JPH05167807A - Method and device for image formation - Google Patents

Abstract

PURPOSE:To record multilevel image data by expressing one picture element is plural dots by controlling dots to be recorded at every scan and the amount of their carrying in a subscan direction. CONSTITUTION:Image data read by a CCD line sensor 26 is written on synchronous memory 110 sequentially after image processing is performed at an input system image processing part 116 and a main processing part 106. Thence, odd-numbered scan on a printer part 20 is started, and image recording of one line is started based on the image data read out from the synchronous memory 110. When the odd-numbered scan is completed, recording paper is carried in the subscan direction by distance equivalent to 1/2 the distance between the nozzles of a recording head 58. Thence, when even-numbered scan is completed, the recording paper is carried in the subscan direction by the distance in which the distance of 1/2 the one between the nozzles is added on the nozzle arranging distance of the recording head 56. Furthermore, one picture element can be expressed in the plural dots by changing data to be recorded in the odd-numbered scan and the even-numbered scan.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming method and apparatus for forming an image by the presence / absence of dots at a predetermined position on a recording medium.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a printer capable of forming an image on a recording medium such as a recording paper by controlling the presence or absence of dots adhered by a coloring material at a predetermined position on the recording medium. There is a device. An example of image formation in such a conventional image forming apparatus will be described below with reference to FIG. In FIG. 18, reference numeral 180 denotes an inkjet head including four ink ejection nozzles 181. Reference numeral 183 denotes pixels recorded by scanning the ink jet head 180 with respect to a paper as a recording medium. In this way, by scanning the inkjet head 180 in the main scanning direction and performing an ink ejection operation controlled by a binary image signal output from an image processing apparatus (not shown), four dots corresponding to the number of nozzles of the inkjet head 180. The width of When the recording operation for one scan is completed, the distance between the nozzles 181 becomes 4 in the sub-scanning direction.
An image having a desired width can be formed on the recording paper by moving the recording paper by a distance equivalent to twice and repeating the recording operation by scanning in the main scanning direction. Here, the image on the recording paper corresponding to one pixel of the binary image signal corresponds to the presence / absence of one dot.

[0003]

As described above, in the above-described conventional example, the binary image signal is used and the value of the image data corresponding to one pixel is made to correspond to the presence or absence of one dot. However, a higher quality image can be obtained. In order to form, it is necessary to record an image based on the multi-valued image signal. In order to form such a multi-valued image, it is conceivable to form image data corresponding to one pixel by the presence or absence of a plurality of adjacent dots. However, when one pixel is formed by a plurality of dots using an inkjet head having a plurality of nozzles arranged at a fixed density, the number of pixels per fixed area on the recording medium decreases. On the other hand, it is possible to increase the arrangement density of the nozzles arranged in the inkjet head, but there is a technical limit to increasing such density, and the cost of the inkjet head increases. was there.

The present invention has been made in view of the above-mentioned conventional example, and multivalued image data can be recorded by changing one recording dot for each scan and the conveyance length of the recording medium to express one pixel by a plurality of dots. An object is to provide an image forming method and apparatus.

[0005]

In order to achieve the above object, the image processing apparatus of the present invention has the following configuration.
That is, an image forming apparatus that forms an image depending on the presence or absence of a color material dot adhering to a predetermined position on a recording medium, and a storage unit that stores multivalued image data in which one pixel is composed of a plurality of dots. Recording means for recording an image by scanning in the main scanning direction based on multi-valued image data stored in the storage means, dots for recording in each main scanning by the recording means, and recording medium in the sub-scanning direction And a control means for controlling the carry amount to control the printing by the printing means.

In order to achieve the above object, the image processing method of the present invention comprises the following steps. That is, it is an image forming method of forming an image by the presence or absence of the adhesion of dots by a coloring material to a predetermined position on a recording medium, and a step of inputting multivalued image data in which one pixel is composed of a plurality of dots, Based on the multi-valued image data, there is a step of controlling the dots to be printed in each scan in the main scanning direction and the carry amount of the printing medium in the sub scanning direction to perform printing.

[0007]

With the above arrangement, when an image is printed by scanning in the main scanning direction based on multi-valued image data, the dots to be printed in each main scanning and the carry amount of the printing medium in the sub scanning direction are controlled. And operate to record.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an external perspective view of the digital color copying machine of this embodiment. This digital color copier
It is roughly divided into two parts, one is a color image scanner section (hereinafter abbreviated as a reader section) 12 for reading a color original image placed on an original table and outputting digital color image data. is there. It should be noted that the reader unit 12 has a built-in controller unit 14 that performs various kinds of image processing of digital color image data and has a processing function such as an interface with an external device. Further, as a second major element, a printer unit 20 is provided below the reader unit 12 for recording color digital image signals output from the controller unit 14 of the reader unit 12 on recording paper. There is.

The reader unit 12 receives image information from originals of various shapes and sizes such as a three-dimensional or sheet-like or large-sized sheet-like original placed on an original table (not shown) below the original pressing plate 16. It also has a built-in reading mechanism. In addition, on one side of the upper surface of the reader unit 12,
An operation unit 18 connected to the controller unit 14 is provided. The operation unit 18 is for inputting various information and operation instructions for the copying machine. Further, the controller unit 14 is configured to give an operation instruction to the reader unit 12 and the printer unit 20 in accordance with information input via the operation unit 18. When it is necessary to perform more complicated editing processing or the like, the document pressing plate 1
A digitizer or the like may be attached instead of 6, and this may be connected to the controller unit 14. This enables more advanced image processing such as designating the position of the original image and performing special processing on the image at that position.

On the other hand, in the printer section 20 of this embodiment, a full-color ink jet printer using an ink jet type recording head as described in JP-A-54-59936 is used. ..

The above-mentioned two main components can be separated from each other, and can be installed at a place separated from each other by extending the connecting cable.

The above-mentioned major elements will be described in detail below.

FIG. 2 is a sectional view schematically showing the internal structure of the digital color copying machine 10 shown in FIG.

First, the digital color copying machine 1 of this embodiment
The configuration of the 0 reader unit 12 will be described.

In the reader unit 12, the exposure lamp 2
2, a lens 24, and an image sensor 26 capable of reading a line image in full color (in this embodiment, C
By using a CD sensor), an image of a color document placed on the platen glass 28, a projected image by a projector,
Alternatively, the image of the sheet-shaped document is read by the sheet feeding mechanism 30. Next, various image processings on the image information read by the reader unit 12 in this way are performed by the reader unit 12 and the controller unit 14, and then the read and image-processed information is sent to the printer unit 20. Then, it is recorded on the recording paper here.

Next, in the printer unit 20, the recording paper is a small-sized fixed size (in this embodiment, A4 size to A3 size) cut paper cassette 32 for storing cut paper, and a large size (in this embodiment, A2 size). It is selectively supplied from the roll paper 34 for recording the size (A1 size to A1 size).
Further, the feeding of the recording paper is started by a print start instruction from the controller unit 14, and is first conveyed to the first feeding roller 44 position through the following path. In the present embodiment, the recording paper is manually inserted along the paper feed unit cover 38.
As shown in FIG. 6, it is also possible to perform manual paper feeding (paper feeding from outside the device) by manually inserting recording paper one by one.

A case where recording paper is fed from the paper feed cassette 32 mounted in the printer unit 20 will be described. A pick-up roller 40 for taking out the cut sheets one by one from the paper feed cassette 32 is provided on the upper surface of the recording paper setting surface of the paper feed cassette 32. Therefore, by rotating the pick-up roller 40, the uppermost recording sheets set in the sheet feeding cassette 32 are taken out one by one and sent to the cut sheet feeding roller 42. Further, thereafter, the fed cut paper is conveyed to the position of the paper feed first roller 44 by the cut paper feed roller 42.

On the other hand, in the case of the roll paper 34, it is continuously sent out by the roll paper feed roller 46, and the cutter 48
Is cut to a standard length by
It is transported to position 4. If the fed recording paper is manually fed from the manual feed port 36, the manually fed recording paper is fed by the manual feed roller 50 to the feeding first roller 4
It is transported to position 4.

Here, the pick-up roller 40, the cut paper feed roller 42, the roll paper feed roller 46, the first paper feed roller 44, and the manual feed roller 50 are a paper feed motor (not shown) (DC in this embodiment). It is driven to rotate by using a servo motor), and an electromagnetic clutch attached to each roller can be used for on / off control of the rotation drive at any time.

The recording paper thus selectively fed from any one of the above-mentioned paper feed paths is conveyed to the position of the first paper feed roller 44. In order to remove the skew (skew) of the recording paper, at the time of this paper feeding, after forming a predetermined amount of paper loop on the recording paper, the paper feeding first roller 44 is rotationally driven, and then the paper feeding second roller 44 is fed. The recording paper is conveyed to the roller 52.

Further, between the first paper feed roller 44 and the second paper feed roller 52, a paper feed roller 64 disposed above the recording head 56 and a paper feed first roller disposed below the recording head 56. In order to perform an accurate paper feeding operation with the two rollers 52, the recording paper is slackened by a predetermined amount to form a buffer. A buffer amount detection sensor 54 for detecting the buffer amount as the slack amount of the recording paper is arranged near this buffer. In this way, by always forming a buffer on the recording paper during paper conveyance,
In particular, it is possible to reduce the load on the paper feed roller 64 and the second paper feed roller 52 when a large-size recording paper is conveyed. This enables an accurate paper feeding operation.

In the printer unit 20 having the recording paper conveying system as described above, when printing is performed by the recording head 56, the scanning motor 62 is mounted on the scanning carriage rail 60 on which the recording head 56 is mounted. Thus, the recording head 56 is reciprocally moved in the front and back directions in the drawing to scan the recording paper in the main scanning direction. Then, in the forward scan, an image is printed on the recording paper by the recording head 56, and in the backward scan, the paper feed roller 64 performs a paper feed operation in the sub-scanning direction in which the recording paper is fed by a predetermined amount.

Here, the feed amount of the recording paper along the sub-scanning direction is set to the feed amount equal to one half of the distance between the nozzles of the print head 56 in the odd scan of the print head 56. , 256 of the recording head 56 in the even scan
It is set to a length corresponding to an amount obtained by adding 1/2 of the distance between nozzles of the recording head 56 to the arrangement width of the nozzles of the book.

FIG. 12 is a diagram showing the movement amount of the recording paper in the sub-scanning direction. The recording head 56 has 256 nozzles, and when moving from the N scan position to the (N + 1) scan position, the recording paper is conveyed by 1/2 of the nozzle interval. Further, when moving from the (N + 1) scan position to the (N + 2) scan position, the recording paper is equal to the arrangement length of 256 nozzles plus one half of the distance between the nozzles of the recording head 56. It is moved in the sub scanning direction. Although not shown here, the recording head 5 of the platen 74
Suction holes are formed over the opposing surface portions of 6.
These suction holes are for bringing the recording paper into close contact with the platen 74.

Further, during the drive control of the recording paper by the scanning motor 62 during the backward scan of the recording head 56, the buffer amount detection sensor 54 detects the buffer amount so that a predetermined buffer amount is always held. Is controlled by. The recording paper thus printed is discharged onto the paper discharge tray 66, and the series of printing operations described above is completed.

Next, referring to FIG. 3, the scanning carriage 58
The configuration around the will be described in detail.

In FIG. 3, reference numeral 68 is a paper feed motor as a drive source for intermittently feeding the recording paper in the sub-scanning direction. The paper feed motor 68 is capable of setting and changing the amount of rotation of the paper feed motor 68.
Also, the second sheet feeding roller 52 is driven via the second sheet feeding roller clutch 70. The above-mentioned scanning motor 62 is provided as a drive source for reciprocally scanning the scanning carriage 58 along the main scanning direction indicated by the arrows A and B via the scanning belt 72.

In this embodiment, a paper pressing member (not shown) is arranged at a position opposite to the lower end of the platen 74, and the paper pressing member fixes the recording paper to the platen during scanning of the scanning carriage 56. By doing so, the movement of the recording paper is controlled so as not to occur. When the recording paper reaches the position of the second paper feed roller 52, the second paper feed roller clutch 70 and the paper feed motor 68 are turned on, and the leading end of the recording paper is held by the pair of paper feed rollers 64. Up to the platen 74. Then, the conveyed recording paper is detected by the paper detection sensor 76 provided on the platen 74 after passing through the platen 74. Information from the sensor 76 is used for recording paper position control, jam control, and the like.

When the leading edge of the recording paper reaches the paper feed roller 64, the second feeding roller clutch 70 and the paper feed motor 6
8 is turned off, and then the inner space of the platen 74 is made a negative pressure by the activation of a suction motor (not shown), and the suction operation is started. By such suction operation, the recording paper is brought into close contact with the platen 74. At the same time, the above-mentioned paper pressing member also fixes the recording paper to the platen.

Here, prior to the image printing operation on the recording paper, the scanning carriage 58 is moved to the position where the home position sensor 78 is arranged, and then the forward scanning is performed in the direction of arrow A. Be done.

In this forward scan, cyan "C", magenta "M", yellow "Y", and black "K" inks are appropriately ejected from the recording head 56 from a predetermined position, and along the main scanning direction. When the image recording operation for a predetermined length is completed, the rotation direction of the scanning motor 62 is reversed and the scanning carriage 58 is moved in the reverse direction, that is, in the direction shown by the arrow B, to start the backward scanning. During this backward scan,
The scanning motor 62 is reversely driven until the scanning carriage 58 returns to the position where the home position sensor 78 is provided.

During the backward scan of the scanning carriage 58, the paper feed motor 68 is activated to drive the paper feed roller 64.
Is driven to rotate in the sub-scanning direction indicated by arrow C, a paper feed amount equal to ½ of the nozzle-to-nozzle distance of the recording head 56 in the odd scan, and an even scan in the sub scan direction.
The paper feed operation is performed by an amount corresponding to the amount obtained by adding 1/2 of the distance between the nozzles of the recording head 56 to the arrangement width of the 256 nozzles of the recording head 56.

In the present embodiment, in addition to the above-described movement amount, the odd-numbered scan may be set to the one-sided movement amount defined by the line width. In this embodiment, the recording head 56 is an ink jet nozzle, and a total of 256 nozzles are arranged for each color of YMCK.

When the scanning carriage 58 stops at the home position defined by the home position sensor 78, the recovery operation of the recording head 56 is performed.
This recovery operation is a process for performing a stable recording operation, and is a process for preventing unevenness at the start of ejection which is caused by a change in the viscosity of the ink remaining in the nozzles of the recording head 56. In this process, pressurizing operation is performed on each nozzle of the recording head 56 according to pre-programmed conditions such as a sheet feeding time, a temperature inside the apparatus, and an ejection time, and an idle ejection operation of ink is performed from each nozzle. By repeating the operation described above, desired image recording is performed over the entire surface of the recording paper.

Next, the digital color copying machine 1 of this embodiment
The processing and control of the image signal of the control system in 0 will be described with reference to the block diagram of FIG.

In FIG. 4, reference numeral 100 indicates a main CPU which controls the entire apparatus.
A printer control CP 00 controls the printer control operation.
U102, reader control CPU 10 that controls the reading control operation
4, the main image processing unit 106 for processing the image display operation,
An operation unit 108 as an input unit for the operator is connected. Here, the printer control CPU 102 and the reader control CPU 104 respectively control the operation of the printer unit and the reader unit, and are set in a master-slave relationship with the main CPU 100.

The main image processing unit 106 described above performs image processing such as edge enhancement smoothing, masking, black extraction, quinarization, and trimming. Also, printer control C
The synchronous memory 1 is provided in the PU 102 and the main image processing unit 106.
10 are connected. This synchronous memory 110 holds the image data from the main image processing unit 106,
Image data required for each even-numbered scan, absorption of temporal variations in input operation, delay correction due to mechanical arrangement of the recording heads 56, and the like are performed. The output of the synchronous memory 110 is connected to the recording head 56.

The printer control CPU 102 controls a printer unit drive system 114 for controlling the input drive of the printer unit 20.
It is connected to the. In addition, the reader control CPU 104
It is connected to an input system image processing unit 116 that performs necessary correction processing in the reading system such as shading correction, color correction, and γ correction, and a reader unit drive system 118 that controls input driving of the reader. Further, a CCD line sensor 120 is connected to the input system image processing unit 116, and the input system image processing unit 116 is connected to the main image processing unit 106. In this way, the reader unit 12 is connected to the main CP.
U100, reader control CPU 104, main image processing unit 106, operation unit 108, input system image processing unit 116, reader unit drive system 118, and CCD as an image sensor
The line sensor 26 and the like are provided.

Further, the printer section 20 has a printer control C.
The PU 102, the synchronous memory 110, the recording head 56, the printer unit drive system 114, and the like are provided.

Next, the structure of a characteristic part of the synchronous memory 110 in this embodiment will be described with reference to FIG.

FIG. 5 is a block diagram showing the structure of the synchronous memory 110.

In FIG. 5, reference numeral 121 denotes a buffer memory, which is configured to store 1 bit at 1 address. In this way, the image data necessary for each of the odd-numbered and even-numbered two scans can be held and stored in bit units. A write address counter 122 is used for writing the input image data in the buffer memory 1
21 addresses are designated. Reference numeral 123 denotes a read counter, which specifies the address of the image data to be read when reading the image data from the buffer memory 121. Each of the write counter 122 and the read counter 123 can be independently controlled by the control logic 124. The image clock and control signals in FIG. 5 are input from the main image processing unit 106.

The image data from the main image processing unit 106 is incremented by 1 in increments of the write counter 122 by the image clock, and as shown in FIG. Written in. Each number in FIG. 6 indicates an address of the buffer memory 121, a number input to the buffer memory 12 indicates a write address, and an arrow output from the buffer memory 121 indicates a read address. As described above, the data writing to the buffer memory 121 is performed in the odd scan, and the image data written in the buffer memory 121 is read in the read counter 123 in the odd scan by 4n + 1, 4n + 2.
By counting such as (n = 0, 1, 2, 3, ...), the image data is read as shown in FIG. On the other hand, in the even scan, the read counter 1
23 is 4n + 3, 4n + 4 (n = 0, 1, 2, 3, ...)
By counting in this way, the image data is read from the buffer memory 121 as shown in FIG.

Next, the main CPU 10 in the present embodiment.
0, printer control CPU 102, reader control CPU 10
7 shows details of the copy sequence executed in FIG.
This will be described below with reference to the flowchart shown in FIG.

First, when a start key (not shown) in the operation unit 108 is pressed, a copy sequence task program is called from a program memory (not shown),
The main CPU 100 advances the process to step S1 in FIG.

In step S1, the copy area is set according to the data such as the document size, the main scanning direction scaling factor, the sub scanning direction scaling factor, and the paper size set by the operation unit 108. Next, in step S2, the data necessary for the initial setting is transmitted to the reader control CPU 104, and the reader unit 12 performs the initial setting. When this initial setting is completed, the process proceeds to the next step S3, data necessary for the initial setting is transmitted to the printer control CPU 102, and the printer unit 20 performs the initial setting.

When the above process is completed, the process proceeds to step S4, and when the initial setting such as shading correction and paper feeding in the reader unit 12 and printer unit 20 is completed, the document image data of the original image data is read in the reader unit 12 in step S5. Start reading. The image data thus read is subjected to image processing by the input system image processing unit 116 and the main image processing unit 106, and then the buffer memory 12 of the synchronous memory 110.
Sequentially written to 1. Next, in step S6, the odd number scan of the printer unit 20 is started, and the synchronous memory 11
From the buffer memory 121 of 0, as described above, the read counter 123 is set to 4n + 1, 4n + 2 (n = 0, 1,
The image data is read out by counting operation such as 2, 3, ..., And image recording for one line (odd scan) is started by the read image data.

When the recording operation by the odd number scan is completed in step S7, the process proceeds to step S8, and the recording paper is conveyed in the sub-scanning direction by a distance corresponding to ½ of the distance between the nozzles of the recording head 56. When the conveyance of the recording paper in the sub-scanning direction is completed in step S9, the process proceeds to step S10, and the even scanning in the printer unit 10 is started. At this time, the buffer memory 12 of the synchronous memory 110
1 to 4n + as described above.
3, 4n + 4 (n = 0, 1, 2, 3, ...) Is operated to read the image data and record for one line.

When it is confirmed in step S11 that the recording operation by the even scan has been completed, the process proceeds to step S12, and the distance obtained by adding the half nozzle distance of the head to the 256 nozzle disposition distance of the recording head 56 is added. The recording paper is conveyed in the sub-scanning direction by a distance corresponding to. Next, in step S13, when it is confirmed that the recording paper has been conveyed in the sub-scanning direction, the process advances to step S14 to determine whether copying of the entire area is completed or not based on the size of the document set in the reader unit 12. If the copying of the entire area is not completed, the process returns to step S4 and the above-described processing is repeated. However, if the copying of the entire area is completed, this copy sequence control operation is ended.

Next, details of the five-valued image signal input to the synchronous memory 110 will be described with reference to FIGS.

The image signal read by the CCD sensor 26 is
The input system image processing unit 116 and the main image processing unit 106 perform processes such as A / D conversion, shooting correction, color correction, black extraction, and the like, and then a quinarization process unit performs quinarization process. In this quinarization processing unit, the image data is sorted into five levels according to four preset threshold values,
Encoding is performed according to the 4-bit code shown in FIG.

FIG. 8 is a diagram showing the relationship between the image signal and the image clock which are quinaryized as shown in FIG.

Here, the image data having 4 bits per pixel is recorded according to the procedure described above with reference to FIG. That is, only the upper 2 bits are selected and recorded in the odd scan, and only the lower 2 bits are selected and recorded in the even scan. In the case of FIG. 8, in the odd scan, only the upper 2 bits “01” of the level 3 pixel and the upper 2 bits “10” of the level 1 pixel are selected and output to the recording head 56. On the other hand, in the even scan, only the lower 2 bits “11” of the level 3 pixel and the lower 2 bits “00” of the level 1 pixel are selected and output to the recording head 56 for recording.

FIG. 11 shows each dot printed in this way according to the level of pixel data, and FIG. 10 shows the printing results in the main scanning and sub-scanning directions.

In this way, regarding each pixel, recording based on four dots (2 dots × 2 dots) recorded in a checkerboard pattern can be obtained.

As described above, according to the present embodiment, the amount of movement of the recording paper in the sub-scanning direction is set to ½ of the nozzle distance of the recording head in the odd scan, and 256 in the even number scan. One pixel can be represented by a plurality of dots (multi-valued) by setting the nozzle arrangement width to a distance corresponding to one half of the nozzle-to-nozzle distance and changing the data to be recorded in the even scan and the odd scan. .. Thereby, a high quality image can be formed. <Other Embodiments> Next, other embodiments according to the present invention will be described.
The following is described with reference to the associated drawings.

In the above-mentioned embodiment, the recording is performed so that one pixel is represented by four dots formed by a matrix of 2.times.2 dots by performing the quinarization process. However, similarly to this, N dots.times.N. It is also possible to record (N × N + 1) -valued image data using a matrix of dots (N = 3, 4, 5, ...). Further, here, a dot matrix of N dots × N dots (N = 3, 4, 5, ...) Is used,
It is also possible to form multivalued image data of (N × N) or less.

Further, the arrangement shape of the recorded dots is not limited to the above-mentioned regular matrix, and it may be arranged in, for example, a N × M rectangular matrix shape (N ≠ M). Is.

Next, the quinarization process is performed as described above, and 2
An embodiment in which one pixel is formed by a rectangular matrix of dots × 3 dots will be described with reference to FIG.

In this case, one pixel is recorded by scanning three times. Therefore, 3n scan (n is 0, 1, 2,
3), the distance between one-third of the nozzles of the recording head 56, two-thirds of the distance between nozzles in the (3n + 1) scan, and 256 nozzles in the (3n + 2) scan. The recording paper is fed in the sub-scanning direction by the distance obtained by adding the width to one third of the inter-nozzle distance.

In the 3n scan, the synchronous memory 110 is used.
Of the read counter 123 from the buffer memory 121 of 6n + 1, 6n + 2 (n = 0, 1, 2,
3, ...), and one line is recorded by the image data read from the buffer memory 121. Similarly, in the (3n + 1) scan, the read counter 123 is set to 6n + 3, 6n + 4 (n = 0, 1, 2, 3, 3).
...), (3n + 2) scan, read counter 123
Is counted as 6n + 5, 6n + 6 (n = 0, 1, 2, 3, ...), and one line is recorded by the image data read from the buffer memory 12.

In the other embodiment, the quinaryization processing unit codes each pixel data of the image data into quinary data according to the 6-bit code shown in FIG.

FIG. 14 is a timing chart showing the relationship between the quinary-valued image signal and the image clock.

Here, the image data consisting of 6 bits per pixel is recorded by three scans as described above. That is, only the upper 2 bits are selected and recorded in the 3n scan, only the middle 2 bits are selected in the (3n + 1) scan, and only the lower 2 bits are selected and recorded in the (3n + 2) scan. .. In this way, the recording operation as shown in FIG. 15 is performed. Thus, regarding each pixel, six dots are arranged in a rectangular shape and recorded in a (2 × 3) dot shape.

In the above-described embodiment, the paper is fed in the sub-scanning direction so that the lines are arranged at equal intervals in the sub-scanning direction, but the present invention is not limited to this case. This is shown in FIG. 17, which shows an example of printing when the paper feed distance in 3n scan and (3n + 1) scan is set to one third or less of the nozzle-to-nozzle distance of the print head.

The present invention brings excellent effects particularly in an ink jet type recording head and a recording apparatus for recording by forming flying droplets by utilizing thermal energy among the ink jet recording systems.

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 converter arranged corresponding to the sheet or liquid path in which the liquid crystal is held, which corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling. Since heat energy is generated in the electrothermal converter to cause film boiling on the heat acting surface of the recording head, air bubbles in the liquid (ink) corresponding to this drive signal in a one-to-one correspondence can be formed. It is valid. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. When the drive signal is pulsed, growth and contraction of the bubbles are immediately and appropriately performed, so that it is possible to achieve ejection of the liquid (ink) with excellent responsiveness, which is more preferable.

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, 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 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 surface is arranged in a 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.

Further, a full line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus is a combination of a plurality of recording heads as disclosed in the above specification. Either of the structure satisfying the requirement or the structure as one recording head integrally formed may 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 configuration of the recording apparatus of the present invention, because the effect of the present invention can be further stabilized. .. Specific examples thereof include capping means, cleaning means, pressurizing or suctioning means for the recording head, preheating means using an electrothermal converter or a heating element other than this, or a combination thereof, and recording. It is also effective to perform stable recording by performing a preliminary discharge mode in which another discharge is performed.

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-color mixed colors.

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, it is common to adjust the temperature of the ink itself within a range of 30 ° C to 70 ° C to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It is sufficient that the ink is liquid.

In addition, the temperature rise due to thermal energy is positively prevented by being used as 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, it is integrally or separately provided as an image output terminal of a copying apparatus combined with a reader or the like as described above, an information processing apparatus such as a word processor or a computer. Other than the above, it may take the form of a facsimile machine having a transmission / reception function.

In this embodiment, the digital color copying machine is taken as an example, and the image signal is inputted from the reader section such as a scanner, but the present invention is not limited to this, and I / O from an external device is used. It can also be applied to a system for forming an image by processing an image input via F.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program for implementing the present invention to a system or an apparatus.

As described above, according to this embodiment, it is possible to increase the density of the nozzles arranged on the recording head without increasing the density.
It is possible to record one pixel with multiple dots. Thus, there is an effect that a high-quality image can be formed.

[0081]

As described above, according to the present invention, by changing the print dot and the transport length of the print medium for each scan,
There is an effect that one pixel is expressed by a plurality of dots and multivalued image data can be recorded.

[Brief description of drawings]

FIG. 1 is an external perspective view of a digital color copying machine according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing the internal structure of the digital color copying machine of this embodiment.

FIG. 3 is a diagram showing a configuration around a scanning carriage in the digital color copying machine of the embodiment.

FIG. 4 is a block diagram showing a schematic configuration of a control system of the digital color copying machine of the embodiment.

FIG. 5 is a block diagram showing the configuration of a synchronous memory of the printer unit of the digital color copying machine of the embodiment.

FIG. 6 is a diagram showing write and read addresses to a buffer memory of a synchronous memory.

FIG. 7 is a flowchart showing a copy sequence in the digital color copying machine of the embodiment.

FIG. 8 is a timing diagram showing a relationship between a penta-valued image signal and an image clock.

[Fig. 9] Fig. 9 is a diagram illustrating a 4-bit code that has been converted into a five-value code.

FIG. 10 is a diagram showing a recording example of image data when recording 1 pixel with 4 dots.

FIG. 11 is a diagram for explaining the density level of each pixel recorded as shown in FIG.

FIG. 12 is a diagram showing the feed length of the recording sheet in the sub-scanning direction for each scan of the recording head in the printer unit of the present embodiment.

FIG. 13 is a diagram showing a 5-bit coded 6-bit code according to another embodiment of the present invention.

FIG. 14 is a diagram showing timings of a five-valued image signal and an image clock in another embodiment.

FIG. 15 is a diagram for explaining each pixel of image data recorded in another example and a recording order thereof.

FIG. 16 corresponds to the code shown in FIG.
It is a figure which shows the example which quantizes 3 dots and records them.

FIG. 17 is a diagram showing the order of printing with one pixel of 2 × 3 dots corresponding to each scan.

FIG. 18 is a diagram showing a conventional recording example of each dot in the main scanning direction and the sub scanning direction.

[Explanation of symbols]

 10 digital color copying machine 12 reader section 20 printer section 26 image sensor (CCD) 56 recording head 62 scanning motor 68 paper feed motor 100 main CPU 102 printer control CPU 106 main image processing section 108 operation section 110 synchronous memory 121 buffer memory 122 writing Counter 123 Read Counter 124 Control Logic

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Claims (5)

[Claims] 1. An image forming method for forming an image according to the presence or absence of dot adhesion by a coloring material to a predetermined position on a recording medium, wherein multi-valued image data in which one pixel is composed of a plurality of dots is input. And a step of performing printing by controlling the dots to be printed for each scan in the main scanning direction and the carry amount of the printing medium in the sub-scanning direction based on the multi-valued image data. Image forming method. 2. An image forming apparatus for forming an image according to the presence or absence of dots adhered by a coloring material to a predetermined position on a recording medium, wherein multi-valued image data in which one pixel is composed of a plurality of dots is stored. Storage means, recording means for recording an image by scanning in the main scanning direction based on the multi-valued image data stored in the storage means, and dots for each main scanning by the recording means and in the sub-scanning direction 2. An image forming apparatus, comprising: a control unit that controls the conveyance amount of the recording medium to control recording by the recording unit. 3. The recording means performs recording by scanning a recording head having a plurality of recording elements in the main scanning direction, and conveys the recording medium in the sub-scanning direction for each recording of the recording head for recording. The image forming apparatus according to claim 2, wherein 4. The image forming apparatus according to claim 3, wherein the recording head is an inkjet recording head that performs recording by ejecting ink. 5. The recording head is a recording head that ejects ink by utilizing thermal energy, and is an ink jet recording head that includes a thermal energy converter for generating thermal energy applied to the ink. The image forming apparatus according to claim 4, which is characterized in that.