Image diagnostic method, image diagnostic apparatus, image forming apparatus, and program

Abstract

To provide an image diagnostic method, image diagnostic apparatus, image forming apparatus, and program that enable more accurate image diagnostics. [Solution] An image diagnostic device based on an image formed by an image forming apparatus comprising an image forming engine and a reading unit positioned along a transport path for the medium and reading the medium downstream of the transport path from the image forming position by the image forming engine, performs the following steps: (P1) An adjustment step in which the image forming engine forms a first pattern for adjusting the image forming position, the reading unit reads a first medium on which the first pattern has been formed, and the image forming position is adjusted based on the reading result of the first medium. (P2-P4) After the execution of the adjustment step, a diagnostic step in which the image forming engine forms a second pattern for diagnosing the state of the image forming engine, the reading unit reads a second medium on which the second pattern has been formed, and a diagnostic result of the state of the image forming engine is obtained based on the reading result of the second medium.

Description

Technical Field

[0001] This invention relates to an image diagnosis method, an image diagnosis apparatus, an image forming apparatus, and a program.

Background Art

[0002] There is a technique in which a predetermined test image formed on a medium in an image forming apparatus is read by a reading unit located on the conveyance path of the medium, and the read image is analyzed. Image diagnosis for diagnosing the state of an image forming engine can be performed based on the result of the analysis.

[0003] In the analysis of a read image, detection of image defects such as streaks and noise appearing in the image is performed. The streaks include streaks extending in the conveyance direction (Feed Direction) and streaks extending in a direction perpendicular to the conveyance direction (Cross Direction). The noise includes periodically appearing spot-like noise. By obtaining information such as the presence or absence of these occurrences, the occurrence position, and the frequency from a test image formed on the same type of medium, the state of the image forming engine can be obtained with high accuracy (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the improvement of image quality and productivity in recent years, there is a problem that the state of an image forming engine cannot be obtained with the required accuracy by conventional image diagnosis techniques.

[0006] An object of this invention is to provide an image diagnosis method, an image diagnosis apparatus, an image forming apparatus, and a program capable of performing image diagnosis with higher accuracy. [Means for solving the problem]

[0007] To achieve the above objective, the present invention Image forming engine, A reading unit positioned along the transport path of the medium, which reads the medium downstream of the transport path from the image formation position by the image forming engine, An image diagnostic device based on an image formed by an image forming apparatus equipped with the following features: The image forming engine generates a first pattern for adjusting the image forming position. The reading unit reads the first medium on which the first pattern is formed. An adjustment step to adjust the image formation position based on the reading result of the first medium, After the above adjustment step is performed, The image forming engine generates a second pattern for diagnosing the state of the image forming engine. The reading unit reads the second medium on which the second pattern is formed. A diagnostic step of obtaining a diagnostic result of the state of the image forming engine based on the reading result of the second medium, This is an image-based diagnostic method that performs the following: [Effects of the Invention]

[0008] According to the present invention, there is an effect of being able to perform image diagnosis with greater accuracy. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic front view illustrating the configuration of an image forming apparatus. [Figure 2] This diagram shows the functional block of an image forming apparatus. [Figure 3] This diagram shows the procedure for diagnostic imaging. [Figure 4] This figure shows an example of a first test image used for image position adjustment. [Figure 5] This figure shows an example of a read image from a medium when there is a misalignment in the formed image. [Figure 6] A diagram showing an example of a read image of a medium when there is a deviation in the formed image. [Figure 7] A diagram showing an example of a read image of a medium when there is a deviation in the formed image. [Figure 8] A flowchart showing the control procedure of the position adjustment control process. [Figure 9] A flowchart showing the procedure of image diagnosis. [Figure 10] A diagram showing an example of a second test image for simple image diagnosis. [Figure 11] A flowchart showing the control procedure of the streak and spot detection process. [Figure 12] A flowchart showing the control procedure of the FD streak detection process. [Figure 13] A flowchart showing the control procedure of the spot detection process. [Figure 14] A flowchart showing the control procedure of the CD streak detection process. [Figure 15] A flowchart showing the control procedure of the detailed image diagnosis process. [Figure 16] A flowchart showing the control procedure of the FD streak detailed analysis process. [Figure 17] A flowchart showing the control procedure of the FD streak detailed analysis process. [Figure 18] A flowchart showing the control procedure of the spot detailed analysis process. [Figure 19] A flowchart showing the control procedure of the spot type diagnosis process. [Figure 20] A flowchart showing the control procedure of the spot type diagnosis process. [Figure 21] A flowchart showing the control procedure of the primary transfer output adjustment process. [Figure 22] A flowchart showing the control procedure of the secondary transfer output adjustment process. [Figure 23] A flowchart showing the control procedure of the developing AC bias output adjustment process. [Figure 24] This flowchart shows the control procedure for the CD stenosis detailed analysis process. [Figure 25] This figure shows an example of the initial settings screen for image adjustments. [Figure 26] This figure illustrates the procedure for image diagnosis in another embodiment. [Figure 27] This figure shows an example of a screen displaying the image diagnostic process. [Figure 28] This figure shows an example of a results display screen that appears after performing an image diagnostic. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be described based on the drawings. Figure 1 is a schematic front view illustrating the configuration of the image forming apparatus 1. The image forming apparatus 1 comprises an image forming apparatus body 10, and may also include a paper feed device 40 on the front side of the apparatus body 10 and a paper reader 20 on the rear side of the apparatus body 10. Each device and the apparatus body 10 are electrically and mechanically connected, and paper transport and communication are possible between each device and the apparatus body 10.

[0011] The paper feeder 40 has multiple paper feed stages for storing the medium on which the image is to be formed. The paper feeder 40 can supply the medium stored in the paper feed stages to the main unit 10 of the downstream device. The medium does not have to be paper. For example, the medium may be cloth, plastic, or the like.

[0012] The main body of the device 10 includes an image forming operation unit 11, a main paper feeding unit 12, a transport path 130, a reversing transport path 131, a downstream transport path 132, a retraction transport path 133, an automatic document feeding device 18, a control unit 100, an operation reception unit 141, a display unit 142, and the like.

[0013] The main paper feed unit 12 is located at the bottom of the housing of the main unit 10. The main paper feed unit 12 is equipped with multiple supply trays 12a for various media. Each supply tray 12a holds a medium and can dispense one sheet at a time. The material of the medium does not have to be paper. For example, the medium may be cloth or plastic. Replenishing the supply trays 12a with medium may be done manually by the user. If the supply trays 12a containing the medium to be image formed become empty during the image forming operation, a notification operation may be performed by the display unit 142 or the like to indicate that a medium supply is required. Note that the supply trays referred to here are not limited to the shape of a normal tray, as long as they can hold multiple media and supply them one sheet at a time to the main unit 10.

[0014] A transport path 130 extends within the housing of the main unit 10 of the device. The medium supplied from the paper feed device 40 or the main unit paper feed section 12 is transported along the transport path 130 by guide rollers or the like.

[0015] The image forming unit 11 is an image forming engine that performs the operation of forming an image based on image data. The image forming unit 11 is located adjacent to the middle of the transport path 130. The image forming unit 11 has photoreceptors 11a for each of the cyan, magenta, yellow, and black (CMYK) colors. Around each photoreceptor 11a, there are chargers, laser diodes, developers, cleaning units, etc. (not shown), which are located. The image forming unit 11 also has an intermediate transfer belt 11b that moves around to a position that contacts each photoreceptor 11a. The intermediate transfer belt 11b contacts the medium on the transport path 130 at a secondary transfer section 11c along its length. Further downstream from the secondary transfer section 11c in the medium transport direction of the transport path 130, there is a fixing unit 112.

[0016] When forming an image on a medium, the photoreceptor 11a is uniformly charged by a charger, and then laser light from a laser diode 111 is irradiated onto the photoreceptor 11a according to the image, forming a latent image on the photoreceptor 11a. The latent image on the photoreceptor 11a is developed by a developer to form a toner image. The toner image on the photoreceptor 11a is primary transferred to an intermediate transfer belt 11b. The image on the intermediate transfer belt 11b is secondary transferred to the medium in a secondary transfer unit 11c. The medium on which the image has been formed is transported downstream along the transport path 130, and the image is fixed by a fixer unit 112.

[0017] The transport path 130 branches off from the reverse transport path 131 downstream of the fixing unit 112. Partway along the reverse transport path 131, the downstream transport path 132 branches off and connects to the transport path 130 downstream of the branching point of the reverse transport path 131. In the reverse transport path 131, the retraction transport path 133 branches off downstream of the branching point of the downstream transport path 132. The downstream end of the reverse transport path 131 merges with the transport path 130 upstream of the image forming operation unit 11. The transport path 130 is connected to the transport path 230 of the reading device 20, which is connected downstream of the main body 10 of the device.

[0018] If only one side of the medium is to be image-formed, the medium is transported along the transport path 130 and sent directly to the transport path 230 of the reader 20. If the front and back sides of the medium are to be switched and output after image formation on one side, the medium is first sent from the transport path 130 to the inversion transport path 131. After the medium is transported along the inversion transport path 131 past the branching point of the downstream transport path 132, it is sent back along the inversion transport path 131 and then to the downstream side of the transport path 130 via the downstream transport path 132. If the medium is to be inverted after image formation on the front side to form an image on the back side of the medium, the medium is sent from the transport path 130 to the inversion transport path 131. Then, the medium is sent from the inversion transport path 131 to the retraction transport path 133, the order of the medium is reversed and it is sent to the downstream side of the inversion transport path 131 and returns to the transport path 130. After that, the image forming operation unit 11 forms an image on the back side of the medium.

[0019] The display unit 142 has a display screen 142a. The display screen 142a may be, for example, a liquid crystal display (LCD). The display unit 142 can display information on the display screen 142a according to the control of the control unit 100. The display unit 142 may allow the position and orientation of the display screen 142a to be changed.

[0020] The operation reception unit 141 has a touch panel 141a (see Figure 2) positioned over the display screen 142a and a group of operation keys such as a numeric keypad. The operation reception unit 141 receives input operations to the touch panel 141a and the group of operation keys and outputs the content of the input operations as operation signals to the control unit 100. Note that the operation reception unit 141 and the display unit 142 do not have to be integrated. For example, the operation reception unit 141 may have a pointing device such as a mouse. Alternatively, the operation reception unit 141 may be a separate tablet or mobile terminal from the display unit 142 and capable of transmitting operation signals to the control unit 100 via wireless communication.

[0021] The automatic document feeder 18 (ADF) may be located on the upper part of the housing of the main unit 10, in a position different from the operation reception unit 141. The automatic document feeder 18 automatically feeds the document placed on the document tray, enabling scanning by the scanner unit 19 (see Figure 2).

[0022] The control unit 100 controls the overall operation of the image forming apparatus 1. The control unit 100 has a CPU (Central Processing Unit) and memory. The CPU may be a single unit or multiple units capable of parallel computation. The memory includes volatile memory (RAM) and non-volatile memory. The RAM provides the CPU with a working memory space and stores temporary data. The non-volatile memory stores programs, setting data, etc. The non-volatile memory may include part or all of an HDD (Hard Disk Drive) or flash memory. The flash memory may be an SSD (Solid State Drive).

[0023] The reading device 20 includes a transport path 230, image reading units 24 and 25, a colorimeter 26, and a reading control unit 200. The transport path 230 is connected to the transport path 130 of the device body 10, and the medium sent out from the transport path 130 is transported through it. Downstream of the transport path 230, the medium may be discharged directly. Alternatively, the medium may be sent to a medium discharge device (paper discharge device) or the like (not shown).

[0024] The image reading unit 24 reads the lower surface of the medium being transported along the transport path 230, that is, downstream of the image formation position. The image reading unit 25 reads the upper surface of the medium being transported along the transport path 230. The image reading unit 24 may be located upstream of the image reading unit 25 in the transport direction along the transport path 230. The colorimeter 26 measures the color of the image on the upper surface of the medium downstream of the image reading unit 25 in the transport direction.

[0025] The image reading units 24 and 25 may have imaging sensors such as CCD sensors or CMOS sensors. The imaging sensor may also be a line sensor. A line sensor can capture images across the entire width of the medium in a direction intersecting the medium's transport direction. This allows the image reading units 24 and 25 to read the entire surface of the transported medium. The reading results read by the image reading units 24 and 25 and the colorimeter 26 are transmitted to the reading control unit 200. The image reading units 24 and 25 may have a switchable white plate and a black plate at the background position of the medium within the imaging range.

[0026] The read control unit 200 includes a CPU and memory, and controls the operation of the read device 20. The CPU may be a single hardware processor, or it may be a plurality of hardware processors, each performing calculations independently or in parallel. The memory includes RAM and non-volatile memory. RAM provides the CPU with a working memory space and stores temporary data. Non-volatile memory stores program and setting data, etc. The non-volatile memory may include at least one of HDD and non-volatile memory.

[0027] Although the above describes a configuration in which two image reading units 24 and 25 read the upper and lower surfaces of the medium, a single image reading unit may also read the upper and lower surfaces of the medium. In this case, the reading device 20 may have a reversing transport path connected to the transport path 230, and by reversing the transport of the medium, the image reading unit may be able to sequentially read both sides of the medium.

[0028] In this embodiment, the CPU 151 performs image diagnosis based on the image read by the reading device 20. Therefore, the images read by the image reading units 24 and 25 are transferred from the reading control unit 200 to the CPU 151. In other embodiments, the reading control unit 200 may perform image diagnosis based on the read image. In this case, the reading control unit 200 is included in the image diagnosis device. The reading control unit 200 can output instructions to the CPU 151 to perform image adjustments, machine adjustments, etc., as needed.

[0029] The image forming apparatus 1 may have other components in addition to the apparatus body 10, the reader 20, and the paper feeder 40. Alternatively, as described above, the image forming apparatus 1 may have at least the apparatus body 10, and the reader 20 and the paper feeder 40 may be located externally.

[0030] Figure 2 shows the functional blocks of the image forming apparatus 1. The image forming apparatus 1 comprises a control block 15, an image forming operation unit 11, a transport unit 13, a scanner unit 19, an operation reception unit 141, a display unit 142, an image processing unit 16, a measurement unit 17, and a reading device 20. The apparatus body 10 may have all of the control block 15, image forming operation unit 11, transport unit 13, scanner unit 19, operation reception unit 141, display unit 142, image processing unit 16, and measurement unit 17. Alternatively, the reading device 20 may have some of the above components.

[0031] The image processing unit 16 performs processing on the acquired image data. The image processing unit 16 may be capable of converting image data acquired from an external device 50 via the communication control unit 161 or input from the scanner unit 19 into a format that can be used for image formation by the image forming operation unit 11. The image processing unit 16 may also be capable of processing the image data acquired from the scanner unit 19 as appropriate and outputting it to the external device 50 via the communication control unit 161. Image data before and after processing can be stored in the image memory 162. The image memory 162 may be DRAM. Reference image data for image diagnosis may be stored in the image memory 162. The communication control unit 161 has a network interface card (NIC) or the like that controls communication over a network such as a LAN (Local Area Network). The network is not limited to a LAN. Also, the network is not limited to wired or wireless.

[0032] The control block 15 includes a CPU 151 (control unit), RAM 152, and non-volatile memory 153. The control block 15 controls the overall operation of the image forming apparatus 1. For example, the CPU 151 of the control block 15 can perform media transport control, image forming operation control, image data processing control, and diagnosis of the formed image on the media. Image data processing control may include adjustment processing of the image for image forming obtained by the image processing unit 16. The CPU 151 is included in the image diagnostic apparatus of this embodiment. Each component of the control block 15 may be the same as each component of the control unit 100. The non-volatile memory 153 stores and holds a program 153a, setting information for each part, and setting parameters related to the image forming operation. The program 153a includes an image diagnostic control program. The setting information includes feature information 153b. The feature information 153b includes features and causes of streaks, spots, etc., of the detection target. Image data, job data acquired from external sources, setting parameters, diagnostic image parameters and diagnostic test images, and diagnostic image results may be stored in external memory outside the control block 15 as needed. The control block 15 can count the current date and time, elapsed time, etc., based on the clock signal related to its operation.

[0033] The image forming unit 11 forms a latent image on the photoreceptor 11a according to the light emission pattern of the laser diode 111 as described above, develops this image with toner, and then transfers the toner to the medium via the intermediate transfer belt 11b. The fixing unit 112 fixes the toner on the medium, thereby forming the image. The light emission pattern of the laser diode 111 is determined according to the image forming image data processed by the image processing unit 16 and stored in the image memory 162.

[0034] The conveying unit 13 includes a rotating roller and a rotating motor that rotates the rotating roller. The conveying unit 13 switches the connections of the conveying path 130, the reversing conveying path 131, the downstream conveying path 132, and the retraction conveying path 133 to convey the medium along an appropriate path and at an appropriate speed.

[0035] The scanner unit 19 captures an image of the reading surface of a document sent to the reading position by the automatic document feeder 18 and generates image data of the reading surface. The scanner unit 19 comprises an imaging unit 191 and an imaging control unit 192. The imaging unit 191 may be a line sensor such as a CCD sensor or a CMOS sensor. The imaging control unit 192 controls the imaging unit 191 to scan the reading surface, i.e., to move relative to the reading surface, thereby obtaining image data of the entire reading surface. The scanned image data is formatted in a predetermined format by the imaging control unit 192 and sent to the image processing unit 16 by serial communication or the like. The imaging control unit 192 has a CPU and memory. The CPU and memory of the imaging control unit 192 may be the same as the CPU and memory of the control unit 100 of the main unit 10, or they may be a separate hardware configuration from the CPU and memory of the control unit 100.

[0036] The operation reception unit 141 has an operation device such as a touch panel 141a and a group of operation keys, as described above, and outputs an operation signal corresponding to the received input operation. The operation device allows input of operation control conditions such as setting image forming conditions and operation commands for the image forming apparatus 1. The display unit 142 has a display screen 142a, as described above, and displays information according to the control of the control unit 100 or the CPU 151. The display screen 142a can display the setting details of the image forming conditions, the screen for receiving setting changes, the progress and status of the image forming operation, etc.

[0037] The measurement unit 17 measures environmental conditions at a predetermined location in the main body 10, for example, near the transport position of the medium in the image forming operation unit 11. The measurement unit 17 may include, for example, a thermometer 171 and a hygrometer 172. The thermometer 171 measures temperature, and the hygrometer 172 measures humidity. The measurement results are converted into digital values ​​with appropriate sampling accuracy and output to the CPU 151 of the control block 15. In addition to or instead of the above, the thermometer 171 and hygrometer 172 may also measure the temperature and humidity outside the main body 10, i.e., the ambient temperature and humidity, respectively.

[0038] The reading device 20 includes the image reading units 24 and 25, the colorimeter 26, and the reading control unit 200, as well as a transport unit 23. The reading control unit 200 can perform imaging control of the image reading units 24 and 25, generate a read image based on the imaging results, and output the generated read image data. Here, the reading device 20 is connected to the bus of the main unit 10, but it may also be connected via an appropriate connection terminal or communication control unit. The read image data may also be directly input to the image forming operation unit 11 or the control block 15. The transport unit 23 transports the medium sent from the transport path 130 of the main unit 10 along the transport path 230. The transport unit 23 has a rotating roller along the transport path 230 and a rotating motor that rotates the rotating roller. As described above, if the front and back sides of the medium can be reversed in the transport path 230, the transport unit 23 can switch the transport path depending on whether reversal is necessary. The setting of the transport speed and switching of the transport path may be performed based on control signals received from the control block 15 of the main unit 10 of the device.

[0039] Thus, the image forming apparatus 1 is capable of the following three processes with respect to images: (1) Processing image data acquired from an external source to form an image. (2) Copying process that processes image data of an image read by the scanner unit 19 to form an image. (3) Scanning process that outputs the image read by the scanner unit 19 as image data to an external source.

[0040] The parameter settings related to image formation may be obtained not only through input operations by the operation reception unit 141, but also through settings performed via a printer driver in an external device 50. The settings in the external device 50 can be obtained from the external device 50 via the communication control unit 161.

[0041] Next, we will explain image diagnosis. As described above, the CPU 151 can diagnose an image based on the image read from the medium by the reader 20. In image diagnosis, a simple image quality diagnosis can be performed using the read data of a simplified image diagnosis pattern (second pattern) formed on the medium (second medium). In this image quality diagnosis, for example, surface image quality such as gradation, maximum density, edge quality of patch areas, development memory, and granularity, as well as line image quality such as line width and color shift, may be diagnosed. The content of the diagnosis is not limited to these, and any items may be added. In addition, in image diagnosis, an image noise diagnosis can be performed using an image noise diagnosis pattern printed on the medium. Examples of image noise include streaks, banding, spots, and stains. Streaks and banding are noise that extends noticeably in a certain direction. Spots are noise that exists in isolation in a two-dimensional plane and include white spots, black spots, and color spots of other colors, as well as fireflies. White spots are white gaps, where toner is not applied to the area where it should be applied. Black spots are localized areas where toner has solidified. Circular, two-dimensional density variations resulting from transfer errors are called "fireflies." Here, spots and fireflies are collectively referred to as "spots." Dirt is noise that can appear even when no image formation is taking place. Dirt can be irregular in shape and spread out.

[0042] As a prerequisite for this image diagnosis, the image forming apparatus 1 allows for adjustment of the image formation position. If there is a misalignment in the diagnostic test image during image diagnosis, the accuracy of the diagnosis will decrease. Therefore, in one embodiment, before forming the diagnostic test image, adjustment of the image formation position is performed, in particular, front-to-back registration adjustment is performed to align the image formation position and orientation between the front and back sides.

[0043] Image diagnostics, including adjustment of the image formation position, may be performed periodically. For example, image diagnostics may be performed at predetermined intervals of 1 to 3 days, after each continuous image formation, or at the start of power supply each day if the power supply to the image forming apparatus 1 is cut off every night. In addition, image diagnostics may be performed as needed or at intervals in the image forming operation, such as when the media contained in the tray is changed, when the temperature and / or humidity conditions of the image forming apparatus 1 change significantly, or when the roller rotation speed or nip pressure of the transport section 13, 23 changes by more than a predetermined standard.

[0044] Figure 3 shows the procedure for diagnostic imaging. In the image diagnostic method of this embodiment, first, the alignment and front / back registration of each surface of the medium are performed (P1; adjustment step). A preliminary diagnosis of the image is performed (P2), and if a problem is detected in the preliminary diagnosis, a detailed diagnosis of the image is performed (P3). Steps P2 and P3 are included in the diagnostic step of this embodiment.

[0045] The CMYK colors are automatically adjusted in a batch (P4), and color verification is performed (P5). Finally, the image and colors are visually checked by the user (P6). If there are no problems, the image diagnosis is completed. Any conventionally known processing can be applied to the processes after position adjustment and image diagnosis (P4-P6), so a detailed explanation is omitted.

[0046] Figure 4 shows an example of a first test image I1 for image position adjustment. Figure 4(a) is the test image I11 formed on the surface of the medium, and Figure 4(b) is the test image I12 formed on the back surface of the medium. The position of the formed first test image (first pattern) is determined by the test images I11 and I12 for the front and back surfaces of the medium M, respectively. The pattern of test image I11 and the pattern of test image I12 may be identical. Test image I11 includes four lines L11 to L14 along the four sides of the medium M. Test image I12 includes four lines L21 to L24 along the four sides of the medium M. If the image is formed in the correct position, the coordinates of the intersection points C11 to C14 of the four lines L11 to L14 and the intersection points C21 to C24 of the four lines L21 to L24 will appear correctly. Furthermore, the pairs of lines L11 and L13, and the pairs of lines L21 and L23, are parallel to each other along the transport direction, and lines L12 and L14 are parallel and perpendicular to lines L11 and L13. The first test image I1 may be formed in a single color, for example, black.

[0047] Figures 5 to 7 show examples of read images of medium M when there is a misalignment in the formed image. As shown in Figure 5(a), if the position of the formed image (image formation position) is shifted by a rotation angle θ, the read image of the medium (first medium) on which the first test image I1 was formed will also be shifted by the same angle. As shown in Figure 5(b), if the image formation position is shifted in a direction perpendicular to the transport direction, the read image will also be shifted by a width dH in the width direction perpendicular to the transport direction. The magnitude of the positional shift may be determined by the difference between the coordinates of the intersection points C11~C14 and C21~C24 in these read images and the coordinates of the read image of the reference image that would be assumed if the image were formed normally. Alternatively, the magnitude of the positional shift and the magnification / reduction ratio may be determined based on the relative position from the corner position of the medium M in each image. Furthermore, in the positional shifts shown in Figures 5(a) and (b), the shifts are symmetrical between the front and back sides. Therefore, the average position of the image formation positions on the front and back sides is the correct image formation position. The amount of shift in the image formation position may be determined based on the amount of shift from this average position.

[0048] As shown in Figure 6(a), the formed image may be reduced or enlarged relative to the reference image. Here, the test image I11 is smaller than the original image size shown by the dotted line. As shown in Figure 6(b), the width of the formed image may change in the transport direction. Here, the test image I11 may be trapezoidal in shape. In this case, the enlargement / reduction ratio can be determined individually for each side L12 and L14. As shown in Figure 7, the trapezoidal shape may have different widths along the transport direction between side L11 and side L13. The above five patterns may also occur in combination.

[0049] Based on the reading results obtained in this way, the output image may be deformed and adjusted to offset the amount of misalignment. That is, if there is a rotational misalignment of rotation angle θ, the misalignment of the image formation position is reduced by outputting image data obtained by rotating the original image in the opposite direction by an angle of "-θ" as the data to be used for image formation. If the misalignment in the width direction is "dH", the misalignment of the image formation position is reduced by using image data obtained by shifting the image formation position by "-dH" from the original as the data to be used for image formation.

[0050] Figure 8 is a flowchart showing the control procedure for the position adjustment control process. The position adjustment control process corresponds to the adjustment step (P1) in this embodiment. The CPU 151 causes the image forming unit 11 to form test images I11 and I12 for position adjustment on both sides of the adjustment medium, respectively (S501). The CPU 151 causes the image reading units 24 and 25 to read the test images I11 and I12, respectively (S502). The CPU 151 calculates the amount of deviation from the reference position of the intersection points C11-C14 and C21-C24 (S503).

[0051] The CPU 151 determines the amount of rotational displacement of the formed images on both sides based on the above displacement amount (S504). The CPU 151 determines the amount of magnification displacement, i.e., size displacement, of the formed images on both sides based on the above displacement amount (S505). The CPU 151 determines the amount of shift, i.e., translation, of the images on both sides based on the above displacement amount (S506). The CPU 151 may determine the displacement amounts determined by steps S504 to S506 all at once, or it may determine them in a different order than described above.

[0052] Based on the above displacement amount, the CPU 151 determines the amount of image position adjustment to compensate for the displacement (S507). Then, the CPU 151 terminates the position adjustment control process.

[0053] Such adjustments are performed on specific media used for diagnostic imaging from among the media supplied from multiple supply trays 12a. In other words, the image formation position adjustment may be performed only on the specific media. After performing the image formation position adjustment, diagnostic imaging is performed on the media whose image formation position has been adjusted.

[0054] Figure 9 is a flowchart showing the procedure for image diagnostic control processing. This image diagnostic control processing includes diagnostic steps P2 and P3 in this embodiment. Image diagnosis is performed after positional adjustments have been made, as described above. The CPU 151 causes the image forming unit 11 to form a simplified diagnostic image (S1). The CPU 151 acquires a read image of the formed simplified diagnostic image from the reading device 20 and performs a basic image quality diagnosis (S2). The CPU 151 performs streak and spot detection processing using the simplified diagnostic image (S3).

[0055] CPU 151 determines whether streaks or spots have been detected and whether the number, size, and density of the detected streaks or spots are outside the predetermined acceptable range (S4). If no streaks or spots are detected, or if detected but within the acceptable range (S4; NO), CPU 151 proceeds to step S15.

[0056] In step S15, the CPU 151 adjusts the image quality according to the results of the basic image quality diagnosis (S15). Then, the CPU 151 proceeds to step S12.

[0057] If streaks and spots are detected and it is determined that the streaks or spots are outside the acceptable range (S4; YES), the CPU 151 proceeds to step S5. In step S5, the CPU 151 requests a decision from the user and obtains the decision (S5). For example, the CPU 151 displays an image of the detection results of the streaks and spots on the display unit 142 and requests a selection operation to determine whether or not to accept them. The CPU 151 obtains the user's decision in accordance with the input operation received by the operation reception unit 141. Alternatively, it is conceivable that the user is not near the image forming apparatus 1. In this case, for example, the images of the detection results of the streaks and spots may be compiled into a report format or registered on a predetermined access server, and a message requesting confirmation from the user may be sent via email or SNS. The user may be guided to remotely check the image of the detection results and then perform an input operation to select whether or not they are within the acceptable range from a predetermined website.

[0058] CPU 151 determines whether the acquired judgment result is "within the user's acceptable range" (S6). If it is determined to be within the user's acceptable range (S6; YES), CPU 151 proceeds to step S15. If it is determined to be outside the user's acceptable range (S6; NO), CPU 151 performs a detailed image diagnosis and obtains the diagnosis result (S7).

[0059] The CPU 151 determines, based on the detailed image diagnosis, whether streaks and / or spots are still detected and whether the streaks and / or spots are outside a predetermined acceptable range (S8). If it is determined that streaks and / or spots are no longer detected, or are detected but within an acceptable range (S8; YES), the CPU 151 proceeds to step S15.

[0060] If streaks and spots are detected and it is determined that the detected streaks and spots are outside the acceptable range (S8; NO), the CPU 151 requests a user's decision and obtains the user's decision (S9). The CPU 151 displays, for example, an image of the detection result of the streaks or spots on the display unit 142 and requests a selection operation to determine whether it is acceptable or not. The CPU 151 obtains the user's decision according to the input operation received by the operation reception unit 141. Alternatively, assuming that the user is not near the image forming apparatus 1, the images of the detection result of the streaks or spots may be compiled into a report format or registered on a predetermined access server. The CPU 151 may also send a message to the user requesting confirmation of the report or registration details via email or SNS. The user may be guided to remotely check the image of the detection result and then perform an input operation to select whether it is within the acceptable range from a predetermined website or the like.

[0061] Based on the user's judgment obtained, the CPU 151 determines whether the streaks and spots are within the user's acceptable range (S10). If it is determined that they are within the user's acceptable range (S10; YES), the CPU 151 proceeds to step S15. If it is determined that they are not within the user's acceptable range (S10; NO), the CPU 151 contacts a specialist staff member or service technician to address the cause of the streaks and spots. Alternatively, the CPU 151 sends a request for action to the user, asking them to make contact (S11). The CPU 151 may send a notification via the network to a staff dispatch center, or it may display a contact phone number on the display unit 142 and request the user to make a phone call. As described later, if the cause of the identified streaks and spots can be mechanically addressed, that is, if the user does not need to take action, the image forming apparatus 1 may perform an automatic action. For example, if the dirt on a specific part can be mechanically removed, the image forming apparatus 1 may perform cleaning of that part. Next, CPU151 proceeds to step S12.

[0062] In step S12, the CPU 151 creates a report on the diagnostic results (S12). The CPU 151 compiles the report with analysis parameters related to the diagnosis, such as basic image quality, their adjustment amounts, detected images of streaks and spots, analysis parameters, degree of recovery, and whether or not final contact was made with the staff. The report may be created according to a predetermined format. Then, the CPU 151 terminates the image diagnostic control process.

[0063] Figure 10 shows an example of a second test image for simplified diagnostic imaging. A second test image (second pattern), which is a simplified diagnostic image for diagnosing the state of the image forming operation unit 11, may be formed on a total of six surfaces, for example, on both sides of three media M (second media). A first chart I21, including various images for simplified image diagnosis such as patch images and density gradation images, is formed on the surface of the first media M. The objects of diagnosis may be, for example, development memory, granularity, maximum density, in-plane color difference, gradation, line width, color shift, patch edge quality, etc. Well-known techniques may be used for these diagnoses. A second chart I22 is formed on the back surface of the first media M to diagnose whether the above position adjustment has been performed accurately. The second chart I22 may have the same pattern as the first test image. The amount of positional shift can be determined in the same way as determined using the first test image.

[0064] In simplified image diagnostics, streaks and noise are also detected. These streaks include vertical streaks, i.e., FD streaks along the feed direction, and horizontal streaks, i.e., CD streaks along the cross direction. On the reverse side of the second medium M, a third chart I23 is formed, which includes halftone images of each YMCK color extending in the feed direction for detecting FD streaks. The third chart I23 can also be used to adjust the density balance.

[0065] On the third surface, a fourth chart I24 is formed, which includes halftone images of each YMCK color extending in the width direction for detecting CD streaks. The density of the halftone images in the third chart I23 and the fourth chart I24 may be uniform, for example, 50%. Alternatively, the density of the halftone images may differ for each CMYK color. In these image noise diagnostic patterns, the third chart I23 and the fourth chart I24 may also detect spot stains, spots, and diagonal streaks other than in the FD direction or CD direction.

[0066] White images I25 and I26 are formed on the surface of the second medium M and the back surface of the third medium M, respectively. That is, the medium M passes through the image forming unit 11 and the fixing unit 112 along the transport path 130, and an image forming operation is performed on the medium M, but toner is not applied to the medium M based on the image data. As a result, dirt adhering to each part along the transport path 130 during image formation can be detected.

[0067] Since FD streaks appear at specific locations in the width direction and do not move, the second chart I22 is formed across the entire width, allowing for complete detection. FD streaks are abnormalities that occur over a period of time, such as toner leaks. CD streaks are not continuous in the transport direction, but may appear periodically, or irregularly or as isolated occurrences.

[0068] Streaks and spots may be ranked into a predetermined range of levels according to their size, density ratio, etc. The tolerance range for which the CPU 151 mechanically determines whether or not a streak or spot is within an acceptable range may be automatically changed or manually changed in response to user input, depending on the rank accepted by the user. The ranks may be defined such that a higher value indicates a more pronounced streak or spot.

[0069] Figure 11 is a flowchart showing the control procedure for streak and spot detection processing performed in the image diagnostic control processing. The CPU 151 detects dirt using the second chart I22 of the second test image (S31). The CPU 151 performs FD streak detection processing using the third chart I23 (S32). The CPU 151 detects diagonal streaks using the third chart I23 (S33). The CPU 151 performs spot detection processing using the third chart I23 (S34). The CPU 151 sets whether or not density balance adjustment is necessary using the third chart I23 (S35).

[0070] CPU 151 performs CD streak detection processing using the fourth chart I24 (S36). CPU 151 performs spot detection processing using the fourth chart I24 (S37). CPU 151 performs stain detection using white images I25 and I26 (S38). Then, CPU 151 returns to image diagnostic control processing.

[0071] Figure 12 is a flowchart showing the control procedure for the FD streak detection process performed in the streak and spot detection process. The CPU 151 sequentially selects each CMYK color (S41). The CPU 151 detects FD streaks from the halftone images of the selected colors (S42). For example, the CPU 151 may detect density anomalies on multiple lines extending in the width direction and determine that an FD streak exists if the detection location of the density anomaly is the same on multiple lines.

[0072] The CPU 151 sets the rank of the detected FD streaks as described above, based on the thickness and density of the FD streaks (S43). The CPU 151 determines whether the rank is above the reference value, that is, whether it is more pronounced than the reference level corresponding to the reference value (S44). If it is determined that the rank is above the reference value (S44; YES), the CPU 151 sets the selected color as a candidate for detailed diagnosis (S45). The CPU 151 then proceeds to step S46. If it is determined that the rank is not above the reference value (S44; NO), the CPU 151 proceeds to step S46.

[0073] In step S46, the CPU 151 determines whether all colors have been selected (S47). If it is determined that not all colors have been selected, i.e., that there are unselected colors (S47; NO), the CPU 151 returns to step S41. If it is determined that all colors have been selected (S47; YES), the CPU 151 terminates the FD streak detection process and returns to the streak and spot detection process.

[0074] Figure 13 is a flowchart showing the control procedure for the spot detection process, which is called during the streak and spot detection process. The CPU 151 sequentially selects each CMYK color (S51). The CPU 151 detects spots from the halftone images of the selected colors (S52). The CPU 151 detects localized anomalies of the selected colors from the halftone images of the selected colors, which are two-dimensionally isolated points. The CPU 151 sets a rank for the detected spots (S53).

[0075] The CPU 151 determines whether the rank of each detected spot is above the standard value (S54). If it is determined that the rank of at least one of the detected spots is above the standard (S54; YES), the CPU 151 designates the selected color as a candidate for detailed diagnosis (S55). Then, the CPU 151 proceeds to step S56. If it is determined that the rank of all detected spots is below the standard (S54; NO), the CPU 151 proceeds to step S56. In step S56, the CPU 151 determines whether all colors have been selected (S56). If it is determined that there are unselected colors (S56; NO), the CPU 151 returns to step S51. If it is determined that all colors have been selected (S56; YES), the CPU 151 terminates the spot detection process, terminates the spot detection process, terminates the streak detection process, and returns to the streak detection process.

[0076] Figure 14 is a flowchart showing the control procedure for CD streak detection processing. The CD streak detection process is called within the streak and spot detection process. The CPU 151 sequentially selects each CMYK color (S61). The CPU 151 detects CD streaks from the halftone image of the selected colors (S62). The CPU 151 detects streaks that extend in the width direction. The CPU 151 sets the rank of the detected CD streaks (S63).

[0077] The CPU 151 determines whether the rank of each detected CD streak is above the standard value (S64). If it is determined that the rank of even one of the detected CD streaks is above the standard (S64; YES), the CPU 151 designates the selected color as a candidate for detailed diagnosis (S65). Then, the CPU 151 proceeds to step S66. If it is determined that the rank of all detected CD streaks is below the standard (S64; NO), the CPU 151 proceeds to step S66. In step S66, the CPU 151 determines whether all colors have been selected (S66). If it is determined that there are unselected colors (S66; NO), the CPU 151 returns to step S61. If it is determined that all colors have been selected (S66; YES), the CPU 151 terminates the spot detection process, terminates the spot and streak detection process, and returns to the streak and spot detection process.

[0078] Figure 15 is a flowchart showing the control procedure for detailed image diagnostic processing called in the image diagnostic control process. CPU 151 determines whether or not detailed analysis of FD lines is enabled (S71). If it is determined that detailed analysis of FD lines is enabled (S71; YES), CPU 151 executes the detailed analysis of FD lines (S72). The process then proceeds to step S73. If it is determined that detailed analysis of FD lines is disabled, the process proceeds to step S73.

[0079] CPU 151 determines whether or not spot detailed analysis is enabled (S73). If it is determined that spot detailed analysis is enabled (S73; YES), CPU 151 executes the spot detailed analysis process (S74). Then, the process proceeds to step S75. If it is determined that spot detailed analysis is disabled (S73; NO), CPU 151 proceeds to step S74.

[0080] CPU 151 determines whether CD streak detailed analysis is enabled or disabled (S75). If it is determined that CD streak detailed analysis is enabled (S75; YES), CPU 151 executes the CD streak detailed analysis process (S76). Then, CPU 151 terminates the detailed image diagnostic process and returns to the streak and spot detection process. If it is determined that detailed CD streak analysis is not enabled (S75; NO), the CPU 151 terminates the detailed image diagnostic processing and returns to streak and spot detection processing.

[0081] Figures 16 and 17 are flowcharts showing the control procedure for the FD streak detailed analysis process performed in the detailed image diagnostic processing. The CPU 151 causes the image forming unit 11 to output full-screen halftone images of each CMYK color onto the medium (S101). In other words, the image forming unit 11 outputs four full-screen halftone images. The CPU 151 detects FD streaks from each halftone image (S102).

[0082] CPU 151 determines whether or not there are FD lines in a common position across all colors in the width direction (S103). If it is determined that there are no FD lines in a common position (S103; NO), CPU 151 proceeds to step S114.

[0083] If it is determined that there is a component in the FD streak that is in a common position in the width direction for all colors (S103; YES), the CPU 151 sets the value of variable N to "0" (S104). The CPU 151 rotates the intermediate transfer belt 11b idle (S105). The CPU 151 outputs the halftone images of each CMYK color to the medium in full screen again (S106). The CPU 151 detects the FD streak from the halftone images of each color (S107).

[0084] CPU 151 determines whether or not there are FD lines in a common position across all colors in the width direction (S108). If it is determined that there are no FD lines in a common position across all colors (S108; NO), CPU 151 proceeds to step S112.

[0085] If it is determined that there is an FD streak in a common position across all colors (S108; YES), the CPU 151 adds 1 to the variable N (S109). The CPU 151 then determines whether the variable N is greater than the upper limit Nm (S110). If it is determined that the variable N is not greater than the upper limit Nm (S110; NO), the CPU 151 returns to step S105. That is, the upper limit Nm is the upper limit of the number of idle rotations of the intermediate transfer belt in step S105.

[0086] If it is determined that the variable N is greater than the upper limit Nm (S110; YES), the CPU 151 identifies the intermediate transfer belt 11b as the cause of the FD streaks (S111). In cases where the intermediate transfer belt 11b is the cause, it is often damaged. The CPU 151 then proceeds to step S112.

[0087] When the process moves to step S112, the CPU 151 sets a rank for each FD streak (S112). The CPU 151 determines whether or not there are any FD streaks with a rank above the standard value (S113). If it is determined that there are no streaks with a rank above the standard value (S113; NO), the CPU 151 terminates the FD streak detailed analysis process and returns the process to the detailed image diagnosis process.

[0088] If it is determined that there are FD streaks with a rank above the standard value (S113; YES), the CPU 151 sets the variable N to "0" (S114). The CPU 151 cleans the charging wires related to the charging of the photoreceptor (S115). If the image forming apparatus 1 does not have a mechanism for automatically cleaning the charging wires, the CPU 151 may perform a notification operation to the user requesting the cleaning of the charging wires via the display unit 142 or the like.

[0089] After cleaning the charged wire, the CPU 151 causes the image forming unit 11 to output full-screen halftone images of the colors in which FD streaks are detected onto the medium (S116). The CPU 151 detects FD streaks from the read images of the outputted halftone images (S117). The CPU 151 sets a rank for each read FD streak (S118). The CPU 151 determines whether or not there are any FD streaks with a rank above the standard value (S119). If it is determined that none of the FD streaks have a rank above the standard value (S119; NO), the cause of the abnormality is the charged wire. The CPU 151 performs an abnormal image diagnosis of the reading device 20 (S122). Then, the CPU 151 terminates the FD streak detailed analysis process and returns the process to the detailed image diagnosis process.

[0090] If it is determined that at least some of the FD lines are above the standard rank (S119: YES), the CPU 151 adds 1 to the variable N (S120). The CPU 151 then determines whether the variable N is greater than the upper limit Nm (S121). Note that the upper limit Nm may be different from the upper limit Nm in step S110. If it is determined that the variable N is not greater than the upper limit Nm (S121: NO), the CPU 151 returns to step S115.

[0091] If it is determined that the variable N is greater than the upper limit Nm (S121; YES), the process proceeds to Figure 17, where the CPU 151 sets the variable N to "0" (S122). The CPU 151 performs a PC / brush refresh (S123). The CPU 151 causes the image forming unit 11 to output a halftone image to the medium in full screen for the color whose cause of the FD streaks has not yet been identified (S124). The CPU 151 detects the FD streaks (S125).

[0092] The CPU 151 sets a rank for each detected FD streak (S126). The CPU 151 determines whether or not there are any FD streaks with a rank above the reference value (S127). If it is determined that there are no FD streaks with a rank above the reference value (S127; NO), the CPU 151 terminates the FD streak detailed analysis process and returns the process to the detailed image diagnosis process.

[0093] If it is determined that there is an FD streak with a rank equal to or greater than the standard value (S127; YES), the CPU 151 adds 1 to the variable N (S128). The CPU 151 determines whether the variable N is greater than the upper limit Nm (S129). The upper limit Nm may be different from either or both of the upper limit Nm in steps S110 and S121. If it is determined that the variable N is not greater than the upper limit Nm (S129; NO), the CPU 151 returns to step S123.

[0094] If it is determined that the variable N is greater than the upper limit Nm, the CPU 151 sets the photoreceptor 11a to a bias development mode that does not use charging or exposure (S130). The CPU 151 outputs an image by bias development output for colors for which the cause of FD streaks has not been determined by the image forming operation unit 11 (S131). The CPU 151 detects FD streaks from the output image (S132).

[0095] The CPU 151 determines whether or not FD streaks have been detected (S133). If it is determined that no FD streaks were detected (S134; NO), the cause of the FD streaks is set to exposure streaks or dirt on the dustproof glass (S134). The CPU 151 terminates the FD streak detailed analysis process and returns the process to the detailed image diagnostic process.

[0096] If it is determined that FD streaks have been detected (S133; YES), the CPU 151 outputs a solid image by normal development for the color for which the cause of the FD streaks has not been identified (S134). The CPU 151 detects FD streaks from the read image of the solid image (S135). The CPU 151 determines whether or not there were FD streaks (S136). If it is determined that there were FD streaks (S136; YES), the cause of the FD streaks is set to a developer jam (S137). The CPU 151 terminates the FD streak detailed analysis process and returns the process to the detailed image diagnosis process. If it is determined that there were no FD streaks (S136; NO), the cause is determined to be either dirt on the electrode grid, the drum unit, or the cleaning material for the electrode (S138). The CPU 151 terminates the FD streak detailed analysis process and returns the process to the detailed image diagnosis process.

[0097] Figure 18 is a flowchart showing the control procedure for the spot detail analysis process performed in detailed image diagnostic processing. The CPU 151 causes the image forming unit 11 to output halftone images of each color to the medium in full screen (S141). The CPU 151 then executes the spot type diagnostic process described later (S142).

[0098] The CPU 151 determines whether image adjustment is necessary as set in the spot type diagnostic process (S143). If image adjustment is set to be necessary (S143; YES), the CPU 151 performs image adjustment (S144). Image adjustment may include, for example, calibration and maximum density adjustment. These include adjustments in accordance with the output control performed in the spot type diagnostic process. The CPU 151 proceeds to step S145. If image adjustment is set to be unnecessary (S145; NO), the CPU 151 proceeds to step S145.

[0099] When the process moves to step S145, the CPU 151 determines whether the spot set in the spot type diagnosis process is at the OK level, that is, whether its rank is below the standard (S145). If it is determined to be within the OK range (S145; YES), the CPU 151 terminates the spot detailed analysis process and returns the process to the detailed image diagnosis process.

[0100] If it is determined that the spot is not at an OK level (S145; NO), the CPU 151 determines whether there were no periodic abnormalities detected in the spot type diagnostic process or whether they were within the OK range (S146). Possible causes of periodic spots include, for example, the drum unit, developing unit, intermediate transfer belt, intermediate transfer drive roller, primary transfer roller, fixing upper roller, fixing lower roller, etc. The appearance period of the spot differs depending on these causes. Therefore, the cause can be identified by identifying the appearance period. These correspondences are stored in feature information 153b, and the CPU 151 may refer to the feature information 153b as needed. If it is determined that the periodic abnormality is not at an OK level (S146; NO), the CPU 151 takes action corresponding to the cause according to the above period (S147). If the CPU 151 cannot directly control the action, the CPU 151 may display the action on the display unit 142 and request action from the user. The CPU 151 proceeds to step S148. If the periodic anomaly is determined to be within the OK range (S146; YES), the CPU 151 proceeds to step S148.

[0101] In step S148, the CPU 151 determines whether the non-periodic fireflies are at an OK level (S148). If it is determined that the non-periodic fireflies are not at an OK level (S148; NO), the CPU 151 performs or notifies the cleaning of the relevant component elements related to the image formation operation (S149). The CPU 151 then proceeds to step S150. If the non-periodic fireflies are at an OK level or no non-periodic fireflies are detected (S148; YES), the CPU 151 then proceeds to step S150.

[0102] In step S150, the CPU 151 determines whether the non-periodic white spots are at an OK level (S150). If it is determined that the non-periodic white spots are not at an OK level (S150; NO), the CPU 151 performs a notification operation prompting a change in the developer (S151). The notification operation may also be a display operation by the display unit 142. The CPU 151 proceeds to step S152. If the non-periodic white spots are at an OK level or no white spots are detected (S150; YES), the CPU 151 proceeds to step S152.

[0103] In step S152, the CPU 151 determines whether the aperiodic black spots are at an OK level (S152). If it is determined that the aperiodic black spots are not at an OK level (S152; NO), the CPU 151 performs or notifies the relevant component elements related to the image formation operation (S152). The CPU 151 terminates the spot detailed analysis process and returns the process to the detailed image diagnosis process. If the aperiodic black spots are at an OK level or no aperiodic black spots are detected (S152; YES), the CPU 151 terminates the spot detailed analysis process and returns the process to the detailed image diagnosis process.

[0104] Examples of these non-periodic spots include those caused by the developer or double-sided unit. While such non-periodic spots can be dealt with to the extent that they can be distinguished by the type of firefly or spot, non-periodic spots with multiple causes are difficult to identify and address.

[0105] Figures 19-20 are flowcharts showing the control procedure for the spot type diagnosis process performed in the spot detailed analysis process. The CPU 151 detects spots using the halftone image formed in step S141 (S201). The CPU 151 sets the detail rank for each spot (S202). The CPU 151 determines whether the detail rank is within the reference range (S203). If it is determined that the detail rank is within the reference range (S203; NO), the CPU 151 sets the spot level to OK (S204). Then, the CPU 151 terminates the spot type diagnosis process and returns the process to the detailed image diagnosis process.

[0106] In the determination process of step S203, if it is determined that the detailed rank of the spot is not within the standard range (S203; NO), the CPU 151 sets the spot level to NG (S205). The CPU 151 identifies the periodicity and type of each spot (S205). As described above, the periodicity can be determined by associating the appearance location of the spot with its position in the transport direction. The cause of the spot's occurrence is identified according to the periodicity.

[0107] CPU 151 determines whether or not there are periodic spots (S207). If it is determined that there are no periodic spots (S207; NO), CPU 151 sets periodic anomaly OK (S208). If it is determined that there are periodic spots (S207; YES), CPU 151 sets periodic anomaly NG (S209). After steps S208 and S209, CPU 151 proceeds to step S210.

[0108] In step S210, the CPU 151 determines whether or not there is aperiodic contamination (S210). If it is determined that there is no aperiodic contamination (S210; NO), the CPU 151 sets aperiodic contamination OK (S211). If it is determined that there is aperiodic contamination (S210; YES), the CPU 151 sets aperiodic contamination NG (S212). After steps S211 and S212, the CPU 151 proceeds to step S213.

[0109] In step S213, the CPU 151 determines whether or not there are non-periodic fireflies (S213). If it is determined that there are no non-periodic fireflies (S213; NO), the CPU 151 sets non-periodic fireflies OK (S220). Then, the CPU 151 proceeds to step S221. If it is determined that there are non-periodic fireflies (S213; YES), the CPU 151 determines whether or not the adjustment value of the primary transfer output is at the limit value (S214). If it is determined that it is at the limit value (S214; YES), the CPU 151 proceeds to step S218. If it is determined that it is not at the limit value (S214; NO), the CPU 151 executes the primary transfer output adjustment process (S215). The CPU 151 sets the element cleaning to none (S216).

[0110] CPU 151 determines whether the level of fireflies obtained in the primary transfer output adjustment process is within the reference range (S217). If it is determined that the level of fireflies is within the reference range (S217; YES), CPU 151 sets the image to require adjustment (S219). Then, CPU 151 proceeds to step S220. If it is determined that the level of fireflies is not within the reference range (S217; NO), CPU 151 sets the non-periodic firefly NG (S218). Then, CPU 151 proceeds to step S221.

[0111] In step S221, the CPU 151 determines whether or not there are aperiodic white spot abnormalities (S221). If it is determined that there are no aperiodic white spots (S221; NO), the CPU 151 sets the white spot level to OK (S230). The CPU 151 then proceeds to step S231.

[0112] If aperiodic white spots are detected (S221; YES), the CPU 151 determines whether secondary transfer output adjustment has already been performed (S222). If secondary transfer output adjustment has already been performed (S222; YES), the CPU 151 performs a development AC bias output adjustment process, which is an adjustment of the AC component of the development bias (S226).

[0113] If it is determined that secondary transfer output adjustment has not been performed (S222; NO), the CPU 151 executes the secondary transfer output adjustment process (S223). The CPU 151 sets that the secondary transfer output adjustment has been completed (S224). The CPU 151 determines whether the white spot rank set in the secondary transfer output adjustment process is within the reference range (S225). If it is determined that the white spot rank is within the reference range (S225; YES), the CPU 151 sets that image adjustment is required (S228). Then, the CPU 151 proceeds to step S230.

[0114] If it is determined that the white spot rank is not within the standard range (S225; NO), the CPU 151 proceeds to step S226. After the processing in step S226, the CPU 151 determines whether or not the white spot rank is within the standard range (S227). If it is determined that the white spot rank is within the standard range (S227; YES), the CPU 151 proceeds to step S228. If it is determined that the white spot rank is not within the standard range (S227; NO), the CPU 151 sets the white spot level to NG (S229). After that, the CPU 151 proceeds to step S231.

[0115] When the process moves to step S231, the CPU 151 determines whether or not aperiodic black spots have been detected (S231). If it is determined that a black spot anomaly has been detected (S231; YES), the CPU 151 sets the black spot level to NG (S233). If it is determined that no black spot anomaly has been detected (S231; NO), the CPU 151 sets the black spot level to OK (S232). The CPU 151 then terminates the spot type diagnosis process and returns the process to the spot detailed analysis process.

[0116] Figure 21 is a flowchart showing the control procedure for the primary transfer output adjustment process performed in the spot type diagnostic process. The CPU 151 adjusts the primary transfer output (S301). The adjustment may target, for example, the voltage of the charging roller or the toner supply amount. The CPU 151 causes the image forming unit 11 to output halftone images of the toner colors in which non-periodic fireflies were detected, across the entire screen of the medium (S302).

[0117] The CPU 151 detects non-periodic fireflies from the output halftone image (S303). The CPU 151 sets a rank for each detected firefly. The representative value of the rank may be the maximum value among the determined ranks. The CPU 151 determines whether the rank of the fireflies is within the reference range (S305). If it is determined that the rank of the fireflies is within the reference range (S305; YES), the CPU 151 terminates the primary transfer output adjustment process and returns to the spot type diagnosis process.

[0118] If it is determined that the firefly rank is not within the standard range (S305; NO), the CPU 151 increments the count value representing the number of primary transfer output adjustments by 1 (S306). The CPU 151 determines whether the count value is within the predetermined upper limit (S307). If it is determined that the count value is not within the upper limit (S307; NO), the CPU 151 returns to step S301. If it is determined that the count value is within the upper limit (S307; YES), the CPU 151 terminates the primary transfer output adjustment process and returns the process to the spot type diagnosis process.

[0119] Figure 22 is a flowchart showing the control procedure for the secondary transcription output adjustment process performed in the spot type diagnosis process. The CPU 151 adjusts the secondary transcription output (S311). The CPU 151 causes the image forming unit 11 to output full-screen double-sided halftone images of the colors in which aperiodic white spots are detected onto the medium (S312). The CPU 151 detects aperiodic white spots from the output halftone images (S313). The CPU 151 sets the rank of each detected white spot (S314).

[0120] CPU151 determines whether the rank of the white spots is within the reference range (S315). If it is determined that the rank is within the reference range (S315; YES), CPU151 terminates the secondary transcription output adjustment process and returns the process to the spot type diagnosis process. If it is determined that the rank is not within the reference range (S315; NO), CPU151 increments the count value representing the number of adjustments for the secondary transcription output by 1 (S316). CPU151 determines whether the count is equal to a predetermined upper limit (S317). The upper limit may be different from the upper limit related to the number of primary transcription output adjustment processes. If the count is not equal to the upper limit (S317; NO), CPU151 returns to step S311. If it is determined that the count is equal to the upper limit (S317; YES), CPU151 terminates the secondary transcription output adjustment process and returns the process to the spot type diagnosis process.

[0121] Figure 23 is a flowchart showing the control procedure for the development AC bias output adjustment process performed during the spot type diagnostic process. The CPU 151 adjusts the output of the development AC bias (S321). For colors in which aperiodic white spots are detected, the CPU 151 causes the image forming unit 11 to output a halftone image on the medium in full screen (S322).

[0122] The CPU 151 detects non-periodic white spots from the output halftone image (S323). The CPU 151 sets a rank for the detected white spots (S324). The CPU 151 determines whether the rank of the white spots is within the reference range (S325). If it is determined that the rank of the white spots is within the reference range (S325; YES), the CPU 151 terminates the development AC bias output adjustment process and returns the process to the spot type diagnosis process.

[0123] If it is determined that the rank of the white spots is not within the standard range (S325; NO), the CPU 151 increases the count representing the number of adjustments for the development AC bias output by 1 (S326). The CPU 151 determines whether the count is equal to a predetermined upper limit (S327). This upper limit may be different from the upper limit of the primary transfer output adjustment process or the upper limit of the secondary transfer output adjustment process. If it is determined that the count is not equal to the upper limit (S327; NO), the CPU 151 returns to step S321. If it is determined that the count is equal to the upper limit (S327; YES), the CPU 151 terminates the development AC bias output adjustment process and returns the process to the spot type diagnosis process.

[0124] Figure 24 is a flowchart showing the control procedure for the CD streak detailed analysis process performed in the detailed image diagnostic processing. The CPU 151 outputs full-screen halftone images of each color onto the medium using the image forming unit 11 (S161). The CPU 151 detects CD streaks from each halftone image (S162). The CPU 151 detects the periodicity of the transport direction of the detected CD streaks (S163). That is, the CPU 151 detects whether or not the CD streaks are periodic, at what period the CD streaks appear if they are periodic, and the variation (unevenness) of the CD streaks at each detected period. The periodicity is not limited to one type, and periodic and non-periodic CD streaks may coexist. Also, the period of the CD streaks may vary to some extent.

[0125] Possible locations that can cause periodic CD streaks include, for example, the drum unit, developing unit, intermediate transfer belt, transfer roller, fixing belt, and fixing roller. The period in which CD streaks occur differs depending on the location. Therefore, the location of the cause can be identified from the period of the detected CD streaks. These correspondences are stored in advance as characteristic information 153b in the non-volatile memory 153 of the control block 15 and may be referenced by the CPU 151 as needed. The period of the CD streaks can be easily determined using, for example, the Fourier transform. On the other hand, it is difficult to identify the location of non-periodic CD streaks from the image diagnostic information. Therefore, in this case, it is sufficient for the output to indicate that CD streaks of an unknown cause have occurred.

[0126] The CPU 151 sets detailed ranks for the detected CD streaks, separating them into non-periodic and periodic streaks (S164). The CPU 151 determines whether the detailed ranks for all periods are within the reference range (S165). If it is determined that all detailed ranks are within the reference range (S165; YES), the CPU 151 terminates the CD streak detailed analysis process and returns the process to the detailed image diagnosis process.

[0127] If it is determined that all detail ranks are not within the reference range, i.e., that there are detail ranks outside the reference range (S165; NO), the CPU 151 identifies the cause corresponding to the periodicity of the detail ranks outside the reference range. The CPU 151 then takes action to address the identified cause, or performs a notification operation using the display unit 142 or the like to prompt the user to take action (S166).

[0128] The CPU 151 determines whether the non-periodic streaks are at an OK level (S167). If the non-periodic streaks are not OK (S167; NO), the CPU 151 determines that the non-periodic streaks have an unspecified cause, terminates the CD streak detailed analysis process, and returns the process to the detailed image diagnosis process.

[0129] If it is determined that the non-periodic streaks are OK (S167; YES), the CPU 151 terminates the CD streak detailed analysis process and returns to the detailed image diagnosis process.

[0130] As described above, in one embodiment, image adjustment including the detection of streaks and spots is performed after the front-to-back adjustment, but the execution of the front-to-back adjustment can be canceled by user settings. Furthermore, the supply tray 12a on which the front-to-back adjustment is performed may be selectable.

[0131] Figure 25 shows an example of the initial settings screen for image adjustment displayed on the display unit 142, etc. These initial setup screens may be output externally and remotely displayed on an external device's display or similar.

[0132] As shown in Figure 25(a), the initial setup screen may allow the user to select whether or not to actually adjust each item that may be subject to adjustment. Some adjustments may be automatically determined based on the results of the image diagnosis. Such adjustments may include the option to perform front-to-back adjustment. For example, if image diagnosis is required multiple times a day, it is conceivable that the results of the previous front-to-back adjustment may be considered valid, and the re-execution of the front-to-back adjustment may be omitted. In other words, the frequency at which front-to-back adjustment is required may differ from the frequency at which image diagnosis or image adjustment is required. Therefore, this initial setup display screen may include not only a simple selection of whether or not to perform the adjustment, but also settings such as, for example, the option to avoid re-execution within a specified period.

[0133] Figure 26 illustrates the procedure for image diagnosis in another embodiment. In this embodiment, steps P11 and P12 are added. Steps P1 to P10 are the same as those described above, so a detailed explanation is omitted.

[0134] Information regarding the status of the image forming unit is acquired as needed or at appropriate intervals (P11; acquisition step). If this acquired information satisfies the conditions for subsequent steps, the process proceeds to step P12. The status information may include, for example, the number of images formed (printed) since the last diagnosis, the continuous startup time since the image forming apparatus 1 was started, i.e., power supply started, and the continuous operating time during which images are continuously formed in the image forming apparatus 1, as illustrated above. Conversely, the continuous elapsed time since the last image forming operation (print job) was executed, i.e., the waiting time, may also be acquired information. Furthermore, the status information may include temperature and humidity measured by the measurement unit 17, or the amount of change in temperature and humidity. In addition, interruptions to the image forming operation, such as replenishing media in a specific supply tray 12a, may also be conditions for performing image diagnosis. Replenishing media may be identified, for example, by attaching a weight sensor to the supply tray 12a and detecting an increase in weight, or it may be determined when the media remaining amount is no longer zero. Alternatively, the replenishment of media may be determined indirectly by the simpler actions of pulling out and retracting the supply tray 12a, or even by opening and closing the door to open the supply tray 12a.

[0135] In step P12, a process (P12; discrimination step) is performed to select whether or not position adjustment is necessary. If position adjustment is not necessary, the position adjustment and front / back registration adjustment steps (P1) are omitted, and the simplified image diagnosis (P2) begins.

[0136] As described above, the omission of position adjustment may only be permitted if the specified conditions are met. Alternatively, the decision to perform position adjustment may simply be made according to the user's request. The user's request may be received by the operation reception unit 141. On the other hand, even if the user requests the omission of position adjustment, if the necessary position adjustment has not been performed, the omission of position adjustment may not be permitted. In other words, the execution of the processes from the simplified image diagnosis (P2) onward may be permitted only for the supply tray 12a that has undergone position adjustment. In this case, the CPU 151 may notify the user via the display unit 142 to perform the necessary position adjustment. If the CPU 151 receives repeated requests to omit position adjustment despite the notification, it may omit process P1 and permit the execution of processes P2 onward.

[0137] As shown in Figure 25(b), the user may select and set a supply tray 12a (first supply tray) that contains the medium to be adjusted, and a supply tray 12a (second supply tray) that contains the medium to be used for image diagnosis and image quality adjustment. The first and second supply trays may be selected from some or all of a plurality of supply trays 12a. In this case, the second supply tray may only be selectable from among the first supply trays. Furthermore, the second supply tray may be selectable from one of the first supply trays. That is, the second medium may be supplied from one of the first supply trays. Based on the input operation to the touch panel 141a and the contents of the initial setting screen displayed on the display screen 142a at the time of the input operation, the CPU 151 accepts the selection setting.

[0138] Furthermore, as described above, position adjustment and image diagnosis may be automatically initiated at specific timings. These specific timings may be selected by the user. These specific timings may be, for example, when the image forming apparatus 1 is started up, or at a specified time. Even at a specified time, there may be a predetermined interval of several days, for example, three days, since the most recent position adjustment or image diagnosis was performed. Alternatively, the system may be configured to prevent position adjustment or image diagnosis from being performed at specific timings. In this case, the user can command the execution of position adjustment or image diagnosis at the required timing through input operations. For example, when outputting a job, the operation reception unit 141 may allow setting whether or not to perform image diagnosis. In addition, the standard time for continuous startup time (third standard time), the standard time for continuous operation time (second standard time), and the standard time for elapsed time (first standard time) may be determined by the user as described above. Similarly, a predetermined number that serves as the standard for the number of images formed, standard values ​​for temperature and humidity, and standard values ​​for variations in the operation of the transport units 13 and 23 and offset may also be predetermined by the user as specified conditions. Users may set reference time, predetermined number, and reference value, either arbitrarily or within a predetermined range of values.

[0139] Figure 27 shows an example of a screen during the execution of an image diagnostic test. During the execution of the image diagnosis, the CPU 151 may display the estimated time required for the image diagnosis on the display screen 142a. This eliminates the need for the user to monitor the image forming apparatus 1 until the image diagnosis is complete, while also easily reducing the waiting time during which the user does not need to check the results after the image diagnosis is finished.

[0140] Figure 28 shows an example of a results display screen that appears after performing an image diagnostic. As shown in Figure 28(a), after the completion of the simplified image diagnostic processing, the display screen of the display unit 142 may show the results of the simplified image diagnostic processing. The output content of the displayed results of the simplified image diagnostic processing may include the detection results of the positional displacement state of the image formation position based on the first test image or the second chart.

[0141] The screen displaying the preliminary image diagnosis results may also show a button to request a detailed image diagnosis. In other words, the detailed image diagnosis may not be performed automatically, but only upon user request. Alternatively, the preliminary and detailed image diagnoses may be performed consecutively, with the preliminary image diagnosis results displayed first after the detailed diagnosis. In this case, the items for which the detailed diagnosis was performed may be selectable from the preliminary image diagnosis results for display of the detailed image diagnosis results. Alternatively, the detailed diagnosis results may be displayed in a list, similar to the preliminary image diagnosis results, with the results for selected items displayed in more detail.

[0142] In Figure 28(b), the detailed diagnostic results are displayed as a list on the left side of the screen, and the detailed results of the selected CD periodic irregularities are shown on the right side of the screen.

[0143] As described above, the image diagnostic method of this embodiment is a method executed by an image diagnostic device based on an image formed by an image forming device 1 comprising an image forming operation unit 11 and a reading device 20. The reading device 20 is located along the transport paths 130 and 230 of the medium and reads the medium downstream of the transport paths 130 and 230 from the image formation position by the image forming operation unit 11. In this image diagnostic method, the image diagnostic device performs an adjustment step and a diagnostic step performed after the adjustment step. The adjustment step includes the following processes: (1) The image forming operation unit 11 forms a first test image I1 for adjusting the image formation position. (2) The reading device 20 reads the first medium on which the first test image I1 has been formed. (3) The image formation position is adjusted based on the reading result of the first medium. The diagnostic step includes the following processes: (1) The image forming operation unit 11 forms a second test image for diagnosing the state of the image forming operation unit 11. (2) The reading device 20 reads the second medium on which the second test image has been formed. (3) Based on the reading result of the second medium, a diagnostic result of the state of the image forming operation unit 11 is obtained. With this image diagnostic method, the position adjustment of the image formation position is performed before the image formation for image diagnostics, so that the test image for image diagnostics is formed with greater accuracy. Therefore, the accuracy of image diagnostics is improved compared to conventional methods. As a result, the adjustment is made more efficient, and the repetition of diagnosis and adjustment due to not obtaining a proper image is reduced.

[0144] Furthermore, the adjustment process may include front-to-back registration adjustment of the media. This ensures that not only the image formation positions on each side, but also the image formation positions on the front and back sides are more appropriately aligned.

[0145] Furthermore, this image diagnostic method may also include an acquisition step in which the image diagnostic device acquires information related to the state of the image formation position, and a determination step in which, based on the acquired state, determines whether or not to perform an adjustment step before the diagnostic step. Although position adjustment and image diagnosis are basically performed together, the image diagnostic device may be configured to omit position adjustment. For example, if image diagnosis is performed frequently, position adjustment does not necessarily have to be performed every time. This can reduce the time required for image adjustment and the amount of media and toner used for position adjustment.

[0146] The image forming apparatus 1 may also be equipped with a supply tray 12a for holding media. In the acquisition step, information regarding the replenishment of media in the supply tray 12a may be acquired as a status. The adjustment step may be performed when media has been replenished in the supply tray 12a after the most recent adjustment step, and / or when media has been replenished in the supply tray 12a after the most recent image forming operation. This reduces the need for unnecessary and continuous position adjustments when there is no change in the image forming position.

[0147] Furthermore, the acquisition step may acquire information regarding the elapsed time since the previous image formation operation was performed. In the discrimination step, it may be stipulated that the adjustment step be executed if the elapsed time is equal to or greater than the first reference time. Changes in the image formation position depend to some extent on the passage of time. Therefore, by performing the adjustment step at appropriate intervals of a reference time or longer, the accuracy of image diagnosis can be efficiently maintained.

[0148] Furthermore, during the acquisition process, information regarding at least one of the temperature and humidity related to the image forming apparatus 1 may be acquired as a state. Temperature and humidity affect the state of the media and the fixing state of the toner. Therefore, by including these temperature and humidity parameters in the image formation process, image quality can be stabilized. Moreover, by properly confirming and adjusting the image formation position at this time, the effects of media expansion and contraction and distortion can be reduced, making it possible to perform image diagnosis with greater accuracy.

[0149] Furthermore, the image forming apparatus 1 may be equipped with one or more supply trays 12a for accommodating media. The first media may be supplied from the first supply tray among the supply trays 12a. That is, by designating a first supply tray for supplying media for alignment and image diagnosis, image diagnosis can be performed with the same quality. On the other hand, if there are multiple supply trays 12a, it is possible to quickly transition to normal image forming after image diagnosis. Therefore, this image diagnosis method makes it possible to adjust the image quality more efficiently and output high-quality images to the desired media.

[0150] Furthermore, the image forming apparatus 1 may have multiple supply trays 12a, or multiple first supply trays. Adjustment processes may be performed on each first medium supplied from the first supply tray. By having multiple supply trays 12a, the image forming apparatus 1 can quickly switch and supply media according to the application and form images. Also, by having multiple supply trays 12a, the image forming apparatus 1 can easily switch between forming images of multiple sizes. Having multiple first supply trays allows for flexible allocation of supply trays 12a. In addition, when media usable for diagnostic imaging are contained in multiple supply trays 12a, multiple first supply trays can be easily switched and used according to the media storage status.

[0151] Furthermore, this image diagnostic method may also accept a setting to select a first supply tray. That is, the user can place the medium for position adjustment and image diagnostics in the desired supply tray, so the user can assign the supply tray as they see fit.

[0152] Furthermore, the second medium may be supplied from part or all of the first supply tray. That is, image quality diagnosis and adjustment may be performed using the same medium as the position adjustment of the formed image. Since the adjustment is performed using a medium in the same paper state, more stable and accurate adjustment is possible. In this case, different media from the first supply tray may be used depending on the content of the image diagnosis and image quality adjustment. This can further streamline the adjustment process.

[0153] Furthermore, the second medium may be supplied from one of the first supply trays. That is, image diagnosis and image quality adjustment may be performed using any one of the mediums on which the image position adjustment has been performed. As long as the position adjustment has been performed, sufficiently accurate adjustment is possible with a medium supplied from one of the first supply trays, so adjustment can be performed with the minimum necessary medium.

[0154] Furthermore, the diagnostic imaging device may permit the execution of the diagnostic process on a supply tray 12a on which an adjustment process has been performed. In other words, the execution of the diagnostic process using media supplied from a supply tray 12a on which an adjustment process has not been performed may be prohibited. This prevents inaccurate adjustments from being performed by mistake, thereby reducing the decrease in work efficiency and leading to a reduction in wasted media.

[0155] Furthermore, the image diagnostic method of this embodiment may also accept a setting to select a first supply tray on which to perform the diagnostic process. Therefore, the user can select the optimal medium to diagnose and adjust the image quality. This allows each supply tray 12a to be used flexibly to accommodate the necessary medium.

[0156] Furthermore, the diagnostic process may output diagnostic results. The output of the diagnostic results may include diagnostic results regarding the image formation location. By showing the diagnostic results to the user, the user can easily understand the problems that have occurred. In addition, by including information on positional displacement of the image formation location in the problems, the user can easily recognize the occurrence of positional displacement as a problem, similar to the results of other image diagnostics.

[0157] Furthermore, if the diagnostic process is performed after the adjustment process, the second pattern may include a pattern for identifying the image formation position on the second medium. The diagnostic process may also diagnose whether the image formation position has been correctly adjusted. While the misalignment is basically corrected based on the first pattern, confirming that the misalignment has been correctly adjusted in conjunction with image diagnosis allows for efficient and highly accurate adjustment.

[0158] Furthermore, in the image diagnostic method of this embodiment, the process including the adjustment step and the diagnostic step may be performed under at least one of the following conditions: (1) When the image forming operation unit 11 is started. (2) When it is the specified time. (3) When the image forming operation unit 11 has formed images on a predetermined number of media or more. (4) When the image forming operation unit 11 has been operating for a second reference time or longer. (5) When power has been supplied to the image forming operation unit 11 for a third reference time or longer. (6) When a predetermined change is detected in the transport unit that transports the media. In this way, by appropriately performing image diagnostics at appropriate intervals and under conditions where positional shifts or image quality deviations may occur, the degradation of image accuracy can be efficiently reduced.

[0159] Furthermore, in the image diagnostic method of this embodiment, it may be possible to accept input for whether or not to perform the adjustment step before executing the diagnostic step. As described above, it is basically preferable that the image formation position is adjusted before the diagnostic step. However, if it is not necessary, the adjustment step may be omitted depending on the user's settings. This can reduce unnecessary inspection time, media and toner consumption.

[0160] Furthermore, the estimated time required for execution may be output at least during the execution of either the adjustment process or the diagnostic process. Since these adjustments and diagnostics take some time, it is a waste of time for users to constantly monitor the image forming apparatus. On the other hand, if a user who has left their seat to perform adjustments or diagnostics does not return even after the results are obtained, the image forming operation cannot be resumed, resulting in a decrease in work efficiency. Therefore, by outputting the estimated time required in advance at the start of the process, it is possible to use the time effectively by performing other tasks or taking breaks only when the appropriate amount of time is needed.

[0161] Furthermore, the image diagnostic apparatus of this embodiment includes a CPU 151 capable of executing the above-described image diagnostic method. This image diagnostic apparatus allows for more accurate image adjustment and enables the image forming apparatus 1 to efficiently form a suitable image.

[0162] Furthermore, the image forming apparatus 1 of this embodiment includes the above-described image diagnostic apparatus. As a result, the image forming apparatus 1 can output images that have been efficiently and accurately adjusted.

[0163] Furthermore, program 153a of this embodiment causes the image diagnostic device to execute the image diagnostic method described above. Therefore, it is possible to easily, efficiently, and accurately adjust images.

[0164] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the control unit that operates as an image diagnostic device does not have to be the CPU 151, control unit 100, or reading control unit 200 within the image forming apparatus 1. The control unit of the external device 50 may acquire reading data and measurement data from the image forming apparatus 1 and perform image diagnosis. Alternatively, the CPU 151 or other unit within the image forming apparatus 1, acting as an image diagnostic device, may delegate some processing to an external CPU or dedicated processor, acquire the results, and then perform the remaining processing.

[0165] Furthermore, the image forming apparatus may be capable of forming images on only one side. In this case, alignment and image diagnosis on the back side are unnecessary. Also, even if image forming is possible on both sides, if an image is formed on only one side, image diagnosis on the back side may be omitted.

[0166] Furthermore, the adjustment of the image formation positions on the front and back surfaces can be performed independently, and direct alignment of the front and back surfaces is not required.

[0167] Furthermore, the pattern (design) of the first test image I1 does not have to be four straight lines of a length close to the width and length of the medium. For example, the first test image I1 may be a local cross, i.e., a registration mark, or any other shape that can identify the amount of displacement of the image formation position. Also, the content and order of formation of the second test image I2 are not limited to the above and may be arbitrarily determined to the extent that the necessary information can be obtained.

[0168] Furthermore, while the above example described display mechanisms such as screen 142a as the destination for image diagnostic settings and diagnostic results output, this is not limited to this. Audio output may also be used. Alternatively, diagnostic results may be output as data in a document format such as PDF.

[0169] Furthermore, the media supply tray 12a may be a single unit. In this case, the single supply tray 12a is fixed to the object of position adjustment and image diagnosis.

[0170] The scanning of the original document in the scanner unit 19 may be performed by placing the original document on a platen glass (not shown). Alternatively, the scanner unit 19 may scan a printed document output from the image forming apparatus 1, either by being transported or manually set. In other words, the scanner unit 19 may function as a reading unit in place of or in addition to the reading device 20.

[0171] Furthermore, the reading device 20 is not mechanically connected in-line to the main body 10 and may be configured separately from the image forming apparatus 1. The reading device 20 may be configured to read a medium set by a user or the like. The reading results may also be sent to the CPU 151 or control unit 100 via a communication line or network. Alternatively, the reading results may be sent from the reading device 20 to the CPU 151 or control unit 100 via a removable portable recording medium such as a memory stick. In addition, although the image reading units 24 and 25 were located within the reading device 20 in the above embodiment, this is not limited to that. For example, the image reading units 24 and 25 may be located within the main body 10.

[0172] The image forming unit 11 does not have to form a color image using the four CMYK colors. It may form an image with a larger number of colors, including other colors. Alternatively, the image forming unit 11 may perform image formation in monochrome or other single colors.

[0173] Furthermore, a specific tray among the supply trays 12a may be permanently assigned for image adjustment. Also, the transport paths 130 and 230 do not need to be reversible.

[0174] Furthermore, while the above description has used non-volatile memory 153 such as HDD, SSD, and flash memory as examples of computer-readable media for storing the program 153a related to position adjustment and image diagnostic control of the present invention, the invention is not limited to these. Other computer-readable media such as other non-volatile memory such as MRAM, and portable recording media such as CD-ROMs and DVD discs can also be used. In addition, carrier waves can also be used as a medium for providing the program data according to the present invention via a communication line. Furthermore, the specific configurations, processing operations, and procedures shown in the above embodiments can be modified as appropriate without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and its equivalents. [Explanation of Symbols]

[0175] 1. Image forming apparatus 10 Main unit of the device 100 Control Unit 11 Image forming operation unit 11a Photoreceptor 11b Intermediate transfer belt 11c Secondary transfer section 111 Laser Diode 112 Fixing section 12 Main paper feed section 12a Supply Tray 13 Conveying section 130 Conveyor paths 131 Reversal transport path 132 Downstream transport route 133 Evacuation and transport route 141 Operation Reception Section 141a Touch Panel 142 Display section 142a display screen 15 Control Block 151 CPU 152 RAM 153 Non-volatile memory 153a Program 153b Feature Information 16 Image Processing Unit 161 Communication Control Unit 162 Image Memory 17 Measurement Unit 171 Thermometer 172 Hygrometer 18. Automatic document feeder 19 Scanner section 191 Imaging Unit 192 Imaging Control Unit 20 Reader 200 Reading Control Unit 23 Conveying section 230 Conveyor paths 24, 25 Image reading unit 26 Colorimeter 40 Paper feeder 50 External device I11, I12 Test Images I21 Chart 1 I22 Second Chart I23 Third Chart I24 Fourth Chart I25, I26 White image M medium

Claims

1. Image forming engine, A reading unit positioned along the transport path of the medium, which reads the medium downstream of the transport path from the image formation position by the image forming engine, An image diagnostic device based on an image formed by an image forming apparatus equipped with the following features: The image forming engine generates a first pattern for adjusting the image forming position. The reading unit reads the first medium on which the first pattern has been formed. An adjustment step to adjust the image formation position based on the reading result of the first medium, After the above adjustment step is performed, The image forming engine generates a second pattern for diagnosing the state of the image forming engine. The reading unit reads the second medium on which the second pattern is formed. A diagnostic step of obtaining a diagnostic result of the state of the image forming engine based on the reading result of the second medium, A diagnostic imaging method that performs this task.

2. In the adjustment step, the front and back orientation of the medium is adjusted. The image diagnostic method according to claim 1.

3. The aforementioned medical imaging device, An acquisition step to acquire information relating to the state of the image formation position, A determination step that determines whether or not to perform the adjustment step before the diagnostic step based on the acquired state, The image diagnostic method according to claim 1, wherein the method is performed.

4. The image forming apparatus includes a supply tray for containing a medium, In the acquisition step, information regarding the replenishment of the medium into the supply tray is acquired as the state. The adjustment step is performed when the medium is replenished in the supply tray after the most recent adjustment step, and / or when the medium is replenished in the supply tray after the most recent image forming operation. The image diagnostic method according to claim 3.

5. In the acquisition step, information regarding the elapsed time since the preceding image forming operation was performed is acquired as the state. In the determination step, it is determined that the adjustment step will be executed if the elapsed time is equal to or greater than the first reference time. The image diagnostic method according to claim 3.

6. The image diagnostic method according to claim 3, wherein in the acquisition step, information relating to at least one of temperature and humidity related to the image forming apparatus is acquired as the state.

7. The image forming apparatus comprises one or more supply trays for containing media, The first medium is supplied from the first supply tray among the supply trays. The image diagnostic method according to claim 1.

8. The image forming apparatus comprises a plurality of supply trays, and a plurality of first supply trays, The adjustment process is performed on each of the first media supplied from the first supply tray. The image diagnostic method according to claim 7.

9. The image diagnostic method according to claim 7, which accepts a setting for selecting the first supply tray.

10. The imaging diagnostic method according to claim 7, wherein the second medium is supplied from part or all of the first supply tray.

11. The imaging diagnostic method according to claim 8, wherein the second medium is supplied from one of the first supply trays.

12. The image forming apparatus includes a supply tray for containing a medium, The image diagnostic apparatus authorizes the execution of the diagnostic process for the supply tray on which the adjustment process has been performed. The image diagnostic method according to claim 1.

13. The image diagnostic method according to claim 10, which accepts a setting to select a first supply tray for performing the diagnostic step.

14. In the diagnostic process, the diagnostic result is output. The image diagnostic method according to claim 1, wherein the output content of the diagnostic result includes the diagnostic result of the image formation position.

15. If the diagnostic step is performed after the adjustment step, the second pattern includes a pattern for identifying the image formation position on the second medium. The diagnostic step involves diagnosing whether the image formation position is correctly adjusted. The image diagnostic method according to claim 14.

16. The process including the adjustment step and the diagnostic step is When the aforementioned image forming engine is started, If it is the specified time, When the image forming engine forms images on a predetermined number of media, If the image forming engine operates for a second reference time or longer, If power is supplied to the image forming engine for a third reference time or longer, And, If a predetermined change is detected in the transport unit that transports the medium, Execute under at least one of the following conditions: The image diagnostic method according to claim 1.

17. The image diagnostic method according to claim 1, wherein before executing the diagnostic step, the method accepts a setting input to determine whether or not to execute the adjustment step.

18. The image diagnostic method according to claim 1, wherein the estimated time required for execution is output during at least one of the execution of the adjustment step and the diagnostic step.

19. An image diagnostic apparatus comprising a control unit capable of performing the image diagnostic method according to any one of claims 1 to 18.

20. An image forming apparatus comprising the image diagnostic apparatus described in claim 19.

21. A program that causes the image diagnostic device to execute the image diagnostic method described in any one of claims 1 to 18.

Images