Image forming apparatus and transport control method

Abstract

To continuously form an image without interrupting image formation on a plurality of recording media.SOLUTION: This image forming device comprises: a conveyance unit that continuously conveys a plurality of recording media; a medium detection unit that detects information about the recording media conveyed by the conveyance unit; an output unit 53 that detects information about a first recording medium conveyed at a first speed by the conveyance unit, and outputs the conveying speed of a recording medium determined on the basis of the detected information; and a conveyance control unit 55 that performs, when the conveying speed output from the output unit 53 is different from the first speed, control so as to set the conveying speed of at least one of a second recording medium and others conveyed by the conveyance unit after the first to be a second speed different from the first speed.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. and Transmission control method By law In particular, the present invention relates to an image forming apparatus that forms an image while conveying a recording medium, and a conveyance control method executed in the image forming apparatus. By law Regarding. [Background technology]

[0002] 2. Description of the Related Art In an image forming apparatus such as an MFP (Multi Function Peripheral), a sheet is taken out one by one from a cassette in which a plurality of sheets are stored, and conveyed, and an image is formed on the sheet being conveyed.

[0003] This MFP detects the paper type of the recording medium and forms an image on the recording medium under image formation conditions according to the paper type. JP2018-106112A describes an image forming device that stores media characteristics of the recording material, and interrupts image formation processing when a first media characteristic of the recording material being conveyed detected by a media sensor differs from a second media characteristic of the recording material at the time of the previous image formation that is stored, and the image formation conditions according to the first media characteristic differ from the image formation conditions according to the second media characteristic.

[0004] However, the image forming apparatus described in JP 2018-106112 A suspends the image forming process, so that the image forming process cannot be continued. This requires the user to perform an operation to remove the obstacle, which requires complicated operations. , print jobs cannot be completed efficiently There are problems such as: [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-106112 A Summary of the Invention [Problem to be solved by the invention]

[0006] One of the objects of the present invention is to To efficiently execute print jobs The object of the present invention is to provide an image forming apparatus capable of performing the above.

[0007] Another object of the present invention is to provide a transport control method that enables continuous image formation on a plurality of recording media without interruption. [Means for solving the problem]

[0009] According to one aspect of the present invention, an image forming apparatus executes a job of forming an image on a recording medium under image forming conditions determined based on information about the recording medium, the image forming apparatus including a paper feed unit that feeds the recording medium stored in a paper feed tray, a transport unit that transports the recording medium fed from the paper feed unit, a media detection unit that detects information about the recording medium transported by the transport unit, and Conveying speed and a conveyance control unit that controls the conveyance of the first recording medium, which is the first recording medium of the first job. of Transport at first speed Let, No. 1 Recording medium The second recording medium is transported later. of Transporting at a second speed that is faster than the first speed To make Control, The media detection unit detects First recording medium a first recording medium detected while the first recording medium is being conveyed at a first speed; Information and , detected while the second recording medium is being transported at a second speed; It is determined that the information on the second recording medium is different from that on the first recording medium. case, First recording medium for the next job of , conveyed at a first speed to make .

[0010] According to another aspect of the present invention, a transport control method is a transport control method executed by an image forming apparatus, the image forming apparatus being an image forming apparatus that executes a job of forming an image on a recording medium under image formation conditions determined based on information about the recording medium, the image forming apparatus being equipped with a paper feed unit that feeds recording media stored in a paper feed tray, a transport unit that transports the recording media fed from the paper feed unit, and a media detection unit that detects information about a plurality of recording media transported by the transport unit, of Transport at first speed and causing the media detection unit to detect information regarding the first recording medium. , No. 1 Recording medium The second recording medium is transported later. at a second speed faster than the first speed, and cause the media detection unit to detect information about the second recording medium. Steps and First recording medium It was determined that the information regarding the second recording medium was different from the information regarding the case, First recording medium for the next job of , conveyed at a first speed to make The method includes the steps of: [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing the appearance of an MFP according to the present embodiment. [Diagram 2] 2 is a block diagram showing an outline of the hardware configuration of the MFP. [Diagram 3] FIG. 2 is a schematic side view showing the internal configuration of an image forming unit and a part of a paper feeding unit. [Figure 4] FIG. 4 is a side view showing a detection area in a conveying path. [Diagram 5] 2 is a diagram showing an example of functions of a CPU of the MFP according to the present embodiment. FIG. [Figure 6] FIG. 13 is a diagram illustrating an example of a type table. [Figure 7] FIG. 13 is a diagram illustrating an example of a speed table. [Figure 8] 10 is a flowchart showing an example of the flow of a transport control process. [Figure 9] 11 is a flowchart showing an example of the flow of a first image forming process. [Figure 10] 10 is a flowchart showing an example of the flow of a second image forming process. [Figure 11] FIG. 13 is a diagram illustrating an example of a time chart. [Figure 12] FIG. 11 is a diagram showing an example of a change in image forming conditions in response to an example of a change in the type of recording medium. [Figure 13] FIG. 13 is a diagram showing an example of a time chart in a first modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In the following description, the same components are given the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. In the following description, an MFP will be described as an example of an image forming apparatus. Furthermore, in the MFP described below, paper such as plain paper, high-quality paper, recycled paper, or photo paper, or stacked paper in which two sheets of paper are stacked on top of each other, such as an envelope, is used as a recording medium on which an image is formed.

[0014] Fig. 1 is a perspective view showing the appearance of an MFP in this embodiment. Fig. 2 is a block diagram showing an outline of the hardware configuration of the MFP. With reference to Figs. 1 and 2, MFP 100 is an example of an image forming device, and includes a main circuit 110, a document reading unit 130 for reading a document, an automatic document feeder 120 for conveying the document to document reading unit 130, an image forming unit 140 for forming an image on a recording medium based on image data, a paper feed unit 150 for supplying the recording medium to image forming unit 140, and an operation panel 160 as a user interface.

[0015] The automatic document feeder 120 automatically transports multiple documents set on the document tray 125 one by one to a document reading position of the document reading unit 130, and discharges the documents from which images formed on the documents have been read by the document reading unit 130 onto the document discharge tray 127. The automatic document feeder 120 is provided with a document detection sensor that detects documents placed on the document tray 125.

[0016] The document reading unit 130 includes a light source that irradiates light and a photoelectric conversion element that receives the light, and scans an image formed on a document placed on the reading surface. When a document is placed on the reading surface, the light irradiated from the light source is reflected by the document, and the reflected light forms an image on the photoelectric conversion element. When the photoelectric conversion element receives the light reflected by the document, it generates image data by converting the received light into an electrical signal. The document reading unit 130 outputs the image data to the CPU 111 provided in the main circuit 110.

[0017] The paper feed section 150 takes out recording media stored in three paper feed trays 151, 152, and 153 and a manual feed tray 154 (see FIG. 3), which will be described later, and conveys the recording media to the image forming section 140.

[0018] Image forming unit 140 is controlled by CPU 111, and forms an image on a recording medium transported by paper feed unit 150 by a well-known electrophotographic method. In the present embodiment, image forming unit 140 forms an image of image data input from CPU 111 on a recording medium transported by paper feed unit 150. The recording medium on which the image has been formed is discharged to paper discharge tray 159. The image data output by CPU 111 to image forming unit 140 includes image data input from document reading unit 130 as well as image data such as print data received from the outside.

[0019] Main circuit 110 includes a CPU (Central Processing Unit) 111 that controls the entire MFP 100, a communication interface (I / F) unit 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, a hard disk drive (HDD) 115 as a large-capacity storage device, a facsimile unit 116, and an external storage device 118. CPU 111 is connected to automatic document feeder 120, document reading unit 130, image forming unit 140, paper feeding unit 150, and operation panel 160, and controls the entire MFP 100.

[0020] The ROM 113 stores a program executed by the CPU 111 or data required to execute the program. The RAM 114 is used as a work area when the CPU 111 executes the program. The RAM 114 also temporarily stores image data continuously sent from the document reading unit 130.

[0021] Operation panel 160 is provided on the top of MFP 100. Operation panel 160 includes display unit 161 and operation unit 163. Display unit 161 is, for example, a liquid crystal display (LCD), and displays an instruction menu for the user, information related to acquired image data, and the like. Note that instead of an LCD, for example, an organic EL (electroluminescence) display can be used as long as it is a device that displays images.

[0022] The operation unit 163 includes a touch panel 165 and a hard key unit 167. The touch panel 165 is of a capacitance type. Note that the touch panel 165 is not limited to the capacitance type, and other types such as a resistive film type, a surface acoustic wave type, an infrared type, and an electromagnetic induction type can be used.

[0023] Touch panel 165 is provided with its detection surface superimposed on the upper or lower surface of display unit 161. Here, the size of the detection surface of touch panel 165 is the same as the size of the display surface of display unit 161. Therefore, the coordinate system of the display surface and the coordinate system of the detection surface are the same. Touch panel 165 detects, on the detection surface, a position indicated by the user on the display surface of display unit 161, and outputs the coordinates of the detected position to CPU 111. Since the coordinate system of the display surface and the coordinate system of the detection surface are the same, the coordinates output by touch panel 165 can be replaced with the coordinates of the display surface.

[0024] The hard key unit 167 includes a plurality of hard keys. The hard keys are, for example, contact switches. The touch panel 165 detects a position on the display surface of the display unit 161 that is designated by the user.

[0025] The communication I / F unit 112 is an interface for connecting the MFP 100 to a network. The communication I / F unit 112 communicates with other computers or data processing devices connected to the network using a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). The network to which the communication I / F unit 112 is connected is a local area network (LAN), and the connection form may be either wired or wireless. The network is not limited to a LAN, and may be a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or the like.

[0026] Facsimile unit 116 is connected to a public switched telephone network (PSTN) and transmits facsimile data to the PSTN or receives facsimile data from the PSTN. Facsimile unit 116 stores the received facsimile data in HDD 115, converts the data into print data that can be printed by image forming unit 140, and outputs the data to image forming unit 140. As a result, image forming unit 140 forms an image of the facsimile data received by facsimile unit 116 on paper. Facsimile unit 116 also converts the data stored in HDD 115 into facsimile data and transmits the data to a facsimile device connected to the PSTN.

[0027] External storage device 118 is controlled by CPU 111, and is equipped with CD-ROM (Compact Disk Read Only Memory) 118A or a semiconductor memory. In this embodiment, an example in which CPU 111 executes a program stored in ROM 113 will be described, but CPU 111 may control external storage device 118 to read a program to be executed by CPU 111 from CD-ROM 118A, store the read program in RAM 114, and execute it.

[0028] The recording medium for storing the program executed by CPU 111 is not limited to CD-ROM 118A, but may be a flexible disk, a cassette tape, an optical disk (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)), an IC card, an optical card, a semiconductor memory such as a mask ROM, or an EPROM (Erasable Programmable ROM). Furthermore, CPU 111 may download a program from a computer connected to the network and store it in HDD 115, or a computer connected to the network may write a program to HDD 115, and the program stored in HDD 115 may be loaded into RAM 114 and executed by CPU 111. The program here includes not only a program that can be directly executed by CPU 111, but also a source program, a compressed program, an encrypted program, and the like.

[0029] FIG. 3 is a schematic side view showing the internal configuration of a part of the image forming unit and the paper feeding unit. Referring to FIG. 3, inside the MFP 100, a main transport path 41 indicated by a thick dotted line is formed so as to basically extend in the vertical direction. The main transport path 41 is a path for guiding a recording medium transported from the paper feeding unit 150 to the paper discharge tray 159 through the image forming unit 140. In the main transport path 41 of this example, a lower end 43 opposite to an upper end 13 located above the image forming unit 140 constitutes an entrance for receiving paper from the paper feeding unit 150. In addition, the upper end 13 of the main transport path 41 constitutes an exit for discharging paper after image formation to the paper discharge tray 159. A paper discharge roller 15 is provided at the upper end 13 of the main transport path 41. The lower end 43 of the main transport path 41 is connected to a plurality of sub-transport paths SP1, SP2, and SP3 of the paper feeding unit 150, which will be described later.

[0030] The paper feed unit 150 includes three paper feed trays 151, 152, and 153 and a manual feed tray 154. The three paper feed trays 151, 152, and 153 are stacked in this order from top to bottom. The manual feed tray 154 is provided on the side wall 101 of the MFP 100 and is located below the image forming unit 140. As shown by a thick dashed line in FIG. 3, in the paper feed unit 150, a sub-transport path SP1 is formed that extends from the uppermost paper feed tray 151 of the three paper feed trays 151, 152, and 153 to the lower end 43 of the main transport path 41. In addition, a sub-transport path SP2 is formed that extends from the manual feed tray 154 to the lower end 43 of the main transport path 41. Furthermore, two sub transport paths 152a, 153a are formed extending from the middle and lower paper feed trays 152, 153, respectively, of the three paper feed trays 151, 152, 153, to the lower end 43 of the main transport path 41. A predetermined length of each of the two sub transport paths 152a, 153a extending from the lower end 43 of the main transport path 41 is a sub transport path SP3 shared by the two sub transport paths 152a, 153a.

[0031] A pickup roller 151p and a paper feed roller 151r are provided corresponding to the paper feed tray 151. The paper feed roller 151r is provided on the sub-transport path SP1. A pickup roller 152p and a paper feed roller 152r are provided corresponding to the paper feed tray 152. The paper feed roller 152r is provided on the sub-transport path 152a. A pickup roller 153p and a paper feed roller 153r are provided corresponding to the paper feed tray 153. The paper feed roller 153r is provided on the sub-transport path 153a. A pickup roller 154p and a paper feed roller 154r are provided corresponding to the manual feed tray 154. The paper feed roller 154r is provided on the sub-transport path SP2. The operation of taking out and transporting a recording medium from each of the paper feed trays 151, 152, 153, and the manual feed tray 154 is the same, so the paper feed tray 151 will be described here as an example.

[0032] One or more recording media are stored in a stacked state in the paper feed tray 151. The paper feed tray 151 has a lift-up mechanism that pushes up the one or more recording media stored therein. The pickup roller 151p is biased downward by an elastic member such as a spring. Therefore, the pickup roller 151p abuts against the uppermost recording medium of the one or more recording media stored in the paper feed tray 151 from above and presses the recording medium from above. As the pickup roller 151p rotates, the frictional force between the pickup roller 151p and the recording medium causes the uppermost recording medium to be sent to the sub-transport path SP1. The recording medium sent to the sub-transport path SP1 is supplied to the main transport path 41 by the paper feed roller 151r as a recording medium.

[0033] As the pickup roller 151p rotates, the topmost recording medium of one or more recording media stored in the paper feed tray 151 is sent to the sub-transport path SP1 due to friction with the pickup roller 151p, while the second recording medium overlapping the topmost recording medium receives a frictional force from the topmost recording medium. For this reason, the second recording medium may be transported together with the topmost recording medium. To prevent this, a separation roller is disposed at a position opposite the pickup roller 151p. The separation roller comes into contact with the second recording medium. The force biasing the pickup roller 151p is adjusted so that the frictional force between the pickup roller 151p and the topmost recording medium and the frictional force between the separation roller and the second recording medium are greater than the frictional force between the topmost recording medium and the second recording medium.

[0034] In the MFP 100, during image formation, a tray that contains a recording medium on which an image is to be formed is selected as a target tray from among the three paper feed trays 151, 152, and 153 and the manual feed tray 154. A pickup roller and a paper feed roller corresponding to the tray selected as the target tray from among the three paper feed trays 151, 152, and 153 and the manual feed tray 154 are operated, and the recording medium is supplied from the tray selected as the target tray to the main transport path 41 through one of the sub-transport paths SP1, SP2, and SP3.

[0035] The image forming section 140 includes image forming units 21Y, 21M, 21C, and 21K for yellow, magenta, cyan, and black, respectively. At least one of the image forming units 21Y, 21M, 21C, and 21K is driven to form an image on a recording medium. When all of the image forming units 21Y, 21M, 21C, and 21K are driven, a full-color image is formed. Print data for yellow, magenta, cyan, and black are input to the image forming units 21Y, 21M, 21C, and 21K, respectively. The image forming units 21Y, 21M, 21C, and 21K differ only in the color of the toner they handle, so here, the image forming unit 21Y for forming a yellow image will be described.

[0036] The image forming unit 21Y includes an exposure head to which yellow printing data is input, a photosensitive drum (image carrier), a charger, a developing device, and a transfer roller 23Y. The exposure head emits a laser beam in response to the received printing data (electrical signal). The emitted laser beam is one-dimensionally scanned by a polygon mirror included in the exposure head to expose the photosensitive drum. The direction in which the photosensitive drum is one-dimensionally scanned is the main scanning direction. The photosensitive drum is charged by the charger, and then irradiated with the laser beam emitted by the exposure head. As a result, an electrostatic latent image is formed on the photosensitive drum. Next, the developing device places toner on the electrostatic latent image to form a toner image. The toner image formed on the photosensitive drum is transferred onto the intermediate transfer belt 27 by the transfer roller 23Y.

[0037] Meanwhile, the intermediate transfer belt 27 is suspended by the drive roller 24 and the roller 24A so as not to slacken. When the drive roller 24 rotates counterclockwise in the figure, the intermediate transfer belt 27 rotates counterclockwise in the figure at a predetermined speed. In conjunction with the rotation of the intermediate transfer belt 27, the roller 24A rotates counterclockwise.

[0038] As a result, the image forming units 21Y, 21M, 21C, and 21K sequentially transfer the toner images onto the intermediate transfer belt 27. The timing at which each of the image forming units 21Y, 21M, 21C, and 21K transfers a toner image onto the intermediate transfer belt 27 is adjusted by detecting a reference mark provided on the intermediate transfer belt 27. As a result, the yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 27.

[0039] In main transport path 41, a timing roller 45, a transfer roller 47, and a fixing roller 49 are arranged in this order at intervals from lower end 43 to upper end 13. The recording medium supplied from paper supply unit 150 to main transport path 41 is sent to timing roller 45.

[0040] Timing roller 45 adjusts the transport state of the recording medium in main transport path 41 so that the recording medium reaches transfer roller 47 at the same timing as the toner image formed on intermediate transfer belt 27 reaches transfer roller 47. The recording medium transported by timing roller 45 is pressed against intermediate transfer belt 27 by transfer roller 47, and yellow, magenta, cyan, and black toner images formed in superposition on intermediate transfer belt 27 are transferred to the recording medium by charging transfer roller 47. The charge amount of transfer roller 47 is adjusted to a value suitable for the basis weight of the recording medium by controlling the voltage applied to transfer roller 47 by CPU 111.

[0041] The recording medium onto which the toner image has been transferred is transported to and heated by fixing rollers 49. This melts the toner and fixes it to the recording medium. Thereafter, the recording medium on which the image has been formed is discharged by discharge rollers 15 from the upper end 13 of the main transport path 41 onto a discharge tray 159. The temperature of the fixing rollers 49 is adjusted to a value suitable for the basis weight of the recording medium by being controlled by the CPU 111.

[0042] MFP 100 in this embodiment is provided with ultrasonic sensor 29 and optical sensor 30 having detection areas within main transport path 41.

[0043] The optical sensor 30 includes a light emitting unit 30a and a light receiving unit 30b, and is a transmissive type. The optical sensor 30 is disposed between the lower end 43 of the main transport path 41 and the timing roller 45, at a position upstream of the ultrasonic sensor 29. The optical sensor 30 is disposed such that the light emitting unit 30a and the light receiving unit 30b face each other across the main transport path 41. The optical sensor 30 detects the recording medium in the area in the main transport path 41 between the light emitting unit 30a and the light receiving unit 30b. The optical sensor 30 outputs a transmittance indicating the ratio of the amount of light received by the light receiving unit 30b to the amount of light irradiated by the light emitting unit 30a. Note that, although a transmissive type optical sensor is shown here as an example, it may be a reflective type. Also, a transmissive optical sensor and a reflective optical sensor may be combined. The optical sensor 30 enables detection of basis weight.

[0044] The ultrasonic sensor 29 includes an ultrasonic transmitter 29a and an ultrasonic receiver 29b, and is a transmission type. The ultrasonic sensor 29 is disposed between the lower end 43 of the main transport path 41 and the timing roller 45, at a position downstream of the optical sensor 30. The ultrasonic sensor 29 includes the ultrasonic transmitter 29a and the ultrasonic receiver 29b, which are disposed facing each other across the main transport path 41. The ultrasonic transmitter 29a includes a piezoelectric element and a drive circuit for the piezoelectric element, and transmits ultrasonic waves. The ultrasonic receiver 29b includes a piezoelectric element and a detection circuit for detecting an electromotive force generated in the piezoelectric element, and detects an electromotive force generated in the piezoelectric element by the ultrasonic waves transmitted from the ultrasonic transmitter 29a. The area in the main transport path 41 between the ultrasonic transmitter 29a and the ultrasonic receiver 29b is the detection area.

[0045] The ultrasonic sensor 29 causes the ultrasonic transmitter 29a to transmit ultrasonic waves of a predetermined volume to the detection area. When the recording medium moves across the detection area while the ultrasonic transmitter 29a transmits ultrasonic waves to the detection area, the ultrasonic waves hit a part of the moving recording medium. At this time, a part of the ultrasonic waves that hit the recording medium passes through the recording medium, and the rest of the ultrasonic waves are absorbed by the recording medium or reflected from the recording medium. The ultrasonic receiver 29b receives the ultrasonic waves that have passed through the recording medium, and outputs a signal according to the volume of the received ultrasonic waves to the CPU 111. Here, the ultrasonic sensor 29 outputs a value indicating the attenuation of the ultrasonic waves. The value indicating the attenuation of the ultrasonic waves is an attenuation rate here. The attenuation rate indicates the ratio of the volume of the ultrasonic waves that pass through the recording medium to the volume of the transmitted ultrasonic waves. The value indicating the attenuation of the ultrasonic waves may be a value obtained by subtracting the received volume from the transmitted volume.

[0046] The attenuation rate of ultrasonic waves varies depending on the basis weight of the paper, and there is a predetermined relationship between the basis weight of ultrasonic waves and the basis weight of the paper. The greater the basis weight of the paper, the greater the attenuation rate of ultrasonic waves. Therefore, by determining the relationship between the basis weight of the paper and the attenuation rate of ultrasonic waves through experiments or the like, the basis weight of the paper can be determined from the attenuation rate of ultrasonic waves.

[0047] There is a significant difference in the attenuation rate of ultrasonic waves between paper and stacked paper. This is because stacked paper is made up of two sheets of paper overlapping each other. When two sheets of paper overlap, there is a gap between the two sheets, so the attenuation rate of ultrasonic waves by stacked paper is greater than the attenuation rate of ultrasonic waves by a single sheet of paper. rate The attenuation rate of two sheets of paper with the smallest basis weight stacked on top of each other is smaller than that of the paper with the largest basis weight. This makes it possible to detect the presence or absence of voids from the ultrasonic attenuation rate.

[0048] Also, the presence or absence of a recording medium may be detected from the attenuation rate of ultrasonic waves. Therefore, the position of the recording medium may be detected based on the output value of ultrasonic sensor 29. In this way, ultrasonic sensor 29 can function as a position detection sensor that detects the position of the recording medium.

[0049] Combining the ultrasonic sensor 29 with the optical sensor 30 not only makes it possible to determine the type of recording medium, but also to simultaneously detect the type and basis weight of the recording medium. This improves convenience. If the type of recording medium is stored in the RAM 114, the optical sensor 30 may be used as a timing sensor to detect the presence or absence of paper. Furthermore, the detection of basis weight by the optical sensor 30 and the detection of the overlapping state by the ultrasonic sensor 29 can be performed in parallel.

[0050] Fig. 4 is a side view showing a detection area on the transport path. In Fig. 4, in order to facilitate understanding of the shapes of the main transport path 41 and the multiple sub-transport paths SP1, SP2, and SP3 and their positional relationships, the sub-transport paths SP1 and SP2 are hatched in two different ways, and the main transport path 41 and the sub-transport path SP3 are hatched in two different ways. Also shown is a portion of the recording medium Pa moving on the main transport path 41. Here, an example is shown in which the recording medium Pa is fed individually.

[0051] As shown by the dotted line in Fig. 4, the ultrasonic sensor 29 is disposed to have a detection area DA1 within the main transport path 41. The detection area DA1 of the ultrasonic sensor 29 extends in a direction intersecting the traveling direction of the recording medium Pa and intersecting the recording medium Pa moving along the main transport path 41. In the detection area DA1, a target position TP1 is set at a position spaced a predetermined distance from the ultrasonic transmitter 29a along a line connecting the ultrasonic transmitter 29a and the ultrasonic receiver 29b. The target position TP1 is an ideal position that the recording medium Pa moving along the main transport path 41 should pass through in the detection area DA1 in order to detect the attenuation rate.

[0052] The optical sensor 30 is disposed so as to have a detection area DA2 within the main transport path 41. The detection area DA2 of the optical sensor 30 extends in a direction intersecting the traveling direction of the recording medium Pa and intersecting the recording medium Pa moving along the main transport path 41. In the detection area DA2, a target position TP2 is set at a position spaced a predetermined distance from the light-emitting unit 30a along a line connecting the light-emitting unit 30a and the light-receiving unit 30b. The target position TP2 is an ideal position where the recording medium Pa moving along the main transport path 41 should pass in the detection area DA2 in order to detect the transmittance.

[0053] Fig. 5 is a diagram showing an example of functions of the CPU of the MFP in the present embodiment. The functions shown in Fig. 5 are realized by CPU 111 included in MFP 100 as a result of CPU 111 executing a transport control program stored in ROM 113, HDD 115, or CD-ROM 118A. Referring to Fig. 5, CPU 111 includes a media sensor control unit 51, an output unit 53, a transport control unit 55, a job execution unit 56, and an image formation control unit 57.

[0054] The media sensor control unit 51 controls the ultrasonic sensor 29 and the optical sensor 30. The media sensor control unit 51 controls the ultrasonic sensor 29 and acquires the attenuation rate output by the ultrasonic sensor 29 while the recording medium passes through the detection area DA1. The media sensor control unit 51 controls the optical sensor 30 and acquires the transmittance output by the optical sensor 30 while the recording medium passes through the detection area DA2. The media sensor control unit 51 outputs the attenuation rate and the transmittance to the output unit 53.

[0055] The output unit 53 receives the attenuation rate and the transmittance from the media sensor control unit 51. The output unit 53 determines a transport speed based on the attenuation rate and the transmittance, and outputs the determined transport speed to the transport control unit 55. The output unit 53 includes a type determination unit 61 and a transport speed determination unit 63.

[0056] The type determination unit 61 determines the type of recording medium based on the transmittance and attenuation rate input from the media sensor control unit 51, and outputs the determined type of recording medium to the transport speed determination unit 63. The types of recording medium include paper and overlapped paper. Paper includes plain paper, high-quality paper, recycled paper, and photo paper. Overlapped paper refers to a type in which two or more sheets of paper are overlapped, such as an envelope. The attenuation rates of paper and overlapped paper are obtained by experimentation to determine a threshold value, and the type determination unit 61 compares the attenuation rate of the ultrasonic wave input from the media sensor control unit 51 with the threshold value to determine whether the type of recording medium is paper or overlapped paper. Specifically, the type determination unit 61 determines that the recording medium is overlapped paper if the attenuation rate of the ultrasonic wave input from the media sensor control unit 51 is equal to or lower than the threshold value, and determines that the recording medium is paper if the attenuation rate is greater than the threshold value.

[0057] Furthermore, the type determination unit 61 Recording medium When determining that the type of recording medium is paper, the basis weight of the recording medium is detected based on the transmittance. The type determination unit 61 obtains the relationship between the transmittance and the basis weight in advance by experiment or simulation, and stores the obtained relationship, thereby determining the basis weight from the transmittance based on the relationship. In this embodiment, a table or an arithmetic expression that correlates the transmittance and the basis weight is stored in the HDD 115. Furthermore, the type determination unit 61 determines the type of recording medium from the determined basis weight by referring to a table that defines the relationship between the type of recording medium and the basis weight. The type determination unit 61 outputs the type of recording medium to the transport control unit 55, and outputs the basis weight to the image formation control unit 57.

[0058] Fig. 6 is a diagram showing an example of a type table. Referring to Fig. 6, the type table includes type records including a type item, a grammage lower limit item, and a grammage upper limit item, and associates the type of recording medium with the grammage. The type of recording medium is set in the type item, the minimum grammage value of the recording medium of the type set in the type item is set in the grammage lower limit item, and the maximum grammage value of the recording medium of the type set in the type item is set in the grammage upper limit item. high The value is set.

[0059] The type record defines the minimum and maximum values ​​of the basis weight of each recording medium of type plain paper, thick paper 1, thick paper 2, and thick paper 3. The basis weight of the recording medium increases in the order of type plain paper, thick paper 1, thick paper 2, and thick paper 3. The minimum and maximum basis weight of a recording medium of type "plain paper" is 52 g / m 2 and 90 g / m 2 The basis weight of the recording medium of type "thick paper 1" is set to 91 g / m 2 and 157 g / m 2 The basis weight of the recording medium of type "thick paper 2" is set to 158 g / m 2 and 209 g / m 2 The basis weight of the recording medium of type "thick paper 3" is set to 210 g / m 2 and 300 g / m 2 are set to

[0060] Returning to FIG. 5, the conveying speed determination unit 63 receives the type of recording medium from the type determination unit 61. Record The transport speed of the recording medium is determined based on the type of medium. The transport speed of the recording medium is predetermined for each type of recording medium. In this embodiment, a speed table in which a transport speed is associated with each of a plurality of types of recording medium is stored in HDD 115. The transport speed determination unit 63 refers to the speed table to determine the transport speed corresponding to the type of recording medium. The transport speed determination unit 63 includes an initial speed determination unit 65 and a medium speed determination unit 67.

[0061] FIG. 7 is a diagram showing an example of a speed table. Referring to FIG. 7, the speed table includes a speed record including a type item and a transport speed item, and associates the type of recording medium with the transport speed. The type of recording medium is set in the type item, and the transport speed of the recording medium is set in the transport speed item. The speed record determines the transport speed of each of the recording media types: plain paper, thick paper 1, thick paper 2, and thick paper 3. The transport speed of the recording media is slower in the order of plain paper, thick paper 1, thick paper 2, and thick paper 3. The transport speed is set to 300 mm / s for the recording medium type "plain paper". The transport speed is set to 170 mm / s for the recording medium type "thick paper 1". The transport speed is set to 140 mm / s for the recording medium type "thick paper 2". The transport speed is set to 120 mm / s for the recording medium type "thick paper 3".

[0062] Returning to FIG. 5, the initial speed determination unit 65 determines a first speed as the conveying speed, and outputs the conveying speed determined as the first speed to the conveying control unit 55. Here, the minimum value of the conveying speeds determined for each of the multiple types of recording media is used as the first speed. The initial speed determination unit 65 determines the conveying speed as the first speed at a predetermined timing. The predetermined timing includes a first timing after the power supply to the MFP 100 is turned on, a second timing after the opening and closing of a tray that supplies a recording medium among the paper feed trays 151, 152, and 153 is detected, and a third timing after a print job is completed at which the transmittance and attenuation rate are changed by a predetermined value or more by the media sensor control unit 51 after the type of recording medium is determined by the type determination unit 61 from the transmittance and attenuation rate corresponding to the type of recording medium determined up to that point.

[0063] The type of recording medium is determined by the type determination unit 61 based on the transmittance and attenuation rate detected by the media sensor control unit 51 for the recording medium transported at the transport speed determined as the first speed by the initial speed determination unit 65. The media speed determination unit 67 determines the transport speed based on the type of recording medium determined by the type determination unit 61 for the recording medium transported at the transport speed determined as the first speed, and outputs the determined transport speed to the transport control unit 55.

[0064] The job execution unit 56 executes a print job and generates print data used by the image forming unit 140 to form an image. The print job defines a process for forming an image on a plurality of recording media. When executing a print job, the job execution unit 56 generates print data based on data to be subjected to image formation according to print conditions. The image formation control unit 57 executes a print job, for example, when the communication I / F unit 112 receives a print job from an external computer. The print job is described in, for example, PJL (Printer Job Language) or PCL (Printer Control Language), and includes print conditions and data to be subjected to image formation. Furthermore, the job execution unit 56 executes a job designated by the user when the user operates the operation unit 163. The job designated by the user includes print conditions and data to be subjected to image formation. The data to be subjected to image formation is data designated by the user. The data designated by the user includes image data output by the document reading unit 130 after reading a document, data stored in the HDD 115, and data stored in an external computer.

[0065] The printing data is, for example, data in a bitmap format. The printing data corresponds to the size of the paper on which the image is to be formed, and defines the image to be formed on the paper by a plurality of pixel values. The printing data includes four pieces of data corresponding to yellow, magenta, cyan, and black, respectively. Therefore, when the printing data consists of a plurality of pages, the printing data includes four pieces of data corresponding to yellow, magenta, cyan, and black, respectively, for each of the plurality of pages.

[0066] The job execution unit 56 outputs the print conditions to the conveyance control unit 55 and the image formation control unit 57, and outputs the print data to the image formation control unit 57. The image formation control unit 57 controls the image forming unit 140 to form an image of the print data according to the print conditions. The image formation control unit 57 receives the basis weight of the recording medium from the type determination unit 61. The conveyance control unit 55 controls the image forming unit 140 based on the print data and the basis weight so that the transfer roller 47 is charged to a potential suitable for transferring the toner image formed on the intermediate transfer belt 27 to the recording medium to be subjected to image formation. The image formation control unit 57 also determines the image formation conditions based on the basis weight, and forms an image according to the image formation conditions. For example, when the basis weight of the recording medium is large, the charge amount of the transfer roller 47 is set higher, and the temperature of the fixing roller 49 is set higher. On the other hand, when the basis weight of the recording medium is small, the charge amount of the transfer roller 47 is set lower, and the temperature of the fixing roller 49 is set lower.

[0067] The transport control unit 55 controls the paper feed unit 150 to transport paper stored in one of the three paper feed trays 151, 152, and 153 and the manual feed tray 154 as a recording medium. The transport control unit 55 selects a tray determined by the print conditions as a target tray from among the three paper feed trays 151, 152, and 153 and the manual feed tray 154. The transport control unit 55 controls a pickup roller and a paper feed roller for supplying paper from the target tray to the image forming unit 140. For example, the transport control unit 55 rotates the pickup roller 151p and the paper feed roller 151r when the paper feed tray 151 is selected as the target tray. In addition, the transport control unit 55 rotates the pickup roller 152p and the paper feed roller 152r when the paper feed tray 152 is selected as the target tray. In addition, the transport control unit 55 rotates the pickup roller 153p and the paper feed roller 153r when the paper feed tray 153 is selected as the target tray. In addition, when the manual feed tray 154 is selected as the target tray, the transport control unit 55 controls the pickup roller 15 4 p and feed roller 15 4By this control, the recording medium is transported from one of the paper feed trays 151, 152, 153 and the manual feed tray 154 to the main transport path 41.

[0068] The transport control unit 55 receives the transport speed from the output unit 53. The transport control unit 55 controls the paper feed unit 150 to transport the recording medium. The transport control unit 55 outputs the transport speed at which the recording medium is transported to the image formation control unit 57. When the image formation control unit 57 inputs print conditions for forming an image of multiple pages, the transport control unit 55 transports multiple recording media continuously. The transport control unit 55 transports the first recording medium of the number of recording media to be printed determined by the print conditions at a first speed. In this embodiment, the first speed is the transport speed input from the initial speed determination unit 65.

[0069] The conveyance control unit 55 receives a signal from the medium speed determination unit 67 during the conveyance of the first recording medium. Transport A feed speed is input. The transport speed input from the medium speed determination unit 67 while the first recording medium is being transported is determined based on the attenuation rate and transmittance acquired by the media sensor control unit 51 from the first recording medium. When the transport speed input from the medium speed determination unit 67 while the first recording medium is being transported is a second speed different from the first speed, the transport control unit 55 transports the second recording medium at the second speed. The second speed is a transport speed input from the medium speed determination unit 67 and is a speed different from the initial value. Therefore, the second speed is faster than the first speed. The transport control unit 55 transports the second and subsequent recording media of the number of recording media to be printed determined by the print conditions at the second speed. Also, the transport control unit 55 transports the second and subsequent recording media of the number of recording media to be printed determined by the print conditions at the second speed even if the transport speed input from the medium speed determination unit 67 is different from the second speed while the transport control unit 55 transports the second and subsequent recording media of the number of recording media to be printed determined by the print conditions at the second speed.

[0070] The transport control unit 55 adjusts the transport speed of the recording medium by controlling the rotation speed of the pickup roller, the paper feed roller, timing roller 45, transfer roller 47, fixing roller 49 and paper discharge roller 15 of the paper feed unit 150.

[0071] The media sensor control unit 51 includes a sampling count determination unit 59. The sampling count of the ultrasonic sensor 29 is the number of times that the ultrasonic sensor 29 transmits and detects ultrasonic waves to output the attenuation rate. The more the sampling count, the more the power consumed by the ultrasonic sensor 29 increases, but the accuracy of the attenuation rate output by the ultrasonic sensor 29 improves. Conversely, the smaller the sampling count, the less the power consumed by the ultrasonic sensor 29 decreases, but the accuracy of the attenuation rate output by the ultrasonic sensor 29 decreases. The sampling count of the optical sensor 30 is the number of times that the optical sensor 30 irradiates and receives light to output the transmittance. The more the sampling count, the more the power consumed by the optical sensor 30 increases, but the accuracy of the transmittance output by the optical sensor 30 improves. Conversely, the smaller the sampling count, the less the power consumed by the optical sensor 30 decreases, but the accuracy of the transmittance output by the optical sensor 30 decreases. The sampling count determination unit 59 determines the sampling count to be the normal count when the first recording medium of the number of prints determined by the print conditions is transported by the transport control unit 55, and determines the sampling count to be a count smaller than the normal count when the second or subsequent recording medium is transported.

[0072] The type determination unit 61 receives the attenuation rate and transmittance for each of the recording media, the number of which is the same as the number of prints defined by the print conditions, from the media sensor control unit 51. The type determination unit 61 determines the type for each of the recording media, the number of which is the same as the number of prints defined by the print conditions, outputs the basis weight to the image formation control unit 57, and outputs the type of the recording medium to the media speed determination unit 67.

[0073] The type determination unit 61 may determine the types of the first recording medium and any one of the second and subsequent recording media among the recording media of the same number as the number of prints determined by the print conditions. In this case, the type determination unit 61 only needs to determine the types of two recording media, so the load is reduced. In addition, in this case, the media sensor control unit 51 only needs to detect the attenuation rate and transmittance of the first recording medium and any one of the second and subsequent recording media. This allows the power consumption of the optical sensor 30 and the ultrasonic sensor 29 to be reduced.

[0074] FIG. 8 is a flowchart showing an example of the flow of a transport control process. The transport control process is a process executed by CPU 111 included in MFP 100 as CPU 111 executes a transport control program. With reference to FIG. 8, CPU 111 included in MFP 100 sets an initialization flag to ON (step S01), and the process proceeds to step S02. In the next step S02, a first speed is set as the set speed, and the process proceeds to step S02. The set speed is a transport speed at which paper feed unit 150 transports the recording medium. Therefore, paper feed unit 150 transports the recording medium at the set speed. The first speed is a value that is predetermined as an initial value. Here, the first speed is the minimum value of the transport speeds that are respectively determined for a plurality of types of recording media.

[0075] In step S03, it is determined whether or not a print job has been accepted. The process waits until the print job is accepted (NO in step S03), and if the print job is accepted (YES in step S03), the process proceeds to step S04. In step S04, the first image forming process is executed, and the process proceeds to step S04.

[0076] Fig. 9 is a flow chart showing an example of the flow of the first image forming process. Referring to Fig. 9, CPU 111 starts conveying the recording medium (step S21) and proceeds to step S22. In this case, since the set speed is set to the first speed, the recording medium is conveyed at the first speed. The conveying path along which paper feed unit 150 conveys the recording medium at the first speed is a path from any one of paper feed trays 151, 152, 153 and manual feed tray 154 to timing roller 45.

[0077] In step S22, the transmittance and the attenuation rate are acquired, and the process proceeds to step S23. CPU 111 controls ultrasonic sensor 29 to acquire the attenuation rate of ultrasonic waves passing through the recording medium, and controls optical sensor 30 to acquire the transmittance of light passing through the recording medium. Furthermore, ultrasonic sensor 29 outputs the attenuation rate measured at a normal number of sampling times, and optical sensor 30 outputs the transmittance measured at a normal number of sampling times.

[0078] In step S23, the type of recording medium is determined, and the process proceeds to step S24. From the attenuation rate, it is determined whether the recording medium is an envelope or paper. Also, from the transmittance, the basis weight of the recording medium is determined, and the type corresponding to the basis weight is determined.

[0079] In step S24, the media speed is determined and the process proceeds to step S25. The media speed is a recording medium transport speed that is predetermined for the paper type. In step S25, it is determined whether the media speed is the same as a first speed. If the media speed is the same as the first speed, the process proceeds to step S26, otherwise the process proceeds to step S27.

[0080] In step S27, the media speed is set to the second speed, and the process proceeds to step S28. In step S28, the set speed is set to the second speed, and the process proceeds to step S26.

[0081] In step S26, an image is formed on the recording medium, and the process returns to the transport control process. When the process proceeds from step S25, the set speed is the first speed. In this case, an image is formed by image forming unit 140 while the recording medium is transported at the first speed. When the process proceeds from step S28, the set speed is the second speed. In this case, an image is formed by image forming unit 140 while the recording medium is transported at the second speed.

[0082] Returning to FIG. 8, when the first image forming process is completed in step S04, the process proceeds to step S05. In step S05, the initialization flag is set to OFF, and the process proceeds to step S06. In step S06, it is determined whether or not there is a page to be the next target of image formation. If there is a page to be the next target of image formation, the process proceeds to step S08, and if not, the process proceeds to step S07. In step S07, it is determined whether or not a print job has been accepted. If a print job has been accepted, the process proceeds to step S08, and if not, the process proceeds to step S10. If the process proceeds to step S08, the second speed is set as the conveying speed. In step S08, the second image forming process is executed, and the process proceeds to step S09.

[0083] Fig. 10 is a flow chart showing an example of the flow of the second image forming process. Referring to Fig. 10, the conveyance of the recording medium is started (step S31). Before the second image forming process is executed, the first image forming process is executed, and the set speed is set to the second speed. Therefore, the recording medium is conveyed at the second speed.

[0084] In step S32, the transmittance and the attenuation rate are acquired, and the process proceeds to step S33. CPU 111 controls ultrasonic sensor 29 to acquire the attenuation rate of ultrasonic waves passing through the recording medium, and controls optical sensor 30 to acquire the transmittance of light passing through the recording medium. Furthermore, ultrasonic sensor 29 outputs the attenuation rate measured at a number of sampling times less than the normal number, and optical sensor 30 outputs the transmittance measured at a number of sampling times less than the normal number.

[0085] In step S33, the type of recording medium is determined, and the process proceeds to step S34. From the attenuation rate, it is determined whether the recording medium is an envelope or paper. Also, from the transmittance, the basis weight of the recording medium is determined, and the type corresponding to the basis weight is determined.

[0086] In step S34, the media speed is determined and the process proceeds to step S35. The media speed is a recording medium transport speed that is predefined for the paper type. In step S35, the set speed is compared to the media speed. If the set speed is equal to the media speed, the process proceeds to step S36; otherwise, the process proceeds to step S37. S36A At the stage where step S35 is executed, the set speed is set to the second speed, so if the media speed is different from the second speed, the process proceeds to step S36. S36A Continue to Step S36A In step S31, the medium speed is set to the third speed, and the process proceeds to step S36. If the set speed, which is set to the second speed, is different from the medium speed, the set speed is not changed and the medium speed is set to the third speed. Therefore, the recording medium is subsequently transported at the second speed, which is set to the set speed. Therefore, even if the third speed is determined in the middle of a print job, the recording medium is transported at the second speed until the print job is completed.

[0087] In step S36, an image is formed on the recording medium, and the process proceeds to step S37. Whether the process proceeds from step S35 or from step S37, the set speed is the second speed. Therefore, an image is formed by the image forming unit 140 while the recording medium is conveyed at the second speed. When the process proceeds from step S37, the conveying speed corresponding to the type of recording medium determined in step S33 is different from the second speed. In this case, the various set values ​​for the image forming unit 140 to form an image on the recording medium are values ​​corresponding to the type of recording medium determined in step S33. Specifically, the voltage applied to the transfer roller 47 is adjusted to a value suitable for the basis weight of the recording medium, and the temperature of the fixing roller 49 is adjusted to a value suitable for the basis weight of the recording medium.

[0088] In step S37, it is determined whether there is a page to be the next target of image formation. If there is a page to be the next target of image formation, the process proceeds to step S38, but if not, the process proceeds to step S42. In step S38, it is determined whether the paper feed tray has been opened or closed. It is determined whether the tray in which the previously transported recording medium was stored, among the paper feed trays 151, 152, and 153 and the manual feed tray 154, has been opened or closed. If the tray has been opened or closed, the process proceeds to step S39, but if not, the process returns to step S31. When the process returns to step S31, the set speed is the second speed. Therefore, after step S31, the next recording medium is transported at the second speed (step S31), and the image of the next page is formed on the recording medium (step S36).

[0089] In step S39, the set speed is set to the first speed, and the process proceeds to step S40. In step S40, a first image forming process is executed. In the first image forming process, the recording medium is transported at the first speed (step S21), a media speed for the type of recording medium is determined (step S24), and if the media speed is different from the first speed, the set speed is set to a second speed which is the media speed (step S28).

[0090] In step S41, it is determined whether or not there is a page to be the next target of image formation. If there is a page to be the next target of image formation, the process returns to step S31, but if not, the process returns to the transport control process. In both cases where the process returns to step S31 and where the process returns to the transport control process, the set speed is the second speed. When the process returns to step S31, after step S31, the next recording medium is transported at the second speed (step S31), and the image of the next page is formed on that recording medium (step S36).

[0091] The process proceeds to step S42 when the formation of a plurality of pages of images defined by the print job on the recording medium is completed. If step S37 is executed while the print job is being executed, the medium speed is set to the third speed, but if step S37 is not executed, no value is set to the third speed. In step S42, it is determined whether or not a value is set to the third speed. If a value is set to the third speed, the process proceeds to step S43, but if not, the process returns to the transport control process. In step S43, the initialization flag is set to ON, and the process returns to the transport control process. If the initialization flag is set to ON, a value is set to the third speed, and the type of recording medium may have been changed midway.

[0092] Returning to FIG. 8, when the second image forming process is completed in step S08, the process proceeds to step S09. In step S09, it is determined whether or not the initialization flag is set to ON. If the initialization flag is set to ON, the process returns to step S01, but if not, the process proceeds to step S10. If the initialization flag is set to ON, the type of recording medium may have been changed during the execution of the job. Therefore, the process returns to step S01, the set speed is set to the first speed (step S01), and the first image forming process is executed (step S04). By executing the first image forming process, the type of recording medium is detected and the second speed is set as the conveying speed. If the initialization flag is not set to ON, the process proceeds to step S10 with the conveying speed set to the second speed.

[0093] In step S07, if the print job is not accepted, or if the initialization flag is not set to ON in step S09, the process proceeds to step S10. In step S10, it is determined whether the paper feed tray has been opened or closed. It is determined whether the opening or closing of the tray in which the previously transported recording medium was stored, among the paper feed trays 151, 152, and 153 and the manual feed tray 154, has been detected. If the opening or closing of the tray has been detected, the process returns to step S01, but if not, the process proceeds to step S11. If the paper feed tray is opened or closed, the paper feed tray may be replenished with paper. For this reason, the process returns to step S01, the set speed is set to the first speed (step S01), and the first image forming process is executed (step S04). By executing the first image forming process, the type of the recording medium is detected, and the transport speed is set to the second speed. If the paper feed tray is not opened or closed, the process proceeds to step S11 with the transport speed set to the second speed.

[0094] In step S11, it is determined whether the main power supply of the MFP 100 has been switched OFF. If it is detected that the power supply has been switched OFF, the process ends, but if not, the process returns to step S07. In step S07, it is determined whether the print job has been accepted, and if the print job has been accepted, the process proceeds to step S08. When the process proceeds from step S07 to step S08 to execute the second image forming process, the second speed is set as the conveying speed, so that the recording medium on which the image of the first page of the print job is formed is conveyed at the second speed (step S31). The second speed is the conveying speed determined based on the type of recording medium when the previously executed print job is executed. If the paper feed tray used in the previously executed print job and the print job to be executed next is the same, there is a high probability that the type of recording medium is also the same.

[0095] FIG. 11 is a diagram showing an example of a time chart. Referring to FIG. 11, the state of the paper feed tray, the state of the conveyed recording medium, the state of the recording medium conveyed at the first speed, the state of the recording medium conveyed at the second speed, and the state of the initialization flag are shown in order from the top. The state of the paper feed tray shows the open / closed state of the paper feed tray 151 that stores the recording medium to be conveyed. The open state of the paper feed tray 151 is shown by a high signal, and the closed state of the paper feed tray 151 is shown by a low signal. The state of the conveyed recording medium shows the state of the recording medium being conveyed by a high signal, and the state of the recording medium not being conveyed by a low signal. The state of the recording medium being conveyed at the first speed shows the state of the recording medium being conveyed at the first speed by a high signal, and the state of the recording medium not being conveyed at the first speed by a low signal. The state of the recording medium being conveyed at the second speed shows the state of the recording medium being conveyed at the second speed by a high signal, and the state of the recording medium not being conveyed at the second speed by a low signal. The state of the initialization flag is indicated as high when the initialization flag is ON, and as low when the initialization flag is OFF.

[0096] Here, a case is shown in which four print jobs, a first job to a fourth job, are executed by MFP 100. Each of the four print jobs, the first job to the fourth job, includes four pages.

[0097] First, in a state where the initialization flag is set to OFF, in response to the detection of an open state of the paper feed tray 151 and then a closed state being detected, the initialization flag is set to ON. Thereafter, when a first job is executed, the recording medium on which the image of the first page is formed is transported from the paper feed tray 151 at a first speed. While the recording medium on which the image of the first page is formed is being transported at the first speed, the attenuation rate and the transmittance are measured, and the transport speed of the recording medium is set to a second speed. Speed is determined at the

[0098] Then, the recording medium on which the image of the second page of the first job is formed is transported at a second speed from the paper feed tray 151. While the recording medium on which the image of the first page is formed is transported at the first speed, the attenuation rate and the transmittance are measured, the medium speed of the recording medium is determined, and the medium speed is set to the second speed. Speed If the second speed is equal to the first speed, the second speed is maintained. Similarly, the recording medium on which the images of the third and fourth pages of the first job are formed is transported at the second speed.

[0099] Next, the second job is executed without opening or closing the paper feed tray 151. Since there is no change in the recording media stored in the paper feed tray 151 after the first job is executed, the conveying speed is maintained at the second speed. Therefore, similar to the case of the second to fourth pages included in the first job, the recording media on which the images of the first to fourth pages included in the second job are formed are conveyed from the paper feed tray 151 at the second speed.

[0100] Next, the third job is executed without opening or closing the paper feed tray 151. Since there is no change in the recording medium stored in the paper feed tray 151 after the first job is executed, the conveying speed is maintained at the second speed. Therefore, similar to the cases of the second to fourth pages included in the first job, the recording medium on which the image of the first page included in the third job is formed is conveyed from the paper feed tray 151 at the second speed. The recording medium on which the image of the second page of the first job is formed is conveyed from the paper feed tray 151 at the second speed. While the recording medium on which the image of the second page of the third job is formed is conveyed at the second speed, the attenuation rate and transmittance are measured, the medium speed of the recording medium is determined, and the medium speed is set to the second speed. Speed When the medium speed is a third speed different from the first speed, an initialization flag is set to ON, and the conveying speed is maintained at the second speed. When the medium speed is the third speed, this is the case when multiple types of recording media are stored in the paper feed tray 151. In the same manner as when the recording media on which the image of the second page is formed is conveyed, the recording media on which the images of the third and fourth pages of the third job are formed are conveyed at the second speed.

[0101] Next, the fourth job is executed without opening or closing the paper feed tray 151. Since the initialization flag is set to ON, the recording medium on which the image of the first page of the fourth job is formed is transported from the paper feed tray 151 at a first speed. While the recording medium on which the image of the first page is formed is transported at the first speed, the attenuation rate and the transmittance are measured, and the transport speed of the recording medium is increased to the second speed. Speed The degree is determined.

[0102] Then, the recording medium on which the image of the second page of the fourth job is formed is transported at the second speed from the paper feed tray 151. While the recording medium on which the image of the first page is formed is transported at the first speed, the attenuation rate and the transmittance are measured, the medium speed of the recording medium is determined, and the medium speed is set to the second speed. Speed If the second speed is equal to the first speed, the second speed is maintained. Similarly, the recording medium on which the images of the third and fourth pages of the fourth job are formed is transported at the second speed.

[0103] Fig. 12 is a diagram showing an example of changes in image forming conditions with respect to an example of a change in the type of recording medium. Referring to Fig. 12, an example of the conveying speed, fixing temperature, and transfer voltage before and after the type of recording medium is switched is shown. The first line shows a case where the type of recording medium is switched from plain paper to thick paper 1, the second line shows a case where the type of recording medium is switched from plain paper to thick paper 2, the third line shows a case where the type of recording medium is switched from plain paper to thick paper 3, the fourth line shows a case where the type of recording medium is switched from thick paper 1 to plain paper, the fifth line shows a case where the type of recording medium is switched from thick paper 1 to thick paper 2, and the sixth line shows a case where the type of recording medium is switched from thick paper 1 to thick paper 3.

[0104] The conveying speed remains the same before and after the type of recording medium is switched, whereas the fixing temperature and transfer voltage change before and after the type of recording medium is switched.

[0105] As shown in the first line, when the type of recording medium is switched from plain paper to cardboard 1, the conveying speed is constant at 300 mm / s, while the fixing temperature is switched from 180° C. to 210° C. and the transfer voltage is switched from 1400 V to 1700 V. Similarly, as shown in the second, third, fifth and sixth lines, when the basis weight of the recording medium changes from a small recording medium to a large recording medium, the fixing temperature and transfer voltage are switched from small values ​​to large values.

[0106] As shown in the fourth line, when the type of recording medium is switched from cardboard 1 to plain paper, the conveying speed is constant at 170 mm / s defined for cardboard 1, while the fixing temperature is switched from 160° C. to 140° C. and the transfer voltage is switched from 1500 V to 1250 V. When the recording medium changes from one with a larger basis weight to one with a smaller basis weight, the fixing temperature and transfer voltage are switched from larger values ​​to smaller values.

[0107] The amount of heat that the fixing roller 49 applies to the recording medium is determined for each type of recording medium. Since the amount of heat that the fixing roller 49 applies to the recording medium differs when the conveying speed differs, the fixing temperature is determined for each type of recording medium by a table or an arithmetic expression that defines the relationship between the fixing temperature and the conveying speed. Similarly, the amount of work applied to the toner by the magnetic field generated by the transfer roller 47 is determined for each type of recording medium. Since the amount of work differs when the conveying speed differs, the transfer voltage is determined for each type of recording medium by a table or an arithmetic expression that defines the relationship between the transfer voltage and the conveying speed.

[0108] <First Modification> The MFP 100 in the above-described embodiment measures the attenuation rate and transmittance for all of the multiple pages included in the print job, and determines the type of the recording medium. After the second speed is determined, the MFP 100 in the first modified example measures the attenuation rate and transmittance of a recording medium on which an image of any one of the multiple pages included in the print job is to be formed, and determines the type of the recording medium. The any one page is, for example, the last page. For example, the attenuation rate and transmittance of the first recording medium on which the image of the first page of the print job is to be formed is measured, the type of the first recording medium is determined, and the second speed is determined from the type. Then, the attenuation rate and transmittance of the last recording medium on which the image of the last page of the print job is to be formed is measured, and the type of the last recording medium is compared with the type of the first recording medium to detect that the type of the recording medium has been changed between the first recording medium and the last recording medium. In this case, the attenuation rate and transmittance of each of the two recording media on which the images of the first and last pages of the multiple pages included in the print job are formed is measured, and the attenuation rate and transmittance of the other one or more recording media are not measured. This reduces the power consumption of the ultrasonic sensor 29 and the optical sensor 30, and also reduces the load on the CPU 111.

[0109] Furthermore, when multiple print jobs are performed consecutively, if the same paper feed tray is used for the first and second print jobs, the recording medium on which the images of the multiple pages included in the second print job are formed is conveyed at a second speed determined for the second print job when the first print job is executed. In this case, the attenuation rate and transmittance are measured for the recording medium on which the image of any one of the multiple pages included in the second print job is formed, and the attenuation rate and transmittance are not measured for the other one or more recording media. In this case, the power consumption of the ultrasonic sensor 29 and the optical sensor 30 is further reduced, and the load on the CPU 111 is further reduced.

[0110] Fig. 13 is a diagram showing an example of a time chart in the first modified example. Referring to Fig. 13, from the top, the state of the paper feed tray, the state of the conveyed recording medium, the state of the recording medium conveyed at a first speed and the attenuation rate and transmittance are measured, the state of the recording medium conveyed at a second speed and the attenuation rate and transmittance are measured, and the state of the initialization flag are shown.

[0111] Here, a case is shown in which four print jobs, a first job to a fourth job, are executed by MFP 100. Each of the four print jobs, the first job to the fourth job, includes four pages.

[0112] First, in a state where the initialization flag is set to OFF, in response to the detection of an open state of the paper feed tray 151 and then a closed state being detected, the initialization flag is set to ON. Thereafter, when a first job is executed, the recording medium on which the image of the first page is formed is transported from the paper feed tray 151 at a first speed. While the recording medium on which the image of the first page is formed is being transported at the first speed, the attenuation rate and the transmittance are measured, and the transport speed of the recording medium is set to a second speed. Speed The degree is determined.

[0113] Then, the recording medium on which the images of the second to fourth pages of the first job are formed is transported from the paper feed tray 151 at the second speed. The attenuation rate and transmittance are not measured while the two recording media on which the images of the second and third pages are formed are transported at the second speed. The attenuation rate and transmittance are measured for the recording medium of the fourth page, which is the final page of the first job, and the medium speed is determined. When the medium speed is the second Speed If the second speed is equal to the first speed, the second speed is maintained.

[0114] Next, the second job is executed without opening or closing the paper feed tray 151. Since there is no change in the recording medium stored in the paper feed tray 151 after the first job is executed, the conveying speed is maintained at the second speed. Therefore, similar to the case of the second and third pages included in the first job, the recording medium on which the images of the first to third pages included in the second job are formed is conveyed from the paper feed tray 151 at the second speed. During this time, the attenuation rate and transmittance are not measured. The attenuation rate and transmittance are measured for the recording medium of the fourth page, which is the final page of the second job, and the medium speed is determined. When the medium speed is the second Speed If the second speed is equal to the first speed, the second speed is maintained.

[0115] Next, the third job is executed without opening or closing the paper feed tray 151. Since there is no change in the recording media stored in the paper feed tray 151 after the first job is executed, the conveying speed is maintained at the second speed. Therefore, the recording media on which the images of the first to fourth pages of the third job are formed are conveyed from the paper feed tray 151 at the second speed. The attenuation rate and transmittance are not measured while the three recording media on which the images of the first to third pages are formed are being conveyed at the second speed. The attenuation rate and transmittance are measured for the recording medium of the fourth page, which is the final page of the third job, and the medium speed is determined. When the medium speed is the second SpeedWhen the medium speed is a third speed different from the first speed, an initialization flag is set to ON, and the conveying speed is maintained at the second speed. When the medium speed is the third speed, this is the case when multiple types of recording media are stored in the paper feed tray 151. In the same manner as when the recording media on which the image of the second page is formed is conveyed, the recording media on which the images of the third and fourth pages of the third job are formed are conveyed at the second speed.

[0116] Next, the fourth job is executed without opening or closing the paper feed tray 151. Since the initialization flag is set to ON, the recording medium on which the image of the first page of the fourth job is formed is transported from the paper feed tray 151 at a first speed. While the recording medium on which the image of the first page is formed is transported at the first speed, the attenuation rate and the transmittance are measured, and the transport speed of the recording medium is increased to the second speed. Speed is determined at the

[0117] Then, the recording medium on which the images of the second page to the fourth page of the fourth job are formed is transported from the paper feed tray 151 at the second speed. The attenuation rate and transmittance are not measured while the two recording media on which the images of the second page and the third page are formed are transported at the second speed. The attenuation rate and transmittance are measured for the recording medium of the fourth page, which is the final page of the fourth job, and the medium speed is determined. When the medium speed is the second Speed If the second speed is equal to the first speed, the second speed is maintained.

[0118] <Second Modification> In the above-described embodiment, MFP100 determines the type of recording medium from the attenuation rate and transmittance measured while transporting the recording medium at a first speed, and determines a second speed as the medium speed from the determined type. After the second speed is determined, the type of recording medium is determined from the attenuation rate and transmittance measured while transporting the recording medium at the second speed, and the medium speed is determined from the determined type. Then, when the medium speed is different from the second speed, the medium speed is set to a third speed.

[0119] After the second speed is determined, the MFP100 in the second modified example detects a change in the type of the recording medium when the attenuation rate and the transmittance change by a predetermined percentage without determining the type of the recording medium. Specifically, the CPU111 of the MFP100 stores the attenuation rate and the transmittance measured while conveying the recording medium at the first speed as reference values, conveys the recording medium to be conveyed thereafter at the second speed, and compares the attenuation rate and the transmittance measured for the recording medium with the reference values. If the attenuation rate and the transmittance differ from the reference value by a predetermined percentage or more, it is determined that the type of the recording medium has been changed. In this case, an arbitrary value different from the second speed is set to the third speed, or a flag indicating that the type of the recording medium has been changed is displayed. Since the type of the recording medium is not specified, the load on the CPU111 can be reduced.

[0120] As described above, the MFP 100 in this embodiment includes the paper feed unit 150 that conveys the recording medium, and the ultrasonic sensor 29 and the optical sensor 30 that detect information about the recording medium conveyed by the paper feed unit 150. The ultrasonic sensor 29 outputs the attenuation rate of ultrasonic waves as information about the recording medium, and the optical sensor 30 outputs the transmittance of light as information about the recording medium. When executing a print job that forms an image of multiple pages, the CPU 111 causes the paper feed unit 150 to convey the first sheet of recording medium corresponding to the first page at a first speed that is an initial value. At this time, the conveying speed of the recording medium is determined based on the attenuation rate and the transmittance measured by the ultrasonic sensor 29 and the optical sensor 30. When the determined conveying speed is different from the first speed, the CPU 111 causes the paper feed unit 150 to convey the second and subsequent recording media after the first sheet at a second speed that is different from the first speed. When the medium speed, which is the transport speed of the recording medium determined based on the attenuation rate and transmittance measured from the first recording medium transported at the first speed, is different from the first speed, the second and subsequent recording media after the first one are transported at a second speed different from the first speed, which makes it possible to continuously form images on a plurality of recording media without interruption.

[0121] The transport speed of the second and subsequent recording media is determined to be a second speed, which is a medium speed determined based on the attenuation rate and transmittance measured for the first recording medium transported at the first speed. Therefore, an image is formed at a transport speed suitable for the recording medium, and deterioration of image quality can be suppressed.

[0122] Furthermore, since the second speed is faster than the first speed, the time required for forming images on a plurality of recording media can be made as short as possible.

[0123] Furthermore, when the conveying speed of the recording medium determined based on the attenuation rate and transmittance measured from the second recording medium conveyed at the second speed during execution of the print job is a third speed different from the second speed, the CPU 111 conveys the images of the multiple pages included in the print job at the second speed, and conveys the first recording medium on which the image of the first page of the next print job of the print job is formed at the first speed. Therefore, the process of executing the print job is not interrupted, so that the print job can be executed efficiently. Also, since the first recording medium corresponding to the first page of the print job accepted next to the currently executed print job is conveyed at the first speed, deterioration of the image quality formed on the recording medium when the next accepted print job is executed is suppressed.

[0124] Furthermore, when the conveying speed of the recording medium, determined based on the attenuation rate and transmittance measured from the second recording medium conveyed at the second speed while the print job is being executed, is the second speed, the CPU 111 conveys the first recording medium, on which the image of the first page of the next print job of the print job is formed, at the second speed. Therefore, the next recording medium following the multiple consecutive recording media is conveyed at an appropriate conveying speed, so that the time to form an image on the recording medium of the next print job can be shortened. Also, since the next recording medium following the multiple recording media is conveyed at the second speed, deterioration of the image quality of the images formed on the next recording medium and the subsequent recording media is suppressed.

[0125] Further, the CPU 111 determines the type of the recording medium based on the attenuation rate and transmittance measured from the recording medium by the ultrasonic sensor 29 and the optical sensor 30, and of A conveying speed determined for each type is determined from the type. CPU 111 determines the type of at least one of the second and subsequent recording media among a plurality of consecutive recording media corresponding to a plurality of pages of a print job. This reduces the number of measurements by ultrasonic sensor 29 and optical sensor 30, thereby reducing the power consumed by ultrasonic sensor 29 and optical sensor 30.

[0126] After determining the second speed, the CPU 111 does not change the conveying speed until the print job is completed, which allows the print job to be executed efficiently.

[0127] Furthermore, after the second speed is determined, the CPU 111 reduces the number of sampling times of the ultrasonic sensor 29 and the optical sensor 30. This makes it possible to reduce the power consumed by the ultrasonic sensor 29 and the optical sensor 30.

[0128] Furthermore, during the execution of a print job, after determining the second speed, if the attenuation rate and transmittance measured from the recording medium by the ultrasonic sensor 29 and the optical sensor 30 change by a predetermined rate or more, the CPU 111 in the first modified example conveys the remaining recording medium at the second speed, and conveys the first recording medium on which the image of the first page of the next print job is formed at the first speed. Therefore, the execution of the print job being executed is not interrupted midway, and the print job can be completed as scheduled. Furthermore, since the CPU 111 conveys the first recording medium on which the image of the first page of the next print job is formed at the first speed, deterioration of the image quality formed on the recording medium in the next print job is suppressed.

[0129] <Summary of the embodiment> (Item 1) A conveying unit that conveys a plurality of recording media continuously; a media detection unit that detects information regarding the recording medium transported by the transport unit; an output unit that detects the information related to a first sheet of the recording medium conveyed by the conveying unit at a first speed using the media detection unit, and outputs a conveying speed of the recording medium that is determined based on the detected information; and a conveying control unit that, when the conveying speed output by the output unit is different from the first speed, controls the conveying speed of at least the second sheet and any subsequent sheets of the recording medium conveyed by the conveying unit after the first sheet to be a second speed different from the first speed.

[0130] According to this aspect, a transport speed of the recording medium determined based on information about the first recording medium transported at a first speed is output, and if the output transport speed differs from the first speed, the transport speed of at least one of the second and subsequent recording media transported after the first is controlled to a second speed different from the first speed. This makes it possible to provide an image forming apparatus capable of continuous image formation on a plurality of recording media without interrupting the image formation.

[0131] (Item 2) The image forming apparatus according to item 1, wherein a conveying speed of the sheet output by the output section is the second speed.

[0132] According to this aspect, the transport speed of at least one of the second and subsequent recording media is set to the transport speed of the recording media that is determined based on information about the first recording media that is transported at the first speed, so that an image is formed at a transport speed suitable for the recording media, thereby suppressing deterioration in image quality.

[0133] (Item 3) The image forming apparatus described in item 1 or 2, wherein, when the conveying speed output by the output unit is different from the first speed, the conveying control unit determines the conveying speed of the recording medium from the second sheet onwards to be the second speed, which is faster than the first speed.

[0134] According to this aspect, the second and subsequent recording media are transported at the second speed that is faster than the first speed, so that the time required for forming images on a plurality of recording media can be made as short as possible.

[0135] (Item 4) An image forming apparatus as described in any one of Items 1 to 3, wherein, when a third speed different from the second speed is output from the output unit while a plurality of consecutive recording media are being transported by the transport unit, the transport control unit transports the remainder of the plurality of consecutive recording media at the second speed and transports the next recording medium following the plurality of consecutive recording media at the first speed.

[0136] According to this aspect, the remaining of the continuous recording media are transported at the second speed, and the next recording medium following the continuous recording media is transported at the first speed. Therefore, image formation on the continuous recording media is not interrupted, and images are efficiently formed on the multiple recording media. Also, since the next recording medium following the multiple recording media is transported at the first speed, degradation in the quality of the images formed on the recording media after the next recording medium is suppressed.

[0137] (Item 5) The image forming device described in Item 4, wherein the transport control unit transports the next recording medium following the consecutive recording media at the second speed if the third speed is not output from the output unit while the consecutive recording media are being transported by the transport unit.

[0138] According to this aspect, the next recording medium following the plurality of consecutive recording media is transported at the second speed. Therefore, the next recording medium following the plurality of consecutive recording media is transported at an appropriate transport speed, so that the time required to form an image on the next recording medium can be shortened. In addition, the next recording medium following the plurality of recording media is transported at the second speed, so that deterioration in the image quality of the images formed on the next recording medium and the recording media thereafter is suppressed.

[0139] (Item 6) The output unit includes a type determination unit that determines a type of the recording medium based on the information about the recording medium detected by the media detection unit; a conveying speed determination unit that determines a conveying speed determined for the type of the recording medium determined by the type determination unit, The image forming apparatus according to any one of items 1 to 5, wherein the type determination means determines the type of at least one of the recording media from the second sheet onward after the output unit outputs a conveying speed different from the first speed.

[0140] According to this aspect, the type of at least one of the second or subsequent recording media among the plurality of recording media is determined. This reduces the number of detections by the media detection unit, thereby reducing power consumption.

[0141] (Item 7) An image forming apparatus according to any one of Items 1 to 6, wherein the transport control unit does not change the transport speed after the output unit outputs a transport speed different from the first speed until a plurality of consecutive recording media are transported by the transport unit.

[0142] According to this aspect, the conveying speed is not changed until the plurality of successive recording media are conveyed by the conveying section, so that images can be formed efficiently on the plurality of recording media.

[0143] (Item 8) An image forming apparatus as described in any one of Items 1 to 7, wherein the media detection unit reduces the number of samplings for detecting the information regarding the recording medium transported by the transport unit after the output unit outputs a transport speed different from the first speed, compared to before the output unit outputs a transport speed different from the first speed.

[0144] According to this aspect, after a transport speed different from the first speed is output, the number of samplings in the media detection unit is reduced compared to before the transport speed different from the first speed was output, thereby making it possible to reduce power consumption in the media detection unit.

[0145] (Item 9) An image forming apparatus as described in any of Items 1 to 8, wherein, while a plurality of consecutive recording media are being transported by the transport unit, if the information regarding the recording media detected by the media detection unit changes by more than a predetermined percentage after the output unit outputs a transport speed different from the first speed, the transport control unit transports the remainder of the plurality of consecutive recording media at the second speed and transports the next recording medium following the plurality of consecutive recording media at the first speed.

[0146] According to this aspect, the remaining of the continuous recording media are transported at the second speed, and the next recording medium following the continuous recording media is transported at the first speed. Therefore, image formation on the continuous recording media is not interrupted, and images are efficiently formed on the multiple recording media. Also, since the next recording medium following the multiple recording media is transported at the first speed, degradation in the quality of the images formed on the recording media after the next recording medium is suppressed.

[0147] (Item 10) A transport control method executed in an image forming apparatus, comprising: The image forming apparatus includes: A conveying unit that conveys a plurality of recording media continuously; a media detection unit that detects information about the recording media transported by the transport unit, an output step of detecting the information related to a first sheet of the recording medium conveyed at a first speed by the conveying unit with the media detection unit, and outputting a conveying speed of the recording medium determined based on the detected information; a transport control step of controlling, when the transport speed output in the output step is different from the first speed, the transport speed of at least the second sheet and any subsequent sheets of the recording medium transported by the transport section after the first sheet to be a second speed different from the first speed.

[0148] According to this aspect, it is possible to provide a transport control method that enables continuous image formation on a plurality of recording media without interruption.

[0149] (Item 11) A transport control program executed by a computer that controls an image forming apparatus, The image forming apparatus includes: A conveying unit that conveys a plurality of recording media continuously; a media detection unit that detects information about the recording media transported by the transport unit, an output step of detecting the information related to a first sheet of the recording medium conveyed at a first speed by the conveying unit with the media detection unit, and outputting a conveying speed of the recording medium determined based on the detected information; a transport control step of controlling, when the transport speed output in the output step is different from the first speed, the transport speed of at least the second sheet and any subsequent sheets of the recording medium transported by the transport section after the first sheet to be a second speed different from the first speed.

[0150] According to this aspect, it is possible to provide a transport control program that enables continuous image formation on a plurality of recording media without interruption.

[0151] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0152] 100 MFP, 110 main circuit, 111 CPU, 112 communication I / F section, 113 ROM, 114 RAM, 115 HDD, 116 facsimile section, 118 external storage device, 118A CD-ROM, 120 automatic document feeder, 130 document reading section, 140 image forming section, 150 paper feed section, 151, 152, 153 paper feed tray, 159 paper output tray, 160 operation panel, 161 display section, 163 operation section, 165 touch panel, 167 hard key section, 15 paper output roller, 21Y, 21M, 21C, 21K image forming unit, 23Y transfer roller, 24 drive roller, 24A roller, 27 intermediate transfer belt, 29 ultrasonic sensor, 29a ultrasonic transmission section, 29b ultrasonic reception section, 30 Optical sensor, 30a light emitting unit, 30b light receiving unit, 41 main transport path, 43 lower end, 45 timing roller, 47 transfer roller, 49 fixing roller, DA1 detection area, DA2 detection area, Pa recording medium, SP1 sub-transport path, SP2 sub-transport path, SP3 sub-transport path, TP1 target position, TP2 target position, Pa recording medium, 51 media sensor control unit, 53 output unit, 55 transport control unit, 56 job execution unit, 57 image formation control unit, 59 sampling count determination unit, 61 type determination unit, 63 transport speed determination unit, 65 initial speed determination unit, 67 media speed determination unit.

Claims

1. An image forming apparatus that executes a job of forming an image on a recording medium under image forming conditions determined based on information about the recording medium, a paper feed unit that feeds recording media stored in a paper feed tray; a conveying unit that conveys the recording medium fed from the paper feeding unit; a media detection unit that detects information regarding the recording medium transported by the transport unit; A conveyance control unit that controls a conveyance speed of the conveyance unit, The transport control unit is a first recording medium, which is a first recording medium of a first job, is transported at a first speed, and a second recording medium, which is transported after the first recording medium, is transported at a second speed faster than the first speed; An image forming apparatus, when the media detection unit determines that information regarding the first recording medium detected when the first recording medium is being transported at the first speed is different from information regarding the second recording medium detected when the second recording medium is being transported at the second speed, transports the first recording medium of the next job at the first speed.

2. The image forming apparatus according to claim 1 , wherein the media detection unit detects the information relating to the recording medium a plurality of times in the first job.

3. The image forming apparatus according to claim 1 , wherein the transport control unit starts transporting the first recording medium at the first speed, and changes the speed to the second speed based on information about the first recording medium.

4. The image forming apparatus according to claim 3 , wherein the transport control unit changes the speed of the first recording medium transported at the first speed to the second speed upstream of the image forming unit in the transport direction of the recording medium.

5. The image forming apparatus according to claim 1 , wherein the media detection unit detects all recording media of the first job.

6. 2. The image forming apparatus according to claim 1, wherein the first speed is a minimum value of conveying speeds determined for a plurality of types of recording media.

7. The image forming apparatus according to claim 1 , wherein the transport control unit transports the first recording medium of the next job at the first speed when opening and closing of the paper feed tray is detected.

8. the media detection unit is an ultrasonic sensor and an optical sensor, 2. The image forming apparatus according to claim 1, wherein the information about the recording medium is an attenuation rate of the ultrasonic wave detected by the ultrasonic sensor and a transmittance of the light detected by the optical sensor.

9. a type determination unit that determines the type of the recording medium based on an attenuation rate of the ultrasonic wave detected by the ultrasonic sensor and a transmittance rate of the light detected by the optical sensor; a conveying speed determination unit that determines a conveying speed determined for the type of the recording medium determined by the type determination unit, 9. The image forming apparatus according to claim 8, wherein the second speed is determined by the output section based on information about the first recording medium.

10. 10. The image forming apparatus according to claim 9, wherein the transport control unit does not change the transport speed after the second speed is output by the output unit until the first recording medium of the next job is transported by the transport unit.

11. 10. An image forming apparatus as described in claim 9, wherein the information regarding the first recording medium and the information regarding the second recording medium are judged to be different when the second speed and a conveying speed determined for the second recording medium are different.

12. An image forming apparatus as described in claim 9, wherein a case in which it is determined that the information regarding the first recording medium and the information regarding the second recording medium are different is a case in which the type of the first recording medium and the type of the second recording medium determined by the type determination unit are different.

13. 2 . The image forming apparatus according to claim 1 , wherein the media detection unit performs measurement sampling on the second recording medium less than the number of measurement sampling on the first recording medium.

14. A transport control method executed in an image forming apparatus, comprising: the image forming apparatus executes a job for forming an image on a recording medium under image forming conditions determined based on information about the recording medium, a paper feed unit that feeds recording media stored in a paper feed tray; a conveying unit that conveys the recording medium fed from the paper feeding unit; a media detection unit that detects information about the recording media transported by the transport unit, a step of conveying a first recording medium, which is a first recording medium of a first job, at a first speed and causing the media detection unit to detect information about the first recording medium; a step of transporting a second recording medium, which is transported after the first recording medium, at a second speed faster than the first speed, and causing the media detection unit to detect information related to the second recording medium; and if it is determined that the information relating to the first recording medium and the information relating to the second recording medium are different, transporting the first recording medium of the next job at the first speed.

Images