JPH10175339A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable execution of printing of high quality while preventing occurrence of nonuniformity in print density and oozing. SOLUTION: This printer has a medium sucking-retaining means 20 by negative pressure which sucks and retains a print medium M on the outer peripheral surface 11 of a rotatable drum 10 by using the negative pressure and ink jet nozzles 207 which are disposed in the periphery of the drum 10 and it is so formed that printing can be made on the print medium M in rotation which is sucked and retained on the drum 10 by the negative pressure, by jetting ink thereto, while the medium sucking-retaining means 20 by the negative pressure is so formed that it can suck and retain a non-printed region of the print medium M. A printed print medium holding means 165 is formed of a plurality of suction holes provided in a belt of a belt conveyor 161 and of a negative pressure generating means 167 for generating the negative pressure and also is so formed that it can suck, by the negative pressure, the non-printed region of the printed print medium M led onto the belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium negative pressure suction holding means for suctioning and holding a printing medium by utilizing a negative pressure on an outer peripheral surface of a rotatable drum, and an ink jet nozzle disposed around the drum. And an inkjet printer having the same.

[0002]

2. Description of the Related Art A nozzle unit for each color is reciprocated over the entire length in a row direction, and printing is performed during each forward movement to print one line, and after one line printing, a printing medium (plain paper, OHP paper, etc.). Compared to a so-called serial type ink-jet printer, M can be fed one line in the column direction and repeated, so that the printing speed can be greatly increased and continuous printing operation can be performed on a large number of sheets. The present applicant has proposed an ink-jet printer capable of achieving a great reduction in size (for example, Japanese Patent Application No. 8-296959).

That is, in FIG. 4, a drum 10 is rotatable at a constant peripheral speed and can hold a print medium M on an outer peripheral surface 11 thereof. Rotation of this drum 10 (Y)
The nozzle unit for each color (200C, 200M,
200Y, 200B).

Accordingly, the nozzle units for the respective colors (200C, 20C) are integrated over the entire length in the row direction (perpendicular to the paper surface).
0M, 200Y, 200B) or an integrated nozzle unit for each color (200C, 200M, 200Y, 200B) in which a plurality of nozzle unit elements are arranged in the row direction, while being reciprocated by the pitch between the inkjet nozzles, for example. Ink is sprayed from the inkjet nozzles 207 for each color onto the print medium M to print in the row direction, and the drum 1 is moved during the forward movement of the pitch between the inkjet nozzles.
Printing in the column direction can be performed while utilizing the rotation of 0.
That is, since the line-direction printing and the column-direction printing can proceed simultaneously, the printing speed can be greatly increased.

In addition, a nozzle unit for each color (200C
Etc.) and the respective color ink tanks (not shown) are disposed at separate positions, so that the nozzle unit 200 for each color is provided.
In addition, the point that the reciprocating movement speed in the row direction can be significantly increased further promotes higher printing speed, and the capacity of the ink tank for each color can be greatly increased.
This means that zero or more continuous printing operations can be performed.

In order to realize these, one side (right side in the figure) of the drum 10 is provided with a feeding means 60 and a medium feeding means 90.
On the other (left) side, a medium peeling means 140, a belt conveyor 161 and a direction switching means 190 are provided. Further, a medium negative pressure suction holding unit 20 capable of holding the print medium M by negative pressure is provided on the drum 10 and its periphery.
Is provided. In some cases, the charge holding unit is provided as an auxiliary unit.

The feeding means 60 can selectively feed the printing medium M one by one from one of the cassette feeding means 71 and the manual feeding means 61. The medium supply means 90 feeds the fed print medium M to the drum 1 at a predetermined timing.
Feed to the 0 side.

As shown in FIGS. 5 and 6, the medium negative pressure suction holding means 20 has a number of suction holes 12 penetrating radially in and out of the drum 10, and a negative pressure capable of generating a negative pressure in the drum 10. The print medium M is formed so as to be able to be sucked and held on the outer peripheral surface 11 of the drum.

The charge adsorption and holding as auxiliary means is performed by the charging means 51. The charging means 51 charges the print medium M with a positive charge and uses the charge attraction generated between the print medium M and the grounded drum 10 to transfer the print medium M to the drum outer peripheral surface 11.
Hold by suction. The replenishment charging means 55 replenishes the amount of the decrease in the charge attraction force accompanying the execution of printing. After the printing, the charge removing means 55 adds a charge opposite to that of the charging means 51 to remove the charge for adsorption.

The medium peeling means 140 peels the print medium M from the drum 10 after printing, and the belt conveyor 161 discharges and transports the peeled print medium M leftward in FIG. The belt conveyor 161 is provided with a printed medium holding unit 165 so that the print medium M can be more reliably discharged and conveyed.

As shown in FIG. 7, the printed medium holding means 165 sucks and holds the printed print medium M through a plurality of suction holes 166 penetrated through the belt 162 of the belt conveyor 161 and the suction holes 166. And a negative pressure generating means 167 for generating a negative pressure for performing the printing operation.

The direction changing means 190 selectively switches between the discharge tray 192 and the upper discharge tray 193.

Thus, since the feeding, supply, holding, printing, peeling, and discharging and conveying of the print medium M can be continuously performed, multicolor printing of, for example, 20 sheets or more of A4 size can be performed in one minute.

[0014]

In the above-mentioned printer, the drum 10 is rotated at a high speed (for example,
In order to achieve high-speed printing at a peripheral speed of 800 mm / sec), it is necessary to increase the negative pressure attracting force acting on the printing medium M and firmly hold the printing medium M on the drum outer peripheral surface 11.

However, when the negative pressure attraction force is increased, the portion of the print medium M facing each suction hole 12 is particularly strongly sucked, and the ink on the opposed portion permeates deeper than the other portions. , Uneven print density,
The bleeding occurs and the printing quality is reduced.

On the other hand, in the printed medium holding means 165, even when the negative pressure attraction force is increased, the ink printed on the print medium M may bleed and the print quality may be degraded.

An object of the present invention is to provide an ink-jet printer capable of stably performing high-quality printing while preventing the occurrence of print density unevenness and bleeding.

[0018]

According to a first aspect of the present invention, there is provided a rotatable drum, medium negative pressure suction holding means for suctioning and holding a print medium on the outer peripheral surface of the drum by utilizing negative pressure, and a drum. An ink jet nozzle disposed in the periphery thereof, the ink is sprayed onto a rotating print medium that is suction-held by the drum at a negative pressure to form a printable medium, and the medium negative-pressure suction holding means is provided on the non-printing medium. The printing area is formed so as to be able to be held by suction.

In this invention, the medium negative pressure suction holding means suctions and holds the non-printing area of the print medium. Therefore, a situation in which the ink sucked onto the print medium from the ink jet nozzle is strongly sucked and the print density becomes uneven or bleeds does not occur. As a result, high quality printing can be stably performed while preventing print density unevenness and bleeding.

According to a second aspect of the present invention, there is provided a belt conveyor for conveying a print medium printed by spraying ink from an ink jet nozzle in a predetermined direction, and a printed medium holding means for holding the printed print medium on the belt conveyor. And a plurality of suction holes provided in a belt forming the belt conveyor, and a negative pressure for sucking and holding a printed printing medium through each suction hole. And a negative pressure generating means for generating, and a non-printing area of a printed printing medium introduced onto the belt is formed so as to be capable of attracting negative pressure.

According to the invention, the printed medium holding means sucks the non-printed area of the printed print medium with a negative pressure. Therefore, a situation does not occur in which the ink printed on the printed printing medium is strongly sucked and blurred. As a result, high quality printing can be stably performed while preventing print density unevenness and bleeding.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG.
As shown in FIG. 3, the medium negative pressure suction holding means 20 is configured to be capable of suction holding the non-printing area of the print medium M.

The ink jet printer has the same structure as that of the prior proposal (Japanese Patent Application No. 8-296959) shown in FIG.

As shown in FIGS. 1 to 3, the medium suction and holding means 21 includes a negative pressure establishing means 31 and a number of suction holes 12 formed in the outer peripheral surface 11 of the drum. By generating a negative pressure in the space 16, the non-printing area of the print medium M can be suction-held by the negative pressure through each suction hole 12.

Each suction hole 12 is formed through the outer peripheral surface 11 so as to face a non-printing area of the print medium M held on the outer peripheral surface 11 of the drum. In this embodiment, when the print medium M is suction-held by the negative pressure on the drum outer peripheral surface 11, the suction holes 12 form the front end portion Ma, the rear end portion Mb, and the left and right end portions (Ml) outside the print region Mi. , Mr).

The negative pressure establishing means 31 includes a corresponding suction port 34 corresponding to the suction port 14 on the drum 10 side and the corresponding suction port 3
4 and a suction fan 32 that sucks air to establish a negative pressure in the drum internal space 16 through a duct 35.

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. The side end plate (end surface) 15L is a blind plate. 10S
Is a rotation axis of the drum 10.

In FIG. 1, reference numeral 9 denotes a sensor for detecting the rotational position of the drum. The rotation position of the drum 10 is grasped by the sensor 9 detecting a specific suction hole (a suction hole facing the leading end portion Ma of the print medium M) 12 of the rotating drum 10. As described above, the specific suction hole 12 is detected by the sensor 9.
Medium supply means 90 after a predetermined time has passed since the detection of
Is driven to feed the print medium M to the drum 10, so that the non-print areas (Ma, Mb, Ml, and Mr) of the print medium M are sucked while facing the suction holes 12.

In this configuration, the medium negative pressure suction holding means 2
0 is a non-printing area (Ma, Mb, Ml, M
r) is held by adsorption. Therefore, a situation in which the ink sucked onto the print medium M from the ink jet nozzle 207 is strongly sucked and the print density becomes uneven or bleeds does not occur. As a result, high quality printing can be performed stably while speeding up printing while preventing the occurrence of print density unevenness and blurring.

(Second Embodiment) A second embodiment is shown in FIG. 1 and FIG. In the ink jet printer according to the second embodiment, the printed medium holding unit 165 is configured such that the non-printed area (for example, the leading end portion Ma) of the printed print medium M is used.
Is configured to be able to be attracted by negative pressure.

The printed medium holding means 165 has a plurality of suction holes 166 formed through the belt 162 of the belt conveyor 161 in the thickness direction, a suction fan 167, and the suction fan 167 and the suction pipe 168. An air suction member 169 connected to each of the suction holes 166 and capable of sucking air through the suction holes 166 is formed so that the printing medium M can be suctioned to the belt 162 through each suction hole 166 by negative pressure. Each suction hole 162 is penetrated through the belt 162 so as to face a non-printing area (tip Ma) of the print medium M with print held on the belt 162.

In this configuration, the printed medium holding means 16
5 sucks the non-printing area (Ma) of the printed printing medium M with a negative pressure. Therefore, a situation does not occur in which the ink printed on the printed printing medium M is strongly sucked and blurred. As a result, it is possible to speed up printing by discharging the printed printing medium M while preventing the occurrence of print density unevenness and bleeding, and to stably perform high quality printing.

[0033]

According to the first aspect of the present invention, since the medium negative pressure suction holding means is formed so as to be able to suction and hold the non-printing area of the print medium, the ink sprayed from the ink jet nozzle onto the print medium is strongly suctioned. Print density difference,
No bleeding occurs. As a result, high quality printing can be stably performed while preventing print density unevenness and bleeding.

According to the second aspect of the present invention, since the non-printed area of the printed print medium is formed so as to be able to attract the negative pressure, the printed print medium holding means can prevent print density unevenness and bleeding. High quality printing can be performed stably.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a view for explaining an arrangement of suction holes of a medium negative pressure suction holding unit.

FIG. 3 is a view for explaining the negative pressure suction operation of the medium negative pressure suction holding means.

FIG. 4 is a diagram for explaining a second embodiment of the present invention.

FIG. 5 is a diagram for explaining a previously proposed printer.

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

FIG. 7 is a view for explaining a printed medium holding unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Drum 11 Outer peripheral surface 12 Suction hole 20 Medium negative pressure adsorption holding means 31 Negative pressure establishing means 161 Belt conveyor 162 Belt 165 Printed medium holding means

Claims (2)

[Claims] A rotatable drum; a medium negative pressure suction holding means for suctioning and holding a print medium by using a negative pressure on an outer peripheral surface of the drum; and an ink jet nozzle disposed around the drum. In addition, ink is sprayed onto the rotating print medium that has been suction-held on the drum and is formed so that printing is possible, and the medium negative-pressure suction holding means is formed so that a non-printing area of the print medium can be suction-held. An inkjet printer characterized by the following. 2. An ink jet printer comprising: a belt conveyor that conveys a print medium printed by spraying ink from an ink jet nozzle in a predetermined direction; A plurality of suction holes provided in a belt forming the belt conveyor, and a negative pressure generating means for generating a negative pressure for sucking and holding a printed printing medium through each suction hole; And a non-printing area of a printed printing medium introduced on a belt is formed so as to be capable of attracting a negative pressure.