JP2015174345A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image of high resolution fast while suppressing the capacity of a buffer.SOLUTION: An image output section 50 reads pixel data on a pixel array in a first direction X of image data to be recorded out of a RAM 48, and outputs pixel group data to be recorded by respective nozzle arrays to a recording section 14 at each timing delayed corresponding to the width between the nozzle arrays so as to obtain a resolution in a second direction of an image. A first execution section 50A executes a first mode in which pixel data from the RAM 48 are read repeatedly as many times as the number of the plurality of nozzle arrays and output to the recording section 14. A second execution section executes a second mode in which pixel data from the RAM 48 are read and stored in a buffer 57, and then output to the recording section 14. A control section 50C controls the first execution section 50A and second execution section 50B so as to execute the first mode or second mode according to the resolution in the second direction of the image to be recorded.

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art An ink jet recording apparatus that forms an image by ejecting liquid droplets such as ink from nozzles is known. In addition, a configuration is also known in which two nozzle rows in which a plurality of nozzles are arranged in the first direction are arranged in a second direction intersecting the first direction, and the nozzles are arranged in a staggered manner.

  In this case, since there is a gap between nozzle rows adjacent in the second direction, dots recorded by droplet discharge at the same timing use data of pixel rows that differ between the nozzle rows. For this reason, conventionally, it has been necessary to read image data twice from the storage unit and thin out unused pixels.

  However, the method of reading image data from the storage unit a plurality of times has a problem that the image forming speed decreases as the number of accesses to the storage unit increases. In particular, in the case of an image forming apparatus using a known line head, the image forming speed may be lowered even though high-speed printing is required.

  On the other hand, instead of reading the image data twice from the storage unit, the image data to be recorded by the other nozzle row until the droplets are ejected from the other nozzle row by delaying the ejection of the droplets from the one nozzle row. It is also conceivable to store in a buffer. However, there is a problem that the buffer capacity increases as the resolution increases.

  For this reason, conventionally, it has been difficult to form an image with high resolution at high speed while suppressing the capacity of the buffer.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image forming apparatus capable of forming an image with high resolution at high speed while suppressing the capacity of the buffer.

  In order to solve the above-described problems and achieve the object, the present invention is directed to a nozzle row in which a plurality of nozzles that discharge droplets are arranged in a first direction, in a second direction that intersects the first direction. A plurality of recording units arranged; a drive unit that moves the recording medium relative to the recording unit in the second direction; a storage unit that stores image data of an image to be recorded; and the first direction in the image data The pixel data of the pixel row along the line is read from the storage unit, and each of the pixel group data recorded by each of the nozzle rows included in the pixel data is realized in the resolution in the second direction of the image. An image output unit for outputting to the recording unit at each timing delayed according to the width between the nozzle rows, the image output unit including a buffer for storing the pixel group data, and the storage From the pixel A first mode in which the pixel group data to be recorded at each of the nozzle rows included in the pixel data is output to the recording unit at each timing. A first execution unit that reads the pixel data from the storage unit, and records the pixel group data to be recorded by at least the nozzle row arranged in the uppermost stream in the second direction among the plurality of nozzle rows. A second mode of executing the second mode in which the pixel group data to be recorded by the nozzle row arranged downstream in the second direction from the nozzle row is stored in the buffer and then output to the recording portion. 2 execution units and a control unit that controls the first execution unit and the second execution unit so as to execute the first mode or the second mode according to the resolution. It is formed apparatus.

  According to the present invention, it is possible to form an image with high resolution at a high speed while suppressing the capacity of the buffer.

FIG. 1 is a diagram illustrating an example of an image forming apparatus. FIG. 2 is an enlarged schematic diagram of the recording unit. FIG. 3 is a schematic diagram of image data to be recorded. FIG. 4 is a timing chart showing an example of data output timing to the recording unit. FIG. 5 is a configuration diagram of the image forming apparatus according to the present embodiment. FIG. 6 is a block diagram illustrating a functional configuration of the image output unit. FIG. 7 is a flowchart illustrating a procedure of processing executed by the image output unit. FIG. 8 is an explanatory diagram of a specific example of the present embodiment. FIG. 9 is a configuration diagram of the image forming apparatus of the present embodiment. FIG. 10 is a block diagram illustrating a functional configuration of the image output unit. FIG. 11 is an explanatory diagram of a specific example of the present embodiment. FIG. 12 is a table showing examples and comparative examples.

  Exemplary embodiments of an image forming apparatus will be described below in detail with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a diagram illustrating an example of the image forming apparatus 10.

  The image forming apparatus 10 includes a controller board 12, a drive unit 16, and a recording unit 14. The controller board 12 controls the entire image forming apparatus 10.

  The recording unit 14 is an ink jet recording head that discharges droplets for recording dots corresponding to pixels. The droplet is, for example, ink.

  FIG. 2 is an enlarged schematic diagram of the recording unit 14. FIG. 2A is a plan view showing the surface of the recording unit 14 where the nozzles 18 are provided. FIG. 2B is an enlarged schematic view of a part of FIG.

  The recording unit 14 has a configuration in which a plurality of nozzle rows 20 in which a plurality of nozzles 18 are arranged along the first direction X are arranged at intervals in the second direction Y (in FIG. 2, the nozzle row 20A and the nozzle row 20B). reference). The first direction X and the second direction Y only need to cross each other. In the present embodiment, the first direction X and the second direction Y are orthogonal directions. Further, in the present embodiment, the case where the recording unit 14 has a configuration in which the nozzle rows 20 are arranged in two rows in the second direction Y will be described. Therefore, in the present embodiment, the recording unit 14 has a configuration in which the nozzle row 20A is arranged on the upstream side in the second direction Y, and the nozzle row 20B is arranged on the downstream side in the second direction Y with an interval W therebetween. Will be explained.

  As shown in FIG. 2, the plurality of nozzles 18 provided in the recording unit 14 are arranged in a staggered manner. FIG. 3 is a schematic diagram of the image data 21 of the image to be recorded. The controller board 12 includes, in the image data 21, the pixel data 30 of the pixel array along the first direction X, the pixel group data of the pixel group 30A recorded by the nozzle array 20A, and the pixel group 30B recorded by the nozzle array 20B. Separated or extracted from pixel group data. Each pixel group data is output to the recording unit 14 as pixel group data recorded by the corresponding nozzle row 20 (nozzle row 20A, nozzle row 20B).

Returning to FIG. 1, in the present embodiment, the image forming apparatus 10 has a plurality of recording units 14 (in FIG. 1, recording units 14 ₁ to 14 ₈ ) arranged in a staggered manner along the first direction X. It is a configuration. When the recording units 14 are arranged in a staggered manner, the formation of streaks or the like in the image due to the gaps between the adjacent recording units 14 is suppressed. The drive unit 16 moves the recording medium P relative to the recording unit 14 in the second direction Y.

  The image forming apparatus 10 includes a single recording unit 14 that is long in the first direction X and longer than the length in the first direction X of the recording medium P that can be recorded by the image forming apparatus 10. There may be.

  In this embodiment, a case where the recording units 14 are arranged in two rows in the second direction Y will be described. However, the recording units 14 in three or more rows are arranged in the second direction Y. Also good. Further, the number of the recording units 14 arranged in the first direction X is not limited to the number shown in FIG.

  On the recording medium P, ink is ejected as droplets from each of the nozzles 18 (not shown in FIG. 1) provided in the recording unit 14. The recording medium P is conveyed relative to the recording unit 14 in the second direction Y by the driving unit 16. Note that the position of the recording medium P in the second direction Y is obtained by a sensor such as an encoder (not shown). Due to the ejection of the ink and the relative movement of the recording medium P, dots corresponding to the pixels of the image to be recorded are formed on the recording medium P. As a result, an image is formed on the recording medium P.

  Here, as described with reference to FIG. 2, the nozzles 18 are arranged in a staggered manner in the recording unit 14. In the example illustrated in FIG. 2, each of the nozzle array 20 </ b> A and the nozzle array 20 </ b> B in the recording unit 14 can record dots in the first direction X with a resolution of 300 dpi. Since the nozzles 18 in the nozzle row 20A and the nozzle row 20B are arranged in a staggered manner, in the example shown in FIG. 2, the recording unit 14 is configured to record an image of 600 dpi in the first direction X. .

  The resolution in the second direction Y that can be recorded by the image forming apparatus 10 is adjusted by the ejection timing of ink from each nozzle array 20 provided in the recording unit 14. Here, as shown in FIG. 2, there is a gap between the nozzle rows 20 adjacent in the second direction Y. The gap (hereinafter referred to as the width) between the nozzle rows 20 varies depending on the configuration of the recording unit 14. In the example shown in FIG. 2, for example, the width W is 2.54 mm.

  Therefore, in order to realize the resolution in the second direction Y of the image to be recorded, each of the pixel group data for each nozzle row 20 extracted or separated from the pixel data of the same pixel row is the target second. In order to realize the resolution in the direction, it is necessary to output to the recording unit 14 at every timing delayed according to the width between the nozzle rows 20.

  FIG. 4 is a timing chart showing an example of data output timing to the recording unit 14.

  It is assumed that the width between the nozzle rows 20A and 20B is 2.54 mm. Assume that the resolution of the image to be recorded in the second direction Y is 600 dpi. In this case, the width between the nozzle arrays 20 of the nozzle array 20A and the nozzle array 20B is 60 of the pixel data of the pixel array for one line along the first direction X in the image data of the 600 dpi image to be recorded. It corresponds to the line.

  In this case, the controller board 12 corresponds to the 60 lines after outputting the pixel group data to be recorded by the nozzle row 20A to the recording unit 14 (see “A-row output data” in FIG. 4A). At the timing delayed, the pixel group data to be recorded by the nozzle row 20B is output to the recording unit 14 (see “B row output data” in FIG. 4A).

  By receiving pixel group data at these timings, the recording unit 14 applies a voltage to the pressure chambers that communicate with the nozzles 18 of the nozzle rows 20 using a known mechanism such as a piezoelectric element. Thereby, ink corresponding to the pixel group data is ejected from each nozzle row 20 (nozzle row 20A, nozzle row 20B) at intervals corresponding to the above timing, and dots are formed. As a result, an image having a resolution of 600 dpi in the second direction Y is formed.

  On the other hand, it is assumed that the resolution in the second direction Y of the image to be recorded is 1200 dpi. In this case, the width between the nozzle arrays 20 of the nozzle array 20A and the nozzle array 20B is 120 lines of the pixel data of the pixel array for one line along the first direction X in the image data of the image to be recorded. It corresponds to.

  In this case, the controller board 12 corresponds to the 120 lines after outputting the pixel group data to be recorded by the nozzle row 20A to the recording unit 14 (see “A row output data” in FIG. 4B). At the timing delayed, the pixel group data to be recorded by the nozzle row 20B is output to the recording unit 14 (see “B row output data” in FIG. 4B).

  By receiving pixel group data at these timings, the recording unit 14 applies a voltage to the pressure chambers that communicate with the nozzles 18 of the nozzle rows 20 using a known mechanism such as a piezoelectric element. Thereby, ink corresponding to the pixel group data is ejected from each nozzle row 20 (nozzle row 20A, nozzle row 20B) at intervals corresponding to the above timing, and dots are formed. As a result, an image having a resolution of 1200 dpi in the second direction Y is formed.

  FIG. 5 is a configuration diagram of the image forming apparatus 10 of the present embodiment.

  The image forming apparatus 10 includes a PSU (Power Supply Unit) 32, a PC (Personal Computer) 33, an operation unit 34, a sensor 36, a drive unit 16, a recording unit 14, and a controller board 12. The PSU 32, the PC 33, the operation unit 34, the sensor 36, the drive unit 16, and the recording unit 14 are electrically connected to the controller board 12.

  The PSU 32 is a power supply device that is supplied with power from the power plug 31 and supplies power to the controller board 12 and each unit connected to the controller board 12.

  The PC 33 is an external device. In the present embodiment, the PC 33 is connected to the controller board 12 via, for example, a network (not shown). The PC 33 transmits image data of an image to be recorded by the image forming apparatus 10 to the controller board 12.

  The operation unit 34 receives various instructions from the user. The operation unit 34 is a keyboard, a touch panel, or the like. The scanner unit 35 is a functional unit that reads a document and generates image data, and executes a known scanner function. The sensor 36 includes a sensor 36A that detects the position of the recording unit 14 in the second direction Y of the recording medium P, and a sensor 36B that performs various types of detection.

  The controller board 12 includes a power supply circuit 40, a host I / F 41, an operation unit I / F 42, a scanner I / F 43, a SoC (System-on-a-chip) 44, a sensor I / F 45, and an engine control. A unit 46, a RAM (Random Access Memory) 48, a ROM (Read Only Memory) 49, and an image output unit 50 are provided. The power supply circuit 40, host I / F 41, operation unit I / F 42, scanner I / F 43, sensor I / F 45, engine control unit 46, RAM 48, ROM 49, and image output unit 50 are electrically connected to the SoC 44. . The SoC 44 includes a CPU.

  The power supply circuit 40 converts the power supplied from the PSU 32 into a DC voltage having a required voltage level on the controller board 12 and supplies the DC voltage to each unit of the image forming apparatus 10.

  The host I / F 41 is an interface that receives image data from an external device such as the PC 33 via USB / Ethernet (registered trademark) or the like.

  The operation unit I / F 42 receives a signal based on a user operation instruction received by the operation unit 34, and controls display of various images on a display unit provided in the operation unit 34. The scanner I / F 43 receives image data generated by the scanner unit 35. The scanner I / F 43 controls various mechanisms provided in the scanner unit 35.

  The sensor I / F 45 includes a plurality of sensor I / Fs 45 (sensor I / F 45A, sensor I / F 45B). The sensor I / F 45 receives the detection signal from each sensor 36 and analyzes the detection result. For example, the sensor I / F 45 analyzes the encoder signal that is the detection result of the recording unit 14 in the second direction Y of the recording medium P, the detection result of the leading end of the recording medium P in the second direction Y, and the like. To analyze.

  The engine control unit 46 controls the drive unit 16 and actuators (not shown) such as motors and clutches provided in the image forming apparatus 10.

  The ROM 49 stores data that needs to be retained even when the power supply to the image forming apparatus 10 is cut off, such as a program for processing executed by the image forming apparatus 10.

  The RAM 48 stores a program execution area and various data. The RAM 48 corresponds to a storage unit. That is, the RAM 48 stores image data to be recorded. The RAM 48 stores image data in a data format in which dots corresponding to pixels can be recorded. For example, the RAM 48 stores bitmap data indicating pixel values for each pixel as image data. In the present embodiment, the RAM 48 is, for example, a DRAM (Dynamic Random Access Memory).

  The image output unit 50 controls the recording unit 14 such that ink for recording dots corresponding to each pixel of the image data is ejected from the nozzles 18 provided in the recording unit 14. That is, the image output unit 50 transmits pixel group data, a drive waveform for driving the recording unit 14, and the like to the recording unit 14 in accordance with the position of the recording medium P with respect to the recording unit 14.

  The image output unit 50 is electrically connected to the SoC 44 and the RAM 48. That is, the image output unit 50 can directly access the RAM 48 without using a CPU (mounted on the SoC 44). For this reason, it is possible to transfer data between the controller board 12 and the recording unit 14 at high speed.

  The image output unit 50 reads, from the RAM 48 (storage unit), pixel data of a pixel column along the first direction X in the image data to be recorded. And according to the width | variety between the nozzle rows 20 so that each pixel group data recorded with each of the nozzle rows 20 included in the pixel data may realize the resolution in the second direction Y of the image to be recorded. Output to the recording unit 14 at each delayed timing.

  The image output unit 50 includes a first execution unit 50A, a second execution unit 50B, a control unit 50C, and a buffer 57.

  The buffer 57 is a buffer for adjusting the output timing of the pixel group data. The buffer 57 corresponds to a buffer. The buffer 57 is, for example, an SRAM (Static Random Access Memory).

  The buffer 57 is provided corresponding to each of the nozzle rows 20 other than the nozzle row 20 arranged in the uppermost stream in the second direction Y among the plurality of nozzle rows 20 included in the recording unit 14. In other words, the buffer 57 is a nozzle row arranged downstream of the nozzle row 20A arranged in the uppermost stream in the second direction Y among the plurality of nozzle rows 20 provided in the recording unit 14. 20B is provided. In other words, the image output unit 50 includes the number of buffers 57 obtained by subtracting “1” from the number of rows of the plurality of nozzle rows 20 included in the recording unit 14.

  In the present embodiment, the recording unit 14 includes two nozzle rows 20 including a nozzle row 20A and a nozzle row 20B. Therefore, the image output unit 50 includes one buffer 57 for each recording unit 14.

  The capacity of the buffer 57 may be a data amount that can realize the delay of the ink ejection timing corresponding to the width between the nozzle rows 20 in order to realize the target resolution in the second direction Y.

  Specifically, the capacity of the buffer 57 can hold pixel group data of an image having a resolution lower than the maximum resolution in the second direction Y that can be recorded by the image forming apparatus 10 and a data amount corresponding to the width between the nozzle rows 20. Capacity.

  The capacity of the buffer 57 is a capacity capable of holding pixel group data of an image having a resolution equal to or higher than the minimum resolution in the second direction Y that can be recorded by the image forming apparatus 10 in accordance with the width of the nozzle rows 20. is there.

  Specifically, when the resolution in the second direction Y of the image to be recorded is the lowest resolution that can be recorded by the image forming apparatus 10, the capacity of the buffer 57 is upstream in the second direction Y. The timing from the output of the pixel group data of the resolution to the nozzle row 20A arranged on the side to the output of the pixel group data of the resolution to the downstream nozzle row 20B corresponds to the width between the nozzle rows 20 It is sufficient if the capacity is sufficient to delay the time.

  When the resolution in the second direction Y of the image to be recorded is the maximum resolution that can be recorded by the image forming apparatus 10, the capacity of the buffer 57 is arranged on the upstream side in the second direction Y. In order to delay the timing from when the pixel group data of the resolution is output to the nozzle row 20A to when the resolution pixel group data is output to the downstream nozzle row 20B, corresponding to the width between the nozzle rows 20 Less than enough capacity.

  In the present embodiment, a case where the recording unit 14 is provided with two nozzle rows 20 (nozzle row 20A and nozzle row 20B) in the second direction Y will be described. However, the recording unit 14 may have a configuration in which three or more nozzle rows 20 are arranged in the second direction Y. In this case, the buffer 57 may be provided in correspondence with each of the nozzle rows 20 other than the nozzle row 20 arranged in the uppermost stream in the second direction Y among the plurality of nozzle rows 20 of three or more rows. In this case, it is preferable to adjust the capacity of each buffer 57 so that the capacity of the buffer 57 corresponding to the nozzle row 20 located on the downstream side in the second direction Y satisfies the above condition and becomes larger.

  The first execution unit 50A repeatedly reads the pixel data of the pixel columns along the first direction X in the image data to be recorded from the RAM 48 a number of times according to the nozzle rows 20 provided in the recording unit 14, and the pixel data In the first mode, the pixel group data to be recorded by each of the nozzle rows 20 included in is output to the recording unit 14 at each timing.

  Specifically, the first execution unit 50 </ b> A reads pixel data of a pixel row along the first direction X in the image data to be recorded from the RAM 48.

  Then, the first execution unit 50A uses the nozzle row 20 (nozzle row 20A in FIG. 2) arranged in the uppermost stream in the second direction Y among the plurality of nozzle rows 20 of the recording unit 14 in the read pixel data. The pixel group data of the pixel group to be recorded is output to the recording unit 14 as pixel group data to be recorded by the nozzle row 20A. Further, the first execution unit 50A stores, in the buffer 57, pixel group data of the pixel group to be recorded by the nozzle row 20B arranged downstream of the nozzle row 20A in the second direction Y in the read pixel data. Then, after the timing delay, the pixel group data stored in the buffer 57 is output to the recording unit 14.

  The second execution unit 50B reads the pixel data of the pixel row in the image data to be recorded from the RAM 48, and records it with the nozzle row 20A arranged at least in the uppermost stream in the second direction Y among the plurality of nozzle rows 20. The pixel group data to be output is output to the recording unit 14. The second execution unit 50B stores the pixel group data to be recorded by the nozzle row 20B arranged downstream of the nozzle row 20A in the second direction Y in the buffer 57 and then outputs the pixel group data to the recording unit 14. Run the mode.

  That is, the first execution unit 50 </ b> A uses the buffer 57 when outputting data to the recording unit 14. On the other hand, the second execution unit 50B does not use the buffer 57 when data is output to the recording unit 14, but the pixel data of the same pixel column included in the image data is replaced with the number of nozzle rows 20 included in the recording unit 14, Read multiple times from RAM 48.

  The control unit 50C controls the first execution unit 50A and the second execution unit 50B to execute one of the first mode and the second mode according to the resolution in the second direction Y of the image to be recorded. To do.

  Specifically, the control unit 50C controls the first execution unit 50A to execute the first mode when the resolution in the second direction Y of the image to be recorded is equal to or less than a threshold value. On the other hand, when the resolution in the second direction Y of the image to be recorded exceeds the threshold value, the control unit 50C controls the second execution unit 50B to execute the second mode.

  The threshold value is determined according to the capacity of the buffer 57 provided in the image output unit 50, the width between the nozzle rows 20, and the resolution in the second direction Y of the image that can be recorded by the image forming apparatus 10. The threshold value is a value equal to or less than the capacity of the buffer 57 necessary for realizing the recording of the target resolution in the second direction Y by causing the delay of the ink ejection timing corresponding to the width of the nozzle row 20.

  Specifically, the threshold value can be stored when pixel group data having a data amount capable of realizing a delay in ink ejection timing corresponding to the width between the nozzle rows 20 is stored in the buffer 57. Define the maximum resolution. This maximum resolution is a value less than the maximum value among the resolutions in the second direction Y of the image that can be recorded by the image forming apparatus 10.

  Here, as described above, the capacity of the buffer 57 is the pixel group data of an image having a resolution less than the maximum resolution in the second direction Y that can be recorded by the image forming apparatus 10 and data corresponding to the width between the nozzle rows 20. It is a capacity that can hold the amount. The capacity of the buffer 57 is a capacity capable of holding pixel group data of an image having a resolution equal to or higher than the minimum resolution in the second direction Y that can be recorded by the image forming apparatus 10 in accordance with the width of the nozzle rows 20. is there.

  For this reason, the threshold value is a value that is less than the maximum resolution that can be recorded by the image forming apparatus 10, a value that exceeds the minimum resolution that can be recorded by the image forming apparatus 10, and a value that satisfies the above conditions. .

  That is, the threshold value is a value that exceeds the minimum resolution in the second direction Y of the image that can be recorded by the image forming apparatus 10 and less than the maximum resolution, and includes the capacity of the buffer 57 and the width between the nozzle rows 20. Accordingly, a resolution that serves as a boundary of whether or not the function as a buffer for adjusting the output timing of the pixel group data for each nozzle row 20 to the recording unit 14 according to the delay can be determined. .

  FIG. 6 is a block diagram illustrating a functional configuration of the image output unit 50.

  The image output unit 50 includes a reception unit 50D, a control unit 50C, a reading unit 53, a separation unit 56, a buffer 57, an extraction unit 58, and an output unit 59.

  The receiving unit 50D receives the resolution in the second direction Y of the image to be recorded. The receiving unit 50D may receive the resolution of the image to be output from the operation unit 34. Further, when the SoC 44 stores the image data in the RAM 48, the resolution in the second direction Y in the image data may be output to the image output unit 50. Then, the receiving unit 50D may receive the resolution in the second direction Y of the image to be recorded from the SoC 44.

  The reading unit 53 controls access to the RAM 48. The reading unit 53 designates an area of image data stored in the RAM 48 and reads a predetermined area (pixel data of a pixel column) in the image data from the RAM 48. Specifically, the operation unit I / F 42 designates a predetermined area of the image data stored in the RAM 48 and issues a read request. This predetermined area is an area of a pixel column for which no read request has been issued in the image data.

  The reading unit 53 includes a first reading unit 54 and a second reading unit 55. The first reading unit 54 designates an area of image data stored in the RAM 48 and reads pixel data of a pixel row corresponding to a predetermined area in the image data from the RAM 48.

  The second reading unit 55 includes a third reading unit 55A and a fourth reading unit 55B. The third reading unit 55A reads a pixel row in a predetermined area in the image data as pixel data for the nozzle row 20A. The fourth reading unit 55B reads the pixel row in the predetermined area in the image data as pixel data for the nozzle row 20B. That is, the second reading unit 55 reads the same predetermined area of the image data by both the third reading unit 55A and the fourth reading unit 55B. That is, the second reading unit 55 reads the same pixel data twice. It becomes.

  In the present embodiment, the case where the recording unit 14 is configured to include two nozzle rows 20 in the second direction Y is described. Therefore, the second reading unit 55 includes two reading units (a third reading unit 55A and a fourth reading unit 55B), and reads the same pixel data twice. However, the recording unit 14 may include three or more nozzle rows 20 in the second direction Y. In this case, the SoC 44 may read the same pixel data for the number of times corresponding to the number of nozzle rows 20 arranged in the second direction Y.

  The output unit 59 outputs the pixel group data to the recording unit 14. The output unit 59 outputs the pixel group data to the recording unit 14 in synchronism with the rearrangement of data into the sequence requested by the recording unit 14 and the detection result by the sensor 36A that detects the position in the second direction Y.

  The output unit 59 includes an output unit (that is, a channel) corresponding to each nozzle row 20 provided in the recording unit 14. In the present embodiment, the output unit 59 outputs the pixel group data recorded by the nozzle row 20A to the recording unit 14 and the pixel group data recorded by the nozzle row 20B to the recording unit 14. Second output unit 59B. Among these output units 59A and second output units 59B, a buffer 57 is assigned in advance to the second output unit 59B that outputs pixel group data to the nozzle row 20B on the downstream side in the second direction Y.

  The separation unit 56 separates the pixel data read by the first reading unit 54 into pixel group data recorded by the nozzle row 20A and pixel group data recorded by the nozzle row 20B. Then, the separation unit 56 outputs the pixel group data for the nozzle row 20A, which is the upstream nozzle row 20 in the second direction Y, to the first output unit 59A. The first output unit 59A outputs the received pixel group data to the recording unit 14 as pixel group data to be recorded by the nozzle row 20A.

  On the other hand, the separation unit 56 stores pixel group data for the nozzle row 20B, which is the nozzle row 20 on the downstream side in the second direction Y, in the buffer 57. As described above, the buffer 57 is allocated to the second output unit 59B. When the pixel group data is sequentially stored in the buffer 57 and the pixel group data corresponding to the delay is stored, the second output unit 59B sequentially reads from the buffer 57 the pixel group data stored first. The pixel group data to be recorded by the nozzle row 20B is output to the recording unit 14. For this reason, the buffer 57 has a function of delaying the output timing of the pixel group data to the recording unit 14.

  The extraction unit 58 includes a third extraction unit 58A and a fourth extraction unit 58B. The third extraction unit 58A extracts pixel group data to be recorded by the nozzle row 20A from the pixel data read by the third reading unit 55A. Then, the extracted data is output to the recording unit 14 via the first output unit 59A. The fourth extraction unit 58B extracts pixel group data recorded by the nozzle row 20B from the pixel data read by the fourth reading unit 55B. Then, the extracted pixel group data is output to the recording unit 14 via the second output unit 59B.

  The first reading unit 54, the separation unit 56, the buffer 57, and the output unit 59 correspond to the first execution unit 50A. Further, the second reading unit 55 (third reading unit 55A, fourth reading unit 55B), the extraction unit 58 (third extraction unit 58A, fourth extraction unit 58B), and the output unit 59 (first output unit 59A, first output). 2 output unit 59B) corresponds to the second execution unit 50B.

  Next, a procedure of processing executed by the image output unit 50 will be described. FIG. 7 is a flowchart illustrating a procedure of processing executed by the image output unit 50.

  First, the receiving unit 50D receives the resolution in the second direction Y of the image to be recorded (step S100). Next, the control unit 50C determines whether or not the resolution in the second direction Y of the image to be recorded is equal to or less than a threshold value (step S102).

  When the resolution in the second direction Y is equal to or less than the threshold (step S102: Yes), the process proceeds to step S104. In step S104, the control unit 50C controls the first execution unit 50A to execute the first mode (step S104), and this routine is finished.

  On the other hand, when the resolution in the second direction Y exceeds the threshold (step S102: No), the process proceeds to step S106. In step S106, the control unit 50C controls the second execution unit 50B to execute the second mode (step S106), and ends this routine.

  Next, a specific example when the above processing is executed will be described. FIG. 8 is an explanatory diagram of a specific example of the present embodiment.

  FIG. 8 shows a configuration in which the recording unit 14 includes two nozzle rows 20 of the nozzle row 20A and the nozzle row 20B in the second direction Y, and the width between the nozzle rows 20 is 2.54 mm. Assumed (see also FIG. 2). As shown in FIG. 2, the recording unit 14 can record dots in the first direction X with a resolution of 300 dpi in each of the nozzle row 20A and the nozzle row 20B. Since the nozzles 18 of the nozzle array 20A and the nozzle array 20B are arranged in a staggered manner, the recording unit 14 is configured to be able to record an image of 600 dpi in the first direction X.

  In the example shown in FIG. 8, the threshold value is 600 dpi, and the capacity of the buffer 57 is the pixel data of the pixel column for one line along the first direction X in the image data with a resolution of 600 dpi in the second direction Y. A case where the capacity is equivalent to 60 lines will be described.

  8A, when the resolution in the second direction Y of the image to be recorded is 600 dpi, the control unit 50C (see FIG. 6) controls the first execution unit 50A so as to execute the first mode. It is explanatory drawing in the case. That is, FIG. 8A is an explanatory diagram when the resolution in the second direction Y of the image to be recorded is equal to or less than a threshold value.

  In this case, the first reading unit 54 reads pixel data of a pixel column along the first direction X from the image data stored in the RAM 48. The first reading unit 54 reads the pixel data by designating an area of the pixel data in the image data stored in the RAM 48 as the predetermined area and issuing a read request for the predetermined area. That is, the first reading unit 54 collectively reads the pixel data for the nozzle row 20A and the nozzle row 20B by issuing a single read request.

  Next, the separation unit 56 separates the read pixel data into pixel group data recorded by the nozzle row 20A and pixel group data recorded by the nozzle row 20B. Specifically, in the pixel data, odd-numbered pixels are separated as pixels to be recorded by the nozzle row 20A, and even-numbered pixels are separated as pixels to be recorded by the nozzle row 20B. Thereby, the separating unit 56 separates the read pixel data into pixel group data recorded by the nozzle row 20A and pixel group data recorded by the nozzle row 20B.

  In the specific example shown in FIG. 8, the buffer 57 delays the output of the pixel group data recorded by the nozzle row 20B to the recording unit 14 by 60 pixel rows in the second direction Y with respect to the nozzle row 20A. Use for.

  The separation unit 56 outputs the pixel group data recorded by the nozzle row 20A to the first output unit 59A. When receiving the pixel group data, the first output unit 59A outputs the pixel group data to the recording unit 14 as the pixel group data to be recorded by the nozzle row 20A.

  On the other hand, the separation unit 56 outputs the pixel group data recorded by the nozzle row 20 </ b> B to the buffer 57. Therefore, the buffer 57 functions as a buffer for delaying the output timing of the pixel group data to the nozzle row 20B so that a delay of 60 pixel rows in the second direction Y occurs with respect to the nozzle row 20A. To do. The second output unit 59B assigned to the buffer 57 outputs the pixel group data stored in the buffer 57 to the recording unit 14 as pixel group data to be recorded by the nozzle row 20B.

  For this reason, when the resolution of the image to be recorded is equal to or lower than the threshold value, the image output unit 50 executes the first mode using the buffer 57.

  FIG. 8B illustrates a case where the resolution in the second direction Y of the image to be recorded is 1200 dpi, and the control unit 50C (see FIG. 6) controls the second execution unit 50B to execute the second mode. It is explanatory drawing of. That is, FIG. 8B is an explanatory diagram when the resolution in the second direction Y of the image to be recorded exceeds the threshold value.

  In this case, the third reading unit 55A reads pixel data of the pixel row along the first direction X from the image data stored in the RAM 48 as pixel data for the nozzle row 20A. The third reading unit 55A reads the pixel data for the nozzle row 20A by designating the area of the pixel data in the image data stored in the RAM 48 as the predetermined area and issuing a read request for the predetermined area. .

  Next, the third extraction unit 58A extracts pixel group data to be recorded by the nozzle row 20A from the pixel data for the nozzle row 20A read by the third reading unit 55A. Specifically, pixel group data to be recorded by the nozzle row 20A is extracted by extracting odd-numbered pixels in the pixel data as pixels to be recorded by the nozzle row 20A. More specifically, the third extraction unit 58A extracts 300 dpi pixel group data by extracting odd-numbered pixels from 600 dpi pixel data in the first direction X. Then, the third extraction unit 58A outputs this pixel group data to the first output unit 59A.

  When the first output unit 59A receives the pixel group data from the third extraction unit 58A, the first output unit 59A outputs the received pixel group data to the recording unit 14 as pixel group data to be recorded by the nozzle row 20A.

  On the other hand, the third reading unit 55B uses the pixel data of the pixel line 60 lines before the upstream in the second direction Y from the line read immediately before by the third reading unit 55A from the image data stored in the RAM 48. By designating the area as the predetermined area and issuing a read request for the predetermined area, the pixel data for the nozzle row 20B is read.

  Next, the fourth extraction unit 58B extracts pixel group data to be recorded by the nozzle row 20B from the pixel data for the nozzle row 20B read by the fourth reading unit 55B. Specifically, even-numbered pixels in the pixel data are extracted as pixels to be recorded by the nozzle row 20B, thereby extracting pixel group data to be recorded by the nozzle row 20B. More specifically, the fourth extraction unit 58B extracts 300 dpi pixel group data by extracting even-numbered pixels from 600 dpi pixel data in the first direction X. Then, the fourth extraction unit 58B outputs this pixel group data to the second output unit 59B.

  When the second output unit 59B receives the pixel group data from the fourth extraction unit 58B, the second output unit 59B outputs the received pixel group data to the recording unit 14 as pixel group data to be recorded by the nozzle row 20B.

  For this reason, when the resolution of the image to be recorded exceeds the threshold, the image output unit 50 executes the second mode without using the buffer 57.

  As described above, in the image forming apparatus 10 of the present embodiment, the image output unit 50 reads the pixel data of the pixel columns along the first direction X in the image data to be recorded from the RAM 48 as the storage unit, Each pixel group data recorded in each of the nozzle rows 20 included in the pixel data is delayed for each timing according to the width between the nozzle rows 20 so as to realize the resolution in the second direction Y of the image. To the recording unit 14.

  The image output unit 50 includes a buffer 57, a first execution unit 50A, a second execution unit 50B, and a control unit 50C.

  The first execution unit 50A repeatedly reads the pixel data from the RAM 48 according to the number of the plurality of nozzle rows 20, and records the pixel group data recorded in each of the nozzle rows 20 included in the pixel data at each timing. The first mode output to the unit 14 is executed. The second execution unit reads pixel data from the RAM 48 and outputs pixel group data to be recorded by the nozzle row 20 arranged at least in the uppermost stream in the second direction Y to the recording unit 14 among the plurality of nozzle rows 20. A second mode is executed in which pixel group data to be recorded by the nozzle row 20 disposed downstream of the nozzle row 20 in the second direction Y is stored in the buffer 57 and then output to the recording unit 14. The control unit 50C controls the first execution unit 50A and the second execution unit 50B so as to execute the first mode or the second mode according to the resolution in the second direction Y of the image to be recorded.

  As described above, the image forming apparatus 10 according to the present embodiment includes the second mode in which the same pixel column is read from the RAM 48 a plurality of times and output to the recording unit 14 according to the resolution in the second direction Y of the image to be recorded. The first pixel mode can be switched between the first mode in which the RAM 48 is read once and the output timing is delayed using the buffer 57.

  Therefore, an image with a high resolution in the second direction Y can be formed at high speed while suppressing the capacity of the buffer 57.

  The image forming apparatus 10 according to the present embodiment executes the first mode when the resolution in the second direction Y of the image to be recorded is equal to or less than the threshold value, and executes the second mode when the resolution exceeds the threshold value. In addition, the first execution unit 50A and the second execution unit 50B are controlled.

  For this reason, when the resolution of the image to be recorded in the second direction Y is equal to or lower than the threshold, the buffer 57 can be used to reduce the number of memory accesses to the RAM 48, thereby reducing the image forming speed. Therefore, image formation can be performed at high speed. If the resolution of the image to be recorded in the second direction Y exceeds the threshold value, pixel data is read from the RAM 48 a plurality of times, and image formation is performed without using the buffer 57. For this reason, it is not necessary to provide a buffer 57 having a larger capacity than necessary as the buffer 57, and the cost can be reduced.

  Further, by reducing the number of memory accesses to the RAM 48, it is possible to improve the data output performance to the recording unit 14 and improve the processing efficiency of the CPU.

  Note that switching between the first mode and the second mode according to the threshold value by the control unit 50C may be realized in software (by executing a program) or may be realized in hardware. This switching is preferably realized by executing a program.

  By realizing this switching by executing a program, it is not necessary to be aware of the hardware configuration of the image forming apparatus 10, and this embodiment can be realized with a control flow using a common program under any conditions. Become.

(Embodiment 2)
FIG. 9 is a configuration diagram of the image forming apparatus 10A of the present embodiment.

  The image forming apparatus 10A includes a PSU 32, a PC 33, an operation unit 34, a sensor 36, a drive unit 16, a recording unit 14, and a controller board 12A. Except for the controller board 12A, the image forming apparatus 10 is the same as that of the first embodiment.

  In the present embodiment, a plurality of recording units 14 are arranged along the first direction X and a plurality are arranged in the second direction Y, as shown in FIG. In the present embodiment, as an example, the recording units 14 are arranged in two rows along the second direction Y. The plurality of recording units 14 are arranged in a staggered manner.

  Returning to FIG. 9, the controller board 12A includes a power supply circuit 40, a host I / F 41, an operation unit I / F 42, a scanner I / F 43, a SoC 44, a sensor I / F 45, an engine control unit 46, and a RAM 48. A ROM 49, and an image output unit 51. The power supply circuit 40, the host I / F 41, the operation unit I / F 42, the scanner I / F 43, the sensor I / F 45, the engine control unit 46, the RAM 48, the ROM 49, and the image output unit 51 are electrically connected to the SoC 44. . The image output unit 51 is electrically connected to the SoC 44 and the RAM 48.

  The controller board 12A is the same as the controller board 12 of the first embodiment except that an image output unit 51 is provided instead of the image output unit 50.

  The image output unit 51 controls the recording unit 14 such that ink for recording dots corresponding to each pixel of the image data is ejected from the nozzles 18 provided in the recording unit 14. That is, the image output unit 51 transmits pixel group data and a driving waveform for driving the recording unit 14 to the recording unit 14 in accordance with the position of the recording medium P.

  The image output unit 51 is electrically connected to the SoC 44 and the RAM 48. That is, the image output unit 51 can directly access the RAM 48 without using a CPU (mounted on the SoC 44). For this reason, between the controller board 12A and the recording unit 14, the data can be transferred at high speed.

  The image output unit 51 includes a first execution unit 51A, a second execution unit 51B, a control unit 51C, and a buffer 65.

  The buffer 65 is a buffer for adjusting the output timing of the pixel group data. The buffer 65 is, for example, an SRAM.

  The buffer 65 is arranged on the upstream side in the second direction Y among the rows of the recording units 14 arranged in the second direction Y (in this embodiment, two rows in the second direction Y (see FIG. 1)). The columns of the recording units 14 and the columns of the recording units 14 arranged on the downstream side in the second direction Y are provided corresponding to each of the columns.

  As described above, in the present embodiment, since the recording units 14 are arranged in two rows in the second direction Y, the controller board 12A is connected to the recording unit 14 arranged upstream in the second direction Y. A case where a total of two buffers 65 (buffer 65A and buffer 65B) are provided for each of the columns and the columns of the recording units 14 arranged on the downstream side in the second direction Y will be described.

  The capacity of each buffer 65 is the same as that of the first embodiment.

  In addition, the structure provided with the buffer 65 for every recording part 14 may be sufficient. Further, as in the first embodiment, each of the nozzle rows 20 other than the nozzle row 20 arranged in the uppermost stream in the second direction Y among the nozzle rows 20 of the nozzles 18 provided in each recording unit 14. It is good also as a structure provided with the buffer 65 corresponding to these. In this case, it is preferable to adjust so that the buffer 65 corresponding to the nozzle row 20 located on the downstream side in the second direction Y has a larger capacity.

  The first execution unit 51A is the same as the first execution unit 50A. That is, the first execution unit 51A reads pixel data of a pixel column along the first direction X in the image data from the image data to be recorded stored in the RAM 48.

  Then, the first execution unit 51A has the nozzle row 20 (the nozzle row 20A in FIG. 2) arranged on the most upstream side in the second direction Y among the plurality of nozzle rows 20 of the recording unit 14 in the read pixel data. The pixel group data of the pixel group to be recorded is output to the recording unit 14 as pixel group data to be recorded by the nozzle row 20A. In addition, the first execution unit 51A stores, in the buffer 65, pixel group data of the pixel group recorded by the nozzle row 20B arranged on the downstream side in the second direction Y in the read pixel data. Similarly to the first embodiment, the pixel group data stored in the buffer 65 at a timing delayed according to the width between the nozzle rows 20 (see width W in FIG. 2) and the resolution of the image to be formed. Is output to the recording unit 14.

  The second execution unit 51B is the same as the second execution unit 50B. That is, the second execution unit 51B reads out the pixel data from the RAM 48, extracts pixel group data to be recorded by each nozzle row 20 from the pixel data, and outputs to the recording unit 14 a series of processes to be output to the recording unit 14. For each of the nozzle rows 20 (nozzle row 20A, nozzle row 20B) provided, it is repeatedly executed at each timing.

  That is, the first execution unit 51 </ b> A uses the buffer 65 when outputting data to the recording unit 14. On the other hand, the second execution unit 51B does not use the buffer 65 when data is output to the recording unit 14, but the pixel data of the same pixel column included in the image data is replaced with the number of nozzle rows 20 included in the recording unit 14, Read from RAM 48 multiple times.

  The control unit 51C controls the first execution unit 51A and the second execution unit 51B to execute at least one of the first mode and the second mode in accordance with the resolution in the second direction Y of the image to be recorded. .

  Specifically, the control unit 51C controls the first execution unit 51A to execute the first mode when the resolution in the second direction Y of the image to be recorded is equal to or less than a threshold value.

  On the other hand, when the resolution in the second direction Y of the image to be recorded exceeds the threshold value, the control unit 51C executes the second mode for the recording unit 14 disposed on the upstream side in the second direction Y, and the second mode The first execution unit 51A and the second execution unit 51B are controlled so as to execute the first mode for the recording unit 14 arranged on the downstream side in the direction Y. The threshold is the same as in the first embodiment.

  When the image forming apparatus 10A has a configuration in which a plurality of recording units 14 in four or more rows are arranged in the second direction Y, two recording units 14 adjacent in the second direction Y are set as one set, and each set is included in each set. The above process may be executed for the two rows of recording units 14 to which they belong.

  FIG. 10 is a block diagram illustrating a functional configuration of the image output unit 51.

  The image output unit 51 includes a reception unit 50D, a control unit 51C, a reading unit 53, a separation unit 56A, a buffer 65, an extraction unit 58, and an output unit 60.

  Implementation is performed except that a control unit 51C is provided instead of the control unit 50C, a buffer 65 is provided instead of the buffer 57, a separation unit 56A is provided instead of the separation unit 56, and an output unit 60 is provided instead of the output unit 59. This is the same as the image output unit 50 of the first embodiment.

  The output unit 60 includes an output unit 61 and an output unit 62. The output unit 61 outputs the pixel group data to the recording unit 14 disposed on the upstream side in the second direction Y. The output unit 62 outputs the pixel group data to the recording unit 14 disposed on the downstream side in the second direction Y.

Further, the output unit 61 outputs pixel group data to be recorded by each of the plurality of nozzle rows 20 provided in the recording unit 14 (recording unit 14 _{1 in} FIG. 10) arranged on the upstream side in the second direction Y. A plurality of output units. In the example shown in FIG. 10, the output unit 61 includes a first output portion 61A for outputting the pixel group data to be recorded on the upstream side of the nozzle array 20A in the second direction Y to the recording unit 14 _1, downstream of the second direction Y comprising a second output unit 61B for outputting the pixel group data to be recorded on the side of the nozzle array 20B to the recording unit 14 _1, the. A buffer 65A is allocated to the second output unit 61B as an initial setting.

Similarly, the output unit 62 outputs pixel group data to be recorded by each of the plurality of nozzle arrays 20 provided in the recording unit 14 (recording unit 14 _{2 in} FIG. 10) disposed on the downstream side in the second direction Y. A plurality of output units for outputting are provided. In the example shown in FIG. 10, the output unit 62 includes a first output portion 62A for outputting the pixel group data to be recorded on the upstream side of the nozzle array 20A in the second direction Y to the recording unit 14 _2, downstream of the second direction Y comprising a second output unit 62B for outputting the pixel group data to be recorded on the side of the nozzle array 20B to the recording unit 14 _2. A buffer 65B is allocated to the second output unit 62B as an initial setting.

The separation unit 56A separates the pixel data of the predetermined area read by the first reading unit 54 into pixel group data recorded by the nozzle row 20A and pixel group data recorded by the nozzle row 20B. Then, the separation unit 56A outputs pixel group data for the nozzle row 20A, which is the upstream nozzle row 20 in the second direction Y, to the output unit 60. In the output unit 60, for the recording unit 14 arranged on the upstream side in the second direction Y, the pixel group in which the first output unit 61A of the output unit 61 records the received pixel group data with the nozzle row 20A. as data is output to the recording unit 14 _1. In the output unit 60, for the recording unit 14 arranged on the downstream side in the second direction Y, the first output unit 62A of the output unit 62 records the received pixel group data with the nozzle row 20A. as the pixel group data is output to the recording unit 14 _2.

On the other hand, the separation unit 56 </ b> A stores pixel group data for the nozzle row 20 </ b> B, which is the nozzle row 20 on the downstream side in the second direction Y, in the buffer 65. At this time, the separation portion 56A, when the buffer 65A corresponding to the recording unit 14 ₁ which is disposed on the upstream side of the second direction Y is not used in the recording unit 14 _1, recording both the buffer 65A and the buffer 65B used as part 14 for _2. Specifically, a buffer 65A which has been assigned as the initial setting to the second output unit 61B for outputting the pixel group data to the recording unit 14 _1, the recording unit 14 ₂ to the second output unit 62B for outputting the image group data , Switch assignments.

Thus, the image output unit 51, a buffer 65A for recording portion 14 ₁ which is disposed on the upstream side of the second direction Y, if necessary, the recording unit 14 disposed on the downstream side of the second direction Y It is the structure which can be diverted for ₂ use.

  The first reading unit 54, the separation unit 56A, the buffer 65, and the output unit 60 correspond to the first execution unit 51A. Further, the second reading unit 55 (third reading unit 55A, fourth reading unit 55B), the extraction unit 58 (third extraction unit 58A, fourth extraction unit 58B), and the output unit 60 are added to the second execution unit 51B. Equivalent to.

Next, a procedure of processing executed by the image output unit 51 will be described. The process executed by the image output unit 51 is partially different from the process executed by the image output unit 50. That is, in the image output unit 51, when the control unit 51C determines that the resolution in the second direction Y of the image to be recorded is equal to or less than the threshold value, the control unit 51C controls the first execution unit 51A to execute the first mode. On the other hand, when the control unit 51C determines that the resolution in the second direction Y of the image to be recorded exceeds the threshold value, the recording unit 14 (recording unit 14 _{1 in} FIG. 10) arranged on the upstream side in the second direction Y. The first execution unit is configured to execute the second mode with respect to the recording unit 14 (recording unit 14 _{2 in} FIG. 10) disposed downstream in the second direction Y. 51A and the second execution unit 51B are controlled. The threshold is the same as in the first embodiment.

  Next, a specific example when the above processing is executed will be described. FIG. 11 is an explanatory diagram of a specific example of the present embodiment.

FIG. 11 assumes a case where the recording units 14 have a configuration in which two rows are arranged in the second direction Y. On the upstream side of the second direction Y recorder 14 ₁ is arranged, the recording unit 14 ₂ is disposed on the downstream side in the second direction Y. Specifically, as shown in FIG. 1, the recording units 14 are staggered in the first direction X and the second direction Y.

  Each recording unit 14 is configured to include two nozzle rows 20 of the nozzle row 20A and the nozzle row 20B in the second direction Y, and the width between the nozzle rows 20 is assumed to be 2.54 mm. (See also FIG. 2). Each of the nozzle array 20A and the nozzle array 20B in the recording unit 14 can record dots in the first direction X with a resolution of 300 dpi, as shown in FIG. Since the nozzles 18 of the nozzle array 20A and the nozzle array 20B are arranged in a staggered manner, the recording unit 14 is configured to be able to record an image of 600 dpi in the first direction X.

Therefore, FIG. 11, four nozzle rows 20 (second direction Y on the upstream side of the recording portion 14 ₁ of the nozzle arrays 20A in the second direction Y, the nozzle array 20B, the downstream side of the recording portion in the second direction Y 14 One color (for example, black) image is formed by the _two nozzle rows 20A and 20B).

Further, in the example shown in FIG. 11, the threshold value is 600dpi, the buffer 65A for recording portion 14 _1, and each of the capacity of the buffer 65B for recording portion 14 _2, the image data having a resolution 600dpi in the second direction Y A case will be described in which the capacity is equivalent to 60 lines of pixel data of one line of pixel rows along the first direction X.

That is, the buffer 65A is output to the recording unit 14 ₁ of the pixel group data to be recorded in the nozzle array 20B of the recording unit 14 _1, the output to the recording unit 14 ₁ of the nozzle array 20A, the second direction Y It is used to delay 60 pixel lines. The buffer 65B is output to the recording unit 14 ₂ of the nozzle array 20B recording unit 14 ₂ of the pixel group data to be recorded in, the nozzle row 20A of the recording unit 14 _2, 60 lines of the second direction Y Used to delay by a pixel column.

FIG. 11 is a specific example showing a case where the resolution in the second direction Y of the image to be recorded is 1200 dpi exceeding the threshold (600 dpi). That is, FIG. 11, the control unit 51C is the recording unit 14 ₁ which is disposed on the upstream side of the second direction Y by executing the second mode, the recording unit 14 disposed on the downstream side of the second direction Y ₂ is an explanatory diagram illustrating a case where the first execution unit 51A and the second execution unit 51B are controlled so that the first mode is executed with respect to 2. FIG.

As shown in FIG. 11, for the recording portion 14 ₁ which is disposed on the upstream side in the second direction Y, the second execution unit 51B executes the second mode.

That is, the third reading unit 55A is, from the image data stored in the RAM 48, the pixel data of the pixel row along the first direction X, read as pixel data for the nozzle array 20A of the recording unit 14 _1. Next, the third extraction unit 58A is the third reading unit 55A read from the pixel data for the nozzle array 20A of the recording unit 14 _1, extracts the pixel group data to be recorded in the nozzle array 20A of the recording unit 14 ₁ . The extraction method is the same as in the first embodiment.

The first output section 61A, when the third extraction unit 58A accepts pixel group data from the pixel group data received, and outputs the pixel group data to be recorded in the nozzle array 20A of the recording unit 14 ₁ to the recording unit 14 _1.

On the other hand, the fourth reading unit 55 </ b> B reads pixel data from image data stored in the RAM 48. Next, the fourth extraction unit 58B is, the pixel data read by the fourth reading unit 55B, and extracts the pixel group data to be recorded in the nozzle array 20B of the recording unit 14 _1. Then, the fourth extraction unit 58B outputs this pixel group data to the second output unit 61B.

The second output unit 61B, when the fourth extraction unit 58B receives the pixel group data from the pixel group data received, and outputs the pixel group data to be recorded in the nozzle array 20B of the recording unit 14 ₁ to the recording unit 14 _1.

Therefore, in this embodiment, when the resolution of the recording target image exceeds a threshold value, for the recording portion 14 ₁ which is disposed on the upstream side of the second direction Y, a buffer 65A corresponding to the recording unit 14 ₁ The second mode is executed without using.

On the other hand, with respect to the recording unit 14 ₂ disposed on the downstream side in the second direction Y, the first execution unit 51A executes the first mode.

That is, the first reading unit 54 reads pixel data from image data stored in the RAM 48. The first reading unit 54 reads pixel data by issuing a read request. The first reading section 54, by issuing one read request, read together pixel data of the nozzle array 20A of the recording portion 14 ₂ and the nozzle array 20B.

Then, the separation unit 56 separates the pixel data read, the pixel group data to be recorded in the nozzle array 20A of the recording unit 14 _2, and the pixel group data to be recorded in the nozzle array 20B of the recording unit 14 _2, the. The separation method is the same as in the first embodiment.

Separating section 56A outputs the pixel group data to be recorded in the nozzle array 20A of the recording unit 14 ₂ to the first output portion 62A. The first output unit 62A accepts the pixel group data is output as the pixel group data to be recorded in the nozzle array 20A to the recording unit 14 _2.

On the other hand, the separation unit 56 </ _b > A outputs the pixel group data recorded by the nozzle row 20 </ _b > B of the recording unit 142 to the buffer 65. Here, the recording unit 14 ₁ of the upstream side in the second direction Y, since no use buffer 65A, the buffer 65A for recording portion 14 _1, the downstream buffer for recording portion 14 ₂ of the second direction Y Can be used.

Thus, the separation portion 56A has a pixel group data to be recorded in the nozzle array 20B of the recording unit 14 _2, and outputs to the buffer 65A and the buffer 65B. That is, as described above, the separation unit 56A, when the buffer 65A corresponding to the recording unit 14 ₁ which is disposed on the upstream side of the second direction Y is not used in the recording unit 14 _1, the buffer 65A and a buffer 65B both used for the recording unit 14 _2. Specifically, a buffer 65A which has been assigned as the initial setting to the second output unit 61B for outputting the pixel group data to the recording unit 14 _1, the recording unit 14 ₂ to the second output unit 62B for outputting the image group data , Switch assignments. For this reason, the second output unit 62B can share and use a plurality of buffers 65 (buffer 65A, buffer 65B). That is, the second output unit 62B can delay 120 lines with respect to the first output unit 62A.

When the pixel group data is sequentially stored in the buffer 65A and the buffer 65B and stored for 120 lines, the second output unit 62B is further forwarded every time pixel group data for one line is stored in the buffer 65. in order from the one line of the pixel group data stored in, and output as the pixel group data to be recorded in the nozzle array 20B to the recording unit 14 _2.

  For this reason, in the recording part 14 arrange | positioned downstream of the 2nd direction Y, the access count of RAM48 can be suppressed and the fall of a memory access speed can be suppressed.

  As described above, in the image forming apparatus 10A according to the present embodiment, the control unit 51C is arranged on the upstream side in the second direction Y when the resolution in the second direction Y of the image to be recorded exceeds the threshold value. The first execution unit 51A and the second execution unit 51B execute the second mode for the recording unit 14 and execute the first mode for the recording unit 14 arranged on the downstream side in the second direction Y. To control.

  For this reason, the effect similar to Embodiment 1 is acquired.

In the image forming apparatus 10A of this embodiment, when the buffer 65A corresponding to the recording unit 14 ₁ which is disposed on the upstream side of the second direction Y is not used in the recording unit 14 _1, the buffer 65A and the buffer both 65B used for the recording unit 14 _2. Specifically, a buffer 65A which has been assigned as the initial setting to the second output unit 61B for outputting the pixel group data to the recording unit 14 _1, the recording unit 14 ₂ to the second output unit 62B for outputting the image group data , Switch assignments.

  As described above, in the image forming apparatus 10A of the present embodiment, when the resolution of the image to be recorded in the second direction Y exceeds the threshold, the recording unit 14 disposed on the downstream side in the second direction Y is used. Thus, the first mode is executed by using both the buffer 65 corresponding to the recording unit 14 and the buffer 65 corresponding to the recording unit 14 disposed upstream of the recording unit 14 in the second direction Y. .

  For this reason, in the recording unit 14 on the downstream side in the second direction Y, the number of memory accesses to the RAM 48 can be further reduced. Further, the capacity of the buffer 65 provided in the image forming apparatus 10A can be reduced.

  Moreover, since the allocation of the buffer 65 to each output unit (the first output unit 61A, the second output unit 61B, the first output unit 62A, and the second output unit 62B) can be switched in a fluid manner as described above. Therefore, the number of memory accesses to the RAM 48 can be reduced and efficient data output can be realized. Further, by reducing the number of memory accesses to the RAM 48, it is possible to improve the data output performance to the recording unit 14 and improve the processing efficiency of the CPU.

  A configuration in which a buffer 65 is provided for each recording unit 14 may be employed. In this case, when the width B in the first direction X of the recording medium P is smaller than the maximum width in the first direction X that can be recorded by the recording unit 14 of the image forming apparatus 10A, the buffer 65 corresponding to the unused recording unit 14 is provided. The recording unit 14 that ejects ink may be used.

  As described above, also in the first direction X, the number of memory accesses to the RAM 48 can be reduced by diverting the buffer 65 corresponding to the recording unit 14.

  Note that the switching of the allocation of the buffer 65 (the buffer 65A and the buffer 65B) may be realized in software (by executing a program) or hardware. Note that this switching is preferably realized by executing a program.

  By realizing this switching by executing a program, it is not necessary to be aware of the hardware configuration of the image forming apparatus 10A, and this embodiment can be realized with a control flow by a common program under any condition. . In addition, effects such as reduction in the size of the hardware configuration, reduction in cost, and reduction in development costs can be obtained.

(Embodiment 3)
In the second embodiment, the four nozzle rows 20 in the second direction Y (the nozzle row 20A, the nozzle row 20B, and the second direction Y of the upstream recording unit 14 (recording unit 14 ₁ ) in the second direction Y). The case where an image of one color (for example, black) is formed by the nozzle row 20A and the nozzle row 20B of the downstream recording unit 14 (recording unit 14 ₂ ) has been described (see FIG. 11).

  However, the image forming apparatus 10A according to the above-described embodiment can also be applied to an image forming apparatus that forms images of a plurality of colors.

  In this case, a configuration in which a recording unit in which a plurality of recording units 14 shown in FIG. 1 are arranged in a staggered manner may be provided for each color. In other words, a configuration in which a plurality of recording units that discharge droplets (inks) of different colors is arranged along the second direction Y may be used. The recording unit may have a configuration in which a plurality of recording units 14 are arranged in a staggered manner. Then, the first mode and the second mode may be executed for each recording unit as in the second embodiment.

  At this time, if the image to be recorded is a monochrome image, a buffer (buffer 65 in the second embodiment) provided in the recording unit other than the color to be recorded is used for the recording unit that records the color to be recorded. That's fine.

  That is, when the resolution in the second direction Y of the image to be recorded exceeds the threshold value, the control unit 51C determines that the second direction Y in the recording unit arranged at the most downstream of the second direction Y among the plurality of recording units. A buffer 65 corresponding to the recording unit 14, and a buffer 65 corresponding to the recording unit 14 positioned upstream in the second direction Y from the recording unit 14. The first mode is executed by using the buffer 65 corresponding to each of the recording units 14 included in each of the recording units arranged upstream of the recording unit in the second direction Y. The execution unit 51A is controlled.

  With this configuration, the number of accesses to the RAM 48 can be further reduced.

  Further, it is assumed that images of three colors (for example, C, M, and Y) can be recorded as a plurality of color images in addition to black. Then, it is assumed that a black monochrome image is formed. In this case, the buffers for the recording units of the three colors C, M, and Y other than the black to be recorded (buffer 65 in the second embodiment) are used for black monochrome images. For this reason, assuming that each buffer 65 has a capacity of 60 lines as described above, a buffer having a capacity of 240 lines can be used for a black monochrome image. Therefore, in this case, if the resolution in the second direction Y is up to 2400 dpi, it can be stored in the buffer.

  Examples for explaining the present embodiment in more detail are shown below, but the present invention is not limited to these examples.

  FIG. 12 is a table showing an example to which each of Embodiments 1 to 3 is applied and a comparative example to which Comparative Examples 1 to 2 are applied.

  Comparative Example 1 is a case where data output to the recording unit 14 is always executed in the first mode using a buffer regardless of the resolution in the second direction Y of the image to be recorded (first execution in FIG. 8). Part 50A). Comparative Example 2 is a case where data output to the recording unit 14 is always read a plurality of times regardless of the resolution in the second direction Y of the image to be recorded and executed in the second mode without using a buffer ( (See the second execution unit 50B in FIG. 8).

  Specifically, FIG. 12 is a table showing the relationship among the width between the nozzle arrays 20, the second direction resolution of the image to be recorded, the buffer capacity (buffer capacity), and the required number of memory reads. .

  As shown in FIG. 1, the recording units 14 are arranged in two rows in the second direction Y and a plurality of recording units 14 in the first direction X, and the plurality of recording units 14 are arranged in a staggered manner. Each recording unit 14 includes two nozzle rows 20 as shown in FIG.

  In FIG. 12, a value satisfying the condition described in the above embodiment is set as the threshold value.

  Specifically, when the gap width between the nozzle rows is 2.54 mm and the buffer capacity is 60 lines, a resolution of 600 dpi is set as the threshold value. When the gap width between the nozzle rows is 2.54 mm and the buffer capacity is 120 lines, a resolution of 1200 dpi is set as the threshold value. When the gap width between the nozzle rows was 2.54 mm and the buffer capacity was 240 lines, a resolution of 2400 dpi was set as the threshold value.

  Further, when the gap width between the nozzle rows is 5.08 mm and the buffer capacity is 60 lines, a resolution of 300 dpi is set as the threshold value. Further, when the gap width between the nozzle rows is 5.08 mm and the buffer capacity is 120 lines, a resolution of 600 dpi is set as the threshold value. When the gap width between the nozzle rows is 5.08 mm and the buffer capacity is 240 lines, a resolution of 1200 dpi is set as the threshold value.

  As shown in FIG. 12, when the first to third embodiments are applied, it is possible to reduce the required number of memory reads for the RAM 48 compared to the first and second comparative examples. In the first to third embodiments, as described above, the first mode and the second mode are switched and executed according to the resolution in the second direction Y of the image to be recorded.

  Therefore, in the image forming apparatus 10 and the image forming apparatus 10A according to the first to third embodiments, when the resolution in the second direction Y is higher than the threshold, the image quality is not deteriorated. High resolution images can be recorded without providing a buffer such as SRAM more than necessary.

  In the image forming apparatus 10 and the image forming apparatus 10A according to the first to third embodiments, when the resolution in the second direction Y is lower than the threshold, the delay is realized using a buffer. Therefore, the number of memory accesses to the RAM 48 can be reduced, and image formation can be performed at high speed.

  In addition, although embodiment was described above, the said embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10, 10A Image forming apparatus 14 Recording unit 18 Nozzle 48 RAM
50, 51 Image output unit 50A, 51A First execution unit 50B, 51B Second execution unit 50C, 51C Control unit 57, 65, 65A, 65B Buffer

JP 2008-183884 A

Claims (9)

A recording section in which a plurality of nozzle rows in which a plurality of nozzles for discharging droplets are arranged in a first direction are arranged in a second direction intersecting the first direction;
A drive unit for moving the recording medium relative to the recording unit in the second direction;
A storage unit for storing image data of an image to be recorded;
The pixel data of the pixel column along the first direction in the image data is read from the storage unit, and each of the pixel group data to be recorded by each of the nozzle columns included in the pixel data is read from the image data. An image output unit for outputting to the recording unit at each timing delayed according to the width between the nozzle rows so as to realize resolution in two directions;
With
The image output unit includes:
A buffer for storing the pixel group data;
The pixel data is repeatedly read from the storage unit a number of times according to the number of the nozzle rows, and the pixel group data recorded by each of the nozzle rows included in the pixel data is output to the recording unit at each timing. A first execution unit for executing a first mode;
The pixel data is read from the storage unit, and the pixel group data to be recorded by at least the nozzle row arranged in the uppermost stream in the second direction among the plurality of nozzle rows is output to the recording unit, and the nozzle A second execution unit that executes a second mode in which the pixel group data to be recorded by the nozzle row disposed downstream of the row in the second direction is stored in the buffer and then output to the recording unit;
A control unit that controls the first execution unit and the second execution unit to execute the first mode or the second mode according to the resolution;
An image forming apparatus. The controller is
The first execution unit and the second execution unit are controlled to execute the first mode when the resolution is equal to or lower than a threshold value, and to execute the second mode when the resolution exceeds the threshold value. The image forming apparatus according to claim 1.   2. The buffer has a capacity capable of holding the pixel group data of an image less than the maximum resolution in the second direction that can be recorded by the image forming apparatus, in accordance with a width between the nozzle rows. Alternatively, the image forming apparatus according to claim 2.   4. The buffer has a capacity capable of holding the pixel group data of an image having a resolution equal to or higher than the minimum resolution in the second direction that can be recorded by the image forming apparatus, according to a width between the nozzle rows. The image forming apparatus described in 1.   The buffer is provided corresponding to each of the nozzle rows arranged downstream in the second direction from the nozzle row arranged in the uppermost stream in the second direction among the plurality of nozzle rows. The image forming apparatus according to claim 1. A plurality of the recording units are arranged in at least the second direction,
The control unit executes the first mode when the resolution is less than or equal to the threshold value, and is disposed upstream of the recording unit in the second direction when the resolution exceeds the threshold value. The first execution unit and the first mode are executed so that the second mode is executed on the recording unit, and the first mode is executed on the recording unit arranged on the downstream side in the second direction. 2. The image forming apparatus according to claim 1, which controls an execution unit.   The said buffer is provided corresponding to each of the said recording part arrange | positioned in the upstream of the said 2nd direction, and the said recording part arrange | positioned in the downstream of the said 2nd direction. Image forming apparatus. The controller is
When the resolution exceeds the threshold, the buffer corresponding to the recording unit and the upstream of the recording unit upstream of the recording unit are arranged with respect to the recording unit arranged downstream of the second direction. The image forming apparatus according to claim 7, wherein the first execution unit is controlled to execute the first mode using the buffer corresponding to the recording unit. Arranging a plurality of recording units having the recording unit for discharging the droplets of different colors along the second direction,
The controller is
When the resolution exceeds the threshold, among the plurality of recording units, the recording unit disposed on the downstream side in the second direction in the recording unit disposed on the most downstream side in the second direction. The buffer corresponding to the recording unit, the buffer corresponding to the recording unit disposed upstream of the recording unit in the second direction, and upstream of the recording unit in the second direction. 8. The first execution unit is controlled to execute the first mode using the buffer corresponding to each of the recording units included in each of the recording units. Image forming apparatus.

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