JPH10138519A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the changeover of resolution, high speed multicolor printing and continuous printing operation of a large number of printing sheets. SOLUTION: A drum having a printing medium M capable of being held to the outer peripheral surface thereof and rotatable centering around its axial line at a constant peripheral speed, respective color nozzle units arranged to the periphery of the drum so as to be positionally shifted in the rotary direction of the drum and having a large number of ink jet nozzles 207a-207n and a unit moving means moving the color nozzle units in the axial line direction of the drum are provided and the unit moving means is formed so as to make the color nozzle units movable by 1/N the pitch PT between the ink jet nozzles during one rotation of the drum and color printing can be applied to the printing medium M in resolving power N times the resolution determined by the pitch PT between the ink jet nozzles by utilizing the N-time rotation of the drum.

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 performing high-speed multi-color printing with a constant resolution between ink jet nozzles of each color nozzle unit and switching resolutions, and capable of continuous printing operation.

[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]

The printing resolution of the ink jet printer 500 is determined by the pitch P between the ink jet nozzles of the nozzle unit 502 for each color. At best, it is only possible to shift the dots by software to obtain a resolution twice as high as the reference, for example. The same applies to the laser printer 600.

Furthermore, multicolor printing using the ink jet printer 500 is very slow. 5 to 5 color printing on a single sheet (for example, A4 size)
Spend more than 10 minutes. If the resolution is doubled by software, twice or more times are required. 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, from the viewpoint of the printing speed, the laser color printer 600 sets the A4 size to, for example, 15 to
Color printing can be performed in 20 seconds. That is, the number of sheets that can be printed in one minute during continuous printing is four. That is, it is 4 ppm. Moreover, the photosensitive drum 61
Reference numeral 1 denotes a rotational motion, and the paper is continuously fed in one direction (Y), so that the noise is relatively low. However, since the expensive process means 610 must be provided in four rows, the cost is high and the size is large.

Thus, the ink jet printer 500
For example, it is not very noticeable when printing several postcards at a fixed resolution at home, but multi-color printing in a general office that prints various books including documents and illustrations with different required resolutions and photographs etc. Required resolution and required printing speed 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 which can switch the resolution, can perform multicolor printing at a high speed, and can continuously print many sheets.

[0016]

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 in the line (X) direction over the entire length, 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 ink jet nozzle 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. 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 can be urged as a nozzle unit element for each color, and a plurality of nozzle unit elements for each color can be 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 m
(Sec × 4 dots). That is, logically, one sheet of, for example, 3000 dots in the Y direction can be printed in about 1.2 seconds.

However, a plurality of nozzle units (elements) for each color integrated with the large and heavy ink cassette 504
It is not realistic to arrange a part of them in the X direction while arranging them in the Y 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, so to speak. 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 idea, a plurality of (N) nozzle unit elements for each color are spaced apart 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, it is not practical 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 and moved 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 above examination results, it is possible to achieve high-speed printing by simultaneously performing the printing in the row direction and the printing in the column direction.

In addition, if attention is paid to the fact that the reciprocating movement time of the nozzle unit for each color in the X direction can be greatly reduced and the rotational movement in the Y direction can be performed at a high speed, and the operation time of each ink jet nozzle, the high-speed multi-color nozzle unit can be obtained. By selectively switching the amount of movement in the X direction per rotation of the print medium within a range where color printing is not hindered, it is possible to perform printing in which the resolution is switched regardless of the pitch of each inkjet nozzle.

Thus, the present invention utilizes the relative movement (high-speed rotational movement) of the print medium and the nozzle units for each color in the longitudinal direction of the print medium, and reciprocates the nozzle units for each color over a short distance, for example, the pitch between inkjet nozzles. By making it possible to integrally or integrally form a plurality of movable nozzle unit elements for each color, an apparent line printer structure can be realized, and reciprocal movement in the X direction and relative movement in the Y direction can be realized. Speed up the rotational movement.
The color printing can be speeded up by continuously printing using the nozzle units for each color during the relative rotational movement, and the resolution can be switched by switching the moving amount of the nozzle unit for each color per rotation of the drum in the X direction. It is formed so that continuous printing operation can be performed on a large number of sheets.
Furthermore, by adopting a motor unit, etc., it is possible to improve the printing quality while smoothing the reciprocating movement of the inkjet nozzles for each color in the X direction, and to achieve a higher printing speed by increasing the reversing speed in the X direction. It is formed.

That is, according to the first aspect of the present invention, a drum capable of holding a print medium on an outer peripheral surface and rotatable at a constant peripheral speed about an axis, and being disposed around the drum in a rotationally displaced direction. A nozzle unit for each color having a large number of ink jet nozzles, and a unit moving means for moving the nozzle unit for each color in the axial direction of the drum are provided, and the nozzle unit for each color is moved while the unit moving means makes one rotation of the drum. It is formed so as to be movable by 1 / N of the pitch PT between the ink jet nozzles, and the pitch PT between the ink jet nozzles by using N rotations of the drum.
Wherein a color print is formed on a print medium at a resolution of N times the resolution determined by the above.

In this invention, ink is sprayed from each ink jet nozzle onto the rotating print medium while rotating the drum at a constant peripheral speed and moving the nozzle units for each color in the axial direction of the drum using the unit moving means. To perform color printing. At this time, the amount of movement of each color nozzle unit in the drum axis direction per rotation of the drum is 1 / N of the pitch PT between the ink jet nozzles. For example,
If PT = 1/75 inch and N = 4, it is 1/300 inch, and if N = 8, it is 1/600 inch.

Therefore, if the nozzle is switched to rotate N (4,8) while the nozzle unit for each color moves the pitch PT between the ink jet nozzles, 75 dp can be obtained.
i, the pitch PT between the inkjet nozzles (=
1/75 inch) and 300dpi or 600d resolution
The multi-color printing switched to pi can be performed. In addition, since the moving speed in the longitudinal direction of the printing medium is equal to the peripheral speed of the drum (e.g., equivalent to 120 rpm) and is continuous rotation, multicolor printing can be performed at a much higher speed than in the case of the conventional inkjet printer. And continuous printing operation for a large number of sheets is possible.

Further, according to a second aspect of the present invention, each of the color nozzle units is displaced in the rotational direction of the drum so that the ink jet nozzles in each of the color nozzle units are at the same position in the drum axis direction. It is an ink jet printer provided.

In this invention, the corresponding ink jet nozzles of each color nozzle unit are located at the same position in the drum axis direction, so that the color dots to be superimposed in the width direction of the print medium can be made completely identical. Therefore, in addition to providing the same operation and effect as the case of the first aspect of the present invention, high-quality multi-color printing can be performed as compared with the case of the conventional ink jet printer in which each ink jet nozzle pitch P is sent.

According to a third aspect of the present invention, the unit moving means includes a motor unit having a reciprocating rod which can be switched in and out by using the rotational force of the motor and switching the direction of rotation of the motor. It is an inkjet printer.

In this invention, when the motor unit is driven, the reciprocating rod protrudes (forwards) in the direction of rotation, and the nozzle unit for each color can be moved in the one-line printing direction in the width direction of the printing medium. When the rotation direction is switched to the reverse direction after printing one line, the reciprocating rod is immersed (returned) and the nozzle units for each color are returned to the original positions.

Therefore, the same effects as those of the first and second aspects of the invention can be obtained, and furthermore, the reciprocating movement of the nozzle units for each color is performed by the motor unit capable of smoothly rotating and quickly appearing and retracting. In addition, more uniform and high-quality multi-color printing can be performed, the printing speed can be further increased, and noise can be eliminated.

Further, according to the invention of claim 4, the unit moving means is formed of one motor unit and the nozzle units for each color are moved in the axial direction of the drum by utilizing the reciprocating movement of the reciprocating rod. This is an inkjet printer that is formed so as to be able to move synchronously.

In this invention, the nozzle units for each color, which are displaced in the rotational direction of the drum, are synchronously moved in the axial direction of the drum by one motor unit. Therefore, in addition to the same effects as those of the first to third aspects of the present invention, the dots for each color in the width (row) direction of the print medium can be accurately overlapped, so that a higher quality multi-color Color printing can be performed.

Further, the invention according to claim 5 is characterized in that the motor unit is of a variable rotation speed type, and the motor unit has a reverse rotation speed after the color printing operation with respect to a forward rotation speed during the color printing operation. This is an ink jet printer provided with a rotation speed switching control unit that performs drive control at high speed.

In this invention, when the one-line operation printing is completed, the rotation speed switching control means switches the reverse rotation speed of the motor unit to high speed. Therefore, the same effects as those of the first to fourth aspects of the invention can be obtained, and the start timing of the next line printing can be further advanced, so that higher-speed color printing can be performed.

[0045]

Embodiments of the present invention will be described below with reference to the drawings. This inkjet printer is shown in FIG.
As shown in FIG. 4, a drum 10 capable of holding a print medium M on an outer peripheral surface 11 and rotatable at a constant peripheral speed about an axis (10S), and a rotationally displaced arrangement around the drum 10 in the rotation direction. Nozzle unit 2 for each color, each of which has a plurality of inkjet nozzles 207a to 207n.
00C, 200M, 200Y, and 200B, and a unit moving means 110 for moving each color nozzle unit 200 in the axial direction of the drum, and the nozzle unit 200 for each color is moved while the unit moving means 110 makes one rotation of the drum 10. Pitch PT between each inkjet nozzle
Is formed so as to be movable by 1 / N of that, and color printing can be executed on the print medium M at a resolution N times the resolution determined by the pitch PT between the ink jet nozzles by using N rotations of the drum 10.

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 means 20.

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 / convey means 160 side via the medium delivering means (141). The sheet is discharged and conveyed in a predetermined direction by the 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. At the end (left) side of the medium discharging / conveying means 160, an ink drying means 180 for forcibly drying the ink on the print medium M is provided for perfecting the ink drying.

Each color nozzle unit 200C, 200
M, 200Y, 200B and the ink supply means 210 are arranged separately. Here, the unit moving means 110
Can quickly and reciprocally move the small and light color nozzle unit 200 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
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). In this embodiment, 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 print medium M is moved in the row (Y) direction is significantly higher than the conventional example (600) and at 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 be able to hold the printing medium M of A4 size or more and to obtain a high peripheral speed.

Here, the nozzle unit 200 for each color is
Each ink supply means 210 (ink cassette 211)
Therefore, a plurality of (N) nozzle unit elements 205 for each color can be integrally formed.
In this embodiment, in order to secure the technical and cost advantages, the nozzle unit 205 is a combination of four (= N) nozzle unit elements 205A, 205B, 205C, and 205D shown in FIG. ) Direction. In other words, as shown in FIG. 4, the nozzle units 200 for each color are divided into N (= 4) in the direction of the drum axis (X) as shown in FIG.
It is integrally formed from 5D. The length of the divided row of each nozzle unit element 205A, 205B, 205C, 205D is S1, S2, S3, S4 shown in FIG.

More specifically, the nozzle unit element 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 inkjet 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
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.

Here, as shown in FIG. 11, an 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 of the urging means 216 is driven in a state where the ink return tube 217 is closed by the tube opening / closing means 218, the color ink is added from the ink tank 213 into the nozzle unit 200 for each color (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, the air in the ink buffer 206 can be released. Further, if printing is performed with the urging means 216 stopped and the ink return tube 217 opened by the tube opening / closing means 218, the ink reduced by the ink jet can be transferred from the ink tank 213 to the ink return tube 2 by the capillary effect.
17, the ink is automatically replenished into the ink buffer 206. The ink level in the ink tank 213 is always kept constant by the liquid level keeping means 212.

As shown in FIG. 12, each of the urging 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. It is adjusted but almost the same. Inkjet characteristics (meniscus)
This is to make it possible to stably perform higher quality printing by making the printing uniform. Note that the ink tanks 213 for each color are used.
Is disposed at a position lower than the ink ejection port of the nozzle unit 200 for each color, and the ink tank 213 for each color is 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 disposed separately from the nozzle units 200 for each color, the nozzle unit 200 for each color (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, the interval for exchanging the ink cassette can be lengthened. Accordingly, the nozzle unit 200 (nozzle unit element 205) for each color can be synchronously moved in the X direction with a light load and at a high speed, and the continuous printing operation time can be greatly increased.

Here, the unit moving means 110
Is formed by a reciprocating mechanism 111 and a motor unit 121 having a reciprocating rod 122 shown in FIGS. 2 and 9, and can perform reciprocating movement in the X (X1, X2) direction quickly and smoothly. The nozzle unit 200 for each color includes the mounting member 11
2 and is attached to the reciprocating mechanism 111 via. 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 is formed so that the rotational force can be directly converted into a propulsive force, that is, a reciprocating (reciprocating) movement of the reciprocating rod (122) by using a screw structure for a front bearing of a general stepping motor. I have. In this embodiment, a linear stepping actuator [SPS2
0E series: manufactured by Copal Electronics Co., Ltd.].

That is, the reciprocating motion of the reciprocating rod 122, which can switch the direction of rotation of the motor (121) by using the rotational force of one motor (121) and which can be switched in and out by using the rotation 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 the 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 mSce) 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.

Here, each color nozzle unit 200 (2
05) X1 by 1 / N (for example, 8) of the pitch PT (for example, 1/75 inch) between the inkjet nozzles.
In the conventional example (500), the resolution (75 dpi) determined by the pitch PT (1/75 inch) between the inkjet nozzles in the direction (forward movement) and the rotation of the drum N (= 8) is utilized. 8) Double resolution (600dp)
In i), multicolor printing can be performed. That is, regardless of the size of the pitch PT between the ink nozzles, the nozzle unit 200 for each color is used while utilizing the high-speed rotational movement of the drum 10.
By switching the amount of synchronous movement in the X1 direction of (205) and the number of drum rotations N thereof, it is possible to switch the operation to a desired resolution and to operate the nozzle unit 200 (20) for each color.
5) can be made technically easier and at lower cost.

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 (rotating 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 feeding roller 65, and when switched to the other rotation direction, the one-way clutch 75C rotates the feeding 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.

The medium supply means 90 is formed by a pair of supply roller (91, 92) units having a posture correcting function shown in FIG. At the timing described above. 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 (butt) with 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 detects the rotational position of the drum 10 detected by the position detecting means 100 including the light emitting device and the light receiving device shown in FIG. When the set position is set in advance, the print medium M is supplied by engaging with the medium supply unit 90, that is, the supply power supply unit (93) (for example, inputting a drive command).

The medium holding means 20 for holding the printing medium M thus supplied on the outer peripheral surface 11 of the drum 10 is appropriately selected from negative pressure suction holding, charge suction holding, mechanical holding and the like. However, in this embodiment, the holding is performed by charge suction holding, and negative pressure suction holding and mechanical holding are introduced as auxiliary means for this.

That is, the charge adsorption holding is performed by the charging means 51 of the charging roller system shown in FIG. The print medium M is charged with a positive charge, and the print medium M is moved to its outer peripheral surface 1 by utilizing the charge attracting force generated between the drum 10 and the grounded drum 10.
1 to hold.

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 printing speed hindrance factor of the conventional example (500) is provided by utilizing the periphery of the drum 10. 2 is formed by a heat source 131 and a warm air flowing means (fan) 132, which is heated by the heat source 131 while flowing the outside air, and the warm air is blown onto the print medium M held on the drum 10 to print 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, a replenishing charging means 53 is provided so as to be able to replenish the attenuation of the charge attraction 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 capability, and
The charging ability of No. 1 indicates that the supply of the printing medium M starts and the drum 10
May be large during one rotation in the Y direction, and may be small after one rotation. However, in this case, the charging means 51
Should be a non-contact type (for example, a corona charger) that does not contact the drum 10 (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.

Negative pressure suction holding means 21 as auxiliary means
Is formed so that a negative pressure is formed in the drum 10 by the negative pressure establishing means 31 and the print medium M can be suction-held by the negative pressure through a number of suction holes 12 penetrating in and out of the drum 10 in the radial direction. . However, the present invention can be implemented even if the charging means 51 and the master and slave are changed.

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 provided on the side end plate (end face) 15R of the drum 10, and the corresponding suction port 34 is
Is fixedly disposed on the inner bracket 5R. Therefore, the drum 10 (15R) and the negative pressure establishing means 30 (5R)
Means that they approach in the drum axis direction but do 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. Side end plate (end face) 1
5L is a blind plate.

In this embodiment, the suction holes 12 are
Although only the leading end side of the print medium M is provided at the position where the suction is performed, it may be provided only at the rear end side or at a position where both the front side and the rear end side can be suctioned. Furthermore, the drum outer peripheral surface 1
1 may be uniformly arranged on the entire surface.

As shown in FIG. 7 and FIG. 8, the holding claw holding means 41 for mechanical holding holds the peripheral portion of the supplied print medium M, and in this embodiment, The distal end side is formed so as to be held between the drum 10 by the holding claws 42.

That is, the holding claw holding means 41 comprises the holding claw 42, the always holding mechanism 43, the always-release lock mechanism 44, the lock release mechanism 45, and the lock return mechanism 46. The release lock mechanism 44 is mounted on one end side of the movable drum 10, and the lock release mechanism 45 and the lock return mechanism 46 are mounted on 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 normally-release lock mechanism 44 comprises a lock lever 44L which 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.

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 printing medium M after the color printing is separated from the drum 10 (11) by the medium separating means 140 including the separating claw 141 which can be inserted (inserted) between the drum 10 and the printing 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 separating the medium separation 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), 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 holding means 20 and the medium peeling 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.

The medium discharging / conveying means 160 is a means for discharging / conveying the separated printing medium M in a predetermined direction. In this embodiment, as shown in FIG. 10, a belt conveyor 161 in contact with the non-printing surface side (back side) is provided. 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 print surface side 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 side thereof. 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 each color nozzle unit 200 toward and away 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. The cap 246 raised by the cap elevating means 240 after retreating covers each ink jet nozzle 207 to prevent the ink from drying. The cap 246 is made of an elastically deformable seal member (for example, a hollow cylindrical body made of synthetic rubber) shown in FIG. 14, and can press the spray holes (tips) of the respective inkjet nozzles 207. Therefore, even if each ink jet nozzle 207 is arranged on the normal line of the drum 10, it is possible to reliably seal.

As shown in FIG. 2, the forward / backward moving means 220 is rotatable 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. It is formed from a pinion 222 that is mounted and meshes 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 moved leftward (in the direction away from the drum 10) in FIG.
Raises the cap 246. Then, the advancing / retreating means 220 moves the nozzle units 200 for each color to the right (the direction approaching the drum 10), 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.

A 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 receiver 231, a waste ink tube 232, a waste ink pump 233, a sponge 235 and a waste ink tank 234 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.

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 rotation position of the drum 10 detected by the position detection means 100 reaches the set position, the supply timing adjustment control means (250) drives the medium supply 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.

Then, the negative pressure suction holding means 21 as an auxiliary means uses the negative pressure in the drum 10 established by the negative pressure establishing means 31 to suction hold the print medium M under the negative pressure. At the same time, the holding claw holding means 41 (45, 43) operates, and a portion (the leading end side) of the print medium M is held by the holding claw 42 on the drum 10 (1).
Hold in 1). Thus, the charging unit 51 forming the medium holding unit 20 charges the print medium M. Prior to this, the preheating means (130) forcibly preheats and dries the print medium M, so that the charging can be performed efficiently. Therefore, the printing medium M can be reliably attracted and held at the predetermined position in the Y direction on the outer peripheral surface 11 of the drum.

Further, since the leading end side of the printing medium M is held by the negative pressure suction before being held 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 controls the nozzle units 200C, 200M, 200Y, and 200B for each color (nozzle unit elements 205A, 205B, 205C, and 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.

Here, the unit moving means 110 includes the nozzle units 200C, 200M, 200Y, 20Y for each color.
0B is synchronized and moved forward in the X1 direction shown in FIG. At this time, while moving from the front dot D1 to the rear dot D2,
Move forward at a constant speed. Here, the control unit 250 drives and controls each of the inkjet nozzles 207 using the high-speed rotation movement in the Y direction during this period, and controls each of the dots (（D1n−1, D1n) of the row (F1) to which the previous dot D1 belongs. Is printed while rotating the drum 10 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, each dot (の D2n-1, D2n) of the column F2 to which the front dot D2 belongs is printed on the virtual locus R2. That is, while moving the inkjet nozzle 207a by the predetermined pitch PT in the X1 direction, the row (L)
And the plane of the row (F) [(L1, L2 to Ln) × (F1,
F2 to F4)], the A4 size multi-color printing can be performed 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.

Here, the nozzle unit 20 for each color is used.
If the amount of movement in the X direction of 0 and the number of rotations N of the drum 10 are selected, it is possible to perform color printing with switching to a desired resolution regardless of the pitch (PT, PTp) of the inkjet nozzles 207. That is, 300 dpi, 600 dpi using the nozzle unit 200 for each color having a resolution of 75 dpi.
The color printing operation switched to dpi,.

In FIGS. 1 and 4, the last line (Ln) on the rear end side belonging to the same column (F1) as the first line (L1) dot D1 on the leading 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.

Further, if the amount of reciprocating movement in the X1 direction is kept constant, and control is performed so as to reach the dot D2 when returning to the first row (L1) after one rotation of the drum 10, the first column (F1 ) First line (L1) on the leading end side of the printing medium M of the eye
The amount of positional deviation in the X1 direction from the last row (Ln) eye dot Dn on the rear end side belonging to the same column (F1) as the eye dot D1 is 1
It can be smaller than a 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 moves forward (X
It is moved backward by a predetermined pitch PT in the X2 direction at a higher speed than in the case of 1). Prepare for the next print.

At the same time, the removal timing adjustment control means (250) removes the holding force of the medium holding means 20 (21, 41) at a predetermined timing and activates the medium peeling means 140. That is, the peeling claw 141 peels the print medium M from the drum 10 (11), and after peeling, delivers the print medium M to the medium discharge / convey means 160 as a medium delivery means.

The medium discharging and conveying means 160 discharges and conveys the print medium M at a speed corresponding to its peripheral speed until the end of the printing medium M is separated from the drum 10 (11), and after the separation, 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 capable of holding the print medium M on the outer peripheral surface 11 and rotating at a constant peripheral speed about the axis (10S), and the drum 10 rotating around the drum 10 Nozzle units 200A, 200B, 200 each having a large number of ink jet nozzles 207a to 207n, each of which is misaligned in the direction.
C, 200D, and a unit moving means 110 for moving the nozzle unit 200 for each color in the axial direction of the drum.
The nozzle unit 200 for each color is formed so as to be movable by 1 / N of the pitch PT between the inkjet nozzles during the rotation, and the resolution is N times the resolution determined by the pitch PT between the inkjet nozzles by using the N rotations of the drum 10. Is formed so that color printing can be executed on the print medium M, while the nozzle unit 200 for each color moves the pitch PT between the inkjet nozzles, the drum is moved to N (4,
8) By switching to rotate, it is possible to perform multicolor printing in which the resolution is switched to 300 dpi or 600 dpi at a pitch PT (= 1/75 inch) between the ink jet nozzles corresponding to 75 dpi. In addition, since the moving speed of the printing medium M in the longitudinal direction is equal to the peripheral speed of the drum (e.g., equivalent to 120 rpm) and is continuous rotation, the printing speed is greatly increased as compared with the conventional inkjet printer (500). In addition, continuous printing operation for a large number of sheets (500 sheets) can be realized.

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

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 promoted. Print speed.

Further, since the reciprocating movement amount of the nozzle unit 200 for each color in the X direction is, 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.

Further, 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.

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 drum axis (X) direction, higher quality printing can be performed from this point as well.

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.

The nozzle unit elements 205A to 205A-2
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.

The medium supply means 90 is provided on one (right) side of the drum 10 and the nozzle units 200 for each color are provided on the other (left) side. Since the medium discharge / convey means 160 is provided, the discharge space (S) for leaving the print medium M after printing on the mounting table in front of the printer for a long time as in the conventional example (500) can be wiped out. Accordingly, the size of the print medium M can be substantially reduced, the handling of the print medium M after printing is facilitated, and the supply, printing, and discharge of the print medium M can be more smoothly performed.

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 has 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.

Further, the supply roller unit (90) contacts the leading end Mf of the print medium M to the contact portion 99 between the pair of rollers 91 and 92.
Is formed so that it can be supplied to the drum 10 side without skew after the posture is corrected and the printing medium M can be accurately held on the drum 10.

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

Further, the medium holding means 20 formed of the charging means 51 and the like is provided to hold the print medium M on the drum 10 by utilizing the charge attracting force, and the charge removing means 55 and the mechanical medium peeling means 140 are provided. Is provided so that the print medium M is peeled from the drum 10, so that the print medium M can be more stably and reliably held on the drum 10 and can be smoothly peeled from the drum 10. Therefore, high-speed color printing can be performed continuously and stably.

Further, a clamping claw holding means 41 is provided as an aid to the charging means 51, and a peripheral portion of the printing medium M, which is held by the negative pressure suction holding means 21, is held by the negative pressure suction holding means 21.
Since it is formed so as to be able to be pressed and held at 1, it is possible to guarantee more secure and stable holding.

Further, 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, a negative pressure suction holding means 21 is provided as an aid to the holding claw holding means 41, and is suction-held on the drum outer peripheral surface 11 through a suction hole 12 penetrating in and out of the drum in the radial direction and utilizing negative pressure. As a result, the print medium M can be held more reliably and stably.

Further, since the ink drying means 130 is provided to positively dry the ink on the printing medium M held by 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 that has been separated from the drum 10 and is being conveyed is being 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 discharge / convey means 160 is formed so as to be capable of discharging / conveying the print medium M peeled from the drum 10 by using the medium peeling 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 side, the printing medium M after printing is printed. Can be more stably and smoothly discharged and conveyed. The medium delivery means (141) further promotes this.

A direction switching means 190 is provided downstream of the medium discharge / convey means 160 so that the print medium M can be selectively switched to any 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.

The ink supply means 210 connects the nozzle units 200 for each color and the ink tanks 213 for each color with the ink supply tube 215 and is formed so that the pressure of each color ink can be equalized 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 and retreating 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.

[0165]

According to the present invention, the nozzle unit for each color is formed so as to be movable by 1 / N of the pitch PT between the ink jet nozzles while the unit moving means makes one rotation of the drum. Since the color printing can be performed on the print medium at a resolution N times the resolution determined by the pitch PT between the ink jet nozzles by using N rotations, it is possible to perform the multi-color printing with the resolution switched. In addition, since the moving speed in the longitudinal direction of the print medium is equal to the peripheral speed of the drum and is continuous rotation, a large multicolor color printing of, for example, one sheet of A4 size for three seconds can be performed as compared with the conventional inkjet printer. It is possible to increase the speed and perform a continuous printing operation of a large number (for example, 500) of sheets.

According to the second aspect of the present invention, the nozzle units for each color are displaced in the rotational direction of the drum such that the ink jet nozzles in the nozzle units for each color are located at the same position in the axial direction of the drum. Thus, the same effect as that of the first aspect of the invention can be obtained, and high-quality multi-color printing can be performed as compared with the conventional ink jet printer in which each ink jet nozzle is fed at a pitch PT.

According to the third aspect of the present invention, the unit moving means is formed to include a motor unit having a reciprocating rod which can switch between a retractable position and a retractable position by using the rotational force of the motor and switching the rotational direction of the motor. As a result, the same effects as those of the first and second aspects of the invention can be obtained, and furthermore, the reciprocating movement of the nozzle units for each color can be performed smoothly and quickly, so that more uniform and high-quality multi-colors can be obtained. Color printing can be performed, printing can be further speeded up, and noise related to reciprocal movement in the row direction can be eliminated.

Further, according to the invention of claim 4, the unit moving means is formed of one motor unit, and the nozzle units for each color can be synchronously moved in the axial direction of the drum using the reciprocating motion of the reciprocating rod. Therefore, in addition to the effects similar to those of the first to third aspects of the present invention, the dots for each color in the width (row) direction of the print medium can be accurately overlapped. Therefore, higher quality multi-color printing can be performed.

Further, according to the fifth aspect of the present invention, the motor unit is of a variable rotation speed type, and the motor unit is moved backward after the color printing operation with respect to the forward rotation speed during the color printing operation. A rotation speed switching control means for driving and controlling the motor at a high speed is provided.
In addition to having the same effect as the case of the invention of claim 4,
Furthermore, since the start timing for the next line printing can be advanced,
Higher-speed color printing can be performed.

[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 20 Medium holding means 21 Negative pressure suction holding means 31 Negative pressure establishing means 41 Nipping claw holding means 51 Charging means 53 Replenishment 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 121 motor unit (motor) 122 reciprocating rod 130 ink drying means (preheating means) 140 medium peeling means 160 medium Discharging / conveying means 181 ink drying means 190 direction switching means 200 nozzle unit for each color 205 nozzle unit element 207 ink jet nozzle 210 ink supply means 216 urging means 218 pressure adjusting means 220 advance / retreat moving means 230 waste ink collecting means 240 Cap lifting / lowering means 250 Control unit (rotation speed switching control means) M Print medium

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Takada 570 Ono-cho, Oni-cho, Taga-gun, Shizuoka Pref. In the Ohito Office

Claims (5)

[Claims] 1. A drum capable of holding a print medium on its outer peripheral surface and rotatable at a constant peripheral speed about an axis, and a plurality of ink jet nozzles which are displaced in the rotational direction around the drum and are respectively arranged in a rotational direction. A nozzle unit for each color, and a unit moving means for moving the nozzle unit for each color in the axial direction of the drum, and the nozzle unit for each color is moved between the ink jet nozzles while the unit moving means makes one rotation of the drum. , And is formed so as to be capable of performing color printing on a print medium at a resolution N times the resolution determined by the pitch PT between the inkjet nozzles using N rotations of the drum. Inkjet printer. 2. The nozzle unit for each color is displaced in the rotation direction of the drum such that the inkjet nozzles in the nozzle unit for each color are located at the same position in the drum axis direction. 2. The inkjet printer according to 1. 3. The unit moving means is formed to include a motor unit having a reciprocating rod which can be switched in and out by using the rotational force of a motor and switching the direction of rotation of the motor. The ink-jet printer as described. 4. The unit moving means is formed of one motor unit, and is formed so as to be able to synchronously move the nozzle units for each color in the axial direction of the drum using reciprocating motion of the reciprocating rod. The inkjet printer according to any one of claims 1 to 3. 5. A rotation speed switch wherein the motor unit is of a variable rotation speed type, and the motor unit is driven and controlled such that the backward rotation speed after the color printing operation is higher than the forward rotation speed during the color printing operation. 5. The ink jet printer according to claim 3, further comprising control means.