Image forming device

Abstract

To provide an image forming device with a mode that can reduce variations in sheet detection results.SOLUTION: A control unit 400 determines sheet information based on results of detection of a plurality of sheets by a media sensor 100 in a sheet determination mode.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to an apparatus for forming an image on a sheet. [Background technology]

[0002] In recent years, electrophotographic image forming apparatuses have been provided with a media sensor for determining the type of sheet, and the media sensor detects the physical properties of the sheet using an optical sensor or the like.

[0003] Patent Document 1 describes an apparatus having a sheet determination mode in which a media sensor detects one conveyed sheet, and a CPU determines information about the sheet based on the detection result of the media sensor. The CPU sets image formation conditions corresponding to the determined sheet information. Patent Document 1 also describes a sheet determination mode in which sheet information is determined, but image formation is not performed on the sheet detected by the media sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-26815 Summary of the Invention [Problem to be solved by the invention]

[0005] In the device of Patent Document 1, when performing sheet determination in a sheet determination mode in which image formation is not performed, the CPU performs sheet determination based on the detection of one sheet by the media sensor. If the media sensor only detects one sheet, there is a risk that the detection results of the sheet will vary due to individual sheet variations, and there is a risk that the sheet determination results will be unstable.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus having a mode capable of reducing variation in the detection results of a sheet. [Means for solving the problem]

[0007] The present invention is characterized in that it has a conveying unit that conveys a sheet, a sheet detection unit that detects physical properties of the sheet conveyed by the conveying unit, an image forming unit that forms an image on the sheet, and a control unit that executes an image formation operation that causes the image forming unit to form an image on the sheet conveyed by the conveying unit, and a sheet determination mode that causes the sheet conveyed by the conveying unit to be detected by the sheet detection unit and determines sheet information based on the result of the detection of the sheet by the sheet detection unit, while not causing the image forming unit to form an image on the sheet, and the control unit executes, as the sheet determination mode, a first mode that determines sheet information based on the result of detection of a single sheet by the sheet detection unit, and a second mode that determines sheet information based on the result of detection of multiple sheets by the sheet detection unit. Effect of the Invention

[0008] The present invention has a mode in which the sheet determination mode determines sheet information based on the results of detection of a plurality of sheets, and this mode can reduce variation in the sheet detection results. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows an image forming apparatus. [Diagram 2] Control block diagram [Diagram 3] FIG. 13 is a diagram showing how the sheets are separated in the fixing unit. [Figure 4] View of the media sensor in a direction perpendicular to the sheet transport direction [Diagram 5] Media sensor viewed in the sheet transport direction [Figure 6] Image showing how a line sensor reads data [Figure 7] Permeability coefficient vs. basis weight relationship [Figure 8] An example of the detection result for sheet F [Figure 9] Display diagram (image formation mode setting) [Figure 10] Flowchart of image formation mode setting [Figure 11] Diagram showing the superficiality classification matrix [Figure 12] FIG. 1 is a diagram showing image forming modes corresponding to a range of basis weights and types of sheets. [Figure 13] FIG. 13 is a diagram showing an example of a display (notification result of image formation mode candidates) [Figure 14] Flowchart for detecting multiple sheets [Figure 15] A diagram showing the multiple sheet detection area table [Figure 16] An example of what is displayed on the display (detection mode setting screen) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An image forming apparatus according to an embodiment of the present invention will be described with reference to Fig. 1. In the following description, "basis weight" refers to the mass per unit area of ​​a sheet and is expressed in [g / m^2].

[0011] (Image forming device) FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 201. As shown in FIG.

[0012] The image forming apparatus 201 is a tandem type intermediate transfer type laser beam printer that utilizes an electrophotographic process. The image forming apparatus 201 inputs image data output from a host device 501 (FIG. 2). The image forming apparatus 201 can then form an image on a sheet P, which is a recording medium, based on the input image data.

[0013] FIG. 2 shows a control block diagram. The control unit 400 is a control unit that controls the overall operation of the image forming apparatus 201, and exchanges information with a host device 501 and a display 502. The memory 401 stores the control program according to this embodiment and initial values ​​of various settings. The memory 401 also stores an image forming mode database 402. The control unit 400 is connected to the media sensor 100 and the image forming unit 201B. The control unit 400 is connected to a conveying unit 600 for conveying a sheet, the media sensor 100, and a sheet detection sensor 270. The control unit 400 is connected to a sensor 601 other than the media sensor 100 and the sheet detection sensor 270. The media sensor 100 has an information processing unit 160, an ultrasonic sensor (sheet detection unit) 120, and an optical sensor (sheet detection unit) 150. The information processing unit 160 is connected to the ultrasonic sensor 120, the optical sensor 150, and the sheet detection sensor 270. The information processing unit 160 has an internal memory Z 1601. The media sensor 100 will be described in detail later.

[0014] A display (operation unit) 502 is a touch panel that displays various information and accepts user instructions by a touch panel function. A control unit 400 executes a control program stored in a memory 401 to control an image forming operation.

[0015] 1, the image reading device 202 is installed on the image forming apparatus main body 201A. A discharge space S for discharging sheets is formed between the image reading device 202 and the image forming apparatus main body 201A. The image reading device 202 is connected to a control unit 400. In this embodiment, the image reading device 202 is configured as a part of the image forming apparatus 201, but is not limited to this and may be configured as a device separate from the image forming apparatus 201.

[0016] The cassette feeding section 230 has a feeding cassette 1 that stores sheets P. The cassette feeding section 230 has a pickup roller 2 for picking up the sheets P stored in the feeding cassette 1. The cassette feeding section 230 has a feed roller 3 and a retard roller 4 for separating the sheets P sent out from the pickup roller 2. The manual feeding section 235 has a manual feeding tray 5 that is a means for holding the sheets P. The manual feeding section 235 has a pickup roller 278 for picking up the sheets P placed on the manual feeding tray 5. The manual feeding section 235 has a feed roller 279 and a retard roller 280 for separating the sheets P sent out from the pickup roller 278.

[0017] The media sensor 100 is installed on the conveying path between the feed roller 279 and the pull-out roller 290. The media sensor 100 detects the physical properties of the sheet P picked up by the pickup roller 278 and conveyed by the feed roller 279. In this embodiment, the media sensor 100 is disposed in the position shown in Fig. 1, but is not limited to this. For example, the media sensor 100 may be provided on the conveying path between the pair of registration rollers 240 and the feed roller 3, and the media sensor 100 may detect the sheet fed from the cassette feeding unit 230.

[0018] The image forming section 201B has a laser scanner 210 and four image forming units 211 that form toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K). Here, each image forming unit 211 has a photoconductor drum 212, a charger 213, and a developing unit 214. The image forming section 201B has a secondary transfer section 201D and a fixing section 201E disposed above the image forming units 211. A toner cartridge 215 supplies toner to the developing units 214.

[0019] The secondary transfer unit 201D has a drive roller 216a, a tension roller 216b, and a transfer belt 216 wound around the drive roller 216a and the tension roller 216b. The secondary transfer unit 201D has a primary transfer roller 219 that contacts the transfer belt 216 at a position facing the photosensitive drum 212 on the inside of the transfer belt 216. The transfer belt 216 is rotated in the direction of the arrow by the drive roller 216a. The secondary transfer unit 201D also has a secondary transfer roller 217. The secondary transfer roller 217 is provided at a position facing the drive roller 216a.

[0020] A fixing unit 201E is disposed downstream in the transport direction of the secondary transfer roller 217. The fixing unit 201E includes a pressure roller 220a and a heating roller 220b.

[0021] A first discharge roller pair 225a and a second discharge roller pair 225b are disposed downstream of the fixing unit 201E in the conveying direction. A double-sided reversing unit 201F is disposed downstream of the first discharge roller pair 225a and the second discharge roller pair 225b. The double-sided reversing unit 201F has a reversing roller pair 222 that reverses a sheet P having an image formed on one side thereof, and a re-conveying path R that is a conveying path for conveying the reversed sheet P again to the image forming unit 201B.

[0022] The conveying unit 600 includes a pickup roller 278, a feed roller 279, a retard roller 280, a pull-out roller 290, a pickup roller 2, a feed roller 3, a retard roller 4, and a motor for driving them. The conveying unit 600 includes a pair of registration rollers 240 and a motor for driving them. The conveying unit 600 includes a motor for driving the secondary transfer roller 217, a motor for driving the pressure roller 220a, and a motor for driving the heating roller 220b. The conveying unit 600 includes a first pair of discharge rollers 225a, a second pair of discharge rollers 225b, a pair of reversing rollers 222, other rollers for conveying a sheet in the image forming apparatus 201, and a motor for driving them.

[0023] A display 502 that receives operations from a user is provided on the upper portion of the image forming apparatus 201. This display 502 is configured as a part of the image forming apparatus 201, but is not limited to this. For example, the display 502 may be configured as a device separate from the image forming apparatus 201 and electrically connected to the control unit 400 of the image forming apparatus 201.

[0024] (Image forming job of the image forming device) Next, the image forming operation of the image forming apparatus 201 will be described. First, when the control unit 400 receives an instruction to start the image forming operation from the host device 501, which is an external device, the control unit 400 starts an image forming job. The instruction to start the image forming operation may be input to the control unit 400 by the user operating the display 502. Note that the image forming job refers to a series of operations from when the instruction to start the image forming operation is received until the image forming operation is performed and the sheet is discharged to the stacking unit 223. After receiving the instruction to start the image forming operation, the control unit 400 performs image processing on the received image data. The control unit 400 drives the laser scanner 210 based on the image data. The laser scanner 210 sequentially exposes the surface of the photoconductor drum 212, the surface of which is uniformly charged to a predetermined polarity and potential by the charger 213, with a laser to form an electrostatic latent image. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on each photoconductor drum 212.

[0025] The developing device 214 develops the electrostatic latent image with toner of each color to form a toner image. The toner images of each color are transferred to the transfer belt 216 in order, superimposed on each other, by a primary transfer bias applied to the primary transfer roller 219. As a result, a toner image is formed on the transfer belt 216. In parallel with the formation of the toner image, the sheet P is fed from the cassette feeding section 230 and conveyed to the pair of registration rollers 240. The pair of registration rollers 240 corrects the skew of the sheet P. The pair of registration rollers 240 conveys the sheet P to the secondary transfer section 201D. Then, the secondary transfer section 201D transfers the toner image on the transfer belt 216 onto the sheet P by a secondary transfer bias applied to the secondary transfer roller 217. The sheet P to which the toner image has been transferred is conveyed to the fixing section 201E. Fixing section 201E applies heat and pressure to the toner image on sheet P in a roller nip formed by pressure roller 220a and heating roller 220b, thereby fixing the toner image to sheet P. At this time, the adhesive force of the molten toner causes sheet P to stick to heating roller 220b. If sheet P is weak in stiffness, it will be taken up by rotating heating roller 220b as it is, so a separation plate 221 for separating sheet P is provided downstream of heating roller 220b (FIG. 3a). If separation plate 221 was not provided, sheet P would be taken up by rotating heating roller 220b as it is, as shown in FIG. 3b.

[0026] The first discharge roller pair 225a or the second discharge roller pair 225b provided downstream of the fixing unit 201E discharges the sheet P with the fixed image to the discharge space S. As a result, the sheet P is stacked on the stacking unit 223 provided on the bottom surface of the discharge space S. When images are formed on both sides of the sheet P, the sheet P with the image formed on one side is transported to the re-conveyance path R by the reversing roller pair 222. Then, the sheet P is transported again to the image forming unit 201B, where an image is formed on the other side. Thereafter, the sheet P is discharged to the discharge space S by the first discharge roller pair 225a or the second discharge roller pair 225b. This completes the image forming job by the image forming apparatus 201. This image forming operation is performed based on the set image forming mode.

[0027] An image forming mode is a predetermined image forming condition (for example, a transfer voltage value of secondary transfer unit 201D, a target temperature of fixing unit 201E, a conveying speed in fixing unit 201E, etc.). The image forming modes are given names such as "Thin Paper 1", "Thin Paper 2", "Plain Paper 1", "Coated Paper 1", "Coated Paper 2", "Coated Paper 3", etc., which are shown in FIG. 12 to be described later. In this embodiment, the names shown in FIG. 12 such as "Thin Paper 1", "Thin Paper 2", "Plain Paper 1", "Coated Paper 1", "Coated Paper 2", "Coated Paper 3", etc. are included in the information corresponding to the names of the image forming modes.

[0028] The optimal image formation mode differs depending on the physical properties (basis weight, surface properties) of the sheet on which the image is formed. Since the surface properties of a sheet differ depending on the type of sheet, there is a correlation between the surface properties of a sheet and the type of sheet. Therefore, in order to appropriately set the image formation mode, it is important to know the basis weight and type of the sheet to be used before the image formation operation. In this embodiment, the basis weight and type of the sheet are determined based on the detection result of the media sensor 100.

[0029] (Media sensor configuration) 2, the media sensor 100 has an ultrasonic sensor 120, an optical sensor 150, and an information processing unit 160. The information processing unit 160 issues detection instructions to the ultrasonic sensor 120 and the optical sensor and processes the detection results of the ultrasonic sensor 120 and the optical sensor. The sheet detection sensor 270 is a sensor that detects the presence or absence of a sheet, and the optical sensor 150, which is electrically connected to the media sensor 100, is a contact image sensor (CIS).

[0030] The configuration of the media sensor 100 will be described with reference to Figs. 4 and 5. Fig. 4 is a view of the media sensor 100 as viewed in a direction perpendicular to the sheet conveying direction. Fig. 5 is a view of the media sensor 100 as viewed in the sheet conveying direction. As shown in Fig. 4, the media sensor 100 is installed on the conveying path between the feed roller 279 and the pull-out roller 290. The sheet detection sensor 270 is disposed upstream of the media sensor 100 and downstream of the feed roller 279 in the sheet conveying direction. As shown in Fig. 5, the media sensor 100 has an ultrasonic sensor 120 and an optical sensor 150. The ultrasonic sensor 120 has an ultrasonic transmitter 130 and an ultrasonic receiver 131. The optical sensor 150 has a light source 1501 (LED) and a line sensor 1502. When detecting a sheet by the optical sensor 150 and when detecting a sheet by ultrasonic waves, it is necessary to reduce fluttering of the conveyed sheet P and stabilize the posture of the sheet P. In order to reduce the fluttering of the sheet P and stabilize the posture of the sheet P, a sheet pressing roller 260 and a sheet pressing roller 261 are provided between the feed roller 279 and the pull-out roller 290. The sheet pressing roller 260 is located opposite the optical sensor 150 and is configured to press the sheet P against the optical sensor 150. This reduces the fluttering of the sheet P and stabilizes the posture of the sheet P when the optical sensor 150 measures the surface of the sheet P located in the detectable area where the optical sensor 150 can detect it. The sheet pressing roller 261 is configured to press the sheet P against the lower block 109. The detectable area where the ultrasonic sensor 120 can detect the sheet P is located between the sheet pressing roller 260 and the sheet pressing roller 261 in the sheet width direction perpendicular to the sheet conveying direction. This reduces the fluttering of the sheet P and stabilizes the posture of the sheet P when the ultrasonic sensor 120 measures the sheet P. In addition, the ultrasonic transmitter 130 is not shown in Fig. 4 because it is located so as to be hidden behind the sheet pressure roller 260. Also, in Fig. 4, the sheet pressure roller 261 is not shown in Fig. 4 because it is located so as to be hidden behind the sheet pressure roller 260.

[0031] (Acquisition of basis weight) The basis weight of the sheet is obtained based on the detection result of the ultrasonic sensor 120.

[0032] As shown in FIG. 5, the ultrasonic transmitter 130 is disposed on the upper block 110 side, and the ultrasonic receiver 131 is disposed on the lower block 109 side, so as to sandwich the transport path along which the sheet P is transported.

[0033] Both the ultrasonic transmitter 130 and the ultrasonic receiver 131 are composed of a piezoelectric element (also called a piezo element) which is an element for mutual conversion between mechanical displacement and an electric signal, and an electrode terminal. When a pulse voltage of a predetermined frequency is input to the electrode terminal of the ultrasonic transmitter 130, the piezoelectric element of the ultrasonic transmitter 130 oscillates and transmits ultrasonic waves. The transmitted ultrasonic waves are then propagated to the ultrasonic receiver 131 through the sheet P. The piezoelectric element of the ultrasonic receiver 131 receives the ultrasonic waves propagated through the sheet P, and generates an output voltage corresponding to the amplitude of the received ultrasonic waves at the electrode terminal of the ultrasonic receiver 131. The ratio of the output voltage when there is no sheet between the ultrasonic transmitter 130 and the ultrasonic receiver 131 to the output voltage when there is a sheet between the ultrasonic transmitter 130 and the ultrasonic receiver 131 is the transmittance (transmission coefficient). The ultrasonic waves transmitted from the ultrasonic transmitter 130 are attenuated by passing through the sheet P, and the ultrasonic receiver 131 receives the attenuated ultrasonic waves. Since the degree of ultrasonic attenuation varies depending on the basis weight of the sheet, the transmittance also varies depending on the basis weight of the sheet. The basis weight of the sheet can be estimated by using the transmittance and the ultrasonic transmission coefficient-sheet basis weight conversion formula.

[0034] In this embodiment, the basis weight is determined using the detection result of the ultrasonic sensor 120, but this is not limiting. For example, the sheet may be sandwiched between a first roller fixed in the thickness direction of the sheet and a second roller movable according to the thickness of the sheet, and the basis weight may be determined based on the amount of movement of the second roller.

[0035] (Acquisition of superficiality) The surface property of the sheet is acquired based on the detection result of the optical sensor 150 .

[0036] As described in the configuration of the media sensor 100 , the optical sensor 150 includes a light source 1501 and a line sensor 1502 .

[0037] Light emitted by a light source (LED) 1501 is refracted by a line guide (not shown) and then strikes the sheet P at a certain angle. The light reflected from the sheet P is then received by a line sensor 1502 via a lens (not shown). This allows the line sensor 1502 to read the light reflected from the sheet P as an image. FIG. 6(a) is a conceptual diagram of reading by the line sensor 1502. As shown in FIG. 6(a), the image sensor 1502a of the line sensor 1502 has image sensors arranged at a pitch of 300 dpi in a direction perpendicular to the sheet conveying direction. The image sensor 1502a of the line sensor 1502 can capture an image of 400 pixels (A1, A2, A3,...A400) in a direction perpendicular to the sheet conveying direction in one capture.

[0038] The CIS can only detect one line of image in one scan, but the detection result of one line does not provide enough information to determine the surface property of the sheet. This is because if the surface property is determined based on only the image of one line within a sheet surface, the output results vary greatly for each detection position. To solve this problem, the line sensor 1502 captures multiple lines of the sheet P being conveyed.

[0039] The adjacent pixel difference integrated value is a value obtained by adding up the results of integrating the brightness difference for each adjacent pixel of the line sensor 1502 for the number of lines, and is an index expressing the unevenness of the sheet. In FIG. 6(b), each pixel is numbered 1 to n, the detection lines are also named A to n in the order of the detection lines, and the detection value of each pixel is the detection line name + pixel number. In this case, the adjacent pixel difference integrated value Y is expressed by the following formula (1) using the adjacent pixel difference integrated value k for each line. Note that the detection pixel data direction in FIG. 6(b) is the arrangement direction of the image pickup elements 1502a of the line sensor 1502. Also, the detection line direction in FIG. 6(b) is the sheet conveyance direction. kA=(A2−A1)+(A3−A2)···+(An−An−1) kB=(B2-B1)+(B3-B2)...+(Bn-Bn-1) · · · km=(m2−m1)+(m3−m2)···+(mn−mn−1) Y = kA + kB + km (1)

[0040] The total luminance value is obtained by adding up the total luminance values ​​of the pixels received by the line sensor 1502 for the number of detected lines, and represents the brightness of the sheet. The total luminance value M is expressed by the following formula (2). M=A1+A2+···B1+B2+···G1+G2+····+mn(2)

[0041] A highly transparent film made of resin such as PET reflects less light from the light source 1501, and so the measured brightness sum value is low. Also, in a sheet whose surface is intentionally given a geometrically uneven shape, such as embossed paper, the unevenness increases the brightness difference between adjacent pixels, so the adjacent pixel difference integrated value is large. Recycled paper also has an uneven grain direction, and the pulp fibers become shorter after going through several recycling processes, so the surface roughness increases, and the adjacent pixel difference integrated value tends to be large. Conversely, coated paper has fewer unevenness due to the coating layer on the surface, so the adjacent pixel difference integrated value tends to be small.

[0042] In this embodiment, the surface property is determined using the adjacent pixel difference integrated value, but the method is not limited to this. For example, the surface property may be determined based on the detection results of the first light receiving unit that detects the diffuse reflection light from the sheet and the second light receiving unit that detects the regular reflection light from the sheet by the irradiation unit. Generally, the reflection characteristic of a sheet with low glossiness is complete diffusion, while the reflection characteristic of a sheet with high glossiness is a mixture of regular reflection and diffusion. The surface property can be detected by utilizing the fact that the reflection characteristic differs depending on the surface property of the sheet.

[0043] In the present embodiment, the transparency is determined using the reflected light from the sheet, but the present invention is not limited to this. For example, the transparency may be determined based on the detection result of the light receiving unit that detects the light transmitted through the sheet by irradiating the surface of the sheet with light.

[0044] (Processing in the information processing section) The information processing unit 160 issues detection instructions to the ultrasonic sensor 120 and the optical sensor 150 and processes the detection results of the ultrasonic sensor 120 and the optical sensor 150.

[0045] When the information processing unit 160 receives a sheet detection command from the control unit 400, it starts a detection sequence. First, the information processing unit 160 performs initialization processing of the ultrasonic sensor 120 and the optical sensor 150 in preparation for sheet detection. In the initialization processing, the information processing unit 160 calls and sets initial setting values ​​stored in the memory Z1601. After that, the information processing unit 160 causes the ultrasonic sensor 120 to perform ultrasonic detection in a state where there is no sheet in a detectable area where the ultrasonic sensor 120 can detect a sheet. Then, the information processing unit 160 stores in the memory Z1601 the result of the output voltage A generated by the ultrasonic sensor 120 in a state where there is no sheet in the detectable area. Then, in response to the sheet detection sensor 270 detecting the conveyed sheet, the information processing unit 160 causes the ultrasonic sensor 120 to perform ultrasonic detection of the sheet that has entered the detectable area of ​​the ultrasonic sensor 120. The information processing unit 160 stores in the memory Z1601 the result of the output voltage B generated by the ultrasonic sensor 120, and calculates the transmittance based on the output voltage A and the output voltage B.

[0046] Furthermore, in response to the sheet detection sensor 270 detecting the conveyed sheet, the information processing unit 160 causes the optical sensor 150 to detect the luminance value of the sheet that has entered the detectable area of ​​the optical sensor 150. Then, the information processing unit 160 stores the output value (luminance value) of each pixel by the optical sensor 150 in the memory Z1601. Thereafter, the information processing unit 160 processes the output value by the optical sensor 150, and saves the luminance sum value and the adjacent pixel difference integrated value in the memory Z1601 in the information processing unit 160.

[0047] The information processing unit 160 converts the detection result of the ultrasonic sensor 120 into basis weight, and stores the basis weight in memory Z1601 in the information processing unit 160. To convert from ultrasonic transmittance to basis weight, the transmittance (transmission coefficient) is calculated from the detection result when there is no sheet and the detection result when there is a sheet, and the basis weight is calculated using the ultrasonic transmission coefficient-sheet basis weight conversion formula corresponding to the diagram shown in FIG.

[0048] When the information processing unit 160 calculates the basis weight, it determines that all measurements have been completed, and transmits to the control unit 400 the basis weight, the adjacent pixel difference integrated value, and the luminance sum value.

[0049] (Individual differences in sheets) FIG. 8 shows an example of sheet F in which the detection results of the basis weight and the surface property vary due to various factors.

[0050] For the same sheet F, if a detection value of 1 is obtained, plain paper 1 is recommended in determining the image formation mode described below, and if a detection value of 2 is obtained, plain paper 2 is recommended.

[0051] From the user's perspective, it is desirable for the same recommendation results to be obtained when the same sheet is detected.

[0052] This variation in detection results occurs due to individual differences in sheets. For example, in FIG. 8, detection values ​​1, 3, 4, 5, and 6 are located in the plain paper 1 area where plain paper 1 is selected as the image formation mode. Also, in FIG. 8, detection values ​​2 and 7 are located in the plain paper 2 area where plain paper 2 is selected as the image formation mode. As can be seen from FIG. 8, considering the range of variation in the detection results for sheet F, it is highly likely that plain paper 1 would be better selected as the image formation mode. It is possible to reduce variation in judgment due to individual differences in sheets by detecting multiple sheets and making a judgment, rather than judging the image formation mode based on the detection value of a single sheet.

[0053] (Sheet Judgment Mode) FIG. 9 is a diagram showing a sheet manual setting mode key 700 displayed on the display 502. The sheet manual setting mode key 700 is a key for the user to select the sheet manual setting mode. Furthermore, FIG. 9 is a diagram showing a sheet determination mode key 701 for performing sheet determination based on the media sensor 100 displayed on the display 502. The sheet determination mode key 701 is a key for the user to select the sheet determination mode. The user can select either the sheet manual setting mode or the sheet determination mode from the state shown in FIG. 9. The sheet manual setting mode is a mode in which the user manually selects the sheet type and the basis weight range. The user can manually set the sheet. When the sheet type and the basis weight range are selected by the user in the sheet manual setting mode, the control unit 400 sets an image formation mode corresponding to the selected sheet type and basis weight range. The image formation mode corresponding to the sheet type and the basis weight range is stored in the image formation mode database 402. The sheet determination mode is a mode in which the control unit 400 determines the sheet type and the basis weight range based on the detection result of the sheet by the media sensor 100.

[0054] 9 by performing a predetermined operation on the display 502. In response to the user's touch operation of the key 702, the control unit 400 returns the screen of the display 502 to, for example, the home screen. This allows the user to return the screen of the display 502 to the home screen by performing a touch operation on the key 702.

[0055] Fig. 10 is a flowchart of an operation executed by the control unit 400 in response to a user touching the sheet determination mode key 701 shown in Fig. 9. The flowchart in Fig. 10 will be described.

[0056] 10 in response to the sheet determination mode key 701 being touched by the user, the control unit 400 starts the flow of FIG. 10 and proceeds to S101. In S101, the control unit 400 instructs the information processing unit 160 to detect a sheet. The control unit 400 causes the conveying unit 600 to start conveying one sheet from the manual feed unit 235 (S102). The control unit 400 monitors whether or not detection data has been received from the information processing unit 160 (S103), and if it has been received (Yes in S103), proceeds to S104, and if it has not been received (No in S103), continues to monitor reception.

[0057] In S103, when the adjacent pixel difference integrated value, the luminance sum value, and the basis weight are transmitted from the information processing unit 160 to the control unit 400, the control unit 400 stores the transmitted information in the memory 401 and proceeds to S104. Note that after the sheet, which has started to be conveyed in S102, is detected by the media sensor 100, it is discharged by the conveying unit 600 to the stacking unit 223 without an image being formed thereon.

[0058] In S104, the control unit 400 determines whether the data last transmitted from the information processing unit 160 in S103 is for the first sheet or not, and if it is determined that it is data for the first sheet (Yes in S104), the process proceeds to S105. In S104, the control unit 400 determines whether the data last transmitted from the information processing unit 160 in S103 is for the first sheet or not, and if it is determined that it is not data for the first sheet (No in S104), the process proceeds to S107. The data for the first sheet is data from the first sheet detection process.

[0059] In S105, the control unit 400 executes a multiple sheet detection determination process as described in the flowchart of Fig. 14 below, and proceeds to S106. In S106, if the multiple sheet detection mode is set in S105 (Yes in S106), the control unit 400 proceeds to S107, and if the single sheet detection mode is set in S105 (No in S106), the control unit 400 proceeds to S109.

[0060] In S107, the control unit 400 determines whether the data last transmitted from the information processing unit 160 is for the fourth sheet, and if it is determined that the data is not for the fourth sheet (No in S107), the process proceeds to S102. Then, in S102, the control unit 400 causes the conveying unit 600 to start conveying one sheet from the manual feed unit 235. In S107, the control unit 400 determines whether the data last transmitted from the information processing unit 160 is for the fourth sheet, and if it is determined that the data is for the fourth sheet (Yes in S107), the process proceeds to S108. The fourth sheet data is data from the fourth sheet detection process.

[0061] In S108, the control unit 400 calculates the average value of the adjacent pixel difference integrated values ​​for the four sheets stored in the memory 401, and stores this average value in the memory 401. In S108, the control unit 400 calculates the average value of the luminance sum values ​​for the four sheets stored in the memory 401, and stores this average value in the memory 401. In S108, the control unit 400 calculates the average value of the basis weights for the four sheets stored in the memory 401, and stores this average value in the memory 401. After storing the average value of the adjacent pixel difference integrated values, the average value of the luminance sum values, and the average basis weight in the memory 401, the control unit 400 proceeds to S109.

[0062] In S109, in the case of the single sheet detection mode, the control unit 400 determines the sheet type using the data for one sheet (adjacent pixel difference integrated value and brightness summation value) stored in the memory 401 and the data corresponding to the matrix in Fig. 11. In S109, in the case of the multiple sheet detection mode, the control unit 400 determines the sheet type using the data for one sheet (average of adjacent pixel difference integrated values ​​and average of brightness summation value) stored in the memory 401 and the data corresponding to the matrix in Fig. 11.

[0063] In the matrix of Fig. 11, the vertical axis is the adjacent pixel difference integrated value, and the horizontal axis is the luminance sum value. Based on the adjacent pixel difference integrated value and the luminance sum value stored in the memory 401, the control unit 400 determines which of "transparent film", "second original", "coated paper", "plain paper", "recycled paper", and "embossed paper" the sheet belongs to. Information corresponding to the matrix of Fig. 11 is information determined in advance by experiments or the like, and this information is stored in the memory 401. Note that the memory 401 also stores threshold values ​​(luminance sum values ​​a0 to a3, adjacent pixel difference integrated values ​​b0 to b4) for the control unit 400 to make a determination. After the control unit 400 executes the determination of the type of sheet, the process proceeds to S110.

[0064] In S110, in the case of the single sheet detection mode, the control unit 400 judges the basis weight range using the data (basis weight) of one sheet stored in the memory 401 and the information of FIG. 12. In S110, in the case of the multiple sheet detection mode, the control unit 400 judges the basis weight range using the data (average basis weight) of the sheet stored in the memory 401 and the information of FIG. 12. In S110, the control unit 400 judges which basis weight range the basis weight stored in the memory 401 corresponds to among the multiple basis weight ranges shown in FIG. 12. The information of FIG. 12 is predetermined information, and this information is stored in the memory 401. The threshold values ​​of the basis weight range are indicated by c1 to c23, and the respective values ​​are stored in the memory 401. FIG. 12 shows the relationship between the basis weight and the type of sheet and the image formation mode name corresponding to the image formation mode. Here, "plain paper", "coated paper", "recycled paper" and "embossed paper" in Fig. 12 are associated with adjacent pixel difference integrated values ​​and brightness sum values ​​as in Fig. 11. That is, in this embodiment, adjacent pixel difference integrated values, brightness sum values ​​and basis weights are associated with image formation modes. After determining the basis weight range, the control 400 proceeds to S111.

[0065] In S111, the control unit 400 causes the display 502 to display a screen as shown in Fig. 13. Fig. 13 is an example in which image forming mode candidates 900 determined by the control unit 400 are displayed on the display 502. In the example of Fig. 13, four "sheet type, basis weight range, image forming mode" are displayed as the candidates 900, and "plain paper, 64-75 [g / m^2], plain paper 1" is displayed as recommended. After the control unit 400 causes the display 502 to display the image forming mode candidates 900, the process proceeds to S112. In S111, the control unit 400 causes the display 502 to display "recommended" based on the sheet type determination result in S109 and the basis weight range determination in S110. Furthermore, in S111, the control unit 400 causes the display 502 to display, as candidates, plain paper having a basis weight range (60-63 [g / m^2]) smaller than the determined basis weight range (64-75 [g / m^2]). Furthermore, in S111, the control unit 400 causes the display 502 to display, as candidates, plain paper having a basis weight range (76-90 [g / m^2]) larger than the determined basis weight range (64-75 [g / m^2]). In the present embodiment, an example has been shown in which the control unit 400 causes the display 502 to display multiple candidates in S111, but this is not limiting. For example, in S111, the control unit 400 may cause the display 502 to display only "recommended" candidates.

[0066] In S112, the control unit 400 sets the image formation mode as the image formation mode during image formation in response to the user touching one of the candidates 900 on the screen as shown in FIG. 13 (Yes in S112). In this embodiment, the user touching any one of the fields of the candidates 900 also means that the sheet is set. In S112, if the user has not performed a touch operation (No in S112), the control unit 400 continues monitoring in S112 (monitoring the touch operation). When the control unit 400 sets the image formation mode in S113, it ends the process of the flowchart in FIG. 10. In response to receiving an instruction to start the image formation operation, the control unit 400 can cause the image forming unit 201B to perform the image formation operation on the sheet in the set image formation mode.

[0067] In addition, in the example of the display result in FIG. 13, an example in which the sheet type (sheet information), the basis weight range (sheet information), and the name of the image formation mode (sheet information) are displayed has been shown, but the present invention is not limited to this. For example, the items to be displayed may be the sheet type and the basis weight range, and the name of the image formation mode may not be displayed. Also, for example, the items to be displayed may be the name of the image formation mode, and the sheet type and the basis weight range may not be displayed. Also, for example, the items to be displayed may be the sheet type, and the basis weight range and the name of the image formation mode may not be displayed. Also, for example, the items to be displayed may be the basis weight range, and the sheet type and the name of the image formation mode may not be displayed.

[0068] Depending on the sheet, the control unit 400 of this embodiment can suppress variations in judgment due to variations in detection results caused by individual differences in the sheet by using the average value of the four pieces of data to judge the sheet.

[0069] The flowchart in Fig. 14 will be described. Fig. 14 shows a flowchart for the control unit 400 to determine whether or not it is better to detect multiple sheets by the media sensor 100 when the control unit 400 discriminates sheets. When the control unit 400 proceeds to S105 in the flowchart in Fig. 10, it starts a multiple sheet detection determination. Then, the control unit 400 proceeds to S201, and determines whether or not the detection data of the first sheet is in the multiple sheet area based on the multiple sheet detection area table stored in the memory 401 and the detection data corresponding to the first sheet.

[0070] The multiple sheet detection area table is a table shown in FIG. 15, and is a table for the control unit 400 to check whether the detection data corresponding to the first sheet stored in the memory 401 is within the range shown in the table. The detection data corresponding to the first sheet is the information of the first sheet corresponding to the adjacent pixel difference integrated value, the information of the first sheet corresponding to the brightness sum value, and the information of the first sheet corresponding to the basis weight. The multiple sheet detection area 1 in FIG. 15 corresponds to the multiple sheet detection area 1a1 shown in FIG. 11. The multiple sheet detection area 2 in FIG. 15 corresponds to the multiple sheet detection area 2a2 shown in FIG. 11. The multiple sheet detection area 3 in FIG. 15 corresponds to the multiple sheet detection area 3b3 shown in FIG. 11. The multiple sheet detection area 4 in FIG. 15 corresponds to the multiple sheet detection area 4b2 shown in FIG. 11. The multiple sheet detection area 5 in FIG. 15 corresponds to the multiple sheet detection area 5b1 shown in FIG. The multiple sheet detection area 6 in FIG. 15 corresponds to the multiple sheet detection area 6u1, which is the area surrounded by the dashed line shown in FIG. 12. Multiple sheet detection region 7 in Fig. 15 corresponds to multiple sheet detection region 7u2, which is an area surrounded by a dashed line in Fig. 12. Multiple sheet detection region 8 in Fig. 15 corresponds to multiple sheet detection region 8u3, which is an area surrounded by a dashed line in Fig. 12. Multiple sheet detection regions 1 to 8 are regions that include an area in the positive direction of the threshold value when control unit 400 determines the image formation mode, and an area in the negative direction of the threshold value when control unit 400 determines the image formation mode. Sheets whose detection results fall within the ranges of multiple sheet detection regions 1 to 8 are sheets that are likely to have different determination results depending on sheet variations.

[0071] In S202, the control unit 400 determines whether the first detection data is within at least one of the multiple areas 1 to 8. If it is not within the multiple areas (No in S202), the control unit 400 proceeds to S203. If it is within the multiple areas (Yes in S202), the control unit 400 proceeds to S204.

[0072] In S203, the control unit 400 sets the one sheet detection mode, and ends the process of the flowchart in FIG.

[0073] In S204, the control unit 400 displays the screen of FIG. 16 on the display 502 and proceeds to S205. FIG. 16 is a screen for informing the user that "selecting multiple sheet detection may improve image quality." This can encourage the user to perform multiple sheet detection. The user can select by touching the screen of FIG. 16 whether to have the image forming apparatus 201 perform sheet determination with one sheet or to have the image forming apparatus 201 perform sheet determination with four sheets. When the control unit 400 displays the screen of FIG. 16 on the display 502, the control unit 400 proceeds to S205. In this embodiment, the control unit 400 displays a notification recommending multiple sheet detection on the display 502 in S204 in the flowchart of FIG. 14, but this is not limited to this. For example, if the result of S202 is Yes, the control unit 400 may proceed to S207 without issuing the notification in S204 and execute the multiple sheet detection mode. In this case, there is an advantage that the user does not need to perform an operation to set the detection mode (single sheet detection mode, multiple sheet detection mode).

[0074] In S205, the control unit 400 monitors whether or not the user has selected either the single sheet detection mode key 800 or the multiple sheet detection mode key 801 while the screen of Fig. 16 is being displayed on the display 502. If a mode has been selected by the user in S205, the control unit 400 proceeds to S206, and if not, continues monitoring.

[0075] In S206, if the user touches the multiple sheet detection mode key 801, the control unit 400 proceeds to S207 to set the multiple sheet detection mode, and ends the processing of the flowchart in Fig. 14. Also, in S206, if the user touches the single sheet detection mode key 800, the control unit 400 proceeds to S203 to set the single sheet detection mode, and ends the processing of the flowchart in Fig. 14.

[0076] It is possible to reduce variations in judgment due to individual differences in sheets by detecting and determining the image formation mode based on the detection value of a single sheet rather than by detecting and determining the image formation mode based on the detection value of a plurality of sheets.

[0077] On the other hand, when multiple sheets are always conveyed and multiple sheets are detected, there is a problem that the sheets cannot be judged until a predetermined number of sheets is reached. In addition, when multiple sheets are always conveyed and multiple sheets are detected, there is a problem that the detected multiple sheets are wasted. Therefore, by making it possible to switch between judging the sheet based on the detection result of one sheet and judging the sheet based on the detection result of multiple sheets based on the detection result of the first sheet, there are two advantages. The first advantage is that the sheet can be judged quickly for sheets whose judgment results are unlikely to vary. The second advantage is that the number of sheets that are wasted can be reduced for sheets whose judgment results are unlikely to vary. In addition, the user can select whether to set the single sheet detection mode or the multiple sheet detection mode when the screen of FIG. 16 is displayed on the display 502. This allows the user to prioritize reducing the number of sheets used for detection even when prompted to use the multiple sheet detection mode.

[0078] In the present embodiment, in the multiple detection mode, the control unit 400 causes the media sensor 100 to detect four sheets, but this is not limited to the present embodiment. The control unit 400 may also cause the media sensor 100 to detect two or more sheets in the multiple detection mode. Also, the number of sheets in the multiple detection mode may be changeable by a user operation, and the control unit 400 may cause the media sensor 100 to detect the changed number of sheets.

[0079] In this embodiment, when the detection result of one sheet by the media sensor 100 falls within the multiple sheet detection area, the control unit 400 uses the detection result of one sheet and displays candidate sheets on the display 502, but this is not limited to the above. The number of sheets to be detected in the sheet determination mode may be changed by the user. In this case, the user may be able to set one sheet as the set number, and may also set multiple sheets. In this case, for example, when the screen of FIG. 9 is displayed on the display 502, the control unit 400 may cause the media sensor 100 to detect the set number of sheets in response to the user's touch operation of the introduction key B701.

[0080] The above-described media sensor 100 is an example of an embodiment, and does not limit the present invention. In the present configuration, the media sensor 100 is located inside the image forming apparatus main body 201A, but the media sensor 100 may be located outside the image forming apparatus main body 201A. For example, in a configuration in which the media sensor 100 has an insertion port into which a sheet is inserted by a user, the media sensor 100 may detect the sheet when the user inserts the sheet into the insertion port by hand. The method of determining the sheet based on the detection process result of the media sensor 100 arranged outside the image forming apparatus main body 201A is performed in the same manner as the flowchart of FIG. 10. In this configuration, the media sensor 100 performs a first sheet detection process in response to the user's insertion operation into the insertion port. Then, the control unit 400 may cause the display 502 to issue a notification to prompt the user to detect the second sheet based on the result of the first sheet detection process. In other words, the control unit 400 may cause the display 502 to issue a notification to prompt the user to enter the multiple detection mode based on the result of the first sheet detection process.

[0081] The sheet detection process is a process executed by the media sensor 100 from when a user inserts a sheet into the insertion slot until the user removes the sheet from the insertion slot. Incidentally, detection of whether or not a sheet has been inserted into the insertion slot may be performed by the media sensor 100, or may be performed by a sensor different from the media sensor 100. In response to the user's insertion operation into the insertion slot, the media sensor 100 executes detection process for another sheet (second and subsequent sheet detection processes), and the control unit 400 judges the sheet based on the results of the detection processes performed multiple times. In this case, the sheet judgment mode is from when the media sensor 100 starts the first sheet detection process until when the final sheet detection process is completed and the control unit 400 displays the sheet information on the display 502. Incidentally, when the control unit 400 judges the sheet by one sheet detection process, the sheet judgment mode is as follows. The sheet judgment mode is from when the media sensor 100 starts one sheet detection process until when the one sheet detection process is completed and the control unit 400 displays the sheet information on the display 502.

[0082] In a configuration in which the media sensor 100 has an insertion port through which a sheet is inserted by the user, the number of times a sheet is detected in the multiple detection mode may be changed by a user operation, and the control unit 400 may cause the media sensor 100 to execute the sheet detection process the changed number of times. Also, the user may be allowed to change the setting of the number of times the sheet detection process is to be performed in the sheet determination mode. In this case, the number of times the sheet detection process can be performed by the user may be set to one time, or multiple times.

[0083] In addition, in this embodiment, the image forming mode database 402 is included in the memory 401, but this is not limited to the above. For example, the media sensor 100 may be provided with a database, and the media sensor 100 may determine the type of sheet.

[0084] Furthermore, although an example has been shown in which the image formation mode is determined by determining the sheet type and basis weight from the characteristics of the sheet detected by the media sensor 100, the present invention is not limited to this. For example, the media sensor 100 may be another sheet physical property measuring device, and the image formation mode may be determined directly from the detected characteristics of the sheet. [Explanation of symbols]

[0085] 100 Media Sensor 130 Ultrasonic Transmitter 131 Ultrasonic receiver 120 Ultrasonic Sensor 150 Optical Sensor 1501 Light source 1502 Line sensor 160 Information Processing Section 201 Image forming device 235 Manual feed section 260, 261 Sheet holding roller 270 Sheet detection sensor 279 Feed Roller 290 Pull-out roller 400 Control section 401 Memory 402 Image Formation Mode Database 502 Display

Claims

1. A conveying unit that conveys a sheet; a sheet detection unit that detects a physical property of the sheet conveyed by the conveying unit; an image forming unit that forms an image on a sheet; a control unit that executes an image forming operation in which an image is formed by the image forming unit on the sheet conveyed by the conveying unit, and a sheet determination mode in which the sheet conveyed by the conveying unit is detected by the sheet detection unit, sheet information is determined based on a result of the detection of the sheet by the sheet detection unit, and an image is not formed on the sheet by the image forming unit; having The control unit executes, as the sheet determination mode, a first mode in which sheet information is determined based on a result of detection of one sheet by the sheet detection unit, and a second mode in which sheet information is determined based on a result of detection of a plurality of sheets by the sheet detection unit.

1. An image forming apparatus comprising:

2. the control unit determines whether or not to cause the sheet detection unit to detect a second sheet based on a result of the detection of a first sheet by the sheet detection unit.

2. The image forming apparatus according to claim 1,

3. the control unit determines whether or not to cause a display to display a key for causing the sheet detection unit to detect a second sheet based on a result of the detection of a first sheet by the sheet detection unit.

2. The image forming apparatus according to claim 1,

4. In response to the key being operated by a user, the conveying unit starts conveying a second sheet, and the sheet detection unit detects the second sheet conveyed by the conveying unit.

4. The image forming apparatus according to claim 3.

5. The sheet detection unit has an ultrasonic sensor.

2. The image forming apparatus according to claim 1,

6. The sheet detection unit has an optical sensor.

2. The image forming apparatus according to claim 1,

7. a sheet detection unit that detects physical properties of a sheet inserted by a user through a sheet insertion port; a control unit that executes a sheet determination mode in which sheet information is determined based on a result of a sheet detection process performed by the sheet detection unit; having the sheet detection unit executes the detection process for the sheet from when a user inserts the sheet into the insertion opening until when the user removes the sheet from the insertion opening; The control unit executes, as the sheet determination mode, a first mode in which sheet information is determined based on a result of the detection process of the sheet performed once by the sheet detection unit, and a second mode in which sheet information is determined based on a result of the detection process of the sheet performed multiple times by the sheet detection unit.

1. An image forming apparatus comprising:

8. The control unit determines whether to display a notification on a display to prompt the sheet detection unit to perform a second sheet detection process based on a result of the first sheet detection process performed by the sheet detection unit.

8. The image forming apparatus according to claim 7,

Images