Inkjet recording device and inkjet recording method

Abstract

To solve such the problem that, when an inkjet recording device records an image, deviation of impact position of a discharged ink droplet may adversely impact on a width of a region where a recording object is formed.SOLUTION: An inkjet recording device suppresses deviation of impact position of an ink droplet relative to an edge region, thereby restricting simultaneous discharge from adjacent two nozzles supplied with ink from a common liquid chamber.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus and an inkjet recording method for recording an image on a recording medium.

Background Art

[0002] An inkjet recording apparatus records an image on a recording medium by repeatedly controlling the conveyance of the recording medium and scanning a carriage mounted with a recording head.

[0003] Patent Document 1 describes that when recording an image, in order to smooth the contour portions of characters, figures, etc., dots of a large size are changed to dots of a small size.

Prior Art Documents

Patent Documents

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, when recording an image with an inkjet recording apparatus, if ink ejection operations are simultaneously performed from adjacent nozzles, the ejection stability may decrease. When the ejection stability decreases, the accuracy of landing on the recording medium decreases, and it is conceivable that the ink lands at a position deviated from the position where the ink is originally intended to land. If such a deviation in the landing position causes rattling in the edge region of the recording target, the width of the recording target may change.

[0006] In view of such problems, an object of the present invention is to provide an inkjet recording apparatus capable of recording a recording object such that the width of the recording target becomes the width desired by the user.

Means for Solving the Problems

[0007] The present invention comprises a recording head having a plurality of nozzles arranged in a first direction for ejecting ink supplied from a common liquid chamber, and scanning means for performing relative scanning with a recording medium in a second direction intersecting the first direction. a line drawing extending in the first direction The width in the second direction is greater than a predetermined number of pixels. The width of the line drawing For the edge region, in one relative scan The recording head allows the use of either the odd-numbered nozzles or the even-numbered nozzles arranged in the first direction. , Control the ink ejection operation from the recording head to record without allowing the use of the other side. , A line drawing extending in the first direction, The width in the second direction is less than or equal to the predetermined number of pixels. The width of the line drawing For the edge region, in one relative scan, Odd-numbered The nozzle and the above Even-numbered nozzle Both use Allow recording so Before It is characterized by comprising control means for controlling the ejection of ink from the recording head. [Effects of the Invention]

[0008] The present invention makes it possible to record materials having a width desired by the user. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram of an inkjet printer. [Figure 2] Schematic diagram of the recording head 303 as observed from the nozzle formation surface. [Figure 3] Block diagram of the control configuration for an inkjet recording system. [Figure 4] Block diagram of the recording system overview [Figure 5] Flowchart of image data processing performed by an image processing device [Figure 6] Cross-sectional view of the ink flow path showing the ink flow in the recording head 303. [Figure 7] A diagram showing the barcode when the ink's targeting accuracy decreases. [Figure 8] This figure shows an example of assigning the number of ink droplets to binary data. [Figure 9] Flow chart for improving ejection stability in the first embodiment [Figure 10] Figure showing a barcode with improved ink landing accuracy in the first embodiment [Figure 11] Figure showing an example of a pass mask when recording is performed in two divisions [Figure 12] Flow chart for improving ejection stability in the second embodiment [Figure 13] Schematic diagram when the recording head 303 is observed from the nozzle formation surface [Figure 14] Figure showing an example of a recording operation of multi-pass scanning [Figure 15] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ (Inkjet recording device) Figure 1 is a diagram illustrating the recording device of this embodiment. The recording device of this embodiment is a so-called serial recording inkjet printer, and performs multi-pass recording, which completes the recording of an image for a unit area by multiple relative scans of the recording head 303 with respect to the recording medium P.

[0012] The recording medium P, fed to the recording unit, is transported in the direction of arrow Y (sub-scanning direction) in the figure as the transport roller 101 rotates, by the nip section between the transport roller 101 and the pinch roller 102 that follows it, which are positioned on the transport path. The platen 103 is positioned opposite the ejection port surface where the ejection port (nozzle) of the inkjet recording head 303 is formed. By supporting the back surface of the recording medium P from below, it maintains a constant distance between the surface of the recording medium P and the ejection surface of the recording head 303. The recording medium P on which the image has been recorded is nipped by the ejection roller 105 and the spur 106 that follows it, and is transported in the Y direction as the ejection roller 105 rotates, and ejected into the output tray 107.

[0013] The recording head 303 is mounted on the carriage 108 in a position with its ejection port facing the platen 103 or the recording medium P, and is detachably mounted on the carriage 108. The carriage 108 moves back and forth in the X direction along two guide rails 109 and 110 by the driving force of the carriage motor. During this movement, the recording head 303 performs an ejection operation in response to a recording signal, ejecting ink droplets from its ejection port and applying ink to the recording medium.

[0014] Figure 2 is a schematic diagram of the recording head 303 as viewed from the ejection port side. In this embodiment, the cyan nozzle row 21, magenta nozzle row 22, yellow nozzle row 23, and black nozzle row 24 are arranged in parallel in the X direction as shown in the figure. Each nozzle row has ejection ports (nozzles) for ejecting ink, arranged at equal intervals in the Y direction.

[0015] Furthermore, a recording element is provided inside each nozzle (not shown), and thermal energy is generated when the recording element is driven by electrical energy. This thermal energy causes the ink to foam, and as a result, the ink is ejected as droplets from the nozzle. For simplicity, in the following explanation, a row of multiple nozzles that eject the same color and amount of ink will be referred to as a nozzle row.

[0016] The X-direction in which the carriage 108 moves intersects with the Y-direction in which the recording medium is transported, and is called the main scanning direction. On the other hand, the Y-direction in which the recording medium is transported is called the sub-scanning direction. Multi-path recording is performed by alternately repeating the movement of the carriage 108 and recording head 303, which is the main scan and involves recording, and the transport of the recording medium (sub-scan), thereby gradually forming an image on the recording medium P.

[0017] Figure 14 illustrates the relationship between the recording medium P and the nozzles (discharge ports) used for image recording during multipath recording. While the black nozzle row 24 is used as an example, the same principles apply to other nozzle rows.

[0018] First, in the first scan, the recording head 303 is moved in the +X direction (forward direction) together with the carriage 108, and an image is recorded in area A1 using all nozzles, performing forward recording. After the first scan, the recording medium P is transported in the +Y direction. The amount transported at this time is the length corresponding to all nozzles. Then, after the recording head 303 is returned to the -X direction together with the carriage 108, forward recording is performed by the second scan. In the second scan, the recording head 303 is again moved in the +X direction together with the carriage 108, and an image is recorded in area A2 using all nozzles. After the second scan, the recording medium P is transported in the +Y direction. The amount transported at this time is also the length corresponding to all nozzles. After that, the recording medium P is ejected in the +Y direction, and the recording operation ends.

[0019] Thus, the recording method in this embodiment is a one-pass unidirectional recording method in which an image of a predetermined area (A1, A2) on the recording medium is completed by a single scan in one direction by the recording head 303.

[0020] In the example described above, after the first scan in the +X direction, the recording head 303 was returned by a scan in the -X direction without recording, and then a second scan in the +X direction was performed. However, the scan in the -X direction may also be a second scan with recording. That is, after the first scan, the carriage 108 and the recording head 303 are not returned in the -X direction, and the recording medium P is transported in the +Y direction for the entire length of the nozzles. Then, in the second scan in the -X direction, an image may be recorded in region A2 using all the nozzles.

[0021] Figure 3 is a block diagram illustrating the control configuration of the inkjet recording system of this embodiment. The main control unit 301 of the recording device controls the entire recording device and is composed of a CPU, ROM, RAM, etc. The recording buffer 302 stores image data as raster data before it is transferred to the recording head 303. The recording head 303 is an inkjet recording head having multiple nozzles capable of ejecting ink droplets, and ejects ink from each nozzle according to the image data stored in the recording buffer 302. The paper feeding and ejection motor control unit 304 controls the transport of the recording medium and the feeding and ejection of paper. The interface (I / F) 305 is connected to the image processing device by an I / F signal line 313 and exchanges data signals. The data buffer 306 temporarily stores image data received from the image processing device. The system bus 307 is a bus that connects the various functions of the recording device.

[0022] The main control unit 308 of the image processing device is primarily responsible for image creation and image data control in the image processing device, and is composed of a CPU, ROM, RAM, etc. The interface (I / F) 309 exchanges data signals with the recording device. The display unit 310 displays various information to the user, and can be an LCD, for example. The operation unit 311 is an operation unit that receives operations and instructions from the user, and can be a keyboard or mouse, for example. The system bus 312 is a bus that connects the main control unit 308 of the image processing device to each function.

[0023] (Overview of the recording system) Figure 4 is a block diagram illustrating the overview of the recording system of this embodiment. The recording system shown in this figure comprises a host PC 401 and a recording device (printer) 407 that records images based on recording data transmitted from the PC 401. The PC 401 consists of an application 402, an OS 403, a printer driver 404, and a recording data transmission unit 406. In this embodiment, recording data including a barcode image will be used as an example to explain the recording data sent to the printer 407. Although a barcode image will be used as an example to explain the recording target, the present invention is not limited to recording data including a barcode image. The recording target may include objects such as characters, lines, or photographs.

[0024] Application 402 is an application that can insert barcode data into an image. Based on instructions from the printer driver 404, the image processing functions provided by OS 403 and the data obtained from application 402 are combined and converted into recording data.

[0025] The printer driver 404 rasterizes (bitmaps) the received recording data in the rasterization unit 405 to an image with a resolution matching the recording head, converting it into recording data that the printer can receive. The converted recording data is sent to the recording data transmission unit 406 and then transmitted to the printer 407.

[0026] Next, the process by which a default string is sent to a printer as barcode data in the recording system of this embodiment will be described. Barcode data is image data that includes a so-called barcode, which is composed of a combination of bars and spaces. The barcode image is generated by converting the default string into a format consisting of bars and spaces using a barcode font.

[0027] When a string is entered into application 402, the printer driver 404 is called via OS 403. The printer driver 404 then requests barcode font information stored in it, and the user sets the specified barcode font.

[0028] The barcode font information includes the barcode font name selected from several pre-registered barcode types, as well as information such as the height and width of the barcode font. Examples include JAN code, CODE39, and CODE128. Then, the application 402 sends these settings and image data together to the printer driver 404 via the OS 403.

[0029] Subsequently, the rasterization unit 405 rasterizes the data using a specified barcode font to create barcode data consisting of one-dimensional combinations of bars and spaces. The rasterized data is converted into record data in a format that the printer 407 can receive and is transmitted to the printer 407 via the record data transmission unit 406.

[0030] In this embodiment, a configuration in which the application calls the printer driver's barcode font via the OS has been described, but the invention is not limited to this configuration.

[0031] (Overall Flow Overview) Figure 5 is a flowchart illustrating the image data processing performed by the image processing apparatus of this embodiment. The processing shown in this figure may be performed on the host PC 401, on the printer 407, or in a configuration where the processing is partially divided and executed by different systems.

[0032] In step S501, image data is input. The input image data may be vector data or bitmap data.

[0033] In step S502, the input image data is rendered, and the vector data is rasterized. At this stage, mapping and imposition may also be performed to match the size of the recording medium on which the image is stored.

[0034] Furthermore, pixel data corresponding to one column of pixels arranged in a predetermined direction on a matrix is ​​called raster data. Multiple such columns arranged in a row are called band data. When performing these image processing operations in printer 407, processing may be performed with limited ROM or RAM capacity, but it is common to use a configuration that processes band data sequentially.

[0035] In step S503, the barcode detection unit detects the barcode area. Here, the position of the detected barcode is obtained. The barcode data may be formed by rasterizing a barcode font, or it may be formed from the beginning as bitmap data or vector data. Therefore, the barcode information may be obtained during rendering in step S502, or it may be detected from edge information after it has been converted to a bitmap. In addition, the user may specify it on the panel or on the host side, and this embodiment is not limited to this method.

[0036] In step S504, the edge detection unit detects edge information of the bars contained in the barcode. Here, the edge information detected includes information on pixels corresponding to the edge region of the bar and pixels corresponding to the non-edge region, which is the internal region of the edge. Then, using the barcode position information acquired in step S503 and the detected edge information, control over the barcode edge region, as described later, is performed. The edge detection process can be carried out using known methods such as Sobel filters and Laplacian filters.

[0037] Figure 15 is a diagram illustrating the edge detection process and shows the state detected by the edge detection unit. This figure is an example of an image containing three recording targets, and from left to right, it contains a line with a width of 1 pixel, a line with a width of 5 pixels, and a line with a width of 2 pixels. In this embodiment, 1531 is set as an independent edge region, 1532 and 1534 are edge regions, and 1533 is set as a non-edge region. A non-edge region is a region contained within an edge region. Here, among the regions detected by the edge detection process, a region with a short side of 1 pixel, i.e., a region with a width of 1 pixel, is called an independent edge region. As will be described in detail later, in this embodiment different ejection control is performed for edge regions and non-edge regions, and the ejection control for independent edge regions is the same as that for non-edge regions.

[0038] Figure 16 illustrates the process of detecting edge regions using filtering. Figure 16(a) is the input image data, which is an image of vertical lines with a width of 1 pixel horizontally. Figure 16(b) is the edge detection filter, and Figure 16(c) is the calculation result using the edge detection filter. Figure 16(d) plots the filter calculation result against a vertical axis of 1600. Here, the calculation results using the filter in Figure 16(b) are shown for vertical lines with a width of 1 pixel (1601), 2 pixels (1602), 3 pixels (1603), 4 pixels (1604), and 5 pixels (1605). The filter calculation result differs depending on the width of the lines; for example, the calculation result for a 1-pixel wide line is 5100.

[0039] As will be explained in detail later, in this embodiment, different ejection control is performed for edge regions and non-edge regions. A 1-pixel wide grid line is normally detected as an edge region, but in this embodiment, it is necessary to perform the same ejection control as for non-edge regions. Therefore, the result of a filter calculation is used as a method to distinguish and detect a 1-pixel wide grid line from other edge regions.

[0040] As shown in Figure 16(d), the filter calculation result is a value corresponding to the line width. By setting thresholds 1632 and 1633 and detecting pixels within this range as edge regions, it is possible to prevent pixels with a line width of 1 pixel from being detected as edge regions. Black circles 1641 indicate pixels determined to be edge regions, and white circles 1642 indicate pixels determined to be non-edge regions.

[0041] The edge detection process described above may be performed on the entire input image data or only on the detected barcode area. While the following explanation assumes processing of edge areas included in a barcode, this is merely one example of implementation, and the present invention can achieve similar effects not only on barcode images but also on the edge areas of lines and characters.

[0042] Figure 18 is a flowchart showing the edge detection process in step S504. This process is repeated for all pixels rendered in step S502, but here it shows the process for one pixel. First, image data is input in step S1801, and a filter operation is performed in step S1802 to calculate the calculated value X. The filter operation in step S1802 consists of the following three steps: (1) As shown in Figure 16(a), pixel values ​​of 5x5 pixels are obtained centered on the pixel to be processed. (2) Each corresponding pixel is multiplied by the 5x5 filter coefficients shown in Figure 16(b). (3) All the pixel values ​​in Figure 16(c), which are the results of the 5x5 multiplications, are added together to calculate the calculated value X.

[0043] In step S1803, it is determined whether the calculated value X exceeds threshold A. This threshold A corresponds to the value of threshold 1632 in Figure 16(d) above. If the result of the determination is Yes, the process proceeds to step S1804; if the result of the determination is No, the process proceeds to step S1805. In step S1804, it is determined that the pixel to be processed is included in the non-edge region. In step S1805, it is determined whether the calculated value X exceeds threshold B. This threshold B corresponds to the value of threshold 1633 in Figure 16(d) above. If the result of the determination is Yes, the process proceeds to step S1806; if the result of the determination is No, the process proceeds to step S1804. In step S1806, it is determined that the pixel to be processed is included in the edge region, and the process proceeds to step S1807. In step S1807, it is determined whether the filter calculation process in step S1802 and the determination processes in S1803 and S1805 have been completed for all pixels of the input image data. If the processes have not been completed for all pixels, the process returns to step S1802. If the processes have been completed for all pixels, the process returns to Figure 5 and proceeds to step S505.

[0044] In step S505, image processing is performed to convert the image data into a format that the printer 407 can record. Here, the image data generated in S504 is converted into image data that corresponds to the color reproduction gamut of the printer 407.

[0045] In this embodiment, the input image data is data representing color coordinates (R, G, B) in a color space such as sRGB, which is the color representation of the monitor. Then, the input image data for each of the 8 bits of R, G, and B is converted into image data (R', G', B') corresponding to the printer's color reproduction range using known methods such as matrix arithmetic processing or processing using a three-dimensional LUT.

[0046] Next, the 8-bit image data for R', G', and B' is converted into image data consisting of color signal data corresponding to the ink colors used by the printer 407. The printer 407 in this embodiment records images using black (K), cyan (C), magenta (M), and yellow (Y) inks. Therefore, the RGB signal image data is converted into image data consisting of 8-bit color signals for K, C, M, and Y. This color conversion is also performed using a three-dimensional lookup table and interpolation. As an alternative conversion method, methods such as matrix arithmetic processing may be used, as described above. Furthermore, the number of ink colors is not limited to the four colors K, C, M, and Y, but may also include other types of inks such as light cyan (Lc), light magenta (Lm), gray (Gy) inks, transparent ink, and spot color inks.

[0047] Next, a process is performed to adjust the number of dots recorded on the recording medium by correcting each 8-bit image data. This adjustment is necessary because the relationship between the number of dots assigned to the recording medium and the optical density reproduced on the recording medium by that number of dots is not linear. In this adjustment process, a one-dimensional lookup table (LUT) can be used as a method to convert the input data into output data.

[0048] Next, quantization is performed on the ink color image data, which consists of 256 8-bit values. The quantization process generates 1-bit binary data for each pixel, representing either a recorded "1" or an unrecorded "0". The output of the quantization process may also be the number of ink droplets per unit area, and is not limited to 1-bit binary data consisting of recorded "1" or unrecorded "0". It may also be quantized into multi-level data of 2 bits or more. Furthermore, while error diffusion and dithering are known methods for quantization, any method may be used.

[0049] Then, an image is recorded on the recording medium by applying ink based on the image data generated in step S505.

[0050] Next, the ejection stability of the recording head will be explained using Figure 6. This figure is a schematic cross-sectional view of the ink flow path in the recording head 303, showing the flow of ink as a liquid. Ink is supplied from an ink tank (not shown) to the common liquid chamber 62 via the ink supply port 61. The ink supplied to the common liquid chamber 62 is filled into the nozzle 64a via the flow path. Then, when a voltage is applied to the heater 63, which is a recording element located above the nozzle 64a, foaming occurs and ink droplets are ejected from the nozzle 64a.

[0051] Much of the energy generated by foaming is converted into ink droplet ejection, but some of the energy propagates from nozzle 64a to the common liquid chamber 62. This propagated energy vibrates the ink in the common liquid chamber 62, affecting the meniscus vibration of the ink filling nozzle 64b adjacent to nozzle 64a. Thus, in a head configuration where ink is supplied from the common liquid chamber 62 to nozzle 64a and nozzle 64b adjacent to nozzle 64a, the ink inside nozzle 64b vibrates due to the ink droplet ejection operation of nozzle 64a. As a result, the ink ejection operation from nozzle 64b becomes unstable. This ejection stability issue occurs when ejection is continuous, but does not occur during the initial ejection or when ejection occurs after a certain amount of time has elapsed since the previous ejection.

[0052] Figure 7 illustrates the case where the ink droplet's landing position on the recording medium is shifted due to this decrease in ejection stability. Figure 7(a) shows the case where the ink droplet lands in an ideal position, while Figure 7(b) shows the case where the ink droplet's landing position is shifted due to the influence of the ejection operation of an adjacent nozzle. In Figure 7(b), the width of the recorded area is wider than the width of the area in the image data due to the shift in landing position. In particular, when the space between areas is represented by blank areas where no ink is applied, such as in a barcode image, unlike the case where the ink lands ideally as in Figure 7(a), the space area is narrowed by the increased width of the area, as shown in Figure 7(b). Furthermore, if the aforementioned landing shift occurs in a recording object adjacent to a narrow space area, the space area becomes compressed. The characteristic configuration of this embodiment, which solves these problems, will be described below.

[0053] (Explanation of recording control) Figure 8(a) shows the number of ink droplets applied per unit area when a 1-bit binary data representing either "1" (record) or "0" (not recorded) is input. As shown in this figure, two patterns, A and B, are prepared. For the non-edge areas of the bars in the barcode image, both patterns A and B are defined to record 1 dot when the record is "1". On the other hand, for the edge areas of the barcode, when the record is "1", one dot is recorded in one pattern, and zero dots are recorded, i.e., not recorded, in the other pattern.

[0054] Figure 8(b) shows the pattern assigned to the input image data, and this pattern allows control over whether pattern A or B is assigned to the input value. In this embodiment, by synchronizing the pattern and the nozzle pitch, it is possible to control the ejection of ink from two adjacent nozzles to the target area so that ink is not ejected simultaneously. Here, even if the value of the binary data is "1" indicating a record, ink will not be ejected to the pixels of pattern B. In other words, for edge areas, ink is ejected only from odd-numbered nozzles, and not from even-numbered nozzles.

[0055] Figure 9 is a flowchart of the process by which the recording control unit records image data.

[0056] In step S901, image data in binary format and information indicating the edge region of the detected barcode are input.

[0057] In step S902, a determination is made for each pixel to determine whether it corresponds to the edge region of the detected barcode.

[0058] In steps S903 and S904, a recording pattern is assigned as shown in Figure 8, and the number of ink droplets to be applied per unit area is determined. As a result, one dot is applied to pixels that indicate a "1" in the non-edge areas of the barcode, but in the edge areas of the barcode, there are pixels that do not have a dot applied even if they indicate a "1" in the edge areas of the barcode.

[0059] Finally, in step S905, a record is made according to the number of ink droplets allocated, and ink is applied.

[0060] Figure 10 shows the dot arrangement of a barcode recorded on a recording medium. Ink is restricted so that it is not ejected simultaneously from two nozzles adjacent to each other in the vertical direction of the figure to the edge regions of bar area 1001 and bar area 1003.

[0061] As described above, in an inkjet recording device, if ink is ejected simultaneously from two adjacent nozzles, the ejection becomes unstable and the accuracy of the ink placement decreases. In contrast, by limiting simultaneous ejection from two adjacent nozzles, it is possible to stabilize the ejection and suppress the decrease in accuracy of the ink placement. In this way, by suppressing the misalignment of the ink placement relative to the edge of the recording area, it is possible to suppress the collapse of the space area 1002 located between the two recording areas and formed by the margin.

[0062] Figure 17 illustrates the effect of recording area width and simultaneous ejection limiting processing on image density. It shows the image density when a uniform 50% ejection limit is applied to edge regions, regardless of the line width of the recording area. The wider the area, the smaller the change in density of the recording area due to edge thinning. On the other hand, when ejection limiting processing is applied to a 1-pixel wide area, 50% of the pixels are thinned out, resulting in a significant decrease in density. Therefore, in this embodiment, for a recording area with a width of 1 pixel (independent edge region), simultaneous ejection limiting processing from two adjacent nozzles is not applied to the edge, treating it the same as a non-edge region. This makes it possible to maintain density without simultaneous ejection limiting for recording areas where the density decrease due to simultaneous ejection limiting is large, such as 1-pixel wide lines.

[0063] In this embodiment, the binary recording data indicating whether or not to apply ink was changed to restrict simultaneous ejection from two adjacent nozzles, but similar effects can be obtained by other methods. For example, in step S505, when the image processing unit adjusts the number of dots recorded on the recording medium using a one-dimensional lookup table (LUT), it may also be possible to switch to a LUT with a different adjusted value based on information that it is an edge region. Alternatively, when performing quantization processing, it may be possible to perform quantization processing such that pixels corresponding to one of the two adjacent nozzles become unrecorded "0" based on information that it is an edge region.

[0064] In this embodiment, edge regions and non-edge regions were detected as edge information of the barcode. However, it is preferable to perform the same processing on regions other than the barcode as on the edge region of the barcode. That is, simultaneous ejection from two adjacent nozzles is restricted for the edge region, while other regions do not need to be restricted.

[0065] Furthermore, in this embodiment, an edge detection filter or the like is used to extract the edge region of the barcode, and simultaneous ejection from two nozzles adjacent to the edge region is restricted. When the barcode is the object to be recorded, it is not necessary to restrict the entire edge region. The problem that the present invention addresses is ink bleeding in the edge region extending in the Y direction, which is the direction in which the multiple nozzles are arranged, when the barcode is the object to be recorded. Therefore, it is also possible to detect only the edge region of the barcode consisting of bars and spaces whose length in the Y direction is longer than the length in the X direction, i.e., bars and spaces. Also, since there are no reading problems caused by bleeding in the X direction edges, it is also possible to detect only the Y-direction extending side of each bar (up and down direction in Figure 7) as the edge region.

[0066] In the example shown in Figure 8, ink is dispensed from odd-numbered nozzles assigned to pattern A, and not from even-numbered nozzles assigned to pattern B. Therefore, of the ink dispensed simultaneously, 100% is dispensed from odd-numbered nozzles and 0% is dispensed from even-numbered nozzles. As mentioned above, if the effects of simultaneous dispensing can be suppressed, it is not necessary to set one of the odd-numbered or even-numbered nozzles to 0%. Ink may be dispensed from even-numbered nozzles. In this embodiment, for non-edge regions, 100% of the ink is dispensed from odd-numbered nozzles, and 100% is dispensed from even-numbered nozzles, with a difference of 0%. On the other hand, for edge regions, 100% of the ink is dispensed from odd-numbered nozzles, and 0% is dispensed from even-numbered nozzles, with a difference of 100%. It is preferable that the difference in the percentage of ink dispensed from two adjacent nozzles to an edge region is greater than the difference in the percentage of ink dispensed from two adjacent nozzles to a non-edge region. Furthermore, the relationship between odd-numbered nozzles and even-numbered nozzles may be reversed, and a configuration in which more ink is ejected from even-numbered nozzles relative to the edge region is also possible.

[0067] Furthermore, in this embodiment, lines with a width of 1 pixel in the scanning direction of the recording head were detected by comparing a filtered value with a threshold, but the detection method is not limited to the above method. For example, an edge detection method using attribute values ​​associated with objects in image data may also be used. The line width detection method is also not limited to the above method, and the threshold for whether to restrict simultaneous ejection from two nozzles adjacent in the nozzle array direction is not limited to 1 pixel, but may be a form that determines whether it is greater than a predetermined number of pixels. This can be appropriately determined depending on the degree of influence of the ejection instability mentioned above.

[0068] (Second embodiment) In the above-described embodiment, simultaneous ejection was defined as ejecting ink to pixels in the same row (same column) aligned in the nozzle arrangement direction (Y direction in the figure) on the recording medium, and simultaneous ejection from two adjacent nozzles was restricted. The degree of influence of ink vibration from adjacent nozzles varies depending on the driving frequency of the recording head and the composition of the ink. Therefore, restricting ejection from adjacent nozzles for recording one pixel in the X direction may not solve the problem. In contrast, this embodiment describes an example of restricting simultaneous ejection for nozzles in a pixel range that affects the ejection operation.

[0069] This section describes an example where the effects of ejection instability due to ink vibration via the common liquid chamber can affect a location on the recording medium that is two pixels away. Specifically, the edge detection process in step S504 in Figure 5 is different, while the processes from steps S501 to S503 are the same as in the first embodiment, so the explanation of the similar parts will be omitted.

[0070] Figure 19 shows the independent edge region 1931, edge regions 1932 and 1934, and non-edge region 1933 detected by the edge detection unit in this embodiment. The independent edge region 1931 is an area whose short side is 1 pixel. Similar to the previously described embodiment, the independent edge region is treated the same as the non-edge region and is not subject to simultaneous ejection restrictions.

[0071] Figure 20 illustrates the process of detecting edge regions using filtering. Similar to Figure 16, Figure 20(a) is the input image data, which is an image of vertical lines with a width of 1 pixel horizontally. Figure 20(b) shows the edge detection filter, and Figure 20(c) shows the calculation results using the edge detection filter. Figure 20(d) plots the filter calculation results against a vertical axis of 2000. Here, the calculation results using the filter in Figure 20(b) are shown for vertical lines 2001 (1 pixel width), 2002 (2 pixel width), 2003 (3 pixel width), 2004 (4 pixel width), and 2005 (5 pixel width).

[0072] In this embodiment, as shown in Figure 20, the edge region is defined as two pixels from the edge of the recording area. Thresholds 2032 and 2033 are set, and pixels within this range are detected as edge regions. Black circles 2041 indicate pixels determined to be edge regions, and white circles 2042 indicate pixels determined to be non-edge regions.

[0073] Figure 21 is a flowchart showing the edge detection process in this embodiment. This process is repeated for all pixels rendered in step S502, but here we show the process for one pixel. First, image data is input in step 2101, and a filter operation is performed in step 2102 to calculate the calculated value X. The filter operation process in step S2102 consists of the following three steps: (1) As shown in Figure 20(a), pixel values ​​of 5 × 5 pixels are obtained centered on the pixel to be processed. (2) Each corresponding pixel is multiplied by the 5 × 5 filter coefficients shown in Figure 20(b). (3) All the values ​​of each pixel, which are the results of the 5 × 5 multiplications shown in Figure 20(c), are added together to calculate the calculated value X.

[0074] In step S2103, it is determined whether the calculated value X exceeds the threshold A'. This threshold A' corresponds to the value of threshold 2032 in Figure 20. If the result of the determination is Yes, the process proceeds to step S2104; if the result of the determination is No, the process proceeds to step S2105. In step S2104, it is determined that the pixel to be processed is included in the non-edge region. In step S2105, it is determined whether the calculated value X exceeds the threshold B'. This threshold B' corresponds to the value of threshold 2033 in Figure 20. If the result of the determination is Yes, the process proceeds to step S2106; if the result of the determination is No, the process proceeds to step S2104. In step S2106, it is determined that the pixel to be processed is included in the edge region, and the process proceeds to step S2107.

[0075] In step S2107, it is determined whether the filter calculation process in step S2103 and the determination processes in S2104 and S2106 have been completed for all pixels of the input image data. If the process has not been completed for all pixels, the process returns to step S2102. If the process has been completed for all pixels, the process returns to Figure 5 and proceeds to step S505. The process in step S505 is the same as in the first embodiment, so the explanation is omitted.

[0076] In this embodiment, simultaneous ejection is restricted for nozzles in a pixel range affected by ejection instability due to ink vibration via a common liquid chamber, allowing for the recording of data such that the width of the recording area is the width desired by the user. Although an example has been described in which the effect of ejection instability extends to a position two pixels apart on the recording medium surface, the present invention is not limited to two pixels.

[0077] It is preferable to appropriately set this range of pixel counts depending on the degree of impact. By defining lines with a width of less than or equal to a predetermined number of pixels as independent edge regions and treating them the same as non-edge regions where ejection restriction is not applied, ejection restriction can be appropriately applied only to pixels where it is necessary.

[0078] (Third embodiment) In the first and second embodiments, independent edge regions having a width less than or equal to a predetermined pixel width were treated the same as non-edge regions and subjected to the same processing. However, independent edge regions have the problem of not only a decrease in density but also a change in shape. In this embodiment, an example that considers both the decrease in density and the change in shape of independent edge regions will be described.

[0079] In this embodiment, the independent edge region 1531 in Figure 15 is treated as a separate region from the non-edge region 1533. The processing from steps S501 to S503 will be omitted from the explanation, and the edge detection process in step S504 will be described.

[0080] Figure 22 is a flowchart showing the edge detection process in this embodiment. This process is repeated for all pixels rendered in step S502, but here we show the process for one pixel. First, image data is input in step 2201, and a filter operation is performed in step 2201 to calculate the calculated value X. The three steps of the filter operation process in step S2202 are the same as in the embodiment described above.

[0081] In step S2203, it is determined whether the calculated value X exceeds the threshold A''. If the result is Yes, the process proceeds to step S2204; if the result is No, the process proceeds to step S2205. In step S2204, it is determined that the pixel to be processed is included in an independent edge region, and the process proceeds to step S2208.

[0082] In step S2205, it is determined whether the calculated value X exceeds the threshold B'' (< threshold A''). If the result is Yes, the process proceeds to step S2206; if the result is No, the process proceeds to step S2207. In step S2206, it is determined whether the pixel to be processed is included in the edge region; in step S2207, it is determined whether the pixel to be processed is included in the non-edge region.

[0083] In step S2208, if it is determined that the determination process has been completed for all pixels of the input image data, the process returns to Figure 5 and proceeds to step S505.

[0084] In step S505, the processing of edge regions and non-edge regions is the same as in the previously described embodiment, so the explanation is omitted. Here, we will describe pixels that have been determined to be independent edge regions. Here, we will describe a configuration that minimizes density reduction while keeping the effects of simultaneous ejection within an acceptable range, compared to the first embodiment.

[0085] In this embodiment, the proportion of ink ejected from odd-numbered nozzles to non-edge regions is 100%, the proportion of ink ejected from even-numbered nozzles is 100%, and the difference is 0%. On the other hand, the proportion of ink ejected from odd-numbered nozzles to edge regions is 100%, the proportion of ink ejected from even-numbered nozzles is 0%, and the difference is 100%. Preferably, the difference in the proportion of ink ejected from two adjacent nozzles to an independent edge region is greater than or equal to the difference in the proportion of ink ejected from two adjacent nozzles to a non-edge region, and less than or equal to the difference in the proportion of ink ejected from two adjacent nozzles to an edge region.

[0086] Furthermore, if the influence of simultaneous ejection on the control of the ejection nozzles for independent edge regions can be kept within an acceptable range, it is not necessary to set one of the odd-numbered nozzles and the even-numbered nozzles to 0%. In other words, if the difference in the percentage of ink ejected from two adjacent nozzles for an independent edge region approaches 0%, the density can be maintained better, and if the difference in percentage approaches 100% for an independent edge region, the shape can be maintained better. For example, if the difference in percentage approaches 50% for an independent edge region, a balance can be struck between suppressing density reduction and maintaining shape.

[0087] In this way, by performing different processing on independent edge regions and non-edge regions, it is possible to suppress both the reduction in density and the reduction in shape changes in independent edge regions.

[0088] (Fourth embodiment) In this embodiment, the configurations that differ from the first embodiment will be described. Components similar to those in the first embodiment are denoted by the same reference numerals, and their detailed descriptions are omitted; only the differing parts will be described in detail.

[0089] In the first embodiment, edge regions were detected, and ejection stability was enhanced by restricting the simultaneous ejection of ink from two adjacent nozzles in a single scan, thereby completing the recording of the target image in a single scan, known as one-pass recording. In this embodiment, a configuration is described in which the image data is divided into multiple scans, and the image is recorded in multiple scans, known as multi-pass recording, to complete the recording of the target image.

[0090] Figure 11 shows the path masks used to divide image data when recording in two separate scans. Figure 11(a) is the path mask used for non-edge regions, and Figure 11(b) is the path mask used for edge regions. Pixels indicated by diagonal lines are recording pixels where ink application is permitted during the scan, while white pixels are non-recording pixels where ink application is not permitted. The two masks are mutually exclusive, allowing recording to be performed on all pixels in two scans.

[0091] In Figure 11(a), during the first scan of the non-edge region of the barcode, recording is performed based on the recording data generated using mask 1101, and during the second scan, recording is performed based on the recording data generated using mask 1102. In Figure 11(b), during the first scan of the edge region, recording is performed based on the recording data generated using mask 1103, and during the second scan, recording is performed based on the recording data generated using mask 1104. In recording for each scan of this edge region, the recording pixels and non-recording pixels of each mask are arranged so that simultaneous ejection from two adjacent nozzles does not occur.

[0092] Figure 12 is a flowchart of the process for recording image data in this embodiment.

[0093] In step S1201, image data in binary format and information indicating the detected edge region are input.

[0094] In step S1202, the number of ink droplets to be applied per unit area is determined. In this embodiment, one dot is applied to each pixel that indicates a record, regardless of whether it is an edge region or a non-edge region.

[0095] In step S1203, a determination is made for each pixel to determine whether it corresponds to an edge region.

[0096] In steps S1204 and S1205, a path mask is assigned to the binary data. This process assigns a path mask to edge regions that prevents simultaneous ejection from two adjacent nozzles in the same scan.

[0097] Finally, in step S1206, an image is recorded based on the recorded data corresponding to each of the two scans.

[0098] In this embodiment, a path mask is used in which recording pixels and non-recording pixels are arranged in an edge region so that simultaneous ejection from two adjacent nozzles does not occur during a single scan. By restricting simultaneous ejection from two adjacent nozzles, the ink ejection operation from each nozzle is stabilized, and a decrease in targeting accuracy can be suppressed.

[0099] Furthermore, by dividing the image data into multiple scans and recording them, the total number of dots applied to the recording medium can be maintained even when limiting simultaneous ejection from two adjacent nozzles. Therefore, ejection can be stabilized without diluting the density desired by the user.

[0100] In this embodiment, a configuration in which image data is divided and an image including the target is recorded in two scans has been described. However, this can also be applied to configurations in which the image data is divided and recorded in three or more scans. That is, by controlling the simultaneous ejection from two adjacent nozzles in a single scan, it is possible to obtain high-quality images while achieving ink ejection stability.

[0101] (Other embodiments) In the embodiments described above, a method for maintaining ejection stability by restricting simultaneous ejection from two adjacent nozzles was explained. Depending on the nozzle spacing of the recording head and the flow path length to the liquid chamber, vibrations of ink through the common liquid chamber may affect the ejection operation of nozzles that are two or more distance apart. The present invention may also be configured to restrict simultaneous ejection for nozzles within a range that affects the ejection operation.

[0102] Furthermore, similar problems may arise in configurations where multiple nozzle rows are connected to a common liquid chamber. For example, as shown in Figure 13, the present invention is applicable to a recording head in which a nozzle row consisting of even-numbered nozzles and a nozzle row consisting of odd-numbered nozzles are connected to a common liquid chamber and are positioned offset in the X direction. In this case, it is thought that the simultaneous ejection of ink affects the ink ejection operation between two adjacent nozzles on the common liquid chamber. For example, if two rows of nozzles included in nozzle group 1321 are supplied with ink from a single common liquid chamber, it is thought that the ejection operation of nozzle 1321a will also affect the ejection operation of nozzle 1321b. In other words, for multiple rows of nozzles supplied with ink from the same common liquid chamber, it is necessary to restrict simultaneous ejection for two nozzles that are adjacent in the Y direction of the figure (in this figure, nozzles 1321a and 1321b).

[0103] In the above embodiment, a thermal recording head using an electrothermal conversion element as the recording element for ejecting ink was described. However, a piezo-type recording head that ejects ink by changing the volume by applying a voltage to a piezoelectric element may also be used.

[0104] Furthermore, the above-described embodiment described an inkjet recording device of the so-called serial recording type, in which an image is recorded by scanning a recording head with multiple nozzles arranged in a direction intersecting the nozzle arrangement direction. The present invention is applicable to forms in which an image is recorded by relative scanning between a recording medium and a recording head. For example, it may also be applied to a so-called full multi-type inkjet recording device in which the recording medium is transported in a direction intersecting the nozzle arrangement direction, and an image is recorded using a line head capable of recording an image over the entire width of the recording medium in a single scan. Even in the case of a full multi-type inkjet recording device, it is preferable to apply the above configuration to barcodes in which bars extend in the direction in which the nozzles are arranged.

[0105] Furthermore, although the above embodiment described the width of the edge region as 1 pixel, the number of pixels detected as an edge region may be 2 or more. In this case, it is preferable to restrict the simultaneous ejection of two adjacent nozzles for a region of 1 pixel aligned in the nozzle arrangement direction. That is, it is preferable that the difference in the proportion of ink ejected from two nozzles adjacent to an edge region is greater than the difference in the proportion of ink ejected from two nozzles adjacent to a non-edge region.

[0106] Furthermore, this can also be achieved by combining the configurations of the above embodiments and implementing control that divides the recording into multiple scans and then does not record on the recording medium. [Explanation of Symbols]

[0107] 101 Conveyor roller 108 Carriage 303 Recording head 401 PC 407 Printer

Claims

1. A recording head having multiple nozzles arranged in a first direction for ejecting ink supplied from a common liquid chamber, A scanning means that performs relative scanning with respect to the recording medium in a second direction intersecting the first direction, Control means for controlling the ink ejection operation from the recording head so that, for edge regions of a line drawing extending in the first direction and having a width in the second direction greater than a predetermined number of pixels, the use of one of the odd-numbered nozzles and even-numbered nozzles arranged in the first direction of the recording head is permitted in one relative scan, while the use of the other is not permitted; and for edge regions of a line drawing extending in the first direction and having a width in the second direction less than or equal to the predetermined number of pixels, the use of both the odd-numbered nozzles and even-numbered nozzles is permitted in one relative scan for recording. An inkjet recording device characterized by comprising the following features.

2. The inkjet recording apparatus according to claim 1, characterized in that the control means controls the ink ejection operation from the recording head so as to allow the use of both the odd-numbered nozzles and the even-numbered nozzles in a single relative scan for recording non-edge regions contained within the edge region of a line drawing extending in the first direction.

3. The inkjet recording apparatus according to claim 1 or 2, wherein the control means further comprises detection means for detecting an edge region of a line drawing that extends in the first direction and whose width in the second direction is greater than the predetermined number of pixels.

4. The inkjet recording apparatus according to claim 3, characterized in that the control means determines, by calculation using a filter, that it detects an edge region of a line drawing that extends in the first direction and whose width in the second direction is greater than the predetermined number of pixels.

5. The inkjet recording apparatus according to claim 4, characterized in that the control means detects pixels whose calculated value is greater than a first threshold and less than a second threshold as edge regions of a line drawing that extends in the first direction and whose width in the second direction is greater than the predetermined number of pixels.

6. The inkjet recording apparatus according to any one of claims 1 to 5, characterized in that the predetermined number of pixels is 1 pixel.

7. The control means is By dividing the image data using a pass mask that corresponds to multiple scans, recording data corresponding to each of the multiple scans is generated. The inkjet recording apparatus according to any one of claims 1 to 6, characterized in that it controls whether to allow the use of the odd-numbered nozzles and the even-numbered nozzles, respectively, based on the setting of whether to allow recording in the pass mask.

8. The inkjet recording apparatus according to any one of claims 1 to 7, characterized in that the scanning means moves the recording head in the second direction.

9. The inkjet recording apparatus according to any one of claims 1 to 8, characterized in that the odd-numbered nozzles and the even-numbered nozzles are offset from each other in the second direction.

10. The inkjet recording apparatus according to any one of claims 1 to 9, characterized in that the recording head ejects ink from a nozzle by foaming caused by applying voltage to a heater.

11. A recording head having multiple nozzles arranged in a first direction for ejecting ink supplied from a common liquid chamber, A scanning means that performs relative scanning with respect to the recording medium in a second direction intersecting the first direction, An inkjet recording method for recording an image using, An inkjet recording method characterized in that, for edge regions of a line drawing extending in the first direction and having a width in the second direction greater than a predetermined number of pixels, the ink ejection operation from the recording head is controlled to allow the use of one of the odd-numbered nozzles and even-numbered nozzles arranged in the first direction of the recording head during a single relative scan, while not allowing the use of the other; and for edge regions of a line drawing extending in the first direction and having a width in the second direction less than or equal to the predetermined number of pixels, the ink ejection operation from the recording head is controlled to allow the use of both the odd-numbered nozzles and even-numbered nozzles during a single relative scan.

Images