JP2014215573A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of a situation where image formation based on formation instructions is not started until all the plurality of types of pre-processing are completed satisfying execution conditions when the formation instructions are received.SOLUTION: A printer 1 determines, when an operation unit 90 receives print instructions, whether or not the print instructions satisfy postponement conditions including satisfying at least position acquisition execution conditions and density acquisition execution conditions, and if determined that the print instructions satisfy the postponement conditions, executes a part of position acquisition processing and density acquisition processing during a pre-formation period from the reception of the print instructions until the start of sheet print processing, and executes the rest of the part after the completion of the sheet print processing.

Description

  The present invention relates to an image forming apparatus capable of executing a plurality of pre-processing before image formation based on a formation instruction.

  2. Description of the Related Art Conventionally, there is an image forming apparatus capable of executing misregistration correction control and density correction control as a plurality of preliminary processes (see Patent Document 1). Specifically, the image forming apparatus includes an intermediate transfer belt and an optical sensor. In the misregistration correction control, the image forming apparatus forms a misregistration correction pattern on the intermediate transfer belt, and acquires the position of the misregistration correction pattern from the detection result of the misregistration correction pattern by the optical sensor. In the density correction control, the image forming apparatus forms a density correction pattern on the intermediate transfer belt, and acquires the density of the density correction pattern from the detection result of the density correction pattern by the optical sensor.

  In this image forming apparatus, it is assumed that performing both the misregistration correction control and the density correction control at a time can be shortened in terms of time as compared with performing individually at different timings under different conditions. Therefore, this image forming apparatus executes both the positional deviation correction control and the density correction control when the positional deviation correction execution condition is satisfied and the density correction execution condition is not satisfied but is within the allowable range.

JP 2010-113286 A

  However, in the above-described conventional image forming apparatus, the positional deviation correction control is executed and the density correction is performed on condition that the positional deviation correction execution condition is satisfied and, for example, a target image formation instruction based on a user input operation is received. When the density correction control is executed on the condition that the execution condition is satisfied and the target image formation instruction based on the input operation of the user is received, the following inconvenience occurs. That is, in such an image forming apparatus, when both the positional deviation correction execution condition and the density correction execution condition are satisfied when the formation instruction is received, the execution of the positional deviation correction control and the density correction control is completed. Until the formation of the target image is not started, the user may wait for a long time. Note that the preliminary processing is not limited to misregistration correction control and density correction control, and includes various processes such as the cleaning process for the intermediate transfer belt and the detection sensitivity adjustment process for the optical sensor.

  In the present specification, a technique capable of suppressing the occurrence of a situation in which image formation based on a formation instruction is not started until a plurality of pre-processing satisfying an execution condition is completed when the formation instruction is received. Is disclosed.

  An image forming apparatus disclosed in this specification performs a first operation and a second operation on a carrier, an image forming unit that forms an image on the carrier, a reception unit that receives a formation instruction, and the carrier. An operation unit, and a control unit, wherein the control unit accepts the formation instruction and satisfies the first execution condition before the image formation based on the formation instruction is started. Before the start of image formation based on the formation instruction, on the condition that the operation unit performs the first operation and the reception unit receives the formation instruction and satisfies a second execution condition. And a second pre-processing for causing the operation unit to execute the second operation, and when the accepting unit accepts the formation instruction, the advance condition includes at least the first execution condition and the second execution condition. Satisfaction If the condition determination process for determining whether or not the advance condition is satisfied in the condition determination process, during the first half of the formation period from when the formation instruction is received to before the start of image formation based on the formation instruction, A forward process for executing a part of the first pre-process and the second pre-process, and executing the remaining part of the first pre-process and the second pre-process after the end of image formation based on the formation instruction; It has the structure which performs.

  When the accepting unit accepts the formation instruction, the image forming apparatus determines whether the advance condition including at least the first execution condition and the second execution condition is satisfied, and determines that the advance condition is satisfied. In this case, a part of the first pre-processing and the second pre-processing is executed during the first half of the forming period from the time when the forming instruction is received until the start of image formation based on the forming instruction, and the rest of the first pre-processing and the second pre-processing is executed. This part is executed after the end of image formation based on the formation instruction. Accordingly, it is possible to suppress the occurrence of a situation in which image formation based on the formation instruction is not started until all of the plurality of preliminary processes that satisfy the execution condition when the formation instruction is received.

  In the image forming apparatus, the control unit has a configuration that performs a comparison process that compares a magnitude relationship between the satisfaction degree of the first execution condition and the satisfaction degree of the second execution condition, and in the advance processing, From the comparison result of the comparison process, a configuration may be adopted in which a pre-process with a high degree of satisfaction among the first pre-process and the second pre-process is preferentially executed during the first period of formation.

  In the advance processing, the image forming apparatus preferentially executes the pre-processing having a high degree of satisfaction among the first pre-processing and the second pre-processing, in other words, the pre-processing that is highly necessary to be executed. Thereby, it is possible to suppress the advance processing that is highly necessary to be executed.

  In the above-described image forming apparatus, the control unit has a configuration for executing unreached processing for setting a state that does not satisfy an execution condition corresponding to the remaining portion of the first execution condition and the second execution condition. Also good.

  This image forming apparatus is in a state in which the execution conditions corresponding to the remaining portions of the first execution condition and the second execution condition are not satisfied. Thereby, after execution of a part of the first pre-process and the second pre-process, the remaining part is prevented from being executed immediately, and the state where the remaining part is not executed is prevented from continuing. Can do.

  In the image forming apparatus, the operation unit includes a detection unit that detects an image formed on the carrier, and the control unit causes the image forming unit to form a first pattern image in the first preprocessing. The first characteristic is acquired for the first pattern image from the detection result obtained by causing the detection unit to detect the first pattern image as the first operation. In the second pre-processing, the reception unit issues the formation instruction. On the condition that the second execution condition is received and the second execution condition is satisfied, the image forming unit forms a second pattern image, and the detection unit detects the second pattern image as the second operation. The second pattern image may be configured to acquire a second characteristic different from the first characteristic.

  According to this image forming apparatus, there occurs a situation in which image formation based on the formation instruction is not started until all of the plurality of pre-processing (characteristic acquisition processes) satisfying the execution condition when the formation instruction is received. Can be suppressed.

  The image forming apparatus includes a measurement unit that measures a variable element value that varies at least one of the first characteristic and the second characteristic, and a change amount of the variable element value is determined in advance as the advance condition. It may include being less than the threshold value for the advance determination.

  According to this image forming apparatus, it is possible to prevent the advance processing from being executed even though the variable element value changes relatively greatly and it is highly necessary to execute the first pre-processing and the second pre-processing. be able to.

  In the image forming apparatus, the control unit does not satisfy the advance condition in the comparison process that compares the magnitude relationship between the satisfaction degree of the first execution condition and the satisfaction degree of the second execution condition and the condition determination process. If it is determined, from the comparison result of the comparison process, the pattern image formed by the pre-process with a small degree of satisfaction among the first pre-process and the second pre-process is changed to a pattern that shortens the time of the pre-process And a pattern change process to be executed.

  According to this image forming apparatus, when both the first pre-process and the second pre-process are executed without satisfying the advance condition, the first pre-process and the second pre-process are compared with the configuration in which neither pattern image is changed. The time required to complete the process can be shortened.

  In the image forming apparatus, the carrier is a transport body that transports an image formed by the image forming unit, and the control unit is configured to use a width of a pattern image in the transport direction of the transport body in the pattern change process. It may be configured to shorten the length.

  According to this image forming apparatus, the time required to complete the first pre-processing and the second pre-processing can be shortened by shortening the width of the pattern image in the transport direction of the transport body.

  In the image forming apparatus, in the first pre-processing and the second pre-processing, the specific density pattern image is formed in the image forming unit, and the density of the specific density pattern image is acquired from the detection result by the detection unit. Specific gradation acquisition processing, and forming a gradation density pattern image including a plurality of density marks having different gradations in the image forming unit, and acquiring the gradation of the gradation density pattern image from the detection result of the detection unit In the advance processing, the control unit executes the specific density acquisition process during the first half of the formation, and ends the image formation based on the formation instruction. It may be executed after that time.

  According to this image forming apparatus, when it is determined that the advance feed condition is satisfied, the gradation density acquisition process that requires a relatively long time can be postponed.

  In the image forming apparatus, the image forming unit forms an image using a single color image forming operation for forming an image using a colorant having only one specific color, and two or more colorants including the specific color. Non-monochromatic image forming operation can be executed, and in the first pre-processing and the second pre-processing, the pattern image of the specific color is formed in the image forming unit and the detection result by the detecting unit is used. A specific color density measurement process for acquiring the density of the pattern image of the specific color, and a pattern image of a color other than the specific color is formed in the image forming unit, and each of the other colors is detected from a detection result by the detection unit. A color density measurement process for acquiring a density of a color pattern image is included, and the control unit has a configuration for executing a monochrome determination process for determining whether the formation instruction instructs the monochrome image formation operation. And forward In the processing, when it is determined in the monochrome determination process that the formation instruction instructs the monochrome image forming operation, the specific color density acquisition process is executed during the first half of the formation, and the other color density acquisition process is set as the formation instruction. It may be executed after the end of the image formation based on.

  According to the image forming apparatus, when the advance condition is satisfied and the formation instruction instructs a single-color image formation operation, it takes a relatively long time, and other color density acquisition is not necessary for image formation based on the formation instruction. Processing can be postponed.

  The present invention can be realized in various modes such as an image forming apparatus, an image formation control adjustment method, a computer program for realizing the functions of these methods or apparatuses, and a recording medium on which the computer program is recorded. .

  According to the invention disclosed in this specification, there is a situation in which image formation based on the formation instruction is not started until all of the plurality of pre-processing that satisfy the execution condition are completed when the formation instruction is received. It is possible to suppress.

Sectional drawing which shows schematic structure of the printer of Embodiment 1. FIG. Block diagram schematically showing the electrical configuration of the printer Flow chart showing print control processing Flow chart showing postponing processing Schematic diagram showing position acquisition pattern Schematic diagram showing density acquisition pattern Flow chart showing non-advance processing Time chart when executing forward and non-forward processing The flowchart which shows the postponing process of Embodiment 2. The flowchart which shows the postponing process of Embodiment 3.

<Embodiment 1>
The printer 1 according to the first embodiment will be described with reference to FIGS. In the following description, the left side of FIG. 1 is the front side (F) of the printer 1, the front side of the paper is the right side (R) of the printer 1, and the upper side of the paper is the upper side (U) of the printer 1. In addition, a thick solid line in FIG.

  The printer 1 is an example of an image forming apparatus, and is a multiple transfer tandem color printer capable of performing monochrome printing and color printing. Monochrome printing is an example of a single-color image forming operation, and is printing in which a monochrome image is formed using toner of one specific color, for example, black K. Color printing is an example of a non-monochromatic image forming operation, and printing that forms a color image using toner of two or more colors including the specific color, for example, black K, yellow Y, magenta M, and cyan C. It is. When distinguishing each component or term of the printer 1 for each color, K (black), Y (yellow), M (magenta), C (cyan) meaning each color at the end of the code of the component or the like. ).

(Entire printer configuration)
As illustrated in FIG. 1, the printer 1 includes a casing 2 that includes a sheet storage unit 10, a conveyance unit 20, and an image forming unit 30.

  The casing 2 is formed in a substantially box shape as a whole, and an opening 2A is formed on an upper surface portion thereof. The casing 2 has a cover 2B. The rear end of the cover 2B is rotatably connected to the casing 2, and a closed posture for closing the opening 2A (see FIG. 1) and an opening for opening the opening 2A. It can be displaced to the posture. It should be noted that the belt unit 23 and the process units 33K to 33C, which will be described later, can be replaced by opening the cover 2B.

  The sheet storage unit 10 is provided at the bottom of the casing 2 and includes a tray 11 and a push-up member 12. The tray 11 can accommodate a plurality of sheets 3 (specifically, paper, OHP sheets, etc.) in a stack. The push-up member 12 is provided in the tray 11 and is configured to push up the front end side of the sheet 3 accommodated in the tray 11.

  The transport unit 20 includes a pickup roller 21 and a belt unit 23. The pickup roller 21 is provided above the front end of the tray 11, contacts the upper surface of the front end side of the sheet 3 pushed up by the push-up member 12, and is driven to rotate, whereby the sheets stacked on the uppermost position in the tray 11. 3 are conveyed one by one toward the belt unit 23.

  The belt unit 23 has a pair of support rollers 23 </ b> A and 23 </ b> B and a belt 24. The belt 24 is an example of a carrier and a conveyance body, has an annular shape, and is stretched between a pair of support rollers 23A and 23B. When the rear support roller 23B is rotationally driven, the belt 24 circulates in the clockwise direction on the paper surface, and conveys the sheet 3 placed on the upper surface thereof to the rear. The belt 24 is made of a resin material such as polycarbonate, and the surface thereof is mirror-finished. Inside the belt 24, four transfer rollers 34K to 34C constituting the image forming unit 30 are provided, and the respective transfer rollers 34K to 34C are arranged on the photosensitive members 40K to 40C of the respective process units 33K to 33C described later. On the other hand, they are arranged to face each other with the belt 24 interposed therebetween.

  The image forming unit 30 is provided above the belt unit 23 and includes four image forming units 31K, 31Y, 31M, and 31C corresponding to the respective colors of black, yellow, magenta, and cyan, and a fixing unit 50. The four image forming units 31K, 31Y, 31M, and 31C are arranged side by side along the conveying direction of the belt 24, in other words, the front-rear direction.

  The four image forming units 31K, 31Y, 31M, and 31C are assumed to have the same configuration and operation except that the toner colors are different. Hereinafter, the configuration and operation will be described by taking the image forming unit 31K as an example. The image forming unit 31 </ b> K forms a black toner image directly on the belt 24 or indirectly via the sheet 3. The image forming unit 31K includes an exposure unit 32K, a process unit 33K, and a transfer roller 34K.

  The exposure unit 32K includes a plurality of LEDs (not shown), and the plurality of LEDs are arranged in a line in the left-right direction of the printer 1. Therefore, in the printer 1, the left-right direction is the main scanning direction, and the front-rear direction is the sub-scanning direction. The exposure unit 32K performs light emission control based on image data to be formed, and performs exposure by irradiating light from the plurality of LEDs onto the surface of the opposing photoreceptor 40K.

  The process unit 33K includes a toner storage chamber 36, a supply roller 37, a developing roller 38, and a layer thickness regulating blade 39. The toner storage chamber 36 stores black toner as a colorant. The toner in the toner storage chamber 36 is supplied onto a supply roller 37, and the toner on the supply roller 37 is supplied to a developing roller 38. The toner is positively frictionally charged with the developing roller 38. The toner on the developing roller 38 is further frictionally charged with the layer thickness regulating blade 39 to be a thin layer having a constant thickness. The printer 1 is configured to be able to change the developing bias applied to the developing roller 38 by changing a bias correction value described later.

  The process unit 33K includes a photoreceptor 40K whose surface is covered with a positively chargeable photosensitive layer, and a scorotron charger 41. At the time of executing a sheet printing process and various acquisition processes described later, the photosensitive member 40K is rotationally driven, and accordingly, the surface of the photosensitive member 40K is uniformly positively charged by the charger 41. The positively charged portion is exposed by the exposure unit 32K, and an electrostatic latent image is formed on the surface of the photoreceptor 40K.

  Next, the toner on the developing roller 38 is supplied to the electrostatic latent image, whereby the electrostatic latent image is visualized to form a toner image. Thereafter, the toner image carried on the surface of the photoreceptor 40K is transferred to the transfer roller 34K while the sheet 3 passes through each transfer position between the photoreceptor 40K and the transfer roller 34K. The voltage is sequentially transferred onto the sheet 3 or the belt 24 by the voltage. The sheet 3 to which the toner image has been transferred is then conveyed to the fixing unit 50 where the toner image is thermally fixed, and then the sheet 3 is conveyed upward and discharged onto the upper surface of the casing 2.

  Further, the printer 1 includes a cleaning unit 60, a mark sensor 70, and a humidity sensor 71 in the casing 2. The cleaning unit 60 is provided below the belt unit 23 and collects toner (including a position acquisition pattern P1 and a density acquisition pattern P2 described later), paper dust, and the like attached to the surface of the belt 24.

  The mark sensor 70 is an example of an operation unit and a detection unit, and can perform a position detection operation and a density detection operation. The position detection operation is an example of a first operation, and the mark sensor 70 forms a plurality of marks constituting a position acquisition pattern P1 (an example of a first pattern image) formed on the belt 24 by the image forming unit 30. This is an operation for detecting the position of each of M1 in the sub-scanning direction (hereinafter, simply an example of a first characteristic called an image forming position). This detection result is used for a position correction process described later. The density detection operation is an example of a second operation, and the mark sensor 70 forms a plurality of marks M2 constituting a density acquisition pattern P2 (an example of a second pattern image) formed on the belt 24 by the image forming unit 30. This is an operation for detecting each image density (an example of the second characteristic). This detection result is used for a density correction process described later.

  Specifically, the mark sensor 70 is provided, for example, on the rear side of the belt 24, and detects the position of the mark M1 formed on the surface of the belt 24 and the image density of the mark M2 when various acquisition processes described later are executed. Then, the detection result is output to the control unit 80 described later. More specifically, the mark sensor 70 includes a light projecting unit 70A that emits light toward the detection position X set on the surface of the belt 24 and a light receiving unit 70B that receives reflected light from the detection position X. (See FIG. 5). The humidity sensor 71 is an example of a measurement unit, detects the humidity in the casing 2, and outputs the detection result to the control unit 80. Humidity is an example of a variable element value that fluctuates the image forming position and the image density.

(Electrical configuration of printer)
As shown in FIG. 2, the printer 1 includes a control unit 80, an operation unit 90, and a display unit 91 in addition to the conveyance unit 20, the image forming unit 30, the cleaning unit 60, the mark sensor 70, and the humidity sensor 71 described above. And a communication unit 92.

  The control unit 80 includes a CPU (Central Processing Unit) 81, a ROM 82, a RAM 83, and an ASIC (Application Specific Integrated Circuit) 84. The ROM 82 stores a program for executing print control processing, which will be described later, and a program for executing various operations of the printer 1. The CPU 81 controls each unit of the printer 1 according to a program read from the ROM 82. In addition to the ROM 82 and RAM 83, the medium for storing the various programs may be a non-volatile memory such as a CD-ROM, a hard disk device, or a flash memory. The ASIC 84 is a hardware circuit such as a dedicated image processing circuit.

  The operation unit 90 is an example of a reception unit, includes a plurality of buttons, and allows various input operations by the user, and gives an operation signal according to the input operation to the control unit 80. The display unit 91 includes a liquid crystal display, a lamp, and the like, and can display various setting screens, operation states of the printer 1, and the like. The communication unit 92 is an example of a reception unit, and can perform data communication with an external information processing apparatus (not shown) such as a personal computer via a communication line by wire or wireless. is there.

(Various acquisition processes and their execution conditions)
The controller 80 can execute position acquisition processing and density acquisition processing as will be described later.

(1) Position Acquisition Processing The position acquisition processing is an example of first pre-processing, and sheet printing processing is performed on the condition that the operation unit 90 or the communication unit 92 receives a print instruction and satisfies the position acquisition execution condition. Is a process of causing the image forming unit 30 to form the position acquisition pattern P1 on the belt 24 and causing the mark sensor 70 to execute the position detection operation before starting the above. The print instruction is an example of a formation instruction, and is an instruction for causing the printer 1 to execute sheet printing processing. Hereinafter, it is assumed that the print instruction includes print data of a target image, print condition information such as color printing or monochrome (single color) printing, and the like. The sheet printing process is a process for printing a target image designated by the user on the sheet 3, for example.

  The position acquisition execution condition is an example of a first execution condition, and is a requirement for the control unit 80 to issue an execution request for the position acquisition process. In the following, the print process is executed from the previous execution of the position acquisition process. It is assumed that the cumulative number of sheets 3 that have been executed (hereinafter simply referred to as the number of printed sheets α) has reached the specified number αth. The print number α and the specified number αth are stored in the RAM 83.

(2) Density Acquisition Processing The density acquisition processing is an example of second pre-processing, and sheet printing processing is performed on the condition that the operation unit 90 or the communication unit 92 receives a print instruction and satisfies the density acquisition execution condition. Is a process of causing the image forming unit 30 to form the density acquisition pattern P2 on the belt 24 and causing the mark sensor 70 to execute the density detection operation before the start of the above. The density acquisition execution condition is an example of a second execution condition, and is a requirement for the control unit 80 to issue an execution request for density acquisition processing. In the following description, the humidity β detected by the humidity sensor 71 is defined humidity. It is assumed that βth has been reached. The humidity β and the specified humidity βth are stored in the RAM 83.

(Print control process)
For example, when the printer 1 is powered on, the control unit 80 repeatedly executes the print control process shown in FIG. 3 at predetermined time intervals. Specifically, the CPU 81 first determines whether the operation unit 90 or the communication unit 92 has received a print instruction (S1). The CPU 81 can determine from the operation signal from the operation unit 90 whether or not the operation unit 90 has received a print instruction based on the user's input operation. From the signal from the communication unit 92, the communication unit 92 It can be determined whether a print instruction has been received from the information processing apparatus.

  If the CPU 81 determines that a print instruction has not been received (S1: NO), the CPU 81 ends the print control process, and starts the print control process again after a predetermined time. If the CPU 81 determines that a print instruction has been received (S1: YES), the CPU 81 determines whether color printing is designated from the print condition information included in the print instruction (S2).

  If the CPU 81 determines that color printing is not designated (S2: NO), the CPU 81 causes the image forming unit 30 to perform an operation for monochrome printing based on the print data included in the print instruction, and sets the number of prints α. Then, the number of sheets printed in the current sheet printing process is added (S3), and this printing control process is terminated. Since the monochrome printing is less affected by the image quality deterioration due to the positional deviation of the image formed by the image forming unit 30 and the density deviation of the image compared with the color printing, the control unit 80 acquires the position before starting the monochrome printing. Processing and density acquisition processing are not executed.

(1) Advance feed condition determination processing When the CPU 81 determines that color printing is designated (S2: YES), the CPU 81 executes advance feed condition determination processing (S4, S5). The advance condition determination process is an example of a condition determination process, and is a process for determining whether or not the advance condition including satisfying at least both the position acquisition execution condition and the density acquisition execution condition is satisfied.

  The CPU 81 determines whether or not both the position acquisition execution condition and the density acquisition execution condition are satisfied (S4). Specifically, the CPU 81 determines whether or not the number of printed sheets α has reached the specified number αth. If the determination is affirmative, the CPU 81 determines that the position acquisition execution condition is satisfied. If the determination is negative, the CPU 81 sets the position acquisition execution condition. Judge that it does not meet. Further, the CPU 81 determines whether or not the current humidity β has reached the specified humidity βth from the detection result of the humidity sensor 71, and when the determination is affirmative, it is determined that the concentration acquisition execution condition is satisfied, and the determination is negative It is determined that the density acquisition execution condition is not satisfied.

  When it is determined that both the position acquisition execution condition and the density acquisition execution condition are satisfied (S4: YES), the CPU 81 determines whether or not the amount of change in the humidity β is less than the advance determination threshold (S5). The amount of change in the humidity β may be, for example, the difference between the humidity detected at the previous execution of at least one of the position acquisition process and the density acquisition process and the humidity β detected this time, or a predetermined reference humidity and the current detection It may be a difference from the humidity β.

(2) Advance-feed process When the CPU 81 determines that both the position acquisition execution condition and the density acquisition execution condition are satisfied (S4: YES), and determines that the amount of change in the humidity β is less than the advance determination threshold ( S5: YES), that is, when it is determined that the pre-feed condition is satisfied, the pre-feed process shown in FIG. 4 is executed (S6). In the pre-feed process, only a part of the position acquisition process and the density acquisition process is executed in a pre-print period (an example of a pre-formation period) from when a print instruction is received until the sheet print process is executed based on the print instruction. The remaining portion is prohibited from being executed during the first half of printing and is executed after the end of the sheet printing process. In other words, the remaining portion is postponed. As a result, when both the position acquisition execution condition and the density acquisition execution condition are satisfied when the print instruction is received, a situation may occur in which the sheet printing process is not started until all of the position acquisition process and the density acquisition process are completed. Can be suppressed.

(2-1) Determination of the acquisition process to be postponed Specifically, the CPU 81 calculates the degree of satisfaction of each of the position acquisition execution condition and the density acquisition execution condition (S21). The degree of satisfaction of the position acquisition execution condition is a relative amount between a value correlated with the amount of positional deviation of the image formed by the image forming unit 30 and a threshold corresponding to the position acquisition execution condition, and more specifically, position acquisition. The degree of satisfaction of the execution condition may be a satisfaction rate (= α / αth) obtained by dividing the number of printed sheets α by a specified number αth, or a satisfaction difference (= α−αth) obtained by dividing the number of printed sheets α by subtraction.

  The degree of satisfaction of the density acquisition execution condition is a relative amount between a value correlated with the density deviation amount of the image formed by the image forming unit 30 and a threshold value corresponding to the density acquisition execution condition, and more specifically, the density acquisition. The satisfaction degree of the execution condition may be a satisfaction rate (= β / βth) obtained by dividing the humidity β by the specified humidity βth, or a satisfaction difference (= β−βth) obtained by dividing the specified humidity βth by subtraction from the humidity β. Here, a large degree of satisfaction means that it is highly necessary to execute the acquisition process and the correction process.

  Therefore, the CPU 81 determines whether or not the satisfaction degree of the position acquisition execution condition is larger than the satisfaction degree of the density acquisition execution condition from the calculation result in S21 (S22), and the postponement acquisition process is performed based on the comparison result. decide. This forward processing The processing of S21 and S22 is an example of comparison processing.

(2-2) Position Acquisition Process When the CPU 81 determines that the satisfaction level of the position acquisition execution condition is greater than the satisfaction level of the density acquisition execution condition (S22: YES), the position acquisition process is more than the density acquisition process. There is a high necessity for execution, in other words, the amount of positional deviation of an image has a greater influence on image quality than the amount of density deviation. For this reason, the position acquisition process (S23, S24) is preferentially executed within the period before printing. Thereby, it is possible to prevent the position acquisition process that is highly necessary to be executed from being postponed.

  Specifically, the CPU 81 causes the image forming unit 30 to form the position acquisition pattern P1 on the belt 24 (S23). Here, the CPU 81 reads the latest position correction value and density correction value stored in the RAM 83. This density correction value includes a gradation correction value (also referred to as a gamma correction value) and a bias correction value. The CPU 81 corrects the exposure timing of the photosensitive member 40 by the exposure unit 32 based on the position correction value, changes the gradation of the image data based on the gradation correction value, and further develops each developing roller based on the bias correction value. The image density is corrected by changing the developing bias value given to 38, and the position acquisition pattern P1 is formed. Accordingly, the position acquisition pattern P1 is formed in a state where the image forming position and the image density are corrected based on the latest position correction value and density correction value stored in the RAM 83.

  For example, as shown on the left side of FIG. 5, the position acquisition pattern P1 is a pattern in which a plurality of marks M1 that are longer in the main scanning direction than in the sub scanning direction are arranged at intervals in the sub scanning direction. The plurality of marks M1 includes a set of four marks M1K to M1C arranged in the order of black, yellow, magenta, and cyan, and a plurality of sets of marks M1K to M1C are arranged at intervals in the sub-scanning direction.

  When starting to form the position acquisition pattern P1 on the belt 24, the CPU 81 causes the mark sensor 70 to execute the position detection operation, and acquires information on the position of each mark M1 from the detection result (S24). Specifically, the CPU 81 detects the timing at which each mark M1 passes through the detection position X of the mark sensor 70 based on a signal from the mark sensor 70, and based on the result, the CPU 81 uses the black mark M1K as a reference. The position deviation in the sub-scanning direction of the color (corrected color) marks M1Y, M1M, and M1C is acquired.

  When the CPU 81 acquires the position deviation for all the sets of marks M1, the CPU 81 calculates the average value of all the sets for the position deviation of each correction color, and the amount of misregistration (color deviation) that is the difference between the average value and the reference deviation. The value is also updated by adding a value that cancels the amount) to the position correction value of each correction color stored in the RAM 83 (S25). The reference deviation is an ideal position deviation between the marks M1 where no color misregistration amount occurs.

  After the position correction value is updated, the CPU 81 executes an unreached process for making the state not satisfying the density acquisition execution condition (S26). Specifically, the CPU 81 executes density acquisition by performing at least one of making the current value of the humidity β smaller than the specified humidity βth and making the specified humidity βth larger than the current value of the humidity β. Make the condition not met. That is, the execution of the density acquisition process is prohibited within the period before printing, and is postponed after the end of the sheet printing process.

  Here, if the undelivered process is not executed, the following problem may occur. That is, for example, when it is desired to continuously execute a plurality of sheet printing processes based on a plurality of printing instructions in a short time, if the position acquisition process is executed in the advance processing before the sheet printing process based on one printing instruction, the number of printed sheets Since α is reset to zero (see S8 in FIG. 3), when the next print instruction is received, the position acquisition execution condition is not satisfied, but only the density acquisition condition is satisfied.

  Then, the density acquisition process is immediately executed before the sheet printing process based on the next printing instruction (S4: NO, S9: YES), and eventually, a plurality of sheet printing processes are continuously executed in a short time. There is a risk that it will not be possible. On the other hand, by executing the non-achieving process, the CPU 81 can suppress the continuous state where the density acquisition process is not performed while continuously executing a plurality of sheet printing processes in a short time. . Note that the CPU 81 may perform the unreached process before or in parallel with any of the processes of S23 to S25. When the CPU 81 executes the unreached process, the CPU 81 ends the final advance process and proceeds to S8.

  In S <b> 8, the CPU 81 causes the image forming unit 30 to perform an operation for color printing while correcting the image forming position and the image density based on the latest position correction value and density correction value stored in the RAM 83. The number of prints α is reset to zero, and this print control process is terminated.

(2-3) Density Acquisition Process When the CPU 81 determines that the satisfaction level of the position acquisition execution condition is not greater than the satisfaction level of the density acquisition execution condition (S22: NO), the density acquisition process is more preferable than the position acquisition process. In other words, the density deviation amount has a greater influence on the image quality than the image positional deviation amount. The density acquisition processing (S27, S28) is preferentially executed within the period before printing. Thereby, it is possible to prevent the density acquisition process that is highly necessary to be executed from being postponed.

  Specifically, the CPU 81 causes the image forming unit 30 to correct the image forming position and the image density based on the latest position correction value and the density correction value stored in the RAM 83, as in S23, and to obtain the density acquisition pattern. P2 is formed on the belt 24 (S27). For example, as shown on the left side of FIG. 6, the density acquisition pattern P2 includes a plurality of substantially rectangular marks M2 arranged at intervals in the sub-scanning direction, and has a predetermined density interval (for example, 20%). ) Has a gradation pattern composed of a plurality of marks M2 having different image densities for each color.

  When starting to form the density acquisition pattern P2 on the belt 24, the CPU 81 causes the mark sensor 70 to execute the density detection operation, and acquires information on the image density of each mark M2 from the detection result (S28). Specifically, the CPU 81 detects the amount of reflected light when each mark M2 passes the detection position X of the mark sensor 70 based on a signal from the mark sensor 70, and based on the result, the image density for each gradation pattern. To get.

  When the CPU 81 acquires the image density for all the marks M2, the CPU 83 stores the image density detection value of the mark M2 having a predetermined image density (for example, 100%) in the gradation pattern at a predetermined ideal density. By changing the stored bias correction value of each color, the value is updated (S29). Further, the CPU 81 adjusts the gradation characteristic of each color stored in the RAM 83 so that the change characteristic of the image density of the gradation pattern approximates the characteristic of the image density faithful to the image corresponding to the image data included in the print instruction. The value is updated by changing the correction value (S29).

  After updating the density correction value, the CPU 81 executes an unreached process for making the position acquisition execution condition unsatisfied (S30). Specifically, the CPU 81 performs at least one of making the current value of the printed sheet number α smaller than the specified sheet number αth and making the specified sheet number αth larger than the current value of the printed sheet number α. Make the acquisition execution condition not satisfied. That is, the execution of the density acquisition process is prohibited within the period before printing, and is postponed after the end of the sheet printing process. Thereby, it can suppress that the state where a position acquisition process is not performed continues forever, performing a forward-feed process. Note that the CPU 81 may perform the unreached process before or in parallel with any of the processes of S27 to S29. When the CPU 81 executes the unreached process, the CPU 81 ends the final advance process and proceeds to S8.

(3) Non-advance processing In S4 and S5 of FIG. 3, the CPU 81 determines that both the position acquisition execution condition and the density acquisition execution condition are satisfied (S4: YES), and the change amount of the humidity β is for the advance determination. When it is determined that the value is not less than the threshold (S5: NO), that is, when it is determined that the advance condition is not satisfied, the non-advance process shown in FIG. 7 is executed without executing the aforementioned advance process (S7).

  The non-advance processing is processing for executing both position acquisition processing and density acquisition processing as described below. As described above, even when both the position acquisition execution condition and the density acquisition execution condition are satisfied, if the change amount of the humidity β is relatively large, the image quality due to the image position deviation and density deviation formed by the image forming unit 30 is improved. The influence of the reduction is great, and there is a high need for performing position correction processing and density correction processing. For this purpose, a non-advance processing is executed. Thereby, although it is highly necessary to execute the position correction process and the density correction process, it is possible to prevent the advance process from being executed.

  Specifically, the CPU 81 determines whether or not reduction setting has been made (S41). The presence / absence of the reduction setting is stored in the RAM 83 in advance, and the CPU 81 is changed as appropriate based on, for example, an input operation by the user on the operation unit 90, processing in S43 and S44 described later, and the like. When the CPU 81 determines that the reduction setting has not been made (S41: NO), the CPU 81 calculates the degree of satisfaction of each of the position acquisition execution condition and the density acquisition execution condition (S42), as in S21 and S22. It is determined whether the satisfaction degree of the acquisition execution condition is larger than the satisfaction degree of the density acquisition execution condition (S43).

  When the CPU 81 determines that the satisfaction degree of the position acquisition execution condition is larger than the satisfaction degree of the density acquisition execution condition (S43: YES), the CPU 81 reduces the density acquisition pattern P2 (S44). When this reduction setting is made, the CPU 81 reduces the density acquisition pattern formed in the density acquisition processing (S46, S47) described later from the density acquisition pattern P2 shown on the left side of FIG. 6 to the right side of FIG. A pattern change process for changing to the density acquisition pattern P2S is executed. The reduced density acquisition pattern P2S is a pattern in which the time for density acquisition processing is shorter than that of the density acquisition pattern P2. Specifically, the number of gradations of the gradation pattern is smaller than that of the density acquisition pattern P2. In the drawing, a gradation pattern composed of three marks M2 having different image densities every 40% interval is illustrated.

  Thus, by changing from the density acquisition pattern P2 to the reduced density acquisition pattern P2S, the number of marks in the entire density acquisition pattern is reduced, and the time required for the density acquisition process is reduced accordingly. Therefore, compared with the configuration in which the density acquisition process is executed with the density acquisition pattern P2, it is possible to shorten the period from when the print instruction is received until the start of the sheet printing process.

  In addition, the image quality can be improved even in the configuration in which the tone correction processing is executed by the reduced density acquisition pattern P2S, compared to the configuration in which the tone correction processing itself is not executed. On the other hand, in the reduced density acquisition pattern P2S, the correction accuracy of the gradation correction processing can be lowered particularly by the number of gradations smaller than that of the density acquisition pattern P2. However, the satisfaction degree of the density acquisition execution condition is smaller than the satisfaction degree of the position acquisition execution condition. That is, the density acquisition process is less necessary to be executed than the position acquisition process. Therefore, it is possible to suppress the influence due to the reduction in correction accuracy compared to the configuration in which the density acquisition execution condition is satisfied when the degree of satisfaction of the density acquisition execution condition is larger than the satisfaction degree of the position acquisition execution condition.

  On the other hand, if the CPU 81 determines that the satisfaction degree of the position acquisition execution condition is not greater than the satisfaction degree of the density acquisition execution condition (S43: NO), the CPU 81 reduces the position acquisition pattern P1 (S45). When this reduction setting is made, the CPU 81 changes the position acquisition pattern formed in the later-described position acquisition processing (S49, S50) from the position acquisition pattern P1 shown on the left side of FIG. 5 to the reduced position acquisition pattern P1S. Pattern change processing to be executed. The reduced position acquisition pattern P1S is a pattern in which the time for the position acquisition process is shorter than that of the position acquisition pattern P1, and specifically, the number of marks is the same as that of the position acquisition pattern P1, The interval between the marks M1 is the same, but the width of the mark M1 in the sub-scanning direction is narrow.

  Thus, by changing from the position acquisition pattern P1 to the reduced position acquisition pattern P1S, the entire length of the position acquisition pattern is shortened, and the time required for the position acquisition process is shortened accordingly. Therefore, compared with the configuration in which the position acquisition process is executed with the position acquisition pattern P1, the period from when the print instruction is received to the start of execution of the sheet printing process can be shortened.

  Further, even in the configuration in which the position correction process is executed by the reduced position acquisition pattern P1S, the image quality can be improved as compared with the configuration in which the position correction process itself is not executed. On the other hand, in the reduced position acquisition pattern P1S, the position detection accuracy of the mark M1, and hence the correction accuracy of the position correction process, can be lowered by the amount that the width of the mark M1 in the sub-scanning direction is narrower than the position acquisition pattern P1. However, the satisfaction degree of the position acquisition execution condition is smaller than the satisfaction degree of the density acquisition execution condition. That is, the position acquisition process is less necessary to be executed than the density acquisition process. Therefore, it is possible to suppress the influence due to the reduction in correction accuracy compared to the configuration in which the degree of satisfaction of the position acquisition execution condition is set smaller when the satisfaction degree of the density acquisition execution condition is larger.

  After the reduction setting, the CPU 81 executes a density acquisition process and a density correction value update process (S46 to S48). In this density acquisition process and the like, although the density acquisition pattern used when the reduction setting is set differs, the density acquisition process and the density correction value update process (S27 to S29) in the above-described advance process are performed in other cases. It is the same. Next, the CPU 81 executes a position acquisition process and a position correction value update process (S49 to S51), ends the non-deferred transfer process, and proceeds to S8 of FIG. In this position acquisition process and the like, although the position acquisition pattern used when the reduction setting is set is different, the position acquisition process and the position correction value update process (S23 to S25) in the above-described advance process are performed in other cases. It is the same.

  If the CPU 81 determines in S41 in FIG. 7 that the reduction setting has already been made (S41: YES), the waiting time until the start of the sheet printing process is already shortened by the reduction setting. The process proceeds to S46 without further reduction setting. Note that the CPU 81 may execute the density acquisition process and the density correction value update process after the position acquisition process and the position correction value update process in the non-advance processing.

  In S4 of FIG. 3, when the CPU 81 determines that both the position acquisition execution condition and the density acquisition execution condition are not satisfied (S4: NO), the CPU 81 determines whether or not the density acquisition execution condition is satisfied (S9). If it is determined that the acquisition execution condition is satisfied (S9: YES), the density acquisition process and the density correction value update process (S10 to S12) are executed, and the process proceeds to S8. The density acquisition process and the like are the same as the density acquisition process and the density correction value update process (S27 to S29) in the above-described advance process.

  If the CPU 81 determines that the density acquisition execution condition is not satisfied (S9: NO), the CPU 81 determines whether the position acquisition execution condition is satisfied. If the CPU 81 determines that the position acquisition execution condition is satisfied, the position acquisition process and the position correction are performed. A value update process (S13 to S15) is executed, and the process proceeds to S8. This position acquisition process and the like are the same as the position acquisition process and the position correction value update process (S23 to S25) in the forward feed process. Although omitted in FIG. 3, when neither the position acquisition execution condition nor the density acquisition execution condition is satisfied, the CPU 81 proceeds to S8 without executing any of the position acquisition process and the density acquisition process.

(Effect of this embodiment)
According to the present embodiment, when the printer 1 receives a print instruction, when it determines that the position acquisition execution condition and the density acquisition execution condition are satisfied, the formation from the time when the print instruction is received until the start of the sheet printing process is performed. In the previous period, a part of the position acquisition process and the density acquisition process is executed, and the remaining part is executed after the end of the sheet printing process.

  Here, when the CPU 81 determines that both the position acquisition execution condition and the density acquisition execution condition are satisfied (S4: YES), and determines that the amount of change in the humidity β is less than the advance determination threshold (S5: YES) As shown in the middle part of FIG. 8, it is assumed that the sheet printing process is executed after both the position acquisition process and the density acquisition process are executed without executing the advance process. In this case, it is assumed that the waiting time from the printing instruction to the start of the sheet printing process is T2. On the other hand, in the above embodiment, the CPU 81 executes the position acquisition process by the advance process, for example, as shown in the upper part of FIG. 8, and executes the sheet printing process without executing the density acquisition process. As a result, the waiting time from the printing instruction to the start of the sheet printing process is T1 (<T2), and the waiting time can be shortened as compared with the configuration in which the advance processing is not executed.

  Further, when the CPU 81 determines that the amount of change in the humidity β is not less than the threshold value for the advance determination (S5: NO), the CPU 81 executes both the position acquisition process and the density acquisition process by the non-advance process. For example, as shown in the lower part of FIG. 8, the time required for the density acquisition process is shortened. For this reason, the waiting time becomes T3 (<T2), and the waiting time can be shortened compared with the case where the reduction setting is not made (see the middle part of the figure). As described above, according to the present embodiment, when a print instruction is received, a situation in which image formation based on the formation instruction does not start until all of the plurality of pre-processing that satisfy the execution condition is completed. It is possible to suppress.

<Embodiment 2>
FIG. 9 shows a second embodiment. The difference from the first embodiment lies in the contents of the advance processing, and the other points are the same as in the first embodiment. Therefore, the common portions are denoted by the same reference numerals as those in the first embodiment, and the duplicate description is omitted, and only different portions are described next.

  As shown in FIG. 9, the CPU 81 performs position acquisition processing and specific density acquisition processing in the post-transmission processing, and postpones the gradation density acquisition processing. The specific density acquisition process is a process for acquiring the image density for updating the above-described bias correction value, and the tone density acquisition process acquires the image density for updating the above-described tone correction value. Process.

  Specifically, the CPU 81 first causes the image forming unit 30 to form the position acquisition pattern P1 on the belt 24 (S61) and causes the mark sensor 70 to execute the position detection operation, as in S23 of FIG. The position deviation of each mark M1 is acquired from the detection result (S62). Next, the CPU 81 causes the mark sensor 70 to form a specific density acquisition pattern having only a mark M2 having a predetermined image density for each color on the belt 24 (S63), and performs an operation of detecting the density of each mark M2. The image density of each mark M2 is also acquired from the detection result (S64). The specific density acquisition pattern is, for example, a pattern having only 100% of the mark M2 in the density acquisition pattern P2 shown in FIG.

  When the CPU 81 acquires the position deviation and the image density for all sets of marks M1, the CPU 81 updates the values by adding to the position correction values of the respective correction colors stored in the RAM 83 as in S25 of FIG. 4 (S65). . Further, the CPU 81 updates the value by changing the bias correction value of each color stored in the RAM 83 so that the detected value of the image density of each color mark M1 becomes a predetermined ideal density (S63). ), The final advance processing is terminated.

  Thus, by delaying the tone density acquisition process that requires more time than the specific density acquisition process, the waiting time can be shortened while correcting the image density. Note that the gradation density acquisition process is subsequently executed when only the density acquisition execution condition is satisfied. In the present embodiment, the CPU 81 does not execute the unreached process, but may be configured to execute the unreached process.

<Embodiment 3>
FIG. 10 shows a third embodiment. The difference from the first embodiment lies in the contents of the advance processing, and the other points are the same as in the first embodiment. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, and a duplicate description is omitted. Only different parts will be described below. In this embodiment, in FIG. 3, when the CPU 81 determines that a print instruction has been received (S1: YES), the process of S2 is not executed, and either color printing or monochrome printing is designated. , It proceeds to S4. In S8, the CPU 81 also executes monochrome printing.

  As illustrated in FIG. 10, the CPU 81 performs density acquisition processing in the post-transmission process, and postpones the position acquisition process. Specifically, the CPU 81 determines whether or not monochrome printing is designated from the printing condition information included in the printing instruction (S71). When the CPU 81 determines that monochrome printing is designated (S71: YES), the CPU 81 causes the image forming unit 30 to form a monochrome density acquisition pattern on the belt 24 (S72). The monochromatic density acquisition pattern is a pattern including only the single color (for example, black) mark M2K in the above-described density acquisition pattern P2 (see FIG. 6).

  When the CPU 81 starts to form a monochrome density position acquisition pattern on the belt 24, the CPU 81 causes the mark sensor 70 to execute the density detection operation, and acquires the image density of the black mark M2K from the detection result (S73). Then, when the CPU 81 acquires the image density for all the marks M2K, the detected value of the image density of the mark M2K having a predetermined image density (for example, 100%) in the gradation pattern becomes a predetermined ideal density. The black bias correction value stored in the RAM 83 is changed to update the value (S74). In addition, the CPU 81 stores the black gradation stored in the RAM 83 so that the change characteristic of the image density of the gradation pattern approaches the characteristic of the image density faithful to the image corresponding to the image data included in the print instruction. By changing the correction value, the value is updated (S74), and the final advance processing is terminated.

  As a result, when monochrome printing is designated, it is possible to postpone the density acquisition processing for colors other than the blocks that are not necessary for the monochrome printing, thereby shortening the waiting time. If the CPU 81 determines that monochrome printing is not designated (S71: NO), the CPU 81 executes the processing from S27 to S29, and ends the final advance processing, as in the above embodiment. In this case, the CPU 81 may execute the density acquisition process and the correction process only for colors other than black.

<Other embodiments>
The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and includes, for example, the following various aspects.

  The image forming apparatus may be a multiple transfer type transfer body type or a multiple development type (multi-rotation type, single pass type) printer in addition to the multiple transfer type tandem type printer 1. In this case, the photosensitive member carries an electrostatic latent image and a toner image and is an example of a carrier, and a developing device and a charger are examples of an image forming unit.

  Further, the image forming apparatus may be a multiple transfer / intermediate transfer type (intermediate transfer body type / tandem type) printer. In this case, the intermediate transfer member and the photosensitive member carry the electrostatic latent image and the toner image, and are examples of the carrier, and the developing device and the charger are examples of the image forming unit. Further, the image forming apparatus may be another electrophotographic printer such as a polygon scanning method, or may be an ink jet printer.

  The “operation unit” is not limited to the mark sensor 70 and may include, for example, a cleaning unit 60 that performs a cleaning operation on the belt 24. In short, the “operation unit” may be anything that performs an operation on the carrier.

The “first operation and second operation” are not limited to the position detection operation and the density detection operation by the mark sensor 70, and may be the following operations, for example.
Detection operation of detecting the position of the mark in the main scanning direction by the mark sensor 70 Light receiving operation of reflected light from the belt 24 by an optical sensor such as the mark sensor 70 (the light reception result is detection of scratches on the belt 24 and sensitivity adjustment of the optical sensor) For use)
Cleaning operation by the cleaning unit 60

  The “first characteristic and second characteristic” are not limited to the image forming position and image density in the sub-scanning direction of the image, but may be the size (magnification) of the image.

  The “measuring unit” is not limited to the humidity sensor 71, but may be a temperature sensor, a timer that measures time, a sensor that counts the number of rotations of the belt 24, the photoconductor 40, and the like, a cover sensor that detects opening and closing of the cover 2B, and the like. In short, the “measurement unit” only needs to measure a variable element value that varies at least one of the first characteristic and the second characteristic.

  In addition to humidity, the variable element value may be the temperature in the casing 2, the power-off time of the printer 1, the number of times the cover 2B is opened and closed, and the like. In short, the variation element value may be a value that varies at least one of the image forming position and the image density of the image forming unit 30.

  In the above embodiment, the control unit 80 is configured to execute the print control process by one CPU and memory. However, the present invention is not limited to this, and the control unit 80 is configured to execute print control processing by a plurality of CPUs, to execute print control processing only by a hardware circuit such as the ASIC 84, or to execute print control processing by a CPU and hardware circuits. The structure to do may be sufficient. For example, the ASIC 84 may execute a part of the sheet printing process.

The preliminary process is not limited to the position acquisition process and the density acquisition process, and may be the following process.
A process for forming a pattern for detecting the position in the main scanning direction by the image forming unit 30 on the belt 24 and acquiring the position of the pattern in the main scanning direction by an optical sensor such as the mark sensor 70. Processing to collect the adhering matter on the surface Processing to cause the optical sensor to receive the reflected light from the belt 24 while rotating the belt 24 (the light reception result is used for sensitivity adjustment of the optical sensor, etc.)
The control unit 80 may be configured to execute three or more types of acquisition processes as the pre-process.

The position acquisition execution condition and the density acquisition execution condition may be conditions including at least one of the following conditions 1 to 6, for example. Note that it is preferable that the position acquisition execution condition and the density acquisition execution condition have values that correlate with the positional deviation amount and the density deviation amount of the image formed by the image forming unit 30 reach a predetermined threshold value.
Condition 1: The cover 2B has been opened more than the specified number of times. The control unit 80 can determine whether or not the above condition is satisfied from the detection result of a cover opening / closing sensor (not shown).
Condition 2: Elapsed time has reached a specified time since the previous execution of image forming position acquisition processing Condition 3: Temperature in casing 2 has reached a specified temperature Condition 4: Humidity in casing 2 has reached a specified temperature Condition 5: The number of sheets 3 printed since the execution of the previous image formation position acquisition process has exceeded the specified number of sheets Condition 6: The belt 24 and the photoconductor from the execution of the previous image formation position acquisition process 40 revolutions exceeded the specified number

  If the CPU 81 determines in the print control process of FIG. 3 that a print instruction has been received (S1: YES), the CPU 81 may proceed to S3 without determining whether or not color printing is designated without performing the determination in S2. .

  When the CPU 81 determines that both the position acquisition execution condition and the density acquisition execution condition are satisfied in the print control process of FIG. 3 (S4: YES), the CPU 81 determines the variable element value (humidity β) without making the determination of S5. Regardless, the process may proceed to S6. In short, the advance condition may be a condition including at least the position acquisition execution condition and the density acquisition execution condition.

  The CPU 81 may be configured to prohibit the execution of the acquisition process with the lower degree of satisfaction for a certain period instead of the unreached process such as S26.

  The CPU 81 does not have to execute S21 and S22 in the advance processing. For example, the CPU 81 may determine which of the position acquisition process and the density acquisition process is to be executed based on designation by the user via the operation unit 90 or based on a predetermined execution order.

  The CPU 81 updates only one of the bias correction value and the gradation correction value in the density correction value update process such as S29, and either one of the bias correction process or the gradation correction process in the sheet printing process or the like. Only one may be performed.

  The CPU 81 may have a configuration in which S42 and S43 are not executed in the non-advance processing. For example, the CPU 81 may determine which of the position acquisition pattern P1 and the density acquisition pattern P2 is to be reduced based on designation by the user via the operation unit 90 or based on a predetermined execution order. Further, the CPU 81 may reduce both the position acquisition pattern P1 and the density acquisition pattern P2.

  When the CPU 81 reduces the number of marks in the processes of S44 and S45, the number of marks of the patterns P1 and P2 is reduced or the width of the mark M in the sub-scanning direction is reduced. However, the present invention is not limited to this, and if the reduction setting is made, the CPU 81 may shorten the time required for various acquisition processes by narrowing the interval between the marks M in the sub-scanning direction.

  When the CPU 81 reduces the number of marks in the processes of S44 and S45, the number of marks of the patterns P1 and P2 is reduced or the width of the mark M in the sub-scanning direction is reduced. However, the present invention is not limited to this, and if the reduction setting is made, the CPU 81 may shorten the time required for various acquisition processes by narrowing the interval between the marks M in the sub-scanning direction.

  In the second embodiment, the CPU 81 may execute the gradation density acquisition process and advance the specific density acquisition process in the advance process.

  1: Printer 24: Belt 30: Image forming unit 70: Mark sensor 71: Humidity sensor 80: Control unit 90: Operation unit 92: Communication unit P1: Position acquisition pattern P2: Density acquisition pattern

Claims (9)

A carrier,
An image forming unit that forms an image on the carrier;
A reception unit for receiving a formation instruction;
An operation unit for performing a first operation and a second operation on the carrier;
A control unit,
The controller is
First pre-processing for causing the operation unit to execute the first operation before starting image formation based on the formation instruction, on condition that the reception unit receives the formation instruction and satisfies a first execution condition; ,
Second pre-processing for causing the operation unit to execute the second operation before starting image formation based on the formation instruction on condition that the reception unit receives the formation instruction and satisfies a second execution condition; ,
A condition determination process for determining whether or not a forward condition including at least the first execution condition and the second execution condition is satisfied when the reception unit receives the formation instruction;
If it is determined in the condition determination process that the forward feed condition is satisfied, the first pre-processing and the second pre-processing are performed during the formation first period from when the formation instruction is received to before the start of image formation based on the formation instruction. An image forming apparatus configured to execute a part of the first pre-processing and the second pre-processing to perform a post-feed process executed after the end of image formation based on the forming instruction. The image forming apparatus according to claim 1,
The controller is
A configuration for performing a comparison process for comparing a magnitude relationship between a satisfaction degree of the first execution condition and a satisfaction degree of the second execution condition;
In the advance processing, an image forming apparatus is configured to preferentially execute a pre-processing with a high degree of satisfaction among the first pre-processing and the second pre-processing from the comparison result of the comparison processing in the first half of the formation. . The image processing apparatus according to claim 1, wherein:
The controller is
An image forming apparatus configured to execute a non-reaching process for not satisfying an execution condition corresponding to the remaining portion of the first execution condition and the second execution condition. The image processing apparatus according to any one of claims 1 to 3,
The operation unit has a detection unit for detecting an image formed on the carrier,
The controller is
In the first pre-processing, a first pattern image is formed on the first pattern image based on a detection result obtained by causing the image forming unit to form a first pattern image and causing the detection unit to detect the first pattern image as the first operation. Get
In the second pre-processing, the image forming unit forms a second pattern image on the condition that the receiving unit receives the forming instruction and satisfies a second execution condition, and the detecting unit forms the second pattern image. An image forming apparatus configured to acquire a second characteristic different from the first characteristic for the second pattern image from a detection result obtained by detecting the second pattern image as an operation. The image forming apparatus according to claim 4,
A measurement unit that measures a variable element value that varies at least one of the first characteristic and the second characteristic;
The advance feed condition is an image forming apparatus including a change amount of the variable element value being less than a predetermined advance decision threshold. The image forming apparatus according to claim 4, wherein:
The controller is
A comparison process for comparing a magnitude relationship between the satisfaction degree of the first execution condition and the satisfaction degree of the second execution condition;
When it is determined that the advance condition is not satisfied in the condition determination process, a pattern image formed by a pre-process with a small degree of satisfaction among the first pre-process and the second pre-process is determined from the comparison result of the comparison process. An image forming apparatus comprising: a pattern changing process for changing to a pattern that shortens the preprocessing time. The image forming apparatus according to claim 6,
The carrier is a carrier that conveys an image formed by the image forming unit,
The controller is
In the pattern change process, the image forming apparatus is configured to shorten the width of the pattern image in the transport direction of the transport body. The image forming apparatus according to claim 6, wherein:
In the first pre-processing and the second pre-processing, a specific density acquisition process for forming a specific density pattern image in the image forming unit and acquiring a density of the specific density pattern image from a detection result by the detection unit, and , A gradation density acquisition process in which a gradation density pattern image including a plurality of density marks having different gradations is formed in the image forming unit, and the gradation of the gradation density pattern image is acquired from a detection result by the detection unit Contains
The controller is
The image forming apparatus, wherein in the advance-feed process, the specific density acquisition process is executed during the first formation period, and the gradation density acquisition process is executed after the end of image formation based on the formation instruction. The image forming apparatus according to any one of claims 6 to 8,
The image forming unit forms a single color image using a colorant having only one specific color, and a non-monochrome image formation operation that forms an image using two or more colorants including the specific color. And is executable
In the first pre-processing and the second pre-processing, a specific color density that causes the image forming unit to form the pattern image of the specific color and acquires the density of the pattern image of the specific color from the detection result by the detection unit. Measurement processing and other color density measurement processing for forming a pattern image of another color except the specific color in the image forming unit and acquiring the density of the pattern image of each other color from the detection result by the detection unit Contains
The controller is
A single color determination process for determining whether the formation instruction instructs the single-color image forming operation;
In the advance processing, when it is determined in the monochrome determination process that the formation instruction instructs the monochrome image forming operation, the specific color density acquisition process is executed during the first half of the formation, and the other color density acquisition process is performed. An image forming apparatus that is executed after the end of image formation based on an instruction.

Images