JP3176181B2 - Recording apparatus, inkjet recording apparatus, and inkjet recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus, and more particularly to an ink jet recording apparatus and a method for ejecting ink from a recording head for recording.

[0002]

2. Description of the Related Art Recording devices such as printers, copiers, and facsimile machines are configured to record an image composed of dot patterns on a recording material such as paper or a plastic thin plate based on image information. I have.

[0003] The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like according to a recording system. An ink (recording liquid) droplet is ejected and ejected from an ejection port of a recording head, and is adhered to a recording material to perform recording.

[0004] In recent years, a large number of recording apparatuses have been used, and high-speed recording, high resolution, high image quality, low noise, and the like have been required for these recording apparatuses. The above-mentioned ink jet recording apparatus can be cited as a recording apparatus that meets such demands. In this ink jet recording apparatus, recording is performed by discharging ink from a recording head.
Stabilization of the ink ejection amount is required.

[0005] However, although the ink ejection is stabilized on the ink jet recording apparatus side, the quality of the recorded image largely depends on the performance of the recording head alone. Shape of discharge port of print head and electrothermal transducer (discharge heater)
The slight differences that occur during the print head manufacturing process, such as variations in the print quality, affect the amount of ink ejected and the direction of the ejected ink, and cause the image quality to deteriorate as density unevenness of the finally formed image. Will be.

A specific example will be described with reference to FIGS. In FIG. 11A, reference numeral 1101 denotes a multi-head, which is composed of eight multi-nozzles (1102) for simplicity. Reference numeral 1103 denotes an ink droplet ejected by the multi-nozzle 1102. Normally, it is ideal that ink is ejected in a uniform direction with a uniform discharge amount as shown in FIG. If such ejection is performed, dots of uniform size are landed on the paper surface as shown in FIG. 11B, and a uniform image without density unevenness is obtained as a whole. (11-c).

However, actually, as described above, each of the nozzles has a variation, and if the printing is performed in the same manner as described above, as shown in FIG. The size and direction of the ink drops ejected from the nozzles vary, and the ink drops land on the paper surface as shown by 12-b. According to this figure,
Area factor 1 periodically in the head main scanning direction
There is a blank portion that does not satisfy 00%, conversely, dots overlap more than necessary, or a white streak as shown in the center of the figure occurs. The collection of dots landed in such a state has a density distribution shown in FIG. 12-c with respect to the nozzle arrangement direction, and as a result,
Normally, these phenomena are perceived as density unevenness as seen by human eyes.

Therefore, as a countermeasure against the density unevenness, for example, a method as disclosed in Japanese Patent Application Laid-Open No. 60-107975 has been devised. The method will be described with reference to FIGS.
According to this method, the multi-head 2001 is scanned three times in order to complete the printing area shown in FIGS. 11 and 12, but a half area of four pixels is completed in two passes. In this case, the eight nozzles of the multi-head are divided into a group of four upper nozzles and a group of four lower nozzles.
The dots to be printed in each scan are obtained by thinning out prescribed image data by about half according to a predetermined image data arrangement. Then, dots are embedded in the remaining half of the image data at the time of the second scan, and printing in a 4-pixel unit area is completed. The above printing method is hereinafter referred to as a multi-pass printing method.

When such a recording method is used, even if the same multi-head as that shown in FIG. 12 is used, the influence on the print image specific to each nozzle is reduced by half. −b, and the black streaks and white streaks as seen in FIG. 12-b become less noticeable. Therefore, the density unevenness also
As shown in FIG. 3C, compared with the case of FIG.

In performing such recording, the first scan and the second scan
At the scanning eye, the image data is divided in such a manner that the image data is complemented with each other in accordance with a certain arrangement. However, this image data arrangement (thinning-out pattern) is, as shown in FIG. It is most common to use something like this.

Therefore, in the unit print area (here, in units of four pixels), printing is completed by the first scan for printing the staggered grid and the second scan for printing the inverted staggered grid.

An example of electrical control for performing such thinned-out printing will be described below with reference to FIGS. The Head unit sets the print data Si in an 8-bit shift register with the print data synchronous clock CLKi, and outputs BEi1 *, BEi2 *, BEi3 *,
By turning on the BEi4 * signals, the HEAD transistor array is driven and the Heater generates heat to perform printing. Here, * indicates low active. The LATCH * signal is a control signal for latching print data, and the CARESi * signal is a reset signal for clearing the latch. One heat is Heat Trigg
er signal and BEi1 *, BEi2 *, BEi3 from the pulse generator
*, Output BEi4 * signal. This signal may be output with a time lag, but here, it is output simultaneously for simplicity.

In order to perform the thinning, the flip-flop in the figure is hit by a Heat Trigger signal, and a signal (for example, BEi1 * and BEi3 *) to be alternately masked is changed each time heat is applied.
Actually, it depends on the high / low of the output signal DATAENB of the flip-flop as shown in the timing chart of FIG. He
BEi1 *, BEi2 *, BEi3 *, BEi4 * when at Trigger signal is applied
The signal goes low and each nozzle heats. The timing indicated by the broken line in the figure is the masked timing, which corresponds to the DATAENB signal. The EVEN signal and the ODD signal are both signals for initial setting of the mask pattern. If you want to print in a staggered pattern,
When the EN signal is sent, the flip-flop is preset and zigzag printing is possible. On the line where reverse zigzag printing is desired, when the ODD signal is sent, the flip-flop is reset, and the BEi2 * and BEi4 * signals are turned on first to enable reverse zigzag printing.

14-a, 14-b, and 14-c in FIG. 14 show how the recording of a certain area is completed when the staggered and inverted staggered patterns are used, as in FIG. This is described using a multi-head having nozzles. First, in the first scan, a staggered pattern (hatched circles) is printed using the lower four nozzles (14-a).
Next, in the second scan, paper feed is performed by 4 pixels (1/1 of the head length).
Performing only 2), the reverse zigzag pattern (white circle mark) is recorded (14-b). Further, in the third scan, the paper is fed again by four pixels (1/2 of the head length) again, and the staggered pattern is recorded again (14-c).

In this manner, the paper feed in units of four pixels is sequentially performed.
By alternately recording staggered and inverted staggered patterns,
A recording area in units of four pixels is completed for each scan. As described above, by completing printing in the same region using two different types of nozzles, it is possible to obtain a high-quality image without density unevenness.

[0016]

However, even when such multi-pass printing is performed, the above-mentioned density unevenness has not been eliminated at all depending on the duty, and new density unevenness has been confirmed especially in a half tone. Or The phenomenon will be described below.

Normally, the image data to be recorded in a certain area received by the printer is already regularly arranged. On the recording device side, these data are stored in the buffer in a certain amount, and a new mask (image arrangement pattern) of staggered or inverted staggered as described above is applied.
The printing of the pixel is performed only when both are turned on.

FIGS. 17 to 19 illustrate this state. In FIG. 17, reference numeral 1710 denotes already-arranged data stored in a buffer, reference numeral 1720 denotes a staggered pattern mask indicating pixels permitted to be printed in the first pass, and reference numeral 1730 denotes 2
Inverted zigzag pattern masks 1740 and 1750 indicating pixels permitted to be printed in the pass indicate pixels to be printed in the first pass and the second pass, respectively.

In FIG. 17, an area 2 in the buffer
When printing at 5%, data that has already been arranged is stocked. In general, this data is arranged in a state where print data varies as much as possible in order to maintain a uniform density in a specified fixed area. What kind of image arrangement these are depends on what area gradation method is performed at the time of image processing before being transferred to the printer main body. What is shown at 1710 is an example of a certain image arrangement for 25% data.
If printing is performed with a mask of 0, the data is distributed and recorded in the first pass and the second pass in a state in which the data is exactly equally divided as shown in 1740 and 1750.

However, as shown in FIG.
When the data arrives, the data 1810 in which the images are arranged in the most varied state and the staggered pattern mask (180
It is easy to imagine that either 2) or the inverted zigzag pattern mask (1830) is in the completely aligned state.

When this occurs, the first pass (184)
At 0), printing of all image data ends, and no printing is performed at the second pass (1850). That is, all the print data (1810) is printed by the same nozzle. Therefore, the effect of nozzle variation is directly reflected on density unevenness,
The original purpose of the divided recording method is not achieved.

FIG. 19 shows a printing state when array image data with a duty higher than that of FIGS. 17 and 18 is input. In this case, printing is performed in the first pass and the second pass. It can be seen that there is a considerable difference in the numbers. As described above, there is a problem in that the density unevenness, which has been improved at a high duty ratio close to 100%, reappears at data close to 50% from a low duty ratio.

As shown in FIG. 14, the head always prints either the staggered pattern or the inverted staggered pattern using all the nozzles. Therefore, in the print area of FIG. 14, the upper four pixels are landed in a staggered pattern first, and then the reverse staggered pattern is landed. After the staggered pattern is landed, the staggered pattern is landed. In other words, when this is combined with the above problem, a print area in which many dots land in the first pass and then a small number of dots land in the second pass, An area where a large number of dots are printed appears alternately at half the width of the head. From such a phenomenon, there are also the following adverse effects, particularly at the joint portion of the ink jet recording system.

In the ink jet recording system, when another dot is superimposed on a previously recorded dot, in the overlapping portion, the dot hit later than the previously recorded dot sinks in the depth direction of the paper. That is the tendency.

FIG. 20 is a cross-sectional view schematically showing this. This is because the dyes such as dyes in the ejected ink are physically and chemically bonded to the recording medium.At this time, since the bonding between the recording medium and the dyes is finite, the bonding force differs greatly depending on the type of the dyes. As long as there is no connection, the ink dye (cross hatching) ejected first and the recording medium are prioritized, so that much remains on the surface of the recording medium. It is considered that they are not easily bonded and sink and dye in the depth direction of the paper. Further, considering the behavior of the ink at the fiber level inside the recording medium, the fiber once bonded to the dye or the like in the ink has a higher hydrophilicity than the state where it is not bonded at all. Therefore, an ink droplet that has landed adjacent to a portion having strong hydrophilicity tends to be drawn in the direction in which the previous ink droplet has landed.

Also, as the previous ink droplet is not sufficiently fixed, that is, contains more water, the hydrophilicity is stronger and the ink droplets that have landed adjacently are more likely to be attracted. Therefore, the print area where a small number of dots land after a large number of dots have landed, and the area where a large number of dots are printed in the second pass in the state where printing is scarce at first, are 、 the width of the head. When the dots appear alternately, the dots recorded in the area adjacent to the printing area where a large amount of ink lands at the boundary have a strong attraction force, and are adjacent to the printing area where a small amount of ink lands. The dots recorded in the area have a weak attraction. Due to this difference, the density of the boundary between the print areas is high or low, resulting in density unevenness. This is particularly conspicuous in a half tone, and has a periodicity that appears alternately by half the width of the head.

When thinning printing is performed using a specific mask pattern, the print data and the mask pattern may have the same cycle. The amplitude of the density coming from the arrangement of the print pixels and non-print pixels by the mask pattern and the amplitude of the print data overlap, causing resonance. As a result, the dot arrangement of the formed image has a pattern having a specific directionality. Usually, this phenomenon is called moiré. This is conspicuous when an image using the same mask pattern exists in a plurality of rows, and is easily recognized by the user. This moire largely depends on the periodicity of the mask pattern.

Due to the disadvantages described above, in multi-pass printing that has been performed to correct variations in nozzles, it is not always possible to obtain sufficient image quality with respect to density unevenness. These adverse effects of the density unevenness promote the human vision that is recognized as the density unevenness because of the periodicity that appears alternately in a print area of a certain width.

Accordingly, an object of the present invention is to provide a recording apparatus and an ink jet recording apparatus which can always obtain sufficient image quality by reducing density unevenness.

[0030]

Therefore, an ink jet recording apparatus of the present invention scans the same recording area of a recording medium a plurality of times with a recording head having a plurality of discharge sections for discharging ink, and thins out each scan. In an ink jet recording apparatus that forms a thinned image according to a pattern to complete an image, setting means for setting a plurality of different types of mask patterns in which non-recording pixels and recording pixels are arranged, and the setting means for each recording area Thinning means for thinning out print data using the set different types of mask patterns as thinning patterns for the respective print areas. Further, according to the present invention, there is provided a recording apparatus which scans a recording head having a plurality of recording sections with respect to the same recording area of a recording medium a plurality of times, forms a thinned image according to a thinning pattern in each scan, and completes the image. Setting means for setting a plurality of different types of mask patterns in which recording pixels and recording pixels are arranged; and different types of mask patterns set for each recording area by the setting means, and thinning patterns for the respective recording areas. And a thinning means for thinning out print data. In addition, according to the present invention, an ink jet that scans a recording head having a plurality of ejection sections for ejecting ink a plurality of times over the same recording area of a recording medium and forms a thinned image in accordance with a thinning pattern in each scan to complete the image. In the recording method, a setting step of setting a plurality of different types of mask patterns in which non-recording pixels and recording pixels are arrayed, and different types of the mask patterns set for each recording area by the setting step, A thinning step of thinning print data as a thinning pattern for a print area.

[0031]

According to the above arrangement, a different mask pattern is used for each recording area, so that the periodicity due to the pattern of the thinning arrangement is not repeated for a plurality of rows, and the same recording which is not uniform in the conventional multi-pass recording method. By changing the periodicity of the density unevenness, the above-described adverse effect of the density unevenness caused by the number of recording pixels during the multi-pass printing of the area is made less noticeable, and high image quality can be realized.

[0032]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an ink jet recording apparatus according to the present invention.

FIGS. 21 to 25 show preferred ink jet units IJU, ink jet heads IJH, ink tanks IT, ink jet cartridges IJC, ink jet recording apparatus main bodies IJRA, and carriage HCs to which the present invention is applied or applied. FIG. 7 is an explanatory diagram for explaining the respective relationships. Hereinafter, the configuration of each unit will be described with reference to these drawings.

(I) Schematic description of the apparatus main body FIG. 21 is an example of an outline view of an ink jet recording apparatus IJRA applied to the present invention. In the figure, a driving force transmission gear 501 is linked with a forward / reverse rotation of a driving motor 5013.
Reed screw 500 rotating via 1,5009
5 has a pin (not shown) and is reciprocated in the directions of arrows a and b. The carriage HC is equipped with an ink cartridge IJC. Reference numeral 5002 denotes a paper holding plate, which platens the paper 500 in the carriage moving direction.
Press against 0. Reference numerals 5007 and 5008 denote home position detecting means for confirming the presence of the carriage lever 5006 in this region and switching the rotation direction of the motor 5013. Reference numeral 5016 denotes a member for supporting a cap member 5022 for capping the front surface of the recording head. Reference numeral 5015 denotes suction means for suctioning the inside of the cap, and recovering the suction of the recording head through the opening 5023 in the cap. 5017 is a cleaning blade.
Reference numeral 019 denotes a member which enables the blade to move in the front-rear direction, and these members are supported by the main body support plate 5018. It goes without saying that the blade is not limited to this form, and a well-known cleaning blade can be applied to this embodiment.

Reference numeral 5012 denotes a lever for starting suction for recovery of suction, and a cam 5020 which engages with the carriage.
The driving force from the driving motor is controlled by known transmission means such as clutch switching.

These capping, cleaning, and suction recovery are configured so that desired processing can be performed at the corresponding positions by the action of the lead screw 5005 when the carriage comes to the home position side area. If the desired operation is performed at the timing described above, any of the embodiments can be applied.

The ink jet cartridge IJ in this embodiment
C is a shape in which the ink storage ratio is large, and has a shape in which the tip of the ink jet unit IJU projects slightly from the front surface of the ink tank IT. The ink cartridge IJC is of a type that is fixedly supported by the above-described positioning means of the cartridge HC mounted on the ink jet recording apparatus main body IJRA and the electric contact, and is detachable from the carriage HC. is there.

(Ii) Description of Configuration of Inkjet Unit IJU The ink jet unit IJU is of a type in which recording is performed using an electrothermal converter that generates thermal energy for causing ink to cause film boiling according to an electric signal. It is a unit.

(Iii) Description of Heater Board FIG. 22 is a schematic diagram of a heater board 100 of a head used in this embodiment. A temperature control (sub) heater 8d for controlling the temperature of the head, a discharge section array 8g provided with a discharge (main) heater 8c for discharging ink, and a drive element 8h are positioned as shown in FIG. In relation, they are formed on the same substrate. By arranging each element on the same substrate in this manner, the head temperature can be detected and controlled efficiently, and the head can be made compact and the manufacturing process can be simplified. Also, FIG. 7 shows the positional relationship of the outer peripheral wall cross section 8f of the top plate, which is separated into a region where the heater board is filled with ink and a region where the heater board is not filled. The discharge heater 8d side of the outer peripheral wall section 8f of the top plate functions as a common liquid chamber. A liquid passage is formed by a groove formed on the discharge section row 8g of the outer peripheral wall section 8f of the top plate.

(Iv) Description of Control Configuration Next, a control configuration for executing recording control of each section of the above-described apparatus configuration will be described with reference to a block diagram shown in FIG. In the figure showing a control circuit, 10 is an interface for inputting a recording signal, 11 is an MPU, 1
Reference numeral 2 denotes a program ROM for storing a control program executed by the MPU 11, and reference numeral 13 denotes a dynamic RAM for storing various data (such as the print signal and print data supplied to the head). The number of times the recording head has been replaced can be stored. 14 is a recording head 1
8 is a gate array that controls supply of print data to the interface 8, the interface 10, the MPU 11, the RAM 13
It also controls the transfer of data between them. Reference numeral 20 denotes a carrier motor for transporting the recording head 18, and reference numeral 19 denotes a transport motor for transporting the recording paper. Reference numeral 15 denotes a head driver for driving the head, and reference numerals 16 and 17 denote motor drivers for driving the transport motor 19 and the carrier motor 20, respectively.

FIG. 24 is a circuit diagram showing the details of each part of FIG. The gate array 14 includes a data latch 141,
It has a segment (SEG) shift register 142, a multiplexer (MPX) 143, a common (COM) timing generation circuit 144, and a decoder 145. The recording head 18 has a diode matrix configuration, and a drive current flows through the ejection heaters (H1 to H64) where the common signal COM and the segment signal SEG coincide, whereby the ink is heated and ejected.

The decoder 145 decodes the timing generated by the common timing generation circuit 144 and selects one of the common signals COM1 to COM8. The data latch 141 latches the recording data read from the RAM 13 in 8-bit units, and the multiplexer 143 stores the recording data in the segment shift register 1.
In accordance with 42, it is output as segment signals SEG1-8. The output from the multiplexer 143 can be variously changed according to the contents of the shift register 142, such as 1-bit unit, 2-bit unit, or all 8 bits, as described later.

The operation of the above control configuration will be described. When a recording signal enters the interface 10, the recording signal is converted between the gate array 14 and the MPU 11 into recording data for printing. Then, the motor drivers 16 and 17 are driven, and the recording head is driven according to the recording data sent to the head driver 15 to perform printing.

FIG. 25 is a block diagram for explaining the flow of print data inside the printing apparatus. The recording data sent from the host computer is stored in a reception buffer inside the recording device via the interface. The reception buffer has a capacity of several kilobytes to several tens kilobytes. After the command analysis is performed on the recording data stored in the receiving buffer, the data is sent to the text buffer. In the text buffer, recorded data is held as one line of intermediate format,
Processing to add the print position, type of modification, size, character (code), font address, and the like of each character is performed. The text buffer capacity differs depending on each model,
A serial printer has a capacity of several lines, and a page printer has a capacity of one page. Further, the print data stored in the text buffer is expanded and stored in a print buffer in a binarized state, and a signal is sent to the print head as print data to perform printing. In this embodiment, the binary data stored in the print buffer is multiplied by mask pattern data (random mask) described later, and then a signal is sent to the print head. Therefore, it is possible to set the mask pattern data after looking at the data stored in the print buffer. Depending on the type of recording device, there is also a recording device which does not have a text buffer but develops recording data accumulated in a receiving buffer at the same time as command analysis and writes the data in a print buffer.

A specific embodiment of the present invention will be described below using such an apparatus.

(Embodiment 1) As a first embodiment, an example of forming an image by setting a mask pattern for each recording (printing) area in an ink jet recording apparatus will be described with reference to the drawings. The printing area referred to here is an area divided in the recording scanning direction, and in this embodiment, an area recorded in one scanning is divided into four.

The manner in which a mask pattern is set for each print area and printing is performed will be described with reference to FIG. In this embodiment, four pass printing for completing printing is performed by four printing scans of one printing area. The mask pattern to be used is a 4 × 4 mask pattern of 25% duty thinning, and whether to print or not is set for each print pixel. First, in the first printing area, printing is performed using the mask pattern: A-1 in the first printing scan. Subsequently, in the second printing scan, printing is performed using the mask pattern: A-2, and at the same time, printing is performed in the second printing area using a mask pattern: B-1 different from the first printing area. Further, in the third print scan, printing is performed using the mask pattern: A-3, and in the second print area, the mask pattern:
B-2 In the third print area, recording is performed using a mask pattern: C-1 different from the above-described print area.
Then, printing using the mask pattern: A-4 is performed in the fourth printing scan, and printing in the first print area is completed. In the same procedure, the mask pattern: B-
Recording is performed at 1, B-2, B-3, and B-4. In the third print area, mask patterns: C-1, C-2, C-3,
Recording is performed in C-4, and recording is performed in the fourth print area using mask patterns: D-1, D-2, and D-3.

In this manner, printing is performed with a different mask pattern for each print area. This embodiment is an example in which four types of mask patterns are used. In the fifth print area, the same mask pattern as in the first print area is used.
In the printing area, the same mask pattern as in the second printing area is used. Depending on the number of types of mask patterns to be set, the printing area where printing is performed using the same mask pattern may be close or tens of lines apart. Therefore, it is possible to control the frequency of occurrence of a print area where printing is performed using the same mask pattern, based on the number of types of mask patterns held.

FIG. 2 shows an example of four types of mask patterns used in this embodiment. In FIG. 2, each mask pattern is a 4 × 4 mask pattern of 25% duty thinning, and A-1, A-2, A-3, and A-4 are one group of mask patterns used in one print area. is there. One group for B-1, B-2, B-3, and B-4, C
-1, C-2, C-3, C-4, one group, D-1,
D-2, D-3, and D-4 form one group.
The arrangement of dots to be printed differs depending on each mask group.

Next, a recording head for setting each mask pattern will be described with reference to FIG. Although the recording head shown in FIG. 3 has a plurality of nozzles and can perform printing with each nozzle, in this embodiment, since the four-pass printing is performed, the nozzle portion of the recording head is divided into four regions. . The respective divided regions are defined as L1, L2, L3, and L4. Different mask patterns can be set independently for each divided area. For example, in the fourth scanning printing in FIG. 1, L4 is A-4, L3 is B-3, and L2 is C-.
2, L1 is set to D-1 as a mask pattern. In the fifth scan recording, L4 is B-4, L4
3 is set as a mask pattern, C-2, L2 is set as D-2, and L1 is set as A-1. Thus, different mask patterns are independently set for each divided area.

Next, the fact that a certain printing area can be complemented by the 4 × 4 mask pattern of 25% duty thinning shown in FIG. 2 will be described with reference to FIG. Figure 4 shows the mask pattern:
This is the case where A-1, A-2, A-3, and A-4 are used. In the portion where printing is performed with each of the four mask patterns, all four mask patterns are different from each other, and finally all the four mask patterns are added up, so that 100 parts are finally obtained.
% Complement can be done. Further, a portion where printing is performed is not duplicated by the mask pattern. This relationship can be applied to other mask pattern groups. The mask pattern used for one print area can always be 100% complemented and not duplicated.

Next, the timing for setting a mask pattern for each print area will be described. FIG. 5 shows a print sequence of 4-pass printing. This sequence is a sequence in a state where print data has been sent. Check the print data transmission, and ramp up the carriage. The setting of the mask pattern is performed at the time of carriage ramp-up. st
If the carriage ramps up on ep-1, first step-2
A mask pattern is set in the divided area L1 of the print head. The mask pattern is set from the example of the mask pattern shown in FIG. Similarly, a mask pattern is set in the divided area: L2 in step-3, a divided area: L3 in step-4, and a divided area: L4 in step-5. Then, a mask is set in the buffer in step-6, printing is performed in step-7, and the process returns to step-1. When a mask pattern is set for each print area, for each print area,
Mask patterns are set so that print data can be complemented by 100%.

However, a mask pattern can be completely freely set in a new print area or an area where nothing is printed. The mask pattern may be stored in a storage area such as a ROM in the printing apparatus in advance, and the stored mask pattern may be called when the mask pattern is set, or a function for generating the mask pattern may be provided. At times, a mask pattern may be created and temporarily stored in NVRAM or the like for use.

Next, a process in which printing is performed in each printing area to form an image will be described with reference to FIG. FIG. 6 shows a process in which an image when four-pass printing is performed in this embodiment is formed by each printing scan. First, in the first print area, printing is performed by thinning out using the mask pattern set in the first print scan, and in the second print scan, printing is performed on a different print pixel using a mask pattern different from the first print scan. In the second print scan, printing is performed on a different print pixel with a different mask pattern from the first and second print scans. Finally, in the fourth print scan, printing is performed with a different mask pattern from the above-described print scan. The recording is completed for all the print pixels in the first print area.

On the other hand, in the second printing area, printing has been started from the second printing scan. Recording is completed in the same process as the first print area, but the mask pattern used is different. The same applies to the third print area and the fourth print area, and recording is performed using a different mask pattern from the other print areas.

As described above, according to the present invention, in a multi-pass printing method in which printing is performed by a plurality of movements and printing scans using an ink jet printing apparatus, the number of printing scans (the number of passes) is determined. A plurality of mask patterns can be set for each print area, and different mask patterns can be independently set for different print areas. Therefore, since recording is performed on each print area with a unique different mask pattern, it is possible to control the periodicity that appears alternately in a print area having a width with density unevenness, instead of suppressing the density unevenness itself. By setting the cycle to be hardly recognized as density unevenness by human eyes, a high-quality image can be recorded.

In principle, even if there is a synchronism with a certain print data pattern, it is only in that print area, and there is no synchronism in other print areas.
Therefore, if the period in which the synchronized print area appears is, for example, a period of several tens of lines that is difficult to recognize, it is not recognized as density unevenness. In addition, by setting the cycle of the set mask pattern variously and changing the cycle of occurrence, it is possible to make it more difficult to recognize the density unevenness. Further, moiré depending on the periodicity of the mask pattern can also be stopped at a very small portion, and is hardly recognized as moiré. Therefore, by setting a different mask pattern for each print area, it is possible to control the periodicity of the density unevenness and to print a high-quality image.

(Embodiment 2) Next, as a second embodiment, a four-pass printing method for performing printing by controlling the period of a mask pattern set for each printing area will be described.

FIG. 7 shows a sequence for controlling the periodicity of the mask pattern set for each print area. This sequence is a sequence in a state where the print data has been sent. After confirming the transmission of the print data, the carriage is ramped up. When the carriage is ramped up in step-1, the CPU determines whether there is a mask pattern set in step-2. If there is a set mask pattern, the buffer is set in step-5 using the mask pattern, and printing is performed in step-6. If no mask pattern has been set, a cycle value for setting the mask pattern is determined in step-3, and the mask pattern is set in step-4. Since the mask circulates at various intervals, it is hereinafter referred to as a circulating mask pattern.

Next, using the cyclic mask pattern, step-5
To set the buffer, print in step-6, and step-1
Return to In this sequence, a cyclic mask pattern can be set for each print area, and if there is no mask set, a cyclic mask pattern is set in step-3 and step-4. For example, it jumps to printing in step-2.

FIG. 8 shows a specific mask pattern. FIG. 8 shows seven types of mask patterns A to G. These mask patterns are stored in advance in a ROM, a RAM, or the like.
It may be set so that a plurality of mask patterns are generated at the time of N or the like. In this embodiment, seven types of mask patterns are shown. However, as the number of mask patterns increases, the number of selections increases, and the randomness of mask pattern selection increases. AG
Is a set of four mask patterns,
Each of the four mask patterns can complement 100%.

FIG. 9 shows a change in the cyclic mask pattern when the cycle value is changed. In the case of cycle 1, A to G are sequentially set. This is the basic system. In cycle 2, the setting is performed by skipping one. In cycle 3, the setting is performed by skipping two. In cycle 4, the setting can be performed by skipping three. By changing the cycle value, the order of A to G can be changed. If this method is used to set a cyclic mask pattern according to the sequence of FIG. 7, the cycle of the set cyclic mask pattern can be controlled by a cycle value.

As described above, in the multi-pass printing method in which printing is performed by a plurality of movements and printing scans using an ink-jet printing apparatus, when a unique mask pattern is set for each printing area, By controlling the cycle of the set mask pattern, the cycle in which the density unevenness occurs can be controlled.

(Embodiment 3) Next, as a third embodiment, a printing method in which a mask pattern is stored in one ring buffer and used will be described.

FIG. 10 shows a ring buffer. The ring buffer is a circular storage area that can be used by returning to the buffer 1 again when the buffer 1, the buffer 2, the buffer 3, and the buffer 4 are used. In the present embodiment, when one mask pattern is stored in the ring buffer and used as a mask pattern, by changing the readout position, it can be used as if it were a different mask pattern.

The ring buffer shown in FIG. 10 is set to have a length of 4 bytes (corresponding to 32 nozzles) so that it can be used when 4-pass printing is performed using a 128-nozzle recording head. The overall length and width depend on the settings of the main body of the recording apparatus, but in this embodiment, the setting is several kilobytes. Buffer 1, Buffer 2, Buffer 3, and Buffer 4 are mask patterns that can be 100% complemented in total, and these four large mask patterns are linked to form one larger mask pattern. Therefore, for one print area,
A in the figure, which is the starting position of each buffer,
The mask pattern is read from B, C, and D. As a result, a mask pattern that can be 100% complemented can be set. In addition, the readout positions can be shifted for different print areas, and can be set as if they were different mask patterns. The read position is shifted by two columns each, and A ', B', C ',
D '.

As described above, one mask pattern is set in the ring buffer of the present embodiment, and the read position is changed in each printing area, so that various mask patterns can be set in each printing area. Can be set. The larger the capacity of the ring buffer, the less the periodicity of the mask pattern set in each print area. Thereby, the periodicity of the occurrence of the density unevenness can be changed.

(Embodiment 4) FIG. 26 is a block diagram showing a configuration of a data transfer circuit embodying the present invention. Referring to FIG. 1, reference numeral 101 denotes a data register connected to a memory data bus to read out print data stored in a print buffer 130 in the memory and temporarily store the read data. Reference numeral 102 denotes data stored in the data register 101. A parallel-serial converter for converting into serial data, an AND gate 103 for masking serial data, and a counter 104 for managing the number of data transfers.

Reference numeral 105 denotes a CPU via a CPU data bus.
Reference numeral 110 is a register for storing a mask pattern, 106 is a selector for selecting a digit position of the mask pattern, and 107 is a selector for selecting a row position of the mask pattern. Reference numeral 111 denotes a counter for managing the digit position.

The data transfer circuit shown in FIG.
In response to a print command signal sent from 10, the print data of 128 bits is serially transferred to the print head.
The print data stored in the print buffer 130 in the memory is temporarily stored in the data register 101, and is converted into serial data by the parallel-serial converter 102. The converted serial data is AN
After being masked by D-gate 103, it is transferred to the printhead. The transfer counter 104 counts the number of transfer bits and terminates the data transfer when it reaches 128.

The mask register 105 includes four mask registers A, B, C, and D, and stores a mask pattern written by the CPU 110. Each register stores a mask pattern of 4 bits × 4 bits. The selector 106 selects mask pattern data corresponding to the digit position by using the value of the column counter 111 as a selection signal. The selector 107 selects mask pattern data corresponding to the row position by using the value of the transfer counter 104 as a selection signal. Selector 1
The transfer data is masked using the AND gate 103 according to the mask pattern data selected by 06 and 107.

In this embodiment, the masked transfer data is supplied directly to the recording head, but may be temporarily stored in a print buffer.

(Embodiment 5) A printing method in which a random mask pattern is set for each printing area and the mask is shifted for each pass will be described.

FIG. 27 shows a random mask pattern used in this embodiment. In the present embodiment, a mask pattern having a size of 32 kbytes (column direction: 4 bytes × raster direction: 8 k) is used, and a case where the mask pattern is used for 4-pass printing will be described. The random mask pattern of this embodiment is 4
Since it is for a pass, it is divided into regions: A, B, C, and D, respectively, and the four masks are connected to form one mask pattern. This random mask pattern is recorded on the RAM, and the read position (pointer)
Can be set freely. Further, the pointer can be shifted and used for each print area.

FIG. 28 shows a recording head and a mask pattern to be used for each print area. In the first printing scan, printing is performed with the mask: A1, and in the subsequent scans, printing is performed with the masks: B1, C1, and D1, and printing is completed. Here, the mask: A1 indicates a mask indicating the position of the pointer 1 in the area A in FIG. Similarly, B1, C1, and D1 are masks in which the position of the pointer is 1 in each area. In the next print area, masks: A2, B2, C2, and D2 are used. The pointer is shifted from the mask used in the previous print area. The shift amount can be set arbitrarily, but in the present embodiment, one area is shifted by 256 columns. The pointer comes to the same position in the ninth print scan. Therefore, when viewed in the adjacent print area, it looks as if a different mask pattern is used. By shifting the mask, an effect equivalent to using a different mask pattern can be obtained simply by shifting the pointer from one mask.

Next, a method of generating a random mask will be described. FIG. 29 shows a block diagram of creating a random mask pattern. In this embodiment, a case of 4-pass printing will be described. First, a mask of a specific size is set, and the mask is filled with the same number of four parameters (a, b, c, d). Then, randomly select from the parameters in it,
Replace (replace). This is performed a plurality of times to create a mask in which each parameter is randomly arranged. The number of times of replacement is arbitrary as long as the number of times is sufficient to make the mask random, but in this embodiment, 25000 ×
I went 15 times.

The state of the parameters of this random arrangement is stored in the ROM. From there, create each thinning mask. For example, parameters: a, b, c, d
Are set to correspond to masks: A, B, C, and D, respectively, and a mask is created by setting a bit only at a position where the corresponding parameter exists. Originally, the positions of the parameters are randomly arranged, so that the created mask is also a random mask pattern having a random arrangement. Furthermore, since it is created from a single mask, it must be 100%
It becomes a complementary random mask pattern. This operation is performed by the CPU, and the created mask is stored in the RAM and used.

FIG. 30 shows the relationship between the CPU and the ROM and RAM. When the process is performed by the printer main body, random arrangement data is stored in the ROM, the above-described random mask is created at a timing such as when the power is turned on, and the state of the mask is stored in the RAM. When the carriage is ramped up for each print scan, the data is read from the RAM and ANDed with the print data in the print buffer to perform printing.

Therefore, when creating a random mask, it is possible to change the random mask according to the print mode. For example, random mask patterns for 2-pass printing, 4-pass printing, and 8-pass printing can be created from the same random array data. This is determined by the number of types of parameters (four types in FIG. 29) of the data in the random array. If there are 24 types of parameters (for example, 0 to 23), the number of paths corresponding to a submultiple thereof is Can correspond. In other words, if two masks are created corresponding to 0 to 11 and 12 to 23, it corresponds to two passes,
If three masks are created corresponding to 7, 8 to 15, and 16 to 23, it corresponds to three passes. Hereinafter, similarly,
It is possible to handle 6, 8, 12, and 24 passes.

Further, it is possible to perform 100% or more complementation or double printing at a specific ratio by associating a plurality of parameters with one mask instead of associating one parameter with one mask. And the up rate can be arbitrarily set by the number of parameters to be set. In the above example, if two masks are created corresponding to 0 to 15, 8 to 23, the result is 133%.
150% if two masks are created for 6 to 23
become.

As described above, the ROM of this embodiment is
A random mask is created from the random array data stored in the RAM and stored in the RAM.
Read from and use. Further, by shifting the read position for each print area, a structure is obtained in which a different random mask pattern is used in the close print area. This makes it possible to use the random mask pattern more effectively in terms of non-synchronization with the print data.

(Others) The present invention brings about an excellent effect particularly in a recording head and a recording apparatus which use thermal energy among ink jet recording methods.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling, to the electrothermal transducer arranged corresponding to the sheet or liquid path in which is held, This is effective because heat energy is generated in the electrothermal transducer, and the film is boiled on the heat-acting surface of the recording head. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. Examples of the drive signal in the form of a pulse include those described in U.S. Pat.
Suitable are those described in US Pat. No. 45,262. If the conditions described in U.S. Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,558,333 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 459600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication (Kokai) No. 123670/1984 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

Further, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

The present invention is not limited to ink jet recording, but can be applied to general recording apparatuses such as thermal recording, thermal transfer recording, and wire dot recording. In a serial printer, a mask pattern is changed for each recording area. The effect of this case will be described.

As described above, in the division (multi-pass) printing, by performing printing with a plurality of different printing elements (elements) for one raster, characteristics of the printing elements (e.g., deviation, dot size, etc.) are obtained. The non-uniformity is averaged to make density unevenness in one recording area difficult to see.
As described above, if the printing elements used in synchronization with the print data and the mask pattern are biased, the characteristics of the divided printing easily appear in one raster. Therefore, by using a random mask, the synchronism with the data becomes partial, and divided printing can be performed effectively.

This can be said to be common to all dot matrix printers. In the case where a pseudo gradation characteristic is obtained by using two values of dot ON / OFF, it is necessary to uniformly control the characteristics of the recording element, and divided printing in which a mask pattern is changed for each recording area is effective.

Further, in the case of a recording apparatus that performs printing by using heat (thermal rotation or the like), division printing is effective from the viewpoint of suppressing the temperature rise of the recording head. In this case, too, the temperature rise of the head is also biased due to the synchronization between the print data and the thinning mask, and density unevenness (non-uniform dot diameter) occurs due to heat distribution in the recording head. On the other hand, by changing the mask pattern for each recording area, comprehensive heat uniformity can be achieved.

In a color recording apparatus having a plurality of recording heads arranged in the scanning direction of the carriage, the color tone changes in the order of dot formation. Synchronization between the print data and the thinning mask appears in the color tone, and an image having a color tone different from the color desired by the user may be recorded. For example, in the case of thermal transfer recording, if dots (ink layers) printed earlier exist on the recording medium, the dots to be transferred next are difficult to transfer. On the other hand, in the case of ink jet recording, when a highly permeable ink is used, the dye of the previously printed ink is first adsorbed on the ink holding layer or the fiber of the recording medium, and the dye of the next printed ink is hardly adsorbed.
Therefore, the color tone of the first dot becomes strong. On the other hand, in the case of ink having low permeability, the color of the post-printed dot may be increased because the post-printed dye does not flow and overlaps the upper layer. By changing the mask pattern for each recording area for these phenomena as well, it is possible to reduce the occurrence of a color tone shift in a macroscopic manner.

[0091]

According to the present invention, a mask pattern in which non-recording pixels and recording pixels are arranged is uniquely set for each recording area, thereby changing the pattern period of the thinned-out arrangement. Density unevenness caused by the number of printing pixels during several multi-pass printings of the same printing area, which was not uniform in the conventional multi-pass printing method, becomes less noticeable by changing the periodicity of the density unevenness. Thus, high-quality image formation can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating setting of a different mask pattern for each print area in an ink jet recording apparatus for explaining a basic concept of the present invention.

FIG. 2 is a diagram illustrating an example of a 4 × 4 mask pattern of 25% duty thinning used in the first embodiment.

FIG. 3 is an explanatory diagram of each divided area corresponding to a print area of a recording head.

FIG. 4 is a diagram for explaining 100% complementation of printing using four 4 × 4 mask patterns used in the first embodiment.

FIG. 5 is a diagram illustrating a sequence of setting a mask pattern for each print area performed in the first embodiment.

FIG. 6 shows a case where a different mask pattern is used in each print area;
FIG. 4 is a diagram illustrating a process of forming an image.

FIG. 7 is a diagram showing a sequence for setting a cyclic mask pattern performed in the second embodiment.

FIG. 8 is a diagram showing an example of a mask pattern constituting a cyclic mask pattern.

FIG. 9 is a diagram illustrating control of a cycle of a cyclic mask pattern by a cycle value.

FIG. 10 is an explanatory diagram of setting of a mask pattern by a ring buffer used in the third embodiment.

FIG. 11 is a diagram showing an ideal printing state of the ink jet printer.

FIG. 12 is a diagram illustrating a printing state of an inkjet printer having uneven density.

FIG. 13 is a diagram illustrating divided printing according to a conventional example.

FIG. 14 is a diagram illustrating divided printing according to a conventional example.

FIG. 15 is a diagram showing an electric circuit for generating a thinning pattern according to a conventional example.

FIG. 16 is a timing chart of a heat pulse according to a conventional example.

FIG. 17 is a diagram illustrating 25% data and print dots during conventional divided printing.

FIG. 18 is a diagram illustrating 50% data and print dots during conventional divided printing.

FIG. 19 is a diagram illustrating 63% data and print dots during conventional divided printing.

FIG. 20 is a cross-sectional view of landing of two dots.

FIG. 21 is an explanatory diagram showing an ink jet recording apparatus main body to which the present invention is applied.

FIG. 22 is a diagram illustrating a heater board.

FIG. 23 is a block diagram showing a control circuit.

FIG. 24 is a block diagram showing a control configuration.

FIG. 25 is a configuration diagram illustrating the flow of print data.

FIG. 26 is a block diagram illustrating a configuration of a data transfer circuit according to an embodiment of the present invention.

FIG. 27 is a diagram showing a random mask pattern.

FIG. 28 is a diagram illustrating a recording head for a print area and a mask pattern to be used.

FIG. 29 is a block diagram illustrating random mask pattern creation.

FIG. 30 is a block diagram showing a relationship between a CPU, a ROM, and a RAM.

[Explanation of symbols]

 103 AND gate 105 Mask register 106 Selector 110 CPU 130 Print buffer

──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Kentaro Yano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Osamu Iwasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Daigoro Kanematsu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masao Sasaki 263 Imai Minamicho, Nakahara-ku, Kawasaki City, Kanagawa Prefecture (56) References 5-155040 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/01

Claims (7)

(57) [Claims] 1. An ink jet recording method in which a recording head having a plurality of ejection sections for ejecting ink is scanned a plurality of times on the same recording area of a recording medium, and a thinned image is formed according to a thinning pattern in each scan to complete the image. In the apparatus, setting means for setting a plurality of different types of mask patterns in which non-printed pixels and print pixels are arranged, and different types of the mask patterns set for each print area by the setting means, An ink jet printing apparatus, comprising: a thinning means for thinning print data as a thinning pattern for an area. 2. The ink jet printing apparatus according to claim 1, wherein said setting means can set said mask pattern for each printing scan. 3. The ink jet recording apparatus according to claim 1, wherein the setting unit changes a generation cycle of the set mask pattern. 4. The ink jet recording apparatus according to claim 1, wherein said setting means generates a plurality of complementary mask patterns from one mask pattern. 5. The ink jet recording apparatus according to claim 1, wherein the recording head discharges the ink by heat. 6. A recording apparatus which scans a recording head having a plurality of recording sections with respect to the same recording area of a recording medium a plurality of times and forms a thinned image in accordance with a thinning pattern in each scan to complete the image. Setting means for setting a plurality of different types of mask patterns in which pixels and recording pixels are arranged; and different types of mask patterns set for each recording area by the setting means as a thinning pattern for each of the recording areas. A recording apparatus comprising: thinning means for thinning print data. 7. An ink jet recording method in which a recording head having a plurality of ejection sections for ejecting ink is scanned a plurality of times on the same recording area of a recording medium, and a thinned image is formed in each scan according to a thinning pattern to complete the image. In the method, a setting step of setting a plurality of different types of mask patterns in which non-recording pixels and recording pixels are arranged, and the different types of mask patterns set for each recording area by the setting step are used for each of the recording steps. A thinning step of thinning print data as a thinning pattern for an area.