Image formation device

Abstract

To easily set a suitable threshold value by making it possible to change the threshold value while checking the determination result of the sheet information based on the change of the threshold value.SOLUTION: If a control unit 400 determines sheet information based on the detection result of a media sensor 100 and the threshold value is changed after a display 502 displays the determined sheet information, the control unit 400 determines sheet information based on the detection result and the changed threshold value, and the display 502 displays the sheet information.SELECTED DRAWING: Figure 18

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 are equipped with a media sensor to determine the type of sheet. The media sensor detects the physical properties of the sheet using an optical sensor or the like. The image forming apparatus determines the sheet type based on the detection result by the media sensor from the sheet information registered in advance.

[0003] The sheet type is determined based on the detection result of the media sensor and a determination table. The threshold value in the determination table is set in advance in the image forming apparatus. However, for sheets for which the detection result of the media sensor is close to the threshold value, the determination result may vary.

[0004] Therefore, for users who use sheets for which the determination based on the media sensor varies when a normal threshold is used, a device has been proposed that allows the user to change the basis weight threshold of the image forming device (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-33214 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the device of Patent Document 1, if the user changes the basis weight threshold after feeding a sheet and executing a determination by the media sensor, the user needs to feed the sheet again to execute the sheet determination based on the changed threshold, which is troublesome for the user.

[0007] The present invention makes it possible to easily set an appropriate threshold value by making it possible to change the threshold value while checking the determination result of the sheet information based on the change in the threshold value. [Means for solving the problem]

[0008] The present invention comprises an image forming unit that forms an image on a sheet, a sheet detection unit that detects physical properties of the sheet, a control unit that determines sheet information based on the detection result of the sheet detection unit and a threshold value, and an operation unit that displays the sheet information determined by the control unit and accepts a user instruction indicating a change to the threshold value, and is characterized in that when the operation unit accepts a user instruction indicating a change to the threshold value, the control unit determines the sheet information based on the detection result and the changed threshold value, and the operation unit displays the sheet information. Effect of the Invention

[0009] The present invention makes it possible to easily set an appropriate threshold value by making it possible to change the threshold value while checking the determination result of the sheet information based on the change in the threshold value. [Brief description of the drawings]

[0010] [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] A diagram showing the relationship between the detection result of sheet F and the image formation mode. [Figure 9]Display diagram (image formation mode setting) [Figure 10] Flowchart of measurement control of media sensor [Figure 11] Flowchart of image formation mode determination [Figure 12] Diagram showing the superficiality classification matrix [Figure 13] FIG. 1 is a diagram showing image forming modes corresponding to a range of basis weights and types of sheets. [Figure 14] A diagram showing an example of the display (display results of image formation mode candidates) [Figure 15] A diagram showing an example of the display (screen showing image formation mode candidates selected) [Figure 16] An example of the display (threshold change introduction screen) [Figure 17] Example of the display (threshold change screen) [Figure 18] Example of the display (threshold change screen) [Figure 19] A diagram showing the relationship between the detection result of sheet F and the image formation mode. [Figure 20] A diagram showing an example of the display (display results of image formation mode candidates) [Figure 21] A diagram showing an example of the display (screen showing image formation mode candidates selected) [Figure 22] Example of the display (threshold change screen) [Figure 23] Example of the display (threshold change screen) [Figure 24] Example of the display (threshold change screen) [Diagram 25] A diagram showing an example of the display (display results of image formation mode candidates) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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].

[0012] (Image forming device) FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 201. As shown in FIG.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] (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.

[0026] 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.

[0027] 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.

[0028] 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. 13 to be described later. In this embodiment, the names shown in FIG. 13 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.

[0029] 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.

[0030] (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).

[0031] 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.

[0032] (Acquisition of basis weight) The basis weight of the sheet is obtained based on the detection result of the ultrasonic sensor 120.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] (Acquisition of superficiality) The surface property of the sheet is acquired based on the detection result of the optical sensor 150 .

[0037] As described in the configuration of the media sensor 100 , the optical sensor 150 includes a light source 1501 and a line sensor 1502 .

[0038] 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.

[0039] 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.

[0040] 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) 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 the basis weight, the adjacent pixel difference integrated value, and the luminance sum to the control unit 400. As will be described later, the control unit 400 determines the type of sheet based on the adjacent pixel difference integrated value, the luminance sum, and a table corresponding to the matrix in FIG.

[0049] (Assumed range of variation in sheets) FIG. 8 is a diagram showing the relationship between the result of detection of sheet F by media sensor 100, the expected range of variation in the result, and the threshold value of basis weight.

[0050] The expected variation range indicates the range in which the detection value varies, taking into account factors such as sheet variation, variation in the detection value by the sensor, environmental influences, etc. The expected variation range is calculated using formulas (formulas (3) and (4)) set based on experimental results. Expected variation range Xa = detected value of sheet F (basis weight) × (1 ± expected variation value of basis weight) (3) Expected variation range Ya = Measurement value of sheet F (adjacent pixel difference integrated value) × (1 ± expected variation value of adjacent pixel difference integrated value) (4) Equations (3) and (4) are stored in the memory 401, and the control unit 400 can calculate the expected variation range of the sheet based on the detection result of the media sensor 100.

[0051] 8 shows a case in which most of the expected variation range of sheet F is located in the plain paper 1 area, so the control unit 400 recommends the plain paper 1 image formation mode. However, due to the variation factors described above, the detection result by the media sensor 100 may end up being located in the plain paper 2 area. In this case, the control unit 400 recommends the plain paper 2 image formation mode over the plain paper 1 image formation mode.

[0052] The determination of the image formation mode based on the detection result of the media sensor 100 may be used by the user to check whether the sheet detected by the media sensor 100 has been correctly determined. In this case, if the user knows in advance that the image formation mode for sheet F will never be plain paper 2, it is better for the user to determine that the recommended image formation mode for sheet F is always plain paper 1. In this embodiment, a user who knows that the image formation mode for sheet F will never be plain paper 2 can set a threshold value so that the recommended image formation mode for sheet F is always plain paper 1.

[0053] (Manual sheet setting mode and 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. FIG. 9 is also 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, 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] The user can call up the setting screen shown in FIG.

[0055] In response to a 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.

[0056] (Image formation mode setting sequence) The image formation mode setting sequence will be described with reference to FIG.

[0057] Fig. 10 is a flowchart executed by the control unit 400 when the user touches the sheet determination mode key 701 while the screen of Fig. 9 is displayed on the display 502. The following explanation of the flowchart will be given for the case where the sheet to be detected is the sheet F shown in Fig. 8.

[0058] In response to a user touching the sheet determination mode key 701, the control unit 400 instructs the information processing unit 160 to execute sheet detection (S101).

[0059] The control unit 400 causes the conveying unit 600 to start conveying one sheet F from the manual feed unit 235 (S102).

[0060] The control unit 400 monitors whether detection data related to sheet F has been received from the information processing unit 160 (S103), and if it has been received (Yes in S103), stores the detection data of sheet F in the memory 401 and proceeds to step S104, and if it has not been received (No in S103), continues checking for reception. The detection data stored in the memory 401 are the adjacent pixel difference integrated value, the brightness sum value, and the basis weight. The sheet that has started to be conveyed in S102 is detected by the media sensor 100 and then discharged to the stacking unit 223 by the conveying unit 600.

[0061] The control unit 400 determines the image forming mode for the sheet F, the detection data of which is stored in the memory 401 in S104. Fig. 11 is a flowchart of the process (image forming mode determination) of S104 in Fig. 10. The flowchart in Fig. 11 will be described.

[0062] The control unit 400 executes the process of S201 when the adjacent pixel difference integrated value, the luminance sum, and the basis weight are transmitted from the information processing unit 160. In S201, the control unit 400 calculates an expected variation range Ya based on the adjacent pixel difference integrated value transmitted from the information processing unit 160. Then, the control unit 400 determines the type of the sheet based on the expected variation range Ya, the luminance sum, and a table corresponding to the matrix in FIG.

[0063] In the matrix of Fig. 12, the vertical axis is the adjacent pixel difference integrated value, and the horizontal axis is the luminance sum value. Based on the expected variation range Ya and the luminance sum value, 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. 12 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 has determined the type of sheet, the process proceeds to S202.

[0064] In S202, the control unit 400 calculates the expected variation range Xa based on the basis weight transmitted from the information processing unit 160. The control unit 400 determines which basis weight range the expected variation range Xa falls into among the multiple basis weight ranges shown in FIG. 13. The information in FIG. 13 is predetermined information, and this information is stored in the memory 401. The thresholds of the basis weight ranges are indicated by c1 to c23, and the respective values ​​are stored in the memory 401. FIG. 13 shows the relationship between the information corresponding to the basis weight and the information corresponding to the type of sheet, and the image formation mode name corresponding to the image formation mode. Here, the "plain paper", "coated paper", "recycled paper", and "embossed paper" in FIG. 13 are associated with the adjacent pixel difference integrated value and the brightness sum value as in FIG. 12. That is, in this embodiment, the adjacent pixel difference integrated value, the brightness sum value, and the basis weight are associated with the image formation mode. After executing the basis weight range determination, the control unit 400 proceeds to S203.

[0065] In S203, the control unit 400 determines an image formation mode based on the sheet type determined in S201, the basis weight range determined in S202, and the information in FIG. 13. The image formation modes are stored in the image formation mode database 402. As shown in FIG. 13, the image formation modes include "thin paper 1-2," "plain paper 1-3," "heavy paper 1-7," "coated paper 1-3," "recycled paper 1-3," and "embossed paper 1-8." When the control unit 400 determines the image formation mode in S203, it ends the processing of the flowchart in FIG. 11. When the control unit 400 determines the image formation mode, it proceeds to S105.

[0066] In S105, the control unit 400 causes the display 502 to display a determination result 704 of the image forming mode corresponding to the sheet F detected by the media sensor 100. In this way, the control unit 400 notifies the user of the determination result 704. FIG. 14 is an example of a notification screen that the control unit 400 causes the display 502 to display in S105. FIG. 14 is an example of a display in which a plurality of image forming mode candidates are displayed on the display as the determination result 704 in S105. In S105, the control unit 400 causes the display 502 to display the sheet type (sheet information, type information) and basis weight range (sheet information, basis weight information) together with the name of the image forming mode (sheet information). After causing the display 502 to display the screen shown in FIG. 14, the control unit 400 proceeds to S106.

[0067] The determination result 704 in FIG. 14 is a determination result when the detection data for sheet F received by the control unit 400 in S103 is the sheet F detection value shown in FIG. 8. The determination rate included in the determination result 704 in FIG. 14 is a determination rate when the expected variation range of the detected sheet F is the range shown in FIG. 8. The determination rate is expressed as a ratio of an area where the expected variation range overlaps with an area of ​​a certain image forming mode to an area of ​​the expected variation range. For example, in FIG. 8, when the basis weight range of plain paper 1 is 64 to 75 [g / m^2], the area where the image forming mode area of ​​plain paper 1 overlaps with the expected variation range area of ​​sheet F is 80% of the expected variation area of ​​sheet F. Therefore, when the basis weight range of the image forming mode of plain paper 1 is 64 to 75 [g / m^2], the sheet F in FIG. 14 indicates that there is an 80% probability that an image should be formed in the image forming mode of plain paper 1. Further, in the case of the screen of FIG. 14, the image forming mode determined to be recommended by the control unit 400 is plain paper 1. In the present embodiment, the criteria for the control unit 400 to determine the recommended image forming mode are that the discrimination rate is 70% or more and that the discrimination rate is the highest among the candidate image forming modes, but are not limited thereto. For example, the criteria for the control unit 400 to determine the recommended image forming mode may be that the discrimination rate is 60% or more. In the present embodiment, the criteria for the discrimination rate for the image forming mode candidate by the control unit 400 is that the discrimination rate is 15% or more, but are not limited thereto. For example, the criteria for the discrimination rate for the image forming mode candidate by the control unit 400 may be that the discrimination rate is 20% or more. Note that, with respect to the display example of FIG. 14, the control unit 400 displays the multiple image forming modes in a top-down order of high discrimination rates in the display of the multiple image forming modes. In the present embodiment, the control unit 400 displays the multiple image forming modes in a top-down order of high discrimination rates in the display of the multiple image forming modes, but are not limited thereto. For example, in a display of a plurality of image forming modes, the plurality of image forming modes may be displayed in order from the left in descending order of the discrimination rate. Also, in a display of a plurality of image forming modes, the plurality of image forming modes may be displayed in order at random regardless of the discrimination rate.However, displaying a plurality of image forming modes in order of decreasing discrimination rate has the effect of improving visibility for the user compared to displaying a plurality of image forming modes in order of decreasing discrimination rate.

[0068] The user can select an image forming mode by selecting one of the candidates 704 by touch operation. FIG. 15 is a diagram of a display example showing that the control unit 400 displays the horizontal row of plain paper 1 columns in color and displays an OK key A707 in response to the user touching the column of plain paper 1 as the image forming mode. In a state where a screen such as that of FIG. 15 is displayed on the display 502, in response to the user touching the OK key A707 (Yes in S106), the control unit 400 proceeds to S109. In S109, the control unit 400 sets the image forming mode selected by the user in S106 as the image forming mode for image formation, and ends the processing of the flowchart. In this embodiment, the setting of the image forming mode performed by the control unit 400 in S109 is also the setting of the sheet. In response to the user touching the cancel key 706, the control unit 400 ends the flow of FIG. 10 midway and returns the screen of the display 502 to, for example, the home screen. This allows the user to touch the cancel key 706 to end the sheet determination mode midway and return the screen of the display 502 to the home screen.

[0069] In S106, if the OK key A707 is not touched (No in S106), the control unit 400 proceeds to S107. In S107, if the user has not touched the basis weight threshold change key 710 or the sheet type threshold change key 712, the control unit 400 proceeds to S106. The control unit 400 repeats the transition between S106 and S107 until the user operates the OK key A707, the basis weight threshold change key 710, or the sheet type threshold change key 712.

[0070] When the user touches the threshold change key 705 while the display is displaying the screen of FIG. 14 or FIG. 15, the control unit 400 displays the screen of FIG. 16 on the display 502. FIG. 16 shows a display example in which a rounded rectangular key for changing the threshold setting is displayed in the field of the image formation mode candidate 708. The user can change the basis weight threshold and the sheet type threshold used when the control unit 400 judges the image formation mode candidate by operating the rounded rectangular key. The user can change the threshold of the operated part by touching the rounded rectangular key shown in FIG. 16. In FIG. 16, the key labeled "plain paper" surrounded by a double-lined rounded rectangular is a key for the user to change the threshold when the control unit 400 judges the sheet type. The reason why the key labeled "plain paper" in FIG. 16 is displayed with double lines is to make it easier for the user to recognize that the sheet type for the two image formation mode candidates (plain paper 1 and plain paper 2) is the same. The double line on the keys indicates that when the user selects either the key labeled "plain paper" and changes the threshold, the other threshold will change accordingly. In FIG. 16, the double line on the keys labeled "75" and "76" among the numeric values ​​in the basis weight range indicates that when the user selects either the key labeled "75" or "76" and changes the threshold, the other threshold will change accordingly.

[0071] Fig. 17 is an example of a screen displayed by the control unit 400 on the display 502 in response to the user touching the "75" key on the screen of Fig. 16. As shown in Fig. 17, the control unit 400 displays the "75" and "76" keys in color and also displays the basis weight threshold change key 710. In the screen of Fig. 17, "75" and "76" are adjacent numbers among the basis weight range values, and therefore have a relationship with each other. Therefore, even if the user touches the "76" key, the control unit 400 causes the display 502 to display the same screen as Fig. 17.

[0072] When the screen of FIG. 17 is displayed on the display 502, the control unit 400 transitions to S108 in response to the user touching the "+" key of the basis weight threshold change key 710 as the operation unit three times (Yes in S107). In S108, the control unit 400 causes the display 502 to display the screen of FIG. 18. The screen of FIG. 18 indicates that the basis weight threshold display has been changed from 0 to 3 by the "+" key being touched three times. The threshold value "0" indicates that the threshold value is the same as the reference value stored in the memory 401. The control unit 400 executes the determination of the image formation mode and the determination of the discrimination rate based on the expected variation range corresponding to the detection data (detection data of sheet F) stored in the memory 401 and the changed threshold value. FIG. 18 is a display example showing that the basis weight threshold display of the basis weight threshold change key 710 has been changed from 0 to 3 by the user's operation, and therefore the image formation mode candidate 708 is displayed as only plain paper 1. This means that, as shown in FIG. 19(a), when the expected basis weight range of the sheet on which an image is formed in the image forming mode of plain paper 1 is 64 to 78 [g / m^2], the expected variation range of sheet F is entirely included in the plain paper 1 area. The control unit 400 displays the image forming mode of plain paper 1 with a discrimination rate of 100% as shown in the diagram of FIG. 18. On the other hand, in FIG. 19(a), the expected variation range of sheet F does not overlap with the plain paper 2 area. Therefore, as shown in the diagram of FIG. 18, the control unit 400 does not display plain paper 2, which is an image forming mode with a discrimination rate of less than 15%. This allows the user to check how the image forming mode corresponding to sheet F is determined as a result of changing the basis weight threshold. In addition, the user can check the determination result of sheet F without taking the trouble of having the media sensor 100 detect the sheet again after changing the threshold. In addition, the user can check how the discrimination rate of the image forming mode corresponding to sheet F is determined as a result of changing the basis weight threshold. Furthermore, by having the control unit 400 display both the basis weight threshold change key 710 and the candidates 708 as the judgment results on the display 502, the user can check the judgment results while changing the threshold, which is an advantage for the user.

[0073] In response to the user touching the OK key B711 on the screen of FIG. 18, the control unit 400 causes the display 502 to display the screen of FIG. 20. FIG. 20 is an example of an image formation mode candidate displayed on the display 502. In response to the user touching the plain paper 1 column of the determination result 704 on the screen of FIG. 20, the control unit 400 displays the plain paper 1 column in color as in the screen of FIG. 21. FIG. 21 is an example of a screen when the image formation mode candidate displayed on the display 502 is selected by the user. Furthermore, the control unit 400 causes the OK key A707 to be displayed. In the state of the screen of FIG. 21, in response to the user touching the OK key A707 (Yes in S106), the control unit 400 sets the selected image formation mode (S109) and ends the processing of the flowchart.

[0074] 10 in the middle of the process and returns the screen of the display 502 to, for example, the home screen, in response to the user's touch operation of the cancel key 709. This allows the user to end the sheet determination mode and return the screen of the display 502 to the home screen by touching the cancel key 709.

[0075] When the screen of FIG. 14 or FIG. 15 is displayed on the display 502, the user can touch the threshold change key 705 to display the screen of FIG. 16 on the display 502. The user can also change the threshold of the sheet type by operating the screen of FIG. 16. In this embodiment, the thresholds of the sheet types are b0, b1, b2, b3, and b4 in FIG. 12. When the user touches the rounded rectangular key of "plain paper" displayed in the candidate 708 column while the screen of FIG. 16 is displayed on the display 502, the control unit 400 displays the screen of FIG. 22 on the display 502. FIG. 22 is an example of a screen when the threshold change screen is displayed on the display 502. When the user touches the "+" key displayed in the "sheet type (upper limit)" column of the sheet type threshold change key 712 as the operation unit twice while the screen of FIG. 22 is displayed on the display 502, the control unit 400 displays the screen of FIG. 23 on the display 502.

[0076] Fig. 23 is an example of a screen when a threshold change screen is displayed on the display 502. Fig. 23 shows that the upper limit of the threshold for plain paper has increased by 2. However, even if the upper limit threshold for plain paper has increased by 2, there is no change in the result of the determination of the sheet type for sheet F by the control unit 400, so the sheet type remains as plain paper on the screen in Fig. 23.

[0077] 17 is displayed on the display 502, if the user touches the "-" key displayed in the column for basis weight threshold change key 710 three times, the control unit 400 causes the display 502 to display the screen of FIG. 24. FIG. 24 is an example of a screen when the threshold change screen is displayed on the display 502. The screen of FIG. 24 indicates that the basis weight threshold display has been changed from 0 to -3 as a result of the user touching the "-" key three times. FIG. 24 indicates that the discrimination rate for plain paper 1 (image formation mode) and plain paper 2 (image formation mode) has become 50% as a result of the user's manipulation of the basis weight threshold.

[0078] When the expected basis weight of the sheet on which an image is formed in the image formation mode of plain paper 1 becomes 64 to 72 g / m^2 by changing the threshold value, 50% of the expected variation range of sheet F in Fig. 19(b) is included in the plain paper 1 area. As a result, the discrimination rate of plain paper 1 in the image formation mode and plain paper 2 in the image formation mode is displayed as 50% on the screen in Fig. 24.

[0079] When the screen of Fig. 24 is displayed on the display 502, if the user touches the OK key B711, the control unit 400 causes the display 502 to display the screen of Fig. 25. Fig. 25 is an example in which candidates for image formation modes are displayed on the display 502. From the screen state of Fig. 25, the user can select one image formation mode from the determination result 704 column.

[0080] In addition, although the examples of the display results in FIGS. 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, and 25 show examples in which the sheet type, basis weight range, and image formation mode name are displayed, the present invention is not limited to this.

[0081] For example, the items to be displayed may be the type of sheet and the range of basis weight, and the name of the image forming mode may not be displayed.

[0082] Also, for example, the item to be displayed may be the type of sheet, and the range of basis weight and the name of the image forming mode may not be displayed.

[0083] Also, for example, the items to be displayed may be the range of basis weight, and the sheet type and the name of the image forming mode may not be displayed.

[0084] Also, for example, the items to be displayed may be the names of the image forming modes, and the sheet types and basis weight ranges may not be displayed.

[0085] As described above, this embodiment allows the user to set appropriate parameters for threshold setting by providing a function for changing the threshold for sheet determination processing by the media sensor 100 and a function for displaying the discrimination rate after changing the threshold. Furthermore, this embodiment eliminates the need for the user to have the media sensor detect the sheet again after changing the threshold, reducing the burden on the user.

[0086] Regarding the change of the basis weight threshold, in this embodiment, the user can change the threshold of the part selected by the user, but this is not limited to this. It is also possible to change all of the multiple thresholds to the positive or negative side.

[0087] In the above description, the user can change the threshold value of the portion selected by the user for changing the sheet type threshold value, but this is not limited to this. It is also possible to change all of the multiple threshold values ​​to the positive or negative side.

[0088] Regarding the change of the threshold value, in this embodiment, the control unit 400 causes the display 502 to display a screen for changing the threshold value when the media sensor 100 detects a sheet, but this is not limiting. In addition to the method of changing the threshold value in this embodiment, the control unit 400 may display a threshold value change screen on the display 502 in response to a user operation and accept a change of the threshold value by the user.

[0089] Although the image forming mode name, sheet type, and basis weight range are displayed as the judgment result based on the sheet detection result by the media sensor 100, the present invention is not limited to this. Other information related to physical properties that can be detected by the media sensor may be displayed as the judgment result. For example, the basis weight value (e.g., 77 [g / m^2]) may be displayed instead of the basis weight range.

[0090] The above-described media sensor 100 is an example of an embodiment, and is not limited thereto. In the above description, an example in which the media sensor 100 is inside the image forming apparatus main body 201A has been described, but is not limited thereto. For example, the media sensor 100 may be located outside the image forming apparatus main body 201A. In this case, the media sensor 100 has an insertion port for a user to insert a sheet by hand, and is configured so that when the user inserts a sheet into this insertion port, the media sensor 100 detects the sheet. Then, based on the detection result of the media sensor 100, the control unit 400 judges the sheet. Also, in this embodiment, the memory 401 has the image forming mode database 402, but is not limited thereto. For example, the media sensor 100 may have a database, and the media sensor 100 may judge the sheet.

[0091] 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 physical properties 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 feature amount of the sheet. [Explanation of symbols]

[0092] 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. an image forming unit that forms an image on a sheet; A sheet detection unit that detects the physical properties of a sheet; a control unit that determines sheet information based on a detection result of the sheet detection unit and a threshold value; an operation unit that displays the sheet information determined by the control unit and receives a user instruction to change the threshold value; When the operation unit receives a user instruction indicating a change of the threshold value, the control unit determines sheet information based on the detection result and the changed threshold value, and the operation unit displays the sheet information.

1. An image forming apparatus comprising:

2. The sheet information includes a discrimination rate.

2. The image forming apparatus according to claim 1,

3. the operation unit displays both a key for changing the threshold value and sheet information; 2. The image forming apparatus according to claim 1,

4. When displaying two or more candidates of sheet information, the operation unit displays them in order of high discrimination rate.

3. The image forming apparatus according to claim 2,

5. The sheet information includes sheet type information.

2. The image forming apparatus according to claim 1,

6. The sheet information includes basis weight information.

2. The image forming apparatus according to claim 1,

7. The sheet information includes sheet type information and basis weight information.

2. The image forming apparatus according to claim 1,

8. The sheet detection unit has an ultrasonic sensor.

2. The image forming apparatus according to claim 1,

9. The sheet detection unit has an optical sensor.

2. The image forming apparatus according to claim 1,

Images