Image forming apparatus

Abstract

The present invention provides an image forming apparatus that can reduce liquid consumption in borderless image forming processing. [Solution] An image for borderless printing is generated by adding additional images A1 to A5 to the outside of the original image. The additional images A1 to A5 are adjusted so that the total amount of ink used for additional images A1 to A5 is less than the total amount of ink used for the additional images A1 to A5 and the corresponding block regions a1 to a5 of the original image.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] Conventionally, there is an image forming apparatus that forms an image by attaching a liquid to a medium. In such an image forming apparatus, a borderless image forming process may be performed so that no blank space occurs at the edge of the medium. The borderless image forming process is performed, for example, by adjusting the image to a size larger than the medium (printing paper) and then forming the image on the medium. Such borderless image forming process (borderless full-surface printing) is described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the borderless image forming process as described above, for example, when performing borderless printing by enlarging the original image to a size larger than the medium, or when performing borderless printing by adding an image identical to the edge region of the original image outside the original image, the amount of liquid used for the portion protruding from the medium becomes the size corresponding to a part of the original image area, and there is a risk that it may not meet the requirement of reducing liquid consumption.

[0005] An object of the present invention is to provide an image forming apparatus capable of reducing liquid consumption in borderless image forming processing.

Means for Solving the Problems

[0006] The image forming apparatus of the present invention comprises an image forming unit that performs an image forming operation to form an image by depositing a liquid onto a medium, and a control unit, wherein the control unit performs an addition process to generate an image by adding an additional image to the outside of an original image, and a borderless image forming process that causes the image forming unit to perform the image forming operation such that at least a part of the formation area of ​​the additional image is located outside the medium and the original image is formed on the medium, and the total amount of liquid used in the image forming operation for the additional image is smaller than the total amount of liquid used in the image forming operation for a reference area which is a part of the original image and is adjacent to the additional image in the image and has the same area as the additional image. [Effects of the Invention]

[0007] The total amount of liquid used in the image formation operation for the added image is less than the total amount of liquid used in the image formation operation for the reference area. For example, when performing borderless printing by enlarging the original image to a size larger than the medium, or by adding an image identical to the edge region of the original image outside the original image, the amount of liquid used for the portion extending beyond the medium will be proportional to a portion of the original image, which may not meet the requirement to reduce liquid consumption. In contrast, in the present invention, the total amount of liquid used in the image formation operation for the added image corresponding to the portion extending beyond the medium is less than the amount of liquid used in the image formation operation for the reference area (a portion of the original image). Therefore, liquid consumption can be reduced. As a result, an apparatus capable of reducing liquid consumption in borderless image formation processing is realized. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overview diagram of a printer according to one embodiment of the present invention. [Figure 2] Figure 1 is a block diagram showing the configuration of the printer's control system. [Figure 3] Figure 1 shows the band data generated by the printer and the corresponding bands in the original image. [Figure 4] This figure shows the ink ejection range during borderless and bordered printing processes performed by the printer shown in Figure 1. [Figure 5] This figure shows the additional image that is added to the original image during the borderless processing shown in Figure 4. [Figure 6] This figure shows the state where an additional image has been added to the band at the front end of the original image shown in Figure 3. [Figure 7] This figure shows the state where an additional image has been added to the middle band of the original image shown in Figure 3. [Figure 8] This figure shows the state where an additional image has been added to the trailing band of the original image shown in Figure 3. [Figure 9] Figures 6 to 8 show the additional images and magnified sections of the block regions. [Figure 10] Figure 1 is a flowchart showing the flow of additional processing performed by the control unit. [Figure 11] Figure 10 is a flowchart detailing the Bf process. [Figure 12] Figure 10 is a flowchart detailing the Bm process. [Figure 13] Figure 10 is a flowchart detailing the Br process. [Modes for carrying out the invention]

[0009] Hereinafter, a printer 100 according to a preferred embodiment of the present invention will be described with reference to the drawings. In the following description, the vertical direction is defined based on the state in which the printer 100 is installed for use (the state in Figure 1), the long direction of the housing 100a is defined as the left-right direction in a plan view, and the short direction of the housing 100a is defined as the front-back direction.

[0010] The printer 100 (corresponding to the "image forming apparatus" of the present invention) is a device that forms an image on a sheet of paper S. As shown in Figure 1, the printer 100 mainly comprises a housing 100a, a transport mechanism 2, a carriage 4, a head 5, a moving mechanism 6, a paper output tray 7, a cartridge mounting section 8, and a control unit 9.

[0011] The transport mechanism 2 supplies the paper S, which is housed in the lower part of the housing 100a, to the head 5 above it. The transport mechanism 2 has transport roller pairs 23 and 24 and a guide section 25. The guide section 25 guides the paper S, which is being transported upward by the rollers located in the lower part of the housing 100a, toward the front.

[0012] The transport roller pairs 23 and 24 are arranged spaced apart from each other in the front-rear direction. Transport roller pair 23 consists of a drive roller that rotates by the drive of transport motor 23a (see Figure 2) and a driven roller that moves along with the drive roller. Transport roller pair 24 consists of a drive roller that rotates by the drive of transport motor 24a (see Figure 2) and a driven roller that moves along with the drive roller. The paper S, guided forward by the guide unit 25, is transported further forward by the transport roller pairs 23 and 24.

[0013] The head 5 (corresponding to the "image forming unit" of the present invention) includes a plurality of nozzles 51 formed on its lower surface and a driver IC 52 (see Figure 2). When the driver IC 52 is driven by the control unit 9, an image forming operation is performed in which ink is ejected from the nozzles 51. The ink ejected from the head 5 by the image forming operation reaches the image forming surface of the paper S, which is located at the image recording position opposite the lower surface of the head 5. As the paper S is transported by the transport mechanism 2, the ink from the head 5 adheres to the paper S, thereby forming an image on the image forming surface of the paper S.

[0014] The head 5 is mounted on the carriage 4. The carriage 4 is movable by a moving mechanism 6. The moving mechanism 6 has two guide rails 61, 62 and a carriage motor 63 (see FIG. 2). The two guide rails 61, 62 are arranged at intervals in the front-rear direction and each extends in the left-right direction. The carriage 4 is arranged so as to straddle the two guide rails 61, 62. The carriage 4 is connected to the carriage motor 63 via a belt or the like. When the carriage motor 63 is driven under the control of the control unit 9, the carriage 4 moves in the left-right direction along the guide rails 61, 62. Hereinafter, the left-right direction in which the carriage 4 moves may be referred to as the main scanning direction, and the front-rear direction in which the paper S is conveyed may be referred to as the sub-scanning direction, respectively.

[0015] The paper S on which an image is formed by the head 5 is discharged to the paper discharge tray 7 by the conveyance mechanism 2. The paper discharge tray 7 is disposed in front of the head 5 within the housing 100a and at the upper part of the housing 100a.

[0016] The cartridge mounting portion 8 is installed at the right end and the front portion of the housing 100a. The cartridge mounting portion 8 can detachably mount four ink cartridges 8a that store black, yellow, cyan, and magenta inks respectively. Ink is supplied from the ink cartridges 8a mounted on the cartridge mounting portion 8 to the head 5 via a tube (not shown) or the like.

[0017] The control unit 9 controls the entire printer 100. As shown in FIG. 2, a conveyance motor 23a, 24a, a driver IC 52, a carriage motor 63, etc. are electrically connected to the control unit 9.

[0018] As shown in Figure 2, the control unit 9 includes a CPU (Central Processing Unit) 91, ROM (Read Only Memory) 92, RAM (Random Access Memory) 93, and ASIC (Application Specific Integrated Circuit) 94. ROM 92 stores programs executed by the CPU 91 and ASIC 94, as well as various fixed data. ROM 92 also includes a writable area consisting of EEPROM (Electrically Erasable Programmable Read-Only Memory), etc. Various settings are written to this area. These settings include information such as a table of halftone coefficients (see Table 1 below). RAM 93 temporarily stores image data representing the image to be formed on the paper S, and data necessary during program execution. Image data is acquired from external devices such as a PC or USB (Universal Serial Bus) memory (corresponding to the "image data acquisition process" of the present invention). ASIC 94 performs operations such as rewriting the data in RAM 93.

[0019] Furthermore, the control unit 9 may perform various processes solely with the CPU 91, solely with the ASIC 94, or collaboratively with the CPU 91 and ASIC 94. Also, the control unit 9 may be performed by a single CPU 91, or by multiple CPUs 91 sharing the processing. Similarly, the control unit 9 may be performed by a single ASIC 94, or by multiple ASICs 94 sharing the processing. The various processes performed by the control unit 9 will now be described.

[0020] The control unit 9 performs image formation processing. Image formation processing is performed based on image data acquired from an external device such as a PC. The initial image data acquired from the external device is, for example, vector data in which the content of the image to be formed (hereinafter referred to as the "original image") is described in a page description language. The control unit 9 converts this vector data into raster data consisting of data indicating the pixel value of each pixel that makes up the original image. The raster data consists of data relating to multiple planes corresponding to multiple colors, for example, four planes: C (cyan), M (magenta), Y (yellow), and K (black). In this embodiment, a large (small) pixel value corresponds to a large (small) amount of ink used for that pixel.

[0021] In the above conversion process from vector data to raster data, band data, which is a set of raster data, is generated for each of the bands Bf, Bm, and Br of the original image I shown in Figure 3 (corresponding to the "band processing" of the present invention). Each band corresponds to a rectangular region that constitutes a part of the original image I, extending from one end to the other in the width direction. Band Bf is the band corresponding to the front end of the original image I. Band Br is the band corresponding to the rear end of the original image I. Band Bm is the band corresponding to the intermediate part sandwiched between band Bf and band Br.

[0022] The control unit 9 controls the drive of the transport motors 23a and 24a and the carriage motor 63 based on the respective band data representing bands Bf, Bm, and Br. Through this control, the paper S is fed to the head 5, and ink is ejected from the head 5 at appropriate positions and timings.

[0023] The image forming process according to this embodiment includes bordered processing and borderless processing (corresponding to the "borderless image forming process" of the present invention). As shown in Figure 4, in bordered processing, ink from the head 5 is ejected toward the ink ejection range A set within the paper S. The ink ejection range A matches the size of the original image. In contrast, in borderless processing, ink is ejected toward the ink ejection range B, which is larger than the size of the original image relative to the ink ejection range A. The ink ejection range B is set to span the paper S in both the main scanning direction corresponding to the front-to-back direction of the original image I and the sub-scanning direction corresponding to the width direction of the original image I. In this way, by ejecting ink over an area larger than the paper S, borderless printing is possible, in which an image can be formed without gaps across the entire image forming surface of the paper S.

[0024] Incidentally, as specific methods for performing borderless printing, for example, one could enlarge the original image to a size larger than the paper size S to perform borderless printing, or add an image identical to the border area of ​​the original image to the outside of the original image to perform borderless printing. However, with these methods, the amount of ink used for the portion that extends beyond the paper size S will be proportional to a portion of the original image. Therefore, these methods may not be suitable for the requirement to reduce ink consumption. Accordingly, in this embodiment, the following configuration is adopted to reduce ink consumption during borderless printing.

[0025] As shown in Figure 5, the control unit 9 performs an additional processing to generate a borderless image I', which is the target of borderless image formation, by adding an additional image A to the outside of the original image I. Then, the control unit 9 performs borderless processing so that the original image I is formed exactly across the entire sheet of paper S. In other words, the image formation process is performed so that the area where ink is ejected for the additional image A coincides with the area outside the sheet of paper S in the ink ejection range B in Figure 4.

[0026] The details of the above-mentioned additive processing will now be explained. The additive processing is performed on the band-unit image each time band data is generated. First, for band Bf, as shown in Figure 6, when its leading edge is divided in the width direction into multiple block regions a1 (corresponding to the "first reference region" of the present invention), an additive image A1 (corresponding to the "first additive image" of the present invention) is added to the outside of each block region a1. Each block region a1 is a rectangular region consisting of pixels for multiple lines arranged in the front-to-back direction. The additive image A1 corresponds one-to-one with the block region a1 and has the same shape and area as the corresponding block region a1. The corresponding additive images A1 and block regions a1 are arranged adjacent to each other in the front-to-back direction.

[0027] The content of the additional image A1 is adjusted according to the content of the block region a1. Specifically, the arrangement of pixels constituting the additional image A1 matches the arrangement of pixels constituting the block region a1, and for each of the C, M, Y, and K planes, the pixel values ​​on the additional image A1 side are adjusted so that the pixel values ​​on the additional image A1 side are smaller than the pixel values ​​on the block region a1 side for each corresponding pixel between the additional image A1 and the block region a1. Thus, because the pixel values ​​on the additional image A1 side are smaller than the pixel values ​​on the block region a1 side, and because the additional image A1 has the same area as the block region a1, it is derived that the total amount of ink used in the image formation operation for the additional image A1 is smaller than the total amount of ink used in the image formation operation for the block region a1.

[0028] More specifically, the relationship between the pixel density in block region a1 and the pixel value in additional image A1, as shown in Table 1 below, is used. The pixel density in Table 1 represents the pixel density in block region a1. The halftone coefficient indicates the degree to which the pixel value in additional image A1 is reduced relative to the pixel value in block region a1. A larger halftone coefficient corresponds to a greater degree of reduction. The halftone coefficient may be used, for example, as one coefficient in a function used to calculate the pixel value in additional image A1 using the pixel value in block region a1. As a specific example, the pixel value in additional image A1 may be calculated by multiplying the pixel value in block region a1 by the reciprocal of the halftone coefficient. Alternatively, different reduction rates may be obtained by conditional branching based on the halftone coefficient using an algorithm that obtains the reduction rate of the pixel value in additional image A1 relative to the pixel value in block region a1. As shown in Table 1, the lower the pixel density, the larger the halftone coefficient. In other words, the degree of reduction of the pixel value in additional image A1 relative to the pixel value in block region a1 is greater. Based on these halftone coefficients, the additional image A1 is adjusted so that the magnitude of the pixel values ​​in the additional image A1, i.e., the increase or decrease in the total amount of ink used, corresponds to the magnitude of the pixel density in the block region a1, i.e., the increase or decrease in the total amount of ink used.

[0029] [Table 1]

[0030] Figures 9(a) and 9(b) show, as an example, corresponding portions of block region a1 and additional image A1. Figures 9(c) and 9(d) show, as an example, other corresponding portions of block region a1 and additional image A1. The width of the hatching in each pixel in the figures represents the intensity of the color. Darker colors correspond to larger pixel values.

[0031] The additional images A1 in Figures 9(b) and 9(d) were acquired using Table 1 based on the block region a1 in Figures 9(a) and 9(c). When pixels are relatively densely present, as in block region a1 in Figure 9(a), a small halftone coefficient corresponding to a relatively large pixel density is used in Table 1. Therefore, as shown in Figure 9(b), additional image A1 is composed of pixels that are relatively close in density (low reduction rate) to the pixels in block region a1. On the other hand, when pixels are relatively sparsely present, as in block region a1 in Figure 9(c), a large halftone coefficient corresponding to a relatively small pixel density is used in Table 1. Therefore, as shown in Figure 9(d), additional image A1 is composed of pixels that are relatively lighter (higher reduction rate) than the pixels in block region a1.

[0032] Furthermore, as shown in Figure 6, when the left end of band Bf is divided in the front-to-back direction into multiple block regions a2 (corresponding to the "second reference region" of the present invention), an additional image A2 (corresponding to the "second additional image" of the present invention) is added to the outside of each block region a2. Each block region a2 is a rectangular region consisting of pixels for multiple lines arranged in the front-to-back direction. The additional image A2 corresponds one-to-one with the block region a2 and has the same shape and area as the corresponding block region a2. The corresponding additional images A2 and block regions a2 are arranged adjacent to each other in the width direction.

[0033] The content of the additional image A2 is adjusted according to the content of block region a2. Specifically, the arrangement of pixels constituting the additional image A2 matches the arrangement of pixels constituting block region a2, and for each of the C, M, Y, and K planes, the pixel values ​​on the additional image A2 side are adjusted so that the pixel values ​​on the additional image A2 side are smaller than the pixel values ​​on the block region a2 side for corresponding pixels between the additional image A2 and block region a2. More specifically, the relationship between the pixel density in block region a2 and the pixel values ​​in additional image A2, as shown in Table 1 above, is used. The specific method for adjusting the pixel values ​​of each pixel in additional image A2 is the same as the method for additional image A1. Therefore, the total amount of ink used in the image formation operation for additional image A2 is smaller than the total amount of ink used in the image formation operation for block region a2.

[0034] Furthermore, as shown in Figure 6, when the right end of band Bf is divided in the front-to-back direction into multiple block regions a3 (corresponding to the "third reference region" of the present invention), an additional image A3 (corresponding to the "third additional image" of the present invention) is added to the outside of each block region a3. Block region a3 and additional image A3 are arranged symmetrically in the width direction with respect to block region a2 and additional image A2. The specific method for adjusting the content of additional image A3 is the same as the method for additional image A2 described above.

[0035] Furthermore, as shown in Figure 6, a block region a4 smaller in width than block region a1 is set at the upper left corner of band Bf. An additional image A4 is added outside block region a4. Additional image A4 has an L-shaped bend along the corner. The content of additional image A4 is adjusted so that the total amount of ink used in the image formation operation for additional image A4 is less than the total amount of ink used in the image formation operation for block region a4.

[0036] Furthermore, as shown in Figure 6, a block region a5, which is smaller in width than block region a1, is set at the upper right corner of band Bf. An additional image A5 is added outside block region a5. The additional image A5 has an L-shaped bend along the corner. The content of the additional image A5 is adjusted so that the total amount of ink used in the image formation operation for the additional image A5 is less than the total amount of ink used in the image formation operation for block region a5.

[0037] As shown in Figure 7, when the left end of band Bm is divided in the front-to-back direction into multiple block regions a6 (corresponding to the "fourth reference region" of the present invention), an additional image A6 (corresponding to the "fourth additional image" of the present invention) is added to the outside of each block region a6. Each block region a6 is a rectangular region consisting of pixels for multiple lines arranged in the front-to-back direction. The additional image A6 corresponds one-to-one with the block region a6 and has the same shape and area as the corresponding block region a6. The corresponding additional images A6 and block regions a6 are arranged adjacent to each other in the width direction.

[0038] The content of the additional image A6 is adjusted according to the content of the block region a6. Specifically, the arrangement of pixels constituting the additional image A6 matches the arrangement of pixels constituting the block region a6, and for each of the C, M, Y, and K planes, the pixel values ​​on the additional image A6 side are adjusted so that the pixel values ​​on the additional image A6 side are smaller than the pixel values ​​on the block region a6 side for corresponding pixels between the additional image A6 and the block region a6. More specifically, the relationship between the pixel density in the block region a6 and the pixel values ​​in the additional image A6, as shown in Table 1 above, is used. The specific method for adjusting the pixel values ​​of each pixel in the additional image A6 is the same as the method described above for the additional image A1. Therefore, the total amount of ink used in the image formation operation for the additional image A6 is smaller than the total amount of ink used in the image formation operation for the block region a6.

[0039] Furthermore, as shown in Figure 7, when the right end of band Bm is divided in the front-to-back direction into multiple block regions a7 (corresponding to the "fifth reference region" of the present invention), an additional image A7 (corresponding to the "fifth additional image" of the present invention) is added to the outside of each block region a7. Block region a7 and additional image A7 are arranged symmetrically in the width direction with respect to block region a6 and additional image A6. The specific method for adjusting the content of additional image A7 is the same as the method described above for additional image A6.

[0040] As shown in Figure 8, when the trailing end of the band Br is divided in the width direction into multiple block regions a8 (corresponding to the "sixth reference region" of the present invention), an additional image A8 (corresponding to the "sixth additional image" of the present invention) is added to the outside of each block region a8. Each block region a8 is a rectangular region consisting of pixels for multiple lines arranged in the front-to-back direction. The additional image A8 corresponds one-to-one with the block region a8 and has the same shape and area as the corresponding block region a8. The corresponding additional images A8 and block regions a8 are arranged adjacent to each other in the front-to-back direction.

[0041] The content of the additional image A8 is adjusted according to the content of the block region a8. Specifically, the arrangement of pixels constituting the additional image A8 matches the arrangement of pixels constituting the block region a8, and for each of the C, M, Y, and K planes, the pixel values ​​of the additional image A8 are adjusted so that the pixel values ​​of corresponding pixels between the additional image A8 and the block region a8 are smaller than the pixel values ​​of the block region a8. More specifically, the relationship between the pixel density in the block region a8 and the pixel values ​​in the additional image A8, as shown in Table 1 above, is used. The specific method for adjusting the pixel values ​​of each pixel in the additional image A8 is the same as the method described above for the additional image A1. Therefore, the total amount of ink used in the image formation operation for the additional image A8 is smaller than the total amount of ink used in the image formation operation for the block region a8.

[0042] Furthermore, as shown in Figure 8, when the left end of the band Br is divided in the front-to-back direction into multiple block regions a9 (corresponding to the "seventh reference region" of the present invention), an additional image A9 (corresponding to the "seventh additional image" of the present invention) is added to the outside of each block region a9. Each block region a9 is a rectangular region consisting of pixels for multiple lines arranged in the front-to-back direction. The additional image A9 corresponds one-to-one with the block region a9 and has the same shape and area as the corresponding block region a9. The corresponding additional images A9 and block regions a9 are arranged adjacent to each other in the width direction.

[0043] The content of the additional image A9 is adjusted according to the content of the block region a9. Specifically, the arrangement of pixels constituting the additional image A9 matches the arrangement of pixels constituting the block region a9, and for each of the C, M, Y, and K planes, the pixel values ​​on the additional image A9 side are adjusted so that the pixel values ​​on the additional image A9 side are smaller than the pixel values ​​on the block region a9 side for corresponding pixels between the additional image A9 and the block region a9. More specifically, the relationship between the pixel density in the block region a9 and the pixel values ​​in the additional image A9, as shown in Table 1 as an example, is used. The specific method for adjusting the pixel values ​​of each pixel in the additional image A9 is the same as the method described above for the additional image A1. Therefore, the total amount of ink used in the image formation operation for the additional image A9 is smaller than the total amount of ink used in the image formation operation for the block region a9.

[0044] Furthermore, as shown in Figure 8, when the right end of the band Br is divided in the front-to-back direction into multiple block regions a10 (corresponding to the "eighth reference region" of the present invention), an additional image A10 (corresponding to the "eighth additional image" of the present invention) is added to the outside of each block region a10. The block region a10 and the additional image A10 are arranged symmetrically in the width direction with respect to the block region a9 and the additional image A9. The specific method for adjusting the content of the additional image A10 is the same as the method described above for the additional image A9.

[0045] Furthermore, as shown in Figure 8, a block region a11, smaller in width than block region a8, is set at the lower left corner of band Br. An additional image A11 is added outside block region a11. The additional image A11 has an L-shaped bend along the corner. The content of the additional image A11 is adjusted so that the total amount of ink used in the image formation operation for the additional image A11 is less than the total amount of ink used in the image formation operation for block region a11.

[0046] Furthermore, as shown in Figure 8, a block region a12 smaller in width than block region a8 is set at the lower right corner of band Br. An additional image A12 is added outside block region a12. The additional image A12 has an L-shaped bend along the corner. The content of the additional image A12 is adjusted so that the total amount of ink used in the image formation operation for the additional image A12 is less than the total amount of ink used in the image formation operation for block region a12.

[0047] The following describes the flow of additional processing performed by the control unit 9 with reference to Figures 10 to 12. As shown in Figure 10, the control unit 9 generates band data by converting vector data to raster data (S1). The band data is generated in the order of bands Bf, Bm, and Br, and the process in S2 is performed each time a band is generated. In S2, the control unit 9 determines whether the data generated in S1 relates to band Bf. If it is determined that the data generated in S1 relates to band Bf (S2, Yes), the control unit 9 performs the Bf processing (S4). The Bf processing is a process that adds additional images A1 to A5 to band Bf by processing the band data corresponding to band Bf, as will be described later. Then, the process in S1 is performed.

[0048] If it is determined that the data generated in S1 is not related to band Bf (S2, No), the control unit 9 determines whether the data generated in S1 is related to band Br (S3). If it is determined that the data generated in S1 is not related to band Br (S3, No), the control unit 9 performs Bm processing (S5). As described later, Bm processing is a process that adds additional images A6 and A7 to band Bm by processing the band data corresponding to band Bm. Then, the process in S1 is performed.

[0049] If it is determined that the data generated in S1 is related to the band Br (S3, Yes), the control unit 9 executes Br processing (S6). As described later, Br processing is the process of adding additional images A8 to A12 to the band Br by processing the band data corresponding to the band Br. Then the series of processes is completed.

[0050] The details of the Bf processing in S4 are as follows. As shown in Figure 11, the control unit 9 determines the blank state at the leading edge of band Bf (S11). Specifically, the control unit 9 determines how many blank lines are consecutive from the leading edge of band Bf. Here, a blank line corresponds to a line in which blank pixels are continuous from the left edge to the right edge of band Bf.

[0051] Next, the control unit 9 determines whether the number of blank lines identified in S11 is greater than or equal to a predetermined value (S12). If it determines that the number of blank lines is greater than or equal to a predetermined value (S12, Yes), the control unit 9 sets all of the additional image A1 and all of the additional images A4 and A5 to blank images and adds them to band Bf (S13).

[0052] Next, the control unit 9 sets the point of interest (see Figure 6) to the leftmost position (S14). The point of interest is the position where processing is performed on band Bf. The point of interest is moved one block region to the right at a time (see the white arrow in Figure 6), from the position of block region a4, which corresponds to the leftmost end of band Bf, to the position of block region a5, which corresponds to the rightmost end of band Bf, and processing is performed.

[0053] In S15, the control unit 9 determines whether the point of interest is at the left edge. If it determines that the point of interest is at the left edge (S15, Yes), the control unit 9 determines whether the additional image A4 has already been added, that is, whether S13 has been executed (S16). If it determines that the additional image A4 has not already been added (S16, No), the control unit 9 adds the additional image A4 corresponding to the pixel density of the block region a4 to the band Bf (S17) and executes S18. If it determines that the additional image A4 has already been added (S16, Yes), the control unit 9 does not execute S17 and executes S18. In S18, the control unit 9 adds the additional image A2 corresponding to the pixel density of each block region a2 that are arranged in the front-to-back direction at the left edge of the band Bf to each of the block regions a2.

[0054] Next, the control unit 9 determines whether or not there is a next point of interest (S19). Whether or not there is a next point of interest corresponds to whether or not the point of interest can be moved one position to the right of the current point of interest. In this process, if the point of interest is in any of the block regions a1, a2, and a4, it is determined that there is a next point of interest. On the other hand, if the point of interest is in block region a3, it is determined that there is no next point of interest. If it is determined that there is a next point of interest (S19, Yes), the control unit 9 moves the point of interest to the block region one position to the right (S20) and executes the process in S15. If it is determined that there is no next point of interest (S19, No), the control unit 9 executes the process in S1 of Figure 10.

[0055] If it is determined in S15 that the position of interest is not at the left end (S15, No), the control unit 9 determines whether the position of interest is at the right end (S21). If it is determined that the position of interest is at the right end (S21, Yes), the control unit 9 determines whether the additional image A5 has already been added, that is, whether S13 has been executed (S22). If it is determined that the additional image A5 has not already been added (S22, No), the control unit 9 adds the additional image A5 corresponding to the pixel density of block region a5 to band Bf (S23) and executes S24. If it is determined that the additional image A5 has already been added (S22, Yes), the control unit 9 does not execute S23 and executes S24. In S24, the control unit 9 adds the additional image A3 corresponding to the pixel density of each block region a3 that are arranged in the front-to-back direction at the right end of band Bf to each block region a3. Then, the control unit 9 executes the process in S19.

[0056] If it is determined in S21 that the position of interest is not at the right edge (S21, No), the control unit 9 determines whether the additional image A1 has already been added, that is, whether S13 has been executed (S25). If it is determined that the additional image A1 has not already been added (S25, No), the control unit 9 adds the additional image A1 corresponding to the pixel density of block region a1 to band Bf (S26) and executes S19. If it is determined that the additional image A1 has already been added (S25, Yes), the control unit 9 does not execute S26 and executes S19.

[0057] The details of the Bm processing in S5 are as follows. As shown in Figure 12, the control unit 9 adds an additional image A6 to each of the block regions a6 that are arranged in the front-to-back direction at the left end of the band Bm, according to the respective pixel density of each block region a6 (S27). Next, the control unit 9 adds an additional image A7 to each of the block regions a7 that are arranged in the front-to-back direction at the right end of the band Bm, according to the respective pixel density of each block region a7 (S27).

[0058] The details of the Br processing in S6 are as follows. As shown in Figure 13, the control unit 9 determines the blank state at the trailing end of the band Br (S31). Specifically, the control unit 9 determines how many blank lines are continuous from the trailing end of the band Br. Here, a blank line corresponds to a line in which blank pixels are continuous from the left end to the right end of the band Br.

[0059] Next, the control unit 9 determines whether the number of blank lines identified in S31 is greater than or equal to a predetermined value (S32). If it determines that the number of blank lines is greater than or equal to a predetermined value (S32, Yes), the control unit 9 sets all of the additional image A8 and all of the additional images A11 and A12 to blank images and adds them to the band Br (S33).

[0060] Next, the control unit 9 sets the point of interest (see Figure 8) to the leftmost position (S34). The point of interest is the position where processing is performed on the band Br. The point of interest is moved one block region to the right at a time (see the white arrow in Figure 8), from the position of block region a11, which corresponds to the leftmost end of the band Br, to the position of block region a12, which corresponds to the rightmost end of the band Br, and processing is performed.

[0061] In S35, the control unit 9 determines whether the point of interest is at the left edge. If it determines that the point of interest is at the left edge (S35, Yes), the control unit 9 determines whether the additional image A11 has already been added, that is, whether S33 has been executed (S36). If it determines that the additional image A11 has not already been added (S36, No), the control unit 9 adds the additional image A11 corresponding to the pixel density of the block region a11 to the band Br (S37) and executes S38. If it determines that the additional image A11 has already been added (S36, Yes), the control unit 9 does not execute S37 and executes S38. In S38, the control unit 9 adds the additional image A9 corresponding to the pixel density of each block region a9 that are arranged in the front-to-back direction at the left edge of the band Br to each block region a9.

[0062] Next, the control unit 9 determines whether or not there is a next point of interest (S39). Whether or not there is a next point of interest corresponds to whether or not the point of interest can be moved one position to the right of the current point of interest. In this process, if the point of interest is in any of the block regions a8, a9, and a11, it is determined that there is a next point of interest. On the other hand, if the point of interest is in block region a10, it is determined that there is no next point of interest. If it is determined that there is a next point of interest (S39, Yes), the control unit 9 moves the point of interest to the block region one position to the right (S40) and executes the process in S35. If it is determined that there is no next point of interest (S39, No), the control unit 9 executes the process in S3 of Figure 10.

[0063] If the control unit 9 determines in S35 that the position of interest is not at the left end (S35, No), it determines whether the position of interest is at the right end (S41). If the control unit 9 determines that the position of interest is at the right end (S41, Yes), it determines whether the additional image A12 has already been added, that is, whether S33 has been executed (S42). If the control unit 9 determines that the additional image A12 has not already been added (S42, No), it adds the additional image A12 corresponding to the pixel density of the block region a12 to the band Br (S43) and executes S44. If the control unit 9 determines that the additional image A12 has already been added (S42, Yes), it does not execute S43 and executes S44. In S44, the control unit 9 adds the additional image A10 corresponding to the pixel density of each block region a10 that are arranged in the front-to-back direction at the right end of the band Br to each block region a10. Then, the control unit 9 executes the process of S39.

[0064] If it is determined in S41 that the position of interest is not at the right edge (S41, No), the control unit 9 determines whether the additional image A8 has already been added, that is, whether S33 has been executed (S45). If it is determined that the additional image A8 has not already been added (S45, No), the control unit 9 adds the additional image A8 corresponding to the pixel density of block region a8 to band Br (S46) and executes S39. If it is determined that the additional image A8 has already been added (S45, Yes), the control unit 9 does not execute S46 and executes S39.

[0065] According to the embodiment described above, the total amount of ink used in the image formation operation for the additional images A1 to A12 is less than the total amount of ink used in the image formation operation for the block regions a1 to a12. For example, if borderless printing is performed by enlarging the original image to a size larger than the paper S, or by adding an image identical to the edge region of the original image to the outside of the original image, the amount of ink used for the portion that extends beyond the paper S will be proportional to a portion of the original image, which may not be suitable for the requirement to reduce ink consumption. In contrast, in this embodiment, the total amount of ink used in the image formation operation for the additional images A1 to A12, which correspond to the portion that extends beyond the paper S, is less than the amount of ink used in the image formation operation for the block regions a1 to a12 (both portions of the original image). Therefore, ink consumption can be reduced. As a result, an apparatus capable of reducing ink consumption in borderless image formation processing is realized.

[0066] Furthermore, in the above embodiment, some block regions (for example, block regions a1-a3, a6-a10) are aligned along the edges of the original image, and additional images (for example, additional images A1-A3, A6-A10) are adjacent to each of these block regions. This makes it possible to reduce ink consumption for each combination of these block regions and additional images aligned along the edges of the original image.

[0067] Furthermore, in the above-described embodiment, the total amount of ink used in each additional image (for example, additional images A1 to A3, A6 to A10) increases or decreases in accordance with the increase or decrease in the total amount of ink used in each block region (for example, block regions a1 to a3, a6 to a10). In other words, the amount of ink consumed by each additional image varies according to the content of each block region of the original image, thus avoiding unnatural fluctuations in ink consumption due to the addition of additional images.

[0068] Furthermore, in the above-described embodiment, the arrangement of pixels constituting some of the additional images (for example, additional images A1-A3, A6-A10) matches the arrangement of pixels constituting some of the block regions (for example, block regions a1-a3, a6-a10). In other words, there is a one-to-one correspondence between pixels in the additional images and the block regions. And, for corresponding pixel values ​​in the additional images and block regions, the former value is smaller than the latter value. In other words, the additional images are adjusted so that the amount of ink used per pixel is reduced. Therefore, it is possible to reliably reduce ink consumption.

[0069] Furthermore, in the above-described embodiment, the added image is adjusted using a halftone coefficient, which is shown as an example in Table 1. The halftone coefficient indicates the degree to which the pixel values ​​in the added image are reduced relative to the pixel values ​​in the block region. As shown in Table 1, the smaller the pixel density in the block region, the larger the halftone coefficient. A larger halftone coefficient corresponds to a greater degree of pixel value reduction. Also, lower pixel density and pixel values ​​tend to lead to a reduction in ink usage. In other words, by adjusting the added image based on the halftone coefficient, the smaller the total amount of ink used in the block region, the smaller the ratio of the total amount of ink used in the added image to the total amount of ink used in the block region tends to be. Therefore, the effect of reducing ink consumption is more easily ensured.

[0070] Furthermore, according to the above-described embodiment, borderless printing is performed so that the original image is formed exactly across the entire sheet of paper S. In other words, the entire original image is formed within the boundaries of the sheet of paper S. Therefore, compared to cases where borderless printing is performed by enlarging the original image beyond the boundaries of the sheet of paper S, the quality of the image formed on the sheet of paper S is ensured.

[0071] Furthermore, according to the above embodiment, each time band data related to bands Bf, Bm, and Br is generated, an additional image is added to each of the bands Bf, Bm, and Br. Therefore, the additional images are appropriately adjusted for each band corresponding to the front, middle, and rear ends of the original image.

[0072] Furthermore, according to the above embodiment, if the number of blank lines at the front end of band Bf or the rear end of band Br is greater than or equal to a predetermined value, the additional image A1 or A8 is set to a blank image (S11-S13 in Figure 11 or S31-S33 in Figure 13). This sets the additional image to appropriate content according to the blank space at the front or rear end of the original image.

[0073] <Other variations> Although embodiments of the present invention have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of the present invention is indicated by the claims rather than the above description of embodiments, and all modifications within the meaning and scope equivalent to the claims are included.

[0074] For example, in each of the embodiments described above, borderless printing is performed so that the original image I shown in Figure 5 is formed on the entire sheet of paper S. In contrast, the formation range of the original image I may be changed so that it fits within the sheet of paper S. For example, the original image I may be formed on the sheet of paper S to the same size as the size indicated by the image data, similar to the bordered printing process. In either case, if the added image A is added to the original image I so that it straddles the outer edge of the sheet of paper S (i.e., so that a part of the added image A is positioned outside the sheet of paper S), borderless printing will be performed appropriately. Furthermore, the quality of the image formed on the sheet of paper S is ensured compared to the case where the original image is enlarged to exceed the boundaries of the sheet of paper S.

[0075] Furthermore, in the above-described embodiment, block regions are defined as rectangular areas on the original image aligned along the edges of the original image. Additional images are added to each block region such that the total amount of ink used for the additional images is less than the total amount of ink used for the block regions. Alternatively, a single additional image may be added to a band-shaped reference region extending across the entire edge of the original image. In this case, the content of the additional image should be adjusted so that the total amount of ink used for this single additional image is less than the total amount of ink used for the band-shaped reference region.

[0076] Furthermore, in the above-described embodiment, there is a one-to-one correspondence between pixels in the block region a1, etc. and the additional image A1, etc. However, there is no need for a one-to-one correspondence between pixels in the block region a1, etc. and the additional image A1, etc. It is sufficient that the content of the additional image is adjusted so that the total amount of ink used in the additional image is less than the total amount of ink used in the block region. For example, the pixel values ​​of the additional image may be uniformly set so that the average value of the pixel values ​​in the additional image is less than the average value of the pixel values ​​in the block region.

[0077] In addition, although the embodiments described above have described the application of the present invention to printers, it is not limited thereto. The present invention may also be applied to other inkjet-type image forming devices that eject ink from a head, such as multifunction printers and copiers, or to these image forming devices. Furthermore, the present invention may be applied to devices that use liquids such as various processing solutions instead of ink. [Explanation of Symbols]

[0078] 2. Conveying mechanism 5 heads 6 Moving mechanism 9. Control Unit 100 Printers

Claims

1. An image forming unit that performs an image forming operation by applying liquid to a medium, It includes a control unit, The control unit, An additional process that generates the image by adding an additional image to the outside of the original image, A borderless image forming process is performed, in which the image forming unit is instructed to perform the image forming operation such that at least a portion of the area where the additional image is formed is located outside the medium and the original image is formed on the medium. An image forming apparatus characterized in that the total amount of liquid used in the image forming operation with respect to the added image is less than the total amount of liquid used in the image forming operation with respect to a reference region that is a part of the original image, adjacent to the added image in the image, and having the same area as the added image.

2. The control unit, in the additional processing, Each of the rectangular regions on the original image that are aligned along the edges of the original image is set as the reference region, The image forming apparatus according to claim 1, characterized in that an additional image having the same shape as the reference region is added to each of the reference regions so as to be adjacent to the reference region.

3. The image forming apparatus according to claim 3, characterized in that the total amount of liquid used in the image forming operation with respect to the additional image increases or decreases in accordance with the increase or decrease in the total amount of liquid used in the image forming operation with respect to the reference region.

4. The smaller the value of each pixel constituting the additional image, the smaller the amount of liquid used for that pixel in the image forming operation. The image forming apparatus according to claim 3, characterized in that each pixel included in the reference region corresponds one-to-one with each pixel included in the additional image, and the value of the pixel included in the additional image is smaller than the value of the pixel included in the reference region.

5. The image forming apparatus according to claim 3, characterized in that the ratio of the total amount of liquid used in the image forming operation for the additional image to the total amount of liquid used in the image forming operation for the reference region is smaller as the total amount of liquid used in the image forming operation for the reference region is smaller.

6. The smaller the value of each pixel constituting the additional image, the smaller the amount of liquid used for that pixel in the image forming operation. The image forming apparatus according to claim 5, characterized in that each pixel in the reference region corresponds one-to-one with each pixel in the additional image, and the ratio of the value of a pixel in the additional image to the value of a pixel in the reference region is smaller as the pixel density in the reference region decreases.

7. The control unit, An image data acquisition process is performed to obtain image data showing the aforementioned original image from an external source. The image forming apparatus according to claim 1, characterized in that the image forming process is performed so that the original image is formed on the medium in a size equal to the size indicated by the image data, or within a range that fits within the medium.

8. The control unit, In the original image, band processing is performed to generate band data indicating the pixel values ​​of the original image for each rectangular region extending across its entire width. The image forming apparatus according to claim 1, characterized in that each time the band data is generated by the band processing, the additional processing is performed on the band which is a part of the original image indicated by the band data.

9. The control unit, In the above additional processing, With respect to the band corresponding to the front end of the original image, A portion of the band corresponding to a predetermined number of pixels from the front end of the band is defined as the first reference region. A portion of the band corresponding to a predetermined number of pixels from the left end of the band is defined as the second reference region. A portion of the band corresponding to a predetermined number of pixels from the right end of the band is designated as the third reference region, The image forming apparatus according to claim 8, characterized in that a first additional image corresponding to the first reference region is added to the front end of the band, a second additional image corresponding to the second reference region is added to the left end of the band, and a third additional image corresponding to the third reference region is added to the right end of the band.

10. The aforementioned additional processing is, A first determination process determines whether the entire set of pixels from the front edge of the original image for a predetermined number of rows in the first reference region is blank, The image forming apparatus according to claim 9, further comprising a first blank setting process, which sets the entire first additional image to blank if the first determination process determines that the entire pixels for a predetermined number of rows from the front end of the original image are blank.

11. The control unit, In the above additional processing, With respect to the band corresponding to the intermediate portion sandwiched between its front end and rear end in the original image, A portion of the band corresponding to a predetermined number of pixels from the left end of the band is defined as the fourth reference region. A portion of the band corresponding to a predetermined number of pixels from the right end of the band is designated as the fifth reference region, The image forming apparatus according to claim 8, characterized in that a fourth additional image corresponding to the fourth reference region is added to the left end of the band, and a fifth additional image corresponding to the fifth reference region is added to the right end of the original image.

12. The control unit, In the above additional processing, With respect to the band data corresponding to the trailing end of the original image, A portion of the band corresponding to a predetermined number of pixels from the trailing end of the band is defined as the sixth reference region. A portion of the band corresponding to a predetermined number of pixels from the left end of the band is defined as the seventh reference region. A portion of the band corresponding to a predetermined number of pixels from the right end of the band is designated as the eighth reference region, The image forming apparatus according to claim 8, characterized in that a sixth additional image corresponding to the sixth reference region is added to the rear end of the band, a seventh additional image corresponding to the seventh reference region is added to the left end of the band, and an eighth additional image corresponding to the eighth reference region is added to the right end of the band.

13. The aforementioned additional processing is, In the sixth reference region, a second determination process determines whether the entire set of pixels from the trailing end of the original image for a predetermined number of rows is blank, The image forming apparatus according to claim 12, further comprising a second blank setting process, which sets the entire sixth additional image to blank if the second determination process determines that the entire pixels for a predetermined number of rows from the trailing end of the original image are blank.

Images