JP5125772B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that determines an image forming position in accordance with an end position of a sheet, and in particular, can curl a sheet by blowing air.

  Conventionally, a main scanning direction position detecting means for detecting the position of the side edge of the conveyed paper is provided, and the image writing position is changed according to the edge position of the paper in the middle of conveyance before being sent to the image forming unit. Thus, a technique for correcting the image position in the main scanning direction on the paper has been proposed (see, for example, Patent Document 1). As the main scanning direction position detecting means, a technique using a line sensor has been proposed (see, for example, Patent Document 2).

  FIG. 15 is a plan view showing an outline of the image forming apparatus. The image forming apparatus 500 includes a photosensitive drum 501 constituting an image forming unit, a registration roller 502 that conveys the paper P, a leading edge detection sensor 503 a that detects the leading edge of the paper P conveyed by the registration roller 502, A main scanning direction position detection sensor 503b that detects a side end that is a passing position in the main scanning direction is provided.

  In the image forming apparatus 500, when the leading edge of the paper P is detected by the leading edge detection sensor 503a, the passage position of the paper P in the main scanning direction is detected by the main scanning direction position detection sensor 503b, and the passage of the paper P in the main scanning direction is detected. The image writing position is determined according to the result of actual measurement of the position, that is, where the side edge of the paper P is located in the transport path.

  There has been proposed a technique for stably exposing the film to be conveyed by applying wind to suppress the warpage of the film (for example, see Patent Document 3).

Japanese Patent No. 2550558 JP 2000-33010 A JP 2002-196500 A

  FIG. 16 is an explanatory diagram illustrating a conventional problem. In the image forming apparatus 500 illustrated in FIG. 15, the detection position of the main scanning direction position detection sensor 503 b is viewed from the front in the conveyance direction of the paper P.

  In the image forming apparatus 500, the end position detection by the main scanning direction position detection sensor 503b is performed during the conveyance operation of the paper P. For this reason, the paper guide plates 504 facing each other with an interval of about several millimeters are usually installed at the detection position of the main scanning direction position detection sensor 503b.

  Since the distance between the paper guide plate 504 and the main scanning direction position detection sensor 503b is wider than the paper thickness of the paper P, if the paper P is curled, bending such as the side edge of the paper P warping occurs. If the paper P is curled, the end position of the paper P detected by the main scanning direction position detection sensor 503b is shifted by L compared to the case where there is no curl, and the end position is erroneously detected. .

  In an image forming apparatus having a function of performing double-sided printing, heat is not applied to the paper when printing on the front surface, and curling does not occur, so the edge position of the paper is accurately detected. On the other hand, at the time of printing on the back side, heat is applied to the sheet by fixing operation or the like at the time of image formation on the front side, so that the sheet curls and the end position is erroneously detected. As a result, the image formation position shift appears remarkably on the front and back sides of the paper.

  To narrow the gap between the guide plates in order to suppress the curl of the paper, it is necessary to improve the rigidity and accuracy of the guide plates, which not only increases the cost, but also causes the occurrence of poor paper passing with thick paper. . Further, when the paper is pressed against the guide plate by an elastic body such as PET, for example, the generation of paper dust or the like increases. Since the main scanning direction position detection sensor is an optical sensor, erroneous detection due to paper dust or the like frequently occurs.

  When curling paper by blowing, copiers and printing machines are required to handle various types of paper, but the rigidity varies depending on the type and basis weight of the paper. For example, a sheet with a small basis weight causes a conveyance failure due to an increase in frictional force caused by wind, and a sheet with a large basis weight has a problem that curling cannot be sufficiently suppressed.

  The present invention has been made to solve such a problem, and can reliably suppress curl regardless of the type of paper, prevent occurrence of conveyance failure, and prevent erroneous detection of the paper edge position. An object is to provide a forming apparatus.

In order to solve the above-described problem, the invention according to claim 1 is a paper transport unit having paper guides opposed to each other at a wider interval than a paper thickness of the paper to be passed, and a paper transported through the paper transport unit. A main scanning direction position detection sensor that detects the position of the end of the main scanning direction of the paper, and a sheet that is transported through the paper transporting unit is detected by the main scanning direction position detection sensor at one of the paper thickness directions. The air blowing mechanism has an air volume adjusting means for switching the air volume for pressing the paper against the paper guide, and the air blown by the air blowing mechanism according to the type information of the paper conveyed through the paper conveying unit. switching the presence or absence of the blowing air volume and wind, in the state in which the paper supplying air by the air supply mechanism is pressed against the paper guide, detect the position of the end portion in the main scanning direction of the sheet by a main scanning direction position detecting sensor system An image forming apparatus that includes a section.

In the image forming apparatus of the present invention, the edge position in the main scanning direction of the paper is detected by the main scanning direction position detection sensor while blowing the air to the paper conveyed through the paper conveying unit by the air blowing mechanism, and the image writing position is detected. Is determined based on the edge position of the paper in the main scanning direction . In the image forming apparatus, depending on the type of paper on which the image is formed, the basis weight, etc., the air volume of the air blown from the air blowing mechanism and the presence / absence of the air blowing are switched, so that the curl of the paper can be prevented without causing a conveyance failure. Is securely pressed to prevent erroneous detection of the end position of the paper in the main scanning direction .

  The invention described in claim 2 includes an information input unit for designating paper type information, and the control unit is configured to set the air volume switching operation in accordance with the paper type information designated by the information input unit. The image forming apparatus according to Item 1.

  According to a third aspect of the present invention, the control unit causes the air volume of the air blown from the blower mechanism to have a larger basis weight than a sheet having a smaller basis weight, according to the paper type information specified by the information input unit. The image forming apparatus according to claim 2, wherein an operation mode for strengthening the sheet is set.

According to a fourth aspect of the present invention, the control unit blows wind from the blower mechanism in accordance with the detection timing of the position detection sensor in the main scanning direction according to the paper type information specified by the information input unit, and performs main scanning. 4. The image forming apparatus according to claim 2, wherein an operation mode for stopping the blowing of wind at a timing other than the detection timing of the direction position detection sensor is set.

  The invention according to claim 5 is an operation mode in which the control unit constantly blows air from the blower mechanism during the conveying operation of one or a plurality of sheets according to the sheet type information specified by the information input unit. The image forming apparatus according to claim 2, wherein is set.

According to the sixth aspect of the present invention, the control unit causes the air flow to flow at a first air volume from the blower mechanism during the conveying operation of one or more sheets according to the sheet type information specified by the information input unit. The image forming apparatus according to claim 5, wherein an operation mode is set in which the air is blown and the air is blown with a second air volume stronger than the first air volume in accordance with a detection timing of the position detection sensor in the main scanning direction .

According to the image forming apparatus of the present invention, the air flow that suppresses the curl of the paper and the presence / absence of the air blowing are switched according to the type of the paper, the basis weight, and the like, so It is possible to prevent erroneous detection of the end position in the main scanning direction due to the curl of the paper and conveyance failure due to an increase in frictional force.

  Hereinafter, an embodiment of an image forming apparatus of the present invention will be described with reference to the drawings.

<Example of Configuration of Image Forming Apparatus of Embodiment>
FIG. 1 is an internal configuration diagram illustrating an example of an image forming apparatus according to the present embodiment, FIG. 2 is a perspective view illustrating an overview of the image forming apparatus according to the present embodiment, and FIG. 3 illustrates image formation according to the present embodiment. FIG. 4 is a side sectional view of a paper transport mechanism showing an example of the apparatus.

  First, an outline of the image forming apparatus 1 of the present embodiment will be described. The image forming apparatus 1 of the present embodiment includes a paper transport mechanism 2 that transports the paper P, a blower mechanism 3 that blows wind W onto the paper P transported by the paper transport mechanism 2 and suppresses curling of the paper P, and An image forming unit 4 that forms an image on the paper P is provided.

  The image forming apparatus 1 detects the edge of the paper P by the leading edge detection sensor 5a and the main scanning direction position detection sensor 5b while blowing the wind W by the blower mechanism 3 on the paper P conveyed by the paper conveyance mechanism 2. The image writing position by the image forming unit 4 is determined based on the edge position information of the paper P.

  The image forming apparatus 1 can control the conveyance failure of the paper P conveyed by the paper conveyance mechanism 2 by switching the air volume of the air W blown from the blower mechanism 3 according to the type of the paper P on which the image is formed. Without curling, the curl of the paper P is securely pressed to prevent erroneous detection of the end position of the paper P.

  Next, an example of the sheet transport mechanism 2 according to the present embodiment constituting the image forming apparatus 1 will be described. The paper transport mechanism 2 is an example of a paper transport unit, and includes a registration roller 20 that transports the paper P and a guide member 21 that guides the paper P transported by the resist roller 20 as shown in FIG.

  In the guide member 21, a guide plate 21a and a guide plate 21b constituting a paper guide are arranged to face each other, and the paper P is conveyed between the guide plate 21a and the guide plate 21b. The guide member 21 is configured such that the guide plate 21a and the guide plate 21b face each other at a predetermined interval wider than the thickness of the thick paper P among the paper P considered as an image forming target in the image forming apparatus 1. Prevents poor transport when transporting cardboard.

  The leading edge detection sensor 5a and the main scanning direction position detection sensor 5b are examples of edge detection sensors, and are arranged on the downstream side of the registration roller 20 with respect to the conveyance direction of the paper P. The leading edge detection sensor 5a is a reflective or transmissive optical sensor including a light emitting / receiving element, and a detection surface is exposed on the guide plate of the guide member 21, in this example, the guide plate 21a, and the leading edge in the transport direction of the paper P is detected. A detection signal is output according to whether or not the part has reached. That is, when the sheet P is conveyed between the guide plate 21a and the guide plate 21b of the guide member 21 and the leading end of the sheet P reaches the detection position of the leading end detection sensor 5a, the output of the leading end detection sensor 5a is, for example, “ L "changes to" H ".

  The main scanning direction position detection sensor 5b is a reflective or transmissive optical line sensor in which light emitting and receiving elements are arranged in parallel in the main scanning direction perpendicular to the transport direction of the paper P. In this example, the main scanning direction position detection sensor 5b is provided on the guide plate 21a. The detection surface is exposed, and a detection signal is output according to the position of one side edge of the paper P conveyed between the guide plate 21a and the guide plate 21b.

  The blower mechanism 3 is disposed on the downstream side of the registration roller 20 with respect to the conveyance direction of the paper P, facing the main scanning direction position detection sensor 5b, and below the guide plate 21b in this example. The blower mechanism 3 includes a fan unit 30 that blows out the wind W and a shutter unit 31 that adjusts the air volume.

  The fan unit 30 includes, for example, a centrifugal fan 30a that is rotationally driven by a fan motor, which will be described later, and a fan case 30c in which an air outlet 30b is formed. In the fan unit 30, the air outlet 30b is directed to the air outlet opening 21c formed in the guide plate 21b so as to face the main scanning direction position detection sensor 5b, and the centrifugal fan 30a is driven to rotate to blow the wind W. The air outlet 30b faces the main scanning direction position detection sensor 5b.

  Here, the air blowing mechanism 3 may be configured such that the wind W blown out by the fan unit 30 hits the entire width direction (main scanning direction) of the paper P, but the curl of the paper P during the conveyance is mainly the width. Since the wind W is generated at both ends in the direction, the wind W may be applied mainly to both ends of the paper P. For example, in the guide plate 21b, the air path and the air outlet 30b are formed by the fan case 30c so that the air W is blown out from at least two air outlets 21c formed on both sides in the width direction of the paper P. .

  Thereby, in the air blowing mechanism 3, the wind W is blown out near the detection position of the paper P by the main scanning direction position detection sensor 5b.

  The shutter unit 31 is an example of an air volume adjusting means, and includes a first shutter 31a that opens and closes the blowout opening 21c and a first shutter drive unit 31b that drives the first shutter 31a. The shutter unit 31 includes a second shutter 31c that opens and closes the outlet opening 21c, and a second shutter drive unit 31d that drives the second shutter 31c.

  The first shutter 31a opens and closes the blowout opening 21c by a linear operation between a closed position indicated by a solid line and an open position indicated by a two-dot chain line in FIG. The first shutter 31a fully closes the outlet opening 21c at the closed position shown by a solid line in FIG. 3, and fully opens the outlet opening 21c at the open position shown by a two-dot chain line in FIG.

  The second shutter 31c is formed with an air volume adjustment opening 31e having a size capable of obtaining a desired air volume, and is blown out by a linear operation between a closed position indicated by a solid line and an open position indicated by a two-dot chain line in FIG. The part 21c is opened and closed. When the second shutter 31c is in the closed position indicated by a solid line in FIG. 3, the opening of the blowout opening 21c is narrowed by the air volume adjustment opening 31e, and at the open position indicated by a two-dot chain line in FIG. Fully open.

  The first shutter driving unit 31b is configured by a solenoid that linearly operates the first shutter 31a, and the second shutter driving unit 31d is configured by a solenoid that linearly operates the second shutter 31c. Thereby, the first shutter 31a and the second shutter 31c are opened and closed independently, and the presence or absence of the blowing of the wind W is switched by opening and closing the first shutter 31a. The air volume of the wind W is switched by opening and closing.

  Next, an operation example of the paper transport mechanism 2 of the present embodiment will be described. 4A to 4C are explanatory diagrams of the operation of the shutter unit showing an example of the operation of the paper transport mechanism of the present embodiment, and FIG. 5 is an explanatory diagram showing the relationship between opening and closing of the shutter unit and the air volume. is there.

  In FIG. 4A, the first shutter drive unit 31b sets the first shutter 31a to the closed position, and the second shutter drive unit 31d sets the second shutter 31c to the closed position. When the first shutter 31a is in the closed position, the blowout opening 21c is fully closed. Thereby, even if the fan part 30 is driven, the wind W is not blown out from the blowing opening part 21c.

  In FIG. 4B, the first shutter drive unit 31b sets the first shutter 31a to the open position, and the second shutter drive unit 31d sets the second shutter 31c to the closed position. When the first shutter 31a is in the open position and the second shutter 31c is in the closed position, the opening of the blowout opening 21c is narrowed by the air volume adjustment opening 31e. Thus, when the fan unit 30 is driven at a constant speed, the wind W having a reduced air volume is blown out from the blowout opening 21c.

  In FIG. 4C, the first shutter drive unit 31b sets the first shutter 31a to the open position, and the second shutter drive unit 31d sets the second shutter 31c to the open position. When both the first shutter 31a and the second shutter 31c are in the open position, the blowout opening 21c is fully opened. Thus, when the fan unit 30 is driven at a constant speed, the air volume is increased and the wind W is blown out from the blowing opening 21c.

  FIG. 6 is an explanatory view showing an effect example of the image forming apparatus of the present embodiment. In the paper transport mechanism 2 of the image forming apparatus 1 shown in FIG. It is the figure seen from the front of the conveyance direction of P.

  When the wind W is blown from the blowing opening 21c by the blower mechanism 3, the paper P is pressed against the detection surfaces of the upper guide plate 21a and the main scanning direction position detection sensor 5b in this example. As a result, even when the paper P is curled due to heat or the like, the curl is suppressed at the edge detection position. Accordingly, the end position of the paper P can be detected accurately.

  Next, the overall configuration of the image forming apparatus 1 of the present embodiment provided with the above-described paper transport mechanism 2 will be described. In this example, the image forming apparatus 1 is a monochrome digital multi-function peripheral having a copy function, a printer function, a scanner function, and the like, and includes an apparatus main body 100 and an automatic document reversal feeding apparatus 200 as shown in FIG.

  First, the configuration of the apparatus main body 100 will be described. The apparatus main body 100 includes the above-described paper transport mechanism 2, the image forming unit 4 that forms an image on the paper P transported by the paper transport mechanism 2, and the image forming unit 4. A fixing unit 6 that fixes an image formed on the paper P to the paper P is provided.

  Further, the apparatus main body 100 includes a main body paper supply unit 7 that supplies the paper P to the paper transport mechanism 2, a main body paper discharge unit 8 that discharges the paper P on which an image is formed, and an inversion unit that reverses the paper P from the front to the back. 9, an external paper feeding unit 10 that supplies paper P to the paper transport mechanism 2 from the outside, and a reading unit 11 that reads a document.

  The sheet transport mechanism 2 having the configuration described with reference to FIG. 3 and the like is disposed on the upstream side of the image forming unit 4 with respect to the transport direction of the sheet P. The sheet P whose end position is detected by the front end detection sensor 5a and the main scanning direction position detection sensor 5b described in 3 etc. is sent to the image forming unit 4 by the feed roller 22.

  In the image forming unit 4, the toner image formed on the photosensitive drum 40 is transferred onto the paper P. The photosensitive drum 40 is coated with a photosensitive layer on the surface of a cylindrical substrate, and is rotationally driven in the direction of an arrow by a driving mechanism (not shown).

  The image forming unit 4 is uniformly charged by the corona charger 41 while rotating the photosensitive drum 40, and then exposed by the exposure unit 42, and an electrostatic latent image is formed on the surface of the photosensitive drum 40.

  The exposure unit 42 reflects a beam emitted from a laser (not shown) by a polygon mirror and irradiates the surface of the photosensitive drum 40. The polygon mirror is rotated at a predetermined rotational speed, and the main scanning of the laser beam is performed by the rotation of the polygon mirror. Further, the laser beam is sub-scanned by the rotation of the photosensitive drum 40. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 40. The electrostatic latent image formed on the photosensitive drum 40 is visualized by the developing unit 43.

  The developing unit 43 includes a developing sleeve 43a, a mechanism for stirring and supplying toner, and the like. The developing sleeve 43a supplies toner to the photosensitive drum 40, and attaches the toner to the electrostatic latent image on the photosensitive drum 40. A toner image is formed. The toner image on the photosensitive drum 40 is transferred from the photosensitive drum 40 to the paper P by the transfer charger 44, and the paper P on which the toner image has been transferred is separated from the photosensitive drum 40 by the separation charger 45.

  The transfer charger 44 is disposed opposite to the photosensitive drum 40 and discharges the charge from the back side of the paper P superimposed on the photosensitive drum 40 electrostatically carrying the toner image, thereby transferring the toner image onto the paper P. Transcript. The separation charger 45 neutralizes the paper P adsorbed on the photosensitive drum 40 and separates the paper P from the photosensitive drum 40.

  The toner remaining on the surface of the photosensitive drum 40 without being transferred to the paper P is collected by the cleaning unit 46. The cleaning unit 46 includes a blade or the like that comes into contact with the photosensitive drum 40, and scrapes and stores toner or the like attached to the surface of the photosensitive drum 40.

  The paper P on which the toner image is formed by the image forming unit 4 is conveyed to the fixing unit 6. The fixing unit 6 includes a fixing unit 61 having a heating roller in which a heater is incorporated and a pressure roller that presses the paper P against the heating roller. The paper P on which the toner image is transferred by the image forming unit 4 is fixed to the fixing unit 61. Then, pressure and heat are applied to the paper P by the fixing device 61, and the toner is welded and fixed onto the paper P.

  The main body sheet feeding unit 7 includes a plurality of sheet feeding cassettes 70 that can store sheets P of different sizes or the same size, and a feeding mechanism 71 having rollers and the like for feeding and conveying the sheets P from each sheet feeding cassette 70. The paper P is fed out from the paper feed cassette 70 one by one and supplied to the paper transport mechanism 2.

  The main body discharge unit 8 discharges the paper P processed by the fixing unit 6 to the outside of the apparatus main body 100. The reversing unit 9 includes a reversing conveyance path 90 that branches from the conveyance path on the downstream side of the fixing unit 6 with respect to the conveyance direction of the paper P, and reverses the conveyance direction to merge on the upstream side of the paper conveyance mechanism 2. By sending the paper P processed by the fixing unit 6 to the reverse conveyance path 90, the paper P is reversed and fed from the paper conveyance mechanism 2 to the image forming unit 4. The transport direction of the paper P that has passed through the fixing unit 6 is switched by the transport switching gate 91, and the paper P is sent to the main body paper discharge unit 8 or the reversing unit 9 depending on the operation mode.

  The external paper feed unit 10 includes a conveyance path that merges upstream of the paper conveyance mechanism 2, and the paper P supplied from an external paper supply unit (not shown) or the like is sent from the paper conveyance mechanism 2 to the image forming unit 4. As described above, any of the paper P supplied from the main body paper supply unit 7, the paper P on which an image is formed on the front surface and reversed upside down by the reversing unit 9, and the paper P supplied from the external paper supply unit 10 A conveyance path sent from the conveyance mechanism 2 to the image forming unit 4 is configured, and the end position is detected by the paper conveyance mechanism 2, and the image writing position by the image forming unit 4 is determined.

  The reading unit 11 includes a light source 12 that irradiates a document, an image sensor 13 that reads an image, and a light receiving optical system 14 that causes light emitted from the light source 12 and reflected by the document to enter the image sensor 13. An image on the original P1 supplied by the paper feeding device 200 is read, and image data as an electrical signal is output.

  The automatic document reversing paper feeder (RADF) 200 is configured to change the transport direction of the document tray 201 on which the document P1 is placed, the discharge tray 202 on which the document P1 that has been read is discharged, and the document P1 to be reversed upside down. A reversing tray 203 for switching and a paper feed mechanism 204 for feeding the original P1 are provided. The automatic document reversing paper feeding device 200 feeds the document P1 placed on the document tray 201 one by one by the paper feeding mechanism 204 and supplies it to the reading position of the reading unit 11.

  FIG. 7 is a block diagram illustrating an example of a control function of the image forming apparatus according to the present embodiment. 7 shows a control system related to the paper transport mechanism 2 in the image forming apparatus 1. The image forming apparatus 1 includes a fan motor 102 that drives the air blowing mechanism 3 described with reference to FIG. 3 and the like, a first shutter driving unit 31b, a second shutter driving unit 31d, and the image forming unit 4 described with reference to FIG. Are controlled by the control unit 103. The control unit 103 is connected to a nonvolatile memory 104 and an operation unit 105 which is an example of an information input unit.

  The nonvolatile memory 104 stores an air volume setting table 104a in which the air volume blown out by the blower mechanism 3 is set according to the type of paper P, for example, the paper type and the basis weight. The operation unit 105 performs selection of a paper feed cassette for supplying the paper P and various printing operations.

  When the paper P is set in the paper cassette 70 shown in FIG. 1, paper information specifying the paper type, basis weight, etc. of the paper P is stored in the nonvolatile memory 104, and the paper cassette 70 that supplies the paper P is supplied. Is selected on the operation unit 105, the control unit 103 recognizes the paper type, basis weight, and the like of the paper P that is an image formation target. Then, the control unit 103 refers to the air volume setting table 104a of the non-volatile memory 104 according to the paper type, basis weight, and the like of the paper P on which image formation is performed, and blows out the wind W with a predetermined air volume.

<Example of Operation of Image Forming Apparatus of Present Embodiment>
8 to 12 are operation time charts of air volume switching in the image forming apparatus according to the present embodiment, and FIG. 13 is an explanatory diagram of an air volume setting table showing an example of air volume setting depending on the paper type. The operation of the image forming apparatus 1 of the present embodiment will be described.

  In the image forming apparatus 1 of the present embodiment, the registration roller 20 is initially stopped at the start of the machine operation in the printing operation, and the rotation of the registration roller 20 is started at a predetermined timing. Thereafter, the paper P is conveyed by the registration rollers 20, and the paper P passes through the main scanning direction position detection sensor 5b and passes through the leading edge detection sensor 5a.

  When the paper P passes through the main scanning direction position detection sensor 5b and the leading edge detection sensor 5a, if the leading edge of the paper P reaches the leading edge detection sensor 5a and a detection signal is output, the main scanning direction position detection sensor 5b Based on the output detection signal, the end (side end) position of the conveyed paper P is detected. The edge position information of the paper P is fed back to the image forming unit 4, the image writing position is determined, and the image alignment is performed according to the edge position information of the paper P.

  In the operation of detecting the end position of the paper P by the main scanning direction position detection sensor 5b, the image forming apparatus 1 blows out the wind W from the air blowing mechanism 3 with the air volume according to the paper type and the like to suppress the curling of the paper P. . In the image forming apparatus 1, depending on the paper type of the paper P on which an image is formed, the wind W is continuously blown from the blower mechanism 3 during the printing operation, or the paper P is detected by the main scanning direction position detection sensor 5b. Whether the wind W is blown out intermittently is switched according to the detection timing of the end position. Also, the strength of the air volume can be switched.

  FIG. 8 shows an operation in the first air volume adjustment mode as an operation of switching the intensity of the air W blown from the air blowing mechanism 3 in the image forming apparatus 1 and the presence / absence of the air blowing. In the first air flow rate adjustment mode (1), the air flow W is blown out by the air blowing mechanism 3 from the start to the stop of the mechanical operation of the image forming apparatus 1 by the printing operation.

  In the first air volume adjustment mode (1), when the control unit 103 of the image forming apparatus 1 starts the machine operation, it drives the fan motor 102 of the blower mechanism 3 and at the same time, as shown in FIG. One shutter driving unit 31b is driven to set the first shutter 31a to the open position. At this time, the second shutter drive unit 31d is not driven, and the second shutter 31c is held in the closed position.

  When the printing of the predetermined number of sheets P is completed and the machine operation is finished, the driving of the fan motor 102 of the blower mechanism 3 is stopped, and at the same time, the first shutter driving unit 31b is driven as shown in FIG. Thus, the first shutter 31a is set to the closed position.

  As a result, in the first air volume adjustment mode (1), the wind W having a weak air volume is constantly blown from the start to the stop of the machine operation, and the edge of the paper P at the main scanning direction position detection sensor 5b. At the position detection timing, the paper P is pressed against the guide member 21 with a weak force, and the paper P being conveyed is always pressed against the guide member 21 with a weak force.

  FIG. 9 shows the operation in the second air volume adjustment mode. In the second air volume adjustment mode (2), the air W is blown out with the air volume increased by the air blowing mechanism 3 from the start to the stop of the machine operation of the image forming apparatus 1 by the printing operation.

  In the second air volume adjustment mode (2), when the control unit 103 of the image forming apparatus 1 starts the mechanical operation, the fan motor 102 of the blower mechanism 3 is driven and at the same time, as shown in FIG. One shutter driving unit 31b is driven to set the first shutter 31a to the open position. Further, the second shutter drive unit 31d is driven to set the second shutter 31c to the open position.

  When the printing of the predetermined number of sheets P is completed and the machine operation is finished, the driving of the fan motor 102 of the blower mechanism 3 is stopped, and at the same time, the first shutter driving unit 31b is driven as shown in FIG. Thus, the first shutter 31a is set to the closed position. Further, the second shutter drive unit 31d is driven to place the second shutter 31c in the closed position.

  As a result, in the second air volume adjustment mode (2), the wind W having a high air volume is constantly blown from the start to the stop of the machine operation, and the edge of the paper P in the main scanning direction position detection sensor 5b. At the position detection timing, the paper P is pressed against the guide member 21 with a strong force, and the paper P being conveyed is always pressed against the guide member 21 with a strong force.

  FIG. 10 shows the operation in the third air volume adjustment mode. In the third air volume adjustment mode (3), when the machine operation of the image forming apparatus 1 by the printing operation is started, the air blowing mechanism 3 does not blow air, but at the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b. The wind W is blown out with the air volume weakened immediately before and immediately after the sheet P arrives at a certain tip detection sensor 5a.

  In the third air volume adjustment mode (3), the control unit 103 of the image forming apparatus 1 drives the fan motor 102 of the blower mechanism 3 when the machine operation is started. At this time, the first shutter driving unit 31b and the second shutter driving unit 31d are not driven, and as shown in FIG. 4A, both the first shutter 31a and the second shutter 31c are in the closed position. Hold.

  When the sheet P is conveyed to a predetermined position and the registration roller 20 is activated, as shown in FIG. 4B, the first shutter drive unit 31b is driven to open the first shutter 31a. At this time, the second shutter drive unit 31d is not driven, and the second shutter 31c is held in the closed position.

  At the timing when the registration roller 20 is activated, the leading edge of the paper P has not yet reached the leading edge detection sensor 5a, and the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b is not reached. As a result, the wind W is blown out with a low air volume before the end position of the paper P is detected.

  When the registration roller 20 is activated and the paper P is conveyed, the leading edge of the paper P reaches the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. Then, when the registration roller 20 is activated and a predetermined time elapses, as shown in FIG. 4A, the first shutter driving unit 31b is driven to bring the first shutter 31a into the closed position. As a result, the blowing of the wind W is stopped after the end timing of detecting the end position of the paper P is completed.

  Thereafter, until the printing of a predetermined number of sheets of paper P is completed, the first shutter 31a is opened at the same time as the registration roller 20 is started, and the first shutter 31a is closed after a predetermined time. Is weakly blown intermittently at the detection timing of the end position of the paper P.

  When the printing of the predetermined number of sheets P is finished and the machine operation is finished, the driving of the fan motor 102 of the blower mechanism 3 is stopped.

  As a result, in the third air volume adjustment mode (3), the wind W is blown out with the air volume weakened between the start and stop of the machine operation and immediately before and immediately after the sheet P arrives at the leading edge detection sensor 5a. Then, the sheet P is pressed against the guide member 21 with a weak force at the detection timing of the end position of the sheet P by the main scanning direction position detection sensor 5b.

  FIG. 11 shows the operation in the fourth air volume adjustment mode. In the fourth air volume adjustment mode (4), when the machine operation of the image forming apparatus 1 by the printing operation is started, the air blowing mechanism 3 does not blow, but at the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b. The wind W is blown out with a strong air volume from immediately before and immediately after the sheet P arrives at a certain tip detection sensor 5a.

  In the fourth air volume adjustment mode (4), the control unit 103 of the image forming apparatus 1 drives the fan motor 102 of the blower mechanism 3 when the machine operation is started. At this time, the first shutter driving unit 31b and the second shutter driving unit 31d are not driven, and as shown in FIG. 4A, both the first shutter 31a and the second shutter 31c are in the closed position. Hold.

  When the sheet P is conveyed to a predetermined position and the registration roller 20 is activated, as shown in FIG. 4C, the first shutter drive unit 31b is driven to open the first shutter 31a. Further, the second shutter drive unit 31d is driven to set the second shutter 31c to the open position.

  As described above, at the timing when the registration roller 20 is activated, the leading edge of the paper P has not yet reached the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. is not. As a result, the wind W is blown out with a strong air volume before the end timing of the paper P is detected.

  When the registration roller 20 is activated and the paper P is conveyed, the leading edge of the paper P reaches the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. Then, when the registration roller 20 is activated and a predetermined time elapses, as shown in FIG. 4A, the first shutter driving unit 31b is driven to bring the first shutter 31a into the closed position. Further, the second shutter drive unit 31d is driven to place the second shutter 31c in the closed position. As a result, the blowing of the wind W is stopped after the end timing of detecting the end position of the paper P is completed.

  Thereafter, the first shutter 31a and the second shutter 31c are opened at the same time as the registration roller 20 is activated until the printing of the predetermined number of sheets P is completed, and the first shutter 31a and the second shutter are opened after a predetermined time. Control is performed to close the position 31c, and the wind W with a strong air volume is intermittently blown in accordance with the detection timing of the end position of the paper P.

  When the printing of the predetermined number of sheets P is finished and the machine operation is finished, the driving of the fan motor 102 of the blower mechanism 3 is stopped.

  As a result, in the fourth air volume adjustment mode (4), the wind W is blown out with a strong air volume between the start and stop of the machine operation and immediately before and immediately after the sheet P arrives at the leading edge detection sensor 5a. Then, the sheet P is pressed against the guide member 21 with a strong force at the detection timing of the end position of the sheet P by the main scanning direction position detection sensor 5b.

  FIG. 12 shows the operation in the fifth air volume adjustment mode. In the fifth air flow rate adjustment mode (5), the air flow W is blown out by the air blowing mechanism 3 from the start to the stop of the mechanical operation of the image forming apparatus 1 by the printing operation. Further, the wind W is blown out with a strong air volume from immediately before and immediately after the paper P arrives at the leading edge detection sensor 5a which is the detection timing of the end position of the paper P in the main scanning direction position detection sensor 5b.

  In the fifth air volume adjustment mode (5), when the control unit 103 of the image forming apparatus 1 starts the machine operation, the fan motor 102 of the blower mechanism 3 is driven at the same time as shown in FIG. One shutter driving unit 31b is driven to set the first shutter 31a to the open position. At this time, the second shutter drive unit 31d is not driven, and the second shutter 31c is held in the closed position.

  When the sheet P is conveyed to a predetermined position and the registration roller 20 is activated, the second shutter drive unit 31d is driven to open the second shutter 31c, as shown in FIG. 4C.

  As described above, at the timing when the registration roller 20 is activated, the leading edge of the paper P has not yet reached the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. is not. As a result, the wind W is blown out with a strong air volume before the end timing of the paper P is detected.

  When the registration roller 20 is activated and the paper P is conveyed, the leading edge of the paper P reaches the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. Then, when the registration roller 20 is activated and a predetermined time has elapsed, as shown in FIG. 4B, the second shutter drive unit 31d is driven to bring the second shutter 31c into the closed position. Thereby, after the end timing of detecting the end position of the paper P is finished, the air volume is switched to be weak and the wind W is blown out.

  Thereafter, the first shutter 31a is held in the open position until the printing of the predetermined number of sheets P is completed, and the second shutter 31c is set to the open position at the same time as the registration roller 20 is started. Control to set 31c to the closed position is performed. That is, while the paper P is being transported, the wind W having a low air volume is continuously blown out, and the wind W having a high air volume is intermittently blown in accordance with the detection timing of the end position of the paper P. The

  When the printing of the predetermined number of sheets P is completed and the machine operation is finished, the driving of the fan motor 102 of the blower mechanism 3 is stopped, and at the same time, the first shutter driving unit 31b is driven as shown in FIG. Thus, the first shutter 31a is set to the closed position.

  Thus, in the fifth air volume adjustment mode (5), the wind W having a weak air volume is constantly blown from the start to the stop of the machine operation, and the sheet P being conveyed is always weakly applied to the guide member 21. Pressed. In addition, immediately before and immediately after the sheet P arrives at the leading edge detection sensor 5a, the wind W is blown out with a strong air volume. At the detection timing of the end position of the sheet P by the main scanning direction position detection sensor 5b, the sheet W P is pressed against the guide member 21 with a strong force.

  Next, the relationship between the paper type and basis weight of the paper P and the air volume will be described. In general, when printing on the back side in the double-sided printing mode, the temperature of the paper P is high due to the fixing operation or the like at the time of front-side printing. In order to reduce dirt such as paper dust, it is better to continue blowing the wind W by the blower mechanism 3.

  Further, the paper P having a small basis weight can be curled by the weak airflow W, and if the airflow is increased, the paper P may lose its rigidity due to an increase in paper passing resistance, resulting in poor conveyance. Should be weak. On the other hand, paper with a large basis weight needs a strong air volume to suppress curling with the wind W, and the paper P has a high rigidity, so that there is no conveyance failure caused by increasing the air volume. The sheet P having an intermediate basis weight can achieve both detection accuracy and good feedability by reducing the air volume during conveyance and increasing the air volume only when the end position is detected.

  On the other hand, as the paper type, the coated paper is not rigid with respect to the basis weight of the paper, and the surface is smooth. Therefore, if the wind W is continuously blown, the paper P sticks to the guide plates 21a and 21b of the guide member 21. There is a high possibility of a conveyance failure. For this reason, blowing air with the air volume necessary to hold the curl only when detecting the end position does not blow air during transport, so detection accuracy and good feedability can be obtained. Switching is made so that the wind W is blown out only at the end detection.

In the air volume setting table shown in FIG. 13, when the paper type of the paper P is coated paper, the basis weight is small. In this example, if the paper weight is 130 g / m ² or less, the air volume setting table has the above-described third air volume adjustment mode. B blows out W. In other words, the air is not blown at the start of the machine operation, and the wind W is blown out with the air volume being weakened at the end detection timing.

When the paper type of the paper P is coated paper and the basis weight is large, in this example, the wind W is blown out in the fourth air volume adjustment mode described above as 131 g / m ² or more. In other words, the air is not blown at the start of the machine operation, but the wind W is blown out with the air volume being increased at the end detection timing.

When the paper type of the paper P is high-quality paper, plain paper, book paper, or rough paper, the basis weight is small. In this example, if the paper weight is 91 g / m ² or less, the wind W in the first air volume adjustment mode described above is used. Blow out. That is, the wind W is continuously blown from the start to the stop of the machine operation with the air volume being reduced.

Paper type fine paper sheet P, plain paper, book paper, in the case of a rough paper, if the basis weight is middle and in this example is 209 g / m ² or less at 92 g / m ² or more, the above-described 5 The wind W is blown out in the air volume adjustment mode. That is, from the start to the stop of the machine operation, the wind W is continuously blown with the air volume being weak, and the wind W is blown with the air volume being strong at the end detection timing.

In the case where the paper type P is fine paper, plain paper, book paper, rough paper, and the basis weight is large, in this example, if the paper weight is 210 g / m ² or more, the wind W in the second air volume adjustment mode described above is used. Blow out. That is, the wind W is continuously blown from the start to the stop of the machine operation with the air volume being increased.

  FIG. 14 is a flowchart showing an example of the operation of the image forming apparatus according to the present embodiment. Next, referring to each drawing, the air volume adjustment mode is switched depending on the type of paper P and the basis weight, and the end position The operation of pressing the curl of the paper P with air at the time of detection will be described.

  In step SA1 in FIG. 14, the type information such as the paper type and basis weight of the paper P is input by selecting the paper feed cassette 70 that feeds the paper P with the operation unit 105. Note that the type information of the paper P may be input from the operation unit 105 or the like by an operation independent of the selection of the paper feed cassette 70.

  In step SA <b> 2 of FIG. 14, when the mechanical operation of the image forming apparatus 1 is started by a printing operation, the control unit 103 drives the fan motor 102 of the blower mechanism 3. In step SA3 in FIG. 14, the paper type and basis weight classification of the paper P are determined.

  When the first air volume adjustment mode is selected from the paper type and basis weight classification of the paper P, in the example of the air volume setting table in FIG. 13, the paper type of the paper P is fine paper, plain paper, book paper, rough paper. In the case of paper, when the basis weight is small, the wind W is continuously blown from the start to the stop of the machine operation with the air volume being reduced.

  That is, in step SA4 in FIG. 14, the control unit 103 drives the first shutter driving unit 31b to open the first shutter 31a as shown in FIG. 4B. If it is determined in step SA5 in FIG. 14 that printing of a predetermined number of sheets P is completed and the machine operation is terminated, in step SA6 in FIG. 14, the first shutter drive unit 31b is moved as shown in FIG. Driven to bring the first shutter 31a into the closed position.

  As a result, when the first air volume adjustment mode (1) is selected, the wind W with a weak air volume is constantly blown from the start to the stop of the machine operation, and the paper in the main scanning direction position detection sensor 5b is blown. At the detection timing of the end position of P, the paper P is pressed against the guide member 21 with a weak force, and the paper P being conveyed is always pressed against the guide member 21 with a weak force.

  Then, when the mechanical operation of the image forming apparatus 1 by the printing operation is finished in step SA7 in FIG. 14, the driving of the fan motor 102 of the blower mechanism 3 is stopped and the printing operation is finished.

  When the second air volume adjustment mode is selected from the paper type and basis weight classification of the paper P, in the example of the air volume setting table in FIG. 13, the paper type of the paper P is fine paper, plain paper, book paper, rough paper In the case of paper, when the basis weight is large, the wind W is continuously blown from the start to the stop of the machine operation with the air volume being increased.

  That is, in step SA8 in FIG. 14, the control unit 103 drives the first shutter drive unit 31b to open the first shutter 31a and the second shutter as shown in FIG. The shutter drive unit 31d is driven to place the second shutter 31c in the open position. If it is determined in step SA9 in FIG. 14 that printing of a predetermined number of sheets P is completed and the machine operation is terminated, in step SA10 in FIG. 14, the first shutter drive unit 31b is moved as shown in FIG. The first shutter 31a is driven to the closed position, and the second shutter drive unit 31d is driven to set the second shutter 31c to the closed position.

  Thus, when the second air volume adjustment mode (2) is selected, the wind W with a strong air volume is constantly blown from the start to the stop of the machine operation, and the sheet in the main scanning direction position detection sensor 5b is blown. At the detection timing of the end position of P, the paper P is pressed against the guide member 21 with a strong force, and the paper P being conveyed is always pressed against the guide member 21 with a strong force.

  Then, when the mechanical operation of the image forming apparatus 1 by the printing operation is finished in step SA7 in FIG. 14, the driving of the fan motor 102 of the blower mechanism 3 is stopped and the printing operation is finished.

  When the third air volume adjustment mode is selected from the paper type and basis weight classification of the paper P, in the example of the air volume setting table in FIG. 13, the paper type of the paper P is coated paper, and the basis weight is If it is small, the air is not blown at the start of the machine operation, and the wind W is blown out with the air volume being reduced at the end detection timing.

  That is, in step SA11 in FIG. 14, when the sheet P is conveyed to a predetermined position and the registration roller 20 is activated, the control unit 103 drives the first shutter drive unit 31b as shown in FIG. 4B. Thus, the first shutter 31a is set to the open position.

  At the timing when the registration roller 20 is activated, the leading edge of the paper P has not yet reached the leading edge detection sensor 5a, and the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b is not reached. As a result, the wind W is blown out with a low air volume before the end position of the paper P is detected.

  When the registration roller 20 is activated and the paper P is conveyed, the leading edge of the paper P reaches the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. If it is determined in step SA12 in FIG. 14 that the predetermined time has elapsed since the registration roller 20 was activated, in step SA13 in FIG. 14, the first shutter drive unit 31b is moved as shown in FIG. Driven to bring the first shutter 31a into the closed position. As a result, the blowing of the wind W is stopped after the end timing of detecting the end position of the paper P is completed.

  If it is determined in step SA14 in FIG. 14 that the sheet P has stopped after passing the registration roller 20, it is determined in step SA15 in FIG. 14 whether printing of a predetermined number of sheets P is completed and the machine operation is terminated.

  Thereafter, until the printing of a predetermined number of sheets of paper P is completed, the first shutter 31a is opened at the same time as the registration roller 20 is started, and the first shutter 31a is closed after a predetermined time. Is weakly blown intermittently at the detection timing of the end position of the paper P.

  As a result, when the third air volume adjustment mode (3) is selected, the air volume is reduced between immediately before and immediately after the paper P arrives at the leading edge detection sensor 5a from when the machine operation starts to when it stops. The wind W is blown out, and the paper P is pressed against the guide member 21 with a weak force at the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b.

  Then, when the mechanical operation of the image forming apparatus 1 by the printing operation is finished in step SA7 in FIG. 14, the driving of the fan motor 102 of the blower mechanism 3 is stopped and the printing operation is finished.

  When the fourth air volume adjustment mode is selected from the paper type and basis weight classification of the paper P, in the example of the air volume setting table in FIG. 13, the paper type of the paper P is coated paper, and the basis weight is If it is large, the air is not blown at the start of the machine operation, and the wind W is blown out with the air volume being increased at the end detection timing.

  That is, in step SA16 in FIG. 14, when the sheet P is conveyed to a predetermined position and the registration roller 20 is activated, the control unit 103 drives the first shutter driving unit 31b as shown in FIG. Then, the first shutter 31a is set to the open position, and the second shutter drive unit 31d is driven to set the second shutter 31c to the open position.

  At the timing when the registration roller 20 is activated, the leading edge of the paper P has not yet reached the leading edge detection sensor 5a, and the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b is not reached. As a result, the wind W is blown out with a strong air volume before the end timing of the paper P is detected.

  When the registration roller 20 is activated and the paper P is conveyed, the leading edge of the paper P reaches the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. If it is determined in step SA17 in FIG. 14 that the predetermined time has elapsed since the registration roller 20 is activated, in step SA18 in FIG. 14, the first shutter drive unit 31b is moved as shown in FIG. The first shutter 31a is driven to the closed position, and the second shutter drive unit 31d is driven to set the second shutter 31c to the closed position. As a result, the blowing of the wind W is stopped after the end timing of detecting the end position of the paper P is completed.

  If it is determined in step SA19 in FIG. 14 that the sheet P has stopped after passing the registration roller 20, it is determined in step SA20 in FIG. 14 whether printing of a predetermined number of sheets P is completed and the machine operation is ended.

  Thereafter, the first shutter 31a and the second shutter 31c are opened at the same time as the registration roller 20 is activated until the printing of the predetermined number of sheets P is completed, and the first shutter 31a and the second shutter are opened after a predetermined time. Control is performed to close the position 31c, and the wind W with a strong air volume is intermittently blown in accordance with the detection timing of the end position of the paper P.

  As a result, when the fourth air volume adjustment mode (4) is selected, the air volume is increased between immediately before and after the start of the machine operation and immediately before and immediately after the sheet P arrives at the leading edge detection sensor 5a. The wind W is blown out, and the sheet P is pressed against the guide member 21 with a strong force at the detection timing of the end position of the sheet P by the main scanning direction position detection sensor 5b.

  Then, when the mechanical operation of the image forming apparatus 1 by the printing operation is finished in step SA7 in FIG. 14, the driving of the fan motor 102 of the blower mechanism 3 is stopped and the printing operation is finished.

  When the fifth air volume adjustment mode is selected from the paper type and basis weight classification of the paper P, in the example of the air volume setting table in FIG. 13, the paper type of the paper P is fine paper, plain paper, book paper, rough paper In the case of paper, when the basis weight is intermediate, the wind W is continuously blown from the start to the stop of the machine operation with the air volume being weak, and the wind W is blown out with the air volume being strong at the edge detection timing.

  That is, in step SA21 in FIG. 14, the control unit 103 drives the first shutter drive unit 31b to open the first shutter 31a as shown in FIG. 4B.

  In step SA22 of FIG. 14, when the paper P is conveyed to a predetermined position and the registration roller 20 is activated, the second shutter 31c is driven by driving the second shutter driving unit 31d as shown in FIG. 4C. Open position.

  At the timing when the registration roller 20 is activated, the leading edge of the paper P has not yet reached the leading edge detection sensor 5a, and the detection timing of the end position of the paper P by the main scanning direction position detection sensor 5b is not reached. As a result, the wind W is blown out with a strong air volume before the end timing of the paper P is detected.

  When the registration roller 20 is activated and the paper P is conveyed, the leading edge of the paper P reaches the leading edge detection sensor 5a, and the detection timing of the edge position of the paper P by the main scanning direction position detection sensor 5b is reached. In step SA23 in FIG. 14, when the registration roller 20 is activated and a predetermined time has elapsed, in step SA24 in FIG. 14, the second shutter drive unit 31d is driven as shown in FIG. 4B. The second shutter 31c is set to the closed position. Thereby, after the end timing of detecting the end position of the paper P is finished, the air volume is switched to be weak and the wind W is blown out.

  If it is determined in step SA25 in FIG. 14 that the sheet P has stopped after passing the registration roller 20, it is determined in step SA26 in FIG. 14 whether printing of a predetermined number of sheets P is completed and the machine operation is completed.

  Thereafter, the first shutter 31a is held in the open position until the printing of the predetermined number of sheets P is completed, and the second shutter 31c is set to the open position at the same time as the registration roller 20 is started. Control to set 31c to the closed position is performed. That is, while the paper P is being transported, the wind W having a low air volume is continuously blown out, and the wind W having a high air volume is intermittently blown in accordance with the detection timing of the end position of the paper P. The

  As a result, when the fifth air volume adjustment mode (5) is selected, the wind W having a weak air volume is constantly blown from the start to the stop of the machine operation, and the sheet P being conveyed is directed to the guide member 21. It is always pressed with a weak force. In addition, immediately before and immediately after the sheet P arrives at the leading edge detection sensor 5a, the wind W is blown out with a strong air volume. At the detection timing of the end position of the sheet P by the main scanning direction position detection sensor 5b, the sheet W P is pressed against the guide member 21 with a strong force.

  If it is determined in step SA26 in FIG. 14 that printing of the predetermined number of sheets P has been completed and the machine operation is to be terminated, in step SA27 in FIG. 14, the first shutter drive unit 31b is moved as shown in FIG. Driven to bring the first shutter 31a into the closed position.

  Then, when the mechanical operation of the image forming apparatus 1 by the printing operation is finished in step SA7 in FIG. 14, the driving of the fan motor 102 of the blower mechanism 3 is stopped and the printing operation is finished.

  With the operation of the image forming apparatus 1 described above, the strength of the wind blown from the blower mechanism 3 and the presence / absence of the blowout are switched depending on the paper type and basis weight of the paper P, so It is possible to improve the detection accuracy of the part position and to obtain a good feeding performance.

<Modification of Image Forming Apparatus According to Embodiment>
In the image forming apparatus 1 according to the above-described embodiment, the air blowing mechanism 3 is provided to face the main scanning direction position detection sensor 5b, and the sheet P is pressed against the upper guide plate 21a shown in FIG. As indicated by an arrow W1 in FIG. 3, the paper P may be pressed against the lower guide plate 21b so that air can be blown from the position of the main scanning direction position detection sensor 5b. In this case, the air blowing mechanism 3 at a position facing the position sensor 5b in the main scanning direction is not necessary.

  In the blower mechanism 3, the air volume adjusting means is a shutter that opens and closes the blowout opening 21c. This is because the response at the time of control is good and the air volume can be switched in a short time. On the other hand, the air volume adjusting means may be performed by changing the rotation speed of the fan unit 30 or by changing the position of the fan unit 30.

  In addition, the second shutter 31c having the first shutter 31a and the air volume adjustment opening 31e is provided so that the air volume can be adjusted by fully opening and closing each shutter. The source may be a pulse motor, and the shutter opening may be arbitrarily adjusted.

  Furthermore, the strength of the wind is not two types of strength and weakness, and the number of divisions may be increased, and the air volume may be switched by setting not only the paper type and the basis weight but also the paper size.

  The present invention is applied to an image forming apparatus that determines an image forming position in accordance with an end position of a sheet.

1 is an internal configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. 1 is a perspective view illustrating an outline of an image forming apparatus according to an embodiment. FIG. 3 is a side sectional view of a paper transport mechanism showing an example of an image forming apparatus according to the present embodiment. FIG. 6 is an operation explanatory diagram of a shutter unit illustrating an operation example of a paper transport mechanism according to the present embodiment. It is explanatory drawing which shows the relationship between opening and closing of a shutter part, and an air volume. It is explanatory drawing which shows the example of an effect of the image forming apparatus of this Embodiment. 3 is a block diagram illustrating an example of a control function of the image forming apparatus according to the present exemplary embodiment. FIG. 4 is an operation timing chart of air volume switching in the image forming apparatus according to the present embodiment. 4 is an operation timing chart of air volume switching in the image forming apparatus according to the present embodiment. 4 is an operation timing chart of air volume switching in the image forming apparatus according to the present embodiment. 4 is an operation timing chart of air volume switching in the image forming apparatus according to the present embodiment. 4 is an operation timing chart of air volume switching in the image forming apparatus according to the present embodiment. It is explanatory drawing of the air volume setting table which shows the example of the air volume setting by paper type and basic weight. 5 is a flowchart illustrating an operation example of the image forming apparatus according to the present exemplary embodiment. 1 is a plan view illustrating an outline of an image forming apparatus. It is explanatory drawing which shows the conventional subject.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Paper conveyance mechanism, 21 ... Guide member, 21a, 21b ... Guide plate, 21c ... Blowing opening part, 3 ... Blower mechanism, 31a ... First shutter, 31c ... second shutter, 4 ... image forming unit, 5a ... tip detection sensor, 5b ... main scanning direction position detection sensor, 103 ... control unit

Claims (6)

A paper transport unit having paper guides facing each other at a wider interval than the paper thickness of the paper that can be passed;
A main scanning direction position detection sensor for detecting a position of an end of the paper transported in the main scanning direction of the paper;
The amount of wind that blows the paper that is transported through the paper transport unit against the paper guide in one of the paper thickness directions at the detection position of the main scanning direction position detection sensor and that presses the paper against the paper guide A blower mechanism having an air volume adjusting means for switching between,
A state in which the amount of wind blown by the blower mechanism and the presence / absence of blown air are switched according to the type information of the paper that is transported through the paper transport unit, and the paper is pressed against the paper guide by the air blown by the blower mechanism in the image forming apparatus characterized by comprising a control unit detect the position of the end portion in the main scanning direction of the paper by the main scanning direction position detecting sensor.   2. The apparatus according to claim 1, further comprising an information input unit for designating paper type information, wherein the control unit is configured to perform an air volume switching operation in accordance with the paper type information designated by the information input unit. The image forming apparatus described.   The control unit is an operation mode in which the amount of air blown from the blower mechanism is increased with a sheet having a larger basis weight than a sheet having a smaller basis weight in accordance with the sheet type information specified by the information input unit. The image forming apparatus according to claim 2, wherein: is set. The control unit blows wind from the blower mechanism in accordance with the detection timing of the main scanning direction position detection sensor according to the paper type information specified by the information input unit, and the main scanning direction position detection sensor The image forming apparatus according to claim 2, wherein an operation mode for stopping the blowing of wind is set at a timing other than the detection timing at.   The control unit is configured to set an operation mode in which air is constantly blown from the blower mechanism during the conveying operation of one or a plurality of sheets according to the sheet type information specified by the information input unit. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. The control unit blows out air from the blower mechanism with a first air volume during the conveying operation of one or a plurality of sheets according to the sheet type information specified by the information input unit, and performs the main scanning. 6. The image forming apparatus according to claim 5, wherein an operation mode for blowing air with a second air volume stronger than the first air volume is set in accordance with a detection timing of the direction position detection sensor.

Images