JP4411028B2 - Inkjet recording apparatus and inkjet recording system - Google Patents

Description

The present invention relates to an ink jet recording apparatus and an ink jet recording system for performing recording using a gradation pattern of a systematic dither method and a dot pattern in which dot arrangement information is stored.

  An ink jet recording apparatus records an image by ejecting ink droplets from ink ejection ports constituting nozzles of an ink jet recording head (hereinafter referred to as “recording head”) and depositing the ink on a recording medium. As one of the ink ejection methods in the recording head, a state in which the ink undergoes a sudden volume change (bubble generation) by applying an electrical signal to a heating element (electrothermal converter) disposed in the vicinity of the ejection port. There is a system in which a change is caused and ink is ejected from an ejection port by an action force based on this state change. As another ink ejection method, there is a method in which a piezoelectric element or the like (electrical / mechanical conversion element) is used and ink is ejected from an ejection port by a change in ink pressure due to mechanical fluctuation. As a recording method, a recording operation in which ink is ejected while the recording head moves in the main scanning direction and a conveying operation in which a recording medium is transported by a predetermined amount in the sub-scanning direction intersecting the main scanning direction are alternately performed. There is a serial scan method in which an image is recorded on a recording medium by repeating.

  A serial scan type ink jet recording apparatus using such a recording head can record a high-quality image at high speed and with low noise, and has a plurality of ejection openings in the recording head along the sub-scanning direction. Can be arranged in density. For this reason, it has many excellent points such that it is possible to easily obtain not only a high-resolution recording image and black and white image but also a color image with a small recording device for the size of the recording medium. The recording head can be formed into a so-called multi-nozzle by accumulating a plurality of ink discharge ports and ink liquid paths constituting the nozzle so as to integrate a plurality of recording elements. When recording a color image, generally, a plurality of recording heads having multiple nozzles are provided.

  However, as the resolution of recorded images increases, the size of data to be processed in the recording apparatus becomes enormous. Therefore, in a printing system consisting of an image processing unit and an inkjet recording unit, the data processing speed in the image processing unit or the data transfer rate when transferring from the image processing unit to the inkjet recording unit becomes a bottleneck, and the throughput of the entire system There is a risk of causing a significant decrease in. Further, as the resolution of the recorded image is increased, the memory capacity for data storage required in the ink jet recording apparatus main body must be increased, which may increase the cost of the recording apparatus.

  Therefore, in recent inkjet recording apparatuses, image data subjected to relatively low resolution and multi-value quantization processing (hereinafter also referred to as “highly quantized image data”) is transferred from the image processing unit to the inkjet recording unit. In the ink jet recording unit, the received low-resolution and high-quantized image data is developed into a predetermined matrix and recorded (dot matrix recording).

  One of representative examples of multi-value quantization processing in the image processing unit, that is, an n-value (n ≧ 3) method is an organized dither method. In the systematic dither method, a matrix in which threshold values irrelevant to input pixels are regularly distributed is used as a dither matrix, and this dither matrix is repeatedly used in the vertical direction and the horizontal direction. Then, the gradation of the input image is changed to n values (n ≧ 3) by the input pixel and the corresponding threshold value on the dither matrix. The regular threshold arrangement (hereinafter also referred to as “tone pattern”) of the systematic dither method that has been generally used includes a dot dispersion type and a dot concentration type.

  FIG. 13 shows a typical dot dispersion type (Bayer-type) gradation pattern representing 256 gradations. This gradation pattern is an 8 × 8 matrix. The ink jet recording unit has a dot matrix corresponding to an n-value (n ≧ 3) gradation value, and a plurality of predetermined dot patterns are stored in the dot matrix. 14A to 14E show examples of dot patterns defined in a dot matrix having a size of 2 × 2 pixels so as to correspond to five-valued gradation values “0” to “4”. Show.

  For example, the image data is quantized to 9 values (4 bits) at a resolution of 300 DPI (horizontal) × 300 DPI (vertical) by multi-value quantization processing in the image processing unit, and the quantized image data in the inkjet recording unit Is recorded in a 4 × 2 matrix of 1200 DPI (horizontal) × 600 DPI (vertical). In this case, the processing in the image processing unit is a relatively low-resolution 300 DPI quantization process, and the load on the image processing unit is reduced as compared with a relatively high-resolution 1200 DPI quantization process. One 4-bit image data with a resolution of 300 DPI corresponds to four 1-bit image data of 600 × 600 DPI, and corresponds to eight of 1-bit image data of 1200 × 600 DPI. Therefore, the data transfer amount from the image processing unit to the ink jet recording unit is half that required when the ink jet recording unit develops and records in a 600 × 600 DPI matrix.

  In Patent Document 1, a plurality of dot patterns having different positions of one dot in a 2 × 2 dot matrix are prepared and used as a dot pattern having a gradation value “1” as shown in FIG. A configuration for sequentially changing the dot pattern is described. Similarly, a plurality of dot patterns having gradation values “2” and “3” as shown in FIGS. 14C and 14D are prepared, and the dot patterns to be used are sequentially changed. The dot pattern to be used is sequentially changed during one recording scan, is changed according to the recording position of the image, or is randomly changed.

JP-A-9-46522

  However, as a result of examining the durability of the recording head when recording an image over a long period of time in the above-described conventional serial scan type inkjet recording apparatus using a systematic dither method, a plurality of nozzles of the recording head It was found that it appeared with periodicity that had an adverse effect on durability.

  Hereinafter, with reference to the attached drawings, the periodicity of the adverse effect on the nozzle will be described.

  As an inkjet recording apparatus, for example, in a recording apparatus using a recording head that uses thermal energy to foam ink and eject ink droplets, among a plurality of nozzles in a recording head capable of ejecting ink, in particular, a long For nozzles that eject ink intensively by time recording, the quality of images recorded using the nozzles tends to deteriorate. As the cause, it is conceivable that the dye and impurities in the ink are solidified and deposited by heat on the heater surface which is an electrothermal converter for supplying thermal energy to the ink.

  In the above conventional example, as a result of recording an image over a long period of time using the systematic dither method, all nozzles of the recording head are not uniformly deteriorated, and as shown in FIG. In the vertical direction), deteriorated nozzles such as ink ejection failure appeared with a certain periodicity. This is because the use (ink ejection) frequency of the nozzle corresponding to the fixed pattern having a certain periodicity is biased. In the case of FIG. 15, the certain period is a 16-nozzle period corresponding to the size of the gradation pattern of the systematic dither method.

  The reason is that the gradation pattern of the systematic dither method is repeatedly used in the vertical direction and the horizontal direction in the area where the image data exists. This is because the positional relationship is always fixed. Another cause is that the movement amount of the relative movement of the recording head and the recording medium in the vertical direction (sub-scanning direction) before and after the recording head scans in the horizontal direction (main scanning direction) is the gradation pattern. Since it is an integral multiple of the size (or the size of the gradation pattern is an integral multiple of the number of nozzles corresponding to the amount of movement of the print head that moves in the vertical direction between print scans), This is because the relationship between the tone pattern and the nozzle position of the recording head is fixed.

  Furthermore, since the dot pattern of the corresponding dot matrix is used for the n-value (n ≧ 3) image data based on the gradation pattern of the systematic dither method, the frequency of use (ink ejection) of the nozzle by that dot pattern is used. There is also a risk of the occurrence of bias.

  For example, the use of nozzles used when an image having a halftone density (duty 5%, 10%, 15%, 25%) is recorded using the gradation pattern shown in FIG. 13 and the dot pattern shown in FIG. The (ink ejection) frequency is shown in FIGS. Here, in order to make the feature of the problem conspicuous, a dot pattern in which one dot is arranged in a 2 × 2 dot matrix as shown in FIG. 10A is used. The frequency of nozzle use (ink ejection) appears with periodicity according to the size of the gradation pattern of the systematic dither method shown in FIG. Therefore, the number of times representing the nozzle use (ink ejection) frequency in FIGS. 10B to 10F is used when a 16 × 16 dot area is recorded by the gradation pattern (8 × 8) in FIG. No. of nozzles used (probability). For example, when an image with a duty of 5% is recorded as shown in FIG. 10B, as shown in FIG. 17, the gradation pattern (8 × 8) and the recording area (16 × 16 dots) shown in FIG. From the relationship with the used nozzles of the recording head, the number of times the nozzles No. 1 and No. 9 are used is two.

  In the conventional example shown in FIGS. 10B to 10F, only a pattern in which one dot is positioned at the upper left of the 2 × 2 dot matrix as shown in FIG. 10A is fixedly used. Therefore, even if the halftone density is increased, the nozzle use frequency is only uniform every other nozzle as shown in FIG. 10F, and only nozzles with an odd nozzle number are used. As a result, the deterioration of the specific nozzle that is frequently used is strongly reflected in the recorded image. The deterioration of the nozzle causes, for example, a variation in the ink ejection direction called “jore”, a variation in the ink ejection amount called “shobo”, and finally a non-ejection of the ink.

  When a deteriorated nozzle such as an ink ejection defect appears with high periodicity, one of the nozzle number L and the nozzle number K is an integral multiple of the other, that is, K = L × a (a is a natural number), or L = K. The relationship of xb (b is a natural number) is established. K is the number of nozzles of the recording head corresponding to the conveyance amount of the recording medium between the recording scans before and after the recording head. That is, in the serial scan type inkjet recording apparatus that alternately repeats the recording scan in the main scanning direction of the recording head and the conveyance of the recording medium in the sub-scanning direction (the direction along the nozzle arrangement direction), the latter recording The number of nozzles of the recording head corresponding to the medium transport amount is K. L is the size of the gradation pattern of the systematic dither method in the nozzle arrangement direction, and corresponds to the number of nozzles.

  For example, when recording is performed by using a recording head in which 1280 nozzles are arranged in the sub-scanning direction and intermittently transporting the recording medium by 1280 nozzles, K = 1280. In this case, when a gradation pattern as shown in FIG. 13, that is, a gradation pattern with a size L corresponding to the number of nozzles in the nozzle arrangement direction as shown in FIG. 17 is used, K = L × 80, Deteriorated nozzles appear with high periodicity as shown in FIG. On the contrary, when the size L of the gradation pattern is larger than K, the deteriorated nozzle appears with the same periodicity when L = K × b (b is a natural number).

An object of the present invention is to prevent a specific nozzle of a recording head from being used in a concentrated manner when performing gradation recording using a gradation pattern (dither matrix) of a general systematic dither method. An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording system that can perform stable recording for a long period of time by extending image degradation and the life of nozzles themselves.

The ink jet recording apparatus of the present invention includes a plurality of inks for ejecting ink of the same color according to image data that has been n-valued by a systematic dither method that performs n-value (n ≧ 3) processing using a dither matrix. In an inkjet recording apparatus that records an image on a recording medium by ejecting ink from a recording head in which nozzles are arranged, main scanning means for main-scanning the recording head in the main scanning direction with respect to the recording medium; Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scanning direction by the number of nozzles K (where K = a × L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or a certain amount corresponding to K = L / b (b is a natural number)) And conveying means for creating transmission among the plurality of nozzles, the end of the downstream side, less H than the L (H is an integer of 0 or more) and disable the number of nozzles, can use the remaining nozzles After the first main scan in which recording is performed, the predetermined amount of conveyance is performed by the conveyance unit, and thereafter, the main scanning is performed in which the plurality of nozzles are usable, and the certain amount of conveyance is performed by the conveyance unit; The main scanning means, the conveying means, and the control means for controlling the recording head so that a mode for recording an image for one page is executed by repeating the above, the control means includes the H The value can be changed.

The ink jet recording apparatus of the present invention includes a plurality of inks for ejecting ink of the same color according to image data that has been n-valued by a systematic dither method that performs n-value (n ≧ 3) processing using a dither matrix. In an inkjet recording apparatus that records an image on a recording medium by ejecting ink from a recording head in which nozzles are arranged, main scanning means for main-scanning the recording head in the main scanning direction with respect to the recording medium; Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scanning direction by the number of nozzles K (where K = a × L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or a certain amount corresponding to K = L / b (b is a natural number)) (I) a first mode in which an image for one page is recorded by repeating main scanning for recording with the plurality of nozzles usable and the predetermined amount of transport by the transport unit; (Ii) Among the plurality of nozzles, the number of nozzles less than L at the end on the downstream side in the transport direction is disabled, and after the first main scan in which recording is performed with the remaining nozzles enabled Then, the predetermined amount of conveyance is performed by the conveyance unit, and thereafter, the main scanning for performing the recording with the plurality of nozzles being usable and the conveyance of the certain amount by the conveyance unit are repeated, whereby an image for one page is obtained. And a second mode for selectively executing the second mode.

The inkjet recording system of the present invention includes a quantization means for quantizing input image data into n-value (n ≧ 3) image data by a systematic dither method using a dither matrix, and a quantization process by the quantization means. Selection means for selecting a dot pattern corresponding to the gradation value based on the gradation value of the image data, a main scanning means for main scanning the recording head in the main scanning direction, and a dot selected by the selection means Driving means for driving the recording head so that ink is ejected from a recording head in which a plurality of nozzles for ejecting ink of the same color are arranged during main scanning by the main scanning means according to a pattern; Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scan direction. Equivalent to K (where K = a × L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or K = L / b (b is a natural number)). conveying means for conveying by a predetermined amount, among the plurality of nozzles, the end of the downstream side, the less H than L (H is an integer of 0 or more) and disable the number of nozzles, the remaining After the first main scan in which printing is performed with the nozzles usable, the fixed amount is transported by the transport unit, and then the constant scan by the transport unit and the main scan in which recording is performed with the plurality of nozzles usable. The main scanning means, the conveying means, and the control means for controlling the recording head so that a mode for recording an image for one page is executed by repeating the conveyance of the amount, and the control means , Characterized in that it is capable of changing the values of the serial H.

The inkjet recording system of the present invention includes a quantization means for quantizing input image data into n-value (n ≧ 3) image data by a systematic dither method using a dither matrix, and a quantization process by the quantization means. Selection means for selecting a dot pattern corresponding to the gradation value based on the gradation value of the image data, a main scanning means for main-scanning the recording head in the main scanning direction, and a dot selected by the selection means Driving means for driving the recording head so that ink is ejected from a recording head in which a plurality of nozzles for ejecting ink of the same color are arranged during main scanning by the main scanning means according to a pattern; Between the previous main scanning and the next main scanning of the recording head by the main scanning means, the recording medium is moved in the transport direction intersecting the main scanning direction. Equivalent to K (where K = a × L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or K = L / b (b is a natural number)). And (i) main scanning for performing recording with the plurality of nozzles usable, and the predetermined amount of conveyance by the conveying unit are repeated to record an image for one page. The first mode, and (ii) among the plurality of nozzles, the number of nozzles less than L at the end on the downstream side in the transport direction is disabled, and recording is performed with the remaining nozzles usable. After the main scanning, the predetermined amount of conveyance is performed by the conveying unit, and thereafter, the main scanning in which recording is performed with the plurality of nozzles being usable and the certain amount of conveyance by the conveying unit are repeated, thereby repeating 1 page And a means for selectively executing the second mode for recording the minute image.

According to the present invention, when gradation recording is performed using a gradation pattern (dither matrix) of a systematic dither method, it is possible to equalize the frequency of use of all nozzles in the recording head.

As a result, it is possible to avoid that the characteristics of a specific nozzle are strongly reflected in a recorded image having a specific gradation value. In addition, it is possible to reduce the occurrence of recording image quality deterioration due to deterioration of the specific nozzle .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an image processing system which is a representative embodiment of the present invention. In FIG. 1, reference numeral 30 denotes an image input unit for inputting multi-value image data from an image input device such as a scanner or a digital camera, or multi-value image data stored in various recording media such as a hard disk. Reference numeral 31 denotes an image processing unit that performs multi-valued image data input from the image input unit 30 and performs image processing to be described later to convert it into n-valued image data. An image output unit 32 inputs n-value image data converted by the image processing unit 31 to form an image. Although not shown in the figure, each part of the system includes a CPU that controls the operation of each part and a cooperative operation with other parts, a ROM that stores a control program executed by the CPU, A RAM used as a work area for executing the control program is mounted.

  FIG. 2 is an external perspective view showing a schematic configuration of an ink jet recording apparatus that is a representative example of the image output unit 32.

  In FIG. 2, 11 is a carriage, and a head cartridge in which a recording head and an ink tank for storing ink are integrated is detachably mounted. Reference numeral 12 denotes a carriage motor that reciprocates the carriage 11 in the main scanning direction indicated by an arrow X. Reference numeral 4 denotes a belt that transmits the driving force of the carriage motor 12 to the carriage 11. Reference numeral 6 denotes a guide that supports the carriage 11 so as to be movable in the main scanning direction. It is a shaft. The belt 4 is bridged between the pulleys 5a and 5b. 13 is a flexible cable for transferring an electrical signal from a control unit, which will be described later, to the recording head, 15 is a cassette for storing recording media (for example, recording sheets) in a stacked state, and 16 is an optical position of the carriage 11. This is an encoder 16 for reading automatically. The recording medium in the cassette 15 is transported in a sub-scanning direction indicated by an arrow Y that intersects the main scanning direction by a transport mechanism (not shown).

  Reference numerals 141 and 143 denote caps and wiper blades used for performing a recovery process of the recording head. The recovery process is a process for maintaining a good ink discharge state of the recording head, and may include a discharge recovery process, a suction recovery process, wiping, and the like. The ejection recovery process is a recovery process in which ink that does not contribute to image recording is ejected from the ejection port of the recording head to the cap 141. The suction recovery process is a recovery process in which negative pressure is introduced into the cap 141 capping the ejection port of the recording head, and ink is sucked and discharged from the ejection port of the recording head. Wiping is a process of wiping the ejection port formation surface of the recording head with the wiper blade 143. These capping, wiping (cleaning), and suction recovery are performed when the carriage 11 is moved to a predetermined home position side area, and can also be performed at a known timing.

  Next, the configuration of the control system of such a recording apparatus will be described.

  FIG. 3 is a block diagram illustrating a schematic configuration of a control circuit of the recording apparatus. In the figure, 1700 is an interface for inputting a recording signal, 1701 is a CPU, 1702 is a ROM for storing a control program executed by the CPU 1701, an error processing program, and the like, and 1703 is various data (supplied to the recording signal and the recording head 22). The recording data etc.) is temporarily stored. Reference numeral 1704 denotes a gate array (GA) that controls supply of print data to the print head 22 and also controls data transfer among the interface 1700, the CPU 1701, and the RAM 1703. Reference numeral 12 denotes a carriage motor for moving the recording head 22 in the main scanning direction. Reference numeral 1709 denotes a conveyance motor for conveying the recording medium in the sub-scanning direction. Reference numeral 1705 denotes a head driver for driving the recording head 22, and reference numerals 1706 and 1707 denote motor drivers for driving the transport motor 1709 and the carriage motor 12, respectively.

  When a recording signal is input to the interface 1700, the recording signal is converted into recording data for printing between the gate array 1704 and the CPU 1701. Then, the motor drivers 1706 and 1707 are driven, and the recording head 22 is driven in accordance with the recording data sent to the head driver 1705 to perform recording. The recording head 22 records an image by ejecting ink droplets from the ink ejection ports constituting the nozzles and depositing the ink on a recording medium. As one of the ink ejection methods in the recording head, a state in which the ink undergoes a sudden volume change (bubble generation) by applying an electrical signal to a heating element (electrothermal converter) disposed in the vicinity of the ejection port. There is a system in which a change is caused and ink is ejected from an ejection port by an action force based on this state change. As another ink ejection method, there is a method in which a piezoelectric element or the like (electrical / mechanical conversion element) is used and ink is ejected from an ejection port by a change in ink pressure due to mechanical fluctuation.

  4 is a perspective view showing in more detail the configuration of the vicinity of the carriage of the recording apparatus in FIG.

  The recording head 22 shown in FIG. 4 uses six color inks of black (K), light cyan (LC), dark cyan (C), light magenta (LM), dark magenta (M), and yellow (Y). The recording heads 22K, 22LC, 22C, 22LM, 22M, and 22Y are configured to be ejected. The ink tank 21 includes ink tanks 21K, 21LC, 21C, 21LM, 21M, and 21Y that store the inks of the respective colors supplied to the recording heads 22, respectively. The cap 141 includes six caps 141K, 141LC, 141C, 141LM, 141M, and 141Y in order to cap the respective ejection port forming surfaces (surfaces on which the ink ejection ports are formed) of the recording head 22. Yes. Reference numeral 3 denotes a conveyance roller for conveying the recording medium 1 in the sub-scanning direction.

  In the case of this example, the recording cartridge 22 and the ink tank 21 constitute a head cartridge. In the head cartridge, the recording head 22 and the ink tank 21 may be configured integrally, or may be configured such that they can be separated.

  FIG. 5 is a view of the recording head 22 as viewed from the ejection port 23 side.

  As shown in FIG. 5, each of the recording heads 22 has 1280 ejection ports 23 formed in a row at intervals corresponding to a recording density of 1200 dpi. These six recording heads 22 are arranged in the main scanning direction. The amount of ink discharged from each discharge port 23 is about 4 ng.

  FIG. 6 is a block diagram of the image processing unit 31 in FIG.

6, 40, which are input data correcting unit der. Reference numeral 41 denotes a quantization unit, which performs “N” by a systematic dither method in which the multilevel image data corrected by the input data correction unit 40 is performed using a dither matrix (for example, a gradation pattern as shown in FIG. 13). Quantize to the tone value of the value. This N value is determined by the relationship between the input resolution and the output resolution. For example, when the input resolution is 300 dpi and the output resolution is 600 dpi, the output data dots are 2 × 2 4 dots per block for the input image data of 8 bits per pixel. The number of gradations that can be expressed by one block is five. Therefore, the quantization unit 21 outputs a quantized value quantized into five values of “0”, “64”, “128”, “192”, and “255”. Each quantized value corresponds to the gradation values “0”, “1”, “2”, “3”, “4”.

  A dot pattern development unit 44 selects a dot pattern to be used for output from a plurality of dot patterns corresponding to each gradation value based on the gradation value quantized by the quantization unit 41. The selected desired dot pattern is acquired from the dot pattern storage unit 45. The dot pattern storage unit 45 stores a plurality of dot patterns corresponding to each gradation value. The dot pattern storage unit 45 selects a desired dot pattern from a plurality of dot patterns based on the dot pattern selection information input from the dot pattern development unit 44 and outputs the selected dot pattern to the dot pattern development unit 44. To do. The dot pattern storage unit 45 is provided in a semiconductor memory such as an EEPROM. However, in the image recording apparatus of the present invention, it may be copied and used in a high-speed memory such as an SRAM in consideration of high-speed processing. .

  In this embodiment, the dot pattern stored in the dot pattern storage unit 45 has a 2 × 2 dot size pattern for each gradation value. That is, as shown in FIGS. 14A to 14E, 2 × 2 dots are independently provided for each of the gradation values “0”, “1”, “2”, “3”, and “4”. It has a dot pattern table of size.

  Next, a recording operation in the recording apparatus having the above configuration will be described.

  Ink is supplied from the ink tank 21 to the recording head 22, and the recording head 22 ejects ink onto the recording paper 1 according to the image signal while moving in the main scanning direction. As a result, an image corresponding to the width W corresponding to the number of ejection ports 23 in the recording head 22 is recorded. This recording is performed by driving the recording head 22 based on the image signal in accordance with the reading timing of the encoder 16 to eject and deposit ink droplets on the recording paper 1. After the recording for one scan (n-th scan in FIG. 7) is completed, before the next scan (n + 1-th scan in FIG. 7) using the next image data is started, the transport roller pair 3 is driven to convey the recording paper 1 intermittently by a predetermined amount K in the sub-scanning direction.

  In this way, recording is performed on the recording paper 1 by repeating the recording operation for one scan and the conveyance of the recording paper 1 of a predetermined amount K.

  FIG. 8 is a diagram illustrating an example of the relationship between the ejection ports 23 of the recording head 22 and the arrangement of dots D formed on the recording paper 1 by the ink ejected from the ejection ports 23. In this embodiment, the dot pattern size is set to 2 × 2 dots for the sake of simplicity of description, but of course the dot pattern size applicable in the present invention is not limited to this, and other sizes are also available. The dot pattern may be used.

In this embodiment, by using the dot pattern of the gradation pattern and the 2 × 2 dots dither method performs gradation representation. In this embodiment, the dot pattern is changed for each scan of the recording head.

  Hereinafter, the dot pattern in the present embodiment will be specifically described.

  FIGS. 9B to 9F show images of halftone densities (duty 5%, 10%, 15%, 25%) using the gradation pattern shown in FIG. 13 and the dot pattern in this embodiment. Indicates the frequency of nozzles used (ink ejection). Again, in order to simplify the explanation and to make the feature of the effect stand out, as shown in FIG. 9A, a dot pattern in which only one dot is arranged in a 2 × 2 dot matrix, that is, 5 It is assumed that a dot pattern indicating a gradation value “1” among gradation values quantized into values is used. 9B to 9F, the number of times representing the nozzle use (ink ejection) frequency appears with periodicity according to the size of the gradation pattern of the systematic dither method in FIG. This is the number of times (probability) of using the nozzles used when a 16 × 16 dot area is recorded.

  As in the conventional examples of FIGS. 10B to 10F described above, images with halftone densities (duty 5%, 10%, 15%, 25%) were recorded on the assumption that various images were recorded. In this case, as shown in FIG. 10A, only a pattern in which one dot is positioned at the upper left of the 2 × 2 dot matrix is fixedly used. Therefore, even if the halftone density is increased, the nozzle use frequency is only uniform every other nozzle as shown in FIG. 10F, and only nozzles with an odd nozzle number are used. Therefore, the deterioration of the specific nozzle that is frequently used is strongly reflected in the recorded image. The deterioration of the nozzle causes, for example, a variation in the ink ejection direction called “jore”, a variation in the ink ejection amount called “shobo”, and finally a non-ejection of the ink.

  In the case of the present embodiment shown in FIGS. 9B to 9F, as shown in FIG. 9A, as a dot pattern having a gradation value “1”, one dot is formed at the upper left of the 2 × 2 dot matrix. The first dot pattern in which is located and the second dot pattern in which one dot is located in the lower right of the 2 × 2 dot matrix are used. When the first dot pattern is used, nozzles with an odd nozzle number are used, and when the second dot pattern is used, nozzles with an even nozzle number are used. Such first and second dot patterns are used interchangeably each time the recording head 22 performs one scan. As a result, ink is ejected from nozzles with odd and even nozzle numbers, and the frequency of use of all nozzles in the recording head 22 is equalized.

  Note that the process using such a dot pattern is executed by the dot pattern development unit 44 and the dot pattern storage unit 45 shown in FIG. However, such processing may be realized by a dedicated logic circuit, or may be realized by the CPU executing a processing program. The developed dot pattern is transferred to an ink jet printer, and recording is performed by the recording head 22 ejecting ink based on the designated dot pattern.

  As described above, in this embodiment, when recording is performed by ejecting ink from the recording head 22 based on the dot pattern corresponding to the quantized gradation value, the ink ejection is performed even with the same gradation value. A plurality of dot patterns are prepared for the same gradation value so that the nozzles for performing the above are not concentrated on the same nozzle. A plurality of dot patterns prepared for the same gradation value are changed at a predetermined timing (in this embodiment, every scan of the recording head 22), and different dot patterns are selectively used. As a result, the used nozzles can be distributed over a plurality of nozzles. Thereby, it is possible to prevent the characteristics of a specific nozzle from being strongly reflected in a recorded image having a specific gradation value. For example, it is possible to reduce the occurrence of a phenomenon of image quality deterioration due to deterioration of a specific nozzle in a recorded image. When the nozzle is deteriorated, a variation in the direction of ink ejection called “jore”, a variation in the amount of ink ejection called “shobo”, and finally a non-ejection of ink occur.

  In the above embodiment, the dot pattern change timing is set for each scan of the recording head 22, but according to this configuration, it is necessary to switch the dot pattern in real time as compared with the change timing disclosed in Patent Document 1. This is preferable in that the hardware configuration can be simplified and the cost of the main body can be reduced.

  In this embodiment, the dot pattern change timing is not limited for each scan. For example, when the dot arrangement cannot be changed within the range of one page of the recording paper 1 on which an image is recorded, all nozzles in the recording head 22 are increased as the number of pages increases by changing the dot pattern for each page. The usage frequency can be equalized. Similarly, even if the dot pattern is changed in units of jobs or recording units by the user, the used nozzles can be equalized.

  When the dot pattern is changed in units of pages, a slight difference in image quality due to switching of the dot patterns becomes in units of pages, so that it becomes less noticeable. In addition, when the dot pattern is changed in units of jobs, a slight difference in image quality due to switching of the dot patterns becomes in units of jobs, so that it becomes less noticeable. Further, when the dot pattern is changed in units of recording copies, a slight difference in image quality due to switching the dot patterns becomes units of recording copies, so that it becomes less conspicuous.

  In this embodiment, the dot pattern is a 2 × 2 dot pattern, but is not limited thereto. For example, in order to disperse the used nozzles in the dot matrix, a dot matrix in which four dot patterns of 2 × 2 dots are arranged as shown in FIG. However, since the number of times representing the nozzle use (ink ejection) frequency appears with periodicity according to the size of the gradation pattern of the systematic dither method as shown in FIG. 13, the used nozzles may be concentrated on a specific nozzle. . Also in this case, as in the case of the present embodiment, the dot pattern shown in FIG. 16A and the dot pattern shown in FIG. 16B different from the dot pattern shown in FIG. The nozzles can be equalized.

  After all, in this embodiment, when using a dot pattern corresponding to a gradation pattern of a systematic dither method that has been generally used conventionally, the dot pattern is changed for each scan of the recording head 22. The image deterioration due to the deviation of the used nozzles, which has been a problem in recent inkjet apparatuses, has been solved.

(Second embodiment)
In the above embodiment, when performing the gradation expression by using the gradation patterns of systematic dither method and (dither matrix) and a dot pattern, it changes its dot pattern for each scan of the recording head 22. As described above, the dot pattern change timing may be any one of the print scanning unit, the page unit, the print job unit, or the print number unit. In the present embodiment, in addition to the change of the dot pattern, the correspondence relationship between the nozzles of the recording head 22 and the recording data is changed for each page of the recording paper. Thereby, even when the halftone density of the recorded image is low, the use frequency of all the nozzles in the recording head 22 can be more evenly equalized. Further, in this embodiment, the timing for changing the correspondence between the nozzles of the recording head 22 and the recording data may be in units of recording jobs or in units of recording copies in addition to the units of pages. It can also be matched with the pattern change timing. In this embodiment, the frequency of use of all the nozzles in the recording head 22 can be changed by simply changing the correspondence between the nozzles of the recording head 22 and the recording data for each page of the recording paper without combining with the above-described embodiment. Can be more evenly distributed.

  Hereinafter, the present embodiment will be specifically described.

  FIGS. 11B to 11F show the frequency of nozzles used (ink ejection) when an image having a halftone density (duty 5%, 10%, 15%, 25%) is recorded in this embodiment. Indicates. As in the previous embodiment, here, in order to simplify the description and to highlight the features of the effect, only one dot is placed in the 2 × 2 dot matrix as shown in FIG. It is assumed that a dot pattern to be arranged, that is, a dot pattern showing a gradation value “1” among gradation values quantized into five values is used. 11B to 11F, the number of times representing the nozzle use (ink ejection) frequency appears with periodicity according to the size of the gradation pattern of the systematic dither method in FIG. This is the number of times (probability) of using the nozzles used when a 16 × 16 dot area is recorded.

  In addition to the conventional example of FIGS. 10B to 10F, the dot pattern is changed for each scan of the recording head 22 as in the embodiment of FIGS. Even when equalization is performed, when an image with a thin halftone density is recorded, the tendency of the used nozzles to concentrate on a specific nozzle cannot be avoided. This is because the tendency is caused by the threshold value in the gradation pattern of the systematic dither method.

  In the present embodiment, in order to ensure equalization of the frequency of use of all nozzles in the printhead 22, the first and first scans are performed for each scan of the printhead 22 as in the embodiments of FIGS. In addition to the process of changing the dot pattern of 2, as shown in FIGS. 12A and 12B, the process of changing the position of the used nozzle in the recording head 22 is also performed for each page of the recording paper. In this embodiment, for the sake of simplicity of explanation, the same recording method as in FIG. 7, that is, by scanning the recording head 22 once, the width W corresponding to the number of ejection ports 23 in the recording head 22 ( A one-pass recording method for completing an image with a width of 1280 nozzles) was adopted.

  First, when the image of the first page is recorded, in the first scan, the recording of the width W for 1280 nozzles of the recording head 22 is performed as usual, and in the second and subsequent scans, the first scan is recorded. Recording is performed with a width W corresponding to 1280 nozzles of the recording head 22 so as to be sequentially continuous with the image. As a result, an image is recorded on the first page of the recording paper.

  Next, when the image of the second page is recorded, in the first scan, null (NULL) data (ink is ejected) as image data for two nozzles on the upper end side in all 1280 nozzles corresponding to the width W of the recording head 22. Data), and the image data is shifted downward in the correspondence relationship with the nozzles by the added two nozzles. Then, the width (W−W1) corresponding to the remaining 1278 nozzles is recorded without recording the width W1 corresponding to the two upper end nozzles. Therefore, when the nozzle numbers 1 to 1280 are assigned from the upper side to the lower side in FIG. 12, the original image data corresponding to the nozzle numbers 1 to 1278 is the nozzle numbers 3 to 1280 in the first scan. Therefore, the original image data corresponding to the nozzles having the nozzle numbers 1279 and 1280 are associated with the nozzles having the nozzle numbers 1 and 2 in the next second scan. Therefore, in the second and subsequent scans, the image data corresponding to the nozzles 1279 and 1280 in the previous scan are associated with the nozzles 1 and 2. As described above, after the second scan, printing with a width W of 1280 nozzles is performed as usual so as to be sequentially continuous with the print image of the first scan. As a result, an image is recorded on the second page of the recording paper.

  Next, when the image of the third page is recorded, in the first scan, null data (data that does not eject ink) is used as image data for four nozzles on the upper end side in all 1280 nozzles corresponding to the width W of the recording head 22. The image data is shifted downward in correspondence with the nozzles by the added four nozzles. Then, the width for the remaining 1276 nozzles is recorded without recording the width for the upper four nozzles. Therefore, in the first scan, the original image data corresponding to the nozzles having the nozzle numbers 1 to 1276 are associated by the nozzles having the nozzle numbers 5 to 1280, and the original image corresponding to the nozzles having the nozzle numbers 1277 to 1280 is obtained. Data is associated with the nozzles of nozzle numbers 1 to 4 at the next second scan. Therefore, after the second scan, the image data corresponding to the nozzles 1277 to 1280 in the previous scan are associated with the nozzles 1 to 4. As described above, after the second scan, printing with a width W of 1280 nozzles is performed as usual so as to be sequentially continuous with the print image of the first scan. As a result, an image is recorded on the third page of the recording paper.

  Similarly, in the first scan of image recording on the fourth, fifth, sixth, and seventh pages, null data is added as image data for the 6, 8, 10, 12 nozzles on the upper end side, and the added 6, 8 , 10 and 12 nozzles, the image data is shifted downward, and recording is performed for the widths of 1274, 1272, 1270 and 1268 nozzles. In the first scan of image recording on the eighth page, null data is added as image data for the 14 nozzles on the upper end side, and the image data is shifted downward by the added 14 nozzles to have a width of 1266 nozzles. Make a record.

  In the present embodiment, the recording operation is repeated with such image recording of the first to eighth pages as one cycle. That is, each time an image for one page is recorded, the correspondence between the nozzle and the image data is changed by two nozzles, and the change between the nozzle and the image data is performed seven times until the image for eight pages is recorded. The correspondence is shifted by a total of 14 (= 2 × 7) nozzles. Accordingly, in the image recording for the 1st to 8th pages, the shift amount of the correspondence relationship between the nozzles and the image data is changed by 0, 2, 4, 6, 8, 10, 12, 14 nozzles, and this is set as one cycle. The image recording for the ninth and subsequent pages is repeated. For this reason, the shift amount of the correspondence relationship between the nozzle and the image data is inevitably smaller than the size L (= 16) in the sub-scanning direction of the gradation pattern as shown in FIGS. Further, by changing the correspondence between the nozzles of the recording head 22 and the recording data for each page of the recording paper in this way, an image is formed at the leading end of the recording paper 1 by the amount of null data added in the first scan. There will be a blank space that is not recorded. The margin generated by the addition of such null data is a slight width corresponding to 14 rasters with a maximum of 14 nozzles. Therefore, the shift of the image recording position is not so noticeable, but it is preferable that there is no shift. Therefore, in order to completely eliminate the shift in the recording position of the image, the blank for the null data may be set in the blank area at the leading end of the recording paper 1. For example, in the first scan, by assigning null data to the end nozzles that pass through the blank area at the leading edge of the recording paper 1, the blank generated by the addition of null data is reduced within the blank area at the leading edge of the recording paper 1. Can be set to As a method for realizing this, the transport amount of the recording paper 1 in the cueing operation up to the recording start position is controlled for each page based on the amount of added null data, and the nozzle to which the null data is assigned is set to the front end of the recording paper 1. For example, a method of positioning in a blank area in a part is used. More specifically, the carry amount in the cueing operation is controlled to be small as the amount of added null data increases so that the width of the blank area becomes the same for each page.

  As a result, the nozzle use frequencies in FIGS. 9B to 9F are dispersed as shown in FIGS. 11B to 11F, and the use frequencies of all the nozzles in the recording head 22 are surely equalized. Can do. For example, in the case of FIG. 9B, four nozzles (nozzle numbers 1, 2, 9, and 20) out of 16 nozzles are used once for a total of four times, whereas FIG. In this case, a total of four nozzle uses are distributed to 16 nozzles, and as a result, the usage frequency per nozzle is equalized to 0.25.

  By equalizing the frequency of use of the nozzles in this way, it is possible to avoid that the characteristics of a specific nozzle are strongly reflected in characters such as documents and recorded images having a low density of illustration. In addition, it is possible to reduce the occurrence of recording image quality deterioration due to deterioration of the specific nozzle. When the nozzle is deteriorated, for example, there is a possibility that a variation in the ink ejection direction referred to as “jore”, a variation in the amount of ink ejection referred to as “shobo”, or an ink non-ejection may occur.

  In this embodiment, the timing for changing the position of the nozzle used by the print head in the first scan is set for each page of the print image, but the present invention is not limited to this. For example, when the position of the nozzle used for the first scan of the recording head cannot be changed for each page of the recording paper on which the image is recorded, the position of the nozzle used for the first scan of the recording head is set in units of recording units. Changes may be made. In that case, the usage frequency of all the nozzles in the recording head is equalized as the recording over a long period of time increases.

  In this embodiment, a dot pattern of 2 × 2 dots is used as a dot pattern corresponding to a gradation pattern of a systematic dither method generally used conventionally, and the dot pattern is changed for each scanning of the recording head. In addition, the position of the nozzle used in the first scan of the recording head was changed for each page of the recording image. Thereby, it was possible to solve the image deterioration due to the deviation of the used nozzles, which has been a problem in recent ink jet recording apparatuses.

  In this embodiment, since a 2 × 2 dot pattern is used, the position of the nozzle used in the first scan of the recording head is changed in units of two nozzles, but the present invention is not limited to this. The position of the nozzle used in the first scan of the recording head may be adjusted to the vertical size of the dot pattern, or the same effect can be obtained even if it is changed in units of one nozzle.

  Further, in order to shift the correspondence between the nozzles and the image data, the null data is used as in this embodiment, or the function of a predetermined number of nozzles is disabled, and the image data is shifted by the disabled nozzles. Good. In short, it is only necessary that the correspondence between the nozzles and the image data can be shifted. Further, the timing for shifting the correspondence between the nozzles and the image data may be in units of print jobs or units of prints in addition to page units. Further, as described above, the dot pattern change timing may be any one of a print scanning unit, a page unit, a print job unit, or a print number unit. As an example of a specific form of the recording operation, a form in which the null data is used, the correspondence between the nozzles and the image data is shifted in units of pages, and the dot pattern is changed in units of pages.

  If the relationship between the nozzle and image data is shifted and the dot pattern is changed in units of pages, the relationship between the nozzle and image data and the slight difference in image quality due to the switching of the dot pattern will be in units of pages, making it less noticeable. Become. Also, if the relationship between the nozzle and image data is shifted and the dot pattern is changed in units of jobs, the relationship between the nozzle and image data and the slight difference in image quality due to switching of the dot pattern will be in units of jobs. Less noticeable. In addition, when the relationship between the nozzle and the image data is shifted and the dot pattern is changed in units of recording units, the relationship between the nozzle and the image data and the slight difference in image quality due to the switching of the dot patterns is in units of recording units. So it becomes less noticeable.

(Other)
The present invention can be applied to all recording apparatuses using recording media such as paper, cloth, non-woven fabric, and OHP film, and specific application apparatuses include office machines such as printers, copiers, facsimiles, mass production machines, and the like. be able to.

  In the above embodiment, the liquid droplets ejected from the recording head have been described as ink, and the liquid stored in the ink tank has been described as ink. However, the container is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  In addition, the above-described embodiment includes means (for example, an electrothermal converter, a laser beam, etc.) that generates thermal energy as energy used for performing ink ejection, particularly in the ink jet recording system, and the thermal energy By using a system that causes a change in the state of the ink, it is possible to achieve higher recording density and higher definition.

  As its typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recording information and applying a rapid temperature rise exceeding the film boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because film boiling occurs on the heat acting surface of the liquid and, as a result, bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening to form at least one droplet. When the drive signal is pulse-shaped, the bubble growth and contraction is performed immediately and appropriately, and thus it is possible to achieve the discharge of the liquid (ink) with particularly excellent responsiveness, which is more preferable.

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

  As the configuration of the recording head, in addition to the combination configuration (straight liquid flow path or right-angle liquid flow path) of the discharge port, the liquid path, and the electrothermal transducer as disclosed in each of the above-mentioned specifications, the heat acting surface The configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which is disposed in a bending region, are also included in the present invention. In addition, Japanese Patent Application Laid-Open No. 59-123670, which discloses a configuration in which a common slot is used as a discharge portion of an electrothermal transducer, or an opening that absorbs a pressure wave of thermal energy is discharged to a plurality of electrothermal transducers A configuration based on Japanese Patent Laid-Open No. 59-138461 disclosing a configuration corresponding to each part may be adopted.

  Furthermore, as 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, the length is satisfied by a combination of a plurality of recording heads as disclosed in the above specification. Either a configuration or a configuration as a single recording head formed integrally may be used.

  In addition to the cartridge-type recording head in which the ink tank is integrally provided in the recording head itself described in the above embodiment, it can be electrically connected to the apparatus body by being attached to the apparatus body. A replaceable chip type recording head that can supply ink from the apparatus main body may be used.

  In addition, it is preferable to add recovery means, preliminary means, and the like for the recording head to the configuration of the recording apparatus described above because the recording operation can be further stabilized. Specific examples thereof include a capping unit for the recording head, a cleaning unit, a pressurizing or sucking unit, an electrothermal converter, a heating element different from this, or a preheating unit using a combination thereof. In addition, it is effective to provide a preliminary ejection mode for performing ejection different from recording in order to perform stable recording.

  Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrated or may be a combination of a plurality of colors. An apparatus having at least one of full colors can also be provided.

  In the embodiment described above, the description is made on the assumption that the ink is a liquid, but it may be an ink that is solidified at room temperature or lower, or an ink that is softened or liquefied at room temperature, Alternatively, in the ink jet system, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within a stable discharge range. Any material may be used if it is liquid.

  In addition, it is solidified in a stand-by state in order to actively prevent temperature rise by heat energy as energy for changing the state of ink from the solid state to the liquid state, or to prevent ink evaporation. Ink that is liquefied by heating may be used. In any case, by applying heat energy according to the application of thermal energy according to the recording signal, the ink is liquefied and liquid ink is ejected, or when it reaches the recording medium, it already starts to solidify. The present invention can also be applied to the case of using ink having the property of being liquefied for the first time. In such a case, the ink is held as a liquid or solid in a porous sheet recess or through-hole as described in JP-A-54-56847 or JP-A-60-71260, It is good also as a form which opposes with respect to an electrothermal converter. In the present invention, the most effective one for each of the above-described inks is to execute the above-described film boiling method.

  In addition, as a form of the recording apparatus according to the present invention, a copying apparatus combined with a reader or the like as well as an image output terminal of an information processing device such as a computer or a separate apparatus, and a transmission / reception function are provided. It may take the form of a facsimile machine.

  Note that the present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), or an apparatus composed of a single device (for example, a copier, a facsimile machine, etc.). You may apply.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

1 is a block diagram illustrating a schematic configuration of an image processing system according to an embodiment of the present invention. 1 is an external perspective view of an inkjet recording apparatus to which the present invention can be applied. FIG. 3 is a block configuration diagram of a control system in the recording apparatus of FIG. 2. FIG. 3 is a perspective view of a vicinity of a carriage in the recording apparatus of FIG. 2. FIG. 5 is a diagram when the recording head in FIG. 4 is viewed from the discharge port side. FIG. 2 is a block configuration diagram of an image processing unit in FIG. 1. FIG. 6 is an explanatory diagram of a relationship between a recording width of a recording head and its recording scan. FIG. 4 is an explanatory diagram of a relationship between a nozzle of a recording head and an arrangement of dots formed by ink ejected from the nozzle. (A) is explanatory drawing of the two dot patterns used in the embodiment of the present invention, and (b) to (f) are when images of different densities are recorded using the two dot patterns of (a). It is explanatory drawing of the usage frequency of this nozzle. (A) is an explanatory diagram of one dot pattern used in the conventional example, and (b) to (f) are nozzles when images of different densities are recorded using one dot pattern of (a). It is explanatory drawing of usage frequency. (A) is explanatory drawing of two dot patterns used in other embodiment of this invention, (b)-(f) uses the two dot patterns of (a), and is a nozzle and image data. It is explanatory drawing of the usage frequency of a nozzle when changing the correspondence and recording the image of a different density | concentration. (A) is explanatory drawing of the relationship between the recording head at the time of recording the 1st page in other embodiment of this invention, and its scanning recording, (b) is the 2nd page in other embodiment of this invention. FIG. 6 is an explanatory diagram of a relationship between a recording head and its scanning recording when recording the image. It is explanatory drawing of an example of the gradation pattern of a systematic dither method. (A)-(e) is explanatory drawing of an example of the dot pattern of the gradation values 0-4. It is explanatory drawing of the deterioration nozzle which appears with periodicity in the recording head used for a long time with the conventional apparatus. (A) And (B) is explanatory drawing of the dot pattern from which the gradation value 1 differs which uses 4 dot patterns of 2x2 dots side by side. It is explanatory drawing of the correspondence of the gradation pattern used in a prior art example, a recording area, and the usage frequency of a nozzle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording paper 3 Conveying roller pair 4 Belt 6 Guide shaft 11 Carriage 12 Carriage motor 13 Flexible cable 15 Cassette 16 Encoder 21 Ink tank 22 Recording head 23 Discharge port 30 Image input part 31 Image processing part 32 Image output part 40 Input data correction part 41 Quantization unit 44 Dot pattern development unit 45 Dot pattern storage unit 141 Cap 143 Wiper blade 1700 Interface 1701 CPU
1702 ROM
1703 RAM
1704 G. A.
1705 Head driver 1706, 1707 Motor driver 1709 Conveyance motor

Claims (6)

From a recording head in which a plurality of nozzles for ejecting ink of the same color are arranged in accordance with image data that has been n-valued by a systematic dither method that performs n-value (n ≧ 3) processing using a dither matrix In an inkjet recording apparatus that records an image on a recording medium by ejecting ink,
Main scanning means for main-scanning the recording head in the main scanning direction with respect to the recording medium;
Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scanning direction by the number of nozzles K (where K = a × Transport means for transporting a certain amount corresponding to L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or K = L / b (b is a natural number);
Among the plurality of nozzles, the end of the downstream side, less H than the L (H is an integer of 0 or more) and disable the number of nozzles, the first for performing recording as possible using the remaining nozzles After the main scanning, the predetermined amount of conveyance is performed by the conveying unit, and then the main scanning for performing recording by making the plurality of nozzles usable, and the certain amount of conveying by the conveying unit are repeated. The main scanning means, the conveying means, and a control means for controlling the recording head so that a mode for recording an image for a page is executed,
The ink jet recording apparatus, wherein the control means can change the value of H. 2. The ink jet recording apparatus according to claim 1, wherein the control unit changes the value of H at any one of a page unit, a recording job unit, and a recording unit number. Selection means for selecting a dot pattern corresponding to the gradation value based on the gradation value of the n-valued image data;
Change means for changing a dot pattern selectable by the selection means so that a plurality of different dot patterns corresponding to the same gradation value are selectively used;
3. The ink jet recording apparatus according to claim 1, wherein the changing unit changes the selectable dot pattern at any one timing of a main scanning unit, a page unit, a recording job unit, and a recording unit number. . From a recording head in which a plurality of nozzles for ejecting ink of the same color are arranged in accordance with image data that has been n-valued by a systematic dither method that performs n-value (n ≧ 3) processing using a dither matrix In an inkjet recording apparatus that records an image on a recording medium by ejecting ink,
Main scanning means for main-scanning the recording head in the main scanning direction with respect to the recording medium;
Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scanning direction by the number of nozzles K (where K = a × Transport means for transporting a certain amount corresponding to L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or K = L / b (b is a natural number);
(I) a first mode in which an image for one page is recorded by repeating main scanning in which recording is performed with the plurality of nozzles usable and the predetermined amount of conveyance by the conveyance unit; (ii) the plurality of the plurality of nozzles Among the nozzles, the number of nozzles less than L at the end on the downstream side in the transport direction is disabled, and after the first main scan for recording with the remaining nozzles enabled, the transport means performs the A second mode in which an image for one page is recorded by repeating a certain amount of conveyance, and thereafter repeating main scanning for performing recording with the plurality of nozzles being usable and the predetermined amount of conveyance by the conveyance means. Means for selectively executing
An ink jet recording apparatus comprising: Quantization means for quantizing the input image data into n-value (n ≧ 3) image data by a systematic dither method using a dither matrix;
Selection means for selecting a dot pattern corresponding to the gradation value based on the gradation value of the image data quantized by the quantization means;
Main scanning means for main scanning the recording head in the main scanning direction;
In accordance with the dot pattern selected by the selection unit, the recording is performed so that ink is ejected from a recording head in which a plurality of nozzles for ejecting ink of the same color are arranged during main scanning by the main scanning unit. Driving means for driving the head;
Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scanning direction by the number of nozzles K (where K = a × Transport means for transporting a certain amount corresponding to L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or K = L / b (b is a natural number);
Among the plurality of nozzles, the end of the downstream side, less H than the L (H is an integer of 0 or more) and disable the number of nozzles, the first for performing recording as possible using the remaining nozzles After the main scanning, the predetermined amount of conveyance is performed by the conveying unit, and then the main scanning for performing recording by making the plurality of nozzles usable, and the certain amount of conveying by the conveying unit are repeated. The main scanning means, the conveying means, and a control means for controlling the recording head so that a mode for recording an image for a page is executed,
The ink jet recording system, wherein the control means can change the value of H. Quantization means for quantizing the input image data into n-value (n ≧ 3) image data by a systematic dither method using a dither matrix;
Selection means for selecting a dot pattern corresponding to the gradation value based on the gradation value of the image data quantized by the quantization means;
Main scanning means for main scanning the recording head in the main scanning direction;
In accordance with the dot pattern selected by the selection unit, the recording is performed so that ink is ejected from a recording head in which a plurality of nozzles for ejecting ink of the same color are arranged during main scanning by the main scanning unit. Driving means for driving the head;
Between the previous main scan and the next main scan of the recording head by the main scanning means, the recording medium is moved in the transport direction crossing the main scanning direction by the number of nozzles K (where K = a × Transport means for transporting a certain amount corresponding to L (a is a natural number, L is the number of nozzles corresponding to the size of the dither matrix in the transport direction), or K = L / b (b is a natural number);
(I) a first mode in which an image for one page is recorded by repeating main scanning in which recording is performed with the plurality of nozzles usable and the predetermined amount of conveyance by the conveyance unit; (ii) the plurality of the plurality of nozzles Among the nozzles, the number of nozzles less than L at the end on the downstream side in the transport direction is disabled, and after the first main scan for recording with the remaining nozzles enabled, the transport means performs the A second mode in which an image for one page is recorded by repeating a certain amount of conveyance, and thereafter repeating main scanning for performing recording with the plurality of nozzles being usable and the predetermined amount of conveyance by the conveyance means. Means for selectively executing
An ink jet recording system comprising:

Images