JP2015228013A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform image quality adjustment efficiently at an appropriate timing to achieve stabilization of image quality and suppress unnecessary consumption of toner.SOLUTION: An image forming apparatus 1 includes a developing part 102 and a toner storage container 1021, and further includes: an image quality adjustment execution timing setting part 157 that sets a timing to execute a subsequent image quality adjustment in terms of the number of prints according to the extent of the difference between a reference toner supply time and the actual toner supply information; and an image quality adjustment part and an image density adjustment part (151 and 158) that adjust the image quality of an image every time the set timing to execute image quality adjustment is reached.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a multifunction machine, a laser printer, and a facsimile machine that forms an image by electrophotography.

  An image forming apparatus such as a copying machine includes a photosensitive drum, a charging device that uniformly charges the photosensitive drum, an exposure device that exposes the photosensitive drum to form a latent image, and the latent image is exposed with a developer. A developing device or the like is provided. The developer used in the image forming apparatus causes a characteristic change with respect to environmental changes such as temperature and humidity, and a characteristic change accompanying a change with time. When the characteristics of the developer change, the image formation state obtained by charging, exposing and developing the photosensitive drum changes accordingly.

  Therefore, a technique called image quality adjustment is known in which image forming conditions are changed in order to suppress changes in the image forming state. Image quality adjustment usually involves actually forming a test pattern image on recording paper, measuring the density of the formed image, and changing the image formation conditions so as to eliminate the difference between the measured value and the ideal value. This suppresses changes in the image formation state. However, there is a problem that the image forming apparatus cannot be used while the work for adjusting the image quality is performed.

  In recent years, colorization of image forming apparatuses has progressed, and image forming apparatuses have a plurality of image forming units for each color. With such colorization, the demand for the quality of the printed image is increased, and image quality adjustment is performed when the power of the image forming apparatus is turned on or every predetermined number of printed sheets. However, since the image quality adjustment operation consumes a considerable amount of toner, it is desirable to reduce the number of executions as much as possible from the viewpoint of cost.

  Japanese Patent Application Laid-Open No. 2005-228867 discloses that image data adjustment conditions are different between text data and image data, and when there is a print request, the number of counts after execution of the previous process control is a predetermined image data number threshold value. A technique is described in which it is determined whether or not it has been exceeded, and process control is executed when it is exceeded.

  In Patent Document 2, in the toner supply control for determining the toner supply amount based on both the measured values of the dot counter and the toner density sensor, the image forming interval of continuously formed images is corrected when the toner supply amount exceeds the upper limit. Thus, there is described an image forming apparatus capable of performing density control with high reliability.

JP 2005-352379 A Japanese Patent Laid-Open No. 9-185243

  Since the invention described in Patent Document 1 determines image quality adjustment for each predetermined number of sheets, image quality adjustment processing with high responsiveness can be performed when there is a large change in the characteristics of a member involved in image formation or a change in characteristics with time. It's hard to expect. On the other hand, even when the characteristic change is predicted to be relatively small, image quality adjustment processing is performed for each predetermined number of sheets. Therefore, if the image quality adjustment and the print job overlap, the print job is not executed and job efficiency is reduced. There is a problem of doing. In the invention described in Patent Document 2, when the toner replenishment amount exceeds the upper limit, the upper limit of the toner replenishment amount is maintained by increasing the image forming interval of the image to perform highly reliable density control. The density adjustment is not performed at a required timing.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and a method for suppressing reduction in job efficiency and toner consumption by performing image quality adjustment at an appropriate timing. And

  The present invention relates to an image forming apparatus comprising: a developing unit that supplies a developer to an image carrier on which an electrostatic latent image is formed; and a developer container for supplying the developer to the developing unit. Image quality adjustment execution timing setting means for setting the image quality adjustment execution timing by comparing the required supply information of the agent with the actual actual supply information of the developer, and an image every time the set image quality adjustment execution timing is reached. Image quality adjusting means for adjusting the image quality of the image.

  According to another aspect of the present invention, there is provided an image forming apparatus including: a developing unit that supplies a developer to an image carrier on which an electrostatic latent image is formed; and a developer container that replenishes the developing unit with the developer. In the image forming method, the step of setting the image quality adjustment execution timing by comparing the required supply information of the developer and the actual actual supply information of the developer, and whenever the set image quality adjustment execution timing is reached, Adjusting the image quality of the image.

  According to these inventions, the developer is supplied from the developing unit to the electrostatic latent image formed on the image carrier such as the photosensitive drum, and the original image is made visible by being attached thereto. When the developer is consumed, the developer is supplied from the developer container to the developing unit. Then, the image quality adjustment execution timing setting means compares the required supply information of the developer with the actual actual supply information of the developer, and sets the execution timing of the image quality adjustment according to the comparison result. The image quality adjusting means determines whether or not the set image quality adjustment execution timing is reached, and when the execution timing is reached, adjusts the image quality of the image. The execution timing can be set by the period, time, number of printed sheets, and the like. If the content of the image adjustment is a simple type that does not involve printing on recording paper, it can also be set by the number of sheets to be performed between print jobs. Further, the developer replenishment information is information corresponding to the developer consumption assumed to be necessary for image formation, while the developer actual replenishment information is information corresponding to the actual replenishment amount. . Both values are closer to each other as the characteristics of the image carrier and the developer are more appropriate. Therefore, the comparison of the two results in the occurrence of a change in the developer characteristics and other circumstances, so that it is possible to perform appropriate image quality adjustments according to the situation by setting the timing of image quality adjustment to be long or short. To do. In this way, image quality can be adjusted efficiently at an appropriate timing to stabilize the image quality, and wasteful toner consumption can be suppressed.

  Further, the image quality adjustment execution timing setting means sets a period until the next image quality adjustment is performed according to the difference between the developer required supply information and the developer actual supply information. . According to this configuration, the period (span) corresponding to the abnormal state is set by shortening the period until the next execution timing in accordance with the difference between the two, that is, the larger the difference.

  The image quality adjustment execution timing is set by the number of printed sheets. According to this configuration, it is executed between print jobs.

  In addition, a dot counter that measures the dot count value of the electronic image is provided, and the developer replenishment information is set based on the dot count value. According to this configuration, the required replenishment information for the developer is easily obtained.

  The developer container includes a developer replenishing unit that performs a replenishing operation of the developer, and the image quality adjusting unit adjusts the developer replenishment amount with respect to the developer replenishing unit. And According to this configuration, it is possible to adjust the image density included in the image quality by adjusting the developer replenishment amount.

  Further, the image quality adjusting means includes a determining means for determining whether or not the developer container is a genuine product, and adjusts the developer replenishment amount according to the determination result. According to this configuration, it is determined whether or not the developer container such as a mounted cartridge is a genuine product. As a determination method by the determination means, it is possible to determine the contents regarding the presence / absence of genuineness entered by the user via the operation unit or the like, or to determine by reading the contents of the IC chip mounted in the proper place of the developer container The method to do can be adopted. When the determination result is not a genuine product, the developer replenishment amount for the genuine product is corrected to permit the use of a non-genuine product developer. For example, the replenishment amount in the case of non-genuine products is set to be a little larger than that in the case of genuine products, for example, about several percent, preferably about 2%, so that the image is formed thinner. Is prevented as much as possible.

  Further, the image quality adjusting unit adjusts the developer replenishment amount based on at least one of the dot count value, the history of use of the apparatus, the environmental situation, and the printing operation situation. According to this configuration, the developer replenishment amount is adjusted based on various factors (parameters).

  According to the image forming apparatus of the present invention, it is possible to stabilize image quality and suppress wasteful toner consumption by efficiently adjusting image quality at an appropriate timing.

1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus. FIG. 2 is an explanatory diagram showing a schematic configuration of a density measurement unit constituting the image forming apparatus. 4 is a flowchart illustrating an example of image quality adjustment control by the image forming apparatus. (A) is an explanatory view showing the appearance of high density correction test patches TPA to TPC used for image quality adjustment of the image forming apparatus, and (b) is a value of a developing bias when the test patches TPA to TPC are created. It is explanatory drawing which shows the relationship with reflected light intensity. (A) is an explanatory view showing the appearance of the tone correction test patches TP1 to TP16 of the image forming apparatus, and (b) is an input tone number D1 to D16 and reflected light intensity corresponding to the test patches TP1 to TP16. It is explanatory drawing which shows the relationship with the output gradation numbers H1-H16 calculated | required based on I1-I16. 6 is a diagram illustrating an example of a table of “image adjustment execution timing between jobs”. FIG. FIG. 10 is a diagram illustrating a table of another example of “image adjustment execution timing between jobs”. FIG. 6 is a diagram illustrating an example of a table in which “a ratio of actual toner replenishment (multiplier factor)” is set with a developing bias as a parameter. FIG. 10 is a diagram illustrating an example of a table in which “ratio of actual toner supply (coefficient multiple)” is set using a printing rate as a parameter. FIG. 10 is a diagram illustrating an example of a table in which “a ratio of actual toner supply (multiplier factor)” is set with life as a parameter. FIG. 6 is a diagram illustrating an example of a table in which “a ratio of actual toner replenishment (coefficient multiplication)” is set with a residual toner amount as a parameter. FIG. 6 is a diagram illustrating an example of a table in which “ratio of actual toner supply (coefficient multiplication)” is set with toner density as a parameter. FIG. 10 is a diagram illustrating an example of a table in which “a ratio of actual toner replenishment (multiplier factor)” is set with temperature and humidity as parameters. FIG. 10 is a diagram illustrating an example of a table in which “the ratio of actual toner replenishment (coefficient multiplication)” is set using the number of printed sheets per unit time as a parameter. FIG. 10 is a diagram illustrating an example of a table in which “ratio of actual toner supply (coefficient multiplication)” is set with the type of document as a parameter. It is a flowchart which shows an example of the procedure of the image quality adjustment process and implementation timing setting process which a control part performs. FIG. 10 is a diagram illustrating an example of a table in which “a ratio of actual toner replenishment (multiplier factor)” is set using whether the toner container is a genuine product or a non-genuine product as a parameter.

  The image forming apparatus 1 according to the first embodiment shown in FIG. 1 forms an electrostatic latent image by exposing the photosensitive drum 101, the charging roller 103 that uniformly charges the photosensitive drum 101, and the photosensitive drum 101. Image forming units 100a to 100d having an exposure unit 10 for developing and a developing unit 102 for developing the electrostatic latent image by attaching toner to the electrostatic latent image.

  The image forming apparatus 1 according to the first embodiment forms multicolor and single color images on a sheet based on read image data of a document or image data transmitted via a network or the like. Therefore, as shown in FIG. 1, the image forming apparatus 1 includes an exposure unit 10, a photosensitive drum 101 (101a to 101d), a developing unit 102 (102a to 102d), a charging roller 103 (103a to 103d), and a cleaning unit. 104 (104a,...), Intermediate transfer belt 11, primary transfer roller 13 (13a to 13d), secondary transfer roller 14, fixing device 15, paper transport paths P1, P2, P3, paper feed cassette 16, manual paper feed tray 17 and a paper discharge tray 18 and the like.

  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 100a to 100d using the image data.

  The image forming units 100a to 100d have the same configuration. For example, the black image forming unit 100a includes a photosensitive drum 101a, a developing unit 102a, a charging roller 103a, a transfer roller 13a, a cleaning unit 104a, and the like. The image forming units 100 a to 100 d 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.

  The exposure unit 10 includes a semiconductor laser (not shown), a polygon mirror 4, a first reflection mirror 7, a second reflection mirror 8, and the like, and a laser beam modulated by image data of black, cyan, magenta, and yellow hues. Are irradiated onto each of the photosensitive drums 101a to 101d. 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 unit 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. That is, each of the developing units 102a to 102d receives toners of respective colors of black, cyan, magenta, and yellow by receiving supply of unused toner from known toner storage containers 1021a to 1021d. The electrostatic latent images of the respective hues formed on the respective 101a to 101d are visualized as toner images of the respective hues of black, cyan, magenta and yellow. The cleaning unit 104 removes and collects toner remaining on the surface of the photosensitive drum 101 after development and image transfer.

  A toner storage container 1021 such as a cartridge is detachably attached to the developing unit 102. The toner storage container 1021 can supply toner to the developing unit 102 by driving a toner supply unit 1022 (see FIG. 2) including a toner discharge motor that rotates a toner discharge roller and the like disposed at a lower discharge port. I have to. The toner replenishing unit 1022 replenishes a predetermined amount (g / sec) of toner per unit time.

  A recording medium (CRUM: Customer Replaceable Unit memory) of an IC chip 10211 (10211d) is mounted at a predetermined location of each toner container 1021 as illustrated only in the toner container 1021d of FIG. Yes. Various information (number of printed sheets, number of days used, total printing rate, driving time, etc.) is stored in the IC chip 10211 in a predetermined format, and can be read from the control unit 150 side. The genuine product determination unit 112 determines whether or not the attached toner storage container 1021 is related to the manufacturer of the image forming apparatus 1 at an appropriate time from the time of mounting to before the start of toner supply. Whether or not the toner container 1021 is a genuine product is determined based on the presence or absence of predetermined information stored in the IC chip 10211. The genuine product determination unit 112 may determine whether the toner container 1021 is a genuine product based on whether information can be read from the IC chip 10211.

  The toner concentration detector 1020 (see FIG. 2) is disposed facing the developing unit 102, detects the toner concentration in the developer, and outputs the detected value to the control unit 150 (see FIG. 2). The controller 150 sets the toner replenishment time based on the detected value of the toner density from the toner density detector 1020 and drives the toner replenishment part 1022 (see FIG. 2) for each image forming process of one image. . As a result, an amount of toner corresponding to the consumed amount is supplied from the toner container 1021 to the developing unit 102.

  The primary transfer rollers 13 a to 13 d transfer the toner images carried on the surfaces of the photosensitive drums 101 a to 101 d onto the intermediate transfer belt 11. The secondary transfer roller 14 transfers the toner image on the intermediate transfer belt 11 onto the paper fed from the paper feed cassette 16 or the manual paper feed tray 17. The sheet on which the toner image has been transferred passes through the fixing device 15 and is discharged onto the discharge tray 18 by the discharge roller 18a.

  Next, an electrical configuration for performing image quality adjustment in the image forming apparatus 1 according to the first embodiment will be described with reference to FIGS. 2 and 3.

  As shown in FIG. 2, the image forming apparatus 1 according to the first embodiment includes a photosensitive drum 101, a charging roller 103, an exposure unit 10, a developing unit 102, a toner container 1021, and a toner replenishing unit 1022. The image forming unit 100 is provided. The image forming apparatus 1 also includes a display unit 110 that displays an image, an operation unit 111 that performs various inputs from the user side, a storage unit 120, a temperature / humidity detection unit 130, a concentration measurement unit 140, and the like. The operation of each unit is controlled by a control unit 150 configured by a computer, for example. The image forming apparatus 1 further includes a dot counter 160 described later.

  The storage unit 120 stores a history of various uses related to the image forming apparatus 1. The history includes the time that the image forming apparatus 1 has been left, the temperature or humidity in the apparatus of the image forming apparatus 1, the number of printed sheets by the print job, the photosensitive drum 101, the charging roller 103, the exposure unit 10, and the developing unit 102. The accumulated usage time or the number of printed sheets, the toner consumption used by the image forming apparatus 1, the toner supply information, and the like.

  The temperature / humidity detection unit 130 detects the temperature and humidity around the image forming apparatus 1.

  As shown in FIG. 3, the density measurement unit 140 includes a light emitting element 141 that irradiates light toward the transfer belt 11, and a test patch that is transferred onto the transfer belt 11 and is created in an image quality adjustment mode as will be described later. (Toner pattern) Receives light regularly reflected by TP, outputs a voltage corresponding to the amount of received light, and receives light irregularly reflected by the test patch, depending on the amount of received light And a diffused reflection light receiving element 143 that outputs the measured voltage. In addition, although the case where light was irradiated to the test patch on the transfer belt 11 was illustrated, it may replace with this and it is good also as an aspect which irradiates light to the test patch on the photoconductive drum 101.

  The control unit 150 executes a processing program stored in a program storage unit (not shown), thereby performing a so-called simple image quality adjustment function in the image forming unit 100 (hereinafter referred to as “image quality adjustment unit 151”). In particular, the print job start instruction determination unit 152, the print job type determination unit 153, the image quality adjustment determination unit 154, the image quality adjustment management unit 155, and the message display unit 156 function.

  The print job start instruction determination unit 152 receives an operation on the operation unit 111 and determines whether or not the start of the print job is instructed. The print job type discrimination unit 153 discriminates the type of print job instructed to start. The type of print job is, for example, whether the job to be printed is color or monochrome, the total number of jobs to be printed is large or small, or the type of document to be printed is photo or normal (such as text) It is determined based on whether it is an image or the like.

  The image quality adjustment determination unit 154 determines execution of image quality adjustment based on at least one of the use history of the image forming apparatus 1 and the detection result by the temperature / humidity detection unit 130. Specifically, the image quality adjustment determination unit 154 determines that the change in temperature or humidity exceeds a predetermined value, the use history of the image forming apparatus 1 exceeds a predetermined threshold, or FIGS. 7 and 8 described later. When the execution timing shown in (2) is reached, image quality adjustment is performed. The image quality adjustment management unit 155 determines whether or not to interrupt the image quality adjustment execution based on the type of the print job and the determination result of the image quality adjustment determination unit 154 when the print job execution timing overlaps during the image quality adjustment. judge.

  Next, image quality adjustment processing by the control unit 150 of the image forming apparatus 1 will be described with reference to the flowchart of FIG. 4 and FIGS. 5 and 6. The image quality adjustment mode includes high density correction (steps S1 to S9) and gradation correction (steps S13 to S19).

  In the following example, the gradation correction is performed only when the fluctuation amount of the developing bias voltage due to the high density correction exceeds the threshold value. However, the gradation correction may be performed every time the image quality is adjusted. . In addition, here, a case where image quality adjustment of the image forming unit 100a in charge of black is performed will be described as an example, but the color image forming units 100b to 100d can also be implemented by the same method. Furthermore, the method (procedure) and conditions for performing image quality adjustment are examples, and the method and conditions for image quality adjustment are not limited to those shown here.

  First, the procedure for performing high density correction (steps S1 to S9) will be described. By charging, exposing and developing the photosensitive drum 101, high density correction test patches TPA to TPC as shown in the example of FIG. 5A are formed on the photosensitive drum 101. A toner pattern is formed. Then, this toner pattern is transferred to the transfer belt 11, and high density correction test patches (hereinafter referred to as "test patches") TPA to TPC are created (step S1).

  The photosensitive drum 101 is charged with the applied voltage Vg of the charging roller 103. The value of the applied voltage Vg is a value of the applied voltage set at the previous image quality adjustment. The applied voltage has an initial value of −600 (V), but can be changed in step S9 described later. In addition, the exposure is performed with the duty ratio of the semiconductor laser of the exposure unit 10 being a predetermined value, here 100% (that is, continuous driving). The development is performed while changing the developing bias voltage of the developing unit 102.

  The toner patterns for the test patches TPA to TPC are formed in a state where the development bias voltage is set to, for example, Vbp-50 (V), Vbp (V), Vbp + 50 (V). Vbp (V) is a developing bias voltage set at the time of the previous image quality adjustment. In this example, the development bias voltage has an initial value of −325 (V), but is changed to an optimal value in step S5 described later.

  As shown in FIG. 5A, the appearance of the test patches TPA to TPC is such that the smaller the developing bias voltage value (the larger the absolute value in the negative direction), the greater the amount of toner adhesion. Is shown. That is, the toner adhesion amount increases in the order of the test patches TPA, TPB, and TPC.

  Next, the reflected light intensities IA, IB and IC of the test patches TPA to TPC are measured (step S3). As shown in FIG. 3, the reflected light intensity is measured by irradiating light from the light emitting element 141 toward the test patches TPA to TPC on the transfer belt 11, and the light regularly reflected or irregularly reflected by the test patches TPA to TPC. The light is received by the reflection light receiving element 142 or the irregular reflection light receiving element 143, and is performed based on the magnitude of the voltage generated by the regular reflection light receiving element 142 or the irregular reflection light receiving element 143.

  For black, the density of test patches TPA to TPC is evaluated based on the intensity of specularly reflected light, and for other colors, the density of test patches TPA to TPC is evaluated based on the intensity of diffusely reflected light. It is common. Further, since the amount of irregularly reflected light increases and the amount of specularly reflected light decreases as the toner adhesion amount increases, the magnitude of the voltage generated in the regular reflection light receiving element 142 or the irregular reflection light receiving element 143 is determined by the test patches TPA to TPC. Correlate with the concentration of

  Hereinafter, the case where the reflected light intensity is the regular reflected light intensity will be described as an example. Here, FIG. 5B is a graph showing the relationship between the developing bias voltage when creating the test patches TPA to TPC and the reflected light intensities IA, IB, and IC measured in step S3. FIG. 5B shows three measurement data corresponding to the test patches TPA to TPC and a straight line connecting two adjacent ones of the three measurement data.

  Subsequently, the developing bias voltage Vbo at which the reflected light intensity becomes the reference value Io is calculated by the procedure shown in FIG. 5B (step S5). Next, the absolute value of the difference between the grid voltage Vg and the development bias voltage Vbo calculated in step S5 is obtained, and it is determined whether this absolute value is smaller than 150 (V) (step S7).

  If it is determined in step S7 that the absolute value of the difference between the grid voltage Vg and the development bias voltage Vbo is smaller than 150 (V), in order to prevent toner from adhering to the ground (so-called “fogging”), The grid voltage Vg is set to the development bias voltage Vbo-150 (V) (step S5), and the process proceeds to step S11. On the other hand, if it is determined in step S7 that the absolute value of the difference between the grid voltage Vg and the developing bias voltage Vbo is greater than 150 (V), the process proceeds directly to step S11.

  In step S11, it is determined whether or not the development bias voltage fluctuation amount (| Vbp-Vbo |) due to the high density correction in steps S1 to S9 exceeds the fluctuation threshold (ΔVbmax). If it is determined in step S11 that the development bias voltage fluctuation amount (| Vbp−Vbo |) due to the high density correction exceeds the fluctuation threshold (ΔVbmax), the gradation correction processing in step S13 and subsequent steps is performed. Done. On the other hand, if it is determined in step S11 that the development bias voltage fluctuation amount (| Vbp−Vbo |) due to the high density correction does not exceed the fluctuation threshold (ΔVbmax), the image quality is not corrected. The adjustment process is complete.

  The threshold value of the variation amount may be different for each color. For example, the black threshold value may be larger than the other color threshold values, and this is in line with the fact that color printing generally requires higher accuracy printing than monochrome printing. .

  Next, the procedure for performing gradation correction (steps S13 to S19) will be described. First, as shown in the example of FIG. 6A, tone correction test patches TP1 to TP16 are formed on the photosensitive drum 101 by charging, exposing and developing the photosensitive drum 101. The toner pattern is formed. The toner pattern is transferred to the transfer belt 11 to create tone correction test patches (hereinafter referred to as “test patches”) TP1 to TP16 (step S13).

  The photosensitive drum 101 is charged with the applied voltage Vg of the charging roller 103. When the applied voltage Vg is changed in step S9, the changed voltage is set. In addition, the exposure is performed by setting the duty ratio of the semiconductor laser of the exposure unit 10 to a value corresponding to the input gradation numbers D1 to D16. In one example, the input gradation numbers D1 to D16 are 255, 239, 223, 207, 191, 175, 159, 143, 127, 111, 95, 79, 63, 47, 31 and 15, respectively. The laser duty ratio corresponding to the number of input gradations is obtained by referring to a gradation correction table in which the number of input gradations and the laser duty ratio are associated. The gradation correction table used at the time of the previous gradation correction is used. At the time of the first gradation correction, a default gradation correction table built into the apparatus at the time of shipment is used. Further, development is performed at the development bias voltage Vbo calculated in step S5.

  As shown in FIG. 6A, the appearance of the test patches TP1 to TP16 shows a state where the toner adhesion amount increases as the number of input gradations increases. That is, the toner adhesion amount increases in the order of the test patches TP1 to TP16.

  Next, the reflected light intensities I1 to I16 of the test patches TP1 to TP16 are measured (step S15). The reflected light intensities I1 to I16 are measured by the same method as that for high density correction.

  FIG. 6B shows 16 pieces of measurement data corresponding to the test patches TP1 to TP16, a regression curve B obtained from these 16 pieces of measurement data by the least square method, and the number of input gradations. An ideal curve A indicating an ideal relationship with the number of output gradations is shown.

  Ideally, the relationship between the number of input tones and the number of output tones is the ideal curve A (therefore, the relationship between the number of input tones and the number of output tones is the ideal curve during the previous tone correction. Although the gradation correction table is created so as to match A), the relationship between the number of input gradations and the number of output gradations deviates from the ideal curve A due to environmental changes or deterioration over time, for example, a regression curve. It can be like B. Then, by determining the laser duty ratio for each input gradation number so that the relationship between the input gradation number and the output gradation number matches the ideal curve A, the input gradation number and the laser duty ratio are associated with each other. A gradation correction table is newly created (step S17).

  Next, the development bias voltage Vbo is stored as Vbp (step S19), and the gradation correction process is completed, that is, the image quality adjustment process is completed.

  Subsequently, setting of the execution timing of the image quality adjustment process will be described.

  In FIG. 2, the dot counter 160 obtains the number of pixels of the portion where the toner is placed in the electrostatic latent image formed on the photosensitive drum 101 by counting each pixel data constituting the image data. . The dot counter 160 outputs the number of pixels of the portion where the toner is placed in the electrostatic latent image to be developed to the storage unit 120 as a dot count value. The control unit 150 stores the dot count value in the storage unit 120.

  Further, the control unit 150 functions as an image quality adjustment execution timing setting unit 157 and an image density adjustment unit 158 by executing a processing program stored in a program storage unit (not shown). The image quality adjustment execution timing setting unit 157 performs an evaluation process for evaluating the toner supply state and a timing setting process for setting a timing for performing image quality adjustment based on the evaluation result.

  The evaluation process is to obtain the difference by acquiring the reference toner replenishment time and the actual toner replenishment time. The timing setting process is to set the next image quality adjustment execution time according to the difference obtained in the evaluation process.

  The reference toner replenishment time corresponds to the toner replenishment information, and is a value corresponding to the developer consumption assumed to be necessary for image formation. The actual toner replenishment time corresponds to the actual toner replenishment information and refers to a value corresponding to the actual replenishment amount.

Here, the reference toner replenishment time is
Reference toner replenishment time = toner consumption calculated from dot count value / toner replenishment amount per unit time replenished from toner container 1021 The “toner consumption calculated from the dot count value” refers to the toner consumption required for developing one image converted from the value measured by the dot counter 160. The toner consumption amount is not limited to a single image, and may be acquired from an average of a required number of sheets. For example, the control unit 150 associates and stores the previous predetermined number of prints and each dot count value as accumulated information, calculates an average of toner consumption for each print from the accumulated information, and calculates the dot count value from the dot count value. The calculated toner consumption may be handled. The “toner replenishment amount per unit time replenished from the toner container 1021” refers to a value (g / sec) indicating the toner replenishment capability of the toner replenishment unit 1022.

  The actual toner replenishment time is the time during which the toner replenishing unit 2022 performs the operation of replenishing toner from the toner container 1021 to the developing unit 102 per print according to the detection result of the toner density detector 1020. Say.

  A table of “image adjustment execution timing between jobs” illustrated in FIG. 7 is stored in the storage unit 120 in advance. In the example of FIG. 7, the reference toner replenishment time is 0.20 [sec]. On the other hand, the actual toner replenishment time is 0.1 [sec], 0.15 [sec],... 0.30 [sec], and the job depends on the difference from the reference toner replenishment time. The content of the image adjustment execution timing is set. For example, when the actual toner replenishment time is 0.2 [sec] which is the same as the reference toner replenishment time, it is set to be performed between the 100th and 101st sheets (that is, immediately after the 100th sheet). And as the distance from the reference increases, the interval of execution timing becomes narrower. This is shorter because there is a possibility that some abnormality or the toner density (development characteristics) in the developing unit 102 is greatly changed when the reference toner replenishment time and the actual toner replenishment time are greatly different. This corresponds to the fact that it is preferable to perform the image quality adjustment processing at intervals. On the other hand, if the reference toner replenishment time is close to the actual toner replenishment time, it is likely that the image formation conditions are appropriate, so it is not necessary to change the image quality adjustment execution timing very much. doing. In the above, the reference toner replenishment time is 0.20 [sec] is an example, and other values such as the magnitude of the dot count value caused by the type of the printed document can be appropriately used as a reference. . Accordingly, the table shown in FIG. 7 is not shown, but further includes table contents for each reference toner replenishment time within a necessary range.

  In the table shown in FIG. 7, the actual toner replenishment time interval is 0.05 [sec], but may be further subdivided. Further, when the actual toner replenishment time is between the values in the table shown in FIG. 7, for example, 0.12 [sec], it can be dealt with by performing an interpolation process. In addition to adopting a table, the implementation timing may be calculated from the difference using a calculation formula. Furthermore, since the execution timing is set on the basis of the number of printed sheets, the image quality adjustment process is executed in principle between print jobs. However, the image quality adjustment process itself is a simple process as shown in FIG. Therefore, even if it is interposed between jobs, there is almost no decrease in job efficiency.

  A table of “image adjustment execution timing between jobs” illustrated in FIG. 8 is stored in the storage unit 120 in advance. This table is for setting the next execution timing based on the previous execution timing. That is, in the example of FIG. 8, “image adjustment execution timing between previous jobs” is performed between the 70th and 71st sheets, and now “actual toner supply time” is 0.2 [ sec], the “timing coefficient determined from the actual toner replenishment time with respect to the reference toner replenishment time” is “1”, so the next “image adjustment execution timing between jobs” is 70− It is between the 71st sheet. On the other hand, if the “actual toner supply time” is 0.1 [sec], the “timing coefficient determined from the actual toner supply time relative to the reference toner supply time” is “0.4”. The next “image adjustment execution timing between jobs” is between 28th and 29th sheets (28th sheet = 70th sheet × 0.4). Also in FIG. 8, the same advantage as in FIG. 7 can be obtained by shortening the execution timing of the next image quality adjustment processing according to the difference (absolute value) between the reference toner replenishment time and the actual toner replenishment time. can get. In the above, the reference toner replenishment time is 0.20 [sec], and the “image adjustment execution timing between previous jobs” is 70-71th as an example, depending on the situation Other values can be used as appropriate. Accordingly, the table shown in FIG. 7 is not shown, but further includes table contents for each reference toner replenishment time and “image adjustment execution timing between previous jobs” within a necessary range. Similarly to the case of FIG. 7, the next “image adjustment execution timing between jobs” may be calculated using a calculation formula.

  FIGS. 9 to 16 are tables for setting the actual toner replenishment ratio based on each parameter, for example, by a factor, and are stored in the storage unit 120 in advance. FIG. 9 shows the assumed development bias [V] and the development bias [V] at the previous operation of higher-accuracy image quality adjustment performed through printing on recording paper by stopping the print job. This is a table in which “the ratio of actual toner replenishment (multiplier factor)” is set in order to cope with the change in image density depending on the difference between the two. That is, the control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG. The toner replenishment process in which the replenishment time is multiplied by a factor is continued until the next image quality adjustment process. The assumed development bias of the image quality adjustment result is an image forming condition that is assumed in advance as an ideal state from parameters such as the printing rate, the usage environment of the image forming unit 100, and the usage history. The assumed bias is stored in the storage unit 120. In FIG. 9, the developing bias of the developing unit 102 is used. Alternatively, the potential of the photosensitive drum 101 or the power value of the semiconductor laser in the exposure unit 10 may be used instead.

  FIG. 10 is a table in which “the ratio of actual toner replenishment (coefficient multiplication)” is set corresponding to the printing rate calculated from the dot count value. This corresponds to the amount of toner replacement in the developing unit according to the printing rate. That is, the control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG. The toner replenishment process in which the replenishment time is multiplied by a factor is continued until the next image quality adjustment process. This continuation process is performed in the same way up to FIG.

  FIG. 11 is a table in which “the ratio of actual toner replenishment (coefficient multiple)” is set corresponding to the life of the developer and the life of the photosensitive drum 101. The life of the developer and the photosensitive drum 101 is classified into predetermined stages, for example, “first half” and “second half” depending on the history of the number of printed sheets, the period of use, the number of rotations, and the like. In the above description, information such as the number of printed sheets, the period of use, and the number of rotations affects image fogging and toner scattering, and thus is measured by each detection unit, acquired by the control unit 150, and managed by the storage unit 120. That is, the control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG. The life may be only one of the developer and the photosensitive drum 101.

  FIG. 12 is a table in which “the ratio of actual toner replenishment (coefficient multiplication)” is set corresponding to the amount of toner remaining in the toner container 1021. The remaining amount of toner in the toner container 1021 is classified into a predetermined number, for example, “high”, “half”, and “low”. In the above, the amount of toner remaining in the toner storage container 1021 affects the amount of toner replenished to the developing unit 102. Therefore, information stored in the IC chip 10211d disposed at a predetermined position of the toner storage container 1021. It is estimated from (number of printed sheets, days used, total printing rate, driving time). Alternatively, an optical sensor or a weight measuring device may be used. The control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG.

  FIG. 13 shows “actual toner replenishment ratio (coefficient multiplication) corresponding to the level of the detected value of the sensor output (when the toner concentration detector 1020 is a magnetic permeability sensor) held in the developing unit and the reference value. ) ”. Here, the detected value is divided into three stages as compared with the reference value. When the developer is a two-component system composed of toner and carrier, the more toner is needed, the more toner needs to be replenished. The control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG.

  FIG. 14 is a table in which “ratio of actual toner replenishment (coefficient multiple)” is set corresponding to temperature and humidity. The characteristics of the developer and the photosensitive drum 101 are easily affected by temperature and humidity. According to the detection result of the temperature / humidity detection unit 130, there are three categories here. The control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG.

  FIG. 15 is a table in which “the ratio of actual toner replenishment (coefficient multiplication)” is set corresponding to the number of printed sheets per unit time. The calculated number of printed sheets per unit time is divided into three stages according to the developer or the life of the photosensitive drum 101. The more the toner is replaced, the more the toner replenishment amount is increased. The control unit 150 sets the toner replenishment time by multiplying the toner replenishment time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG.

  FIG. 16 is a table in which “ratio of actual toner supply (multiplier factor)” is set corresponding to the type of document. The type of document is assumed to be text, photo, copy, fax, etc., and the document type can be determined by analyzing the unique properties of each document type from the electronic data of the document image. The control unit 150 sets the toner supply time by multiplying the toner supply time set according to the detection result of the toner density detector 1020 by the coefficient value set in FIG.

  As described above, the control unit 150 adjusts the image quality by adjusting the toner supply amount based on at least one of the dot count value, the operation history of the image forming apparatus 1, the environmental status, and the printing operation status. The toner supply amount may be adjusted by employing at least one of the parameters shown in FIGS. 9 to 16. The image quality adjustment process includes, in addition to the process shown in FIG. 4, a toner replenishment time based on FIGS. 9 to 16 and an image density adjustment setting process by adjusting the toner replenishment amount.

  Next, an example of the procedure of the image quality adjustment process and the execution timing setting process executed by the control unit 150 will be described using a flowchart with reference to FIG. When the print key or the like in the operation unit 111 is operated and a print instruction for the first print job is received (step S31), a print operation is performed by the control unit 150, and the number of prints is incremented by one. (Step S33).

  Next, it is determined whether or not the number of printed sheets has reached the execution timing, that is, the execution timing set during the previous image quality adjustment process (exceeded the set number of printed sheets) (step S35). If the execution timing has not been reached, the process proceeds to step S45. In a mode in which the print job prints a plurality of sheets, the next page print instruction is accepted and the process returns to step S31 in the same manner until the print job is completed (Yse in step S45).

  If it is determined in step S35 that the number of printed sheets has reached the execution timing, the image quality adjustment process (step S37) shown in FIG. 4 and at least one image density adjustment setting (included in the image quality adjustment process) shown in FIGS. (Step S39). Next, referring to FIGS. 7 to 8, the next execution timing setting process is performed (step S41). Then, the number of printed sheets is reset (step S43), and measurement for the next execution timing is started. Next, it is determined whether or not the print job is finished (step S45). On the other hand, if the print job is not completed, the process returns to step S31 and the same processing is repeated. Note that the order of steps S37, S39, S41, and S43 may be changed. Further, the image quality adjustment in steps S37 and S39 in the above is a simple type that is not adjusted through printing on the recording paper, so that the job efficiency is not lowered, but the execution timing is set to the recording paper. It is also possible to apply to the above-described high-accuracy image quality adjustment performed through printing on the printer.

  In FIG. 7, the reference toner replenishment time is represented by using the dot count value. However, as the second embodiment, the type and size of the recording paper, the toner adhesion rate in one recording paper, that is, the printing rate, Alternatively, the print area ratio or the like may be acquired, and the reference toner replenishment time may be set using such information.

  In the third embodiment, instead of using the reference toner supply time and the actual toner supply time, the toner consumption amount or the toner supply amount may be used.

  Next, FIG. 18 is a table in which “the ratio of actual toner replenishment (coefficient multiplication)” is set using whether the toner container 1021 is a genuine product or a non-genuine product as a parameter. It is conceivable that a non-genuine product is mounted on the image forming apparatus 1 in addition to a genuine toner container 1021. In the case of a non-genuine product, there may be a difference in toner characteristics, and it is conceivable that the amount of toner replenishment differs from that of a genuine product due to a structural difference in the toner replenishing portion of the toner storage container 1021. In image formation, it is not preferable to print a lighter image than to print a darker image. Therefore, in a non-genuine product, toner supply is increased by a predetermined ratio (%) compared to a genuine product. It is set to be implemented. The predetermined ratio may be several percent, preferably about 2%. The controller 150 sets the toner replenishment time by multiplying the toner replenishment rate set in FIGS. 9 to 16 by the coefficient value set in FIG. This correction process is performed in addition to the toner replenishment execution ratio shown in FIGS. 9 to 16 executed in FIG.

  In addition, regarding the toner replenishment process based on the presence or absence of a genuine product, instead of the mode in which the genuine product determination unit 112 uses the IC chip 10211 to determine the presence or absence of a genuine product, a user inputs from the operation unit 111 as a fourth embodiment. Alternatively, the presence or absence of a genuine product may be determined from the content of at least one of the genuine product and the non-genuine product. In addition, regarding the replenishment amount correction process based on the determination result of whether or not it is a genuine product, instead of the replenishment amount correction mode shown in FIG. It is good also as an aspect which accelerates. Further, a mode of using the IC chip 10211 and a mode of inputting from the operation unit 11 relating to a toner replenishment process depending on the presence or absence of a genuine product, a mode of increasing and correcting a correction amount, and a mode of speeding up the replenishment timing related to a correction process of a replenishment amount For example, each embodiment including the sixth embodiment including a combination of a mode input from the operation unit 11 and a mode of increasing the correction amount can be employed.

  In addition, the description of the above-described embodiment is an example in all respects, and should be considered not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 102 Developing part 1020 Toner density detector 1021 Toner container (developer container)
10211 IC chip 1022 Toner supply part (developer supply part)
111 Operation Unit 112 IC Chip Reading Unit 120 Storage Unit 130 Temperature / Humidity Detection Unit 150 Control Unit 151 Image Quality Adjustment Function (Image Quality Adjustment Unit)
157 Image quality adjustment execution timing setting section (image quality adjustment execution timing setting means)
158 Image density adjustment setting section (image quality adjustment means)
160 dot counter 10211d CRUM

Claims (8)

In an image forming apparatus comprising: a developing unit that supplies a developer to an image carrier on which an electrostatic latent image is formed; and a developer container for supplying the developer to the developing unit.
Image quality adjustment execution timing setting means for setting the execution timing of image quality adjustment by comparing the required supply information of the developer and the actual actual supply information of the developer;
An image forming apparatus comprising image quality adjusting means for adjusting the image quality of an image every time the set image quality adjustment timing is reached.   2. The image quality adjustment execution timing setting unit sets a period until the next image quality adjustment is performed according to a difference between the required supply information of the developer and the actual supply information of the developer. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the image quality adjustment execution timing is set by a number of printed sheets. A dot counter for measuring a dot count value of the electronic image;
The image forming apparatus according to claim 1, wherein the required supply information of the developer is set based on the dot count value.   The developer container includes a developer replenishing unit that performs a replenishing operation of the developer, and the image quality adjusting unit adjusts the developer replenishment amount with respect to the developer replenishing unit. The image forming apparatus according to claim 1.   6. The image quality adjusting unit according to claim 5, wherein the image quality adjusting unit includes a determining unit that determines whether or not the developer container is a genuine product, and adjusts the replenishment amount of the developer according to a determination result. Image forming apparatus.   5. The developer adjustment amount according to claim 4, wherein the image quality adjusting unit adjusts the developer replenishment amount based on at least one of the dot count value, the history of use of the apparatus, the environmental status, and the printing operation status. The image forming apparatus described. In an image forming method in an image forming apparatus comprising: a developing unit that supplies a developer to an image carrier on which an electrostatic latent image is formed; and a developer container for supplying the developer to the developing unit.
Comparing the requested developer supply information with the actual actual supply information of the developer to set the execution timing of image quality adjustment;
And a step of adjusting the image quality of the image every time the set image quality adjustment execution timing is reached.