JPH07223312A - Ink-jet recording device for which hot-melt ink is used - Google Patents

Abstract

PURPOSE:To provide an ink-jet recording device which obtains sufficient fixing strength to a recording medium and dots of hot-melt ink which are allowed to fly to an intermediate transfer body from a recording head can be transferred effectively to a recorded body without depending on a piling height. CONSTITUTION:A yellow, magenta, cyanogen and black recording heads 2-5 are filled with hot-melt ink and molten by being heated up to a flying temperature. When image information is applied to the heads 2-5 each, the ink becomes thread-forming and flies to an intermediate transfer body 6. A pile height of dots 10 stuck to the intermediate transfer body 6 is equalized by a pressure- contacting roller 14 heated by a heater 15, transferred to a recording medium 7 and fixed by a rear roll 8. Residual ink, paper powder, foreign matter or dust on the surface of the intermediate transfer body 6 is removed by a cleaner 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus used in a printer, a facsimile, etc., and particularly, a hot melt ink in which hot melt ink melted by heating flies from a recording head to form an ink image on an intermediate transfer member. The present invention relates to an inkjet recording device using a melt ink.

[0002]

2. Description of the Related Art Since the ink used in a conventional ink jet recording apparatus uses a solvent which is liquid at room temperature, bleeding of dots after adhering to the recording paper causes deterioration of image quality, and further The suitability was poor when plain paper was used as the recording paper, such as when lining.

An ink jet recording apparatus using a hot melt ink is a device which heats and melts a hot melt ink which is solid at room temperature and causes it to fly onto a recording medium by an electrostatic attraction force or a pressure pulse. Since it solidifies rapidly after it adheres to the recording medium, the above-mentioned problems are solved, but since the solidification is too fast, the pile height (height of the dot sphere) of the ink dot becomes high and the fixing strength is low. Has become.

Further, even if a transparent film sheet such as an OHP sheet is used as a recording medium and color ink is printed on the recording medium, the raised ink dots diffuse light on the transparent film sheet, resulting in a clear color. There was also the problem that it did not develop color.

The present inventors have previously proposed an ink jet recording apparatus which can select a type of recording medium and can obtain sufficient fixing strength. One is to cause hot melt ink in a heated and melted state to fly from a recording head to an intermediate transfer body by using electrostatic attraction force, etc., and to maintain the ink adhering to the intermediate transfer body near the softening temperature, thereby recording medium. Inkjet recording apparatus adapted to perform pressure transfer to a sheet (Japanese Patent Laid-Open No. 5-200997)
The other is to cause hot melt ink in a heated and melted state to fly from a recording head to an intermediate transfer body by using electrostatic attraction force, and the ink adhered to the intermediate transfer body is used as a recording medium. And an ink jet recording method (Japanese Patent Application No. 4-314398). These are capable of forming a stable image irrespective of the type of recording paper by simultaneously holding and ejecting ink on the intermediate transfer member, and at the same time increasing the fixing strength.

FIG. 5 is a schematic configuration diagram of an example of an electrostatic attraction type ink jet recording apparatus using an intermediate transfer member.
In the figure, 1 is a recording head, 2 is a black head, 3 is a yellow head, 4 is a magenta head, 5 is a cyan head, 6 is an intermediate transfer member, 7 is a recording medium, 8 is a back roll, and 9 is The cleaner 10 is a dot flying to the intermediate transfer member, and 11 is a dot transferred onto the recording medium. In this example, as the recording head, the recording head 1 having four heads for color printing including a black head 2, a yellow head 3, a magenta head 4, and a cyan head 5 was used. However, the head of another color may be used, or only the head for a single color, for example, black may be used.

When each head is driven by the image information, the hot melt ink flies by Coulomb force,
The dots 10 are attached to the intermediate transfer body 6 which is arranged to face each other. The adhered dots 10 rapidly solidify after adhering to the intermediate transfer member 6. An image formed by dots on the intermediate transfer body 6 is transferred to the recording medium 7. The back roll 8 conveys the recording medium 7, presses the recording medium 7 against the intermediate transfer body 6 to perform transfer, and dots 11 are printed on the recording medium 7. The cleaner 9 is configured to remove residual ink, paper dust, foreign matter, dust, etc. on the intermediate transfer body 6.

FIG. 6 is an explanatory diagram of the printing operation. In the figure,
Reference numeral 1 is a recording head, 1a is hot melt ink, 1b is an ink heater, 1c is a control electrode, 6 is an intermediate transfer member, and 10 is a dot which has flown to the intermediate transfer member. The hot melt ink 1a is heated by the ink heater 1b and is in a molten state. When a drive voltage is applied between the control electrode 1c and the conductive intermediate transfer member according to the image information, the ink string is attached to the intermediate transfer member 6 to form the dots 10. The dots 10 attached on the intermediate transfer member 6 have a size corresponding to the gradation when gradation control is performed,
Pile height is not constant. Further, in the case of color printing, since dots of different colors are overlapped, the total pile height size varies.

When a dot with a low pile height is located beside a dot with a high pile height, a transfer failure may occur because the pressure is not sufficiently transmitted to the dot with a low pile height during pressure transfer from the intermediate transfer member to the recording medium. There is. Of course, by maintaining the ink near the softening temperature on the intermediate transfer body, the hardness of the dots will drop somewhat, and pressure will be applied easily to small dots, but when the colors are printed, dots of different colors will overlap and pile height will increase. It has been found that there is a problem that the pressure is not sufficiently transmitted to the small dots when the difference of is large.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is possible to obtain a sufficient fixing strength on a recording medium and to fly the hot melt ink from the recording head to the intermediate transfer member. It is an object of the present invention to provide an inkjet recording apparatus capable of efficiently transferring the dots of (3) to the recording medium regardless of the height of the pile height.

[0011]

The present invention is an ink jet recording apparatus provided with an intermediate transfer member for holding hot melt ink ejected from a recording head according to image information and transferring the hot melt ink to a recording medium. In the area from the portion where the hot melt ink flying from the recording head adheres on the intermediate transfer body to the transfer of the hot melt ink to the recording body, the hot melt ink on the intermediate transfer body It is characterized by having a leveling means for leveling the height of the dots formed in (3) below a predetermined value.

The leveling means is composed of a pressure contact means arranged facing the intermediate transfer body with a predetermined gap and / or a heating means for heating the surface of the intermediate transfer body to a temperature above room temperature and below the melting point of the ink. Also, the pressing means is a roller, has a heating means for heating the surface of the roller to a temperature above room temperature and below the melting point of the ink, and the critical surface tension of the surface of the intermediate transfer member. Is higher than the surface tension at the melting point of the hot melt ink.

[0013]

In the present invention, after the hot melt ink is ejected onto the intermediate transfer member, the unevenness of the pile height is generally adjusted on the intermediate transfer member by using the leveling means. During the transfer, no pressure is applied or the recording medium is not contacted to cause a transfer failure such that a small dot is not transferred. Therefore, it is possible to prevent image deterioration such as dot dropout.

[0014]

FIG. 1 is a schematic configuration diagram of an embodiment of an ink jet recording apparatus using the hot melt ink of the present invention. In the figure, parts similar to those in FIG. 6 are designated by the same reference numerals, and description thereof will be omitted. Reference numeral 13 is an intermediate transfer member heater, 14 is a pressure contact roller, and 15 is a pressure contact roller heater. The recording means is composed of a plurality of or a single recording head 1 which is filled with hot melt ink and has a heating member for heating and melting the hot melt ink. When performing color printing, a plurality of recording heads for ejecting different color inks such as yellow, magenta, cyan, and black are provided side by side, facing the intermediate transfer body 6, and different on the intermediate transfer body 6. Color inks may be overlapped. The hot melt ink is heated by a heating member to a flight temperature that is a temperature higher than the melting point and melted, and when pressure or electrostatic attraction is applied, it forms a towing thread and flies toward the intermediate transfer body. Intermediate transfer member 6 to which hot melt ink flying from the recording head 1 adheres
Does not particularly care about the material. Further, the intermediate transfer member 6 may have any shape such as a drum shape or a belt shape.

In this embodiment, an electrostatic suction type ink jet recording apparatus is used as a recording means so that a black head 2, a yellow head 3,
A magenta head 4 and a cyan head 5 were used. Each of the heads 2 to 5 of the recording head 1 is solid at room temperature,
It is filled with hot melt ink that melts when heated and decreases in volume resistivity, and has a heating member for heating and melting the filled hot melt ink. When the image information is applied to each of the heads 2 to 5 of the recording head 1, the ink becomes a string and flies toward the intermediate transfer body 5.

The intermediate transfer body 6 is formed of a stainless steel tube, and a pressure contact means is provided so as to keep a gap from the surface of the intermediate transfer body 6. The pressure contact means is arranged on the intermediate transfer body 6 from a portion where the dots 10 flying from the recording head are attached to the time when the hot melt ink is transferred to the recording medium, and changes the pile height. The intermediary transfer member 6 is arranged with a gap of about the pile height of the adjusted dots from the surface of the intermediate transfer member 6. The material of the pressing means is preferably one that repels the surface so that it does not stick to the ink. For that purpose, a liquid-repellent resin such as silicone or Teflon is preferable. The pressing means preferably has a roller shape so as to follow the feeding of the intermediate transfer body 6. In this embodiment, the pressing roller 14 is used. Also,
In order to efficiently change the pile height, it is preferable to heat the pressure contact roller 14 using the pressure contact roller heater 15. The heating temperature is from room temperature to the melting point of the ink, more preferably from the softening point of the ink to the melting point.

To adjust the pile height, the intermediate transfer body heater 13 can be used as an auxiliary means to heat the intermediate transfer body 6. Even if the entire intermediate transfer body 6 is heated,
Although a part of the intermediate transfer member 6 may be heated, the intermediate transfer member 6 may be heated.
It is important to heat at least a part of the area from the area where the hot melt ink flying from the recording head adheres to the area where the hot melt ink is transferred to the recording medium 7. Preferably, a means for efficiently heating only a part is preferable in order to avoid temperature rise of the device and power consumption due to excessive heat generation. As such means, for example,
By arranging a thermal head on the back surface of the intermediate transfer member and heating only a part of the intermediate transfer member, or by using a heat generating member that heats the intermediate transfer member 6 itself by energization, the energizing electrode is arranged on the back surface of the intermediate transfer member 6. There is a method of heating by applying electricity. Also,
The heating temperature is effective if it is higher than room temperature, but it is preferable that the heating temperature is equal to or higher than the softening point of the ink so that the ink is likely to change its shape. However, if the heating temperature greatly exceeds the melting point of the ink, the dots will run down, so
It is preferably below the melting point of the ink.

In this embodiment, the intermediate transfer body 6 and the pressure contact roller 14 respectively have an intermediate transfer body heater 13 and a pressure contact roller heater 15 built therein, and can be freely set within a range from room temperature to 150 ° C. by a temperature adjusting device (not shown). You can do it.

The hot-melt ink has various physical properties required depending on the flying method, but the common physical property is required to have the property of exhibiting a plastic flow that does not cause cracks on the recording medium by withstanding rubbing or bending due to external force. . Examples of such hot-melt inks include linear polyethylene to which various dyes, antioxidants, viscosity modifiers and the like have been added as colorants.

Further, the pile height may be leveled by using the heating means shown as the intermediate transfer body heater 13 without using the pressure contact means. In this case, by heating up to near the melting point of the hot melt ink using the critical surface tension of the surface of the intermediate transfer body 6, the ink becomes wet on the intermediate transfer body 6 and consequently the pile height can be lowered. it can. At this time, the material of the surface of the intermediate transfer member depends on the surface tension of the hot-melt ink used, but the hot-melt ink is approximately 10 to 50 dyn.
Since it is e / cm, if it is higher than this value, Cu, A
Various metals and alloys such as l and Ni, various heat resistant resins, and ceramics can be used. When the wetness is small, the surface may be further roughened by using a No. 500 to No. 2000 wrapping paper.

In the transfer section, the back roll 8 is used as a pressure contact member, and the ink on the intermediate transfer member 6 is transferred and fixed onto the recording medium 7. A cleaner 9 for removing residual ink, paper dust, foreign matter, and dust on the surface of the intermediate transfer body 6 is arranged between the transfer means and the recording means.

FIG. 2 is an explanatory view of the pressure contact roller. In the figure, 6 is an intermediate transfer member, 10 is a dot flying to the intermediate transfer member, 12 is a dot after pressure contact, 14 is a pressure contact roller, and 15 is a pressure contact roller heater. As described above, the pressure contact roller 14 is arranged at a predetermined distance from the surface of the intermediate transfer body 6. To the intermediate transfer member 6, as described in FIG.
Each dot 10 is attached according to the image information. Different-colored dots are overlapped at a portion where a plurality of colors are overlapped. Further, the dot diameter is also different by performing the gradation control. When the intermediate transfer body 6 moves in the direction of the arrow, the pressure contact roller 14 rotates along with the intermediate transfer body 6, but a dot having a diameter larger than the distance between the pressure contact roller 14 and the intermediate transfer body 6 or a dot that is overlapped and becomes higher. Becomes compressed dots 12, and the pile height becomes low. Therefore, it is possible to prevent dots that are not transferred in the subsequent transfer process.

A specific example of the above-described embodiment will be described. The recording head 1 is composed of four color heads 2 to 5 having a recording density of 300 spi, and each of the recording heads 2 to 5 is filled with four color inks of black, yellow, magenta, and cyan, respectively. The recording heads 2 to 5 have pulse wave voltage of 400 V and pulse width of 1.0 m according to an image signal from a host computer (not shown).
The pulse of s is applied, and the particles fly and adhere onto the intermediate transfer member 6 to which the bias voltage of −1000V is applied.

The hot-melt ink used in this example was prepared by adding straight-chain polyethylene as a main component and adding various color dyes, antioxidants, viscosity modifiers, etc. as colorants, and as a result of differential thermal analysis, The melting point of this ink is 102 ° C.
And the softening point was 70 ° C.

In the first specific example, the intermediate transfer member 6 after flying.
On the surface of the, dot diameter 60μm, pile height 40μm
Line and a line having a dot diameter of 15 μm and a pile height of 10 μm were alternately arranged, and the gap between the intermediate transfer member 6 and the pressure roller 14 was adjusted to 20 μm, and the image was fixed onto the recording paper. The intermediate transfer member heater 13 and the pressure contact roller heater 15 are turned off and remain at room temperature.

In this example, the transfer rate of dots having a dot diameter of 15 μm and the pile height of 10 μm transferred onto the recording paper was 93%, and a slight amount of ink remained on the intermediate transfer member 6, but the print quality was poor. Was fine.

A comparative example will be described. Using the same device as in the above specific example, the pressure roller 14 was separated by a distance that did not contact the dots on the intermediate transfer member 6, and the same pattern as in the first specific example was printed. Dots with a dot diameter of 15 μm and pile height of 10 μm Is 3 on the recording paper
It was about 0%, and thin lines were hardly seen on the recording paper.

In the second specific example, the intermediate transfer member heater 13 is used.
To turn on the temperature on the intermediate transfer member 6 to 100 ° C.,
The pressure roller heater 15 remains off, and the pressure roller 14
The gap was set to 20 μm, and the same pattern as in the first specific example was printed. Printed sample dot diameter 15μ
The dot having a height of m and a pile height of 10 μm was transferred onto the recording paper at a transfer rate of 95%.

Next, the temperature on the intermediate transfer member 6 was changed from 25 ° C. to 125 ° C., and the transfer rate at which dots having a dot diameter of 15 μm and a pile height of 10 μm were transferred onto the recording paper was measured. . The result is shown in FIG. From this, the temperature on the intermediate transfer member 6 is effective when the temperature is higher than room temperature and lower than the melting point of the ink, and particularly when the temperature is higher than the softening point of the ink and lower than the melting point of the ink, the temperature is higher than that of the first specific example. Proved to be even more effective.

In the third specific example, in the first specific example, the intermediate transfer body heater 13 is turned off, the pressure contact roller heater 15 is turned on, and the surface temperature of the pressure contact roller 14 is
The temperature was changed from 25 ° C to 125 ° C. As a result of measuring the transfer rate at which dots having a dot diameter of 15 μm and a pile height of 10 μm were transferred onto the recording paper, the printed sample was as shown in FIG.

From this, the surface temperature of the pressure roller 14 is
Effective above room temperature and below the melting point of the ink,
In particular, it was found that when the temperature was higher than the softening point of the ink and lower than the melting point of the ink, it was more effective than the first specific example.

In the fourth specific example, the surface of the intermediate transfer member 6 is slightly roughened with wrapping paper No. 2000 without using the pressure contact roller 14 used in the first specific example. When the dots recorded on the surface of the intermediate transfer member 6 are heated to the ink melting point by the heating of the intermediate transfer member heater, in particular, the dots having a high pile height are wetted on the surface of the intermediate transfer member 6, so that the pile height becomes low. It was The transfer rate of dots having a dot diameter of 15 μm and a pile height of 10 μm transferred to a recording paper by this system was 94%.

As described above, in the recording medium used in the present invention, the image formed on the intermediate transfer member is transferred and fixed by the leveling means and the transfer means of the present invention, so that the thickness, material, etc. There is no special limitation, and not only plain paper but also thick paper or film sheet can be used.

[0034]

As is apparent from the above description, according to the present invention, after the hot melt ink is ejected onto the intermediate transfer member,
Since the unevenness of the height is adjusted to the pile height by using the leveling means on the intermediate transfer body, when the transfer from the intermediate transfer body to the recording medium occurs, a transfer failure may occur in which small dots are not transferred. In addition, there is an effect that it is possible to prevent image deterioration such as missing dots.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an inkjet recording apparatus using a hot melt ink of the present invention.

FIG. 2 is an explanatory diagram of a pressure contact roller.

FIG. 3 is an explanatory diagram of a printing situation in a second specific example.

FIG. 4 is an explanatory diagram of a printing situation in a third specific example.

FIG. 5 is a schematic configuration diagram of an example of an inkjet recording apparatus of an electrostatic suction method using an intermediate transfer member.

FIG. 6 is an explanatory diagram of a printing operation.

[Explanation of symbols]

1 ... Recording head, 1a ... Hot melt ink, 1b ... Ink heater, 1c ... Control electrode, 2 ... Black head,
3 ... Yellow head, 4 ... Magenta head, 5 ... Cyan head, 6 ... Intermediate transfer body, 7 ... Recording medium, 8 ... Back roll, 9 ... Cleaner, 10 ... Dots flying to the intermediate transfer body, 11 ... Dots transferred on the recording medium, 12 ...
Dots after pressure contact, 13 ... Intermediate transfer body heater, 14 ... Pressure contact roller, 15 ... Pressure contact roller heater.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigenori Ando 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Tetsuro Kodera 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72 ) Inventor Koji Adachi 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Toru Okamoto 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Keizo Abe Hongo, Ebina City, Kanagawa Prefecture 2274 Fuji Xerox Co., Ltd. (72) Inventor Kazuo Maruyama 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (7)

[Claims] 1. An ink jet recording apparatus provided with an intermediate transfer body for holding hot melt ink ejected from a recording head according to image information and transferring the hot melt ink to a recording medium, wherein the intermediate transfer body is provided. The height of the dots formed by the hot melt ink on the intermediate transfer body in the area from the portion where the hot melt ink flying from the recording head adheres to the time when the hot melt ink is transferred to the recording medium. An ink jet recording apparatus using a hot melt ink, which has a leveling means for leveling the ink to be a predetermined value or less. 2. The ink jet recording apparatus using the hot melt ink according to claim 1, wherein the leveling unit is a pressure contact unit that is arranged facing the intermediate transfer member with a predetermined gap. . 3. The ink jet recording apparatus using the hot melt ink according to claim 1, wherein the leveling means is a heating means for heating the surface of the intermediate transfer member to a temperature above room temperature and below the melting point of the ink. . 4. The leveling means is composed of a pressure contact means arranged facing the intermediate transfer body with a predetermined gap and a heating means for heating the surface of the intermediate transfer body to a temperature above room temperature and below the melting point of the ink. An ink jet recording apparatus using the hot melt ink according to claim 1. 5. The ink jet recording apparatus using the hot melt ink according to claim 2, wherein the pressure contact means is a roller. 6. The ink jet recording apparatus using the hot melt ink according to claim 5, further comprising a heating unit that heats the surface of the roller to a temperature between room temperature and a melting point of the ink. 7. The ink jet recording apparatus using hot melt ink according to claim 3, wherein the critical surface tension of the surface of the intermediate transfer member is higher than the surface tension at the melting point of the hot melt ink. .