WO2011007487A1

WO2011007487A1 - Method for printing on both sides of paper, paper feeding apparatus, and printer paper

Info

Publication number: WO2011007487A1
Application number: PCT/JP2010/003159
Authority: WO
Inventors: 巖松本
Original assignee: 株式会社フオトクラフト社
Priority date: 2009-07-14
Filing date: 2010-05-10
Publication date: 2011-01-20
Also published as: JP2011020292A; EP2455224A4; JP5349180B2; EP2455224B1; EP2455224A1

Abstract

Double-sided printing of images with high positional accuracy even on large-sized paper is accomplished by using paper, upon both ends of which punch-holes for transportation have been disposed, and a feeding apparatus (YH) provided with a drive roller (13) that rotationally drives while in contact with the paper and two tractors (14), which have a plurality of pins that engage with the punch-holes, that are disposed on both ends of the drive roller and rotationally drive by means of the rotationally driving force of the same shaft as the drive roller. The paper is set into the feeding apparatus, and the paper is fed in that state at a speed matching the movement of the pins while an image is printed upon one surface of the paper. The paper having printing finished upon one surface is flipped and set into the feeding apparatus, and the paper is fed in that state at a speed matching the movement of the pins while an image is printed upon the other surface of the paper.

Description

Method for printing on both sides of paper, paper transport device, and printer paper

The present invention relates to a method for printing on both sides of a sheet, a sheet conveying device for a printer, and a printer sheet used therefor.

Conventionally, a silver salt color film has been widely used as an image display medium such as an electric advertisement or an electric signboard. However, in recent years, an image printed on a printer paper by an ink jet printer is often used.

In such an image display medium, it is necessary to increase the density of the image for transmitted light as compared with the image for reflected light.

The silver salt method has a long history, and since a dye (coupler) with good transparency is used, high color developability can be obtained even at high concentrations. However, in the ink jet system with a short history, in order to increase the density of the image, the density of the ink made of a poorly transmissive pigment is simply increased or repeated twice or three times, and the quality is ignored. The method that has been taken.

Also, when printing on both sides by the inkjet method, there is a problem that the front and back images are shifted from each other.

That is, an ink jet printer is disclosed in which a recording medium is nipped and conveyed by a sheet conveying roller and a pressure roller, and a print head is reciprocated on the platen in a direction perpendicular to the medium conveying direction (Patent Document). 1). When printing on both sides using such an ink jet printer, the position of the paper with respect to the paper transport roller is misaligned, resulting in misalignment of the image.

Therefore, conventionally, such a method is used only when printing on a large size paper by a large ink jet printer. In other words, when the size of the paper is large, the viewing distance is long, that is, the user often sees from a distance, and the difference between the front and back images is not so noticeable.

However, since there are considerable image shifts, the shifts are noticeable when viewed nearby, which is problematic in terms of image quality.

Also, a method of automatically detecting an image shift and correcting an error manually, a method of reading an error with a CCD camera and automatically correcting a printing position, and the like are performed. However, even when the deviation is corrected by these methods, it is difficult to sufficiently correct the deviation. Although it is not so conspicuous when viewed from a large size and far away, the shift is conspicuous as it is in the middle size or small size, and there still remains a problem in terms of image quality.

Further, as a recording sheet for transmitted light for an ink jet printer, an ink receiving layer containing titanium oxide in a porous ink receiving layer (Patent Document 2), water-containing silica particles, a water retention material, and the like. What has (patent document 3) etc. are known.

Further, as a recording sheet for reflected light and transmitted light for an ink jet printer, a sheet having an ink receiving layer containing silica particles and an overall opacity of 70 to 90% has been proposed (Patent Document 4).

As described above, when double-sided printing of an image is performed by the printer disclosed in Patent Document 1, it is difficult to align the paper, and the image cannot be accurately aligned with high accuracy.

Also, even when performing double-sided printing of images using the papers disclosed in Patent Documents 2 to 4, it is difficult to align the paper, and it is impossible to perform accurate and accurate alignment. That is, when performing double-sided printing of images on these conventional papers, after printing an image on one surface, the paper is turned upside down and positioned as much as possible, and the image is placed on the other surface (back surface). Print. If a deviation occurs after printing is started, the position is corrected each time.

However, in such a method, a great amount of labor is required to set the paper on the paper transport roller so that it is not correct until printing is started. Even if the position is found to be misaligned, it is not easy to correct it and adjust it accurately. If the position cannot be corrected, it must be set again from the beginning.

Also, there is a conventional form paper in which punch holes for feeding are provided at both ends. However, such a conventional form sheet is small in size, such as B5 or A3, and is light in weight, so that it can be sufficiently conveyed by a conventional pin tractor type conveyance mechanism. In addition, the required positional accuracy of the paper is about 1 mm or less because character printing is the main application.

However, when performing double-sided printing of images on paper, high accuracy that is not comparable to the accuracy of the form, for example, accuracy in the micron range, is required. Moreover, the paper used for electric advertisements is as large as 1 meter or more, and is heavy. Conventionally, it has not been possible to perform double-sided printing of images on a large size sheet with high positional accuracy.

It is ideal that an electric signboard has a backlight disposed on the back side of the image, and that the surface illuminance is brighter than the surface illuminance due to external light. Satisfying the conditions indoors is not difficult, but meeting the conditions outdoors is not easy.

The reason for this is that the indoor ambient light is artificial lighting, and the surface illuminance is not so high, so that the illumination light source from the back can exceed the surface brightness by satisfying a predetermined condition. Because. However, outdoor ambient light is sunlight, and the surface illuminance due to this is extremely large, and it is extremely difficult to exceed the surface brightness.

As you often experience, the beauty of the night view of a big city is a geometric pattern woven by artificial lighting, but the lighting of the building is lit in most cases even during the daytime. However, the windows of daytime buildings and nighttime buildings are very different. This is due to the difference between artificial lighting and the brightness of the sun. The brightness of the surface light source of an electric advertisement or an electric signboard is about 5 to 6000 lux on average, but it becomes 100,000 looks in sunlight. This difference in brightness becomes a difference in contrast, and the indoor light leaking from the building window during the daytime cannot be seen. For this reason, an ideal image of an electric advertisement is created on both sides of a reflective material, and the image has moderate brightness regardless of whether the ambient light on the surface is the sun or artificial light. Ideally, it should be able to withstand viewing and at night the image will appear with the brightness of the backlight. As an image of such an ideal lighting advertisement, a silver salt type color film is not perfect, but conventionally there has been no material for lighting advertisement replacing the color film.
JP 2001-335183 A JP 2004-167706 A JP 2000-135859 A JP2003-312131

The present invention has been made in view of the above-described problem, and a method capable of performing double-sided printing of an image with high positional accuracy even on a large-size sheet, and a high position even on a large-size sheet. It is an object of the present invention to provide a paper conveyance device and printer paper that can be conveyed with high accuracy.

A method according to the present invention is a method for printing an image on both sides of a sheet, a sheet having punch holes for feeding at both ends, a driving roller that is rotationally driven in contact with the sheet, and Using a conveying device having a plurality of pins that engage with the punch holes and having two pin tractors that are arranged at both ends of the drive roller and rotationally driven by a rotational drive force coaxial with the drive roller, The paper is set on the transport device, and the paper is transported at a speed synchronized with the movement of the pins to print an image on one surface of the paper, and the paper that has been printed on one surface is turned over. In this state, the sheet is conveyed at a speed synchronized with the movement of the pin, and an image is printed on the other surface of the sheet.

Preferably, the shape of the pin is such that the pin on the line along the moving direction of the paper after the movement of the pin from the root position on the front side of the pin when the punch hole of the paper starts to come out of the pin. The shape may be such that the distance to the position on the front side is equal to the movement distance of the root position on the front side of the pin.

1 is a diagram illustrating a schematic configuration of a printer according to an embodiment. It is a front view of the paper conveyance device of the printer. FIG. 3 is an enlarged front view showing a main part of the sheet conveying apparatus in FIG. 2. FIG. 4 is a cross-sectional view of the paper transport device of FIG. 3. FIG. 3 is a cross-sectional view of the sheet conveying device of FIG. It is a figure which expands and shows a part of FIG. It is a front view of a sheet. It is a figure which expands and shows the part of the punch hole of a paper. It is a figure which shows the mode of conveyance of the paper by a pin tractor. It is a figure explaining the coordinate axis about the shape of the surrounding surface of the front side of a pin. It is a figure explaining the relationship of the contact position of the surrounding surface of the front side of a pin, and a paper. It is a figure explaining the determination method of the shape of the surrounding surface of the front side of a pin. It is a figure explaining the other example of the coordinate axis about the shape of a pin. It is a figure explaining the other example of the relationship of the contact position of a pin and a paper. It is a figure which shows the other example of a pin tractor. FIG. 4 is a diagram illustrating images printed on both sides of a sheet. It is a figure explaining the image density printed on the back surface of a paper.

1, the printer 1 includes a machine body 11, a delivery roller 12, a drive roller 13, a pin tractor 14, a pressure roller 15, a recording head 16, a platen box 17, a fan 18, a paper guide 19, and a control circuit.

The printer 1 is connected to a computer via an interface (not shown) and can be operated and controlled using a pointing device such as a keyboard. In addition, the control contents and images can be displayed by a display device (not shown).

A roll of paper PY wound in a roll shape is set on the machine body 11, and the paper PY is pulled out by a paper transport device YH described later, and an image GZ is printed on the surface thereof by the recording head 16. . The paper PY can be printed on both sides and is transparent or translucent, and the printed image can be observed with reflected light or transmitted light.

As shown in FIGS. 7 and 8, the paper PY is provided with a punch hole PA for feeding at both ends in a line at a constant pitch along the length direction. The punch hole PA has a circular shape, and its peripheral edge is cut off along the circumference. That is, there is no jaggedness or the like for avoiding interference with the pin at the peripheral portion of the punch hole PA, and the positional relationship thereof is accurately determined by the outer peripheral surface of the pin contacting the peripheral portion of the punch hole PA. .

In addition, the sheet PY is provided with a mark MKP indicating the correspondence between the positions of the punch holes PA provided in one row and the punch holes PA provided in the other row.

One mark MKP is provided for a predetermined number of punch holes PA. In the embodiment shown in FIGS. 7 and 8, one mark MKP is provided for five punch holes PA. As the mark MKP, a black dot, a color dot, an arrow, or the like can be used. Further, a hole may be provided as the mark MKP.

The mark MKP indicates that the left and right punch holes PA with the mark MKP are in the same position in the longitudinal direction. Therefore, as long as it can indicate which of the left and right punch holes PA is at the same position, the number, position, shape, addition method, and the like of the mark MKP can be arbitrarily selected.

The delivery roller 12 sends the paper PY to the drive roller 13 and the pin tractor 14. The feed roller 12 may or may not be provided with a pin that engages with the punch hole PA. Further, a guide plate may be provided in place of the feed roller 12. A guide plate may be provided together with the feed roller 12.

The driving roller 13 and pin tractor 14 cooperate with the pressure roller 15 to accurately position and convey the paper PY.

That is, referring also to FIG. 2, the driving roller 13 is rotationally driven in a state where the lower surface of the paper PY is in contact with the paper. The pin tractor 14 is disposed at both ends of the drive roller 13, has a plurality of pins PN that engage with feed punch holes PA provided at both ends of the paper PY, and is coaxial with the drive roller 13. It is rotationally driven by the rotational driving force.

That is, the pin tractor 14 is rotationally driven by a drive shaft having the same axis as that of the drive roller 13. Therefore, it is easy to synchronize the conveyance of the paper PY by the pin tractor 14 and the conveyance of the paper PY by the drive roller 13.

In the present embodiment, the shaft of the pin tractor 14 and the shaft of the drive roller 13 are integrally connected in the axial direction, but via a power transmission mechanism such as a coupling or a gear at an appropriate position in the axial direction. It may be connected.

Note that the pin tractor 14 on the left side in FIG. 2 may be described as “pin tractor 14a”, and the pin tractor 14 on the right side may be described as “pin tractor 14b”.

The pressure roller 15 (

pressure rollers

15 a and 15 b) is arranged to face the drive roller 13 and the pin tractor 14, and presses the paper PY toward the drive roller 13 and the pin tractor 14.

That is, the pressure roller 15a is pressed against the driving roller 13 weakly. This prevents a large frictional force from acting on the contact surface between the driving roller 13 and the paper PY, and allows a slight deviation between the driving roller 13 and the paper PY.

In order to weaken the force that presses the pressure roller 15a against the driving roller 13, the spring force that presses the pressure roller 15a may be weakened. In the case of a structure in which the pressure roller 15a is pressed by its own weight, the weight of the pressure roller 15a may be reduced. Further, a spring or the like for adjusting the pressing force of the pressure roller 15a may be provided. Alternatively, the number or length of the pressure rollers 15a may be reduced.

Also, instead of reducing the pressing force of the pressure roller 15a, or together with this, the material of the surface of the pressure roller 15a may have a small friction coefficient. Further, the material of the surface of the driving roller 13 may have a small friction coefficient.

Further, the pressure roller 15b presses the paper PY against the pin tractor 14. As a result, the sheet PY is pressed against the surface of the main body roller 141 at the position of the punch hole PA, and the punch hole PA is inserted to the root position TN of the pin PN. Thus, as the pin tractor 14 rotates, the position of the punch hole PA accurately moves along a curve CV described later on the peripheral surface of the pin PN, and the paper PY is accurately conveyed with high accuracy.

Incidentally, when there is no pressure roller 15b or when the pressure roller 15b does not press the paper PY to the surface of the main body roller 141, the punch hole PA is inserted at a halfway position that is not the root position TN of the pin PN. In this case, the sheet PY is not accurately conveyed by the pin PN.

The sheet conveying device YH is configured by the driving roller 13, the pin tractor 14, and the

pressure rollers

15a and 15b. The paper transport device YH is driven to rotate at a controlled speed by a motor (not shown) and a power transmission mechanism such as a gear or a belt.

The paper transport device YH transports the paper PY at a speed synchronized with the movement of the pin PN, and sends the paper PY forward by the rotation of the driving roller 13. That is, both ends of the paper PY are conveyed by the pin tractor 14 and the central portion of the paper PY is conveyed by the driving roller 13 at the same speed. The conveyance speed by the pin tractor 14 and the conveyance speed by the drive roller 13 are the same, and the paper PY is conveyed accurately in a straight line at a controlled speed without being twisted or dropped off.

Actually, the conveyance by the pin tractor 14 is more dominant than the driving roller 13, and the paper PY is conveyed at a speed synchronized with the movement of the pin PN of the pin tractor 14. That is, when a slight difference in the conveyance speed due to changes in temperature or humidity occurs between the pin tractor 14 and the drive roller 13, the conveyance speed is obtained by the pin tractor 14, and the drive roller 13 is almost the same speed as that. Thus, the paper PY is sent forward.

In order to make the conveyance by the pin tractor 14 dominant, the diameter of the driving roller 13 may be slightly smaller than the diameter of the main body roller 141.

By the way, the two pin tractors 14 are also marked with a mark MKT indicating the correspondence relationship between the pin PN provided on one pin tractor 14a and the pin PN provided on the other pin tractor 14b. .

The mark MKT makes it possible to identify each pin PN with different colors or shapes. For example, dots or arrows of each color such as black, red, green, blue, yellow, and purple can be printed or engraved. Moreover, you may attach | subject a number or code | symbol with respect to each pin PN.

Further, one mark MKT may be provided for a predetermined number of pins PN. For example, one mark MKT is provided for three pins PN.

The mark MKT indicates that the left and right pins PN with the mark MKT are in the same position in the longitudinal direction. Therefore, as long as it can indicate which of the left and right pins PN is at the same position, the number, position, shape, addition method, and the like of the mark MKT can be arbitrarily selected.

The recording head 16 performs color printing by the inkjet method on the surface of the paper PY immediately after being sent out by the paper transport device YH. The recording head 16 is attached to a carriage that reciprocates along a rail (not shown), and has a slight gap with the paper PY above the platen box 17 so as to cross the paper PY in the width direction. Move back and forth. The ink nozzles of the recording head 16 are opposed to the upper surface of the platen box 17, and the image GZ is printed by ejecting ink onto the paper PY adsorbed on the upper surface of the platen box 17.

Assuming that the transport direction of the paper PY is the X direction, the moving direction of the recording head 16 is the Y direction orthogonal thereto, and the surface of the paper PY is obtained by the movement of the paper PY in the X direction and the movement of the recording head 16 in the Y direction. An image GZ is printed on the XY plane.

In order for the printing position to be accurate, it is necessary that the image GZ drawn by the ink ejected from the recording head 16 and the position in the XY direction of the paper PY have a certain correct relationship. In addition, in order to accurately align the positions of the images GZ to be printed on both sides of the same sheet PY with high accuracy, the sheet PY is accurately set at an accurate position with respect to the sheet transport device YH. It needs to be transported accurately so that there is no.

In the paper transport device YH of the present embodiment, the paper PY is transported by the pin tractor 14, so that the position of the paper PY is accurately determined by the pin PN engaged with the punch hole PA of the paper PY, and there is no deviation during transport. .

Moreover, as will be described later, the shape of the pin PN is along the direction of movement of the paper PY after the movement of the pin PN from the root position on the front side of the pin PN when the punch hole PA of the paper PY starts to come out of the pin PN. The distance to the position on the front side of the pin PN on the line is the same as the movement distance of the root position on the front side of the pin PN.

That is, the shape of the pin PN moves in the direction in which the front side of the pin PN comes out in contact with the peripheral edge on the front side of the punch hole PA as the pin PN moves out of the state where the pin PN is inserted into the punch hole PA. It has a shape like this.

For this reason, the conveyance speed of the paper PY by the pin tractor 14 is the same as the peripheral speed of the drive roller 13, and the paper PY is smoothly fed out at a constant speed. The shape of the pin PN will be described in detail later.

Note that a fan 18 is provided in the lower part of the platen box 17, and the air inside the platen box 17 is exhausted by the fan 18, and the pressure is reduced. A large number of fine holes are provided on the upper surface of the platen box 17, and the paper PY is adsorbed by a negative pressure and is in close contact with the upper surface of the platen box 17. That is, the paper PY is conveyed in a state of being in close contact with the upper surface of the platen box 17.

The paper PY on which the image GZ is printed on the surface by the recording head 16 is discharged along the paper guide 19.

As shown in FIGS. 2 to 5, the drive roller 13 integrally has

drive shafts

13a and 13b extending linearly from both ends thereof. The

drive shafts

13a and 13b are rotatably supported at their ends by

bearings

21a and 21b attached to the body 11, and are driven to rotate by a power transmission mechanism (not shown).

The surface of the drive roller 13 is knurled so that an appropriate frictional force is generated between the drive roller 13 and the paper PY. Such a driving roller 13 may be integrated by, for example, providing a screw on the inner peripheral surface of both ends of a hollow pipe and screwing a boss or a screw shaft screwed into the screw.

The key 22 is fitted and attached to one drive shaft 13a in a key groove provided in the axial direction on the surface thereof. The pin tractor 14 a is provided with a key groove 23 that engages with the key 22. The key groove 23 engages with the key 22 and is movable in the axial direction along the key 22. The pin tractor 14a is provided with a set screw 24. After adjusting the axial position of the pin tractor 14a, the set screw 24 is tightened to fix the axial position.

The pin tractor 14b is also provided with a set screw similar to that of the pin tractor 14a, and the position is fixed by tightening the set screw after adjusting the position in the axial direction.

Also, between the drive roller 13 and the pin tractor 14a,

rollers

131 and 132 are inserted to fill the space between them. The

rollers

131 and 132 have the same outer diameter as that of the driving roller 13. The

rollers

131 and 132 are also provided with a key groove that engages with the key 22, and can move in the axial direction along the key 22. The

rollers

131 and 132 are provided with a set screw, and the position in the axial direction is fixed by tightening the set screw.

In addition, it is possible to select and use appropriate lengths, numbers, and the like of the

rollers

131 and 132 in the axial direction.

Such rollers

131 and 132 may be inserted into the drive shaft 13a with the drive roller 13 removed from the machine body 11 together with the

drive shafts

13a and 13b. Alternatively, the

rollers

131 and 132 may be divided into two and attached to the drive shaft 13a by being coupled with screws or the like.

5 and 6, the body roller 141 of the pin tractor 14 is provided with a plurality of pins PN at equal angular pitches. That is, the pin tractor 14 is a roller with a pin. The outer diameter of the main body roller 141 is the same as the outer diameter of the driving roller 13.

As shown in FIG. 6, the pin PN has a round shape whose outer peripheral surface is a circumferential surface and converges in a smooth curve from the root position TN to the tip position TS.

Next, the shape of the pin PN will be described in detail.

That is, as shown in FIG. 6, when focusing on the pin PN at the center of the figure, the pin PN is inserted into the punch hole PA of the paper PY, and the root position TN on the front side of the pin PN is the punch hole PA of the paper PY. It is the state which contact | connected the front peripheral part. When the outer diameter of the root position TN of the pin PN is DN and the inner diameter of the punch hole PA is DA, DA> DN. Therefore, a gap is formed between the root position TN on the rear side of the pin PN and the peripheral portion on the rear side of the punch hole PA.

As specific examples of dimensions, when the outer diameter of the main body roller 141 is about 28 mm, the maximum value of the outer diameter of the pin PN is about 3 mm, and the inner diameter of the punch hole PA is about 3.2 mm. The gap between the peripheral edge of the PA is about 0.2 mm. The height of the pin PN is about 2.5 mm.

In this state, the pin tractor 14 rotates to the right side (arrow M1 direction) in the figure. Thus, the paper PY is conveyed in the right direction (arrow M2 direction) in the drawing.

A pin PN that is one pitch ahead of the center pin PN in FIG. 6 (which may be referred to as “pin PNZ”) is just an imaginary surface MK extending from the outer peripheral surface of the pin PNZ and the tip. A ridge line intersecting the plane MH passing through the position TS is in contact with the front peripheral edge of the punch hole PA. That is, this state is the moment when the pin PNZ comes out of the punch hole PA.

The root position TN is a height position that varies depending on the position of the pin PN in the circumferential direction, but is ignored here because it is a minute difference.

The pin PN that is one pitch behind the pin PN may be described as “pin PNG”.

FIG. 9 shows a state in which the paper PY is conveyed along with the rotation of the pin tractor 14.

FIG. 9A is the same state as FIG. 6 described above. In this state, the root position TN of the pin PN and the punch hole PA are in contact with each other in a portion surrounded by a broken-line circle. FIGS. 9B to 9F show states where the pin tractor 14 is rotated in the direction of the arrow M1 by a predetermined angle. Next to FIG. 9F, the state returns to the state of FIG. In these drawings, the root position TN of the pin PN and the punch hole PA are in contact with each other in a portion surrounded by a broken-line circle.

In each state of FIGS. 9A to 9D, the root position TN of the pin PN and the punch hole PA are in contact with only one pin PN, but FIGS. 9E to 9F ), The root position TN of the pin PN and the punch hole PA are in contact with the two pins PN and PNG. During this time, the conveyance and positioning of the paper PY shift from the pin PN to the pin PNG.

During this time, the peripheral surface on the front side of the pin PN moves in a direction to come out in contact with the peripheral edge on the front side of the punch hole PA.

As shown in FIG. 10, in order to obtain the shape of the peripheral surface of the pin PN, the root position TN is the origin, the tangential direction of the surface of the main body roller 141 is the U axis, and the perpendicular direction is the V axis. The shape of the peripheral surface of the pin PN is determined by obtaining the coordinates of each point of the curve CV in such a UV plane.

As shown in FIG. 11, the U axis and the V axis move according to the rotation angle of the main body roller 141. When the root position TN of the pin PN is directly above the pin tractor 14, that is, when the pin PN is at the contact position between the main body roller 141 and the paper PY, the origin position is set to 0 °, and the rotation angle is 0 °. The angle is θ [degree]. What is necessary is just to obtain | require the coordinate of the contact position P with the paper PY about the U-axis and V-axis in various rotation angles (theta).

In FIG. 11, U is obtained as follows.

U = cos θ × D
= Cos θ x (BC)
= Cos θ × (r × tan θ-2πrθ / 360) (1)
V is obtained as follows.

V = EG
= (A−r) − (D × sin θ)
= (R / cos θ−r) − (r × tan θ−2πrθ / 360) × sin θ
(2)
In the above formula, r is the radius of the main body roller 141. Further, since it is assumed that the peripheral speed due to the rotation of the main body roller 141 and the conveyance speed of the paper PY are synchronized (synchronized), “C” that is the conveyance distance of the paper PY is a circumferential length corresponding to the rotation angle θ. Is equal to

FIG. 12 shows the coordinates of the contact position P at various rotation angles θ obtained as described above and plotted on the UV plane.

The outer peripheral surface of the pin PN is formed by rotating the curve CV shown in FIG. 12 around the center line TC of the pin PN.

In the curve CV shown in FIG. 12, the portion far from the origin is a line indicated by the virtual plane MK described above.

Also, the shape of the peripheral surface of the pin PN can be obtained by the following method.

That is, as shown in FIG. 13, the center line TC of the pin PN is the V axis, and the tangent line perpendicular to the V axis on the surface of the main body roller 141 is the U axis. The shape of the peripheral surface of the pin PN is determined by obtaining the coordinates of each point of the curve CV in such a UV plane.

As shown in FIG. 14, the U axis and the V axis move according to the rotation angle of the main body roller 141. The origin position is when the pin PN is directly above the pin tractor 14, that is, when the pin PN is at the contact position between the main body roller 141 and the paper PY, the rotation angle at this time is 0 degree, and the rotation angle from there is θ [ Degree]. What is necessary is just to obtain | require the coordinate of the contact position P with the paper PY about the U-axis and V-axis in various rotation angles (theta).

In FIG. 14, U is obtained as follows.

U = cos θ × D
= Cos θ x (CB)
= Cos θ × (2πrθ ″ / 360−r × tan θ) (3)
V is obtained as follows.

V = E + G
= (A−r) + (D × sin θ)
= (R / cos θ−r) + (2πrθ ″ / 360−r × tan θ) × sin θ
...... (4)
In the above equation, θ '' is
θ ″ = θ + θ ′ (5)
It is. Here, θ ′ is a deviation angle of the root position TN with respect to the center line TC of the pin PN. That is, the deflection angle θ ′ is obtained as follows.

θ ′ = arc sin (rp / r) (6)
Note that rp is the maximum value of the radius of the pin PN. When the maximum outer diameter of the pin PN is 3 mm, rp is 1.5 mm.

Similarly to the above, since it is assumed that the peripheral speed due to the rotation of the main body roller 141 and the conveyance speed of the paper PY are synchronized (synchronized), “C” which is the conveyance distance of the paper PY is set to the rotation angle θ. Equal to the corresponding circumference. However, in the equations (3) and (4), “C” is a circumferential length corresponding to an angle obtained by adding the deflection angle θ ′ to the rotation angle θ.

As the method for obtaining the coordinates of the contact position P, various methods other than those described above can be used. Further, the contact position P may be obtained by drawing. Moreover, you may obtain | require the approximate expression of the curve CV using a mathematical method. An appropriate program may be executed by a computer for the drawing or calculation.

The pin PN having the shape described above is a rotating body. Such a pin PN can be formed by cutting using a metal material or a synthetic resin material. Or you may shape | mold with a metal mold | die or may grind | polish after shaping | molding. Since the front half of the pin PN is important for positioning the paper PY by the pin PN, only that portion may be precisely finished.

The pin PN has a bullet shape, but may have a conical shape. In addition, the shape viewed from the tip position TS side is a circle, but may be a rectangle or a polygon instead of a circle.

The pin tractor 14 described above is a roller with a pin in which a plurality of pins PN are provided on the main body roller 141, but a timing belt may be used.

Next, the pin tractor 14B using a timing belt will be described.

In FIG. 15, the pin tractor 14 </ b> B includes a casing 31, a timing belt 34 that is stretched between two

rollers

32 and 33 and two

rollers

32 and 33 that are rotatably attached to the casing 31 with a bolt BT. A timing gear 35 is provided so as to be rotatable with respect to the casing 31 and is rotationally driven by the drive shaft 13a to rotationally drive the timing belt 34.

A pin PN that engages with a punch hole PA provided in the paper PY is provided on the outer peripheral surface of the timing belt 34.

The timing belt 34 is parallel to the paper PY between the timing gear 35 and the roller 33, and is gently inclined so as to be gradually separated from the paper PY between the timing gear 35 and the roller 32.

Above the pin tractor 14B, there is provided a sheet holding device SA including a holding roller 15B attached to the printer, a holding lever 43 provided to be rotatable about a shaft 44, a spring 44, and the like.

When the drive shaft 13a rotates, the timing gear 35 rotates integrally, and the timing belt 34 meshing with this rotates. As the timing belt 34 travels, the pin PN engaged with the punch hole PA travels the paper PY.

The paper PY is fed in the direction of the arrow M2 accurately in a parallel portion between the timing gear 35 and the roller 33 with the plurality of punch holes PA sufficiently engaged with the pin PN. At the inclined portion between the timing gear 35 and the roller 32, the timing belt 34 is gradually separated from the paper PY, and accordingly, the pin 36 is smoothly pulled out from the punch hole PA.

Note that the shape of the pin PN is a cannonball type as described above, and can be obtained as described with reference to FIGS.

It should be noted that the structure or shape of the pin tractor 14B can be various other than those described above. For example, a roller similar to the

rollers

32 and 33 is provided at a position where the timing gear 35 is provided, and the timing gear 34 is provided between the roller and the roller 32 to drive the timing belt 34.

Next, a method for printing the image GZ on both sides of the paper PY by the printer 1 will be described.

As described above, the paper PY provided with the punch holes PA for feeding at both ends, the drive roller 13 that rotates in contact with the paper PY, and the plurality of pins that engage with the punch holes PA A paper transport device YH having two

pin tractors

14a and 14b that are arranged at both ends of the drive roller 13 and are rotationally driven by a rotational drive force coaxial with the drive roller 13 is used.

The positions of the two

pin tractors

14a and 14b are adjusted in accordance with the position of the punch hole PA of the paper PY to be used.

The paper PY is set on the paper transport device YH, and in this state, the paper PY is transported at a speed synchronized with the movement of the pin PN, and an image GZ1 is printed on one surface HM1 of the paper PY (see FIG. 16A). .

When printing on one surface UM1 of the paper PY is finished, the paper PY is cut from the web at that position. The cut paper PY is turned over, set in the paper transport device YH, and in this state, the paper PY is transported at a speed synchronized with the movement of the pin PN, and the image GZ2 is printed on the other front surface (back surface) UM2 of the paper PY [ See FIG. 16B].

At this time, the image GZ2 printed on the back surface UM2 of the paper PY is an image obtained by turning over the image GZ1 printed on the front surface UM1, that is, a mirror image. That is, the image GZ2 is an image having the same content as the image GZ1, and is an image obtained by horizontally inverting the image GZ1. Note that when the orientation of the top and bottom of the paper PY is reversed, the image GZ2 may also be reversed.

The images GZ1 and GZ2 are printed so as to overlap at the same position. That is, in the state viewed through the paper PY, the position of the origin GG2 of the image GZ2 printed on the back surface UM2 is the same position as the position of the origin GG1 of the image GZ1 printed on the front surface UM1.

That is, for example, if one punch hole PA11 in the paper PY is used as a reference, the positional relationship between the punch hole PA11 and the origin GG1 or GG2 may be the same on the front and back of the paper PY.

Also, the pin PN11 inserted into the punch hole PA11 when the front surface UM1 is printed is inserted with the opposite punch hole PA21 on the left and right sides when the back surface UM2 is printed. Therefore, for the image GZ2, if the upper left position is the origin GG21, the positional relationship between the origin GG21 and the pin PN11 may be defined. Since the positional relationship between the origin GG2 and the origin GG21 is known for the image GZ2, the positional relationship between the origin GG21 and the pin PN11 may be set based on these.

In the paper transport device YH, the position of the paper PY is accurately and accurately determined and transported by the pin tractor 14, so that the print positions of the images GZ1 and GZ2 on the front and back are determined and printed as described above. , They match exactly without shifting.

That is, the double-sided printing of the image GZ can be performed with high positional accuracy, regardless of whether the paper PY is large or small.

As described above, according to the paper transport device YH, it is possible to perform double-sided printing of images with high positional accuracy even with a large size paper PY. Further, even if the paper PY is large in size, the paper PY can be conveyed with high positional accuracy.

In addition, what is necessary is just to cut and isolate | separate the both ends where the punch hole PA was provided about the paper PY in which double-sided printing was finished.

Further, it is preferable to adjust the density of the image GZ2 printed on the back surface UM2. *

FIG. 17 shows the relationship between the density of the back side image (output image) GZ2 with respect to the front side image (input image) GZ1.

17, the dynamic range of the output image density is narrower than the density of the input image. That is, the density of the output image is compressed to ND1 to ND2% with respect to the input image. That is, the density distribution is limited so that the density ND1 to ND2 of the intermediate portion in the gray scale or the lightness scale of each primary color is obtained.

However, for the input image density of about 0 to 2%, that is, for the brightest density, the brightest density can be obtained similarly. This is because it is necessary to leave the brightest part as it is.

The specific range of the concentration ND1 is, for example, about 10 to 20%, and the concentration ND2 is, for example, about 50 to 80%. Therefore, the density of the output image can be limited to a range of about 20 to 70% with respect to the input image. In this way, by limiting the density of the output image and using this as the density of the image GZ2 for the back side, when the images printed on both sides of the paper PY are observed with transmitted light, they are clearly observed at a natural density. it can.

Note that a marker for detecting image misalignment may be provided at an end in the width direction of the image GZ. In that case, the marker may be automatically printed on the outer periphery of the drawing size. In addition, when the printing position is shifted after printing is started, the printing position may be corrected by operating the keyboard of the computer.

Further, it is also possible to detect a deviation of the printed image GZ using a camera equipped with a CCD or the like and correct the printing position based on this. In this case, for example, the image GZ1 is printed on the surface of the paper PY, the image GZ1 is photographed with a camera, and the printing position is measured. When printing the image GZ2 on the back side of the paper PY, the image GZ2 is photographed with a camera, the print position is measured, and the amount of deviation is corrected so as to coincide with the print position of the image GZ1.

When correcting the printing position, for example, the origin GG is moved in the main scanning direction (X direction), and the position correction signal is transmitted to the motor that drives the driving roller 13 in the sub scanning direction (Y direction), for example. Should be output.

By doing so, the printing positions of the images GZ1, 2 can be automatically matched, and the images GZ1, 2 can be automatically printed on the front and back of the paper PY.

In the present embodiment, the same images GZ1 and GZ2 are printed on both sides of the paper PY, but different images may be printed instead of the same image. Further, the printing may be performed twice or three times or more on the same surface of the paper PY without printing on both sides of the paper PY. For example, an additional image may be printed on the same surface of the image GZ1 printed on the surface of the paper PY. When an additional image is printed, the color may be changed to gold, for example. Even when printing is performed a plurality of times on the same surface of the paper PY, the position of the paper PY can be maintained with high accuracy, so that the position of the image to be printed can be accurately aligned.

In the embodiment described above, the pitch of the punch holes PA provided in the paper PY is the same as the pitch of the pins PN, but may be smaller than the pitch of the pins PN.

In the embodiment described above, the structure, shape, size, number, material, composition of the driving roller 13, the pin tractor 14, the pressure roller 15, the pin PN, the paper PY, the punch hole PA, or the whole or each part of the printer 1 are used. These can be appropriately changed in accordance with the spirit of the present invention.

Claims

A method for printing an image on both sides of paper,
Paper with feed punch holes at both ends, and
A driving roller that rotates in contact with the paper, and a plurality of pins that engage with the punch holes, are arranged at both ends of the driving roller and are driven to rotate by a rotational driving force that is coaxial with the driving roller. Using a transfer device with two pin tractors,
The paper is set in the transport device, and in that state, the paper is transported at a speed synchronized with the movement of the pin to print an image on one surface of the paper,
The paper that has been printed on one surface is turned over and set in the transport device, and in that state, the paper is transported at a speed synchronized with the movement of the pins to print an image on the other surface of the paper. ,
A method for printing on both sides of a sheet.
The shape of the pin is
The distance from the root position on the front side of the pin when the punch hole of the paper starts to come out of the pin to the position on the front side of the pin on the line along the moving direction of the paper after the movement of the pin, It is a shape that is equal to the movement distance of the root position on the front side of the pin,
A method for printing on both sides of a sheet according to claim 1.
The two pin tractors are provided with marks indicating the correspondence relationship of the conveyance direction positions of the pins provided on one pin tractor and the pins provided on the other pin tractor,
The paper is marked with a mark indicating the correspondence between the positions of the punch holes provided at one end and the punch holes provided at the other end.
The method of printing on both surfaces of the paper of Claim 1 or 2.
A driving roller that rotates in contact with the paper;
Two pins that have a plurality of pins that engage with feed punch holes provided at both ends of the paper and that are arranged at both ends of the drive roller and are rotationally driven by a rotational drive force coaxial with the drive roller A tractor,
A pressing member that is disposed to face the driving roller and the pin tractor and presses the paper toward the driving roller and the pin tractor,
The paper is transported at a speed synchronized with the movement of the pin, and the paper is sent forward by the rotation of the driving roller.
A paper transport device for a printer.
The shape of the pin is
The distance from the root position on the front side of the pin when the punch hole of the paper starts to come out of the pin to the position on the front side of the pin on the line along the moving direction of the paper after the movement of the pin, It is a shape that is equal to the movement distance of the root position on the front side of the pin,
The paper conveying device of the printer according to claim 4.
The shape of the pin is
When it comes out from the state inserted in the punch hole, it is shaped to move in the direction in which the front side is in contact with the peripheral edge on the front side of the punch hole as it moves.
The paper conveying device of the printer according to claim 4.
The two pin tractors arranged at the both end portions are marked with a mark indicating the correspondence relationship between the pins provided on one pin tractor and the pins provided on the other pin tractor in the conveying direction.
A paper conveying apparatus for a printer according to claim 4.
At least one pin tractor of the two pin tractors is provided such that its axial position is adjustable.
A paper conveying device for a printer according to claim 4.
The pin tractor is engaged with a key provided on the drive shaft in a rotational direction with respect to a drive shaft provided coaxially with the drive roller, and is movable in the axial direction along the key.
The paper transport device for a printer according to claim 8.
The pin tractor is
The plurality of pins are provided on an outer peripheral surface, and are rollers with pins provided coaxially with the drive roller.
A paper conveying apparatus for a printer according to claim 4.
The pin tractor is
A casing,
Two rollers rotatably mounted on the casing;
A timing belt provided with the plurality of pins on an outer peripheral surface and stretched between the two rollers;
A timing gear that is rotationally driven by a rotational driving force coaxial with the driving roller and causes the timing belt to travel,
The timing belt has a parallel portion that travels in parallel with the paper, and an inclined portion that gently slopes away from the paper.
A paper conveying apparatus for a printer according to claim 4.
Printer paper conveyed by a drive roller and pin tractor,
At both ends in the width direction, feed punch holes with which the pins of the pin tractor engage are provided in a row along the length direction, respectively.
Marks indicating the correspondence between the positions of the punch holes provided in one row and the punch holes provided in the other row are marked,
Printer paper characterized by that.