JP2013132752A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that it is difficult to reduce the maximum electric power consumption by averaging the power consumption while preventing a decrease in productivity.SOLUTION: With respect to image data which is arranged for each discharge timing, a proportion of the number of nozzles (print ratio) which are simultaneously driven for each discharge timing is calculated from discharge tone data for each discharge timing and the number of discharge nozzles. A control profile of a conveyance speed of a sheet 10 is generated by using a movement average or the like so that it may not exceed the maximum value of the speed specified in the apparatus, by using the stored print ratio. The conveyance of the sheet 10 is controlled on the basis of the generated control profile. The sheet position is detected and timing signals for allowing the nozzles of recording heads 41 to discharge droplets are generated.

Description

  The present invention relates to an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming apparatus using a liquid discharge head (droplet discharge head) for discharging droplets as a recording head An ink jet recording apparatus is known.

  In such an image forming apparatus, the number of nozzles of the recording head tends to increase in order to increase the speed, and power consumption is reduced by changing the number of nozzles that must be driven (discharge droplets) at the same time. Change. On the other hand, there are images output by the image forming device that form dots entirely like images from characters with a small number of dots such as character images, and the recording head is driven and controlled so that maximum driving is possible. There must be.

  Therefore, conventionally, based on the number of ejections counted in a certain bandwidth from the image data, the viscosity of the ink, and a predetermined ejection frequency, the amount of power loss of the drive circuit that occurs when ejecting ink droplets is calculated and calculated When the result exceeds the allowable range, it is known to perform control to insert the dummy data and reduce the discharge frequency (Patent Document 1).

  Further, it is known that phase control of a drive waveform is performed based on image data so that an instantaneous current consumption of each drive circuit is equal to or lower than a predetermined upper limit (Patent Document 2).

JP 2010-179476 A JP 2006-088695 A

  However, as disclosed in Patent Document 1, in the configuration in which dummy data is inserted, the order of data for driving the nozzles is changed by the insertion of dummy data. There is a problem that the printing speed and productivity are unnecessarily lowered, such as the printing mode being switched in band units.

  Further, as disclosed in Patent Document 2, the configuration in which the phase of the driving waveform is controlled to reduce the current consumption for ink ejection driving can reduce the instantaneous current consumption, but the image formation Then, since the nozzles are driven continuously, there is a problem that if the number of nozzles increases, the average power cannot be suppressed only by phase control.

  The present invention has been made in view of the above problems, and an object of the present invention is to average the power consumption of the recording head and suppress the maximum power consumption while suppressing a decrease in productivity.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head having a plurality of nozzles for discharging droplets;
Means for calculating a printing rate of nozzles that are simultaneously driven by the recording head from image data of an image to be printed;
Means for controlling the movement of the recording head or the recording medium at a moving speed of the recording head or a conveyance speed of a recording medium on which an image is formed by the recording head according to the calculated printing rate;
Means for detecting a position of the recording head or the recording medium and generating a discharge timing of liquid droplets from the recording head,
At least, when the printing rate is equal to or higher than a predetermined value, the moving speed of the recording head or the conveyance speed of the recording medium is set slower than when the printing rate is less than the predetermined value.

  According to the present invention, it is possible to average the power consumption of the print head and suppress the maximum power consumption while suppressing a decrease in productivity.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 4 is a cross-sectional explanatory view in the longitudinal direction of the liquid chamber showing an example of a liquid discharge head constituting the recording head of the image forming apparatus. It is sectional explanatory drawing similarly used for description of droplet discharge operation | movement. FIG. 2 is a block explanatory diagram illustrating an overview of a control unit of the image forming apparatus. It is a flowchart with which it uses for description of an example of the discharge control by a control part. FIG. 6 is an explanatory diagram for explaining a sheet conveyance position and droplet discharge timing in the line type image forming apparatus. It is explanatory drawing which shows an example of the image dot with which it uses for description of gradation data, drive waveform electric power, and a printing rate. It is explanatory drawing explaining an example of the drive waveform according to drop size similarly. FIG. 6 is an explanatory diagram for explaining a relationship between an output image and paper conveyance control. It is explanatory drawing with which it uses for description of the arrangement | sequence of each nozzle row in another example, and simultaneous discharge timing similarly.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a schematic explanatory view of the image forming apparatus.

  This image forming apparatus is a full-line type ink jet recording apparatus, and feeds paper 10 that is a recording medium stacked in a paper feeding unit 11 one by one by a paper feeding roller 12 composed of a half-moon roller. Then, the sheet interval adjusting roller 13 corrects the timing between sheets and conveys it to the sheet conveying mechanism 21.

  The paper transport mechanism 21 includes a transport belt 24 that is wound between a driving roller 22 and a driven roller 23. The conveying belt 24 sucks the sheet 10 with suction or electrostatic force and conveys the sheet 10 so as to face the image forming unit 25 by a circular movement.

  The image forming unit 25 performs ink for four colors (black K, cyan C, magenta M, yellow Y) on the sheet (recording medium) 10 conveyed from the upstream side in the sheet conveying direction to the upstream side in the medium conveying direction. ) Full-line type recording heads 41K, 41C, 41M, 41Y (hereinafter referred to as “recording head 41” when the colors are not distinguished) for discharging four colors are disposed. An image is formed on the paper 10 by ejecting. The type and number of colors are not limited to this.

  The recording head 41 may be, for example, one full-line type recording head, or a full-line type for a medium (paper) width by arranging a plurality of short heads in a staggered manner on a base member to form a head array. It may be configured as a recording head. Further, the recording head 141 may be configured by a liquid discharge head unit having a liquid discharge head and a head tank that supplies liquid to the liquid discharge head, or may be configured by a single liquid discharge head.

  The paper 10 on which a required image is formed by the image forming unit 25 is discharged to the paper discharge unit 31.

  Further, a maintenance / recovery mechanism 51 that performs maintenance / recovery of the recording head 41 is disposed on the downstream side of the image forming unit 25 in the sheet conveyance direction. The maintenance / recovery mechanism 51 moves in the direction of the arrow. When performing maintenance / recovery of the recording head 41, the maintenance / recovery mechanism 51 moves below the recording head 41.

  Further, in the transport belt 24, an idle discharge receiver 61 is disposed so as to face each recording head 41 with the transport belt 24 interposed therebetween. An inter-paper gap discharge hole 62 is formed in the transport belt 24. Then, the recording head 41 discharges droplets that do not contribute to image formation at the timing when the empty discharge hole 62 is positioned at the opposite empty discharge receiver 61 between the sheets.

  Further, the drive roller 22 is provided with an encoder wheel 71, and the moving speed and the moving amount of the conveyor belt 24 can be detected by a read signal from an encoder sensor 72 that reads the encoder wheel 71.

  Next, an example of the liquid discharge head constituting the recording head will be described with reference to FIGS. 2 and 3 are cross-sectional explanatory views along the liquid chamber longitudinal direction (direction orthogonal to the nozzle arrangement direction) of the head. Here, a liquid ejection head used in the configuration of a line type recording head having a head array configuration will be described.

  This liquid discharge head is composed of an individual liquid chamber (a pressure chamber, a pressure chamber, and a nozzle plate 104 that joins a flow path plate 101, a vibration plate member 102, and a nozzle plate 103 to discharge a droplet 104 through a through hole 105. It means to include what is called a pressurized liquid chamber, a pressure chamber, an individual flow path, a pressure generation chamber, etc. Hereinafter, simply referred to as “liquid chamber”) 106, a fluid resistance portion for supplying liquid to the liquid chamber 106 107 and the liquid introduction part 108 are formed, respectively, and liquid (ink) is introduced into the liquid introduction part 108 from the common liquid chamber 110 formed in the frame member 117 through the filter 109 formed in the vibration plate member 102. Ink is supplied from the unit 108 to the liquid chamber 106 through the fluid resistance unit 107.

  The flow path plate 101 is formed by laminating metal plates such as SUS to form openings and groove portions such as the through hole 105, the liquid chamber 106, the fluid resistance portion 107, and the liquid introduction portion 108. The vibrating plate member 102 is a wall surface member that forms the wall surface of each liquid chamber 106, the fluid resistance portion 107, the liquid introduction portion 108, and the like, and is a member that forms the filter 109. The flow path plate 101 is not limited to a metal plate such as SUS, and may be formed by anisotropic etching of a silicon substrate.

  Then, a columnar shape as a drive element (actuator means, pressure generating means) that generates energy for pressurizing the ink in the liquid chamber 106 to the surface opposite to the liquid chamber 106 of the vibration plate member 102 and ejecting droplets from the nozzle 104. A laminated piezoelectric member 112 which is an electromechanical conversion element is joined. One end of the piezoelectric member 112 is joined to the base member 113, and the FPC 115 that transmits a driving waveform is connected to the piezoelectric member 112. These elements constitute the piezoelectric actuator 111.

  In this example, the piezoelectric member 112 is used in the d33 mode that expands and contracts in the stacking direction, but it may be in the d31 mode that expands and contracts in the direction orthogonal to the stacking direction.

  In the liquid discharge head configured as described above, for example, as shown in FIG. 2, the piezoelectric member 112 is contracted and the diaphragm member 102 is deformed by lowering the voltage applied to the piezoelectric member 112 from the reference potential Ve. As the volume of the liquid chamber 106 expands, ink flows into the liquid chamber 106, and then, as shown in FIG. 3, the voltage applied to the piezoelectric member 112 is increased to extend the piezoelectric member 112 in the stacking direction. By deforming the vibration plate member 102 in the direction of the nozzle 104 and contracting the volume of the liquid chamber 106, the ink in the liquid chamber 106 is pressurized, and the droplets 301 are ejected from the nozzle 104.

  Then, by returning the voltage applied to the piezoelectric member 112 to the reference potential Ve, the diaphragm member 102 is restored to the initial position, and the liquid chamber 106 expands to generate a negative pressure. The liquid chamber 106 is filled with ink. Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. FIG. 4 is a block diagram of the control unit.

  The control unit 200 includes a CPU 201 that also functions as various means in the present invention that controls the entire image forming apparatus, a ROM 202 that stores programs executed by the CPU 201 and other fixed data, and a RAM 203 that temporarily stores image data and the like. ing.

  Further, an external I / F (interface) 221, a communication control unit 222, a reading control unit 232, a data transfer unit for driving and controlling the recording head 41, a discharge drive control unit 241 including a drive signal generation unit, An IO control unit 251 and the like are provided.

  The control unit 200 is connected to an operation unit 211 serving as a man-machine interface for a user to perform various operations and settings, and a display unit 212 for displaying various information.

  Here, the external I / F 221 exchanges data with the outside such as a host computer, a telephone line, and a memory card. The communication control unit 222 controls communication protocols such as LAN, USB, telephone line, SD card, etc. constituting the external I / F 221. The reading control unit 232 controls reading of the scanner 231 connected to the outside. The data fetched from these external I / F 221 and scanner 231 is temporarily stored in the RAM 203 to perform image processing and the like.

  When performing this image processing, the nozzle position information of the recording head 41 is mechanical information, and is information unique to each apparatus, and the relationship between the image dots is known in advance. Sorting is performed in the order of discharging.

  When the image data rearrangement process is performed, the CPU 201 determines the number of nozzles (simultaneously driven nozzles) and gradation that perform ejection operations at the same timing.

  Further, since each recording head 41 has a plurality of nozzle rows arranged in a staggered manner, it is necessary to buffer at least the ejection image data for the number of lines on the RAM 203.

  The image data rearranged in the discharge order temporarily stored in the RAM 203 is sequentially transferred to the discharge drive control unit 241 via the CPU 201.

  The ejection drive control unit 241 transfers the received image data to the head driver 242 as serial data, and transfers a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 242. In addition to the output, it includes a D / A converter that performs D / A conversion on the drive pulse pattern data stored in the ROM 202, and a drive signal generation unit including a voltage amplifier, a current amplifier, etc. Alternatively, a drive signal composed of a plurality of drive pulses is output to the head driver 242.

  The head driver 242 selectively selects a drive pulse constituting a drive signal provided from the ejection drive control unit 241 based on image data corresponding to one line of the print head 41 input serially. The recording head 41 is driven by being applied to a driving element (for example, the above-described piezoelectric member) that generates energy for discharging the ink. At this time, by selecting a driving pulse constituting the driving signal, for example, dots having different sizes such as a large droplet, a medium droplet, and a small droplet can be sorted.

  The IO control unit 251 includes a sheet feeding unit 261 (such as a sheet feeding roller 12 and a sheet interval adjusting roller 13), a sheet conveying unit 262 (such as the driving roller 22 of the sheet conveying mechanism 21), and a sheet discharging unit 264. In addition, the operation control of the maintenance / recovery unit 271 (each part of the maintenance / recovery mechanism 51) that maintains and recovers the nozzle state of the recording head 41 is also performed. In addition, various sensors 281 for operating the image forming apparatus, various solenoids 282, various clutches 283, and various motors 284 are also controlled and detected. When applied to a serial type image forming apparatus, the operation of the head moving unit 263 is also controlled.

  The ejection drive control unit 241 receives a detection signal (detection pulse) from the encoder sensor 72 and drives the recording head 41 via the head driver 242 at a droplet ejection timing determined by the position of the paper 10. When applied to a serial type image forming apparatus, the recording head is driven at a droplet discharge timing determined by the position of the recording head from a detection signal from an encoder sensor that detects the movement of the head moving unit 263.

  Next, an example of discharge control by the control unit will be described with reference to the flowchart of FIG. Although the present embodiment relates to a line type image forming apparatus, the present invention can also be applied to processing in a serial type image forming apparatus, and therefore, processing in a serial type image forming apparatus will be referred to as appropriate.

  Image data is acquired from an external I / F 221 or the like, and adjustment processing (image mask processing) is performed to insert and delete vertical and horizontal spaces in the acquired image data based on print operation settings such as output paper. )I do.

  Thereafter, in the case of a serial type image forming apparatus, image data processing (main scanning shift processing) is performed when performing interlacing or multi-pass in the sub-scanning direction. In the present embodiment, since it is a line type image forming apparatus, this main scanning shift process is skipped (illustrated by a broken line).

  In the case of a serial type image forming apparatus, since the nozzle rows are arranged in the sub-scanning direction, the image data also needs to be switched between the main scanning direction and the sub-scanning direction. In this embodiment, since it is a line type image forming apparatus, this main / sub rotation process is skipped (illustrated by a broken line).

  Thereafter, the image data is distributed for each nozzle row in accordance with the specifications of the nozzle row of the recording head 41, and the image data distributed for each nozzle row is converted into image data based on the arrangement of each nozzle row (such as a staggered arrangement). Nozzle row delay processing is performed to add delay data to.

  Here, from the image data that has been branched and subjected to nozzle row delay processing and arranged for each discharge timing, the discharge gradation data for each discharge timing, the ratio of the number of nozzles to be driven simultaneously for each discharge timing from the number of discharge nozzles ( (Printing rate) is calculated, and the calculated printing rate is stored in the memory. Here, the sum of all nozzles is calculated as the printing rate by multiplying the nozzles to be driven from the image data arranged at each discharge timing, the number of times of driving, and the driving amount.

  Then, using the stored printing rate, a control profile of the conveyance speed of the paper 10 is generated using a moving average or the like so as not to exceed the maximum speed determined by the apparatus.

  In the case of a serial type image forming apparatus, a control profile of a moving speed (carriage moving speed) of a recording head that is controlled at once (a control unit such as for each band or for each sheet) is used by using a printing rate. It is generated using a moving average or the like so as not to exceed the maximum speed determined by the apparatus.

  At this time, at least when the printing rate is greater than or equal to a predetermined value, a control profile is generated that makes the sheet conveyance speed slower than when the printing rate is less than the predetermined value. Note that it is also possible to generate control profiles having different conveyance speeds in two or more stages according to the printing rate.

  That is, here, the printing rate per unit time and the predetermined value of the printing rate determined for each printing mode are compared and determined, and the moving speed of the recording head or the recording medium before the unit is driven. The conveyance speed is corrected.

  Thereafter, the drive roller 22 of the transport mechanism unit 21 of the paper transport unit 262 is rotationally driven based on the generated control profile to perform transport control of the paper 10. In the case of a serial type image forming apparatus, the movement of the recording head is controlled based on the generated control profile.

  A detection signal (pulse signal) is output from the encoder sensor 72 as the drive roller 22 of the transport mechanism unit 21 of the paper transport unit 262 rotates, and is supplied to the ejection drive control unit 241. In the case of a serial type image forming apparatus, a detection signal (pulse signal) is similarly output from an encoder sensor that reads an encoder sheet arranged in the main scanning direction of a carriage on which a recording head is mounted.

  The ejection drive control unit 241 detects the sheet position from the input pulse count and generates a timing signal for ejecting droplets from the nozzles of the recording head 41 (ejection timing generation).

  On the other hand, the image data adjusted for each ejection timing by performing the nozzle row delay processing is stored in the ejection image data memory. Thereafter, it is determined whether or not there is image data. If there is image data, the ejection image data is transferred to the ejection drive control unit 241.

  The ejection drive control unit 241 drives the recording head 41 with the received image data and the generated ejection timing to eject droplets.

  Next, the sheet conveyance position and the droplet discharge timing in the line type image forming apparatus will be described with reference to FIG.

  Here, for the sake of simplicity, it is assumed that the heads 401 and 402 eject liquid droplets of different colors, and the heads 401 and 402 have nozzles (nozzle rows) 411 and 412. The nozzles (nozzle rows) 411 and 412 of these heads 401 and 402 face the paper 441, and the droplet landing position by the nozzle 411 is the discharge position 421, and the droplet landing position by the nozzle 412 is the discharge position 422. .

  In addition, it is assumed that the sheet 441 is conveyed by the conveying unit in the downstream direction of the conveying direction at each time t0 to t6.

  Here, the dots 431 formed by the nozzles 411 need to be formed at predetermined positions on the paper 441. In other words, since the determined dot position of the paper 441 and the discharge position 421 of the nozzle 411 are overlapped at time t0, the nozzle 411 is driven at time t0 to perform droplet discharge, whereby the desired nozzle 411 performs dot discharge. 431 is formed.

  When the dot 433 is formed by the nozzle 412 at the position adjacent to the dot 431 formed by the nozzle 411, the sheet 441 overlaps with the discharge position 422 of the nozzle 412 at the position adjacent to the time tl5. Then, the nozzle 412 is driven to form.

  Further, by driving the nozzle 411 at time t1 and time t5, the dot 431 formed by the nozzle 411 and the dot 433 formed by the nozzle 412 are formed, so that it is possible to form dots at equal intervals. Become.

  Since the paper transport distance that determines the dot position is determined by the discharge time (timing) and the transport speed, for example, when dots are formed at equal intervals, if the transport speed is constant, the discharge control may be performed at fixed time intervals. Accelerating the time will also shorten the time of the accelerated minute.

  Further, the paper transport position (distance) can be detected by the encoder wheel 71 and the sensor 72 provided in the transport mechanism unit 21, and the discharge timing can be generated according to the transport speed.

  Next, gradation data, drive waveform power, and printing rate will be described with reference to FIGS. FIG. 7 is an explanatory diagram for explaining an example of an image dot, and FIG. 8 is an explanatory diagram for explaining an example of a drive waveform corresponding to the droplet size.

  The individual dots of the output image express the shade of the image by changing the dot size by changing the droplet discharge amount based on the gradation data of each pixel. In the example of FIG. 7, the four-value expression of the no-drop dot 501, the small-dot dot 502, the medium-drop dot 503, and the large-drop dot 504 is used.

  These dots (droplets) of each size can be formed by varying the drive waveform applied to the pressure generating means (the piezoelectric member 112 described above). For example, FIG. 8A shows a case where no driving is performed, FIG. 8B shows a small droplet driving waveform for discharging a small droplet, FIG. 8C shows a middle droplet driving waveform for discharging a medium droplet, and FIG. (D) is an example of a large droplet driving waveform for discharging a large droplet. Here, a small droplet driving waveform and a medium droplet driving waveform are generated using a part of the large droplet driving waveform.

  As described above, since the number of times of driving (the number of times of vibration) of the piezoelectric member corresponding to the droplets of each droplet size is determined, the power consumed for ejection driving can be obtained according to the gradation data of the pixels.

  Next, the relationship between the output image and the sheet conveyance control will be described with reference to the explanatory diagram of FIG. In this example, a sheet position and conveyance control (speed) when an image is formed by a head 601 having one nozzle row 611 are shown.

  Character images 622 and photographic images 624 are formed by driving individual nozzles constituting the nozzle array 611 sequentially from the upstream side to the downstream side in the conveyance direction of the paper 621 based on the image data.

  At this time, as shown in FIG. 9A, on the paper 621, there are a character information portion (character image) 622 on the paper, a white paper portion 623 on the paper, and a photo information portion (photo image) 624 on the paper. Exist, and the amount of ink ejected is different.

  Here, the character information portion 622 with sparse dots has a low printing rate, the blank paper portion 623 without any dots has a printing rate close to zero, and the photo information portion 624 filled with dots has a printing rate. Get higher.

  This is shown in FIG. 9B as a relationship between the paper position and the printing rate.

  Therefore, from the relationship between the paper position and the printing rate, as shown in FIG. 9C, the region where the printing rate is high reduces the conveying speed, and the region where the printing rate is low has a conveying speed higher than the region where the printing rate is high. Control the conveyance to lower.

  Since the conveyance speed is reduced in the area where the printing rate is high, the ejection drive cycle is delayed according to the conveyance speed. That is, the droplet ejection timing cycle is delayed.

  As a result, the maximum power consumption caused by the droplet ejection drive can be suppressed without reducing the productivity, and the power consumption of the print head can be averaged and the maximum power consumption can be suppressed while suppressing the decrease in productivity. it can.

  In other words, since the printing rate by the nozzles that are simultaneously driven for ejection can be calculated from the image data including the gradation data before ejection driving, it is possible to control the speed of head movement or paper conveyance by predicting several lines ahead. The timing of the ejection drive of the recording head can be feedback controlled by an encoder signal for head movement or paper conveyance so that the ejection drive can be performed at a desired dot position, so even if the speed of head movement or paper conveyance is changed. By keeping the printing rate per time constant without changing the resolution of the output image, it is possible to average the power consumption required for ejection driving without unnecessarily reducing productivity.

  Next, the arrangement of the nozzle rows and the simultaneous ejection timing will be described with reference to FIG. Here, an example in which a line type recording head is configured by arranging a plurality of heads in a staggered manner will be described.

  That is, the recording head for one line is configured by arranging four heads 701 to 704 in a staggered manner in the paper width direction. Each of the heads 701 to 704 has a nozzle row 711 to 714, respectively.

  Here, since the nozzle row 711, the nozzle row 712, the nozzle row 713, and the nozzle row 714 of each head 701 to 704 are in a staggered arrangement, the image data input to the heads used for ejection is also input with shifted timing. There is a need to.

  The character information portion 722, the blank paper portion 723, and the photographic information portion 724 are images that are arranged as output images, but the nozzle arrangement is considered for the ejection timing of each nozzle of the nozzle rows 711 to 713 of each head 701 to 704. Thus, it is necessary to control the droplet discharge timing.

  That is, since the ejection timing differs depending on the nozzle arrangement, the relationship between the paper position and the printing rate and the relationship between the paper position and the conveyance speed (conveyance control profile) are different from the example shown in FIG. However, since the head arrangement and the nozzle arrangement are uniquely determined for each apparatus, it is not necessary to change them according to the image to be printed and the print mode.

  In addition, although an example in which one head has one nozzle row is shown here, a head having a plurality of nozzle rows can be dealt with by dividing the image data into a plurality of pieces and adjusting the timing. Can do.

  In this way, when the line-type recording heads are arranged in a staggered manner, image data that is larger than the line width is buffered, and printing of nozzles that are simultaneously driven several lines before the droplet ejection timing of the corresponding image data is performed. It is preferable to calculate a rate and generate a control profile for head movement or paper conveyance according to the printing rate.

  In the present application, the “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, etc., and means a material to which ink droplets or other liquids can be attached. , Recording media, recording paper, recording paper, and the like. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “Formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply causing a droplet to land on the medium). ) Also means.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

10 Recording medium (paper)
21 Transport Mechanism 25 Image Forming Unit 41 Recording Head (Liquid Discharge Head)
200 Control Unit 241 Discharge Drive Control Unit

Claims (3)

A recording head having a plurality of nozzles for discharging droplets;
Means for calculating a printing rate of nozzles that are simultaneously driven by the recording head from image data of an image to be printed;
Means for controlling the movement of the recording head or the recording medium at a moving speed of the recording head or a conveyance speed of a recording medium on which an image is formed by the recording head according to the calculated printing rate;
Means for detecting a position of the recording head or the recording medium and generating a discharge timing of liquid droplets from the recording head,
At least when the printing rate is equal to or higher than a predetermined value, the moving speed of the recording head or the conveyance speed of the recording medium is made slower than when the printing rate is less than a predetermined value. apparatus.   2. An image forming apparatus according to claim 1, wherein a total of all nozzles is calculated as a printing rate by multiplying the nozzles to be driven from the image data arranged at each discharge timing, the number of times of driving, and the driving amount. apparatus.   The printing rate per unit time is compared with a predetermined value of the printing rate determined for each printing mode of the image forming apparatus, and the moving speed of the recording head or the target coverage is measured before the nozzle is driven. The image forming apparatus according to claim 1, wherein the conveyance speed of the recording medium is corrected.

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