JPH0392351A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent decrease of printing density and occurrence of discharge inferiority or the like due to clogging caused by deposition of paper powder or the like to an ink discharge port of an ink jet recording head by a method wherein a water repellent treating means which performs treatment of applying a water repellent agent inferior in wettability of ink, is established. CONSTITUTION:A recording medium 6 is pinched between rollers 25, 26 to be carried. At that time, the carrying rollers 26 to which an oily agent is supplied with an oil sponge 27 applies an oily agent onto a surface of the recording medium 6 according to rotation and the oily agent is infiltrated into the recording medium 6 such as plain paper or the like. The recording medium 6 coated by the oily agent becomes equivalent to treating paper having a water repellent layer on its surface, and is carried to a recording position with a head 1. A liquid drop discharged from the head 1 according to image recording information becomes difficult to be infiltrated into it by a water repellent effect of the surface of the recording medium 6, and is carried as it is not fixed to a fixing device 4. Water content in ink is compulsorily evaporated with a hot plate, warm wind, etc., herein, and an excellent recording density dot wherein a dye in the ink remains near the surface of the recording medium 6 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an inkjet recording device.

[Conventional technology] Inkjet recording devices, which perform recording by ejecting ink onto a recording medium, are non-impact recording devices that generate less noise, and can easily record color images by using multicolored inks. It has unique characteristics and has become rapidly popular in recent years. [Problem to be solved by the invention]

Although such an inkjet recording apparatus has the advantage of being able to select a variety of recording media, the following problems may occur depending on the type of recording medium used.

In other words, when the recording medium is so-called plain paper, the ink permeates and spreads along the fibers of the plain paper, causing the dots to not form a uniform circular shape, but to create a shape where whiskers protrude around the periphery (hereinafter referred to as feathering). ) dots were sometimes formed.

In addition, the diffusion and permeation into paper is fast, and even the dye in the ink can penetrate into the paper before the ink solvent dries, causing the problem of lowering the recording density on the paper. Ta.

Furthermore, paper fluff and paper dust on the surface of plain paper may adhere to the ink ejection ports of the inkjet recording head, causing problems such as clogging and ejection failure.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet recording apparatus that does not suffer from the above-mentioned problems even when plain paper is used as a recording medium.

(Means for Solving the Ff! Problem) To this end, the present invention provides an inkjet recording apparatus equipped with a recording head that performs recording on a recording medium by discharging ink from an ejection port. A moving means for relatively moving a medium, and a wood repellent agent having poor wettability of the ink applied to the recording surface of the recording medium before the recording medium reaches a recording position by the recording head due to the movement. It is characterized by comprising a water repellent treatment means for carrying out a treatment for supporting the water.

(Function) According to the present invention, water-repellent treatment is applied to the recording surface of the recording medium in the paper feeding process, etc. before ink is ejected and recorded. Even when a material that can penetrate and diffuse is used, feathering of ejected ink droplets can be eliminated and uniform, minute dot diameters can be formed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

(Example 1) FIG. 1 shows an example of an inkjet recording apparatus to which the present invention can be applied. In the figure, 1 is a print head whose surface on which ejection ports for ejecting ink droplets are formed faces the print medium 6, and 2 is a carriage on which the print head 1 is mounted. Ki V
The ridge 2 is movably supported by the guide Ith3,
A timing belt 4 is attached to the carriage 2, and is moved along a guide shaft 3 by a transfer motor 5, and during this movement, a recording head 1 performs recording.

There are various kinds of recording heads 1, such as those that eject ink by driving a piezoelectric element, and those that generate bubbles in a liquid path using the thermal energy of an electrothermal transducer and eject ink using the foaming energy. It is possible to use a head of various types.

Reference numeral 11 denotes a cylindrical platen roller made of urethane rubber or the like, which faces the head 1 in close proximity. 6
is a recording medium, which is conveyed in the direction of the arrow in accordance with the rotation of the platen roller 1l as the feed motor 7 is driven. II
A is a presser roller which cooperates with the platen roller 11 to clamp the recording medium 6.

The presser roller IIA may have a spur-shaped roller to reduce the contact area with the recorded surface of the recorded recording medium 6 and prevent recording stains. Also, 2
Reference numeral 8 denotes a paper press plate for regulating the behavior of the recording medium 6 and bringing it into close contact with the platen roller 24.

FIG. 2 is a schematic cross-sectional view of the inkjet recording apparatus according to this embodiment. Here, 25 and 26 are the recording medium 6
These are conveyance rollers for supporting and conveying the recording medium 6 toward the recording position, and among these, the surface portion of the roller 26 that contacts the recording surface of the recording medium 6 is formed of a porous material. Reference numeral 27 denotes an oil sponge that comes into contact with the conveyance roller 26, and is impregnated with oil (oil agent) containing an oil-based component with a high water-repellent effect.
It is desirable to select an oil component whose physical properties match those of the ink used in the inkjet recording apparatus. In FIG. 2, reference numeral 24 denotes a fixing device such as a heater, which is disposed on the downstream side of the recording position in the direction in which the recording medium travels, and is used to accelerate the drying and fixing of ink after recording.

In such a precept, an unillustrated! A recording medium 6 such as plain paper fed by a paper feeding member such as a paper roller 8 is fed by a paper feeding member such as a paper roller 2
5, 26. At this time, the conveyance roller 26 supplied with the oily agent by the oil sponge 27 applies the oily agent to the surface of the recording medium 6 as it rotates, and causes the oily agent to penetrate into the inside of the recording medium 6 such as plain paper. The recording medium 6 coated with the oil-based agent becomes equivalent to treated paper having a water-repellent layer on its surface, and is conveyed to the recording position by the head 1. Then, the droplets ejected from the head 1 according to the image recording information are difficult to penetrate into the recording medium 6 due to the water-repellent effect on the surface thereof, and are conveyed to the fixing device 4 without being fixed.

Therefore, the moisture in the ink is forcibly evaporated by a hot plate, hot air, etc., and dots with good recording density are formed in which the dye in the ink remains near the surface of the recording medium 6. Third
The figure shows dot formation in a conventional example and an example.

In the figure (^) shows the state of the recording medium 6 and ink droplets in conventional inkjet recording on plain paper. The ink for inkjet recording is pure water. In addition to dyes, glycols and glycol ethers are used to prevent head clogging.
Many contain nitrogen-containing solvents such as pyrrolidones. Immediately after the ink droplets have been ejected and attached, the contact angle between the ink droplets and a recording medium such as plain paper is generally very small and has good wettability. If the ingredients in the ink are only dye and pure water, the pure water evaporates quickly and is fixed in a short time, forming dots with high recording density in which the dye remains near the surface of the recording medium. As mentioned above, if a non-luminous solvent is blended to prevent clogging, the evaporation rate will be slow. Then, the ink penetrates into the inside of the paper, and when using plain paper with low absorption capacity, the ink spreads along the 1A fibers of the paper, resulting in uniform circular dots without being formed, as shown in Figure (B).
This results in feathering as shown in the image.

On the other hand, in this embodiment, as shown in FIG. 6(C), an oil-based agent is applied to the surface of the recording medium (plain paper) 6 to form a water-repellent layer 6A, thereby preventing ink droplets from forming. The contact angle with the recording surface becomes large, and the wettability becomes inferior compared to that shown in FIG. 2(A). Therefore, if the volume of the ink droplet is the same as in the case of the same figure (^), the dot diameter will become considerably smaller due to the surface tension of the ink droplet. Furthermore, the water-repellent oil-based agent makes it difficult for ink droplets to penetrate and diffuse inside.
The dot shape becomes a fairly uniform circular shape. The ingredients in the oil composition make it difficult for ink droplets to stick to the recording medium.
As shown in FIG. 2, it is desirable to evaporate the solvent by forced fixing. Since the dye in the ink remains near the surface of the dot after fixing, it is possible to maintain the same density as when using conventional so-called coated paper.

According to this example, as the dot diameter becomes smaller, it is preferable to increase the resolution of the output device, but this is in line with the trend toward higher resolution in recording devices in recent years. This ensures high recording density in the high-density areas and character areas of the recorded material, and since the dot diameter is small and circular, it is easy to create gradation of condensed halftones, and it is also possible to improve the gradation in highlighted areas. The graininess of dots is reduced, making it possible to output high-quality graphic images.

Furthermore, by using the current conveyance roller as the coating means, the configuration is simplified, and it is possible to prevent the device from becoming larger and more expensive.

(Example 2) The present invention is applicable to, for example, yellow (Y) in FIG. An inkjet recording device that performs recording by overlapping dots, such as an inkjet recording device that performs full-color recording by arranging recording heads 1 corresponding to each color of magenta (M), cyan (C), and black (Bk), It is also extremely effective against

FIG. 4 shows the state of ink extraction in such a full-color inkjet recording apparatus when untreated plain paper is used as the recording medium and when paper treated as described above is used.

Figure 4 (8) shows Y, M, C. Inkjet recording was performed on conventional plain paper with two colors of Bk being balanced (in this case, Y and M were used as an example). Due to the dot landing accuracy of the device, it is difficult for two dots to completely overlap, and the situation as shown in FIG. 4(A) inevitably occurs. Similarly to the example shown in Fig. 3, the penetration and diffusion of the solvent in the Sotsu paper caused the
As shown in B), the two superimposed colors form a dot shape with mutual feathering. Therefore, the extent to which color refraction occurs, that is, the subtractive color mixture of Y, M, and C is not performed well, and the mixed color (in this case, red) is not reproduced.

On the other hand, FIG. 4C shows the state of the recording medium and ink droplets in this example. As in the example shown in FIG. 3, the contact angle between the ink droplet and the recording medium is large, and the rate of penetration and diffusion into the paper is slow, so the two ink droplets shown in FIG. 4(C) The moment the liquids come into contact with each other, they coalesce as shown in Figure 4 (CD), and the two colors are mixed.

The dot shape after forcibly fixing is as shown in FIG. 4(E), and a circular dot shape with uniformly mixed colors is formed. Furthermore, in the case of a printer that requires high accuracy, since the ink droplet volume after the d color is different from the ink droplet volume of a single color, the dot diameter after recording is also different.

Therefore, for example, if the dot diameter can be arbitrarily modulated (for example, by using a piezoelectric element or an electrothermal transducer to change the driving amount), the ink droplet volume can be increased for monochrome recording, and the ink droplet volume can be increased for monochrome recording. In this case, variations in dot diameter can be suppressed by reducing the ink droplet volume. Furthermore, in the case of a system in which the dot diameter cannot be modulated, it is effective to bring the dot diameters closer together in monochrome recording and mixed color recording by scanning the head multiple times.

(Embodiment 3) FIG. 5 shows still another embodiment of the present invention, in which the basic device configuration and recording process are the same as those of the embodiment shown in FIGS. 1 and 2. Components constructed in the same manner as in FIGS. 1 and 2 are designated by the same numbers. In the embodiment shown in FIGS. 1 and 2, the conveyance roller 25 and the conveyance roller 26 are always in pressure contact, but in the embodiment shown in FIG. Pressure welding (state (a) in the figure) and release (state (a) in the figure)
It is possible to take two states (state (b) in the figure).

To do this, move the transport roller 26 to the position ffi (a)
A suitable support member may be provided for movable support between position (b) and position (b), and this member may be adapted to accept manual or automatic operation. Moreover, it may operate integrally with the presser roller IIA. According to this, the roller 26 is in pressure contact only when the recording medium 6 passes or only in the effective recording area, and when the recording medium 6 does not pass, the roller 26
By keeping the roller in the open state, it is possible to prevent excess oil from being applied to the conveying roller 25. ．． In other words, in the case of constant pressure contact, the roller 25
, 28 may come into contact with each other, causing the oily agent to adhere to the conveying roller 25. However, in this case, excess oily agent also adheres to the back surface of the recording medium, but in this example, such waste is avoided and the oily agent is It becomes possible to apply only to the recording surface.

Further, the conveying roller 26 is always kept in a pressure contact state, and the oil sponge 27 is pressed against the conveying roller 26 ((C) in the figure).
) and the open state (state (d) in the figure) may be switchable. Furthermore, in this case, there are recording media such as plain paper, which would suffer from the above-mentioned problems if the recording surface is not treated to be water-repellent, and recording media, such as plastic sheets for Of{P, that are used as is. However, with a recording medium that does not suffer from the above-mentioned problems, it becomes possible to switch between application and non-application of the oil-based agent.

(Embodiment 4) FIG. 6 shows a fourth embodiment of the present invention, which differs in configuration from the above embodiments. That is, the process of applying the oil-based agent is characterized in that the oil-based agent is applied not by a roller but by a head. In FIG. 6(A), reference numeral 51 indicates a normal inkjet recording head, and reference numeral 52 indicates a coating head section that performs treatment to make ink water repellent. The coating head section 52 is mounted on the same carriage so as to be located on the upstream side in the direction of travel.As shown in FIG. 6(B), the coating head section 52 has a structure similar to that of the head section of a conventional thermal transfer printer. The part corresponding to the ink ribbon is a coating ribbon that carries a wax that melts the oily agent when heated.

In FIGS. 6(8) and 6(B), 54 is a thermal transfer head having a heating element that applies thermal energy to the coating ribbon 53, and 60 is a recording head 5l according to recording data.
a drive data generating section 6 that generates data for driving the ejection energy generating element of and the heating element of the thermal transfer head 54;
Reference numeral 1 denotes a delay unit for applying drive data to the recording head 5l with a predetermined time delay. Here, if the thermal transfer head 54 and the recording head 5l have the same density and the same number of recording elements, and if these recording elements are aligned in the recording medium traveling direction, then the delay section 6
1 is sufficient as long as it simply delays classification data such as the separation distance between the heads and provides it to the recording head 5l.

In the above configuration, the drive signal corresponding to the recorded information is
First, by printing the heating element of the thermal transfer head 54 of the coating head section 52, the oil-based agent molten carbon is exuded from the coating ribbon 53, and dots of the oil-based agent are deposited on the recording paper. Here, only when the record information is given,
The thermal transfer head 54 is pressed against the platen, and the coating ribbon 5
3 is wound on one side, which is similar to a conventional thermal transfer printer. The inkjet recording head 51 then discharges ink onto the dots on the recording medium that have been coated with the oil-based agent by the coating head section 52.
A record is made. The ink adhered to the oil-based agent has a smaller dot diameter and becomes circular, which is the same effect as in the embodiment described above. However, in this embodiment, since the oil-based agent is applied only to the areas corresponding to the dots of inkjet recording, the ease of writing on the margins of the recording medium is improved. Moreover, the effect that the oil-based agent can be used without wasting it can also be obtained.

(Others) Although the embodiments described above show application using a roller and a thermal transfer head, various methods of application can be adopted, such as a method of spraying an oil-based agent or a method of vaporizing an oil-based agent to adhere it. Of course.

It should be noted that the present invention provides excellent effects particularly in bubble jet recording heads and recording apparatuses among ink jet recording systems.

This is because such a system achieves higher recording density and higher definition.

For its typical configuration and principle, see, for example, US Pat. No. 4,723,129. It is preferable to use the basic principle disclosed in the specification of the same No. 4740796. This method is the so-called on-demand type. It can be applied to any continuous type, but in particular, in the case of an on-demand type, an electrothermal converter is placed corresponding to a sheet holding liquid (ink) or a 7-night passage. The electrothermal transducer generates thermal energy by applying at least one drive signal that corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling, thereby causing film boiling on the thermally active surface of the recording head. This is effective because it can generate a bubble in the liquid (ink) that corresponds one-to-one to this drive signal. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. It is more preferable to make this driving wJ signal into a pulse shape, since bubble growth and contraction can be performed immediately and appropriately, and liquid (ink) ejection with particularly excellent responsiveness can be achieved. This pulse-shaped drive signal is:
US Pat. No. 4,463,359. Same No. 434525
Those described in Specification No. 2 are suitable.

Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid channels, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the wafer is placed in a bending region. In addition, Japanese Patent Application Laid-Open No. 1989-5 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Application Laid-Open No. 59/1989 which discloses a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
- The effects of the present invention are also effective even with a configuration based on Publication No. 1381161. That is, regardless of the form of the printhead, the printing condition can be reliably improved.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus.

Such a recording nozzle may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even serial type recording heads like the one above can be installed in the main body of the device, making it possible to electrically connect to the main body of the device and supply ink from the main body of the device.Replaceable chip-type recording heads Alternatively, the present invention is also effective when using a force τ cartridge type recording head which is provided integrally with the recording head itself.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, the inkjet recording apparatus of the present invention can be used as an image output terminal for information embedded devices such as computers, as well as as a copying machine combined with a reader or the like, or as a facsimile machine having a transmitting/receiving function. It may be one pot.

(Effects of the Invention) As explained above, according to the present invention, ink is ejected,
We applied water-repellent treatment to the surface of the recording medium in the paper feeding process before recording, so even if a material that allows ink to permeate and diffuse, such as plain paper, is used as the recording medium, Even if there is, it is possible to eliminate feathering of the ejected ink droplets and form uniform, minute dots and diameters. This makes it possible to achieve high resolution and to produce high-density images with dye remaining on the recording medium.

Furthermore, paper fluff. It is possible to prevent the generation of paper dust and reduce the possibility of occurrence of ejection failure.

Furthermore, if the current conveyance roller is also used as the coating means, the configuration can be simplified and the device can be prevented from increasing in size and price. Additionally, when applied to a full-color printer, the overlapping of mixed colors can be reproduced well.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of an inkjet recording device to which the present invention can be applied, FIG. 2 is a schematic sectional view showing a first embodiment of the present invention, and FIGS. 3 (A) to (D) are An explanatory diagram for explaining the effects of the first embodiment. Figure 4〈^)-7(E) is an explanatory diagram for explaining the effects of the second embodiment of the present invention. Figure 5 is an explanatory diagram for explaining the effects of the second embodiment of the present invention. FIGS. 6(A) and 6(B) are schematic cross-sectional views showing the third embodiment of the invention, respectively.
FIG. 2 is a schematic cross-sectional view showing an example of the present invention and a schematic view showing its application head portion. 1,5l... Inkjet recording head, 6... Recording medium, 6A... Water repellent layer, 1l... Platen roller, 24... Fixing device, 25. 26... Conveyance roller, 27... Oil sponge, 52... Application head section. Figure 2 (A) Figure 3 (B) (A) (C) Figure 4 (B) Figure 5

Claims (1)

[Scope of Claims] 1) In an inkjet recording apparatus equipped with a recording head that performs recording on a recording medium by discharging ink from an ejection port, a moving means for moving the recording medium relative to the recording head; , before the recording medium reaches a recording position by the recording head due to the movement, a water repellent treatment is performed to carry a water repellent having poor wettability to the ink on the recording surface of the recording medium. An inkjet recording device characterized by comprising means. 2) The inkjet recording apparatus according to claim 1, wherein the water repellent treatment means includes a member that applies an oily agent as the water repellent. 3) The inkjet recording apparatus according to claim 2, wherein the member is also used as a conveyance member provided for feeding or conveying the recording medium. 4) The inkjet recording apparatus according to claim 3, wherein the water repellent treatment means includes a porous member impregnated with an oily agent in order to transfer the oily agent to the member. 5) The member or the porous member is switchable so as to be in pressure contact with the recording medium or the member when the recording medium is being conveyed, and open when the recording medium is not being conveyed, respectively. Inkjet recording device. 6) The water repellent treatment means has a thermal transfer head that melts the wax-like oily agent as the water repellent agent supported on the film-like ribbon by means of exothermic energy, transfers it onto the recording medium, and solidifies it; 2. The inkjet recording apparatus according to claim 1, wherein the wax-like oil agent is applied by a thermal transfer head in accordance with recording information. 7) The inkjet recording apparatus according to claim 1, further comprising means for forcibly fixing the ink after the ink is ejected and recording is performed.