JPH1067148A - Paper feed device of printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a decrease in feed accuracy even when a downstream side need means collides against a spur roller when a front end of a paper is sent to the downstream side by a feed means at the upper side of the stream than a printing head. SOLUTION: A paper P is fed by an initial move amount I by an upstream feed means 28 so that a printing start position faces a printing head 36. The paper while printing is sent downstream at a predetermined feed speed. When a front end of the paper P reaches a position p1 in front of a downstream feed means 29, the predetermined feed speed is switched to a lower feed speed, and the front end of the paper is sent at the lower speed to be held between a feed roller 25 and a spur roller 26 at the downstream side. When the paper reaches a position p2 where the holding is completed, the lower speed is changed to the predetermined feed speed and the paper is sent again at the predetermined feed speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for a printer, and more particularly, to a paper feeder in which a front end of a conveyed paper meets a downstream feed means downstream of a print head by slowing the paper feed speed. The present invention relates to a device for preventing deterioration of sheet feeding accuracy due to side feeding means.

[0002]

2. Description of the Related Art Conventionally, in a printer such as an ink jet printer, a paper feed mechanism for feeding a plurality of sheets stacked on a paper feed table one by one by a paper feed roller, and paper is fed by the paper feed mechanism. Paper feed mechanism to transport the paper to the paper output tray,
A printing mechanism having a print head for printing on paper fed by the paper feeding mechanism is provided. In the paper feed mechanism, a first feed roller and a driven roller that comes into contact with the first feed roller are provided on the upstream side in the transport direction from the print head, and the second feed roller and the contact roller on the downstream side in the transport direction from the print head. A plurality of spur rollers are provided.

[0003] The spur roller is a gear-shaped roller in which a plurality of radially extending protruding teeth are formed in an annular shape. Even if the ink on the printed paper is not dried by jetting, the spur roller adheres to the spur roller. Without feeding, the paper can be fed while being held in cooperation with the second feed roller. That is, the fed paper is conveyed along the paper conveyance path to a predetermined printing start position in which the front end is located closer to the front than the second feed roller by pressing and nipping by the first feed roller and the driven roller. From the print start position, a predetermined amount of paper feed (line feed) is performed at a predetermined feed speed every time printing is performed by the print head, and after the front end of the paper reaches the second feed roller, Each time the printing operation is completed, the paper is repeatedly fed by a predetermined amount in a state where the paper is pressed and nipped by the second feed roller and the spur roller in addition to the pressing and nipping by the first feed roller and the driven roller. It has become.

[0004]

As described above, in the conventional ink jet printer, the fed paper is pressed and nipped by the first feed roller and the driven roller, and conveyed to the print start position, and then printed. After that, the paper is fed at a predetermined feed speed by a predetermined amount every time the printing operation is completed. In the middle of the paper feeding every time the printing is completed, the front end of the paper is fed to the second feed roller. And a driven roller. At this time,
The front end of the sheet rarely enters the contact point between the rotating second feed roller and the driven roller accurately, and collides with one of the outer circumferences and is guided there. For this reason, resistance acts on the paper feed, the feed pitch decreases, the printing position shifts,
The problem that the print quality is reduced occurs. In particular, in the case of using a spur roller as a driven roller such as an ink jet printer, when the leading edge of the paper collides with the base of the protruding teeth of the spur roller, not only the resistance is further increased, but also printing is performed at a high resolution like an ink jet printer. In this case, a slight feed pitch error has a large effect on print quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feeding device for a printer which can maintain the paper feeding accuracy even when the front end of the paper encounters downstream feeding means downstream of the print head.

[0006]

According to a first aspect of the present invention, there is provided a sheet feeder for a printer, comprising: a print head; a first feed roller and a driven roller disposed upstream of the print head in a sheet transport path. A paper feed mechanism including a side feed means and a downstream feed means comprising a second feed roller and a driven roller disposed downstream of the print head, and printing before the front end of the paper reaches the downstream feed means. In the printer which starts printing by the head, the front end of the sheet is positioned between a first position between the print head and the downstream feeding means and a second position at an arbitrary small distance downstream from the downstream feeding means. When the front end of the sheet passes through the section between the first position and the second position when the output of the position detecting section detects the presence of Predetermined feed rate In remote slower setting feedrate is obtained and a feed speed control means for controlling the paper feed mechanism to send the paper.

The fed paper is pressed and nipped by the first feed roller and the driven roller of the upstream feed means disposed upstream of the print head by controlling the feed mechanism by the feed speed control means. Then, after the front end is fed along the paper transport path to a predetermined printing start position before reaching the downstream feeding means, printing is started by the print head, and a predetermined feeding speed is set by a predetermined amount every time a printing operation is completed. Will be sent by By the way, in the middle of the paper feeding, the front end of the paper is moved by the position detecting means to a first position between the print head and the downstream feeding means, and a second position at an arbitrary small distance from the downstream feeding means to the downstream side. When it is detected that the sheet passes through the section between the position and the position, the sheet feed mechanism is controlled by the feed speed control means, and the sheet is fed at a set feed speed lower than a predetermined feed speed.

That is, in the middle of the paper feeding executed every time the printing operation is completed, the front end of the paper encounters the downstream feeding means while moving at a low speed. As a result, the paper is smoothly moved between the second feed roller and the driven roller to be pressed and pinched by the feed force using the large frictional force, and the paper feed is executed with high accuracy, thereby deteriorating the print quality. Can be printed without the need.

According to a second aspect of the present invention, in the paper feeder of the printer according to the first aspect of the present invention, the position detecting means sets a position where the front end of the sheet is registered by the first feed roller and the driven roller as a reference position, and the reference position And the length of the sheet transport path from the first feed roller to the second feed roller. In this case, since the position where the front end of the sheet is registered by the first feed roller and the driven roller is used as the reference position, the position of the front end of the sheet when starting the sheet feed can be easily recognized, and the sheet feed amount from the reference position and Using the length of the paper transport path from the first feed roller to the second feed roller to accurately and easily determine the passage of a section between the first position and the second position of the front end of the paper by calculation Can be. In addition, the same operation as the first aspect is achieved.

According to a third aspect of the present invention, in the paper feeder of the printer according to the first or second aspect, the print head is an ink jet type head that ejects ink toward a paper to perform printing. The driven roller of the feeding means is a spur roller in contact with the printing surface of the sheet. In this case, during the feeding operation performed for each printing operation, the front end of the sheet moves at a low speed and encounters the spur roller of the downstream side feeding means. 2 The paper moves smoothly between the feed roller and the spur roller and is pressed and nipped, so that the leading edge of the paper is not lifted up and the paper is fed accurately. Can be printed without deteriorating the print quality.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is a case where the present invention is applied to an inkjet printer for monochrome printing that ejects black ink onto paper P to perform printing. As shown in FIG. 1, the inkjet printer 1 basically has
A sheet feeding mechanism 10 for feeding a plurality of sheets P stacked on a sheet table 12 one by one, and a sheet P fed by the sheet feeding mechanism 10 through a sheet conveying path 4 to a sheet discharge table (not shown) ), A printing mechanism 30 for ejecting and printing ink on the paper P being conveyed, and a pair of feed rollers 21 and 25 of the paper feed mechanism 14 and the paper feed mechanism 20. Is constituted by a drive mechanism (not shown) for rotationally driving the motor.

First, the paper feed mechanism 10 will be briefly described. As shown in FIG. 1, a paper feed cassette 11 is detachably mounted in a cassette mounting recess 2a formed at the upper end of the rear end of the main body frame 2. The rear end of the paper table 12 on which a plurality of sheets P are stacked is pivotally supported by the paper feed cassette 11 and the front end thereof is urged upward by a compression coil spring 13. . Immediately above the front end of the paper table 12, a paper feed roller 14 extending in the left-right direction is provided.
The left and right ends of the paper feed roller 14 are rotatably supported by a pair of left and right side walls 3 connected to the main body frame 2.

That is, a plurality of sheets P stacked on the sheet table 12 of the sheet cassette 11 are pressed by the sheet feeding roller 14 by the compression coil spring 13 via the sheet table 12. A feed motor 62 composed of a stepping motor
When the paper feed roller 14 is rotated counterclockwise through a drive mechanism (not shown) by the driving of the print head 3 (see FIG. 3), only the upper paper P is printed by the paper feed roller 14.
6 is fed. Next, the paper feed mechanism 20 that transports the paper P fed by the paper feed mechanism 10 will be described.

As shown in FIG. 1 and FIG.
The paper transport path 4 for transporting the paper P by the paper guide portion 2b extending forward from the cassette mounting recess 2a.
Are formed. The upstream feed mechanism 28 (corresponding to the upstream feed means) will be described.
A first feed roller 21 made of rubber is rotatably provided upstream of a print head 36 to be described later.
A driven roller 22 pivotally supported by the first feed roller 21 and abutting against the first feed roller 21 from above is pivotally attached to the side wall plate 3 and is rotatable at the lower end of a swing arm 24 urged by a compression coil spring 23. Is pivoted to.

The downstream feed mechanism 29 (corresponding to the downstream feed means) will be described. A second feed roller 25 made of rubber is rotatable on the downstream side of the print head 36 in the paper feed path 4 so as to be rotatable. Pivoted on frame 2, this second
Each of the plurality of spur rollers 26 abutting on the feed roller 25 from above is a gear-shaped roller having a plurality of radial projections, and is a mounting plate fixed to a support plate 33 that supports a carriage 31 described later. 27, it is rotatably supported at predetermined intervals in the printing width direction.

The first feed roller 21 and the second feed roller 21
The feed roller 25 is driven by a feed motor 62 via a drive mechanism (not shown). When the sheet P is fed by the feed roller 14 as shown in FIG. The rollers 21 and 25 are rotated in the counterclockwise direction, and the first feed roller 21 and the driven roller 22 are rotated.
Then, a registration operation for aligning the front end of the fed sheet P is performed. Thereafter, both feed rollers 21 and 25 are rotated clockwise to feed the registered sheet P at a predetermined feed speed in the transport direction. It has become. Here, the position where the first feed roller 21 and the driven roller 22 contact each other is defined as a reference position p0.

Next, the printing mechanism 30 will be described.
As shown in FIGS. 1 and 2, a carriage 31 is supported by a side wall (not shown) and extends in a left-right direction.
And an upper end portion of a support plate 33 movably supported in the left-right direction. An ink cartridge 35 containing ink to be used for printing is detachably mounted on a cartridge holder 34 fixed to the carriage 31. A print head 36 having a plurality of ink jet nozzles (not shown) for ejecting ink supplied from the ink cartridge 35 is mounted so as to face the paper transport path 4.

The carriage 31 is connected to a carriage drive motor 63 via a carriage drive mechanism (not shown).
(See FIG. 3), the paper P reciprocates in a direction orthogonal to the feeding direction. Here, the print head 36 has, for example, 64 inkjet nozzles,
It is divided and arranged in two rows of 32 pieces each. And
Based on the dot pattern data to be printed,
The ink jet nozzles are selectively driven for ejection.

Next, the control system of the inkjet printer 1 is configured as shown in the block diagram of FIG. The control device 50 includes a CPU 51, a ROM 52 and a RAM 53 connected to the CPU 51 via a bus 54 such as a data bus, an input / output interface 55, and drive circuits 56 to 58 connected to the input / output interface 55.
It is composed of

The input / output interface 55 includes:
An operation panel 60 provided with a power switch, various switches, and display lamps, an origin position detection switch 61 for detecting the origin position of the carriage 31, and the like are connected. A print head 36 is connected to the head drive circuit 56, A feed motor 62 is connected to the circuit 57,
The carriage drive motor 63 is connected to the drive circuit 58. Further, recording data transmitted from an external electronic device 65 such as a host computer can be received via a communication interface 64 connected to the bus 54.

The ROM 52 stores a print head 36, a carriage drive motor 63, a feed motor 62, and the like based on a communication control program for receiving recording data from the external electronic device 65 and print data developed into dot pattern data. A print drive control program for drive control, a print control program specific to the present application, which will be described later, and the like are stored. The RAM 53 is provided with various memories and buffers necessary for communication control and print control, in addition to a memory for storing received recording data and a print data memory for storing print data.

Here, as shown in FIG. 2, the ROM 52 stores a reference position p0, which is a position where the first feed roller 21 is disposed.
And a position p1 (corresponding to a first position) between the print head 36 and the downstream-side feed mechanism 29, that is, a position p1 (corresponding to a first position) at an arbitrary small distance upstream of the spur roller 26. , A first movement distance A from the reference position p0,
A position p2 (corresponding to a second position) at an arbitrary small distance downstream of the spur roller 26, and a position at which the pressing and nipping of the leading end of the sheet P is completed by the second feed roller and the spur roller 26. The second which added the encounter section D up to p2
The moving distance B is stored.

Next, a printing control routine performed by the control device 50 of the ink jet printer 1 will be described with reference to the flowchart of FIG. In the figure, reference symbol Si
(I = 10, 11, 12,...) Are each step. However, when this control is started, it is assumed that the dot pattern data to be printed is stored in the print data memory of the RAM. The paper feed roller 14 is driven in the counterclockwise direction, and the first feed roller 21 and the second feed roller 25 are driven in the counterclockwise direction. As shown in FIG. After the front end of the sheet P is sent between the first feed roller 21 and the driven roller 22 to complete the registration operation, the first feed roller 21 and the second feed roller 25 are driven clockwise, The feed motor 62 is driven by a predetermined drive pulse so that the predetermined print start position of the paper P corresponds to the print head 36, and the paper P is fed by the initial movement amount.
A movement distance I corresponding to the initial movement amount is set as a count value W of a feed amount counter that counts the total feed amount of the paper P. In this state, the control of FIG. 4 is started, the print data for one line (for one print operation) is read from the print data memory, and 64 print data provided in the print head 36 are provided based on the print data. Ink jet nozzles are selectively driven for ejection to perform printing processing (S1).
3).

Next, when the sheet P is fed, the current feed amount count value W is added to the next one feed amount α.
Is added to the count value W of the total feed amount, and the first moving distance A
When the paper P is smaller than the spur roller 2
When no collision occurs (S14: No), the feed motor 62 is driven at a predetermined feed speed (for example, 60 mm / sec), and the paper P is fed by a predetermined line feed amount (for example, 1/6 inch). (S15). Then, the total feed amount count value W is set to a value obtained by adding one feed amount α to the count value W (S17). If the printing process is not completed (S18: No), S13 and subsequent steps are repeatedly executed. You.

By the way, when the paper P is fed,
When the count value W of the total feed amount obtained by adding the next feed amount α to the current feed amount count value W is equal to or more than the initial movement distance A (S14: Yes) and is equal to or less than the nipping complete distance B (S19). : Yes), the count value W is the clamping completion distance B
Since the leading edge of the paper P is located in the encounter section D until the feed speed becomes larger than the predetermined feed speed, the feed motor 62 sets the feed speed lower than the predetermined feed speed (for example, about half of 30 mm / sec), the sheet P is fed by a predetermined line feed amount (S20), and the steps after S16 are executed.

As a result, as shown in FIG. 2, the sheet P is slowly fed at a set feed speed lower than a predetermined feed speed over the encounter section D, so that the front end of the sheet P rotates. Even if it collides with the spur roller 26, it is smoothly guided between the second feed roller 25 and the spur roller 26 and pressed and nipped by the feed force using the large friction due to the low speed of the first feed roller 21. , The feeding amount of the paper P is reliably fed by a predetermined amount, and the feeding accuracy does not deteriorate.

On the other hand, after the front end of the paper P has passed the spur roller 26, the count value W of the total feed amount when the paper P is fed is larger than the nipping completion distance B (S14: Yes, (S19: No), the feed motor 62 is driven at a predetermined feed speed in S15, and the paper feed is executed (S15). Then, when the printing process of the received print data is completed (S18: Yes), this control is terminated and the process returns to the main routine.

Here, the detecting means includes the ROM 52 storing the sandwiching completion distance B and the encounter section D, and the S of the print control.
10, S12, S14, S17, S19 and the control device 50.
It is composed of S20 and a control device 50. Further, the paper feeder includes a control program for print control, a feed speed control unit, a control device 50, and the like.

As described above, the print head 36,
An upstream feed mechanism 28 including a first feed roller 21 and a driven roller 22 disposed upstream of the print head 36 in the paper transport path 4, and a second feed mechanism 28 disposed downstream of the print head 36. And a paper feed mechanism 20 including a downstream feed mechanism 29 including a two-feed roller 25 and a spur roller 26, and an ink-jet printer 1 that starts printing by the print head 36 before the front end of the paper P reaches the downstream feed mechanism 29. In the middle of the feeding of the paper P executed every time the printing operation is completed, the front end of the paper P encounters the spur roller 26 while moving at a lower speed than a predetermined feeding speed when passing through the encounter section D. Therefore, even if it collides with the spur roller 26, it is accurately sent with a large feed force, and the second
Since the paper moves smoothly between the feed roller 25 and the spur roller 26 and is pressed and clamped, and the paper is fed with high accuracy, printing can be performed without deteriorating the print quality.

The first feed roller 21 and the driven roller 2
2 and the position where the front end of the paper P is registered is the reference position p0.
The initial movement distance A and the nipping completion distance B are used in relation to the paper feed amount W from the reference position p0 and the length of the paper transport path 4 from the first feed roller 21 to the second feed roller 25. Then, it is determined by calculation whether or not the front end of the sheet P is located in the meeting section D. Therefore, when starting the sheet feeding, the position where the front end is registered can be easily recognized as the reference position p0, and the sheet front end position can be easily recognized. A section in which the feed speed of P is switched to a low speed can be accurately and easily obtained.

Here, as a modification of the above embodiment,
The set feed speed can be set to an arbitrary feed speed equal to or less than half of the predetermined feed speed. Further, a detection sensor for detecting the front end of the paper P is provided at the position of p1 so as to face the paper conveyance path 4, and since the front end of the paper P is detected by this detection sensor, the speed is set over the encounter section D. Thus, the feed motor 62 may be configured to be driven. Further, the downstream feed mechanism 2 including the upstream feed mechanism 28 and the second feed roller 25 and a normal driven roller abutting thereon.
It is needless to say that the present invention can be applied to a paper feeder of various printers such as a thermal printer provided with the printer 9.
Note that in the encounter section D, the feed amount (line feed amount) of the paper P for each time is set to 1 / N of the normal line feed amount (1/6), and the print head 36 has one of the inkjet nozzles in the paper feed direction. Printing at a low speed may be performed substantially by repeating printing using / N. Although the count value W of the feed amount uses the count value from the reference position p0, the count value from the initial movement amount I can also be used. Also in the latter case, the initial movement amount I
Is counted from the reference position p0, the count value W of the feed amount is substantially the same as that counted from the reference position p0.

[0032]

According to the first aspect of the present invention, there is provided a paper feeder for a printer, wherein an upstream side feeder comprises a print head, a first feed roller and a driven roller disposed upstream of the print head in the paper feed path. Means and a paper feed mechanism including a second feed roller disposed downstream of the print head and a downstream feed means comprising a driven roller, wherein the print head controls the front end of the paper before reaching the downstream feed means. In a printer that starts printing, a position detection unit and a feed speed control unit that controls a sheet feeding mechanism to feed a sheet are provided, and in the middle of sheet feeding executed every time a printing operation is completed, the front end of the sheet is moved to the first position. When passing through the section between the second position and the second position, the moving member encounters the downstream-side feeding means while moving at a low speed, so that a smooth movement is provided between the second feeding roller and the driven roller of the downstream-side feeding means. It would be pressed sandwiched go to's, since the accuracy paper feeding is performed, it is possible to print without reducing the printing quality.

According to the paper feeder of the printer of the second aspect, the same effect as that of the first aspect is obtained, but the position detecting means uses the first feed roller and the driven roller as a reference for the position where the front end of the paper is registered. The position is detected using the sheet feed amount from the reference position and the length of the sheet conveyance path from the first feed roller to the second feed roller. Therefore, when starting the sheet feed, the position where the front end is registered is used as a reference. The position of the front end of the paper can be easily recognized as the position, and the first position of the front end of the paper and the first position of the front end of the paper can be determined by using the paper feed amount from the reference position and the length of the paper transport path from the first feed roller to the second feed roller. The passage in the section between the two positions can be accurately and easily obtained by calculation.

According to the paper feeder of the printer according to the third aspect, the same effects as those of the first or second aspect can be obtained, but the print head is an ink jet type head that prints by ejecting ink toward the paper. Since the driven roller of the downstream side feeding means is a spur roller in contact with the printing surface of the sheet, during the feeding operation executed for each printing operation,
The front end of the sheet moves at a low speed and encounters the spur roller of the downstream side feeding means. Even if the paper collides with the spur roller which is easily caught, it smoothly moves between the second feed roller and the spur roller to press and pinch. In addition, since the paper is fed with high accuracy, printing can be performed without deteriorating the printing quality even when performing high-resolution printing using the inkjet print head.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a main part of an ink jet printer according to an embodiment of the present invention.

FIG. 2 is an enlarged partial side view of a main part of FIG.

FIG. 3 is a block diagram of a control system of the inkjet printer.

FIG. 4 is a schematic flowchart of a print control routine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inkjet printer 4 paper transport path 20 paper feed mechanism 21 first feed roller 22 driven roller 25 second feed roller 26 driven spur 36 print head 62 feed motor D encounter section

Claims (3)

[Claims] 1. A print head, an upstream feed means comprising a first feed roller and a driven roller disposed upstream of the print head in the paper transport path, and a print head disposed downstream of the print head. A paper feed mechanism including a second feed roller and a downstream feed means comprising a driven roller, wherein the printer starts printing by the print head before the front end of the paper reaches the downstream feed means. Position detecting means for detecting that the position is between a first position between the print head and the downstream-side feeding means and a second position arbitrarily small distance downstream from the downstream-side feeding means; Receiving the output of the means, when the front end of the sheet passes through the section between the first position and the second position, at a set feed rate lower than the predetermined feed rate when passing through the other sections. Like sending paper Sheet feeder of the printer, characterized in that it comprises a feed speed control means for controlling the paper feed mechanism. 2. The method according to claim 1, wherein the position detecting means sets a position at which a front end of the sheet is registered between the first feed roller and the driven roller as a reference position, and feeds the sheet from the reference position and a first feed roller to a second feed roller. 2. The sheet feeding device of the printer according to claim 1, wherein the detection is performed using the length of the sheet conveying path up to the paper feeding path. 3. The print head is an ink jet type head that prints by ejecting ink toward a paper,
3. The sheet feeding device for a printer according to claim 1, wherein the driven roller of the downstream side feeding means is a spur roller that contacts a printing surface of the sheet.