Image forming device

Abstract

To provide an image forming device capable of suppressing a consumption amount of consumables.SOLUTION: An image forming device 1 comprises an image forming unit 30 and a control unit 110. The image forming unit 30 forms an image on a sheet P1. The control unit 110 controls the image forming unit 30. The control unit 110 acquires a pre-image G1 and a formation image G2. The pre-image G1 represents an image previously formed on the sheet P1. The formation image G2 represents an image to be formed. The control unit 110 identifies a differential portion d1 with respect to the formation image G2 in the pre-image G1. The control unit 110 generates an output image G3 on the basis of the differential portion d1. The control unit 110 controls the image forming unit 30 so as to form the output image G3 on the sheet P1.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] The image processing device described in Patent Document 1 re-evaluates printed matter that has already been ejected when the detection threshold and / or detection items for image abnormalities are changed. As a result, printed matter that has been re-evaluated as non-defective can be reused. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-205567 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the image processing device described in Patent Document 1 cannot reduce the consumption of consumables in the printing device.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus that can reduce the consumption of consumables. [Means for solving the problem]

[0006] The image forming apparatus according to the present invention includes an image forming unit and a control unit. The image forming unit forms an image on a sheet. The control unit controls the image forming unit. The control unit acquires a preliminary image and a formed image. The preliminary image indicates an image that has been formed in advance on the sheet. The formed image indicates an image to be formed. The control unit identifies a difference portion in the preliminary image relative to the formed image. The control unit generates an output image based on the difference portion. The control unit controls the image forming unit to form the output image on the sheet. [Effects of the Invention]

[0007] According to the present invention, consumption of consumables can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating an image forming apparatus according to a first embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] 1A is a diagram showing a preliminary image, FIG. 1B is a diagram showing a formed image, FIG. 1C is a diagram showing an output image, and FIG. 1D is a diagram showing an image printed on a sheet. [Figure 5] 3 is a flowchart showing an image forming method of the image forming apparatus 1 according to the embodiment of the present invention. [Figure 6] 3 is a flowchart showing an image forming method of the image forming apparatus 1 according to the embodiment of the present invention. [Figure 7] 4 is a flowchart showing a method for generating an output image of the image forming apparatus 1 according to the embodiment of the present invention. [Figure 8] FIG. 10 is a schematic diagram showing an image forming apparatus according to a second embodiment of the present invention. [Figure 9] 3 is a flowchart showing an image forming method of the image forming apparatus 1 according to the embodiment of the present invention. [Figure 10] 3 is a flowchart showing an image forming method of the image forming apparatus 1 according to the embodiment of the present invention. [Figure 11] 3 is a flowchart showing an image forming method of the image forming apparatus 1 according to the embodiment of the present invention. [Figure 12] 3 is a flowchart showing an image forming method of the image forming apparatus 1 according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and description thereof will not be repeated.

[0010] [Embodiment 1] An image forming apparatus 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an image forming apparatus 1 according to a first embodiment of the present invention. In this embodiment, the image forming apparatus 1 is a color copier.

[0011] 1, the image forming apparatus 1 includes an image reading unit 5, a paper feeding unit 10, an image forming unit 30, a fixing unit 40, a discharge unit 50, an input / output unit 60, and a control board 100. The image forming apparatus 1 also includes a first conveying unit L1, a second conveying unit L2, and a third conveying unit L3.

[0012] The image reading unit 5 scans an original document to obtain image data. For example, the image reading unit 5 reads a preliminary image formed on a printed sheet P1. The preliminary image is an image formed on a sheet in advance.

[0013] The paper feed unit 10 has a plurality of paper feed cassettes 11 and a plurality of first paper feed roller groups 12. Each paper feed cassette 11 can accommodate a plurality of sheets P. Each first paper feed roller group 12 feeds the sheets P accommodated in the corresponding paper feed cassette 11 one by one to the first conveying unit L1.

[0014] The sheet feeding unit 10 further includes a manual feed tray 16 and a second sheet feed roller group 17. The manual feed tray 16 is capable of holding a plurality of sheets P. The second sheet feed roller group 17 feeds the sheets P placed on the manual feed tray 16 one by one to the first conveying unit L1.

[0015] The first conveying section L1 conveys the sheet P fed by the paper feeding section 10 to the fixing section 40 via the transfer device 35 provided in the image forming section 30.

[0016] The image forming unit 30 forms an image on the sheet P transported by the first transport unit L1 to the transfer device 35. In addition to the transfer device 35, the image forming unit 30 includes a toner supply device 31, an exposure device 32, a photosensitive drum 33, and a development roller 34.

[0017] The toner supply device 31 supplies toner to the developing roller 34 .

[0018] The exposure device 32 irradiates the photosensitive drum 33 with laser light based on image data, exposing it to form an electrostatic latent image. The development roller 34 supplies toner to the corresponding photosensitive drum 33 to develop the toner image. As a result, a toner image is formed on the photosensitive drum 33.

[0019] The transfer device 35 transfers the toner image formed on the photosensitive drum 33 onto the sheet P. The sheet P onto which the toner image has been transferred is transported to the fixing unit 40. When an image is formed using toners of multiple colors, the transfer device 35 transfers the toner images formed on the photosensitive drums 33 corresponding to the respective colors onto the sheet P in an overlapping manner.

[0020] The fixing unit 40 has a heating member 41 and a pressure member 42. The fixing unit 40 fixes the unfixed toner image onto the sheet P by applying heat and pressure to the sheet P with the heating member 41 and the pressure member 42.

[0021] The second conveying section L2 conveys the sheet P conveyed from the fixing section 40 toward the third conveying section L3 or the discharge section 50.

[0022] The discharge section 50 discharges the sheet P to the outside of the apparatus main body.

[0023] The third transport section L3 is used during double-sided printing and reverse side printing. The third transport section L3 inverts the sheet P transported from the second transport section L2 and transports it to the first transport section L1. Specifically, the third transport section L3 transports the sheet P to a position in the first transport section L1 downstream of the paper feed section 10 and upstream of the transfer device 35. As a result, the inverted sheet P is transported again by the first transport section L1. As a result, during double-sided printing, images based on the input image data are formed on both sides of the sheet P.

[0024] The input / output unit 60 is disposed on the top of the main body. The input / output unit 60 displays an input screen. The input / output unit 60 accepts input operations by the user and generates input data according to the input operations. Furthermore, the input / output unit 60 outputs the results processed by the control unit 110. The input / output unit 60 is, for example, a touch panel or an operation panel having operation buttons and a touch panel.

[0025] The control board 100 is equipped with a control unit 110, a storage unit 120, and a communication unit .

[0026] The control unit 110 is a hardware circuit configured by a processor such as a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), etc. The control unit 110 controls the operation of each unit of the image forming apparatus 1 by the processor reading and executing a control program stored in the storage unit 120. The control unit 110 controls, for example, the image forming unit 30.

[0027] The storage unit 120 is configured with an HDD (Hard Disk Drive), RAM (Random Access Memory), and ROM (Read Only Memory). The storage unit 120 may also include an external memory. The external memory is removable media. Examples of the external memory that the storage unit 120 includes are a USB (Universal Serial Bus) memory and an SD (Secure Digital) card. The storage unit 120 stores various types of data and control programs for controlling the operation of each unit of the image forming apparatus 1. The control programs are executed by the control unit 110.

[0028] The communication unit 130 is capable of communicating with electronic devices equipped with communication devices that use the same communication method (protocol). In this embodiment, the communication unit 130 communicates with external devices via a network such as a LAN (Local Area Network). The communication unit 130 is, for example, a communication module (communication device) such as a LAN board.

[0029] The external device is a device used by a user, and specifically, for example, a personal computer or a tablet terminal device. In this embodiment, the user operates the external device to send a request to execute a print job to the image forming apparatus 1. In other words, the user operates the external device to send a formed image to the image forming apparatus 1. The formed image indicates an image to be formed. When the communication unit 130 receives the print job request, the control unit 110 controls the operation of each unit of the image forming apparatus 1 to execute the print job.

[0030] The control unit 110 acquires the preliminary image and the formed image. More specifically, the image reading unit 5 reads the preliminary image formed on the printed sheet P1. The read preliminary image is output to the control unit 110. As a result, the control unit 110 acquires the preliminary image. When the user operates the external device, the formed image is sent from the external device to the image forming apparatus 1. As a result, the control unit 110 acquires the formed image via the communication unit 130.

[0031] The control unit 110 identifies a difference portion in the preliminary image from the formed image. Specifically, the control unit 110 identifies a difference portion in the preliminary image from the formed image by comparing the preliminary image with the formed image. For example, the control unit 110 identifies a portion at the same coordinates (position) where an image is formed in the preliminary image but not in the formed image as a difference portion. The control unit 110 also identifies a portion at the same coordinates (position) where an image is not formed in the preliminary image but is formed in the formed image as a difference portion. The control unit 110 also identifies a portion at the same coordinates (position) where the colors of the preliminary image and the formed image are different as a difference portion.

[0032] The control unit 110 generates an output image based on the difference portion. The control unit 110 controls the image forming unit 30 to form the output image on a sheet. That is, the control unit 110 controls the image forming unit 30 to print only the difference portion between the preliminary image and the formed image on the printed sheet P1. Therefore, the printed sheet P1 can be reused to obtain a desired printed matter. Furthermore, since the printed sheet P1 is reused to print only the difference portion, the amount of toner consumed can be reduced. As described above, the image forming apparatus 1 can reduce the amount of consumables (sheet P1 and toner) consumed.

[0033] Image forming apparatus 1 according to an embodiment of the present invention will be further described with reference to FIGS. 1 to 4. FIG. 2 is a diagram showing sheet P1. FIG. 3 is a diagram showing formed image G2. FIG. 4(a) is a diagram showing preliminary image G1. FIG. 4(b) is a diagram showing formed image G2. FIG. 4(c) is a diagram showing output image G3. FIG. 4(d) is a diagram showing image G4 printed on sheet P. Note that the X and Y coordinates in FIGS. 4(a) to 4(c) are described for the purpose of understanding the invention and are different from the actual absolute coordinates on sheet P1.

[0034] As shown in FIG. 2, sheet P1 is a delivery note. A preliminary image G1 has been formed on sheet P1 in advance. In other words, sheet P1 is a printed sheet P. Here, sheet P1 is a monochrome printout. In other words, sheet P1 is a printout on which black letters and the like are printed on white paper. The preliminary image G1 includes a delivery destination image G11, a date image G12, a delivery source image G13, a title image G14, and a delivery contents image G15.

[0035] The delivery destination image G11 is an image showing delivery destination information. Here, the delivery destination image G11 is an image showing delivery destination information "To: ABC Co., Ltd."

[0036] The date image G12 is an image showing date information. In this example, the date image G12 is an image showing the date information "XX year XX month XX day."

[0037] The supplier image G13 is an image showing supplier information. Here, the supplier image G13 is an image showing supplier information "CCC Corporation."

[0038] The title image G14 is an image showing title information. Here, the title image G14 is an image showing the title information "Delivery Note."

[0039] The delivery content image G15 is an image showing delivery content information, such as the number, product name, unit price, quantity, amount, and total.

[0040] FIG. 3 is a diagram showing a formed image G2. Here, the formed image G2 is a monochrome image. As shown in FIG. 3, the formed image G2 includes a delivery destination image G21, a date image G22, a delivery source image G23, a title image G24, and a delivery contents image G25. The date image G12, delivery source image G13, title image G14, and delivery contents image G15 included in the preview image G1 shown in FIG. 2 are the same as the date image G22, delivery source image G23, title image G24, and delivery contents image G25 included in the formed image G2 shown in FIG. 3, respectively. On the other hand, the delivery destination image G11 included in the preview image G1 shown in FIG. 2 is different from the delivery destination image G21 included in the formed image G2 shown in FIG. 3. Specifically, the second character "B" in the character string shown in the delivery destination image G11 is different from the second character "R" in the character string shown in the delivery destination image G21.

[0041] When a user reuses a printed sheet P1 for printing, the user first scans the printed sheet P1 using the image forming apparatus 1. As a result, the image reading unit 5 reads a preliminary image G1 formed on the printed sheet P1. The read preliminary image G1 is output to the control unit 110. As a result, the control unit 110 acquires the preliminary image G1.

[0042] Next, the user operates the external device to transmit the formed image G2 to the image forming apparatus 1. As a result, the control unit 110 acquires the formed image G2 via the communication unit .

[0043] Next, the user places the scanned and printed sheet P1 on the manual feed tray 16.

[0044] The control unit 110 identifies a difference between the preliminary image G1 and the formed image G2. Here, the second character "B" of the character string shown in the delivery destination image G11 of the preliminary image G1 is different from the second character "R" of the character string shown in the delivery destination image G21 of the formed image G2.

[0045] Identification of the difference portion d1 will be described with reference to Figures 4(a) to 4(d). Below, generation of the output image G3 will be described, focusing on the second character "B" of the character string shown in the delivery destination image G11 and the second character "R" of the character string shown in the delivery destination image G21.

[0046] As shown in FIG. 4(a), the pre-image G1 is an image showing the letter B.

[0047] As shown in FIG. 4(b), the formed image G2 is an image showing the letter R.

[0048] As shown in FIG. 4(c), the control unit 110 identifies a difference portion d1 in the preliminary image G1 relative to the formed image G2. The control unit 110 identifies the difference portion d1 in pixel units. The pixel resolution corresponds to, for example, the scanning resolution of the image reading unit 5. Here, the control unit 110 identifies pixel PX1 (X=2, Y=1), pixel PX2 (X=3, Y=1), pixel PX3 (X=4, Y=1), and pixel PX4 (X=2, Y=1) as the difference portion d1. The control unit 110 identifies a first portion d11 and a second portion d12. The first portion d11 indicates a portion of the difference portion d1 where an image is formed in the preliminary image G1. In other words, the first portion d11 indicates a portion in the preliminary image G1 where black is replaced with white. Here, the control unit 110 identifies pixel PX1 (X=2, Y=1), pixel PX2 (X=3, Y=1), and pixel PX3 (X=4, Y=1) as the first portion d11. The second portion d12 indicates a portion of the difference portion d1 where no image is formed in the preliminary image G1. In other words, the second portion d12 indicates a portion in the preliminary image G1 where white is replaced with black. Here, the control unit 110 identifies pixel PX4 (X=5, Y=1) as the second portion d12.

[0049] The control unit 110 sets the first portion d11 to the color of the second portion d12. Meanwhile, the control unit 110 sets the second portion d12 to the color of the first portion d11. Here, the color of the first portion d11 is black. The color of the second portion d12 is white. The control unit 110 sets the first portion d11 to the color of the second portion d12 and sets the second portion d12 to the color of the first portion d11, and generates an output image G3.

[0050] The control unit 110 controls the image forming unit 30 to form the output image G3 on the printed sheet P1. That is, the printed sheet P1 is reprinted on the first portion d11, where an image is formed in the preliminary image G1 but not in the formed image G2, i.e., the black portion of the printed sheet P1 in the differential portion d1 is filled in white. On the other hand, the printed sheet P1 is reprinted on the second portion d12, where an image is not formed in the preliminary image G1 but is formed in the formed image G2, i.e., the white portion of the printed sheet P1 in the differential portion d1 is filled in black. As a result, as shown in FIG. 4(d), an image G4 can be obtained in which the letter "B" formed on the printed sheet P1 is replaced with the letter "R." In this way, the image forming apparatus 1 reuses the printed sheet P1 to form an image only on the differential portion d1. This reduces the consumption of consumables (sheet P1 and toner).

[0051] An image forming method of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the image forming method of the image forming apparatus 1 according to the embodiment of the present invention. An image is formed on a printed sheet P1 by executing the processes of steps S102 to S110 shown in Fig. 5.

[0052] Step S102: The control unit 110 acquires a preliminary image G1. Specifically, the image reading unit 5 reads the preliminary image G1 formed on the printed sheet P1. The read preliminary image G1 is output to the control unit 110. As a result, the control unit 110 acquires the preliminary image G1. The process proceeds to step S104.

[0053] Step S104: Control unit 110 acquires formed image G2. Specifically, the user operates an external device to transmit formed image G2 to image forming apparatus 1. As a result, control unit 110 acquires formed image G2 via communication unit 130. The process proceeds to step S106.

[0054] Step S106: The control unit 110 identifies a difference portion d1 in the preliminary image G1 relative to the formed image G2. The process proceeds to step S108.

[0055] Step S108: The control unit 110 generates an output image G3 based on the difference portion d1, and the process proceeds to step S110.

[0056] Step S110: The control unit 110 controls the image forming unit 30 to form the output image G3 on the printed sheet P. The process then ends.

[0057] As described above with reference to FIGS. 1 to 5, the control unit 110 identifies the difference portion d1 in the preliminary image G1 relative to the formed image G2. The control unit 110 generates an output image G3 based on the difference portion d1. The control unit 110 controls the image forming unit 30 to form the output image G3 on the sheet P1. Therefore, the printed sheet P1 can be reused to obtain a desired printed matter. The control unit 110 also controls the image forming unit 30 to print only the difference portion d1 between the preliminary image G1 and the formed image G2. Furthermore, since the printed sheet P1 is reused to print only the difference portion d1, toner consumption can be reduced. As described above, the image forming apparatus 1 can reduce consumption of consumables (sheet P1 and toner).

[0058] Furthermore, the control unit 110 identifies the difference portion d1 in pixel units. Therefore, the difference portion d1 can be identified in detail. As a result, the quality of the printed matter printed by reusing the printed sheet P1 can be improved.

[0059] Furthermore, the control unit 110 sets the first portion d11 to the color of the second portion d12, sets the second portion d12 to the color of the first portion d11, and generates the output image G3. Therefore, for example, the printed sheet P1 is reprinted so that the black portions of the printed sheet P1 in the differential portion d1 are filled in white. The printed sheet P1 is also reprinted so that the white portions of the printed sheet P1 in the differential portion d1 are filled in black. In this way, the image forming apparatus 1 reuses the printed sheet P1 to form an image only on the differential portion d1. This makes it possible to reduce consumption of consumables (sheet P1 and toner).

[0060] The first portion d11 is black, and the second portion d12 is white. Therefore, the monochrome printed sheet P1 can be reused to obtain a desired printed matter.

[0061] The control unit 110 may determine the color of the second portion d12 based on the preliminary image G1 read by the image reading unit 5. That is, the control unit 110 may determine the color of the portion of the preliminary image G1 where no image is formed based on the preliminary image G1 read by the image reading unit 5. In other words, the control unit 110 may determine the paper color of the printed sheet P1 based on the preliminary image G1 read by the image reading unit 5. Therefore, the control unit 110 can determine the color of the second portion d12 of the output image G3 according to the paper color of the printed sheet P1. As a result, the printed sheet P1 can be reused to obtain a desired printed product according to the paper color of the printed sheet P1. For example, if the paper color of the printed sheet P1 is light blue, the control unit 110 controls the image forming unit 30 to fill the first portion d11 (the portion where an image is formed in the preliminary image G1) from black to light blue.

[0062] It is preferable that the control unit 110 determines whether or not to form an image on the printed sheet P1 based on whether or not the difference portion d1 is equal to or smaller than a threshold value.

[0063] An image forming method of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the image forming method of the image forming apparatus 1 according to the embodiment of the present invention. An image is formed on a printed sheet P1 by executing the processes of steps S202 to S214 shown in Fig. 6. The flowchart shown in Fig. 6 is similar to the flowchart shown in Fig. 5 except that it is determined whether or not to form an image on a printed sheet P1 based on whether the difference portion d1 is equal to or smaller than a threshold value, and therefore, duplicated explanations will be omitted to avoid redundancy.

[0064] Steps S202 to S206: The same processes as steps S102 to S106 shown in FIG. 5 are performed.

[0065] Step S208: The control unit 110 determines whether the difference portion d1 is equal to or less than a threshold. For example, the control unit 110 determines whether the ratio of the difference portion d1 to the entire sheet P is equal to or less than a threshold. In this case, the threshold is, for example, 30%. Alternatively, the control unit 110 may determine whether the area (number of pixels) of the difference portion d1 is equal to or less than a threshold. The threshold is stored in the storage unit 120. If the control unit 110 determines that the difference portion d1 is not equal to or less than the threshold (Step S208: No), the process proceeds to Step S214. If the control unit 110 determines that the difference portion d1 is equal to or less than the threshold (Step S208: Yes), the process proceeds to Step S210.

[0066] Step S210: The control unit 110 generates an output image G3 based on the difference portion d1. The process proceeds to step S212.

[0067] Step S212: The control unit 110 controls the image forming unit 30 to form the output image G3 on the printed sheet P1, and the process ends.

[0068] Step S214: The control unit 110 controls the image forming unit 30 so as not to form an image on the printed sheet P1, and the process ends.

[0069] As described above with reference to FIG. 6, when the differential portion d1 is equal to or less than the threshold, the image forming unit 30 is controlled to form the output image G3 on the sheet. On the other hand, when the differential portion d1 exceeds the threshold, the image forming unit 30 is controlled not to form the output image G3 on the sheet. If the differential portion d1 is large, reprinting the printed sheet P1 may result in more consumption of consumables (toner) than printing on a blank sheet P. For this reason, when the differential portion d1 exceeds the threshold, that is, when the differential portion d1 is large, the control unit 110 controls the image forming unit 30 not to form the output image G3 on the sheet P1. Therefore, the consumption of consumables (toner) can be appropriately suppressed.

[0070] An image forming method of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a method for generating an output image G3 of the image forming apparatus 1 according to the embodiment of the present invention. The output image G3 is formed by executing the processes of steps S210a and S210b shown in Fig. 7.

[0071] Step S210a: The control unit 110 identifies the first part d11 and the second part d12. The process proceeds to step S210b.

[0072] Step S210b: The control unit 110 sets the color of the first portion d11 to the color of the second portion d12, sets the color of the second portion d12 to the color of the first portion d11, and generates an output image G3, and then the process ends.

[0073] [Embodiment 2] In embodiment 1, the preliminary image G1 formed on the printed sheet P1 was read by the image reading unit 5, but the preliminary image G1 formed on the printed sheet P1 may also be read by the line sensor 21 and the line sensor 22.

[0074] An image forming apparatus 1 according to a second embodiment of the present invention will be described with reference to Fig. 8. Fig. 8 is a schematic diagram showing an image forming apparatus 1 according to a second embodiment of the present invention. The image forming apparatus 1 shown in Fig. 8 is similar to the image forming apparatus 1 shown in Fig. 8 except that it further includes a line sensor 21 and a line sensor 22, and therefore, redundant description will be omitted to avoid redundancy.

[0075] 8, the image forming apparatus 1 includes an image reading unit 5, a paper feeding unit 10, an image forming unit 30, a fixing unit 40, a discharge unit 50, an input / output unit 60, and a control board 100, as well as a line sensor 21 and a line sensor 22. The line sensors 21 and 22 are examples of an "image reading unit."

[0076] The image forming apparatus 1 includes a dedicated paper feed cassette 11a that stores printed sheets P1. The printed sheets P1 have a first side and a second side. A first preliminary image G1a is formed on the first side. The second side is opposite to the first side. A second preliminary image G1b is formed on the second side.

[0077] The line sensor 21 is provided in the first conveying section L1. Specifically, the line sensor 21 is provided at a position downstream of the dedicated paper feed cassette 11a and upstream of the transfer device 35. The line sensor 21 reads a first preliminary image G1a formed on a first side of a printed sheet P1 fed from the dedicated paper feed cassette 11a. The line sensor 21 then generates read image data based on the read image. Note that the image forming apparatus 1 may be provided with an image sensor such as an area sensor instead of the line sensor 21.

[0078] The line sensor 22 is provided in the third conveying section L3. The line sensor 22 reads the second preliminary image G1b formed on the second surface of the inverted printed sheet P1. The line sensor 22 then generates read image data based on the read image. Note that the image forming apparatus 1 may be provided with an image sensor such as an area sensor instead of the line sensor 22.

[0079] The control unit 110 identifies a first-side difference portion d1a indicating a difference portion d1 in the first preliminary image G1a relative to the formed image G2. The control unit 110 determines whether the first-side difference portion d1a is equal to or smaller than a threshold. If the control unit 110 determines that the first-side difference portion d1a is equal to or smaller than the threshold, the control unit 110 controls the image forming unit 30 to form an output image G3 on the first side of the printed sheet P1. In this case, after the image forming unit 30 forms the output image G3 on the first side of the printed sheet P1, the control unit 110 controls the second conveying unit L2 to convey the sheet P1 conveyed from the fixing unit 40 toward the discharge unit 50. As a result, the sheet P1 is discharged from the discharge unit 50.

[0080] If the control unit 110 determines that the first-side difference portion d1a exceeds the threshold, it identifies the second-side difference portion d1b, which indicates the difference portion d1 in the second preliminary image G1b relative to the formed image G2. The control unit 110 determines whether the second-side difference portion d1b is equal to or less than the threshold. If the second-side difference portion d1b is equal to or less than the threshold, it controls the image forming unit 30 to form the output image G3 on the second side of the sheet. In this case, after the image forming unit 30 forms the output image G3 on the second side of the printed sheet P1, the control unit 110 controls the second conveying unit L2 to convey the sheet P1 conveyed from the fixing unit 40 toward the discharge unit 50. As a result, the sheet P1 is discharged from the discharge unit 50.

[0081] If the second-side difference portion d1b exceeds the threshold, the image forming unit 30 is controlled so as not to form an image on the printed sheet P1. In this case, the printed sheet P1 is discharged without forming an image on either the first or second side of the printed sheet P1.

[0082] An image forming method of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to Figures 9 and 10. Figures 9 and 10 are flowcharts showing the image forming method of the image forming apparatus 1 according to the embodiment of the present invention. An image is formed on a printed sheet P1 by executing the processes of steps S302 to S324 shown in Figures 9 and 10.

[0083] Step S302: The control unit 110 acquires the first preliminary image G1a. Specifically, the line sensor 21 reads the first preliminary image G1a formed on the first surface of the printed sheet P1. The read first preliminary image G1a is output to the control unit 110. As a result, the control unit 110 acquires the first preliminary image G1a. The process proceeds to step S304.

[0084] Step S304: Control unit 110 acquires formed image G2. Specifically, the user operates an external device to transmit formed image G2 to image forming apparatus 1. As a result, control unit 110 acquires formed image G2 via communication unit 130. The process proceeds to step S306.

[0085] Step S306: The control unit 110 identifies the first-side difference portion d1a in the first preliminary image G1a relative to the formed image G2. The process proceeds to step S308.

[0086] Step S308: The control unit 110 determines whether the first-side difference portion d1a is equal to or less than a threshold. For example, the control unit 110 determines whether the ratio of the first-side difference portion d1a to the entire sheet P is equal to or less than a threshold. In this case, the threshold is, for example, 30%. If the control unit 110 determines that the first-side difference portion d1a is not equal to or less than the threshold (Step S308: No), the process proceeds to Step S314 shown in FIG. 10. If the control unit 110 determines that the first-side difference portion d1a is equal to or less than the threshold (Step S308: Yes), the process proceeds to Step S310.

[0087] Step S310: The control unit 110 generates an output image G3 based on the first-side difference portion d1a. The process proceeds to step S312.

[0088] Step S312: The control unit 110 controls the image forming unit 30 to form the output image G3 on the first side of the printed sheet P1, and the process ends.

[0089] Step S314: The control unit 110 acquires the second preliminary image G1b. Specifically, the line sensor 22 reads the second preliminary image G1b formed on the second surface of the printed sheet P1. The read second preliminary image G1b is output to the control unit 110. As a result, the control unit 110 acquires the second preliminary image G1b. The process proceeds to step S316.

[0090] Step S316: The control unit 110 identifies the second surface difference portion d1b in the second preliminary image G1b relative to the formed image G2. The process proceeds to step S318.

[0091] Step S318: The control unit 110 determines whether the second-side difference portion d1b is equal to or less than a threshold. For example, the control unit 110 determines whether the ratio of the difference portion d1 to the entire sheet P is equal to or less than a threshold. In this case, the threshold is, for example, 30%. If the control unit 110 determines that the second-side difference portion d1b is not equal to or less than the threshold (Step S318: No), the process proceeds to Step S324. If the control unit 110 determines that the second-side difference portion d1b is equal to or less than the threshold (Step S318: Yes), the process proceeds to Step S320.

[0092] Step S320: The control unit 110 generates an output image G3 based on the second plane difference portion d1b. The process proceeds to step S322.

[0093] Step S322: The control unit 110 controls the image forming unit 30 to form the output image G3 on the second side of the printed sheet P1, and the process ends.

[0094] Step S324: The control unit 110 controls the image forming unit 30 so as not to form an image on the printed sheet P1, and the process ends.

[0095] As described above with reference to FIGS. 8 to 10, when the control unit 110 determines that the first-side differential portion d1a is equal to or less than the threshold, the control unit 110 controls the image forming unit 30 to form the output image G3 on the first side of the printed sheet P1. When the control unit 110 determines that the first-side differential portion d1a exceeds the threshold, the control unit 110 determines whether the second-side differential portion d1b is equal to or less than the threshold. When the second-side differential portion d1b is equal to or less than the threshold, the control unit 110 controls the image forming unit 30 to form the output image G3 on the second side of the printed sheet P1. When the second-side differential portion d1b exceeds the threshold, no image is formed on the printed sheet P1. Therefore, when the first-side differential portion d1a on the first side of the printed sheet P1 exceeds the threshold, the output image G3 can be formed on the second side of the printed sheet P1. Therefore, the printed sheet P1 can be appropriately reused. As a result, the consumption of consumables (toner and sheets) can be appropriately reduced.

[0096] An image forming method of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to Figures 11 and 12. Figures 11 and 12 are flowcharts showing the image forming method of the image forming apparatus 1 according to the embodiment of the present invention. An image is formed on a printed sheet P1 by executing the processes of steps S402 to S424 shown in Figures 11 and 12. The flowcharts shown in Figures 11 and 12 are similar to the flowcharts shown in Figures 9 and 10, except that the first-side difference portion d1a and the second-side difference portion d1b are compared, and an output image G3 is formed on the side of the printed sheet P1 corresponding to the smaller difference portion d1, and therefore, duplicated explanations will be omitted to avoid redundancy.

[0097] Step S402: The control unit 110 acquires the first preliminary image G1a. Specifically, the line sensor 21 reads the first preliminary image G1a formed on the first surface of the printed sheet P1. The read first preliminary image G1a is output to the control unit 110. As a result, the control unit 110 acquires the first preliminary image G1a. The process proceeds to step S404.

[0098] Step S404: The control unit 110 acquires the second preliminary image G1b. Specifically, the line sensor 22 reads the second preliminary image G1b formed on the second surface of the printed sheet P1. The read second preliminary image G1b is output to the control unit 110. As a result, the control unit 110 acquires the second preliminary image G1b. The process proceeds to step S406.

[0099] Step S406: Control unit 110 acquires formed image G2. Specifically, the user operates an external device to transmit formed image G2 to image forming apparatus 1. As a result, control unit 110 acquires formed image G2 via communication unit 130. The process proceeds to step S408.

[0100] Step S408: The control unit 110 identifies a first-side difference portion d1a in the first preliminary image G1a relative to the formed image G2. The control unit 110 identifies a second-side difference portion d1b in the second preliminary image G1b relative to the formed image G2. The process proceeds to step S410 shown in FIG. 12.

[0101] Step S410: The control unit 110 determines whether at least one of the first-side difference portion d1a and the second-side difference portion d1b is equal to or less than a threshold. For example, the control unit 110 determines whether the ratio of the difference portion d1 to the entire sheet P is equal to or less than a threshold. In this case, the threshold is, for example, 30%. If the control unit 110 determines that at least one of the first-side difference portion d1a and the second-side difference portion d1b is not equal to or less than the threshold (Step S410: No), that is, if the first-side difference portion d1a and the second-side difference portion d1b exceed the threshold, the process proceeds to Step S424. If the control unit 110 determines that at least one of the first-side difference portion d1a and the second-side difference portion d1b is equal to or less than the threshold (Step S410: Yes), the process proceeds to Step S412.

[0102] Step S412: If control unit 110 determines that at least one of first side difference portion d1a and second side difference portion d1b is equal to or less than the threshold (step S410: Yes), first side difference portion d1a and second side difference portion d1b are compared. The process proceeds to step S414.

[0103] Step S414: The control unit 110 determines whether the first-side difference portion d1a is equal to or smaller than the second-side difference portion d1b. If the control unit 110 determines that the first-side difference portion d1a is not equal to or smaller than the second-side difference portion d1b (Step S414: No), that is, if the control unit 110 determines that the second-side difference portion d1b is smaller than the first-side difference portion d1a, the process proceeds to Step S420. If the control unit 110 determines that the first-side difference portion d1a is equal to or smaller than the second-side difference portion d1b (Step S414: Yes), the process proceeds to Step S416.

[0104] Step S416: The control unit 110 generates an output image G3 based on the first-side difference portion d1a. The process proceeds to step S418.

[0105] Step S418: The control unit 110 controls the image forming unit 30 to form the output image G3 on the first side of the printed sheet P1, and the process ends.

[0106] Step S420: The control unit 110 generates an output image G3 based on the second plane difference portion d1b. The process proceeds to step S422.

[0107] Step S422: The control unit 110 controls the image forming unit 30 to form the output image G3 on the second side of the printed sheet P1, and the process ends.

[0108] As described above with reference to FIGS. 11 and 12, when the control unit 110 determines that at least one of the first-side difference portion d1a and the second-side difference portion d1b is equal to or smaller than the threshold, the control unit 110 compares the first-side difference portion d1a with the second-side difference portion d1b. When the control unit 110 determines that the first-side difference portion d1a is equal to or smaller than the second-side difference portion d1b, the control unit 110 controls the image forming unit 30 to form the output image G3 on the first side of the sheet P1. On the other hand, when the control unit 110 determines that the second-side difference portion d1b is smaller than the first-side difference portion d1a, the control unit 110 controls the image forming unit 30 to form the output image G3 on the second side of the sheet P1. Therefore, the output image G3 can be formed on the side with the smaller difference portion d1. As a result, the consumption of consumables (toner and sheets) can be appropriately reduced.

[0109] The embodiments of the present invention have been described above with reference to the drawings (FIGS. 1 to 12). However, the present invention is not limited to the above-described embodiments, and can be embodied in various forms without departing from the spirit of the present invention (for example, (1) to (2) shown below). The drawings mainly show each component in a schematic manner for ease of understanding, and the thickness, length, number, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. Furthermore, the materials, shapes, dimensions, etc. of each component shown in the above-described embodiments are merely examples and are not particularly limited, and various modifications are possible within a range that does not substantially depart from the effects of the present invention.

[0110] (1) The image forming apparatus 1 described with reference to Figures 1 to 12 is an electrophotographic multifunction device, but the present invention is not limited to this. The image forming apparatus 1 may be, for example, an inkjet multifunction device. In this case, the consumption of ink as a consumable item can be reduced.

[0111] (2) In the image forming apparatus 1 described with reference to Figures 1 to 12, the preliminary image G1 formed on the printed sheet P1 is read by the image reading unit 5, line sensor 21, or line sensor 22 provided in the image forming apparatus 1, but the present invention is not limited to this. For example, the preliminary image G1 may be image data obtained by reading the printed sheet P1 with an image reading device separate from the image forming apparatus 1. Alternatively, the preliminary image G1 may be image data obtained by capturing an image of the printed sheet P1 with an electronic device such as a smartphone. [Industrial Applicability]

[0112] The present invention can be used in the field of image forming devices. [Explanation of symbols]

[0113] 1. Image forming device 5 Image reading unit 21 Line sensor (image reading unit) 22 Line sensor (image reading unit) 30 Image forming unit 110 control section G1 Pre-image G1a 1st preview image G1b 2nd preview image G2 formed image G3 output image P, P1 seats d1 difference part d11 1st part d12 2nd part d1a 1st side difference part d1b 2nd side difference part

Claims

1. an image forming unit that forms an image on a sheet; a control unit that controls the image forming unit; Equipped with The control unit A pre-image formed on the sheet and a formed image showing an image to be formed are acquired; Identifying a difference portion of the preliminary image relative to the formed image; generating an output image based on the difference portion; an image forming apparatus that controls the image forming unit to form the output image on the sheet;

2. The control unit determining whether the difference is equal to or smaller than a threshold; When it is determined that the difference is equal to or smaller than a threshold value, the image forming unit is controlled to form the output image on the sheet. The image forming apparatus according to claim 1 , wherein when it is determined that the difference portion exceeds a threshold value, the image forming unit is controlled so as not to form the output image on the sheet.

3. The image forming apparatus according to claim 1 , wherein the control unit identifies the difference portion in pixel units.

4. The control unit Identifying a first portion of the difference portion in which an image is formed in the preliminary image and a second portion of the difference portion in which an image is not formed in the preliminary image; 3. The image forming apparatus according to claim 1, wherein the output image is generated by setting the first portion to the color of the second portion and setting the second portion to the color of the first portion.

5. the first portion is black in color; 5. The image forming apparatus according to claim 4, wherein the second portion is white in color.

6. an image reading unit that reads the preliminary image formed on the sheet; The image forming apparatus according to claim 4 , wherein the control unit specifies the color of the second portion based on the preliminary image read by the image reading unit.

7. The sheet is a first surface on which a first preliminary image is formed; a second surface opposite to the first surface and having a second preliminary image formed thereon; and an image reading unit configured to read the first preliminary image formed on the first surface and the second preliminary image formed on the second surface; The control unit Identifying a first surface difference portion indicating a difference portion of the first preliminary image with respect to the formed image; determining whether the first plane difference portion is equal to or smaller than a threshold value; When it is determined that the first-side difference portion is equal to or smaller than a threshold value, the image forming unit is controlled to form the output image on the first side of the sheet; If it is determined that the first-side difference portion exceeds a threshold value, a second-side difference portion indicating a difference portion of the second preliminary image relative to the formed image is identified, and it is determined whether the second-side difference portion is equal to or smaller than a threshold value; When it is determined that the second-side difference portion is equal to or smaller than a threshold value, the image forming unit is controlled to form the output image on the second side of the sheet; 3. The image forming apparatus according to claim 1, wherein when it is determined that the second-side difference portion exceeds a threshold value, the image forming unit is controlled so as not to form an image on the sheet.

8. The sheet is a first surface on which a first preliminary image is formed; a second surface opposite to the first surface and having a second preliminary image formed thereon; and an image reading unit configured to read the first preliminary image formed on the first surface and the second preliminary image formed on the second surface; The control unit a first surface difference portion indicating a difference portion of the first preliminary image with respect to the formed image; a second surface difference portion indicating a difference portion of the second preliminary image with respect to the formed image; Identify the determining whether the first plane difference portion and the second plane difference portion are equal to or smaller than a threshold value; If it is determined that the first side difference portion and the second side difference portion are equal to or smaller than a threshold value, the first side difference portion and the second side difference portion are compared; When it is determined that the first-side difference portion is equal to or smaller than the second-side difference portion, the image forming unit is controlled to form the output image on the first side of the sheet; 3. The image forming apparatus according to claim 1, wherein when it is determined that the second-side difference portion is smaller than the first-side difference portion, the image forming unit is controlled to form the output image on the second side of the sheet.

Images