JP2016221927A - Image formation apparatus, image processing method and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive waveform adjustment method which suppresses deterioration in image quality generated due to the fact that a drive voltage differs depending on the nozzle number to be driven.SOLUTION: An image formation apparatus comprises: pattern formation means which forms an adjustment pattern on a recording medium by driving a recording head; and correction means which corrects a drive waveform in accordance with correction information based on the adjustment pattern. The adjustment pattern includes a reference line A and an adjustment line extending in a sub-scanning direction. The pattern formation means simultaneously drives the first number of nozzles that is the drive nozzle number with the maximum droplet discharge speed and droplet discharge amount among the plurality of nozzles at the time of reference line formation, and simultaneously drives the second number of nozzles different from the first number at the time of adjustment line formation.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image forming apparatus, a control method, and a program.

There is known an image forming apparatus that ejects liquid droplets while scanning a carriage mounted with a recording head on which a plurality of nozzles are formed in the main scanning direction. Various types of image forming apparatuses such as a thermal jet type ink jet recording apparatus and a piezoelectric type ink jet recording apparatus are known.
A piezoelectric ink jet recording apparatus includes a recording head for discharging ink, an ink chamber provided in the recording head for storing ink, a nozzle hole for discharging ink stored in the ink chamber, and an ink And a piezoelectric element for deforming the chamber. A driving voltage is applied to the piezoelectric element from the pulse voltage generating means via a harness. Then, the ink chamber is deformed according to the applied drive voltage, and droplets are ejected from the ink chamber by the deformation.

However, an overshoot or undershoot of the drive voltage occurs due to the inductance component of the harness, and the drive voltage varies depending on the number of nozzles to be driven. If the driving voltage is different, there is a problem that the speed at which the droplets are ejected, the size of the droplets, and the like change, and the image quality deteriorates.
In order to solve this problem, a technique is disclosed in which the output timing of the drive waveform is controlled in accordance with the number of simultaneous ejection nozzles to prevent deterioration in image quality due to fluctuations in the ink ejection speed (Patent Document 1).

However, the method disclosed in Patent Document 1 can prevent image deterioration due to fluctuations in the ink ejection speed, but cannot correct the size of the droplets. That is, the problem that the image quality deteriorates due to the inability to correct the droplet size remains.
Therefore, an object of the present invention is to prevent deterioration of image quality.

  In order to solve the above-described problems, an image forming apparatus of the present invention drives a recording head having a plurality of nozzles arranged in the sub-scanning direction by a driving waveform generated according to image data, and applies a liquid to a recording medium. An image forming apparatus for discharging droplets, wherein the recording head drives the recording head to form an adjustment pattern on the recording medium, and the correction means corrects the drive waveform according to correction information based on the adjustment pattern. The adjustment pattern includes a reference line extending along the sub-scanning direction and an adjustment line, and the pattern forming unit includes a first number of nozzles among the plurality of nozzles when the reference line is formed. A second number of nozzles different from the first number are driven simultaneously when the adjustment lines are formed.

  According to the present invention, it is possible to prevent deterioration of image quality.

1 is a diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a recording head. 2 is a functional block diagram of the image forming apparatus. FIG. It is a figure explaining the relationship between a droplet discharge speed or a droplet discharge amount, and the number of nozzles driven simultaneously. 2 is a functional block diagram of an image forming apparatus related to drive waveform correction. FIG. It is a figure explaining the method of correct | amending a drive waveform. It is a figure explaining the detail of the test pattern in one Embodiment of this invention. It is a figure explaining the whole test pattern in one embodiment of the present invention. It is a figure explaining the relationship between the drive waveform magnification | multiplying_factor obtained using the test pattern in one Embodiment of this invention, and the number of simultaneous drive nozzles. It is a figure explaining a test pattern when a standard line is set to 192ch. It is a figure explaining the optical sensor in one Embodiment of this invention. It is a figure explaining the area | region which reads a test pattern with an optical sensor. It is a figure explaining the relationship between the density | concentration which read the test pattern of 100ch-30ch with the optical sensor, and drive waveform magnification.

Embodiment 1
FIG. 1A is a diagram illustrating an overall configuration of the image forming apparatus 100 according to the first embodiment, and FIG. 1B is a diagram illustrating a detailed configuration of the image forming apparatus 100 as viewed from above. The image forming apparatus 100 is a serial type liquid ejection type image forming apparatus. The image forming apparatus 100 is provided with a main guide rod 1 and a sub guide rod 2 therein. A carriage 5 is supported on the main guide rod 1 and the sub guide rod 2.

In the image forming apparatus 100, an endless belt-like timing belt 6 is disposed along the main guide rod 1. The timing belt 6 is wound around a driving pulley 7 and a driven pulley 8. The driving pulley 7 is driven by the rotation of the main scanning motor 12 connected to the driving pulley 7, and the timing belt 6 rotates (runs) by the driving of the driving pulley 7.
As shown in FIG. 1B, the carriage 5 is connected to the timing belt 6 by a belt holding portion 9. By connecting the carriage 5 and the timing belt 6, the timing belt 6 is rotated in the forward and reverse directions, whereby the carriage 5 is reciprocated in the main scanning direction (X direction in the figure).
The carriage 5 has a plurality of recording heads 21, and each recording head 21 ejects at least one ink of yellow (Y), magenta (M), cyan (C), and black (K). Can do. Further, an optical sensor 30 is attached to the carriage 5, and the optical sensor 30 detects the ink or the recording medium P ejected onto the recording medium P. Details of the optical sensor 30 will be described later.

Further, the carriage 5 has an encoder sensor 10, and the encoder sensor 10 reads an encoder sheet 11 installed in parallel to the main guide rod 1 of the image forming apparatus 100. Based on the reading of the encoder sensor 10, the position of the carriage 5 in the main scanning direction is detected. Based on the detected position, the movement of the carriage 5 is controlled.
The image forming apparatus 100 also has a sub-scanning motor 13 (see FIG. 3), and intermittently conveys the recording medium P fed from the paper feeding unit using the sub-scanning motor 13. The image forming apparatus 100 intermittently conveys the recording medium P in the sub-scanning direction, and moves the carriage 5 in the main scanning direction while the conveyance of the recording medium P in the sub-scanning direction is stopped. The image forming apparatus 100 can form an image on the recording medium P by discharging droplets from the recording head 21 as the carriage 5 moves.
Further, the image forming apparatus 100 has a maintenance mechanism 3 for maintaining the quality of the image. The maintenance mechanism 3 maintains the image quality, for example, by cleaning the ejection surface of the recording head 21 or ejecting unnecessary liquid from the recording head 21.
Although the serial type ink jet recording apparatus has been described with reference to FIG. 1, the ink jet recording method is not limited to this. For example, a line head type ink jet recording apparatus in which the recording heads 21 are arranged in a staggered manner (in a staggered manner) in the main scanning direction may be used.

  FIG. 2 is a diagram illustrating the surface of the recording head 21 that faces the recording medium. The recording head 21 has a plurality of nozzles 22 arranged in the sub-scanning direction. The plurality of nozzles 22 form a nozzle row in the sub-scanning direction (Y direction in the figure). In the present embodiment, the recording head 21 has two nozzle arrays, n1, n3, n5,... N189, n191, and nozzle arrays composed of n2, n4, n6,. It has two nozzle rows.

FIG. 3 is a functional block diagram relating to control of the image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 includes a control unit 31, a carriage 5, a main scanning motor 12, a sub scanning motor 13, and an operation display unit 14.
The control unit 31 includes a main control unit 32, a head drive control unit 33, a main scanning drive control unit 34, and a sub-scanning drive control unit 35. The main control unit 32 includes a CPU 321 (Central Processing Unit), a ROM 322 (Read Only Memory), a RAM 323 (Random Access Memory), an NVRAM 324 (Non-Volatile Random Access Memory), an ASIC 325 (Application Specific Integrated Circuit), and a waveform correction unit 326. Have.

The head drive control unit 33 is connected to the main control unit 32 and the recording head 21. Further, the head drive control unit 33 has a head driver such as an ASIC for head data generation array conversion. The head drive control unit 33 applies a predetermined drive waveform to the recording head 21 based on commands from the head driver and the main control unit 32. A mask signal for masking a predetermined drive waveform is also transmitted from the main control unit 32 to the head drive control unit 33, and the size of droplets ejected from the recording head 21 can be controlled by the mask signal.
The main scanning drive control unit 34 is connected to the main scanning motor 12 and the main control unit 32. The main scanning drive control unit 34 drives the main scanning motor 12 based on a command from the main control unit 32. The sub-scanning drive control unit 35 is connected to the sub-scanning motor 13 and the main control unit 32, and drives the sub-scanning motor 13 based on a command from the main control unit 32.
The operation display unit 14 (accepting means) includes a numeric keypad, a display, and the like, and accepts input from the user. Information based on the input from the user is input to the main control unit 32.

FIG. 4 is a diagram for explaining the relationship between the number of drive nozzles and the landing position deviation of the droplets. The horizontal axis of the graph of FIG. 4 indicates the number of nozzles 22 that are simultaneously driven in the recording head 21 shown in FIG. 2, and the vertical axis of the graph of FIG. 4 indicates the droplet discharge speed Vj. FIG. 4 shows the relationship between the number of nozzles driven simultaneously and the droplet discharge speed Vj, but the number of nozzles driven simultaneously and the droplet discharge amount Mj also have the same relationship as the graph shown in FIG. can get. Further, it is known that the droplet discharge speed Vj and the droplet discharge amount Mj are substantially in a proportional relationship.
FIG. 4 shows that the droplet discharge speed Vj or the droplet discharge amount Mj changes depending on the number of nozzles driven simultaneously. This is because the manner of occurrence of overshoot and undershoot of the drive waveform applied to the recording head 21 differs depending on the number of nozzles driven simultaneously. If the overshoot and undershoot of the drive waveform are different, the voltage amplitude of the drive waveform is affected, and the droplet discharge speed Vj and the droplet discharge amount Mj change. That is, when the number of nozzles that are driven simultaneously changes, the droplet discharge speed Vj and the droplet discharge amount Mj change. In FIG. 4, when the number of nozzles driven simultaneously is “100”, the droplet discharge speed Vj and the droplet discharge amount Mj are the largest.

Although FIG. 4 illustrates the case where the recording head 21 has 192 drive nozzles, the number of drive nozzles included in the recording head is not limited to this. Further, the number of drive nozzles at which the droplet discharge speed Vj and the droplet discharge amount Mj are the largest may vary depending on the image forming apparatus. In that case, the largest number of drive nozzles is obtained by measuring the droplet discharge speed and the droplet discharge amount in advance.
In this embodiment, the magnification of the drive waveform is changed in order to correct the droplet discharge speed and the droplet discharge amount based on the number of nozzles that are driven simultaneously. In the present embodiment, an example in which the drive waveform is corrected by the waveform correction unit 326 (correction unit) illustrated in FIG. 3 will be described.

FIG. 5 is a functional block diagram of the image forming apparatus related to drive waveform correction. The waveform correction unit 326 includes an image data output unit 41, a pixel count unit 42, a drive waveform correction value calculation unit 43, a drive waveform table 44, and a drive waveform correction unit 45. A head drive control unit 33 exists between the waveform correction unit 326 and the recording head 21, but the drive control unit 33 is not shown in FIG.
The image data output unit 41 specifies image data to be ejected in the next cycle from image data input from the outside, and outputs the specified image data to the pixel count unit 42 and the recording head 21. The image data output unit 41 outputs image data at a predetermined cycle, for example, every scan.
The pixel counting unit 42 counts the number of nozzles that are driven simultaneously based on the image data input from the image data output unit 41. After counting the number of nozzles that are driven simultaneously, the number of nozzles that are driven simultaneously is output to the drive waveform correction value calculation unit 43.

The relationship between the drive waveform correction value and the number of drive nozzles is stored in advance in the internal memory of the waveform correction unit 326 or the drive waveform correction table of the NVRAM 324. Further, a test pattern is stored in the RAM 324, and when the test pattern is printed, the head drive control unit 33 reads the data from the test pattern, transfers it to the recording head 21, and performs printing. That is, the RAM 324 and the head drive control unit 33 function as a pattern forming unit that drives the recording head 21 to form a test pattern on the recording medium P. The drive waveform correction value calculation unit 43 acquires a drive waveform correction value based on the number of drive nozzles input from the pixel count unit 42 and the internal memory of the waveform correction unit 326 or the drive waveform correction table of the NVRAM 324. Details of the drive waveform correction value will be described later.
The correction value calculated by the drive waveform correction value calculation unit 43 and the drive waveform stored in the drive waveform table 44 are input to the drive waveform correction unit 45. The drive waveform correction unit 45 performs correction processing, and the corrected drive waveform is output to the recording head 21.

FIG. 6 is a diagram for explaining the correction of the drive waveform performed by the waveform correction unit 326. FIG. 6A is a drive waveform stored in the drive waveform table 44 and is a drive waveform before correction by the waveform correction unit 326. FIG. 6B shows a drive waveform after correction by the waveform correction unit 326.
The drive waveform is corrected except for a portion having a constant voltage value called an intermediate potential. FIG. 6 illustrates the case where the drive waveform correction value is 1.2, and the amplitude value other than the intermediate potential is multiplied by 1.2. By correcting the amplitude other than the intermediate potential, in other words, the amplitude of the drive waveform centered on the intermediate potential, the droplet discharge speed Vj and the droplet discharge amount Mj can be changed.

FIG. 7 is a diagram for explaining the test pattern of the present embodiment. FIG. 7A is a diagram for explaining a reference pattern of the test patterns, and FIGS. 7B and 7C are diagrams for explaining an adjustment pattern of the test patterns. In the present embodiment, the case where the number of simultaneously driven nozzles is 100 is the peak of the droplet discharge speed Vj and the droplet discharge amount Mj will be described. The unit of the number of nozzles 22 that are driven simultaneously is represented as “ch (channel)”. For example, when the number of nozzles driven simultaneously is “100”, it is called “100 ch”.
In the present embodiment, the reference line that ejects ink at 100 ch where the droplet ejection speed and the droplet ejection amount are maximized, and the droplet ejection speed and the droplet ejection amount are smaller than when ink is ejected at 100 ch. Based on the result of reading the adjustment line that ejects ink with the number of channels, the droplet ejection speed and the droplet ejection amount of the adjustment line are corrected.

  As shown in FIG. 7A, the control unit 31 uses only 100 ch, which is the number of drive nozzles that maximizes the droplet discharge speed Vj and the droplet discharge amount Mj, and corrects the reference pattern without correcting the drive waveform. Is printed on the recording head 21.

Further, as shown in FIG. 7B, an adjustment pattern is formed by repeating reference lines printed in odd-numbered columns in the main scanning direction and adjustment lines printed in even-numbered columns in the main scanning direction. Is done. The reference line is printed in 100 ch. The adjustment line is formed with a number of channels other than 100. Two types of adjustment patterns are used as the adjustment pattern: an adjustment pattern in which the drive waveform of the adjustment line is corrected by the drive waveform correction value, and an adjustment pattern in which the drive waveform of the adjustment line is not corrected by the drive waveform correction value. FIG. 7B shows an adjustment pattern in which the reference line is formed by 100 ch and the adjustment line is formed by 50 ch, the drive waveform correction value is “1”, that is, the drive waveform is not corrected, and FIG. Shows an adjustment pattern in which the reference line is formed by 100 ch and the adjustment line is formed by 50 ch, and the drive waveform correction value is “1.1”, that is, the drive waveform is corrected.
Since the adjustment line in FIG. 7B is 50 ch, the droplet discharge speed Vj is slower than 100 ch. Since the droplet discharge speed Vj is slower than 100 ch, the discharge position of the adjustment line in FIG. 7B is shifted to the downstream side in the main scanning direction (right side in FIG. 7) rather than the adjustment line in FIG. Further, not only the droplet discharge speed Vj is slow, but also the droplet discharge amount Mj is smaller for 50 ch than for 100 ch. As described above, the density of the adjustment pattern in FIG. 7B is lower than that of the reference pattern in FIG.

  On the other hand, the adjustment line in FIG. 7C is 50 ch as in FIG. 7B, but because the drive waveform is corrected, the droplet discharge speed Vj is faster than in FIG. Mj is also large. For this reason, the reference pattern in FIG. 7A and the adjustment pattern in FIG. 7C have the same density.

  In the example of FIG. 7, the example of unidirectional printing in which the reference pattern and the adjustment pattern are printed by one scan has been described, but the number of scans is not limited to this. The reference pattern and the adjustment pattern may be formed by bidirectional printing in which the reference line is printed in the forward path and the adjustment line is printed in the backward path. Further, the adjustment line may be printed on the forward path and the reference line may be printed on the backward path. When the adjustment pattern is printed so that the reference line is printed in the forward path and the adjustment line is printed in the backward path, the ejection position of the adjustment line is shifted upstream in the main scanning direction (left side in FIG. 7). However, even if the discharge position of the adjustment pattern printed by bidirectional printing is shifted to the left, the displacement amount of the discharge position is the same as that of the adjustment pattern printed by one-way printing. Since the density is the same as in the case of unidirectional printing, either unidirectional printing or bidirectional printing may be performed.

  FIG. 8 is a diagram for explaining an adjustment chart including the reference pattern of FIG. 7A and the adjustment patterns of FIGS. 7B and 7C. The adjustment chart illustrated in FIG. 8 is obtained by forming a reference pattern and an adjustment pattern on a medium such as recording paper. The pattern A shown in FIG. 8 is a reference pattern, and all the patterns other than the pattern A are adjustment patterns. As shown in FIG. 8, the adjustment pattern is formed in a plurality of lines from the top to the bottom of the recording paper. Each adjustment pattern is formed so that the number of channels of the reference line is the same (100 ch) and the number of channels of the adjustment line is different for each row (30 ch to 192 ch). Further, adjustment patterns are formed so that the drive waveform magnification increases from the left side to the right side of FIG. In FIG. 8, adjustment patterns of drive waveform magnifications “1” (no correction), “1.05”, “1.1”, “1.15”, and “1.2” are formed. Further, as described above, the reference pattern A is also formed.

  The user views the adjustment chart discharged onto the recording paper and inputs an adjustment pattern having the same density as the reference pattern from the operation display unit 14 for each drive channel. In the case of the example of FIG. 8, in 100ch-30ch, the density of the adjustment pattern having the drive waveform magnification of 1.15 and the reference pattern are equal. In 100ch-50ch, the density of the adjustment pattern having the driving waveform magnification of 1.1 and the reference pattern are equal, and in 100ch-150ch, the density of the adjustment pattern having the driving waveform magnification of 1.1 is equal to the density of the reference pattern. In 192ch, the density of the adjustment pattern having the drive waveform magnification of 1.15 is equal to that of the reference pattern. Therefore, the user selects “1.15” in 100ch-30ch, selects “1.1” in 100ch-50ch, selects “1.1” in 100ch-150ch, and “1. 15 ”is selected. The control unit 31 stores the adjustment pattern selected by the user in the RAM 323. By selecting an adjustment pattern having the same density as the reference pattern, the user can determine a drive waveform correction value for each number of nozzles that are driven simultaneously. That is, the information on the adjustment pattern selected by the user becomes correction information for calculating or determining the correction value.

  If an adjustment pattern is printed in units of 1ch and the user selects an adjustment pattern having the same density as the reference pattern in units of 1ch, an accurate drive waveform correction value can be obtained for each channel. Ink for forming an adjustment pattern The amount becomes enormous. Therefore, FIG. 8 does not record patterns for all the channels, but uses an adjustment chart output only with a representative number of channels.

  When the user selects an appropriate adjustment pattern for each number of channels of a plurality of adjustment lines shown in FIG. 8, a graph as shown in FIG. 9 can be created. In the graph of FIG. 9, the drive waveform correction values between the four types of channels shown in FIG. 8 are complemented with linear functions. By complementing the drive waveform correction value in this way, it is not necessary to output to the adjustment chart for obtaining the drive waveform correction value for channels other than the representative number of channels. Therefore, the ink amount for forming the adjustment pattern can be reduced. In the embodiment of FIG. 9, the drive waveform correction value between channels is complemented by a linear function, but the complement method is not limited to this. For example, it is possible to complement using an approximate curve.

  By correcting the drive waveform for each number of nozzles that are driven simultaneously as in the present embodiment, the droplet discharge speed Vj and the droplet discharge amount Mj can be made substantially constant, and the image quality can be maintained without shifting the discharge position. Can be improved. Although the reference is 100 ch, this is not restrictive, and 192 ch or the like may be used as a reference. However, as shown in FIG. 10, there are cases where it is difficult to select the concentration peak because 100 ch has a larger droplet discharge amount than 192 ch. Therefore, it is desirable that the reference channel number be the number of simultaneously driven nozzles at which the droplet discharge speed and the droplet discharge amount peak.

[Embodiment 2]
In the first embodiment, the example in which the adjustment chart is output, the user selects the adjustment pattern having the same density as the reference pattern, and the drive waveform is corrected based on the user's selection has been described. In the second embodiment, an example in which an adjustment pattern having the same density is selected using the optical sensor 30 instead of the user's selection will be described. By using the optical sensor 30, the accuracy of selecting an adjustment pattern having the same density as compared with visual observation by the user is improved.
The optical sensor 30 is mounted on the carriage 5 as shown in FIG. Therefore, the optical sensor 30 is scanned in the main scanning direction along with the scanning of the carriage 5. The optical sensor 30 detects the density of the reference pattern and the adjustment pattern while being scanned in the main scanning direction.

  The user instructs to start reading the adjustment pattern using the operation display unit 14 or the like. Then, the CPU 321 scans the carriage in the main scanning direction and discharges droplets from the nozzles to output an adjustment chart on the recording paper. As shown in FIG. 1B, since the optical sensor is located downstream of the recording head in the sub-scanning direction, the recording sheet is conveyed in the sub-scanning direction after an adjustment chart is formed on the recording sheet. Sometimes the recorded adjustment chart is located directly below the optical sensor. The density of the adjustment chart can be detected by positioning the adjustment chart directly below the optical sensor. The detection timing of the adjustment chart is not limited to this, and the density of the adjustment chart may be detected while the recording paper is conveyed by rewinding the recording paper upstream after printing the entire adjustment chart.

  FIG. 11 is a diagram showing a configuration for the optical sensor 30 to detect a test pattern. The optical sensor 30 includes a light emitting element 51 (light emitting part) and a light receiving element 52 (light receiving part). The light emitting element 51 emits light toward the recording medium P, and the light receiving element 52 receives the light reflected by the recording medium P. The light receiving element receives the regular reflection light reflected by the recording medium P. The light emitting element 51 uses a light source that projects visible light such as an LED.

  The CPU 321 sets a PWM value for driving the light emitting element 51 in the light emission control unit 511. The light emission control unit 511 causes the PWM signal generation unit to generate a PWM signal corresponding to the set PWM value. The PWM signal created by the PWM signal creating means is output to the smoothing circuit 512 and smoothed by the smoothing circuit 512. By outputting the smoothed PWM signal to the drive circuit 513, the light emitting element 51 is driven to emit light. The light emitted from the light emitting element 51 is applied to a region where the reference pattern and the adjustment pattern of the adjustment chart are printed overlapping in the main scanning direction as shown in FIG.

  Then, the reflected light reflected on the adjustment chart on the recording medium enters the light receiving element 52. The light receiving element 52 outputs an intensity signal of the reflected light to the photoelectric conversion circuit 521. The photoelectric conversion circuit 521 photoelectrically converts the intensity signal of the input reflected light and outputs the photoelectrically converted signal to the low-pass filter circuit 522. The low-pass filter circuit 522 removes high-frequency noise from the photoelectrically converted signal. After the noise of the signal photoelectrically converted by the low-pass filter circuit 522 is removed, the noise-removed signal is output from the low-pass filter circuit 522 to the A / D conversion circuit 523. The signal input to the A / D conversion circuit 523 is A / D converted and output to the signal processing circuit (waveform correction unit 326). The signal processing circuit stores detection voltage data, which is a digital value of the detection voltage subjected to A / D conversion, in the RAM 323. Such density detection is performed for all patterns in the adjustment chart, and the detection voltage data is stored in the RAM 323 for each number of nozzles to be driven simultaneously and the drive waveform magnification.

FIG. 13 is a graph showing the relationship between the density obtained by reading the 100ch-30ch adjustment chart with the optical sensor 30 and the drive waveform magnification. From FIG. 13, in the case of 100ch-30ch, the density becomes maximum when the drive waveform magnification is 1.15. The portion having the maximum density is stored in the NVRAM 324 as a correction value. Here, density information obtained by reading the adjustment chart with the optical sensor 30 is correction information for calculating or determining a correction value. Since the method for correcting the drive waveform using the stored correction value is the same as in the first embodiment, description thereof is omitted.
In this way, by detecting the drive waveform magnification at which the density is maximized using the optical sensor 30, the droplet discharge speed Vj and the droplet discharge amount Mj are controlled, and the image quality can be improved.
The density of the reference pattern may be stored in the ROM 322 in advance, and a value closest to the density of the reference pattern may be used as the correction value. In this case, printing of the reference pattern becomes unnecessary, and ink consumption can be suppressed.

Up to this point, the present invention has been described based on each of the above embodiments. However, the functions of the image forming apparatus according to the above embodiments are the same as the processing procedures described above for the image processing according to each of the above embodiments. It can be realized by executing on a computer as a program coded in a programming language suitable for the forming apparatus. Therefore, a program for realizing the image forming apparatus according to each of the above embodiments can be stored in a computer-readable recording medium.
Therefore, the program according to each of the above embodiments is installed in the image forming apparatus 100 from a recording medium such as a flexible disk, a CD (Compact Disc), a DVD (Digital Versatile Disk), and the like. Can do. In addition, the program according to each of the above embodiments can be downloaded and installed via a telecommunication line such as the Internet.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. All technical matters included in the technical idea described in the claims are defined by the present invention. It becomes the object of.
Although the embodiments show preferred examples, those skilled in the art can realize various alternatives, modifications, variations, and improvements from the contents disclosed in the present specification. Is included in the technical scope described in the appended claims.

[Summary of Embodiments and Effects of the Present Invention]
<Embodiment 1>
This aspect is an image forming apparatus 100 that drives a recording head 21 including a plurality of nozzles 22 arranged in the sub-scanning direction by a driving waveform generated according to image data, and discharges droplets onto a recording medium P. Then, a pattern forming unit (RAM 324 and head drive control unit 33) that drives the recording head to form an adjustment pattern on the recording medium, and a correction unit (waveform correction unit 326) that corrects the drive waveform according to correction information based on the adjustment pattern. The adjustment pattern includes a reference line and an adjustment line extending along the sub-scanning direction, and the pattern forming unit simultaneously drives the first number of nozzles among the plurality of nozzles when forming the reference line. The second number of nozzles different from the first number are driven simultaneously when the adjustment line is formed.
According to this aspect, it is possible to prevent deterioration in image quality.

<Embodiment 2>
In this aspect, the first number of nozzles is the number of nozzles that maximizes the speed at which droplets are ejected from the nozzles 22.
In this aspect, the reference line is output at the density peak by discharging the droplets with the number of nozzles that maximizes the droplet discharge speed.

<Embodiment 3>
In this aspect, the first number is the number of nozzles that maximizes the amount of liquid droplets discharged from the nozzles 22.
In this aspect, the reference line is output at the density peak by discharging the droplets with the number of nozzles that maximizes the droplet discharge amount.

<Embodiment 4>
In this aspect, the pattern forming means (the RAM 324 and the head drive control unit 33) is characterized in that it forms a reference pattern composed only of reference lines.
According to this aspect, the reference pattern can be compared with the adjustment pattern including the reference line and the adjustment line by outputting the reference pattern. By comparing the two patterns, correction information for easily obtaining the drive waveform correction value can be obtained.

<Embodiment 5>
This aspect includes a reception unit (operation display unit 14) that receives input of correction information from the user, and the correction unit (waveform correction unit 326) corrects the drive waveform based on the correction information input to the reception unit. It is characterized by that.
According to this aspect, the apparatus configuration can be simplified by allowing the user to input correction information.

<Embodiment 6>
This aspect includes a light emitting unit (light emitting element 51) that emits light to the recording medium P, and a light receiving unit (light receiving element 52) that receives light emitted from the light emitting unit and reflected by the recording medium. The correction means (waveform correction unit 326) corrects the drive waveform based on the correction information output from the light receiving unit.
According to this aspect, since visual confirmation by the user is not required, the correction accuracy of the drive waveform is improved.

<Embodiment 7>
In this aspect, the correction means (waveform correction unit 326) corrects a potential other than the intermediate potential.
In this aspect, the correction unit can change the droplet discharge speed Vj and the droplet discharge amount Mj to appropriate states by correcting the amplitude of the drive waveform (drive waveform magnification) centered on the intermediate potential. .

100 image forming apparatus, 1 main guide rod, 2 sub guide rod, 3 maintenance mechanism, 5 carriage, 6 timing belt, 7 driving pulley, 8 driven pulley, 9 belt holding unit, 10 encoder sensor, 11 encoder sheet, 12 main scanning Motor, 13 Sub-scan motor, 14 Operation display section, 21 Recording head, 22 Nozzle, 30 Optical sensor, 31 Control section, 32 Main control section, 33 Head drive control section, 34 Main scan drive control section, 35 Sub scan drive control Unit, 41 image data output unit, 42 pixel count unit, 43 drive waveform correction value calculation unit, 44 drive waveform table, 45 drive waveform correction unit, 51 light emitting element, 52 light receiving element, 321 CPU, 322 ROM, 323 RAM, 324 NVRAM, 325 ASIC, 326 waveform correction unit, 511 Control means, 512 a smoothing circuit, 513 a driving circuit, 521 a photoelectric conversion circuit, 522 a low-pass filter circuit, 523 A / D converter circuit

JP 2011-148287 A

Claims (9)

An image forming apparatus that drives a recording head including a plurality of nozzles arranged in the sub-scanning direction according to a driving waveform generated according to image data, and discharges droplets onto a recording medium,
Pattern forming means for driving the recording head to form an adjustment pattern on the recording medium;
Correction means for correcting the drive waveform according to the correction information based on the adjustment pattern,
The adjustment pattern includes a reference line extending along the sub-scanning direction and an adjustment line, and the pattern forming unit simultaneously drives a first number of nozzles among the plurality of nozzles when forming the reference line, An image forming apparatus, wherein a second number of nozzles different from the first number are simultaneously driven when the adjustment line is formed.   The image forming apparatus according to claim 1, wherein the first number is a number of nozzles that maximizes a speed at which droplets are ejected from the nozzles.   The image forming apparatus according to claim 1, wherein the first number is the number of nozzles that maximizes the amount of liquid droplets discharged from the nozzles.   The image forming apparatus according to claim 1, wherein the pattern forming unit forms a reference pattern including only the reference line. Receiving means for receiving input of the correction information from the user,
The image forming apparatus according to claim 4, wherein the correction unit corrects the drive waveform based on the correction information input to the reception unit. A light emitting unit for irradiating the recording medium with light;
A light receiving unit that receives light emitted from the light emitting unit and reflected by the recording medium, and
The image forming apparatus according to claim 1, wherein the correction unit corrects the driving waveform based on correction information output from the light receiving unit.   The image forming apparatus according to claim 5, wherein the correction unit corrects a potential excluding an intermediate potential. An image processing method executed in an image forming apparatus that drives a recording head having a plurality of nozzles arranged in the sub-scanning direction by using a drive waveform generated according to image data and discharges droplets onto a recording medium. ,
Pattern forming means for driving the recording head to form an adjustment pattern on the recording medium;
Correcting the drive waveform according to correction information based on the adjustment pattern,
The adjustment pattern includes a reference line extending along the sub-scanning direction and an adjustment line, and the pattern forming unit simultaneously drives a first number of nozzles among the plurality of nozzles when forming the reference line, An image processing method, wherein a second number of nozzles different from the first number are simultaneously driven when the adjustment line is formed. In a control program for causing an image forming apparatus to drive a recording head provided with a plurality of nozzles arranged in the sub-scanning direction by using a driving waveform generated according to image data and to discharge liquid droplets onto a recording medium,
Pattern forming means for driving the recording head to form an adjustment pattern on the recording medium;
Correcting the drive waveform according to correction information based on the adjustment pattern,
The adjustment pattern includes a reference line extending along the sub-scanning direction and an adjustment line, and the pattern forming unit simultaneously drives a first number of nozzles among the plurality of nozzles when forming the reference line, A control program for simultaneously driving a second number of nozzles different from the first number when forming the adjustment line.

Images