JP2010210941A - Image forming apparatus, image quality adjusting method and program for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, etc., which can maintain a more suitable image quality without interrupting a printing job by easily performing image quality adjustment by spacing between sheets in the printing job. <P>SOLUTION: The image forming apparatus includes a printing section and an image adjusting section for performing the image quality adjustment in the printing section by using a gradation patch pattern. A prescribed number of printed sheets before the image adjusting section performs the image quality adjustment is set according to the state of the image forming apparatus and whether or not the accumulated number of printed sheets exceeds the prescribed number of printed sheets is determined. Here, the average printing ratio is calculated based on the accumulated number of sheets when determined that the prescribed printed number of printed sheets is exceeded and a gradation patch pattern is partially used when the printing section performs image quality adjustment during the printing job. In addition, image adjustment is performed by: using a high density section in the gradation patch pattern when the calculated average printing ratio is greater than the reference average printing ratio; and using a low density section in the gradation patch pattern when the calculated average printing ratio is smaller than the reference average printing ratio. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a printing unit and an image quality adjusting unit that performs image quality adjustment (process control) of the printing unit using a gradation patch pattern.

  In an electrophotographic image forming apparatus, in order to form a toner image, a one-component developing system using one-component toner, and a two-component developing apparatus using a two-component developer including a non-magnetic toner and a magnetic carrier It is divided roughly into.

  The one-component development method is suitable for downsizing, but is not suitable for high-speed development. Therefore, in a high-speed and long-life image forming apparatus, a two-component development device is almost adopted. In this type of developing apparatus using a two-component developer, the carrier itself in the two-component developer is not consumed and remains in the apparatus, but does not decrease. However, the toner is consumed and decreased. Therefore, in order to stabilize the image quality, the toner is appropriately replenished so that the toner concentration of the two-component developer is kept constant.

  Also, the image forming apparatus changes the print image quality under the influence of deterioration of the photoconductor and developer and changes in environmental conditions. Therefore, various image quality adjustments (process control or process control) are used to prevent this phenomenon. In recent years, these adjustment modes have been implemented even when the image forming apparatus is not used for a long time.

  For example, image quality adjustment (Pro-con) is performed every time a predetermined number of prints is reached, or image quality adjustment (Pro-con) is performed every time when the power is turned on or after returning from the leaving mode. The reason is that if printing is continued to some extent, the photoreceptor and developer deteriorate and the desired print image quality cannot be obtained, and when the power is turned on or after returning from the neglected mode, the image forming engine has stopped until then. Therefore, in the case of the two-component development method, the developer is not charged with stirring for a while, and the temperature and humidity environment in which the machine is installed are changed (for example, the temperature and humidity difference between morning and daytime). Such).

  Here, Patent Document 1 discloses an image forming apparatus having a manual setting mode in which a user instructs the timing of executing process control of the image forming unit, and calculates and stores cumulative operation information after the previous process control is executed. A cumulative operation information management unit that performs the process control at a timing when the cumulative operation information reaches the threshold, and a threshold setting unit that sets the cumulative operation information at the time when the instruction is given in the manual setting mode. An image forming apparatus is disclosed that includes a process control management unit that executes and resets the cumulative operation information.

JP 2008-170799 A

  In a conventional image forming apparatus, the image quality adjustment period (the number of sheets for setting the control computer) is generally set by the number of printed sheets, the developing roller rotation time of the developing device, and the like. May be performed. In particular, this tendency increases for jobs with a large number of printed sheets. Then, since the print job is temporarily stopped, there is a problem that the user feels uncomfortable.

  Such a problem does not occur if the image quality adjustment can be performed with the sheet interval of the recording paper. However, since it is actually necessary to adjust the image quality using a halftone patch of a dozen gradations, several tens mm (for example, With a process speed of 220 mm / sec, 50 sheets per minute, and an A4 size paper spacing of 54 mm), these patches cannot be read, and a halftone patch is unavoidably created on the photoreceptor in the middle of a print job. The current situation is that the image quality is adjusted accordingly.

  In view of the above-described problems, an object of the present invention is to easily maintain image quality without interrupting a print job by simply performing image quality adjustment (process control) at the paper interval of the print job. Providing an image forming apparatus and the like.

  In view of the above-described problems, an image forming apparatus of the present invention includes a printing unit, and an image quality adjusting unit that performs image quality adjustment (process control) of the printing unit using a gradation patch pattern. According to the state of the image forming apparatus, a predetermined number of prints setting unit for setting a predetermined number of prints until the image quality adjustment unit performs image quality adjustment, and a cumulative number printed after the printing unit is adjusted for image quality A print number determination unit that determines whether or not the number of prints exceeds the predetermined print number, and an average print rate based on the cumulative number of prints when the print number determination unit determines that the predetermined number of prints has been exceeded. An average printing rate calculation unit that calculates the image quality, and the image quality adjustment unit uses a part of a gradation patch pattern when the printing unit performs image quality adjustment during a print job, and the calculated average Print rate If the reference average print rate is larger than the pre-stored reference average print rate, image quality adjustment using the high density portion of the gradation patch pattern is performed, and the calculated average print rate is the pre-stored reference average print rate. If it is smaller, the image quality adjustment using the low density portion of the gradation patch pattern is performed.

  The image forming apparatus of the present invention further includes an environment detecting unit that detects an apparatus environment of the image forming apparatus, and the predetermined print number setting unit is based on the environment of the image forming apparatus detected by the environment detecting unit. The predetermined number of prints is set.

  In the image forming apparatus of the present invention, the image quality adjustment unit changes the number of patches used for image quality adjustment according to the width between sheets.

  In the image forming apparatus of the present invention, the predetermined number of printed sheets is 30 or more and 50 or less.

  An image quality adjustment method for an image forming apparatus according to the present invention is used in an image forming apparatus including a printing unit, and an image quality adjustment step for performing image quality adjustment (process control) of the printing unit using a gradation patch pattern. A predetermined number of prints setting step for setting a predetermined number of prints until the image quality adjustment unit performs image quality adjustment according to the state of the image forming apparatus, and the image quality of the printing unit is adjusted. A print number determination step for determining whether or not a cumulative print number printed later exceeds the predetermined print number, and when the print number determination step determines that the predetermined print number is exceeded, based on the cumulative print number An average printing rate calculating step for calculating an average printing rate, and the image quality adjusting step is performed when the printing unit performs image quality adjustment during a print job. When a part of the tone patch pattern is used and the calculated average printing rate is larger than the reference average printing rate stored in advance, image quality adjustment is performed using the high density portion of the gradation patch pattern. When the calculated average printing rate is smaller than a pre-stored reference average printing rate, image quality adjustment using the low density portion of the gradation patch pattern is performed.

  According to an embodiment of the present invention, there is provided a program that includes a printing unit and an image quality adjustment unit that performs image quality adjustment (process control) of the printing unit using a gradation patch pattern. And a predetermined number of prints setting procedure for setting a predetermined number of prints until the image quality adjustment unit performs image quality adjustment, and a cumulative number of prints printed after the print unit is adjusted for image quality exceeds the predetermined number of prints. An average printing rate calculation procedure for calculating an average printing rate based on a cumulative printing number when the printing number determination procedure determines that the predetermined number of printing sheets has been exceeded. When the print unit performs image quality adjustment during a print job, a part of the gradation patch pattern is used, and the calculated average print rate is stored in advance as a reference average print. If it is larger, image quality adjustment using a high density portion of the gradation patch pattern is performed, and if the calculated average printing rate is smaller than a pre-stored reference average printing rate, the gradation patch It is characterized in that the image quality adjustment unit is controlled to perform image quality adjustment using the low density portion of the pattern.

  According to the present invention, in a print job, when a part of the gradation patch pattern is used and the calculated average printing rate is larger than the reference average printing rate, the density by the high density portion of the gradation patch pattern When the correction is small, the density correction by the low density portion is executed, so that the time can be greatly reduced as compared with the conventional image quality adjustment. In addition, since the latest print information is taken into consideration, it is possible to achieve both minimum image quality stability and print job efficiency.

  Further, according to the present invention, since the number of patches used for image quality adjustment in the gradation patch pattern is changed depending on the width between sheets, the patch density can be read and inserted between sheets. Therefore, the print image quality can always be maintained at a high level even during a print job.

  Further, according to the present invention, the predetermined number of sheets is 30 or more and 50 or less, so even if the printed document is continuous, the developer is sufficiently replaced and agitated and stabilized. Further, it is not necessary to have a large amount of memory, and the calculation of the average printing rate is completed in a single time.

  Further, according to the present invention, the print number setting section can be changed according to the environmental conditions, so that the print image quality can be maintained at a high level in any environment.

  Further, according to the present invention, it is possible to provide a computer program for causing a computer to execute the above image forming method and a computer-readable recording medium on which the computer program is recorded.

FIG. 2 is a diagram for explaining a device configuration of an image forming apparatus in the present embodiment. FIG. 2 is a diagram for describing a functional configuration of an image forming apparatus in the present embodiment. It is a flowchart for demonstrating the operation | movement in this embodiment. It is a figure which shows an example of the gradation patch pattern used in this embodiment.

  Hereinafter, an image forming apparatus 1 including an image quality adjusting unit according to the best embodiment of the present invention will be described in detail with reference to the drawings.

[1. Device configuration]
FIG. 1 is an explanatory diagram showing a simple configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 serving as a main body forms multicolor and single color images on a sheet based on the read image data of the original document or image data transmitted via a network or the like. For this reason, the image forming apparatus 1 includes an exposure unit E, a photosensitive drum (corresponding to the image carrier of the present invention) 101 (101a to 101d), a developing device 102 (102a to 102d), and a charging roller 103 (103a to 103a). 103d), cleaning unit 104 (104a-104d), intermediate transfer belt 11, primary transfer roller 13 (13a-13d), secondary transfer roller 14, fixing device 15, paper transport paths P1, P2, P3, paper feed cassette 16 A manual paper feed tray 17 and a paper discharge tray 18 are provided.

  The image forming apparatus 1 corresponds to the hues of four colors of cyan (C), magenta (M), and yellow (Y), which are three subtractive primary colors obtained by color separation of black (K) and a color image. Image formation is performed in the image forming units Pa to Pd using the image data. The image forming portions Pa to Pd have the same configuration. For example, the black image forming portion Pa includes a photosensitive drum 101a, a developing device 102a, a charging roller 103a, a primary transfer roller 13a, a cleaning unit 104a, and the like. The image forming portions Pa to Pd are arranged in a line in the moving direction (sub-scanning direction) of the intermediate transfer belt 11.

  The charging roller 103 is a contact-type charger that uniformly charges the surface of the photosensitive drum 101 to a predetermined potential. Instead of the charging roller 103, a contact type charger using a charging brush or a non-contact type charger using a charging wire may be used. An exposure unit E which is an exposure apparatus of the present invention includes a semiconductor laser, a polygon mirror 4, a first reflection mirror 7, a second reflection mirror 8, and the like (not shown), and images of hues of black, cyan, magenta and yellow. Each of the photosensitive drums 101a to 101d is irradiated with a light beam such as a laser beam modulated by data. On each of the photosensitive drums 101a to 101d, an electrostatic latent image is formed based on image data of each hue of black, cyan, magenta, and yellow.

  The developing device 102 supplies toner to the surface of the photosensitive drum 101 on which the electrostatic latent image is formed, and develops the electrostatic latent image into a toner image. Each of the developing devices 102a to 102d contains toner of each hue of black, cyan, magenta, and yellow, and the electrostatic latent image of each hue formed on each of the photosensitive drums 101a to 101d is black, cyan. Then, the toner images are visualized as magenta and yellow toner images. The cleaning unit 104 removes and collects toner remaining on the surface of the photosensitive drum 101 after development and image transfer.

  The intermediate transfer belt 11 disposed above the photosensitive drum 101 is stretched between the driving roller 11a and the driven roller 11b to form a loop-shaped movement path. The outer peripheral surface of the intermediate transfer belt 11 faces the photosensitive drum 101d, the photosensitive drum 101c, the photosensitive drum 101b, and the photosensitive drum 101a in this order. Primary transfer rollers 13a to 13d are arranged at positions facing the respective photosensitive drums 101a to 101d with the intermediate transfer belt 11 interposed therebetween. Each of the positions where the intermediate transfer belt 11 faces the photosensitive drums 101a to 101d is a primary transfer position. The intermediate transfer belt 11 is formed of a film having a thickness of about 100 to 150 μm.

  The primary transfer rollers 13a to 13d have constant voltage control of a primary transfer bias opposite to the charging polarity of the toner in order to transfer the toner images carried on the surfaces of the photosensitive drums 101a to 101d onto the intermediate transfer belt 11. Applied. As a result, the toner images of each hue formed on the photosensitive drum 101 (101a to 101d) are sequentially transferred to the outer peripheral surface of the intermediate transfer belt 11, and a full color toner image is formed on the outer peripheral surface of the intermediate transfer belt 11. Is done.

  However, when image data of only a part of the hues of yellow, magenta, cyan, and black is input, some of the four photosensitive drums 101a to 101d corresponding to the hue of the input image data. Only the photosensitive drum 101 forms an electrostatic latent image and a toner image. For example, when forming a monochrome image, an electrostatic latent image and a toner image are formed only on the photosensitive drum 101 a corresponding to the black hue, and only the black toner image is transferred to the outer peripheral surface of the intermediate transfer belt 11. Is done.

  Each of the primary transfer rollers 13a to 13d is configured by covering the surface of a shaft made of a metal (for example, stainless steel) having a diameter of 8 to 10 mm with a conductive elastic material (for example, EPDM, urethane foam, or the like). A high voltage is uniformly applied to the intermediate transfer belt 11 by the elastic material.

  The toner image transferred to the outer peripheral surface of the intermediate transfer belt 11 at each primary transfer position is conveyed to a secondary transfer position that is a position facing the secondary transfer roller 14 by the rotation of the intermediate transfer belt 11. The secondary transfer roller 14 is pressed against the outer peripheral surface of the intermediate transfer belt 11 whose inner peripheral surface is in contact with the peripheral surface of the driving roller 11a at a predetermined nip pressure during image formation. When the paper fed from the paper feed cassette 16 or the manual paper feed tray 17 passes between the secondary transfer roller 14 and the intermediate transfer belt 11, the polarity of the toner charged on the secondary transfer roller 14 is opposite to that of the toner. The high voltage is applied. As a result, the toner image is transferred from the outer peripheral surface of the intermediate transfer belt 11 to the surface of the sheet.

  Of the toner adhering to the intermediate transfer belt 11 from the photosensitive drum 101, the toner remaining on the intermediate transfer belt 11 without being transferred onto the paper is removed by the cleaning unit 12 in order to prevent color mixing in the next process. Collected.

  The sheet on which the toner image has been transferred is guided to the fixing device 15, and passes between the heating roller 15a and the pressure roller 15b to be heated and pressurized. As a result, the toner image is firmly fixed on the surface of the paper. The paper on which the toner image is fixed is discharged onto the paper discharge tray 18 by the paper discharge roller 18a.

  In the image forming apparatus 1, a substantially vertical direction for feeding the paper stored in the paper feed cassette 16 to the paper discharge tray 18 between the secondary transfer roller 14 and the intermediate transfer belt 11 and via the fixing device 15. Paper transport path P1 is provided. In the paper transport path P1, a pickup roller 16a that feeds the paper in the paper feed cassette 16 one by one into the paper transport path P1, a transport roller r that transports the fed paper upward, and the transported paper A registration roller 19 that guides between the secondary transfer roller 14 and the intermediate transfer belt 11 at a predetermined timing and a paper discharge roller 18 a that discharges the paper to the paper discharge tray 18 are disposed.

  Further, inside the image forming apparatus 1, a paper conveyance path P <b> 2 in which a pickup roller 17 a and a conveyance roller r are arranged is formed between the manual paper feed tray 17 and the registration roller 19. Further, a paper transport path P3 is formed between the paper discharge roller 18a and the upstream side of the registration roller 19 in the paper transport path P1.

  The paper discharge roller 18a is rotatable in both forward and reverse directions. When the second side image is formed during single-sided image formation for forming an image on one side of the paper and double-sided image formation for forming an image on both sides of the paper, the paper discharge roller 18a is rotated forward. Driven in the direction, the paper is discharged to the paper discharge tray 18. On the other hand, when the first side image is formed in the double-sided image formation, the discharge roller 18a is driven in the normal rotation direction until the rear end of the paper passes through the fixing device 15, and then reversely rotated with the rear end of the paper sandwiched. Driven in the direction, the sheet is guided into the sheet conveyance path P3. As a result, the paper on which the image is formed on only one side when the double-sided image is formed is guided to the paper transport path P1 with the front and back surfaces and the front and rear ends reversed.

  The registration roller 19 receives the paper fed from the paper feed cassette 16 or the manual paper feed tray 17 or transported via the paper transport path P3 at the timing synchronized with the rotation of the intermediate transfer belt 11. And the intermediate transfer belt 11. For this reason, the registration roller 19 stops rotating when the operation of the photosensitive drum 101 and the intermediate transfer belt 11 is started, and the sheet fed or conveyed prior to the rotation of the intermediate transfer belt 11 has the front end at the registration roller 19. The movement in the sheet conveyance path P1 is stopped in a state where the sheet 19 is in contact with the sheet 19. Thereafter, the registration roller 19 is a position where the secondary transfer roller 14 and the intermediate transfer belt 11 are in pressure contact with each other, at a timing when the front end portion of the sheet and the front end portion of the toner image formed on the intermediate transfer belt 11 face each other. Start spinning.

  At the time of full color image formation in which image formation is performed in all of the image forming portions Pa to Pd, the primary transfer rollers 13a to 13d press the intermediate transfer belt 11 against all of the photosensitive drums 101a to 101d. On the other hand, at the time of monochrome image formation in which image formation is performed only in the image forming portion Pa, only the primary transfer roller 13a is brought into pressure contact with the photosensitive drum 101a.

[2. Functional configuration]
Next, the functional configuration of the image forming apparatus 1 will be described with reference to FIG. In the image forming apparatus 1, an image quality adjustment unit 200, an image forming unit 300, a storage unit 400, and an environment detection unit 500 are connected to the control unit 100 via a bus.

  The control unit 100 is a functional unit for controlling the image forming apparatus 1, and implements the functions of the image forming apparatus 1 by reading and executing various programs and data stored in the storage unit 400 described later. . The control unit 100 is constituted by, for example, a CPU (Central Processing Unit).

  The image quality adjustment unit 200 is a functional unit for adjusting the image quality of the image forming apparatus 1 (image forming unit 300). The image quality adjustment unit 200 periodically executes image quality adjustment processing (process control / process control) based on an instruction from the control unit 100.

  The image forming unit 300 describes functional units necessary for explaining the functional configuration of the devices constituting the image forming apparatus 1. Details have been described with reference to FIG. 1, but the photosensitive drum 302 (the photosensitive drum 101 in FIG. 1), the reflection density sensor 304 (the reflection density sensor 23 in FIG. 1), and the sheet conveying unit 306 (the paper in FIG. 1). The conveyance path P1-P3), the 1st counter 308, and the 2nd counter 310 are included.

  The reflection density sensor 304 detects the optical reflection density of the image formed on the photosensitive drum 302. The detected optical reflection density is output to the image quality adjustment unit 200.

  The first counter 308 and the second counter 310 are counters for counting the number of printed sheets. When the number of printing sheets supplied to the secondary transfer position is counted and image quality adjustment processing (process control / procon) described later is performed, the control unit 100 resets the counting result to “0”. . That is, the first counter 308 and the second counter 310 count the number of sheets on which an image is printed after the execution of the process control (hereinafter referred to as “cumulative print number”). However, the first counter 308 counts only for color images, and the second counter 310 counts only for monochrome images. Further, at the time of double-sided image formation, even if there is only one printing paper, the number of printing papers on which images are printed is counted as two.

  The storage unit 400 stores various data and programs and is a functional unit. For example, it may be composed of a semiconductor memory such as EEPROM or DRAM, a magnetic disk such as HDD, or the like.

  The storage unit 400 stores various data and programs in the data storage area 402. Further, an image quality adjustment program 410 and a predetermined print number setting program 412 are stored as main programs.

  Specifically, the image quality adjustment processing is realized by the control unit 100 reading and executing the image quality adjustment program 410. Further, the control unit 100 reads out and executes the predetermined print number setting program 412 so that the predetermined print number setting process is realized.

  The data storage area 402 stores “cumulative print number”, “predetermined print number”, “average print rate”, and “reference print rate”.

  The cumulative number of printed sheets is data for storing the cumulative number of sheets printed by the image forming apparatus 1 on the printing paper after adjusting the image quality. Further, the predetermined number of printed sheets stores an interval when the image quality adjustment unit 200 executes image quality adjustment processing (process control / process control). Here, the predetermined number of printed sheets may be stored in advance, or may be set by a service person during maintenance. Further, it may be changed as needed by the environment detection unit 500 described later.

  The average print rate stores the average of the print rates for the currently printed printing paper. That is, the average of the most recent printing rate is calculated and stored, going back from the currently printed print job. The reference print rate is a print rate that serves as a threshold when compared with the average print rate when image quality adjustment is performed.

  Here, in the present embodiment, it is assumed that the average of the printing rates of the last 30 to 50 sheets is calculated and stored retroactively from the currently printed job. This is because the weight ratio of the toner during the two-component development is usually about 4% to 8%. When the two-component developer in the developing device is about 200 g, the toner in the developer is It will be 8-16g.

  Therefore, as an example, when 50 high-printing originals with a printing rate of 50% are continuously printed, approximately 11 g of toner is required. This toner consumption amount substantially corresponds to the amount of toner in the 5% by weight of the two-component developer in the developing device. Of course, new toner is replenished into the developing device during printing, but if the toner that was in the developing device at the start of printing is preferentially used, it is about 50 sheets to be replaced.

  Further, the newly charged toner and the toner originally in the developing device have a charge amount slightly different depending on the presence or absence of a physical stress history in the developing device, but the general toner concentration is 5% development. Assuming the agent, the determination is made between 30 sheets in which the toner replacement is approximately half replaced and 50 sheets in which the toner replacement is completely replaced. Thereby, the image quality can be sufficiently stabilized even for continuous printing of a high-print original.

  The image quality adjustment program 410 is read and executed by the control unit 100, thereby realizing image quality adjustment processing (FIG. 3). The predetermined print number setting program 412 is read and executed by the control unit 100, whereby the predetermined print number setting process is realized.

  The environment detection unit 500 is a functional unit that detects an environment related to the image forming apparatus 1. A specific operation of the environment detection unit 500 will be described later.

  Specifically, the control unit 100 is configured to display each function when a printing process is instructed by the user (for example, when a start button (not shown) is operated by the user) or when image data is received from the outside. The printing process is executed by controlling the copy and executing the print job.

  As a result, for example, a duplicate image of the image described on the original paper placed on the original conveying device provided in the image forming apparatus 1 is printed on the printing paper by the procedure described above. In addition, an image based on the image data received by the image forming apparatus 1 is printed on the printing paper according to the procedure described above.

  Each time an image is recorded on one recording sheet, the fact that a color image or a monochrome image has been printed on one printing sheet is output to the first counter 308 or the second counter 310. Further, by outputting the image print signal to the control unit 100 and the image quality adjustment unit 200, the control unit 100 and the image quality adjustment unit 200 determine that the image print job is being executed in the image forming unit 300. can do.

  When the image print job is completed, that is, all images based on image data read from a document (or received from the outside) in one image print job are printed on printing paper and conveyed by the sheet conveying unit 306. 1 is output from the image forming unit 300 to the control unit 100 or the image quality adjustment unit 200, a job end signal indicating that the image print job has ended is output. . When the job end signal is input, it is determined that the image print job being executed in the image forming unit 300 has ended.

[3. Process flow]
Next, the basic processing flow (operation description) of the image forming apparatus 1 in the present embodiment is performed based on the flowchart of FIG. 3. First, the gradation halftone patch to be used will be described.

  As shown in FIG. 4, the gradation halftone patch is composed of four colors, CMYK, and is configured with a patch density of 14 gradations. The patch used in the print job of the present invention has a No. corresponding to the highlight portion at a low density. 1 to No. No. 3 corresponding to the solid part at high concentration. 11 to No. 14. The size of each patch is about 18.5 mm square, and three are about 58 mm square.

  The printing operation is started after the image forming apparatus 1 accepts a print job command or is left unattended, and the cumulative number of printed sheets (the cumulative number of printed sheets after the image quality adjustment is made) after the start of the printing operation is predetermined. It is determined whether or not the number of printed sheets has been reached (step S10). If not, printing is repeated until the predetermined number of prints is reached (step S10; No). On the other hand, if the predetermined number of prints has been reached (step S10; Yes), it is determined whether or not the point in time is in the middle of the print job (step S12). If it is not during a print job, image quality adjustment (procedure control) is performed using all normal low to high density patches (step S12; No → step S14). On the other hand, if the print job is in progress (step S12; Yes), it is determined whether or not the most recent average print rate is greater than a reference average print rate (threshold value; in this embodiment, “3%” as an example). Is performed (step S16).

  If the latest average printing rate is larger than the threshold value in step S16, image quality adjustment is performed using a high density patch (patch No. 11 to No. 14) (step S16; Yes → step S18). On the contrary, if the latest average printing rate is smaller than the threshold value, the image quality adjustment by the low density patch (patch No. 1 to No. 3) is performed (step S16; No → step S20).

  Here, the reason why such image quality adjustment can be performed will be described. When the latest average printing rate is high, a high density portion is occupied as a document. Therefore, it is only necessary to perform image quality correction on the high density side with high accuracy. When only the high density part of the gradation patch is used and the latest average printing rate is low, the low density part (highlight part) or Mainly manuscripts such as letters and lines. Therefore, the accuracy of the high density portion is not so much required, and the highlight portion is more important. Therefore, image quality adjustment is performed using only the highlight portion of the gradation patch.

[4. Modified example]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  In the embodiment described above, the number of patches used for image quality adjustment may be changed according to the width between sheets. Specifically, in the thick paper mode, printing is performed at a reduced process speed, so that the space between the sheets is widened. As a result, it is possible to perform image quality adjustment with higher accuracy by increasing the patch pattern to the maximum within the range of the inter-paper width and using the patch pattern. Therefore, image quality adjustment between paper sheets can be performed, and it is possible to achieve both maintenance of print job efficiency and image quality stability.

  In addition, when printing a large amount of high-print-rate originals, a method of printing with a gap between sheets can be considered in order to ensure followability of toner supply on the apparatus main body side. In this case, even if the number of patches is increased, the print job efficiency is not directly affected.

  Further, by changing the predetermined number of printed sheets according to the environmental conditions, the print image quality can be maintained at a high level in any environment. Specifically, the environment of the image forming 1 is detected by the environment detection unit 500. For example, a temperature sensor that detects temperature, a humidity sensor that detects humidity, and the like may be provided, which may be disposed at any position in the image forming apparatus 1, for example, disposed in the vicinity of the developing device 102. .

  Since the resistance value and the charge amount of the developer change greatly due to the change in the surrounding environment, for example, the image quality adjustment condition defined at normal temperature and normal humidity (indicated by N / N) is corrected. Specifically, since the image density is easily generated when the temperature is high and high humidity (H / H), the developing bias and the charging potential are controlled so that the image density is not generated.

  The low temperature is about 5 ° C to 10 ° C, the normal temperature is about 20 ° C to 25 ° C, the high temperature is about 30 ° C to 35 ° C, the low humidity is about 20% to 40%, and the normal humidity is about 50% to 65%. The high humidity may be about 70% to 90%. The predetermined number of printed sheets can be changed according to the detected temperature and humidity.

  With the configuration described above, it is possible to more appropriately maintain the print image quality in response to changes in environmental conditions such as the developer and the photoconductor.

  Furthermore, as another embodiment of the present invention, it is also possible to provide a computer program for causing a computer to execute the above-described image forming method and a computer-readable recording medium on which the computer program is recorded.

  For example, a control board in which a storage unit 400 in which a computer program according to the present invention is installed and an image quality adjustment unit 200 are incorporated is added to a conventional image forming apparatus, or the control board and a conventional image forming apparatus The image forming apparatus 1 is easily configured by exchanging the control board included in the image forming apparatus 1. Therefore, for example, it is easy to change the image forming apparatus already purchased by the user to the image forming apparatus 1.

  Further, as the recording medium, a memory for processing performed by the CPU, for example, a RAM or a ROM (Read Only Memory) itself may be the recording medium, or a program reading device is provided as an external storage device of the computer. It may be a recording medium that can be read by being inserted there. In any case, the recorded image forming program may be executed by the CPU accessing the recording medium, or the CPU reads the image forming program read from the recording medium. It may be downloaded to the program storage area and executed. It is assumed that this download program is stored in a predetermined storage device in advance. The CPU comprehensively controls each part of the computer so as to form a predetermined image according to the installed image forming program.

  The recording medium that can be read by the program reader includes magnetic tapes such as magnetic tapes and cassette tapes, magnetic disks such as flexible disks and hard disks, or CD-ROM (Compact Disc-Read Only Memory) / MO (Magneto Optical discs). ) / MD (Mini Disc) / DVD (Digital Versatile Disc) optical discs, IC (Integrated Circuit) cards (including memory cards) / Optical cards, etc., Mask ROM, EPROM (Erasable Programmable Read) It may be a medium for recording a fixed program including a semiconductor memory such as an only memory (EEPROM), an EEPROM (Electrically Erasable Programmable Read Only Memory), or a flash ROM.

  In addition, the computer may be configured to be connectable to a communication network including the Internet, and may be a medium that fluidly carries the program so as to download the image forming program from the communication network. When the image forming program is downloaded from the communication network in this way, the download program may be stored in a computer in advance or installed from another recording medium.

  An example of a computer system that executes an image forming program read from a recording medium includes various image reading apparatuses such as a flatbed scanner, a film scanner, and a digital camera, and various image forming methods by executing various programs. A computer that performs processing, an image display device such as a CRT (Cathode Ray Tube) display that displays processing results of the computer, a liquid crystal display, and an image output device such as a printer that outputs the processing results of the computer to paper It is a system configured to be connected to each other. Further, the computer system is provided with a modem or the like for connecting to a server or the like via a communication network and transmitting and receiving various programs including an image forming program and various data such as image data.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Polygon mirror 7, 8 Reflection mirror 11 Intermediate transfer belt 11a Drive roller 11b Driven roller 12 Cleaning unit 13 Primary transfer roller 14 Secondary transfer roller 15 Fixing device 16 Paper feed cassette 17 Manual paper feed tray 18 Paper discharge tray DESCRIPTION OF SYMBOLS 19 Registration roller 23,304 Reflection density sensor 101,302 Photosensitive drum 102 Developing apparatus 103 Charging roller 104 Cleaning unit 100 Control part 200 Image quality adjustment part 300 Image formation part 400 Storage part 500 Environment detection part

Claims (6)

An image forming apparatus comprising: a printing unit; and an image quality adjustment unit that performs image quality adjustment (process control) of the printing unit using a gradation patch pattern.
A predetermined number of prints setting unit for setting a predetermined number of prints until the image quality adjustment unit performs image quality adjustment according to the situation of the image forming apparatus;
A print number determination unit for determining whether or not the cumulative number of prints printed after the image quality adjustment of the print unit exceeds the predetermined print number;
An average printing rate calculation unit that calculates an average printing rate based on the cumulative printing number when the printing number determination unit determines that the predetermined printing number is exceeded;
With
The image quality adjustment unit uses a part of a gradation patch pattern when the printing unit performs image quality adjustment during a print job, and the calculated average print rate is a reference average print rate stored in advance. If it is larger, image quality adjustment using a high density portion of the gradation patch pattern is performed, and if the calculated average printing rate is smaller than a pre-stored reference average printing rate, the gradation patch An image forming apparatus that performs image quality adjustment using a low density portion of a pattern. An environment detecting unit for detecting an environment of the image forming apparatus;
The image forming apparatus according to claim 1, wherein the predetermined print number setting unit sets a predetermined print number based on an environment of the image forming apparatus detected by the environment detection unit.   The image forming apparatus according to claim 1, wherein the image quality adjustment unit changes the number of patches used for image quality adjustment according to a width between sheets.   The image forming apparatus according to claim 1, wherein the predetermined number of printed sheets is 30 or more and 50 or less. An image quality adjustment method used in an image forming apparatus comprising: a printing unit; and an image quality adjustment step of performing image quality adjustment (process control) of the printing unit using a gradation patch pattern,
A predetermined number of prints setting step for setting a predetermined number of prints until the image quality adjustment unit performs image quality adjustment according to the state of the image forming apparatus;
A number-of-prints determination step for determining whether the cumulative number of sheets printed after the image quality of the printing unit has been adjusted exceeds the predetermined number of sheets printed;
An average printing rate calculating step of calculating an average printing rate based on the cumulative printing number when the printing number determination step determines that the predetermined number of printings has been exceeded;
Have
The image quality adjustment step uses a part of a gradation patch pattern when the printing unit performs image quality adjustment during a print job, and the calculated average print rate is a reference average print rate stored in advance. If it is larger, image quality adjustment using a high density portion of the gradation patch pattern is performed, and if the calculated average printing rate is smaller than a pre-stored reference average printing rate, the gradation patch An image quality adjustment method for an image forming apparatus, wherein image quality adjustment is performed using a low density portion of a pattern. An image forming apparatus comprising: a printing unit; and an image quality adjustment unit that performs image quality adjustment (process control) of the printing unit using a gradation patch pattern.
A predetermined number of prints setting procedure for setting a predetermined number of prints until the image quality adjustment unit performs image quality adjustment according to the state of the image forming apparatus;
A number-of-prints determination procedure for determining whether the cumulative number of sheets printed after the image quality of the printing unit has been adjusted exceeds the predetermined number of sheets printed;
An average printing rate calculation procedure for calculating an average printing rate based on the cumulative printing number when the printing number determination procedure determines that the predetermined number of printings has been exceeded;
Realized,
When the printing unit performs image quality adjustment in a print job, when using a part of a gradation patch pattern and the calculated average printing rate is larger than a pre-stored reference average printing rate, The image density adjustment using the high density portion of the gradation patch pattern is performed, and when the calculated average printing rate is smaller than the pre-stored reference average printing rate, the low density portion of the gradation patch pattern is changed. A program for realizing that the image quality adjustment unit is controlled to perform the used image quality adjustment.

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