JPH09267496A - Printer - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a printer in which white streaks hardly appear on a printing surface. A gear 321 made of a synthetic resin for driving a paper feed roller is fixed to a gear mounting portion provided on a shaft 331 of a paper feed roller 330 with an adhesive S, or a composite for driving a paper feed roller. A resin gear is integrally molded and fixed to a gear mounting portion provided on the shaft of the paper feed roller. The printing unit is an inkjet head capable of performing color printing, and the paper feed roller 330 feeds the paper P with a paper feed amount with a distance between nozzles closest to each other in the paper feed direction of the head as a minimum feed unit. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer.
In particular, it relates to improvement of the paper feeding mechanism.

[0002]

2. Description of the Related Art FIG. 8 is a schematic side view showing a paper feeding mechanism of a conventional printer, and FIG. 9 is an exploded perspective view of a main part with parts omitted.

In FIG. 8, reference numeral 1 is a drive motor, which is fixed to a frame (not shown). 2 is this motor 1
Pinions fixed to the output shaft of the device, 3 and 4 are reduction gears made of synthetic resin, and 5 is a paper feed roller. The power of the motor 1 is transmitted to the paper feed roller 5 via the pinion 2, the reduction gears 3, 4. The paper feed roller 5 is rotatably supported by a frame (not shown), and the reduction gear 4 is fitted and attached to one end of a metal shaft 5a.

As shown in FIG. 9, at one end of the shaft 5a,
A metal pin 6 is provided in a direction orthogonal to the shaft 5a, and the grooves 4a, 4a fitted in the pin 6 are provided in the reduction gear 4
Is formed so as to be continuous with the hole 4b.

The reduction gear 4 made of synthetic resin is attached to the shaft 5a by being weakly press-fitted. This is because if the reduction gear 4 is strongly pressed into the shaft 5a, the reduction gear 4 will be deformed in the initial stage of being attached to the shaft 5a.

In FIG. 8, reference numerals 7 and 8 denote first and second pressure contact rollers that are pressed against the paper feed roller 5 by a biasing means (not shown), and press the paper P against the paper feed roller 5. There is.

The sheet P is composed of the first and second pressure contact rollers 7,
The sheet 8 is pressed against the sheet feeding roller 5 and is conveyed with a conveying force.

FIG. 12 is a plan view schematically showing a printing operation of a conventional printer.

In the figure, reference numeral 9 is an ink jet head, and this head 9 has a nozzle row N consisting of a plurality of nozzles n. The head 9 selectively ejects ink droplets from the nozzles n while moving in the direction of the arrow X11 or X22 in the figure to print characters and other images on the paper P. Reference numeral P1 in the drawing indicates a print area formed by one print operation by the head 9, and the length L of the nozzle row N is L.
Is equal to Note that the symbol Y in the figure represents the paper feed direction.

When one printing operation is completed, the above-mentioned motor 1 is rotated and the paper feed roller 5 moves the paper P to the arrow Y.
In the direction, the sheet is fed by the length L, and the head 9 prints on the next print area P2.

[0011]

The above-mentioned conventional printer has the following problems.

When the motor 1 is driven, FIG. 8 and FIG.
As shown in (a), the side walls 4a2, 4a2 on one side of the grooves 4a, 4a of the reduction gear 4 press the pin 6, whereby the rotational force is transmitted from the reduction gear 4 to the shaft 5a. Therefore, the side walls 4a2, 4a2 on one side of the grooves 4a, 4a are
It is pushed by the pin 6.

As the reduction gear 4, a synthetic resin gear is used for cost reduction, and the reduction gear 4 is attached to the shaft 5a by weak press-fitting, so that when the motor 1 is driven. Side walls 4a on one side of the grooves 4a, 4a
When the pins 2 and 4a2 are pushed by the pin 6, the reduction gear 4 is deformed, and as shown in FIG. 10 (a), a gap A1 is formed between the side wall 4a1 and 4a1 opposite to the grooves 4a and 4a and the pin 6. , A
1 is formed.

On the other hand, as the above-described printing operation is performed, the trailing edge of the paper P is sandwiched between the paper feed roller 5 and the first and second pressure contact rollers 7, 8 as shown in FIG. Pass through. FIG. 11 shows a state in which the trailing edge portion PE of the sheet passes through the pinching portion 7 a between the sheet feeding roller 5 and the pressure contact roller 7. With reference to this figure, a case where the trailing end portion PE of the paper passes through the pressing portion 7a will be described as an example. The paper P is pressed against the paper feed roller 5 by the pressing force F1 of the pressing roller 7, and is conveyed. The rear edge of the paper
When the sheet passes through the pinching portion 7a, a force F2 is applied to the rear end portion PE so as to repel the rear end portion PE in the sheet feeding direction (the direction of the arrow Y).

At this time, the pressure contact roller 7 is used for the rear end portion PE of the sheet.
Of the paper feed roller 5, a force F3 is applied to the paper feed roller 5 to turn the paper feed roller 5 in the paper feed direction (the direction of the arrow Y) via the rear end portion PE of the paper.

Since the gaps A1 and A1 are formed in the grooves 4a and 4a of the reduction gear 4 as described above, when the trailing edge PE of the sheet passes through the pinching portion 7a, the When the force F3 is applied, as shown in FIGS. 10B and 11, the paper feed roller 5 is rotated by the gap A1 more than the rotation amount of the reduction gear 4.

That is, the paper feed roller 5 rotates more than the desired paper feed amount, and the pitch of the paper feed amount shifts.

When such a pitch shift occurs, FIG.
The print areas P1 and P2 are separated from each other as shown in (3), and the separated areas appear as white streaks on the print surface depending on the print pattern.

In particular, when a full color image is to be obtained with an ink jet head, for example, as shown in FIG. 13, a nozzle row NR, NB, NY having a plurality of nozzles n is provided in the head 9 ' A full-color image is formed by selectively ejecting a red ink droplet from NR, a blue ink droplet from a nozzle row NB, and a yellow ink droplet from a nozzle row NY. In this case, as shown in FIG. 13, the arrangement of the nozzles n forming the nozzle row is set such that the nozzles n of each color are not linearly arranged in the direction orthogonal to the paper feeding direction Y, as shown in FIG. Print areas P1 and P2
Is intentionally partially overlapped with each other, and ink droplets of different colors are overlapped to form a high-resolution color image. The overlapping portion P12 between the printing areas P1 and P2 is formed by feeding the paper P by the length L12 after printing in the printing area P1. At this time, in the overlapping portion P12 of the printing areas, different colors are formed. In order to properly overlap the ink droplets, high paper feeding accuracy, at least the distance between the nozzles of the inkjet head that are closest to each other in the paper feeding direction (for example, Lp in FIG. 14) is set as the minimum feeding unit. Paper feeding accuracy is required.

However, as described above, if the pitch of the paper feed amount is deviated, white streak appears, and there is a problem that the white streak becomes noticeable in full-color printing.

Moreover, since the coated paper generally used for full-color printing is thicker than the plain paper, the trailing edge of the paper is largely repelled by the pressure roller, which causes white streaks. Was even more noticeable.

An object of the present invention is to solve the above problems, and when the trailing edge of a sheet passes through the nip portion between the sheet feed roller and the pressure contact roller, the sheet feed roller sets a desired sheet feed amount. It is an object of the present invention to provide a printer that can prevent the above-described rotation and that hardly shows white streaks on the printing surface.

[0023]

In order to achieve the above-mentioned object, a printer according to a first aspect of the present invention comprises a paper feed roller for feeding a sheet, and a pressure contact roller for pressing the sheet against the paper feed roller. Printing means for printing on the paper fed by the paper feed roller, a gear mounting portion provided on the shaft of the paper feed roller, and a composite for driving the paper feed roller mounted on the gear mounting portion. A resin gear is provided, and the gear is fixed to the gear mounting portion with an adhesive.

According to another aspect of the printer of the present invention, a paper feed roller for feeding the paper, a pressure contact roller that is pressed against the paper feed roller and presses the paper against the paper feed roller, and prints on the paper sent by the paper feed roller. Printing means for performing
A gear mounting portion provided on the shaft of the paper feed roller and a synthetic resin gear for driving the paper feed roller, which is mounted on the gear mounting portion, are provided, and the gear is integrally formed on the gear mounting portion. It is characterized by being fixed.

According to a third aspect of the present invention, in the printer according to the first or second aspect, the printing means includes a plurality of nozzle rows for ejecting ink of different colors, and ejects ink from each of these nozzle rows. Is an inkjet head capable of performing color printing by means of, and the paper feed roller feeds paper by a paper feed amount with a distance between nozzles closest to each other in the paper feed direction of the inkjet head as a minimum feed unit. It is characterized by being.

[0026]

According to the printer of the first aspect, the synthetic resin gear for driving the paper feed roller is fixed to the gear mounting portion provided on the shaft of the paper feed roller with an adhesive. The following effects can be obtained.

That is, when the trailing edge of the paper passes through the nip portion between the paper feed roller and the pressure contact roller, a force is applied to the trailing edge of the paper to push it out in the paper feeding direction. As a result, a force to rotate the paper feed roller acts on the paper feed roller. However, according to this printer, a synthetic resin gear for driving the paper feed roller is attached to the gear mounting portion with an adhesive. Since it is configured to be fixed by means of, the shaft of the paper feed roller does not rotate more than the rotation amount of the gear, and the paper feed roller rotates more than the desired paper feed amount. Is prevented.

Therefore, when the trailing edge of the sheet passes through the pinching section, the pitch of the sheet feed amount does not deviate, and the white line is less likely to appear on the printing surface.

According to the printer of claim 2, the synthetic resin gear for driving the paper feed roller is fixed to the gear mounting portion provided on the shaft of the paper feed roller by integral molding. In addition to the function and effect of the printer according to the first aspect, the function and effect of simplifying the manufacturing process can be obtained.

As described in claim 3, the above-mentioned structure according to claim 1 or 2 is provided with a plurality of nozzle rows for ejecting inks of different colors, and ink is ejected from each of these nozzle rows to produce a color image. A printer including an inkjet head capable of printing and a paper feed roller that feeds a paper at a paper feed amount with a distance between nozzles of the inkjet head that are closest to each other in the paper feed direction as a minimum feed unit On the other hand, it is particularly effective.

That is, in the case where different color inks are ejected from each nozzle row to obtain full-color printing,
As described above, the printing is performed by overlapping the printing areas. However, according to the configuration of claim 1 or 2, since the desired paper feeding accuracy can be obtained, the printing areas can be accurately overlapped. Is possible. Therefore, white streaks hardly appear on the printing surface, and a high-quality color image can be obtained.

According to the first or second aspect of the invention, even when full-color printing is performed using thick coated paper or the like, when the trailing edge of the paper passes through the pinching portion,
Since the pitch of the paper feed amount does not deviate, white lines are less likely to appear on the printed surface, and a high quality color image can be obtained.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a partially omitted side view showing a first embodiment of a printer according to the present invention, and FIG. 2 is a partially omitted plan view showing a paper feeding device.

In FIG. 1, 100 is a paper feeding device, and 200 is
Is an ink jet printer main body, 300 is a paper feeder,
Reference numeral 410 denotes an inkjet head for full-color printing as a printing unit, and 420 denotes an inkjet head for monochrome printing.

The paper feeding device 100 includes a paper support 110.
And a pair of hoppers 120 (only one side is shown in the figure) and a pair of paper feed rollers 130 (only one side is shown in the figure).

Paper to be fed (not shown) is provided on the upper surfaces of the paper support 110 and the pair of hoppers 120.
Is placed.

The pair of hoppers 120 can support both sides of the front portion of the sheet, and are slidably inserted into the support rod 140.

The pair of paper feed rollers 130 are D type rollers having a rubber layer on the surface, and are fixed to the grooved paper feed roller shaft 131. Paper feed roller shaft 131
Is rotatably supported by a side frame (not shown) of the printer main body 200 via a bearing.
The sheet is rotationally driven at the time of sheet feeding by a drive mechanism (not shown).

As shown in FIG. 2, the paper feeding device 300 is
Drive motor 310 and reduction gears 320, 3 made of synthetic resin
21, a paper feed roller 330 made of rubber, and first and second pressure contact rollers 351 and 352.

As the drive motor 310, a step motor which makes one rotation with a predetermined pulse is used. The motor 310 is fixed to the side frame F of the printer body 200, and the pinion 311 is fixed to its output shaft.

The power of the motor 310 is the pinion 31.
1 and the reduction gears 320, 321 to the paper feed roller 330.

The paper feed roller 330 has a metal shaft 33.
1 is rotatably supported between the side frames F of the printer body 200, and the reduction gear 321 is attached to a gear attachment portion 332a provided at one end 332 of the shaft 331.

The gear mounting portion 332a is constructed by providing the pin 6 in the direction orthogonal to the shaft 331, as shown in FIG. 3, as in the case of the conventional example. The reduction gear 321 is provided with a groove 322 that fits into the pin 6.
It is formed continuously with 23.

The reduction gear 321 is fitted into the shaft 331 and the pin 6 with a weak press-fitting force that does not cause deformation at the time of mounting, and as shown in FIGS.
It is fixed to 31 and the pin 6. As the adhesive S, an adhesive that can bond metal and synthetic resin is used.

The rotational accuracy of the paper feed roller 330, which is rotationally driven via the drive motor 310, the pinion 311, and the reduction gears 320 and 321, as described above, is closest to the inkjet head 410, which will be described later, in the paper feed direction. It is possible to feed a sheet with a sheet feed amount with a distance between nozzles, for example, (1/720) inch as a minimum feed unit. In FIG. 2, 333 is a shaft 331.
Is a cap that covers one end portion 332.

As shown in FIG. 1, the first and second pressure contact rollers 351 and 352 are provided in a paper feed guide 350 provided along the paper feed roller 330, and the paper is fed by a biasing means (not shown). The feed rollers 330 are pressed against each other.

The sheet sent from the sheet feeding device 100 is brought into close contact with the sheet feeding roller 330 by pressing the first and second pressure contact rollers 351 and 352, and is conveyed with a conveying force.

Reference numeral 340 denotes a pressure contact roller provided at the most downstream position in the paper feed direction, which presses the paper against the paper feed roller 330 by urging means (not shown), and rolls the paper wound around the paper feed roller 330 and conveyed. A feed angle for feeding the ink jet heads 410 and 420, which will be described later, downward is defined.

In this embodiment, the pressure roller 340 is used.
After the trailing edge of the paper (not shown) has passed through the pressing portion 340a between the paper feed roller 330 and the paper feed roller 330, the printing by the inkjet heads 410 and 420 is not performed.

According to the paper feeding device 100 and the paper feeding device 300 as described above, the paper placed on the paper support 110 is fed by the pair of hoppers 120 when the paper is fed.
0, and is fed to the paper feeder 300 by the rotation of the paper feed roller 130. The sheet fed to the sheet feeding device 300 is pressed against the first and second pressure contact rollers 351 and 352 to be wound, and the feed angle is regulated by the pressure contact roller 340 so that the print portion A (see FIG. 1) is displayed. Be transported.

FIGS. 7A and 7B are plan views schematically showing the printing operation of the printer of this embodiment.

In FIGS. 7A and 7B, the inkjet head 410 for full-color printing and the inkjet head 420 for monochrome printing are mounted on the carriage 430 in a state of being aligned in the direction orthogonal to the paper surface of FIG. By moving the carriage 430, the carriage 430 moves in the X11 direction or the X22 direction in FIGS. 7A and 7B.

The head 410 has nozzle rows NR, NB, and NY composed of a plurality of nozzles n.
From the nozzle row NB, a blue ink drop from the nozzle row NB, and a yellow ink drop from the nozzle row NY. The symbol P1 in the figure indicates the nozzle arrays NR, N in one printing operation.
B and NY represent print areas to be printed.

The head 420 has a nozzle array N consisting of a plurality of nozzles n and is capable of ejecting black ink.

The distance Lp between the nozzles n and n of the head 410, which are closest to each other in the paper feed direction Y, is (1/720) inch in this embodiment. The paper feed roller 330 can feed the paper P by a paper feed amount with the distance Lp between the nozzles n, n being the minimum feed unit.

When monochrome printing is performed by the head 420, the motor 310 is rotated by a predetermined number of steps, whereby the paper feed roller 330 is rotated by an amount equal to the length L of the nozzle row N of the head 420. It Then, printing is performed by the head 420 for each predetermined printing area P1.

Further, in the case of performing high resolution full color printing, the motor 310 is rotated by the required number of steps, and the distance Lp (1) between the nozzles n, n closest to each other in the paper feed direction Y of the head 410 is obtained. The paper feed roller 330 is rotated by an arbitrary feed amount with a minimum feed unit of / 720 inch), and three colors of ink are selectively ejected from the head 410 to perform full-color printing. For example, as shown in FIG. 7B, after printing in the print area P1, the motor 3 is moved by a predetermined number of steps (length L12).
10 is rotated to print the upper part of the next print area P2 over the lower part of the print area P1, thereby performing full-color printing. In this case, the printing area P12 is an area where printing is performed in an overlapping manner.

As shown in FIG. 1, the heads 410,
The sheet P printed at 420 is transported by a pair of transport rollers 251,
52, the paper discharge tray 28 above the hopper 120 via the paper discharge roller 261
Is discharged above zero.

According to the printer of the above-described first embodiment, the gear mounting portion 33 of the shaft 331 of the paper feed roller 330.
Since the reduction gear 321 attached to 2a is fixed to the shaft 331 and the pin 6 with the adhesive S, the following operational effects are obtained.

When the motor 310 is driven, as shown in FIG. 4, the side walls 322 of the grooves 322 and 322 of the reduction gear 321 are driven.
a, 322a presses the pin 6 of the shaft 331 via the adhesive S, and at the same time, the side wall 3 on the opposite side of the grooves 322, 322.
22b and 322b pull the pin 6 in the rotation direction of the reduction gear 321 (direction of arrow Y1 in the figure) via the adhesive S, so that the side walls 322a and 322 of the grooves 322 and 322 are formed.
Since a is not unidirectionally pressed by the pin 6, the reduction gear 321 is less likely to be deformed. Therefore, no gap is formed between the side walls 322b and 322b of the grooves 322 and 322 and the pin 6 as in the conventional case.

Therefore, as shown in FIG. 5, a pinching portion 351a between the paper feed roller 330 and the first pressure contact roller 351.
When the trailing edge PE of the sheet P passes through the sheet P, a force F2 that pushes the trailing edge PE in the sheet feeding direction (the arrow Y direction in the drawing) acts on the trailing edge PE by the pressing force F1. As a result, even if a force F3 that tries to rotate the paper feed roller 330 is generated, the force F3 causes the paper feed roller 33 to rotate.
It will not happen that 0 rotates. Similarly, when the trailing edge portion PE of the sheet P passes through the pinching portion 352a between the paper feed roller 330 and the second pressure contact roller 352,
Even if a force to rotate the paper feed roller 330 is generated, the paper feed roller 330 does not rotate due to this force.

Therefore, according to the printer of this embodiment, it is possible to prevent the paper feed roller 330 from rotating more than the desired paper feed amount, and it is possible to obtain the effect that the white streak hardly appears on the print surface. To be

According to the printer of this embodiment,
An ink-jet head 410 capable of performing color printing, and a paper feed for feeding the paper P by a paper feed amount having a minimum feed unit of a distance Lp between nozzles n, n of the head 410 which is closest in the paper feed direction Y. Roller 33
Since 0 is provided, the following operation and effect can be obtained.

That is, in the case where different color inks are ejected from each nozzle row to obtain full color printing,
Printing is performed by overlapping the printing areas. However, according to the printer of the present embodiment, the desired paper feeding accuracy can be obtained, so that the printing areas can be accurately overlapped, and White streaks are less likely to appear on the screen. Therefore, a high quality color image can be obtained.

When thick coated paper or the like is used to obtain full-color printing, when the trailing edge of the sheet passes through the pinching portions 351a and 352a, the trailing edge of the sheet is fed. Although the force to push the paper in the direction tends to be larger than that in the case of plain paper, the printer of this embodiment causes the paper feed roller 330 to rotate more than a desired paper feed amount. Since white spots are less likely to appear even in full-color printing using thick coated paper, a high-quality image can be obtained.

<Second Embodiment> FIG. 6 is a schematic side view of an essential part showing a second embodiment of the printer of the present invention.

The difference of the second embodiment from the above-described first embodiment is that the reduction gear 321 described above is attached to the gear mounting portion 332a provided on the metal shaft 331 of the paper feed roller 330. The point is that they are fixed by integral molding.

As means for fixing the reduction gear 321 and the shaft 331 by integral molding, insert molding, outsert molding or the like can be adopted.

According to the printer of the second embodiment described above, the reduction gear 321 and the shaft 331 are integrally molded and fixed to each other. Therefore, in addition to the function and effect described in the first embodiment, Thus, the effect of simplifying the manufacturing process can be obtained.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the present invention.

For example, the invention according to claim 1 or 2 is
The present invention is not limited to the printer having the ink jet type head described above, but may be applied to other types of printers such as a thermal transfer printer and a laser printer.

[0073]

According to the present invention, it is possible to obtain the effect that white streaks hardly appear on the printed surface.

[0074]

[Brief description of drawings]

FIG. 1 is a partially omitted side view showing a first embodiment of a printer according to the present invention.

FIG. 2 is a partially omitted plan view showing a paper feeding device.

FIG. 3 is a side view of the reduction gear.

FIG. 4 is an enlarged view of a main part of the reduction gear shown in FIG.

FIG. 5 is an operation explanatory view.

FIG. 6 is a partially omitted side view showing a printer according to a second embodiment of the invention.

7A and 7B are plan views schematically showing a printing operation.

FIG. 8 is a schematic side view showing a paper feeding mechanism of a conventional printer.

FIG. 9 is a perspective view showing an end portion of a paper feed roller and a gear.

10A and 10B are explanatory views of a conventional technique.

FIG. 11 is an explanatory diagram of a conventional technique.

FIG. 12 is a plan view schematically showing a printing operation.

FIG. 13 is a plan view schematically showing a printing operation.

FIG. 14 is an enlarged schematic plan view of a main part of the head.

[Explanation of symbols]

 321 Reduction gear 332a Gear mounting portion 330 Paper feed roller 331 Shaft 351 First pressure contact roller 352 Second pressure contact roller 410 Inkjet head S Adhesive

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location F16H 55/06 F16H 55/17 A 55/17 B41J 3/04 101Z (72) Inventor Kazutoshi Kashihara Seiko Epson Co., Ltd. 3-3-5 Yamato, Suwa City, Nagano Prefecture (72) Inventor Takuya Yasue 3-3-5 Yamato, Suwa City, Suwa City, Nagano Prefecture Seiko Epson Corporation

Claims (3)

[Claims] 1. A paper feed roller for feeding a paper, a pressure contact roller pressed against the paper feed roller to press the paper against the paper feed roller, and a printing means for printing on the paper fed by the paper feed roller. A gear mounting portion provided on the shaft of the paper feed roller, and a gear made of a synthetic resin for driving the paper feed roller, which is mounted on the gear mounting portion,
A printer in which the gear is fixed to the gear mounting portion with an adhesive. 2. A paper feed roller for feeding a paper, a pressure contact roller pressed against the paper feed roller to press the paper against the paper feed roller, and a printing means for printing on the paper fed by the paper feed roller. A gear mounting portion provided on the shaft of the paper feed roller, and a gear made of a synthetic resin for driving the paper feed roller, which is mounted on the gear mounting portion,
A printer in which the gear is fixed to the gear mounting portion by integral molding. 3. The ink jet head, wherein the printing means is provided with a plurality of nozzle rows for ejecting ink of different colors, and is capable of performing color printing by ejecting ink from each of these nozzle rows. 3. The printer according to claim 1, wherein the roller feeds the paper with a paper feed amount with a distance between nozzles closest to each other in the paper feed direction of the inkjet head as a minimum feed unit.