JPH05238003A - Apparatus and method for ink jet recording, and matter recorded thereby - Google Patents

Abstract

PURPOSE:To produce high quality recorded images without extending the time of recording by a method wherein the recording is made by horizontal and vertical scannings while at least one side of both ends on blocks that are divided into a plurality of blocks is made not an end having the end of a nozzle array, and the recording is made, in accordance with data to be recorded, by a plurality of scannings employed for one pixel. CONSTITUTION:In image formation for an area 908, recording by a first scanning is made with nozzles in a block B1, then the recorded matter is fed in the direction of vertical scanning for a distance equivalent to the length of the nozzles 340, and the recording by the second scanning is made, overlapping the area 908, with the nozzles in the block B2. The recording by the third scanning is made likewise with the nozzles in the block B3, and thereby continuous-tone images in four values are formed. At the same time, the nozzles in other blocks work for formation of images by the following scannings. The more the nozzle is positioned close to the end of the nozzle array, the more the temperature of that nozzle declines. Therefore, density gradient D tends to happen to the ink on the upward side and the downward side of a head 101A. By making the density distribution in each of the blocks to be overlapped D1, D2 and D3, the overlapped density distribution DS becomes uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for recording an image by an ink jet system while a recording head moves and scans a recording medium, and is preferably used for output of a copying machine, a facsimile, a computer or the like. The present invention relates to a recording device, an inkjet recording method, and a recorded matter thereof.

[0002]

2. Description of the Related Art Conventionally, a recording apparatus for recording on a recording medium such as paper or OHP sheet (hereinafter also referred to as recording paper) has been proposed in the form of mounting recording heads of various recording systems. .. Among them, the ink jet recording method is a method in which ink is directly ejected from a recording head onto a recording paper, and it is attracting attention as a recording method which has advantages such as low running cost and quiet recording operation. In recent years, inkjet recording apparatuses, especially recording heads, have been manufactured by film forming technology and micro-machining technology in semiconductor devices, and smaller and less expensive recording heads are being realized.

In a recording apparatus of such an ink jet recording system, a recording head in which a large number of fine ink discharge ports located at the tip of a nozzle are arranged is used. Further, as an inkjet recording apparatus, the recording head is reciprocally scanned (also referred to as main scanning or scanning) on the recording sheet in a direction perpendicular to the recording sheet conveyance direction while intermittently conveying (stepping) the recording sheet. There is a so-called serial type that forms an image. In this method, the ejection ports of the recording head are arranged in a line at right angles to the main scanning direction, and the length of the ejection port array (the recording width of one scan) has a great influence on the recording time. The longer the row, the shorter the printhead can be.

However, in manufacturing a recording head, the longer the ejection port array, the more difficult it is to maintain a predetermined accuracy or performance. Even if such a recording head could be manufactured, if a defect such as clogging of the ejection port occurs during the recording operation, even if the number is small, the entire recording head must be replaced at once. It has to be uneconomical. Further, such a recording head also has a big problem in terms of ensuring stability and reliability during use.

On the other hand, a recording head having a shorter ejection port array is easier to manufacture and has higher reliability during use. Further, since the unit price of the recording head is low, there is an advantage that there is little waste at the time of replacement. From the above, in practice, the optimum length of the ejection port array of the recording head is determined after comprehensively considering reliability during use, recording time, cost, and the like.

[0006]

However, the above-mentioned ink jet recording apparatus has a problem that it is not easy to cope with high performance in terms of resolution or gradation. The reason is that there is a limit to the density of the ejection port array when manufacturing the head, and it is not possible to easily increase the resolution. Basically, a recorded image by the inkjet method ejects ink or does not eject it. The point is that it is a binary image.

To solve this problem, the following means have been considered. That is, the amount of ink droplets ejected from each nozzle at one time is reduced, and one unit pixel conventionally represented by one ink dot is represented by a plurality of fine dots. .. This makes it possible to improve the gradation according to the number of dots in the unit pixel without lowering the resolution. However, in order to implement this, it is necessary to increase the ink ejection frequency (the number of ink ejections per unit time) of the recording head, but this is not easy. Therefore, this must be dealt with by lowering the main scanning speed of the recording head, and the recording time becomes longer accordingly. And
In order to prevent this, it is conceivable to lengthen the ejection port array of the print head to lengthen the width for printing in one main scan.
Employing such a recording head has many problems in terms of cost and reliability, as already described. For this reason, it is not easy to improve the image quality of a recorded image and shorten the recording time in the current inkjet recording apparatus.

Further, such a serial type ink jet recording apparatus has two problems of non-ejection of ink from an ejection port and unevenness of ejected ink density. Of these, ink non-ejection is a phenomenon called white void, in which an image like a white line is missing on the recording paper when the non-ejection occurs at an ejection port in the print head for some reason. As a result, the image quality is significantly reduced. The ejected ink density unevenness is a phenomenon that the ink density recorded on the recording paper differs depending on the corresponding ejection port. This is because the shape of each ejection port to be formed is slightly different, the performance of the ink ejection force generation source varies from nozzle to nozzle, and the temperature of each nozzle is different. The cause is that each discharge port is different. Among them, in an ink jet recording apparatus of a type that applies thermal energy to nozzles to eject ink, since the nozzle temperature has a great influence on ink ejection performance, a heater is usually provided in the recording head to keep a constant temperature. Is adjusted.

However, even if the temperature is adjusted in this way, a temperature gradient depending on the location in the recording head is unavoidable. For example, when comparing the central portion and the end portion of the recording head, the end portion is slightly lower. Therefore, the amount of ink discharged is small in the vicinity of the end portion of the discharge port array, and the density of the recorded ink tends to decrease, which causes image density unevenness and deteriorates image quality. These are important problems that are still difficult to solve even if the method for improving the gradation is used.

The present invention has been made in view of the above problems, and an object thereof is an ink jet recording apparatus, an ink jet recording method and an ink jet recording method capable of improving the image quality of a recorded image without extending the recording time. It is to provide recorded materials.

[0011]

SUMMARY OF THE INVENTION An ink jet recording apparatus according to the present invention which solves the above-mentioned problems includes a plurality of ejection port arrays in which a plurality of ejection ports for ejecting ink onto a recording medium are arranged. Main scanning unit that causes the recording units arranged in the main scanning direction to relatively perform main scanning relative to the recording medium in a direction different from the ejection port array direction, and the overall length of the plurality of ejection port arrays for each main scanning. A sub-scanning unit that relatively sub-scans the recording unit and the recording medium in the ejection port array direction by a smaller amount, and a plurality of all ejection ports of the plurality of ejection port arrays in the ejection port array direction. At least one of the ejection ports located at both ends of the block is a block that is not the ejection port at the end of the ejection port array, and the ejection ports of different blocks are used for different main scans according to print data. Recording media And a discharge control means for ejecting the ink on the same pixels, and performing recording by a plurality of times of the main scanning with respect to one pixel.

Here, as a concrete example of the recording means,
An example is a case where a plurality of recording heads each including an ejection port array are provided. Further, each ejection port array of the recording means can be arranged in a direction perpendicular to the main scanning direction or inclined. Further, the recording means causes a state change in the ink by thermal energy and causes the ink to be ejected from the ejection port based on the state change, and causes a state change in the ink due to heat for each corresponding ejection port. It is preferable to have a means for generating heat energy.

Further, according to the present invention, a recording means in which a plurality of ejection port arrays in which a plurality of ejection ports for ejecting ink onto a recording medium are arrayed and arranged in the ejection port array direction is arranged in the ejection port array direction. Ejects ink onto the recording medium while performing main scanning relative to the recording medium in different directions, and the recording unit is smaller than the entire length of the plurality of ejection port arrays for each main scanning. An inkjet recording method for performing recording by relatively sub-scanning the recording medium and the recording medium in the direction of the ejection port array, the main scanning being performed a plurality of times for the same pixel on the recording medium according to recording data. An inkjet recording method is provided in which the recording for the same pixel is not performed by using the ejection ports at two or more ends of the ejection port array.

According to the present invention, a recording means in which a plurality of recording heads having ejection openings for ejecting ink onto a recording medium are arranged in the ejection opening array direction is different from the ejection opening array direction. Main scanning means for performing a main scanning relative to the recording medium relative to the recording medium, and for each main scanning, the recording means and the recording medium are moved relative to each other by an amount smaller than the entire length of the plurality of ejection port arrays. A sub-scanning unit for sub-scanning in the direction of the ejection port array, and a ejection control unit for ejecting ink to the same pixel on the recording medium from different ejection ports during different main scanning according to the recording data. On the other hand, there is provided an inkjet recording apparatus characterized in that recording is performed by the main scanning a plurality of times.

According to the present invention, the recording means in which a plurality of recording heads having ejection openings for ejecting ink onto the recording medium are arranged in the ejection opening array direction is different from the ejection opening array direction. Ink is ejected onto the recording medium while performing main scanning relative to the recording medium in a direction, and each time the main scanning is performed, the ink is discharged from the recording head and the recording head by an amount smaller than the entire length of the plurality of ejection port arrays. An inkjet recording method is provided, in which recording is performed by relatively sub-scanning a recording medium in the ejection port array direction.

Further, according to the present invention, there is provided a recorded matter recorded by the above-mentioned ink jet recording method.

[0017]

In order to perform recording according to the present invention, a plurality of recording heads having ejection openings for ejecting ink onto the recording medium are arranged in the ejection opening array direction, and the recording means is arranged in the ejection opening array direction. Ink is ejected onto the recording medium while performing main scanning relative to the recording medium in a direction different from. Then, printing is performed by relatively sub-scanning the recording head and the recording medium in the direction of the ejection port array by an amount smaller than the entire length of the plurality of ejection port arrays for each main scanning. As a result, the length of the ejection port array of the recording head (the recording width of one scan) can be increased, and the recording time can be shortened as compared with the conventional case. Further, since the recording heads with short ejection port arrays are combined, the manufacturing is easy and the reliability is high. Further, since the print heads can be replaced for each print head, there is little waste.

As another recording method, a recording means in which a plurality of ejection port arrays in which a plurality of ejection ports for ejecting ink onto a recording medium are arrayed and arranged in the ejection port array direction is used. Ink is ejected onto the recording medium while performing main scanning relative to the recording medium in a direction different from the direction. Recording is performed by relatively sub-scanning the recording means and the recording medium in the direction of the ejection port array by an amount smaller than the entire length of the ejection port array for each main scanning. At this time, when printing is performed on the same pixel on the print medium a plurality of times in the main scan according to print data, the print is performed on the same pixel by using the ejection ports at two or more end portions of the ejection port array. Does not. As a result, even if image density unevenness occurs due to the positions of the ejection ports in the ejection port array, it is possible to reduce the influence on the recorded image and obtain high image quality. Therefore, it is possible to improve the image quality of a recorded image without extending the recording time.

[0019]

【Example】

(Embodiment 1) An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a sectional view of the inkjet recording apparatus according to the present invention. The equipment is roughly classified into a recording system 100,
The recording system unit transport system 200, the recording paper transport system 300, a control system (not shown), and the like. The recording system 100 includes an inkjet recording head unit 101 and an ink tank (not shown).
To the recording head, an ink supply tube 103, and a recording head driver (not shown) for controlling the driving of the recording head. Here, the ink discharge method of the recording head is performed by energizing an electrothermal converter for ink discharge disposed inside each nozzle to generate heat, and causing the thermal energy to cause a state change in the ink. A method of ejecting ink from the ejection port is preferably used. However, the ink ejection method is not limited to this, and it is also possible to use a so-called piezo-type recording head that ejects ink by using an electromechanical transducer for ink ejection arranged inside each nozzle.

Next, the ejection principle of the recording head used in the ink jet recording apparatus of this embodiment as the recording means in the present invention will be described in detail. A recording head applied to an inkjet recording apparatus generally includes a fine liquid discharge port (orifice), a liquid passage, and an energy acting portion provided in a part of the liquid passage, and droplet formation for acting on the liquid in the acting portion. It is equipped with an energy generating means for generating energy and is replaceable. As an energy generating means for generating such energy, one using an electromechanical converter such as a piezo element, irradiating an electromagnetic wave such as a laser,
There is a liquid which is absorbed there to generate heat and which ejects and flies droplets by the action of the heat, or a liquid which is heated by an electrothermal converter to eject the liquid. .. Among them, in a recording head unit used in an inkjet recording method in which liquid is ejected by thermal energy, liquid ejection ports (orifices) for ejecting recording liquid droplets to form flying liquid droplets are arranged at high density. Therefore, it is possible to record with high resolution.

In addition, the recording head portion using the electrothermal converter as the energy generating means can be easily made compact as a whole recording head portion, and the recent technological progress and improvement of reliability in the semiconductor field can be achieved. Since the remarkable advantages of IC technology and micro processing technology can be fully utilized and it is easy to lengthen and planarize (dualize), it is easy to realize multi-nozzle and high-density mounting. It is possible to provide an inkjet recording head unit that is mass-producible and has low manufacturing cost.

The ink jet recording head portion manufactured through the semiconductor manufacturing process using the electrothermal converter as the energy generating means is generally provided with a liquid passage corresponding to each ink ejection port, and each liquid passage is provided. Is provided with an electrothermal converter as means for applying thermal energy to the liquid that fills the liquid passage to eject the liquid from the corresponding ink ejection port to form flying droplets. The liquid is supplied from a common liquid chamber that communicates with each liquid passage. In addition, as a method of manufacturing the ink ejection unit, a solid layer for forming at least a liquid channel on the first substrate, an active energy ray-curable material layer used for forming at least a wall of the liquid channel, and a second layer Substrates are sequentially laminated, a mask is laminated on the second substrate, and active energy rays are irradiated from above the mask, and at least the wall of the liquid channel of the active energy ray-curable material layer is used as a constituent portion. There is a method of curing and then removing the uncured portion of the solid layer and the active energy ray-curable material layer from between the two substrates to form at least a liquid path (see JP-A-62-253457).

The recording unit transport system 200 is equipped with a recording head and a recording head driver, and moves the recording head by moving it along a guide rail 221 extending in a predetermined direction (here, a direction orthogonal to the drawing). It is a system including a carriage 201 for scanning the recording paper and others. The recording paper conveyance system 300 is composed of recording paper RP and CS conveyance paths P, PC, PR and PI, and rollers for each section. The control system includes a controller that controls the operation sequence of the entire apparatus and an image processing unit that performs various processes related to the image signal of the output image. CS
Is a cut sheet of recording paper, and is placed on the cassette 7. The RP is a roll of recording paper and can rotate around the rotation axis RPA. PC, PR, and PI are conveyance paths for the cut sheet CS, the roll sheet RP, and the recording sheet inserted in the manual feed port 9, and join near the upstream side of the nipping position of the conveyance roller 301.

A pickup roller 311 is provided on the transport path PC.
And the separation member (not shown) cooperate with each other to introduce the cut sheets separated from the cassette 7, and to install the rollers on each path.
While being sandwiched by 316, 315, and 314, it is guided on the transport path PC and guided to the transport roller 301. In the conveyance path PR, there are a set roller 324 for introducing the roll paper on the path while pulling out the roll paper, a roller 325 for conveying the path on the path toward the conveyance roller 301, and a roller for cutting the roll paper to a predetermined size. A cutter 326 is provided. Further, 321 is a holder for holding the roll paper RP. The recording paper introduced to the transport roller 301 through each path is registered by the registration roller 331.
It is guided to the platen 401 via the sheet and is further sandwiched by the transport roller 341 on the downstream side of the platen 401 in the transport path P. Then, the recording paper is attracted to the platen by a mechanism (not shown) such as air suction.

After that, the carriage moves 1 on the guide rail.
The recording head makes a reciprocating movement, which causes the recording head to scan the recording paper. A drive signal for the head is sent from the control system in synchronization with this scanning, and ink is ejected accordingly.
When an image for one line is formed on the recording paper in this way, the recording paper is conveyed by a predetermined amount by the conveyance roller 341, and the recording head is scanned again. When the above operation is performed for a predetermined image length, the recording paper is sent out by the transport roller 341 and is discharged from the paper discharge port 11.

FIG. 3 shows the configuration of the recording system and the recording system transport system. 201 and 203 are respectively the recording head unit 10
1 is an ink carriage containing a carriage and an ink tank, and is moved and scanned along a guide rail 221. 219A and 219B are pulleys 207A, respectively
And idler 208A and pulley 207B and idler
The wires are erected between 208B and, and are fixed to the carriage and the ink carriage, respectively. Motor 210A
The motor 210B is coupled to the pulleys 207A and 207B, respectively, and the rotation of these drives scans each carriage. The head and the ink tank are connected via an ink supply pipe 103, and ink is supplied through this. 230
Is a signal cable for transmitting an output signal for driving the head to the head side, and one end thereof is connected to a control system (not shown) fixed to the body side.

Here, since the ink ejection performance of the recording head largely depends on the temperature of the recording head, it is necessary to provide a heater or a cooling fan in or around the recording head. Wiring is also included in the above cable. The cable coming out of the control system extends parallel to the guide rail, makes a U-turn, and is guided to the opening 203A of the ink carriage 203. Here, a guide 230G made of a metal leaf spring material is provided along the inner side of the bend of the cable, which serves to assist the waist of the cable and prevent it from buckling during reciprocation. The main body side of the cable and the guide are fixed by the fixing member 231, and the ink carriage side is fixed by another fixing member (not shown). The cable 230 is once fixed to the ink carriage by the another fixing member and then goes out through another opening (not shown). Then, it enters the carriage 201 and is connected to the head driver. The head driver drives the recording head in response to a signal from this cable and ejects ink to form a predetermined image.

Reference numerals 211 and 212 are sensors for detecting home positions of the carriage and the ink carriage, respectively. For example, at this position, a mechanism (not shown) for capping the head is provided in order to prevent the ink from evaporating from the nozzles of the recording head. 213 and 214
Are reversal position sensors that set reversal positions in the scanning direction of each carriage when the head is repeatedly scanned on the recording paper PP to perform continuous recording. Reference numeral 215 is an image leading edge sensor for determining the timing to start recording on the recording paper.

In this embodiment, the head carriage side and the ink carriage side move almost the same, and the distance between them does not change relatively. Therefore, during normal movement, the ink supply tube 103
Also, the situation in which the cable 230, which will be described later, is pulled and disconnected does not occur. However, even if the two carriages try to separate from each other for some reason, for example, when an abnormal external force is applied or the device malfunctions, the wire 218 is configured so that they do not separate from each other by more than a certain amount so that the tubes are not affected. ing.

Next, the structure around the head unit 101 and its operation will be described. The structure is shown in FIG. In this configuration, a plurality of recording heads are vertically arranged in the ejection port array direction so that the recording width in one scanning is as wide as possible to shorten the recording time. Actually, four heads having a recording width W1 are arranged in a staggered manner in the head holder 102 in the sub-scanning direction. As a result, each head 101A, 101B, 10
The recording areas of 1C and 101D can be connected without a gap, and can be regarded as a long head having a recording width W (= W1x4) as a whole. Further, in the present invention, in order to improve the gradation, one pixel is represented by three ink dots, and all the three ink dots have different ejection nozzles. Therefore, the recording width W is divided into three,
Blocks B1, B2, B3 are formed. That is, the first head 10
All 1A nozzles and the lower 1/3 nozzle of the second head 101B are in block B1, the upper 2/3 nozzles of the second head 101B and the lower 2/3 nozzles of the 3101C head are in block B2, and the third head 101C
Block 1/3 of upper part of 1/3 and all nozzles of 4th head 101D
To, respectively. The nozzle length of this block is Ls
(Ls = W / 3).

Then, as shown in FIG. 5, a scan
In (A), using ink from the nozzle of block B1
Record 1/3 of the image. In the next scan (B), the nozzle of block B2 prints the next 1/3 image with a slight shift within one pixel. Further, in the next scan (C), the nozzle of block B3 prints the next 1/3 image with a slight shift in one pixel. As a result, it is possible to express with two to four values per pixel, which is the same as the conventional one, and even if there is a defect in ink ejection to a specific nozzle, overwriting is performed with different nozzles, so the effect is reduced to 1/3. There is an advantage that Here, the volume of the ink ejected from the nozzle at one time is about 10 pl, which is about 1/1 of the conventional volume.
It corresponds to 3. Hereinafter, a method in which images are superposed by repeating scanning a plurality of times in this way is called multi-scan, and a method in which an image is recorded by only one scan is called single scan.

Next, the electrical control and operation in this embodiment will be described. FIG. 6 shows a block diagram. In FIG. 6, reference numeral 804 denotes a control unit, which is composed of a microprocessor (not shown), a program storage ROM, a work RAM, an I / O port, etc., and controls the mechanical drive unit 803 of the entire printer and controls related to printing. Further, the printer device of this embodiment has a control circuit of a general-purpose parallel interface such as IEEE488, a so-called GPIB interface, and receives image data from an external computer or the like (not shown) and prints it out. Of FIG.
802 is the interface control unit, and 805 is a buffer memory for storing image data. The control unit 804 also performs these controls.

An operation unit 801 is operated by an operator to instruct remote control of the apparatus and instructions for sucking / discharging paper sheets online, and is controlled by the control unit 804.
The synchronous delay memories 806 to 809 are for absorbing the time variation of the mechanical operation at the time of image printing and recording heads 101A, 101B, 101C and 101D.
The delay is corrected by the arrangement on the mechanism. The read / write control unit 810 is a control circuit for reading image data from the buffer memory 805 and writing it in the synchronous delay memories 806 to 809 in accordance with the multi-scan method in this embodiment described later. The read / write control unit 810 supplies image data to the head drivers 811 to 814 in synchronization with the mechanical operation. The head drivers 811 to 814 are driver units that drive the recording heads 101A to 101D, respectively.

Next, the actual recording sequence will be described with reference to FIG. Reference numerals 101A to 101D schematically show the four heads used in this embodiment, and the respective heads are arranged in a staggered pattern. 25 for each recording head
It is composed of 5 nozzles, and a total of 1020 nozzles are printed by one scan. On the other hand, the feed amount of the recording paper in the sub-operation direction is
It is equivalent to 340 nozzles (1020/3). That is, the final image is obtained by scanning the same region of each block of B1, B2, and B3 three times.

For example, when forming an image of the area 908 in FIG. 7, the first scan is first performed by the nozzles of the block B1. Subsequently, printing for 340 nozzles is fed in the sub-scanning direction and printing is performed by the nozzles of block B2 so that the second scan overlaps the area 908. Similarly, the third scan is printed by the nozzles of the block B3, and a four-valued multivalued image is formed. At this time, it goes without saying that the other blocks simultaneously form the image for the next scan.

Next, description will be made with reference to FIG. 8 to 8
Are the four recording heads arranged in a zigzag pattern.
Each nozzle number is described as a continuous number from 1 to 1020 for convenience of explanation. Reference numeral 1008 is a diagram schematically showing a recorded image for one line for each pixel for explanation. The same figure shows the density data of each image. Since the multi-scan of the present embodiment expresses by four values, one pixel is scanned three times and one scan is performed once, as described above. In the first scan, the block B1 is used to record an image of 340 lines. Line 1008 is block B in the first scan
No. 1020 nozzle (1007) of the first recording head 101A records the first value. When the first scan is completed, the recording paper is fed in the sub-scanning direction by a predetermined amount. Then, the second scan is started, but in the second scan, the 680th nozzle (100
By 6), the second value of 1008 line is recorded. Similarly, in the third scan, the third value of the 1008th line is printed by the 340th nozzle (1005) of the printhead 101C in the block B3.

Of the 1008 lines, the first pixel indicated by 1011 has a density of image data of 3 and ink is ejected three times, so blocks B1, B2 and B3 are used. Since the second pixel indicated by 1012 has a density of 2, blocks B1 and B
Two blocks are selected from 2 and B3 and used. Since the third pixel shown by 1013 has a density of 3, blocks B1, B2, and B3 are used. 4th pixel shown by 1014,
The fifth pixel indicated by 1015 and the sixth pixel indicated by 1016 have a density of 1
Therefore, one block is selected from the blocks B1, B2, and B3 to be used. Recording is performed in the same manner thereafter.

Next, FIG. 1 shows the actual recording operation of the head, which is divided into several stages as described below. (A) First, in the first scan, the image thinned to 1/3 by the nozzle of block B1 is recorded. (B) Next, the recording paper is stepwise advanced by Ls, and a 1/3 image is further superimposed on the previously recorded image by the nozzle of block B2. At the same time, 1/3 of the next image by block B1
To record. (C) The chart paper is moved further by Ls, and the previous block B2
The last 1/3 of the image is overlaid on the image recorded in step B3. At the same time, block as in (B)
Images of 1/3 of each are recorded in B2 and block B1. Of these, the part recorded in block B3 is the completed image.

The following operation (C) is repeated from the last to the scan two times before. And block on next scan
Recording is performed by B2 and block B3, and by the last scan, recording is performed only by block B3. With the above, recording of all images is completed. By performing the recording operation by the above-described method, the gradation is improved without lowering the resolution, and the recording time is not so different from the case of the binary recording with one head having the nozzle length W1. In addition, this method has the following advantages. Even if ejection failure occurs in a certain nozzle, white spots do not occur if the other two nozzles that perform printing on the same pixel are normal, and even if that portion has uneven image density, it is almost noticeable. Absent.

Further, the present invention has an effect that even if the image density unevenness in one head occurs, it is not noticeable in the image. This will be described with reference to the schematic diagram shown in FIG. Generally, in an ink jet recording head that ejects ink by thermal energy, the temperature of the head has a great influence on the ejection performance as described above, and it is desirable to keep all nozzles at a uniform temperature. For that reason, a heater is provided outside to constantly adjust the temperature during operation. However, it is difficult for any adjusting mechanism to make it uniform, and a temperature gradient occurs. In particular, the nozzle temperature tends to decrease toward the end, and as a result, for example, an ink density gradient D as shown in FIG. 9A is likely to occur in the vertical direction of the head 101A.

Therefore, for example, when images are overwritten, if the same nozzles of the same head are overlaid, or end nozzles of different heads are overlaid, for example, the same nozzle of the same head is overwritten three times. if you did this,
As shown in FIG. 9B, the image is recorded in a form (DS ') in which the ink density gradient is further emphasized.

Therefore, in order to deal with it, it is possible to intentionally perform a correction such that the image density at the end portion is increased when performing image processing. However, it is difficult to predict the correction amount, and it is almost impossible to achieve a completely uniform density in any image. On the other hand, in the case of the present invention,
As shown in FIG. 9C, if the density distributions of the blocks to be overlapped are D1, D2, and D3, respectively, the overlapping results DS tend to be more uniform, and the image density unevenness becomes less noticeable. Therefore, it is possible to omit special image processing for the end portion, and it is possible to simplify electrically. Here, the density unevenness described above is not limited to the one due to the temperature gradient, but it is possible to make it uniform by the present invention as long as it is a regular one similar to each head that occurs due to some other common factor. is there.

In addition, there are the following merits when the head is replaced. For example, when the nozzle position of the head after replacement is slightly different from that before replacement because there is variation in the nozzle molding position depending on the head, or when the position reproducibility of the head is incomplete, it is not It is conceivable that the space corresponding to the head connection portion of the image appears as a difference in density due to the change in the space. However, in the present invention, since images from other regular nozzle positions are superposed on it, they do not appear so conspicuously on the image as compared with the case of single scan.

As described above in detail, according to the present invention, in order to improve the image quality of a recorded image without extending the recording time, the cost of the head is reduced as compared with the case of using one long head, and The reliability can be improved.
Further, regarding the non-ejection of nozzles and the unevenness of the ink density of the ink ejected from the head, which are problems peculiar to the inkjet recording apparatus, it is possible to suppress the unevenness on the image caused thereby due to almost no concern. Furthermore, when the print head is replaced with respect to the head holder, the influence on the image should be minimized even if the relative position with other print heads changes due to the insertion operation of the print head. You can Further, because of this, it is not necessary to use nerves excessively when exchanging the head, and the exchanging operation can be easily performed.

(Second Embodiment) In the first embodiment, a method called multi-scan in which four heads are used to perform overwriting three times has been described. Therefore, as Example 2,
A method of performing two-time multi-scan using three heads will be described. The method according to the second embodiment is particularly effective when not only aiming at high image quality as in the first embodiment, but more importance is given to downsizing of the apparatus and high reliability of the head.

FIG. 10A shows the structure around the head.
Along with that, it will be described below. In this embodiment, the three recording heads 501A, 501B, 501C are tilted with respect to the sub-scanning direction and are arranged in the head holder 502 in the ejection port array direction in order to increase the recording width in one scanning. There is. The reason for arranging them in a tilted manner is to eliminate the connection of recording areas between the heads and to save the space around the heads as much as possible. Next, all nozzles are divided into two and they are represented as B4 and B5. That is, the multi-scan is performed twice to form an image by superposing the inks of the two blocks, and the image can be represented by three values. Although slightly inferior to the 4-value, this method can also sufficiently improve the image quality as compared with the conventional method. The rest of the configuration of the apparatus is the same as that of the recording apparatus of the first embodiment, and the description thereof is omitted. Further, although the part of the multi-valued process of the image signal and the part of the head drive timing correction of the electrical process are slightly different from those of the first embodiment,
Since the basic structure does not change, the description is omitted.

In the recording operation, among the operation steps described in the first embodiment, the steps shown in FIGS. 1A and 1B are common, and thereafter, (B) is repeated. Then, the last one line is recorded only in the block B5, and the recording operation is completed. Here, the step feed amount of the recording paper is W / 2. Also, the volume of ink ejected from the ejection port once is about half that of the conventional ink.
FIG. 10B shows a schematic diagram in the case where the ink density unevenness in the head occurs in this embodiment. In FIG. 10B, D1 is the ink density gradient in the case of block B4, and D2 is the ink density gradient in the case of block B5. Also in this example, as a result of D1 and D2 being superposed, the density gradient of the ink becomes like DS, the unevenness is made uniform as in the case of the first embodiment, and a good image with less uneven density can be obtained. As described above, the second embodiment has the following advantages.

Although it is slightly inferior to the 4-value, it is possible to sufficiently improve the image quality as compared with the conventional one. Also, the recording time is about 70% of the time when the binary recording is performed by one head, and when all the heads used are the same, the recording time is slightly shortened as compared with the first embodiment. Further, another difference when compared with the first embodiment is that the number of heads is three. This reduces the cost of the head and also reduces the failure rate, which improves reliability. Moreover, since the space of the head portion can be reduced, the device size can be reduced.

(Third Embodiment) In the first embodiment, a method has been described in which four heads are used to divide the entire ejection opening array into three blocks for recording, but as another embodiment, one printing is performed. Printing can be performed by forming one block by using all the ejection ports of the recording head, or by forming one block by using all the ejection ports of a plurality of recording heads. For example, four recording heads are used, the number of blocks is two, and the number of main scans for the same pixel is two. That is, the first recording head and the second recording head form the first block, and the third recording head and the fourth recording head form the second block. This is Example 3. Note that, as in the first and second embodiments, a recording means in which a plurality of recording heads having ejection openings for ejecting ink on the recording medium are arranged in the ejection opening array direction is used.

According to the third embodiment, the effect of the first and second embodiments can be obtained in that the influence on the recorded image is reduced when the image density unevenness due to the position of the ejection port in the ejection port array occurs. However, since multi-value recording is possible, gradation is improved as compared with single scanning. Further, in one print head, the blocks to which the ejection ports belong do not differ, and since image processing can be performed in print head units, there is the advantage of electrical simplification. Furthermore, since the recording heads with short ejection port arrays are combined, manufacturing is easy and reliability is high. In addition, since the print heads can be replaced for each print head, it is possible to obtain the effect of reducing waste.

In the above description of the embodiment, the case where one set of recording heads is used has been described, but the present invention is not limited to this, and a plurality of sets of head rows are arranged in parallel, and inks of different colors are supplied from each set. Similar effects can be obtained even in a device that forms a full-color image by discharging. Further, although the case where paper is used as the recording medium has been described, the present invention is not limited to this and can be applied to any material, such as a plastic film or a cloth material, as long as it can be recorded by the inkjet method.

The present invention provides excellent effects particularly in an ink jet recording method and recording apparatus in which flying droplets are formed by utilizing thermal energy among ink jet recording methods.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal transducer arranged corresponding to the sheet or liquid path in which is stored, a rapid temperature increase corresponding to the recorded information and exceeding nucleate boiling is applied. , It is effective because it generates heat energy in the electrothermal converter and causes film boiling on the heat-acting surface of the recording head, resulting in the formation of bubbles in the liquid (ink) corresponding to this drive signal one-to-one. Is. Liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. A configuration using US Pat. No. 4,558,333 or US Pat. No. 4,459,600, which discloses a configuration in which the heat acting portion is arranged in the bending region, may be used. In addition, Japanese Unexamined Patent Application Publication No. Sho 5-5 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters.
Japanese Patent Application Laid-Open No. 9-123670 and Japanese Patent Application Laid-Open No. Sho 5 (1993) -58
A configuration based on Japanese Patent Publication No. 9-138461 may also be used.

In addition, by being attached to the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. Alternatively, a cartridge type recording head provided with an ink tank may be used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a constitution of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. If these are specifically mentioned,
Capping means, cleaning means, pressurizing or sucking means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording It is also effective to perform stable recording.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrally formed or a plurality of combinations may be used. Alternatively, the device may be provided with at least one of full colors by color mixing.

In the embodiments of the present invention described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and softens at room temperature, or is a liquid, or the above-mentioned. In the inkjet 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. Any liquid may be used.

In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in a standing state for the purpose of preventing evaporation of the ink. In some cases, whether ink is used, the ink is liquefied by application of thermal energy according to the recording signal and is ejected as a liquid ink, or the one that has already started to solidify when it reaches the recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A No. 60-71260, a mode in which it faces the electrothermal converter in a state of being held as a liquid or solid in the recess or through hole of the porous sheet. 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.

Further, as a form of the recording apparatus according to the present invention, the recording apparatus according to the present invention is integrally or separately provided as an image output terminal of the information processing equipment such as the word processor or the computer, and is combined with a reader or the like. It may be in the form of a copying machine or a facsimile machine having a transmission / reception function.

[0062]

As described above, according to the present invention, the following effects can be obtained. 1) It is possible to improve the gradation of an image without extending the recording time and maintaining the resolution.

2) Without increasing the cost of the recording means
Moreover, it does not impair its reliability.

3) Even if non-ejection or unevenness of ink density occurs at a particular ejection port, it is possible to reduce the influence on the recorded image and maintain good image quality.

4) It is possible to suppress the influence on the image quality even with respect to the displacement of the ejection port, which is likely to occur when the recording head is replaced. At the same time, it is easy to replace the recording head.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a recording operation of a recording head according to a first embodiment of the invention.

FIG. 2 is a cross-sectional view of the inkjet recording apparatus of the present invention.

FIG. 3 is a configuration diagram of a recording system and a recording system unit transport system of the inkjet recording apparatus of the present invention.

FIG. 4 is a configuration diagram around a recording head in a first embodiment of the invention.

FIG. 5 is an illustration of ink superposition in the first embodiment of the present invention.

FIG. 6 is an electrical control block diagram in the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of a recording method according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a one-line recording method according to the first embodiment of the present invention.

FIG. 9 is a schematic diagram illustrating an effect relating to image density unevenness of the present invention.

FIG. 10 is a configuration diagram showing a configuration around a recording head in a second embodiment of the present invention.

[Explanation of symbols]

 100 Recording system 101A, 101B, 101C, 101D, 501A, 501B, 501C Recording head 102, 502 Head holder 200 Recording system unit transport system 300 Recording paper transport system 804 Control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B41J 2/51 H04N 1/034 9070-5C 1/23 101 B 9186-5C 9012-2C B41J 3 / 04 104 D 9211-2C 3/10 101 E

Claims (10)

[Claims] 1. A recording means, in which a plurality of ejection port arrays in which a plurality of ejection ports for ejecting ink onto a recording medium are arrayed, are arranged in the ejection port array direction in a direction different from the ejection port array direction. Main scanning means for relatively performing a main scan relative to the recording medium; and for each main scanning, the recording means and the recording medium are relatively moved by an amount smaller than the entire length of the plurality of ejection port arrays. A sub-scanning unit for performing sub-scanning in the ejection port array direction, among all the ejection ports of the plurality of ejection port arrays divided into a plurality of blocks in the ejection port array direction, and among the ejection ports located at both ends of the block. At least one of the blocks is not a discharge port at the end of the discharge port array, and a discharge control unit that discharges ink from the discharge port of a different block to the same pixel on the recording medium according to the print data at different main scans. Equipped with multiple pixels for one pixel An ink jet recording apparatus characterized by performing recording at times of the main scanning. 2. The ink jet recording apparatus according to claim 1, wherein the recording unit includes a plurality of recording heads each including an ejection port array. 3. The ink jet recording apparatus according to claim 1, wherein each ejection port array of the recording unit is arranged in a direction perpendicular to the main scanning direction. 4. The ink jet recording apparatus according to claim 1, wherein each ejection port array of the recording unit is arranged to be inclined with respect to the main scanning direction. 5. The recording means causes a state change in the ink by thermal energy, and causes the ink to be ejected from an ejection port based on the state change.
The inkjet recording device described. 6. The recording means, for each corresponding ejection port,
The ink jet recording apparatus according to claim 5, further comprising a thermal energy generating unit that causes the ink to change its state due to heat. 7. A recording means having a plurality of ejection port arrays in which a plurality of ejection ports for arranging ink on a recording medium are arrayed and arranged in the ejection port array direction in a direction different from the ejection port array direction. Ink is ejected onto the recording medium while performing main scanning relatively to the recording medium, and the recording unit and the recording target are recorded by an amount smaller than the entire length of the plurality of ejection port arrays for each main scanning. An inkjet recording method for performing recording by sub-scanning a medium relative to the ejection port array direction, wherein recording is performed by the main scanning a plurality of times on the same pixel on a recording medium according to recording data. In this case, the ink jet recording method is characterized in that the recording for the same pixel is not performed using the ejection ports at two or more ends of the ejection port array. 8. A recording means in which a plurality of recording heads having ejection openings for ejecting ink onto a recording medium are arranged in the ejection opening row direction is recorded in a direction different from the ejection opening row direction. Main scanning means for relatively performing main scanning with respect to the medium; and for each main scanning, the recording means and the recording medium are relatively ejected by an amount smaller than the entire length of the plurality of ejection port arrays. Equipped with sub-scanning means for performing sub-scanning in the direction of the outlet row, and ejection control means for ejecting ink to the same pixel on the recording medium according to the recording data from different ejection ports at different main scanning times. 2. An ink jet recording apparatus, wherein recording is performed by the main scanning. 9. A recording means in which a plurality of recording heads having ejection openings for ejecting ink onto a recording medium are arranged in the ejection opening row direction is recorded in a direction different from the ejection opening row direction. Ink is ejected onto the recording medium while performing main scanning relatively to the medium, and the recording head and the recording medium are ejected for each main scanning by an amount smaller than the entire length of the plurality of ejection port arrays. The inkjet recording method is characterized in that recording is performed by relatively sub-scanning in the direction of the ejection port array. 10. A recorded matter recorded by the inkjet recording method according to claim 9.