Image forming apparatus, control method, and storage medium

Abstract

To set a process condition suitable for a medium by reducing an influence of a measurement error when a physical property value of the medium is measured.SOLUTION: The image forming apparatus 1 includes the measurement unit 20 that measures the physical property value of the medium 9, the determination part 63 that determines the process condition based on the physical property value measured by the measurement unit 20, the job control part 64 that controls the image forming operation on the medium 9 by applying the determined process condition, and the storage part 51 that stores the physical property value measured by the measurement unit 20 and the process condition determined by the determination part 63 in association with each other. When the newly measured physical property value of the medium 9 is within a predetermined range with respect to the physical property value stored in the storage unit 51, the determination unit 63 determines the process conditions associated with the physical property value as the process conditions at the time of executing the job on the current medium 9.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, a control method, and a program, and more particularly to a technique for setting optimal process conditions in accordance with media used in an image forming apparatus. [Background technology]

[0002] In electrophotographic image forming apparatuses, process conditions such as process speed vary depending on the type of media. For example, in the case of media with a small basis weight, the image can be completely fixed to the media in the fixing device even if the media is transported at high speed. However, in the case of media with a large basis weight, if the media is transported at high speed, the fixing process cannot be performed sufficiently in the fixing device, and the image will not be completely fixed to the media. For this reason, conventional image forming apparatuses are configured to measure the basis weight of the media and set process conditions such as process speed (for example, see Patent Document 1).

[0003] However, measurement errors occur in the basis weight of media. If a measurement error occurs near the threshold at which the process conditions change, the process conditions may change even though the media is actually the same type. As a result, a low-speed transport is set as the process condition even though the media is actually capable of high-speed transport, resulting in a problem of reduced productivity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-97170 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus, a control method, and a program that enable the setting of appropriate process conditions by reducing the effects of measurement errors. [Means for solving the problem]

[0006] In order to achieve the above object, the invention of claim 1 is an image forming apparatus comprising a measurement unit that measures physical property values ​​of a media, a determination unit that determines process conditions based on the physical property values ​​measured by the measurement unit, a control unit that controls an image forming operation on the media by applying the process conditions determined by the determination unit, and a memory unit that stores the physical property values ​​measured by the measurement unit and the process conditions determined by the determination unit in association with each other, wherein the determination unit determines the process conditions associated with the physical property values ​​that fall within the predetermined range when the physical property values ​​of the media newly measured by the measurement unit are within a predetermined range of the physical property values ​​stored in the memory unit.

[0007] The invention of claim 2 is an image forming apparatus of claim 1, characterized in that the memory unit stores the physical property values ​​measured by the measurement unit in association with the process conditions determined by the determination unit when image formation on media is being performed by the control unit.

[0008] The invention of claim 3 is an image forming apparatus of claim 2, characterized in that the measurement unit measures the physical property values ​​of the transported media one by one when the control unit is performing image formation on the media, and the memory unit accumulates and stores the physical property values ​​of multiple media measured by the measurement unit while image formation is being performed.

[0009] The invention according to claim 4 is the image forming apparatus according to claim 1, wherein the measuring unit measures at least the basis weight of the medium as the physical property value of the medium.

[0010] The invention of claim 5 is the image forming apparatus of claim 1, characterized in that the measurement unit measures at least two physical property values ​​of the media from among the basis weight, thickness, moisture content, and size of the media.

[0011] The invention according to claim 6 is the image forming apparatus according to claim 1, characterized in that the process conditions include at least a process speed.

[0012] The invention of claim 7 is an image forming apparatus of claim 1, characterized in that the determination unit holds a threshold value for switching process conditions depending on the physical property value of the media, and when the physical property value of the media newly measured by the measurement unit is within a predetermined range of the threshold value, it determines whether the physical property value of the media measured by the measurement unit is within a predetermined range of the physical property value stored in the memory unit.

[0013] The invention of claim 8 is an image forming apparatus of claim 7, characterized in that, if the newly measured physical property value of the media is within a predetermined range of the threshold value, the measurement unit measures the physical property value of each piece of media being transported while the control unit is performing image formation on the media, and the memory unit stores the physical property value of the media measured by the measurement unit while image formation is being performed in association with the process conditions determined by the determination unit.

[0014] The invention of claim 9 is an image forming apparatus of claim 1, characterized in that the determination unit performs a significant difference test between the physical property values ​​of the media measured while image formation is being performed on the media after the image formation operation by the control unit has been completed and the physical property values ​​associated with the process conditions applied during image formation.

[0015] The invention of claim 10 is an image forming apparatus of claim 9, characterized in that when the determination unit determines that there is a significant difference in the significant difference test, the determination unit stores the physical property values ​​accumulated during image formation in the memory unit as physical property values ​​of new media.

[0016] The invention of claim 11 is an image forming apparatus of claim 9, characterized in that, when the determination unit determines that there is no significant difference in the significant difference test, it merges the set of physical property values ​​accumulated while image formation is being performed with the set of physical property values ​​associated with the process conditions applied during image formation.

[0017] The invention of claim 12 is an image forming apparatus according to claim 1, further comprising an environmental sensor that acquires environmental information, wherein the memory unit stores the physical property values ​​measured by the measurement unit, the process conditions determined by the determination unit, and the environmental information acquired by the environmental sensor in association with one another, and wherein when new physical property values ​​of media are measured by the measurement unit, the determination unit extracts a set of physical property values ​​measured under the same environmental conditions from the set of physical property values ​​stored in the memory unit based on the environmental information acquired by the environmental sensor, and determines whether the physical property values ​​of the media newly measured by the measurement unit are within a predetermined range relative to the set of extracted physical property values.

[0018] The invention of claim 13 is an image forming apparatus of claim 1, characterized in that when image formation on media is being performed by the control unit, the memory unit stores the physical property values ​​measured by the measurement unit, the process conditions determined by the determination unit, and information regarding the date of image formation in mutual association, and the determination unit extracts a set of physical property values ​​measured at the same time from the set of physical property values ​​stored in the memory unit based on the date when the physical property values ​​of the media were newly measured by the measurement unit, and determines whether the physical property values ​​of the media newly measured by the measurement unit are within a predetermined range with respect to the set of extracted physical property values.

[0019] The invention of claim 14 is a control method for an image forming device equipped with a measurement unit that measures physical property values ​​of media, comprising: a determination step of determining process conditions based on the physical property values ​​measured by the measurement unit; a control step of controlling an image forming operation on the media by applying the process conditions determined in the determination step; and a storage step of correlating the physical property values ​​measured by the measurement unit with the process conditions determined in the determination step and storing them in a predetermined storage unit, wherein the determination step is characterized in that, when the physical property values ​​of the media newly measured by the measurement unit are within a predetermined range of the physical property values ​​stored in the storage unit, the process conditions associated with the physical property values ​​within the predetermined range are determined.

[0020] The invention of claim 15 is a program executed in an image forming apparatus equipped with a measurement unit that measures physical property values ​​of media, which causes the image forming apparatus to execute a determination step of determining process conditions based on the physical property values ​​measured by the measurement unit, a control step of controlling an image forming operation on the media by applying the process conditions determined in the determination step, and a storage step of correlating the physical property values ​​measured by the measurement unit with the process conditions determined in the determination step and storing them in a predetermined storage unit, wherein the determination step is characterized in that, when the physical property values ​​of the media newly measured by the measurement unit are within a predetermined range of the physical property values ​​stored in the storage unit, the process conditions associated with the physical property values ​​within the predetermined range are determined. [Effects of the Invention]

[0021] According to the present invention, it is possible to reduce the influence of measurement errors and set optimal process conditions for the media. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. [Figure 2]FIG. 2 is a block diagram showing the functional configuration of a control unit. [Figure 3] FIG. 10 is a diagram illustrating an example of physical property value data. [Figure 4] FIG. 10 is a diagram illustrating an example of a method for determining process conditions by a determination unit. [Figure 5] 10 is a flowchart illustrating an example of a processing procedure performed by a control unit. [Figure 6] 10 is a flowchart illustrating an example of a detailed procedure of a process condition determination process. [Figure 7] 10 is a flowchart illustrating an example of a detailed procedure of a job execution process. [Figure 8] 10 is a flowchart showing an example of a detailed procedure of a process condition verification process. [Figure 9] 10A and 10B are diagrams illustrating distributions of physical property values ​​when measuring the paper thickness and moisture content of a medium. [Figure 10] FIG. 10 is a block diagram showing the functional configuration of an image forming apparatus according to a third embodiment. [Figure 11] FIG. 10 is a diagram showing another example of physical property value data. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Elements common to the embodiments described below are designated by the same reference numerals, and redundant description thereof will be omitted.

[0024] (First embodiment) FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus 1 according to a first embodiment of the present invention. The image forming apparatus 1 includes a paper feed unit 10, a measurement unit 20, an image forming unit 30, and a paper discharge unit 40. The paper feed unit 10, the measurement unit 20, the image forming unit 30, and the paper discharge unit 40 are arranged in this order along the X direction shown in FIG. 1 and are mechanically and electrically connected to one another. When the image forming apparatus 1 starts executing a print job, the paper feed unit 10 feeds a sheet-like medium 9, such as printing paper, and transports the medium 9 in the X direction. That is, the medium 9 fed from the paper feed unit 10 is transported sequentially through the measurement unit 20, the image forming unit 30, and the paper discharge unit 40. The image forming apparatus 1 forms an image on the medium 9 as it passes through the image forming unit 30. The medium 9 with the image formed thereon is discharged by the paper discharge unit 40 to one of the paper discharge trays 41 and 42.

[0025] The paper feed unit 10 is equipped with multiple paper feed trays 11. Each paper feed tray 11 contains multiple sheets of media 9 of the same type stacked together. However, the multiple paper feed trays 11 may contain different types of media 9. The paper feed unit 10 is equipped with a paper feed transport section 12. The paper feed transport section 12 picks up media 9 one by one from the paper feed tray 11 specified in the job out of the multiple paper feed trays 11 and sends them to a transport path 13. The transport path 13 is a path along which media 9 are transported one by one, and is formed in communication from the paper feed unit 10 to the paper discharge unit 40.

[0026] The measurement unit 20 measures the physical properties of the media 9 fed from the paper feed unit 10. The measurement unit 20 has a branching section 15 on the transport path 13 provided inside, which branches the transport path 13 into two paths. One path is the transport path 13 that leads the media 9 transported from the paper feed unit 10 to the image forming unit 30. The other path is the transport path 14 that discharges the media 9 transported from the paper feed unit 10 to a purge tray 16 provided above the measurement unit 20 without supplying the media 9 to the image forming unit 30.

[0027] The measurement unit 20 includes two measurement units 21 and 22. These two measurement units 21 measure the physical property values ​​of the medium 9. There are various types of physical property values ​​of the medium 9. For example, the physical property values ​​of the medium 9 include paper thickness, basis weight, size, moisture content, stiffness, surface properties, and resistance value. The measurement units 21 and 22 measure these physical property values.

[0028] The measurement unit 21 is provided, for example, upstream of the branching unit 15. The measurement unit 21 measures the physical properties of the media 9 fed from the paper feed unit 10 as the media 9 is transported along the transport path 13. The measurement unit 21 measures the thickness, basis weight, size, and moisture content of the media 9. The measurement unit 21 includes a paper thickness sensor 23, a size detection sensor 24, a basis weight sensor 25, and a moisture content sensor 26. The paper thickness sensor 23, the size detection sensor 24, the basis weight sensor 25, and the moisture content sensor 26 can measure the respective physical properties while the media 9 continues to be transported, without stopping the transport of the media 9.

[0029] The paper thickness sensor 23 includes, for example, a pair of rollers arranged above and below the transport path 13. The distance between the rollers changes depending on the paper thickness as the media 9 passes through. The paper thickness sensor 23 measures the paper thickness by detecting the change in the distance between the rollers. The size detection sensor 24 is, for example, a contact image sensor and measures the size of the media 9 in the X and Y directions. The basis weight sensor 25 measures the basis weight of the media 9 by, for example, irradiating the media 9 with light and detecting the specular reflectance, diffuse reflectance, and transmittance. However, the basis weight sensor 25 may also be configured as a weight sensor that directly measures the weight of the media 9. The moisture content sensor 26 irradiates the media 9 with light of a wavelength absorbed by moisture and light of a wavelength not absorbed by moisture and detects the reflectance of the light. The moisture content sensor 26 measures the moisture content of the media 9 based on the difference between the reflectances. The measurement unit 21 sequentially measures multiple physical properties, such as basis weight, as the media 9 is transported along the transport path 13.

[0030] The measuring unit 22 is provided, for example, on the transport path 14 leading to the purge tray 16. The measuring unit 22 measures the stiffness, surface properties, and resistance value of the physical properties of the media 9. The measuring unit 22 includes a stiffness sensor 27, a surface property sensor 28, and a resistance sensor 29. The stiffness sensor 27 measures the stiffness of the media 9. The surface property sensor 28 measures the glossiness of the surface of the media 9. The resistance sensor 29 measures the resistance value of the media 9 by applying a voltage to the media 9. When the media 9 is transported on the transport path 14, the measuring unit 22 temporarily stops the transport of the media 9 and measures the physical properties of the media 9 while the media 9 is stopped.

[0031] After measuring the physical property values ​​using the stiffness sensor 27, the surface property sensor 28, and the resistance sensor 29, the measuring unit 22 resumes transport of the medium 9 and ejects the medium 9 onto the purge tray 16. In other words, the medium 9 whose physical property values ​​have been measured by the measuring unit 22 is not transported to the image forming unit 30.

[0032] The image forming unit 30 forms an image on the medium 9 transported from the measurement unit 20. The image forming unit 30 includes an image forming section 31, a fixing device 32, a control section 7, and an operation panel 8. The image forming section 31 and the fixing device 32 form an image on the medium 9 transported along the transport path 13, and fix the image to the medium 9.

[0033] The image forming section 31 includes an intermediate transfer belt 33, a plurality of imaging units 34Y, 34M, 34C, 34K, and 34W, and a secondary transfer roller 35.

[0034] The intermediate transfer belt 33 is an endless belt that moves in a circular motion in a predetermined direction and conveys images generated by the imaging units 34Y, 34M, 34C, 34K, and 34W after the primary transfer.

[0035] The multiple imaging units 34Y, 34M, 34C, 34K, and 34W are arranged at predetermined intervals so as to contact the intermediate transfer belt 33. The multiple imaging units 34Y, 34M, 34C, 34K, and 34W form images in each of the colors yellow (Y), magenta (M), cyan (C), black (K), and special color (W). Each imaging unit 34Y, 34M, 34C, 34K, and 34W has a rotating photosensitive drum, and is configured with a charger, an exposure unit, and a developing unit disposed around the photosensitive drum. The charger charges the surface of the photosensitive drum to a predetermined charge. The exposure unit exposes the charged surface of the photosensitive drum to light, thereby forming an electrostatic latent image corresponding to image data. The developing unit applies a developer containing toner to the surface of the photosensitive drum and develops the electrostatic latent image with toner. This forms an image on the surface of the photosensitive drum.

[0036] Imaging unit 34Y forms a Y toner image and performs primary transfer to intermediate transfer belt 33. Imaging unit 34M forms an M toner image and performs primary transfer to intermediate transfer belt 33. Imaging unit 34C forms a C toner image and performs primary transfer to intermediate transfer belt 33. Imaging unit 34K forms a K toner image and performs primary transfer to intermediate transfer belt 33. Imaging unit 34W performs primary transfer of a spot color toner image to intermediate transfer belt 33. Imaging unit 34W in this embodiment forms a white image as the spot color (W). Note that the image forming section 31 may be configured without including the imaging unit 34W for the spot color (W).

[0037] The multiple imaging units 34Y, 34M, 34C, 34K, and 34W superimpose the images of each color and perform primary transfer onto the intermediate transfer belt 33. Therefore, when the intermediate transfer belt 33 passes the position of the most downstream imaging unit 34W, a color image is formed on the surface of the intermediate transfer belt 33. The intermediate transfer belt 33 transports the color image toward the position of the secondary transfer roller 35.

[0038] The secondary transfer roller 35 is provided in the transport path 13 along which the medium 9 is transported, and is in contact with the surface of the intermediate transfer belt 33. The secondary transfer roller 35 presses the medium 9 transported along the transport path 13 against the intermediate transfer belt 33, and a predetermined voltage is applied to the secondary transfer roller 35, thereby secondarily transferring the image held by the intermediate transfer belt 33 onto the surface of the medium 9.

[0039] The medium 9 onto which the image has been transferred by the secondary transfer roller 35 is transported to the fixing device 32. The fixing device 32 includes a heating roller 36 and a pressure roller 37, and forms a nip portion where the heating roller 36 and the pressure roller 37 are in contact with each other. The fixing device 32 transports the medium 9 to the nip portion, and fixes the image onto the medium 9 by performing a fixing process including a heating process and a pressure process while the medium 9 passes through the nip portion.

[0040] The image forming unit 30 is provided with a reversing path 17 that turns over the medium 9 that has passed through the fixing device 32 and transports it again upstream of the secondary transfer roller 35. When forming images on both sides of the medium 9, the image forming unit 30 forms an image on one side of the medium 9, then transports the medium 9 to the reversing path 17, turns it over, and forms an image on the other side of the medium 9.

[0041] The paper discharge unit 40 receives media 9 on which an image has been formed in the image forming unit 30, and discharges the media 9 to paper discharge trays 41 and 42. Inside the paper discharge unit 40, the transport path 13 branches into two paths 18 and 19. Path 18 guides the media 9 to the paper discharge tray 41 and discharges it. Path 19 guides the media 9 to the paper discharge tray 42 and discharges it.

[0042] The control unit 7 comprehensively controls the execution of jobs in the image forming apparatus 1. That is, the control unit 7 controls the operations of the paper feed unit 10, the measurement unit 20, the image forming unit 30, and the paper discharge unit 40. For example, the control unit 7 accepts job setting operations by the user via the operation panel 8. Then, the control unit 7 controls the execution of the job specified by the user.

[0043] Before starting execution of a job specified by a user, the control unit 7 determines the process conditions appropriate for that job. The process conditions are conditions for properly forming an image on the medium 9. The process conditions include the process speed, which specifies the transport speed of the medium 9 and the speed of the intermediate transfer belt 33, and the fixing temperature when performing heat treatment in the fixing device 32. For example, if the medium 9 is thick paper, the fixing device 32 needs to perform the fixing process at a higher temperature and for a longer time than for thin paper in order to properly fix an image to the medium 9. Therefore, the process conditions when the medium 9 is thick paper differ from the process conditions when the medium 9 is thin paper. In particular, the process speed when the medium 9 is thick paper is slower than when it is thin paper.

[0044] To determine the process conditions, the control unit 7 feeds the media 9 from the paper feed tray 11 specified in the job. The media 9 is transported by the measurement unit 20 from the branching section 15 to the transport path 14 and ejected onto the purge tray 16. At this time, the measurement unit 20 measures the physical properties of the media 9 using each of the measurement sections 21 and 22. The control unit 7 then determines the process conditions based on the physical properties of the media 9 measured by the measurement unit 20. The control unit 7 then applies the determined process conditions and starts executing the job. The operation of the control unit 7 is described in detail below.

[0045] 2 is a block diagram showing the functional configuration of the control unit 7. The control unit 7 includes a CPU 50, a storage unit 51, and a communication unit 52. The CPU 50 is a hardware processor that reads and executes a program 60 stored in the storage unit 51. The storage unit 51 is a non-volatile storage device configured as a hard disk drive (HDD) or a solid state drive (SSD). The program 60 to be executed by the CPU 50 is stored in advance in the storage unit 51. The storage unit 51 also stores physical property value data 61 that accumulates physical property values ​​of the media 9 measured by the measurement units 21 and 22 of the measurement unit 20. The communication unit 52 communicates with the control unit 7 to control the operation of each unit of the image forming apparatus 1.

[0046] As shown in FIG. 2, the CPU 50 executes a program 60 to function as an acquisition unit 62, a determination unit 63, and a job control unit 64.

[0047] The acquisition unit 62 functions before the start of job execution and operates the paper feed unit 10 and the measurement unit 20. The acquisition unit 62 feeds at least one sheet of media 9 from the paper feed tray 11 specified in the job and transports it to the measurement unit 20. The acquisition unit 62 drives the branching unit 15 of the measurement unit 20 and switches to a state in which the media 9 is transported from the branching unit 15 to the transport path 14.

[0048] When the medium 9 fed from the paper feed unit 10 passes through the measurement unit 21, the acquisition unit 62 drives each sensor included in the measurement unit 21 to acquire physical property values ​​of the medium 9. That is, the acquisition unit 62 acquires the paper thickness, basis weight, size, and moisture content of the medium 9.

[0049] Furthermore, when the medium 9 is transported to the transport path 14, the acquisition unit 62 temporarily stops the transport of the medium 9 at the detection position of each sensor included in the measurement unit 22. The acquisition unit 62 then drives each sensor included in the measurement unit 22 to acquire the physical property values ​​of the medium 9. That is, the acquisition unit 62 acquires the stiffness, surface properties, and resistance value of the medium 9. After acquiring the physical property values ​​from the measurement unit 22, the acquisition unit 62 resumes the transport of the medium 9 on the transport path 14 and ejects the medium 9 to the purge tray 16.

[0050] The determination unit 63 functions before the start of job execution, similar to the acquisition unit 62. The determination unit 63 analyzes the physical property values ​​of the medium 9 acquired by the acquisition unit 62, and determines process conditions suitable for the medium 9 that will be transported during job execution. At this time, the determination unit 63 reads out physical property data 61 from the storage unit 51. The physical property data 61 is data that accumulates and records physical property values ​​collected during past job execution.

[0051] FIG. 3 is a diagram showing an example of physical property data 61. The physical property data 61 is data that accumulates physical property values ​​measured by the measurement unit 21 for each sheet of media 9 conveyed during job execution, and is data in which the process conditions applied during job execution are associated with each physical property value. The example in FIG. 3 illustrates the relationship between basis weight and paper thickness, among multiple physical property values. The physical property data 61 shown in FIG. 3 accumulates information on four types of media 9.

[0052] For example, the media 9 of the first type K1 is a media on which a job is executed under the first process conditions. The media 9 of the second type K2 is also a media on which a job is executed under the first process conditions. The first process conditions are, for example, a process speed of 225 mm / s.

[0053] Furthermore, the media 9 of the third type K3 are media on which a job was executed under the second process conditions. The media 9 of the fourth type K4 are also media on which a job was executed under the second process conditions. The second process conditions are, for example, conditions under which a process speed of 340 mm / s is applied. Therefore, when the second process conditions are applied, job execution efficiency is higher than when the first process conditions are applied.

[0054] The first process conditions and the second process conditions are switched between, for example, based on a threshold value Th set for the basis weight of the medium 9. When the basis weight of the medium 9 is equal to or greater than the threshold value Th, the first process conditions are adopted as the process conditions during job execution. When the basis weight of the medium 9 is less than the threshold value Th, the second process conditions are adopted as the process conditions during job execution.

[0055] However, when the measurement unit 21 measures the physical property values ​​of the media 9 one by one during job execution, measurement errors cause the distribution of physical property values ​​to spread, as shown in Figure 3. For example, the second type K2 of media 9 has a distribution of basis weights that straddles the threshold value Th. Similarly, the third type K3 of media 9 also has a distribution of basis weights that straddles the threshold value Th.

[0056] Therefore, when the acquisition unit 62 acquires the physical property value V of at least one piece of media 9 before the execution of the job starts, the determination unit 63 identifies which of the physical property value distributions of the multiple types K1 to K4 the physical property value V belongs to. For example, the determination unit 63 statistically analyzes the physical property value V and the physical property value distributions of the multiple types K1 to K4 to identify the physical property value distribution to which the physical property value V belongs. Specifically, the determination unit 63 calculates the distance between the physical property value V and the physical property value distribution of each type K1 to K4, and identifies the physical property value distribution in which the calculated distance falls within a predetermined range. If there are multiple physical property value distributions within the predetermined range, the determination unit 63 identifies the physical property value distribution with the closest distance. Then, the determination unit 63 determines that the process conditions associated with the identified physical property value distribution are optimal for the media 9 when the job is executed.

[0057] 4 is a diagram showing an example of a method for determining process conditions by the determination unit 63. For example, if the physical property value acquired by the acquisition unit 62 is the physical property value V1 shown in FIG. 4, the determination unit 63 identifies the physical property value distribution that is within a predetermined range for the physical property value V1 as the physical property value distribution of the second type K2. The determination unit 63 then identifies the process conditions that were applied when the job for the media 9 of the second type K2 was executed as the first process conditions, and determines the first process conditions as the process conditions to be applied to the job for the media 9 with the physical property value V1.

[0058] If the physical property value V1 acquired by the acquisition unit 62 were simply compared with the threshold value Th, the determination unit 63 would determine the second process conditions as the optimal process conditions for the media 9 having the physical property value V1. However, such a determination based on a simple comparison may result in an erroneous determination due to the influence of measurement error. Therefore, to prevent an erroneous determination due to measurement error, the determination unit 63 determines the optimal process conditions for the media 9 having the physical property value V1 by comparing the physical property value V1 with a physical property value distribution collected during the execution of a previous job. As a result, the physical property value V1 is determined to belong to the physical property value distribution of the media 9 of the second type K2, and the first process conditions are determined.

[0059] 4, the determination unit 63 determines that the physical property distribution within a predetermined range for the physical property value V2 is the physical property distribution of the third type K3. The determination unit 63 then determines that the process conditions applied during job execution for the media 9 of the third type K3 are the second process conditions, and determines the second process conditions as the process conditions to be applied to job execution for the media 9 with the physical property value V2.

[0060] If the physical property value V2 acquired by the acquisition unit 62 were simply compared with the threshold value Th, the determination unit 63 would determine the first process conditions as the optimal process conditions for the medium 9 having the physical property value V2. However, such a determination based on a simple comparison may result in an erroneous determination due to the influence of measurement error. Therefore, to prevent an erroneous determination due to measurement error, the determination unit 63 determines the optimal process conditions for the medium 9 having the physical property value V2 by comparing the physical property value V2 with a physical property value distribution collected during the execution of a previous job. As a result, the physical property value V2 is determined to belong to the physical property value distribution of the third type K3 of media 9, and the second process conditions are determined.

[0061] Here, the determination unit 63 may compare the physical property values ​​V1 and V2 acquired by the acquisition unit 62 with the physical property value distribution collected during execution of a past job only when the physical property values ​​V1 and V2 are within a predetermined range R1 with respect to the threshold value Th. In other words, when the physical property values ​​V1 and V2 acquired by the acquisition unit 62 are outside the predetermined range R1 with respect to the threshold value Th, the determination unit 63 may determine the process conditions by simply comparing the physical property values ​​V1 and V2 with the threshold value Th. This has the advantage of reducing the time required to compare the physical property values ​​V1 and V2 acquired by the acquisition unit 62 with the physical property value distribution collected during execution of a past job.

[0062] When the determination unit 63 determines the process conditions based on the physical property values ​​of the medium 9 fed before the execution of the job starts, it activates the job control unit 64. Then, the determination unit 63 notifies the job control unit 64 of the determined process conditions. The notified process conditions include the process speed and the fixing temperature.

[0063] The job control unit 64 applies the process conditions determined by the determination unit 63 and starts executing the job. That is, the job control unit 64 sets a process speed according to the type of media 9 used in the job, and also sets a fixing temperature according to the type of media 9. When starting execution of the job, the job control unit 64 sends a command to switch the branching unit 15 to the measurement unit 20. This causes the measurement unit 20 to drive the branching unit 15 and switch to a state in which the media 9 conveyed from the paper feed unit 10 is conveyed to the image forming unit 30. Then, the job control unit 64 starts the paper feed operation of the media 9 by the paper feed unit 10 with the process conditions determined by the determination unit 63 applied, and controls the image forming operation on the media 9.

[0064] When job execution is initiated by the job control unit 64, the acquisition unit 62 drives the measurement unit 21 of the measurement unit 20 and acquires the physical property values ​​of the media 9 as the media 9 passes the positions of the sensors included in the measurement unit 21. If multiple media 9 are continuously transported during job execution, the acquisition unit 62 sequentially acquires the physical property values ​​of those multiple media 9. The acquisition unit 62 then stores the physical property values ​​acquired during job execution as physical property value data for the same type of media 9. At this time, the acquisition unit 62 associates the process conditions determined by the determination unit 63 with the physical property values ​​and stores them. The physical property values ​​acquired during job execution also contain measurement errors. Therefore, the physical property values ​​of multiple media 9 measured during job execution will not be the same. In other words, the set of physical property values ​​collected during job execution forms a physical property value distribution with a certain degree of spread.

[0065] When the job control unit 64 finishes executing the job, the determination unit 63 starts functioning again in the CPU 50. The determination unit 63 then tests whether the process conditions applied during the execution of the current job were appropriate. For example, the determination unit 63 performs a significant difference test between the physical property value distribution of the medium 9 collected during the execution of the current job and the physical property value distribution determined to be closest to the physical property value V acquired before the job was executed. Based on the result of the significant difference test, the determination unit 63 determines whether the medium 9 indicated by the physical property value distribution collected during the execution of the current job and the medium 9 indicated by the physical property value distribution determined to be closest to the physical property value V acquired before the job is executed are the same type.

[0066] As a result, if it is determined that the media 9 are of the same type, the determination unit 63 determines that the process conditions applied during execution of the current job were appropriate. In this case, the determination unit 63 merges the set of physical property values ​​collected during execution of the current job with the set of physical property values ​​determined to be closest to the physical property value V acquired before execution of the job, and updates the physical property value data 61.

[0067] On the other hand, if it is determined that the media 9 are not of the same type, the determination unit 63 determines that the process conditions applied during execution of the current job may have been inappropriate. In this case, the determination unit 63 performs a significance test by comparing the physical property value distribution collected during execution of the current job with the physical property value distributions of other types of media 9 stored in the physical property value data 61. If the result shows that there is a physical property value distribution with no significant difference among the physical property value distributions of other types of media 9, the determination unit 63 determines that the physical property value distribution with no significant difference and the physical property value distribution collected during execution of the current job are of the same type of media 9. The determination unit 63 then merges the set of physical property values ​​collected during execution of the current job with the set of physical property value distributions determined to have no significant difference, and updates the physical property value data 61. The determination unit 63 also reads the process conditions associated with the media 9 with the physical property value distribution with no significant difference and compares it with the process conditions applied during execution of the current job. If there is a difference between the process conditions, the determination unit 63 sets one of the process conditions. At this time, it is preferable that the determination unit 63 adopts the process condition with the faster process speed and updates the physical property value data 61 in association with the merged set of physical property values. By adopting the process condition with the faster process speed, the job execution efficiency is improved.

[0068] Furthermore, if there is no other physical property value distribution that can be determined to have no significant difference from the physical property value distribution collected during execution of the current job, the determination unit 63 determines that the medium 9 used in the current job is a new medium 9. In this case, the determination unit 63 saves the set of physical property values ​​collected during execution of the current job as physical property value data of the new medium 9. At this time, the determination unit 63 updates the physical property value data 61 by associating the process conditions applied in the current job with the physical property values ​​of the new medium 9.

[0069] Therefore, when the next job is executed in the image forming apparatus 1, the determination unit 63 can determine the process conditions based on the updated physical property value data 61.

[0070] Next, a description will be given of specific operations in the image forming apparatus 1. Figures 5 to 8 are flowcharts showing an example of a processing procedure performed by the control unit 7. This processing is performed by the CPU 50 of the control unit 7 executing a program 60.

[0071] When a user instructs the control unit 7 to execute a job, the control unit 7 performs a process condition determination process to determine process conditions before starting execution of the job (step S1). Once the process conditions are determined by the process condition determination process, the control unit 7 sets the determined process conditions (step S2). That is, the control unit 7 sets process conditions according to the medium 9 used to execute the job. Thereafter, the control unit 7 performs a job execution process under the set process conditions (step S3). This causes the job specified by the user to be executed in the image forming device 3. Then, when execution of the job is completed, the control unit 7 performs a process condition verification process (step S4).

[0072] FIG. 6 is a flowchart showing an example of a detailed processing procedure of the process condition determination process (step S1). When the control unit 7 starts the process condition determination process, it activates the acquisition unit 62. The acquisition unit 62 then transports the media 9 to be used in the job (step S10). At this time, the control unit 7 controls the branch unit 15 of the measurement unit 20 to switch it to a state where the media 9 is discharged to the purge tray 16. The media 9 supplied from the paper feed unit 10 is carried into the measurement unit 20 and passes sequentially through the measurement units 21 and 22. The acquisition unit 62 drives the measurement units 21 and 22 to measure the physical property values ​​of the media 9 (step S11). This allows the acquisition unit 62 to acquire the physical property value V of the media 9 to be used in the job before the job is executed. Note that the acquisition unit 62 may measure the physical property values ​​of multiple pieces of media 9 and acquire the average value of those physical property values ​​before starting the job.

[0073] When the control unit 7 acquires the physical property value V of the medium 9, it activates the determination unit 63. The determination unit 63 reads out physical property value data 61, which stores physical property values ​​of the medium 9 used in past jobs (step S12). The physical property value data 61 stores data related to multiple types of media 9. The determination unit 63 selects one type of media 9 from the multiple types stored in the physical property value data 61 (step S13). The determination unit 63 then calculates the deviation value of the physical property value V in the physical property value distribution of the selected type of media 9 (step S14). For example, if the determination unit 63 selects the physical property value distribution of the first type K1 shown in FIG. 3, it calculates two deviation values, the deviation value of the basis weight and the deviation value of the paper thickness, as the deviation value of the physical property value V relative to the physical property value distribution of the first type K1. The determination unit 63 then determines whether the deviation values ​​of the basis weight and the paper thickness are each within a predetermined range (step S15). In this case, the predetermined range is, for example, a range of 30 to 70. If both the deviation values ​​of the basis weight and paper thickness are within the predetermined range (YES in step S15), the determination unit 63 temporarily stores the type of media 9 selected in step S13 as a candidate media of the same type as the media 9 used in the current job (step S16). On the other hand, if at least one of the deviation values ​​of the basis weight and paper thickness is outside the predetermined range (NO in step S15), the determination unit 63 does not store it as a candidate media of the same type.

[0074] Next, the determination unit 63 determines whether data relating to another type of media 9 is stored in the physical property data 61 (step S17). If data relating to another type of media 9 exists (YES in step S17), the process by the determination unit 63 returns to step S13. The determination unit 63 then selects a type of media 9 different from the previously selected media 9. The process of steps S14 to S16 described above is then repeated.

[0075] 3, if physical property values ​​for four types K1 to K4 of media 9 are stored in the physical property value data 61, the determination unit 63 repeats the processing of steps S14 to S16 for each of the four types K1 to K4 of media 9. In this way, the determination unit 63 calculates the deviation value of the physical property value V for each of the four types K1 to K4 of physical property value distributions, and selects media 9 whose deviation value is within a predetermined range as candidate media of the same type. After executing the processing of steps S13 to S16 for all types of media 9 stored in the physical property value data 61, the processing by the determination unit 63 proceeds to the next step.

[0076] The determining unit 63 then determines whether or not a media candidate of the same type is stored (step S18). If a media candidate of the same type is stored (YES in step S18), the determining unit 63 determines whether or not multiple media candidates are stored (step S19). If multiple media candidates are stored (YES in step S10), the determining unit 63 selects, from the multiple media candidates, the media 9 of the type that most closely resembles the media 9 of the physical property value V (step S20). For example, the determining unit 63 selects one media candidate whose deviation value calculated in step S14 is closest to 50, and identifies that media candidate as being of the same type as the media 9 used in the job. Note that if only one media candidate is stored, the determining unit 63 selects that one media candidate.

[0077] The determination unit 63 then reads out the process conditions associated with the selected medium 9 (step S21), and determines the read out process conditions as the process conditions for executing the job (step S22).

[0078] On the other hand, if no candidate media of the same type is stored (NO in step S18), the determination unit 63 determines that the media 9 measured in step S11 is a new media (step S23). In this case, the determination unit 63 determines process conditions according to the physical property values ​​measured in step S11 (step S24). For example, the determination unit 63 compares the basis weight included in the physical property values ​​with a threshold value Th, and determines either the first process conditions or the second process conditions. The process conditions determined in step S22 or S24 are set as the process conditions for job execution in step S2.

[0079] Next, FIG. 7 is a flowchart showing an example of a detailed processing procedure of the job execution process (step S3). When the control unit 7 starts the job execution process, it puts the job control unit 64 and the acquisition unit 62 into operation. When the job execution process starts, the job control unit 64 controls the branch unit 15 of the measurement unit 20 to switch the state so that the medium 9 is transported to the image forming unit 30. Then, the job control unit 64 transports one sheet of the medium 9 from the paper feed unit 10 (step S30). When the medium 9 passes the measurement unit 20, the acquisition unit 62 drives the measurement unit 21 to measure the physical property values ​​of the medium 9 (step S31). The acquisition unit 62 acquires the physical property values ​​and stores them in the memory unit 51 (step S32).

[0080] The job control unit 64 drives the image forming unit 31 and the fixing device 32 in synchronization with the timing at which the medium 9 is transported through the transport path 13 of the image forming unit 30, and forms an image on the medium 9 (step S33).The job control unit 64 then transports the medium 9 on which the image has been formed to the paper discharge unit 40, and discharges it onto one of the two paper discharge trays 41, 42 (step S34).

[0081] The job control unit 64 determines whether the execution of the job has ended (step S35). If the execution of the job has not ended (NO in step S35), the process by the control unit 7 returns to step S30 and repeats the above-described process. That is, the next medium 9 is transported from the paper feed unit 10, and the physical property values ​​of the medium 9 are measured. Then, image formation is performed as the medium 9 is transported through the image forming unit 30. By repeatedly executing the above-described process, the control unit 7 accumulates the physical property values ​​measured during the execution of the job in the memory unit 51. Then, as the execution of the job ends, the job execution process ends.

[0082] Next, FIG. 8 is a flowchart showing an example of a detailed processing procedure of the process condition verification process (step S4). When the control unit 7 starts the process condition verification process, it causes the determination unit 63 to function again. The determination unit 63 determines whether the process conditions set for the current job are the process conditions set for a previous job (step S40). That is, the determination unit 63 determines whether the process conditions set for the current job are the process conditions for the same type of media 9 recorded in the physical property value data 61. As a result, if the process conditions for the same type of media 9 were set and the current job was executed (YES in step S40), the determination unit 63 reads the physical property value distribution collected during the execution of the current job. Then, the determination unit 63 performs a significant difference test between the physical property value distribution collected during the execution of the job and the physical property value distribution for the same type of media 9 recorded in the physical property value data 61 (step S41). The significance level in the significant difference test is set to, for example, 5%. However, the significance level may be a level other than 5%.

[0083] If the significant difference test determines that there is no significant difference (NO in step S42), it is determined that the media 9 used in the current job is the same type as the media 9 selected before the job was executed. In other words, the determination by the determination unit 63 before the current job was executed was correct. As a result, it can be said that the process conditions set in the current job are the optimal process conditions for the media 9 used in the current job. In this case, the determination unit 63 merges the set of physical property values ​​collected during the execution of the current job with the set of physical property values ​​of the media 9 determined to be the same type, and updates the physical property data 61 (step S43).

[0084] If the significant difference test determines that there is a significant difference (YES in step S42), it is highly likely that the media 9 used in the current job is not the same type as the media 9 selected before the job was executed. Therefore, the determination unit 63 executes the processes from step S44 onwards to determine whether the media 9 used in the current job is the same type as other types of media 9 recorded in the physical property data 61. Furthermore, if the process conditions for the media 9 used in the past have not been set when the current job was executed (NO in step S40), the determination unit 63 executes the processes from step S44 onwards.

[0085] The determination unit 63 reads out the physical property value distributions of other types of media 9 recorded in the physical property value data 61 (step S44). Then, the determination unit 63 performs a significant difference test between the physical property value distribution collected during execution of the current job and the physical property value distributions of the other media 9 (step S45). The significance level in this case is also set to, for example, 5%. Note that, if the physical property value data 61 records the physical property value distributions of multiple media 9, the determination unit 63 performs a significant difference test with each of the physical property value distributions of the multiple media 9. Then, the determination unit 63 determines whether or not there is a significant difference in the significant difference test (step S46).

[0086] If there is a physical property value distribution determined to have no significant difference among the media 9 recorded in the physical property value data 61 (NO in step S46), the determination unit 63 merges these sets of physical properties into one (step S47). That is, the determination unit 63 merges the set of physical property values ​​collected during the execution of the job with the set of physical property values ​​determined to have no significant difference, and updates the physical property value data 61. Next, the determination unit 63 reads out the process conditions associated with the merged set of physical property values ​​(step S48) and compares them with the process conditions set during the execution of the current job (step S49). For example, the determination unit 63 compares the process speeds included in the process conditions and determines whether there is a difference between the process speeds.

[0087] If there is a difference in the process speeds (YES in step S49), the determination unit 63 adopts the process conditions with the faster process speed and updates the physical property value data 61 in association with the merged physical property values ​​(step S50). By adopting the process conditions with the faster process speed, job execution efficiency improves when the same type of media 9 is used in subsequent jobs. Note that the determination unit 63 is not limited to adopting the process conditions with the faster process speed when the two process conditions are different. For example, the determination unit 63 may adopt the process conditions with the larger amount of physical property value data from the two sets of physical property values ​​to be merged.

[0088] If there is no difference in the process speed (NO in step S49), the process conditions associated with the merged sets of physical property values ​​match. In this case, the determination unit 63 adopts the matching process conditions and updates the physical property value data 61 in association with the merged physical property values.

[0089] On the other hand, if there is no physical property value distribution determined to have no significant difference among the media 9 recorded in the physical property value data 61 (YES in step S46), the determination unit 63 determines that the media 9 used in the current job is a new type of media 9. In this case, the determination unit 63 records the set of physical property values ​​collected during execution of the current job in the physical property value data 61 as the physical property values ​​of the new media 9, and updates the physical property value data 61 (step S51). At this time, the determination unit 63 saves the process conditions set in the current job in association with the set of physical property values.

[0090] As described above, the image forming apparatus 1 of this embodiment measures the physical property values ​​of the medium 9 used in a job and determines the optimal process conditions for the medium 9 based on the measured physical property values. The image forming apparatus 1 executes the job with the determined process conditions applied and controls the image formation operation on the medium 9. The image forming apparatus 1 measures the physical property values ​​of the medium 9 conveyed during execution of the job, associates the physical property values ​​with the process conditions, and stores them in the physical property value data 61. Therefore, the image forming apparatus 1 records and stores the physical property value distribution of the medium 9 measured during execution of past jobs in the physical property value data 61.

[0091] When a user instructs the image forming apparatus 1 to execute a job, the image forming apparatus 1 feeds at least one sheet of media 9 specified by the user before starting execution of the job, and measures the physical property values ​​of the media 9. The image forming apparatus 1 then determines whether the physical property values ​​of the media 9 measured before execution of the job are within a predetermined range for the physical property values ​​recorded in the physical property value data 61, and determines that media 9 that are within the predetermined range are the same type as the media 9 used in the current job. The image forming apparatus 1 sets the process conditions associated with the media 9 determined to be the same type as the media 9 used in the current job as the optimal process conditions for the current job.

[0092] The image forming apparatus 1 configured as described above can reduce the effects of measurement errors through statistical analysis, even if the physical property values ​​of the medium 9 measured before the execution of a job contain measurement errors. In other words, the image forming apparatus 1 can set optimal process conditions for the medium 9 even if the measured physical property values ​​of the medium 9 contain errors. Therefore, the image forming apparatus 1 can appropriately and efficiently form an image on the medium 9 used in a job.

[0093] (Second embodiment) Next, a second embodiment of the present invention will be described. In the first embodiment, an example was described in which the basis weight and paper thickness of the physical properties of the media 9 were primarily referenced to determine the process conditions. However, the physical properties referenced to determine the process conditions may be physical properties other than basis weight and paper thickness. In this embodiment, an example will be described in which the process conditions are determined by reference to the paper thickness and moisture content.

[0094] FIG. 9 is a diagram showing the distribution of physical properties when measuring the paper thickness and moisture content of media 9. In the example of FIG. 9, there are four types of physical property distributions K5 to K8, and information on the four types of media 9 is shown. For media 9 of the first type K5, first process conditions were set when a previous job was executed. For media 9 of the second type K6, first process conditions were set when a previous job was executed. For media 9 of the third type K7, second process conditions were set when a previous job was executed. For media 9 of the fourth type K8, second process conditions were set when a previous job was executed.

[0095] Before starting execution of a job, the image forming apparatus 1 of this embodiment conveys at least one sheet of media 9 and measures at least the paper thickness and moisture content as the physical property value V of the media 9. At this time, if the physical property value V shown in FIG. 9 is acquired, the image forming apparatus 1 determines process conditions based on the physical property value V. That is, the image forming apparatus 1 compares the physical property value V with the measurement value distributions of multiple types K5 to K8, and identifies the measurement value distribution that falls within a predetermined range for the physical property value V through statistical analysis similar to that of the first embodiment. The image forming apparatus 1 then determines that the media 9 with the measurement value distribution that falls within the predetermined range is the same as the media 9 used in the current job, and determines process conditions accordingly.

[0096] In this way, the image forming apparatus 1 of this embodiment analyzes the distribution of physical property values ​​of paper thickness and moisture content when determining process conditions. The physical property value distribution is associated with the process conditions used when previous jobs were executed. Therefore, the image forming apparatus 1 can determine the optimal process conditions for the media 9 without referring to the basis weight. Note that this embodiment illustrates an example in which process conditions are determined based on paper thickness and moisture content. However, process conditions can also be determined in the same way for combinations other than paper thickness and moisture content. Therefore, the physical property values ​​referenced by the image forming apparatus 1 when determining process conditions may be combinations other than paper thickness and moisture content.

[0097] Other configurations and operations in this embodiment are the same as those described in the first embodiment.

[0098] (Third embodiment) Next, a third embodiment of the present invention will be described. The optimal process conditions for forming an image on a medium 9 vary not only depending on the physical properties of the medium 9, but also on environmental conditions such as temperature and humidity. Therefore, in this embodiment, an image forming apparatus 1 will be described that acquires environmental information such as temperature and humidity and determines the process conditions.

[0099] FIG. 10 is a block diagram showing the functional configuration of the image forming apparatus 1 according to this embodiment. The control unit 7 of the image forming apparatus 1 includes an environmental sensor 54. The environmental sensor 54 acquires environmental information about the environment in which the image forming apparatus 1 is installed. For example, the environmental sensor 54 includes a temperature sensor 65 and a humidity sensor 66. The temperature sensor 65 detects the temperature inside the image forming apparatus 1. The humidity sensor 66 detects the humidity inside the image forming apparatus 1. The environmental sensor 54 acquires environmental information, including the temperature and humidity of the environment in which the image forming apparatus 1 is installed, from the temperature sensor 65 and the humidity sensor 66, and outputs the environmental information to the CPU 50. The environmental sensor 54 does not have to be installed inside the control unit 7, but may be installed outside the control unit 7. The environmental sensor 54 may also be installed outside the image forming apparatus 1.

[0100] When the acquisition unit 62 acquires the physical property values ​​of the medium 9 being transported during job execution, it acquires environmental information from the environmental sensor 54. The acquisition unit 62 then associates the physical property values ​​of the medium 9 measured during job execution with the environmental information and records them in physical property value data 61. FIG. 11 is a diagram showing an example of physical property value data 61 recorded in the above manner. As shown in FIG. 11, the physical property value data 61 of this embodiment is associated with environmental information 67 at the time the physical property values ​​were measured.

[0101] When determining process conditions before executing a job, the determination unit 63 reads physical property value data 61 acquired in the same environment based on environmental information acquired by the environmental sensor 54. If the read physical property value data 61 records physical property value distributions for multiple types of media 9, the determination unit 63 determines which of the multiple physical property value distributions the physical property value V of the media 9 measured before executing the job is closest to. The determination unit 63 then determines the process conditions associated with the closest physical property value distribution as the process conditions to be applied when executing the job.

[0102] Therefore, the determination unit 63 can apply to the current job the process conditions of a previous job that was executed in the same environment as the environment in which the current job is executed. In this case, by performing the same statistical analysis as in the first embodiment, even if an error is included in the measured physical property value V of the media 9, the determination unit 63 can reduce the influence of the error and set the optimal process conditions for the media 9.

[0103] As described above, the determination unit 63 of this embodiment acquires environmental information from the environmental sensor 54 when the measurement unit 20 newly measures the physical property values ​​of the medium 9. The determination unit 63 then extracts a set of physical property values ​​measured under the same environmental conditions from the physical property value data 61 stored in the memory unit 51. The determination unit 63 determines whether the physical property values ​​of the medium 9 newly measured by the measurement unit 20 are within a predetermined range for the extracted set of physical property values, and determines the process conditions.

[0104] Environmental information such as temperature and humidity in the image forming apparatus 1 varies depending on the season and the date. Therefore, the image forming apparatus 1 may be configured to store date-related information associated with the physical property values ​​measured by the measurement unit 20 when the physical property values ​​of the medium 9 are measured. In this case, the determination unit 63 extracts a set of physical property values ​​measured around the same time from the physical property value data 61 stored in the memory unit 51 based on the date when the physical property values ​​of the medium 9 were newly measured by the measurement unit 20. The determination unit 63 then determines the process conditions by determining whether the physical property values ​​of the medium 9 newly measured by the measurement unit 20 are within a predetermined range for the extracted set of physical property values. In this case, the image forming apparatus 1 may be configured without the environmental sensor 54. The date-related information may also include time-related information.

[0105] Other configurations and operations in this embodiment are the same as those described in the first embodiment.

[0106] (Variation) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible.

[0107] For example, in the above embodiment, the measuring unit 20 is provided with two measuring units 21 and 22. The following description also illustrates a configuration example in which one of the two measuring units 21 and 22, measuring unit 21, is installed on the transport path 13 that communicates with the image forming unit 30, and the other measuring unit 22 is installed on the transport path 14 that does not communicate with the image forming unit 30. However, the installation locations of the two measuring units 21 and 22 are not limited to those described in the above embodiment. For example, measuring unit 22, like measuring unit 21, may be installed on the transport path 13 that communicates with the image forming unit 30. In this case, the measuring unit 20 can measure the physical property values ​​of the media 9 transported during job execution using both measuring units 21 and 22. Therefore, the image forming apparatus 1 can acquire various physical property values ​​during job execution and record them in the physical property data 61. Therefore, when determining process conditions before job execution, the image forming apparatus 1 can determine optimal process conditions for the media 9 based on the various physical property values.

[0108] In the above embodiment, the program 60 executed by the CPU 50 of the control unit 7 is pre-stored in the storage unit 51. However, the program 60 is not limited to being pre-stored in the storage unit 51. That is, the program 60 can be traded on its own. Therefore, the program 60 may be provided in a downloadable form via a network such as the Internet. The program 60 may also be provided in a state recorded on a computer-readable recording medium. [Explanation of symbols]

[0109] 1. Image forming device 7 Control Unit 9. Media 10 Paper feed unit 20 measurement units 21,22 Measuring part 30 Image forming unit 40 Paper output unit 51 Storage section 60 Programs 61 Physical property data 62 Acquisition Department 63 Decision Section 64 Job control section Th threshold

Claims

1. a measurement unit for measuring physical properties of the media; a determination unit that determines process conditions based on the physical property values ​​measured by the measurement unit; a control unit that controls an image forming operation on a medium by applying the process conditions determined by the determination unit; a storage unit that stores the physical property values ​​measured by the measurement unit and the process conditions determined by the determination unit in association with each other; Equipped with An image forming apparatus characterized in that, when a physical property value of a media newly measured by the measurement unit is within a predetermined range with respect to the physical property value stored in the memory unit, the determination unit determines a process condition associated with the physical property value within the predetermined range.

2. 2. The image forming apparatus according to claim 1, wherein the memory unit stores the physical property values ​​measured by the measurement unit in association with the process conditions determined by the determination unit when the control unit is performing image formation on the media.

3. the measuring unit measures physical property values ​​of the transported media one by one while the control unit is performing image formation on the media, 3. The image forming apparatus according to claim 2, wherein the storage unit accumulates and stores physical property values ​​of a plurality of sheets of media measured by the measurement unit while image formation is being performed.

4. 2. The image forming apparatus according to claim 1, wherein the measuring unit measures at least the basis weight of the medium as the physical property value of the medium.

5. 2. The image forming apparatus according to claim 1, wherein the measuring unit measures at least two of the media's basis weight, thickness, moisture content, and size as the media's physical property values.

6. 2. The image forming apparatus according to claim 1, wherein the process conditions include at least a process speed.

7. The image forming apparatus according to claim 1, characterized in that the determination unit holds a threshold value for switching process conditions depending on the physical property value of the media, and when the physical property value of the media newly measured by the measurement unit is within a predetermined range of the threshold value, the determination unit determines whether the physical property value of the media measured by the measurement unit is within a predetermined range of the physical property value stored in the memory unit.

8. When the newly measured physical property value of the medium is within a predetermined range of the threshold value, the measurement unit measures the physical property value of each medium being conveyed while the control unit is performing image formation on the medium, 8. The image forming apparatus according to claim 7, wherein the storage unit stores the physical property values ​​of the media measured by the measurement unit while the image is being formed, in association with the process conditions determined by the determination unit.

9. The image forming apparatus according to claim 1, characterized in that, after the image forming operation by the control unit is completed, the determination unit performs a significant difference test between the physical property values ​​of the media measured while the image is being formed on the media and the physical property values ​​associated with the process conditions applied during the image formation.

10. The image forming apparatus according to claim 9, wherein, when the significant difference test determines that there is no significant difference, the determination unit stores the physical property values ​​accumulated during image formation in the memory unit as physical property values ​​of a new medium.

11. The image forming apparatus according to claim 9, wherein, when the significant difference test determines that there is a significant difference, the determination unit merges the set of physical property values ​​accumulated during image formation with the set of physical property values ​​associated with the process conditions applied during image formation.

12. environmental sensors that acquire environmental information; Further provided with the storage unit stores the physical property values ​​measured by the measurement unit, the process conditions determined by the determination unit, and the environmental information acquired by the environmental sensor in association with each other; The image forming apparatus according to claim 1, characterized in that, when the physical property values ​​of the media are newly measured by the measuring unit, the determining unit extracts a set of physical property values ​​measured under the same environmental conditions from the set of physical property values ​​stored in the memory unit based on environmental information acquired by the environmental sensor, and determines whether the physical property values ​​of the media newly measured by the measuring unit are within a predetermined range for the extracted set of physical property values.

13. the storage unit stores, when the control unit is performing image formation on the medium, the physical property values ​​measured by the measurement unit, the process conditions determined by the determination unit, and information regarding the date of image formation in association with each other; The image forming apparatus according to claim 1, wherein the determination unit extracts a set of physical property values ​​measured at the same time from the set of physical property values ​​stored in the memory unit based on the date when the physical property values ​​of the media were newly measured by the measurement unit, and determines whether the physical property values ​​of the media newly measured by the measurement unit are within a predetermined range with respect to the extracted set of physical property values.

14. A control method for an image forming apparatus having a measurement unit that measures physical property values ​​of a medium, comprising: a determining step of determining process conditions based on the physical property values ​​measured by the measuring unit; a control step of controlling an image forming operation on a medium by applying the process conditions determined in the determination step; a storing step of storing the physical property values ​​measured by the measuring unit and the process conditions determined by the determining step in a predetermined storage unit in association with each other; and A control method characterized in that the determination step determines, when a physical property value of a media newly measured by the measurement unit is within a predetermined range of the physical property value stored in the memory unit, a process condition associated with the physical property value within the predetermined range.

15. A program executed in an image forming apparatus having a measurement unit for measuring physical property values ​​of a medium, the program comprising: a determining step of determining process conditions based on the physical property values ​​measured by the measuring unit; a control step of controlling an image forming operation on a medium by applying the process conditions determined in the determination step; a storing step of storing the physical property values ​​measured by the measuring unit and the process conditions determined by the determining step in a predetermined storage unit in association with each other; Execute The determination step is a program characterized in that, when a physical property value of a media newly measured by the measurement unit is within a predetermined range of the physical property value stored in the memory unit, a process condition associated with the physical property value within the predetermined range is determined.

Images