Paper type determination device, image forming system, and paper type determination program

Abstract

To accurately determine whether a paper is synthetic or general.SOLUTION: A detection device (paper type determination device) 20 determines whether a paper (job target paper) is synthetic paper or not, based on the detection result of a moisture sensor (moisture content sensor 234) that detects characteristic information (moisture content) corresponding to the moisture level of the paper.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a paper type determination device, an image forming system, and a paper type determination program. [Background technology]

[0002] Conventionally, a sensor device has been disclosed that determines the type and characteristics of paper based on the paper's optical properties (the ratio of the signal level of surface specular reflection light to the signal level of internal diffuse reflection light) and electrical properties (volume resistivity) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-44929 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the sensor device disclosed in Patent Document 1, as shown in Figure 7, the resistance value of ordinary paper (paper made primarily from pulp fiber) in a low humidity environment becomes as high as that of synthetic paper, which can lead to errors in distinguishing between synthetic paper and ordinary paper. In the example of Figure 7, 2 , 300g / m 2 , 160g / m 2 , 85g / m 2 The papers correspond to the above-mentioned general papers, and synthetic paper A and synthetic paper B correspond to the above-mentioned synthetic papers.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to accurately distinguish between synthetic paper and ordinary paper. [Means for solving the problem]

[0006] In order to solve the above problem, the paper type determination device according to claim 1 comprises: In a paper type determination device for determining a paper type, Whether or not the paper is synthetic paper is determined based on the detection result of a moisture sensor that detects characteristic information corresponding to the moisture content of the paper.

[0007] The invention described in claim 2 is the paper type determination device described in claim 1, Furthermore, it is determined whether the paper is synthetic paper or not based on the detection result of the thickness sensor that detects the thickness of the paper and the detection result of the moisture sensor.

[0008] The invention described in claim 3 is the paper type determination device described in claim 1, Furthermore, it is determined whether the paper is synthetic paper or not based on the detection result of the basis weight sensor that detects the basis weight of the paper and the detection result of the moisture sensor.

[0009] The invention described in claim 4 is the paper type determination device described in claim 2, Based on the detection result of the thickness sensor, a threshold value used to determine whether the paper is synthetic paper or not is determined.

[0010] The invention described in claim 5 is the paper type determination device described in claim 4, If the detection result of the moisture sensor is higher than the threshold value, the paper is determined to be non-synthetic paper containing a sheet made of pulp fiber, and if the detection result is lower than the threshold value, the paper is determined to be synthetic paper made of resin.

[0011] The invention described in claim 6 is the paper type determination device described in claim 4, It has a threshold value table in which the input is the thickness of the paper and the output is the threshold value.

[0012] The invention described in claim 7 is the paper type determination device described in claim 4, The threshold value is determined by the following calculation formula. Threshold = Paper thickness x 1st constant + 2nd constant

[0013] The invention described in claim 8 is the paper type determination device described in claim 1, Furthermore, based on the detection result of characteristic information corresponding to the transmittance of light irradiated onto the paper, it is determined whether or not the paper is a transparent sheet.

[0014] The invention described in claim 9 is an image forming system including the paper type determination device described in any one of claims 1 to 8, Based on the result of the paper type determination by the paper type determination device, the secondary transfer current applied to the paper in the image forming section is changed.

[0015] The invention described in claim 10 is an image forming system including the paper type determination device described in any one of claims 1 to 8, Based on the result of the paper type determination by the paper type determination device, the fixing temperature for fixing the toner onto the paper in the image forming section is changed.

[0016] The paper type determination program according to claim 11, A paper type determination program for determining a paper type, Computer, a determining means for determining whether the paper is synthetic paper or not based on the detection result of a moisture sensor that detects characteristic information corresponding to the moisture content of the paper; Function as. [Effects of the Invention]

[0017] According to the present invention, synthetic paper and general paper can be accurately distinguished. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming system according to an embodiment of the present invention; [Figure 2] 1 is a block diagram showing a main functional configuration of an image forming system according to an embodiment of the present invention; [Figure 3] 10 is a flowchart showing the flow of a process condition setting process. [Figure 4] 10 is a flowchart showing the flow of a paper type determination process. [Figure 5] 10 is a graph showing an example of a second threshold value (threshold value for determining synthetic paper). [Figure 6] 10 is a graph showing another example of the second threshold value (threshold value for determining synthetic paper). [Figure 7] 10 is a graph showing the relationship between environmental humidity and resistance value for ordinary paper and synthetic paper. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming system according to the present invention will now be described with reference to the accompanying drawings.

[0020] [1. Image formation system configuration] Fig. 1 is a diagram showing a schematic configuration of an image forming system 100 according to this embodiment. Fig. 2 is a block diagram showing the main functional configuration of the image forming system 100.

[0021] The image forming system 100 according to this embodiment includes a paper feeder 10, a detection device 20 which is a media detection device (paper type determination device), and an image forming device 30. In the image forming system 100, a paper feeder 10, a detector 20, and an image forming device 30 are arranged in this order from the upstream side along the paper transport direction.

[0022] [1-1. Paper feeder configuration] The paper feed device 10 includes a paper feed control unit 11, a transport unit 12, a paper feed unit 13, and the like. The paper feed control unit 11 is connected to the transport unit 12 and the paper feed unit 13 via a bus 14 .

[0023] The paper feed control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU of the paper feed control unit 11 reads out a program stored in the ROM, loads it into the RAM, and controls each part of the paper feed device 10 in accordance with the loaded program. For example, the paper feed control unit 11 transports paper from one of the paper feed trays of the paper feed unit 13 to the detection device 20 depending on the job.

[0024] The conveying unit 12 conveys the paper through a conveying path that connects the paper feed unit 13 to the detection device 20 . The paper feed unit 13 has paper feed trays that store paper sheets of predetermined paper types and sizes. Here, paper sheets refer to print media that can be used for image formation in the image forming system 100 of this embodiment, and include different types of print media such as plain paper (general paper), synthetic paper, transparent sheets, metallized paper, and colored paper (colored paper).

[0025] [1-2. Structure of the detection device] The detector 20 is provided on the upstream side of the image forming device 30 in the sheet transport direction, and detects the sheet transported from the sheet feeding device 10. The detection device 20 includes a detection control unit 21, a transport unit 22, a first detection unit 23, a second detection unit 24, and a storage unit 25. The detection control unit 21 is connected to the transport unit 22, the first detection unit 23, the second detection unit 24, and the storage unit 25 via a bus .

[0026] The detection control unit 21 includes a CPU, a ROM, and a RAM. The CPU of the detection control unit 21 reads out a program stored in the ROM, loads it into the RAM, and controls each part of the detection device 20 in accordance with the loaded program. For example, the detection control unit 21 controls the first detection unit 23 and the second detection unit 24 to detect the paper conveyed from the paper feeder 10, or controls the first detection unit 23 to detect it only.

[0027] The transport unit 22 includes a first transport path 221, a second transport path 222, a purge tray 229 for discharging sheets to be purged, and the like. The first and second transport paths 221 and 222 each include a plurality of pairs of transport rollers arranged along the transport path, and a drive motor (not shown) for driving these pairs of transport rollers. The first transport path 221 is a main transport path, and its upstream side is connected to the transport path of the paper feeder 10, and its downstream side is connected to the transport path of the image forming device 30. The second transport path 222 branches off from the first transport path 221 at a branching point BP. The second transport path 222 transports sheets to be purged to the purge tray 229 without passing through the image forming unit 38. The first transport path 221 extends in a substantially horizontal direction. At least a portion of the second transport path 222 extends in a substantially vertical direction. In particular, in the area where the stiffness sensor 241 (described later) is located, the second transport path 222 extends in a substantially vertical direction, with the paper transport direction being upward. Here, substantially vertical means being within a range of 90±1°. The second transport path 222 does not have to be entirely straight. As long as at least the measurement area of the stiffness sensor 241 of the second transport path 222 is straight, the other paths may be partially curved. For example, the second transport path 222 may be a transport path that is curved in an S-shape overall.

[0028] The first detection unit 23 is disposed on the first transport path 221 and uses the first transport path 221 as a detection area to detect the paper characteristics of the paper transported on the first transport path 221. In particular, the first detection unit 23 is disposed on the first transport path 221, upstream of the branching point BP. The second detection unit 24 is disposed on the second transport path 222, downstream of the branching point BP.

[0029] The first detection unit 23 includes a size sensor 231 , a paper thickness sensor 232 , a basis weight sensor 233 , and a moisture percentage sensor 234 .

[0030] The size sensor 231 optically detects the size (shape) of the paper. The size sensor 231 is a line sensor that generates read image data by reading the paper being transported at a predetermined transport speed. The detection control unit 21 performs image processing on the obtained read image data for one sheet of paper to detect the edges of the paper (the positions of the four sides or the outer shape) and detect the size (shape).

[0031] The paper thickness sensor 232 detects the thickness of the paper by mechanically measuring the amount of displacement. When a sheet of paper is transported through the nip between the transport rollers, the shaft position of one of the driven rollers in the transport roller pair is displaced depending on the thickness of the sheet of paper. The thickness of the sheet of paper can be measured by measuring the height of this displaced shaft.

[0032] The basis weight sensor 233 is a transmissive and reflective optical sensor that detects the basis weight of paper. It includes a light-emitting unit and a light-receiving unit, and detects the basis weight of paper by measuring the attenuation (transmittance) and reflected light amount (reflectance) of light that passes through the paper. The light-emitting unit that constitutes the reflective optical sensor includes, for example, a blue LED (Light Emitting Diode) that emits blue light, a green LED that emits green light, and a red LED that emits red light. Therefore, the basis weight sensor 233 can detect the color of paper based on the reflected light amount of each light emitted by the blue LED, green LED, and red LED.

[0033] The moisture sensor 234 is a reflective optical sensor that detects the moisture content of paper. The moisture sensor 234 is equipped with a first light-emitting unit that irradiates the paper with light (wavelength 1450 nm) that is absorbed by moisture, a second light-emitting unit that irradiates the paper with light (wavelength 1300 nm) that is not absorbed by moisture, and a light-receiving unit. The moisture sensor 234 measures the amount of light received (amount of reflected light) by both units, and detects the moisture content of the paper based on the ratio between the first amount of light received by the first light-emitting unit and the second amount of light received by the second light-emitting unit.

[0034] In the first conveying path 221, a basis weight sensor 233 and a moisture percentage sensor 234 are disposed downstream of the paper thickness sensor 232. The basis weight sensor 233 and the moisture percentage sensor 234 are disposed side by side in the first conveying path 221 at the same position in the conveying direction (X direction) but at different positions in the width direction (Y direction). This arrangement shortens the overall length of the first detection unit 23 in the conveying direction, thereby reducing the space required. Furthermore, in the first conveying path 221, the size sensor 231 is disposed upstream of the other sensors. That is, the size sensor 231 is disposed upstream of the other sensors: the paper thickness sensor 232, the basis weight sensor 233, and the moisture percentage sensor 234. Normally, the leading edge of the paper is stopped and the paper is temporarily placed on standby before an image is transferred onto the paper in the image forming unit 38. However, by disposing the size sensor 231 upstream of the other sensors, the distance between the size sensor 231 and the image forming unit 38 can be increased, preventing the paper from stopping during detection by the size sensor 231.

[0035] The size sensor 231, paper thickness sensor 232, basis weight sensor 233, and moisture percentage sensor 234 detect paper characteristic information such as size, paper thickness, basis weight, and moisture percentage while conveying the paper conveyed along the first conveying path 221 without stopping it. As a result, when a print job in which continuous printing is performed is executed, the first detection unit 23 can detect paper characteristic information for each of multiple sheets of paper that are conveyed continuously. In other words, the first detection unit 23 can detect paper characteristic information for all sheets. Of these, the paper characteristic information of size, paper thickness, and basis weight is paper characteristic information corresponding to the paper type (paper type), and the paper characteristic information of moisture percentage is paper characteristic information corresponding to changes in the state of the paper.

[0036] In this way, the first detection unit 23 detects the paper type or paper characteristic information corresponding to changes in paper condition each time. This allows appropriate detection of cases where the type of paper loaded in the paper feed tray differs from the print job settings, where incorrect paper is mixed in the paper stack (mainly related to basis weight, thickness, or size), where the paper condition changes during continuous printing, or where the paper stack contains paper with uneven paper condition (mainly related to moisture content). Then, as will be described later, in the detection device 20, when the first detection unit 23 detects inappropriate paper, the detection device 20 switches the paper to the purge path (second conveyance path 222), conveys the paper, and discharges it to the purge tray 229. In this way, inappropriate paper is not sent to a subsequent stage, and jams and poor images can be prevented in the image forming device 30.

[0037] Furthermore, the size sensor 231 is disposed on the most upstream side. In principle, the size sensor 231 cannot determine the size of the paper until the paper passes through the detection position (photographing position). Therefore, the size sensor 231 needs to be disposed upstream of the image forming position of the image forming unit 38 (more specifically, the stopping position of the registration rollers) by the length of the longest paper that can be handled by the image forming system 100 (for example, long paper of about 900 mm). Therefore, the size sensor 231 is disposed on the most upstream side of the first conveying path 221.

[0038] The paper thickness sensor 232 is disposed second from the upstream side. By detecting the thickness of the paper sheet first, the detection device 20 can appropriately set the measurement range (latitude), measurement conditions, etc. when the subsequent basis weight sensor 233 and moisture percentage sensor 234 detect the thickness of the paper sheet.

[0039] The second detection unit 24 includes a stiffness sensor 241 , a surface property sensor 242 , and a resistance sensor 243 .

[0040] The stiffness sensor 241 detects the stiffness of the paper by mechanically measuring the amount of displacement. The stiffness sensor 241 detects the stiffness of the paper from the repulsive force (rigidity) of the paper when the bottom end (free end) of the paper is pressed from the side by a pressing unit (not shown).

[0041] The surface property sensor 242 is a reflective optical sensor (specular reflection, diffuse reflection) that detects the surface property of the paper. The surface property sensor 242 detects the surface property of the paper based on the absolute value and ratio of the intensities of the detected specular reflection light and diffuse reflection light.

[0042] The resistance sensor 243 applies a high voltage between the front and back of a sheet of paper in a stopped state, and detects the electrical resistance (volume electrical resistance) of the sheet based on the value of the current that flows.

[0043] In the second conveying path 222, the stiffness sensor 241 and the surface property sensor 242 are arranged upstream (below) of the resistance sensor 243. In the example shown in Fig. 1, the stiffness sensor 241 and the surface property sensor 242 are arranged in this order in the conveying direction (Z direction), but this order may be reversed. In addition, for reasons explained below, in the path from the first conveying path 221 to the second conveying path 222, the size sensor 231 is arranged upstream of the moisture percentage sensor 234.

[0044] During detection, the resistance sensor 243 applies a high voltage to the paper and causes a current to flow through the paper. Therefore, after the resistance is detected, the paper may accumulate charge on its surface and become statically charged (especially in a low-humidity environment). Since there is a risk that the stiffness detection will not be performed accurately on statically charged paper, the stiffness sensor 241 is located upstream (below) of the resistance sensor 243. Furthermore, passing a current through the paper during detection by the resistance sensor 243 may slightly heat the paper, which may change the moisture content. To eliminate this effect, the moisture content sensor 234 is located upstream of the resistance sensor 243 (on the first conveying path 221).

[0045] The second detection unit 24 stops the paper at each sensor position, performs detection, and then sends the paper to the next sensor downstream. The next sensor measures the paper when the trailing edge of the paper is not clamped by the components (rollers, etc.) of the previous sensor (leaving the edge open makes it easier for the components of the sensor to press the paper to fix the surface). Note that if the paper is long enough (in the conveying direction), for example, if it is longer than A4 size, the paper can be positioned across the detection positions of the three sensors. Therefore, the second detection unit 24 can simultaneously perform resistance detection with the resistance sensor 243, surface property detection with the surface property sensor 242, and stiffness detection with the stiffness sensor 241 with a single stop, minimizing any loss of productivity.

[0046] The storage unit 25 is configured by storage means such as a semiconductor memory, such as a dynamic random access memory (DRAM) or a hard disk drive (HDD). The storage unit 25 stores a first threshold value, a linear function for calculating a second threshold value, and a third threshold value, which are used in the paper type determination process described below.

[0047] [1-3. Configuration of image forming device] The image forming apparatus 30 forms a color image by electrophotography based on image data obtained by reading an image from an original or image data of a job received from an external device (not shown). The image forming apparatus 30 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit 34, an interface 35, a scanner 36, an image processing unit 37, an image forming unit 38, an image fixing unit 39, a conveying unit 40, and the like. The control unit 31 is connected to the memory unit 32, operation unit 33, display unit 34, interface 35, scanner 36, image processing unit 37, image forming unit 38, image fixing unit 39, and conveying unit 40 via a bus 41.

[0048] The control unit 31 includes a CPU, a ROM, and a RAM. The CPU of the control unit 31 reads out a control program stored in the ROM, loads it into the RAM, and controls each unit of the image forming apparatus 30 in accordance with the loaded program. For example, the control unit 31 causes the image processing unit 37 to perform predetermined image processing on the image data and stores the image data in the storage unit 32. The control unit 31 also causes the conveying unit 40 to convey the paper, and causes the image forming unit 38 to form an image on the paper based on the image data stored in the storage unit 32.

[0049] The storage unit 32 is configured by a storage means such as a semiconductor memory such as a DRAM or an HDD. The storage unit 32 stores image data acquired by the scanner 36, image data input from the outside via the interface 35, etc. The image data, etc. may be stored in a RAM included in the control unit 31. The storage unit 32 also stores a process condition estimation model used in the process condition setting process described below.

[0050] The operation unit 33 includes input devices such as operation keys and a touch panel arranged over the screen of the display unit 34. The operation unit 33 converts input operations on these input devices into operation signals and outputs the signals to the control unit 31.

[0051] The display unit 34 includes a display device such as an LCD (Liquid Crystal Display), and displays an operation screen showing the status of the image forming system 100 and the contents of input operations on the touch panel.

[0052] The interface 35 is a means for transmitting and receiving data to and from an external computer, another image forming apparatus, etc. The interface 35 is configured by, for example, any one of various serial interfaces.

[0053] The scanner 36 reads an image formed on a sheet, generates image data including monochrome image data for each of the color components R (red), G (green), and B (blue), and stores the generated image data in the storage unit 32.

[0054] The image processing unit 37 includes, for example, a rasterization processing unit, a color conversion unit, a gradation correction unit, and a halftone processing unit. The image processing unit 37 performs various image processes on the image data stored in the storage unit 32 and stores the processed image data in the storage unit 32.

[0055] Image forming unit 38 forms an image on paper based on image data stored in storage unit 32. Image forming unit 38 includes four sets of exposure units 381, photosensitive drums 382, and development units 383, each set corresponding to the color components of C (cyan), M (magenta), Y (yellow), and K (black). Image forming unit 38 also includes a transfer body 384 and a secondary transfer roller 385.

[0056] The exposure unit 381 includes an LD (Laser Diode) as a light-emitting element. The exposure unit 381 drives the LD based on image data to irradiate and expose the charged photosensitive drum 382 with laser light, thereby forming an electrostatic latent image on the photosensitive drum 382. The development unit 383 supplies toner (color material) of a predetermined color (any of C, M, Y, or K) onto the exposed photosensitive drum 382 using a charged development roller, thereby developing the electrostatic latent image formed on the photosensitive drum 382.

[0057] Images (monochromatic images) formed with C, M, Y, and K toners on four photosensitive drums 382 corresponding to C, M, Y, and K, respectively, are sequentially superimposed and transferred from each photosensitive drum 382 onto a transfer body 384. As a result, a color image having C, M, Y, and K color components is formed on the transfer body 384. The transfer body 384 is an endless belt wound around multiple transfer body transport rollers, and rotates in accordance with the rotation of each transfer body transport roller.

[0058] Secondary transfer roller 385 transfers the color image on transfer body 384 onto paper fed from paper feeder 10. More specifically, the paper and transfer body 384 are sandwiched in a transfer nip formed by pressure contact between the pair of secondary transfer rollers 385. Then, by applying a predetermined transfer voltage to secondary transfer roller 385, the toner forming the color image on transfer body 384 is attracted to the paper and transferred to the paper.

[0059] The image fixing unit 39 includes a fixing roller, a pressure roller, and the like, and performs a fixing process of fixing the toner onto the paper by applying heat and pressure to the paper onto which the toner has been transferred.

[0060] The transport unit 40 includes a plurality of paper transport rollers that rotate while holding the paper, thereby transporting the paper along a predetermined transport path. The transport unit 40 includes a reversing mechanism 401 that reverses the paper that has been subjected to the fixing process by the image fixing unit 39 and transports it to the secondary transfer roller 385. In the image forming device 30, when images are to be formed on both sides of the paper, the reversing mechanism 401 reverses the paper and the paper is discharged after the images have been formed on both sides. When an image is to be formed on only one side of the paper, the reversing mechanism 401 does not reverse the paper and the paper is discharged with the image formed on one side.

[0061] In this embodiment, the control unit 31 of the image forming apparatus 30 controls the entire image forming system 100 in an integrated manner, but this is not limiting. The detection control unit 21 of the detection apparatus 20 may be configured to control the entire image forming system 100 in an integrated manner.

[0062] [2. Operation of image forming system] Next, the operation of the image forming system 100 will be described. FIG. 3 is a flowchart showing the flow of the process condition setting process that is executed when the image forming apparatus 30 receives image data and setting information of a print job via the interface 35. The process condition setting process of FIG. 3 is executed by the CPU of the control unit 31 of the image forming apparatus 30 in cooperation with a process condition control program stored in the ROM.

[0063] The control unit 31 executes the process condition setting process to set process conditions for image formation by the image forming unit 38 for each determined paper type. Here, the process conditions are, for example, transfer conditions when transferring a color image on the transfer body 384 to paper. Specifically, the transfer conditions are the transfer voltage value and transfer current value applied to the secondary transfer roller 385 when transferring the color image on the transfer body 384 to paper.

[0064] The control unit 31 may execute a process condition setting process to set process conditions other than the transfer conditions (for example, the fixing temperature when the fixing process is performed by the image fixing unit 39). Furthermore, the control unit 31 may set transfer conditions other than the transfer voltage value and transfer current value applied to the secondary transfer roller 385 by executing a process condition setting process.

[0065] [2-1. Process condition setting] In the process condition setting process, first, the control unit 31 causes the sheet feeding device 10 to feed the sheet (job target sheet) on which an image is to be formed in the print job from the sheet feeding unit 13, and transports it to the detection device 20 (step S1).

[0066] Next, the control unit 31 causes the detection device 20 to execute a paper type determination process on the paper that is the object of the job (step S2). FIG. 4 shows a flowchart of the paper type determination process. The paper type determination process of FIG. 4 is executed by the CPU of the detection control unit 21 in cooperation with a paper type determination program stored in the ROM.

[0067] [2-2. Paper type determination process] First, the detection control unit 21 detects paper characteristic information (size, paper thickness, basis weight, moisture content, stiffness, surface properties, resistance, etc.) of the paper on the first and second conveying paths 221 and 222 using the first detection unit 23 and the second detection unit 24 (step S21). Here, the paper characteristic information related to basis weight includes information on the attenuation (transmittance) of light passing through the paper to be processed and the amount of reflected light (reflectance) measured in the process of detecting the basis weight.

[0068] Next, the detection control unit 21 determines whether the attenuation (transmittance) of light transmitted through the job target paper is higher than a first threshold value based on the detected paper characteristic information (step S22).

[0069] In step S22, if it is determined that the attenuation (transmittance) of light transmitted through the job target paper is higher than the first threshold (step S22; YES), the detection control unit 21 determines that the paper type of the job target paper is a transparent sheet (step S23). Then, the detection control unit 21 returns the process to the process condition setting process (see FIG. 3). Here, the transparent sheet is, for example, a transparent sheet made of resin, such as an OHP (Over Head Projector) sheet.

[0070] Furthermore, if it is determined in step S22 that the attenuation (transmittance) of light transmitted through the job target paper is not higher than the first threshold (step S22; NO), the detection control unit 21 determines whether the moisture content of the job target paper is lower than a second threshold (step S24). Here, the second threshold is calculated using the following linear function: Second threshold [%] = 0.0113 (first constant) x paper thickness [μm] + 1.43 (second constant)

[0071] FIG. 5 is a diagram showing the above linear function (denoted by the symbol F in the drawing) in an xy coordinate system. As shown in Figure 5, this xy coordinate system has the paper thickness [μm] of the paper to be processed on the x-axis (horizontal axis) and the moisture content [%] of the paper to be processed on the y-axis (vertical axis), with the paper thickness [μm] and moisture content [%] of the performance data (paper characteristic information) plotted at the corresponding coordinate positions. Of the plotted points, those plotted below the linear function F are for synthetic paper. On the other hand, those plotted above the linear function F are for paper made from pulp fiber (non-synthetic paper).

[0072] Alternatively, a threshold table may be stored in memory 25, with the input being the thickness [μm] of the job target paper and the output being the second threshold value, and the second threshold value may be acquired using the threshold table. As shown in FIG. 6, the second threshold value may be a predetermined fixed value, such as threshold value TH1 when the job target paper has a thickness of less than 280 μm, and threshold value TH2 when the job target paper has a thickness of 280 μm or more. The second threshold value may be a uniform (fixed) value regardless of the thickness of the job target paper. Therefore, when the second threshold value is a uniform value, detection control unit 21 can determine whether the job target paper is synthetic paper based on the detection result of moisture sensor (moisture sensor) 234, which detects characteristic information (moisture content) corresponding to the moisture content of the job target paper.

[0073] Returning to FIG. 4, if it is determined in step S24 that the moisture content of the job target paper is lower than the second threshold value (step S24; YES), the detection control unit 21 determines that the paper type of the job target paper is synthetic paper (step S25). Then, the detection control unit 21 returns the process to the process condition setting process (see FIG. 3). Here, synthetic paper refers to a sheet made of resin, excluding the transparent sheet described above, that is, a non-transparent sheet made of resin.

[0074] Also, if it is determined in step S24 that the moisture content of the paper to be processed is not lower than the second threshold value (step S24; NO), the detection control unit 21 determines whether the ratio of specularly reflected light detected by the surface property sensor 242 is higher than the third threshold value (step S26).

[0075] In step S26, if it is determined that the ratio of specular reflection light detected by the surface property sensor 242 is higher than the third threshold (step S26; YES), the detection control unit 21 determines that the paper type of the paper to be printed on the job is metallized paper (step S27). Then, the detection control unit 21 returns the process to the process condition setting process (see FIG. 3).

[0076] Furthermore, in step S26, if it is determined that the ratio of specular reflection light detected by the surface property sensor 242 is not higher than the third threshold (step S26; NO), the detection control unit 21 determines whether the job target paper is colored paper or not (step S28). Here, the detection control unit 21 determines whether the job target paper is colored paper or not based on the result of color detection performed by the basis weight sensor 233.

[0077] If it is determined in step S28 that the job target paper is colored paper (step S28; YES), the detection control unit 21 determines that the paper type of the job target paper is colored paper (step S29). Then, the detection control unit 21 returns the process to the process condition setting process (see FIG. 3).

[0078] Furthermore, if it is determined in step S28 that the job target paper is not colored paper (step S28; NO), the detection control unit 21 determines that the paper type of the job target paper is general plain paper (white paper) made of pulp fiber (step S30).Then, the detection control unit 21 returns the process to the process condition setting process (see FIG. 3).

[0079] Returning to FIG. 3, the control unit 31 determines whether the type of paper to be printed for the job (transparent sheet, synthetic paper, metallized paper, colored paper, plain paper) has been determined in the paper type determination process of FIG. 4 (step S3).

[0080] If it is determined in step S3 that the type of the job target paper has not been determined (step S3; NO), the control unit 31 sets the process conditions estimated by the process condition estimation model stored in the memory unit 32 (step S4). Then, the control unit 31 ends the process condition setting process. Here, the process condition estimation model is a learning model (trained model) that has been machine-learned based on learning data (learning information) that includes paper characteristic information. By inputting the paper characteristic information (estimation information) of the job target paper detected in step S21 of the paper type determination process (see FIG. 4) into this process condition estimation model, it is possible to estimate the process conditions of the job target paper.

[0081] Also, if it is determined in step S3 that the type of paper to be processed for the job has been determined (step S3; YES), the control unit 31 determines whether or not process conditions corresponding to the type of paper to be processed for the job are stored in the memory unit 32 (step S5).

[0082] In step S5, if it is determined that the process conditions corresponding to the type of paper to be processed are stored in the storage unit 32 (step S5; YES), the control unit 31 sets the process conditions (step S6), and then the control unit 31 ends the process condition setting process.

[0083] Furthermore, if it is determined in step S5 that the process conditions corresponding to the type of paper to be processed are not stored in the storage unit 32 (step S5; NO), the control unit 31 sets the process conditions input by the user via the operation unit 33 (step S7). Then, the control unit 31 ends the process condition setting process.

[0084] [3.Effects] As described above, the detection device (paper type determination device) 20 of this embodiment can determine whether paper is synthetic paper or not based on the detection results of the moisture sensor (moisture percentage sensor 234) that detects characteristic information (moisture percentage) corresponding to the moisture content of the paper (job target paper). This makes it possible to determine whether a sheet is synthetic paper or not without being affected by environmental humidity, and therefore makes it possible to accurately distinguish between synthetic paper and ordinary paper.

[0085] Furthermore, the detection device 20 determines whether the paper is synthetic paper or not based on the detection results of a paper thickness sensor (thickness sensor) 232 that detects the thickness of the paper (job target paper) and the detection results of a moisture percentage sensor (moisture sensor) 234. This allows the detection result of the paper thickness sensor 232 to be taken into consideration when determining whether the paper is synthetic paper or not, making it possible to more accurately distinguish between synthetic paper and ordinary paper.

[0086] Furthermore, the detection device 20 determines whether the paper is synthetic paper or not based on the detection result of a basis weight sensor 233 that detects the basis weight of the paper (job target paper) and the detection result of a moisture percentage sensor 234. This allows the detection result of the basis weight sensor 233 to be taken into consideration when determining whether the paper is synthetic paper or not, making it possible to more accurately distinguish between synthetic paper and ordinary paper.

[0087] Furthermore, based on the detection result of the paper thickness sensor 232, the detection device 20 determines a threshold value (second threshold value) used when determining whether or not the paper is synthetic paper. This allows a threshold value (second threshold value) according to the detection result of the paper thickness sensor 232 to be used when determining whether the paper is synthetic paper or not, thereby enabling a more accurate determination between synthetic paper and ordinary paper.

[0088] In addition, if the detection result of the moisture content sensor 234 is higher than a threshold value (second threshold value), the detection device 20 determines that the paper is non-synthetic paper containing a sheet made of pulp fibers, and if the detection result is lower than the threshold value, the detection device 20 determines that the paper is synthetic paper made of resin. This allows accurate discrimination between synthetic paper and ordinary paper.

[0089] The detection device 20 determines the threshold value (second threshold value) using the following formula (linear function): Second threshold value=0.0113 (first constant)×paper thickness [μm]+1.43 (second constant) This allows a threshold value (second threshold value) according to the detection result of the paper thickness sensor 232 to be used when determining whether the paper is synthetic paper or not, thereby enabling a more accurate determination between synthetic paper and ordinary paper.

[0090] Furthermore, the detection device 20 further determines whether the sheet is a transparent sheet based on the detection result (detection result of the basis weight sensor 233) of characteristic information corresponding to the transmittance of light irradiated onto the sheet (job target sheet). This makes it possible to determine whether the paper is synthetic paper or not, and, for synthetic paper, whether it is a transparent sheet or not.

[0091] In addition, the image forming system 100 of this embodiment changes the secondary transfer current (transfer current value applied to the secondary transfer roller 385) applied to the paper (job target paper) in the image forming unit 38 based on the paper type determination result by the detection device (paper type determination device) 20. This allows the secondary transfer current to be adjusted according to the paper, so that an image can be formed appropriately on the paper.

[0092] In addition, the paper type determination program of this embodiment enables the computer (detection device 20) to function as a determination means for determining whether paper is synthetic paper or not based on the detection results of a moisture sensor (moisture percentage sensor 234) that detects characteristic information (moisture percentage) corresponding to the moisture content of the paper (job target paper). This makes it possible to determine whether a sheet is synthetic paper or not without being affected by environmental humidity, and therefore makes it possible to accurately distinguish between synthetic paper and ordinary paper.

[0093] The above-described embodiments are examples of the paper type determination device, image forming system, and paper type determination program according to the present invention, and are not intended to limit the scope of the present invention. The detailed configuration and operation of each part of the device can also be modified as appropriate without departing from the spirit of the present invention.

[0094] Furthermore, in the above embodiment, the paper type determination device (detection device 20) is exemplified as being applied to an image forming device 30 that uses an electrophotographic printing method, but this is not limited to this, and the device can also be applied to an inkjet image forming device or an image forming device using other printing methods. [Explanation of symbols]

[0095] 100 Image forming system 10 Paper feeder 11 Paper feed control unit 12 Conveyor 13 Paper feed section 14 Bus 20. Detection device (paper type determination device) 21 Detection control unit 22 Conveyor 23 First detection unit 231 Size Sensor 232 Paper thickness sensor (thickness sensor) 233 Basis weight sensor 234 Moisture Sensor (Moisture Sensor) 24 Second detection unit 241 Stiffness Sensor 242 Surface Sensor 243 Resistance Sensor 25 Memory section 26 Bus 30 Image forming device 31 Control Unit 32 Storage section 33 Operation section 34 Display section 35 Interface 36 Scanner 37 Image processing section 38 Image forming unit 381 Exposure section 382 Photosensitive drum 383 Development Unit 384 Transcripts 385 Secondary transfer roller 39 Image fixing unit 40 Conveying section 401 Reversal mechanism 41 Bus

Claims

1. In a paper type determination device for determining a paper type, A paper type determination device that determines whether a paper is synthetic paper or not based on the detection results of a moisture sensor that detects characteristic information corresponding to the moisture content of the paper.

2. 2. The paper type determination device according to claim 1, further determining whether the paper is synthetic paper or not based on the detection result of a thickness sensor that detects the thickness of the paper and the detection result of the moisture sensor.

3. 2. The paper type determination device according to claim 1, further determining whether the paper is synthetic paper or not based on the detection result of a basis weight sensor that detects the basis weight of the paper and the detection result of the moisture sensor.

4. 3. The paper type determination device according to claim 2, wherein a threshold value used to determine whether a paper is synthetic paper or not is determined based on the detection result of the thickness sensor.

5. 5. A paper type determination device according to claim 4, wherein if the detection result of the moisture sensor is higher than the threshold value, the paper is determined to be non-synthetic paper including a sheet made of pulp fiber, and if the detection result is lower than the threshold value, the paper is determined to be synthetic paper made of resin.

6. 5. The paper type determination device according to claim 4, further comprising a threshold value table having the paper thickness as an input and the threshold value as an output.

7. 5. The paper type determination device according to claim 4, wherein the threshold value is determined by the following formula: Threshold value = Paper thickness x 1st constant + 2nd constant

8. 2. The paper type determination device according to claim 1, further determining whether the paper is a transparent sheet or not based on the detection result of characteristic information corresponding to the transmittance of light irradiated onto the paper.

9. An image forming system including the paper type determination device according to any one of claims 1 to 8, An image forming system in which a secondary transfer current applied to the paper in the image forming unit is changed based on the result of the paper type determination by the paper type determination device.

10. An image forming system including the paper type determination device according to any one of claims 1 to 8, An image forming system that changes a fixing temperature for fixing toner onto paper in an image forming unit based on the result of paper type determination by the paper type determination device.

11. A paper type determination program for determining a paper type, Computer, a determining means for determining whether the paper is synthetic paper or not based on the detection result of a moisture sensor that detects characteristic information corresponding to the moisture content of the paper; A paper type determination program that functions as a

Images