JP2008254355A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer which enables crop printing to be carried out without soiling a print medium and makes the size of the print medium hard to limited. <P>SOLUTION: An ink jet head 6 is disposed to eject ink droplets over the entire region of a print medium 2 being carried in the direction of intersecting its carrying direction, a carrying roller 14 and a pressure contact roller 15 are provided on the upstream side of the ink jet head 6 in the direction of carrying print medium, a carrying belt 1 is provided on the downstream side of the ink jet head 6 in the carrying direction of print medium, a receiver 11 for receiving ejected ink droplets is provided below the ink jet head 6, and the print medium 2 is carried while being attracted to the outer circumferential surface of the carrying belt 1 so that ink droplets ejected from the ink jet head 6 to the outside of the outline of the print medium 2 are received by the ink receiver 11 after passing through the through hole 16 of a plane regulation body 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a printing apparatus that prints predetermined characters, images, and the like by ejecting liquid from a plurality of nozzles to form fine particles (dots) on a print medium.

Inkjet printers, which are one of such printing devices, are generally inexpensive and can easily obtain high-quality color printed matter. Therefore, with the spread of personal computers and digital cameras, not only offices but also general users. It has become widespread.
Such an ink jet printer discharges (jets) liquid ink droplets from the nozzles of the ink jet head while relatively moving the print medium and the liquid ejecting head (also referred to as an ink jet head), thereby forming minute ink dots on the print medium. In this way, a desired printed matter is created by drawing predetermined characters and images on the print medium. A device that places an ink jet head on a moving body called a carriage and moves it in a direction crossing the conveyance direction of the print medium is generally called a multipass ink jet printer. On the other hand, a long inkjet head (not necessarily integrated) is arranged in a direction intersecting the print medium conveyance direction to enable printing in a so-called one pass. It is called a “printer”.

In such an ink jet printer, for example, an electric charge is applied to the transport belt to charge it, and a print medium made of almost an insulator is electrostatically adsorbed to the transport belt and transported, and ink droplets are ejected from the ink jet head onto the transported print medium. There are some which perform printing by discharging. In addition, there is also a type in which a print medium is adsorbed on a conveyance belt and conveyed by negative air pressure. Such a print medium conveying method is particularly effective in a line head type ink jet printer. In addition, in the inkjet printer described in Patent Document 1 below, a concave groove having a rectangular shape in plan view that is slightly larger than the outer size of the print medium is provided on the outer peripheral surface of the transport belt, and the print medium is formed by matching the outer shape with the concave groove. By adsorbing and ejecting ink droplets to the outer shape of the printing medium, it is possible to perform full surface printing without margins, so-called borderless printing. Note that ink droplets outside the outer shape of the print medium are stored in the concave grooves.
JP 2005-59475 A

However, as described in Patent Document 1, it is extremely difficult to accurately adsorb the print medium to the conveyance belt by aligning the outer shape with the concave groove formed on the outer peripheral surface of the conveyance belt. When the position is shifted, the surface opposite to the printing surface of the printing medium is soiled with ink adhering to the conveyance belt. Further, unless the ink in the groove is removed, the surface opposite to the printing surface of the printing medium is similarly soiled. There is also a problem that the size of the print medium is limited by the formed concave grooves.
The present invention has been made paying attention to the above-described problems, and provides a printing apparatus that can perform borderless printing without fouling the print medium and that is not easily limited in size of the print medium. It is for the purpose.

The printing apparatus of the present invention is provided on the upstream side of the liquid ejecting head in the print medium transport direction, the liquid ejecting head performing liquid ejecting over the entire direction intersecting the transport direction of the print medium with respect to the transported print medium. Roller conveying means, belt conveying means provided on the downstream side in the print medium conveying direction of the liquid ejecting head, and a liquid receiver for receiving liquid ejected below the liquid ejecting head, the belt conveying means, The print medium is adsorbed and conveyed on the outer peripheral surface of the conveyance belt.

According to the present invention, the liquid ejected from the liquid ejecting head outside the outer shape of the print medium is received by the liquid receiver, and the belt transport means on the downstream side of the liquid ejecting head in the print medium transport direction attracts and transports the print medium. Therefore, borderless printing can be performed on the print medium without the print medium being soiled by a liquid such as ink, and the size of the print medium is not particularly limited.
In the printing apparatus according to the aspect of the invention, the length of the liquid receiving area ejected from the liquid ejecting head by the liquid receiver in the direction intersecting the print medium transport direction is the length in the direction intersecting the print medium transport direction. It is characterized by being larger than the thickness.

According to the present invention, the liquid ejected from the liquid ejecting head outside the outer shape of the print medium can be reliably received by the liquid receiver, thereby preventing the print medium or the apparatus itself from being soiled by the liquid such as ink. be able to.
In the printing apparatus of the present invention, the conveyance belt may adsorb the print medium with electrostatic force.
In the printing apparatus of the present invention, the conveyance belt may adsorb the print medium with negative air pressure.

Next, as an example of the printing apparatus of the present invention, an ink jet printer that discharges ink and prints characters, images, and the like on a print medium will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an ink jet printer according to the present embodiment, FIG. 1a is a front view of the ink jet printer according to the present embodiment, and FIG. 1b is a plan view. Reference numeral 6 in the figure denotes an ink jet head as a liquid ejecting head that ejects (discharges) liquid such as ink in the form of droplets. Reference numeral 1 in the figure denotes printing paper on the downstream side of the ink jet head 6 in the print medium conveyance direction. It is an endless transport belt for transporting the print medium 2 such as. The conveyor belt 1 is wound around a driving roller 3 disposed at the left end in the figure, a driven roller 4 disposed at the right end in the figure, and a tension roller 5 disposed below the central part thereof. It has been turned. The drive roller 3 is driven to rotate in the direction of the arrow in the figure by a conveyance motor (not shown), and the print medium 2 is attracted to the conveyance belt 1 charged by a charging roller, which will be described later. Transport to the left, that is, in the direction of the arrow. The driven roller 4 is grounded so as to apply a voltage with the conveying belt 1 being sandwiched between the driven roller 4 and a contact portion of a charging roller described later. The tension roller 5 is disposed inside the conveyor belt 1 and is biased downward by a tension applying mechanism (not shown), thereby applying tension to the conveyor belt 1. This conveyance belt 1 constitutes a belt conveyance means of the present invention.

A charging roller 7 as a charging unit is in contact with the conveyor belt 1 so as to face the driven roller 4, and an AC power supply 8 of about 10 to 50 Hz is connected to the charging roller 7. The arrangement of the charging roller 7 corresponds to the position immediately before the feeding position of the printing medium 2 to the conveying belt 1. The charging roller 7 charges the surface of the conveyance belt 1 made of a medium / high resistance by charging, charges the print medium 2 by the charge, and charges and conveys the print medium 2 by the dielectric polarization. The belt 1 conveys the print medium 2 by electrostatic force due to the electric charge of the dielectric portion on the surface of the belt 1.
Adsorb to the surface of The charging roller 7 is pressed against the transport belt 1 by a spring (not shown).

For example, as shown in FIG. 2, the inkjet head 6 has a relatively small head unit having a length of about 25 to 30 mm in a direction intersecting the print medium conveyance direction arranged in a staggered manner in a plan view. Yellow (Y), Magenta (M), Cyan (C), Black (
4) Nozzle rows of four colors are formed, and the nozzle rows of each color are shifted in the print medium transport direction. The nozzles at the end of each inkjet head (head unit) 6 in the direction intersecting the print medium conveyance direction are the nozzles at the print medium conveyance direction end of the nozzle array of the adjacent inkjet head 6 arranged in a staggered pattern. It arrange | positions so that it may superpose | polymerize in a printing medium conveyance direction. Then, a necessary amount of ink droplets are simultaneously ejected from these nozzles to necessary locations, thereby forming and outputting minute ink dots on the print medium 2. By performing this for each color, it is possible to perform printing by so-called one-pass only by passing the print medium 2 adsorbed on the conveyor belt 1 once. That is, the area where the inkjet head 6 is disposed corresponds to a printing area.

As a method of discharging and outputting ink from each nozzle of the inkjet head, an electrostatic method,
There are piezo method and film boiling ink jet method. In the electrostatic method, when a drive pulse is applied to the electrostatic gap, which is an actuator, the diaphragm in the cavity is displaced, causing a pressure change in the cavity, and an ink droplet is ejected from the nozzle by the pressure change. is there. In the piezo method, when a drive pulse is applied to a piezo element that is an actuator, the diaphragm in the cavity is displaced to cause a pressure change in the cavity, and an ink droplet is ejected from the nozzle by the pressure change. In the film boiling ink jet method, there is a micro heater in the cavity, the ink is instantaneously heated to 300 ° C. or more, the ink becomes a film boiling state, bubbles are generated, and the ink droplet is ejected from the nozzle by the pressure change. Is.
The present invention can be applied to any ink droplet ejection method.

The print medium 2 before being fed is stored in the paper feed unit 12, and auxiliary rollers 10 d and 10 f that feed the print medium 2 of the paper feed unit 12 and a feed are provided in the print medium conveyance direction ahead of the paper feed unit 12. Rollers 13d and 13f are disposed, and a feed roller 14 and a pressure contact roller 15 are disposed ahead of the feed rollers 13d and 13f in the print medium conveyance direction. This feed roller 14
The pressure roller 15 corrects the posture of the printing medium 2 abutted by the feed rollers 13d and 13f, adjusts the conveyance timing of the printing medium 2, and moves the printing medium 2 to the printing area at the adjusted conveyance timing. That is, it is for conveying below the inkjet head 6. The feed roller 14 and the pressure roller 15 constitute a roller conveying unit of the present invention. The feed roller 14 may be surface-coated with, for example, urethane or ceramic particles in order to increase the friction coefficient and increase the printing medium conveying force.

A flat plate-shaped restricting body 9 called a platen is disposed between the feeding roller 14 and the pressure roller 15 and the conveying belt 1, that is, below the ink jet head 6. As the name suggests, the plane regulating body 9 is a print medium 2 that is transported to a print area below the inkjet head 6.
The line head type inkjet head 6 as in this embodiment is particularly important in terms of ejecting ink droplets to a predetermined position and securing a gap with the print medium 2. A series of ink receivers 11 that cover at least the ink droplet ejection range from the inkjet head 6 are disposed below the plane regulation body 9, and ink ejected from the inkjet head 6 is disposed on the plane regulation body 9. A through hole 16 is formed through which the droplet passes and is received by the ink receiver 11. Therefore, when ink droplets are ejected from the inkjet head 6 without the print medium 1 above the through holes 16 of the plane regulation body 9, the ink drops pass through the through holes 16 of the plane regulation body 9 and become ink. Received at the receiver 11.

As is well known, borderless printing in an ink jet printer is performed by ejecting ink droplets slightly outside the outer shape of the printing medium 2. In the present embodiment, the ink droplets ejected outside the outer shape of the printing medium 2 pass through the through hole 16 of the plane regulation body 9 and receive the ink receiver 1.
1, the ink does not adhere to the upper surface of the plane regulation body 9 or the surface opposite to the print surface of the print medium 2, and the surface opposite to the print surface of the print medium 2 does not get dirty. . The through-hole 16 can also cause the ink receiver 11 to receive, for example, ink droplets that are ejected in a state where the print medium 2 is not below the inkjet head 6. It can also be used for flushing.

Therefore, according to this inkjet printer, the auxiliary rollers 10d, 1d,
One sheet of the print medium 2 is taken out by 0f, transferred to the feed rollers 13d and 13f, and fed to the nip portion of the conveying roller 14 and the pressure roller 15. Even after the front end of the print medium 2 in the conveyance direction comes into contact with the nip portion of the conveyance roller 14 and the pressure roller 15, the feed roller 1
When the print medium 2 is fed by a predetermined amount by 3d and 13f, the print medium 2 is bent. After the bending occurs in this way, when the conveyance force of the print medium 2 by the feed rollers 13 d and 13 f, specifically, the clamping force is released, the front end portion of the print medium 2 in the conveyance direction becomes the nip between the conveyance roller 14 and the pressure roller 15. The posture of the print medium 2 is corrected in a state where it hits the part.

When the posture of the print medium 2 is corrected, the transport roller 14 and the pressure roller 15 are rotated to feed the print medium 2 above the plane regulation body 9. Since the printing area below the inkjet head 6 is above the plane regulation body 9, ink droplets are ejected from the necessary nozzles of the inkjet head 6 to print on the printing medium 2. At this time, even if borderless printing is performed, the ink droplets ejected outside the outer shape of the printing medium 2 are received by the ink receiver 11 through the through hole 16 of the plane regulating body 9. In addition, ink does not adhere to the surface opposite to the printing surface of the print medium 2, and they are not soiled.

The print medium 2 on which the printing has been performed slides on the upper surface of the plane regulation body 9 and is fed to the upper surface of the transport belt 1. Since the conveyance belt 1 is alternately charged with the reverse polarity by the AC power supply 8 and the charging roller 7 in the printing medium conveyance direction, when the printing medium 2 is sent to the upper surface thereof, the above-described dielectric polarization acts. The print medium 2 is attracted to the upper surface of the transport belt 1 by electrostatic force. In this state, when the drive roller 3 is rotationally driven by an electric motor (not shown), the rotational driving force is transmitted to the driven roller 4 via the transport belt 1, and the print medium 2 is transported toward the paper discharge unit. When the print medium 2 reaches the paper discharge unit, the print medium 2 is discharged to the paper discharge unit while being separated from the surface of the transport belt 1 by a separation device (not shown), for example.

As described above, according to the ink jet printer of the present embodiment, the ink jet head 6 that ejects ink droplets in the entire direction intersecting the transport direction with respect to the transported print medium 2, and the print medium transport direction of the ink jet head 6 A conveyance roller 14 and a pressure roller 15 (roller conveyance unit) provided on the upstream side, a conveyance belt 1 (belt conveyance unit) provided on the downstream side in the print medium conveyance direction of the inkjet head 6, and a lower part of the inkjet head 6. An ink receiver 11 (liquid receiver) that receives ejected ink droplets is provided, and the belt conveying means is configured to adsorb and convey the printing medium 2 to the outer peripheral surface of the conveying belt 1. When the ink droplets ejected from the ink jet head 6 are received by the ink receiver 11 through the through hole 16 of the plane regulating body 9. In addition, since the conveyance belt 1 on the downstream side in the print medium conveyance direction of the inkjet head 6 adsorbs and conveys the print medium 2, borderless printing can be performed on the print medium 2 without the print medium 2 being soiled by ink. The size of the print medium 2 is not particularly limited.

In addition, since the length of the ink drop receiving area ejected from the inkjet head 6 by the ink receiver 11 in the direction intersecting the print medium conveyance direction is larger than the length in the direction intersecting the print medium conveyance direction, Ink droplets ejected from the inkjet head 6 outside the outer shape of the print medium 2 can be reliably received by the ink receiver 11, thereby preventing the print medium 2 and the apparatus itself from being soiled by liquid such as ink. it can.
In addition, the invention can be easily implemented by using the conveyance belt 1 to adsorb the print medium with electrostatic force.

Next, a second embodiment of an ink jet printer to which the printing apparatus of the present invention is applied will be described with reference to FIG. FIG. 3A is a schematic front view of the ink jet printer of the present embodiment, and FIG. 3B is a plan view of the ink jet printer. In addition, the same code | symbol is attached | subjected to the component requirements equivalent to 1st Embodiment, and the detailed description is abbreviate | omitted. The conveyance belt 1 of the first embodiment sucks and conveys the print medium 2 by electrostatic force. In this embodiment, the print medium 2 is sucked and conveyed by the conveyance belt 1 using negative air pressure.

For this reason, in this embodiment, the AC power supply and the charging roller of the first embodiment, which are conveying belt charging means, are removed. Instead, a thin box-shaped duct 17 whose upper surface is made of a mesh, for example, is disposed immediately below the upper side surface that conveys the print medium 2 on the inner peripheral surface of the conveyance belt 1. A suction fan 18 is connected. In this embodiment,
A large number of small holes are formed in an area of the conveying belt 1 where at least the print medium 2 must be sucked. In addition, it may replace with opening of a small hole and may make a relevant part mesh shape.

Therefore, when the suction fan 18 is driven to suck the air in the duct 17, negative air pressure is generated on the outer peripheral surface of the transport belt 1 through the small holes, and the print medium 2 sent to the outer peripheral surface of the transport belt 1 is air negative. The pressure is sucked by the conveyor belt 1. Accordingly, the print medium 2 printed on the printing surface is sucked by the transport belt 1 without being soiled and discharged to the paper discharge unit.
As described above, in the present embodiment, the invention is easily implemented by the conveyance belt that adsorbs the print medium with negative air pressure.

In the above-described embodiment, only a case where a staggered ink jet head (head unit) is moved in plan view has been described in detail. However, for example, the length is longer than the length in the direction intersecting with the conveyance direction of the print medium. You may use the long inkjet head which has.
Further, for example, when the print medium is attracted to the transport belt by electrostatic force as in the first embodiment, and the print medium fed onto the outer peripheral surface of the transport belt is not easily electrostatically attracted. Alternatively, the upper surface of the print medium may be guided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows 1st Embodiment of the line head type inkjet printer to which this invention is applied, (a) is a top view, (b) is a front view. It is explanatory drawing of the inkjet head of the inkjet printer of FIG. It is a schematic block diagram which shows 2nd Embodiment of the line head type inkjet printer to which this invention is applied, (a) is a top view, (b) is a front view.

Explanation of symbols

1 is a conveying belt, 2 is a printing medium, 3 is a driving roller, 4 is a driven roller, 5 is a tension roller, 6 is an ink jet head, 7 is a charging roller, 8 is an AC power supply, 9 is a plane regulating body, 1
0f, 10d are auxiliary rollers, 11 is an ink receiver, 12 is a paper feeding unit, 13f and 13d are feed rollers, 14 is a transport roller, 15 is a pressure roller, 16 is a through hole, 17 is a duct, and 18 is a suction fan.

Claims (4)

A liquid ejecting head that ejects liquid over the entire direction intersecting the transport direction of the print medium with respect to the transported print medium, roller transport means provided upstream of the liquid ejecting head in the print medium transport direction, and the liquid A belt conveying unit provided on the downstream side of the ejection head in the print medium conveying direction; and a liquid receiver for receiving a liquid ejected below the liquid ejecting head, wherein the belt conveying unit prints on an outer peripheral surface of the conveying belt. A printing apparatus characterized by adsorbing and transporting a medium. The length of the liquid receiving area ejected from the liquid ejecting head by the liquid receiver in a direction intersecting the print medium transport direction is longer than a length in a direction intersecting the print medium transport direction. The printing apparatus according to 1. The printing apparatus according to claim 1, wherein the conveyance belt adsorbs the print medium with electrostatic force. The printing apparatus according to claim 1, wherein the conveyance belt adsorbs a print medium with negative air pressure.

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