JPH05261903A - Transfer type ink jet printer - Google Patents

Abstract

PURPOSE:To concentrate ink discharged out of an ink jet recording head and transfer the same onto a recording paper. CONSTITUTION:Ink drops containing charged toners are discharged out of an ink jet recording head 13 and formed on a transfer medium 11, and the transfer medium 11 carrying ink dots is passed through a contact section in which a discharge roller 12 applying the given potential to the transfer medium 11 and the toner concentration performed by means of static electricity and discharge of carrier liquid by throttling are carried out to transfer the medium onto a recording paper 21.

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 for forming an ink image on a recording paper, and more particularly, after forming an ink image on a transfer medium, the transfer medium and the recording paper are opposed to each other to record. The present invention relates to a transfer-type inkjet printer that transfers an ink image onto paper.

[0002]

2. Description of the Related Art As a transfer type ink jet printer, a method disclosed in US Pat. No. 4,538,156 is known.

As shown in FIG. 7, this is a recording head 10.
The recording paper is pressed against the ink image formed on the surface of the cylindrical transfer medium 100 by the method 1, and is transferred by pressure.

[0004]

The transfer type ink jet printer of the prior art described above has a problem that the quality of the transferred image is poor.

This is because, firstly, when the ink image made of liquid ink comes into contact with the recording paper, the ink image soaks along the fibers and the peripheral portion of the ink image becomes a beard.

Secondly, since the transfer is performed by the contact between the transfer medium and the recording paper, the concave portion does not contact the recording paper and the transfer medium and the image to be transferred is not formed on the recording paper having low smoothness. It was in a so-called "blank" state where it was not transferred.

To solve this problem, the applicant of the present invention discloses in JP-A-62-92849 that ink droplets are once ejected onto a transfer medium, where most of the water in the ink droplets is dried and concentrated. We have proposed a device that transfers the above ink onto recording paper.

This solves the above problems of the transfer type ink jet printer and enables clear image formation. However, since it takes time to concentrate the ink, there is a problem that further needs to be solved in that it cannot fully meet the demand for high-speed printing.

The present invention solves these problems.
It is an object of the present invention to provide a new transfer type inkjet printer capable of efficiently concentrating an ink image on a transfer medium in a short time and transferring it onto a recording paper.

[0010]

SUMMARY OF THE INVENTION The present invention is a transfer type ink jet printer for achieving the above object, and an ink jet type writing means for ejecting ink composed of toner and carrier liquid as droplets, and the ejected ink. A transfer medium carrying droplets, a recording image transfer means for transferring a recording image written by contacting the recording medium on the transfer medium on the lower side of the recording and writing means, and a transfer means And a contact member that removes the dispersion medium from the droplets on the transfer medium in the process up to
A predetermined potential is applied between the contact member and the transfer medium to contact the transfer medium.

[0011]

With this configuration, the dispersion medium is removed from the ink droplets ejected onto the transfer medium by the ink jet recording / writing means, and the ink is transferred to the recording medium in a concentrated state.

[0012]

EXAMPLES The examples shown below will be described.

FIG. 1 shows a first embodiment of the present invention.

In this transfer type ink jet printer, a recording head 1 which is an ink jet type recording and writing means is arranged around a rotating transfer drum 11 in order from the upper side in the rotation direction.
3, a removing roller 12 as a contact member, a recovery tank 14, and a pressure roller 15 are arranged.

A hatched area 23 indicates a printing area where recording is performed by the recording head 13 on the transfer drum 11.

The transfer drum 11 is constructed by providing a conductive elastic layer 17 around a metal tube 16. Conductive elastic layer 1
7 can be obtained from a rubber material in which a conductive compound such as carbon black or metal powder is dispersed. The guide groove 18 is formed around this area so as to avoid the print area 53. The recovery blade 19 abuts on the guide groove 18, and the ink inside the guide groove is peeled off and recovered in the recovery tank 14.

The recording head 13 is an ink jet recording head of the type using a piezoelectric element, and according to a recording signal,
Ink is selectively ejected from a plurality of nozzles as ink droplets.

The transfer drum 11 is rotated in the direction of arrow A by a driving means (not shown). During the recording operation of the recording head 13, the transfer drum 11 is stopped, and the recording head 13 re-rotates to change the direction at the scanning end, so that the recording drum 13 rotates intermittently.

The ink is an emulsion ink in which positively charged toner, which is a colored particle, is dispersed in a carrier liquid, which is a dispersion medium. The dispersion medium is a high resistance low dielectric constant aliphatic hydrocarbon solvent (for example, Isopar G manufactured by Exxon Chemical Co.), and the toner is composed of Raven 1255 manufactured by Columbian Carbon Co. as a pigment and ethyl cellulose as a resin. The ink is formed by dispersing the toner in a dispersion medium together with a charge control agent organic amine. The toner is positively charged.

The ink is diluted with the solid content concentration defined by the following definition to 25 wt% so that it can be ejected from the recording head 13.

Solid content concentration = (toner) / (toner + carrier liquid) The recording head 13 is of a type that scans in the direction of arrow B along the carriage shaft 20 as shown in the drawing.

The recording paper 21, which is a recording medium, is conveyed in the direction of arrow C, comes into contact with the transfer drum 11, and is pressed by the pressure roller 15 from behind.

The removing roller 12 is constructed by providing a conductive elastic layer 23 around the metal tube 22. Further, an insulating layer may be provided on the outermost layer.

The ink concentration operation of the removing roller 12 will be described with reference to FIG. The ink droplets ejected by the recording head 13 form ink dots 40 on the transfer drum 11. The transfer drum 11 is biased to the removal roller 12 at a negative potential by the bias power source 41. Since the toner in the ink is positively charged, it receives an electrostatic force by the above voltage and moves to the transfer roller 11 side and adheres thereto.
When the ink dots pass through the contact portion 70 with the removal roller 12, the ink liquid is squeezed to squeeze the carrier liquid and remains on the contact portion 70. Since the toner has an electrostatic adhesion force, it passes through the contact portion 70. As a result, the contact portion 7
If the carrier liquid is removed, the ink dots 42 in a concentrated state having a large toner content can be obtained.

In the experiments conducted by the present inventors, the transfer roller 11 having an outer diameter of 110 mm and the removing roller 12 having an outer diameter of 30 mm are used.
And using a 25% solids concentration ink in which a toner having a charge amount of 300 μC / g is dispersed,
Removal roller 12 with bias power supply 41 set to 500V
After passing through the contact portion 70 for contacting, the solid content was concentrated to 70% on the transfer drum 11. This was pressure-transferred onto the recording paper 21 and a concentrated state where a good transferred image was obtained could be obtained.

Next, the recovery of the carrier liquid remaining on the contact portion 70 will be described. A guide groove 18 is provided on the outer periphery of the transfer drum 11. The carrier liquid remaining above the contact portion 70 flows into the minute gap and is held by the capillary force. That is, it is held as shown by the retention section 50 in FIG. At this time, when the guide groove 18 reaches the abutting portion 70, the gap increases in accordance with the groove depth, so that the carrier liquid flows into the guide groove 18.
It is held along the edge portion 51 around the groove without getting inside. Since the guide groove is formed in a spiral shape on the outer periphery of the transfer drum as shown in FIG. 1, the portion where the removing roller 12 and the edge of the guide groove 18 come into contact with each other moves as shown by an arrow D with rotation. The carrier liquid moves in the axial direction of the transfer drum 11 and finally reaches the edge tip 22 at the left end in FIG. 1 due to the characteristics of the liquid described above due to the capillary action. When the edge tip 22 passes through the abutting portion 70, the carrier liquid is no longer held, so it falls due to gravity and is peeled from the groove at the left end portion by the peeling blade 19 and collected in the collecting tank 14. FIG. 4 shows a second embodiment of the present invention.

It differs from the first embodiment in that the recording head 13 has a plurality of nozzles aligned with each other in the axial direction of the transfer drum 11. Since the transfer drum 11 does not need to be driven intermittently and is rotated at a constant speed, it takes time for the ink droplet dots ejected by the recording head and formed on the transfer drum 11 to reach the removal roller 12 and the pressure roller 15. Since it is constant regardless of the location, the conditions can be made more uniform than in the case of the configuration of the first embodiment, and the image forming process becomes stable. In order to form a color image, a plurality of recording heads that eject different color inks may be arranged.

FIG. 5 shows a third embodiment of the present invention.

The point different from the first embodiment is that the ink adhering to the removing roller 12 is separated by the roller blade 55 and collected in the container 56. The other configurations and operations are the same, and the description thereof will be omitted.

FIG. 6 shows a fourth embodiment of the present invention.

The transfer drum 11 is constructed by providing a conductive elastic layer 17 around a metal tube 16. Around this
A recovery slit 61 (only a part of which is numbered and other parts are the same and therefore omitted) is formed so as to avoid a printing area (not shown). A recovery hole 66 is provided at the bottom of the recovery slit 61. Although the width E of the recovery slit 61 is shown largely in the relationship shown in the figure, it is actually set to a value that is sufficiently small for the liquid to enter by the capillary action.

The members other than the above are the same as those in the first embodiment, and the description thereof will be omitted.

Next, the operation of recovering the residual carrier liquid in the apparatus of the fourth embodiment will be described. The carrier liquid remains in the upper part of the contact portion 70 between the transfer drum 11 and the removing roller 12. When the recovery slit 61 reaches the contact portion 70, the carrier liquid enters the recovery slit 61 and is guided into the transfer drum 11 through the recovery hole 66.

The first operation is to concentrate the ink on the transfer drum 11.
The description is omitted because it is the same as the embodiment.

In this embodiment, a drum-shaped transfer medium is used, but it may be constituted by an endless belt.

[0036]

As described above, according to the present invention, the ink droplets ejected onto the transfer medium by the ink jet recording / writing means selectively apply the carrier liquid only to the roller to which a voltage is applied to contact the ink droplets. To remove. Therefore,
The effect is that a clear recorded image can be formed on the recording medium without ink bleeding.

Since the above concentration action is performed electrostatically,
There is also an effect that the ink can be concentrated in a short time and the demand for high-speed printing can be met.

Further, since the concentration action does not accompany the evaporation of the carrier liquid, there is an effect that a highly safe device can be provided in which the flammable gas contained in the vapor of the carrier liquid is not scattered and the odor is not generated. Have.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a transfer type inkjet printer according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an ink concentration operation of the transfer type inkjet printer according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a residual carrier liquid recovery operation of the transfer type inkjet printer according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a transfer type inkjet printer according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a transfer type inkjet printer according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a transfer type inkjet printer according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional transfer type inkjet printer.

[Explanation of symbols]

11: Transfer drum (transfer medium) 12: Removal roller 13: Recording head (inkjet recording / writing means) 15: Pressure roller (recorded image transfer means) 21: Recording paper (recording medium) 41: Bias power supply 70: Contact portion

Claims (1)

[Claims] 1. An ink jet recording / writing device that ejects ink composed of toner and carrier liquid as liquid droplets, a transfer medium that carries the ejected ink droplets and moves, and a transfer medium on the lower side of the recording / writing device. Is arranged between the recording / writing means and the transfer means, and the recording image transfer means for transferring the recorded image written by bringing the recording medium into contact with the transfer medium, and applying a predetermined potential to the transfer medium. A transfer-type ink jet printer comprising a contact member that contacts the transfer medium, and removes the dispersion medium from the ink droplets on the transfer medium in the process of reaching the transfer unit.