Sheet characteristic detecting apparatus, image forming system, and program

Abstract

To prevent a problem that occurs according to characteristics of a sheet when measuring the characteristics of the sheet.SOLUTION: A sheet characteristic detection device 2 includes a first characteristic detection unit that is disposed on a conveyance path of a sheet and detects first characteristic information corresponding to a first characteristic of the sheet, and a second characteristic detection unit that is disposed on the conveyance path of the sheet and detects second characteristic information corresponding to a second characteristic of the sheet, where the other characteristic detection unit is controlled based on a detection result of any one characteristic detection unit of the first characteristic detection unit and the second characteristic detection unit.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] In an image forming apparatus that forms and outputs an image on paper, various conditions (image forming conditions) related to the image forming operation, the recording medium conveyance operation, etc., can be appropriately adjusted according to the characteristics of the paper on which the image is formed, thereby enabling stable conveyance of the recording medium and forming a high-quality image. Because there are various types of paper used, there is a technology in which the image forming apparatus is equipped with a sensor that measures the physical properties of the paper, and the physical properties of the paper being conveyed are identified from the measurement results by the sensor and used to set the conditions (for example, Patent Document 1). The physical properties of the paper include the moisture content, electrical resistance, stiffness, etc. of the paper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-084232 Summary of the Invention [Problem to be solved by the invention]

[0004] However, various problems may arise when using the sensor to measure paper, depending on its physical properties and other characteristics. For example, if the paper has a high moisture content, applying a high voltage to the paper to measure its electrical resistance may cause the following problems. Specifically, leakage voltage may be applied to electrical devices in the device via the paper, exceeding their withstand voltage and damaging the electrical devices.

[0005] An object of the present invention is to provide a paper characteristic detection device, an image forming system, and a program that can prevent problems that occur depending on the characteristics of the paper when measuring the characteristics of the paper. [Means for solving the problem]

[0006] In order to achieve the above object, the paper characteristic detection device according to claim 1 comprises: a first characteristic detection unit disposed on a paper transport path for detecting first characteristic information corresponding to a first characteristic of the paper; a second characteristic detection unit disposed on the transport path for detecting second characteristic information corresponding to a second characteristic of the paper; Equipped with Based on the detection result of one of the first characteristic detection unit and the second characteristic detection unit, the other characteristic detection unit is controlled.

[0007] The invention described in claim 2 is the paper characteristic detection device described in claim 1, The image forming unit is disposed upstream or downstream of the image forming unit that forms an image on the paper.

[0008] The invention described in claim 3 is the paper characteristic detection device described in claim 2, is disposed upstream of the image forming unit, The image forming conditions in the image forming unit are determined based on at least one of the first characteristic information and the second characteristic information.

[0009] The invention described in claim 4 is the paper characteristic detection device described in claim 1, the second characteristic detection unit is disposed downstream of the first characteristic detection unit, The second characteristic detector is controlled in accordance with the detection result of the first characteristic detector.

[0010] The invention described in claim 5 is the paper characteristic detection device described in claim 4, The detection conditions in the second characteristic detection section are changed according to the detection result of the first characteristic detection section.

[0011] The invention described in claim 6 is the paper characteristic detection device described in claim 4, The second characteristic detection unit is controlled not to perform detection in accordance with the detection result of the first characteristic detection unit.

[0012] The invention described in claim 7 is the paper characteristic detection device described in claim 6, When the second characteristic detection unit does not perform detection, the sheet is ejected without the second characteristic detection unit performing an operation to stop the sheet.

[0013] The invention described in claim 8 is the paper characteristic detection device described in claim 1, The first characteristic and the second characteristic are different from each other.

[0014] The invention described in claim 9 is the paper characteristic detection device described in claim 1, the first characteristic information is information corresponding to the moisture content of the paper, The second characteristic information is information corresponding to the electrical resistance of the paper.

[0015] The invention described in claim 10 is the paper characteristic detection device described in claim 9, The greater the moisture content, the lower the voltage applied to the paper when the second characteristic detection unit detects the information corresponding to the electrical resistance.

[0016] The invention described in claim 11 is the paper characteristic detection device described in claim 9, The greater the amount of moisture, the fewer times the second characteristic detector detects the information corresponding to the electrical resistance.

[0017] The invention described in claim 12 is the paper characteristic detection device described in claim 1, the second characteristic detection unit is disposed downstream of the first characteristic detection unit, the first characteristic information is information corresponding to the moisture content of the paper, The second characteristic information is information corresponding to the stiffness of the paper.

[0018] The invention described in claim 13 is the paper characteristic detection device described in claim 12, The detection operation when the second characteristic detector detects the information corresponding to the stiffness is changed depending on the moisture content.

[0019] The invention described in claim 14 is the paper characteristic detection device described in claim 1, the second characteristic detection unit is disposed downstream of the first characteristic detection unit, the first characteristic information is information corresponding to the thickness of the paper; The second characteristic information is information corresponding to the moisture content of the paper.

[0020] The invention described in claim 15 is the paper characteristic detection device described in claim 14, The detection conditions for detecting the information corresponding to the moisture content by the second characteristic detection unit are changed according to the paper thickness.

[0021] The invention described in claim 16 is the paper characteristic detection device described in claim 1, The device further includes a control unit that controls one of the first characteristic detection unit and the second characteristic detection unit based on a detection result of the other characteristic detection unit.

[0022] The image forming system according to claim 17, A paper characteristic detection device according to any one of claims 1 to 16; an image forming unit that forms an image on the paper; Equipped with.

[0023] The program according to claim 18 comprises: a first characteristic detection unit disposed on a paper transport path for detecting first characteristic information corresponding to a first characteristic of the paper; a second characteristic detection unit disposed on the transport path for detecting second characteristic information corresponding to a second characteristic of the paper; A computer of a paper characteristic detection device comprising: The first characteristic detector and the second characteristic detector are caused to function as a control unit that controls one of the first characteristic detector and the second characteristic detector based on the detection result of the other characteristic detector. [Effects of the Invention]

[0024] According to the present invention, problems that occur depending on the characteristics of the paper when measuring the characteristics of the paper can be prevented. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing the overall configuration of an image forming system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a detailed configuration of a paper characteristic detection device. [Figure 3] FIG. 1 is a diagram showing an example of a schematic configuration of a moisture percentage sensor. [Figure 4A] FIG. 2 is a perspective view showing an example of a schematic configuration of a stiffness sensor. [Figure 4B] FIG. 2 is a side view showing an example of a schematic configuration of a stiffness sensor. [Figure 5] FIG. 1 is a diagram illustrating an example of a schematic configuration of a resistance sensor. [Figure 6] 10 is a flowchart showing a control procedure of a detection control process. [Figure 7] 10 is a flowchart showing a control procedure of a detection control process according to a first modification. [Figure 8] 10 is a flowchart showing a control procedure of a detection control process according to a second modification. [Figure 9] 10 is a diagram showing the relationship between the moisture content of paper and the applied voltage in Modification 2. FIG. [Figure 10] FIG. 10 is a diagram showing the correspondence between the moisture content of paper and the number of measurements by the resistance sensor in Modification 2. [Figure 11] 10 is a flowchart showing a control procedure of a detection control process according to a third modification. [Figure 12A] 10 is a schematic diagram of a sheet and a stiffness sensor before the first movement of the pressing member. [Figure 12B] 10 shows a schematic diagram of the paper and the stiffness sensor after the first movement of the pressing member. [Figure 13A] 10 shows a schematic diagram of the paper and stiffness sensor before the second movement of the pressing member. [Figure 13B] 10 shows a schematic diagram of the paper and stiffness sensor after the second movement of the pressing member. [Figure 14] 10 is a flowchart showing a control procedure of a detection control process according to a fourth modification. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the scope of the invention is not limited to the illustrated examples.

[0027] <1. Image Forming System Configuration> FIG. 1 is a diagram showing the overall configuration of an image forming system U according to this embodiment. The image forming system U includes a paper feeder 1, a paper characteristic detection device 2, an image forming device 3, and a post-processing device 4.

[0028] (Paper feeder) The paper feeder 1 has a plurality of paper feed trays 11. The paper feeder 1 feeds media (paper) on which images are to be recorded one by one from one of the paper feed trays 11 that has been selected and set.

[0029] (Paper characteristic detection device) The paper characteristic detection device 2 has multiple sensors for measuring the physical properties of paper. The paper characteristic detection device 2 measures the paper sent from the paper feeder 1 along its path using multiple sensors. The paper characteristic detection device 2 can identify the physical properties of the paper (characteristic information) based on the measurement results. The paper characteristic information may be the characteristic value of the paper itself, or a value that indicates the characteristic, such as the current or voltage of a sensor corresponding to the characteristic value of the paper. The paper characteristic detection device 2 may output the physical property value obtained by measurement directly to an external device, for example, the image forming device 3.

[0030] 2 shows a block diagram of the paper characteristic detection device 2. The paper characteristic detection device 2 includes a control unit 21, a memory unit 22, a paper thickness sensor 23, a moisture content sensor 24, a stiffness sensor 25, a resistance sensor 26, a transport unit 27, a communication unit 28, and the like.

[0031] The control unit 21 comprehensively controls the operation of the paper characteristic detection device 2. The control unit 21 includes a CPU (Central Processing Unit), RAM (Random Access Memory), etc. The CPU controls the measurement operations of each sensor (paper thickness sensor 23, moisture content sensor 24, stiffness sensor 25, and resistance sensor 26) and the paper transport operation of the transport unit 27. The RAM temporarily stores the measurement results of each sensor, etc.

[0032] The storage unit 22 stores control programs for the measurement operations of the sensors, measurement setting data, etc. The storage unit 22 has a non-volatile memory such as an HDD or a flash memory.

[0033] The conveying section 27 receives paper sheets sent from the paper feeder 1 on the right side of Fig. 1, and sends the paper sheets along the first conveying path 27M from the left side of Fig. 1 to the image forming device 3. A second conveying path 27S branches off from the middle of the horizontally extending first conveying path 27M. The tip of the second conveying path 27S is connected to the purge tray 271. A paper thickness sensor 23 is located on the upstream side of the first transport path 27M, and a moisture percentage sensor 24 is located on the downstream side. A stiffness sensor 25 is located on the upstream side of the second transport path 27S, and a resistance sensor 26 is located on the downstream side.

[0034] The paper thickness sensor 23 measures the thickness of the paper as characteristic information of the paper and outputs the measurement result. The paper thickness sensor 23 includes a pair of transport rollers, at least one of which moves depending on the thickness of the paper passing through the nip between the rollers, and a measurement unit that measures the distance between the axes of the pair of transport rollers. The measurement unit includes, for example, an actuator, an encoder, a light-emitting unit, a light-receiving unit, etc. The axis position of the movable driven roller displaces depending on the thickness of the paper sandwiched between the pair of transport rollers. The paper thickness sensor 23 measures the height of this displaced axis to measure the thickness of the paper.

[0035] The moisture sensor 24 measures characteristic information corresponding to the moisture content of the paper and outputs the measurement result. In this embodiment, a moisture sensor that measures the moisture content of the paper as the characteristic information of the paper will be described as an example, but a moisture amount sensor that measures the amount of moisture contained in the paper as the characteristic information of the paper may also be applied. FIG. 3 is a schematic diagram showing the configuration of the moisture percentage sensor 24. As shown in FIG. As shown in FIG. 3, the moisture percentage sensor 24 includes a first light-emitting element 241, a second light-emitting element 242, a light-receiving element 243, lenses 244 and 245, and the like.

[0036] The first light emitter 241 emits first near-infrared light (reference light) in a specific wavelength band toward the paper P. A specific example of the first light emitter 241 is an LED (Light Emitting Diode) or the like. The first near-infrared light is light whose absorption rate in the paper P when reflected by the paper P does not depend on the moisture content of the paper P. The light receiving section 243 receives, via a lens 245, the first near-infrared light that is emitted from the first light emitting section 241 and reflected by the paper P via a lens 244. Specific examples of the light receiving unit 243 include a CCD (Charge-Coupled Device) and a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor.

[0037] The second light-emitting unit 242 emits second near-infrared light in a specific wavelength band toward the paper P. A specific example of the second light-emitting unit 242 is an LED or the like. The second near-infrared light is light whose absorption rate in the paper P when reflected by the paper P varies depending on the moisture content of the paper P. The light receiving section 243 receives, via a lens 245, the second near-infrared light that is emitted from the second light emitting section 242 and reflected by the paper P via a lens 244.

[0038] The moisture percentage sensor 24 outputs to the control unit 21 the amount of the first near-infrared light and the amount of the second near-infrared light received by the light receiving unit 243 (characteristic information corresponding to the moisture percentage of the paper). The control unit 21 calculates the moisture content of the paper P based on the ratio between the amount of the first near-infrared light received and the amount of the second near-infrared light received. The configuration of the moisture percentage sensor 24 is not limited to the example shown in Fig. 3. The moisture percentage sensor 24 may have other configurations as long as it can measure characteristic information corresponding to the moisture percentage of the paper P.

[0039] The paper thickness sensor 23 and the moisture content sensor 24 can measure the above-mentioned characteristic information while the paper is being transported at the transport speed.

[0040] The stiffness sensor 25 measures characteristic information corresponding to the stiffness of the paper and outputs the measurement result. The stiffness of the paper is an index showing the resistance when the paper is bent. 4A is a perspective view showing the configuration of the stiffness sensor 25. FIG. 4B is a side view showing the configuration of the stiffness sensor 25. Stiffness sensor 25 includes paper holding roller 251 that holds one edge of paper P, and pressing unit 252. In the example shown in FIGS. 4A and 4B, paper holding roller 251 is also included in transport unit 27 and also functions to transport paper P, but a separate member may also be used.

[0041] The pressing unit 252 includes a pressing member 252a, a pressing force detection unit 252b, a support mechanism 252c, and a motor M1.

[0042] The pressing member 252a is an elongated member formed in the paper width direction (Y-axis direction) so as to be able to contact the entire width of the paper P being transported in the paper transport direction (Z-axis direction). The pressing member 252a presses the paper P. The pressing force detection unit 252b includes, for example, a pressure sensor, and detects the pressing force from the paper sheet P when the pressing member 252a presses the paper sheet P. The support mechanism 252c supports the pressing member 252a and the pressing force detection unit 252b so that they can move in the X-axis direction. The motor M1 is a drive source for moving the pressing member 252a and the pressing force detection unit 252b in the X-axis direction via the support mechanism 252c. The motor M1 includes, for example, a stepping motor.

[0043] A method for obtaining the stiffness of the paper P will be described below. 4A and 4B, under the control of control unit 21, conveyance unit 27 stops motor M2 that drives paper sheet holding rollers 251, and stops the conveyance of paper sheet P at a predetermined position on second conveyance path 27S. At this time, paper sheet P is sandwiched and held between paper sheet holding rollers 251. Paper sheet holding rollers 251 hold paper sheet P at a position a predetermined distance away from edge Pa of paper sheet P.

[0044] Next, the pressing unit 252 moves the pressing member 252a in the positive direction of the X axis by driving the motor M1. As a result, the end Pa (free end) of the paper P is pressed by the pressing member 252a and bent, as shown in FIG. 4B. At this time, the position where the pressing member 252a begins to contact the surface of the paper P (the right side in FIG. 4B) when the paper P is not bent is set to the home position of the pressing member 252a in the X axis direction. When the paper P is bent by the pressing member 252a by a predetermined amount (for example, 3 mm) from this home position, the pressing force detection unit 252b detects the pressing force received from the paper P.

[0045] The pressing unit 252 presses the paper P by pressing the pressing member 252a against the paper P at a position closer to the edge Pa of the paper P than the position where the paper P is held by the paper holding roller 251. The amount of bending of the paper P by the pressing member 252a can be determined from the number of pulse signals input to the driver of the motor M1.

[0046] The stiffness sensor 25 outputs the pressing force (characteristic information corresponding to the stiffness of the paper) detected by the pressing force detection unit 252b to the control unit 21. The control unit 21 calculates the stiffness of the paper based on the pressure value of the pressing force.

[0047] 4A and 4B show an example in which the pressing member 252a presses the paper sheet P from right to left, but the present invention is not limited to this. The pressing member 252a may also press the paper sheet P from left to right.

[0048] The resistance sensor 26 measures characteristic information corresponding to the electrical resistance (volume electrical resistance) of the paper and outputs the measurement result. FIG. 5 is a schematic diagram showing the configuration of the resistance sensor 26. 5, the resistance sensor 26 includes a paper holding roller 261 that sandwiches the paper P between a pair of rollers, and an HV (high voltage) unit 262. In the example shown in FIG. 5, the paper holding roller 261 is also included in the conveying unit 27 and also functions to convey the paper P, but a separate member may also be used. The paper holding roller 261 includes a detection roller 261a located on the left side of the paper surface, and an opposing roller 261b located on the right side of the paper surface and connected to the ground.

[0049] A method for obtaining the electrical resistance of the paper P will be described below. As shown in FIG. 5, under the control of control unit 21, conveyance unit 27 stops motor M3, which drives paper holding roller 261, and temporarily stops paper P at a predetermined position on second conveyance path 27S. At this time, paper P is sandwiched and held between paper holding rollers 261. In this state, resistance sensor 26 applies a high voltage to detection roller 261a via HV unit 262 and measures the value of the current flowing through paper P to opposing roller 261b. Resistance sensor 26 outputs the measured current value (characteristic information corresponding to the electrical resistance of the paper) to control unit 21. Control unit 21 calculates the electrical resistance of the paper by dividing the voltage applied to detection roller 261a by HV unit 262 by the current value measured by resistance sensor 26.

[0050] Alternatively, the resistance sensor 26 may measure the characteristic information corresponding to the electrical resistance of one sheet of paper multiple times to calculate the electrical resistance of the paper. In this case, as described above, resistance sensor 26 applies a high voltage to detection roller 261a using HV unit 262, and performs a first measurement of the current value flowing to opposing roller 261b via paper P held between paper holding rollers 261. Next, resistance sensor 26 outputs the first measured current value to control unit 21. Next, under the control of control unit 21, conveyance unit 27 conveys and temporarily stops paper sheet P so that paper sheet P is held by paper sheet holding roller 261 at a position other than the position where paper sheet P was held by paper sheet holding roller 261 during the first measurement of the current value. In this state, resistance sensor 26 applies a high voltage to detection roller 261a using HV unit 262, and performs a second measurement of the current value flowing to opposing roller 261b via paper sheet P held between paper sheet holding rollers 261. Next, resistance sensor 26 outputs the current value measured the second time to control unit 21. In the same manner, resistance sensor 26 measures the current value flowing to opposing roller 261b via paper sheet P multiple times. Next, the control unit 21 calculates the electrical resistance of the paper by dividing the voltage applied to the detection roller 261a by the HV unit 262 by the average value of the current values ​​measured multiple times.

[0051] The stiffness sensor 25 and the resistance sensor 26 measure the above-mentioned characteristic information while the transport of the paper is temporarily stopped. Under the control of the control unit 21, the conveying unit 27 discharges the paper sheet that has been measured by each sensor onto the purge tray 271 without conveying it to the image forming device 3.

[0052] The communication unit 28 controls communication between the paper characteristic detection device 2, the paper feed device 1, the image forming device 3, and the post-processing device 4 in the image forming system U. The control unit 21 outputs at least one of the thickness, moisture content, stiffness, and electrical resistance of the paper as the characteristics of the paper to the image forming device 3 via the communication unit .

[0053] (Image forming device) The image forming apparatus 3 forms an image on paper based on image data read from a document and outputs the image, for example. The image forming apparatus 3 forms an image on paper by electrophotography based on image data received from an external device (not shown), and outputs the image. In other words, the image forming apparatus 3 is a multifunction peripheral. The image forming apparatus 3 can be connected to an external device, such as a PC, via a LAN (Local Area Network) or the like.

[0054] The image forming apparatus 3 includes a control unit 301, a document reading unit 302, an operation receiving unit 303, a display unit 304, an image forming unit 305, a storage unit (not shown), a communication unit (not shown), and the like.

[0055] The control unit 301 comprehensively controls the operation of the image forming apparatus 3. The control unit 301 includes a CPU, RAM, etc. The CPU performs various settings and operations related to image formation in response to an operation signal input from an operation reception unit 303 or an instruction signal received by a communication unit.

[0056] The document reading unit 302 reads an image of a document placed on a document platen or an automatic document feeder (ADF). The document reading unit 302 scans and exposes the document using the optical system of a scanning exposure device, and reads the reflected light using a line image sensor to obtain an image signal. The document reading unit 302 then performs processes such as A / D conversion, shading correction, and compression on this image signal to generate image data.

[0057] The operation reception unit 303 receives external input operations from a user or the like. The operation reception unit 303 includes a touch panel provided on the screen of the display unit 304, and various hard keys arranged around the screen of the display unit 304. The operation reception unit 303 converts the received operation content into an operation signal corresponding to the content, and outputs it to the control unit 301. The touch panel may be, for example, a pressure-sensitive type, an electrostatic type, an optical type, or the like.

[0058] The display unit 304 has, for example, a color liquid crystal display, and displays various information based on the control of the control unit 301.

[0059] The image forming unit 305 applies and fixes color materials to paper based on image data to be formed. The control unit 301 determines image formation conditions in the image forming unit 305 based on at least one of the paper thickness, moisture content, stiffness, and electrical resistance of the paper received from the paper characteristic detection device 2. The image forming unit 305 forms an image on the paper based on the image formation conditions. The image forming unit 305 includes four writing units 31, an intermediate transfer belt 32, a secondary transfer roller 33, a fixing unit 34, and the like.

[0060] The four writing units 31 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 32 and form images of the respective colors of C (cyan), M (magenta), Y (yellow), and K (black). The configuration of each writing unit 31 may be the same for each color. For example, the writing unit 31 includes an optical scanning unit 31a, a photosensitive member 31b, a developing unit 31c, a charging unit 31d, a cleaning unit 31e, and a primary transfer roller 31f.

[0061] In each writing unit 31, the charging unit 31d uniformly charges the photoconductor 31b. The optical scanning unit 31a emits a light beam based on the original image data to scan and expose the charged photoconductor 31b, forming an electrostatic latent image. The developing unit 31c supplies a color material such as toner to the electrostatic latent image and develops it, forming an image on the photoconductor 31b.

[0062] The four writing units 31 transfer images formed on the photoconductors 31b onto the intermediate transfer belt 32 in succession, superimposing the images, using their respective primary transfer rollers 31f. Through this transfer (primary transfer), the writing units 31 form images of each color on the intermediate transfer belt 32. The intermediate transfer belt 32 moves around, wound around multiple rollers. After the primary transfer, the cleaning unit 31e removes any color material remaining on the photoconductors 31b.

[0063] The image forming device 3 causes paper to pass the position of the secondary transfer roller 33 in time with the timing at which the image on the rotating intermediate transfer belt 32 reaches the position of the secondary transfer roller 33. The secondary transfer roller 33 has a pair of rollers. One of the rollers is in pressure contact with the intermediate transfer belt 32, and the other roller constitutes one of multiple rollers that wrap around the intermediate transfer belt 32. The image is transferred (secondary transfer) from the intermediate transfer belt 32 onto the paper by the pressure contact of the secondary transfer roller 33.

[0064] The paper onto which the image has been secondarily transferred is transported to the fixing unit 34 where a fixing process is performed. The fixing unit 34 has a pair of fixing rollers that are pressed against each other, at least one of which is heatable. The fixing rollers fix the image to the paper by applying heat and pressure to the paper that passes between the fixing rollers.

[0065] When forming images on both sides of a sheet of paper, the sheet of paper on which an image has been formed and fixed on one side is sent to a reversing path 36 and turned over. The sheet of paper is then returned to a position upstream of the secondary transfer roller 33. When image formation is on only one side or when image formation on both sides is completed, the sheet of paper is discharged from the fixing unit 34 to the post-processing device 4.

[0066] (Post-treatment device) The post-processing device 4 performs post-processing on the paper sheets on which the images have been formed. The post-processing includes, for example, sorting, cutting, stapling, folding, etc. The post-processing device 4 discharges the paper sheets after the post-processing onto a discharge tray E or the like.

[0067] <2. Operation of the image forming system> Next, the operation of the image forming system U will be described. 6 is a flowchart showing the control procedure of the detection control process executed by the control unit 21 of the paper property detection device 2. The control unit 21 executes the detection control process before the start of the image forming operation.

[0068] In this embodiment, the first characteristic of the paper is the moisture content of the paper, and the moisture content sensor 24 functions as a first characteristic detector. The second characteristic of the paper is the electrical resistance of the paper, and the resistance sensor 26 functions as a second characteristic detector. In the detection control process, the control unit 21 controls the second characteristic detection unit based on the detection result of the first characteristic detection unit.

[0069] (Detection control processing) The control unit 21 causes the paper feeder 1 to feed the first sheet from a tray that supplies sheets of paper on which images are to be formed, and transports the first sheet along the first transport path 27M (step A1). Next, the control unit 21 acquires characteristic information (first characteristic information) corresponding to the moisture content of the paper from the moisture content sensor 24 of the paper characteristic detection device 2. Next, the control unit 21 calculates the moisture content of the paper based on the characteristic information, thereby acquiring the moisture content of the paper (step A2). Next, the control unit 21 transports the paper to the second transport path 27S (step A3).

[0070] Next, the control unit 21 acquires characteristic information corresponding to the stiffness of the paper from the stiffness sensor 25. The control unit 21 calculates the stiffness of the paper based on the characteristic information, thereby acquiring the stiffness of the paper (step A4). Next, the control unit 21 determines whether the moisture content of the paper obtained in step A2 is equal to or greater than a predetermined first threshold value (for example, 30%) (step A5). The first threshold value is set in advance. If the moisture content of the paper is less than the first threshold value (step A5; NO), the control unit 21 acquires characteristic information (second characteristic information) corresponding to the electrical resistance of the paper using the resistance sensor 26. The control unit 21 calculates the electrical resistance of the paper based on the characteristic information, thereby acquiring the electrical resistance of the paper (step A6). Next, the control unit 21 causes the paper to be transported along the second transport path 27S and discharged onto the purge tray 271 (step A7), and the detection control process ends.

[0071] On the other hand, if the moisture content of the paper is equal to or greater than the first threshold value (step A5; YES), the control unit 21 moves the detection control process to step A7. That is, when the moisture content of the paper is equal to or greater than the first threshold, the control unit 21 ejects the paper without measuring it with the resistance sensor 26. In other words, the control unit 21 controls the resistance sensor 26 (second characteristic detection unit) not to perform detection according to the detection result of the moisture content sensor 24 (first characteristic detection unit). In this case, the control unit 21 ejects the paper without causing the resistance sensor 26 (second characteristic detection unit) to stop the paper. This prevents a high voltage from being applied to the paper by the resistance sensor 26 when the moisture content of the paper is equal to or greater than the first threshold value, which would cause leakage voltage to be applied to an electrical device in the paper characteristic detection device 2 via the paper, thereby preventing damage to the electrical device.

[0072] <3. Modifications> Although the present embodiment has been described above, the specific configuration is not limited to the above embodiment and can be modified within the scope of the gist of the invention. Modifications of the present embodiment will be described below. In the modifications, the same components as those in the above embodiment will be assigned the same reference numerals and their description will be omitted.

[0073] (Variation 1) FIG. 7 shows a flowchart of the detection control process of the first modification. In the first modification, the first characteristic of the paper is the moisture content of the paper, and the moisture content sensor 24 functions as the first characteristic detector. The second characteristic of the paper is the electrical resistance of the paper, and the resistance sensor 26 functions as the second characteristic detector. In the detection control process of the first modification, the control unit 21 controls the second characteristic detection unit based on the detection result of the first characteristic detection unit.

[0074] (Detection control process of modified example 1) The control unit 21 executes steps B1 to B7 similar to steps A1 to A7 in the above embodiment. If the moisture content of the paper is equal to or greater than the first threshold (step B5; YES), the control unit 21 changes the measurement conditions of the resistance sensor 26 for the characteristic information (second characteristic information) corresponding to the electrical resistance of the paper. That is, the control unit 21 changes the detection conditions of the resistance sensor 26 (second characteristic detection unit) according to the detection results of the moisture content sensor 24 (first characteristic detection unit). Next, the control unit 21 acquires characteristic information from the resistance sensor 26 corresponding to the electrical resistance of the paper measured under the changed measurement conditions. Next, the control unit 21 acquires the electrical resistance of the paper by calculating the electrical resistance of the paper based on the characteristic information (step B8), and proceeds to step B7 of the detection control process. In step B8, the control unit 21 changes the measurement conditions by, for example, reducing the voltage that the HV unit 262 applies to the detection roller 261a from 2000V to 1000V.

[0075] (Variation 2) FIG. 8 shows a flowchart of the detection control process of the second modification. In the second modification, the first characteristic of the paper is the moisture content of the paper, and the moisture content sensor 24 functions as a first characteristic detector. The second characteristic of the paper is the electrical resistance of the paper, and the resistance sensor 26 functions as a second characteristic detector. In the detection control process of the second modification, the control unit 21 controls the second characteristic detection unit based on the detection result of the first characteristic detection unit.

[0076] (Detection control process of modified example 2) The control unit 21 executes steps C1 to C4 similar to steps A1 to A4 in the above embodiment. Next, the control unit 21 determines whether the moisture content of the paper obtained in step C2 is equal to or greater than a predetermined second threshold value (for example, 50%) (step C5). The second threshold value is set in advance. If the moisture content of the paper is less than the second threshold (step C5; NO), control unit 21 changes the measurement conditions of characteristic information (second characteristic information) corresponding to the electrical resistance of the paper measured by resistance sensor 26, according to the moisture content of the paper acquired in step C2. Next, control unit 21 acquires characteristic information corresponding to the electrical resistance of the paper measured under the changed measurement conditions from resistance sensor 26. Next, control unit 21 acquires the electrical resistance of the paper by calculating the electrical resistance of the paper based on the characteristic information (step C6).

[0077] In step C6, the control unit 21 changes the measurement conditions by decreasing the voltage that the HV unit 262 applies to the detection roller 261a as the moisture content of the paper increases. In other words, the control unit 21 decreases the voltage that is applied to the paper when the resistance sensor 26 (second characteristic detection unit) detects characteristic information corresponding to the electrical resistance as the moisture content (amount of moisture) of the paper increases. FIG. 9 shows the relationship between the moisture content of the paper and the voltage (applied voltage) that the HV unit 262 applies to the detection roller 261a.

[0078] Alternatively, in step C6, resistance sensor 26 may measure characteristic information corresponding to the electrical resistance of a single sheet of paper multiple times. In this case, control unit 21 changes the measurement conditions by reducing the number of measurements by resistance sensor 26 for a single sheet of paper as the moisture content of the paper increases. In other words, control unit 21 reduces the number of times that resistance sensor 26 (second characteristic detection unit) detects characteristic information corresponding to the electrical resistance as the moisture content (amount of moisture) of the paper increases. FIG. 10 shows the relationship between the moisture content of the paper and the number of measurements made by the resistance sensor 26 for one sheet of paper.

[0079] Next, the control unit 21 causes the paper to be transported along the second transport path 27S and discharged onto the purge tray 271 (step C7), and the detection control process ends.

[0080] On the other hand, if the moisture content of the paper is equal to or greater than the second threshold value (step C5; YES), the control unit 21 moves the detection control process to step C7. That is, when the moisture content of the paper is equal to or greater than the second threshold value, the control unit 21 ejects the paper without measuring it with the resistance sensor 26.

[0081] (Variation 3) FIG. 11 shows a flowchart of the detection control process of the third modification. In the third modification, the first characteristic of the paper is the moisture content of the paper, and the moisture content sensor 24 functions as the first characteristic detector. The second characteristic of the paper is the stiffness of the paper, and the stiffness sensor 25 functions as the second characteristic detector. In the detection control process of the third modification, the control unit 21 controls the second characteristic detection unit based on the detection result of the first characteristic detection unit.

[0082] (Detection control process of modified example 3) The control unit 21 executes steps D1 to D3 similar to steps A1 to A3 in the above embodiment. Next, the control unit 21 determines whether the moisture content of the paper obtained in step D2 is equal to or less than a predetermined third threshold value (for example, 3%) (step D4). The third threshold value is set in advance. If the moisture content of the paper is greater than the third threshold value (step D4; NO), the control unit 21 acquires characteristic information (second characteristic information) corresponding to the stiffness of the paper from the stiffness sensor 25. The control unit 21 calculates the stiffness of the paper based on the characteristic information, thereby acquiring the stiffness of the paper (step D5). In step D5, the pressing unit 252 drives the motor M1 to move the pressing member 252a once in the positive direction of the X axis. The pressing force detection unit 252b detects the pressing force received from the paper sheet P at this time.

[0083] Next, the control unit 21 executes steps D6 and D7, which are similar to steps A6 and A7 in the above embodiment.

[0084] On the other hand, if the moisture content of the paper is equal to or less than the third threshold value (step D4; YES), control unit 21 changes the measurement conditions of characteristic information corresponding to the stiffness of the paper in stiffness sensor 25. Next, control unit 21 acquires characteristic information corresponding to the stiffness of the paper measured under the changed measurement conditions from stiffness sensor 25. Next, control unit 21 acquires the stiffness of the paper by calculating the stiffness of the paper based on the characteristic information (step D8), and transitions the detection control process to step D6. In step D8, control unit 21 changes the measurement conditions by moving pressing member 252a twice in the positive direction of the X axis, and measures the pressing force received from paper P after the second movement using pressing force detection unit 252b.

[0085] 12A to 13B show examples in which characteristic information corresponding to the stiffness of a sheet is measured by stiffness sensor 25 when the moisture content of the sheet is equal to or less than the third threshold value. FIG. 12A shows a schematic diagram of the sheet P and the stiffness sensor 25 before the first movement of the pressing member 252a in the positive direction of the X axis. If the moisture content of the paper is equal to or less than the third threshold, the paper P becomes electrically charged due to friction between the paper P and the transport roller while the paper P is transported to the stiffness sensor 25. Therefore, as shown in Fig. 12A, when the paper P is held by the paper holding roller 251, a predetermined portion Pb of the paper P adheres to the second transport path 27S. FIG. 12B shows a state in which the pressing member 252a is moved in the positive direction of the X axis in this state, and the pressing member 252a presses the paper P. In this case, the edge Pa of the paper sheet P moves in the direction of the arrow shown in FIG. 12B, and therefore the pressing force detection unit 252b cannot accurately measure the pressing force received from the paper sheet P. Thereafter, the stiffness sensor 25 returns the pressing member 252a to its original position.

[0086] As shown in Fig. 12B, the charge on the paper sheet P is removed by the pressing member 252a coming into contact with the paper sheet P. Therefore, as shown in Fig. 13A, before the pressing member 252a moves a second time in the positive direction of the X axis, the paper sheet P is no longer attached to the second transport path 27S. Therefore, as shown in FIG. 13B, after the second movement of the pressing member 252a, the pressing force detection unit 252b can accurately measure the pressing force received from the paper sheet P.

[0087] As described above, in step D8, the control unit 21 changes the detection operation when detecting characteristic information corresponding to stiffness by the stiffness sensor 25 (second characteristic detection unit) according to the moisture content (moisture content) of the paper.

[0088] (Variation 4) FIG. 15 shows a flowchart of the detection control process of the fourth modification. In the fourth modification, the first characteristic of the paper is the thickness of the paper, and the paper thickness sensor 23 functions as a first characteristic detector. The second characteristic of the paper is the moisture content of the paper, and the moisture content sensor 24 functions as a second characteristic detector. In the detection control process of the fourth modification, the control unit 21 controls the second characteristic detection unit based on the detection result of the first characteristic detection unit.

[0089] (Detection control process of modified example 4) The control unit 21 executes step E1, which is the same as step A1 in the above embodiment. Next, the control unit 21 acquires the paper thickness (first characteristic information) of the paper from the paper thickness sensor 23 (step E2). Next, the control unit 21 determines whether the thickness of the paper sheet obtained in step E2 is equal to or less than a predetermined fourth threshold value (step E3). The fourth threshold value is set in advance. If the paper thickness is greater than the fourth threshold (step E3; NO), the control unit 21 executes steps E4 to E6 similar to steps A2, A3, and A7 in the above embodiment, and ends the detection control process. In this case, the control unit 21 may execute processes similar to steps A5 and A6 in the above embodiment after step E5.

[0090] On the other hand, if the paper thickness is equal to or less than the fourth threshold (step E3; YES), the control unit 21 changes the measurement conditions of the characteristic information (second characteristic information) corresponding to the moisture content of the paper measured by the moisture content sensor 24. Next, the control unit 21 acquires the characteristic information corresponding to the moisture content of the paper measured under the changed measurement conditions from the moisture content sensor 24. Next, the control unit 21 calculates the moisture content of the paper based on the characteristic information, thereby acquiring the moisture content of the paper (step E7), and proceeds to step E5 in the detection control process.

[0091] When the paper thickness is equal to or less than the fourth threshold, the paper tends to vibrate in the vertical direction (the Z-axis direction in Figure 1). In order to accurately measure the characteristic information corresponding to the moisture content of the paper, it is necessary to measure when the vibration has subsided. Therefore, in step E7, the control unit 21 changes the measurement conditions by controlling the moisture percentage sensor 24 so that the timing of measuring the characteristic information corresponding to the moisture percentage of the paper is delayed compared to when the paper thickness is greater than the fourth threshold. In other words, the control unit 21 changes the detection conditions when the moisture percentage sensor 24 (second characteristic detection unit) detects the characteristic information corresponding to the moisture percentage (amount of moisture) of the paper, depending on the paper thickness.

[0092] (others) In the image forming system U of the above embodiment and modified example, the paper characteristic detection device 2 is disposed upstream of the image forming device 3, but this is not limiting. The paper characteristic detection device 2 may also be disposed downstream of the image forming device 3. In this case as well, the control unit 301 of the image forming apparatus 3 determines the image forming conditions based on at least one of the paper thickness, moisture content, stiffness, and electrical resistance of the paper received from the paper property detection device 2.

[0093] In the detection control process of the above embodiment and modified example, the control unit 21 controls the second characteristic detection unit based on the detection result of the first characteristic detection unit, but this is not limited to this. The control unit 21 may also control the first characteristic detection unit based on the detection result of the second characteristic detection unit.

[0094] <4. Effects> As described above, the paper characteristic detection device 2 of this embodiment is disposed on the paper transport path and includes a first characteristic detection unit for detecting first characteristic information corresponding to a first characteristic of the paper. The paper characteristic detection device 2 of this embodiment is arranged on the paper transport path and includes a second characteristic detection unit for detecting second characteristic information corresponding to a second characteristic of the paper. In the paper characteristic detection device 2 of this embodiment, the first characteristic detection unit or the second characteristic detection unit is controlled based on the detection result of the other characteristic detection unit. Therefore, if the moisture content of the paper is equal to or greater than a predetermined value, measurement by the resistance sensor 26 is not performed, or the voltage applied to the paper by the resistance sensor 26 can be reduced. This prevents device failure due to leakage voltage that occurs when detecting the electrical resistance of the paper. In other words, it prevents problems that occur depending on the characteristics of the paper when measuring the characteristics of the paper.

[0095] The paper characteristic detection device 2 of this embodiment is disposed on the upstream or downstream side of an image forming unit 305 that forms an image on a paper sheet. Therefore, in both configurations where the paper characteristic detection device 2 is located upstream of the image forming device 3 and downstream of the image forming device 3, it is possible to prevent the device from failing due to leakage voltage that occurs when detecting the electrical resistance of the paper.

[0096] The paper characteristic detection device 2 of this embodiment is disposed upstream of the image forming unit 305. The image forming conditions in the image forming unit 305 are determined based on at least one of the first characteristic information and the second characteristic information. Therefore, the paper can be transported stably and a high-quality image can be formed under image forming conditions that correspond to the characteristics of the paper.

[0097] In the paper property detection device 2 of this embodiment, the second property detection unit is disposed downstream of the first property detection unit. In the paper property detection device 2 of this embodiment, the second property detection unit is controlled in accordance with the detection result of the first property detection unit. In the paper property detection device 2 of this embodiment, the detection conditions in the second property detection section are changed according to the detection result of the first property detection section. Therefore, when the moisture content of the paper is equal to or greater than a predetermined value, the voltage applied to the paper by the resistance sensor 26 can be reduced, thereby preventing device failure due to leakage voltage that occurs when detecting the electrical resistance of the paper.

[0098] In the paper property detection device 2 of this embodiment, control is performed so that detection by the second property detection unit (resistance sensor 26) is not performed, depending on the detection result of the first property detection unit. Therefore, if the moisture content of the paper is equal to or greater than a predetermined value, it is possible to control the resistance sensor 26 so that measurement is not performed. This makes it possible to prevent device failure due to leakage voltage that occurs when detecting the electrical resistance of the paper.

[0099] In the paper property detection device 2 of this embodiment, when detection is not performed by the second property detection unit, the paper is discharged without the operation of stopping the paper by the second property detection unit.

[0100] In the paper characteristic detection device 2 of this embodiment, the first characteristic and the second characteristic are different from each other. In the paper characteristic detection device 2 of this embodiment, the first characteristic information is information corresponding to the moisture content of the paper, and the second characteristic information is information corresponding to the electrical resistance of the paper. In the paper characteristic detection device 2 of this embodiment, the greater the moisture content (moisture percentage) of the paper, the lower the voltage applied to the paper when the second characteristic detection unit (resistance sensor 26) detects information corresponding to the electrical resistance. Therefore, it is possible to prevent the device from breaking down due to the leakage voltage that occurs when detecting the electrical resistance of the paper.

[0101] In the paper characteristic detection device 2 of this embodiment, the greater the moisture content (moisture percentage) of the paper, the fewer times the second characteristic detection unit detects information corresponding to the electrical resistance. Therefore, it is possible to prevent the device from breaking down due to the leakage voltage that occurs when detecting the electrical resistance of the paper.

[0102] In the paper property detection device 2 of this embodiment, the second property detection unit is disposed downstream of the first property detection unit. In the paper characteristic detection device 2 of this embodiment, the first characteristic information is information corresponding to the moisture content of the paper, and the second characteristic information is information corresponding to the stiffness of the paper. In the paper property detection device 2 of this embodiment, the detection operation when detecting information corresponding to stiffness by the second property detection unit (stiffness sensor 25) is changed according to the moisture content (moisture percentage) of the paper. Therefore, even if the moisture content of the paper is below a predetermined value and the paper is electrically charged and adheres to the second transport path 27S, the stiffness of the paper can be detected accurately.

[0103] In the paper property detection device 2 of this embodiment, the second property detection unit is disposed downstream of the first property detection unit. In the paper characteristic detection device 2 of this embodiment, the first characteristic information is information corresponding to the paper thickness of the paper, and the second characteristic information is information corresponding to the moisture content (moisture percentage) of the paper. In the paper characteristic detection device 2 of this embodiment, the detection conditions when the second characteristic detection unit (moisture percentage sensor 24) detects information corresponding to the moisture content of the paper are changed according to the paper thickness. Therefore, even if the thickness of the paper is less than a predetermined value and the paper is prone to vibration, the moisture content of the paper can be detected accurately.

[0104] The paper characteristic detection device 2 of this embodiment includes a control unit 21 that controls either the first characteristic detection unit or the second characteristic detection unit based on the detection result of the other characteristic detection unit.

[0105] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above embodiment, the control unit 21 of the paper characteristic detection device 2 controls either the first characteristic detection unit or the second characteristic detection unit based on the detection result of the other characteristic detection unit, but this is not limited to this. The control unit 301 of the image forming device 3 may also control either the first characteristic detection unit or the second characteristic detection unit based on the detection result of the other characteristic detection unit.

[0106] In the above embodiment, the control unit 301 of the image forming apparatus 3 acquires at least one of the paper thickness, moisture content, stiffness, and electrical resistance of the paper from the paper characteristic detection device 2 and determines the image formation conditions for the image forming unit 305, but this is not limited to this. The control unit 21 of the paper characteristic detection device 2 may perform the process of determining the image formation conditions for the image forming unit 305. Alternatively, the image forming system U may have a control unit for determining the image formation conditions for the image forming unit 305, separate from the control unit 301 of the image forming apparatus 3.

[0107] In the image forming system U described above, the paper characteristic detection device 2 is located independently between the paper feeder 1 and the image forming device 3, but this is not limited to this. The paper feeder 1 or the image forming device 3 may also be equipped with a paper thickness sensor 23, a moisture content sensor 24, a stiffness sensor 25, and a resistance sensor 26.

[0108] In the above explanation, the storage unit 22, which is composed of a nonvolatile memory such as an HDD or flash memory, has been used as an example of a computer-readable medium for storing the program related to the setting control of the present invention, but this is not limited to this. Other computer-readable media that can be used include other nonvolatile memories such as MRAM, and portable recording media such as CD-ROMs and DVD discs. A carrier wave can also be used as a medium for providing the program data related to the present invention via a communication line. In addition, the specific configurations, contents and procedures of the processing operations, etc. shown in the above embodiments can be modified as appropriate without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0109] 1 Paper feeder 11 Paper tray 2. Paper characteristic detection device 21 Control Unit 22 Memory section 23 Paper thickness sensor 24 Moisture Sensor 25 Stiffness sensor 26 Resistive Sensor 27 Conveyor 271 Purge Tray 27M First conveyor route 27S Second conveyor route 28 Communications Department 3. Image forming device 31 Writing section 31a Optical scanning unit 31b Photoreceptor 31c Developing section 31d Charging part 31e Cleaning Department 31f Primary transfer roller 32 Intermediate transfer belt 33 Secondary transfer roller 34 Fixing section 36 Reversal Path 4. After-treatment device 301 Control Unit 302 Document reading unit 303 Operation reception section 304 Display section 305 Image forming unit E Output tray U Image Forming System

Claims

1. a first characteristic detection unit disposed on a paper transport path for detecting first characteristic information corresponding to a first characteristic of the paper; a second characteristic detection unit disposed on the transport path for detecting second characteristic information corresponding to a second characteristic of the paper; Equipped with The sheet characteristic detection device controls one of the first characteristic detection unit and the second characteristic detection unit based on the detection result of the other characteristic detection unit.

2. 2. The paper characteristic detecting device according to claim 1, which is disposed upstream or downstream of an image forming unit that forms an image on the paper.

3. disposed upstream of the image forming unit, 3. The sheet characteristic detecting device according to claim 2, wherein image forming conditions in the image forming unit are determined based on at least one of the first characteristic information and the second characteristic information.

4. the second characteristic detection unit is disposed downstream of the first characteristic detection unit, 2. The paper characteristic detecting device according to claim 1, wherein the second characteristic detecting section is controlled in accordance with the detection result of the first characteristic detecting section.

5. 5. The paper characteristic detecting device according to claim 4, wherein the detection conditions in the second characteristic detecting section are changed in accordance with the detection result of the first characteristic detecting section.

6. 5. The paper characteristic detecting device according to claim 4, wherein the second characteristic detecting section is controlled not to perform detection in accordance with the detection result of the first characteristic detecting section.

7. The sheet characteristic detection device according to claim 6 , wherein when the second characteristic detection unit does not perform detection, the sheet is ejected without the second characteristic detection unit performing an operation to stop the sheet.

8. The paper characteristic detecting device according to claim 1 , wherein the first characteristic and the second characteristic are different from each other.

9. the first characteristic information is information corresponding to the moisture content of the paper, The paper characteristic detecting device according to claim 1 , wherein the second characteristic information is information corresponding to the electrical resistance of the paper.

10. The sheet characteristic detecting device according to claim 9 , wherein the voltage applied to the sheet when the second characteristic detecting unit detects the information corresponding to the electrical resistance is reduced as the moisture content increases.

11. The sheet characteristic detecting device according to claim 9 , wherein the number of times the second characteristic detecting unit detects the information corresponding to the electrical resistance is reduced as the moisture content increases.

12. the second characteristic detection unit is disposed downstream of the first characteristic detection unit, the first characteristic information is information corresponding to the moisture content of the paper, The paper characteristic detecting device according to claim 1 , wherein the second characteristic information is information corresponding to the stiffness of the paper.

13. The paper characteristic detecting device according to claim 12 , wherein a detecting operation when detecting the information corresponding to the stiffness by the second characteristic detecting unit is changed depending on the moisture content.

14. the second characteristic detection unit is disposed downstream of the first characteristic detection unit, the first characteristic information is information corresponding to a paper thickness of the paper, The paper characteristic detecting device according to claim 1 , wherein the second characteristic information is information corresponding to a moisture content of the paper.

15. The paper characteristic detecting device according to claim 14 , wherein a detection condition when the second characteristic detecting unit detects the information corresponding to the moisture content is changed according to the paper thickness.

16. The paper characteristic detecting device according to claim 1 , further comprising a control unit that controls one of the first characteristic detecting unit and the second characteristic detecting unit based on a detection result of the other characteristic detecting unit.

17. The paper characteristic detection device according to any one of claims 1 to 16, an image forming unit that forms an image on the paper; An image forming system comprising:

18. a first characteristic detection unit disposed on a paper transport path for detecting first characteristic information corresponding to a first characteristic of the paper; a second characteristic detection unit disposed on the transport path for detecting second characteristic information corresponding to a second characteristic of the paper; A computer of a paper characteristic detection device comprising: a program that causes either one of the first characteristic detection unit and the second characteristic detection unit to function as a control unit that controls the other characteristic detection unit based on a detection result of the other characteristic detection unit;

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