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JP-2026074810-A - Image forming apparatus

JP2026074810AJP 2026074810 AJP2026074810 AJP 2026074810AJP-2026074810-A

Abstract

[Problem] To enable density adjustment of an image formed by ink ejection from an ink head, regardless of the type of paper used, by reading the output image and adjusting the density as desired. [Solution] The image forming apparatus 1 includes a control unit 100 that ejects ink from multiple ink heads to create a test chart, a density calculation unit 101 that analyzes the image of the read test chart and calculates the density of the image formed by each of the multiple ink heads for each image, a determination unit 103 that determines whether the density of each image falls within a threshold range from the average density of images formed by ink heads of the same color, and an adjustment value calculation unit 104 that calculates an adjustment value to adjust the reference voltage to the drive unit that drives the ink head so that the density of the formed image of the ink head that has formed an image whose density does not fall within the above range approaches the average density. [Selection Diagram] Figure 2

Inventors

  • 江上 遼

Assignees

  • 京セラドキュメントソリューションズ株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (7)

  1. An image forming apparatus, A head unit equipped with multiple ink heads for each color used to form a color image, which eject ink to form an image on recording paper, Multiple drive units that drive each of the multiple ink heads that eject ink of the same color, and that eject ink from the ink heads, An output tray from which the recording paper on which the image has been formed by the ink head is ejected, A control unit controls the drive of the drive unit based on a predetermined reference voltage to eject ink from the plurality of ink heads to form a test chart consisting of a predetermined image pattern on the recording paper, and discharges the recording paper after the image has been formed into the output tray. A document reading unit that reads images from the document, A density calculation unit analyzes the image of the test chart obtained by reading the recording paper after the image has been formed by the document reading unit, and calculates the density of each image formed by each of the multiple ink heads for each image. A determination unit that determines whether the density of the image formed by each of the multiple ink heads falls within a predetermined threshold range based on the average density of the images formed by the multiple ink heads of the same color, An image forming apparatus comprising: an adjustment value calculation unit that calculates an adjustment value for adjusting the reference voltage to the drive unit that drives the ink head, so that the density of the formed image approaches the average density value, for the ink head that has formed an image determined by the determination unit to be outside the range.
  2. The control unit controls the drive of the drive unit based on the reference voltage set to the adjustment value, to eject ink from the plurality of ink heads, to form an image of the second test chart consisting of the image pattern on the recording paper, and to eject the recording paper after the image has been formed into the output tray. The density calculation unit analyzes the image data of the second test chart obtained by reading by the document reading unit and calculates the density of the image formed by each of the multiple ink heads for each image. The determination unit determines whether the density of the image formed by each of the multiple ink heads falls within the threshold range based on the average density of the images formed by the multiple ink heads of the same color. The adjustment value calculation unit calculates an adjustment value for the ink head that has formed an image in which the determination unit has determined that the density is not within the range, so that the density of the formed image approaches the average density value, thereby readjusting the reference voltage to the drive unit that drives the ink head. The image forming apparatus according to claim 1, wherein the control unit performs an error determination on the ink head when the number of adjustments of the reference voltage by the adjustment value reaches a predetermined upper limit and the determination unit determines that there is an image in which the density is not within the range.
  3. The image forming apparatus according to claim 1 or 2, wherein, if the number of adjustments of the reference voltage by the adjustment value is less than a predetermined upper limit, and only images in which the determination unit has determined that the density falls within the specified range exist, the control unit drives the drive unit using the reference voltage consisting of the adjustment value set at that time, causing the head unit to perform subsequent image forming.
  4. If the number of adjustments made to the reference voltage using the adjustment value reaches a predetermined upper limit, and the image forming apparatus is set to the factory default state, The image forming apparatus according to claim 2 or 3, wherein the determination unit performs the determination using a predetermined relaxation threshold that is relaxed from the threshold.
  5. Equipped with the aforementioned ink heads of multiple colors, The image forming apparatus according to claim 1, wherein the control unit controls the drive to cause the head unit to form an image of the test chart using only one ink head or using two or more ink heads.
  6. The image forming apparatus according to claim 1, wherein the adjustment value calculation unit calculates the adjustment value by multiplying the difference between the density of the image formed by each of the plurality of ink heads and the average density by a predetermined adjustment coefficient for adjusting the reference voltage.
  7. The image forming apparatus according to claim 6, wherein the adjustment coefficient is determined according to the paper characteristics of the recording paper used to form the image pattern.

Description

This invention relates to an inkjet-type image forming apparatus. Inkjet image forming machines are known to have multiple ink heads for each color, which eject ink to form an image on recording paper. Japanese Patent Publication No. 2021-160196 This is a perspective view showing the external appearance of an image forming apparatus according to one embodiment of the present invention.This is a functional block diagram schematically showing the main internal configuration of an image forming apparatus according to one embodiment of the present invention.(A) is a schematic diagram of a head unit with an ink head viewed from below, and (B) is a schematic diagram of a head unit with an ink head viewed from the front.This diagram schematically shows a part of the image forming section.This figure shows an example of a test chart formed on recording paper.This figure shows an example of a test chart formed on recording paper.An example flowchart of density adjustment processing by an image forming apparatus. The following description of an image forming apparatus according to one embodiment of the present invention will be provided with reference to the drawings. Figure 1 is a perspective view showing the external appearance of the image forming apparatus according to one embodiment of the present invention. Figure 2 is a functional block diagram schematically showing the main internal configuration of the image forming apparatus according to one embodiment of the present invention. The image forming apparatus 1 is a multifunction device that combines multiple functions, such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes a control unit 10, a document feeding unit 6, a document reading unit 5, an image forming unit 12, a paper feeding unit 14, an operation unit 47, a network interface unit 9, and a storage unit 8. The document feeding unit 6 is configured to open and close via a hinge (not shown) on the upper surface of the document reading unit 5. The document feeding unit 6 functions as a document holder cover when reading documents placed on the platen glass (not shown). The document feeding unit 6 is also known as an ADF (Auto Document Feeder) and comprises a document tray 61 on which documents are placed, and a document output tray 62 located below the document tray 61. The document feeding unit 6 supplies documents placed on the document tray 61 to the document reading unit 5 one by one and outputs the documents to the document output tray 62. The document reading unit 5 is equipped with a scanner and reads documents fed from the document feeding unit 6, or documents placed on the platen glass. Furthermore, the document reading unit 5 can sequentially read multiple document images sent from the document feeding unit 6. The following describes the process when the image forming apparatus 1 performs document reading. The document reading unit 5 optically reads the image of the document supplied to it by the document feeding unit 6, or the document placed on the platen glass, and generates image data. The image data generated by the document reading unit 5 is stored in an image memory (not shown) or similar device. The image forming operation performed by the image forming apparatus 1 will now be described. The image forming unit 12 includes an ink head 122 (see Figure 3) that ejects ink onto recording paper to form an image on the paper, a print transport unit, and a drying transport unit. Based on image data generated by the document reading operation, image data stored in image memory, image data received from a network-connected computer, etc., the image forming unit 12 uses an inkjet method to form an image on recording paper fed from the paper feed unit 14, using ink as the recording medium. The printing transport unit has an endless transport belt 125 (see Figure 3), and uses this transport belt 125 to transport the recording paper opposite the ink head 122. The drying transport unit also has an endless transport belt, similar to the printing transport unit, and uses this belt to transport the recording paper with the image formed on it, allowing the ink adhering to the paper to air dry. The image forming unit 12, as illustrated in Figures 3(A) and (B), includes a head unit 121 with multiple (in this case, 12) ink heads 122C, 122M, 122Y, and 122K (hereinafter collectively referred to as "ink head 122") for each of the following colors: cyan (C), magenta (M), yellow (Y), and black (K), which is the key plate. The ink heads 122 are positioned opposite the transport belt 125 that transports the recording paper. Furthermore, the multiple ink heads 122C, 122M, 122Y, and 122K for each color are arranged in a direction perpendicular to the paper transport direction (main scanning direction), and their positions are offset in the transport direction by every other head. Furthermore, as shown in Figure 4, the image forming unit 12 inc