JP2016051086A - Image formation device, and control method and computer program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of trouble which may be caused when correction processing is performed in timing which is uniformly set without reference to kinds of execution conditions of the correction processing.SOLUTION: An image formation device comprises an image formation part and a control part which executes correction processing for correcting image formation characteristics of the image formation part. The control part executes the correction processing without waiting a next image formation instruction to be accepted when determining that operation quantity conditions including a condition that an operation quantity index value of a predetermined component constituting the image formation part based upon execution time of last correction processing is larger than a first threshold are met, and executes the correction processing before an image formation operation according to the image formation instruction is completed when determining that the image formation instruction is accepted and an environmental condition that a quantity of variation in predetermined environment index value based upon the execution time of the last correction processing is larger than a second threshold is met.SELECTED DRAWING: Figure 5

Description

  The technology disclosed in this specification relates to an image forming apparatus.

  In an image forming apparatus, for example, when an environment such as temperature fluctuates greatly or an operation amount of a component such as a developing roller exceeds a certain level, image forming characteristics such as density characteristics may change. For this reason, there is known an image forming apparatus that executes correction processing for correcting image forming characteristics when a preset condition is satisfied (see, for example, Patent Document 1).

JP 2000-190573 A

  The conditions for executing the correction process include, for example, a condition that the fluctuation amount of the environmental index value based on the previous correction process is larger than a threshold value, and a component based on the previous correction process execution. Various conditions are conceivable, such as a condition that the motion amount index value is larger than the threshold value. In the above conventional technique, the correction process is executed at a uniformly set timing regardless of the type of execution condition of the correction process. For this reason, if it is assumed that the condition is periodically determined and the correction process is performed immediately when it is determined that the condition is satisfied, depending on the type of the condition, the next image formation is performed after the correction process is performed. Until the operation is executed, it is determined that the condition is satisfied again, and the correction process may be executed. Thus, the correction process executed previously may be wasted. Further, if it is determined that the condition is satisfied and correction processing is executed in response to reception of an instruction for the next image forming operation, the start time of the image forming operation in accordance with the instruction for the image forming operation, The completion time may be delayed by the time required for the correction process, and convenience may be reduced. As described above, there is a possibility that inconvenience may occur when the correction process is executed at a uniformly set timing regardless of the type of execution condition of the correction process.

  In this specification, the technique which can solve the subject mentioned above is disclosed.

(1) An image forming apparatus disclosed in the present specification includes an image forming unit, and a control unit that executes a correction process for correcting image forming characteristics of the image forming unit. Determining whether or not an operation amount condition including a condition that an operation amount index value of a predetermined component constituting the image forming unit based on the execution time of the correction process is greater than a first threshold is satisfied; When it is determined that the operation amount condition is satisfied, the correction process is executed without waiting for the next image formation instruction to cause the image forming unit to execute an image forming operation, and the image formation instruction is received. And the environmental condition that the variation amount of the predetermined environmental index value based on the previous execution of the correction process is larger than a second threshold is satisfied, and the environmental condition Is determined to be satisfied, The correction processing is executed and before the completion of the according to the serial image forming instruction the image forming operation. The environmental condition that the fluctuation amount of the environmental index value based on the execution time of the previous correction process is larger than the threshold is the movement amount condition that the movement quantity index value based on the execution time of the previous correction process is larger than the threshold value. In comparison, after the conditions are satisfied once and correction processing is executed, there is a relatively high possibility that the conditions will be satisfied again in the period until the next image formation instruction is received. This is because the fluctuation (increase) in the amount of movement of the component is likely to be caused by the image forming apparatus periodically or by the user intentionally operating the component, whereas the fluctuation of the environment is not. This is because it is highly likely to occur regularly. In this image forming apparatus, regarding such environmental conditions, when an image forming instruction for causing the image forming unit to perform an image forming operation is received and it is determined that the environmental conditions are satisfied, the image forming apparatus Correction processing is executed before the completion of the image forming operation according to the forming instruction. That is, in this case, the correction process is executed before the start of the image forming operation according to the image forming instruction or in the middle of the image forming operation. Therefore, in this image forming apparatus, after the environmental condition is satisfied and the correction process is executed, the possibility that the environmental condition is satisfied again can be extremely reduced before the next image forming operation is executed. Occurrence of a situation where the corrected processing is wasted can be suppressed. On the other hand, the operation amount condition is a condition that is relatively unlikely to be satisfied again in a period until the next image formation instruction is received after the correction processing is executed once it is satisfied, compared with the environmental condition. Therefore, in this image forming apparatus, for such an operation amount condition, when it is determined that the operation amount condition is satisfied, correction processing is performed without waiting for reception of the next image formation instruction, thereby performing the following. It is possible to prevent the start time and completion time of the image forming operation corresponding to the image forming instruction from being delayed.

(2) In the image forming apparatus, the control unit may determine whether or not the environmental condition is satisfied according to reception of the image forming instruction. If the determination whether or not the environmental condition is satisfied is executed before the reception of the image formation instruction, the environmental condition is satisfied before the reception of the image formation instruction after it is determined that the environmental condition is satisfied. However, in this image forming apparatus, the determination as to whether or not the environmental condition is satisfied is executed in response to the reception of the image forming instruction. The occurrence of such a situation can be suppressed.

(3) In the image forming apparatus, the image forming unit includes the replaceable specific part, and the operation amount condition is based on a time when the specific part is installed in the image forming apparatus. It may be configured to include a condition that the operation index value of a specific part is smaller than a third threshold set based on the replacement time of the specific part. In the image forming apparatus, correction processing may be executed at the timing when a specific part reaches the end of its life and is replaced. In this image forming apparatus, the motion amount index value of the specific component based on the previous correction processing execution is larger than the first threshold value, and the specific component is installed on the image forming apparatus. Since the operation amount condition is satisfied when the operation amount index value of the specific component is smaller than the third threshold set based on the replacement time of the specific component, correction processing is performed when the replacement time of the specific component is relatively far Is executed. For this reason, it is possible to suppress the occurrence of a situation in which the correction process executed in consideration of the replacement time of a specific part is wasted.

(4) In the image forming apparatus, the image forming unit includes at least one specific part that can be replaced, and the control unit is configured to use the at least one specific component based on the previous execution time of the correction process. When it is determined that the operation amount condition that the operation amount index value of the first specific component which is one of the specific components is greater than the first threshold is satisfied, the at least one Installation of a second specific part, which is one of the specific parts and is the same as the first specific part or different from the first specific part, to the image forming apparatus When it is determined that the operation amount index value of the second specific part with respect to time is equal to or more than a third threshold set based on the replacement time of the second specific part, The correction process in response to reception of the image formation instruction It may be configured to start. According to the image forming apparatus, it is determined that the operation amount condition that the operation amount index value of the first specific component is larger than the first threshold is satisfied, and the second specific component is When it is determined that the operation amount index value of the second specific component based on the time of installation in the image forming apparatus is equal to or greater than the third threshold set based on the replacement timing of the second specific component Since the correction process is started in response to reception of the next image formation instruction, the image formation process is performed after the correction process is executed even when the replacement time of the second specific component is relatively close. However, the occurrence of a situation where the replacement timing of the second specific part is reached without being executed once can be suppressed.

(5) In the image forming apparatus, when the control unit determines that the operation amount condition is satisfied, any one of the operation amount condition and the environmental condition before receiving the next image formation instruction. It is determined whether or not a presumed condition that is presumed to be satisfied is satisfied, and when it is determined that the presumed condition is satisfied, in response to reception of the next image forming instruction, The correction process may be started, and when it is determined that the estimation condition is not satisfied, the correction process may be started without waiting for reception of the next image formation instruction. According to the present image forming apparatus, after the operation amount condition is satisfied, the estimation condition that is presumed that either the operation amount condition or the environmental condition is satisfied before reception of the next image formation instruction is satisfied. If not, the correction process is started without waiting for reception of the next image formation instruction, so that the start time and completion time of the image formation operation corresponding to the next image formation instruction are prevented from being delayed. be able to. In addition, when the estimation condition is satisfied, the correction process is started in response to reception of the next image formation instruction. Therefore, after the correction process is executed, any correction is performed before reception of the next image formation instruction. Such a condition is satisfied and the correction process is executed again, and the occurrence of a situation where the previously executed correction process is wasted can be suppressed.

(6) In the image forming apparatus, when the control unit determines that the estimation condition is satisfied, the control unit executes the correction process before the image forming operation according to the next image forming instruction. It is good also as composition to do. According to the image forming apparatus, when it is determined that the estimation condition is satisfied, the correction process is performed before the image forming operation according to the next image formation instruction. After that, the entire image forming operation is executed by the image forming unit, and the image forming characteristics of the entire image forming operation can be improved.

(7) In the image forming apparatus, the estimation condition may be a condition that is estimated that the environmental condition is satisfied before reception of the next image formation instruction. According to the present image forming apparatus, after the operation amount condition is satisfied, when the estimation condition that the environmental condition is estimated to be satisfied before reception of the next image formation instruction is satisfied, the next image is satisfied. Since the correction process is started in response to reception of the formation instruction, it is possible to suppress the occurrence of a situation where the executed correction process is wasted.

(8) In the image forming apparatus, the estimation condition may include a condition that a fluctuation amount of the environmental index value per unit time is larger than a fourth threshold value. When the amount of fluctuation of the environmental index value per unit time is large, it is relatively likely that the environmental condition is satisfied before the next image formation instruction is accepted after it is determined that the operation amount condition is satisfied. In such an image forming apparatus, in such a case, it is determined that the estimation condition is satisfied, and correction processing is started in response to reception of the next image formation instruction. Therefore, the executed correction processing is wasted. The occurrence of the situation can be suppressed.

(9) In the image forming apparatus, the estimation condition is that a variation amount of the environmental index value based on a previous execution time of the correction process is larger than a fifth threshold and not more than the second threshold. It is good also as a structure including the conditions that it is. After it is determined that the operation amount condition is satisfied when the fluctuation amount of the environmental index value based on the execution time of the previous correction process is greater than the fifth threshold and less than or equal to the second threshold The environmental condition is relatively likely to be satisfied before the next image formation instruction is received. In this image forming apparatus, in such a case, it is determined that the estimation condition is satisfied and the next image is satisfied. Since the correction process is started in response to reception of the formation instruction, it is possible to suppress the occurrence of a situation where the executed correction process is wasted.

(10) In the image forming apparatus, the estimation condition may include a condition that an occurrence probability of reception of the image formation instruction is lower than a sixth threshold value. If the probability of receiving an image formation instruction is low, either the operation amount condition or the environmental condition may be satisfied before the next image formation instruction is received after the operation amount condition is satisfied In this case, the image forming apparatus determines that the estimation condition is satisfied and starts correction processing in response to reception of the next image formation instruction. Occurrence of a situation where processing is wasted can be suppressed.

(11) In the image forming apparatus, when the control unit determines that the estimation condition is satisfied and then determines that the estimation condition is not satisfied before receiving the next image formation instruction. Alternatively, the correction process may be started without waiting for reception of the next image formation instruction. According to the present image forming apparatus, when it is determined that the estimation condition is not satisfied after the determination that the estimation condition is satisfied, the next image formation instruction is received. Since the correction process is started without waiting, the start time and completion time of the image forming operation corresponding to the next image forming instruction are delayed while suppressing the occurrence of the situation where the executed correction process is wasted. Can be suppressed.

(12) In the image forming apparatus, the control unit determines that the estimation condition is satisfied and satisfies a condition that the number of the correction processes to be executed is less than a seventh threshold value. If it is determined, the correction processing may be started in response to reception of the next image formation instruction. According to this image forming apparatus, after the operation amount condition is satisfied, it is estimated that one of the operation amount condition and the environmental condition is satisfied before the next image formation instruction is received. However, if the number of correction processes scheduled to be executed is equal to or greater than the threshold value, the correction process is started without waiting for reception of the next image formation instruction. Accordingly, it is possible to prevent the start time and completion time of the image forming operation corresponding to the time from being delayed.

(13) In the image forming apparatus, the image forming unit can execute the image forming operation using a plurality of colorants, and the image forming instruction is the image using the colorants of a plurality of colors. A configuration that is an instruction of a forming operation may be employed. According to the present image forming apparatus, image formation using a plurality of colorants, in which the effect of the correction processing for correcting the image formation characteristics of the image forming portion is easily exhibited, as compared with an image forming operation using a single colorant. When the operation instruction is accepted and the environmental conditions are satisfied, the correction process is executed before the completion of the image forming operation according to the image forming instruction, so the effect of the correction process is reflected. Thus, it is possible to suppress the occurrence of a situation where the executed correction processing is wasted while enabling the image forming operation performed.

(14) In the image forming apparatus, the correction process may be a density correction process for correcting a density characteristic as the image forming characteristic. In this image forming apparatus, it is possible to suppress occurrence of a situation where the executed density correction process is wasted or an unnecessary density correction process is executed.

(15) According to another aspect of the present invention, an image forming apparatus includes: an image forming unit; and a control unit that performs a correction process for correcting image forming characteristics of the image forming unit. The control unit satisfies one of a plurality of predetermined conditions, and one of the plurality of predetermined conditions is received before reception of a next image formation instruction for causing the image forming unit to perform an image forming operation. One of the plurality of predetermined conditions is satisfied, when an estimation condition that is presumed to be satisfied is satisfied, and the correction process is started in response to reception of the next image formation instruction. If the estimation condition is not satisfied, the correction process is started without waiting for reception of the next image formation instruction. According to the present image forming apparatus, after a certain condition is satisfied, if a presumed condition that is presumed to satisfy a certain condition before reception of the next image forming instruction is not satisfied, the next image forming is performed. Since the correction process is started without waiting for the reception of the instruction, it is possible to prevent the start time and completion time of the image forming operation according to the next image forming instruction from being delayed. In addition, when the estimation condition is satisfied, the correction process is started in response to reception of the next image formation instruction. Therefore, after the correction process is executed, any correction is performed before reception of the next image formation instruction. Such a condition is satisfied and the correction process is executed again, and the occurrence of a situation where the previously executed correction process is wasted can be suppressed.

(16) An image forming apparatus according to another embodiment disclosed in the present specification executes an image forming unit and a correction process for correcting image forming characteristics of the image forming unit when a predetermined condition is satisfied. And the image forming unit has a replaceable specific part, and the predetermined condition is an operation amount index of the specific part based on the previous execution of the correction process. The operation amount index value of the specific part based on the time when the specific part is installed in the image forming apparatus is larger than the threshold value, and the threshold value is set based on the replacement time of the specific part. Including the operation amount condition of small. In the image forming apparatus, correction processing may be executed at the timing when a specific part reaches the end of its life and is replaced. Therefore, if the correction process is executed when the replacement time of a specific part is near, the correction process is executed again when the specific part is subsequently replaced, and the previous correction process may be wasted. In this image forming apparatus, the specific component movement amount index value based on the execution time of the previous correction process is larger than the threshold value, and the specific component is based on the installation time of the specific component in the image forming apparatus. When the operation amount index value is smaller than the threshold set based on the replacement time of a specific part, the correction process is executed assuming that the operation amount condition is satisfied. The correction process is executed when the operation amount of the specific part is large to some extent and the replacement time of the specific part is relatively far. For this reason, it is possible to suppress the occurrence of a situation in which the correction process executed in consideration of the replacement time of a specific part is wasted.

  The technology disclosed in the present specification can be realized in various forms, for example, an image forming apparatus, a control method for the image forming apparatus, and a computer for realizing the functions of these apparatuses or methods. The present invention can be realized in the form of a program, a non-temporary recording medium recording the computer program, and the like.

Explanatory drawing showing a schematic configuration of the printer 100 Explanatory drawing showing the electrical configuration of the printer 100 Explanatory drawing showing an outline of density correction Flow chart showing the flow of density correction control processing Timing chart of correction processing in the embodiment Timing chart of correction processing in the embodiment Timing chart of correction processing in comparative example Timing chart of correction processing in comparative example Flowchart showing the flow of density correction control processing in another embodiment Timing chart of correction processing in another embodiment Timing chart of correction processing in comparative example

  A configuration of the printer 100 according to an embodiment will be described with reference to FIGS. 1 and 2. The printer 100 is a direct transfer tandem system that forms an image on a sheet W such as a recording sheet or an OHP sheet using toners of four colors, for example, black (K), yellow (Y), magenta (M), and cyan (C). This is an electrophotographic image forming apparatus. In the following description, when each component of the printer 100 is distinguished for each toner color, the letters K, Y, M, and C, which represent the above-described colors, are added to the end of the component codes. In other cases, these characters are omitted as appropriate. Moreover, in each figure, the code | symbol of the component of the same structure provided corresponding to each color shall be attached | subjected typically to the component corresponding to a certain color, and it abbreviate | omits suitably about the component corresponding to another color.

  As shown in FIG. 1, the printer 100 includes a sheet supply unit 120, a sheet conveyance unit 130, and an image forming unit 200.

  The sheet supply unit 120 includes a tray 121 and a pickup roller 122. The tray 121 is a container that can store a plurality of sheets W. The pickup roller 122 takes out the sheet W stored in the tray 121 and sends it out toward the sheet conveyance unit 130.

  The sheet conveyance unit 130 includes a conveyance roller pair 131, a registration roller pair 132, a belt 133, a driven roller 134, a drive roller 135, and a discharge roller pair 136. The conveyance roller pair 131 conveys the sheet W supplied from the sheet supply unit 120 toward the registration roller pair 132. The registration roller pair 132 corrects the skew of the sheet W sent from the conveyance roller pair 131 and conveys the sheet W toward the belt 133. The belt 133 is an endless belt that spans between the driving roller 135 and the driven roller 134 and rotates as the driving roller 135 rotates. As the belt 133 rotates, the surface of the belt 133 that faces a plurality of photosensitive drums 222 (to be described later) (hereinafter referred to as “stretching surface”) is a direction in which the plurality of photosensitive drums 222 are arranged (substantially horizontal in this embodiment). Move to. Along with the movement of the tensioning surface of the belt 133, the sheet W sent from the registration roller pair 132 and placed on the tensioning surface of the belt 133 is also described later along the direction in which the plurality of photosensitive drums 222 are arranged. It is conveyed toward the fixing unit 230. The discharge roller pair 136 discharges the sheet W that has passed through the fixing unit 230 to the outside of the printer 100.

  The image forming unit 200 includes an exposure unit 210, four process units 220 (220K, 220Y, 220M, and 220C) corresponding to each color, and a fixing unit 230.

  The exposure unit 210 includes a laser light source corresponding to each color and a rotating polygon mirror (none of which are shown). For each color, a light beam L emitted from a laser light source is deflected by a rotating polygon mirror that is rotationally driven by a motor (not shown), and is irradiated toward the photosensitive drum 222. As a result, each photosensitive drum 222 is exposed, and an electrostatic latent image is formed on the surface of the photosensitive drum 222.

  The four process units 220 are arranged side by side in the conveyance direction of the sheet W by the belt 133 (substantially horizontal direction in the present embodiment). The configuration of the black process unit 220K will be described below. The configuration of the process units 220 of other colors is the same.

  The process unit 220K includes a charging unit 221, a photosensitive drum 222, a toner box 223, a developing roller 224, and a transfer roller 225. The photosensitive drum 222 rotates around an axis that is parallel to the stretched surface of the belt 133 and that is substantially perpendicular to the conveyance direction of the sheet W by the belt 133. The charging unit 221 charges the surface of the photosensitive drum 222 uniformly. The developing roller 224 supplies the toner in the toner box 223 onto the photosensitive drum 222, thereby developing the above-described electrostatic latent image formed on the photosensitive drum 222 by the exposure unit 210 to form a toner image. The transfer roller 225 is disposed so as to face the photosensitive drum 222 via the stretched surface of the belt 133, and the toner image formed on the photosensitive drum 222 is placed on the stretched surface of the belt 133. Transfer to the conveyed sheet W. In this embodiment, a black process unit 220K, a yellow process unit 220Y, a magenta process unit 220M, and a cyan process unit 220C are arranged in order from the upstream side to the downstream side in the conveyance direction of the sheet W. Therefore, a black toner image, a yellow toner image, a magenta toner image, and a cyan toner image are sequentially transferred onto the conveyed sheet W in a superimposed manner.

  In the printer 100 of the present embodiment, the toner box 223 and the developing roller 224 are configured as an integral cartridge, and the cartridge can be replaced through an opening that is opened and closed by an opening / closing cover (not shown). Yes. Further, the number of rotations of the developing roller 224 is counted by the CPU 111 which will be described later. When the number of rotations of the developing roller 224 reaches a preset number, the cartridge including the developing roller 224 has reached the replacement time. Are displayed on the touch panel of the operation unit 154 to be described later. When this display is made, the user needs to replace the cartridge including the developing roller 224. Further, the belt 133, the driven roller 134, the driving roller 135, and the transfer rollers 225 for each color are configured as one unit.

  The fixing unit 230 fixes the toner image on the sheet W by heating the toner image transferred to the sheet W while applying pressure. As a result, an image is formed on the sheet W.

  The printer 100 further includes a density sensor 144, a belt cleaner 142, and a temperature sensor 146. The density sensor 144 is a reflective optical sensor having a light source and a light receiving unit (not shown), and is arranged on the surface of the belt 133 (more specifically, the four process units 220 on the surface of the belt 133 along the rotation direction of the belt 133). It is arranged so as to oppose a position on the downstream side from a position opposing to. When light is emitted from the light source of the density sensor 144, the light reflected by the surface of the belt 133 enters the light receiving unit of the density sensor 144. The density sensor 144 outputs a signal corresponding to the intensity of the light incident on the light receiving unit. The CPU 111 described later measures the density of the surface of the belt 133 based on a signal output from the density sensor 144.

  The belt cleaner 142 is located on the surface of the belt 133 (more specifically, on the downstream side of the belt 133 in the rotational direction of the belt 133 from the position facing the concentration sensor 144, and on the four process units 220. The toner is attached to the belt 133 so as to be opposed to the upstream position). The toner attached to the belt 133 includes a later-described patch PA intentionally formed on the belt 133 in addition to the toner unintentionally attached to the belt 133.

  The temperature sensor 146 is disposed near an outside air intake (not shown) and outputs a signal corresponding to the temperature of the air at the position. The CPU 111 described later measures the temperature of air based on a signal output from the temperature sensor 146. The temperature sensor 146 is disposed at a position relatively far from the fixing unit 230.

  As shown in FIG. 2, the printer 100 includes an operation unit 154, a communication interface (IF) 152, and a controller 110 that controls the printer 100 in addition to the above-described sheet supply unit 120, sheet conveyance unit 130, and image forming unit 200. With.

  The operation unit 154 includes various buttons (for example, a power button to be described later for performing power on / off of the printer 100 as software) and a touch panel (none of which are illustrated) that accept user operations. The touch panel also functions as a display unit that displays various types of information. The communication interface 152 is hardware that communicates with an external device. The communication interface 152 is, for example, a network interface, a serial communication interface, a parallel communication interface, or the like. The printer 100 acquires image data to be printed from an external device via the communication interface 152.

  The controller 110 includes a CPU 111, a ROM 112, a RAM 113, a nonvolatile memory 114, and an ASIC (Application Specific Integrated Circuit) 115. The ROM 112 stores a program for controlling each unit of the printer 100, various settings, initial values, and the like. The RAM 113 is used as a work area when the CPU 111 executes various programs and as a temporary storage area for data. The nonvolatile memory 114 is a rewritable memory such as NVRAM, flash memory, HDD, or EEPROM. The ASIC 115 is a hardware circuit dedicated to image processing, for example. The CPU 111 controls each unit of the printer 100 in accordance with a program read from the ROM 112 and signals acquired from various sensors. The CPU 111 is an example of a control unit.

  For example, when the environment such as the temperature around or inside the printer 100 fluctuates greatly or the operation amount of a component such as the developing roller 224 exceeds a certain level, the density characteristics of the image forming unit 200 of the printer 100 change. There is a case. The change in density characteristics of the image forming unit 200 includes, for example, a change in toner adhesion amount. If the density characteristics of the image forming unit 200 change, an image is formed at a density different from the density of the image that should be originally formed, which is not preferable. For this reason, the CPU 111 of the printer 100 executes a correction process for correcting the density characteristics of the image forming unit 200 when a predetermined condition is satisfied. Specifically, as a correction process, the CPU 111 controls the image forming unit 200 to form a patch PA as shown in FIG. 3 on the surface of the belt 133, and the patch on the belt 133 is based on an output signal from the density sensor 144. The density of the portion where the PA is formed is measured, and various settings of the image forming unit 200 such as the developing bias in the developing roller 224 are changed based on the difference between the measured density and the assumed density. Note that the arrow in FIG. 3 indicates the moving direction of the belt 133. The density characteristics of the image forming unit 200 are an example of image forming characteristics.

  In this embodiment, two conditions of an operation amount condition and an environmental condition are set as execution conditions for the correction process. The operation amount condition is that the rotation speed ΔR of the developing roller 224 (hereinafter referred to as “the rotation speed ΔR of the developing roller 224”) based on the execution time of the previous correction process is larger than the first threshold Th1 (ΔR> Th1). ) And the number of rotations R of the developing roller 224 (hereinafter referred to as “the cumulative number of rotations of the developing roller 224”) when the developing roller 224 is installed in the printer 100 (that is, when the developing roller 224 is new). R ”) is smaller than the third threshold Th3 (R <Th3). The first threshold value Th1 is a developing roller when the relationship between the rotational speed ΔR of the developing roller 224 and the change in density characteristic of the image forming unit 200 is experimentally obtained, and the change amount of the density characteristic becomes an allowable upper limit value. It is set to the value of the rotational speed ΔR of 224. Further, the third threshold Th3 is set to a value slightly smaller than the cumulative rotation speed R of the developing roller 224 corresponding to a predetermined replacement time. When the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1, it is estimated that the density characteristic has changed to an unacceptable level, and thus correction processing is executed. However, in the printer 100 of this embodiment, the correction process is automatically executed when the developing roller 224 is replaced. Therefore, even when the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1, if the cumulative rotational speed R of the developing roller 224 is greater than or equal to the third threshold Th3, the replacement timing of the developing roller 224 Since the correction processing is executed when the developing roller 224 is replaced, it is determined that the operation amount condition is not satisfied. The developing roller 224 is an example of a predetermined component and a specific component (a first specific component and a second specific component), and the rotation speed of the developing roller 224 is an example of an operation amount index value. .

  Further, the environmental condition is a condition that the temperature fluctuation amount ΔT (hereinafter, simply referred to as “temperature fluctuation amount ΔT”) based on the execution time of the previous correction process is larger than the second threshold Th2 (ΔT> Th2). It is. The second threshold Th2 is a temperature fluctuation amount when the relationship between the temperature fluctuation amount ΔT and the density characteristic change of the image forming unit 200 is experimentally obtained, and the density characteristic change amount becomes an allowable upper limit value. It is set to the value of ΔT. When the temperature fluctuation amount ΔT is larger than the second threshold Th2, it is estimated that the density characteristic has changed to an unacceptable level, and thus correction processing is executed. The temperature is an example of an environmental index value.

  In the printer 100, density correction control processing for performing control related to the above-described density correction is executed. The density correction control process will be described with reference to FIG. The density correction control process is started when the power button of the printer 100 is turned on.

  When the density correction control process is started, the CPU 111 determines whether or not to execute a warm-up operation (S110). If it is determined that the warm-up operation is not performed (S110: NO), a print instruction has been accepted. (S150: NO), it is determined whether or not the power button is turned off (S190), and the power button is turned off. If it is determined that the process has not been performed (S190: NO), the process returns to step S110.

  For example, immediately after the power button of the printer 100 is turned on, the CPU 111 determines that a warm-up operation is to be performed (S110: YES), and causes each unit of the printer 100 to start the warm-up operation (S120). In the warm-up operation, for example, the developing roller 224 is rotated. The CPU 111 monitors whether the operation amount condition is satisfied during the warm-up operation. Specifically, the CPU 111 determines whether or not the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1 (S130), and the cumulative rotational speed R of the developing roller 224 is smaller than the third threshold Th3. It is determined whether or not (S132). The number of rotations of the developing roller 224 is counted by a counter and stored in a memory such as the nonvolatile memory 114 or the RAM 113. The CPU 111 refers to a flag that is set when the rotational speed ΔR of the developing roller 224 is greater than the first threshold Th1 or the cumulative rotational speed R of the developing roller 224 is greater than or equal to the third threshold Th3. Make a decision. If the CPU 111 does not determine that the rotational speed ΔR of the developing roller 224 is greater than the first threshold Th1 until the warm-up operation is completed (S130: NO), or the rotational speed ΔR of the developing roller 224 is the first However, if it is determined that the cumulative rotation speed R of the developing roller 224 is equal to or greater than the third threshold Th3 (S132: NO), the operation amount condition is satisfied. If not, the process proceeds to step S190 without executing the correction process described above. On the other hand, the CPU 111 determines that the rotational speed ΔR of the developing roller 224 is greater than the first threshold Th1 before the warm-up operation is completed (S130: YES), and the cumulative rotational speed R of the developing roller 224 is third. If it is determined that the threshold value Th3 is smaller than the threshold value Th3 (S132: YES), it is determined that the operation amount condition is satisfied, a correction process is executed after the warm-up operation is completed (S140), and the process proceeds to step S190.

  If the CPU 111 determines that the print instruction has been received (S150: YES) in the determination of whether or not the print instruction has been received (S150), the CPU 111 determines whether or not the temperature fluctuation amount ΔT is greater than the second threshold Th2. (S160). If the CPU 111 determines that the temperature fluctuation amount ΔT is equal to or less than the second threshold Th2 (S160: NO), the CPU 111 accepts that the environmental condition is not satisfied without executing the above-described correction processing. A printing operation according to the printing instruction is started (S180). In the example of the timing chart shown in FIG. 5, since it is determined that the environmental condition is not satisfied in the determination of the environmental condition executed in response to the reception of the print instruction PI1, the printing operation is performed without executing the correction process. Has been started.

  On the other hand, if the CPU 111 determines that the temperature fluctuation amount ΔT is greater than the second threshold Th2 (S160: YES), the CPU 111 executes the correction process (S170) after accepting that the environmental condition is satisfied. The printing operation according to the printing instruction is started (S180). In the example of the timing chart shown in FIG. 5, since it is determined that the environmental condition is satisfied in the determination of the environmental condition executed in response to the reception of the print instruction PI2, the correction process is executed, and then the printing operation is performed. Has been started.

  In the printing operation, the developing roller 224 is also rotated. The CPU 111 monitors whether or not the operation amount condition is satisfied during the printing operation, similarly to the above-described warm-up operation (S130 and S132). If the CPU 111 determines that the operation amount condition is satisfied before the printing operation is completed (S130: YES and S132: YES), the CPU 111 executes correction processing after the printing operation is completed (S140). Advances to step S190. In the example of the timing chart shown in FIG. 6, since it is determined that the environmental condition is not satisfied in the determination of the environmental condition executed in response to the reception of the print instruction PI3, the printing operation is performed without executing the correction process. Although it has been started, it is determined that the operation amount condition is satisfied before the printing operation is completed. Therefore, the correction process is executed after the printing operation is completed.

  On the other hand, if the CPU 111 determines that the operation amount condition is satisfied until the printing operation is completed (S130: NO or S132: NO), the process proceeds to step S190 without executing the correction process. In the example of the timing chart shown in FIG. 6, since it is determined that the environmental condition is not satisfied in the determination of the environmental condition executed in response to the reception of the print instruction PI4, the printing operation is performed without executing the correction process. Since it is not determined that the operation amount condition is satisfied until the printing operation is completed, the correction process is not executed even after the printing operation is completed.

  The CPU 111 repeatedly executes the above-described processing, and when the power button of the printer 100 is turned off (step S190: YES), the processing ends.

  In the printer 100 according to the present embodiment, the correction control process is executed as described above. Therefore, as described below, the start time and the completion time of the printing operation according to the print instruction are suppressed from being delayed, Occurrence of a situation where the executed correction process is wasted can be suppressed.

  The environmental condition that the temperature fluctuation amount ΔT is larger than the second threshold Th2 is a condition that is relatively likely to be satisfied again within a short period of time after the correction process is executed once it is satisfied. Therefore, if the determination timing of the environmental condition and the execution timing of the correction process are arbitrary timings, there is a possibility that the executed correction process is wasted. For example, as shown in the timing chart of the comparative example shown in FIG. 7, if the determination of the environmental condition is executed after the completion of the printing operation according to the print instruction PI1, it is determined that the environmental condition is satisfied in the determination. If so, correction processing 1 is executed. Thereafter, the determination of the environmental condition is performed in response to the reception of the next print instruction PI2, and if it is determined that the environmental condition is satisfied, the correction process is performed before the start of the printing operation according to the print instruction PI2. 2 is executed. Therefore, in the comparative example shown in FIG. 7, after the correction process 1 is executed, the correction process 2 is executed again before the next printing operation is executed, and the correction process 1 is wasted. Yes.

  On the other hand, in the printer 100 according to the present embodiment, as illustrated in FIG. 5, when the print instruction is received and it is determined that the environmental condition is satisfied, the printing according to the print instruction is performed. Correction processing is performed before the operation starts. Therefore, in 100 of this embodiment, after the environmental condition is satisfied and the correction process is executed, it is not determined that the environmental condition is satisfied again before the next printing operation is executed. Occurrence of a situation where the executed correction process is wasted can be suppressed.

  Further, as shown in the timing chart of the comparative example shown in FIG. 8, when it is determined that the operation amount condition is satisfied, the correction process is executed after waiting for reception of the next print instruction. The start time and completion time of the printing operation corresponding to the print instruction are delayed, and convenience is reduced. On the other hand, in the printer 100 of this embodiment, as illustrated in FIG. 6, when it is determined that the operation amount condition is satisfied, the next print instruction is performed after the print operation (or warm-up operation) is completed. The correction process is executed without waiting for the receipt of. For this reason, in the printer 100 of the present embodiment, it is possible to prevent the start time and completion time of the printing operation corresponding to the next print instruction from being delayed. In addition, the condition that the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1 among the operation amount conditions is satisfied once, and after the correction process is executed, the rotational speed ΔR of the developing roller 224 becomes zero. Since it is reset, it is a condition that is less likely to be satisfied again within a short period of time. Therefore, even if the correction process is executed without waiting for the reception of the next print instruction when it is determined that the operation amount condition is satisfied as in the present embodiment, the executed correction process is useless. Is unlikely.

  Note that in the printer 100 of the present embodiment, the determination as to whether or not the environmental condition is satisfied is executed in response to reception of a print instruction. If the determination whether or not the environmental condition is satisfied is executed before the reception of the print instruction, the environmental condition is not satisfied by the reception of the print instruction after the determination that the environmental condition is satisfied, There may occur a situation in which correction processing that is not originally necessary is executed. However, in 100 of the present embodiment, the determination as to whether or not the environmental condition is satisfied is executed in response to the reception of the print instruction, so that occurrence of such a situation can be suppressed.

  Next, another embodiment of the density correction control process will be described with reference to FIG. Of the steps in the flowchart shown in FIG. 9, those having the same contents as the steps in the flowchart shown in FIG.

 The density correction control process of another embodiment shown in FIG. 9 is different from the density correction control process of the embodiment shown in FIG. 4 in that steps S134, S142, S144, and S146 are executed. That is, in another embodiment shown in FIG. 9, when it is determined that the operation amount condition is satisfied (S130: YES and S132: YES), the CPU 111 determines whether the estimation condition Cp is satisfied. (S134).

 Here, the estimation condition Cp is set in advance as a condition that the environmental condition is estimated to be satisfied before the next print instruction is received. In the present embodiment, as the estimation condition Cp, the first estimation condition Cp1 that the temperature fluctuation amount per unit time is larger than the fourth threshold Th4, and the temperature fluctuation amount based on the execution time of the previous correction process. A second estimation condition Cp2 that ΔT is larger than the fifth threshold Th5 and equal to or smaller than the second threshold Th2 (Th5 <ΔT ≦ Th2) is set as an OR condition. The unit time is, for example, the past 5 minutes until the time of determination in S134. When the temperature fluctuation amount per unit time is larger than the fourth threshold Th4, the temperature fluctuation per unit time is larger than that when the temperature fluctuation amount is less than or equal to the fourth threshold Th4. It is considered that there is a relatively high possibility that the environmental condition that the temperature fluctuation amount ΔT based on the execution time of the previous correction process is larger than the second threshold value Th2 is satisfied before the next print instruction is received. The first estimation condition Cp1 is set. Further, when the temperature fluctuation amount ΔT is larger than the fifth threshold Th5 and equal to or smaller than the second threshold Th2 (Th5 <ΔT ≦ Th2), the temperature fluctuation amount ΔT is larger than the second threshold Th2. Although the environmental condition of large (ΔT> Th2) is not satisfied, the environmental condition is satisfied before the next print instruction is received as compared with the case where the temperature fluctuation amount ΔT is equal to or less than the fifth threshold Th5. Therefore, the second estimation condition Cp2 is set.

  If the CPU 111 determines that the estimation condition Cp is not satisfied (step S134: NO), it is unlikely that the environmental condition is satisfied before the next print instruction is received, and the correction process is executed. Since it is unlikely that it will be wasted, correction processing is started without waiting for reception of the next print instruction (S140).

  On the other hand, when the CPU 111 determines that the estimation condition Cp is satisfied (S134: YES), the CPU 111 determines whether a print instruction is received (S142), and when it determines that the print instruction is received (S142) (S142: NO), the process is returned to step S134 (S142: NO). If the CPU 111 determines in step S134 that the estimation condition Cp is not satisfied (step S134: NO), the CPU 111 starts the correction process without waiting for reception of the next print instruction (S140). If the CPU 111 determines in S142 that a print instruction has been received (S142: YES), the CPU 111 executes a correction process (S144), performs a printing operation after the correction process is completed (S146), and performs the process in step S190. Proceed to In the example of the timing chart shown in FIG. 10, since it is determined that the operation amount condition is satisfied and the estimation condition Cp is satisfied, correction processing is executed in response to reception of the print instruction PI2. The printing operation is performed after the correction process is completed. If the CPU 111 determines that the estimation condition Cp is not satisfied in the determination in S134 after the printing operation is started in S180 and before the completion of the printing operation (step S134: NO), it is currently executed. After completing the printing operation, the correction process is started without waiting for the next print instruction (S140). If the CPU 111 determines that a print instruction has been received in the determination of S142 after the printing operation is started in S180 and before the completion of the printing operation (step S142: YES), the currently executed printing operation After the completion of the correction process, the correction process is started (S140).

  As described above, in another embodiment illustrated in FIG. 9, when the CPU 111 determines that the operation amount condition is satisfied, it is estimated that the environmental condition is estimated to be satisfied before the next print instruction is received. It is determined whether or not Cp is satisfied, and when it is determined that the estimation condition Cp is not satisfied, the correction process is started without waiting for reception of the next print instruction. It is possible to prevent the start time and completion time of the printing operation from being delayed.

  Further, as shown in the timing chart of the comparative example shown in FIG. 11, when the correction process 1 is executed without waiting for the next print instruction PI2 when it is determined that the operation amount condition is satisfied, the correction process 1 is performed. Is executed, the environmental condition is satisfied before the next print instruction PI2 is received, and the correction process 2 is executed again, so that the previously executed correction process 1 may be wasted. . However, in another embodiment shown in FIG. 9, if the CPU 111 determines that the estimated condition Cp that is presumed to satisfy the environmental condition is satisfied before the next print instruction PI <b> 2 is received, Since the correction process 2 is started in response to the reception of the print instruction PI2, the occurrence of a situation where the correction process 1 is wasted can be suppressed.

  The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are possible. .

  The configuration of the printer 100 of the above embodiment is merely an example, and various modifications can be made. For example, in the above embodiment, the printer 100 performs printing using toners of four colors of black, yellow, magenta, and cyan. However, the types and the number of colors used for printing are not limited thereto. In the above embodiment, the printer 100 is a tandem printer that performs printing using the photosensitive drum 222 provided for each color. However, the printer 100 performs printing using one photosensitive drum that is common to each color. A rotary type printer (also called a four-cycle method when the number of colors is four) may be used. Moreover, in the said embodiment, although the exposure part 210 is a structure provided with a laser light source and a rotary polygon mirror, another structure may be sufficient like the structure provided with the linear LED light source corresponding to a scanning line. .

  In the above-described embodiment, a printer that forms an image using a plurality of colors of toner is described as an example of an image forming apparatus. However, as another example of an image forming apparatus, an image is formed using one color of toner. A monochrome printer to be formed is mentioned. The present invention is also applicable to such a monochrome printer.

  In the above-described embodiment, the processing executed by one CPU 111 may be executed by a combination of a plurality of CPUs, one or more ASICs, one or more CPUs, and one or more ASICs. In such a case, the execution subject of the above process is an example of a control unit. The controller 110 is a collective term for hardware used for controlling the printer 100, such as the CPU 111, and is not necessarily a single piece of hardware existing in the printer 100.

  The content of the density correction control process in the above embodiment is merely an example, and various modifications can be made. For example, in the above embodiment, the temperature near the outside air intake is adopted as the environmental index value in the environmental condition. However, the environmental index value may be set at another position (for example, a position near the rotary polygon mirror of the exposure unit 210). And other index values such as temperature at the position of the belt 133 and humidity at an arbitrary position.

  In the above embodiment, the rotation speed of the developing roller 224 is employed as the operation amount index value under the operation amount condition. However, the operation amount index value may be the rotation speed of the photosensitive drum 222. In this case, the photosensitive drum 222 is an example of a predetermined part and a specific part (a first specific part and a second specific part). In the above-described embodiment, the operation amount condition includes a condition that the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1, and a condition that the cumulative rotational speed R of the developing roller 224 is smaller than the third threshold Th3. However, the parts that are the target of determination of these two conditions may be different parts. For example, the operation amount condition may include a condition that the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1 and a condition that the cumulative rotational speed of the photosensitive drum 222 is smaller than the threshold. Further, the operation amount condition may include a condition that the rotational speed of the photosensitive drum 222 is larger than the threshold value and a condition that the cumulative rotational speed R of the developing roller 224 is smaller than the threshold value. The operation amount index value is another index value as long as it is an index value that correlates with the operation amount of the components constituting the image forming unit 200 of the printer 100, such as the cumulative usage time and the number of printed sheets of each unit of the printer 100. May be. Further, when the exposure unit 210 of the printer 100 has a linear LED light source, and the LED light source is attached to a cover that opens and closes the opening of the housing, the LED light source moves in accordance with the cover opening / closing operation. Alternatively, the operation amount index value may be the number of times the cover is opened and closed.

  In the above-described embodiment, the operation amount condition includes a condition that the rotational speed ΔR of the developing roller 224 is larger than the first threshold Th1, and a condition that the cumulative rotational speed R of the developing roller 224 is smaller than the third threshold Th3. However, the condition relating to the cumulative rotational speed R of the developing roller 224 may not be included, and the condition that the rotational speed ΔR of the developing roller 224 is simply greater than the first threshold Th1 may be used. In such a form, when it is determined that the operation amount condition that the rotation speed ΔR of the developing roller 224 is larger than the first threshold Th1 is satisfied, the cumulative rotation speed R of the developing roller 224 is the third rotation speed R. If the threshold value Th3 is determined to be greater than or equal to the threshold Th3, the correction process may be started in response to reception of the next print instruction. In this way, even when the replacement time of the developing roller 224 is relatively close, after the correction process is executed, the printing operation is not executed at all and the replacement time of the developing roller 224 is reached. Can be suppressed.

  In the above embodiment, the density characteristic of the image forming unit 200 is corrected by changing the developing bias in the developing roller 224 during the correction process. However, the voltage of the charging unit 221 and the exposure intensity of the exposing unit 210 are corrected. The density characteristics may be changed by changing the settings of other parts of the image forming unit 200.

  In the above embodiment, the determination whether or not the environmental condition is satisfied is executed in response to the reception of the print instruction. However, the determination whether or not the environmental condition is satisfied is based on the print instruction. It may be executed at a timing set independently of the reception timing. The determination of whether or not the operation amount condition is satisfied may be performed in response to reception of a print instruction, or may be performed at a timing set independently of the reception timing of the print instruction.

  Further, in each of the above embodiments, when it is determined that the operation amount condition is satisfied, the correction process is performed immediately after completion of the warm-up operation or the printing operation. However, the operation amount condition is satisfied. The execution timing of the correction processing when it is determined that the image is determined can be set to an arbitrary timing without waiting for the next image formation instruction.

  Further, in the above embodiment, the correction process executed in response to the reception of the print instruction is executed before the start of the print operation according to the print instruction, but after the start of the print operation according to the print instruction. It may be executed before completion. For example, when the print instruction includes instructions for monochrome printing and color printing, correction processing is executed after a part or all of the monochrome image printing operation is completed and before the color image printing operation is performed. Thereafter, the remaining printing operation may be executed.

  Further, the content of the estimation condition Cp in the embodiment shown in FIG. 9 is merely an example and can be variously modified. For example, the estimation condition Cp may be the first estimation condition Cp1 in which the temperature fluctuation amount per unit time is larger than the fourth threshold Th4, or the temperature based on the previous correction processing execution time. The second estimation condition Cp2 that the variation amount ΔT is larger than the fifth threshold Th5 and not more than the second threshold Th2 may be used, or an AND condition of both of them may be used.

  Further, the estimation condition Cp may include a condition that the occurrence probability of accepting a print instruction is lower than the sixth threshold Th6. When the probability of receiving a print instruction is lower than the sixth threshold Th6, it is likely that the time until the next print instruction is received is longer than when the print threshold is higher than the sixth threshold Th6. Since it is considered that there is a relatively high possibility that the environmental condition is satisfied before the next print instruction is received, such a condition may be used as the estimation condition Cp. Note that the CPU 111 can record a print instruction reception history and estimate the probability of a print instruction reception based on the print instruction reception history and the current date and time. Alternatively, an estimated value of the occurrence probability of accepting a print instruction according to the date and time may be set in advance. Specifically, for example, a relatively high occurrence probability may be set from 8:00 to 18:00 on weekdays, and a relatively low occurrence probability may be set for other time zones and holidays on weekdays.

  Further, when the CPU 111 determines that the estimation condition Cp is satisfied and determines that the condition that the number of correction processes scheduled to be executed is smaller than the seventh threshold Th7 is satisfied, the next printing is performed. Even when it is determined that the correction process is started in response to the reception of the instruction and the estimation condition Cp is satisfied, the condition that the number of correction processes scheduled to be executed is less than the seventh threshold Th7 is satisfied. If it is determined that there is no correction, the correction process may be started without waiting for reception of the next print instruction. If the number of correction processes scheduled to be executed is relatively large, if the correction process is started in response to reception of a print instruction, the start time and completion time of the printing operation according to the print instruction may be delayed. However, if the number of correction processes scheduled to be executed is less than the seventh threshold Th7, the start time and completion time of the printing operation are delayed even if the correction process is started in response to reception of the print instruction. It can be suppressed.

  In the embodiment shown in FIG. 9, the estimation condition Cp is a condition that the environmental condition is estimated to be satisfied before the next print instruction is received, but the estimation condition Cp is the next print instruction. It may be a condition that is presumed that either of the environmental condition and the operation amount condition is satisfied before the reception.

  In the embodiment shown in FIG. 9, the environmental condition and the operation amount condition are set as the execution conditions of the correction process, and the determination of the estimation condition Cp is executed when it is determined that the operation amount condition is satisfied. However, the execution form of the determination of the estimation condition Cp is not limited to this. For example, as the execution condition of the correction process, a plurality of conditions are set in advance without being limited to the environmental condition and the operation amount condition described above, and it is determined that one of the plurality of conditions is satisfied, and the following If it is determined that one of a plurality of conditions is presumed to be satisfied before the print instruction is received, the correction process starts in response to the next print instruction. If it is determined that one of the plurality of conditions is satisfied and the estimation condition Cp is not satisfied, the correction process is started without waiting for reception of the next print instruction. It may be done. According to the printer of this aspect, after a certain condition is satisfied, if a presumed condition that a certain condition is estimated to be satisfied before reception of the next print instruction is not satisfied, the next print instruction Since the correction process is started without waiting for reception, it is possible to prevent the start time and completion time of the printing operation according to the next print instruction from being delayed. Further, when the estimation condition is satisfied, the correction process is started in response to reception of the next print instruction. Therefore, after the correction process is executed, any one of the print instructions is received before reception of the next print instruction. It is possible to suppress the occurrence of a situation in which the correction process executed again when the condition is satisfied and the correction process executed previously is wasted.

  In the above-described embodiment, the description “execute correction processing” includes the formation of the patch PA, the measurement of the patch PA by the sensor, and the change of various settings of the image forming unit 200 based on the measurement result. However, the present invention is not limited to this, and it is assumed that the formation of the patch PA and the measurement of the patch PA are executed integrally, and various settings of the image forming unit 200 are changed after a while. Alternatively, various settings of the image forming unit 200 may not be changed. For example, a part or all of the printing operation according to the printing instruction may be executed between the formation of the patch PA and the measurement of the patch PA and the change of various settings of the image forming unit 200.

  In the above-described embodiment, the correction process is a density correction process that corrects a density characteristic that is one of the image formation characteristics of the image forming unit 200. However, the correction process may be a correction process that corrects other image formation characteristics. Good. For example, the correction process corrects the image forming position of each color, which is one of the image forming characteristics of the image forming unit 200, thereby suppressing the occurrence of color misregistration in which the image forming positions of the respective colors on the sheet W are shifted from each other. It may be a correction process.

DESCRIPTION OF SYMBOLS 100: Printer 111: CPU 144: Density sensor 146: Temperature sensor 200: Image formation part 220: Process part 222: Photosensitive drum 224: Developing roller

Claims (16)

An image forming unit;
A control unit that executes a correction process for correcting image forming characteristics of the image forming unit,
The controller is
It is determined whether or not an operation amount condition including a condition that an operation amount index value of a predetermined component constituting the image forming unit based on the previous execution time of the correction process is larger than a first threshold is satisfied. When the operation amount condition is determined to be satisfied, the correction processing is executed without waiting for reception of a next image formation instruction for causing the image forming unit to execute an image forming operation,
Whether or not the image forming instruction is accepted and an environmental condition that a variation amount of a predetermined environmental index value based on the previous execution of the correction process is larger than a second threshold is satisfied. An image forming apparatus configured to execute the correction process before the completion of the image forming operation according to the image forming instruction when it is determined that the environmental condition is satisfied. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the control unit determines whether or not the environmental condition is satisfied in response to reception of the image forming instruction. The image forming apparatus according to claim 1, wherein:
The image forming unit has a specific replaceable part,
The operation amount condition is a third condition in which the operation amount index value of the specific component based on the installation time of the specific component in the image forming apparatus is set based on the replacement time of the specific component. An image forming apparatus including a condition that it is smaller than a threshold value. The image forming apparatus according to claim 1, wherein:
The image forming unit has at least one specific part that can be replaced;
The control unit is configured such that the motion amount index value of a first specific component that is one of the at least one specific component based on the previous execution time of the correction process is greater than the first threshold value. It is determined that the operation amount condition is satisfied, and is one of the at least one specific part, the same as the first specific part, or the first specific part The operation amount index value of the second specific component based on the installation time of the second specific component, which is a component different from the component, in the image forming apparatus is the replacement timing of the second specific component. The image forming apparatus starts the correction process in response to reception of the next image formation instruction when it is determined that the value is equal to or greater than a third threshold set based on the above. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises:
When the control unit determines that the operation amount condition is satisfied, it is estimated that one of the operation amount condition and the environmental condition is satisfied before receiving the next image formation instruction. To determine whether the guessing condition is satisfied,
When it is determined that the estimation condition is satisfied, the correction process is started in response to reception of the next image formation instruction,
When it is determined that the estimation condition is not satisfied, the image forming apparatus starts the correction process without waiting for reception of the next image formation instruction. The image forming apparatus according to claim 5, wherein
When the control unit determines that the estimation condition is satisfied, the control unit executes the correction process before the image forming operation according to the next image forming instruction. The image forming apparatus according to claim 5, wherein:
The estimation condition is an image forming apparatus in which the environmental condition is estimated to be satisfied before the next image formation instruction is received. The image forming apparatus according to claim 7,
The estimation condition includes the condition that the variation amount of the environmental index value per unit time is larger than a fourth threshold value. The image forming apparatus according to claim 7 or 8, wherein
The estimation condition includes a condition that a fluctuation amount of the environmental index value based on the previous execution time of the correction process is larger than a fifth threshold and not more than the second threshold. apparatus. An image forming apparatus according to any one of claims 5 to 9,
The estimation condition includes an image forming apparatus including a condition that an occurrence probability of receiving the image forming instruction is lower than a sixth threshold. An image forming apparatus according to any one of claims 5 to 10, wherein
After determining that the estimation condition is satisfied, the control unit determines that the estimation condition is not satisfied before receiving the next image formation instruction. An image forming apparatus that starts the correction process without waiting for reception of the image. An image forming apparatus according to any one of claims 5 to 11,
When the control unit determines that the estimation condition is satisfied and determines that the condition that the number of correction processes to be executed is less than a seventh threshold is satisfied, An image forming apparatus that starts the correction process in response to reception of the image forming instruction. An image forming apparatus according to any one of claims 1 to 12,
The image forming unit can execute the image forming operation using a plurality of colorants,
The image forming apparatus is an image forming apparatus that is an instruction for the image forming operation using the colorants of a plurality of colors. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises:
The image forming apparatus, wherein the correction process is a density correction process for correcting a density characteristic as the image forming characteristic. A method for controlling an image forming apparatus including an image forming unit,
An operation amount including a condition that an operation amount index value of a predetermined component constituting the image forming unit is larger than a first threshold with reference to the execution time of a correction process for correcting the image forming characteristic of the image forming unit last time. It is determined whether or not the condition is satisfied, and when it is determined that the operation amount condition is satisfied, the image forming unit performs the image forming operation without waiting for reception of the next image forming instruction. Executing the correction process;
Whether or not the image forming instruction is accepted and an environmental condition that a variation amount of a predetermined environmental index value based on the previous execution of the correction process is larger than a second threshold is satisfied. And a step of executing the correction process before the completion of the image forming operation according to the image forming instruction when it is determined that the environmental condition is satisfied. A computer program for controlling an image forming apparatus including an image forming unit,
An operation amount including a condition that an operation amount index value of a predetermined component constituting the image forming unit is larger than a first threshold with reference to the execution time of a correction process for correcting the image forming characteristic of the image forming unit last time. It is determined whether or not the condition is satisfied, and when it is determined that the operation amount condition is satisfied, the image forming unit performs the image forming operation without waiting for reception of the next image forming instruction. A process of executing the correction process;
Whether or not the image forming instruction is accepted and an environmental condition that a variation amount of a predetermined environmental index value based on the previous execution of the correction process is larger than a second threshold is satisfied. Determining that the environmental conditions are satisfied, causing the image forming apparatus to execute a process of executing the correction process before the completion of the image forming operation in accordance with the image forming instruction. , Computer program.

Images