JP2017037237A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can set a timing to execute adjustment of the density of toner in response to a user's request.SOLUTION: There is provided an image forming apparatus 1 comprising: image forming units 10 (10Y, 10M, 10C, and 10K) that form toner images; a density detection sensor 27 that detects the density of toner in the formed toner images; prediction means that predicts the amount of change in density of toner on the basis of the detected density of toner and calculate the predicted amount of change in density of toner; display means that displays the predicted amount of change in density of toner to a user; selection means that causes the user to select a condition in terms of a timing of adjustment of the density of toner on the basis of the predicted amount of change in density of toner; and adjustment means that adjusts the density of toner on the basis of the selected condition and the predicted amount of change in density of toner.SELECTED DRAWING: Figure 1

Description

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

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic method, for example, a photosensitive member formed in a drum shape is uniformly charged, and the photosensitive member is exposed to light controlled based on image information. An electrostatic latent image is formed on the photoreceptor. The developing device converts the electrostatic latent image into a visible image (toner image) using toner (hereinafter referred to as “develop”). Further, the toner image is transferred to a recording material and fixed by a fixing device to form an image.

  In Patent Document 1, in an image forming apparatus that executes a special job such as self-check at a predetermined timing different from a normal image forming sequence, a system control unit that notifies the execution of the special job before the execution of the special job; An operation unit provided with an execution button and a cancel button is disclosed for selecting whether or not to execute a special job and instructing the system control unit not to execute the special job.

JP 2002-132097 A

During image formation, the toner density of the toner image may change over time. Therefore, it is necessary to adjust (correct) the toner density. The toner density is adjusted, for example, when the toner density is detected at a predetermined interval and the detected deviation of the toner density becomes equal to or greater than a predetermined threshold value. That is, in this case, the density adjustment of the toner image is automatically performed.
However, at this time, the user cannot know the degree of toner density fluctuation. Further, there is a problem that the timing for adjusting the toner density cannot be set according to the user's request, such as a user who places importance on the stability of toner density and a user who places importance on printing productivity.
SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and the like that can set the adjustment timing of toner density according to a user's request.

According to the first aspect of the present invention, a toner image forming unit that forms a toner image, a detecting unit that detects a toner density of the formed toner image, and a variation amount of the toner density based on the detected toner concentration. Prediction means for predicting and calculating a toner density fluctuation prediction amount, display means for displaying the toner density fluctuation prediction amount to the user, and toner to the user based on the displayed toner density fluctuation prediction amount An image forming apparatus comprising: a selecting unit that selects a condition for density adjustment timing; and an adjusting unit that adjusts the toner density based on the selected condition and the toner density fluctuation prediction amount. .
A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the predicting unit calculates a predicted amount of change in toner density after the print job is executed.
The invention according to claim 3 is characterized in that the predicting unit calculates a predicted amount of fluctuation in toner density after executing a print job based on an image density of the toner image formed by the print job and the number of printed sheets. The image forming apparatus according to claim 2.
According to a fourth aspect of the present invention, the selecting means selects at least whether to perform automatically or set an allowable upper limit value of toner density as a condition for toner density adjustment timing. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.
A fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein the display unit further displays a time required for the print job.
The invention according to claim 6 is characterized in that the display means displays the updated toner density fluctuation prediction amount during execution of the print job. This is an image forming apparatus.
According to the seventh aspect of the present invention, the toner density of the toner image formed by the toner image forming unit is detected, the fluctuation amount of the toner density is predicted based on the detected toner density, and the predicted fluctuation amount of the toner density is obtained. Calculating, displaying the predicted amount of toner density fluctuation to the user, and obtaining selection information that allows the user to select a condition regarding the adjustment timing of the toner density based on the displayed predicted toner density fluctuation. The image forming method is characterized in that the toner density is adjusted based on the selection information and the toner density fluctuation prediction amount.

According to the first aspect of the present invention, it is possible to provide an image forming apparatus capable of setting the execution timing of toner density adjustment according to a user's request.
According to the second aspect of the present invention, the toner density fluctuation prediction amount can be calculated in accordance with the toner density adjustment execution timing.
According to the third aspect of the present invention, it is possible to more easily calculate the toner density fluctuation prediction amount.
According to the fourth aspect of the present invention, the user can more easily select the timing for adjusting the toner density.
According to the fifth aspect of the invention, it is possible to determine the adjustment timing of the toner density in consideration of the time required for the print job by the user.
According to the sixth aspect of the present invention, the user can grasp the toner density fluctuation prediction amount in real time during execution of the print job.
According to the seventh aspect of the present invention, it is possible to provide an image forming method capable of setting the execution timing of toner density adjustment according to a user request.

1 is a diagram illustrating an outline of an image forming apparatus according to an embodiment. It is sectional drawing of a density | concentration detection sensor. FIG. 6A is a diagram illustrating an example of a reference patch formed on an intermediate transfer belt. (B) is a diagram showing changes in the current value (sensor output) output from the density detection sensor when the reference patch is read. It is the block diagram which showed the function structural example of the control part. (A) is a diagram showing a method by which the fluctuation amount prediction unit calculates a fluctuation prediction amount of toner density after executing a print job from information included in the print job. (B) is a diagram showing the relationship between “F: predicted amount of change in toner density after execution of print job” and “G: degree of change in toner density”. (A)-(b) is a figure showing an example of a screen displayed on a touch panel. (A)-(b) is a figure showing an example of a screen displayed on a touch panel during execution of a print job. It is a flowchart explaining operation | movement of a control part.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

<Description of Overall Configuration of Image Forming Apparatus>
FIG. 1 is a diagram showing an outline of an image forming apparatus 1 according to the present embodiment.
The image forming apparatus 1 includes, for example, a plurality (four in the present embodiment) of image forming units 10 (specifically, 10Y) which are examples of toner image forming units that form toner images of respective color components by electrophotography. (Yellow), 10M (magenta), 10C (cyan), 10K (black)). The image forming apparatus 1 further includes an intermediate transfer belt 20 that sequentially transfers (primary transfer) and holds the color component toner images formed by the image forming units 10. The image forming apparatus 1 further includes a secondary transfer device 30 that collectively transfers (secondary transfer) the toner image transferred to the intermediate transfer belt 20 onto a sheet (recording material) P. Further, the image forming apparatus 1 includes a fixing device 50 that fixes the second-transferred toner image on the paper P, and a control unit 60 that controls each mechanism unit of the image forming apparatus 1.

  Each image forming unit 10 (10Y, 10M, 10C, 10K) has the same configuration except for the color of the toner used. Therefore, the yellow image forming unit 10Y will be described as an example. The yellow image forming unit 10Y includes a photosensitive layer 11 that has a photosensitive layer (not shown), is rotatably arranged in an arrow A direction, and holds an image. Around the photosensitive drum 11, a charging roll 12, an exposure unit 13, a developing device 14, a primary transfer roll 15, and a drum cleaner 16 are disposed.

Among these, the charging roll 12 is a rotating body that charges the surface of the photosensitive drum 11 and is placed in contact with the photosensitive drum 11. Then, it is connected to a charging power source (not shown). This charging power supply supplies a negative polarity DC charging bias in which an AC charging bias having a predetermined frequency is superimposed on the charging roll 12.
The exposure unit 13 exposes the surface of the photosensitive drum 11 charged by the charging roll 12 to form an electrostatic latent image. The exposure unit 13 writes an electrostatic latent image on the photosensitive drum 11 charged by the charging roll 12 with the laser beam Bm. The developing device 14 stores corresponding color component toner (yellow toner in the yellow image forming unit 10Y), and develops the electrostatic latent image on the photosensitive drum 11 with this toner. The primary transfer roll 15 primarily transfers the toner image formed on the photosensitive drum 11 to the intermediate transfer belt 20. The drum cleaner 16 removes residues (toner and the like) on the photosensitive drum 11 after the primary transfer. A developing bias power source (not shown) for applying a predetermined developing bias is connected to the developing device 14, and a transfer bias power source (not shown) for applying a predetermined transferring bias is connected to the primary transfer roll 15, respectively. Has been.

The intermediate transfer belt 20 is stretched and supported rotatably on a plurality of (in this embodiment, five) support rolls. Of these support rolls, the drive roll 21 stretches the intermediate transfer belt 20 and drives the intermediate transfer belt 20 to rotate in the direction of arrow B. Further, the tension roll 22 and the tension roll 25 rotate in accordance with the intermediate transfer belt 20 that stretches the intermediate transfer belt 20 and is driven by the drive roll 21. The correction roll 23 functions as a steering roll (which is tiltably arranged with one end in the axial direction as a fulcrum) that stretches the intermediate transfer belt 20 and restricts meandering in a direction orthogonal to the conveyance direction of the intermediate transfer belt 20. To do. Further, the backup roll 24 stretches the intermediate transfer belt 20 and functions as a constituent member of the secondary transfer device 30 described later.
Further, a belt cleaner 26 for removing residues (toner and the like) on the intermediate transfer belt 20 after the secondary transfer is disposed at a portion facing the drive roll 21 with the intermediate transfer belt 20 interposed therebetween. A density detection sensor 27 that is an example of a detection unit is disposed opposite to the intermediate transfer belt 20. The density detection sensor 27 is disposed adjacent to the black image forming unit 10 </ b> K, and reads each color toner image primarily transferred onto the intermediate transfer belt 20 to detect the toner density.

  The secondary transfer device 30 includes a secondary transfer roll 31 disposed in pressure contact with the toner image holding surface side of the intermediate transfer belt 20 and a counter electrode of the secondary transfer roll 31 disposed on the back surface side of the intermediate transfer belt 20. And a backup roll 24. A power supply roll 32 that applies a secondary transfer bias having the same polarity as the charging polarity of the toner is disposed in contact with the backup roll 24. On the other hand, the secondary transfer roll 31 is grounded.

  The paper transport system includes a paper tray 40, a transport roll 41, a registration roll 42, a transport belt 43, and a discharge roll 44. In the paper transport system, the paper P stacked on the paper tray 40 is transported by the transport roll 41, and then temporarily stopped by the registration roll 42, and then the secondary transfer position of the secondary transfer device 30 at a predetermined timing. To send. Further, the sheet P after the secondary transfer is conveyed to the fixing device 50 via the conveying belt 43, and the sheet P discharged from the fixing device 50 is sent out to the outside by the discharge roll 44.

  Next, a basic image forming process of the image forming apparatus 1 will be described. Now, when a start switch (not shown) is turned on, a predetermined image forming process is executed. More specifically, for example, when the image forming apparatus 1 is configured as a printer, digital image signals input from the outside such as a PC (personal computer) are temporarily stored in a memory. Then, toner images of the respective colors are formed based on the digital image signals of four colors (Y (yellow), M (magenta), C (cyan), and K (black)) stored in the memory. That is, each image forming unit 10 (specifically, 10Y, 10M, 10C, 10K) is driven according to the digital image signal of each color. Next, in each image forming unit 10, an electrostatic latent image is formed by irradiating the photosensitive drum 11 charged by the charging roll 12 with the laser beam Bm corresponding to the digital image signal by the exposure unit 13. Then, the electrostatic latent image formed on the photosensitive drum 11 is developed by the developing device 14 to form toner images of each color. In the case where the image forming apparatus 1 is configured as a copying machine, a document set on a document table (not shown) is read by a scanner, and the obtained read signal is converted into a digital image signal by a processing circuit. Similarly, the toner images of the respective colors may be formed.

  Thereafter, the toner images formed on the respective photosensitive drums 11 are sequentially primary-transferred to the surface of the intermediate transfer belt 20 by the primary transfer roll 15 at a primary transfer position where the photosensitive drum 11 and the intermediate transfer belt 20 are in contact with each other. . On the other hand, the toner remaining on the photosensitive drum 11 after the primary transfer is cleaned by the drum cleaner 16.

  The toner image primarily transferred onto the intermediate transfer belt 20 in this way is superimposed on the intermediate transfer belt 20 and conveyed to the secondary transfer position as the intermediate transfer belt 20 rotates. On the other hand, the sheet P is conveyed to the secondary transfer position at a predetermined timing, and the secondary transfer roll 31 sandwiches the sheet P with respect to the backup roll 24.

  Then, at the secondary transfer position, the toner image held on the intermediate transfer belt 20 is secondarily transferred to the paper P by the action of a transfer electric field formed between the secondary transfer roll 31 and the backup roll 24. . The sheet P on which the toner image is transferred is conveyed to the fixing device 50 by the conveyance belt 43. In the fixing device 50, the toner image on the paper P is heated and pressure-fixed, and then sent to a paper discharge tray (not shown) provided outside the apparatus. On the other hand, the toner remaining on the intermediate transfer belt 20 after the secondary transfer is cleaned by the belt cleaner 26.

<Description of variation in toner density>

  As described above, each of the image forming units 10Y, 10M, 10C, and 10K forms a corresponding color component toner image by electrophotography, and primarily transfers the formed color component toner image to the intermediate transfer belt 20. . In the tandem type image forming apparatus 1, since the respective photosensitive drums 11, the charging rolls 12, and the primary transfer rolls 15 are used, the degree of deterioration differs for each color. That is, the thickness of the photosensitive layer provided on the photosensitive drum 11 and the resistance values of the charging roll 12 and the primary transfer roll 15 are different for each image forming unit 10. Also, the charging characteristics of the toner for each color are different. For this reason, even if the corresponding color component toner images are formed by the image forming units 10Y, 10M, 10C, and 10K to form images of the same density for each color and are primarily transferred onto the intermediate transfer belt 20, the In practice, the image density of each color component toner formed on the transfer belt 20 is unlikely to be the same. That is, the toner density varies with time. When the variation amount of the toner density is increased, the deviation from the toner density that is originally desired to be formed is increased, and the image quality is likely to be deteriorated.

  Therefore, in the present embodiment, density adjustment reference patches (density adjustment images and density adjustment toner images) are created by the image forming units 10Y, 10M, 10C, and 10K, and are used for each color component. The toner density is adjusted. That is, the reference patch for density adjustment is first transferred onto the intermediate transfer belt 20. Next, the toner density of the reference patch of each color transferred onto the intermediate transfer belt 20 is read by the density detection sensor 27, and the control unit 60 calculates the toner density of each color component based on the obtained reading result.

  FIG. 2 shows a cross-sectional view of the concentration detection sensor 27. FIG. 2 shows a cross section in which the density detection sensor 27 is cut in a direction orthogonal to the moving direction of the intermediate transfer belt 20. The density detection sensor 27 includes a first LED (Light Emitting Device) 271 and a second LED 272 that irradiate the toner image holding surface of the intermediate transfer belt 20. The density detection sensor 27 also reflects the reflected light from the intermediate transfer belt 20 irradiated by the first LED 271 and the second LED 272 and the density adjustment reference patches S1 and S2 formed on the intermediate transfer belt 20. A PD (Photo Diode) 273 that receives light and outputs a current value having an intensity corresponding to the amount of light received is provided.

  The first LED 271, the second LED 272, and the PD 273 are accommodated in a case 274 having a downward opening. The light emitted from the first LED 271 passes through a first exit slit 274a provided in the case 274, and illuminates the surface of the intermediate transfer belt 20 at an angle of 70 °, for example. The case 274 is also provided with a second exit slit 274b that guides the irradiation light from the second LED 272 to the surface of the intermediate transfer belt 20. Here, the irradiation light from the second LED 272 is configured to illuminate the intermediate transfer belt 20 at an angle of, for example, 135 °. Further, the case 274 is also provided with an incident slit 274c for allowing reflected light from the intermediate transfer belt 20 and the reference patches S1 and S2 formed on the surface of the intermediate transfer belt 20 to pass toward the PD 273. Here, the entrance slit 274 c is provided in a direction of, for example, 110 ° with respect to the surface of the intermediate transfer belt 20. Therefore, the reflected light regularly reflected by the intermediate transfer belt 20 and the reference patches S1 and S2 is incident on the PD 273 among the light emitted from the first LED 271. On the other hand, reflected light diffused by the intermediate transfer belt 20 and the reference patches S1 and S2 is incident on the PD 273 out of the light irradiated by the second LED 272. For example, in a black toner image, the amount of light received by the toner is large, so that the amount of light received may be insufficient with only diffused light. For this reason, in the density | concentration detection sensor 27 concerning this Embodiment, the 1st LED271 and the 2nd LED272 which each differed in the attachment angle are used as a light source. A lens 275 for condensing incident light on the light receiving surface of the PD 273 is mounted inside the entrance slit 274c. The opening of the entrance slit 274c is set to φ0.8, for example.

FIG. 3A is a diagram illustrating an example of the reference patches S1 and S2 formed on the intermediate transfer belt 20. FIG.
The reference patch S1 and the reference patch S2 shown in FIG. 3A are toner images created for each of Y color, M color, C color, and K color. Among these, the reference patch S1 is a toner image having a set density of 100%, and is created for each of Y color, M color, C color, and K color. For example, the reference patch S2 has a set density of 80%, 60%, 40%, and 20%, and is created for each of Y color, M color, C color, and K color. In the illustrated example, the reference patch S1 and the reference patch S2 have a square shape, and are formed so as to fit within the length of one circumference of the intermediate transfer belt 20, respectively. When each of the reference patches S1 and S2 reaches the position of the density detection sensor 27, the toner density is read by the density detection sensor 27.

FIG. 3B is a diagram illustrating changes in the current value (sensor output) output from the density detection sensor 27 when the reference patches S1 and S2 are read.
As shown in the figure, the sensor output initially becomes an output value I ₀ when the reflected light from the surface of the intermediate transfer belt 20 is received. When the intermediate transfer belt 20 moves and the density detection sensor 27 reads the reference patch S1, a sensor output corresponding to the toner density of the reference patch S1 is obtained. Here, taking the C sensor output as an example, an output value I _C is obtained. The difference (I _C −I ₁ ) between the output value I _C and the target output value I ₁ that should be output as the sensor output corresponds to the toner density fluctuation amount. Based on this difference, the control unit 60 calculates a toner density fluctuation amount.

<Description of control unit>
Next, the control unit 60 will be described.
FIG. 4 is a block diagram illustrating a functional configuration example of the control unit 60. In FIG. 4, among the various functions of the control unit 60, those related to the present embodiment are selected and illustrated.
As shown in the figure, the control unit 60 includes a sensor output acquisition unit 61 that acquires a sensor output, a print job reception unit 62 that receives a print job, a print job analysis unit 63 that analyzes the contents of the print job, and a change in toner density. A fluctuation amount prediction unit 64 which is an example of a prediction unit that predicts the amount and calculates a toner concentration fluctuation prediction amount; a fluctuation amount output unit 65 that outputs the toner concentration fluctuation prediction amount to the display unit; Selection information acquisition unit 66 that acquires this selection information when a condition for the adjustment timing of the image is selected, a print job execution unit 67 that executes a print job in the image forming apparatus 1, and the selected condition and toner density And a toner density adjusting unit 68 which is an example of an adjusting means for adjusting the toner density based on the estimated fluctuation amount.

The sensor output acquisition unit 61 acquires the sensor output described with reference to FIG.
The print job reception unit 62 receives a print job transmitted from the user. A print job is a group of data transmitted together with a print instruction from a user. The content of an image to be printed, the content of the number of pages to be printed such as how many pages and how many copies, and what on each sheet of paper. The contents of the printing form, such as whether to print for one page, or one-sided printing or two-sided printing, are included. For this print job, the print job accepting unit 62 accepts a print job via a network, for example. The network is, for example, a LAN (Local Area Network) or the Internet.

  The print job analysis unit 63 analyzes the contents of the print job and extracts information used by the fluctuation amount prediction unit 64. Here, the print job analysis unit 63 extracts the image density and the number of prints of the toner image formed by the print job. The print job analysis unit 63 further calculates the time required for the print job.

  The fluctuation amount prediction unit 64 obtains the current fluctuation amount of the toner density. This can be, for example, an average value of the amount of change in toner density that has occurred during toner density adjustment. Further, the fluctuation amount prediction unit 64 calculates a toner density fluctuation prediction amount as the toner density fluctuation amount after the print job is executed from the information included in the print job. The toner density fluctuation amount refers to a difference between a toner density actually formed when a toner image is formed and a toner density to be originally formed.

FIG. 5A is a diagram illustrating a method in which the fluctuation amount prediction unit 64 calculates a fluctuation prediction amount of toner density after executing a print job from information included in the print job.
The table shown in the figure is “A: print job No.”, “B: image density”, “C: number of printed sheets”, “D: average value of fluctuation amount of toner density three times immediately before”, “ E: Toner density change amount obtained from print job information ”,“ F: Toner density fluctuation prediction amount after execution of print job ”,“ G: Toner density fluctuation degree ”,“ H: Determination result ” .

“A: Print Job No.” is a number assigned to the print job, for example, a print job ID.
“B: Image density” is an image density of a toner image formed by each print job. Here, the image density is determined in three stages: “high” (when the image density is high), “medium” (when the image density is medium), and “low” (when the image density is low).
“C: Number of prints” is the number of prints performed in each print job.
“D: The average value of the toner density fluctuation amount for the last three times” is the current toner density fluctuation amount, and occurs here just before the density adjustment in the last three toner density adjustments. The average value of the fluctuation amount of the toner density is adopted.
“E: change amount of toner density obtained from print job information” is the amount of change in toner density that occurs in each print job in addition to the current change in toner density.
“F: predicted amount of fluctuation of toner density after execution of print job” is a value (predicted value) in which the amount of fluctuation of toner density after execution of each print job is predicted. This is obtained by adding “E: amount of change in toner density obtained from print job information” to “D: average value of the amount of change in toner density three times immediately before”. Therefore, it can also be said that the fluctuation amount prediction unit 64 calculates the fluctuation prediction amount of the toner density after executing the print job based on the image density of the toner image formed by the print job and the number of printed sheets.
“G: degree of change in toner density” is a standardized value of “F: predicted amount of change in toner density after execution of print job”.
FIG. 5B is a diagram illustrating a relationship between “F: predicted amount of change in toner density after execution of print job” and “G: degree of change in toner density”. If “F: predicted amount of change in toner density after execution of print job” is 0 to 100, 0 to 100%. Further, when “F: predicted amount of change in toner density after execution of print job” exceeds 100, it becomes 100%.
“H: determination result” is a determination result of a predicted change in toner density obtained from “G: degree of fluctuation in toner density”. For example, as shown in FIG. 5B, when “G: degree of fluctuation of toner density” is 0% to 25%, it is “stable” (when the toner density fluctuation prediction amount is very small). , 25% to 50% is “small fluctuation” (when the toner density fluctuation prediction amount is small), and 50% to 75% is “medium fluctuation” (the toner density fluctuation prediction amount is medium). In the case of 75% to 100%, it is determined as “large fluctuation” (when the toner density fluctuation prediction amount is large).

  The fluctuation amount output unit 65 outputs “F: toner density fluctuation prediction amount after execution of print job” for display to the user. These are displayed on, for example, a UI (User Interface) of the image forming apparatus 1. Here, the UI is a touch panel.

FIGS. 6A and 6B are diagrams illustrating an example of a screen displayed on the touch panel.
In the upper part of the figure, the toner density fluctuation prediction amount is displayed. What is displayed here is “F: predicted amount of change in toner density after execution of print job”. The predicted fluctuation amount of the toner density is indicated by a numerical value and the position of the mark “▽”, and it can be seen that it is 60% here. In addition, a determination result corresponding to “F: predicted amount of change in toner density after execution of print job” is displayed. In this case, it is understood that the determination result is “medium fluctuation”.

  In the lower part of the figure, radio buttons are displayed that allow the user to select the execution timing of toner density adjustment. Here, “automatic” (automatic adjustment of toner density), “user sets allowable fluctuation degree” (determination timing of toner density adjustment is determined by toner density fluctuation degree), “not executed” (toner density) The user makes a selection from the following three types. When “user sets allowable fluctuation degree” is selected, the user can input a numerical value. This numerical value is an upper limit value that the user can tolerate for fluctuations in toner density. Here, “40%” is input. At this time, if the user does not want the toner density to fluctuate so much, the user inputs a smaller value. On the other hand, when the user does not care much about the change in toner density, a larger numerical value is input.

  These allow the user to select a condition for adjusting the toner density. Then, the user looks at the toner density fluctuation prediction amount and the result of the determination, and determines whether to adjust the toner density automatically, set an allowable upper limit of the toner density fluctuation, or not to execute it. select.

  The touch panel further displays the time required for the print job as the print time. Here, it is displayed that the printing time is 5 minutes 30 seconds. When the printing time is long, the toner density fluctuation prediction amount is usually larger. Therefore, the user can further consider the printing time and select a condition for the toner density adjustment timing.

When the user touches “change confirmation”, the screen of FIG. 6B is displayed.
In FIG. 6B, from the left side of the figure, “no change” (when the toner density fluctuation prediction amount is 0%), “stable” (when the toner density fluctuation prediction amount is 0% to 25%), “ "Small fluctuation" (when the toner density fluctuation prediction amount is 25% to 50%), "Medium fluctuation" (when the toner density fluctuation prediction quantity is 50% to 75%), "Large fluctuation" (toner density fluctuation) Confirmation samples are displayed for each of the cases where the predicted amount is 75% to 100%. This is for conceptually informing the user of the color change of the actually printed image.

  Here, the touch panel is a display unit that displays a predicted toner density fluctuation amount to the user, and a selection unit that allows the user to select a condition for adjusting the toner density based on the displayed predicted toner density fluctuation amount. Can be taken as an example.

  In the screen of FIG. 6A, when the user touches one of the radio buttons and touches “OK”, the selection information acquisition unit 66 acquires this as selection information on the condition regarding the toner density adjustment timing. To do. In this case, the selection information is information indicating whether “automatic”, “user sets allowable fluctuation degree”, or “do not execute” is selected. In addition, when the user selects “the user sets the allowable fluctuation degree”, information on the upper limit value of the allowable change in the toner density is also included.

  The print job execution unit 67 operates each mechanism unit of the image forming apparatus 1 to execute a print job and print on paper.

When toner density is adjusted by a toner density adjusting unit 68 (to be described later) during execution of a print job, the fluctuation amount predicting unit 64 updates the toner density fluctuation prediction amount, and the updated toner density is updated on the touch panel. The fluctuation prediction amount may be displayed.
FIGS. 7A and 7B are diagrams illustrating an example of a screen displayed on the touch panel during execution of a print job.
Of these, FIG. 7A shows a case where the updated toner density fluctuation prediction amount is 35%, and the corresponding determination result is “small fluctuation”. It can also be seen that the remaining printing time until the end of execution of the print job is 2 minutes 50 seconds.
FIG. 7B shows a case where the updated estimated fluctuation amount of toner density is 20% and the determination result corresponding to this is “stable”. It can also be seen that the remaining print time until the end of execution of the print job is 40 seconds.

  The toner density adjustment unit 68 adjusts the toner density based on the selection information acquired by the selection information acquisition unit 66 and the predicted change in toner density calculated by the fluctuation amount prediction unit 64. When the user selects “automatic”, the toner density adjusting unit 68 adjusts the toner density when the predicted change in toner density becomes equal to or greater than a predetermined threshold after the end of each print job. . In addition, when the user selects “the user sets the allowable fluctuation degree”, the toner density adjusting unit 68 determines that the toner density fluctuation prediction amount is equal to or larger than the numerical value input by the user on the screen of FIG. Adjust the toner density. Further, when the user selects “do not execute”, the toner density is not adjusted.

  In order for the toner density adjustment unit 68 to adjust the toner density, the reference patches S1 and S2 described with reference to FIG. 3A are created, and the density detection sensor 27 reads the toner density of the reference patches S1 and S2. Further, the sensor output acquisition unit 61 acquires the sensor output. Next, the fluctuation amount prediction unit 64 calculates the fluctuation amount of the toner density. Based on this, a density adjustment table (density correction table) for adjusting the variation amount of the toner density is created. The toner density is adjusted by this density adjustment table.

<Description of operation of control unit>
Next, the operation of the control unit 60 will be described.
FIG. 8 is a flowchart illustrating the operation of the control unit 60.
First, the print job reception unit 62 receives a print job transmitted from the user (step 101).

  Next, the print job analysis unit 63 analyzes the contents of the print job, and extracts the image density and the number of prints of the toner image formed by the print job (step 102). The print job analysis unit 63 calculates the print time as the time required for the print job (step 103).

  Then, the fluctuation amount prediction unit 64 obtains the current fluctuation amount of the toner density (step 104). Further, the fluctuation amount prediction unit 64 calculates the fluctuation prediction amount of the toner density after executing the print job by the method described with reference to FIG. 5 from the image density of the toner image extracted in step 102 and the number of printed sheets (step 105). ).

  Next, the fluctuation amount output unit 65 outputs the toner density fluctuation prediction amount to a touch panel or the like in order to display it to the user (step 106). On the touch panel, a screen as described in FIG. 6 is displayed. The touch panel also displays the time required for the print job.

  When the user selects a condition regarding the toner density adjustment time on the touch panel, the selection information acquisition unit 66 acquires this as selection information (step 107).

  Further, the print job execution unit 67 executes the print job and prints on the paper P (step 108).

Next, the toner density adjustment unit 68 determines whether or not all print jobs have been completed (step 109).
If all print jobs have been completed (Yes in step 109), the process is terminated.

  On the other hand, if all the print jobs have not been completed (No in step 109), it is determined whether or not the toner density fluctuation prediction amount is equal to or greater than the value to be adjusted after each print job is executed ( Step 110). This value is a predetermined threshold when the user selects “automatic” on the screen of FIG. 6A as described above. Further, when the user selects “the user sets the allowable fluctuation degree”, the numerical value input by the user.

  If the predicted amount of fluctuation in toner density is equal to or greater than the value to be adjusted (Yes in step 110), the sensor output acquisition unit 61 acquires the sensor output, and the toner density adjustment unit 68 adjusts the toner density ( Step 111).

On the other hand, if the predicted fluctuation amount of the toner density is less than the value to be adjusted (No in step 110), the process returns to step 108.
If the user selects “Do not execute” on the screen of FIG. 6A, “No” is selected in Step 110. As a result, the toner density is not adjusted.
In addition, after the toner density adjustment is performed in step 111, the fluctuation amount prediction unit 64 may update the fluctuation prediction amount of the toner density from information on a print job to be performed thereafter.

  According to the image forming apparatus 1 described in detail above, the user can grasp the toner density fluctuation prediction amount on the screen of FIG. Then, the timing for adjusting the toner density can be set according to the user's request. That is, for example, the user selects “user sets allowable fluctuation degree” on the screen of FIG. 6A, and the user inputs an allowable upper limit for toner density fluctuation. At this time, the user inputs a smaller numerical value when importance is attached to the stability of the toner density, and a larger numerical value is input when importance is placed on printing productivity. If the user places more importance on printing productivity, it can be handled by selecting “do not execute”. Thereby, the execution timing of toner density adjustment is set according to the user's request according to the user's request. If the user does not intend to set the timing for adjusting the toner density, “automatic” may be selected, and this case can be dealt with.

  The toner density is adjusted by the toner density adjusting unit 68 based on the selection information such as which of these has been selected and the toner density fluctuation prediction amount calculated by the fluctuation amount prediction unit 64. Do. At this time, since the toner density is adjusted based on the toner density fluctuation prediction amount, it is not necessary to newly create the reference patches S1 and S2 and measure the toner density with the density detection sensor 27. Therefore, printing productivity is unlikely to be lowered.

  Further, the image forming method by the image forming apparatus 1 described in detail above detects the toner density of the toner image formed by the toner image forming means, and predicts the amount of fluctuation of the toner density based on the detected toner density. Selection that calculates the predicted density fluctuation amount, displays the predicted toner density fluctuation amount to the user, and allows the user to select the condition for adjusting the toner density based on the displayed predicted toner density fluctuation amount It can also be grasped as an image forming method characterized in that information is acquired and toner density is adjusted based on selection information and toner density fluctuation prediction amount.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 11 ... Photosensitive drum, 12 ... Charging roll, 13 ... Exposure part, 14 ... Developing device, 15 ... Primary transfer roll, 50 ... Fixing device, 60 ... Control part, 61 ... Sensor output acquisition part, 62 ... print job reception unit, 63 ... print job analysis unit, 64 ... variation amount prediction unit, 65 ... variation amount output unit, 66 ... selection information acquisition unit, 67 ... print job execution unit, 68 ... toner density adjustment unit, P ... paper, S1, S2 ... reference patch

Claims (7)

Toner image forming means for forming a toner image;
Detecting means for detecting the toner density of the formed toner image;
Prediction means for predicting a toner density fluctuation amount based on the detected toner density and calculating a toner density fluctuation prediction quantity;
Display means for displaying the toner concentration fluctuation prediction amount to the user;
Selection means for allowing the user to select a condition for toner density adjustment timing based on the displayed toner density fluctuation prediction amount;
Adjusting means for adjusting the toner density based on the selected condition and the predicted fluctuation amount of the toner density;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the predicting unit calculates a predicted amount of change in toner density after the print job is executed.   The image forming apparatus according to claim 2, wherein the predicting unit calculates a predicted amount of fluctuation in toner density after executing the print job based on an image density and the number of printed sheets of the toner image formed by the print job. apparatus.   4. The method according to claim 1, wherein said selection means selects at least whether to perform automatically or set an allowable upper limit value of toner density variation as a condition for toner density adjustment timing. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the display unit further displays a time required for the print job.   6. The image forming apparatus according to claim 1, wherein the display unit displays the updated toner density fluctuation prediction amount during execution of the print job. Detecting the toner density of the toner image formed by the toner image forming means;
Based on the detected toner density, the toner density fluctuation amount is predicted to calculate the toner density fluctuation prediction quantity,
Displaying the toner density fluctuation prediction amount to the user;
Obtaining selection information that allows the user to select a condition for the toner density adjustment timing based on the displayed toner density fluctuation prediction amount;
An image forming method, wherein a toner density is adjusted based on the selection information and a predicted fluctuation amount of the toner density.

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