JP2017223747A - Image forming apparatus, image forming method and image forming program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus for performing thinning-out of dots while keeping image quality of characters and line drawing which improves measuring accuracy of toner consumption.SOLUTION: An image forming apparatus includes: a toner consumption calculation section which has a toner quantity table indicating a correspondence between the number of dots on a photoreceptor and toner consumption, uses a first toner quantity table for a specific image and uses a second toner quantity table for images other than the specific image, and calculates the toner consumption; and an exposure control section which makes an image forming section form a plurality of patterns of which thinning-out rates of the dots are gradually different from each other, and exposes the patterns with light in a thinning-out quantity determined by the density of the plurality of patterns. The exposure control section limits the thinning-out quantity of the dots within a predetermined range, and creates a first toner quantity table using the density of the pattern of which the thinning-out quantity is the largest in the plurality of patterns and the second toner quantity table when the thinning-out quantity reaches the upper limit.SELECTED DRAWING: Figure 1

Description

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

  In an electrophotographic image forming apparatus, the amount of toner consumed in each printing is generally calculated based on image data. The toner consumption amount can be calculated based on the correlation between the toner consumption amount and the number of dots in the toner image. The calculation result of the toner consumption amount is used for controlling toner supply to the developing device, for example. Regarding the toner consumption calculation method, even if the data has the same number of dots, the toner consumption varies depending on whether it is a character or a thin line. Therefore, a technique for improving the accuracy by determining the attribute of the image data Have also been proposed (Patent Documents 1 and 2).

JP 2011-048301 A Japanese Patent Laying-Open No. 2015-108772

  However, the inventor of the present application has newly found that the toner consumption fluctuates due to the thinning out due to the limitation of the exposure pulse width or the correction of the thinning out of the dot itself. This new problem is that in the electrophotographic process, toner overlaps in a solid area including characters and fine lines and excessively adheres to the drum, so dot thinning (thinning by limiting the exposure pulse width or thinning the dot itself) In other words, the technology has been found by focusing on a technique for suppressing adhesion of excessive toner while maintaining image quality.

  The present invention has been made in view of such circumstances, and provides a technique for improving the measurement accuracy of toner consumption in image formation in which dots are thinned out while maintaining the image quality of characters and line drawings. Objective.

  The present invention provides an image forming apparatus that forms an image based on image data. The image forming apparatus includes a photosensitive member, an exposure unit that exposes the photosensitive member based on the image data to form an electrostatic latent image, and attaches toner to the photosensitive member based on the electrostatic latent image. An image forming unit having a developing unit, a line image detecting unit for detecting a specific image based on the image data, and a correspondence relationship between the number of dots on the photoconductor and toner consumption for the specific image A storage unit that stores a first toner amount table; a second toner amount table that indicates a correspondence relationship between the number of dots on the photoconductor and a toner consumption amount for an image other than the specific image; For the image, the toner consumption amount is calculated using the first toner amount table, and for the image other than the specific image, the toner consumption amount is calculated using the second toner amount table. Calculation And a plurality of patterns formed by the specific image and having different thinning rates of the electrostatic latent image in a stepwise manner are determined on the basis of the density of the plurality of patterns. An exposure control unit that exposes the exposure unit with a thinning amount, and the exposure control unit limits the thinning amount of the electrostatic latent image within a preset range, and when the thinning amount reaches an upper limit The first toner amount table is generated using the density of the pattern having the largest thinning amount among the plurality of patterns and the second toner amount table.

  The present invention provides an image forming method for forming an image based on image data. The image forming method includes: exposing a photosensitive member to the photosensitive member based on the image data to form an electrostatic latent image; An image forming process using a scanning unit and a developing unit that attaches toner to the photoconductor based on the electrostatic latent image, a line image detection process for detecting a specific image based on the image data, and the specific A first toner amount table showing a correspondence relationship between the number of dots on the photoconductor and a toner consumption amount for the image of the image, and a correspondence between the number of dots on the photoconductor and the toner consumption amount for an image other than the specific image A storage step for storing a second toner amount table indicating the relationship; and for the specific image, a toner consumption amount is calculated using the first toner amount table; for images other than the specific image, A toner consumption amount calculating step of calculating a toner consumption amount using the second toner amount table, and a plurality of the latent images formed by the specific image and having different thinning rates in stages. An exposure control step of forming a pattern in the image forming step and exposing the exposure unit with a thinning amount determined based on the density of the plurality of patterns, the exposure control step comprising: When the thinning amount is limited to a preset range and the thinning amount reaches the upper limit, the density of the pattern having the largest thinning amount among the plurality of patterns and the second toner amount table are used. Generating a first toner amount table;

  The present invention provides an image forming program for controlling an image forming apparatus that forms an image based on image data. The image forming apparatus includes a photosensitive member, an exposure unit that exposes the photosensitive member based on the image data to form an electrostatic latent image, and attaches toner to the photosensitive member based on the electrostatic latent image. A developing unit and an image forming unit, wherein the image forming program detects a specific image based on the image data, and the number of dots and toner consumption on the photoconductor for the specific image A first toner amount table showing a correspondence relationship between the first toner amount and a second toner amount table showing a correspondence relationship between the number of dots on the photosensitive member and a toner consumption amount for an image other than the specific image. The toner consumption amount is calculated using the first toner amount table for the specific image, and the toner consumption amount is calculated using the second toner amount table for images other than the specific image. A plurality of patterns formed by the toner consumption calculation unit to be output and the specific image, wherein the thinning rate of the electrostatic latent image differs in a stepwise manner. The image forming apparatus functions as an exposure control unit that exposes the exposure unit with a thinning amount determined based on the density, and the exposure control unit sets the thinning amount of the electrostatic latent image within a preset range. When the amount of thinning reaches the upper limit, the first toner amount table is generated using the density of the pattern having the largest thinning amount among the plurality of patterns and the second toner amount table. .

  According to the present invention, there is provided a technique for improving the measurement accuracy of toner consumption in image formation in which dots are thinned out while maintaining the image quality of characters and line drawings.

1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus 1 according to an embodiment of the present disclosure. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus 1 according to an embodiment. 4 is a flowchart showing the contents of an exposure calibration processing procedure of the image forming apparatus 1 according to an embodiment. It is explanatory drawing which shows the patches P1-P4 formed in the intermediate transfer belt 27a in the exposure calibration process which concerns on one Embodiment. It is a graph which shows the relationship between the exposure pulse width which concerns on one Embodiment, and the output value of a density sensor. It is a graph which shows the relationship between the printing rate (thinning-out rate) of a thin line and the output value of a density sensor concerning one embodiment. 6 is a graph showing a relationship between character gradation and toner consumption according to an embodiment. It is a graph which shows the relationship between the character gradation which concerns on one Embodiment, and the correction magnification A. It is a graph which shows the relationship between the number of printed sheets between calibration and the output value of a density sensor concerning one embodiment.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a functional configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the overall configuration of the image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 includes a control unit 10, an image forming unit 20, an operation display unit 30, a communication interface unit 40, a storage unit 50, a paper feed cassette 60, and a housing 70.

  The image forming unit 20 includes an image reading unit 21a, a color conversion processing unit 21b, a halftone processing unit 21c, a calibration density sensor 22, an exposure unit 23, developing units 24c to 24k, and charging units 25c to 25k. have. The image reading unit 21a reads an image from a document and generates image data. The color conversion processing unit 21b performs color conversion of image data that is RGB data into CMYK. The halftone processing unit 21c executes halftone processing to generate CMYK raster data. The calibration density sensor 22 is used for calibration of the exposure pulse width by the exposure unit 23.

  The control unit 10 includes main storage means such as RAM and ROM, and control means such as MPU (Micro Processing Unit) and CPU (Central Processing Unit). The control unit 10 also has a controller function related to various I / O, USB (Universal Serial Bus), bus, and other interfaces such as hardware, and controls the entire image forming apparatus 1.

  The storage unit 50 is a storage device including a hard disk drive or a flash memory that is a non-temporary recording medium, and stores a control program and data for processing executed by the control unit 10. In the present embodiment, the storage unit 50 further stores calibration image data CD and a toner amount table TD.

  The calibration image data CD stores calibration image data CD for forming calibration patches P1 to P4 (also referred to as patterns; details will be described later). The toner amount table TD is also called a toner consumption amount table, and includes a table representing the relationship between the image data value and the toner consumption amount, and a correction coefficient. The toner amount table TD is used for calculating the toner consumption amount. The toner amount table TD includes a first toner amount table (for example, LUT (Look Up Table)), a second toner amount table (for example, LUT), and a correction table (for example, LUT).

  The first toner amount table shows the correspondence between the number of dots as a latent image and the toner consumption amount for a character or thin line image. The second toner amount table shows the correspondence between the number of dots as the latent image and the toner consumption amount for images other than characters and fine lines. The correction table (for example, LUT) stores a correction value when the first toner amount table is used in a state where it cannot be controlled by exposure calibration.

  The control unit 10 functions as a line image detection unit, and detects a character or thin line image based on the image data. The control unit 10 calculates the toner consumption amount using the first toner amount table for the detected character or thin line image, and uses the second toner amount table for the image other than the character or thin line. The amount is calculated and summed to calculate the toner consumption.

  The image forming apparatus 1 of the present embodiment is a tandem type color printer. In the image forming apparatus 1, photosensitive drums (image carriers) 26m, 26c, 26y, and 26k are arranged in a row in the casing 70 so as to correspond to the respective colors of magenta, cyan, yellow, and black. Developing units 24m, 24c, 24y and 24k are arranged adjacent to the photosensitive drums 26m, 26c, 26y and 26k, respectively.

  The photosensitive drums 26m, 26c, 26y, and 26k are irradiated with laser light Lm, Lc, Ly, and Lk for each color from the exposure unit 23. By this irradiation, electrostatic latent images are formed on the photosensitive drums 26m, 26c, 26y, and 26k. The developing units 24m, 24c, 24y, and 24k adhere the toner to the electrostatic latent images formed on the surfaces of the photosensitive drums 26m, 26c, 26y, and 26k while stirring the toner. Thereby, the developing process is completed, and toner images of respective colors are formed on the surfaces of the photosensitive drums 26m, 26c, 26y, and 26k.

  The image forming apparatus 1 has an endless intermediate transfer belt 27a. The intermediate transfer belt 27a is stretched around a tension roller 27c, a driving roller 27b, and a driven roller 27d. The intermediate transfer belt 27a is driven to circulate by the rotation of the drive roller 27b.

  For example, a black toner image on the photosensitive drum 26k is primarily transferred to the intermediate transfer belt 27a by sandwiching the intermediate transfer belt 27a between the photosensitive drum 26k and the primary transfer roller 29k, and the intermediate transfer belt 27a being driven to circulate. The The same applies to the three colors cyan, yellow, and black. A full-color toner image is formed on the surface of the intermediate transfer belt 27a by performing primary transfer so as to be superimposed on each other at a predetermined timing. Thereafter, the full-color toner image is secondarily transferred to the printing paper P supplied from the paper feed cassette 60 and fixed on the printing paper P by a known fixing process.

  FIG. 3 is a flowchart showing the contents of the exposure calibration processing procedure of the image forming apparatus 1 according to the embodiment. FIG. 4 is an explanatory diagram showing patches P1 to P4 formed on the intermediate transfer belt 27a in the exposure calibration processing according to the embodiment. This calibration process is performed at the time of manufacture for suppressing individual differences, for example, or is performed at regular intervals to suppress secular change. The calibration process may be further performed when requested by the user via the operation display unit 30.

  In step S10, the image forming apparatus 1 forms calibration patches P1 to P4 on the intermediate transfer belt 27a. The patches P1 to P4 are made of, for example, black toner. The patches P1 to P4 are mainly composed of a black belt region formed of dots to which any one of four preset exposure pulse width restrictions is applied and extending in the main scanning direction, and a region composed of white pixels. White band regions extending in the scanning direction are formed alternately in the sub-scanning direction. The number of pixels in the sub-scanning direction of the black belt region and the white belt region is set in advance for calibration of characters and line drawings.

  In step S20, the calibration density sensor 22 of the image forming apparatus 1 measures the densities of the four patches P1 to P4. The density of the four patches P1 to P4 is measured based on the amount of reflected light emitted from the calibration density sensor 22 while rotating the intermediate transfer belt 27a. For this measured amount of reflected light, a target value is set in advance by an experiment or other method.

  FIG. 5 is a graph showing the relationship between the exposure pulse width and the output value of the density sensor according to one embodiment. In FIG. 5A, the horizontal axis represents the exposure pulse width Ep, and the vertical axis represents the output value (density value) of the calibration density sensor 22. The target value is an output value for forming dots with no gap as a solid. If it exceeds the target value, it means that dots are superposedly attached in an excessive manner.

  FIG. 5B shows four types of pulse width limit values set in the four patches P1 to P4. In the present embodiment, the four patches P1 to P4 are patches having a solid region (also referred to as a black belt region) formed by exposure with different ratios of the pulse width of exposure. Specifically, the patch P3 is configured by dots formed by 80% exposure in which the ratio of the exposure pulse width Ep is 80% in the pixel passing period Wp that is a time for passing one pixel during main scanning. Is a patch. The patches P1, P2, and P4 are dots formed by 40% exposure, 60% exposure, and 100% exposure in which the ratio of the exposure pulse width Ep in the pixel passage period Wp is 40%, 60%, and 100%, respectively. It is a configured patch.

  In the example of FIG. 5A, three cases C1 to C3 representing individual differences of the image forming apparatus 1 are shown. Case C1 is the case with the largest output value (ie, the highest density) among the three cases C1 to C3. In case C1, the target value is reached at point R1 between 60% exposure and 80% exposure. In the case C2, similarly to the case C1, the target value is reached at a point R2 between 60% exposure and 80% exposure. In case C3, the target value is reached at a point R3 between 80% exposure and 100% exposure.

  In step S30, the image forming apparatus 1 determines the exposure pulse width. In this embodiment, the exposure pulse width is determined as the minimum exposure pulse width that has reached the target value among the four types of pulse width restrictions. Specifically, in cases C1 and C2, 80% exposure is determined as the exposure pulse width, and in case C3, 100% exposure is determined as the exposure pulse width. The control unit 10 functions as an exposure control unit and causes the exposure unit 23 to perform exposure with the determined exposure pulse width.

  Note that the pulse width limit does not necessarily have to be determined as any of the four types of pulse width limits, and may be determined by interpolation calculation. Specifically, for example, the case C1 may be 65% exposure, the case C2 may be 76% exposure, and the case C3 may be 88% exposure.

  In step S40, the control unit 10 determines whether or not control is possible by exposure calibration. That is, the control unit 10 determines whether or not the toner amount can be controlled by the exposure calibration process. The purpose of controlling the toner amount is to control the toner so as not to be excessively adhered to the drum in a solid region including characters and fine lines. The first toner amount table is a table set on the assumption that it is used in a controllable state by exposure calibration.

  If the control can be performed by exposure calibration (possible state), the control unit 10 proceeds to step S80. If the control is not possible by exposure calibration (uncontrollable state), the control unit 10 proceeds to step S50. The case where it is not controllable by exposure calibration means that the density of the patch exceeds the target density even in the preset maximum thinning state (minimum exposure pulse width).

  FIG. 6A is a graph showing the relationship between the fine line printing rate (thinning rate) and the output value of the density sensor according to an embodiment. The character gradation means the gradation of characters and fine lines. In this example, it is assumed that the image forming apparatus 1 is in a state where the chargeability is lowered in a high temperature and humidity environment.

  The printing rate (thinning rate) indicates a printing rate in a state where thinning is performed by limiting the exposure pulse width or thinning the dots themselves. This example shows that the output value of the density sensor is higher by the difference value D than the density of the target value when the printing rate is 40% (thinning rate 60%).

  In this case, the toner amount cannot be controlled by exposure calibration so that the toner does not overlap and excessively adhere to the drum in the image area of characters and fine lines. That is, this state means that toner is excessively attached to the drum and consumed. The toner amount control by exposure calibration is limited in advance as a thinning rate limit so that the uniform limit is within a range in which the image quality of characters and fine lines does not deteriorate.

  As described above, control of the toner amount by exposure calibration is limited in advance to a range in which the image quality of characters and fine lines is not deteriorated, and thus an uncontrollable state may occur. On the other hand, in the uncontrollable state, the amount of toner consumption increases, so the accuracy of toner consumption prediction is maintained by the following correction.

  FIG. 6B shows a calculation formula for calculating the toner consumption amount in consideration of the excessive toner amount attached to the drum and consumed. Expression (1) is a calculation expression for calculating a difference value D (see FIG. 6A) representing a difference between the lower limit value of the concentration sensor output value (corresponding to the upper limit of the thinning amount) and the target value. Expression (1) is a calculation expression for calculating the correction magnification A from the difference value D. In this example, it is assumed that the correction magnification A is calculated as 1.1 times.

  FIG. 7 shows the relationship between character gradation and toner consumption in one embodiment. As can be seen from FIG. 7, the inventors of the present application have found that the amount of toner that excessively adheres to the drum increases in the region where the character gradation is high (75% to 100%).

  Note that the toner amount may be controlled by thinning out the dots themselves. In such a case, the uncontrollable state is a state in which toner is excessively attached to the drum due to at least one of the control of the toner amount by exposure calibration and the control of the toner amount by thinning out dots themselves. Means. Dot thinning has a broad meaning and includes not only thinning due to the limitation of the exposure pulse width but also dot thinning.

  In step S50, the control unit 10 calculates a correction coefficient. The correction coefficient is a correction coefficient for compensating for an increase in toner consumption caused by the excessive toner adhering to the photosensitive drum 26k that is generated when reproducing an image representing a thin line.

  FIG. 8 is a graph showing the relationship between the character gradation and the correction magnification A according to an embodiment. The horizontal axis is the character gradation, and the vertical axis is the correction magnification A. In this example, the character gradation changes linearly along the correction straight line L in the range of 75% to 100% of the developing portion and the correction magnification A in the range of 1 to 1.1. Specifically, when the character gradation is 85%, the correction magnification A is 1.04. The correction magnification A is 1 when the character gradation is 0% to 75%.

  In step S60, the control unit 10 executes a table creation process. In the table creation process, the control unit 10 creates a correction table from the correction magnification A that changes linearly along the correction straight line L.

  In step S70, the control unit 10 uses the first toner amount table and the correction table to perform correction, and creates a first toner amount correction table. The first toner amount correction table is a table used for calculating the consumption amount of toner consumed in printing characters and fine lines in an uncontrollable state. The control unit 10 causes the storage unit 50 to store the first toner amount correction table.

  In step S80, the control unit 10 acquires calibration data. The calibration data includes a calibration value for limiting the exposure pulse width, a first toner amount correction table (in an uncontrollable state), and data indicating whether it is in a controllable state or an uncontrollable state. Yes.

  FIG. 9 is a graph showing the relationship between the number of printed sheets during calibration and the output value of the density sensor according to one embodiment. If the calibration data includes data indicating an uncontrollable state, the control unit 10 may add a patch for monitoring toner consumption to the image forming unit 20 between, for example, every 100 print media. As a result, the patch P1 (the thinning amount is the upper limit at 40% exposure) is formed on the intermediate transfer belt 27a.

  The control unit 10 updates the difference value D every 100 sheets. For example, between 401 sheets and 500 sheets (or 351 sheets to 450 sheets), the control unit 10 uses the correction magnification A based on the difference value D1 to reduce the toner consumption amount. The toner consumption is calculated using the correction magnification A based on the difference value D2 between 501 and 600 (or 451 to 550). As a result, the toner consumption can be accurately calculated according to environmental changes such as changes in temperature and humidity.

  As described above, according to the image forming apparatus 1 according to the embodiment, the adjustment of the printing rate (thinning rate) is restricted to maintain the image quality of characters and fine lines, and at the time of reproducing an image representing characters and fine lines. The toner consumption amount can be estimated in consideration of the toner consumption resulting from the adhesion of the generated surplus toner to the photoreceptor. Thereby, it is possible to optimize the display of the remaining toner amount and the toner replenishment.

  The present invention can be implemented not only in the above embodiment but also in the following modifications.

  Modification 1: In the above embodiment, the adjustment of the printing rate (decimation rate) of an image including at least one of characters and line drawings is limited. However, the adjustment of the printing rate (decimation rate) is not limited to a line image. The present invention can also be applied to a solid image that affects the image and its outline. The present invention can be applied to an image in which adjustment of a printing rate (thinning rate) is limited (such an image is called a specific image).

  Modification 2: In the above embodiment, a calibration patch is formed on the intermediate transfer belt, and the density is measured by the calibration density sensor. However, the present invention is not limited to this method. Specifically, for example, a calibration patch may be formed on a print medium, and measurement may be performed using an image reading unit.

  Modification 3: In the above embodiment, the processing is performed on the area of the fine line image formed with the black toner, but the present invention is not limited to this, and the area of the fine line image formed with the toners of a plurality of colors is used. You may make it apply this invention to.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control part 20 Image forming part 21a Image reading part 21b Color conversion process part 21c Halftone process part 22 Calibration density sensor 23 Exposure part 24c-24k Developing part 25c-25k Charging part 27a Intermediate transfer belt 50 Storage part 60 Paper cassette 70 Case

Claims (5)

An image forming apparatus that forms an image based on image data,
An image including a photoconductor, an exposure unit that exposes the photoconductor to form an electrostatic latent image based on the image data, and a developing unit that attaches toner to the photoconductor based on the electrostatic latent image. Forming part;
A line image detection unit for detecting a specific image based on the image data;
A first toner amount table showing the correspondence between the number of dots on the photoconductor and toner consumption for the specific image; and the number of dots on the photoconductor and toner consumption for an image other than the specific image. A storage unit for storing a second toner amount table indicating the correspondence relationship between
For the specific image, the toner consumption amount is calculated using the first toner amount table, and for the image other than the specific image, the toner consumption amount is calculated using the second toner amount table. A toner consumption calculation unit;
A thinning amount determined based on the density of the plurality of patterns, which is formed by the specific image and has the image forming unit formed with a plurality of patterns in which the thinning rate of the electrostatic latent image is stepwise different. An exposure control unit that exposes the exposure unit,
With
The exposure control unit limits the thinning amount of the electrostatic latent image to a preset range, and when the thinning amount reaches an upper limit, the density of the pattern having the largest thinning amount among the plurality of patterns is set. An image forming apparatus that generates the first toner amount table using the second toner amount table. The image forming apparatus according to claim 1,
The image forming unit includes an intermediate transfer belt that transfers a toner image from the photoconductor, and a density sensor that measures the densities of the plurality of patterns formed on the intermediate transfer belt,
In the exposure control unit, when the image forming unit forms an image on the print medium, the thinning amount of the plurality of patterns is limited to an upper limit between the plurality of toner images formed on the print medium. An image forming apparatus that forms a closest pattern and updates the second toner amount table based on the density of the pattern measured by the density sensor. The image forming apparatus according to claim 1, wherein
The image forming apparatus, wherein the specific image is an image including at least one of a character and a line drawing. An image forming method for forming an image based on image data,
A photoconductor, an exposure unit that exposes the photoconductor to form an electrostatic latent image based on the image data, and a developing unit that attaches toner to the photoconductor based on the electrostatic latent image are used. An image forming process;
A line image detection step of detecting a specific image based on the image data;
A first toner amount table showing the correspondence between the number of dots on the photoconductor and toner consumption for the specific image; and the number of dots on the photoconductor and toner consumption for an image other than the specific image. A storage step for storing a second toner amount table indicating the correspondence relationship between
For the specific image, the toner consumption amount is calculated using the first toner amount table, and for the image other than the specific image, the toner consumption amount is calculated using the second toner amount table. A toner consumption calculation step;
A plurality of patterns formed by the specific image and having different thinning rates of the electrostatic latent image in a stepwise manner are formed in the image forming step, and a thinning amount determined based on the density of the plurality of patterns An exposure control step of exposing the exposed portion at
With
The exposure control step limits the thinning amount of the electrostatic latent image to a preset range, and when the thinning amount reaches an upper limit, the density of the pattern having the largest thinning amount among the plurality of patterns is set. An image forming method including a step of generating the first toner amount table using the second toner amount table. An image forming program for controlling an image forming apparatus that forms an image based on image data,
The image forming apparatus includes a photosensitive member, an exposure unit that exposes the photosensitive member based on the image data to form an electrostatic latent image, and attaches toner to the photosensitive member based on the electrostatic latent image. An image forming unit having a developing unit;
The image forming program includes:
A line image detection unit for detecting a specific image based on the image data;
A first toner amount table showing the correspondence between the number of dots on the photoconductor and toner consumption for the specific image; and the number of dots on the photoconductor and toner consumption for an image other than the specific image. A storage unit for storing a second toner amount table indicating the correspondence relationship between
For the specific image, the toner consumption amount is calculated using the first toner amount table, and for the image other than the specific image, the toner consumption amount is calculated using the second toner amount table. A toner consumption amount calculation unit; and a plurality of patterns formed by the specific image and having different thinning rates of the electrostatic latent image in a stepwise manner. Causing the image forming apparatus to function as an exposure control unit that exposes the exposure unit with a thinning amount determined based on
The exposure control unit limits the thinning amount of the electrostatic latent image to a preset range, and when the thinning amount reaches an upper limit, the density of the pattern having the largest thinning amount among the plurality of patterns is set. An image forming program for generating the first toner amount table using the second toner amount table.