Image formation apparatus and control method for image formation apparatus

Abstract

To provide an image formation apparatus capable of printing an image written into a line memory with a delay without displacement from a correct position in a main scanning direction even when a writing delay to the line memory occurs due to discharge noise.SOLUTION: An image formation apparatus comprises an image formation unit and a line memory that constitutes a ring buffer. The line memory stores image data corresponding to a natural number of lines in the main scanning direction that constitutes a print image, and the image formation unit forms a print image corresponding to the natural number of lines on a medium on the basis of the image data stored in the line memory.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus and the like. [Background technology]

[0002] Generally, MFPs (Multi-Function Printers / Peripherals) that use the electrophotographic printing method have a shaft inside the toner cassette or fuser that rotates during copying or printing. If the shaft is not properly grounded, static electricity may be suddenly discharged from the shaft that has become charged by rotation.

[0003] In relation to the present disclosure, Patent Document 1 describes an LSU (Laser Scanning Unit) that has a light source with multiple light-emitting elements, has multiple ring buffers, and is capable of reading out one line of image data written to each buffer regardless of the input image data, and making two pieces of image data to be subjected to image processing be adjacent lines, even though the circuit scale is small. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-214454 Summary of the Invention [Problem to be solved by the invention]

[0005] The effects of this discharge noise can cause the line memory to take longer to write than usual. In conventional MFPs, this delay in writing to the line memory can sometimes prevent the original image from being printed correctly. In particular, the line image in the printed image can sometimes be printed shifted from its correct position in the line direction, i.e., the main scanning direction.

[0006] The problem to be solved by this disclosure is to provide an image forming device that can print an image written with a delay without shifting from the correct position in the main scanning direction, even if a delay in writing to a line memory occurs due to discharge noise. [Means for solving the problem]

[0007] The present disclosure provides an image forming device that includes an image forming unit and a line memory that forms a ring buffer, wherein the line memory stores image data corresponding to a natural number of lines in the main scanning direction that form part of a print image, and the image forming unit forms a print image corresponding to the natural number of lines on a medium based on the image data stored in the line memory.

[0008] The present disclosure also provides a control method for an image forming device that includes a line memory that constitutes a ring buffer, wherein the line memory stores image data corresponding to a natural number of lines in the main scanning direction that constitute part of a print image, and the image forming device forms a print image corresponding to the natural number of lines on a medium based on the image data stored in the line memory. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide an image forming apparatus that can print an image written with a delay without being shifted from the correct position in the main scanning direction even if a delay in writing to a line memory occurs due to discharge noise. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a conceptual schematic diagram illustrating an image forming system according to a first embodiment of the present disclosure. [Figure 2] 1 is a functional block diagram of an MFP according to a first embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic conceptual diagram illustrating the process of generating print data from image data of an original image in a conventional MFP. [Figure 4]10A and 10B are conceptual schematic diagrams for explaining the mechanism by which image misalignment occurs due to discharge noise when print data is generated from image data of an original image in a conventional MFP. [Figure 5] 5A and 5B are diagrams for comparing and contrasting a conventional method of allocating lines to a ring buffer with the method of the present disclosure, where FIG. 5A is a diagram for explaining the conventional method of allocating lines to a ring buffer, and FIG. 5B is a diagram for explaining the method of allocating lines to a ring buffer of the present disclosure. [Figure 6] 10 is a flowchart for explaining an operation for setting an offset size of a ring buffer in the MFP according to the first embodiment of the present disclosure. [Figure 7] 7A and 7B are diagrams for comparing and contrasting the changes in line allocation in a ring buffer when the ring buffer is operating normally and when a delay in writing to the ring buffer occurs in a conventional MFP. FIG. 7A shows the changes when the ring buffer is operating normally, and FIG. 7B shows an example of the changes when a delay in writing occurs. [Figure 8] This figure compares the print image formed when a conventional MFP is operating normally with the print image formed when there is a delay in writing to the ring buffer. Figure 8(A) shows the print image under normal conditions, and Figure 8(B) shows the print image in which image misalignment has occurred due to the write delay. [Figure 9] 9A and 9B are diagrams for comparing and contrasting the changes in line allocation in a ring buffer when the ring buffer is operating normally and when a delay in writing to the ring buffer occurs in an MFP according to the first embodiment of the present disclosure, where FIG. 9A shows the changes when the MFP is operating normally and FIG. 9B shows the changes when a delay in writing occurs. [Figure 10] 10A and 10B are diagrams showing a printed image in which image misalignment occurs due to a delay in writing to a ring buffer in the MFP according to the first embodiment of the present disclosure. [Figure 11]11A and 11B are diagrams for explaining the effects of the MFP according to the first embodiment of the present disclosure, in which FIG. 11A is a sample image that has been printed normally, FIG. 11B is an image that reproduces the image misalignment that occurs when there is a delay in writing to the ring buffer in a conventional MFP, and FIG. 11C is an image that reproduces the suppressed image misalignment that occurs when there is a delay in writing to the ring buffer in the MFP according to the first embodiment of the present disclosure. [Figure 12] 12A and 12B are diagrams for explaining the effects of the MFP according to the first embodiment of the present disclosure, in which FIG. 12A is a partial enlarged view of FIG. 11C, which reproduces the suppressed image misalignment when there is a delay in writing to the ring buffer in the MFP according to the first embodiment of the present disclosure, and FIG. 12B is a partial enlarged view of the area corresponding to FIG. 12A in a properly printed sample image. [Figure 13] 10 is a flowchart for explaining an operation for setting an offset size of a ring buffer in an MFP according to a second embodiment of the present disclosure. [Figure 14] FIG. 10 is a functional block diagram of an MFP according to a third embodiment of the present disclosure. [Figure 15] FIG. 11 is a schematic conceptual diagram illustrating a process of generating print data from image data of an original image in an MFP according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] [1. First embodiment] [1.1 System Configuration] 1 is a conceptual schematic diagram of an image forming system 101 according to a first embodiment of the present disclosure. The image forming system 101 includes an MFP (Multi-Function Printer / Peripheral) 1, a terminal device 2, and a network NW. The terminal device 2 is an information processing device capable of data communication with the MFP 1 via the network NW, and is, for example, a desktop computer, a laptop computer, a workstation, a smartphone, or a tablet. The network NW is a data communication network. The network NW is a LAN (Local Area Network), a mobile communication network, the Internet, or a combination thereof.

[0012] 2 is a functional block diagram of the MFP 1. The MFP 1 is a type of image forming device and typically has a copy function, an image scanner function, a facsimile function, and a printer function. The MFP 1 may also have other functions, such as an email sending / receiving function, a file server function, etc.

[0013] The control unit 3 controls the entire image forming apparatus. The control unit 3 is made up of one or more control devices and control circuits, and is made up of, for example, a CPU (Central Processing Unit), which is a processor that executes various types of arithmetic processing, an SoC (System on a Chip), etc. The control unit 3 can also realize each function by reading out programs stored in the storage unit 5 and executing the processes.

[0014] The storage unit 5 stores various programs and data necessary for the operation of the image forming apparatus. The storage unit 5 includes one or more recording devices capable of temporary storage, such as a dynamic random access memory (DRAM), and non-temporary recording devices, such as a solid state drive (SSD) made of semiconductor memory or a hard disk drive (HDD) made of magnetic disks. For convenience of explanation, the storage unit 5 is shown as a single unit, but it may also be configured as separate devices for different purposes, such as an area used for executing programs (main storage area), an area for saving programs and data (auxiliary storage area), an area used for caching, etc.

[0015] The display unit 7 displays images and characters. For example, it is configured with a liquid crystal display (LCD), an organic EL (Electro-Luminescence) panel, etc. The display unit 7 may be a standalone display device, or may further include an externally connected display device.

[0016] The operation unit 9 accepts operation inputs from a user. For example, the operation unit 9 is configured with hardware keys and / or software keys. The operation unit 9 also includes operation keys such as task keys for issuing instructions to execute tasks such as sending a fax or scanning an image, and a stop key for issuing an instruction to cancel an operation.

[0017] The image input unit 11 reads an image (document) and outputs it as image data. The image input unit 11 is configured with a general scanner (image input device). The image input unit 11 may input image data from an external storage medium such as a USB memory, or may receive an image via a network. Furthermore, the image input unit 11 may include an SPF (Single Path Finder, automatic document feeder).

[0018] Image forming unit 13 forms (prints) an image on a medium such as copy paper based on image data. The printing method of image forming unit 13 is arbitrary, and may be, for example, an inkjet printer, a laser printer, a thermal transfer printer, etc. Image forming unit 13 may be a monochrome printer or a color printer. Image forming unit 13 may include a paper feed mechanism that supplies media, a transport mechanism that transports media, a sorter mechanism that sorts media after images have been formed, etc.

[0019] The communication unit 15 is connected to the network NW and performs data communication with the terminal device 2. The communication unit 15 is configured with an interface that can be connected to, for example, a wired LAN (Local Area Network), a wireless LAN, or an LTE (Long Term Evolution) network. When the communication unit 15 is connected to a network, it is connected to other devices or an external network. In addition to the above, the communication unit 15 may be an interface that performs short-range wireless communication such as NFC (Near Field Communication) or Bluetooth (registered trademark).

[0020] The connection unit 17 connects the image forming apparatus to other devices. For example, the connection unit 17 is a USB interface to which a USB memory or the like is connected. The connection unit 17 may also be an interface other than the USB interface, such as HDMI (registered trademark).

[0021] Image processing unit 19 is, for example, an image processing IC (Integrated Circuit), and outputs CMYK (Cyan, Magenta, Yellow, Key plate) data (video signal) based on image data input from image input unit 11 or communication unit 15. Image processing unit 19 may be an SoC (System-on-a-chip) or an ASIC (Application Specific Integrated Circuit).

[0022] The LSU (Laser Scanning Unit) control unit 21 pre-reads line data from the image processing unit 19 and outputs it to the LSU 23. That is, the LSU control unit 21 outputs print data (CMYK data, PWM, Pulse Width Modulation) to the LSU (Laser Scanning Unit) 23 (described later) based on the image data (CMYK data) input from the image processing unit 19. The LSU control unit 21 includes an IC such as an SoC or ASIC. The LSU control unit 21 includes a line memory 21a for each of the CMYK colors. The line memory 21a stores data in a ring buffer. The MFP 1 includes a line memory 21a (ring buffer) for each of the CMYK colors. When discharge noise occurs momentarily, image misalignment occurs in most cases in one of the CMYK colors, but image misalignment in multiple colors may also occur simultaneously.

[0023] The LSU (Laser Scanning Unit) 23 forms (prints) an image on a medium such as copy paper based on the image data.

[0024] [1.2 Operation of conventional MFPs] 3 is a schematic conceptual diagram for explaining the process of generating print data from image data of an original image in a conventional MFP. To facilitate understanding of the operation of the MFP 1 according to the first embodiment, the operation of the conventional MFP will be explained.

[0025] The LSU control unit 21 includes a line memory 21a, and reads ahead line data and outputs it to the LSU 23. The line memory 21a has a predetermined capacity. In conventional MFPs, the LSU control unit 21 is configured to read ahead as much line data as possible within the capacity of the line memory 21a. For this reason, in conventional MFPs, the line memory 21a (ring buffer) stores image data corresponding to a number of lines including a fraction corresponding to less than one line, rather than image data corresponding to N lines (N is a natural number).

[0026] 3, in a conventional MFP, line memory 21a stores image data corresponding to 2.5 lines. First area 21a1 and second area 21a2 each correspond to one line, and third area 21a3 corresponds to 0.5 lines.

[0027] Figure 4 is a conceptual schematic diagram illustrating the mechanism by which discharge noise 39 causes image misalignment when print data is generated from image data of an original image in a conventional MFP. Generally, when copying or printing is performed on an MFP, the rotating shaft of the MFP's cassette or fuser rotates, generating static electricity as it rotates. If the rotating shaft is not properly grounded, the generated static electricity accumulates on the rotating shaft and is eventually discharged all at once. Discharge noise 39 represents the discharge of this static electricity.

[0028] FIG. 5 is a diagram for comparing and contrasting a conventional method of allocating lines to a ring buffer with the method of the present disclosure. FIG. 5(A) is a diagram for explaining a conventional method of allocating lines to a ring buffer. Here, as shown in FIG. 3, it is assumed that the ring buffer stores image data equivalent to 2.5 lines. The maximum capacity of the ring buffer is 0x4000 bytes. A predetermined amount of unused area is added to the areas used by the actual image data of the first and second lines, and an area of ​​0x1600 bytes is allocated per line. Furthermore, an area of ​​0x800 bytes is allocated for the first half of the third line.

[0029] The LSU control unit 21 controls the line memory 21a as a ring buffer. The LSU control unit 21 writes the first through first half of the third lines into the line memory 21a, and when the writing reaches the ring buffer's maximum capacity of 0x4000 bytes, it returns to the starting address 0x0000 of the line memory 21a and continues writing. Therefore, the LSU control unit 21 starts writing the second half of the third line from the starting address 0x0000. Thereafter, the LSU control unit 21 writes the fourth and fifth lines into the line memory 21a.

[0030] When the first through the first half of the third line are written into the line memory 21a, image data equivalent to 1 line, 1 line, and 0.5 line are stored in the line memory 21a in order from the first address. This arrangement of line data in the line memory 21a is referred to as a 1-1-0.5 arrangement. On the other hand, when the second half of the third line through the fifth line are written into the line memory 21a, image data equivalent to 0.5 line, 1 line, and 1 line are stored in the line memory 21a in order from the first address. This arrangement of line data in the line memory 21a is referred to as a 0.5-1-1 arrangement. The 1-1-0.5 arrangement and the 0.5-1-1 arrangement alternate in the line memory 21a. When comparing the first addresses of each line between the 1-1-0.5 arrangement and the 0.5-1-1 arrangement, they always do not match.

[0031] Consider a situation where discharge noise 39 occurs in the 1-1-0.5 layout, delaying the writing of data in the 0.5-1-1 layout. In this case, the LSU control unit 21 reads out the data stored in the 1-1-0.5 layout in the line memory 21a as data in the 0.5-1-1 layout. As a result, the image is formed at a position shifted along the line direction from its original position, as in the printed image 35 in Figure 4, resulting in image misalignment 37.

[0032] [1.3 Operation of the MFP of the First Embodiment] 5B is a diagram illustrating a line allocation method for a ring buffer according to the present disclosure. In this method, the line data stored in the line memory 21a at one time is limited to data corresponding to N lines (N is a natural number). In FIG. 5B, unused areas of a predetermined size are added to the areas used by the actual image data of the first and second lines, so that an area of ​​0x2000 bytes is allocated per line.

[0033] 5B, no matter which line is stored in the ring buffer, the first data of a certain line is always stored at address 0x0000 of the line memory 21a. Similarly, the first data of a certain line is always stored at address 0x2000 of the line memory 21a. Therefore, even if discharge noise 39 occurs, causing a delay in writing to the line memory 21a and resulting in overlapping images of the same line, the image is formed with the correct positional relationship along the line direction.

[0034] FIG. 6 is a flowchart for explaining an operation for setting the offset size of the ring buffer in the MFP 1 according to the first embodiment of the present disclosure. The control unit 21 receives a paper size setting via the operation unit 9 (step S1). The paper size is the length of the paper along the line direction, and is, for example, 210 mm. Next, the control unit 21 receives a resolution setting via the operation unit 9 (step S3). The resolution is a print resolution, and is, for example, 600 dpi. Next, the control unit 21 receives a gradation setting via the operation unit 9 (step S5). The gradation is a numerical value indicating the degree of shading of color or brightness, and is, for example, 4 bits. Next, the control unit 21 calculates the size of one line of image data based on the paper size, resolution, and gradation set in steps S1 to S5 (step S7). If the paper size is L, the resolution is R, the gradation is G, and the size of one line of image data is S, then S=LRG. In the above example, the size of one line of image data is 210 mm / 25.4 inches × 600 dpi × 4 bits = 19844 bits (0x9b1 bytes). Next, the control unit 21 calculates the buffer division number (step S9). Letting the ring buffer size be B, the value V = B / S is calculated. For example, when the ring buffer size (fixed) is 0x4000 bytes and the size of one line of image data is S = 0x9b1 bytes, V = 0x4000 bytes / 0x9b1 bytes = 6.6. The buffer division number n is a value that is equal to or less than V and that is divisible by the ring buffer size, and is 2 in this case. Next, the control unit 21 divides the ring buffer size by the buffer division number to calculate the ring buffer offset size (step S11). For example, when the ring buffer size (fixed) of 0x4000 bytes is divided by the buffer division number of 2, the ring buffer offset size is 0x2000 bytes.

[0035] In the above explanation, A4 size paper is used. If the paper size is changed to A3 size, the image data size per line will double, but by selecting a size that can store both A4 and A3 paper as the offset size of the ring buffer, it is possible to change the paper size without changing the offset size of the ring buffer.

[0036] [1.4 Changes in ring buffer line allocation] [1.4.1 Trends in conventional MFPs] Figure 7 is a diagram for comparing and contrasting the transition of line allocation in the ring buffer when the ring buffer is operating normally and when a delay occurs in writing to the ring buffer in a conventional MFP. Figure 7 shows the transition of an image data buffer for 10 lines. Figure 7(A) shows the transition when the MFP is operating normally. Figure 7(B) shows an example of the transition when a delay occurs in writing.

[0037] At each write timing to the line memory 21a, the image data of a predetermined number of lines currently stored in the line memory 21a is updated (line increment) to image data of the next predetermined number of lines. When printing starts, image data of a predetermined number of lines is read from the line memory 21a at each read timing. If the writing to the line memory 21a is delayed due to the occurrence of discharge noise, the reading is executed before the writing of the line data is completed. As a result, misalignment occurs in the printed image.

[0038] In the figure, reference symbols consisting of an L and a number, such as L1 and L2, indicate the line number, while reference symbols with an "a" at the end, such as L3a, indicate the first half of the line, and reference symbols with a "b" at the end, such as L3b, indicate the second half of the line. Reference symbols A1 to A6 indicate areas within the line memory 21a. A1, A2, and A3 are areas in a 1-1-0.5 arrangement. A1 and A2 are areas for one line, and A3 is an area for 0.5 lines. A4, A5, and A6 are areas in a 0.5-1-1 arrangement. A4 is an area for 0.5 lines, and A5 and A6 are areas for one line. Reference symbols T1 to T4 indicate the times immediately before reading from the line memory 21a. Times T1 to T4 are the times immediately before four consecutive read operations.

[0039] When the conventional MFP is operating normally, as shown in FIG. 7A, the LSU control unit 21 stores line data in the line memory 21a alternately using the 1-1-0.5 arrangement and the 0.5-1-1 arrangement.

[0040] 7B, if discharge noise occurs before time T3 when line data L8a is written to area A3, the writing to area A3 may be delayed, and area A3 may remain in the state before writing when it is read. At this time, area A3 maintains line data L5b, which is the data written to the latter half of area A6 at time T2.

[0041] Due to the delay in writing line data L8a, the writing of the data following line data L8a, i.e., line data L8b and L9, is also delayed. Therefore, at time T4, area A4 maintains the state of the first half of area A1 at time T3 and stores line data L6a. The first half of area A5 maintains the state of the second half of area A1 at time T3 and stores line data L6b. The second half of area A5 maintains the state of the first half of area A2 at time T3 and stores line data L7a. The first half of area A6 maintains the state of the second half of area A2 at time T3 and stores line data L7b. The second half of area A6 stores line data L8a because the delayed writing has finished.

[0042] The writing of line data L8a was delayed due to the effects of discharge noise, which resulted in a delay in the writing of subsequent line data, resulting in line data L6 and L7 being read out twice each. Also, since the line data L6 and L7 stored in a 1-1-0.5 arrangement at time T3 were read out as line data stored in a 0.5-1-1 arrangement at time T4, the colored portion of line data L7, for example, is interpreted as being located in the left half of the screen at time T3, but is interpreted as being located in the right half of the screen at time T4.

[0043] Figure 8 compares a print image formed during normal operation of a conventional MFP with a print image formed when a delay occurs in writing to the ring buffer. Figure 8(A) shows a normal print image, and Figure 8(B) shows a print image in which image misalignment occurs due to the write delay. As explained in Figure 7(B), the discharge noise causes a delay in writing line data to line memory 21a, so the ninth and tenth lines of the print image are shifted to the right, as shown in Figure 8(B). As a result, for example, a portion of the image that should be positioned on the left side of the print image is positioned on the right side, which can give a viewer an impression that the print image is significantly different from the original print image.

[0044] [1.4.2 Trends in the MFP of the first embodiment] Figure 9 is a diagram for comparing and contrasting the changes in line allocation in a ring buffer when the ring buffer is operating normally and when a delay in writing to the ring buffer occurs in an MFP according to the first embodiment of the present disclosure, where Figure 9(A) shows the changes when the ring buffer is operating normally and Figure 9(B) shows the changes when a delay in writing occurs.

[0045] As shown in FIG. 9B, assume that discharge noise occurs when line data L8 is written at time T4. In this case, line data L7 is also read out in duplicate. However, according to the first embodiment, the address arrangement of line data in the line memory 21a is always the same. One line data is stored in the area from address 0x0000 to address 0x2000, and the other line data is stored in the area from address 0x2000 to address 0x4000. Therefore, even if line data is read out in duplicate, the position along the line direction is the same, so the visual impact on a viewer of the printed image can be reduced.

[0046] 10 is a schematic diagram showing a printed image in which image misalignment has occurred due to a delay in writing to the ring buffer in the MFP1 according to the first embodiment of the present disclosure. As described above, the same lines are printed in duplicate due to the effects of discharge noise in the MFP1 according to the first embodiment. Furthermore, line data is formed at a position shifted from the line on the original printed image. However, as shown in the figure, printing can be performed without being affected by discharge noise in the line direction (the left-right direction in the figure).

[0047] [1.5 Comparison of print examples between the MFP of the first embodiment and a conventional MFP] FIG. 11 is a diagram for explaining the effect of the MFP according to the first embodiment of the present disclosure. FIG. 11(A) is a sample image that was printed correctly. FIG. 11(B) is an image that reproduces the image misalignment that occurs when there is a delay in writing to the ring buffer in a conventional MFP. FIG. 11(C) is an image that reproduces the suppressed image misalignment that occurs when there is a delay in writing to the ring buffer in the MFP according to the first embodiment of the present disclosure. As can be seen by comparing FIG. 11(A) and FIG. 11(B), the conventional MFP causes significant image misalignment due to discharge noise. In particular, in FIG. 11(B), image misalignment occurs in both the main scanning direction and the sub-scanning direction. In contrast, the MFP1 according to the first embodiment can suppress the effects of discharge noise to a level that is almost unnoticeable, as shown in FIG. 11(C).

[0048] FIG. 12 is a diagram for explaining the effect of the MFP according to the first embodiment of the present disclosure. FIG. 12(A) is a partial enlarged view of region 51 in FIG. 11(C), which reproduces the suppressed image misalignment when there is a delay in writing to the ring buffer in the MFP according to the first embodiment of the present disclosure. FIG. 12(B) is a partial enlarged view of the region corresponding to region 51 in a properly printed sample image. Two straight lines are drawn in region 51. Image misalignment occurs near points 53 and 55, which are approximately in the center of these lines in the figure, due to the influence of the write delay. However, the image misalignment is limited to the sub-scanning direction (the up-down direction in the figure), and no image misalignment occurs in the main scanning direction (the left-right direction in the figure).

[0049] [2. Second Embodiment] A second embodiment will now be described. In the first embodiment, an image is formed on a medium of one paper size. In contrast, in the second embodiment, an original containing a mixture of originals of multiple different paper sizes (hereinafter referred to as a mixed original) is printed. The following description will focus on only the differences in configuration and processing from the first embodiment.

[0050] 13 is a flowchart for explaining the operation of setting the offset size of the ring buffer in the MFP according to the second embodiment of the present disclosure. Compared to the flowchart in FIG. 6, step S1 is replaced with step S21. In step S21, the control unit 21 accepts, via the operation unit 9, the setting of the largest paper size among the document sizes included in the mixed document. For example, when printing a mixed document that includes A3 (420 mm wide) documents and A4 (210 mm wide) documents, the paper size is set to A3 (420 mm wide).

[0051] In step S7, when the maximum paper size L=420 mm, the resolution R=1200 dpi, and the gradation G=4 bit, the control unit 21 calculates the size of one line of image data S=LRG=420 mm / 25.4 inches×1200 dpi×4 bit=79372 bits (0x26c2 bytes). In step S9, when the ring buffer size B=0x4000 bytes, the control unit 21 calculates V=B / S=0x4000 bytes / 0x26c2 bytes=3.3. The buffer division number n is a value that is equal to or less than V=3.3 and that is divisible by the ring buffer size, and is 2 in this case. Next, in step S11, the control unit 21 divides the ring buffer size B=0x4000 bytes by the buffer division number n=2 to calculate the ring buffer offset size 0x2000 bytes.

[0052] In this way, in the case of mixed originals, by setting the offset size of the ring buffer in line units at the maximum paper size, even when different paper sizes are mixed, the influence of discharge noise can be suppressed in the same way as in the first embodiment without changing the offset size. Printing can continue.

[0053] 3. Third Embodiment A third embodiment will now be described. In the first embodiment, the impact of discharge noise on a printed image can be suppressed. However, because the impact can be suppressed, it is difficult for a user to notice overlapping of the same lines even when viewing a printed image in which the same lines are printed overlapping due to discharge noise. In the third embodiment, when overlapping lines are printed, the user is notified of this. The following description will focus on only the differences in configuration and processing from the first embodiment.

[0054] FIG. 14 is a functional block diagram of an MFP 51 according to a third embodiment of the present disclosure. FIG. 15 is a schematic conceptual diagram illustrating a process for generating print data from image data of an original image in the MFP 51 according to the third embodiment of the present disclosure. The MFP 51 differs from the MFP 1 in that it includes a memory controller 21b. The memory controller 21b is configured with one or more control circuits that control the writing and reading of image data to the line memory 21a. When writing image data (VIDEO data) input from the image processing unit 19 to the line memory 21a, the memory controller 21b detects a failure in writing to the line memory 21a by polling the write completion register of the line memory 21a. Upon detecting the write failure, the memory controller 21b notifies the image processing unit 19 of the write failure detection. Upon receiving this write failure detection, the image processing unit 19 uses the display unit 7 to display a message for the user. This message notifies the user that a write failure occurred in the line memory 21a. In addition to this message, or instead of this message, a message may be displayed on the display unit 7 to notify the user that the same line is printed twice in the print image.

[0055] According to the MFP 51 of the third embodiment, when discharge noise occurs and writing to the line memory 21a fails, a message to notify the user of this is displayed on the display unit 7. Therefore, even if the effect on the printed image is difficult to visually recognize, the user can recognize that the printed image contains overlapping prints of the same line.

[0056] [4. Modifications] The present disclosure is not limited to the above-described embodiments and variations, and various modifications are possible. In other words, embodiments obtained by combining appropriately modified technical means within the scope of the gist of the present disclosure are also included in the technical scope of the present disclosure.

[0057] The technique of the present disclosure is applicable to MFPs, printers, etc. that include an electrophotographic image forming unit. The light source of the image forming unit is arbitrary and may be a laser, an LED (Light Emitting Diode), or an OLED (Organic Light Emitting Diode).

[0058] The programs that run on each device in the embodiments are programs that control the CPU, etc. (programs that make a computer function) so as to realize the functions of the above-described embodiments. Information handled by these devices is temporarily stored in a temporary storage device (e.g., RAM) during processing, and then stored in various storage devices such as ROMs (Read Only Memories) and HDDs, and is read, modified, and written by the CPU as needed.

[0059] Here, the recording medium for storing the program may be any of semiconductor media (e.g., ROM, non-volatile memory card, etc.), optical recording media / magneto-optical recording media (e.g., DVD (Digital Versatile Disc), MO (Magneto Optical Disc), MD (Mini Disc), CD (Compact Disc), BD (Blu-ray (registered trademark) Disc), etc.), magnetic recording media (e.g., magnetic tape, flexible disk, etc.), etc. Furthermore, not only are the functions of the above-described embodiments realized by executing the loaded program, but the functions of the present disclosure may also be realized by processing in cooperation with an operating system or other application programs, etc., based on instructions from the program.

[0060] Furthermore, when distributing the program on the market, the program can be stored in a portable recording medium and distributed, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present disclosure. [Explanation of symbols]

[0061] 1, 51 Image forming device 3. Control Unit 5 Storage section 7 Display section 9 Control section 11 Image input unit 13 Image forming unit 15 Communications Department 17 Connection 19 Image processing section 21 LSU (Laser Scanning Unit) control section 21a Line Memory 21a1 1st area 21a2 2nd area 21a3 Third area 21b memory controller 23 LSU (Laser Scanning Unit) 31 Original image 33, 35 Printed images 37 Picture shift 39 Discharge noise 51 areas 53, 55 locations 101 Image forming system

Claims

1. An image forming unit and a line memory that forms a ring buffer, the line memory stores image data corresponding to a natural number of lines in a main scanning direction that constitute a part of a print image; the image forming unit forms a print image corresponding to the natural number of lines on a medium based on the image data stored in the line memory; Image forming device.

2. further comprising one or more control units that calculate a number of divisions into which the line memory is divided based on a unit data amount, which is a data amount corresponding to one line in the main scanning direction, and a capacity of the line memory; The natural number multiple of the image data corresponds to the number of divisions. The image forming apparatus according to claim 1 .

3. The image forming apparatus according to claim 2 , wherein the one or more control units calculate the unit data amount based on settings related to image formation by the image forming units.

4. The image forming apparatus according to claim 3 , wherein the settings relating to image formation include a paper size setting, a resolution setting, and a gradation setting.

5. When the first medium has a first size and the second medium has a second size that is larger than the first size, the one or more control units calculate a second unit data amount based on the second size; the image forming unit forms a print image corresponding to one line on both the first and second media based on the image data of the second unit data amount; The image forming apparatus according to claim 4 .

6. The image forming apparatus according to claim 1 , further comprising one or more memory controllers that detect a failure in writing to the line memory.

7. The image forming apparatus according to claim 6 , further comprising a display unit that displays a message notifying the user of the failure in writing in response to the detection of the failure in writing.

8. 1. A control method for an image forming apparatus having a line memory that configures a ring buffer, comprising: the line memory stores image data corresponding to a natural number of lines in a main scanning direction that constitute a part of a print image; forming a print image corresponding to the natural number of lines on a medium based on the image data stored in the line memory; A control method for an image forming apparatus.

Images