Image forming apparatus, method and program for processing information on recording medium

Abstract

To provide an image forming device, a method for processing information concerning a recording medium, and a program which can detect that a recording medium has been replenished, without deteriorating productivity.SOLUTION: An image forming device 1 comprises: conveying parts 71a and 71b which continuously convey a recording medium; obtaining parts 91 and 92 which obtain numerical information concerning the recording medium conveyed by the conveying parts; and a control part 100 that compares first numerical information obtained by the obtaining parts with second numerical information obtained prior to the first numerical information.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multi-function digital multifunction machine called an MFP (Multi Function Peripheral), and further to a method and a program for processing information related to a recording medium. [Background technology]

[0002] In an office environment where multiple users use an image forming apparatus, the users may randomly add different types of recording media to the paper feed tray, causing the information about the recording media in the paper feed tray to become out of date.

[0003] Therefore, it is conceivable to perform a paper type determination each time a recording medium is transported, and to detect a change in paper type due to replenishment.

[0004] Also proposed is an image forming apparatus that, based on the result of the first paper type detection, widens the criteria for determining the paper type from the second time onwards within a range that does not cause problems in paper passing (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-12069 A [Patent Document 2] Patent Publication No. 2021-031200 Summary of the Invention [Problem to be solved by the invention]

[0006] However, a certain amount of data is required to determine the paper type, and it takes time to determine the paper type from this data. For example, if the paper type of the first sheet of a job is determined to be a recording medium that can be transported at high speed, high-speed transport may be set for the second and subsequent sheets of recording media. In this case, there is a risk that the amount of data obtained is insufficient to determine the paper type, and it may not be possible to detect the addition of more recording media. Furthermore, if the transport speed for the second and subsequent sheets of recording media is reduced in order to detect the addition of more recording media, productivity will also decrease.

[0007] This problem cannot be solved by simply widening the range of criteria for determining the paper type from the second time onwards, as in the image forming apparatuses described in Patent Documents 1 and 2.

[0008] An object of the present invention is to provide an image forming apparatus, a method for processing information about a recording medium, and a program that can detect when a recording medium has been replenished without reducing productivity. [Means for solving the problem]

[0009] The above object can be achieved by the following means: (1) a conveying section that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium; an acquisition unit that acquires information regarding characteristics of the recording medium transported by the transport unit; a control unit that determines whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired by the acquisition unit and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired by the acquisition unit; and Equipped with Image forming device. (2) the acquisition unit acquires information regarding characteristics of the first recording medium and information regarding characteristics of the second recording medium during execution of one job; The image forming apparatus described in the preceding paragraph 1, wherein the control unit determines whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium and information regarding the characteristics of the second recording medium obtained during execution of the one job. (3) the second recording medium is a first recording medium of the first job, 3. The image forming apparatus according to claim 2, wherein the first recording medium is a second or subsequent recording medium of the one job. (4) The acquisition unit, A light source; a light receiving unit that detects an amount of light from a recording medium relative to the light from the light source; The light receiving unit is acquiring the light amount for the first recording medium as information regarding a characteristic of the first recording medium; acquiring the amount of light for the second recording medium as information regarding a characteristic of the second recording medium; An image forming apparatus as described in any one of paragraphs 1 to 3, wherein the control unit determines whether the types of the first recording medium and the second recording medium are different based on the acquired information regarding the characteristics of the first recording medium and information regarding the characteristics of the second recording medium. (5) The image forming apparatus according to (4), wherein the light amount is at least one of the amount of transmitted light and the amount of reflected light from a recording medium. (6) a first detection mode in which the transport unit transports the recording medium at a second transport speed, and the acquisition unit acquires information regarding a characteristic of the recording medium transported at the second transport speed; a second detection mode in which the transport unit transports the recording medium at a first transport speed that is faster than the second transport speed, and the acquisition unit acquires information about a characteristic of the recording medium transported at the first transport speed; An image forming apparatus as described in any one of paragraphs 1 to 3, wherein the control unit determines whether the types of the first recording medium and the second recording medium are different based on information regarding the characteristics of the first recording medium acquired in the second detection mode and information regarding the characteristics of the second recording medium acquired in the first detection mode. (7) The image forming apparatus described in paragraph 6, wherein the control unit determines the type of the second recording medium based on information regarding the characteristics of the second recording medium acquired in the first detection mode, and determines the first transport speed for transporting the first recording medium in the second detection mode based on the determined type of the second recording medium. (8) A conveying speed is associated with each of a plurality of types of recording media, The image forming apparatus described in paragraph 7, wherein the control unit determines, from among the multiple transport speeds, the transport speed corresponding to the determined type of the second recording medium as a first transport speed for transporting the first recording medium in the second detection mode. (9) the plurality of types of recording media includes cardboard; 9. The image forming apparatus described in paragraph 8, wherein the second transport speed for transporting the second recording medium in the first detection mode is a transport speed associated with thick paper among the transport speeds associated with the types of the multiple recording media. (10) The image forming device described in paragraph 1, wherein the control unit calculates an amount of change between the information regarding the characteristics of the first recording medium and the information regarding the characteristics of the second recording medium by comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, and determines whether the types of the first recording medium and the second recording medium are different based on the calculated amount of change. (11) The image forming device described in paragraph 1, wherein the control unit calculates a ratio between the information regarding the characteristics of the first recording medium and the information regarding the characteristics of the second recording medium by comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, and determines whether the types of the first recording medium and the second recording medium are different based on the calculated ratio. (12) The image forming device described in paragraph 1, wherein the control unit, in comparing information regarding the characteristics of the first recording medium with information regarding the characteristics of the second recording medium, calculates a rate of change of the information regarding the characteristics of the first recording medium relative to the information regarding the characteristics of the second recording medium, and determines whether the types of the first recording medium and the second recording medium are different based on the rate of change. (13) An image forming apparatus as described in any one of paragraphs 10 to 12, wherein the control unit, in comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, compares approximate information of the information regarding the characteristics of the first recording medium with approximate information of the information regarding the characteristics of the second recording medium. (14) The estimated information on the information on the characteristics of the first recording medium is an average value based on the information on the characteristics of the first recording medium, the estimated information on the information on the characteristic of the second recording medium is an average value based on the information on the characteristic of the second recording medium; The image forming apparatus described in paragraph 13, wherein the control unit, in comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, compares estimated information of the information regarding the characteristics of the first recording medium with estimated information of the information regarding the characteristics of the second recording medium. (15) The control unit obtaining an allowable variation for use in comparing information regarding a characteristic of the first recording medium with information regarding a characteristic of the second recording medium; An image forming apparatus as described in paragraph 10, further comprising: determining whether the types of the first recording medium and the second recording medium are different based on the allowable change amount and the change amount of information regarding the characteristics of the first recording medium relative to the information regarding the characteristics of the second recording medium. (16) When the control unit determines that the first recording medium and the second recording medium are of different types, causing the acquisition unit to acquire information on characteristics of a third recording medium, the third recording medium being transported by the transport unit after the first recording medium is transported, in the first detection mode; 8. The image forming apparatus described in paragraph 7, further comprising: determining the type of the third recording medium based on information regarding the characteristics of the third recording medium; and determining a transport speed of a fourth recording medium, which is transported by the transport unit after the third recording medium, based on the detected type of the third recording medium. (17) An image forming device as described in paragraph 6 above, comprising a first paper passing mode and a second paper passing mode, wherein the control unit changes the timing of executing the first detection mode after determining that the types of the first recording medium and the second recording medium are different in the first paper passing mode and the second paper passing mode. (18) The image forming apparatus according to item 15, further comprising a first paper passing mode and a second paper passing mode, wherein the control unit changes the allowable change amount between the first paper passing mode and the second paper passing mode. (19) The control unit ,before The first recording medium is determined based on information regarding the characteristics of the second recording medium. Recording medium 16. The image forming apparatus according to item 15, wherein the allowable change amount is changed based on the conveying speed. (20) The control unit ,before 16. The image forming apparatus according to item 15, wherein the allowable variation is changed based on a type of the second recording medium detected based on information on characteristics of the second recording medium. (21) An image forming unit that forms an image on a recording medium, When the control unit determines that the first recording medium and the second recording medium are of different types, 2. The image forming apparatus according to claim 1, further comprising: determining an image forming condition for the first recording medium in the image forming section. (22) When the control unit determines that the first recording medium and the second recording medium are of different types, 22. The image forming apparatus according to item 21, further comprising: determining a transport speed for the first recording medium in the image forming section. (23) When the control unit determines that the first recording medium and the second recording medium are of different types, If the paper passing mode is an image quality priority mode, image forming conditions and a conveying speed for the first recording medium in the image forming unit are determined; 23. The image forming apparatus according to item 22, wherein if the speed-priority paper passing mode is selected, image forming conditions for the first recording medium in the image forming section are determined. (24) When the control unit determines that the first recording medium and the second recording medium are of different types, An image forming apparatus as described in paragraph 22 above, in which if it is determined that continuing to transport the first recording medium as is would not be enough to change the image formation conditions and transport speed for the first recording medium, the image forming apparatus temporarily waits for the first recording medium, changes the image formation conditions and transport speed, and then resumes transport. (25) When the control unit determines that the first recording medium and the second recording medium are of different types, If the paper feed mode prioritizes image quality, If it is determined that the change in the image forming conditions and the conveying speed cannot be completed in time even if the first recording medium is conveyed as is, the first recording medium is temporarily put on hold, and the image forming conditions and the conveying speed are changed, and then the conveying is resumed; If it is judged that it will be in time, we will transport it as it is, 23. The image forming apparatus according to item 22, wherein only the image forming conditions are changed if the paper passing mode is one in which priority is given to speed. (26) An image forming apparatus including a conveying unit that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium, acquiring information regarding characteristics of the recording medium transported by the transport unit; a control step of determining whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired in the acquisition step and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired in the acquisition step; A method for processing information relating to a recording medium that executes the above. (27) A computer of an image forming apparatus including a conveying unit that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium, acquiring information regarding characteristics of the recording medium transported by the transport unit; a control step of determining whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired in the acquisition step and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired in the acquisition step; A program for executing. (28) A conveying unit that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium; an acquisition unit that acquires information regarding characteristics of the recording medium transported by the transport unit; a control unit that determines whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired by the acquisition unit and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired by the acquisition unit; and An image forming system comprising: Effect of the Invention

[0010] According to the image forming apparatus and the method for processing information on a recording medium of the present invention, numerical information on a recording medium conveyed by a conveying unit that conveys the recording medium continuously is acquired. The acquired first numerical information is compared with second numerical information acquired before the first numerical information. Therefore, based on the comparison result, it is possible to detect whether the recording medium has been changed, that is, whether or not the recording medium has been replenished. The comparison of the first numerical information and the second numerical information is possible even with a small number of data. In addition, the acquisition and comparison of the first and second numerical information has a faster processing speed than the paper type determination process. Therefore, for the second and subsequent recording media, it is possible to detect whether or not the recording medium has been replenished without reducing the speed for replenishment detection, that is, without reducing productivity.

[0011] According to the program of the present invention, the computer of the image forming device can be caused to execute a process of acquiring numerical information regarding the recording medium being transported and comparing the acquired first numerical information with second numerical information acquired before the first numerical information. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a schematic view of a part of a transport path of a sheet on which an image is printed in an image forming apparatus. [Diagram 2] 1A and 1B are explanatory diagrams of an optical sensor. [Diagram 3] FIG. 2 is an explanatory diagram of an ultrasonic sensor. [Figure 4] FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus. [Diagram 5] 2 is a block diagram illustrating a functional configuration of a control unit of the image forming apparatus. FIG. [Figure 6] FIG. 13 is a diagram showing an example sequence of a first detection mode for detecting and acquiring numerical information of the first recording medium conveyed, and a second detection mode for detecting and acquiring numerical information of recording media subsequent to the first recording medium. [Figure 7] 1 is a table showing the relationship between the type of recording medium and the basis weight. [Figure 8] 11 is a table showing the relationship between the type of recording medium and the conveying speed. [Figure 9] 11 is a table illustrating an example of the relationship between the paper feed speed and the number of sample data. [Figure 10] 11 is a table illustrating an example of the relationship between the process speed and the process conditions before and after switching the type of recording medium. [Figure 11] 11 is a table showing an example of change rate correction coefficients in the cases of speed priority and image quality priority. [Figure 12] 6 is a flowchart showing an example of a paper characteristic detection operation of the image forming apparatus according to the embodiment. [Figure 13] This is a continuation of the flowchart in Figure 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1 is a diagram showing a schematic view of a part of a transport path for a recording medium (hereinafter, the recording medium is also called a sheet or paper) on which an image is printed in an image forming apparatus 1 according to an embodiment of the present invention.

[0015] The image forming apparatus 1 may be, but is not limited to, a copier, a printer, or an MFP, which is a multi-function digital multifunction machine.

[0016] 1, a paper feed section 60 is provided at the bottom of the image forming apparatus 1, and a first paper feed tray 60a, which is a first-stage paper feed cassette at the top, and a second paper feed tray 60b, which is a second-stage paper feed cassette at the bottom, are arranged in the paper feed section 60, and a sheet transport path 8 is formed in the vertical direction, communicating with a paper feed opening 8a of the first paper feed tray 60a and a paper feed opening 8b of the second paper feed tray 60b. A sheet fed to the sheet transport path 8 from the paper feed opening 8a of the first paper feed tray 60a or the paper feed opening 8b of the second paper feed tray 60b is transported upward along the sheet transport path 8 by transport rollers (corresponding to a transport section) 71a, 71b, etc., as shown by arrow A, to a pair of skew correction rollers 72 installed at an upper position of the sheet transport path 8.

[0017] In addition, a manual feed tray (not shown) is provided on the opposite side of the sheet transport path 8 from the first paper feed tray 60a, and a sheet set in the manual feed tray is supplied to the sheet transport path 8 via the manual feed opening 8c.

[0018] The user can open and close the first paper feed tray 60a, the second paper feed tray 60b, and the manual feed tray relative to the image forming apparatus 1. Opening the first paper feed tray 60a and the second paper feed tray 60b means removing the first paper feed tray (paper feed cassette) 60a and the second paper feed tray (paper feed cassette) 60b from the device body for paper replacement, replenishment, etc., and opening the manual feed tray means removing the sheets from the manual feed tray to put it in an unused state.

[0019] On the other hand, closing the first paper feed tray 60a and the second paper feed tray 60b means attaching the first paper feed tray 60a and the second paper feed tray 60b to the device body, and closing the manual feed tray means setting sheets in the manual feed tray and making it ready for use.

[0020] Moreover, opening the first paper feed tray 60a, the second paper feed tray 60b, and the manual feed tray is also referred to as opening the paper feed openings 8a, 8b, and 8c, and closing the first paper feed tray 60a, the second paper feed tray 60b, and the manual feed tray is also referred to as closing the paper feed openings 8a, 8b, and 8c. The opening and closing of the first paper feed tray 60a and the second paper feed tray 60b can be detected by a sensor (not shown), and the opening and closing of the manual feed tray can be detected by the presence or absence of a sheet in the manual feed tray.

[0021] The skew correction roller 72 is a roller for correcting the skew (inclination) of the sheet transported through the sheet transport path 8.

[0022] Between the paper feed opening 8a of the upper first paper feed tray 60a and the skew correction roller 72, two media detection sensors 91, 92 are arranged on the upstream and downstream sides of the sheet transport path 8 in the transport direction. These media detection sensors 91, 92 detect the physical properties of the sheet, which is an example of information about the sheet. The upstream media detection sensor 91 is an optical sensor that detects light irradiated onto the sheet, and the downstream media detection sensor 92 is an ultrasonic sensor that detects ultrasonic waves output toward the sheet. Note that the optical sensor 91 may be arranged on the upstream side and the ultrasonic sensor 92 on the downstream side.

[0023] 2A is an explanatory diagram of the optical sensor 91. The optical sensor 91 is composed of a transmission light source 91a such as an LED, a reflection light source 91b, and a light receiving element 91c such as a photodiode, and detects, as physical property values, the amount of transmitted light 93 emitted from the transmission light source 91a and transmitted through the sheet M transported on the sheet transport path 8, and the amount of reflected light 94 emitted from the reflection light source 91b and reflected by the sheet M, by the light receiving element 91c.

[0024] The transmission light source 91a and the reflection light source 91b of the optical sensor 91 may each include a plurality of different light sources. Fig. 2B shows an optical sensor 91 including such a plurality of light sources. The optical sensor 91 in Fig. 2B includes a blue light source 911a and an infrared light source 912a as the transmission light source 91a. On the other hand, the reflection light source 91b includes a red light source 911b, a blue light source 912b, a purple light source 913b, and an infrared light source 914b.

[0025] In this embodiment, the optical sensor 91 shown in Fig. 2B is used. The light receiving element 91c detects infrared wavelength transmitted light: TIR, blue wavelength transmitted light: TB, ultraviolet wavelength reflected light: RUV, infrared wavelength reflected light: RIR, violet wavelength reflected light: RV, red wavelength reflected light: RR, etc. From the combined output values ​​of the detected transmitted light and reflected light, the control unit 100 described later determines the type of sheet M (basis weight, OHP, recycled paper, coated paper, etc.).

[0026] 3 is an explanatory diagram of the ultrasonic sensor 92. The ultrasonic sensor 92 includes a pair of ultrasonic transmitter 92a and ultrasonic receiver 92b arranged diagonally opposite each other across the sheet transport path 8 in the passing direction of the sheet M (see FIG. 1). The ultrasonic sensor 92 transmits ultrasonic waves from the ultrasonic transmitter 92a to the passing sheet M, and receives the ultrasonic waves that have passed through the sheet M by the ultrasonic receiver 92b. The control unit 100, which will be described later, then determines whether the sheet is a single-sheet or two-sheet paper (envelope) based on the amount of ultrasonic attenuation by the sheet M, thereby detecting the sheet type as information related to the sheet.

[0027] In the following description, the numerical information (amount of received light) as the detection result of transmitted light and reflected light by the optical sensor 91 and the numerical information (amount of received light) as the detection result by the ultrasonic sensor 92 are also referred to as paper characteristics. In this embodiment, as described below, the paper characteristics are acquired for each sheet, and the presence or absence of replenishment is detected from the amount of change in the paper characteristics.

[0028] In this embodiment, the image forming apparatus 1 has a user-specified mode and an automatic detection mode, and the user can select either mode. The user-specified mode is a mode in which the user specifies the sheet type. When the user-specified mode is selected, the media detection sensors 91, 92 do not detect the physical properties of the sheet (acquire paper characteristics) and do not identify the sheet type. When the automatic detection mode is selected, the media detection sensors 91, 92 acquire paper characteristics and identify the sheet type.

[0029] Fig. 4 is a block diagram showing the electrical configuration of the image forming apparatus 1. As shown in Fig. 4, the image forming apparatus 1 includes a control unit 100, a storage device 110, an image reading device 120, an operation panel unit 50, an image forming unit 10, a paper feed unit 60, the above-mentioned optical sensor 91, an ultrasonic sensor 92, a printer controller 150, a network interface (network I / F) 160, etc., which are connected to each other via a system bus 175.

[0030] The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, an S-RAM (Static Random Access Memory) 103, an NV-RAM (Non Volatile RAM) 104, and a clock IC 105.

[0031] The CPU 101 executes an operation program stored in the ROM 102 or the like to centrally control the entire image forming apparatus 1. For example, the CPU 101 controls functions such as a copy function, a printer function, and a scan function to be executable. In particular, in this embodiment, the CPU 101 executes detection of the physical properties of a sheet based on the amount of light detected by the optical sensor 91 and the ultrasonic wave detected by the ultrasonic sensor 92. The CPU 101 then determines the type of sheet based on the detection result, and during printing, automatically sets image forming conditions corresponding to the sheet type based on the determination result to execute printing. The CPU 101 also stores and accumulates the physical properties of the sheet and the determination result of the sheet type detected by the optical sensor 91 and the ultrasonic sensor 92 in the storage device 110. The CPU 101 also executes control processing such as outputting the information to the operation panel unit 50 or an external device.

[0032] The ROM 102 stores the programs executed by the CPU 101 and other data.

[0033] The S-RAM 103 serves as a working area when the CPU 101 executes a program, and temporarily stores programs and data used when the programs are executed.

[0034] The NV-RAM 104 is a non-volatile memory backed up by a battery, and stores various settings related to image formation, the number of pixels of the display unit 54, data of various screens displayed on the display unit 54, and the like.

[0035] The clock IC 105 keeps time and also functions as an internal timer to measure processing times, etc.

[0036] The storage device 110 is made up of a hard disk or the like, and stores programs, various data, and the like. In particular, in this embodiment, it accumulates the detection results of paper characteristics (sheet physical property values) detected by the optical sensor 91 and ultrasonic sensor 92, the sheet type discrimination results, and further detection history. The storage device 110 further stores, as a database, the allowable amount of change in the paper characteristics of the second and subsequent sheets in a job relative to the paper characteristics of the first sheet. It also stores, as a database, a change rate correction coefficient. The allowable amount of change and the change rate correction coefficient will be described later.

[0037] The image reading device 120 includes a scanner and the like, and reads an original document set on a platen glass by scanning it, and converts the read original document into image data.

[0038] The operation panel unit 50 is used when a user issues instructions such as a job and performs various settings on the image forming apparatus 1. The operation panel unit 50 includes a reset key 51, a start key 52, a stop key 53, a display unit 54, a touch panel 55, and the like.

[0039] The reset key 51 is used to reset the settings. The start key 52 is used to start a scan, etc. The stop key 53 is pressed to interrupt an operation, etc.

[0040] The display unit 54 is, for example, a liquid crystal display device, and outputs and displays messages, various operation screens, etc. The touch panel 55 is formed on the screen of the display unit 54, and detects touch operations by the user.

[0041] The image forming unit 10 prints on paper image data of an original read by the image reading device 120, or a copy image generated from print data transmitted from an external terminal device 3 or the like. The image forming unit 10 includes a print engine 18 and a fixing unit 19 that applies heat and pressure to a sheet on which an image has been formed to fix the image. The print engine 18 is made up of hardware components for image formation, such as a photoconductor drum, a charging device, an exposure device, a developing device, a transfer belt, and a transfer roller.

[0042] The network I / F 160 functions as a communication unit for transmitting and receiving data to and from an external device via the network 4. The external device is, for example, an external server, a cloud system, a printer driver of a user's information terminal device, another image forming device, etc.

[0043] 5 is a block diagram for explaining the functional configuration of the control unit 100. The control unit 100 functionally includes a media detection control unit 100a, a sheet type detection control unit 100b, an image formation control unit 100c, a storage unit 100d, and an external communication control unit 100e.

[0044] The media detection control unit 100a operates the media detection sensors, an optical sensor 91 and an ultrasonic sensor 92, to detect the physical properties of the sheet in a first detection mode and a second detection mode, which will be described later. The sheet type detection control unit 100b detects the sheet type based on the detection results by the optical sensor 91 and the ultrasonic sensor 92.

[0045] The image formation control unit 100c controls the image forming unit 10 under image forming conditions corresponding to each sheet type based on the sheet type detected by the sheet type detection control unit 100b, and prints an image on the sheet.

[0046] The storage unit 100d temporarily stores the detection results of the physical property values ​​of the sheet by the optical sensor 91 and the ultrasonic sensor 92. The storage unit 100d further temporarily stores the detection results of the sheet type by the sheet type detection control unit 100b, the detection history, etc. The information stored in the storage unit 100d is transferred to the storage device 110 in FIG. 4, where it is accumulated and updated.

[0047] The external communication control unit 100e corresponds to the network I / F 160 in Fig. 4. The external communication control unit 100e transmits and receives data to and from an external device 3, which is composed of an external server, a management personal computer connected via USB, or another image forming device, etc. It is also possible to transmit information stored in the storage unit 100d to the external device 3.

[0048] Next, the operation of the image forming apparatus 1 will be described, focusing on the control by the control unit 100.

[0049] In this embodiment, the control unit 100 controls the optical sensor 91 and the ultrasonic sensor 92 to detect the physical properties of the sheet transported along the sheet transport path 8 and to detect the sheet type in the first detection mode and the second detection mode.

[0050] The first detection mode is performed on the first sheet to be conveyed. The first sheet to be conveyed may be the sheet that is conveyed first after the first or second paper feed tray 60a, 60b is opened (the tray is removed), and a sheet is replaced, replenished, or added, and the first or second paper feed tray 60a, 60b is closed (the tray is inserted). In the case of a manual feed tray, it may be the sheet that is conveyed first after sheet presence / absence detection changes from absent to present, that is, after the manual feed tray is closed. Alternatively, it may be the sheet that is conveyed first from the paper feed port that does not have sheet type information after the information on the sheet type is reset by turning the power of the image forming apparatus 1 OFF / ON, returning from sleep, or the like. Alternatively, it may be the sheet that is conveyed first from the paper feed port when the media detection function is turned from OFF to ON. Alternatively, it may be the sheet that is conveyed as the first sheet of a print job.

[0051] The information about this first sheet is uncertain. For this reason, in the first detection mode, the sheet is transported at a slow speed so that the detection results can be reflected in the process conditions (image formation conditions). Also, to perform detailed detection, the number of times the sensor reads the sheet surface is increased. This increases the amount of sample data and improves accuracy. The type of sheet in the paper feed tray is determined in the first detection mode, and the fixing temperature and transfer current are determined based on the process conditions (image formation conditions) that match the determined sheet type. From the next sheet onwards, the appropriate transport speed is also selected and printing is performed.

[0052] In addition, the media detection control unit 100a determines the allowable change amount (threshold value) of the paper characteristics acquired by the media detection sensors 91, 92 for the second and subsequent sheets according to the sheet type determined from the paper characteristics of the first sheet detected by the media detection sensors 91, 92.

[0053] On the other hand, the second detection mode is a mode in which the physical property values ​​of sheets other than the first sheet are detected after the type of the first sheet is determined in the first detection mode and before the first sheet feed tray 60a, the second sheet feed tray 60b, or the manual feed tray is opened. Detection in the second detection mode may be performed on all sheets other than the first sheet, or may be performed every several sheets, for example, every other sheet or every fifth sheet, or may be performed at the beginning and end of a job excluding the first sheet.

[0054] In the second detection mode, the conveying speed is set according to the sheet type determined by detection in the first detection mode. For this reason, depending on the sheet type, the conveying speed is faster than in the first detection mode, and the time from when the sheet reaches each media detection sensor 91, 92 until it reaches the skew correction roller 72 is shorter. Therefore, the detection time is also shorter than in the first detection mode. For this reason, the number of samples of the detection results obtained by the media detection sensors 91, 92 is reduced, and sufficient sample data required to determine the sheet type cannot be obtained.

[0055] Therefore, in this embodiment, the media detection control unit 100a judges whether the amount of change in the paper characteristics of the second and subsequent sheets detected by the media detection sensors 91, 92 from the paper characteristics of the first sheet is within the allowable change range. If it is within the allowable change range, the media detection control unit 100a judges that the sheet type has not changed, that is, no additional sheets have been added. If it exceeds the allowable change range, it judges that the sheet type has changed, that is, additional sheets have been added.

[0056] FIG. 6 shows an example of a sequence for the first detection mode and the second detection mode.

[0057] In this example, sheets whose type is cardboard 2 are set in the first paper feed tray 60a. From this state, the first paper feed tray 60a is opened, and 10 sheets of plain paper are added on top of the cardboard 2. Also, after the first paper feed tray 60a is inserted or removed (opened or closed) as shown by the "cassette operation" signal in Fig. 6, four print jobs (1) to (4) each consisting of four sheets are executed as shown by the "print job" signal.

[0058] In the example of Fig. 6, the first sheet fed from the first paper feed tray 60a after the first paper feed tray 60a is inserted or removed (opened or closed) is subjected to detection in the first detection mode. In other words, the first sheet of print job (1) is detected in the first detection mode. As described above, in the first detection mode, the sheet is conveyed at a low speed so that the detection result can be reflected in the process conditions (image formation conditions).

[0059] In this embodiment, in the first detection mode, the thick paper 3 is transported from the paper feed opening of the first paper feed tray 60a to the media detection sensors 91 and 92 at the paper feed speed, and the paper characteristics are detected. The media detection control unit 100a determines the sheet type based on the paper characteristics.

[0060] FIG. 7 shows the relationship between sheet type and basis weight. The basis weight is calculated from the paper characteristics detected by the media detection sensors 91 and 92, and the sheet type is determined. For example, when the basis weight is in the range of 52 to 90, it is determined to be plain paper. In this embodiment, ten sheets of plain paper are spliced ​​onto the thick paper 2. For this reason, the first sheet is determined to be plain paper. Downstream from the skew correction roller 72, the sheet is transported at the process speed of the determined sheet type (plain paper in this case), and image formation is performed under conditions based on the sheet type. The first sheet is transported at the feeding speed of the thick paper 3 so that any sheet type can be fed since the sheet type is indefinite. However, any feeding speed other than the feeding speed of the thick paper 3 may be used as long as the sheet can be fed.

[0061] As described above, the media detection control unit 100a determines the allowable variation (threshold) of the paper characteristics acquired by the media detection sensors 91, 92 for the second and subsequent sheets according to the sheet type determined for the first sheet.

[0062] The second and subsequent sheets are conveyed to the media detection sensors 91 and 92 at a sheet feeding speed corresponding to the sheet type of the first sheet.

[0063] FIG. 8 shows the relationship between the sheet type and the transport speed. FIG. 8 shows the feed speed and process speed for plain paper, thick paper 1, thick paper 2, thick paper 3, and recycled paper. The feed speed is the transport speed from the paper feed openings 8a, 8b, and 8c to the skew correction roller 72. The process speed is the speed from the skew correction roller 72 to image formation. For example, plain paper is sent from the paper feed openings 8a, 8b, and 8c to the skew correction roller 72 at a transport speed of 400 mm / s, and from the skew correction roller 72 at a transport speed of 300 mm / s. For both the feed speed and process speed, thick paper 3 is set to the slowest. The speeds are faster in the order of thick paper 3, thick paper 2, thick paper 1, and plain paper, with plain paper set to the fastest. Recycled paper is set to the same speed as plain paper.

[0064] The media detection sensors 91 and 92 detect the paper characteristics in the second detection mode. When the sheet transport speed is faster, the number of samples taken by the media detection sensors 91 and 92 decreases. This results in a smaller number of sampled data points obtained per light source (LED). Figure 9 illustrates the relationship between the paper feed speed and the number of sampled data points. In Figure 9, when the paper feed speed is 160 mm / s or less at the maximum and 121 mm / s or less at the minimum, the number of sampled data points is 9 per LED. When the paper feed speed is 180 mm / s or more at the maximum and 161 mm / s or more at the minimum, the number of sampled data points decreases. When the paper feed speed is 420 mm / s or more at the maximum and 306 mm / s or more at the minimum, the number of sampled data points is 4.

[0065] These multiple sample data are averaged, for example, and used to determine the sheet type. However, when the sheet conveying speed becomes fast, the number of data required for highly accurate sheet type determination cannot be obtained. For this reason, for the second and subsequent sheets, the media detection control unit 100a compares the paper characteristics, which are numerical information acquired by the media detection sensors 91 and 92, with the paper characteristics, which are numerical information acquired for the first sheet. Specifically, the media detection control unit 100a calculates the amount of change in the numerical value of the acquired paper characteristics relative to the numerical value of the paper characteristics of the first sheet. Then, the media detection control unit 100a judges whether the amount of change is within the range of the allowable amount of change (within a predetermined range) of the paper characteristics acquired according to the sheet type of the first sheet. If it is within the range of the allowable amount of change, it is determined that the sheet types are the same. If it is not within the range of the allowable amount of change, the sheet is added and it is determined that the sheet types are different. The amount of change may be a rate of change or a difference. If the amount of change is a rate of change, the allowable amount of change is also expressed as a rate of change. If the amount of change is a difference, the allowable amount of change is also expressed as a difference.

[0066] An example of a paper characteristic item for calculating the amount of change is a combination of the amount of transmitted light received by the blue light source 911a and infrared light source 912a for transmission of the optical sensor 91 and the amount of reflected light received by the red light source 911b, blue light source 912b, purple light source 913b, and infrared light source 914b for reflection. For example, RUV / RIR, which is the ratio of the amount of reflected light received by the ultraviolet wavelength RUV and the infrared wavelength RIR, and RV / RIR, which is the ratio of the amount of reflected light received by the purple wavelength RV and the infrared wavelength RIR, can be mentioned. Further examples include RR / RIR, which is the ratio of the amount of reflected light received by the red wavelength RR and the infrared wavelength RIR, and (TIR-TB), which is the difference in the amount of transmitted light received by the infrared wavelength TIR and the blue wavelength TB.

[0067] The media detection control unit 100a acquires, for example, RUV / RIR, RV / RIR, RR / RIR, and (TIR-TB) for each sheet from the second sheet onwards. For the first sheet, RUV / RIR, RV / RIR, RR / RIR, and (TIR-TB) are also acquired. All values ​​are acquired as approximate information obtained by averaging multiple sample data. The media detection control unit 100a then compares the acquired numerical values ​​for each item of the second and subsequent sheets with the numerical values ​​of the first sheet. If the sheet type of the second and subsequent sheets is the same as the sheet type of the first sheet, the acquired numerical values ​​for each item will roughly match. In other words, the rate of change is approximately 1, and the difference is approximately 0. If the rate of change exceeds (deviates from) the allowable range, it is determined that the sheet type has been changed (there has been an addition). In this case, the media detection control unit 100a may determine that the sheet type has been changed if all of the items of RUV / RIR, RV / RIR, RR / RIR, and (TIR-TB) exceed the allowable range. Alternatively, it may be determined that the sheet type has been changed if, instead of all items, a predetermined range is exceeded. The media detection control unit 100a may make the determination according to a preset determination method.

[0068] Such detection in the second detection mode is performed for the second to fourth sheets in print job (1) of FIG.

[0069] In the example of FIG. 6, since the sheet type has not changed at the stage of print job (2), the media detection sensors 91 and 92 operate in the second detection mode.

[0070] Similarly, print job (3) operates in the second detection mode, but for the third sheet (the 11th sheet counted from the opening and closing of the first paper feed tray 60a), a sheet of a different sheet type is fed due to replenishment. Because of this, the amount of change in the paper characteristics falls outside the allowable change range, and the media detection control unit 100a determines that the sheet type is different.

[0071] However, in this embodiment, in order to maintain productivity, the remaining printing of print job (3) is performed at the same conveying speed, but the process conditions are switched depending on the sheet type estimated from the amount of change.

[0072] Figure 10 shows an example of the relationship between the process speed and process conditions (fixing temperature and transfer voltage in this example) before and after the sheet type is switched. For example, if it is estimated that the sheet type has switched from plain paper to thick paper 2, the process speed is maintained as for plain paper, while the fixing temperature control is changed from 180°C to 230°C. Also, the transfer voltage setting is changed from 1400V to 1900V. In either case, the process speed is the same before and after the switch.

[0073] By changing the process conditions in this way, even if the process speed is not the optimum condition for the thick paper 2, degradation of image quality can be suppressed.

[0074] 6, the first sheet of print job (4) is detected in the first detection mode and the sheet type is determined to be thick paper 2. For the second and subsequent sheets of print job (4), the sheets are transported at a paper feed speed corresponding to the thick paper 2 detected in the first detection mode, and detection operation is performed in the second detection mode.

[0075] In this embodiment, when a job is sent from an external device, the paper passing mode for that job can be set to either speed priority or image quality priority by the printer driver of the external device or the like.

[0076] When image quality priority is set, if the sheet type is determined to be different in the second detection mode, the conveying speed of the sheet being conveyed is reduced to the conveying speed of the thick paper 3. Then, the paper characteristics may be acquired in the first detection mode to determine the sheet type. After the sheet is made to wait at the skew correction roller 72, the conveying speed is changed to a speed according to the determined sheet type, and the sheet is conveyed, image formed, and discharged. The sheet type detected and determined in this first detection mode becomes the reference value for the next sheet and thereafter. Therefore, the sheet is conveyed at a conveying speed corresponding to this sheet type, and the paper characteristics are acquired for each sheet in the second detection mode.

[0077] Also, when image quality is prioritized, the range of the allowable change amount at which the sheet type is determined to be different in the second detection mode may be changed. Specifically, a threshold value that specifies the range of the allowable change amount is changed so that the sheet type is determined to be different with a small change amount in the paper characteristics. This allows for more accurate sheet type determination and ensures better image quality. Instead of changing the range of the allowable change amount, the amount of change in the detected paper characteristics may be changed so that the sheet type is determined to be different with a small change amount in the paper characteristics. Alternatively, when speed is prioritized, the range of the allowable change amount may be changed to be looser so that the first detection mode is not switched to even if the amount of change is large. Instead of changing the range of the allowable change amount, the amount of change in the detected paper characteristics may be changed.

[0078] Regarding the change in the range of the allowable change amount, the allowable change amount after the change may be set in a table depending on whether the priority is image quality or speed. Alternatively, the allowable change amount as a reference may be set in a table, and the correction coefficient to be multiplied with the allowable change amount as a reference may be set in another table depending on whether the priority is image quality or speed. The allowable change amount in the case of image quality priority may be set as the allowable change amount as the reference, and the allowable change amount in the case of speed priority may be changed. Alternatively, the allowable change amount in the case of speed priority may be set as the allowable change amount as the reference, and the allowable change amount in the case of image quality priority may be changed. FIG. 11 shows an example of the change rate correction coefficient in the case of speed priority and image quality priority. The change rate correction coefficients are respectively specified for basis weight, RUV / RIR, RV / RIR, RR / RIR, and (TIR-TB). The correction coefficient may also be calculated by an arithmetic formula. The basis weight is shown in FIG. 11 because there are many data samples when the sheet conveying speed is slow, and it may be possible to calculate the basis weight.

[0079] In addition, the change in the allowable change amount for determining that the sheet type is different in the second detection mode is not limited to whether the priority is given to image quality or speed, and may be changed according to the sheet type determined in the first detection mode, for example.

[0080] For example, when the sheet type is coated paper, high image quality is generally required, so the range of the allowable change amount is changed so that the sheet type is determined to be different even with a small change amount in the paper characteristics. On the other hand, when the sheet type is plain paper, speed is likely to be prioritized over image quality, so the mode is changed so that the detection mode is not switched to the first detection mode even if the change amount is large. By changing the range of the allowable change amount according to the sheet type determined in the first detection mode, it is possible to detect the change in the paper type with higher accuracy. In this case, the changed range of the allowable change amount itself may be set in a table according to the sheet type determined in the first detection mode. Alternatively, the allowable change amount as a reference may be set in a table, and the correction coefficient to be multiplied according to the sheet type determined in the first detection mode may be set in another table. Alternatively, the correction coefficient may be calculated by an arithmetic formula.

[0081] Further, as the allowable change amount serving as a reference, an allowable change amount for a predetermined sheet type may be set, and the allowable change amount may be increased or decreased depending on the sheet type.

[0082] In addition, the range of the allowable change amount for determining that the sheet type is different in the second detection mode may be changed depending on whether the sheet conveying speed in the second detection mode is fast or slow. When the conveying speed is slow, the number of sample data is large, so that a more accurate change amount can be obtained. For this reason, the allowable change amount is changed so that the sheet type is determined to be different with a small change amount in the paper characteristics. On the other hand, when the conveying speed is fast, the allowable change amount may be changed in a looser direction so that the mode does not transition to the first detection mode even if the change amount is large. In this case, the changed allowable change amount itself may be set in a table according to the conveying speed in the second detection mode. Alternatively, the range of the allowable change amount as a reference may be set in a table, and a correction coefficient to be multiplied by the allowable change amount may be set in another table according to the conveying speed in the second detection mode. Alternatively, the correction coefficient may be calculated by an arithmetic expression.

[0083] In addition, as the allowable change amount serving as the reference, the allowable change amount when the transport speed is fast may be set, and the allowable change amount may be increased or decreased according to the transport speed. FIG. 9 shows an example of the correction coefficient according to the transport speed.

[0084] Furthermore, when a plurality of correction coefficients are applicable, the allowable change amount may be calculated by multiplying the reference allowable change amount by each of the correction coefficients.

[0085] Figures 12 and 13 are flowcharts showing an example of the paper characteristic detection operation of the image forming apparatus 1 according to this embodiment. Figure 13 is a continuation of the flowchart of Figure 12. This paper characteristic detection operation is executed by the CPU 101 of the control unit 100 of the image forming apparatus 1 operating in accordance with an operation program stored in the ROM 102 or the like. In this embodiment, it is assumed that sheets are fed from the first paper feed tray 60a.

[0086] In step S01, the process waits for a print instruction (NO in step S01). When a print instruction is received (YES in step S01), in step S02, it is checked whether there is sheet type information in the paper feed slot. In this example, the first paper feed tray 60a is open or closed, so there is no sheet type information in the paper feed slot (NO in step S02). Therefore, in step S03, the first sheet of the first job is sent from the first paper feed tray 60a to the media detection sensors 91 and 92 at the feeding speed of thick paper 3, and the paper characteristics are detected (acquired) (first detection mode). Then, the sheet type is determined by comparing the acquired paper characteristics with information in a paper type / amount of change database (paper type / amount of change DB) in the storage device 110.

[0087] In step S04, downstream of the skew correction roller 72, the paper is transported at the process speed for the determined sheet type, and image formation is performed under conditions based on the sheet type. If there is sheet type information in the paper feed port (YES in step S02), the process proceeds to step S04, and the speed and process conditions according to the sheet type are set and image formation is performed.

[0088] Next, in step S05, an allowable change amount that is a reference for the change amount of the paper characteristics acquired by the media detection sensors 91, 92 for the second and subsequent sheets is acquired from the paper type / change amount database. Furthermore, in step S06, a change rate correction coefficient for the paper characteristics for the second and subsequent sheets is acquired from the change amount correction value database of the storage device 110 according to the sheet type determined from the paper characteristics of the first sheet detected by the media sensors 91, 92. Furthermore, in step S07, a change rate correction value according to the paper passing mode (image quality priority or speed priority) is acquired from the change amount correction value database.

[0089] In step S08, the allowable change amount for the second and subsequent sheets is calculated. Specifically, the allowable change amount serving as the reference obtained from the database is multiplied by the change rate correction coefficients for the sheet type and the paper feed mode. The obtained value is then set as the allowable change amount for the second and subsequent sheets.

[0090] Next, in step S09, the second and subsequent sheets are transported to skew correction roller 72 at a paper feed speed corresponding to the sheet type determined for the first sheet. During transport, media detection sensors 91 and 92 detect paper characteristics (second detection mode).

[0091] As described above, when the conveying speed increases, the number of samples taken by the media detection sensors 91, 92 decreases, and data required for media determination cannot be obtained. For this reason, in step S10 of Fig. 13, it is determined whether the amount of change in the paper characteristics of the second sheet detected by the media detection sensors 91, 92 relative to the paper characteristics of the first sheet is greater than the allowable change amount set in step S08. The amount of change in the paper characteristics of the second sheet relative to the paper characteristics of the first sheet may be the ratio of the paper characteristics of the second sheet to the paper characteristics of the first sheet, that is, the paper characteristics of the second sheet divided by the paper characteristics of the first sheet. Alternatively, it may be the difference between the paper characteristics of the second sheet and the paper characteristics of the first sheet. Values ​​corresponding to the ratio and difference may also be prepared for the allowable change amount.

[0092] In step S10, if the amount of change in the paper characteristics of the second sheet with respect to the paper characteristics of the first sheet is not greater than the allowable amount of change (NO in step S10), the process proceeds to step S16.

[0093] If the amount of change is greater than the allowable amount of change (YES in step S10), then in step S11, a paper feed port sheet information deletion flag is set. Next, in step S12, it is checked whether the image quality priority mode is selected. If the image quality priority mode is not selected (NO in step S12), then in step S13, only the process conditions are changed to process conditions corresponding to the sheet type that is presumably changed. The process speed is not changed.

[0094] However, in step S14, it is determined whether the process condition change will be completed in time. If it will be completed in time (YES in step S14), the process proceeds to step S16. If it will not be completed in time (NO in step S14), the sheet transport is temporarily suspended, and in step S15, the transport speed and process conditions are changed to correspond to the sheet type that is presumably changed. Thereafter, transport is resumed, and the process proceeds to step S16.

[0095] If the image quality priority mode is selected in step S12 (YES in step S12), the conveying speed and process conditions are changed in step S15 to correspond to the sheet type that is presumably changed, and the process proceeds to step S16. In this case, if it is determined that the conveying speed and process conditions cannot be changed in time, the sheet conveyance is temporarily halted before the changes are made.

[0096] After performing the image forming operation in step S16, it is determined in step S17 whether the job has been completed. If the job has not been completed (NO in step S17), the process returns to step S09 in FIG. 12. If the job has been completed (YES in step S17), it is checked in step S18 whether there is a paper feed port sheet information deletion flag. If there is (YES in step S18), the paper feed port sheet information is deleted in step S19, and the process ends. If there is no paper feed port sheet information deletion flag (NO in step S18), the process ends. [Explanation of symbols]

[0097] 1. Image forming device 3 External device 4. Network 10 Image forming section 50 Operation panel section 54 Display section 60 Paper feed section 60a 1st paper feed tray (1st paper feed cassette) 60b Second paper feed tray (first paper feed cassette) 71a, 71b Conveying rollers (sheet conveying section) 72 Deskew roller 91 Optical sensor (acquisition unit) 91a, 911a, 912a Transmission light source 91b, 911b, 912b, 913b, 914b Reflective light source 91c Light receiving detector 92 Ultrasonic sensor (acquisition part) 91a Ultrasonic transmitter 91b Ultrasonic receiver 100 Control section 100a Media detection control unit 100b Sheet type detection control unit 100c Image formation control unit 100d storage section 100e External communication control unit 110 Storage device

Claims

1. a conveying section that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium; an acquisition unit that acquires information regarding characteristics of the recording medium transported by the transport unit; a control unit that determines whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired by the acquisition unit and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired by the acquisition unit; and Equipped with Image forming device.

2. the acquiring unit acquires information regarding a characteristic of the first recording medium and information regarding a characteristic of the second recording medium during execution of one job; The image forming apparatus of claim 1 , wherein the control unit determines whether the types of the first recording medium and the second recording medium are different based on information regarding the characteristics of the first recording medium and information regarding the characteristics of the second recording medium obtained during execution of the one job.

3. the second recording medium is a first recording medium of the first job, 3. The image forming apparatus according to claim 2, wherein the first recording medium is a second or subsequent recording medium of the one job.

4. The acquisition unit is A light source; a light receiving unit that detects an amount of light from a recording medium relative to the light from the light source; The light receiving unit is acquiring the light amount for the first recording medium as information regarding a characteristic of the first recording medium; acquiring the light amount for the second recording medium as information regarding a characteristic of the second recording medium; An image forming apparatus as described in any one of claims 1 to 3, wherein the control unit determines whether the types of the first recording medium and the second recording medium are different based on the acquired information regarding the characteristics of the first recording medium and information regarding the characteristics of the second recording medium.

5. 5. The image forming apparatus according to claim 4, wherein the light amount is at least one of a light amount of transmitted light and a light amount of reflected light from a recording medium.

6. a first detection mode in which the transport unit transports the recording medium at a second transport speed, and the acquisition unit acquires information regarding a characteristic of the recording medium transported at the second transport speed; a second detection mode in which the transport unit transports the recording medium at a first transport speed that is faster than the second transport speed, and the acquisition unit acquires information about a characteristic of the recording medium transported at the first transport speed; An image forming apparatus as described in any one of claims 1 to 3, wherein the control unit determines whether the types of the first recording medium and the second recording medium are different based on information regarding the characteristics of the first recording medium acquired in the second detection mode and information regarding the characteristics of the second recording medium acquired in the first detection mode.

7. 7. The image forming apparatus of claim 6, wherein the control unit determines the type of the second recording medium based on information regarding the characteristics of the second recording medium acquired in the first detection mode, and determines the first transport speed for transporting the first recording medium in the second detection mode based on the determined type of the second recording medium.

8. A conveying speed is associated with each of a plurality of types of recording media, The image forming apparatus according to claim 7, wherein the control unit determines, from among the plurality of transport speeds, the transport speed corresponding to the determined type of the second recording medium as a first transport speed for transporting the first recording medium in the second detection mode.

9. the plurality of recording medium types includes cardboard; 9. The image forming apparatus according to claim 8, wherein the second transport speed for transporting the second recording medium in the first detection mode is a transport speed associated with thick paper among the transport speeds associated with the types of the plurality of recording media.

10. The image forming apparatus of claim 1, wherein the control unit calculates an amount of change between the information regarding the characteristics of the first recording medium and the information regarding the characteristics of the second recording medium by comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, and determines whether the types of the first recording medium and the second recording medium are different based on the calculated amount of change.

11. 2. The image forming apparatus of claim 1, wherein the control unit calculates a ratio between the information regarding the characteristics of the first recording medium and the information regarding the characteristics of the second recording medium by comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, and determines whether the types of the first recording medium and the second recording medium are different based on the calculated ratio.

12. 2. The image forming apparatus of claim 1, wherein the control unit calculates a rate of change of the information regarding the characteristics of the first recording medium relative to the information regarding the characteristics of the second recording medium when comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, and determines whether the types of the first recording medium and the second recording medium are different based on the rate of change.

13. An image forming apparatus according to any one of claims 10 to 12, wherein the control unit, in comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, compares approximate information of the information regarding the characteristics of the first recording medium with approximate information of the information regarding the characteristics of the second recording medium.

14. the estimated information on the information on the characteristics of the first recording medium is an average value based on the information on the characteristics of the first recording medium; the estimated information on the information on the characteristic of the second recording medium is an average value based on the information on the characteristic of the second recording medium; The image forming apparatus of claim 13, wherein the control unit, in comparing the information regarding the characteristics of the first recording medium with the information regarding the characteristics of the second recording medium, compares approximate information of the information regarding the characteristics of the first recording medium with approximate information of the information regarding the characteristics of the second recording medium.

15. The control unit is obtaining an allowable variation for use in comparing information regarding a characteristic of the first recording medium with information regarding a characteristic of the second recording medium; The image forming apparatus of claim 10 , further comprising: a step of determining whether the types of the first recording medium and the second recording medium are different based on the allowable change amount and the change amount of information regarding the characteristics of the first recording medium relative to information regarding the characteristics of the second recording medium.

16. When the control unit determines that the first recording medium and the second recording medium are of different types, causing the acquisition unit to acquire information regarding a characteristic of a third recording medium, the third recording medium being transported by the transport unit after the first recording medium is transported, in the first detection mode; 8. An image forming apparatus as described in claim 7, wherein the type of the third recording medium is determined based on information regarding the characteristics of the third recording medium, and the transport speed of the fourth recording medium, which is transported by the transport section after the third recording medium, is determined based on the detected type of the third recording medium.

17. 7. The image forming apparatus of claim 6, further comprising a first paper passing mode and a second paper passing mode, wherein the control unit changes the timing of executing the first detection mode after determining that the types of the first recording medium and the second recording medium are different in the first paper passing mode and the second paper passing mode.

18. 16. The image forming apparatus according to claim 15, further comprising a first paper passing mode and a second paper passing mode, wherein the control unit changes the allowable change amount between the first paper passing mode and the second paper passing mode.

19. The image forming apparatus according to claim 15 , wherein the control unit changes the allowable change amount based on a transport speed of the first recording medium determined based on information related to characteristics of the second recording medium.

20. The image forming apparatus according to claim 15 , wherein the control unit changes the allowable variation based on a type of the second recording medium detected based on information about characteristics of the second recording medium.

21. The image forming unit further includes an image forming section for forming an image on a recording medium, When the control unit determines that the first recording medium and the second recording medium are of different types, The image forming apparatus according to claim 1 , further comprising: a step of determining an image forming condition for the first recording medium in the image forming section.

22. When the control unit determines that the first recording medium and the second recording medium are of different types, The image forming apparatus according to claim 21 , further comprising: a conveying speed for conveying the first recording medium in the image forming section.

23. When the control unit determines that the first recording medium and the second recording medium are of different types, If the paper passing mode is an image quality priority mode, image forming conditions and a conveying speed for the first recording medium in the image forming unit are determined; 23. The image forming apparatus according to claim 22, wherein if the speed-priority paper passing mode is selected, image forming conditions for the first recording medium in the image forming section are determined.

24. When the control unit determines that the first recording medium and the second recording medium are of different types, An image forming apparatus as described in claim 22, wherein if it is determined that continuing to transport the first recording medium as is would not be enough to change the image forming conditions and transport speed for the first recording medium, the image forming conditions and transport speed are changed and then transport is resumed, after which the first recording medium is temporarily put on hold.

25. When the control unit determines that the first recording medium and the second recording medium are of different types, If the paper feed mode prioritizes image quality, If it is determined that the image forming conditions and the conveying speed cannot be changed in time even if the first recording medium is conveyed as is, the first recording medium is temporarily put on hold, and the image forming conditions and the conveying speed are changed, and then the conveying is resumed. If it is judged that it will be in time, we will transport it as it is, 23. The image forming apparatus according to claim 22, wherein only the image forming conditions are changed if the paper passing mode is one in which priority is given to speed.

26. An image forming apparatus including a conveying unit that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium, acquiring information regarding characteristics of the recording medium transported by the transport unit; a control step of determining whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired in the acquisition step and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired in the acquisition step; A method for processing information relating to a recording medium that executes the above.

27. A computer of an image forming apparatus including a conveying unit that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium, acquiring information regarding characteristics of the recording medium transported by the transport unit; a control step of determining whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired in the acquisition step and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired in the acquisition step; A program for executing.

28. a conveying section that conveys a first recording medium and conveys a second recording medium ahead of the first recording medium; an acquisition unit that acquires information regarding characteristics of the recording medium transported by the transport unit; a control unit that determines whether the first recording medium and the second recording medium are of different types based on information regarding the characteristics of the first recording medium acquired by the acquisition unit and information regarding the characteristics of the second recording medium, the number of sample data per characteristic being greater than the information regarding the characteristics of the first recording medium acquired by the acquisition unit; and An image forming system comprising:

Images