JPH07290716A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To keep the original image forming capacity of variable density inks to form a stable good image by making the color mixture of the variable density inks incospicuous even when the color mixture of the various density inks is produced when the peripheries of respective emitting orifice rows emitting the variable density inks are wipen by the same blade. CONSTITUTION:Wiping operation using a blade is performed in the order from a recording head 10B emitting ink low in density to a recording head 10A emitting ink high in density or in the direction from an emitting orifice row emitting the ink low in density to an emitting orifice row emitting the ink high in density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for recording by ejecting ink from a recording means onto a recording material.

[0002]

2. Description of the Related Art A recording device having functions such as a printer, a copying machine and a facsimile, or a recording device used as an output device of a multifunction machine or a workstation including a computer, a word processor, etc., is a sheet or a plastic thin plate based on image information. Images (including characters and symbols) on recording materials (recording media) such as (sheets for OHP)
Is configured to record. The recording device can be classified into an ink jet type, a wire dot type, a heat sensitive type, a thermal transfer type, a laser beam type and the like depending on the recording system of the recording means used.

In a serial type recording apparatus which employs a recording system in which a main scanning is performed in a direction intersecting a conveying direction (sub-scanning direction) of a recording material, the recording material is set at a predetermined recording position and then the recording material is set. An image (including characters, symbols, etc.) is recorded by a recording unit (recording head) mounted on a carriage that moves (main scanning) along, and after one line of recording is completed, a predetermined amount of paper is fed (sub-scan). An image is recorded in a desired range of the recording material by repeating the operation of performing (scanning) and then recording (main scanning) the image of the next row. On the other hand, in a line type recording apparatus that records a recording material only in the sub-scanning direction in which the recording material is fed in the transport direction, the recording material is set at a predetermined recording position, and one line of recording is continuously performed at one time. A predetermined amount of paper feed (pitch feed) is performed, and an image is recorded on the entire recording material.

Among them, the ink jet type (ink jet recording apparatus) is a means for recording by ejecting ink from a recording means (recording head) onto a recording material, and it is easy to make the recording means compact and high definition. Images can be recorded at high speed, plain paper can be recorded without requiring special processing, running costs are low, and the non-impact method reduces noise and uses multicolor inks. Therefore, it has an advantage that it is easy to record a color image. Above all, a line type recording apparatus using a line type recording means in which a large number of ejection ports are arranged in the paper width direction can further speed up recording.

In particular, an ink jet type recording means (recording head) for ejecting ink by utilizing heat energy,
Through the semiconductor manufacturing process such as etching, vapor deposition, and sputtering, the electrothermal converter formed on the substrate, the electrode,
By forming the liquid passage wall, the top plate, and the like, it is possible to easily manufacture a liquid discharge device having a high-density liquid passage arrangement (ejection port arrangement), and to further reduce the size. Further, by utilizing the advantages of IC technology and micro processing technology, it is easy to make the recording means long and planar (two-dimensional), and it is also easy to make the recording means full-multi and high-density mounting. is there. On the other hand, there are various requirements for the material of the recording material, and in recent years, in addition to the usual recording material such as paper and resin thin plate, thin paper and processed paper (paper with punch holes for filing and perforation). Paper, paper of any shape, etc.)
It has been required to use such as.

In the ink jet recording apparatus for ejecting ink by utilizing the above thermal energy, since the ink is ejected, a heating element (electrothermal converter) is provided in the vicinity of the ejection port.
Is provided, an ink is locally heated by applying an electric signal to the heating element to cause a pressure change, and the pressure change is used to eject the ink from the ejection port. Further, an inkjet recording apparatus of a type that ejects ink using an electromechanical transducer such as a piezoelectric element is also used.

As a method for controlling recording of halftone in a recording apparatus of this type, a dot density control method for expressing halftone by controlling the number of recording dots per unit area by recording dots of a constant size, or recording There is a dot diameter control method that expresses a halftone by controlling the dot size. However, in the latter dot diameter control method, there are restrictions such as requiring complicated control for subtly changing the size of recording dots, so in general,
The former dot density control method is used.

Further, when an electrothermal converter is used as the ink ejecting means, that is, when the electrothermal converter capable of high resolution because it is easy to manufacture and high in density is used, The dot density control method is adopted because it is difficult to control the pressure change amount and it is difficult to modulate the diameter of the recording dot.

The systematic dither method is one of the typical binarization methods for the halftone expression used in the dot density control method. However, this systematic dither method has a problem that the number of gradations is limited by the matrix size. That is, it is necessary to increase the matrix size in order to increase the number of gradations. However, if the matrix size is increased, one pixel of a recorded image composed of one matrix becomes large, and there is a problem that the resolution is impaired. is there.

Another typical binarization method is a conditional decision type dither method such as an error diffusion method. This method is an independent decision type dither method in which the systematic dither method described above is binarized by using a threshold value unrelated to the input pixel, while a method of changing the threshold value in consideration of peripheral pixels of the input pixel. is there. The conditional decision type dither method typified by this error diffusion method has good compatibility of gradation and resolution,
Moreover, when the original image is a printed image, there is an advantage that a moire pattern is rarely generated in the recorded image, but on the other hand, there is a problem that the graininess is easily noticeable in the bright areas of the image and the image quality is low. Then, this problem is particularly remarkable in a recording device having a low recording density.

Therefore, in order to make the above-mentioned graininess inconspicuous, a conventional ink jet recording apparatus is provided with two recording heads for ejecting a light-colored ink and a dark-colored ink, and from the bright portion of the image to the halftone. There has been proposed a recording method in which a recording dot is formed with a light color ink in a portion and a recording dot is formed with a dark color ink from a halftone portion to a dark portion.

On the other hand, in the ink jet recording apparatus, when foreign matter such as unnecessary ink droplets or paper dust adheres to the ejection opening surface (the front surface of the recording head on which the ejection opening is formed), the ejection direction of the ink is biased and the image quality is deteriorated. It may decrease. That is, in the ink jet recording apparatus, since recording is performed by ejecting ink droplets from a recording head onto a recording material (paper, OHP film, etc.), fine ink droplets other than the ejected main ink droplets, or Ink droplets may adhere to the ejection port surface of the recording head due to rebound of ink droplets landing on the recording material (due to generation of ink mist), and the ejection port surface may become wet. If the ejection port surface gets wet with ink and a large amount of the ink gathers around the ejection port, the ejection of the ink is hindered and ejected in an unexpected direction (deviation), or no ink droplet is ejected (non-ejection). May cause adverse effects such as.

In the ink jet recording apparatus, in order to solve the above-mentioned problems caused by using the liquid ink, as a unique constitution not found in other recording apparatuses, a wiping which makes contact with the ejection port surface is performed. A structure is provided in which foreign materials such as ink droplets on the ejection port surface are wiped and removed (wiping) by providing a member and moving the both members relative to each other, thereby refreshing (restoring) the ejection port surface and causing irregularity in the ejection direction. It has been carried out to prevent and recover from discharge failures.

Unnecessary ink droplets adhering to the ejection port surface are formed by ink mist generated when ink is ejected during recording or ink splashing from paper, and foreign matter such as paper dust is also recorded during recording. When and move relatively close to each other, they adhere to the ejection port surface. For this reason, it is common practice to remove the deposits on the ejection port surface by wiping means during or after recording.

As the wiping means, it is often the case that the above-mentioned unnecessary ink droplets are wiped and removed by wiping the ejection port surface with a blade (wiper) formed of an elastic material such as rubber. However, in such a wiping means, the wiping function deteriorates due to a long-term use or a temporary increase in the amount of ink to be removed, which makes it difficult to recover and maintain the ejection performance, and further, a blade as a wiping means. In some cases, the viscous ink or foreign matter deposited on the surface of the ink is transferred to the ejection port surface in the opposite direction, which causes an improper wiping effect such as an improper ejection direction or improper ejection of the foreign matter into the ejection port.

As another problem, when the ejection port surface of the recording head is wiped, some of the wiped ink droplets may be scattered by the elastic force of the blade and the inside of the recording apparatus may be soiled. Most of the ink drops remaining on the blade without being scattered and foreign matter such as paper dust remain attached to the blade. Then, as the water content of the ink that is still attached to the blade evaporates, the ink itself thickens, and foreign matter such as paper dust is also firmly adhered and deposited, and these are transferred to the ejection port surface in reverse. In some cases, ejection failure (non-ejection, twist, etc.) may occur.

Further, in a recording apparatus in which two or more recording heads are arranged side by side to perform color image recording using inks of different colors, the ink transferred to the blade by the first wiping is changed to the next different color. When wiping the recording head, the color of the recording head is mixed with the ink of the recording head, and the quality of the recorded image deteriorates.

Further, in the case of a color ink jet recording apparatus, when a plurality of recording heads are wiped by one blade, the amount of ink adhering to the blades and contaminating the blades also increases, so that the blades are also adversely affected. Therefore, there is a configuration in which a dedicated blade is provided for each recording head, but this causes a problem that the cost is very high and a larger space is required to provide the wiping means.

In order to prevent the above-mentioned deterioration of the wiping function, cleaning means for the wiping means may be provided. An optimal and commonly used configuration of this cleaning means is to use a porous ink absorber having excellent ink absorbency. The ink absorber can be cleaned by contacting with a blade or the like as wiping means and moving (sliding) relative to each other to wipe off and remove foreign matter adhering to the blade and absorb ink. . However, even if the ink absorber has excellent cleaning performance, the absorption performance (absorption property) may decrease as it absorbs the ink, and the long-term reliability may be lacking.

[0020]

In the above-mentioned conventional ink jet recording apparatus, from the viewpoints of space saving and improvement of throughput, a plurality of colors each having a plurality of ejection port arrays (ejection port group) for ejecting dark and light ink ( For example, since four recording heads of four colors are sequentially wiped by one wiping member (wiper blade), the order of ejection port rows in image formation is dark black, light black, dark cyan, light cyan, and dark magenta. , A plurality of recording heads containing eight kinds of inks arranged in light magenta, dark yellow, and light yellow are wiped in this order.

In the case of such a wiping order, for the same color ink, the wiping order is from dark ink ejection port surface to light ink ejection port surface.
When wiping the ejection port surface of dark ink, the dark ink remains on the blade (wiping member), and when wiping the ejection port surface of the light ink, the remaining dark ink is pushed into the ejection port of the light ink. There is a problem that the density of light ink is increased and the degree of light and dark is disturbed.

That is, if an image is recorded in such a state, even if a highlight portion is recorded with light ink, the density of that portion becomes high, and a desired image cannot be obtained. Further, the graininess in the highlight portion increases, and the ability of the recording apparatus that uses dark and light ink to improve the image cannot be exerted, and four colors of black, cyan, magenta, and yellow are used. The image may be worse than that of the recording device. Further, since the wiping order is changed from light ink to dark ink between different color inks, the wiping order is slightly smaller than that in the case of wiping from light ink to light ink, dark ink to dark ink, or dark ink to light ink. Although there is an improvement, it is extremely insufficient.

The present invention has been made in view of the above prior art, and an object of the present invention is to eject each ejection port when wiping each ejection port surface in an ink jet recording apparatus for recording using dark and light ink. Even if a color mixture of ink occurs between rows, the color mixture can be made inconspicuous, and a stable and good image can be recorded without reducing the original image forming ability of the recording apparatus using the dark and light ink. An object is to provide a possible inkjet recording device.

[0024]

According to a first aspect of the invention, in an ink jet recording apparatus for recording by ejecting ink from a recording means to a recording material, a recording means using a low density ink and a high density ink are used. By adopting a configuration in which the wiping is performed in the order of the recording means, the color mixture at the time of wiping is made inconspicuous, thereby achieving the above object. According to a second aspect of the present invention, in an inkjet recording apparatus that performs recording by ejecting ink from a recording unit to a recording material, the ejection port array ejecting low density ink is directed to the ejection port array ejecting high density ink. The same purpose is achieved by adopting a configuration of wiping in the direction.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. FIG. 1 is a schematic perspective view showing a schematic configuration of a first embodiment of an inkjet recording apparatus to which the present invention is applied. In FIG. 1, a recording material 1 made of a sheet of paper, a plastic thin plate, or the like is held by a pair of discharge rollers 4 and 5 via a pair of transport rollers 2 and 3, and these rollers are rotationally driven by a transport motor (not shown). The paper is fed in the direction of the arrow. A guide shaft 6 and an encoder 7 extending in a direction perpendicular to the direction in which the recording material 1 is conveyed are installed between the conveying roller pairs 2 and 3 and the paper discharging rollers 4 and 5.

The carriage 8 is guided and supported by the guide shaft 6 and the encoder 7 so as to be capable of reciprocating. The carriage 8 is reciprocally moved along the guide shaft 6 by a carriage motor (not shown) via a drive belt (not shown). A recording means 10 is mounted on the carriage 8, and in the present embodiment, the recording means 10 is composed of two recording heads (inkjet units) 10A and 10B. In addition, when referring to all or any one of the plurality of recording heads, they are simply referred to as the recording head 10.

Therefore, on the ejection opening surface (front surface) of one recording head 10A, an ejection opening row (ejection opening group) for ejecting dark black color ink, an ejection opening row for ejecting dark cyan color ink, and a dark An ejection port array for ejecting magenta color ink and an ejection port array for ejecting dark yellow color ink are provided. On the ejection port surface of the other recording head 10B, an ejection port array that ejects light black color ink, an ejection port array that ejects light cyan color ink, an ejection port array that ejects light magenta color ink, An ejection port array for ejecting yellow color ink is provided.

At the time of recording, each ejection port of each recording head 10A, 10B is selectively driven based on the recording information according to the timing of reading the position of the carriage 8 by the encoder 7, and the recording material 1 is printed in the order of dark ink color and light ink color. An image can be recorded by ejecting ink droplets onto the surface.

The recording head (recording means) 10 is an ink jet recording means for ejecting ink by utilizing heat energy, and has an electrothermal converter for generating heat energy. In addition, the recording head 10
Is to perform recording by ejecting ink from an ejection port by utilizing a pressure change caused by growth and contraction of bubbles due to film boiling caused by thermal energy applied by the electrothermal converter.

FIG. 2 is a partial perspective view schematically showing the structure of the ink ejection portion of the recording head 10. In FIG.
A discharge port surface 8 that faces the recording material (recording paper or the like) 1 with a predetermined gap (for example, about 0.5 to 2.0 mm).
1, a plurality of discharge ports 82 are formed at a predetermined pitch,
An electrothermal converter (heat-generating resistor, etc.) 85 for generating energy for ejecting ink is arranged along the wall surface of each liquid passage 84 that connects the common liquid chamber 83 and each ejection port 82. The plurality of ejection openings 82 are arranged in such a positional relationship that they are arranged in a direction intersecting the moving direction (main scanning direction) of the recording head 10. In this way, the corresponding electrothermal converter 85 is driven (energized) based on the image signal or the ejection signal to cause the ink in the liquid passage 84 to film-boil, and the ink generated from the ejection port 82 is ejected by the pressure generated at that time. The recording means 10 is configured.

In FIG. 1, a recovery unit having a cap portion is arranged at the home position HP of the carriage 8 selected outside the recording area. When recording is not performed, the carriage 8 is moved to the home position HP, and the ejection port surface 81 of the corresponding recording head 10 is hermetically sealed by the caps of the cap unit, and the ink is fixed in the vicinity of the ejection port due to ink solvent evaporation or Prevents clogging caused by foreign matter such as dust.

In addition, the capping function of the cap portion is an empty ejection mode in which ink is ejected to the cap portion apart from the ink ejection port in order to eliminate ejection failure or clogging of the ink ejection port which is infrequently recorded. And is used for recovering the ejection failure to normal ink ejection by sucking ink from the ink ejection port by operating a pump (not shown) in a capped state. Further, the ejection port surface 81 of the recording head 10 is cleaned by disposing a wiping means composed of a blade or a wiping member at a position adjacent to the cap portion.

FIG. 3 is an exploded perspective view showing a structural example of the recording means of the ink jet recording apparatus according to the present invention. In FIG. 3, a metal support plate 1 serving as a bottom plate of the recording head 10
A wiring board 12 is mounted on the upper surface of the wiring board 1. One end of the wiring board 12 is connected to the wiring part of the heater board 13 and the other end of the wiring board 12 receives an electric signal from the apparatus main body. A plurality of pads are provided corresponding to each electrothermal converter for receiving. That is, the electric signal from the apparatus body is supplied to each electrothermal converter.

In FIG. 3, the presser spring 14 is a groove 15
Of the ink ejection port, which is bent to have a substantially U-shaped cross section in order to elastically press a line, a claw hooked by using an escape hole provided in the base plate, and a spring. It has a pair of rear legs that receive a force from the base plate. Due to the spring force of the pressing spring 14, the wiring board 12 and the groove top 15 are pressed against each other.

The wiring board 12 is attached to the support 11 by sticking with an adhesive or the like. A filter 16 is provided at the end of the ink supply tube. The ink supply member 17 is made by molding, and the channel 15 is formed with a flow path communicating with each ink supply port. To fix the ink supply member 17 to the support 11, the two pins (not shown) on the back surface side of the ink supply member 17 are fixed to the support 1.
It is simply carried out by projecting through the holes 18 and 19 of No. 1 and heat-sealing them.

At this time, the gap between the ejection port plate portion 20 and the chip tank (ink supply member) 17 is formed uniformly. The sealant is injected from the upper sealant injection port of the ink supply member 17, seals the wire bonding, and at the same time seals the gap between the discharge port plate portion 20 and the chip tank 17, and is further provided on the support member 11. The groove between the discharge port plate portion 20 and the front end portion of the support member 11 is completely sealed through the groove 21.

FIG. 4 is a perspective view of the groove 15 in FIG. 3 as viewed from the heater board 13 side. As shown in FIG.
A plurality of (four) liquid chambers 22a, 22b, 22c, 22
d is provided, and each liquid chamber 22 is partitioned by a wall 23. Supply port 2 for introducing ink into each liquid chamber 22
4 are provided. A groove 25 is provided on a pressure contact surface of the wall 23 partitioning the liquid chambers 22 with the heater board 13. The groove 25 communicates with the outer peripheral portion of the groove top 15.

After the groove ceiling 15 is pressed against the heater board 13 and brought into close contact therewith, the outer peripheral portion thereof is sealed with the sealant as described above. At that time, the sealant permeates along the groove 25 and fills the gap between the groove top 15 and the heater board 13. Through such a technical process, each liquid chamber 22 can be formed in a completely separated state. The groove 25
The structure depends on the physical properties of the encapsulant, and it is desirable to have a shape corresponding to each. By separating the liquid chamber 22 into a plurality of chambers in this way, different inks can be supplied to each ink ejection port group (each ejection port array).

FIG. 5 is a front view showing the state of the ejection port surface 81 of the recording means 10 of the ink jet recording apparatus to which the present invention is applied. FIG. 5 shows a state in which ink adheres to the ejection port surface 81 of the recording head 10 due to the bounce of the ejected main ink droplets. In FIG. 5, in each of the recording head 10A using dark ink of each color and the recording head 10B using light ink of each color, each color of yellow (Y), magenta (M), cyan (C) and black (Bk) Ink droplets of respective colors are attached in the vicinity of the ejection opening group. The recording heads 10A, 10
A desired number (two) of sealing discharge ports 27 are provided between each discharge port row B (each discharge port group) for sealing.

Therefore, in the ink jet recording apparatus of the present invention, the cleaning operation by wiping is performed in the order of the recording means (recording head) 10B using low density ink to the recording means (recording head) 10A using high density ink. Be seen. Further, in the ink jet recording apparatus of the present invention, the ejection port array ejecting ink with high lightness (eg, yellow ejection port group) goes to the ejection port array ejecting ink with low lightness (eg, black ejection port group). The cleaning operation by wiping is performed in the direction. As the wiping means, a configuration is adopted in which the ejection port surface 81 is wiped with a blade formed of an elastic member such as rubber to wipe off unnecessary ink droplets.

As shown in FIG. 5, the unnecessary ink droplets 26 adhering to the ejection port surface 81 are formed by the ink mist generated when the ink is ejected during recording or the rebound of the ink from the recording paper. It is considered that foreign substances such as paper dust adhere to the surface 81 when the recording head 10 moves close to and relative to the recording paper during recording. In this way, since the ink of the corresponding color adheres to the vicinity of each of the yellow (Y), magenta (M), cyan (C), and black (Bk) ejection port groups, the recording head 10 in FIG.
By wiping in the y direction (either positive or negative) perpendicular to each ejection port array (each ejection port group), almost color mixing occurs even in a recording head in which a plurality of colors exist in the same head. Instead, the entire discharge port surface 81 can be cleaned. Note that the arrow y direction in FIG. 5 and each direction forming a right angle thereto are also shown in FIG.

FIG. 6 is a schematic plan view showing the wiping operation of the recording head in the ink jet recording apparatus to which the present invention is applied. Next, the wiping operation according to the present invention will be described with reference to FIG. In FIG. 6, (a) shows the state immediately before the wiping operation is performed. First, blade 3
0 moves forward (projects) in the direction of arrow F from the standby (reverse) position
Then, the ejection port surface 81 of the recording head 10 is fixed at a position (wiping position) that is an optimum amount of entry for wiping.

Next, as shown in FIGS. 6B and 6C, when the carriage 8 carrying the recording head 10 moves horizontally from left to right, the blade 30 causes the blade 30 to move.
The inks adhering to the ejection port surface 81 are sequentially contacted by alternately contacting the blade-cleaning absorber 31 disposed at the bottom of the sheet and the ejection port surface 81 of each recording head 10 protruding from the carriage 8. Wiping off (wiping). At this time, the blade 30 is also itself cleaned by the absorber 31.

All absorbers (blade cleaner) 31
When the contact sliding with the ejection port surface 81 of all the recording heads is completed, the blade 30 retracts in the direction of arrow G and stands by at the standby position. By providing the blade cleaners (absorbent bodies) 31 on both sides of the recording head 10 as shown in the figure, the ink wiped from the ejection port surface 81 can be absorbed by the blade cleaners 31 and thereby adhered and remain on the blades 30. It is possible to reduce the amount of ink, and it is possible to effectively prevent color mixing of ink when the ejection port surface 81 of the next recording head 10 is wiped.

Although the recording head 10 is wiped by such a procedure, since the absorption capacity of the porous absorber 31 which is a blade cleaner for cleaning the blade 30 is limited, the blade 30 is always kept clean. It's not easy to do. Therefore, it is conceivable that the next wiping of the recording head 10 is performed while the ink remains on the blade 30. In such a case, the ink of the recording head 10 that has been wiped previously may be removed by the blade 30.
When the next recording head 10 is wiped, the ink of the previous recording head left on the blade 30 is pushed into the ejection port 82 of the next recording head,
The problem of ink color mixing will occur.

At this time, when wiping is performed in order from dark ink to light ink, the dark ink is pushed into the light ink recording head. Since the recording head of the light ink forms an image of the highlight portion, the dark ink that has been pushed in is ejected to the highlight portion, and the difference between the recording material 1 and the ink density becomes large, and the normal recording is performed. The image cannot be obtained.

However, when wiping is performed in order from the light ink to the dark ink, the light ink can be pushed into the dark ink recording head, but the dark ink recording head forms an image of a dark portion. The light ink that has been pushed into the ejection port of the recording head that will be wiped later will be driven into the dark portion. In the dark portion, since both dark ink and light ink are ejected, the density difference in the ejected portion is not so large and is not very noticeable on the recording material 1. Therefore, when wiping is performed, by performing wiping in the order of the print head using the ink having a low density to the print head using the ink having a high density, it is possible to make the color mixture at the time of wiping inconspicuous on the image. Become.

Further, the recording head 10 for ejecting dark ink
In the case where two recording heads, A and the recording head 10B that ejects the light ink, are arranged on the carriage 8 at a predetermined interval, the light ink recording head is directed from the home position side toward the recording area side. Wiping the dark ink recording head in the direction from the recording area side to the home position side, such as wiping each of the dark and light recording heads in the opposite direction, or
The wiping direction is kept constant, and the blade 30 itself is rotated 180 degrees immediately after wiping the light ink recording head to wipe the dark ink recording head on the surface opposite to the blade. Good.

According to such a wiping method, by using both sides of the blade 30, each blade surface is divided into a blade surface for wiping only the dark ink recording head and a blade surface for wiping only the light ink recording head. It can be dedicated, and thereby the above color mixture due to the ink adhering to the blade surface can be prevented.

In addition, similar color inks having different densities have different shades of 2
Even when there are a plurality of types instead of the types, wiping is performed on these recording heads in the order of a recording head that ejects ink with low density and a recording head that ejects ink with high density. As in the case, it is possible to prevent color mixture due to wiping.

There is an ink jet recording apparatus having a structure in which the same recording head ejects similar color dark and light inks in order to improve the accuracy of landing position of the similar color dark and light inks, and the present invention is also applicable to such a recording apparatus. . FIG. 7 is a schematic perspective view showing the main configuration of such an inkjet recording apparatus. In FIG. 7, the carriage 8 has four recording heads 10 for recording with ink colors of yellow (Y), magenta (M), cyan (C), and black (Bk).
Y, 10M, 10C and 10Bk are mounted. As shown in FIG. 12, the recording head 10 for each of these colors is
A row of light ink ejection openings (ejection opening group) that ejects light ink and a row of dark ink ejection openings (ejection opening group) that ejects dark ink are vertically divided. The recording apparatus of FIG. 7 has substantially the same configuration as that of the recording apparatus of FIG. 1 in other aspects. Corresponding parts are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 8 is an exploded perspective view showing a structural example of each recording head (recording head for ejecting dark and light ink) 10 in FIG. In FIG. 8, a wiring board 12 is mounted on the upper surface of a metal support plate 11 that serves as a bottom plate of the recording head 10. One end of the wiring board 12 is connected to a wiring portion of a heater board 13, and At the other end of the wiring board 12, a plurality of pads corresponding to each electrothermal converter for receiving an electric signal from the apparatus main body are provided.
That is, the electric signal from the apparatus body is supplied to each electrothermal converter.

In FIG. 8, the presser spring 14 is a groove 15
Of the ink ejection port, which is bent to have a substantially U-shaped cross section in order to elastically press a line, a claw hooked by using an escape hole provided in the base plate, and a spring. It has a pair of rear legs that receive a force from the base plate. Due to the spring force of the pressing spring 14, the wiring board 12 and the groove top 15 are pressed against each other. The wiring board 12 is attached to the support 11 by sticking with an adhesive or the like.

A filter 16 is provided at the end of the ink supply tube. The ink supply member 17 is made by molding, and the channel 15 is formed with a flow path communicating with each ink supply port. Support 11 for ink supply member 17
The two pins (not shown) on the back surface side of the ink supply member 17 are projected through the holes 18 and 19 of the support 11 respectively and heat-sealed.

At this time, the gap between the ejection port plate portion 20 and the chip tank (ink supply member) 17 is formed uniformly. The sealant is injected from the upper sealant injection port of the ink supply member 17, seals the wire bonding, and at the same time seals the gap between the discharge port plate portion 20 and the chip tank 17, and is further provided on the support member 11. The groove between the discharge port plate portion 20 and the front end portion of the support member 11 is completely sealed through the groove 21.

FIG. 9 is a perspective view of the groove 15 in FIG. 8 as viewed from the heater board 13 side. As shown in FIG.
Is provided with a plurality of (two for light and shade) liquid chambers 22, and each liquid chamber 22 is partitioned by a wall 23. Each liquid chamber 22
Is provided with a supply port 24 for introducing ink. Heater board 1 for wall 23 partitioning each liquid chamber 22
A groove 25 is provided on the pressure contact surface with 3. This groove 25
Communicates with the outer periphery of the groove 15.

After the groove ceiling 15 is pressed against the heater board 13 and brought into close contact therewith, the outer peripheral portion thereof is sealed with the sealant as described above. At that time, the sealant permeates along the groove 25 and fills the gap between the groove top 15 and the heater board 13. Through such a technical process, each liquid chamber 22 can be formed in a completely separated state. The groove 25
The structure depends on the physical properties of the encapsulant, and it is desirable to have a shape corresponding to each. By separating the liquid chamber 22 into a plurality of chambers (two chambers) in this way, different inks (dark and light inks) are provided to the respective ink ejection port groups (each ejection port row) that are divided and arranged in the recording material conveyance direction. ) Can be supplied. In the present embodiment, recording material 1 is formed by ejecting dark and light inks of similar colors from the same recording head.
The mutual landing accuracy between the dark and light inks above is improved.

FIG. 10 shows four recording heads 10 capable of ejecting dark and light inks, that is, recording heads for the respective colors of yellow (Y), magenta (M), cyan (C) and black (Bk). 10Y, 10M, 1
The cartridge type recording head unit in which 0C and 10Bk are integrally assembled by a frame 35 is shown.
The four recording heads 10 are mounted in the frame 35 at a predetermined interval, and are positioned and fixed in a state where the resists in the dark and light (upper and lower) ejection port array directions are also adjusted.

In the present embodiment, the mutual landing position accuracy between colors is improved by adjusting using the mechanical reference surface of each recording head. However, after actually fixing the recording head to the frame 35, It is also possible to eject the ink onto the ink to measure the landing positions and directly adjust the mutual landing positions between the colors based on the data, and such an adjusting method can further improve the accuracy. Reference numeral 36 is a cover of the frame 35, and 37 is a connector for connecting pads provided on the wiring substrate 12 of the four recording heads 10 and electric signals from the recording apparatus main body.

Assembling the four recording heads 10 integrally is advantageous not only in handling advantages but also in improving the mutual landing position accuracy between the recording heads as described above. It is also very effective in reducing the number of signal line connections to the main unit. For example, a signal line common to four recording heads such as a GND line can be made common to reduce the number of lines as it is. Further, if an integrated circuit board is provided and time-division driving is performed for each recording head. It is also possible to use common recording signal lines. Such a means for reducing the number of electrical connections is advantageous in a recording apparatus having a large number of signal lines such as a color machine or a multi-nozzle high speed machine, and is particularly effective in a dark and light inkjet recording apparatus according to the present invention. .

FIG. 11 is a schematic perspective view showing a state in which the cartridge type recording head unit including the above-mentioned four recording heads 10 is mounted on the carriage 8 for recording and scanning. The ink tank of each recording head 10 is divided into two chambers, each filled with dark ink and light ink. Then, the ink tanks for the dark and light inks of the four colors are respectively connected to the respective recording head portions (ink ejection means) on the carriage 8 and are connected to the liquid chambers 22 separated into two to supply the ink. As described above, in this embodiment, the dark and light inks are filled in the ink tanks of one recording head (inkjet cartridge) 10, the recording heads having such a structure are prepared for each of the four colors, and these four recordings are performed. Since recording is performed using an integrated recording head unit that has a total of eight liquid chambers 22 and ejection port arrays (ejection port groups) corresponding to these heads integrated, the inconvenience in handling accompanying grayscale recording Can be resolved.

FIG. 12 is a schematic front view showing a state in which ink mist or the like is attached to the ejection port surface of the four-color recording head-integrated recording head unit described with reference to FIGS.
That is, a state is shown in which ink is attached to each ejection port surface 81 due to rebound of the main ink droplets ejected from each recording head 10. Also in this embodiment, a desired number (two) of sealing ejection ports 27 are provided for sealing between the dark and light ejection port arrays (ejection port group) of each recording head.

In the embodiment of FIG. 12, when the wiping operation is performed in the direction perpendicular to the ejection port array (direction of arrow y in FIG. 12), if the amount of ink adhered on the ejection port surface 81 is large, the ejection port array is Since wiping is performed in the y direction (FIGS. 7 and 12) that is perpendicular to the (ejection port group), two types of ink, dark and light, are mixed in the same recording head, and the dark ink ejection ports of the light ink ejection port array are mixed. There is a high probability that the mixed color ink will be pushed into the near portion and the portion near the light ink ejection port of the ejection port array that ejects dark ink. In this case, when the mixed color ink is pushed into the light ink ejection port, the color mixture on the recording material 1 is very conspicuous, but it is not so conspicuous when the dark ink ejection port is pushed with the mixed color ink.

Therefore, in this embodiment, in order to prevent the color mixture due to wiping in the same recording head from being conspicuous on the recording material 1, from the side of the light ink ejection port array side to the dark ink ejection port array side. A wiping operation is performed toward the x direction (FIGS. 7 and 12) parallel to the ejection port array. By adopting such a wiping operation, it is possible to greatly reduce the probability of dark ink being pushed into the light ink ejection port that may occur when wiping in the y direction perpendicular to the ejection port array.

FIG. 13 is a schematic plan view showing the wiping operation of the recording head in the embodiment of FIGS. In FIG. 13, (a) shows the state immediately before the wiping operation is performed. First, as the carriage 8 moves, the recording heads 10 mounted on the carriage stand by on the moving line of the blade 30. And in FIG.
Blade holder 38 as shown in (b) and (c) of FIG.
Is moved in the direction of arrow H (the direction of arrow x in FIGS. 7 and 12), the blade 30 protrudes from each of the blade cleaners (ink absorbers) 31 provided at the bottom of the carriage 8. The ink on the ejection port surface 81 of the recording head is rubbed to remove the ink on the ejection port surface 81, and the ink is also cleaned (cleaned) by the ink absorber 31.

The above wiping operation is performed with yellow (Y),
Magenta (M), Cyan (C) and Black (Bk)
Is sequentially executed for each recording head, and by completing this, a series of wiping operations for all recording heads is completed. At that time, as shown in the drawing, each recording head 1
By providing the blade cleaner 31 of the ink absorber on both sides of 0, the ink wiped from the ejection port surface 81 can be sequentially absorbed by the blade cleaner 31, thereby reducing the amount of ink remaining on the blade 30. Therefore, it is possible to effectively prevent color mixture of ink when wiping the ejection port surface 81 of the next recording head 10.

In each of the above-mentioned embodiments, the case of the serial recording system in which the recording means (recording head) is moved in the main scanning direction has been described as an example, but the present invention is not limited to the full width or one width of the recording material. Even in the case of a line recording method for recording only by sub-scanning using a line recording means having a length that covers a portion,
The same can be applied and the same effect can be achieved. Further, the present invention provides a color recording apparatus using a plurality of recording means for recording in different colors, a single color recording apparatus for recording by one recording means, or a plurality of recording means for recording with the same color but different densities. Gradation recording device used,
Furthermore, in the case of a recording device that combines these,
The same can be applied and the same effect can be achieved.

Further, according to the present invention, when a replaceable head cartridge in which a recording head and an ink tank are integrated is used, or when the recording head and the ink tank are separated, and the space between them is connected by an ink supply tube or the like. The same can be applied to any arrangement of the recording head and the ink tank, and similar effects can be obtained.

The present invention can be applied to an ink jet recording apparatus using a recording means (recording head) using an electromechanical transducer such as a piezo element, but among them, thermal energy is used. Then, an excellent effect is brought about in an ink jet recording apparatus which uses a recording means of a method of ejecting ink. This is because such a system can achieve high density recording and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
This is preferably done using the basic principles disclosed in 796. This method can be applied to both the so-called on-demand type and the continuous type, but particularly in the case of the on-demand type, a liquid (ink) is used.
By applying at least one drive signal to the electrothermal converter arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling. , Generates heat energy in the electrothermal converter to cause film boiling on the heat acting surface of the recording means (recording head), and as a result, bubbles can be formed in the liquid (ink) in a one-to-one correspondence with this drive signal. So effective.

Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make the driving signal into a pulse shape because bubbles can be grown and contracted immediately and appropriately, and thus a liquid (ink) with excellent responsiveness can be ejected. As this pulse-shaped drive signal, US Pat.
Those described in US Pat. Nos. 4,633,359 and 4,345,262 are suitable. Incidentally, US Pat. No. 43131 of the invention relating to the rate of temperature rise of the heat acting surface
If the conditions described in the specification of No. 24 are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of No. 459600 is also included in the present invention. In addition, Japanese Laid-Open Patent Publication No. 123670/1984 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy. The present invention is also effective as a structure based on Japanese Patent Laid-Open No. 138461/1984, which discloses a structure in which the discharge section is associated with the discharge section. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, as described above, 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 material (recording medium) which can be recorded by the recording apparatus. . As such a recording head,
Either a structure that satisfies the length by combining a plurality of recording heads or a structure as one recording head integrally formed may be used. In addition, even with the serial type as in the above example, the recording head fixed to the device main body,
Alternatively, a replaceable chip-type recording head that can be electrically connected to the device body and supply ink from the device body when mounted on the device body, or an ink tank is integrally provided on the recording head itself. The present invention is also effective when the cartridge type recording head described above is used.

Further, it is preferable to add recovery means or preliminary auxiliary means to the recording head provided as a constitution of the recording apparatus in the present invention because the effect of the present invention can be further stabilized. Specifically, in addition to the above-mentioned capping means, cleaning means, and suction recovery means for the recording head, a pressure-type recovery means, an electrothermal converter, or a heating other than this. It is also effective to perform stable recording by performing a preliminary heating means using an element or a combination thereof and a preliminary ejection mode for performing ejection different from recording.

As described above, regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of recording heads having different recording colors and densities are provided. A plurality of inks may be provided corresponding to the ink. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be either the recording head is integrally configured or a combination of a plurality of recording heads may be used. The present invention is extremely effective for an apparatus provided with at least one of color colors or full colors by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but it is an ink which solidifies at room temperature or lower and softens or liquefies at room temperature, or an ink jet. In the method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It may be in a liquid form. in addition,
To prevent the temperature rise due to the thermal energy from being positively used as the energy for changing the state of the ink from the solid state to the liquid state, or to use the ink that solidifies in the standing state for the purpose of preventing the evaporation of the ink. In any case, the ink is liquefied by applying the thermal energy according to the recording signal and the liquid ink is ejected,
The present invention is also applicable to the case of using an ink that has a property of being liquefied only by thermal energy, such as one that has already started to solidify when it reaches the recording medium.

The ink in such a case is described in JP-A-54-
As described in JP-A-56847 or JP-A-60-71260, a mode in which it is held as a liquid or a solid in the recesses or through holes of the porous sheet and faces the electrothermal converter. May be In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the ink jet recording apparatus according to the present invention, besides the one used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmitting / receiving function. And the like may be used.

[0079]

As is apparent from the above description, according to the first aspect of the invention, in the ink jet recording apparatus for recording by ejecting the ink from the recording means to the recording material, the recording means using the low density ink. Since it is configured to perform wiping in the order of the recording means that uses high-density ink, even when a color mixture of ink occurs between each ejection port array when wiping the periphery of each ejection port array that ejects dark and light ink, (EN) An ink jet recording apparatus capable of making the color mixture inconspicuous and capable of recording a stable and good image without reducing the original image forming ability of the recording apparatus using dark and light ink.

According to the second aspect of the invention, in the ink jet recording apparatus for recording by ejecting the ink from the recording means to the recording material, the high density ink is ejected from the ejection port array for ejecting the low density ink. Since the wiping is performed in the direction toward the ejection port array, even when ink color mixing occurs between the ejection port arrays when wiping the periphery of each ejection port array that ejects dark and light ink, the color mixing is made inconspicuous. (EN) An inkjet recording apparatus capable of recording a stable and good image without reducing the original image forming ability of the recording apparatus using dark and light ink.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a main part configuration of a first embodiment of an inkjet recording apparatus to which the present invention is applied.

FIG. 2 is a partial perspective view schematically showing the structure of an ink ejection portion of the recording means in FIG.

FIG. 3 is an exploded perspective view schematically showing the structure of the recording head in FIG.

FIG. 4 is a schematic perspective view of the groove in FIG. 3 viewed from the heater board side.

5 is a schematic front view showing a state in which ink is attached to the ejection port surfaces of the dark ink print head and the light ink print head in FIG.

FIG. 6 is a schematic front view showing the wiping operation of each recording head in the recording apparatus of FIG.

FIG. 7 is a schematic perspective view showing a main configuration of an ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 8 is an exploded perspective view schematically showing the structure of the recording head in FIG.

9 is a schematic perspective view of the groove in FIG. 8 viewed from the heater board side.

10 is a schematic exploded perspective view of a recording head unit in which four recording heads in FIG. 7 are integrated.

11 is a schematic perspective view showing a state in which a recording head unit in which four recording heads in FIG. 7 are integrated is mounted on a carriage.

12 is a schematic front view showing a state in which ink is attached to the ejection port surfaces of the four recording heads in FIG.

13 is a schematic side view showing a wiping operation of each recording head in the recording apparatus of FIG.

[Explanation of symbols]

 1 Recording Material 2 Conveying Roller 4 Paper Ejecting Roller 6 Guide Shaft 7 Encoder 8 Carriage 10 Recording Means 15 Groove Top 16 Filter 17 Ink Supply Member (Chip Tank) 20 Discharge Port Plate 22 Liquid Chamber 24 Supply Port 25 Groove 26 Unnecessary Ink Droplet 27 Sealing ejection port 30 Blade (wiping member) 31 Ink absorber (blade cleaner) 35 Frame frame 36 Frame cover 37 Connector 38 Blade holder 81 Discharge port surface 82 Discharge port 84 Liquid path 85 Electrothermal converter

Claims (4)

[Claims] 1. In an inkjet recording apparatus for recording by ejecting ink from a recording means to a recording material, wiping is performed in order of a recording means using a low density ink and a recording means using a high density ink. Characteristic inkjet recording device. 2. In an ink jet recording apparatus for recording by ejecting ink from a recording means to a recording material, in a direction from an ejection port array ejecting low density ink to an ejection port array ejecting high density ink. An inkjet recording device characterized by wiping. 3. The ink jet recording means according to claim 1, wherein the recording means is an ink jet recording means provided with an electrothermal converter for generating thermal energy used for ejecting ink. Inkjet recording device. 4. The ink jet recording apparatus according to claim 3, wherein the recording unit ejects the ink from the ejection port by utilizing film boiling generated in the ink by the thermal energy generated by the electrothermal converter. .