JPH05261979A - Perfecting ink-jet printer - Google Patents

Abstract

PURPOSE:To prevent a set-off, embody the formation of a high picture-quality picture, form ink pictures simultaneously on both surfaces of recording paper, miniaturize a device and carry out printing at high speed in a perfecting ink-jet printer. CONSTITUTION:Ink droplets are discharged from a first ink-jet type recording head 13-a, ink pictures are recorded on a first transfer medium 11-a, ink droplets are discharged from a second recording head 13-b, and ink pictures are recorded on a second transfer medium 11-b. The first and second transfer media 11-a, 11-b, on which the recording of the ink pictures is carried, are abutted, recording paper 21 is passed through the abutment sections, and the ink pictures are recorded on 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 ink images on recording paper, and more particularly to a double-sided printing ink jet printer for forming ink images on both front and back surfaces of recording paper.

[0002]

2. Description of the Related Art Ink jet printers discharge liquid ink onto recording paper to perform recording with ink drops. On the other hand, as a printer capable of double-sided printing, an electrophotographic apparatus has been put into practical use. In an electrophotographic double-sided printing printer, after printing on one side of the recording paper, the recording paper is reversed to perform printing on the back surface, which requires a recording paper reversing mechanism, which increases the size of the apparatus. It had a problem of long recording time. The ink jet system can be easily configured to perform recording on both front and back sides without reversing the recording paper, and the double-sided printing apparatus can be downsized and high-speed printing. Such a device
For example, an apparatus as disclosed in JP-A-58-56860 is known. However, in the ink jet printer, it is necessary to use the ink in a state where the ink has a sufficiently low viscosity to be ejected as an ink droplet. In this case, the ink, which is a low-viscosity liquid, permeates the recording paper when it adheres to the recording paper. Therefore, when recording on the surface, the ink that has permeated penetrates the ink image to the back side of the recording paper (hereinafter referred to as show-through). ) It was not suitable for double-sided printing.

Further, when double-sided printing is performed, it takes time to dry the ink soaked in. The longer the drying time of the impregnated ink, the more the impregnation progresses. In order to prevent the deterioration of the image quality due to the penetration, it is necessary to perform recording on the other side after the elapse of a certain time for the recording on one side to dry. This is because if recording is performed on both the front and back sides at the same place at the same time, a large amount of ink adheres to the recording paper at the same time, and the show-through and image quality deterioration due to the penetration are remarkable. Such a configuration is not suitable for high-speed recording because recording on both the front and back sides involves a time delay.

[0004]

SUMMARY OF THE INVENTION The present invention solves these problems, and an object of the present invention is to provide a new double-sided ink jet printer capable of performing double-sided printing with the smallest possible ink penetration in an ink jet printer. To provide a printer.

[0005]

SUMMARY OF THE INVENTION The double-sided printing ink jet printer of the present invention achieves the above object.
An ink jet type recording / writing unit that ejects ink as a droplet and a transfer medium that carries the ejected ink droplet and move. The recording medium is brought into contact with the transfer medium on the lower side of the recording / writing unit. There are two recording units for transferring the recorded image written on the recording medium onto the recording medium. The recording image is transferred by the first recording unit on the first surface of the recording paper, and the second surface is formed on the other surface of the recording paper. The recording unit is configured to transfer a recorded image.

[0006]

With this configuration, the ink image ejected onto the transfer medium by the ink jet recording / writing means is simultaneously transferred to both the front and back surfaces of the recording paper.

[0007]

EXAMPLES The examples shown below will be described.

1 and 4 show a first embodiment of the present invention. In both figures, the first recording head is
a, the state in which the second recording head is placed at 13-b shows the state during double-sided printing.

In FIG. 1, this double-sided printing ink jet printer is arranged around the rotating transfer drums 11-a and 11b, which are first and second transfer media, in order from the upper side in the direction of rotation indicated by arrows Aa and b. The first and second recording heads 13-a and 13b, which are ink jet recording / writing means,
Second removal rollers 12-a, b and first and second recovery tanks 1
4-a and b are arranged. First recording head 1
3-a forms an ink image on the first transfer medium 11-a,
The second recording head 13-b is configured to form an ink image on the second transfer medium 11-b. Hereinafter, units including these units will be referred to as first and second recording units.

A hatched area 23-a indicates a print area where recording is performed by the first recording head 13-a on the first transfer drum 11-a. (Second transfer drum 1
The print area 23-b on 1-b is not numbered because it only partially appears in FIG. Since the elements constituting the first and second recording units are the same, the configuration of each member will be described for the first unit (subscripts a and b are omitted). The transfer drum 11 is configured by providing a conductive elastic layer 17 around the 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. A guide groove 18 is formed around this area so as to avoid the print area 23. 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 that uses a piezoelectric element, and according to a recording signal,
Ink is selectively ejected from a plurality of nozzles as ink droplets.

The nozzles are arranged in the axial direction of the transfer drum 11, and the recording head 13 and the transfer drum 1 are in operation during the recording operation.
Fixed to 1.

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 recording paper 21, which is a recording medium, is conveyed in the direction of arrow C, reaches the contact portion of the first and second transfer drums 11-a, 11b, and is conveyed while being sandwiched between them and being pressed.

As shown in FIG. 2, the removing roller 12 is constructed by providing a conductive elastic layer 53 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 due to the voltage and moves to the transfer drum 11 side and adheres thereto.
When the ink dot 40 passes through the contact portion 70 with the removing roller 15, the ink liquid is squeezed by the squeezing action 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 carrier liquid component is removed below the contact portion 70, and concentrated ink dots 42 having a high toner component concentration are obtained.

In an experiment conducted by the present inventors, a transfer roller 11 having an outer diameter of 110 mm and a removing roller 12 having an outer diameter of 30 mm are used.
Using an ink in which a toner having a charge amount of 300 μC / g is dispersed, the bias power source 41 is set to 500 V,
80% of the carrier liquid was removed from the ink dots 40.
By transferring this to a recording paper, it was possible to obtain a concentrated state in which there was no show-through and a good transferred image was 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 contact portion 70, the gap increases corresponding to the groove depth. The carrier liquid is held in the smaller gap by capillary action. Therefore, the edge portion 51 around the groove is prevented from entering the guide groove 18.
Held along. 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. Due to the characteristics of the liquid described above due to the capillary action, the retained 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. When the edge tip 22 passes through the abutting portion 70, the carrier liquid is no longer retained and falls due to gravity, and the peeling blade 19 is removed from the groove at the left end portion.
Are peeled off and collected in the collection tank 14.

In this way, the first and second transfer drums 1 are
The recording images formed on 3-a and 3-b are transferred to the recording paper 21 sandwiched between them. That is, the recording image on the first transfer drum 13-a is on the upper surface (shown in FIG. 1) of the recording paper 21, and the recording image on the second transfer drum 13-b is on the recording paper 21.
Is transferred to the lower surface of the recording paper 21, and recorded images are simultaneously obtained on both surfaces of the recording paper 21.

Next, the operation during single-sided printing will be described with reference to FIG. 4. FIG. 4 shows a cross-sectional view of the apparatus of the first embodiment.

In FIG. 4, the second recording head 13-b is used.
The double-sided printing is performed as described above by placing it on the second transfer drum 11-b at the position for image recording, as shown in FIG. Thus, the recording operation is performed by switching to the position where the image is recorded on the first transfer drum 11-a. Second recording head 1
The position of 13-c is set so that the line recorded by 3-b is located between the lines recorded by the first recording head 13-a.

In ink jet recording, the recording speed is determined by the ink droplet ejection frequency from a specific nozzle. In the configuration of the present embodiment, the second recording head 13-b is used to fill the space between the areas recorded by the first recording head 13-a so that the peripheral speed of the transfer drum 1-a is doubled. The ejection frequency of each recording head is the same as that for double-sided printing, and the printing speed is 2 for single-sided printing (compared to double-sided printing).
Can be doubled. In the apparatus of this embodiment, the ink recording image formed on the transfer drum 11 is transferred onto the recording paper in a dried or concentrated state after removing the carrier liquid on the transfer drum 11. Therefore, ink does not soak into the recording paper, and the recorded image on one side does not show through. Therefore, in double-sided recording, it is not necessary to form a recorded image on one side and, after it is dried, perform recording on the back side. Therefore, it is possible to record on both the front and back sides at the same place at the same time. As a result, the time required for recording can be shortened and the device can be downsized.

Further, in the apparatus of the present embodiment, the second recording head for recording on the back side is used for recording on the front side during single-sided printing, so that recording is performed at double speed during double-sided printing during single-sided printing. You can

Next, a second embodiment will be described.

FIG. 5 shows a second embodiment of the present invention. FIG. 7 shows a cross sectional view.

The apparatus of this embodiment is different from the apparatus of the first embodiment in the structure and scanning method of the recording head 13. This device is a device for recording at a pitch of 1/300 inch.
The recording head has a plurality of nozzles aligned in the axial direction of the transfer drum 11 and arranged at a pitch of 8 × 1/300 inches. During recording, the first recording head 13-a and the second recording head 13-a are moved by the recording head swinging means 55 in synchronization with the rotation of the transfer drum.
The recording head 13-b integrally swings in the axial direction of the transfer drum 11. The second recording head located at the position 13-b during double-sided printing is configured to change its position to 13-c during single-sided printing.

The scanning operation during recording will be described with reference to FIG. This figure is a view seen from the direction of arrow F in FIG. For simplification of description, a case where the first and second recording heads 13-a and 13-b have three nozzles is illustrated. (A) shows double-sided printing, and (b) shows single-sided printing.

During double-sided printing, the first recording head 13-a is on the first transfer drum 11-a and the second recording head 13-a is on the first transfer drum 11-a.
-B records an image on the second transfer drum 11-b.

The double-sided printing operation is performed as follows.
First, the first transfer drum 11-a and the second transfer drum 11
-B is not in contact with the second transfer drum 11-
b is shown by a broken line), and a gap R is maintained between the two. The first and second recording heads 13-a and 13-b are integrally rocked by the rocking device 55 within a range indicated by P (a length corresponding to the nozzle arrangement pitch).

While rotating the first and second transfer drums 11-a and 11-b at a constant speed, the first and second recording heads 1
By moving 3-a and 13-b integrally in the direction of arrow Q, recording is performed in the band-shaped area using each nozzle. At this time, the first and second recording heads 13-a and 13-a
The speed is set so that the first and second transfer drums 11-a and 11-b rotate once when −b moves 1/300 inch in the Q direction. FIG. 6A shows a state in which the swing amount of the head has reached S. By the first nozzles 61 of the first recording head 13-a (the description of the second and subsequent nozzles is the same, so the description is omitted), the recording is performed on the area indicated by 61 ... on the first transfer drum 11-a. Is performed,
The first nozzle 63 of the second recording head 13-b
Indicates that recording is performed in the area indicated by 64 ... On the second transfer drum 11-b.

By swinging until S coincides with P, the required printing scan is completed and printing is performed over the entire printing area. In this way, the first and second transfer drums 11-
After image recording on a and -b, the recording paper 21 is fed, both drums are brought into contact with each other, and the image is transferred to the recording paper 21.

The operation of each member on the transfer drum is the same as that of the first embodiment, and the description is omitted. Next, the single-sided printing operation will be described.

First, the second recording head is switched to the single-sided printing position. The second recording head is switched to the position 13-c so that the second recording head 13-c causes the first transfer drum 1 to move.
It is arranged so as to perform image recording on 1-a. Second time at this time
The first nozzle 63 of the recording head 13-b of the first recording head 13-b is the first nozzle 61 and the second nozzle 65 of the first recording head 13-a.
It is also moved in the axial direction of the transfer drum by a predetermined amount so as to come to the middle of.

Next, the first transfer drum 11-a and the second transfer drum 11-b are placed in a non-contact state, and a gap R is maintained between them. First and second recording heads 13-a, 1
3-b swings integrally by the swinging device 55 within a range indicated by T (a length corresponding to 1/2 of the nozzle arrangement pitch).

While rotating the first transfer drum 11-a at a constant speed, the first and second recording heads 13-a, 13
By moving -b integrally in the direction of arrow Q, recording is performed in the band-shaped area using each nozzle. FIG. 6B shows a state in which the swing amount of the head has reached S. The first nozzle 6 of the first recording head 13-a
1 ... by the first transfer drum 11-a 61 ...
The recording is performed in the area indicated by, and the second recording head 13
-C shows the state in which recording is performed in the area indicated by 64 ... On the first transfer drum 11-a by the first nozzle 63.

By swinging S until it coincides with T, the required printing scan is completed and printing is performed over the entire printing area. After the image recording is performed on the first transfer drum 11-a in this manner, the recording paper 21 is fed and both drums are brought into contact with each other to transfer the image to the recording paper 21.

In this apparatus, the scanning amount of the recording head can be halved during single-sided printing, and high-speed printing can be performed during single-sided printing.

[0038]

As described above, according to the present invention, the ink recording image formed on the transfer drum is transferred onto the transfer drum.
Transfer to recording paper in a dried or concentrated state. Therefore,
The recording paper is not soaked with ink and the recorded image on one side does not penetrate to the back side. Further, in double-sided recording, it is not necessary to wait for the recording image on one side to dry before recording on the back side. Therefore, recording can be performed on the front and back sides at the same place at the same time. As a result, the time required for recording can be shortened and the device can be downsized.

Therefore, there is an effect that it is possible to realize a new double-sided printing ink jet printer which has a small amount of ink penetration and is capable of high-speed printing.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a double-sided printing inkjet printer according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an ink concentrating action of the double-sided 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 double-sided printing inkjet printer according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of the double-sided printing inkjet printer according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a double-sided printing inkjet printer according to a second embodiment of the present invention.

FIG. 6A is a diagram illustrating a scanning method during double-sided printing of the double-sided printing inkjet printer according to the second embodiment of the present invention. (B) It is a figure explaining the scanning system at the time of single-sided printing of the double-sided printing inkjet printer of the 2nd Example of this invention.

FIG. 7 is a cross-sectional view showing the configuration of a double-sided printing inkjet printer according to a second embodiment of the present invention.

[Explanation of symbols]

11-a, b: first and second transfer drums (transfer medium) 13-a, b: first and second recording heads (inkjet recording / writing means) 21: recording paper (recording medium)

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B41J 2/385 9110-2C B41J 3/16 L

Claims (3)

[Claims] 1. An ink jet recording / writing device for ejecting ink as liquid droplets, and a transfer medium which carries and moves the ejected ink droplets. The recording medium is brought into contact with the transfer medium on the lower side of the recording / writing device. There are two recording units for transferring the recording image written by the recording / writing means onto this recording medium, and the recording image is transferred by the first recording unit on the first surface of the recording paper. A double-sided printing ink jet printer characterized in that a second recording unit transfers a recorded image to the surface. 2. The ink comprises toner and carrier liquid, and each recording unit removes the carrier liquid from the ink recorded image on the transfer medium on the lower side of the recording / writing means and prior to transferring the recorded image to the recording paper. 2. The double-sided ink jet printer according to claim 1, further comprising: an ink concentrating or drying means for transferring the concentrated or dried recording image onto a recording medium. 3. The second recording / writing means is switchable so as to write a recording image on either the first transfer medium or the second transfer medium, and the first recording / writing means during double-sided printing. Then, a recording image is written on the first transfer medium by the second recording / writing means on the second transfer medium,
During single-sided printing, the second recording / writing unit switches the recording image on the first transfer medium to a recordable / writable state, and then uses the first and second recording / writing units to print on the first transfer medium. 2. The double-sided printing ink jet printer according to claim 1, wherein recording and writing are performed on the recording medium.