JP3243997B2 - Printer - Google Patents

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 an improvement of the paper feeding mechanism.

[0002]

2. Description of the Related Art FIG. 4 is a schematic side view showing an example of a paper feeding means of a conventional printer, and FIG. 5 is a schematic side view showing a driving means of the paper feeding means.

In FIG. 4, reference numeral 10 denotes a paper feed roller, 2
Reference numerals 1, 22, and 23 denote pressing rollers. Reference numeral 30 denotes a head as printing means.

The paper feed roller 10 has a shaft 11,
One end of the shaft 11 has a paper feed gear 12 as shown in FIG.
Has been fixed. In FIG. 5, reference numeral 40 denotes a motor, and a pinion 41 fixed to an output shaft of the motor 40.
Are engaged with the paper feed gear 12 via the intermediate gear 42. Therefore, when the motor 40 rotates, the power is transmitted to the paper feed gear 12 via the intermediate gear 42, and the paper feed roller 10 is driven to rotate.

[0005] As shown in FIG.
Is attached to the paper guide 24 and is pressed against the paper feed roller 10 by urging means (for example, a spring) (not shown). The pressing roller 23 is supported by a support member (not shown), and is pressed against the paper feed roller 10 by urging means (not shown). In FIG. 4, these pressing rollers 21, 22, 23
Are indicated by F1, F2 and F3.

The head 30 is mounted on a carriage (not shown), and prints on the paper P while reciprocating in a direction perpendicular to the paper surface of FIG.

[0007] The above-described printer normally operates as follows.

The paper P is supplied from a paper feeding device (not shown) to a paper feed roller 10 as shown by an arrow a in FIG. When the paper is supplied, the paper feed roller 10 is driven to rotate, and the leading end of the supplied paper P reaches the pressing portion 21a between the paper feed roller 10 and the pressure roller 21 (see FIG. 4). Then, the paper is conveyed while being nipped by the paper feed roller 10 and the pressing roller 21.

As the paper feed roller 10 continues to rotate, the leading end of the paper P is further pressed by the pressing rollers 22, 23.
And the paper feed roller 10 and pass through the pressing portions 22a and 23a. In this way, the paper P is conveyed while being wound around the paper feed roller 10, separated from the paper feed roller 10 at the pressing roller 23, guided by a paper guide (not shown), and sent below the head 30.

When the leading end of the paper reaches a predetermined position below the head 30, the rotation of the paper feed roller 10 is temporarily stopped.
Printing by the head 30 is started.

When printing for one line is performed by the head 30, the paper feed roller 30 is driven again to feed the paper P in the direction of the arrow Y1 for the line spacing, and the head 30 prints the next line.

After predetermined printing is performed on the paper P by repeating such an operation, that is, the printing operation by the head 30 and the paper feeding operation by the paper feeding roller 10 at every line pitch, the paper P is discharged to a discharge unit (not shown). Is discharged.

[0013]

As the above-described printing operation is performed, the trailing end Pe of the paper P becomes a pressing portion 21a between the paper feed roller 10 and the pressing rollers 21, 22, 23.
It passes through 22a and 23a. FIG. 4 shows a state in which the trailing end Pe of the sheet passes through the pressing portion 21 a between the sheet feed roller 10 and the pressing roller 21.

Therefore, referring to FIG.
Is a pressing portion 21a between the paper feed roller 10 and the pressing roller 21.
Is described as an example, the trailing edge P of the sheet
When e passes through the pinching portion 21a, a phenomenon occurs in which the rear end Pe is ejected (strongly pushed) in the arrow Y1 direction (paper feed direction).

Since the pressing roller 21 is pressed against the paper feed roller 10 by the force F1 as described above, when the rear end Pe of the sheet passes through the pressing portion 21a (strictly speaking, the rear end P
e is the center 10c of the paper feed roller 10 and the pressing roller 21
(When passing through a line N1 common to the pinching portion 21a) connecting the center 21c to the rear end Pe of the sheet, a component force in the direction of the arrow Y1 due to the pressing contact force F1 acts on the rear end Pe of the sheet. The rear end Pe of the sheet is ejected in the direction of arrow Y1 by the component force.

Even if the above-mentioned component force acts, if the paper feed roller 10 does not slip between the paper P and the paper feed roller 10 does not rotate due to the above-mentioned component force, the trailing end Pe pops out. Does not occur.

However, actually, the paper feed roller 1
0 may slip between the sheet P and the paper P.
Even in the case where the slip does not occur, in the case of the driving means using the gear as shown in FIG. 5, since the gear has backlash, the paper feed roller 10 is rotated by the component force correspondingly. .

That is, the phenomenon that the trailing edge Pe of the sheet is ejected is caused by the fact that the sheet slips with respect to the paper feed roller 10,
Alternatively, the paper feed roller 10 is rotated by the above component force,
Or, it will be caused by a combination of these.

When such a phenomenon that the trailing edge of the sheet is flipped occurs, the amount of the trailing edge of the sheet is increased by the amount of the trailing edge of the sheet rather than the original amount to be fed by the sheet feed roller 10 (for example, the feed amount for the line spacing described above). Is sent extra, and the printing position by the head 30 is shifted accordingly.

Regarding this problem, no countermeasures have been taken in conventional printers.

The displacement of the printing position due to the above-described phenomenon of the trailing edge of the sheet is not so large, and the conventional printer has a very high resolution (dpi (dot)
per inch), and is mainly used for printing a document. When a document is printed at a predetermined line interval, a printing position is determined by a blank portion between lines of the document. The misalignment was so camouflage that it was not noticeable.

However, in recent years, as the printing performance, that is, the resolution of a printer has been improved, for example, when a solid black printing is performed over a printing area of two or more lines,
When printing one and a half lines at a time by one scanning of the head, a slight white streak may appear in an area where solid black is to be printed or in a character string due to the printing position deviation. Yes, it can no longer be ignored.

In particular, when a full-color image is to be obtained by an ink-jet head, for example, as shown in FIG. 6, three nozzle arrays NR, NB, NY
And a red (magenta) ink droplet is selectively ejected from the nozzle line NR, a blue (cyan) ink droplet is ejected from the nozzle line NB, and a yellow (yellow) ink droplet is ejected from the nozzle line NY. As a result, a full-color image is formed. In this case, the arrangement of the nozzles n forming the nozzle row is, for example, as shown in FIG. 7, the nozzles n of each color are arranged not linearly in a direction orthogonal to the paper feed direction Y1, and the print areas P1 and P2 are Is intentionally partially overlapped to form a high-resolution color image by overlapping ink droplets of different colors. Overlapping portion P12 of print areas P1 and P2
Is formed by feeding the paper P by the length L12 after printing on the print area P1. At this time, in order to properly overlap the ink droplets of different colors in the overlap portion P12 of the print area. Requires a high paper feed accuracy, at least an accuracy in which the distance between the nozzles closest to each other in the paper feed direction of the nozzle row (for example, Lp in FIG. 7) is the minimum feed unit.

However, if the paper feed amount is deviated due to the above-described phenomenon of the trailing edge of the paper, not only white streaks appear on the image but also the quality of the full-color image is impaired. .

Furthermore, since coated paper or the like generally used for performing full-color printing is thicker than plain paper, the rear end of the paper is largely repelled by the pressing roller, and white stripes are formed. Alternatively, image quality deterioration was more noticeable.

An object of the present invention is to solve the above-mentioned problems, and to reduce the influence of the above-described phenomenon of the trailing edge of the sheet on the image quality to obtain a high-quality image. To provide.

[0027]

According to a first aspect of the present invention, there is provided a printer, comprising: a paper feed roller; and a paper feed means for feeding the paper by pressing the paper with a pressure roller pressed against the paper feed roller. And a gear for driving this paper feeding means.
A drive means having a printing means for printing on paper sent by said paper feeding means, and control means for controlling the paper feed amount by controlling the driving means, the control means sends the paper When the trailing edge of the sheet passes through the pinching portion between the roller and the pressing roller, the sheet is fed by a small amount by the amount that would be ejected when the trailing edge of the sheet passes through the pinching portion. controlling said drive means so that said holding part
After the trailing edge of the paper has passed, the trailing edge of the paper
Drive control of the drive means by the amount that would have been
Characterized in that that.

According to a second aspect of the present invention , there is provided the printer according to the first aspect, wherein the mark is formed on a printing surface of the sheet.
If it has position adjusting means that can adjust the position of the character means
In both cases, the control means is adjusted by the position adjustment means.
Depending on the position of the printing means, the rear end of the paper
The amount that the trailing edge of the paper will be ejected when passing
It is a control means for determining .

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 discharging inks of different colors, and each of the nozzle rows discharges ink. An ink jet head capable of performing color printing by using the paper feed means and its driving means, wherein the paper feed means and the drive means feed the paper at a feed amount having a distance between nozzles closest to each other in the paper feed direction of the ink jet head as a minimum feed unit. Is sent.

[0030]

According to the printer of the first aspect, the gear is
The paper is nipped and sent by the paper feed roller and the pressure roller of the paper feed means driven by the driving means, and printing is performed by the printing means. The paper feed amount is controlled by the control unit controlling the driving unit.

When the trailing end of the sheet passes through the pressure portion between the paper feed roller and the pressure roller, as described above,
The trailing edge of the paper is ejected in the paper feed direction.

However, according to the printer of the first aspect, when the rear end of the sheet passes through the pressing portion between the paper feed roller and the pressure contact roller, the control section controls the rear end of the sheet. Since the driving means is controlled so that the paper is fed by an amount that is likely to be ejected when passing through the clamping portion, the amount of movement of the sheet caused by the ejection of the trailing edge of the sheet is almost offset. The Rukoto.

Therefore, according to the printer of the first aspect, even if the trailing edge of the sheet occurs, the amount of paper originally intended to be fed hardly changes, and an appropriate amount of paper can be obtained. As a result, a high quality image is obtained. By the way, the drive of the printer according to claim 1 is described.
Since the moving means has gears, as described above, the paper
When the rear end of the gear
The paper feed roller rotates by the amount. For this reason,
Feed the paper so that the trailing edge of the paper passes through the pinch
After printing by the printing means,
Let's feed paper again by driving paper feeding means without taking steps
Then, on the contrary, paper is fed by the amount of the backlash.
However, there is an inconvenience that the amount is reduced. this
On the other hand, according to the printer according to claim 1, the pressing portion
After the trailing edge of the paper has passed, the trailing edge of the paper
(That is, the trailing edge of the paper
Paper feed roller that would have rotated due to the flipping phenomenon
The driving means is controlled by an amount corresponding to the amount of rotation of
Therefore, the above inconvenience is eliminated. That is,
In the printer according to the present invention, the driving means has a gear.
The paper can be fed properly.
And high quality images can be obtained.

According to the printer of the second aspect ,
2. The printer according to claim 1, wherein
A position adjusting unit capable of adjusting a position of the printing unit;
And the control means is adjusted by a position adjusting means.
According to the adjusted position of the printing means, the pressing portion is
When the trailing edge passes, the trailing edge of the paper is ejected.
Since the control means for determining the wax amount, more appropriate Kamioku
Is automatically obtained.

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

According to the first or second aspect of the present invention, as described in the third aspect, the printing means of the printer includes a plurality of nozzle rows for ejecting inks of different colors, and each of the nozzle rows has an ink from each of the nozzle rows. An ink jet head capable of performing color printing by discharging ink, wherein the paper feeding means and its driving means feed paper with a feed amount having a distance between nozzles in a paper feeding direction of the nozzle row as a minimum feeding unit. This is particularly effective when the sheet is fed, and is more effective when the sheet to be printed is a relatively thick sheet such as a coated sheet.

[0043]

Embodiments 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 main part of a printer according to a first embodiment of the present invention, and FIG. 2 is a block diagram of the same main part.

As shown in FIG. 1, the basic structure of the paper feeding means is the same as that shown in FIG. 4, and corresponding parts are denoted by the same reference numerals.

That is, the paper feeding means P of this embodiment
F denotes a paper feed roller 10 and pressing rollers 21, 22, 2
3 (for convenience of explanation, the pressing roller 21
May be referred to as a first pressing roller, the pressing roller 22 may be referred to as a second pressing roller, and the pressing roller 23 may be referred to as a third pressing roller.)

The basic structure of the driving means D is the same as that shown in FIG.
1, an intermediate gear 42, and a paper feed gear 12.

The printing means 6, and a ink jet head 31 similar to that shown in FIG.

The printing operation is basically the same.
Each time printing (image formation) is performed by one single scan, the paper P is fed by a predetermined paper feed amount (for example, the feed amount L1 shown in FIG. 6).
2) Sent by one. In this embodiment, the paper feed amount can be arbitrarily adjusted using the distance between the nozzles closest to each other in the paper feed direction of the nozzle row (for example, Lp shown in FIG. 7) as the minimum feed unit.

The difference between the paper feeding means PF and the driving means D of this embodiment from the conventional one is that the components constituting them are manufactured with high precision. Further, a stepping motor is used as the motor 40.

Therefore, the error of the paper feed amount by one paper feed operation, that is, the paper feed operation performed every time printing is performed by one scan of the head 31 is small, and is about 10 to 20 μm. is there. The amount of paper movement caused by the trailing edge of the paper varies depending on the thickness of the paper.
It is about.

Reference numeral 51 denotes a detecting means for detecting the presence or absence of a sheet and the trailing edge Pe of the sheet.
And a light receiver 51b. If there is a sheet P between the light emitter 51a and the light receiver 51b,
a is in a state where light emitted from a is blocked by the paper P,
The light receiver 51b is in an OFF state. The paper P disappears from between the light emitter 51a and the light receiver 51b, that is, when the trailing end Pe of the paper P passes between the light emitter 51a and the light receiver 51b, the light emitted from the light emitter 51a is transmitted to the light receiver 51b. The light is received, and the light receiver 51b is turned on. These ON / OFF states of the light receiver 51b are monitored by a control unit 50 described later.

In FIG. 2, reference numeral 50 denotes a control means, which controls the driving means D to control the paper feed amount. Further, the control unit 50 controls the head driving unit HD to cause the head 31 to selectively eject ink droplets.

When the trailing end Pe of the paper P passes at least the pressing portions 21a and 22a between the paper feed roller 10 and the pressing rollers 21 and 22, the control means 50 controls the rear of the paper P. The driving means D is controlled so that the paper is fed by an amount that will be ejected when the end Pe passes through the squeezing section, and after the rear end Pe of the sheet passes through the squeezing section, The driving means D is driven and controlled by an amount corresponding to the amount by which the trailing edge Pe of the sheet will be ejected.

This operation will be described mainly with reference to FIGS. 1 and 3, taking a case where the trailing edge Pe of the sheet passes through the clamping portion 21a as an example.

The flowchart shown in FIG. 3 shows that the paper P
When the paper P is fed from a paper feeding device (not shown) to the paper feed roller 10 as shown by an arrow a in FIG. 1 and the leading end of the paper P reaches a predetermined position below the head 31 and the first line has already been printed. From the time when the trailing edge Pe of the sheet passes through the first clamping portion 21a until the subsequent sheet feeding operation is performed.

(I) After the first line is printed, the motor 40 is driven by a predetermined number of pulses (pulse number n ₁ ) in step ST1 to feed the paper by a predetermined amount.

(Ii) In step ST2, the head 31 is driven to perform predetermined printing.

(Iii) In step ST3, the detecting means 5
It is determined whether or not 1 has detected the sheet P, that is, whether or not the trailing edge Pe of the sheet has passed the detecting means 51.

(Iv) In step ST3, the rear end P of the sheet
If it is determined that e has not passed through the detecting means 51, the motor 40 is driven by a predetermined number of pulses (pulse number n ₁ ) in step ST1 to feed a predetermined amount of paper.
2, the head 31 is driven to perform predetermined printing. This operation, that is, step ST3, is performed until it is determined in step ST3 that the trailing edge Pe of the sheet has passed the detection means 51.
1. The operation of step ST2 is repeated.

(V) In step ST3, the trailing edge Pe of the sheet
Is determined to have passed the detecting means 51, the number of drive steps n of the motor 40 after the time when the trailing edge Pe of the sheet passed the detecting means 51 (the time shown in FIG. 1) is counted in step ST4. . The count number n at the time when the trailing edge Pe of the sheet has passed the detecting means 51 is 0.

(Vi) In step ST5, it is determined whether or not the count number n has reached _a predetermined count number na.
Here, the predetermined count number n _a is, as shown in FIG. 1, the number of drive steps n _{c of the} motor 40 required to reach the first clamping portion 21 a from the time when the trailing edge Pe of the sheet has passed the detection means 51. , The number of steps _nd is subtracted. As the number of steps n _{d to be} subtracted, a value smaller than the number of steps n ₁ for intermittently feeding the sheet is set.

[0063] That is, the predetermined count number n _a is set so as to satisfy the following two conditions.

[0064] In _{n a = n c -n d 0} <n d <n 1 (vii) step ST5, if the count number n is not reached the predetermined count number n _a, the motor 40 in step ST6 Is the predetermined number of pulses (pulse number n ₁ )
The sheet is driven to feed a predetermined amount.
1 is driven to perform predetermined printing, and in step ST4, n
To n = n + n ₁ . In step ST5, until the count number n is determined to have reached the predetermined count number n _a, the operation, i.e. the step ST6, step ST
7. The operation of step ST4 is repeated.

(Viii) If it is determined in step ST5 that the count n has reached the predetermined count n _a , the motor 40 is driven by (n ₁ −n _b ) pulses in step ST8 to remove send. Thereby, the rear end P of the sheet
e will pass through the pinching portion 21a.

Here, the pulse number n _b is determined by the rear end Pe of the sheet.
Is the amount that would be ejected when passing through the pinching portion 21a, converted into the number of pulses.

As described above, the pressing portion 21a is moved to the rear end P of the sheet.
When e is passed, the amount of minutes would trailing edge of the sheet is ejected (the number of pulses n _b min) only a small amount (n ₁ -
By feeding the paper at n _b ), the amount of movement of the paper caused by flipping the trailing edge of the paper is almost canceled.

Therefore, even if the trailing edge Pe of the sheet is flipped out in the sheet feed direction, the sheet feed amount originally intended to be fed (the sheet feed amount corresponding to the pulse number n ₁ ) hardly deviates, and the proper sheet feed is performed. The feed amount can be obtained.

The number of pulses n _{b to} be subtracted is
It can be easily set by actually supplying paper to the printer and measuring the amount of paper ejected when the trailing edge passes through the clamping portion.

(Ix) In step ST9, the head 31 is driven to perform predetermined printing.

(X) In step ST10, the motor 40 is driven by the number of (n ₁ + n _b ) pulses to feed the paper.

[0072] Here, the pulse number n _b is the same number as the number of pulses n _b described above.

As described above, in step ST8, in order to offset the movement of the sheet caused by the flipping of the trailing edge Pe, the amount of the trailing edge of the sheet (pulse number n _b ) is used. The paper is fed by a small amount (n ₁ −n _b ).

However, since the driving means D of the printer according to the first embodiment has the gears 41, 42 and 12, when the trailing edge Pe of the sheet is ejected, the backlash of the gear is reduced. The paper feed roller 10 rotates by the amount.

For this reason, the trailing end Pe of the sheet is
1a, the paper is fed in step ST8, and after the printing is performed in step ST9, the motor 40 is turned on again by a predetermined number of steps n ₁ without taking any measures.
When amount corresponding driven to send the paper, now it occurs disadvantageously min (i.e. the amount corresponding to the pulse number n _b) by the paper feed amount of the backlash conversely becomes smaller.

[0076] Therefore, in step ST10, (min pulse number n _b) wherein the pressing portions 21a after the trailing edge Pe of the paper has passed, less driving the minute step ST8
By driving the motor 40 as much as possible, the inconvenience described above is solved.

In the above description, the trailing end Pe of the sheet is
Although the description has been made of the case where the sheet passes through the holding portion 22a, the same applies to the case where the rear end Pe of the sheet passes through the pressing portion 22a. In this case, step ST5 of the flowchart shown in FIG.
Step number n _a in is replaced by the following conditions step number n _e.

[0078] _{n e = n f -n d 0} <n d <n 1 n f , as shown in FIG. 1, the paper trailing end Pe is detected means 5
This is the number of driving steps of the motor 40 required to reach the second clamping portion 22a from the time point when it passes through 1.

The same control is performed with respect to the third pressing portion 23a when printing is performed after the trailing edge Pe of the sheet passes through the pressing portion 23a, and when printing is not performed, Do not do.

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] <Second Embodiment> In the first embodiment differs from the second embodiment described above, FIG. 1, will be described with the help Figure 2, the control unit 5
The point 0 is that the conveyance of the paper by the paper feed roller 10 is started after the leading edge of the paper is aligned by controlling the driving means D as follows, for example.

That is, when the paper P is fed by a paper feeding device (not shown), the control means 50 first stops the paper feed roller 10 and the first pressing roller 21 or rotates the first pressing roller 21 in the reverse direction. By pressing the leading end of the sheet P against the holding portion 21a or by slightly reversing the paper feed roller 10 after the leading end of the sheet slightly passes through the holding portion 21a, the stretching force of the sheet is The leading ends of the sheets are aligned in the pressure unit 21a. Next, the paper feed roller 10 is driven to rotate in the normal rotation direction to start conveying the paper.

The control section 50 controls the driving means D as described above.

On the other hand, paper generally supplied to a printer is
There are several standard sizes such as A4 size,
The size is determined, such as B5 size, and the length is known.

Therefore, if the size of the paper supplied to the printer is known, the number of rotations of the paper feed roller 10, which starts normal rotation after the leading edge alignment operation of the paper has been started, ie, the number of rotations from the start of normal rotation. By counting the number of pulses, it is possible to obtain a point in time at which the trailing edge Pe of the sheet passes through the clamping portion.

Therefore, according to the second embodiment, even if the detecting means 51 is not necessarily provided, the pressing portions 21a and 22a are connected to the sheet P similarly to the first embodiment.
When the trailing edge Pe of the sheet P passes, the driving means D is controlled so that the sheet is fed by an amount that would be ejected when the trailing edge Pe of the sheet P passes through the pinching portion. ,
After the trailing edge Pe of the sheet has passed through the pinching portion, it is possible to drive and control the driving means D by an amount that would cause the trailing edge Pe of the sheet to be ejected.

< Third Embodiment> The third embodiment differs from the above-described first embodiment in the following point.

That is, the third embodiment will be described with reference to FIGS. 1 and 2 and includes a position adjusting means 52 for the head 31 which will be described later, and the head 31 adjusted by the position adjusting means 52. The amount (number of pulses nb) at which the trailing end Pe of the sheet P will be ejected when the trailing end Pe of the sheet P passes through the pressing portion between the sheet feed roller 10 and the pressing roller according to the position It is characterized in that it is determined.

Generally, when the head 31 is an ink jet head, the nozzle surface 31a of the head 31 (FIG. 1)
It is preferable that the distance (gap) G between the print surface Pa and the printing surface Pa of the paper is constant. This is because if the gap G is different, the impact point of the ink droplet on the printing surface Pa of the paper is shifted and the printing quality is reduced.

On the other hand, since the thickness of the paper differs depending on the type (for example, plain paper, coated paper, etc.), it is assumed that the head 31 cannot move back and forth with respect to the printing surface Pa (in the directions of arrows Z1 and Z2 in FIG. 1). In the case of a configuration in which movement cannot be adjusted, that is, a configuration in which position adjustment is not possible, a gap G may occur due to a difference in thickness of a sheet to be used for printing.

On the other hand, according to the third embodiment, since the head 31 is provided with the position adjusting means 52 capable of adjusting the position of the head 31 in the directions of arrows Z1 and Z2 in FIG. The head 31 according to the thickness of the printing surface Pa
The gap G can be adjusted to a constant value by moving forward and backward (moving in the directions of arrows Z1 and Z2 in FIG. 1).

As the position adjusting means 52, known means can be adopted. For example, it can be configured by providing a guide shaft for supporting and guiding the carriage on which the head 31 is mounted as an eccentric shaft, and providing a lever for rotating the guide shaft at the shaft end.

On the other hand, the phenomenon of repelling the trailing edge of the paper is caused by the application of a component force in the paper feed direction due to the pressing force of the pressing roller, and this component force varies with the thickness of the paper. Depending on this, the amount played at the rear end will differ. That is, the thicker the sheet, the greater the amount of play.

Therefore, in the third embodiment,
As shown in FIG. 2, a position detecting means 53 is provided for the position adjusting means 52, and in accordance with the position of the head 31 detected by the position detecting means 53 in the directions of arrows Z1 and Z2 in FIG. The controller 50 is configured so that the amount (the number of pulses nb) at which the is likely to be ejected is determined.

According to such a configuration, when the user operates the position adjusting means 52 (for example, the lever is rotated) when setting the paper in the printer,
The position of the head 31 adjusted by this operation (for example, the position of the lever) is detected, and the pulse number _nb is determined accordingly. That is, when the set sheet is a thick sheet, the head 31 is adjusted to the position moved in the direction of arrow Z1 in FIG. 1, and the pulse number _nb is set to be large accordingly. When the set sheet is a thin sheet, the head 31 is adjusted to the position moved in the direction of the arrow Z2 in FIG. 1, and the pulse number _nb is accordingly small (including 0 in this case). Will be set.

Therefore, according to the third embodiment, a more appropriate paper feed amount is automatically obtained.

Incidentally, for example, the operation panel of the printer is
When a selection switch for selecting the type of paper is provided, the number of pulses _nb may be determined in conjunction with the selection switch.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the present invention.

For example, the structure of claim 1 or 2
The present invention can be applied to a case where the printing unit is not an inkjet head.

[0105]

According to the present invention, a high-quality image can be obtained by minimizing the influence of the phenomenon of flipping of the trailing edge of the sheet at the pressure portion between the paper feed roller and the pressing roller on the image quality.

[0106]

[Brief description of the drawings]

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

FIG. 2 is a block diagram of the main part.

FIG. 3 is a flowchart for explaining the operation of the main part.

FIG. 4 is a schematic side view showing a paper feeding unit of a conventional printer.

FIG. 5 is a schematic side view showing a driving unit of a conventional printer.

FIG. 6 is a schematic plan view showing an inkjet head and its operation.

FIG. 7 is a schematic plan view showing an example of a nozzle of an inkjet head.

[Explanation of symbols]

 PF paper feed means 10 paper feed rollers 21, 22, 23 pressure contact rollers 21a, 22a, 23a clamping section 31 inkjet head (printing means) 50 control means

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazutoshi Kashiwara 3-5-5 Yamato, Suwa-shi, Nagano Inside Seiko Epson Corporation (72) Takuya Yasue 3-5-35 Yamato, Suwa-shi, Nagano (56) References JP-A-4-138273 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 13/00-13/32

Claims (3)

(57) [Claims] 1. A paper feed roller, a paper feed means for nipping and feeding a sheet by a pressing roller pressed against the paper feed roller, a drive means having a gear for driving the paper feed means, and the paper Printing means for printing on the paper sent by the feeding means; and control means for controlling the driving means to control the amount of paper feeding. The control means includes a pinch between the paper feeding roller and the pressing roller. When the rear end of the paper passes through the pressure unit, the driving unit is configured to feed the paper by an amount that is smaller by an amount that will be ejected when the rear end of the paper passes through the pressing unit. control
After the trailing edge of the sheet has passed through the pressing portion, the sheet
The driving hand is increased by an amount that would have been ejected at the rear end.
A printer characterized in that a stage is driven and controlled . 2. The printing means for a printing surface of the paper
With position adjustment means that can adjust the position of
The control means includes a mark adjusted by the position adjustment means.
The trailing edge of the paper passes through the pinching section according to the position of the character
The amount that the trailing edge of the paper will be
2. The printer according to claim 1 , wherein the control unit is a control unit for setting the printer. 3. The ink jet head according to claim 1, wherein the printing unit includes a plurality of nozzle rows for ejecting inks of different colors, and performs an ink jet from each of the nozzle rows to perform color printing. 3. The apparatus according to claim 1, wherein the means and the driving means feed the paper at a feed amount having a minimum feed unit as a distance between nozzles closest to each other in the paper feed direction of the inkjet head. Printer.