JP2712265B2 - Ink transfer type multi-color recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink transfer type multicolor recording apparatus, and more particularly, to a recording apparatus using liquid ink used for a facsimile or the like. In particular, the present invention relates to a multicolor recording apparatus having a writing head disposed around an ink transport drum.

2. Description of the Related Art As a conventional recording apparatus of this type, for example, as shown in FIGS. 7 and 8, a rotating drum b having a large number of ink holes a, a,. An ink squeezing roller e, a blade f, and a large number of needle-shaped electrodes g are arranged around the rotary drum b along the rotation direction of the rotary drum b. ,
A plurality of (two shown in the drawing) image forming units provided with an electrode holder h (writing head) to which g is attached.
i, i, and a pair of rollers 1, 1, which are arranged to face the rotating drum b of the image forming units i, i and transfer either the charged ink or the uncharged ink in the ink holes a to the recording sheet j side.
and an image holding unit k having a transfer roller o that rolls on the back surface of the endless belt n.

In the conventional recording apparatus configured as described above, when the rotary drum b of the first color (right side in FIG. 7) rotates, ink enters and is held in the ink holes a, a. b, the excess ink adhering to the outer peripheral surface is squeezed down by the ink squeezing roller e, and the blade f
Are filled with the ink d in the ink holes a. On the other hand, a digital signal voltage corresponding to the pixel is applied to the electrodes g, g,.
When the ink holes a, a ... come directly below the g ..., only the ink d held in the ink holes a, a ... facing the electrodes g, g ... is polarized, and the electrostatic drum causes the rotating drum b to rotate. The ink is sucked upward, rises, and is transferred to a recording sheet p inserted between the rotary drum b, the endless belt n, and the transfer roller o. Similarly, in the second, third,... Colors in the next step, images formed on the rotary drum b are similarly sequentially transferred to the recording sheet o, and multicolor recording is performed.

[Problems to be Solved by the Invention] However, in general, in this type of ink transfer type recording apparatus, the ink holes a,
are arranged in the same manner, and there is a problem that, when a slight shift occurs in each step, color unevenness of a grid pattern called moire occurs.

As a means for explaining the above problem, it is conceivable to change the angle of the dot array on the write head h side, but it did not sufficiently eliminate the color unevenness but rather caused color shift.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent color unevenness due to transfer from an image forming unit to an image holding unit, and to obtain a high-density image. It is intended to provide an ink transfer type recording apparatus characterized by the following.

[Means for Solving the Problems] In order to achieve the above object, a recording apparatus of the present invention comprises:
A plurality of ink transport drums corresponding to each color of insulation with a large number of ink holding holes capable of holding liquid ink on the surface, and are disposed opposite each ink transport drum to selectively select ions according to image information A plurality of image forming units, each of which has a writing head for selectively charging the liquid ink by irradiating the charged ink or the non-charged ink in each ink holding hole. In an ink transfer type multicolor recording apparatus including an image holding unit having a transfer unit for transferring any one of the ink transfer drums to the recording sheet side, the arrangement angle of the ink holding holes on the ink transfer drum is set to at least two ink transfer drums. ,
The pitch between the ink holding holes of each transport drum is changed to be equal to or less than the pitch of the ion flux of the write head.

In the present invention, the arrangement angle of the ink holding holes may be any angle as long as the ink holding holes of each ink carrying drum do not coincide with each other in the case where the ink holding holes of each ink carrying drum are regularly arranged in a lattice pattern. The angle may be, for example, in the case of four colors, 0 °, 15 °, 30 °, 45 °, or 0 °, 0 °, 30 ° sequentially from the first color to the second, third, and fourth colors. , 60 °, etc., the angle can be changed for at least two ink transport drums. Further, by arranging the ink holding holes irregularly, moire can be prevented as in the case where the angle is positively provided. Further, when the pitch between the ink holding holes is regularly arranged, it is desirable that the pitch is equal to the ion flux pitch (recording density in the horizontal direction) or a fraction thereof. Further, when the pitch between the ink holding holes is irregularly arranged, the pitch between the ink holding holes needs to be a fraction of the ion flux pitch. The number of holes must be approximately equal.

The write head may be of any type as long as it irradiates ions held on the ink held in the ink holding holes of the ink transport drum.

Either conductive or insulating ink can be used as the liquid ink.If conductive ink is used, the ink tank where the lower end of the ink transport drum is immersed is grounded to remove residual charges. If the insulating ink is used, it is desirable to dispose a charger for static elimination on the next step side of the transfer unit of the image holding unit.

The ink transport drum may be entirely made of an insulating member, but preferably has a metal core material such as aluminum coated with an insulator. The sectional shape of the ink holding hole formed on the surface of the ink transport drum may be any as long as it has a recess capable of holding ink. For example, a bowl formed by etching or the like may be used. The size is preferably set, and the size can be appropriately set according to the properties of the recording sheet or ink or the required dot diameter.

The image holding unit may be any unit that transfers and holds the image formed on the image forming unit. For example, the image holding unit transfers and holds the image directly from the image forming unit to a recording sheet, It may have an intermediate medium function of transferring and holding the image on the recording sheet after holding the image from the set. Further, the transfer unit of the image holding unit may be any unit as long as it applies a pressing force toward the ink transport drum to transfer the recording sheet to a recording sheet inserted between the image transport unit and the ink transport drum. Although it may be present, it is preferable that a bias is applied.
The shape may be an endless belt shape or a drum shape having a relatively large diameter.

[Operation] When the ink transport drum of each color configured as described above rotates and passes through the ink tank, the ink in the ink tank is held in the ink holding hole of the ink transport drum, and the ink holding hole is written. When passing directly below the head, ions selectively irradiated from the writing head are selectively charged by the ink held in the ink holding holes to form a predetermined transfer pattern image, and the first color image is formed. The transfer pattern images formed on the ink transport drums of the second and subsequent colors in order from the ink transport drum are transferred onto the recording sheet by the transfer unit of the image holding unit.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

First Embodiment FIG. 1 is a schematic sectional view of a first embodiment of a multicolor recording apparatus according to the present invention. Ink holding hole
Insulating ink transport drum 10 forming 12, 12,..., And conductive liquid ink 14 disposed opposite to the periphery of ink transport drum 10 and held in each ink holding hole 12 by an ion flow according to image information. And a plurality of image forming units 30 (shown as two in the drawing), each of which has an ion flow writing head 20 for selectively charging And an image holding unit 31 having a transfer roll 32 as a transfer unit for transferring the liquid ink 14 held in each of the ink holding holes 12, 12,... To the recording sheet side. In this case, a heater 40 for heating the liquid ink held in the ink holding holes 12, 12,...
An ink temperature detecting thermosensor 52 for detecting the temperature of the ink 14 held at 2, 12,... Is provided, and the heater 40 receives a signal from the thermosensor 52 and receives a signal from the thermosensor 52.
Temperature control means 50 to control the heating capacity of
And a transfer electric field control means 60 for controlling a transfer electric field between the ink transport drum 10 and the transfer roll 32 in accordance with the temperature of the controlled ink.

The ink transport drum 10 of the image forming unit 30 is made of, for example, a core material made of an aluminum alloy coated with an insulator, and the surface of the ink transport drum 10 has a bowl-shaped cross section by etching or the like. Are formed (see FIG. 2). The ink transport drum 10 is rotatably disposed so that its lower end is immersed in the ink 14 contained in the ink tank 16. Around the ink transport drum 10 configured in this manner, a blade 18 and a ion stream writing device that scrape the surface of the drum 10 so as to hold the ink 14 only in the ink holding holes 12 sequentially in the rotation direction of the drum 10. A head 20 is provided, and a transfer roll of the image holding unit 31 is provided.
32 are arranged. In this case, the first color image forming unit
The pitch between the 30 ink holding holes 12, 12,... Is regularly arranged in a grid pattern as shown in FIG. The pitch of the ink holding holes 12, 12,...
(Recording density in the horizontal direction) (see FIG. 3 (a)),
Alternatively, it is desirable to set it to a fraction thereof. Also, the second
The ink holding holes 12, 12,... Of the color eyes are arranged in a grid at an angle of about 45 ° with respect to the ink holding holes 12, 12,.

The ink holding holes 12, 12 for each of the ink transport drums 10 may have any arrangement angle as long as they can be positively changed in a range that does not match each other. The arrangement angle of the holding holes 12, 12,... May be changed, for example, by 15 degrees, or may be changed by 30 degrees. Further, the pitch between the ink holding holes 12, 12,... Can be irregular (see FIG. 4). In this case, it is necessary to make the number of the ink holding holes 12 substantially equal in any of the vertical and horizontal pitches.

As shown in FIG. 2, the ion flow writing head 20 includes an ion generator 21 including a discharge wire 22 and a shield 24 surrounding the discharge wire 22, and the ion generator 21.
An air supply unit 23 for supplying compressed air to an air introduction passage 26 formed in the shield 24, and a discharge wire of the shield 24.
A plurality of control electrodes 27, 27,... Mounted with an insulating substrate 25 on an opposite wall of an ion discharge passage 28 formed at a portion facing the air introduction passage 26 with respect to 22, and formed on the other wall of the ion discharge passage 28. And a ground electrode 29. In this case, the discharge wire 22 is connected to the positive side of the corona potential source 1, the shield 24 is grounded, and the control electrodes 27, 27,. 3, and the ground electrode 29 is grounded via a shield 24. Therefore, ions generated by corona discharge generated between the discharge wire 22 and the shield 24 are guided to the ion discharge path 28 by the air flow from the air supply unit 23, and this ion flow is
Depending on the presence or absence of the electric field of 27, 27 ..., the ink selectively passes through the ion discharge path 28, and selectively irradiates the ink 14 in the predetermined ink holding holes 12, 12,. The transfer pattern image is formed by applying an electric charge to 14. In addition, the ion flow writing head 20 is not in contact with the ink transport drum 10, and specifically, has a capacity of 0.1.
They are arranged at intervals of about 3 to 1.0 mm.

The image holding unit 31 is provided with an endless belt 70 wound around a pair of drive rolls 36 and 38 so as to be in contact with the upper surface of each ink transport drum 10 and faces the ink transport drum 10 of the endless belt 70. The transfer roll 32 is in rolling contact with the back side to be inserted, and the recording sheet 34 is inserted between the endless belt 70 and each of the ink transport drums 10, 10, and the ink of the two ink transport drums 10, 10 is retained on the recording sheet 34. Charged ink 14 in holes 12, 12, ...
The color transfer is performed by transferring the transfer pattern image formed by the above. In this case, the recording sheet 34 inserted between the transfer roll 32 and the ink transport drum 10 by the bias applied to the transfer roll 32 from the transfer electric field control means 60 that has received the signal from the thermosensor 52 has an ink holding hole. The transfer pattern image is transferred by sucking the ink 14 in the transfer pattern 12.

In the multicolor recording apparatus of the present invention configured as described above, while rotating the ink transport drum 10 of each image forming unit 30 and applying a voltage to the ion current writing head 20,
As the ink transport drum 10 rotates, the ink tank 16 is inserted into the ink holding holes 12, 12 of the portion immersed in the ink tank 16.
After the ink 14 inside enters and is held, the ink 14 attached to the surface of the ink transport drum 10 is scraped off by the blade 18 and held only in the ink holding hole 12. Then, when passing immediately below the ion flow writing head 20, ions selectively irradiating from the ion flow writing head 20 generate ions corresponding to predetermined image information by the ink holding holes 12,1.
The ink 14 in 2 is charged. As described above, the ink 14 in the charged ink holding holes 12, 12,... Is applied to the transfer roll 32 on the recording sheet 34 that sequentially moves through the image forming units 30, 30,. The transfer electric field controlled by the applied bias attracts and transfers the image to the transfer roll 32 side, and the transfer pattern image is transferred and held on the recording sheet 34 together with the pressing force of the transfer roll 32. In this case, if the ink tank 16 is grounded, the remaining charged ink 14 after transfer can be neutralized in the ink tank 16, and the next writing operation and transfer operation can be reliably performed.

In the recording apparatus of the present invention configured as described above, when the transfer was performed with the temperature of the ink 14 set to about 50 ° C., the transfer time of the conventional recording apparatus could be improved by about 50%. The minute recording speed could be improved.

In the above embodiment, the case where the bias is applied to the ion flow writing head 20 to charge the ink 14 in the ink holding holes 12, 12,... Has been described. The present invention is not limited thereto, and a charger 80 for precharging the surface of the ink transport drum 10 may be provided on the pre-process side of the ion flow writing head 20.
May or may not be biased.

In the above embodiment, the case where the blade 18 is formed separately from the ink tank 16 is described.However, it is not always necessary to form the blade 18 separately, and the blade 18 may be formed integrally with the ink tank 16. Thus, it is possible to reduce the number of constituent members and to effectively use the space. Further, in the above embodiment, the case where the ink is a conductive ink has been described.However, the ink need not always be a conductive ink, and it is also possible to use an insulating ink. If a charging device (not shown) for removing electricity is provided in the next step of the transfer roll 32, the remaining writing ink is removed and the next writing operation and transfer operation can be reliably performed.

FIG. 6 shows a second embodiment of the present invention, in which an image holding section temporarily holds a pattern image from an image forming section, and a pattern image from the intermediate transfer medium section. And a transfer holding unit for transferring and holding the image. That is, the ink transport drums 10, 10 of each image forming unit 30, 30,.
The transfer roller 32a is brought into rolling contact with the back side of the endless belt 70 that contacts the... To form an intermediate transfer medium portion 31a, and the transfer roll 32 is positioned at a position facing one drive roll 36 of the intermediate transfer medium portion 31a. In this case, the recording sheet 34 is moved between the transfer roll 32 and the endless belt 70. Thus, by moving the recording sheet 34 between the transfer roll 32 and the endless belt 70, the recording sheet
34 movements can be performed accurately and quickly.

In the second embodiment, the other parts are the same as those in the first embodiment, and the same parts are denoted by the same reference numerals and description thereof will be omitted.

[Effects of the Invention] Since the recording apparatus of the present invention is configured as described above, the following effects can be obtained.

In the recording apparatus of the present invention, the arrangement angle of the ink holding holes in the ink carrying drums of at least two image forming units is set such that the pitch between the ink holding holes of the ink carrying drum is equal to or less than the ion flux pitch of the write head. Therefore, the transfer on the recording sheet passing between each ink transport drum and the image holding unit does not have color unevenness or moire, and the image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a first embodiment of a recording apparatus of the present invention, FIG. 2 is a sectional view of an ion flow writing head of the present invention, and FIGS. 3 (a) and 3 (b) are ink holdings of the present invention. FIG. 4 is a schematic plan view showing another form of the ink holding hole, and FIGS. 5 (a) and 5 (b).
FIG. 6 is a cross-sectional view for explaining a transfer state of ink, FIG. 6 is a schematic cross-sectional view of a second embodiment of the present invention, FIG. 7 is a schematic cross-sectional view of a conventional recording apparatus, and FIG. It is an expanded sectional view of a head. Description of symbols (10) Ink transport drum (12) Ink holding hole (14) Ink (20) Ion flow writing head (30) Image forming unit (31) Image holding unit ( 31a) Intermediate transfer medium part (32) Transfer roll (32a) Transfer roll (34) Recording sheet

Claims (1)

(57) [Claims] A plurality of ink transport drums corresponding to respective colors of insulation having a large number of ink holding holes capable of holding liquid ink on a surface thereof; A plurality of image forming units each comprising a write head for selectively irradiating the liquid ink by selectively irradiating ions, and a charged ink in each ink holding hole disposed opposite to the ink transport drum of the image forming unit. Alternatively, in an ink transfer type multicolor recording apparatus including an image holding unit having a transfer unit for transferring any of the uncharged ink to the recording sheet side, the arrangement angle of the ink holding holes on the ink transport drum is set to at least 2 The pitch between the ink holding holes of each of the two ink transport drums was changed to be equal to or less than the pitch of the ion flux of the write head. An ink transfer type multicolor recording apparatus characterized by the above-mentioned.