JP2013035254A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing a throughput by a plurality of monitor controls, at the minimum level.SOLUTION: A power monitor determines as to whether divided printing is performed and a carriage moving speed, color unevenness in a printing range of the divided printing is determined by a color unevenness monitor, a printing direction and a carriage speed in which a temperature rise in a printing range of the divided printing is decided by an excessive temperature prevention monitor are determined to perform the printing while taking the determined items into account.

Description

  The present invention relates to an apparatus for forming an image by ejecting a recording liquid such as ink onto a recording medium while scanning recording means.

  As one of image forming (recording) devices for outputting information such as characters and images processed by copying devices, information processing devices such as word processors and computers, and communication devices. In addition, those that perform digital image recording by the ink jet method are widely used. In such an ink jet recording apparatus, there are various problems depending on the characteristics of the recording head, and various monitor controls are performed to solve these problems. The following monitor control is disclosed as various problems of the recording head and a method for solving the problems.

[Color unevenness monitor control]
The recording head uses a plurality of colors of ink, and the nozzle arrays for ejecting ink are arranged in a straight line in the sub-scanning direction. Color unevenness due to the difference in ejection color order caused by performing reciprocal recording, and unidirectional A decrease in recording speed due to recording only has been a problem. In order to solve this problem, a method is disclosed in which the mixed state of each ink in the image data is quantified and the moving direction of the carriage is determined based on the information. (See Patent Document 1).

[Power monitor control]
The amount of information varies greatly depending on the content of the image data, and there is a distribution in the recording dot density according to the recording location in a predetermined area, such as one page of recording paper, and the amount of power required for driving the recording head is The problem was that the capacity became large. In order to solve this problem, a method is disclosed in which the carriage movement speed and the number of divided prints are determined when the dot count of the area divided into predetermined units is equal to or greater than the predetermined dot count. (See Patent Document 2).

[Overheat prevention monitor control]
The amount of information varies greatly depending on the contents of the image data, and there is a distribution in the recording dot density of a specific ink, the ink ejection amount increases, the temperature of the recording head rises, and the volume of ejected ink droplets As a result, the refilling of ink cannot be made in time, and there has been a problem of occurrence of ejection defects such as twisting and shobo. In order to solve this problem, a method is disclosed in which a threshold corresponding to the temperature of the recording head is compared with a dot count to determine a driving frequency and a carriage moving speed. (See Patent Document 3).

JP 2002-248798 A JP 2005-224955 A JP-A-2005-246641

  The above-mentioned patent documents are monitor controls for solving each problem based on dot count information, and each monitor determines one of frequency, carriage moving speed, carriage scanning direction, and number of divided prints. Has solved the problem. However, when these monitor controls are operated, depending on the image data, an unexpected reduction in image quality and a reduction in throughput may be caused. For this reason, it has been difficult to maintain image quality and minimize throughput.

  The present invention has been made in view of the above problems, and an image forming apparatus capable of minimizing a decrease in throughput due to a frequency, a carriage moving speed, a carriage scanning direction, and the number of divided prints determined by each monitor control. I will provide a.

  First, whether or not to perform divided printing is determined by power monitor control, and the number of divided printing and carriage movement speed when performing divided printing are determined. When it is determined that the division printing is performed by the determining unit, the printing range to be printed in one scan is set by the number of divided printings. Color unevenness monitor control and excessive temperature rise prevention monitor control change the print area for determining the dot count to a range set by the setting means. Secondly, the uneven color monitor control determines whether or not to change the print area to one-way printing. If it is determined by the determining means that unidirectional printing is to be performed, the dot count threshold per temperature of the recording head, which is a determination element of the excessive temperature rise prevention monitor control, is changed. The excessive temperature rise prevention monitor control compares the dot count in the changed print area range with the dot count threshold value per temperature, and determines whether or not to reduce the carriage movement speed.

  According to the present invention, it is possible to suppress degradation in image quality due to each monitor control, and to minimize degradation in throughput.

Schematic diagram of inkjet printer Block diagram of image forming apparatus Flow chart (boundary part) showing an example of color unevenness monitor control processing Flow chart showing an example of uneven color monitor control processing (central part) Window explanatory diagram for calculating duty Flow chart showing an example of power monitor control processing A table showing the presence or absence of carriage speed reduction and the number of divisions for divided printing in the printing method Flow chart showing an example of overheat prevention monitor control processing Printing image for explaining the embodiment FIG. Printing image for explaining the embodiment FIG. 2 Printing image for explaining the embodiment FIG. 3 The flowchart which showed an example of the process of embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an appearance of an ink jet recording apparatus that implements the present embodiment. A carriage 11 on which the recording head 12 is mounted, an optical position sensor 13 that optically reads the position of the carriage, a recovery means 14 for performing recovery processing of the recording head 12, and the like are included. The recording head 12 includes a temperature sensor for detecting the temperature of the recording head 12. The ink jet recording apparatus having such a configuration serially scans the carriage 11 and performs printing with a width corresponding to the ejection port (number of nozzles) of the ink jet head, while intermittently applying a predetermined amount of a recording medium during non-printing. Transport.

  Further, in the recovery means 14, 141 is a suction and leaving cap, 142 is a discharge receiver that receives the discharged processing liquid during discharge recovery, and 143 is a discharge receiver that receives the discharged ink during discharge recovery. A wiper blade 144 wipes the face surface, and wipes the face surface while moving in the direction of the arrow.

  FIG. 2 is a block diagram showing the configuration of an ink jet recording apparatus that implements the present embodiment.

  In the figure, reference numeral 201 denotes a motor driver, which is a carriage motor (operating the recording head) for performing the printing operation of the serial recording apparatus, a paper feed motor (moving the recording medium, feeding and discharging), and a recovery motor (printing). This is a control circuit for controlling motors such as a head recovery operation.

  12 The recording head has a function of printing an image on a recording medium. In the case of a replaceable head, each recording head has a unique ID, and whether or not the head has been replaced can be determined by comparing this ID.

  202. A RAM (Random Access Memory) is a storage device that can hold information only while power is supplied. If the power supply is cut off, the stored information disappears.

  203. A ROM (Read Only Memory) is a recording device that can only be read, and records a control program of the ink jet recording device, and performs a control operation with reference to the CPU.

  204. The CPU reads a control program from the ROM and executes control of each control device according to the program.

  205. The interface is the ink jet recording apparatus and 107. It has a function to connect a host computer, receive print data from the host computer, and send status to the host computer.

  207. The non-volatile memory is a recording device that holds and records various types of information, and can continue to hold the recorded information even when power supply is cut off.

  208. The operation unit includes a key for receiving a key operation from the user, a display device for notifying the user of an error, and the like.

  209. The dot count unit is a circuit having a function of measuring the number of ink droplets actually ejected from the print head.

  210. The power monitor control unit divides the calculated block to be printed during one scan by the dot count unit 209 into a plurality of blocks in the sub-scanning direction, and calculates the number of driving times of the head recording element driven by one scan. If it is larger than a predetermined threshold value, the number of times of driving the head recording element by one scan is suppressed by performing a carriage movement speed reduction, two-division printing, and four-division printing.

  211. The color unevenness monitor control unit divides the calculated print range during one scan into a plurality of the search direction and the sub-scan direction by the dot count unit 209, and calculates each dot count value of the divided range. Then, when a predetermined range is continued at the print boundary or the center in a range that is larger than a threshold determined in advance based on the dot count information, color unevenness is suppressed by printing in one direction.

  212. The overheat prevention monitor control unit divides the calculated print range during one scan into a plurality of search directions and sub-scan directions by the dot count unit 209, and calculates each dot count value of the divided range. . If the predetermined threshold value corresponding to the temperature of the recording head 12 is larger than that, the drive frequency and the carriage moving speed are changed to suppress the temperature rise.

  213. The printing method control unit waits until data for one scan is stored in the print buffer, and requests the power monitor 210, the color unevenness monitor control unit 211, and the excessive temperature rise prevention monitor control 212 to perform processing. Then, the carriage moving speed and the number of divided prints determined by the power monitor control unit 210, the printing direction determined by the color unevenness monitor control unit 211, and the driving frequency and carriage moving speed determined by the excessive temperature rise prevention monitor control 212 are used. Determine the optimal printing method.

  Control of the color unevenness monitor control unit 211 will be described using a flowchart. 3 and 4 are flowcharts showing the color unevenness monitor. The unidirectional printing and reciprocating printing designation control according to this embodiment will be described below with reference to the flowcharts of FIGS. 3 and 4.

  First, at step 301, as initialization, the determination count is set to 0, and monitoring of an upper boundary area (area E ′ in FIG. 5) of image data to be printed is started. In step S302, dot counts of cyan, magenta, and yellow are performed for each window C area. From this dot count, the duty (ink application amount) is obtained. 100% duty applies about 4.5 pl of ink droplets once on a 1/1200 inch square recording medium, that is, about 4.5 pl of ink droplets on every 1/1200 inch square of each specified area. It is to give once. In step S303, the remaining duty Dr is calculated using the calculated duty. The residual duty refers to the degree of mixing of inks of two or more colors. Specifically, the difference between the total duty (total) and the maximum duty value (Max) for each color is calculated.

  Subsequently, in step S304, a determination is made with respect to the residual duty Dr obtained in step S303. Here, since the boundary region is monitored, a lower threshold value of 30% is used, and it is determined whether the remaining duty Dr is 30% or more. If the remaining duty Dr is less than 30%, the determination count is returned to 0 in step S308, and the process proceeds to step S309. On the other hand, when the remaining duty is 30% or more, the process proceeds to step S305, and 1 is added to the determination count. In step S306, it is determined whether or not the determination count is 3 or more in order to determine whether or not the remaining duty is 30% or more continuously three times or more.

  When the determination count is 3 or more, since it is determined that there is a region having a high residual duty Dr continuously at the boundary portion, monitoring is stopped and designated direction printing (one-way printing) is performed. If the determination count is 2 or less, the process proceeds to step S309. In step S309, it is determined whether the determination window C has reached the right edge of the image. If it has not reached the right end, the process proceeds to step S310, the window C is moved to the right by one block, and the process returns to step S302 again to continue monitoring. When the window C has reached the right end in this way, the upper boundary region has ended, and the process proceeds to step S311 to move the window C to the next region.

  By repeating the above processing, it is possible to perform all monitoring of the boundary region E ′ above the image to be printed. If there is no continuous area with a high residual duty in the boundary area above the image, the process proceeds from step S309 to step S311 and moves to monitoring of the next area. When the upper boundary region E ′ is monitored, the remaining duty of the boundary region E below the image is monitored by the same operation as the next region. That is, the process proceeds from step S311 to step S312, where the window C is arranged at the right end of the lower boundary E, the determination count is initialized to 0, and the process returns to step S302. If there is no continuous area with a high residual duty even in the lower boundary region, the process proceeds from step S311 to step S313, and the residual duty at the center of the image is monitored by the same calculation.

  FIG. 4 is a flowchart showing the operation. The process of steps S401 to S410 is the same as the process of steps S401 to S410. However, a high threshold value (100%) is used in step S404 because the central portion does not contact the next printing region or the previous printing region. If the window C reaches the right end, the process proceeds from step S411 to step S412. The window C is moved to the right end of the next lower step, the determination count is initialized to 0, and the process proceeds to step S402. return. In this way, monitoring is performed for all the central areas, and if it is determined that there is no continuous area having a high residual duty, the process proceeds to step S413, and direction designation is not performed, that is, bidirectional printing is to be performed. decide.

  If it is determined to perform bidirectional printing, for example, control may be performed so as to scan in the direction opposite to the previous scanning direction. However, if the recording operation is always performed in the direction opposite to the previous scanning direction, even if there is an image in the left half in the previous scanning area and only the right half in the next scanning area, each scanning Since it is necessary to move the recording head over the entire scanning area, the following control may be performed. That is, when it is decided not to print in the specified direction, there is an image in only the left half of the previous scanning area and the recording scan is performed from the left side in order to select the scanning procedure that is the shortest in time. When there is an image of only the right half of the next scanning area, the recording head is stopped at the end position of the left half of the recording scan, and after the recording paper is conveyed, the scanning direction is changed from left to right. Print twice while keeping.

  210. The control of the power monitor unit will be described using a flowchart.

  FIG. 6 is a flowchart showing the power monitor. First, in step S601, determination of a dot count value is started. If there is an area in which the dot count is equal to or greater than the predetermined threshold value in step S602, the process proceeds to step S604, where the determination process for one scan is interrupted, and based on the dot count threshold value and printing method association table in FIG. Determine the printing method. In step S603, the printing method is determined in step S604 even when there is no monitor area equal to or greater than the threshold value and determination of the monitor area for one scan is completed. In step S605, it is determined whether the printing method determined in step S604 needs to reduce the carriage speed. If necessary, the speed setting is changed in step S606. If not, the printing method is determined in step S607. The speed setting is not changed, and it is determined whether the determined printing method needs to be divided. If division is not necessary, the process advances to step S608 to perform one-scan printing as usual.

  If it is determined in step S607 that split printing is to be performed, the upper half of step S609 is printed first, and then the lower half of step S610 is printed. If it is determined in step S607 that four-division printing is necessary, upper printing (1/4 and 2/4) is performed (step S611, step S612), and lower printing (3). / 4, 4/4) are performed (step S613, step S614).

  212. Control of the excessive temperature rise prevention monitor unit will be described using a flowchart.

  FIG. 8 shows a process executed in each block of the overheat prevention monitor. FIG. 8 shows the overheat prevention monitor in a flowchart. First, in step S801, dot counting is performed for each divided area obtained by dividing an area corresponding to one scan recorded by the recording head into predetermined monitor size units. This dot count is performed independently for each color. This divided area is a unit for performing dot count.

  Next, in step S802, the counted dot count is calculated for each color as a value corresponding to the maximum dot count among the dot counts counted in each divided area in one band. In step S803, the head temperature of each color recording head is acquired, and in step S804, the threshold dot count of each color is calculated from the head temperature of each color based on the acquired head temperature information. In step S805, the maximum dot count corresponding to each color and the threshold dot count corresponding to each color are compared, and it is determined whether the maximum dot count exceeds the threshold dot count for any one color. . If the threshold dot count is exceeded, the process proceeds to step S807, where the drive frequency and carriage speed are reduced.

  On the other hand, if the threshold dot count has not been exceeded, the process advances to step S806 to maintain a predetermined drive frequency and carriage speed. In step S808, recording is performed at the determined drive frequency and carriage speed.

  213. Control of the printing method control unit will be described with reference to the drawings and flowcharts.

  FIG. 9 shows an image in which image data is printed on a recording medium. When the dot count of the first scan is high and the first scan is printed by one scan, this image data is caused by an overpower capacity and a temperature rise. Although ejection failure occurs, color unevenness does not occur even if the first and second scans are printed by reciprocal printing. However, in F, G, and H, color unevenness does not occur in the central portion, but color unevenness occurs when the boundary portion is reached. A description will be given of FIG. 10 printed when the main image data is processed by each monitor (the power monitor 210, the color unevenness monitor 211, and the excessive temperature rise prevention monitor 212) without considering each monitor. The processing flow of the power monitor 210 is processed with no carriage speed reduction in quadrant printing according to FIG. Therefore, the first scan is printed by four scans of 1-1 scan, 1-2 scan, 1-3 scan, and 1-4 scan.

  Next, the process of the uneven color monitor 211 is performed. In the color unevenness monitor, since it is determined that the first scan is processed by one scan, the determination process in the same print area is performed for the 1-1 scan, 1-2 scan, 1-3 scan, and 1-4 scan. Is called. 3 and 4, it is determined that color unevenness does not occur in the first scan and the second scan, and the 1-1 scan, 1-2 scan, 1-3 scan, and 1-4 scan are performed. Reciprocal printing is performed for all scans. As a result, color unevenness due to reciprocal printing occurs in F, G, and H. Next, processing of the excessive temperature rise prevention monitor 212 is performed. Determination processing in the same print area is performed for 1-1 scan, 1-2 scan, 1-3 scan, and 1-4 scan. The main image data is instructed to reduce the carriage speed by the processing of FIG. However, the print head temperature actually has a threshold value only during 1-2 scans, and the throughput decreases due to the reduction in carriage speed during 1-1 scans, 1-3 scans, and 1-4 scans. .

  Next, the printing method control unit 213 considering each monitor will be described using a flowchart. FIG. 12 is a flowchart showing the printing method control unit 213 monitor. First, in step S1201, the power monitor 210 is requested to perform processing. The power monitor performs the processing of FIG. 6 and determines the printing method (division printing, carriage speed reduction). Next, the process proceeds to step S1202, and when it is determined that the image is divided into two or four, the process proceeds to step 1203, and the number of scans is reset to 2 or 4. If it is determined not to perform divided printing, the number of scans is not changed from 1, and the process proceeds to step S1204. In step S1204, a range to be printed in the next scan is determined from the divided print number and the scan number. As shown in FIG. 13, when the number of divisions is 2, the print range is a print range in which the first scan and the first scan are performed in one scan. When the number of divisions is 4, the 1-1st scan is a print range performed in one scan. When the image is not divided, the scan range is not changed, and the first scan, the first scan, the first scan, and the fourth scan are the print range.

  In step S1205, the color unevenness monitor 211 is requested to perform processing. The color unevenness monitor performs the processes shown in FIGS. 3 and 4 based on the print range determined in step 1204 to determine the scan direction. Next, the process proceeds to step S1206. If it is determined that one-way printing is performed, the process proceeds to step S1207. In step S1207, the threshold value based on the temperature for the excessive temperature rise prevention monitor 211 is changed. The threshold is determined from the carriage return distance. If it is determined in step S1206 that reciprocal printing is to be performed, the process proceeds to step S1208 without changing the threshold value for the temperature rise prevention monitor 211. In step S1208, the over temperature prevention monitor 212 is requested to perform processing. The color unevenness monitor determines the carriage speed based on the threshold value determined in step 1207.

  In step 1209, the number of divided printing, the printing direction, and the carriage speed determined by the above processing are set and printing is performed. Proceeding to step S1210, if the number of scans has not been reached, the processing from step 1204 to step S1209 is repeated. If the number of scans has been reached, the process is terminated and the process proceeds to the second scan.

11 Carriage 12 Recording head

Claims (1)

A recording apparatus that performs recording while scanning a carriage on which a recording head is mounted, wherein a mixed state of an image in a scanning area is quantified from a dot count, and the direction of the carriage with respect to the scanning area is determined based on the quantification information. Determined from the carriage direction determining means to be determined and the dot count of the printing element drive count in the print head, related to the size of the partial area in the scanning area, and discriminated whether the drive count is greater than a predetermined value and divided Divided print determining means for determining the number of print divisions, head temperature detecting means for detecting the temperature of the recording head, dot counts for each divided area obtained by dividing the scanning area into a plurality of predetermined units, and the recording head Carriage speed determination for determining whether or not the value is larger than a predetermined value corresponding to the temperature information and determining the movement speed of the carriage The carriage is determined according to the scanning direction determined by the carriage direction determining means, the scanning direction changing means for changing the scanning area of the carriage direction determining means and the carriage speed determining means, and the number of divisions determined by the division number determining means. An image forming apparatus comprising: means for reflecting a predetermined value of a speed determining means; and a printing method determined from the determining means.