can be maintained for the 5-size paper 24 in the same manner. The drive roller 6 may be disposed at any position as long as the position of the other end 41 of the sheet can be maintained as described above.
As in the cases of 23 and 24, the other end 41 may slightly protrude from the driving roller 6.

As shown in FIG. 1, the first driven rollers 7, 7 are disposed so as to be slightly displaced upstream in the sheet transport direction between the first driven rollers 7, 7 and do not form a pair with the driving roller 6. The second driven roller 17 is disposed. Although not shown, a dedicated driven roller dedicated to the other end of the sheet 8 may be provided separately from the first driven roller 7 and the second driven roller 17. 1 and 2, reference numeral 9 denotes a platen that supports the sheet 8 facing the print head from the back.

The discharge speed of the discharge roller 3 is increased with respect to the paper feed speed of the paper feed roller 2 in order to prevent the discharge speed from being lower than the paper feed speed of the paper feed roller 2. The paper feed roller 2 and the paper discharge roller 3 are configured so that the paper 8 is fed at the paper feed speed of the paper feed roller 2 in a state where both the paper feed roller 2 and the paper discharge roller 3 are nipping the paper 8. ing. Therefore, when the paper 8 is being conveyed while being nipped between the rollers 2 and 3, the back tension is applied to the paper discharge roller 3.

Next, the operation of the paper feeder of the printer according to the above embodiment will be described. According to the present embodiment, at least for the postcard 21 and the A4 size sheet 26, the other side edge 4 which is different from the reference position 30 side of the sheet.
Since the driving rollers 6, 6,... Are arranged so as to be able to maintain the posture of the driving rollers 1 from below by the driving rollers 6, 6,.
The posture of the paper can be maintained flat even after the trailing end 10 of the paper comes off the paper feed roller 2, and the print quality does not decrease even if printing is continued as it is.

Further, in addition to the postcard 21 and the A4 size paper 26, the posture can be similarly maintained for the postcard 22, the reciprocating postcard 25, the A5 size paper 23, and the B5 size paper 24 when printing horizontally. In the case where the drive roller is disposed at the position, the printing quality does not deteriorate even if printing is continued as it is after the trailing end of the paper comes off the paper feed roller 2.

A single second driven roller 17 which is disposed between the first driven roller 7 forming a pair with the driving roller 6 and slightly displaced upstream and does not form a pair with the driving roller 6.
With respect to the other end 41 of the sheet end portion 10 which has come off the paper feed roller 2, the other side end 41 is in an overhang state. The other side end 41 may be deformed from top to bottom, and there is a possibility that the curved deformation may be amplified. Since the side end 41 is maintained in a flat state from the lower side, the deformation amplification effect of the second driven roller 17 can be prevented, and a decrease in print image quality can be prevented.

The sheet 8 is not only held from the lower side with respect to the other side end 41 but also maintained from the upper side by a dedicated driven roller dedicated to the other side end. The posture of the sheet 8 is maintained more reliably. Further, when the printer is an ink jet printer, the ink jet printer is capable of obtaining high-quality printed matter at the same level as a photograph. The deterioration can be prevented, and high quality comparable to that of a photograph can be maintained.

[0020]

According to the present invention, the printing quality does not deteriorate even if printing is continued after the end of the paper has come off the paper feed roller. That is, according to the present invention, at least postcard and A
For four-size paper, the drive roller is arranged such that the other end, which is different from the reference position side of the paper, can be maintained from below by the drive roller.
The posture of the paper can be maintained in a flat state even after the end of the paper comes off the paper feed roller, and the print quality does not deteriorate even if printing is continued as it is. Further, in the case where a drive roller capable of maintaining the posture of a postcard, a reciprocating postcard, and an A5 size paper and a B5 size paper when printing horizontally is provided, the end of these papers comes off the paper feed roller. Even after printing, printing quality does not decrease even if printing is continued.

[Brief description of the drawings]

FIG. 1 is a main part longitudinal cross-sectional view showing a state immediately after a sheet comes off a sheet feed roller in a sheet feeder of a printer according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the paper feeding device of the printer, showing a state immediately before the paper comes off a paper feeding roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print head 2 Paper feed roller 3 Discharge roller 4, 6 Drive roller 5, 7 Follower roller 8 Paper 9 Platen 10 End of paper 20 Shaft

Claims (5)

[Claims] A paper feed roller disposed near the upstream side of the print head; and a paper discharge roller disposed near the downstream side of the print head. One end of the paper is conveyed along a reference position. In the state where both the paper feed roller and the paper discharge roller are sandwiching the paper, the paper is sent in a state where the back tension is applied to the paper discharge roller, and even after the end of the paper comes off the paper feed roller. In a paper feeder of a printer configured to be capable of printing, a plurality of drive rollers constituting the discharge roller are disposed so as to be separated from each other in an axial direction with a common shaft, and the width of the drive roller is They are all formed in the same manner, and the arrangement position is such that the end of the sheet has come off the paper feed roller, and the other end of the sheet has to be placed on the lower side with respect to at least the postcard and A4 size sheet. From the drive roller Paper feed apparatus of a printer which is a kill position. 2. A driving roller according to claim 1, wherein, in addition to the paper, a drive roller is provided at a position where the posture can be maintained for a postcard, a reciprocating postcard, an A5 size paper and a B5 size paper when printing horizontally. A paper feeder for a printer, wherein the paper feeder is provided. 3. A pair of a first driven roller forming a pair with the driving roller and a driving roller disposed between the first driven roller and being slightly displaced upstream. A paper feeder for a printer, comprising a single second driven roller that does not perform the operation. 4. The paper feeder according to claim 3, further comprising a dedicated driven roller dedicated to the other end of the sheet, separately from the first driven roller and the second driven roller. 5. A paper feeder for a printer according to claim 1, wherein said printer is an ink jet printer.