JP5853517B2 - Image forming apparatus, method, and program - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus, method, and program for forming an image by ejecting ink onto a recording medium.

  2. Description of the Related Art Conventionally, an ink jet image forming apparatus that forms an image by ejecting ink onto a recording medium such as paper has been used. An ink jet image forming apparatus includes a carriage on which a recording head composed of a plurality of ejection nozzles that eject ink is mounted, and the carriage is moved in the main scanning direction to eject ink onto a recording medium. Form an image.

  Such an ink jet image forming apparatus detects the driving state of the recording head when discharging ink, and if the recording head is being driven, executes the next discharging operation after the driving is completed. Thus, a technique for stabilizing the ink ejection operation is known.

  As an example of such a technique, Patent Document 1 determines whether or not a recording head is in a driving state, and generates a driving start signal to drive the recording head when the recording head is not driven. An image forming apparatus is disclosed.

  However, when the image forming apparatus disclosed in Patent Document 1 continuously ejects ink, depending on the speed fluctuation of the main scanning, as shown in FIG. There is a problem that a drive timing error occurs because # is accumulated and the latest waiting times (tw3 and tw4) overlap. Further, the accumulation of the standby time tw # causes an error between the target landing position and the actual ink landing position, resulting in a problem that the image quality deteriorates.

  In order to avoid a drive timing error, it is possible to employ a configuration that resets the overlapped standby time. However, in this configuration, the number of ink droplet ejections may be insufficient by one, and image quality may deteriorate. .

  The present invention has been made in view of the above-described problems of the prior art, and provides an image forming apparatus, method, and program for avoiding accumulation of standby time associated with adjustment of ink droplet ejection timing and preventing deterioration of image quality. It is intended to provide.

  In order to solve the above problems, the image forming apparatus of the present invention includes recording head means for forming an image by ejecting ink onto a recording medium, and there is no delay caused by the ejection operation immediately before the recording head means. In this case, when the first drive waveform for driving the printhead means is output to the printhead means to eject ink and a delay occurs, the second drive waveform having a shorter wavelength than the first drive waveform is generated. The ink is output by outputting to the recording head means. The present invention also provides a method and a program for ejecting ink using drive waveforms having different wavelengths in accordance with the presence or absence of a delay due to the ejection operation immediately before the recording head means.

  By adopting the above configuration requirements, the present invention can prevent a reduction in the detection accuracy of tampering even when there is little information on the overlapping area of adjacent image blocks.

1 is a diagram illustrating a configuration of an image forming apparatus of the present invention. FIG. 3 is a diagram illustrating a functional configuration of an engine control unit provided in the image forming apparatus of the present invention. 6 is a flowchart showing drive control of a main scanning motor provided in the image forming apparatus of the present invention. FIG. 5 is a diagram illustrating a speed change in the main scanning direction of the carriage realized by main scanning control executed by the image forming apparatus of the present invention. FIG. 4 is a diagram illustrating a relationship between a moving speed of a carriage provided in the image forming apparatus of the present invention and a landing position of ink droplets. 7 is a flowchart showing the operation of the drive timing generation unit provided in the image forming apparatus of the present invention. 6 is a flowchart showing the operation of a recording head control unit provided in the image forming apparatus of the present invention. FIG. 8 is a diagram illustrating a relationship between a driving waveform output to the recording head by the recording head control unit of the embodiment illustrated in FIG. 7 and the size of ink droplets ejected by the recording head. 3 is a drive timing chart of a recording head provided in the image forming apparatus of the present invention. 9 is a flowchart showing the operation of a recording head control unit according to another embodiment of the present invention. FIG. 11 is a diagram illustrating a relationship between a driving waveform output to the recording head by the recording head control unit of the embodiment illustrated in FIG. 10 and the size of ink droplets ejected by the recording head. 9 is a flowchart showing an operation of a recording head control unit according to still another embodiment of the present invention. 6 is a drive timing chart of a recording head provided in a conventional image forming apparatus.

  Hereinafter, although this invention is demonstrated with embodiment, this invention is not limited to embodiment mentioned later. FIG. 1 is a diagram showing a configuration of an image forming apparatus of the present invention. The image forming apparatus 1 includes a carriage 2, a guide lot 3, a main scanning motor 4, a pulley 5, an encoder sheet 6, an encoder sensor 7, a sub scanning motor 8, a recording head 9, and an ink discharge nozzle 10. It is comprised including.

  The carriage 2 is held by the guide lot 3 and is connected to the pulley 5. The carriage 2 moves in the main scanning direction when the main scanning motor 4 connected to the pulley 5 rotates. The carriage 2 includes, for example, a recording head 9 that ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K), and ink ejection arranged in the recording head 9. Ink is ejected from the nozzle 10.

  The image forming apparatus 1 ejects ink droplets at necessary positions while moving the carriage 2 in the main scanning direction, whereby an image is printed on a recording medium 11 such as paper with respect to a band having the same width as the length of the nozzle row. Form. When the image formation for one band is completed, the image forming apparatus 1 drives the sub-scanning motor 8 to move the recording medium 11 in the sub-scanning direction, and repeatedly performs the image forming operation for one band. An image can be formed at an arbitrary location on the recording medium 11.

  The carriage 2 also includes an encoder sensor 7. The encoder sensor 7 reads a pattern recorded at equal intervals on the encoder sheet 6 fixed to the casing of the image forming apparatus 1 by moving the carriage 2. Position information can be acquired.

  FIG. 2 is a diagram illustrating a functional configuration of the engine control unit 100 included in the image forming apparatus of the present invention. Hereinafter, the functional configuration of the engine control unit 100 will be described with reference to FIG.

  The engine control unit 100 is a functional unit that performs overall control of image forming processing, and includes a processor 101, a storage unit 102, a host I / F unit 103, an image processing unit 104, and an image data storage unit 105. Consists of.

  The processor 101 is a device that calculates processing executed by the image forming apparatus 1 and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The storage unit 102 includes a nonvolatile computer-readable recording medium such as a non-volatile RAM (NVRAM), a hard disk drive (HDD), or a solid state drive (SSD).

  The image forming apparatus 1 is an assembler, C, C ++, JAVA (registered trademark), JAVASCRIPT (registered) under the control of an operating system (OS) such as WINDOWS (registered trademark) series, UNIX (registered trademark), or LINUX (registered trademark). By developing and executing the program of the present invention described in a program language such as trademark, PERL, RUBY, PYTHON, etc., each functional unit to be described later is realized on the image forming apparatus 1.

  The host I / F unit 103 is an interface that receives print data from the host 300 that provides image data to be printed. When the host I / F unit 103 receives image data from the host 300, the host I / F unit 103 provides the image data to the image processing unit 104.

  The image processing unit 104 converts the image data provided by the host 300 into data suitable for the print mode provided by the image forming apparatus 1. The image processing unit 104 stores the converted image data in the image data storage unit 105.

  The engine control unit 100 includes a main scanning motor driving unit 106, an edge detection unit 107, a main scanning speed detection unit 108, and a drive timing generation unit 109.

  The main scanning motor driving unit 106 is a functional unit that controls the operation of the main scanning motor 4. The main scanning motor driving unit 106 rotates the main scanning motor 4 based on an instruction from the processor 101, so that the carriage 2 moves in the main scanning direction along the guide lot 3.

  The edge detection unit 107 is a functional unit that detects the edge of the pulse signal output from the encoder sensor 7. The encoder sensor 7 reads the pattern of the encoder sheet 6 and outputs a pulse signal corresponding to the moving distance and moving speed of the carriage 2. The edge detection unit 107 detects the edge of the pulse signal and outputs it to the main scanning speed detection unit 108, the drive timing generation unit 109, and the main scanning position detection unit 110.

  The main scanning speed detection unit 108 is a functional unit that detects the speed information of the carriage 2 from the output cycle (that is, the encoder cycle) of the output signal of the edge detection unit 107. The main scanning speed detection unit 108 uses the output period of the pulse signal from the edge detection unit 107 as a relative movement speed of the carriage 2 and the recording head 9 with respect to the recording medium 11 (hereinafter referred to as “carriage speed”). ) Is detected. The main scanning speed detection unit 108 outputs the detected carriage speed to the drive timing generation unit 109.

  The drive timing generation unit 109 is a functional unit that generates an adjustment period until the drive of the recording head 9 is started (hereinafter referred to as “drive timing adjustment period”). The drive timing generation unit 109 uses the pulse signal from the edge detection unit 107 as a trigger, and calculates a drive timing adjustment period based on the carriage speed and preset setting information.

  The setting information is, for example, table information that associates each value of the carriage speed and the drive timing adjustment period, or a relationship that allows the drive timing adjustment period corresponding to the value of the carriage speed to be derived by inputting the carriage speed. And the like. In the setting information, it is assumed that a drive timing adjustment period is set so that ink ejected in the same encoder cycle is deposited at the same position under various carriage speed conditions.

  Further, after the drive timing adjustment period has elapsed, the drive timing generation unit 109 determines whether or not the recording head 9 is performing an ejection operation based on the drive waveform generated by the recording head control unit 113, and the recording When the ejection operation of the head 9 is not performed, the recording head control unit 113 is instructed to start driving the recording head 9. The operation of the drive timing generation unit 109 will be described later.

  Further, the engine control unit 100 includes a main scanning position detection unit 110, a print area determination unit 111, a drive waveform storage unit 112, and a recording head control unit 113.

  The main scanning position detection unit 110 is a functional unit that detects the position of the carriage 2 with respect to the encoder sheet 6 (hereinafter referred to as “carriage position”). The main scanning position detection unit 110 counts the pulse signal from the edge detection unit 107 and calculates the carriage position from the value indicated by the count. The main scanning position detection unit 110 sends the calculated carriage position to the print area determination unit 111.

  The print area determination unit 111 is a functional unit that determines whether or not the carriage 2 is within the print area. The print area determination unit 111 uses the carriage position sent from the main scanning position detection unit 110 to determine whether the carriage position is within the print area and sends the determination result to the recording head control unit 113. send.

  The drive waveform storage unit 112 is a functional unit that stores various drive waveform data for driving the recording head 9. The drive waveform storage unit 112 stores drive waveform data having a normal wavelength and drive waveform data having a wavelength shorter than that of the normal drive waveform.

  The recording head control unit 113 is a functional unit that controls the operation of the recording head 9. The recording head control unit 113 generates a drive waveform for driving the recording head 9 based on the image data stored in the image data storage unit 105 and the drive waveform data stored in the drive waveform storage unit 112. . The recording head control unit 113 determines whether or not the carriage position is within the print region from the determination result of the print region of the print region determination unit 111, and when the carriage position is within the print region, the drive timing generation unit 109 Using the drive instruction as a trigger, a drive waveform is output to the recording head 9, and the recording head 9 is driven to eject ink.

  The recording head control unit 113 includes an ink droplet counting unit (not shown) that is a functional unit that counts the number of ink ejections. Each time the image data is read from the image data storage unit 105, the ink droplet counting unit counts the number of ink droplets necessary for forming the image data for each ink droplet size and type, and holds it in an internal register. To do.

  FIG. 3 is a flowchart showing drive control of the main scanning motor provided in the image forming apparatus of the present invention. Hereinafter, drive control in the main scanning direction will be described with reference to FIG.

  The processing in FIG. 3 starts when the processor 101 receives an instruction signal for image formation from the host 300 via the host I / F unit 103 in step S300. In step S301, the processor 101 sets control parameters that need to be set for each operation, such as the target speed and stop position of the main scanning motor 4, and parameters unique to each part of the engine control unit 100 such as proportional gain and integral gain. To do. In step S <b> 302, the processor 101 outputs a signal instructing the main scanning motor driving unit 106 to drive the main scanning motor 4 to drive the main scanning motor 4.

  In step S303, the processor 101 monitors interruptions from the main scanning speed detection unit 108 and the main scanning position detection unit 110 related to control of the carriage 2 in the main scanning direction at regular intervals. If there is no interrupt (no), the process of step S303 is repeated to wait for an interrupt from these functional units. On the other hand, if there is an interrupt from these functional units (yes), the process branches to step S304.

  In step S <b> 304, the processor 101 acquires the carriage position of the carriage 2 calculated by the main scanning position detection unit 110 from the main scanning position detection unit 110. In step S <b> 305, the processor 101 acquires the carriage speed of the carriage 2 calculated by the main scanning speed detection unit 108 from the main scanning speed detection unit 108.

  In step S306, the processor 101 determines whether or not the carriage position of the carriage 2 acquired in step S304 has reached the stop position. If the carriage position has not reached the stop position (no), the process branches to step S307. In step S307, the processor 101 calculates a speed deviation amount from the current carriage speed. In step S308, the processor 101 applies PI (Proportional Integral) control to the main scanning motor driving unit 106 based on the speed deviation amount calculated in step S307 to change the rotation speed of the main scanning motor 4, and the process proceeds to step S303. return.

  In the present embodiment, in the PI control, the scanning amount of the main scanning motor 4 is calculated using the parameters set in step S301, the distance to the stop position, and the carriage speed, and the rotation speed of the main scanning motor 4 is changed. .

  On the other hand, if it is determined in step S306 that the carriage position of the carriage 2 has reached the stop position (yes), the processor 101 instructs the main scanning motor driving unit 106 to stop driving the main scanning motor 4 in step S309. Is output to stop the main scanning motor 4, and the process ends in step S310.

  FIG. 4 is a diagram showing a speed change in the main scanning direction of the carriage 2 realized by the main scanning control executed by the image forming apparatus of the present invention.

  The vertical axis shown in FIG. 4 indicates the carriage speed, and the higher the speed, the higher the speed. The horizontal axis represents the position in the main scanning direction. Each position in the main scanning direction is divided into four sections: an acceleration section that accelerates to a predetermined speed (target speed), a constant speed section that moves at a constant speed, a deceleration section that decelerates to a predetermined speed, and a stop section. Broadly divided.

  As shown in FIG. 4, the PI control performed by the processor 101 increases the carriage speed by accelerating the rotation speed of the main scanning motor 4 in the acceleration section, and the rotation speed of the main scanning motor 4 in the constant speed section. The carriage 2 moves at a constant speed. Further, in the deceleration section, the carriage speed is reduced by decelerating the rotation speed of the main scanning motor 4, and the carriage 2 is stopped in the stop section. The target speed and each section at each position in the main scanning direction are included in the control parameters.

  Further, the position in the main scanning direction shown in FIG. 4 includes a printing section (section from timing A in the acceleration section to timing B in the deceleration section) in which ink is ejected to form an image on the recording paper. Yes. The print area determination unit 111 determines whether the carriage 2 is within the print area by determining whether the position of the carriage 2 detected by the main scanning position detection unit 110 is within the print section. Note that the setting information indicating the printing section is included in the control parameter.

  FIG. 5 is a diagram showing the relationship between the moving speed of the carriage provided in the image forming apparatus of the present invention and the ink droplet landing position. Hereinafter, the relationship between the carriage speed and the landing position of the ink droplets ejected from the recording head 9 will be described with reference to FIG.

  vC1 and vC2 indicate the carriage speed of the carriage 2, and vC1> vC2. tD1 and tD2 indicate the drive timing adjustment period from the edge line 50 of the encoder sheet 6 until the drive start instruction for the recording head 9 is issued, and tD2> tD1. xJ1 and xJ2 indicate the distance from the edge line 50 of the encoder sheet 6 to the ink droplet landing position, and xJ1 = xJ2 as described later. Further, vJ is the ink droplet ejection speed, and hJ is the distance from the recording head 9 to the recording paper. In FIG. 5, two conditions relating to ink droplet ejection are identified by the numerical value (1 or 2) at the end of each symbol described above.

  First, as a first condition, the speed of the carriage 2 is vC1, the recording head 9 ejects ink droplets at a velocity vJ after the period tD1 has elapsed, and the ink droplets are separated from the edge line 50 of the encoder sheet 6 by a distance xJ1. Suppose that the liquid drops on the position. Further, as a second condition, the speed of the carriage 2 is vC2, the recording head 9 ejects ink droplets at a velocity vJ after a period tD2, and the ink droplets are at a position xJ2 from the edge line 50 of the encoder sheet 6. Suppose that it has landed.

  The droplet landing positions xJ1 and xJ2 under these conditions are obtained by the following formulas 1 and 2.

  The drive timing generation unit 109 controls the print head after the elapse of the drive timing adjustment periods tD1 and tD2 so that the ink landing positions xJ1 and xJ2 are the same (xJ1 = xJ2) based on the values of the carriage speeds vC1 and cC2. The unit 113 is instructed to start driving the recording head 9.

  At this time, assuming that the target landing position is xJ, the drive timing adjustment period tD is calculated by the following Equation 3. Note that vC is an arbitrary carriage speed.

  Further, assuming that the distance between the edges of the encoder sheet 6 is xE and the encoder cycle of the encoder sensor 7 is tE, the carriage speed vC is expressed by the following mathematical formula 4.

  That is, the drive timing adjustment period tD can be expressed as the following formula 5 from the above formula 3 and formula 4. Here, since xJ, xE, hJ, and vJ are constant values in the image forming apparatus 1 and the print mode, the drive timing adjustment period tD is expressed by a linear function of the encoder cycle tE.

  FIG. 6 is a flowchart showing the operation of the drive timing generation unit 109 provided in the image forming apparatus of the present invention. Hereinafter, the operation of the drive timing generation unit 109 will be described with reference to FIG.

  The process in FIG. 6 starts from step S600. In step S601, the drive timing generation unit 109 determines whether or not the pulse signal indicating edge detection is received from the edge detection unit 107, and the pulse signal is not received. In the case (no), the process of step S601 is repeated, and the process waits until the pulse signal is received. On the other hand, when a pulse signal is received from the edge detection unit 107 (yes), the process branches to step S602.

  In step S602, the drive timing generation unit 109 calculates a drive timing adjustment period using the main scanning speed and the setting parameter. In step S603, the drive timing generation unit 109 clears the drive timing adjustment counter. In step S604, the drive timing generation unit 109 refers to the value of the drive timing adjustment counter to determine whether or not the drive timing adjustment period has elapsed. If the drive timing adjustment period has not elapsed (no), The process branches to step S605. In step S605, the drive timing generation unit 109 increments the value of the drive timing adjustment counter, and returns the process to step S604. On the other hand, if the drive timing adjustment period has elapsed (yes), the process branches to step S606.

  In step S606, the drive timing generation unit 109 clears the drive standby counter. In step S <b> 607, the drive timing generation unit 109 determines whether the previous ejection operation of the recording head 9 has been completed. If the ejection operation has not ended (no), the process branches to step S608, and in step S608, the drive timing generation unit 109 increments the value of the drive standby counter, and returns the process to step S607. On the other hand, if the immediately preceding ejection operation of the recording head 9 has been completed (yes), the process branches to step S609. In step S609, the drive timing generation unit 109 instructs the recording head control unit 113 to start driving the recording head 9, and the process returns to step S601.

  In the above-described embodiment, the drive timing adjustment counter and the drive standby counter are separate counters. However, these counters do not operate at the same time. Therefore, the counter may be configured by a common circuit device.

  FIG. 7 is a flowchart showing the operation of the recording head controller 113 provided in the image forming apparatus of the present invention. Hereinafter, the operation of the recording head controller 113 will be described with reference to FIG.

  The processing in FIG. 7 starts from step S700. In step S701, the recording head control unit 113 determines whether or not the driving timing generation unit 109 has received an instruction to start driving the recording head 9, and receives the driving instruction. If not (no), the process of step S701 is repeated. On the other hand, if the drive instruction has been received (yes), the process branches to step S702.

  In step S702, the recording head control unit 113 checks whether the drive standby counter is greater than zero. If the drive standby counter is 0 (no), the process branches to step S703. In step S703, the recording head control unit 113 outputs a normal driving waveform to be described later to the recording head 9, causes ink to be ejected, and returns the process to step S701. When the drive standby counter is 0, the recording head controller 113 outputs a normal driving waveform to the recording head 9 because no delay has occurred due to the previous ejection operation of the recording head 9.

  On the other hand, if the drive standby counter is greater than 0 (yes), the process branches to step S704. In step S704, the recording head control unit 113 outputs a shortened drive waveform, which will be described later, to the recording head 9 to eject ink, and the process returns to step S701. When the drive standby counter is 1 or more, since a delay has occurred due to the previous ejection operation of the recording head 9, the recording head control unit 113 generates a driving waveform having a shorter wavelength than the normal driving waveform. Output to.

  FIG. 8 is a diagram showing the relationship between the drive waveform output to the recording head 9 by the recording head control unit 113 of the embodiment shown in FIG. 7 and the size of the ink droplets ejected by the recording head 9. FIG. 8 shows a common drive waveform Vcom 810 that is a normal drive waveform and a common drive waveform Vcom 820 that is a shortened drive waveform.

  The common drive waveform Vcom 810, which is a normal drive waveform, is composed of four types of drive pulses 812, 814, 816, and 818, and is ejected from each nozzle of the recording head 9 by a combination of these four types of drive pulses. The size of the ink drop is determined.

  When only the drive pulse 812 is output, the recording head 9 finely drives the nozzles to prevent clogging due to drying of the ink droplets. At this time, ink droplets are not ejected. When only the drive pulse 818 is output, the recording head 9 ejects a small drop of ink. When the drive pulse 816 and the drive pulse 818 are output, the recording head 9 ejects medium drops of ink. When the drive pulse 814, the drive pulse 816, and the drive pulse 818 are output, the recording head 9 ejects large drops of ink.

  The common drive waveform Vcom 820, which is a shortened drive waveform, is composed of three types of drive pulses 824, 826, and 828, and ink ejected from each nozzle of the recording head 9 by a combination of these three types of drive pulses. Drop size is determined.

  When only the drive pulse 828 is output, the recording head 9 ejects small droplets of ink. When the drive pulse 826 and the drive pulse 828 are output, the recording head 9 ejects medium drops of ink. When the drive pulse 824, the drive pulse 826, and the drive pulse 828 are output, the recording head 9 ejects large drops of ink.

  The common drive waveform Vcom 820 does not have a waveform corresponding to the drive waveform 812 of the common drive waveform Vcom 810. As described above, the drive waveform 812 is a waveform that is output in order to prevent clogging due to drying of the ink droplets. However, since it is not necessary to finely drive the nozzle for each period of outputting the drive waveform, Omitting the waveform temporarily does not affect the image quality.

  FIG. 9 is a drive timing chart of the recording head 9 provided in the image forming apparatus of the present invention. Hereinafter, the drive timing of the recording head 9 will be described with reference to FIG.

  TE # shown in FIG. 9 indicates a cycle of an encoder signal that is a pulse signal output from the edge detection unit 107. Further, tD #, tDRV #, and tW # indicate a drive timing adjustment period, a head drive period, and a drive standby period, respectively.

  The recording head control unit 113 outputs the common driving waveform Vcom to the recording head 9 in synchronization with the encoder signal supplied from the driving timing generation unit 109. The recording head controller 113 outputs a normal drive waveform 810 when the drive standby period does not occur, and a shortened drive waveform when the drive standby periods tW1, tW2, tW3, and tW4 occur. 820 is output.

  Thus, unlike the prior art, the drive standby period tW # is not accumulated, and the recording head 9 can be driven in synchronization with the drive timing adjustment period tD #, so that the actual ink landing position and target Therefore, it is not necessary to reduce the number of ink droplet ejections by accumulating the drive waiting period tW #, so that the image quality can be maintained.

  FIG. 10 is a flowchart showing the operation of the printhead controller 113 according to another embodiment of the present invention. Hereinafter, the operation of the recording head control unit 113 will be described with reference to FIG.

  The processing in FIG. 10 starts from step S1000. In step S1001, the recording head control unit 113 determines whether or not an instruction to start driving the recording head 9 from the drive timing generation unit 109, and receives the instruction. If not (no), the process of step S1001 is repeated. On the other hand, if the instruction is received (yes), the process branches to step S1002.

  In step S1002, the recording head control unit 113 checks the drive standby counter value C. If the drive standby counter value C is smaller than the threshold value C1, that is, if there is no delay due to the ejection operation immediately before the recording head 9, the process branches to step S1003. If the drive standby counter value C is greater than or equal to the threshold value C1 and smaller than the threshold value C2, the process branches to step S1004. If the drive standby counter value C is greater than or equal to the threshold value C2, the process branches to step S1005.

  The thresholds C1 and C2 are values that can be set by software, and appropriate values can be set according to the print mode and the characteristics of the recording head (for example, temperature during operation).

  In step S1003, the recording head control unit 113 outputs a normal driving waveform to the recording head 9 to eject ink, and the process returns to step S1001. In step S1004, the recording head control unit 113 outputs the shortened driving waveform to the recording head 9 to eject ink, and the process returns to step S1001. In step S1005, the recording head control unit 113 outputs a further shortened drive waveform, which will be described later, to the recording head 9 to eject ink, and the process returns to step S1001. In the present embodiment, the drive waveform supplied to the recording head 9 can be selected according to the presence or absence of the delay caused by the ejection operation immediately before the recording head 9 or the degree of the delay.

  FIG. 11 is a diagram illustrating a relationship between a drive waveform output to the recording head 9 by the recording head control unit 113 according to the embodiment illustrated in FIG. FIG. 11 shows a common drive waveform Vcom 1110 used in the embodiment shown in FIG.

  The common drive waveform Vcom 1110 is a drive waveform obtained by further shortening the shortened drive waveform 820 shown in FIG. 8, and includes two types of drive pulses 1116 and 1118. The size of the ink droplet ejected from each nozzle of the recording head 9 is determined by the combination of these two kinds of drive pulses.

  When only the drive pulse 1118 is output, the recording head 9 ejects small droplets of ink. When the drive pulse 1116 and the drive pulse 1118 are output, the recording head 9 ejects medium drops of ink. In this embodiment, even when large droplets of ink are to be ejected, medium droplets of ink are ejected. As a result, the head driving period can be further shortened, and a margin for the driving timing of the recording head 9 can be further secured.

  FIG. 12 is a flowchart showing the operation of the printhead controller 113 according to still another embodiment of the present invention. Hereinafter, the operation of the recording head control unit 113 will be described with reference to FIG.

  The processing in FIG. 12 starts from step S1200. In step S1201, the recording head control unit 113 determines whether or not an instruction to start driving the recording head 9 from the drive timing generation unit 109, and receives the instruction. If not (no), the process of step S1201 is repeated. On the other hand, if the instruction is received (yes), the process branches to step S1202.

  In step S1202, the recording head control unit 113 confirms the drive standby counter value C. If the drive standby counter value C is smaller than the threshold value C1, that is, if there is no delay due to the ejection operation immediately before the recording head 9, the process branches to step S1203. If the drive standby counter value C is greater than or equal to the threshold value C1 and smaller than the threshold value C2, the process branches to step S1204. If the drive standby counter value C is greater than or equal to the threshold value C2, the process branches to step S1205.

  In step S1203, the printhead controller 113 outputs a normal drive waveform to the printhead 9 to eject ink, and the process returns to step S1201. In step S1204, the recording head control unit 113 outputs the shortened driving waveform to the recording head 9 to eject ink, and the process returns to step S1201.

  In step S1205, the recording head control unit 113 refers to a register in which the size of ink droplets necessary for forming image data is stored, and determines whether it is necessary to eject large droplets of ink. If there is no need to eject large drops of ink (no), the process branches to step S1206. In step S1206, the recording head control unit 113 outputs the shortened driving waveform to the recording head 9 to eject ink, and the process returns to step S1201.

  On the other hand, if it is necessary to eject large drops of ink (yes), the process branches to step S1207. In step S1207, the recording head control unit 113 outputs a further shortened driving waveform to the recording head 9 to eject ink, and the process returns to step S1201. In the present embodiment, it is possible to eject large droplets of ink, and it is possible to secure a drive timing margin as much as possible.

  Although the present embodiment has been described so far, the present invention is not limited to the above-described embodiment, and the constituent elements of the present embodiment are changed or deleted, or the constituent elements of the present embodiment are changed to other configurations. It can be changed within a range that can be conceived by those skilled in the art, such as adding an element, and any aspect is included in the scope of the present invention as long as the effects of the present invention are exhibited.

  In addition, each functional unit of the above-described embodiment may be realized by a semiconductor integrated circuit such as an ASIC having a unique function of the functional unit, or may be stored in the processor 101 and the storage unit 102 of the present invention. You may implement | achieve by cooperation with a program. The program of the present invention can be stored and installed in a device-readable recording medium such as a CD-ROM, MO, flexible disk, EEPROM, EPROM, or the like, and can be installed via a network.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Carriage, 3 ... Guide lot, 4 ... Main scanning motor, 5 ... Pulley, 6 ... Encoder sheet, 7 ... Encoder sensor, 8 ... Sub scanning motor, 9 ... Recording head, 10 ... Ink ejection Nozzle, 11 ... recording medium

JP 2010-214823 A

Claims (3)

An image forming apparatus that forms an image by ejecting ink onto a recording medium,
Recording head means for ejecting ink onto a recording medium;
Recording head control means for outputting a first driving waveform for driving the recording head means or a second driving waveform having a wavelength shorter than that of the first driving waveform to the recording head means to eject ink;
The recording head control means includes
If there is no delay due to the ejection operation immediately before the recording head means, the first drive waveform is output to the recording head means,
When the delay occurs , the second drive waveform or a third drive waveform having a shorter wavelength than the second drive waveform is output to the recording head unit according to the size of the ink droplet to be ejected. An image forming apparatus. A method executed by an image forming apparatus including recording head means for forming an image by ejecting ink onto a recording medium, the method comprising:
A step of outputting a first driving waveform for driving the recording head means to the recording head means to eject ink when there is no delay due to the ejection operation immediately before the recording head means;
A step of outputting a second drive waveform having a wavelength shorter than that of the first drive waveform to the recording head means to eject ink when the delay occurs;
And the step of ejecting the ink comprises:
And outputting the second drive waveform or a third drive waveform having a shorter wavelength than the second drive waveform to the recording head means in accordance with the size of the ink droplet to be ejected . A computer-executable program for causing the image forming apparatus to execute each step according to claim 2 .