JPH10138528A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable continuous multicolor printing of a large number of printing sheet at a high speed. SOLUTION: A drum 10 rotatable at a constant peripheral speed, a medium holding means 20 for holding a printing medium M to the outer peripheral surface 11 of the drum 10 and respective color nozzle units 200 arranged so as to be positionally shifted in the rotary direction of the drum 10 and having a large number of ink jet nozzles 207 are provided and respective color inks are sprayed on the printing medium M during the rotary movement along with the drum 10 from the selected color ink jet nozzles 207 to enable color printing and, further, a negative pressure holding means 21 for holding the medium holding means 20 by utilizing the negative pressure in the drum through the suction holes 12 mode through the drum and a grasping pawl holding means 41 for pressing and holding the peripheral part of the printing medium M held under negative pressure to the outer peripheral surface 11 of the drum 10 by using a grasping pawl are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer capable of continuously printing a large number of sheets at high speed in multicolor printing.

[0002]

2. Description of the Related Art Along with the spread of personal computers, printers for color printing have been spreading. Many color printers are known as serial type inkjet printers.

Referring to FIG. 15, an ink jet printer 500 includes a print head 501, a moving unit 510 for reciprocating the print head 501 in the X direction shown in FIG. 15A, a control unit and a paper feeding unit (all not shown). Is formed from.

[0004] The print head 501 includes a head case 503.
Consisting of nozzle units 502 for each color stored in
The nozzle unit 502 for each color has Y shown in FIG.
It has a large number of ink jet nozzles for each color arranged at a pitch P (1/300 inch) necessary for obtaining a predetermined resolution (for example, 300 dpi) in the direction. Each ink jet nozzle is directed downward, and can spray each color ink on a sheet (printing medium) M which is fed downward by one line in the sheet longitudinal direction, that is, in the Y direction shown in FIG. 15B.

[0005] In this specification, "printing" includes:
Drawing (printing) of images and the like in addition to characters and symbols is also included.

[0006] An ink cassette 504 is detachably attached to the head case 503. Generally, there are two integrated ink cassettes for each color (Y, M, C) and an ink cassette for black (B).

The moving means 510 includes a carrier 505 on which the head case 503 can be mounted, a guide rod 511,
A sprocket 512 and a timing belt 513,
The print head 501 is formed by a stepping motor (not shown) or the like, and can reciprocate in the X direction in the paper width direction.

In the ink jet printer 500, when the paper M is supplied in the Y direction, the carrier 505 is moved forward in the X direction at a predetermined speed along the guide rod 511, and the color ink is sprayed from the ink jet nozzles for each color. Perform printing (printing). When the one-line printing is completed, the carrier 505 is moved backward, and then the sheet M is fed one line and moved forward again to proceed to the two-line printing. Less than,
By repeating this, one sheet of paper can be printed in color. The paper M on which color printing has been performed is discharged to a discharge space S on the mounting table at the front side of the printer.

A laser type color printer is known as a serial type ink jet printer. In FIG. 16, a laser color printer 600
Are process means 610 for each color (yellow Y, magenta M, cyan C, black B) in the main body case 601.
Y, 610M, 610C, and 610B are arranged in the Y direction, and the paper M is transported in the Y direction through each unit 610 using the transport unit 620.

Each process means 610 includes a photosensitive drum 61
1 (Y, M, C, B) around the laser beam emitter,
A charging device, a developing device, a transfer device, a waste toner collecting device, a static eliminator, and the like are provided, and each color is printed (printed) on the paper M. Specifically, an electrostatic latent image is drawn on the photosensitive drum 611, and each color toner is attached to this. Then, the toner image is transferred onto the sheet M using a transfer device, and is fixed using a heat fixing device (not shown) at the most downstream side in the Y direction.

[0011]

By the way, color printing using the ink jet printer 500 is very slow. It takes, for example, 5 to 10 minutes or more to perform high-resolution color printing on one sheet (for example, A4 size). In some cases, the printing speed is higher than the above value by reducing the size of the ink cassette. However, this method is meaningless because the interval for ink replacement is short and a continuous printing operation of, for example, 200 or more sheets cannot be performed. Further, since the carrier 505 on which the large ink cassette 504 is mounted is repeatedly reciprocated in the X direction, the noise is high and it is difficult to eliminate the noise.

On the other hand, a laser color printer 60
A value of 0 indicates that A4 size color printing can be performed in, for example, 15 to 20 seconds. That is, the number of sheets that can be printed in one minute during continuous printing is four. That is, 4 ppm
It is. In addition, since the photosensitive drum 611 is in a rotational motion and the sheet is continuously fed in one direction (Y), the noise is relatively low. However, since the expensive process means 610 must be provided in quadruple, it is large and expensive.

Thus, the ink jet printer 500
Then, for example, there is no problem when printing several postcards at home, but the required printing speed for colorization in a general office cannot be satisfied. Further, the laser color printer 600 cannot be sufficiently filled.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer capable of performing multicolor printing at a high speed and capable of continuously printing many sheets.

[0015]

The color printers (500, 600) having the above-mentioned conventional structure are analyzed in terms of printing speed.

First, for example, considering printing on A4 size paper (surface), the conventional ink jet printer 500 prints one line while reciprocating the nozzle unit over the entire length in the line (X) direction, and after printing one line, Move to the next row via feed in column (Y) direction. Therefore, it takes 5 to 10 minutes to complete the printing of the surface. On the other hand, in the case of the laser printer 600, one line is printed so as to be printable by a high-speed line (X) feed, which is a main scan by a laser beam, and the next line is moved to the next line by using a column (Y) direction feed by drum rotation. Move on.
Therefore, although the printing of the surface is completed earlier than the case of the ink jet printer 500, the cleaning of the remaining toner on the outer peripheral surface (photosensitive surface) of the drum, the removal of electricity, the recharging, etc. must be performed to complete the printing of one surface. . That is,
Since the outer peripheral surface of the drum is reused many times, there is a certain restriction in increasing the rotation speed of the drum, so that it is limited to about 15 seconds.

Thus, any of the printers 500, 6
00 is also a concept of completing printing of column printing as a result of stacking of line printing. In other words, it can be estimated that if the line direction and the column direction are simultaneously advanced, the printing speed can be significantly increased. Therefore, first, the conventional printers 500 and 600
We will analyze in more detail the factors that hinder printing speedup and discuss the feasibility of the simultaneous progress method.

The ink jet printer 500 is based on the premise that the nozzle units 502 for each color are reciprocated over the entire width of the sheet M in the X direction, so that the nozzle units 502 for each color and the ink cassette 504 are integrated. . In other words, since the nozzle unit 502 for each color and the ink cassette 504 must be integrated, the entire unit must reciprocate in the full width direction. In other words, since the entire print head 501 including the sophisticated nozzle unit 502 for each color and the large and heavy ink cassette 504 is reciprocated in the X direction, the printing is interrupted during the backward movement, so that high-speed printing is extremely difficult. And the noise increases due to the linear motion and the reversal of the moving direction.

Each of the ink jet nozzles has a pitch P (1/30) required to obtain a predetermined resolution (for example, 300 dpi) regardless of the type of the ink jet system.
(0 inch) and are arranged in the Y direction and the X direction is equivalent to one dot. In other words, in consideration of speeding up of color printing, the nozzle unit 5 for each color having a length over the width of the paper is considered.
What is necessary is to use a so-called line printer structure that prints one dot line at a time using 02. However, it is technically and costly difficult to manufacture an integrated nozzle unit 502 for each color nozzle unit that is uniform in finishing accuracy over the entire length thereof. The compromise is made by moving over the entire length in the width (X) direction.

Therefore, the time required for the start-stop-start for each carrier is much longer than the operation time (for example, 0.1 to 0.5 mSec) of each ink jet nozzle, so that the moving speed in the X direction is Can not be faster. This is an obstacle to speeding up color printing. At the same time, the print quality is degraded due to the feed error.

Therefore, as one concept, for example, the conventional nozzle unit 502 for each color is urged as a nozzle unit element for each color, and a plurality of nozzle unit elements for each color are referred to as Y.
It is conceivable to construct a simulated line printer structure by displacing in the X direction and partially arranging in the X direction. In this way, the pitch P between the inkjet nozzles of each nozzle unit element is set to 1/75 inch, for example, and the inkjet nozzles are reciprocated synchronously in the X direction while moving one pitch within the pitch P (1/75 inch).
If you print every / 300 inch, the resolution is 30
The time for one line dot at 0 dpi is about 0.4 seconds (= 0.1
mSec × 4 dots). That is, logically, Y
For example, one sheet of 3000 dots can be printed in about 1.2 seconds.

However, the large and heavy ink cassette 5
It is impractical to arrange a plurality of nozzle units (elements) for each color integral with the element 04 in the Y direction while partially overlapping each other in the X direction. In addition, the intermittent paper feed in the Y direction is also a linear motion and the start-stop operation is repeated. It also causes noise.

This can be understood as a reversal of the difficulty in increasing the speed of color printing from the fact that the conventional ink jet printer (500) leaves the printed paper M in the discharge space S as it were. In other words, the idea is to naturally dry the ink on the previous paper M by using the long time required until the end of color printing on the next paper M. Therefore, since it is meaningless to set, for example, 30 or more sheets M, the apparatus is not configured to be able to set 30 or more sheets M.

As another concept, a plurality of (N) nozzle units for each color are separated in the X direction and reciprocated in the X direction by 1 / N of the entire width of the print medium. It is possible. However, in a state where the large and heavy ink cassette 504 is integrally mounted, the practicality is lacking in view of the necessity of adding or modifying a mechanism accompanying the ink cassette 504.

On the other hand, in the case of the laser color printer 600, since the rotational movement of the photosensitive drum 611 is used, the speed can be increased at least five times or more compared to the inkjet printer 500 with low noise. However, in general, the diameter of the photosensitive drum 611 is, for example, 20 mm and about 4 ppm from the viewpoint of demand for miniaturization and cost reduction. Therefore, the color printing time for one A4 size sheet is, for example, 15 seconds. As described above, a color printing speed several times to several tens of times higher than that of the ink jet printer 500 can be achieved, but it is extremely difficult to respond to a request to perform color printing of one A4 size sheet in 10 seconds or less, for example. . In addition, the problem of increasing the size cannot be solved.

The ink jet printer 50
Assuming that 0 is adopted, the relative movement of the nozzle unit 502 for each color and the paper M in the Y direction is preferably a rotational movement with respect to a linear movement, and the relative movement in the X direction is set to a high speed. Conventional inkjet printer 5 if color printing in the Y (column) direction is possible
It should be possible to achieve a significantly higher printing speed as compared with 00. Noise can also be reduced. In addition, if the printing of each color can be performed using one drum during the relative rotation movement of the nozzle unit 502 for each color and the paper M, the size can be reduced to 1/4 times as compared with the laser color printer 600. It is. In addition, it is considered that the drying of the ink on the paper M can be promoted by utilizing the relative flow with the ambient outside air during the relative rotation transfer.

Here, if the paper M can be rotated at a high speed in the longitudinal (Y) direction, it is possible to wipe out the factor that hinders the high-speed color printing related to the feeding of the paper M and the nozzle unit for each color in the Y direction. In particular, if the paper M is rotated by a drum or the like, the nozzle units for each color can be easily displaced in the Y direction (rotation direction) instead of the X direction. It becomes possible. Therefore, it is possible to form an apparently integrated nozzle unit for each color by directly or indirectly arranging a plurality of short and small color nozzle unit elements in series in the X direction. That is, an apparent line printer structure can be constructed.

Further, if the ink cassette can be arranged at a remote position, the weight of the entire print head can be reduced, and from this point, the moving speed in the X direction can be further increased. In other words, it is possible to wipe out the most influential factor for speeding up color printing, which is related to the feeding of the paper M and the nozzle unit for each color in the X direction. In addition, the short and small nozzle unit elements for each color can be easily realized in terms of both technical and cost aspects. Further, since the size of the ink cassette can be increased, a continuous printing operation can be performed for a large number of sheets (for example, 200 sheets or more).

According to the results of the above examination, if the print medium can be reliably held and peeled from the drum, the printing in the row direction and the printing in the column direction can proceed simultaneously to increase the printing speed and the continuous printing operation. Can be achieved.

Thus, according to the present invention, the supplied print medium is formed so as to be able to reliably and stably hold the supplied print medium on the drum by utilizing the negative pressure and mechanically sandwiching the peripheral portion thereof. The relative movement in the longitudinal direction of the print medium with respect to the nozzle unit uses the rotational movement of the drum, and the nozzle unit for each color is a combination of a plurality of nozzle unit elements for each color that can reciprocate a short distance, for example, the pitch between inkjet nozzles. It is possible to realize an apparent line printer structure by being able to be formed integrally or integrally, and it is possible to realize a reciprocating movement in the X direction and a relative rotation movement in the Y direction while speeding up each color while performing the relative rotation movement. It is formed so as to be printable by using a nozzle unit for printing.

That is, according to the first aspect of the present invention, there is provided a drum rotatable at a constant peripheral speed, a medium holding means for holding a print medium on the outer peripheral surface of the drum, and a drum which is displaced and arranged in the rotational direction of the drum. And a nozzle unit for each color having a large number of ink jet nozzles. The ink jet nozzle for each color is sprayed from the selected ink jet nozzle for each color on the print medium rotating and moving together with the drum so that color printing can be performed. A negative pressure suction holding means for sucking and holding a negative pressure through a suction hole penetrating the inside and outside of the drum and utilizing a negative pressure inside the drum, and a peripheral portion of the printing medium held by the negative pressure suction using a clamping claw to form the drum. And holding means for holding the pressing claws on the outer peripheral surface.

In this invention, the supplied printing medium is:
The negative pressure suction holding means uses the negative pressure through the suction hole penetrating the inside and outside of the drum to hold the negative pressure suction on the outer peripheral surface of the drum, and the holding portion presses and holds the peripheral portion of the print medium. Thus, when the drum is rotated at a constant peripheral speed, the nozzle units for each color, which are displaced in the rotation direction of the drum, and the print medium relatively rotate and move in the longitudinal direction of the print medium. It has extremely low noise and can rotate and move at high speed. Therefore, for example, each color nozzle unit element that forms each color nozzle unit that is misaligned and arranged in the drum rotation direction, using the selected inkjet nozzle for each color of the integrated color nozzle unit in the width direction of the print medium, or Using the selected ink jet nozzle of each color nozzle unit element that can simultaneously move the nozzle unit elements for each color simultaneously in the drum axis direction, for example, by the pitch between the ink jet nozzles, printing can be performed on the print medium securely held on the drum. Therefore, it is possible to achieve a large multi-color printing speed and achieve a large number of sheets (for example, 20
(0 sheets).

The invention according to a second aspect of the present invention is an ink jet printer, wherein the holding claw holding means is formed so as to be able to hold at least the leading end side of the printing medium held by the drum under negative pressure. .

According to the invention, the holding claw holding means holds the leading end side of the print medium held by the negative pressure suction. Therefore, the same operation and effect as those of the first aspect of the invention can be obtained. Further, mechanical holding to the drum becomes easy, the structure can be simplified, and the printing surface is not affected.

Further, according to the present invention, there is provided a medium peeling device for peeling a print medium from a drum, comprising a peeling claw capable of inserting the print medium sucked and held by the drum between the drum and the print medium. Removal timing adjustment control means for removing the negative pressure suction holding force by the negative pressure suction holding means and the clamping force by the clamping claw holding means at a predetermined timing prior to the peeling operation by the medium peeling means. An ink jet printer comprising:

In this invention, when the removal timing adjustment control means removes the negative pressure suction holding force by the negative pressure suction holding means and the holding force by the holding claw holding means at a predetermined timing, the separation claw of the medium peeling means is removed. Is inserted between the drum and the print medium to separate the print medium from the drum.

Therefore, in addition to having the same effects as the first and second aspects of the present invention, the print medium after multicolor printing can be reliably and stably peeled off from the drum. This also promotes high-speed printing.

[0038]

Embodiments of the present invention will be described below with reference to the drawings. This inkjet printer is shown in FIG.
-Drum 1 rotatable at a constant peripheral speed as shown in FIG.
0, a medium holding means 20 for holding the print medium M on the outer peripheral surface 11 of the drum 10, and a nozzle unit 200 for each color which is displaced in the rotational direction of the drum 10 and has a large number of ink jet nozzles 207. Provided,
The ink for each color is sprayed from the selected ink jet nozzle 207 to the print medium M rotating and moving together with the drum 10 to form a color printable ink, and the medium holding means 20 is inserted through the suction hole 12 penetrating inside and outside the drum. Further, the negative pressure suction holding means 21 for holding the negative pressure by using the negative pressure inside the drum and the peripheral portion of the print medium M held by the negative pressure suction are pressed and held on the outer peripheral surface 11 of the drum 10 using the holding claws. The holding means 41 is formed of a holding claw.

First, the overall configuration will be described with reference to FIG. A medium supply means 90 is provided on one (right) side of the high-speed rotatable drum 10, and a medium discharge / conveyance means 160 is provided on the other (left) side. The nozzle units 200C, 200M, 200Y, and 200B for the respective colors are displaced in the rotation (Y) direction of the drum 10, and a medium discharge / convey means 160 is provided above the nozzle units.

The medium supply means 90 can supply the print medium M fed from the paper supply means 60 to the drum 10 after correcting the attitude of the print medium M. The supplied print medium M is held on the outer peripheral surface 11 of the drum 10 by the medium holding unit 20 including the negative pressure suction holding unit 21 and the holding claw holding unit 41.

The print medium M after color printing is peeled off from the drum 10 (11) by the medium peeling means 140 (141) and delivered to the medium discharge / conveying means 160 side via the medium delivering means (141). The medium is discharged and conveyed in a predetermined direction by the medium discharge and conveyance means 160. The direction switching unit 190 is capable of selectively switching between the discharge conveyance with the print surface facing up to the discharge tray 192 and the discharge conveyance with the print surface facing down to the upper discharge tray 193.

The ink drying means 1 is provided around the drum 10.
30 (131, 132) for directly or indirectly drying the ink on the printing medium M held on the drum 10 for speeding up printing, and for facilitating charging of the supplied printing medium M, etc. Can be forcibly preheated. Further, an ink drying unit 181 for forcibly drying the ink on the print medium M is provided at the end (left) side of the medium discharge / conveyance unit 160 in order to complete the drying of the ink.

Each color nozzle unit 200C, 200
M, 200Y, 200B and the ink supply means 210 are arranged separately. Therefore, the unit moving means 11
0 indicates that the nozzle unit 200 for each color, which has been reduced in size and weight, can be rapidly reciprocated in the width (X) direction of the print medium M, that is, in the axial direction of the drum 10. In addition, the nozzle units 200 for each color can be moved back and forth in the left-right direction in FIG. 2 to the drum 10 (11) by the moving unit 220, and the ink jet nozzles 207 for each color are covered with the cap 246 in the separated state to dry the ink. It is formed to be preventable. The cap 246 is moved up and down by cap lifting means 240. In addition, the drive is controlled by the control unit 250 as a whole.

Each of these means is stored in the main body case 1. The upper case 2 (discharge roller 2R) forming the upper discharge tray 193 can be opened as shown by a two-dot chain line in FIG.

In the drum 10, the printing medium M (plain paper, OHP paper, etc.) wound and held on the outer peripheral surface 11 is Y-shaped.
In this embodiment, the drum d has a diameter d of 130 mm and a drum axis (shaft 10).
It is possible to rotate at a constant rotation speed (120 rpm) enabling continuous printing of 20 ppm around S). That is, the drum 10 can make one rotation in 0.5 seconds. The drum 10 is driven to rotate by a main motor 93 composed of a servomotor having excellent high-speed response and constant speed.

More specifically, as shown in FIG.
The shaft 10S is rotatably mounted on the left and right brackets 5L and 5R via bearings.
Is rotated about an axis (10S) via a sprocket, a timing belt or a gear.

That is, the speed at which the printing medium M is moved in the column (Y) direction is significantly higher than that of the conventional example (600) and a constant peripheral speed (816 mm / Sec = 120π).
d / 60). This high peripheral speed can also be used to promote natural drying of the ink. Since the outer peripheral length is 408 mm (= πd), the A4 size (length:
(297 mm, width: 210 mm) can be held with a margin in the length direction thereof, and a print medium (M) longer than that can be held. The length in the drum axis direction is about 220 mm, which is longer than the A4 size (210 mm). The drum 10 has a hollow (10E) cylindrical shape such as an aluminum alloy and is grounded.

The diameter d of the drum 10 is preferably 100 mm or more in order to obtain a high peripheral speed capable of holding a printing medium M of A4 size or more and promoting ink drying.

Since each color nozzle unit 200 is provided separately from each ink supply means 210 (ink cassette 211), it can be integrally formed as a combination of a plurality (N) of nozzle unit elements 205 for each color. In this embodiment, in order to secure technical and cost advantages, four (= N) nozzle unit elements 205 shown in FIG.
A, 205B, 205C, and 205D are arranged as being displaced in the rotational movement (Y) direction of the drum 10. In other words, the nozzle unit 200 for each color
As shown in FIG. 4, N (=) in the drum axis (X) direction.
4) It is integrally formed from the divided nozzle unit elements 205A to 205D. Each nozzle unit element 205
The length of the divided lines of A, 205B, 205C, 205D is
These are S1, S2, S3, and S4 shown in FIG.

More specifically, the nozzle unit elements 205A,
The nozzle unit 205C and the nozzle unit elements 205B, 205D are spaced apart in the drum axis direction, that is, in the X direction, and displaced in the Y direction via the connection support bar 204, and are indirectly shifted in the X direction as a whole in the Y direction. Are arranged in a so-called staggered shape.

However, the pitch PT between the ink jet nozzles
Can be arbitrarily selected, so that if the pitch PT between inkjet nozzles is increased, each nozzle unit 200 can be formed as an integral type extending in the X direction.

Each nozzle unit element (205A) includes:
A large number (159) of inkjet nozzles 207a to 207n are arranged at a constant pitch PT (1/75 inch) within a length Lxa (2.11 inches). Height (Figure 4
Ly in the vertical direction) is 9 mm. X (X1, X2)
Nozzles 2 at each end of each nozzle unit element 205 adjacent in the direction and displaced in the Y direction
A constant pitch PT (1/75 inch) is maintained between 07n and 207a.

The nozzle unit 200 for each color is Y
It is arranged so as to be displaced in the direction by a predetermined pitch Yp (for example, 20 mm). In this embodiment, the arrangement order from the upstream side to the downstream side in the Y direction is as follows: cyan C, magenta M, yellow-Y, black B (200C, 200C).
M, 200Y, 200B).

The multicolor nozzle unit 200 has four nozzles.
Although they are used for colors (C, M, Y, B), they can be displaced in the Y direction, so that it is easy to arrange more than six colors, for example, by adding light red and blue. Thus, it is possible to execute clearer multi-color printing with higher quality.

Further, each color nozzle unit 200C,
Each of the inkjet nozzles (for example, 207a) corresponding to 200M, 200Y, and 200B, that is, each of the nozzle unit elements 205 is at the same position (the position on F1 in FIG. 4) in the drum axis (X) direction. Thus, in this embodiment, the mounting member 11 shown in FIG.
2 and is attached to the reciprocating mechanism 111 via. Therefore, each color dot (inkjet nozzle) can be accurately overlapped in the X direction. That is,
Each column is identical.

Furthermore, the nozzle unit 200 for each color
Since C, 200M, 200Y, and 200B are displaced in the rotation (Y) direction of the drum 10, each ink jet nozzle 207 is disposed on each normal line to the drum 10 so that the drum 10, that is, the print medium M The size and shape of the dots D formed by the sprayed color ink are made the same to maintain and improve the printing quality. The gap between the tip (spray hole) of each ink jet nozzle 207 and the drum 10 is, for example, 1 mm during the printing operation.

As shown in FIG. 11, the ink supply means 210 for supplying the respective color inks to the respective color nozzle units 200 includes an ink tank 213 having a filter 214 and a liquid level fixing means provided in the ink tank 213. 2
12, an ink supply tube 215 connecting the ink tank 213 and the nozzle unit 200 (205), and an urging means 21.
6. Ink return tube 217 and tube opening / closing means 2
18 The ink cassette 211 has a larger amount (for example, 200C) than the conventional example ((10 to 20CC)).
C or more).

When each urging means 216 is driven in a state where the ink return tube 217 is closed by each tube opening / closing means 218, the color ink from the ink tank 213 is added to the corresponding color nozzle unit 200 (ink buffer 206). Pressure can be supplied (energized), and by priming or spitting as it is, air bleeding near each nozzle and clogging of each nozzle can be prevented. After that, if the ink return tube 217 is opened,
Air can be removed from the ink buffer 206. further,
The urging means 216 is stopped and the tube opening / closing means 218
When printing is performed with the ink return tube 217 opened, the ink reduced by the ink jet is automatically supplied from the ink tank 213 to the ink buffer 206 via the ink return tube 217 by the capillary effect. The ink level in the ink tank 213 is
The liquid level is kept constant by the liquid level fixing means 212.

As shown in FIG. 12, each biasing means 216
A rotary type having a plurality of (four) pressing rollers 216R shown in FIG. 2B and rotated by a motor 216M is engaged with each ink supply tube 215 (rotation pressing engagement) to convert each color ink into the corresponding color. (Pressurized supply) to the nozzle unit 200 side. The tube opening / closing means 218 is a rotary type having one pressing roller 218R. In addition, it is good also as a structure by a solenoid piece etc.

Further, in this embodiment, the height difference between the ink tank 213 for each color (specifically, the ink liquid level) and the ink discharge port (spray hole) of the nozzle unit 200 for each color is slightly different depending on the ink characteristics. Adjusted. This is to stabilize even higher quality printing by making the ink jet characteristics (meniscus) uniform. The ink tanks 213 for each color are disposed at a position lower than the ink discharge ports of the nozzle unit 200 for each color, and the ink tanks 213 for each color are opened to the atmosphere during the printing operation.

The spray control element 208 is appropriately selected in accordance with the ink jet system.
A predetermined amount of ink can be sprayed by using the shear deformation of 07. The operation time required from the end of the printing of the previous dot to the end of the printing of the subsequent dot is 0.1 mSec (1 msec).
0 KHz). It should be noted that an ink-jet method such as electric / thermal conversion, electric / mechanical conversion, etc. may be adopted.

As described above, since the ink tank 213 and the ink cassette 211 having a large capacity, a large weight and a large size can be arranged separately from the nozzle unit 200 for each color, the nozzle unit 200 for each color (the nozzle unit element 205). Can be densely arranged in the X direction and the Y direction, and the size and weight can be reduced as compared with the case of the conventional example (500).
Further, since the interval for replacing the ink cassette can be lengthened, the continuous printing operation time can be greatly increased.

Therefore, the nozzle unit 200 for each color
(Nozzle unit element 205) can be synchronously moved in the X direction at a light load and at a high speed. The unit moving means 110 for this purpose is formed of a reciprocating mechanism 111 and a motor unit 121 having a reciprocating rod 122 shown in FIGS. 2 and 9, and performs reciprocating movement in the X (X1, X2) direction quickly and smoothly. I can do it. Nozzle unit 20 for each color
Numeral 0 is attached to the reciprocating mechanism 111 via the attachment member 112. The whole is moved forward and backward by the forward and backward moving means 220 shown in FIG.

As shown in FIG. 9, the reciprocating movement mechanism 111
A pair of guide rails 11 attached to the base 111B
A table 111T is slidably mounted on 1G, and the table 111T is urged downward by a pair of left and right springs 111SP so as to abut against a pair of left and right stoppers 111S so as to be in a fixed position in a normal state. It is formed. The motor unit 121 is fixedly mounted on the frame 111F, and moves the nozzle unit 200 for each color fixed on the table 111T against the urging force of each spring 111SP to the position indicated by the two-dot chain line in the X direction (X1).
Can be done. The return (X2) is for each spring 1
It is performed by the urging force of 11SP.

The motor unit 121 uses a screw structure as a front bearing of a general stepping motor to directly apply a rotational force to a propulsive force, that is, a reciprocating rod (12).
2) It is formed so as to be able to convert it into the reciprocating motion.
In this embodiment, a linear stepping actuator (SPS20E series, manufactured by Copal Electronics Co., Ltd.) is used.

That is, the reciprocating motion of the reciprocating rod 122, which can switch the direction of rotation of the motor (121) by utilizing the rotational force of one motor (121) and which can be switched in and out by using the rotational direction of the motor (121), is used. And nozzle units 200C, 200M, 200Y, 2 for each color.
00B can be synchronously reciprocated in the X (X1, X2) direction. Therefore, since the timing belt and the like can be wiped out as in the conventional example (500), noise can be eliminated.

Further, the rotation speed of the motor unit 121 is variable, and the rotation speed switching control means (250) controls the forward movement (X1) during the color printing operation and the backward movement (X2) after the color printing operation. ) The rotation speed can be switched at a high speed. This is for further increasing the printing speed.

Further, it is formed to return within two rotations of the drum from the separation after the end of the previous printing to the suction of the next printing medium M, and to wait for the next printing.

The motor unit 121 is connected to the table 1
It may be attached to a table that is moved below the 11T by the driving of the advance / retreat moving means 220 and connected to the table 111T via a link mechanism. In this way, the load on the motor unit 121 can be further reduced.

Thus, as shown in FIG. 1, each of the nozzle unit elements 205A, 205B, 205C, and 205D is moved in the X1 direction in a pitch P between the inkjet nozzles.
T (1/75 inch) reciprocating movement and printing during forward movement are performed for each divided line (S
Considering that only the first one dot (D1) of (1, S2, S3, S4) is printed, it is understood that printing can be performed within the operation time (0.1 mSec) of the inkjet nozzle 207. .

However, if this is repeated in the Y (column) direction by, for example, 3000 dots as in the case of the conventional example (500), a remarkable increase in speed cannot be achieved. Here, each divided line (52.5) determined by dividing the length of one line (L) (for example, A4 size width 210 mm) by N (= 4).
mm) Within S1, S2, S3, and S4, the nozzle unit element (for example, from a front dot (for example, D1) separated by a pitch PT (1/75 inch) between inkjet nozzles to a rear dot (for example, D2)) 205A) was selected while utilizing the high-speed rotation (one rotation in 0.5 seconds) in the column (Y) direction of the print medium M while the paper was advanced in the X1 direction, that is, advanced by 1/300 inch. While the ink is sprayed (jetted) from the inkjet nozzle 207 in the nozzle unit element 205A, each dot (（D1n−1, D1n) belonging to the row (F1) corresponding to the previous dot D1 is taken until the drum 10 makes one rotation. When color printing is performed, printing in the row (X) direction and printing in the column (Y) direction can proceed simultaneously. That is, one line equivalent to 300 dpi can be printed in 0.5 seconds.

Therefore, each ink jet nozzle 20
7 can print four rows while the drum 10 rotates four times.
That is, each nozzle unit 205 can print all the columns belonging to the divided row (S1, S2, S3, S4) during four rotations. That is, the entire surface can be printed in 2 seconds (= 0.5 seconds × 4). With room,
Considering that each rotation (0.5 seconds) is used for attaching and detaching the print medium M before and after the start of printing, one A4 size sheet is replaced by 3 (=
Multicolor printing can be performed at a remarkably high speed of 2 + 1) seconds.

The nozzle units 200 for each color (20
5) Pitch PT between each inkjet nozzle (for example,
By moving (forwarding) by 1 / N (for example, 8) of 1/75 inch in the X1 direction and using N (= 8) rotations of the drum, the pitch PT ( Resolution (75d) determined by 1/75 inch
Multicolor printing can be performed at a resolution (600 dpi) that is N (= 8) times as large as that of the image data of the image data of the image data. That is, the nozzle unit 200 (205) for each color utilizes the high-speed rotational movement of the drum 10 regardless of the pitch PT between the ink nozzles.
By switching the amount of synchronous movement in the X1 direction and the number of rotations N of the drum, it is possible to switch the operation to a desired resolution, and to manufacture the nozzle units 200 (205) for each color technically easily and at lower cost. It is possible.

Further, depending on the operation method, if the high-speed printing on the printing medium (surface) M is used, the pitch PT between the ink jet nozzles can be adjusted to a predetermined resolution (for example, 300 dp).
The reference pitch PTp (1/1) shown in FIG.
300 inches), which is 1/75 inch of N (4) times, and the nozzle unit 200 (205) for each color is moved in the direction of the drum axis (X) by the reference pitch PTp (1/300) while the drum 10 makes one rotation. Inch) only move (forward)
And by rotating the drum 10 N (= 4), the nozzle unit 200 for each color of resolution (75 dpi)
Using (205), multicolor printing with a predetermined resolution (300 dpi) can be performed.

The feeding means 60 feeds the printing medium M one by one to the medium feeding means 90 side, and can be opened and closed (freely) on the side 3 of the main body case 1 as shown in FIGS. A manual feeding means 61 for feeding, by using a feeding roller 65, what is manually inserted into the manual feeding tray 62 mounted on the cassette 7;
A cassette feeding means 71 for feeding the print medium M on the sheet 2 (mounting plate 73) one by one using a feeding roller 75, and the feeding rollers 65 and 75 are formed so as to be selectively fed. Feed switching means 81. Cassette 72 (73)
Can accommodate 500 print media M.

The feed switching means 81 switches between the drive source (rotational power) and the rotation direction thereof (65, 7).
5) is formed to be switchable. The drive source is obtained from a motor 82 capable of reversible rotation switching via a gear train 83. Further, a start / stop state switching means 84 for selectively switching between a feed drive state and a feed stop state is provided.

That is, when the motor 82 is switched to one rotation direction, the one-way clutch 65C rotates the feed roller 65, and when the motor 82 is switched to the other rotation direction, the one-way clutch 75C rotates the feed roller 75. The start / stop state switching means 84 includes an actuator 85
And a switching mechanism 86. The switching mechanism 86 includes a lever 8
7 (pin 87P, engaging pin 87K), lever 88 (pin 88P), lever 89 (pin 89P) and the like. The operation of the actuator 85 causes the feed roller 75 to move upward and away from the print medium M, and
The friction plate 65F corresponding to the holder 65H (pin 65P)
Start (approach) by approaching downward through the remote
The state and the stop (separation) state can be switched.

Further, the medium supply means 90 includes a pair of supply rollers (91, 92) having a posture correcting function shown in FIG.
The print medium M formed from the unit and fed from the feeding means 60 can be supplied to the drum 10 at a predetermined timing. The supply speed is a speed corresponding to the peripheral speed of the drum 10.

The posture correction is performed by causing the leading end Mf (see FIG. 1) of the fed print medium M to collide with (abut against) the contact portions 99 of the supply rollers 91 and 92 in the stopped state. This is executed by aligning the tip Mf with the straight line formed by the contact portion 99 extending in the direction of the drum axis (X). Further, a bending space SP shown in FIG. 2 is provided between the feeding means 60 and the medium supply means 90 so that the bending of the print medium M is allowed.

That is, the feed amount of the feed roller 65 (75) at one time is made slightly larger than the distance between the feed roller 65 (75) and the two feed rollers 91 and 92, and The elastic deformation in the middle of M is positively generated, and the pressing force of the tip Mf against the contact portion 99 is strengthened by the elastic force, so that the posture can be more reliably corrected.

At least one of the supply roller units (90) [91, (92)] is provided with a supply power applying means (9) comprising a main motor 93, a gear train, a clutch and the like.
The supply power for rotation is applied from 3). After the posture correction, the supply power applying means (93) sends the print medium M to the drum 10 side by an amount corresponding to the elastic deflection by the supply rollers 91 and 92 by the supply roller rotation drive control means (250). More specifically, the print medium M is sent until the leading end of the print medium M is detected by a sensor (not shown). That is, the leading end Mf of the print medium M
The two sides are engaged by the two supply rollers 91 and 92 to set the standby state.

During the standby state (standby), the start / stop state switching means 84 operates to supply the supply roller 75.
From the print medium M and the friction plate 65F
Move away from 5. Therefore, feeding can be performed at any time, and it is possible to completely prevent the next printing medium M from being erroneously fed.

That is, the supply roller rotation drive control means (250) prohibits the application of the supply rotation power until the attitude of the print medium M is corrected, and permits the application of the supply rotation power after the attitude correction. Specifically, the time is controlled by the time of the feeding operation of the feeding means 60. Print medium M to drum 10
This is because the supply can be made without skewing to the side. The supply power may be obtained from the motor 82.

Further, the supply timing adjustment control means 250 for adjusting the timing with the drum 10 side has the rotational position of the drum 10 set in advance by the position detection means 100 including the light emitting device and the light receiving device shown in FIG. When the set position is reached, the print medium M is supplied by engaging with (for example, inputting a drive command) with the medium supply unit 90, that is, the supply power supply unit (93).

Here, the medium holding means 20 is a means for holding the print medium M on the outer peripheral surface 11 of the drum 10 and is carried out by negative pressure suction holding and mechanical holding. As a means, charge adsorption retention is introduced.

That is, the negative pressure attracting and holding means 21 forms a negative pressure in the drum 10 by the negative pressure establishing means 31 and print medium M through a number of suction holes 12 penetrating in and out of the drum 10 in the radial direction. Is formed so as to be able to hold by suction under negative pressure.

As shown in FIG. 6, the negative pressure establishing means 31 includes a corresponding suction port 34 corresponding to the suction port 14 on the drum 10 side,
A suction fan 32 that sucks air to establish a negative pressure in the drum (hollow portion 10E) from the corresponding suction port 34 through a duct 35 through a duct 35 is formed.

The suction port 14 is a side end plate (end face) of the drum 10.
15R, the corresponding suction port 34 corresponds to the suction port 14 and is fixed to the bracket 5R in the main body case 1. Drum 10 (15R) and negative pressure establishing means 30
(5R) means that it approaches in the drum axis direction but does not contact. Therefore, the rotational load of the drum 10 can be reduced. Further, the gap between the two 15R, 15R is useful for reducing the suction fan load fluctuation between when the print medium M is suctioned under negative pressure and when it is not. The side end plate (end surface) 15L is a blind plate.

Further, the holding claw holding means 41 for mechanical holding
Is a printing medium M supplied as shown in FIGS.
Is formed so that the distal end side is held by the drum 10 by the holding claws 42. In this embodiment, the sheet is held at a plurality of points (tips) including both ends in the direction of the drum axis (X).

That is, the holding claw holding means 41 comprises the holding claw 42, the always holding mechanism 43, the always releasing lock mechanism 44, the lock releasing mechanism 45, and the lock returning mechanism 46. The release lock mechanism 44 is mounted on one end of the drum 10 which is a movable side, and the lock release mechanism 45 and the lock return mechanism 46 are attached to a bracket (not shown) in the main body case 1 which is a stationary side. In addition, the lock release mechanism 45 and the lock return mechanism 46 perform the pinching and the pinching release of the pinching claw 42 in cooperation with the constant pinching mechanism 43 and the constant release lock mechanism 44 while skillfully utilizing the rotational movement of the drum 10. It is formed.

The holding claw 42 includes a claw 42F, an engaging portion 42C,
It has a sector gear 42G and is mounted to be rotatable about a pin 42P. The pinching mechanism 43 always includes a pin 43P.
Lever 43L (base end portion 43B, front end portion 43F) rotatable around the center, a sector gear 43G provided on the front end portion 43F and meshing with the sector gear 42G, and a base end portion 4G.
Spring 43 stretched between 3B and fixed portion 43R
The holding claw 42 is always kept in the holding state shown by the two-dot chain line in FIG. 7 by using the urging force (tensile force) of the spring 43SP.

The always-release lock mechanism 44 is composed of a lock lever 44L that can rotate about a pin 44P. An engagement groove 44C of the lock lever 44L is formed so as to be able to engage and disengage with the engagement portion 42C of the holding claw 42. And both 44C and 42C
Is formed so that the holding claws 42 can always be locked in the holding release state shown by the solid line.

The lock release mechanism 45 includes a pin 45 on the stationary side.
Pivotable lever (tip 45F, base 4
5B) It consists of 45L and actuator 45A. When the lever 45L is rotated clockwise about the pin 45P by the actuator 45A, the distal end 45F formed of the pin engages with the proximal end 44B of the lock lever 44L that has moved with the rotation of the drum 10. I do. Then, the lock lever 44L rotates clockwise and the pinching claw 42 is rotated.
The engagement with (42C) is released. Therefore, the holding claws 42
Is in a state where it can be held by the urging force of the spring 43SP. That is, the constantly released lock state can be released.

The lock return mechanism 46 is, as shown in FIG.
A lever 46L (a distal end 46F, a proximal end 46B) rotatable about a stationary pin 46P;
A. With this actuator 46A, the lever 46
When L is rotated clockwise around the pin 46P,
The lever 43L, which has been moved with the rotation of the drum 10, presses the distal end portion 46F of the lever 46L, which is a pin, and puts the holding claw 42 into the holding release state shown by a two-dot chain line via the sector gears 43G, 42G. Can be. Therefore, the engaging portion 42C of the holding claw 42 is moved to the lock lever 44L.
(44F) engages with the engagement groove 44C. In other words, the pinching claw 42 can be returned to the constantly pinching locked state.

The charge absorption and holding as an auxiliary means is performed by a charging means 51 shown in FIG. 2 of a charging roller system. The print medium M is charged with a positive charge, and the print medium M is attracted and held on the outer peripheral surface 11 by utilizing the charge attracting force generated between the drum 10 and the grounded drum 10.

In order to reduce the load at the time of suction, a means (not shown) for opening the nip of the supply rollers 91 and 92 is provided. In addition, the charging means 51 is connected to the drum 10
When the suction of the print medium M onto the drum 10 is completed, the drum 10 (1
It is formed so as to be separated from 1). Accordingly, it is possible to prevent the ink image formed on the print medium M from coming into contact with the ink image and disturbing the image.

Further, in order to increase the charging efficiency of the charging means 51, a preheating means for forcibly preheating the print medium M supplied to the drum 10 is provided. The preheating means in this embodiment is formed to also serve as the ink drying means 130 described below.

That is, the ink drying means 130 introduced in order to improve the long ink drying time related to the print speed hindrance factor of the conventional example (500) is provided by utilizing the periphery of the drum 10. 2, a heat source 131 and a warm air flowing means (fan) 132, which are heated by the heat source 131 while flowing outside air, and the warm air is blown onto the print medium M held by the drum 10, thereby printing the printed ink. Drying is performed directly or indirectly through heating of the print medium M. Thus, if a part of the warm air flows between the medium supply means 90 and the charging means 51, the print medium M can be forcibly preheated before being supplied to the drum 10.
This preheating improves the ink riding on the print medium M.

Further, the replenishing charging means 53 provided in relation to the charging means 51 is formed so as to be able to replenish the attenuation of the charge adsorbing force accompanying the execution of color printing by ink jet. The charging means 51 can be used also as the replenishing charging means 53. In this case, the charging means 51 is formed to have a variable charging ability, and the charging ability of the charging means 51 is large during the supply of the printing medium M and the rotation of the drum 10 in the Y direction by one rotation. What is necessary is just to be able to switch small later. However, the charging means 51 in this case is the drum 10
It should be a non-contact type (for example, a corona charger) that does not contact the (print medium M).

After the color printing, the charge removing means 55
To remove the charge for adsorption. This is performed by adding a negative charge opposite to that of the charging means 51.

In this embodiment, the medium supply means 9
0 and drum 1 of print medium M by medium holding means 20
One rotation (0.5 sec) of the drum 10 is allocated for supply and holding to zero.

The print medium M after color printing is separated from the drum 10 (11) by a medium peeling means 140 including a peeling claw 141 which can be inserted (inserted) between the drum 10 and the print medium M shown in FIG. It is formed to be possible. The peeling claw 141 is separated from the drum 10 during the printing operation. The medium separating means 140 and the medium holding means 20 (2
A removal timing adjustment control means (250) is provided for synchronization with (1, 41).

That is, the removal timing adjustment control means (250) controls the medium holding means 20 at a predetermined timing suitable for peeling the medium peeling means 140.
The holding force of (21, 41) is removed, and thereafter, the peeling is performed by interrupting (inserting) the peeling claw 141 between the print medium M and the drum 10 (11).

The peeling claw 141 can be separated from the drum 10 (11) during color printing and can be approached (interrupted) at the time of peeling by a link mechanism (not shown). It is formed to also serve as a medium delivery means for delivering to the 160 side. However, the medium delivery means is formed so that the print medium M can be more actively delivered to the medium discharge / conveyance means 160 side using, for example, air pressure, vacuum force, mechanical force, or the like, and is formed separately from the peeling claw 141. You may.

The removal timing adjustment control means (2
50), medium holding means 20 (51, 53, 21, 31,.
41, 55) and one rotation (0.5 sec) of the drum 10 is allocated for releasing and holding the print medium M from the drum 10 by the medium separating means 140.

Further, charging means 51, replenishing charging means 5
3, the charge removing means 55 and the medium peeling means 140 are spaced apart from the upstream side in the rotation (Y) direction of the drum 10 to the downstream side in this order as shown in FIG. It is trying to make it.

Next, the medium discharging / conveying means 160 is means for discharging / conveying the separated printing medium M in a predetermined direction. In this embodiment, as shown in FIG. 10, the medium is in contact with the non-printing surface side (back surface). It is composed of a belt conveyor 161 and a medium pressing means for pressing the print medium M toward the belt conveyor 161. Therefore, it is possible to smoothly discharge the print medium M in a desired direction after printing.

The belt conveyor 161 is shown in FIG.
As shown in (B), the separated printing medium M is
Can be discharged and conveyed at a speed corresponding to the peripheral speed of the print medium M, and after the rear end of the print medium M is separated from the drum 10, the longest time within a range that does not hinder the color printing of the next print medium M is used. The speed can be switched to low speed to discharge and transport. Natural drying of the ink can be further promoted. Therefore, the length of the belt conveyor 161 is A4
It is larger than the length of the size.

The medium pressing means comes in contact with the press belt conveyor 171 which is in contact with both sides (print prohibited area) of the medium on the printing surface, and comes into contact with the print medium M in a normal state when the print medium M is floating. It is formed of a so-called star wheel 176 (see FIG. 10C) for preventing floating. 179 is a contact portion 177 of the star wheel 176
The sponge or felt is used to clean the ink attached to the surface.

An ink drying means 181 shown in FIG. 2 is provided opposite to the belt conveyor 161 and at the end thereof, and the printing surface of the printing medium M being ejected and conveyed is forcibly dried to complete the ink drying. It is trying to make it. The ink is dried directly or indirectly through heating of the print medium M. Therefore, the print medium M with the color printing is turned upside down by the direction switching means 190 on the discharge tray 192 which is openably and closably (freely) mounted on the side 4 of the main body case 1 as in the case of the manual feed tray 62. The discharge can be switched or the non-printing surface can be discharged upward to the upper discharge tray 193. That is, the direction switching means 19
0 can be selectively switched to one of two directions and discharged. Note that three or more directions may be formed so as to be switchable.

After the completion of the color printing, the advancing / retreating means 22 for moving the respective ink jet nozzles 207 of the nozzle units 200 for each color to approach and separate from the outer peripheral surface 11 of the drum.
0 works and the nozzle units 200C, 200M,
200Y and 200B can be retreated (separated) to the left in FIG. After retreating, the cap 246 raised by the cap lifting / lowering means 240 covers each ink jet nozzle 207 to prevent the ink from drying. This cap 2
Reference numeral 46 denotes an elastically deformable seal member (for example, a hollow cylindrical body made of synthetic rubber) shown in FIG. 14, which can press the spray holes (tips) of the ink jet nozzles 207.
Therefore, each ink jet nozzle 207 is
Even if it is arranged on the normal line of 0, it can be reliably sealed.

As shown in FIG. 2, the forward / backward moving means 220 is rotatably mounted on a rack 221 provided on a table provided with the unit moving means 110 (reciprocating mechanism 111) and a bracket in the main body case 1. And a pinion 222 engaged with the rack 221.

Further, the cap lifting / lowering means 240 is
As shown in FIG. 14, one end of the link bar 243 is rotatable around the pin 243P and the other end is slidable in the guide groove 243H via the slide pin 243S. The other link bar 244 slidable in the guide groove 242H through the guide groove 242H, the tip of which can rotate around the pin 244P, and the screw shaft 2 rotated by the gear 247.
42 etc. The link bars 243 and 244 are rotatably connected at an intermediate portion by a pin 245. Therefore, if the screw shaft 242 is rotated, the lifting frame 241
Can be raised and lowered.

The lifting frame 241 has a cap 2
The waste ink receiver 231 having the attached 46 is fixedly mounted. That is, when the nozzle unit 200 for each color is retreated to the left in FIG. Then, the moving means 2
20 moves the nozzle unit 200 for each color to the right (drum 1
(In a direction approaching 0) and stops when each ink jet nozzle 207 comes into contact with each cap 246. That is, it can be covered with the cap 246.

Reference numeral 249 shown in FIG. 14 denotes a wiper blade, which is a rotating body 248 about a support shaft 248P.
To clean each ink jet nozzle 207 before being covered with the cap 246.

The waste ink collecting means 230 comprises a waste ink tank 231 including a waste ink receiver 231, a waste ink tube 232, a waste ink pump 233 and a sponge 235 shown in FIG. By increasing the internal pressure of each ink and the ink buffer 206 in each color nozzle unit 200 (205) at the time of the spit, it is possible to collect the primed inks.

Note that the control unit 250 shown in FIG.
It is formed of a computer including a CPU, a ROM, a RAM, and the like, and forms not only the print control means but also the above-described supply roller drive control means, supply timing adjustment control means, rotation speed switching control means, removal timing adjustment control means, and the like.

Next, the operation of this embodiment will be described. The drum 10 is rotated in the Y direction at a constant peripheral speed (rotation speed) by the main motor 93. When one print medium M is fed by, for example, the cassette feeding means 71 selected by using the feed switching means 81 forming the feeding means 60, the leading end Mf of the printing medium M is supplied to both feeding rollers of the medium feeding means 90. 9
The posture is corrected by colliding with the first and second contact portions 99. The flexure of the print medium M in the flexure space SP facilitates its correcting ability.

Supply roller rotation drive control means (250)
When the posture correction due to the collision is completed and the printing medium M can be supplied to the drum 10 without skewing, the application of the supply rotational power is permitted. That is, the leading end Mf of the print medium M is engaged with both the supply rollers 91 and 92, and the print medium M enters a standby state. Then, the drive stop state switching means 84 operates, and the feeding means 60 is stopped.

Thereafter, when the rotational position of the drum 10 detected by the position detecting means 100 reaches the set position, the supply timing adjustment control means (250) drives the medium supplying means 90 (91, 92) by The printing medium M is supplied to the drum 10 side. That is, the print medium M is supplied at a speed corresponding to the peripheral speed of the drum 10.

Here, the negative pressure suction holding means 21 uses the negative pressure in the drum 10 established by the negative pressure establishing means 31 to suction hold the printing medium M. At the same time, the holding claw holding means 41 (45, 43) operates, and the holding claw 42 holds a part (the leading end side) of the print medium M on the drum 10 (11).
Further, the charging means 51 as an auxiliary charges the print medium M. Prior to this, the preheating means (130) sets the printing medium M
Is forcibly preheated and dried, so that it can be charged efficiently. Therefore, the printing medium M can be reliably held at the predetermined position in the Y direction on the outer peripheral surface 11 of the drum by suction.

Further, since the leading end side of the print medium M is held by the negative pressure before the holding by the holding claws 141, the holding can be performed stably. Further, both supply rollers 9
If the nip pressure of 1,92 is released, the accuracy of the holding position on the drum 10 can be improved.

The control unit 250 includes the nozzle units 200C, 200M, 200Y, 200B for each color (each nozzle unit element 205A, 205B, 205C, 205B).
D) to drive and control the respective divided rows S1 and S1 shown in FIG.
Dots D1, D in the first row (L1) in 2, 2, S4
5, D9,... Are printed simultaneously. Since the ink jet nozzles 207a to 207n for each color are arranged at the same position in the row (X1), the same dot (D1) for each color is used.
Color overlay can be performed accurately.

The unit moving means 110 moves the nozzle units 200C, 200M, 200Y, 200B for each color in the X1 direction shown in FIG. 4 in synchronization with each other. At this time, a forward movement is performed at a constant speed while moving from the front dot D1 to the rear dot D2. Here, the control unit 250 controls the driving of each inkjet nozzle 207 using the high-speed rotational movement in the Y direction during this period, and controls the row (F) to which the previous dot D1 belongs.
Each dot (~ D1n-1, D1n) of 1) is
Is printed while rotating once. Each nozzle unit element 205 prints simultaneously.

Therefore, when the drum 10 makes one rotation,
Color printing of each dot (〜D1n-1, Dn) belonging to the column (F1) on the virtual locus R1 shown in FIG. 1 can be performed. Hereinafter, similarly, while moving from the front dot D2 to the rear dot D3, the dots (の D2n−1, D2n) of the column F2 to which the front dot D2 belongs are simultaneously printed on the virtual trajectory R2. That is, the inkjet nozzle 207
While moving a in the X1 direction by a predetermined pitch PT, the plane [(L1, L2 to Ln) ×
(F1, F2,..., F4)], the A4 size can be printed in multicolor in 2 seconds while simultaneously proceeding. Even if two rotations (1 sec) assigned to the attachment / detachment of the print medium M are added, the time is 3 seconds or less.

If the amount of movement of the nozzle unit 200 for each color in the X direction and the number of rotations N of the drum 10 are selected, the pitch of the ink jet nozzle 207 (P
T, PTp), color printing can be performed at a desired resolution. Further, a predetermined reference pitch PTp (= 1 /
Coarse pitch PT (= 300 inches) multiplied by N (= 4)
Using 1/75 inch, color printing with a resolution (300 dpi) corresponding to the reference pitch PTp can be performed.

In FIGS. 1 and 4, the last row (Ln) on the rear end side belonging to the same column (F1) as the first row (L1) dot D1 on the front end side of the print medium M in the first column (F1). Although the position is shifted from the eye dot Dn by one dot in the X1 direction,
Since the displacement is 1/300 inch corresponding to the resolution (300 dpi), it cannot be visually recognized at all.

Furthermore, if the amount of reciprocating movement in the X1 direction is kept constant, and control is performed so that the dot D2 is reached when the drum 10 returns to the first line (L1) after one rotation, the first
The amount of positional displacement in the X1 direction between the first row (L1) dot D1 on the leading end side of the print medium M in the column (F1) and the last row (Ln) dot Dn on the trailing end side belonging to the same column (F1) is calculated. It can be smaller than one dot.

The ink on the printing medium M by the color printing is accelerated by the relative flow with the ambient air due to the high-speed rotation of the drum 10 (the printing medium M). High quality printing can be maintained because drying is accelerated quickly.

After printing one sheet, the unit moving means 110
Synchronizes the nozzle units 200 for each color and X
It is moved backward by a predetermined pitch PT in two directions. Prepare for the next print.

At the same time, the removal timing adjustment control means (250) controls the charge removal means 55 at a predetermined timing.
And the medium holding means 2
The holding force of 0 (21, 41) is eliminated and the medium peeling means 140 is operated. That is, the peeling claw 141 peels the printing medium M from the drum 10 (11), and after peeling, the printing medium M is used as a medium delivery means when the medium discharging / conveying means 16 disposed above the nozzle unit 200 for each color.
Deliver to the 0 side.

The medium discharge / convey means 160 discharges and conveys the print medium M at a speed corresponding to the peripheral speed until the end of the print medium M is separated from the drum 10 (11), and after that, the natural drying time can be lengthened. Switch to low speed. Then, the print surface side of the print medium M discharged and conveyed is forcibly dried by the ink drying means 181 provided at the end thereof.
Thereafter, by switching the direction switching means 190, the sheet can be quickly discharged to the discharge tray 192 or the upper discharge tray 193. Even if the hand touches the discharged print medium M, ink bleeding or the like does not occur.

At the end of the printing operation, the forward / backward moving means 220
Moves the nozzle unit 200 for each color, and operates the tube opening / closing means 218 with the ink return tube closed to increase the pressure in the ink buffer 206 and forcibly jet ink from each ink jet nozzle 207 to perform cleaning. The waste ink is collected by the waste ink collecting means 230. Thereafter, each ink jet nozzle 207 is covered with the cap 246 raised by the cap lifting / lowering means 240 to prevent drying.

According to this embodiment, the drum 10 rotatable at a constant peripheral speed, the medium holding means 20 for holding the print medium M on the outer peripheral surface 11 of the drum 10, and the drum 10 in the rotation direction of the drum 10. A nozzle unit 200 for each color is provided which is misaligned and has a large number of ink jet nozzles 207, and ink for each color is sprayed from the selected ink jet nozzle 207 for each color onto the print medium M rotating and moving together with the drum 10. And a negative pressure suction holding means 21 for holding the medium holding means 20 through the suction hole 12 penetrating inside and outside the drum and using the negative pressure inside the drum to suction and hold the medium. Holding means 41 for pressing and holding the peripheral portion of the printed printing medium M on the outer peripheral surface 11 of the drum 10 using the holding claw
Since it is possible to print on the rotating printing medium M which is held by suction at the negative pressure on the drum 10 and is rotating, it is possible to dramatically increase the speed of multi-color printing and to realize continuous printing operation of a large number (500 sheets). Can be achieved.

Further, the holding claw holding means 41 holds the peripheral portion of the printing medium M, that is, the leading end side of the printing medium M, which has been negatively suction-held by the negative pressure suction holding means 21, and
Since it is formed so as to be able to be pressed and held, more secure and stable holding can be ensured.

Since the holding claw holding means 20 (41) performs the holding and the holding release by the holding claw 42 while utilizing the rotation of the drum 10, the mechanism (43, 44) mounted on the drum 10 is used. ) Is reduced and the rotational load can be reduced.

Further, there is provided a peeling claw 141 capable of inserting the printing medium M, which has been suction-held by the drum 10 under negative pressure, between the drum 10 and the printing medium M, and a medium peeling means 140 for peeling the printing medium M from the drum 10. Removal timing adjustment control means for removing the negative pressure suction holding force by the negative pressure suction holding means 21 and the clamping force by the clamping claw holding means 41 at a predetermined timing prior to the peeling operation by the medium peeling means 140. Since (250) is provided, the print medium M after multicolor printing can be further reliably and stably peeled off from the drum 10.

Further, a charging means 51 and a replenishing charging means 53 are provided to assist the medium holding means 20, and the printing medium M
Is held on the drum 10 by using the charge adsorption force, and the charge removing means 55 and the mechanical medium peeling means 140 are provided to peel the print medium M from the drum 10. M can be more stably and reliably held on the drum 10 and can be smoothly separated from the drum 10. Therefore, high-speed color printing can be performed continuously and stably.

The charging means 51 and the replenishing charging means 5
3. Since the charge removing means 55 and the medium peeling means 140 are arranged in this order from the upstream side in the rotation (Y) direction of the drum 10 to the downstream side, from the holding on the drum to the peeling after printing. Since the required number of rotations of the printing medium can be minimized, the printing speed can be further increased from this point.

Further, since the printing in the row (X) direction by the synchronous movement of each nozzle unit element 205 and the printing in the column (Y) direction using the high-speed rotation of the print medium M can proceed simultaneously, the printing can be further improved. Print speed.

The pitch P between each ink jet nozzle is
T is set to N times the reference pitch PTp required to obtain a predetermined resolution, and the nozzle unit 200 for each color is moved in the direction of the drum axis (X) per rotation of the drum 10 to the reference pitch PTp.
The nozzle unit 200 for each color is formed so as to be movable only by N rotations of the drum 10 so that color printing at a predetermined resolution can be performed. Depending on the combination, they can be formed integrally or integrally over the entire length in the X direction.

Since the reciprocating movement amount of the nozzle unit 200 for each color in the X direction is set to, for example, 1/600 (= 4 dots) of the entire width (for example, 2400 dots),
It is possible to reliably wipe out the most important factor that hinders the high-speed printing in the X direction.

The ink jet nozzle 207 for each color is used.
Are arranged on the normal line to the drum 10,
The shape and size of the sprayed ink on the print medium M can be made uniform. Therefore, higher quality printing can be performed.

The nozzle unit 200 for each color can be moved by 1 / N of the pitch PT between the ink jet nozzles while the drum 10 makes one rotation by the unit moving means 110. Since it is formed so that color printing can be performed at a resolution N times the resolution determined by the pitch PT, one of the drums 10 can be printed.
If the amount of movement per rotation (PT × 1 / N) and the number of rotations of the drum (N) during the movement are switched, color printing can be performed with the resolution switched while keeping the pitch PT between the ink jet nozzles constant.

Further, since the corresponding ink jet nozzles 207 in the nozzle units 200 for the respective colors are arranged at the same position in the direction of the drum axis (X), even higher quality printing can be performed from this point.

A plurality (four) nozzle unit elements 20 in which the nozzle units 200 for each color are arranged in the direction of the drum axis (X) and displaced in the direction of rotation of the drum.
Since it is formed from 5A to 205D, it is easily available technically and cost-effectively.

Each of the nozzle unit elements 205A to 205A
05D is arranged in a zigzag manner with the other nozzle unit elements 205 adjacent in the drum axis direction in the drum rotation direction, so that the arrangement space can be minimized and the speed in the X direction is further increased by reducing the weight. , The color printing speed can be further increased.

Further, since the driving source of the unit moving means 110 is formed of one motor unit 121 having a reciprocating rod 122 capable of switching between in and out, the reciprocating movement of the nozzle unit 200 for each color in the X direction is quiet. Can be performed smoothly and quickly. Therefore, higher quality and higher printing speed can be achieved. Switch to high speed and go forward (X
2), the printing speed can be further increased.

Further, the feeding means 60 is formed of a manual feeding means 61, a cassette feeding means 71, and a feeding switching means 81, and the fed printing medium M is provided with a medium having a posture correcting function. Since the paper can be supplied to the drum 10 side via the supply means (supply roller unit) 90, the applicability to the change (switching) of the print target medium (M) is wide and easy to handle, and the printing speed is increased. In addition, high-speed color printing of, for example, 500 sheets can be continuously performed.

The medium supply means 90 is provided with a pair of rollers 9.
The print medium M is formed so that the print medium M can be supplied to the drum 10 without skew after the leading end Mf of the print medium M collides with the contact portions 99 of the first and the second 92 and the posture thereof is corrected. 10 can be held accurately.

When the rotational position of the drum 10 detected by the position detecting means 100 reaches a preset position, the print medium M is supplied to the drum 10 side. M can be accurately held by the drum 10.

Further, since the ink drying means 130 is provided to positively dry the ink on the print medium M held on the drum 10, the printing speed and the printing quality can be further improved. .

Further, since the printing surface side of the print medium M being discharged and conveyed, which has been peeled off from the drum 10, is formed so as to be forcibly dried by the ink drying means 181, the discharged print medium M is immediately touched. Even if ink does not bleed or mix. Therefore, also from this point, the speeding up of printing can be further promoted and handling is further facilitated.

Further, since the medium discharging / conveying means 160 is formed so as to be able to discharge and convey the printing medium M separated from the drum 10 by using the medium separating means 140 at a speed corresponding to the peripheral speed of the drum 10, Continuous color high-speed printing can be promoted.

Further, since the medium discharging / conveying means 160 is formed by the belt conveyor 161 in contact with the non-printing surface of the printing medium M and the medium pressing means (171) capable of contacting the printing surface, Can be more stably and smoothly discharged and conveyed. The medium delivery means (141) further promotes this.

Further, a direction switching means 190 is provided downstream of the medium discharge / conveyance means 160 so that the print medium M can be selectively switched to one of two directions so as to be discharged.
The printing medium M after printing can be handled more easily.

Further, since the ink tanks 213 for the respective colors are arranged at positions separated from the nozzle units 200 for the respective colors, the capacity of the ink tanks 213 can be increased. Therefore, since a complicated replacement interval of the ink tank 213 can be lengthened, continuous color printing can be performed for a long time, and the reciprocating movement in the X direction can be further accelerated by reducing the load on the nozzle unit 200 for each color.

Further, the ink supply means 210 is formed so as to connect the nozzle unit 200 for each color and the ink tank 213 for each color with the ink supply tube 215, and to make the pressure of each color ink equal by the urging means 216. Therefore, the degree of freedom in layout can be greatly expanded, and higher quality printing can be performed.

Further, each ink jet nozzle 207 of each color nozzle unit 200 can be separated and approached to the drum 10 by the advancing / retracting means 220 and is covered with the cap 246 raised by the cap elevating means 240 in the separated state. This prevents the ink from drying out of the nozzles.

[0160]

According to the first aspect of the present invention, a drum rotatable at a constant peripheral speed, a medium holding means for holding a print medium on the outer peripheral surface of the drum, and a position shift in the drum rotating direction. And a nozzle unit for each color having a large number of ink jet nozzles, each of which is formed to be capable of color printing by spraying ink for each color from a selected ink jet nozzle for each color onto a print medium that is rotating and moving together with a drum. The holding means is provided through a suction hole penetrating the inside and outside of the drum and using negative pressure suction holding means using the negative pressure inside the drum, and a claw for holding the peripheral portion of the print medium held by the negative pressure suction. Since it is formed of a holding claw holding means for pressing and holding on the outer peripheral surface of the drum, negative pressure is attracted to the drum and held by the drum, and color printing is performed on the rotating print medium M. Because it is formed on the ability achieved can and large number of significant multi-color printing speed (500 sheets)
Continuous printing operation becomes possible.

According to the second aspect of the present invention, the holding claw holding means is formed so as to be able to hold at least the leading end side of the printing medium held by the drum under negative pressure. In addition to the effect similar to that of the invention, the mechanical holding on the drum becomes easy, the structure can be simplified, and the printing surface is not affected.

Further, according to the third aspect of the present invention, there is provided a medium peeling device for peeling a print medium from a drum, the peeling claw having a release claw capable of inserting the print medium sucked and held by the drum between the drum and the print medium. And a removal timing adjustment control means for removing the negative pressure suction holding force by the negative pressure suction holding means and the holding force by the holding claw holding means at a predetermined timing prior to the peeling operation by the medium peeling means. With this configuration, the same effects as those of the first and second aspects of the invention can be obtained, and the printing medium after multicolor printing can be reliably and stably peeled off from the drum. This also promotes high-speed printing.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a technical basis of the present invention and a printing operation of an embodiment.

FIG. 2 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining a relationship between a drum and a nozzle unit.

FIG. 4 is also a view for explaining a nozzle unit.

FIG. 5 is also a view for explaining a feeding means.

FIG. 6 is a view for explaining a negative pressure suction holding unit.

FIG. 7 is a view for explaining a holding claw holding means and a holding operation.

FIG. 8 is a view for explaining a holding claw holding means and a holding release operation.

FIG. 9 is also a view for explaining a unit moving means.

FIG. 10 is also a view for explaining a medium discharge / convey means.

FIG. 11 is a diagram for explaining an ink supply unit.

FIG. 12 is a view for explaining an urging means.

FIG. 13 is a front view for explaining a cap elevating means.

FIG. 14 is a side view for explaining the cap elevating means.

FIG. 15 is a diagram for explaining a conventional example (1).

FIG. 16 is a diagram for explaining a conventional example (2).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body case 10 Drum 11 Outer peripheral surface 12 Suction hole 20 Medium holding means 21 Negative pressure adsorption holding means 31 Negative pressure establishing means 41 Nipping claw holding means 42 Nipping claw 51 Charging means 53 Replenishing charging means 55 Charge removing means 60 Feeding means 61 manual feeding means 71 cassette feeding means 81 feed switching means 90 medium feeding means 100 position detecting means 110 unit moving means 111 reciprocating moving mechanism 130 ink drying means (preheating means) 140 medium peeling means 141 peeling claw 160 medium discharge Conveying unit 181 Ink drying unit 190 Direction switching unit 200 Nozzle unit for each color 205 Nozzle unit element 207 Ink jet nozzle 210 Ink supply unit 216 Urging unit 218 Pressure adjusting unit 220 Advance / retreat moving unit 230 Waste ink collecting unit 240 Cap elevating unit 2 50 control unit (removal timing adjustment control means) M print medium

Claims (3)

[Claims] 1. A drum rotatable at a constant peripheral speed, medium holding means for holding a print medium on an outer peripheral surface of the drum,
A nozzle unit for each color, which is displaced in the direction of rotation of the drum and has a number of ink jet nozzles for each color, and sprays ink for each color from the selected ink jet nozzle for each color onto a print medium rotating and moving with the drum Negative pressure suction holding means and a negative pressure suction holding means for holding the medium holding means through a suction hole penetrating inside and outside the drum and utilizing the negative pressure inside the drum. An ink-jet printer, comprising: holding means for holding a peripheral portion of the medium on the outer peripheral surface of the drum by using a holding claw. 2. The ink jet printer according to claim 1, wherein said holding claw holding means is formed so as to be able to hold at least a leading end side of said print medium held by said drum under negative pressure. 3. A medium separation means for separating the print medium from the drum, the separation medium having a separation claw capable of inserting the print medium sucked and held by the drum between the drum and the print medium. Removal timing adjustment control means for removing the negative pressure suction holding force by the negative pressure suction holding means and the clamping force by the clamping claw holding means at a predetermined timing prior to the peeling operation by the peeling means,
The ink jet printer according to claim 1 or 2, wherein: