Image formation device

Abstract

The present invention improves conveyance of a recording material in an image formation device.　This image formation device comprises: a first conveyance path and second and third conveyance paths branching from the first conveyance path; an image formation means that forms an image on a recording material conveyed along the third conveyance path; a discharge tray to which the recording material having passed through the second conveyance path is discharged; a first detection means that detects a first physical property value of the recording material in the first conveyance path; a second detection means that detects a second physical property value of the recording material in the second conveyance path; and a control means that controls conveyance of the recording material. In a first operation mode for registering characteristic data, the control means causes a first recording material to be conveyed from the first conveyance path to the second conveyance path, causes the first detection means to detect the first physical property value of the first recording material in the first conveyance path, causes the second detection means to detect the second physical property value of the first recording material in the second conveyance path, and registers first characteristic data based on the detected first physical property value and second physical property value of the first recording material in a database.

Description

Image forming apparatus

[0001] The present disclosure relates to an image forming apparatus.

[0002] Conventionally, there has been known an image forming apparatus that detects physical property values of a recording material on a conveyance path by a sensor and forms an image on the recording material under image forming conditions adjusted based on the detected physical property values. Patent Documents 1 to 3 disclose examples of such image forming apparatuses. The image forming apparatuses of Patent Documents 1 to 3 have a secondary conveyance path that branches from the main conveyance path before the image forming unit, and when the physical property values of the recording material detected in the main conveyance path indicate an abnormality, the recording material is discharged to the outside through the secondary conveyance path. Thereby, the possibility that an abnormal recording material causes conveyance failures such as jams in the main conveyance path and the print job fails is suppressed.

[0003] Japanese Patent Application Laid-Open No. 2024-000064, Japanese Patent Application Laid-Open No. 2024-000065, Japanese Patent Application Laid-Open No. 2024-000066

[0004] However, there remains room for further improvement in the conveyance of the recording material in the image forming apparatuses known so far.

[0005] According to one aspect, a first conveyance path, a second conveyance path branching from the first conveyance path, a third conveyance path branching from the first conveyance path, an image forming unit that forms an image on a recording material conveyed along the third conveyance path, a discharge tray through which a recording material that has passed through the second conveyance path without passing through the image forming unit is discharged, a first detection unit that detects at least one first physical property value of the recording material in the first conveyance path, a second detection unit that detects at least one second physical property value of the recording material in the second conveyance path, and a control unit that controls the conveyance of the recording material, wherein the control unit, in a first operation mode for registering characteristic data, conveys a first recording material from the first conveyance path to the second conveyance path and discharges it to the discharge tray, causes the first detection unit to detect the first physical property value of the first recording material in the first conveyance path, causes the second detection unit to detect the second physical property value of the first recording material in the second conveyance path, and registers first characteristic data based on the detected first physical property value and the second physical property value of the first recording material in a database. An image forming apparatus is provided.

[0006] According to this disclosure, the transport of recording material in an image forming apparatus can be improved.

[0007] Other features and advantages of the technical ideas derived from this disclosure will become apparent from the following description with reference to the attached drawings. In the attached drawings, the same or similar components are given the same reference numeral.

[0008] The attached drawings are included in the specification and constitute a part thereof, illustrating embodiments in this disclosure and used to explain the technical ideas derived from this disclosure together with their descriptions. Figure 1 is a schematic diagram showing an example of the overall configuration of an image forming apparatus according to the first embodiment. Figure 2 is a schematic diagram showing an example of the configuration of the image forming section of an image forming apparatus according to the first embodiment. Figure 3 is a block diagram showing an example of the configuration of the control system of an image forming apparatus according to the first embodiment. Figure 4 is an explanatory diagram showing an example of the configuration of a characteristic database. Figure 5 is an explanatory diagram showing an example of the configuration of deck data. Figure 6 is a flowchart showing an example of the flow of transport control processing in paper type registration mode. Figure 7 is a flowchart showing a first example of the flow of transport control processing in printing mode. Figure 8 is a flowchart showing a second example of the flow of transport control processing in printing mode. Figure 9 is an explanatory diagram showing a modified example of the configuration of the characteristic database. Figure 10 is a schematic diagram showing an example of the overall configuration of an image forming apparatus according to the second embodiment. Figure 11 is a block diagram showing an example of the configuration of the control system of an image forming apparatus according to the second embodiment. Figure 12A is a first explanatory diagram showing how a sheet is transported in the manual feed transport path. Figure 12B is a second explanatory diagram showing how a sheet is transported along a manual feed transport path. Figure 12C is a third explanatory diagram showing how a sheet is transported along a manual feed transport path. Figure 13 is a schematic diagram showing an example of the overall configuration of an image forming apparatus according to the third embodiment. Figure 14 is a block diagram showing an example of the configuration of the control system of an image forming apparatus according to the third embodiment. Figure 15 is a flowchart showing a first example of the flow of the physical property detection process. Figure 16 is a flowchart showing a second example of the flow of the physical property detection process.

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are necessary, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] <1. First Embodiment> Figure 1 is a schematic diagram showing an example of the overall configuration of the image forming apparatus 100 according to the first embodiment. Referring to Figure 1, the image forming apparatus 100 includes an image forming unit 101, a post-processing unit 102, and a feeding unit 103.

[0011] <1-1. Image Forming Unit> The image forming unit 101 is an image forming means that forms an image on a recording material (also called a sheet) that is transported along a transport path. The image forming unit 101 includes a main body 104 and a fixing unit 105. The main body 104 and the fixing unit 105 may be housed in a single housing.

[0012] The main body 104 has a plurality of feeding decks 9a and 9b, each of which is a storage means for accommodating bundles of sheets. Sheets in the feeding deck 9a or 9b are fed one by one to the transport path 14 by feeding rollers (not shown), and are held between a plurality of transport roller pairs 8 as they are sent through the transport path 13 to the secondary transfer position.

[0013] The image-forming units 10Y, 10M, 10C, and 10K each form toner images using yellow toner, magenta toner, cyan toner, and black toner, respectively. The image-forming units 10Y, 10M, 10C, and 10K transfer the formed toner images onto the intermediate transfer belt 6, overlapping them to form a full-color toner image. Y, M, C, and K are abbreviations for the toner colors. The intermediate transfer belt 6 may also be called the intermediate transfer body. As the intermediate transfer belt 6 rotates, the toner image is transported to the secondary transfer position. The secondary transfer unit 7, located at the secondary transfer position, has an outer roller and an inner roller. The outer and inner rollers of the secondary transfer unit 7 rotate while gripping the intermediate transfer belt 6. Furthermore, the outer roller and the intermediate transfer belt 6 transport the sheet that has reached the secondary transfer position while gripping it. By applying a secondary transfer voltage between the outer and inner rollers, the toner image is transferred from the intermediate transfer belt 6 to the sheet. The sheet onto which the toner image has been transferred is transported from the main unit 104 to the fuser unit 105.

[0014] The fixing unit 105 includes a first fuser 21 and a second fuser 22. In normal fixing mode, the sheet passes through the first fuser 21. The first fuser 21 heats and pressurizes the sheet, fixing the toner image to the sheet. After that, the sheet is transported along the first fixing transport path 15 and discharged to the post-processing unit 102. If double-sided printing is specified, the sheet with the image formed on the first side is guided to the double-sided transport path 17 and passes through the secondary transfer position again. At the secondary transfer position, the secondary transfer section 7 transfers the toner image to the second side of the sheet. The sheet passes through the first fuser 21 again, fixing the toner image on the second side to the sheet.

[0015] If the sheet and toner image require more heat, a gloss fixing mode may be selected instead of the normal fixing mode. In gloss fixing mode, after passing through the first fuser 21, the sheet is guided to the second fixing transport path 16 where the second fuser 22 is located. The second fuser 22 further heats and pressurizes the sheet, thereby increasing the gloss of the sheet and toner image. The sheet is then discharged from the fixing unit 105 to the post-processing unit 102.

[0016] <1-2. Post-processing Unit> The post-processing unit 102 is a post-processing means that applies post-processing to sheets on which images have been formed, which are received from the image forming unit 101. For example, a sheet (e.g., interleaving paper) supplied from the sorter 35 is inserted between a preceding sheet and a succeeding sheet. The sheet processing units 34a and 34b may be a puncher for making holes in sheets, a binding device (e.g., a stapler) for binding multiple sheets together, or an alignment device for aligning multiple sheets. Sheets on which no post-processing is applied are discharged to the discharge tray 31. Sheets on which post-processing is applied in the sheet processing unit 34a are discharged to the discharge tray 32. Sheets on which post-processing is applied in the sheet processing unit 34b are discharged to the discharge tray 33.

[0017] <1-3. Feeding Unit> The feeding unit 103 is a feeding means for supplying sheets to the image forming unit 101. The feeding unit 103 has large capacity decks 40a, 40b, 40c and a manual feed tray 48. Each of the large capacity decks 40a, 40b, and 40c is a storage means capable of accommodating a larger number of sheet bundles compared to the feeding decks 9a and 9b. The manual feed tray 48 is a receiving means for receiving sheets supplied by manual feeding.

[0018] The first transport path 11 is the main transport path through which sheets fed from the large-capacity decks 40a, 40b, and 40c and the manual feed tray 48 pass. The first transport path 11 branches to the second transport path 12 and the third transport path 13. The flapper 42 is a guide member that guides sheets being transported along the first transport path 11 to the second transport path 12 or the third transport path 13. The second transport path 12 is a transport path connecting the first transport path 11 and the escape tray 46, and is also called the escape path. The escape tray 46 is an discharge tray through which sheets that have passed through the second transport path 12 without going through the image forming unit 101 are discharged. Typically, sheets that should not be transported to the image forming unit 101 are discharged to the escape tray 46. The third transport path 13 is a transport path connecting the first transport path 11 and the image forming unit 101. A normal sheet is transported from the first transport path 11 to the third transport path 13 toward the image forming unit 101. Multiple transport roller pairs 45 are arranged along the first transport path 11, the second transport path 12, and the third transport path 13. Multiple transport roller pairs 45 and motors (not shown) that rotate them constitute a transport means for transporting the sheet along the transport path. The fourth transport path 49 is a manual feed transport path that merges with the first transport path 11 and receives sheets from the manual feed tray 48. A transport roller pair 47 is a transport means for transporting the sheet received from the manual feed tray 48 along the fourth transport path 49.

[0019] The first transport path 11 is equipped with at least one sensor collectively referred to as the first sensor 41. Each of the first sensors 41 is a first detection means for detecting at least one first physical property of the sheet in the first transport path 11. For example, the first sensor 41 detects the first physical property without contacting the sheet in the first transport path 11. The at least one first physical property may include at least one of the sheet's basis weight, sheet thickness, and sheet surface properties. Figure 1 shows examples of the first sensors 41, namely a basis weight sensor 41a and a surface property sensor 41b. The image forming apparatus 100 may include more or fewer first sensors 41.

[0020] The basis weight sensor 41a detects the basis weight of the sheet. The basis weight sensor 41a may include, for example, a light-emitting element that irradiates the sheet with light having a predetermined wavelength (e.g., visible light or infrared light), a first light-receiving element that receives the transmitted light that has passed through the sheet on the opposite side of the transport path, and a second light-receiving element that receives the reflected light that has been reflected by the sheet. The basis weight sensor 41a may also detect the basis weight of the sheet based on the ratio of the amount of transmitted light and reflected light to the amount of irradiated light (e.g., attenuation rate). The basis weight sensor 41a may use ultrasound instead of visible light or infrared light. The basis weight sensor 41a can also detect the thickness of the sheet using a similar mechanism.

[0021] The surface properties sensor 41b detects the surface properties of the sheet. Surface properties refer to, for example, the glossiness and / or smoothness of the sheet's surface. The surface properties sensor 41b includes, for example, a light-emitting element that irradiates the sheet with light at a predetermined incident angle, a first light-receiving element that receives specularly reflected light, and a second light-receiving element that receives diffusely reflected light. The surface properties sensor 41b can detect the surface properties of the sheet based on the ratio of the amount of specularly reflected light and diffusely reflected light to the amount of irradiated light. The surface properties sensor 41b may also include a glossiness sensor and a smoothness sensor.

[0022] The second transport path 12 is equipped with at least one sensor collectively referred to as a second sensor 44. Each of the second sensors 44 is a second detection means for detecting at least one second physical property of the sheet in the second transport path 12. For example, the second sensor 44 detects the second physical property by contacting the sheet in the second transport path 12. The at least one second physical property may include at least one of the sheet's stiffness, volume resistivity, and volume resistivity. Figure 1 shows examples of second sensors 44, namely a stiffness sensor 44a and a resistance sensor 44b. The image forming apparatus 100 may include more or fewer second sensors 44.

[0023] The stiffness sensor 44a detects the stiffness of the sheet. For example, the stiffness sensor 44a clamps the sheet with a pair of rollers at a position separated from one end of the sheet, presses the sheet with a pressing member near the clamping position to displace it by a predetermined distance, and measures the rebound force from the sheet. Since a sheet with higher stiffness requires a greater force to displace the sheet by the same distance, the stiffness sensor 44a can detect the stiffness of the sheet based on the measured rebound force.

[0024] The resistance sensor 44b detects the volume resistance (electrical resistance per unit area) or volume resistivity (electrical resistance per unit volume) of the sheet. For example, the resistance sensor 44b applies a voltage to two electrodes that hold the sheet and measures the current flowing between these electrodes. Since the applied voltage is known, the resistance sensor 44b can detect the volume resistance of the sheet based on the measured values ​​of the applied voltage and current. The resistance sensor 44b can also derive the volume resistivity by dividing the volume resistance by the thickness of the sheet.

[0025] The image forming apparatus 100 may include a thickness sensor as the second sensor 44, which mechanically detects the thickness of the sheet by contacting it. The thickness sensor may include a contact element that is displaced by contacting the sheet and an encoder that detects the amount of displacement of the contact element. Since the amount of displacement correlates with the thickness of the sheet, the thickness of the sheet can be determined from the amount of displacement.

[0026] <1-4. Image Forming Unit> Figure 2 is a schematic diagram showing an example of the configuration of the image forming units 10Y, 10M, 10C, and 10K of the image forming apparatus 100. Since the configurations of the image forming units 10Y, 10M, 10C, and 10K are the same except for the toner color, the image forming units 10Y, 10M, 10C, and 10K will be collectively referred to as the image forming unit 10, and one image forming unit 10 will be used as an example for explanation. The image forming unit 10 includes a photoreceptor 1, a charger 2, an exposure device 3, a developing sleeve 4, a primary transfer roller 5, a toner container 50, and a drum cleaner 51.

[0027] The photoreceptor 1 is a cylindrical image carrier that is rotationally driven by a driving means (not shown) such as a motor. The charger 2 is a charging means (for example, a charging roller or charging wire) that charges the surface of the photoreceptor 1. The charger 2 is subjected to a charging voltage, which is an example of an image formation condition. The exposure device 3 forms an electrostatic latent image on the surface of the photoreceptor 1 by irradiating the surface of the photoreceptor 1 with light modulated according to the input image data. The amount of light from the light source of the exposure device 3 is an example of an image formation condition. The toner container 50 is a container that holds toner T. The developing sleeve 4 is a developing means that develops the electrostatic latent image on the surface of the photoreceptor 1 and forms a toner image by supplying toner supplied from the toner container 50 to the photoreceptor 1. The developing sleeve 4 is subjected to a developing voltage, which is an example of an image formation condition. The developing voltage promotes the adhesion of toner T to the photoreceptor 1. As the photoreceptor 1 rotates further, the toner image is transported to the primary transfer position. The primary transfer roller 5 is positioned to face the photoreceptor 1 at the primary transfer position. A primary transfer voltage, which is an example of image formation conditions, is applied between the primary transfer roller 5 and the photoreceptor 1. The primary transfer roller 5 transfers the toner image from the photoreceptor 1 to the intermediate transfer belt 6. The primary transfer voltage promotes the primary transfer of the toner image. The drum cleaner 51 removes the toner T remaining on the photoreceptor 1.

[0028] <1-5. Control System> Figure 3 is a block diagram showing an example of the configuration of the control system of the image forming apparatus 100. Referring to Figure 3, the image forming apparatus 100 includes an operation unit 106, a communication interface 108, a controller 110, and a storage device 120. The controller 110 is connected via an internal bus to the first sensors 41a, 41b, the second sensors 44a, 44b, the image forming unit 101, the post-processing unit 102, the feeding unit 103, the operation unit 106, the communication interface 108, and the storage device 120.

[0029] The operating unit 106 provides a user interface to the user of the image forming apparatus 100. The operating unit 106 includes an input device for receiving user input and an output device for outputting information. The input device may include, for example, a touch panel, buttons, switches, and a microphone. The output device may include, for example, a display and a speaker.

[0030] The communication interface 108 is an interface for the image forming apparatus 100 to communicate with an external device. The communication interface 108 may be a wireless communication interface or a wired communication interface. The functions of the controller 110, which will be described later, may be provided by a host computer that communicates with the image forming apparatus 100 via the communication interface 108.

[0031] The controller 110 is a control means that controls the overall operation of the image forming apparatus 100. The controller 110 may be built into any of the image forming unit 101, the post-processing unit 102, and the feeding unit 103, or it may be distributed among these units, or it may be installed outside of these units. In the example in Figure 3, the controller 110 includes a central processing unit (CPU) 111, read-only memory (ROM) 112, and random access memory (RAM) 113.

[0032] ROM 112 is a non-volatile storage medium that pre-stores computer programs for the control functions of the image forming apparatus 100. RAM 113 is a volatile storage medium that provides a memory area for calculations to the CPU 111. The CPU 111 controls the operation of the image forming apparatus 100 by executing computer programs loaded from ROM 112 into RAM 113. For example, the CPU 111 controls the transport of sheets from the feeding unit 103, the formation of images on the sheets in the image forming unit 101, and the application of post-processing to the sheets in the post-processing unit 102. In particular, in this embodiment, the CPU 111 functions as a registration unit 131 and a print control unit 132.

[0033] Although not shown in Figure 3, the image forming unit 101, the post-processing unit 102, and the feeding unit 103 each include actuators such as motors, rollers, clutches, solenoids, and flappers that are involved in the transport of the sheets. These actuators constitute the transport means in each unit. In this embodiment, multiple operating modes are provided regarding how the CPU 111 controls the transport of the sheets by the transport means. The first operating mode of the multiple operating modes is the paper type registration mode, and the second operating mode is the printing mode. The registration unit 131 is a functional module responsible for transport control and other controls in the paper type registration mode. The printing control unit 132 is a functional module responsible for transport control and other controls in the printing mode. The functions of these functional modules will be described in detail later.

[0034] The storage device 120 is a storage means having a large storage area, such as a hard disk drive (HDD). In this embodiment, the storage device 120 stores a characteristics database (DB) 121 and deck data 122. The characteristics DB 121 is a database that holds characteristic data of sheets associated with the type of sheet. The deck data 122 is data (also called storage data) indicating the types of recording materials stored in the feeding decks 9a and 9b and the large capacity decks 40a, 40b, and 40c, respectively, in the image forming apparatus 100.

[0035] Figure 4 is an explanatory diagram showing an example of the configuration of the characteristics DB 121. Referring to Figure 4, the characteristics DB 121 includes a type name 121a, physical property data 121b, and image formation conditions 121c. The type name 121a is identification information (hereinafter also referred to as type ID) for uniquely identifying the type of sheet. The type name 121a may be assigned by the user when a new type is registered, may be set automatically, or may be a combination of these. The type name 121a may be a name such as "plain paper," "matt paper," "coated paper," "embossed paper," and "synthetic paper," or it may be a brand name unique to the manufacturer. The physical property data 121b is a set of multiple physical property values ​​detected for each type of sheet. In the illustrated example, the physical property data 121b includes four physical property values: basis weight, surface properties, stiffness, and volume resistivity. The image formation conditions 121c is data indicating image formation conditions suitable for each type of sheet. For example, the image formation conditions 121c may include one or more of the following: sheet transport speed, target fixing temperature, charging voltage, development voltage, primary transfer voltage, secondary transfer voltage, and the fixing mode to be selected. Since methods for determining suitable image formation conditions from physical properties are well known in the industry, they will not be described in detail here.

[0036] Figure 5 is an explanatory diagram showing an example of the configuration of deck data 122. Referring to Figure 5, deck data 122 includes deck number 122a and paper type 122b. Deck number 122a is identification information for uniquely identifying each of the storage means of the image forming apparatus 100, i.e., each deck. Paper type 122b identifies the type of sheet currently stored in each deck using the type ID registered in the type name 121a of the characteristic DB 121. For decks where the type of sheet stored is unknown, paper type 122b may be left blank. Although not shown in Figure 5, deck data 122 may also include further data items such as sheet size and remaining sheet quantity.

[0037] In this embodiment, the data described as being held by the storage device 120 of the image forming apparatus 100 may be held by an external database (for example, a database server on a network) in other embodiments.

[0038] <1-6. Two Operating Modes> Conventionally, when the physical properties of the recording material detected in the main transport path show abnormalities, a technique is known to discharge the recording material to the outside of the image forming apparatus via a secondary transport path. For example, if a sheet with excessively high rigidity is fed into the image forming apparatus, the sheet may cause a jam during transport, and in the worst case, it may damage the internal structure of the apparatus. By discharging such abnormal sheets to the outside of the apparatus without supplying them to the image forming unit, transport failures are reduced, and the possibility of print job failures is suppressed.

[0039] However, some physical properties of recording materials can be detected non-contact without stopping the sheet, while others require stopping the sheet or contact with a component to detect them. The first physical property mentioned above is an example of the former, and the second physical property is an example of the latter. If these physical properties of each sheet are constantly detected in a printing job, productivity will decrease, but if the sheets are transported without detecting the physical properties, the risk of malfunctions will increase, so there is a trade-off between these two.

[0040] Therefore, in this embodiment, the image forming apparatus 100 is equipped with a paper type registration mode for registering characteristic data, in addition to the printing mode for image formation. In the paper type registration mode, the registration unit 131 registers characteristic data based on the first physical property values ​​detected by the first sensors 41a and 41b and the second physical property values ​​detected by the second sensors 44a and 44b, in association with the type of sheet (first recording material), in the characteristic DB 121. The registration unit 131 transports the sheet from the first transport path 11 to the second transport path 12 of the feeding unit 103 and discharges it into the escape tray 46. Therefore, the sheet is not transported to the image forming unit 101.

[0041] On the other hand, in the printing mode, the printing control unit 132 of the controller 110 determines the type of the sheet (second recording material) based on the first physical property value detected by the above-described first sensors 41a and 41b, and acquires the image forming conditions corresponding to the determined type from the characteristic DB 121. Then, the printing control unit 132 causes the sheet to be conveyed from the first conveyance path 11 to the third conveyance path 13, and controls the image forming unit 101 to form an image on the sheet using the acquired image forming conditions.

[0042] In this way, by guiding the sheet to the escape path in the paper type registration mode while detecting all required physical property values and registering the characteristic data in the database, it is possible to eliminate the need to detect all required physical property values of each sheet in the printing mode. Thereby, it is possible to prevent an inappropriate sheet conveyance from occurring while avoiding a decrease in the productivity of the print job.

[0043] The printing mode may be further divided into an automatic determination mode in which automatic determination of the sheet type is enabled and a non-automatic determination mode in which automatic determination of the sheet type is not enabled. In the non-automatic determination mode (third operation mode), the type of the sheet (third recording material) is specified by the user.

[0044] The operation unit 106 provides a mode selection screen for allowing the user to select an operation mode between the paper type registration mode and the printing mode. When the printing mode is selected, the operation unit 106 may further allow the user to select one of the automatic determination mode and the non-automatic determination mode. When the non-automatic determination mode is selected (that is, when automatic determination of the sheet type is not enabled), the operation unit 106 may accept a user input for specifying the sheet type on the screen. Such a user interface may be provided by an external device (for example, a host computer or a user terminal) via the communication interface 108 instead of the operation unit 106.

[0045] (1) Paper type registration mode FIG. 6 is a flowchart showing an example of the flow of conveyance control processing that can be executed in the paper type registration mode. In the flowchart, 'S' is an abbreviation for step.

[0046] First, in S11, in response to an instruction to start paper type registration, the registration unit 131 feeds a sheet (first recording material) from the designated deck (or the manual feed tray 48) to the first conveyance path 11.

[0047] Next, in S12, the registration unit 131 causes at least one first physical property value of the sheet to be detected by the first sensor 41 in the first conveyance path 11. For example, the basis weight sensor 41a detects the basis weight of the sheet, and the surface property sensor 41b detects the surface property of the sheet.

[0048] Next, in S13, the registration unit 131 controls the conveyance means to convey the sheet from the first conveyance path 11 to the second conveyance path 12. For example, the registration unit 131 switches the posture of the flapper 42 to a posture that guides the sheet to the second conveyance path 12 instead of the third conveyance path 13.

[0049] Next, in S14, the registration unit 131 determines whether to further detect at least one second physical property value of the sheet based on the first physical property value detected by the first sensor 41. For example, if the type of the sheet can be uniquely determined based on the first physical property value detected by the first sensor 41, the detection of the second physical property value in S15 may be omitted. If it is determined that the second physical property value should be detected, the process proceeds to S15.

[0050] In S15, the registration unit 131 causes at least one second physical property value of the sheet to be detected by the second sensor 44 in the second conveyance path 12. For example, the stiffness sensor 44a detects the stiffness of the sheet, and the resistance sensor 44b detects the volume resistance value of the sheet.

[0051] Next, in S16, the registration unit 131 determines the type of sheet based on the first physical property value detected in S12 and the second physical property value detected in S15. The determination of the type of sheet may be performed, for example, using a trained model acquired in advance by machine learning processing based on a large number of data samples of known type names and corresponding known physical property values. The trained model divides the vector space of physical property value vectors into subspaces corresponding to each candidate type of sheet. The registration unit 131 can determine the type of sheet by applying the set of physical property values ​​detected in the paper type registration mode to the trained model.

[0052] Next, in S17, the registration unit 131 determines image formation conditions suitable for the type of sheet determined in S16, based on the first and second physical properties detected for that sheet. Note that if the image formation conditions are determined dynamically when the print job is executed, the transport control process in Figure 6 does not need to include S17.

[0053] Next, in S18, the registration unit 131 registers the first characteristic data based on the first and second physical property values ​​of the sheet as a new record in the characteristic DB 121, associated with the type determined in S16. If a record associated with the same type already exists in the characteristic DB 121, the registration unit 131 may cancel the registration of the new record or overwrite the existing record with the new record.

[0054] Next, in S19, the registration unit 131 discharges the sheet from the second transport path 12 to the escape tray 46. After that, the transport control process shown in Figure 6 is completed.

[0055] (2) Print Mode - First Example Figure 7 is a flowchart showing a first example of the flow of transport control processing that can be performed in print mode.

[0056] First, in S21, the print control unit 132, in response to the instruction to start a print job, feeds a sheet from the designated deck (or manual feed tray 48) to the first transport path 11.

[0057] The subsequent processing branches in S22 depending on whether automatic sheet type detection is enabled or not. If automatic detection is enabled, the process proceeds to S23. On the other hand, if automatic detection is not enabled, the process proceeds to S31.

[0058] In S23, the printing control unit 132 causes the first sensor 41 to detect at least one first physical property value of the sheet (second recording material) in the first transport path 11. For example, the basis weight sensor 41a detects the basis weight of the sheet, and the surface quality sensor 41b detects the surface quality of the sheet.

[0059] Next, in S24, the print control unit 132 determines the type of sheet based on the first physical property value detected in S23. The determination of the sheet type here may be performed using the same trained model used in the paper type registration mode, or it may be performed using a separate trained model.

[0060] Next, in S26, the print control unit 132 obtains image formation conditions corresponding to the type of sheet determined based on the first physical property values. For example, the print control unit 132 may identify characteristic data associated with the determined type of sheet (i.e., characteristic data for the second recording material) in the characteristic DB 121 and obtain image formation conditions corresponding to the identified characteristic data from the characteristic DB 121. Alternatively, the print control unit 132 may dynamically determine the image formation conditions based on the physical property values ​​indicated by the characteristic data for the second recording material.

[0061] Next, in S27, the printing control unit 132 controls the transport means to transport the sheet from the first transport path 11 to the third transport path 13. For example, the printing control unit 132 switches the orientation of the flapper 42 to an orientation that guides the sheet to the third transport path 13 instead of the second transport path 12.

[0062] Next, in S28, the print control unit 132 controls the image forming unit 101 to form an image on the sheet using the image forming conditions acquired in S26. The sheet on which the image has been formed in the image forming unit 101 is subjected to post-processing in the post-processing unit 102 as needed, and then discharged to the discharge trays 31, 32, or 33.

[0063] Next, in S29, the print control unit 132 determines whether the print job has finished. If there are subsequent pages to be printed, it is determined that the print job has not finished, and the process proceeds to S32. If there are no subsequent pages remaining, it is determined that the print job has finished, and the transport control process shown in Figure 7 is terminated.

[0064] If automatic determination is not enabled in S22, in S31, the print control unit 132 receives user input via the operation unit 106 to specify the type of sheet (third recording material). The user input received here may also specify the deck from which the sheet is fed. In that case, the print control unit 132 can obtain the type of sheet contained in the specified deck by referring to the deck data 122. Alternatively, the user input may specify one of the sheet types registered in the characteristics DB 121.

[0065] Next, in S32, the printing control unit 132 causes the first sensor 41 to detect at least one first physical property of the sheet in the first transport path 11. For example, the basis weight sensor 41a detects the basis weight of the sheet, and the surface quality sensor 41b detects the surface quality of the sheet.

[0066] Next, in S33, the print control unit 132 verifies the validity of the sheet type specified in S31 based on the first physical property value detected in S32. For example, the print control unit 132 determines the sheet type based on the first physical property value detected in S32 and verifies whether the determined type matches the type specified by user input. If the sheet types match, the verification is determined to be successful in S34, and the process proceeds to S35. On the other hand, if the sheet types do not match, the verification is determined to be a failure, and the process proceeds to S36.

[0067] Furthermore, the detection of the first physical property value in S32 and the verification in S33 are also performed for the second and subsequent sheets if automatic determination of the sheet type is enabled. In this case, the print control unit 132 can determine that the sheet type is valid when the sheet type determined based on the first physical property value of the k-th sheet (k>1) matches the sheet types up to the k-1th sheet.

[0068] In S35, the print control unit 132 acquires image formation conditions corresponding to the specified sheet type (or the same type as the preceding sheet). The acquisition of image formation conditions here may be performed in the same manner as in S26. Then, the process proceeds to S27, where the sheet is transported from the first transport path 11 to the third transport path 13, and an image is formed on the sheet by the image formation unit 101 using the image formation conditions acquired in S35.

[0069] If the verification is determined to be a failure in S34, the print control unit 132 controls the transport means so as not to transport the sheet from the first transport path 11 to the third transport path 13. In S36, the print control unit 132 notifies the user of the abnormality regarding the type of sheet via the operation unit 106 (for example, by displaying a message indicating the abnormality on the screen). Also in S38, the print control unit 132 controls the transport means so as to discharge the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46. After that, the transport control process shown in Figure 7 is terminated.

[0070] (3) Print Mode - Second Example Figure 8 is a flowchart showing a second example of the flow of transport control processing that can be performed in print mode. Below, only the parts that differ from the first example will be explained.

[0071] In the second example, if automatic determination of the sheet type is enabled, the print control unit 132 determines the sheet type based on the first physical property value in S24, and then determines in S25 whether the determined sheet type is compatible with the image forming apparatus 100. For example, the print control unit 132 may determine that the determined sheet type is not compatible with the image forming apparatus 100 if the corresponding characteristic data obtained from the characteristic DB 121 shows a physical property value that deviates from the range of physical property values ​​supported by the image forming apparatus 100.

[0072] If it is determined that the type of sheet is suitable for the image forming apparatus 100, the process proceeds to S26, where the sheet is transported from the first transport path 11 to the third transport path 13, and an image is formed on the sheet by the image forming unit 101 using image forming conditions suitable for the sheet.

[0073] If it is determined that the type of sheet is not compatible with the image forming apparatus 100, the process proceeds to S36. In S36, the print control unit 132 notifies the user of the abnormality regarding the type of sheet via the operation unit 106 (for example, by displaying a message indicating the abnormality on the screen). Also, in S38, the print control unit 132 controls the transport means to discharge the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46.

[0074] In the second example, as described above, in print mode, if the characteristic data stored in the characteristic DB 121 indicates that the sheet is not suitable for the image forming apparatus 100, the sheet is discharged to the escape tray 46 without being transported to the third transport path 13. This reduces the possibility of print jobs failing due to abnormalities such as transport failures occurring in the image forming unit 101 or post-processing unit 102 due to the physical properties of the sheet.

[0075] (4) Printing Mode - Modified Characteristics DB 121 may further store compatibility data for each type of sheet, indicating whether one or more functions of the image forming apparatus 100 support that type of sheet. Figure 9 is an explanatory diagram showing such a modified configuration of the characteristics DB 121. Referring to Figure 9, the characteristics DB 121 includes compatibility data 121d in addition to the type name 121a, physical property data 121b, and image forming conditions 121c. The compatibility data 121d includes a flag, for example, that indicates with the value "YES" or "NO" whether "Process A" and "Process B" each support each type of sheet.

[0076] For example, let's assume that "Process A" is an image formation process and "Process B" is a binding process, which is a type of post-processing. In this case, since "Process A" in the conformance data 121d indicates "YES" for type name "TYPE 11", it is permissible to form an image on a sheet of the type identified by "TYPE 11". Also, since "Process B" in the conformance data 121d indicates "YES" for type name "TYPE 11", it is permissible for the post-processing unit 102 to bind multiple sheets of the type identified by "TYPE 11". On the other hand, since "Process B" in the conformance data 121d indicates "NO" for type name "TYPE 21", it is prohibited for the post-processing unit 102 to bind multiple sheets of the type identified by "TYPE 21".

[0077] The print control unit 132 may, in print mode, control the application of image formation on the sheet in the image forming unit 101 and post-processing on the sheet in the post-processing unit 102 based on the aforementioned suitability data stored in the characteristics DB 121. For example, in a print job that specifies that a particular process should be performed, if the suitability data prohibits that particular process for a sheet of a type that has been automatically determined, the print control unit 132 may discharge the sheet to the escape tray 46 without transporting it to the third transport path 13.

[0078] In the first embodiment described above, in a paper type registration mode different from the printing mode, characteristic data indicating the physical properties of sheets that may cause abnormalities in the image forming unit 101 and the post-processing unit 102 can also be registered in the characteristic DB 121. Therefore, when the same type of sheet is loaded in the printing mode, the risk posed by that sheet can be appropriately determined by referring to the characteristic DB 121, and measures to avoid abnormalities can be reliably taken.

[0079] Up to this point, we have mainly described an example in which the second sensor 44 is located in the second transport path 12 that branches off from the first transport path 11. However, the second sensor 44 may also be located in the first transport path 11 together with the first sensor 41. In this case, in paper type registration mode, the first and second physical properties of the sheet are detected by the first sensor 41 and the second sensor 44, respectively, in the first transport path 11, and then the sheet is discharged from the first transport path 11 through the second transport path 12 to the escape tray 46. In printing mode, only the first physical property of the sheet is detected by the first sensor 41 in the first transport path 11, and then the sheet can be transported from the first transport path 11 to the third transport path 13 for image formation.

[0080] <2. Second Embodiment> In the second embodiment described in this section, improvements are made to countermeasures against abnormalities caused by the characteristics of the sheet supplied by manual feeding.

[0081] Figure 10 is a schematic diagram showing an example of the overall configuration of the image forming apparatus 200 according to the second embodiment. Referring to Figure 10, the image forming apparatus 200 includes an image forming unit 101, a post-processing unit 102, and a feeding unit 203.

[0082] <2-1. Feeding Unit> The feeding unit 203 has the same configuration as the feeding unit 103 of the image forming apparatus 100 according to the first embodiment, except that it additionally has a media sensor 250 and a sheet sensor 255 arranged in the fourth transport path 49, which is a manual feed transport path. The media sensor 250 is a detection means for detecting one or more physical properties of a sheet in the fourth transport path 49. The one or more physical properties here include at least one of the basis weight of the recording material, the thickness of the recording material, and the surface properties of the recording material. The sheet sensor 255 is a detection means for detecting the leading edge of a sheet being transported in the forward direction (to the left in the figure) of the fourth transport path 49.

[0083] <2-2. Control System> Figure 11 is a block diagram showing an example of the configuration of the control system of the image forming apparatus 200. Referring to Figure 11, the image forming apparatus 200 includes an operation unit 106, a communication interface 108, a controller 210, and a storage device 120. The controller 210 is connected via an internal bus to the first sensors 41a, 41b, the second sensors 44a, 44b, the image forming unit 101, the post-processing unit 102, the feeding unit 203, the operation unit 106, the communication interface 108, the storage device 120, the media sensor 250, and the sheet sensor 255.

[0084] The controller 210 is a control means that controls the overall operation of the image forming apparatus 200. The controller 210 may be built into any of the image forming unit 101, the post-processing unit 102, and the feeding unit 203, or it may be distributed among these units, or it may be installed outside of these units. In the example in Figure 11, the controller 210 includes a CPU 211, a ROM 112, and a RAM 113.

[0085] The CPU 211 controls the operation of the image forming apparatus 200 by executing a computer program loaded from the ROM 112 into the RAM 113. For example, the CPU 211 controls the transport of sheets from the feeding unit 203, the formation of images on the sheets in the image forming unit 101, and the application of post-processing to the sheets in the post-processing unit 102. In particular, in this embodiment, the CPU 211 functions as a registration unit 131, a printing control unit 132, and a transport control unit 233. The transport control unit 233 controls the transport of sheets in the manual feed transport path by the transport means of the feeding unit 203.

[0086] The storage device 120 stores the same characteristic DB 121 and deck data 122 as described in the first embodiment. In this embodiment, the characteristic DB 121 includes data (for example, physical property data 121b or compatibility data 121d) indicating whether a sheet of a particular type has physical properties suitable for the image forming apparatus 200.

[0087] As shown in Figure 11, the media sensor 250 includes a third sensor 251, a fourth sensor 252, and a measurement circuit 253. The third sensor 251 may be a sensor that detects the basis weight (or mechanical properties such as thickness) of the sheet using light or ultrasound, similar to the basis weight sensor 41a described above. The fourth sensor 252 may be a sensor that detects surface properties by receiving specularly reflected and diffusely reflected light from light irradiated onto the sheet, similar to the surface properties sensor 41b described above. The measurement circuit 253 is a circuit that converts the measured values ​​output from the third sensor 251 and the fourth sensor 252 into a format of physical property values ​​suitable for determining the type of sheet.

[0088] <2-3. Details of Conveyance Control> Figures 12A to 12C are explanatory diagrams showing enlarged views of how a sheet is conveyed in the manual feed conveyance path 49. As shown in the diagrams, in this embodiment, a pair of conveyance rollers 47a is located near the entrance of the manual feed conveyance path 49, and a pair of conveyance rollers 47b is located at a distance from the pair of conveyance rollers 47a. A sheet sensor 255 and a media sensor 250 are arranged between the pair of conveyance rollers 47a and the pair of conveyance rollers 47b. Furthermore, a pressing roller 260 is arranged near the media sensor 250, facing the media sensor 250. The pressing roller 260 can advance and retract in the vertical direction A2, which is perpendicular to the sheet conveyance direction A1.

[0089] The transport control unit 233 determines that the sheet has reached the detection position of the media sensor 250 after a predetermined time has elapsed since the leading edge of the sheet received from the manual feed tray 48 into the manual feed transport path 49 was detected by the sheet sensor 255 (see Figure 12A). The transport control unit 233 then extends the pressing roller 260 downward from its retracted position and presses the sheet against it (see Figure 12B). The transport control unit 233 also causes the media sensor 250 to detect the physical properties of the sheet being transported along the manual feed transport path 49. While the media sensor 250 is detecting the physical properties of the sheet, the pressing roller 260 remains in its extended position and continues to press the sheet. This stabilizes the posture of the manually fed sheet and enables highly accurate detection of its physical properties.

[0090] The transport control unit 233 acquires characteristic data associated with the type of sheet from the characteristic DB 121 based on the physical property values ​​of the sheet detected by the media sensor 250. The transport control unit 233 may, for example, determine the type of sheet based on the detected physical property values, similar to the printing control unit 132 in the first embodiment, and acquire characteristic data associated with the determined type from the characteristic DB 121. The transport control unit 233 then interrupts the transport of the sheet to the main transport path 11 if the acquired characteristic data (for example, physical property data or compatibility data) indicates that the sheet has physical properties that make it unsuitable for the image forming apparatus 200. Specifically, the transport control unit 233 retracts the pressing roller 260 upward to end the pressing of the sheet and rotates the transport roller pair 47a and 47b in the opposite direction. As a result, the sheet is transported in the reverse direction of the manual feed transport path 49 (see Figure 12C) and discharged into the manual feed tray 48. In Figures 12A to 12C, the forward direction of transport in the manual feed transport path 49 is indicated by arrow A1+, and the reverse direction is indicated by arrow A1-.

[0091] Thus, in this embodiment, if a sheet supplied by manual feeding has physical properties that are not suitable for the image forming apparatus 200, the sheet is not transported not only to the normal path where image formation takes place, but also to the escape path. This makes it possible to more effectively suppress the possibility of abnormalities such as transport failures occurring.

[0092] When the characteristic data acquired by the media sensor 250 indicates that the sheet has physical properties suitable for the image forming apparatus 200, the transport control unit 233 continues to transport the sheet in the forward direction of the manual transport path 49 and hands the sheet over to the main transport path 11. Subsequent transport control is performed in the same manner as in the first embodiment.

[0093] <3. Third Embodiment> In the third embodiment described in this section, measures are added to address type misjudgments caused by double feeding of sheets.

[0094] Figure 13 is a schematic diagram showing an example of the overall configuration of the image forming apparatus 300 according to the third embodiment. Referring to Figure 13, the image forming apparatus 300 includes an image forming unit 101, a post-processing unit 102, and a feeding unit 303.

[0095] <3-1. Feeding Unit> The feeding unit 303 has the same configuration as the feeding unit 103 of the image forming apparatus 100 according to the first embodiment, except that it additionally has a double-feed sensor 350 disposed in the first transport path 11. The double-feed sensor 350 is a detection means for detecting whether double-feeding (a phenomenon in which multiple sheets are transported overlapping each other) is occurring in the sheets passing through the first transport path 11. For example, the double-feed sensor 350 receives ultrasonic waves emitted from an ultrasonic oscillating element that have passed through the sheet with an ultrasonic receiving element, measures the attenuation of the ultrasonic waves, and detects double-feeding based on the measurement result.

[0096] <3-2. Control System> Figure 14 is a block diagram showing an example of the configuration of the control system of the image forming apparatus 300. Referring to Figure 14, the image forming apparatus 300 includes an operation unit 106, a communication interface 108, a controller 310, and a storage device 120. The controller 310 is connected via an internal bus to the first sensors 41a, 41b, the second sensors 44a, 44b, the image forming unit 101, the post-processing unit 102, the feeding unit 303, the operation unit 106, the communication interface 108, the storage device 120, and the double-feed sensor 350.

[0097] The controller 310 is a control means that controls the overall operation of the image forming apparatus 300. The controller 310 may be built into any of the image forming unit 101, the post-processing unit 102, and the feeding unit 303, or it may be distributed among these units, or it may be installed outside of these units. In the example in Figure 14, the controller 310 includes a CPU 311, a ROM 112, and a RAM 113.

[0098] The CPU 311 controls the operation of the image forming apparatus 300 by executing a computer program loaded from the ROM 112 into the RAM 113. For example, the CPU 311 controls the transport of sheets from the feeding unit 303, the formation of images on the sheets in the image forming unit 101, and the application of post-processing to the sheets in the post-processing unit 102. In particular, in this embodiment, the CPU 311 functions as a registration unit 131, a print control unit 132, and a retraction control unit 333.

[0099] When the double-feed sensor 350 detects that a double-feed is occurring with respect to a sheet being transported along the first transport path 11, the escape control unit 333 discharges the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46.

[0100] In the example shown in Figure 13, the double-feed sensor 350 is positioned upstream of the two first sensors 41a and 41b in the transport direction. In this example, the double-feed sensor 350 can detect whether a double-feed is occurring before the first sensors 41a and 41b detect the first physical property value. Therefore, when the double-feed sensor 350 detects that a double-feed is occurring in the sheet being transported, the escape control unit 333 discharges the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46 without causing the first sensors 41a and 41b to detect the first physical property value.

[0101] In other examples, the double-feed sensor 350 may be positioned downstream in the transport direction from the two first sensors 41a and 41b, as long as it is upstream of the branching point to the second transport path 12 and the third transport path 13. In this example, the first sensors 41a and 41b detect a first physical property before the double-feed sensor 350 detects whether a double-feed is occurring. The data of the first physical property detected by the first sensors 41a and 41b is buffered, for example, in the RAM 113. When the double-feed sensor 350 detects that a double-feed is occurring in a sheet being transported, the escape control unit 333 discards the data of the first physical property detected by the first sensors 41a and 41b and discharges the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46.

[0102] The retraction control unit 333 may, when the double-feed sensor 350 detects that a double-feed is occurring, notify the user via the operation unit 106 that the sheet will be discharged to the escape tray 46 due to the double-feed.

[0103] <3-3. Flow of Evacuation Control Processing> (1) First Example Figure 15 is a flowchart showing a first example of the flow of evacuation control processing that can be performed in this embodiment. The evacuation control processing in Figure 15 can be performed, for example, instead of S23 and S32 in the transport control processing in Figures 7 and 8. In the first example, the double-feed sensor 350 is located upstream of the two first sensors 41a and 41b.

[0104] First, in S111, the retraction control unit 333 activates the double feed sensor 350 in accordance with the timing when the leading edge of the sheet fed to the first transport path 11 reaches the detection position of the double feed sensor 350.

[0105] Next, in S112, the double-feed sensor 350 detects whether a double-feed of sheets has occurred. If the double-feed sensor 350 does not detect a double-feed of sheets, the process proceeds to S113. On the other hand, if the double-feed sensor 350 detects that a double-feed of sheets has occurred, the process proceeds to S116.

[0106] In S113, the basis weight sensor 41a detects the basis weight of the sheet in the first transport path 11. Next, in S114, the surface properties sensor 41b detects the surface properties of the sheet in the first transport path 11. Next, in S115, the basis weight sensor 41a and the surface properties sensor 41b output the detected physical property values ​​to the print control unit 132.

[0107] Meanwhile, in S116, the retraction control unit 333 stops the operation of the two first sensors, namely the basis weight sensor 41a and the surface quality sensor 41b. Next, in S117, the retraction control unit 333 controls the transport means to discharge the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46. Next, in S118, the retraction control unit 333 notifies the user of the occurrence of double feeding via the operation unit 106. Then, the retraction control process shown in Figure 15 is completed.

[0108] (2) Second example Figure 16 is a flowchart showing a second example of the flow of the retraction control process that can be performed in this embodiment. The retraction control process in Figure 16 can be performed, for example, instead of S23 and S32 in the transport control process in Figures 7 and 8. In the second example, the double-feed sensor 350 is located downstream of the two first sensors 41a and 41b.

[0109] First, in S121, the basis weight sensor 41a detects the basis weight of the sheet in the first transport path 11. The basis weight detection result is buffered by the RAM 113. Next, in S122, the surface quality sensor 41b detects the surface quality of the sheet in the first transport path 11. The surface quality detection result is buffered by the RAM 113.

[0110] Next, in S123, the retraction control unit 333 activates the double feed sensor 350 in accordance with the timing when the leading edge of the sheet reaches the detection position of the double feed sensor 350. Next, in S124, the double feed sensor 350 detects whether a double feed of the sheet has occurred. If the double feed sensor 350 does not detect that a double feed of the sheet has occurred, the process proceeds to S125. On the other hand, if the double feed sensor 350 detects that a double feed of the sheet has occurred, the process proceeds to S126.

[0111] In S125, the print control unit 132 acquires the detection results of basis weight and surface quality that have been buffered by the RAM 113.

[0112] Meanwhile, in S126, the escape control unit 333 discards the basis weight and surface quality detection results that have been buffered by the RAM 113. Next, in S127, the escape control unit 333 controls the transport means to discharge the sheet from the first transport path 11 through the second transport path 12 to the escape tray 46. Next, in S128, the escape control unit 333 notifies the user of the occurrence of double feeding via the operation unit 106. Then, the escape control process shown in Figure 16 is completed.

[0113] Generally, detecting the physical properties of a sheet (e.g., basis weight or thickness) while it is being fed in a double-feed state results in significant errors in the detection results, which lead to inaccurate determination of the sheet type. Incorrect sheet type determination can lead to poor transport and reduced print quality due to the use of inappropriate image formation conditions. In contrast, in this embodiment, the physical properties detected while it is being fed in a double-feed state are not used to determine the sheet type, thus avoiding errors in sheet type and preventing poor transport and reduced print quality.

[0114] <4. Other Embodiments> The above embodiments can also be realized in the form of a process in which a program that implements one or more functions is supplied to a system or device via a network or storage medium, and one or more processors in the computer of that system or device read and execute the program. They can also be realized by a circuit (e.g., ASIC) that implements one or more functions.

[0115] The technical ideas derived from this disclosure are not limited to the exemplary embodiments disclosed, but are intended to encompass various modifications of the exemplary embodiments, or substitutions with equivalent structures or functions. The scope of the following claims should be interpreted in the broadest way to encompass all such modifications and equivalent structures and functions.

[0116] This application claims priority based on Japanese Patent Application No. 2025-017911, filed on February 5, 2025, and all of its contents are incorporated herein by reference.

[0117] 11: First transport path, 12: Second transport path, 13: Third transport path, 40a, 40b, 40c: High-capacity deck, 41a, 41b: First sensor, 44a, 44b: Second sensor, 46: Escape tray, 48: Manual feed tray, 49: Fourth transport path, 100, 200, 300: Image forming apparatus, 101: Image forming unit, 102: Post-processing unit, 103, 203, 303: Feeding unit, 104: Main unit, 105: Fixing unit, 110, 210, 310: Controller, 121: Characteristics DB, 122: Deck data, 250: Media sensor, 255: Sheet sensor, 350: Double feed sensor

Claims

1. The system comprises: a first transport path; a second transport path branching from the first transport path; a third transport path branching from the first transport path; an image forming means for forming an image on recording material transported along the third transport path; an discharge tray from which recording material that has passed through the second transport path without passing through the image forming means is discharged; a first detection means for detecting at least one first physical property of the recording material in the first transport path; a second detection means for detecting at least one second physical property of the recording material in the second transport path; and a control means for controlling the transport of the recording material, wherein the control means, in a first operating mode for registering characteristic data, transports the first recording material from the first transport path to the second transport path and discharges it to the discharge tray; causes the first detection means to detect the first physical property of the first recording material in the first transport path; and causes the second detection means to detect the second physical property of the first recording material in the second transport path. An image forming apparatus that registers first characteristic data based on the first and second physical properties of the detected first recording material into a database.

2. The image forming apparatus according to claim 1, wherein the control means controls the image forming means in a second operating mode for image forming, such that the control means causes the first detection means to detect the first physical property of the second recording material in the first transport path, identifies second characteristic data for the second recording material registered in the database based on the detected first physical property of the second recording material, transports the second recording material from the first transport path to the third transport path, and forms an image on the second recording material using image forming conditions based on the identified second characteristic data.

3. The image forming apparatus according to claim 1 or 2, wherein the first detection means detects the at least one first physical property value in the first transport path without contacting the recording material, and the second detection means detects the at least one second physical property value in contact with the recording material in the second transport path.

4. The image forming apparatus according to any one of claims 1 to 3, wherein the first detection means detects the at least one first physical property value while the recording material is being transported along the first transport path, and the second detection means detects the at least one second physical property value while the recording material is stopped along the second transport path.

5. The image forming apparatus according to any one of claims 1 to 4, wherein the at least one first physical property value includes at least one of the basis weight of the recording material, the thickness of the recording material, and the surface properties of the recording material.

6. The image forming apparatus according to any one of claims 1 to 5, wherein the at least one second physical property value includes at least one of the stiffness of the recording material, the volume resistivity of the recording material, and the volume resistivity of the recording material.

7. The image forming apparatus according to claim 2, wherein the control means registers the first characteristic data in the database in association with the type of the first recording material in the first operating mode.

8. The image forming apparatus according to claim 7, wherein the control means determines the type of the second recording material based on the first physical property value of the second recording material detected by the first detection means in the second operating mode, and identifies the characteristic data associated with the determined type of the second recording material as the second characteristic data for the second recording material.

9. The image forming apparatus according to claim 8, wherein, in the second operating mode, the control means discharges the second recording material to the discharge tray via the second transport path without transporting it to the third transport path if the second characteristic data registered in the database indicates that the second recording material is not suitable for the image forming apparatus.

10. The image forming apparatus according to any one of claims 1 to 9, wherein the control means, in a third operating mode for image forming, receives user input to specify the type of third recording material, causes the first detection means to detect the first physical property of the third recording material in the first transport path, determines the type of the third recording material based on the detected first physical property of the third recording material, transports the third recording material from the first transport path to the third transport path when the type specified by the user input matches the type determined based on the first physical property, identifies third characteristic data associated with the type of the third recording material in the database, and controls the image forming means to form an image on the third recording material using image forming conditions based on the identified third characteristic data.

11. The image forming apparatus according to claim 10, wherein the control means, in the third operating mode, does not transport the third recording material from the first transport path to the third transport path if the type specified by the user input does not match the type determined based on the first physical property value.

12. The image forming apparatus according to claim 10 or 11, wherein the control means discharges the third recording material from the first transport path to the discharge tray via the second transport path if the type specified by the user input does not match the type determined based on the first physical property value in the third operating mode.

13. The image forming apparatus according to any one of claims 10 to 12, wherein the control means notifies the user of an abnormality regarding the type of the third recording material when the type specified by the user input does not match the type determined based on the first physical property value.

14. The image forming apparatus according to claim 2, further comprising: a post-processing means for applying post-processing to a recording material on which an image has been formed by the image forming means, wherein the control means controls the application of the post-processing to the second recording material by the post-processing means in the second operating mode based on the second characteristic data registered in the database.

Images