IMAGE FORMING APPARATUS AND IMAGE FORMING METHOD

An image forming apparatus includes an image forming portion, an image reading portion, and a test processing portion. The image forming portion forms an image on a sheet using a plurality of recording elements. The image reading portion reads the image on the sheet. The test processing portion causes the image forming portion to form a test image in a marginal region of the sheet, and causes the image reading portion to read the test image. The test processing portion is capable of executing a divisional test in which only some of the plurality of recording elements are used for forming a single test image to be formed on a single sheet and all of the plurality of recording elements are used for forming a test image group constituted of a plurality of the test images to be formed on a plurality of the sheets.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2023-128968 and 2023-128971 filed on Aug. 8, 2023, the entire contents of which are incorporated herein by reference.

BACKGROUND

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

As the related art, there is known an image forming apparatus (an inkjet recording apparatus) having a function of detecting an ink ejection failure. In the image forming apparatus according to the related art, ink is ejected from each of a plurality of arranged nozzles onto a sheet (a recording medium), to thus form an image on the sheet. In this image forming apparatus, it is possible to adjust an ink ejection amount from adjacent nozzles based on a test result of an ink ejection state of the nozzles, to thus compensate for lowering of quality of a formed image that is due to the ink ejection failure of the nozzles.

In the image forming apparatus according to the related art, a test of the ink ejection state includes ejecting ink onto a sheet from a plurality of nozzles, forming a halftone image having a predetermined concentration on the sheet as a test image (a test image), and reading the test image. Then, this image forming apparatus determines whether or not there is an ink ejection failure of the nozzles based on a contrasting density of the read test image.

SUMMARY

An image forming apparatus according to an aspect of the present disclosure includes an image forming portion, an image reading portion, and a test processing portion. The image forming portion forms an image on a sheet using a plurality of recording elements. The image reading portion reads the image on the sheet. The test processing portion causes the image forming portion to form a test image in a marginal region of the sheet, and causes the image reading portion to read the test image. The test processing portion is capable of executing a divisional test in which only some of the plurality of recording elements are used for forming a single test image to be formed on a single sheet and all of the plurality of recording elements are used for forming a test image group constituted of a plurality of the test images to be formed on a plurality of the sheets.

An image forming method according to another aspect of the present disclosure includes: image forming processing for causing an image forming portion which forms an image on a sheet using a plurality of recording elements to form a test image in a marginal region of the sheet; and image reading processing for reading the test image. In the image forming processing, only some of the plurality of recording elements are used for forming a single test image to be formed on a single sheet, and all of the plurality of recording elements are used for forming a test image group constituted of a plurality of the test images to be formed on a plurality of the sheets.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings. It is noted that the following embodiments are each an example of embodying the present disclosure and do not limit the technical scope of the present disclosure.

[1] Overall Configuration of Image Forming Apparatus

First, an overall configuration of an image forming apparatus10according to the present embodiment will be described with reference toFIG.1toFIG.3.

In the present embodiment, as an example, the image forming apparatus10is an inkjet recording apparatus (a printer) which includes recording heads51that eject ink onto a front surface of a sheet Sh1and is capable of executing print processing using an inkjet system for forming an image on the sheet Sh1using the recording heads51. The print processing is processing of forming an image on an image forming target. The sheet Sh1is an example of the image forming target (a recording medium) on which an image is formed in the image forming apparatus10and is a sheet-type medium such as paper and a resin film.

The image forming apparatus10only needs to have a function of forming an image using the inkjet system and may be, for example, a multifunction peripheral having a plurality of functions such as a scanning function, a facsimile function, and a copying function for reading image data from a document sheet in addition to a printing function. Alternatively, the image forming apparatus10may be a facsimile apparatus, a copying machine, or the like.

As shown inFIG.1, the image forming apparatus10configures an image forming system100together with a sheet feed apparatus11, a drying apparatus12, and a discharge apparatus13. In other words, the image forming system100according to the present embodiment includes the image forming apparatus10, the sheet feed apparatus11, the drying apparatus12, the discharge apparatus13, and the like. Herein, the image forming apparatus10, the sheet feed apparatus11, the drying apparatus12, and the discharge apparatus13are connected in the stated order of the sheet feed apparatus11, the image forming apparatus10, the drying apparatus12, and the discharge apparatus13from an upstream side of a conveying direction of the sheet Sh1. Thus, the image forming system100can consecutively perform, with respect to the sheet Sh1, a series of processing carried out by the sheet feed apparatus11, the image forming apparatus10, the drying apparatus12, and the discharge apparatus13. In addition, the respective apparatuses of the image forming system100are collectively managed by a control device7of the image forming apparatus10. It is noted that without being limited to this configuration, a control device which collectively manages the respective apparatuses may be provided separate from the control device7.

The sheet feed apparatus11is capable of storing a plurality of sheets Sh1. The sheet feed apparatus11supplies the sheets Sh1one by one to the image forming apparatus10. The image forming apparatus10ejects ink from the recording heads51onto the sheet Sh1supplied from the sheet feed apparatus11to thus form an image by the inkjet system (an ink image). The image forming apparatus10feeds the sheet Sh1on which the image has been formed to the subsequent drying apparatus12.

The drying apparatus12includes a drying chamber inside and includes, in the drying chamber, a heater, a heating unit that uses a heat pump system, or the like. The drying apparatus12heats the front surface of the sheet Sh1conveyed into the drying chamber from the image forming apparatus10to dry the ink image formed on the sheet Sh1. The drying apparatus12includes an exhaust fan for exhausting (discharging) moisture from the drying chamber. The drying apparatus12feeds the sheet Sh1that has been subjected to drying processing to the subsequent discharge apparatus13. Thus, the sheet Sh1on which the image has been formed by the inkjet system in the image forming apparatus10is discharged to the discharge apparatus13.

The discharge apparatus13stocks the sheets Sh1conveyed from the drying apparatus12. In addition, the discharge apparatus13may have, for example, a post-processing function such as a staple function and a punch function. In this case, in the discharge apparatus13, appropriate post-processing can be performed on the sheet Sh1on which the image has already been formed. Further, although the sheet Sh1that has been subjected to the drying processing in the drying apparatus12is conveyed to the discharge apparatus13in one-side printing in which an image is formed only on one side of the sheet Sh1, in duplex printing in which images are formed on both sides of the sheet Sh1, the sheet Sh1is fed back to the image forming apparatus10after being subjected to the drying processing in the drying apparatus12. Then, after an image is formed on a back surface in the image forming apparatus10and subjected to the drying processing in the drying apparatus12, the sheet Sh1is conveyed to the discharge apparatus13.

As shown inFIG.1andFIG.2, the image forming apparatus10includes a sheet conveying device4, an image forming portion5, an ink supply portion6, the control device7, an image reading portion8, and the like. The image forming portion5includes the plurality of recording heads51. These sheet conveying device4, image forming portion5, ink supply portion6, control device7, image reading portion8, and the like are housed in a housing21that constitutes an outer frame of the image forming apparatus10.

The sheet conveying device4conveys the sheets Sh1supplied from the sheet feed apparatus11one by one via a conveying path40. Thus, the sheet Sh1taken into the housing21of the image forming apparatus10from the sheet feed apparatus11passes below the image forming portion5via the conveying path40to be conveyed in a conveying direction D1and discharged to the drying apparatus12. The conveying path40is a path for conveying the sheet Sh1inside the housing21and includes a preceding conveying path401on the upstream side and a subsequent conveying path402on the downstream side with respect to the image forming portion5. The sheet conveying device4conveys the sheet Sh1supplied from the sheet feed apparatus11to the image forming portion5via the preceding conveying path401and discharges the sheet Sh1from the image forming portion5to the drying apparatus12via the subsequent conveying path402.

The sheet conveying device4includes a sheet feed portion41, one or more preceding conveying roller pairs42, a main conveying unit43, a discharge roller pair44, and the like. The sheet feed portion41feeds the sheets Sh1supplied from the sheet feed apparatus11one by one to the preceding conveying path401. The plurality of preceding conveying roller pairs42take over the conveyance of the sheet Sh1from the sheet feed portion41and convey the sheet Sh1toward the main conveying unit43.

The main conveying unit43is arranged below the image forming portion5. The preceding conveying path401is a path that reaches a position below the image forming portion5(above the main conveying unit43) from the sheet feed apparatus11. The main conveying unit43conveys the sheet Sh1while causing a first surface (a front surface) of the sheet Sh1to oppose the image forming portion5. The first surface of the sheet Sh1is a surface on which an ink image is formed. The main conveying unit43includes a plurality of tension rollers431and a main conveying belt432, and the main conveying belt432is supported and rotated by the plurality of tension rollers431. Thus, the main conveying unit43conveys the sheet Sh1toward the discharge roller pair44while the sheet Sh1is placed on the main conveying belt432.

The discharge roller pair44discharges the sheet Sh1on which an ink image has been formed to the drying apparatus12. The subsequent conveying path402is a path that reaches the drying apparatus12from the position below the image forming portion5(above the main conveying unit43).

The image forming portion5is arranged above the main conveying unit43. The image forming portion5ejects ink of a plurality of colors toward the sheet Sh1conveyed by the main conveying unit43of the sheet conveying device4, to thus form an ink image on the first surface of the sheet Sh1.

The image forming portion5includes the plurality of recording heads51and a head frame52that supports the plurality of recording heads51. The plurality of recording heads51eject the ink of the plurality of colors toward the sheet Sh1conveyed by the main conveying unit43, to thus form an image on the sheet Sh1.

In the example ofFIG.1, the plurality of recording heads51are sectioned into four line heads50respectively corresponding to ink in respective colors of black, cyan, magenta, and yellow. The ink supply portion6supplies the ink of the respective colors (K, C, M, and Y) to the recording heads51of the corresponding line heads50. The four line heads50are arranged next to one another in a sub-scanning direction D12and are fixed in a predetermined positional relationship (seeFIG.3). The number of line heads50to be provided in the image forming portion5is not limited to four and may be, for example, two, three, or five or more. The sub-scanning direction D12is the same as the conveying direction D1of the sheet Sh1on the main conveying belt432.

The plurality of recording heads51are arranged at positions at which a gap of about 1 millimeter is formed between an ink ejection surface provided on lower surfaces thereof and an upper surface of the sheet Sh1on the main conveying belt432. As shown inFIG.3, the plurality of recording heads51are each arranged in a state where a longitudinal direction thereof is provided along a main scanning direction D11. In the present embodiment, as an example, the line heads50of the respective colors each include three recording heads51. A plurality of ink nozzles53that eject ink onto the sheet Sh1conveyed along the conveying path40are formed on the ink ejection surface of each of the recording heads51. Each of the recording heads51includes a plurality of piezoelectric elements corresponding to the plurality of ink nozzles53. Each of the piezoelectric elements oscillates when a drive signal is supplied from the control device7, and thus the ink is pressurized to be ejected (blown out) from the respective ink nozzles53.

The image reading portion8reads an image on the sheet Sh1. The image reading portion8reads an image from the sheet Sh1and outputs image data corresponding to the read image to the control device7. The image reading portion8includes a light source, a plurality of mirrors, an optical lens, a CCD (Charge Coupled Device), and the like.

In the present embodiment, the image reading portion8is positioned above the subsequent conveying path402. The image reading portion8is arranged more on the downstream side of the conveying direction D1of the sheet Sh1by the sheet conveying device4than the image forming portion5. Thus, the image reading portion8can read the image formed on the sheet Sh1by the image forming portion5at a position on the downstream side. In other words, while the sheet Sh1is conveyed by the sheet conveying device4, formation of an image on the sheet Sh1and reading of the image can both be performed.

The control device7collectively controls the image forming apparatus10. The control device7includes, as a main configuration, a computer system including one or more processors and one or more nonvolatile memories. In the image forming apparatus10, the one or more processors execute programs to realize functions of the control device7. The programs may be recorded in advance in the memory (a storage portion), may be provided via an electric communication line such as the Internet, or may be provided by being recorded onto a non-transitory computer-system-readable recording medium such as a memory card and an optical disc. The one or more processors are configured by one or more electronic circuits including a semiconductor integrated circuit. In addition, the computer system used herein includes a microcontroller including one or more processors and one or more memories.

The control device7controls the sheet conveying device4, the image forming portion5, the ink supply portion6, the image reading portion8, and the like provided in the image forming apparatus10. In other words, the control device7is electrically connected to the respective portions of the image forming apparatus10and is capable of, for example, controlling the image forming portion5to form a desired image on the sheet Sh1and controlling the image reading portion8to read an image from the sheet Sh1. In other words, the control device7executes an image forming program recorded in the memory to perform an image forming method for controlling the respective portions of the image forming apparatus10.

In the present embodiment, the control device7has at least a function of a test processing portion71as shown inFIG.2. The test processing portion71performs a test of an operation state of the image forming portion5. The test processing portion71controls the image forming portion5to form a test image on the sheet Sh1, controls the image reading portion8to read the test image, and tests the operation state of the image forming portion5based on whether or not the test image is formed properly. Since the image forming portion5uses the inkjet system in the present embodiment, the test processing portion71tests an ink ejection state from the respective ink nozzles53.

When an operational failure (an ink ejection failure) of the image forming portion5is detected by the test processing portion71, the control device7executes countermeasure processing with respect to the operational failure. As an example of the countermeasure processing, the control device7corrects variations in ink ejection amounts from the plurality of ink nozzles53by shading correction or the like. Alternatively, when the ink ejection failure cannot be eliminated by merely changing the ink ejection amounts, the control device7may cancel the image forming operation by the image forming portion5as the countermeasure processing. In this case, as the countermeasure processing, the control device7may additionally cause a maintenance unit to perform a wiping operation or cause a display operation portion or the like to perform notification (display or the like) to prompt a user to perform maintenance (replacement of the recording head51or the like). The test processing portion71may be provided separate from the main control device7that collectively controls the image forming apparatus10.

Furthermore, the image forming apparatus10further includes a head cooling device, the maintenance unit, a cap unit, an operation display portion, and the like. The head cooling device cools the recording heads51. The maintenance unit performs a wiping operation for wiping the ink ejection surfaces (the lower surfaces of the recording heads51) to clean the ink ejection surfaces. The cap unit covers the ink ejection surface of the recording head51to protect it from drying. The operation display portion is a user interface in the inkjet recording apparatus. The operation display portion includes a display portion such as a liquid crystal display that displays various types of information in response to control instructions from the control device7and an operation portion such as a switch and a touch panel used for inputting various types of information to the control device according to user operations.

[2] Details of Test Processing Portion

Next, the test processing portion71of the image forming apparatus10according to the present embodiment will be described in more detail with reference toFIG.4toFIG.9. In the present embodiment, the test processing portion71provided in the control device7performs a test for an operational failure (an ink ejection failure) of the image forming portion5as described above.

Specifically, as shown inFIG.4, the test processing portion71causes the image forming portion5to form a test image Im1in a marginal region R2of the sheet Sh1. Then, the test processing portion71causes the image reading portion8to read the test image Im1.FIG.4is a schematic diagram showing the sheet Sh1conveyed by the main conveying unit43of the sheet conveying device4from above, and an enlarged diagram of a head-side portion (a range Z1) of the sheet Sh1in the conveying direction D1(the same as the sub-scanning direction D12) is shown on the right-hand side.

The sheet Sh1includes a document sheet region R1and the marginal region R2. The document sheet region R1and the marginal region R2are sectioned by a boundary line L1, and a region on an inner side of the boundary line L1is the document sheet region R1, and a region on an outer side of the boundary line L1is the marginal region R2. InFIG.4and the like, the boundary line L1is indicated by an imaginary line (a dash-dot-dot line), but the boundary line L1is not actually formed on the sheet Sh1. The document sheet region R1is a region where a desired image is formed by the image forming portion5. The marginal region R2is a region that is not used for forming a desired image and is, for example, a region where trimming marks (printer marks) M1for cutting, and the like are formed.

In other words, by forming the test image Im1in such a marginal region R2, the test processing portion71uses the marginal region R2to perform a test of the operation state of the image forming portion5. More specifically, as shown on the left-hand side ofFIG.4, the image forming portion5forms the test image Im1in the head-side marginal region R2of the sheet Sh1conveyed by the sheet conveying device4along the conveying direction D1. Then, the image reading portion8arranged on the downstream side of the image forming portion5reads the test image Im1formed on the sheet Sh1, to enable the test processing portion71to perform the test.

The test processing portion71determines, for example, whether or not there is a defect that is due to an ink ejection failure, such as a dead pixel, in the read test image Im1, and when there is the defect, determines that an operational failure (an ink ejection failure) of the image forming portion5has occurred. In addition, the test processing portion71is capable of specifying which of the plurality of ink nozzles53has the ink ejection failure based on a position at which the defect has occurred in the test image Im1.

Incidentally, as the related art, there is known an image forming apparatus (an inkjet recording apparatus) having a function of detecting an ink ejection failure. In the image forming apparatus according to the related art, ink is ejected from each of a plurality of arranged nozzles onto a sheet (a recording medium), to thus form an image on the sheet. In this image forming apparatus, it is possible to adjust an ink ejection amount from adjacent nozzles based on a test result of an ink ejection state of the nozzles, to thus compensate for lowering of quality of a formed image that is due to the ink ejection failure of the nozzles.

In the image forming apparatus according to the related art, a test of the ink ejection state includes ejecting ink onto a sheet from a plurality of nozzles, forming a halftone image having a predetermined concentration on the sheet as a test image (a test image), and reading the test image. Then, this image forming apparatus determines whether or not there is an ink ejection failure of the nozzles based on a contrasting density of the read test image.

With the configuration of the related art, however, since a test image is formed by ejecting ink from all of the plurality of nozzles onto a single sheet, it likely takes time to form a test image on a single sheet, and an amount of consumption of consumables (ink) is likely to become large.

In contrast, in the image forming apparatus10according to the present embodiment, it is possible to realize the image forming apparatus10in which a time required for forming a test image is likely to be shortened and an amount of consumption of consumables is likely to be suppressed by a configuration described below.

Specifically, the image forming apparatus10according to the present embodiment includes the image forming portion5, the image reading portion8, and the test processing portion71. The image forming portion5forms an image on the sheet Sh1using a plurality of recording elements. The image reading portion8reads the image on the sheet Sh1. The test processing portion71causes the image forming portion5to form a test image Im1in the marginal region R2of the sheet Sh1and causes the image reading portion8to read the test image Im1. Herein, the test processing portion71is capable of executing a divisional test in which only some of the plurality of recording elements are used for forming a single test image Im1to be formed on a single sheet Sh1and all of the plurality of recording elements are used for forming a test image group constituted of a plurality of test images Im1to be formed on a plurality of sheets Sh1.

In the present embodiment, the ink nozzle53is an example of the recording element. In other words, the image forming portion5includes the plurality of ink nozzles53(the recording elements), and the plurality of ink nozzles53are used to form an image on the sheet Sh1. In the present embodiment in particular, as shown inFIG.3, since each of the line heads50of the four colors includes three recording heads51in the image forming portion5, a total of the plurality of ink nozzles53provided in the total of 12 recording heads51becomes a sum of the plurality of ink nozzles53(the recording elements) included in the image forming portion5. The sum of the ink nozzles53as the recording elements included in the image forming portion5in this manner will hereinafter be also referred to as a “predetermined number”.

In short, in the divisional test, all of the predetermined number of ink nozzles53(recording elements) are used to form a test image group constituted of a plurality of test images Im1on a plurality of sheets Sh1instead of being used to form a single test image Im1on a single sheet Sh1. In other words, in the divisional test, the test images Im1that use all of the predetermined number of ink nozzles53(recording elements) are formed divisionally on the plurality of sheets Sh1instead of being formed on a single sheet Sh1. Thus, the test for the predetermined number of ink nozzles53(recording elements) is performed using the plurality of sheets Sh1instead of a single sheet Sh1.

Accordingly, in the image forming apparatus10according to the present embodiment, there are advantages that a time required for forming the test image Im1on a single sheet Sh1is likely to be shortened and an amount of consumption of consumables (ink) is likely to be suppressed as compared to the related art. In addition, since the test can be performed for all of the plurality of recording elements (ink nozzles53) by the test image group divisionally formed on the plurality of sheets Sh1, the test can consequently be performed for the entire image forming portion5(the predetermined number of recording elements).

Hereinafter, specific examples of the test image Im1that is used by the test processing portion71in the image forming apparatus10according to the present embodiment will be described with reference toFIG.5toFIG.9. Herein, descriptions will be given on a case where a four-color printing machine that uses ink of the respective colors of black (K), cyan (C), magenta (M), and yellow (Y) is used as the image forming portion5.

FIG.5shows a test image group of a first pattern. As shown inFIG.5, the test image group of the first pattern includes four test images Im11to Im14that are formed divisionally on four sheets Sh11to Sh14. Each of the test images Im11to Im14is divided into four in the main scanning direction D11and is configured such that images of four colors are respectively arranged in the four regions obtained by the division. The test image Im11formed on the first sheet Sh11includes C, M, Y, and K in the stated order from the left-hand side, and the test image Im12formed on the second sheet Sh12includes K, C, M, and Y in the stated order from the left-hand side. The test image Im13formed on the third sheet Sh13includes Y, K, C, and M in the stated order from the left-hand side, and the test image Im14formed on the fourth sheet Sh14includes M, Y, K, and C in the stated order from the left-hand side.

The test processing portion71repetitively forms these four test images Im11to Im14every four sheets Sh11to Sh14. The test image group of the first pattern is an ideal case where the number of ink colors and the number of test images Im1constituting the test image group match.

FIG.6shows a test image group of a second pattern. As shown inFIG.6, the test image group of the second pattern includes four test images Im11to Im14that are formed divisionally on four sheets Sh11to Sh14. The four test images Im11to Im14are images of the respective colors of C, M, Y, and K, respectively. The test image Im11formed on the first sheet Sh11is an image of C, the test image Im12formed on the second sheet Sh12is an image of M, the test image Im13formed on the third sheet Sh13is an image of Y, and the test image Im14formed on the fourth sheet Sh14is an image of K.

The test processing portion71repetitively forms these four test images Im11to Im14every four sheets Sh11to Sh14. In the test image group of the second pattern, the test image Im1of one color is formed for each sheet Sh1.

FIG.7shows a test image group of a third pattern. As shown inFIG.7, the test image group of the third pattern includes two test images Im11and Im12that are formed divisionally on two sheets Sh11and Sh12. Each of the test images Im11and Im12is divided into four in the main scanning direction D11and is configured such that images of different colors are arranged in two rows in the sub-scanning direction D12. The test image Im11formed on the first sheet Sh11includes C, M, C, and M in the stated order from the left-hand side on the first row and includes K, Y, K, and Y in the stated order from the left-hand side on the second row. The test image Im12formed on the second sheet Sh12includes M, C, M, and C in the stated order from the left-hand side on the first row and includes Y, K, Y, and K in the stated order from the left-hand side on the second row.

The test processing portion71repetitively forms these two test images Im11and Im12every two sheets Sh11and Sh12. In the test image group of the third pattern, the number of test images Im1constituting the test image group becomes ½ of the number of ink colors.

FIG.8shows a test image group of a fourth pattern. As shown inFIG.8, the test image group of the fourth pattern includes three test images Im11to Im13that are formed divisionally on three sheets Sh11to Sh13. Each of the test images Im11to Im13is divided into three in the main scanning direction D11and is configured such that images of different colors are arranged in two rows in the sub-scanning direction D12. The test image Im11formed on the first sheet Sh11includes C, M, and Y in the stated order from the left-hand side on the first row and includes K at a left end of the second row. The test image Im12formed on the second sheet Sh12includes Y, C, and M in the stated order from the left-hand side on the first row and includes K at a center of the second row. The test image Im13formed on the third sheet Sh13includes M, Y, and C in the stated order from the left-hand side on the first row and includes K at a right end of the second row.

The test processing portion71repetitively forms these three test images Im11to Im13every three sheets Sh11to Sh13. In the test image group of the fourth pattern, the number of test images Im1constituting the test image group is smaller than the number of ink colors.

FIG.9shows a test image group of a fifth pattern. As shown inFIG.9, the test image group of the fifth pattern includes three test images Im11to Im13that are formed divisionally on three sheets Sh11to Sh13. Each of the test images Im11to Im13is divided into three in the main scanning direction D11and is configured such that images of different colors are arranged in two rows in the sub-scanning direction D12. The test image Im11formed on the first sheet Sh11includes C, M, and Y in the stated order from the left-hand side on the first row and includes K on the second row. The test image Im12formed on the second sheet Sh12includes Y, C, and M in the stated order from the left-hand side on the first row and includes K on the second row. The test image Im13formed on the third sheet Sh13includes M, Y, and C in the stated order from the left-hand side on the first row and includes K on the second row.

The test processing portion71repetitively forms these three test images Im11to Im13every three sheets Sh11to Sh13. In the test image group of the fifth pattern, the number of test images Im1constituting the test image group is smaller than the number of ink colors. In this case, regarding the color that is used most frequently (for example, K), the test of all of the ink nozzles53can be performed in any of the three sheets Sh11to Sh13.

In the image forming apparatus10according to the present embodiment, for example, the number of test images Im1to be included in the test image group can be set as appropriate as in the first to fifth patterns. In other words, the test processing portion71can change the number of test images Im1to be included in the test image group. Therefore, for example, it is possible to make a setting such that a test of a predetermined number of recording elements are ended using an appropriate number of sheets Sh1according to a purpose, a use frequency, or the like of the image forming apparatus10.

[3] Image Forming Method

Hereinafter, the image forming method executed by the test processing portion71in the image forming apparatus10having the configuration described above will be described with reference to the flowchart shown inFIG.10. Herein, Step S1, Step S2, . . . represent number of processing procedures (steps) executed by the test processing portion71.

First, in Step S1, the test processing portion71controls the image forming portion5to form a test image Im1on a first sheet Sh1. In next Step S2, the test processing portion71controls the image reading portion8to read the test image Im1from the first sheet Sh1.

In Step S3, the test processing portion71determines whether or not the number of sheets Sh1from which the test images Im1have been read in Step S2(the number of read sheets) has reached a predetermined number of sheets N. Herein, the predetermined number of sheets N is the number of test images Im1included in the test image group and is, for example, “N=4” in the test image group of the first pattern. Then, when the number of read sheets has reached the predetermined number of sheets N (S3: Yes), the test processing portion71shifts the processing to Step S4. On the other hand, when the number of read sheets has not reached the predetermined number of sheets N (S3: No), the test processing portion71shifts the processing back to Step S1.

In Step S4, the test processing portion71executes a test for the test images Im1for the predetermined number of sheets N. After that, in Step S5, the test processing portion71resets the number of read sheets (resets to “0”) and shifts the processing back to Step S1.

The procedures of the image forming method described heretofore are mere examples, and the order of the processing shown in the flowchart ofFIG.10may be switched as appropriate, or appropriate processing may be added or omitted.

[4] Modified Example

The plurality of constituent elements included in the image forming apparatus10may be provided dispersedly in a plurality of housings. For example, the image forming portion5and the ink supply portion6may be provided in different housings.

Conversely, in Embodiment 1, at least one of the constituent elements provided separate from the image forming apparatus10may be provided in the image forming apparatus10as a constituent element of the image forming apparatus10. For example, at least one of the sheet feed apparatus11, the drying apparatus12, and the discharge apparatus13may be provided inside the housing21, or the like, so as to be configured integrally with the image forming apparatus10.

Moreover, the image forming target on which an image is to be formed in the image forming apparatus10is not limited to the sheet Sh1such as paper and a resin film and may be, for example, roll-type fabric such as non-woven fabric and textile. In this case, the image forming apparatus10is a textile printing machine (a textile printer) which ejects ink onto the fabric and dyes fibers of the fabric by ink to record an image on the fabric.

In addition, the “recording elements” are not limited to the ink nozzles53and may be, for example, the recording heads51or the line heads50. Further, if systems other than the inkjet system are used in the image forming apparatus10, the recording elements are changed as appropriate according to the system of the image forming apparatus10and the like.

As shown inFIG.11toFIG.13, the image forming apparatus10according to the present embodiment is different from the image forming apparatus10according to Embodiment 1 in the point of being compatible with a change in attribute of the sheet Sh1in the middle of formation of the images on the plurality of sheets Sh1. Hereinafter, configurations similar to those of Embodiment 1 will be denoted by common symbols, and descriptions will be omitted as appropriate.

The attribute of the sheet Sh1used herein includes, for example, a size (a paper sheet size), an orientation, and the like of the sheet Sh1. In the present embodiment, a case where the size of the sheet Sh1is changed in mid-course is assumed as an example. Also in the present embodiment, a case where the test processing portion71executes the divisional test according to the test image group of the first pattern will be exemplified.

For example, as shown inFIG.11, a case where, when forming images on the sheets Sh11to Sh15, the sheets Sh11and Sh12of an “A4 size in portrait orientation” are changed to the sheets Sh13to Sh15of an “A3 size in portrait orientation” is assumed. In this case, for the sheets Sh11and Sh12, the test processing portion71sequentially forms the test images Im11and Im12according to the test image group of the first pattern. Then, when the attribute (the size) of the sheet Sh1is changed, the test processing portion71temporarily stops the divisional test and executes, on the sheet Sh13positioned at the top after the change of the size, an overall test in which all of the predetermined number of ink nozzles53are used. In other words, the test image Im13formed on the sheet Sh13is an image that uses all of the plurality of ink nozzles53of C, M, Y, and K.

Then, for the second and subsequent sheets Sh14and Sh15after the change of the size, the test processing portion71sequentially forms the test images Im14and Im15according to the test image group of the first pattern, to resume the divisional test. Herein, the test images Im14and Im15formed on the sheets Sh14and Sh15are images obtained by expanding the images according to a width of the sheets Sh14and Sh15of the “A3 size in portrait orientation” as compared to the test images Im11and Im12.

Specifically, in the image forming apparatus10according to the present embodiment, the test processing portion71changes a mode of the test image Im1in sync with a timing at which the attribute of the sheet Sh1is changed. Thus, even when the attribute of the sheet Sh1is changed, it is difficult for testing quality to be lowered, and appropriate test processing tailored for the sheet Sh1can be performed.

Particularly in the present embodiment, the test processing portion71executes, for the first sheet Sh1after the change of the attribute, the overall test in which all of the plurality of recording elements (ink nozzles53) are used for forming a single test image Im1to be formed on a single sheet Sh1. Thus, the operation states of all of the predetermined number of recording elements can be guaranteed at a timing at which the attribute of the sheet Sh1is changed. In addition, there are advantages that a time required for forming the test image Im1on a single sheet Sh1is likely to be shortened and an amount of consumption of consumables (ink) is likely to be suppressed as compared to the case of executing the overall test on all of the sheets Sh1.

Alternatively, as another example, the test processing portion71is also capable of adopting a configuration in which the overall test is not performed at the timing at which the attribute of the sheet Sh1is changed as shown inFIG.12. In the example ofFIG.12, for the sheets Sh11and Sh12, the test processing portion71sequentially forms the test images Im11and Im12according to the test image group of the first pattern. Then, when the attribute (the size) of the sheet Sh1is changed, the test processing portion71forms the test image Im13as exemplified inFIG.12on the sheet Sh13positioned at the top after the change of the size. In the sheet Sh13, the test image Im13includes images that use all of the plurality of ink nozzles53of C, M, Y, and K only in regions where the test has not been able to be performed in the sheets Sh11and Sh12before the change of the size. Herein, for the region already tested in the sheets Sh11and Sh12before the change of the size, the test image Im13configures an image in which Y, K, C, and M are arranged in the stated order from the left-hand side according to the test image group of the first pattern.

Then, for the second and subsequent sheets Sh14and Sh15after the change of the size, the test processing portion71sequentially forms the test images Im14and Im15according to the test image group of the first pattern. Herein, the test images Im14and Im15formed on the sheets Sh14and Sh15are images obtained by expanding the images according to a width of the sheets Sh14and Sh15of the “A3 size in portrait orientation” as compared to the test images Im11and Im12. In short, in the example ofFIG.12, the test processing portion71continuously executes the divisional test for the sheets Sh11to Sh15obtained both before the change of the size and after the change of the size.

Furthermore, as shown inFIG.13, when the size of the sheet Sh1becomes small, the test processing portion71only needs to simply continue the divisional test without adding special processing. For example, as shown inFIG.13, a case where, when forming images on the sheets Sh11to Sh14, the sheets Sh11and Sh12of an “A3 size in portrait orientation” are changed to the sheets Sh13and Sh14of an “A4 size in portrait orientation” is assumed. In this case, for the sheets Sh11and Sh12, the test processing portion71sequentially forms the test images Im11and Im12according to the test image group of the first pattern. Then, when the attribute (the size) of the sheet Sh1is changed, the test processing portion71sequentially forms the test images Im13and Im14according to the test image group of the first pattern also for the sheets Sh13and Sh14obtained after the change of the size. It is noted that the test images Im13and Im14formed on the sheets Sh13and Sh14are images obtained by contracting the images according to a width of the sheets Sh13and Sh14of the “A4 size in portrait orientation” as compared to the test images Im11and Im12.

Herein, the case where the attribute of the sheet Sh1is changed between the sheet Sh1of the “A3 size in portrait orientation” and the sheet Sh1of the “A4 size in portrait orientation” has been exemplified, but the same holds true also for other attributes of the sheet Sh1.

In the image forming system100according to the present embodiment (an example of the image forming apparatus according to the present disclosure), the sheet feed apparatus11, the sheet conveying device4of the image forming apparatus10, the drying apparatus12, and the discharge apparatus13function as a sheet conveying portion which conveys the sheet Sh1along a conveying path K1(seeFIG.14) that reaches a first discharge portion14(seeFIG.14) that is a discharge destination of the sheet Sh1via the image forming portion5. For example, the first discharge portion14is a sheet discharge tray. Further, in the image forming system100according to the present embodiment, the processing content of the test processing portion71differs from that of the image forming apparatus10according to Embodiment 1. Hereinafter, configurations similar to those of Embodiment 1 will be denoted by common symbols, and descriptions will be omitted as appropriate.

In the divisional processing according to the present embodiment, the test images Im1included in the test image group are formed periodically. In addition, in the divisional processing according to the present embodiment, one of the test images Im1is formed every time an image (a page image) is formed in the document sheet region R1of the sheet Sh1as shown inFIG.15. In other words, in the divisional processing according to the present embodiment, the plurality of test images Im1included in the test image group are sequentially formed at intervals of image formation by the image forming portion5in the document sheet regions R1of the sheets Sh1. For example, when the number of test images Im1included in the test image group is four, the four test images Im11to Im14are formed in the order of the test image Im11, the test image Im12, the test image Im13, the test image Im14, the test image Im11, . . . at the intervals of image formation by the image forming portion5in the document sheet regions R1of the sheets Sh1as shown inFIG.15. It is noted thatFIG.15exemplifies a case where the divisional test is executed according to the test image group of the second pattern.

Further, the test processing portion71according to the present embodiment tests the read test image Im1every time the test image Im1included in the test image group is read by the image reading portion8. Then, when determined that there is a defect in the test image Im1, the test processing portion71notifies to that effect and also discharges, in an identifiable manner, a specific sheet including a sheet surface on which an image is formed next after a sheet surface including the test image Im1obtained one cycle before the test image Im1that has been determined as having the defect. The sheet surface may include only a front surface of a sheet, or may include both front and back surfaces of a sheet.

Specifically, the test processing portion71notifies that the test image Im1has been determined as having a defect at a timing at which the specific sheet is discharged to the first discharge portion14.

For example, it is assumed that, when sequentially forming page images of first to eighth pages as shown inFIG.15, the test image Im13formed together with the page image of the seventh page includes a defective image Er1such as a white streak. In this case, the test processing portion71determines that the sheet Sh1including the sheet surface on which an image is formed next after the sheet surface including the test image Im13obtained one cycle before the test image Im13including the defective image Er1(the test image Im13formed together with the page image of the third page) (the sheet surface on which the page image of the fourth page is formed) is the specific sheet. In other words, the test processing portion71determines that, while an operational failure has not occurred in the image forming portion5when forming the test image Im13obtained one cycle before the test image Im13including the defective image Er1, the operational failure may have occurred in the image forming portion5when forming an image of the next page, and discharges the specific sheet that might be including the defective image in an identifiable manner.

Moreover, the test processing portion71according to the present embodiment sets the number of test images Im1to be included in the test image group based on the number of sheets Sh1not yet discharged, that are present in a section more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1.

For example, in the image forming system100, it is assumed that the number of sheets Sh1not yet discharged (Sh22), that are present in the section more on the downstream side than the sheet Sh1including the test image Im1as the test target (Sh21) on the conveying path K1at the time of the test of the test image Im1is three (seeFIG.14). In this case, the test processing portion71sets “4” obtained by adding “1” to the number of sheets Sh1not yet discharged (Sh22) as the number of test images Im1to be included in the test image group. Thus, when it is determined that there is a defect in the test image Im13formed on the sheet Sh21as shown inFIG.15, the specific sheet (the sheet Sh22on which the page image of the fourth image is formed) can be set to a not-yet-discharged state. It is noted that the number of sheets Sh1not yet discharged, that are present in the section more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1can be specified based on a length of the section, a size of the sheet Sh1to be conveyed, and intervals among the sheets Sh1during the conveyance.

It is noted that the test processing portion71may set a number that is equal to or smaller than the number of sheets Sh1not yet discharged, that are present in the section more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1as the number of test images Im1to be included in the test image group.

Hereinafter, the image forming method executed by the test processing portion71in the image forming system100having the configuration described above will be described with reference to the flowchart shown inFIG.16.

First, in Step S11, the test processing portion71controls the image forming portion5to form a test image Im1on a first sheet Sh1. In next Step S12, the test processing portion71controls the image reading portion8to read the test image Im1from the first sheet Sh1.

In Step S13, the test processing portion71executes a test for the test image Im1read in Step S12.

In Step S14, the test processing portion71determines whether or not a defect has been detected in the test executed in Step S13. Then, when determining that a defect has been detected (S14: Yes), the test processing portion71shifts the processing to Step S15. On the other hand, when determining that a defect has not been detected (S14: No), the test processing portion71shifts the processing to Step S16.

In Step S15, the test processing portion71notifies that the test image Im1has been determined as having a defect, and discharges, in an identifiable manner, the specific sheet including a sheet surface on which an image is formed next after a sheet surface including the test image Im1obtained one cycle before the test image Im1that has been determined as having the defect.

Specifically, the test processing portion71notifies that the test image Im1has been determined as having a defect, that is, an operational failure has occurred in the image forming portion5, at a timing at which the specific sheet is discharged. For example, the test processing portion71causes the operation display portion of the image forming apparatus10to display a message notifying that the operational failure has occurred in the image forming portion5. Thus, a user of the image forming system100can easily specify the first sheet Sh1that might be including a defective image.

In Step S16, the test processing portion71determines whether or not the number of sheets Sh1from which the test images Im1have been read in Step S12(the number of read sheets) has reached the predetermined number of sheets N. Then, when the number of read sheets has reached the predetermined number of sheets N (S16: Yes), the test processing portion71shifts the processing to Step S17. On the other hand, when the number of read sheets has not reached the predetermined number of sheets N (S16: No), the test processing portion71shifts the processing back to Step S11.

In Step S17, the test processing portion71resets the number of read sheets (resets to “0”) and shifts the processing back to Step S11. The processing of Step S11to Step S17is an example of a test step according to the present disclosure.

It is noted that the test processing portion71may set the number of test images Im1to be included in the test image group according to a predetermined user operation. In other words, the number of test images Im1to be included in the test image group can be set arbitrarily by the user.

In this case, when the number of test images Im1to be included in the test image group, that is set by the user operation, exceeds a first specific number that is based on the number of sheets Sh1not yet discharged, that are present in the section more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1, the test processing portion71may notify to that effect. The first specific number is a number obtained by adding “1” to the number of sheets Sh1not yet discharged, that are present in the section more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1. Thus, it is possible to notify the user that it is impossible to notify that an operational failure has occurred in the image forming portion5at the discharge timing of the first sheet Sh1that might be including a defective image.

As shown inFIG.17, the image forming system100according to the present embodiment is different from the image forming system100according to Embodiment 3 in the point of including a second discharge portion15in addition to the first discharge portion14. For example, the second discharge portion15is a sheet discharge tray. Further, in the image forming system100according to the present embodiment, the processing content of the test processing portion71differs from that of the image forming system100according to Embodiment 3. Hereinafter, configurations similar to those of Embodiment 3 will be denoted by common symbols, and descriptions will be omitted as appropriate.

Instead of notifying that the test image Im1has been determined as having a defect at the timing at which the specific sheet is discharged, the test processing portion71according to the present embodiment switches the discharge destination of the specific sheet and subsequent sheets Sh1from the first discharge portion14to the second discharge portion15.

In addition, the test processing portion71according to the present embodiment sets the number of test images Im1to be included in the test image group based on the number of sheets Sh1not yet discharged, that are present in a section up to a branching position P1(seeFIG.17) between a conveying path that reaches the first discharge portion14and a conveying path that reaches the second discharge portion15, the section being more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1.

For example, in the image forming system100, it is assumed that the number of sheets Sh1not yet discharged (Sh22), that are present in the section up to the branching position P1, the section being more on the downstream side than the sheet Sh1including the test image Im1as the test target (Sh21) on the conveying path K1at the time of the test of the test image Im1, is two (seeFIG.17). In this case, the test processing portion71sets “3” obtained by adding “1” to the number of sheets Sh1not yet discharged (Sh22) as the number of test images Im1to be included in the test image group. Thus, when it is determined that there is a defect in the test image Im1formed on the sheet Sh21, the discharge destination of the specific sheet can be switched. It is noted that in the image forming system100, the number of sheets Sh1not yet discharged, that are present in the section up to the branching position P1, the section being more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1, can be specified based on a length of the section, a size of the sheet Sh1to be conveyed, and intervals among the sheets Sh1during the conveyance.

It is noted that the test processing portion71may set the number of test images Im1to be included in the test image group according to a predetermined user operation.

In this case, when the number of test images Im1to be included in the test image group, that is set by the user operation, exceeds a second specific number that is based on the number of sheets Sh1not yet discharged, that are present in the section up to the branching position P1, the section being more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1, the test processing portion71may notify to that effect. The second specific number is a number obtained by adding “1” to the number of sheets Sh1not yet discharged, that are present in the section up to the branching position P1, the section being more on the downstream side than the sheet Sh1including the test image Im1as the test target on the conveying path K1at the time of the test of the test image Im1. Thus, it is possible to notify the user that it is impossible to discharge, in the identifiable manner, the first sheet Sh1that might be including a defective image and the subsequent sheets Sh1.

Notes of Disclosure

Hereinafter, a general outline of the disclosure extracted from the embodiments described above will be noted. It is noted that the respective configurations and processing functions described in the notes below can be sorted and arbitrarily combined as appropriate.

An image forming apparatus, including:an image forming portion which forms an image on a sheet using a plurality of recording elements;an image reading portion which reads the image on the sheet; anda test processing portion which causes the image forming portion to form a test image in a marginal region of the sheet, and causes the image reading portion to read the test image, in whichthe test processing portion is capable of executing a divisional test in which only some of the plurality of recording elements are used for forming a single test image to be formed on a single sheet and all of the plurality of recording elements are used for forming a test image group constituted of a plurality of the test images to be formed on a plurality of the sheets.

The image forming apparatus according to note 1, in which the test processing portion is capable of changing a number of the test images to be included in the test image group.

The image forming apparatus according to note 1 or 2, in which the test processing portion changes a mode of the test image in sync with a timing at which an attribute of the sheet is changed.

The image forming apparatus according to note 3, in which the test processing portion executes, for a first sheet among the sheets after the change of the attribute, an overall test in which all of the plurality of recording elements are used for forming a single test image to be formed on a single sheet.

The image forming apparatus according to any one of notes 1 to 4, further includinga sheet conveying device which conveys the sheet, in which the image reading portion is arranged more on a downstream side of a conveying direction of the sheet than the image forming portion.