JPH05155008A - Ink jet printer - Google Patents

Abstract

PURPOSE:To create a simple-structure transfer-type ink jet printer and further, record data in a continuous action to realize a high-speed operation. CONSTITUTION:A recording head 2 is allowed to scan in a direction which does not cross directly the movement direction of a transfer medium 1, and thus the components are constituted so as to meet the following relationship: (effective recording width F)=(transfer medium transport sped)X(recording head shuttle back/forth time).

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. More specifically, the present invention relates to a transfer type inkjet printer that forms an ink image on a transfer medium and then transfers it to a recording medium to obtain an ink image on the recording medium.

[0002]

2. Description of the Related Art In contrast to a direct type ink jet printer which directly ejects ink droplets onto a recording paper to form an ink image, a transfer type ink jet printer has no ink jet clogging caused by unintended contact between the recording paper and the recording head. In addition, high reliability can be obtained, and high image quality can be obtained without depending on paper quality (smoothness of paper surface). As a conventional transfer type inkjet printer, there are JP-A-59-22595 and USP4538.
The configuration described in 156 is known. FIG. 8 is a perspective view of a conventional transfer type ink jet printer, and FIG. 9 is a sectional view. In these figures, the cylindrical transfer medium 2
The recording head 202 having a plurality of ink jets is provided for 01 with a gap. The plurality of inkjets are arranged at predetermined intervals in the rotation axis direction of the transfer medium 201,
The recording head 202 can move in this direction. To form an ink image on the transfer medium 201, the recording head 202 is moved in the rotation axis direction of the transfer medium 201 while continuously rotating the transfer medium 201 to eject ink, and an ink image is formed for each ring-shaped region. After forming an ink image for one page, the recording paper 203, which is a recording medium, is brought into contact with the transfer medium 201 and pressed by the pressure roller 204, whereby the ink image is transferred to the recording paper 203.

[0003]

In the ink jet printer of the prior art described above, since the ink image for one page is formed on the recording medium and then transferred to the recording paper, the ink image is formed on the transfer medium. It is necessary that the recording paper and the pressure roller that presses the recording paper do not come into contact with the transfer medium. For this reason, it is necessary for the recording paper pressing unit to be configured to be able to release the pressing force and to separate the pressing roller from the transfer drum except during the transfer operation. Therefore, there is a problem that the mechanism is complicated and the control is complicated. Further, since the recording operation is performed in two steps of forming an ink image on the transfer medium and transferring it to the recording medium, the operation is not continuous and is not suitable for high speed recording.

The present invention solves this problem, and an object thereof is to realize a transfer type ink jet printer having a simple structure. Still another object is to realize continuous operation and high speed recording by simultaneously performing the ink image forming process and the transfer process at different positions.

[0005]

An ink jet printer of the present invention comprises a recording head having at least one ink jet for ejecting ink droplets, a transfer medium which moves through a gap with respect to the ink jet, and the recording head. In an inkjet printer having a pressure applying unit that forms an ink image on the transfer medium and transfers the ink image from the transfer medium to the recording medium, the recording head has an inclination angle with respect to a direction orthogonal to a transport direction of the transfer medium. Is configured to scan the surface of the transfer medium,
Conveyance of the transfer medium and scanning of the recording head are continuously performed in synchronization with each other, and an ink image is formed in a direction orthogonal to the conveyance direction of the transfer medium. As a result, the ink image forming process and the transfer process can be simultaneously performed at different positions, and continuous high-speed recording is performed.

[0006]

EXAMPLES Examples of the present invention will be described.

The configuration of the ink jet printer is shown in a block diagram in FIG. The print data sent from the external computer 101 is received by the receiving unit 102 and stored in the memory 103 as image information. Information in the memory 103 is sent to the head drive circuit 104 based on a signal from the mechanism 105, and ink is ejected from the head 106 at a predetermined timing. FIG. 1 is a perspective view of a mechanism of an inkjet printer according to a first embodiment of the present invention, and FIG. 2 is a sectional view. A recording head 2 is provided on a transfer drum 1, which is a transfer medium.
Scans. The recording head 2 includes a plurality of inkjet 64
The individual pieces are arranged at intervals of 1/300 inch in the conveying direction of the transfer drum 1. Therefore, the effective recording width is 5.5 mm. The recording head 2 is guided by the guide shafts 3 and 4 through a gap with the surface of the transfer drum 1, and the head scanning motor 5 scans the transfer drum 1. By the scanning operation, the transfer drum 1
An ink image is formed in a predetermined band-shaped area on the upper side. The first paper feed roller 6 and the second paper feed roller 7 convey the recording paper 8 which is a recording medium. The recording paper 8 is pressed by the pressure roller 9 and comes into contact with the recording paper.

Next, the operation will be described. In FIG. 1, during the recording operation, the transfer drum 1 is rotated at a constant speed in the direction of arrow A, the recording head 2 is scanned at a constant speed in the direction of arrow B, and the recording paper 8 is conveyed at a constant speed in the direction of arrow C. Meanwhile, ink droplets are ejected from a predetermined inkjet. Even after scanning a predetermined recording area, the recording paper 8 and the transfer drum 1
The recording head 2 returns in the direction of arrow D while being rotated at a constant speed and conveyed in the previous direction. At this time, ink is not ejected. Thereafter, the recording head 2 scans the transfer drum 1 while reciprocating similarly. By the scanning operation, an ink image is formed on the surface of the transfer drum 1 in a belt-like area (shown by a hatched area 10 in FIG. 1) parallel to the rotation axis of the transfer drum 1. Further, the surface of the transfer drum 1 is filled without gaps by repeated scanning. The ink image on the transfer drum 1 then contacts the recording paper 8 and is transferred to the recording paper 8 under pressure. As shown in FIG. 4, a stripe-shaped area 41 parallel to the edge of the recording paper is formed on the recording paper 8 corresponding to one scan, and further adjacent areas 42, 43 are formed by the subsequent scanning operation. , 44 to record without gaps.

The above scanning operation will be described with reference to FIG. FIG. 5 shows the transfer drum 1 and the guide shafts 3 and 4 having an inclination angle with respect to the direction orthogonal to the transport direction of the transfer drum 1.
(Indicated by the central axis). At the end of the scanning area on the transfer drum 1, the points P and R on the axis of the transfer drum 1 and the end points Q, S, V, and W of the guide axis are: VQ = WS PV = PQ = RW = RS It is located in. VW and QS take into consideration the rotation speed of the transfer drum 1 and the scanning speed of the recording head 2, and the axis P
There is a twist relationship with R.

This relationship will be described with specific numerical values in this embodiment. The transfer drum 1 rotates at a constant speed at an outer peripheral speed of 11 mm / s. The reciprocating operation of the recording head 2 is performed in 500 ms. That is, the effective recording width of the recording head 2 during one scanning time (shown by the dimension F in FIGS. 1 and 4) is 5.
It is 5 mm. Since the transfer drum 1 is moved by a distance corresponding to (), the transfer drum 1 can be recorded without gaps by continuous scanning.

As described above, ideally it is desirable that the scanning locus of the recording head 2 is spiral with respect to the stationary transfer drum 1, but in the present embodiment, a linear guide which is not parallel to the rotation axis of the transfer drum 1. Linear scanning is performed on axes 3 and 4. The error of the scanning locus in this case from the ideal locus will be described. The diameter of the transfer drum 1 is 60 mm, the scanning range is 210 mm,
When the effective recording width is 5.5 mm, the area obtained by scanning with the linear guide shafts 3 and 4 of this embodiment (area 10 in FIG. 1).
The shape error of is expressed as a bend of the formed straight line.
That is, when expressed as an error from a straight line when a single line is drawn in the axial direction of the transfer drum 1, in the case of the above numerical value, it is calculated that it is within 2 microns, and can be regarded as a substantially straight line. .. This relationship is shown in FIG. In FIG. 6, the linear scanning locus of one inkjet on the transfer drum 1 is p, and the locus of the ink point formed on the transfer drum 1 by p is q. The ideal ink point locus is a spiral shape r formed on the transfer drum with a constant twist angle. As described above, q and r do not match except at the scan end and the center.
The maximum value of this difference is within 2 microns.

Next, the change of the gap between the recording head 2 and the transfer drum 1 will be described with reference to the same drawing. The guide shafts (3 and 4 in FIG. 5) are arranged close to the transfer drum 1. For the diameter of the transfer drum 1 of 60 mm at the scanning end, the distance between the transfer drum 1 and the guide shafts 3 and 4 (PR, PV,
RS, RW) is 35 mm. When the scanning range of the recording head 2 is set to 210 mm, the change in the distance between the axis of the transfer drum 1 and the recording head 2 (the maximum value is 1 and the minimum value in FIG. 6) from a geometrical consideration using this condition. Is m, this difference l-
m represents the change in distance. ) Is about 50 microns.
This is a value that can be practically ignored for the ink droplet ejection characteristics of an inkjet.

The second embodiment is shown in FIG. A belt is used as a transfer medium, and the transfer medium does not have a curvature at a portion facing the recording head, which is different from the previous embodiment.

The recording head 2 scans on the transfer belt 50 which is a transfer medium. The recording head 2 is guided by guide shafts 3 and 4 having an inclination angle with respect to a direction orthogonal to the conveyance direction of the transfer belt 50 through a gap with the surface of the transfer belt 50. (The head scanning motor and the like are not shown.) The recording head 2 is in the conveyance direction of the transfer belt 50 (direction of arrow A).
The plurality of inkjets arranged on the transfer belt 50 are provided, and an ink image is formed on a predetermined belt-shaped region on the transfer belt 50 by the scanning operation. The first paper feed roller 6 and the second paper feed roller 7 convey the recording paper 8 which is a recording medium. The recording paper 8 is pressed by the pressure roller 9 and comes into contact with the recording paper.

Similar to the previous embodiment, one reciprocating operation time T of the scanning operation of the recording head 5, effective recording width F, transfer belt 50
The transport speed Vt of the above satisfies the relationship of F = T · Vt.

Next, the operation will be described. During the recording operation, the transfer belt 50 is rotated at a constant speed in the direction of arrow A, the recording head 5 is scanned at a constant speed in the direction of arrow B, and the recording paper is conveyed at a constant speed in the direction of arrow C while a predetermined ink jet is performed. Ink droplets are ejected from. After scanning the predetermined recording area, the recording paper 8 and the transfer belt 50 rotate in the forward direction at a constant speed and are conveyed, while the recording head 2 returns in the direction of arrow D. After that, the recording head 2 reciprocates on the transfer belt 50 while reciprocally moving. By one scanning operation, an ink image is formed on the surface of the transfer belt 50 in a belt-shaped region in a direction orthogonal to the transport direction of the transfer belt 50.
Further, the surface of the transfer belt is filled without gaps by repeated scanning. The ink image on the transfer belt 50 is transferred onto the recording paper 8.

[0017]

In the ink jet printer of the present invention, after the ink image for one page is formed on the transfer medium,
Instead of transferring to the recording medium, while continuously transferring the transfer medium, an ink image is formed in each belt-shaped region orthogonal to the transfer direction of the transfer medium. Therefore, it is possible to form the ink image on the transfer medium at a predetermined portion of the transfer medium and transfer it to the recording medium at another place, and perform these two steps simultaneously. Therefore, it is not necessary to release the contact between the recording medium and the transfer medium at the transfer portion to the recording medium. Therefore, there is an effect that a transfer type inkjet printer having a simple structure can be realized.

Furthermore, since the above two steps proceed simultaneously,
There is an effect that recording can be performed by continuous operation and high-speed operation can be realized.

An ink jet printer can be constructed with a small number of ink jets by using a scanning method generally used in serial printers, that is, by scanning the recording head in a direction perpendicular to the transfer medium conveyance direction. However, in this case, the transfer medium is stopped during one scanning, the transfer medium is fed by a predetermined length until the next scanning operation, and the subsequent scanning is performed. When this is applied to a transfer type inkjet printer, the transfer medium needs to be intermittently fed, and the contact time between the transfer medium and the recording medium at the transfer portion varies depending on the location. During the time when the transfer medium is stopped, the transfer medium and the specific portion of the recording medium are kept in contact with each other, and the transferred image is not stable. In the configuration of the present invention, as is clear from the above description,
Since the transfer medium moves by a distance corresponding to the effective recording width during the reciprocating operation time of the recording head, the transfer medium is not stopped and is conveyed at a constant speed even during the returning operation of the recording head. Therefore, the transfer medium is continuously conveyed and intermittent drive control is not required.
The mechanism and control can be simplified, and the transferred ink image of stable quality can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a mechanism of an inkjet printer according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the mechanism of the inkjet printer according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an inkjet printer of the present invention.

FIG. 4 is a diagram illustrating a recording state on recording paper of the inkjet printer of the present invention.

FIG. 5 is a diagram illustrating a guide shaft configuration of the inkjet printer according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a scanning locus of the inkjet printer according to the first embodiment of the present invention.

FIG. 7 is a perspective view of a mechanism of an inkjet printer according to a second embodiment of the present invention.

FIG. 8 is a perspective view of a mechanism of a transfer-type inkjet printer of a conventional example.

FIG. 9 is a sectional view of a mechanism of a transfer-type inkjet printer of a conventional example.

[Explanation of symbols]

 1: Transfer drum (transfer medium) 2: Recording head 3, 4: Guide shaft 8: Recording paper (recording medium) 9: Pressure roller 50: Transfer belt (transfer medium)

Claims (2)

[Claims] 1. A recording head having at least one inkjet that ejects ink droplets, a transfer medium that moves through a gap with respect to the inkjet, and a recording head for generating an ink image on the surface of the transfer medium. And forming an ink image on the transfer medium from the recording head,
In an inkjet printer having a pressure applying means for transferring an ink image from the transfer medium to the recording medium, the recording head scans the surface of the transfer medium with an inclination angle with respect to a direction orthogonal to the transport direction of the transfer medium. An inkjet printer having the above structure. 2. A transfer medium conveyance and a recording head operation are synchronized and continuously performed, and an ink image is formed on the transfer medium in a direction perpendicular to the transfer medium conveyance direction. The described inkjet printer.