JP6372191B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Patent Document 1 discloses that an image carrier that carries a toner image, an intermediate transfer member that receives an image primarily transferred from the image carrier, and a primary transfer image on the intermediate transfer member are recorded on a recording sheet. In an image forming apparatus including a secondary transfer unit that performs next transfer and a recording sheet conveyance unit that conveys a recording sheet to the secondary transfer unit, the secondary transfer unit extends in a predetermined direction and is conveyed. A secondary transfer member that presses the recording paper against the intermediate transfer member; and an opposing member that faces the secondary transfer member across the intermediate transfer member and presses the intermediate transfer member against the secondary transfer member. An image forming apparatus is disclosed in which the axial directions of the secondary transfer member and the opposing member are set so as to be deviated from a direction perpendicular to a recording paper conveyance direction by a predetermined inclination angle.

  Patent Document 2 discloses an image carrier, an optical scanning device that exposes the image carrier to form an electrostatic latent image on the image carrier, and the image carrier by attaching toner to the electrostatic latent image. A developing unit for forming a toner image on the body, an intermediate transfer member on which the toner image on the image carrier is primarily transferred, and a nip between the intermediate transfer member and the intermediate transfer member. An image forming apparatus including a transfer member that secondarily transfers a toner image on an intermediate transfer member to a transfer paper that passes through a portion, wherein the transfer paper is An image forming apparatus having a control mechanism for entering a nip portion is disclosed.

JP 2007-199358 A JP 2006-293132 A

  An object of the present invention is to provide an image forming apparatus in which deterioration of an image formed on a recording medium is suppressed as compared with a case where the inclination angle of the recording medium is not controlled by an alignment roll according to the thickness of the recording medium. It is to be.

In order to achieve the above object, an image forming apparatus according to claim 1 rotates while holding a recording medium in a gap between a rotating body on which an image is formed on a peripheral surface and the rotating body, and A transfer roll for transferring an image formed on the peripheral surface of the rotating body to the recording medium, a first conveying roll for conveying the recording medium to the gap, and the recording medium upstream of the first conveying roll. The second conveying roll to be conveyed and the second conveying roll so that the angle of the recording medium with respect to the rotation axis of the rotating body is within a predetermined threshold before the recording medium enters the first conveying roll. said first transport roll as controls the transport roll, and wherein the recording medium is inclined at a predetermined angle according to the thickness of the recording medium over the previous Kikai rotating shaft entering into the gap And a control means for controlling.
In order to achieve the above object, an image forming apparatus according to claim 2 rotates while holding a recording medium in a gap between a rotating body on which an image is formed on a peripheral surface and the rotating body, and A transfer roll for transferring an image formed on the peripheral surface of the rotating body to the recording medium, one end fixed and the other end being rotatable about the one end, and the conveying direction of the recording medium at the other end A pair of eccentric cams that contact both sides and a pair of conveyance rolls that convey the recording medium while holding the recording medium to the gap, and the pair of eccentric cams are rotated synchronously. The other end of the conveyance roll pair holding the recording medium is rotated by a predetermined angle, and tilted at the predetermined angle according to the thickness of the recording medium with respect to the rotation axis of the rotating body. And the recording medium is And control means for controlling the first transport roll to enter the gap, is intended to include.
According to a third aspect of the present invention, in the second aspect of the present invention, the control unit rotates the other end to the opposite side by the predetermined angle after completing the conveyance for each recording medium. Thus, the first transport roll is controlled so that the first transport roll returns to the reference position.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the first transport roll has one end fixed and the other end rotatable about the one end, and the gap. A pair of conveying rolls that convey the recording medium while holding the recording medium, and the control unit rotates the other end of the conveying roll pair that holds the recording medium by the predetermined angle, The first conveying roll is controlled so that the recording medium enters the gap with an inclination at the predetermined angle.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the control unit rotates the other end to the opposite side by the predetermined angle after completing the conveyance for each recording medium. wherein by the first conveying roll is one which controls the first transport roll back to the reference position.

According to a sixth aspect of the invention, in the fourth or fifth aspect of the invention, the first transport roll has a pair of eccentric cams in contact with both sides of the other end of the recording medium in the transport direction. And the control means controls the first transport roll so that the recording medium enters the gap by inclining at the predetermined angle by rotating the pair of eccentric cams synchronously. Is.

The invention according to claim 7 is the invention according to any one of claims 1 to 6 , further comprising generating means for generating image information for forming an image on the peripheral surface of the rotating body. And the control means further controls the generation means so that the image information to be formed on the rotating body by inclining the image by the predetermined angle is generated.

The invention according to an eighth aspect is the invention according to any one of the first to seventh aspects, wherein the control means is configured such that the thickness of the recording medium is equal to or greater than a predetermined threshold value. The first conveying roll is controlled so that the recording medium enters the gap with an inclination at the predetermined angle.

The invention according to claim 9 is the invention according to any one of claims 1 to 8 , wherein the electrostatic latent image formed on the peripheral surface is developed with toner to form a toner image. The rotating body is a secondary transfer unit that transfers a toner image formed on the image holding body to form an image on the peripheral surface.

According to the first aspect of the present invention, the deterioration of the image formed on the recording medium is suppressed as compared with the case where the inclination angle of the recording medium is not controlled by the alignment roll according to the thickness of the recording medium. The effect is obtained.
According to the first aspect of the present invention, the angle of the recording medium with respect to the rotation axis is within a predetermined threshold before the recording medium enters the first transport roll by the second transport roll. As compared with the case where the control is not performed, an effect that the tilt angle to be applied to the recording medium is accurately controlled can be obtained.

According to the invention described in claim 4 , the first transport roll is fixed at one end and rotatable at the other end around the one end, and the transport roll pair transports the recording medium while holding the recording medium to the gap. As compared with the case where the recording medium is not used, the effect that the inclination angle of the recording medium can be easily changed is obtained.

According to the third and fifth aspects of the invention, after the conveyance for each recording medium is completed, the other end is rotated to the opposite side by a predetermined angle so that the first conveyance roll returns to the reference position. Compared with the case where the control is not performed, the effect that an accurate inclination angle is given to each recording medium even when recording media having different thicknesses are mixed is obtained.

According to the second and sixth aspects of the invention, the inclination angle applied to the recording medium is finely adjusted compared to the case where the angle is applied to the recording medium without using the eccentric cam. can get.

According to the seventh aspect of the present invention, a more appropriate image can be obtained as compared with the case where the generation means is not controlled so that image information to be formed on the rotating body is generated by inclining the image by a predetermined angle. The effect of being formed on a recording medium can be obtained.

According to the eighth aspect of the invention, when the thickness of the recording medium is equal to or greater than a predetermined threshold, the first conveying roll is inclined so that the recording medium enters the gap by tilting at a predetermined angle. Compared with the case where the control is not performed, there is an effect that the wasteful control of the first transport roll is suppressed and the image forming speed is further increased.

According to the ninth aspect of the present invention, the intermediate transfer type image forming apparatus is formed on the recording medium as compared with the case where the inclination angle of the recording medium is not controlled by the alignment roll according to the thickness of the recording medium. The effect that the deterioration of the image to be suppressed is suppressed is obtained.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment. 1 is a block diagram illustrating an example of a main configuration of an electric system of an image forming apparatus according to an embodiment. 6 is a graph showing a change in speed of an intermediate transfer belt from when a recording sheet enters a secondary transfer position to when it is discharged. It is a figure for demonstrating operation | movement of the registration roll unit which concerns on embodiment. It is a schematic block diagram which shows an example of a structure of the registration roll unit which concerns on embodiment. It is a flowchart which shows the flow of a process of the inclination angle adjustment process program which concerns on embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 generates image data for each color of yellow (Y), magenta (M), cyan (C), and black (K), and a recording medium (recording in the present embodiment) is performed based on each image data. An image is formed on the paper P). Hereinafter, image formation performed by the image forming apparatus 100 may be referred to as “printing”. The image forming apparatus 100 includes an image forming unit 102, a paper feed unit 104, and a paper discharge unit 106.

  The image forming unit 102 includes image forming units 10Y, 10M, 10C, and 10K that form toner images of Y, M, C, and K colors.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in a line in the traveling direction W of the endless intermediate transfer belt 30 supported by the support roll 34, the drive roll 20, and the roll 32. The intermediate transfer belt 30 is disposed so as to face the image carriers 12Y, 12M, 12C, and 12K of the image forming units 10Y, 10M, 10C, and 10K and the image carriers 12Y, 12M, 12C, and 12K. The primary transfer rolls 16Y, 16M, 16C, and 16K are inserted.

  In the following, when it is necessary to distinguish YMCK, any one of Y, M, C, and K is added after the sign, and when it is not necessary to distinguish YMCK, Y, M, C, and K are omitted. To do.

  Each image forming unit 10 includes an image carrier 12, a charger 13, an exposure unit 14, a developing device 15, and a primary transfer roll 16.

  The image carrier 12 is driven to rotate, and the surface thereof is charged by the charger 13. In the present embodiment, the charger 13 is configured by a charging brush, but may be configured by a charging roll that is a rotating body.

  The exposure unit 14 includes a laser light source that emits laser light by driving an exposure control unit 98 (see FIG. 2), which will be described later, and exposes the charged image carrier 12 by irradiating the laser beam with the laser beam. An electrostatic latent image is formed on the surface. In the present embodiment, the exposure unit 14 provided with a laser light source will be described as an example. However, the present invention is not limited to this, and an LED (light emitting diode) is provided and the image holding body 12 is provided with an LED. The exposure part which irradiates exposure light from may be sufficient.

The electrostatic latent image formed on the image carrier 12 is developed by the developer 15 using a developer,
YMCK toner image of any color.

The primary transfer roll 16 is conveyed while sandwiching the intermediate transfer belt 30 with the image carrier 12,
By applying a transfer bias, an electrostatic attracting force is generated, and the toner image formed on the image carrier 12 is primarily transferred to the intermediate transfer belt 30. After the primary transfer, untransferred residual toner remaining on the image carrier 12 is removed by a cleaning device (not shown). The surface of the image carrier 12 is neutralized by a neutralization device (not shown) and then charged again by the charger 13 for the next image forming cycle.

  The intermediate transfer belt 30 is wound around the support roll 34, the drive roll 20, and the roll 32, and is conveyed in the direction of arrow W by the drive roll 20.

In the image forming apparatus 100 according to the present embodiment, the image forming process is performed in the image forming units 10Y, 10M, 10C at a timing in consideration of the relative positions of the image forming units 10Y, 10M, 10C, and 10K. Performed every 10K, on the intermediate transfer belt 30,
Sequentially, Y, M, C, and K color toner images are overlaid to form a color toner image. When a black and white image is formed, a single color toner image of K color is transferred onto the intermediate transfer belt 30.

  The toner image formed on the intermediate transfer belt 30 is secondarily transferred to the recording paper P by the secondary transfer roll 36. The secondary transfer roll 36 sandwiches the recording paper P conveyed to the secondary transfer position A with the intermediate transfer belt 30 supported by the support roll 34, and generates an electrostatic adsorption force by the applied transfer bias. Thus, the toner image on the intermediate transfer belt 30 is secondarily transferred to the recording paper P.

The recording paper P is stored in the paper feed cassettes 60 and 61 of the paper feed unit 104 arranged in the preceding stage of the image forming unit 102. Then, the recording paper P is fed from one of the paper feeding cassettes 60 and 61 to the image forming unit 102. The fed recording paper P is sent to the secondary transfer position A by a plurality of transport rolls 66 and 67 and an alignment roll 68 of the transport mechanism 64.
Then, as described above, the toner images are collectively transferred from the intermediate transfer belt 30 to the recording paper P by the support roll 34 and the secondary transfer roll 36. As will be described later, the alignment roll 68 according to the present embodiment is mounted on the registration roll unit 80.

  Untransferred residual toner on the intermediate transfer belt 30 that has not been transferred to the recording paper P during the secondary transfer is scraped off and removed by the cleaning blade 42 of the cleaning device 40.

  The recording paper P on which the toner image has been transferred from the intermediate transfer belt 30 is separated from the intermediate transfer belt 30 and then conveyed to the fixing unit 50 by the conveyance belt 38 disposed on the downstream side of the secondary transfer position A. .

  The fixing unit 50 includes a heat fixing roll 52 having a heating element such as a halogen lamp inside a metallic core having thermal conductivity. Further, a pressure roll 56 that applies pressure to the recording paper P conveyed in pairs with the heat fixing roll 52 is also provided.

  Then, the surface of the recording paper P onto which the unfixed toner image is transferred becomes the heat fixing roll 52 side, and when the recording paper P is gripped and conveyed by the heat fixing roll 52 and the pressure roll 56, heat and The toner image is fixed on the recording paper P by the pressure.

The recording paper P on which the toner image is fixed by the fixing unit 50 is sent to the paper discharge unit 106. And
The recording paper P is discharged to the paper discharge tray 72 by the paper discharge mechanism 110 of the paper discharge unit 106 as shown by the arrow S in FIG.

  Further, the image forming apparatus 100 according to the present embodiment reverses the front and back of the recording paper P on which the toner image is fixed on one side, conveys the recording paper P to the secondary transfer position A again, and the other side. A new toner image is also transferred from the intermediate transfer belt 30 to the surface, and a mechanism capable of printing on both sides of the recording paper P is provided.

  Specifically, the recording paper P is reversed by the reverse conveyance mechanism 70 of the paper discharge unit 106, and then conveyed to the conveyance mechanism 64 via the conveyance path 74. The other surface of the recording paper P is again conveyed by the conveyance mechanism 64. Is transferred to the secondary transfer position A on the intermediate transfer belt 30 side.

  Then, after the toner image is transferred to the other surface of the recording paper P, the toner image is similarly fixed to the other surface by the fixing unit 50, and the sheet is discharged onto the discharge table 72 by the discharge mechanism 110 of the discharge unit 106. Discharged.

  The image forming unit 102 further includes a control unit 90, and the control unit 90 performs overall control of the entire image forming apparatus 100. With reference to FIG. 2, the main configuration of the electric system including control unit 90 of image forming apparatus 100 according to the present embodiment will be described.

  As shown in FIG. 2, the control unit 90 includes a CPU (Central Processing Unit) 90A, a ROM (Read Only Memory) 90B, and a RAM (Random Access Memory) 90C. Each of them is connected to each other via a bus BUS such as an address bus, a data bus, and a control bus.

  The ROM 90B stores various programs such as a program for controlling the entire image forming apparatus 100 and an inclination angle adjustment processing program described later. Then, the CPU 90A reads the program from the ROM 90B, develops it in the RAM 90C, and executes it, thereby performing various controls.

  In addition, a UI (User Interface) panel 92 and an image processing unit 94 are connected to the bus BUS.

  The UI panel 92 includes, for example, a touch panel display in which a transmissive touch panel is superimposed on a display. Various types of information are displayed on the display surface of the display, and information and instructions are received when the user touches the touch panel. In this embodiment, an example in which the UI panel 92 is applied has been described. However, the present invention is not limited to this, and a display unit such as a liquid crystal display and an operation unit provided with a numeric keypad and operation buttons are provided. It is good also as a form provided separately.

  The image processing unit 94 performs predetermined image processing such as image compression, scaling, color conversion, gradation processing, and the like on image data transferred from an image reading device (not shown), the control unit 90, or the like. . The image data subjected to the image processing is transmitted to the exposure control unit 98, and an electrostatic latent image is formed by the exposure unit 14 based on the image data after the image processing under the control of the exposure control unit 98.

The bus BUS further includes an image forming unit 102 which is each component of the image forming apparatus 100.
A paper feed unit 104 and a paper discharge unit 106 are connected. Each unit constituting the image forming unit 102 is connected to the bus BUS. FIG. 2 illustrates a registration roll unit control unit 96 that controls a registration roll unit 80 described later and an exposure control unit 98 that controls the exposure unit 14. Others are omitted.

By the way, when the relatively thick recording paper P enters the secondary transfer position A (nip portion),
Due to the thickness of the recording paper P, the load applied to the intermediate transfer belt 30 may fluctuate and the intermediate transfer belt 30 may vary in speed. Due to this speed fluctuation, the image formed on the recording paper P may deteriorate such as smear (print blur), banding (band-like density unevenness), color misregistration, and the like.

  With reference to FIG. 3, the relationship between the speed fluctuation of the intermediate transfer belt 30 and the image deterioration will be described. FIG. 3 is a graph showing changes in the speed of the intermediate transfer belt 30 from when the recording paper P enters the secondary transfer position A to when it is discharged.

When the leading edge of the recording paper P enters the secondary transfer position A, a force that pushes the secondary transfer roll 36 and the support roll 34 is generated, and a large load is generated on the intermediate transfer belt 30. On this occasion,
If the drive capability of the drive roll 20 is insufficient, the speed of the intermediate transfer belt 30 may decrease as shown in FIG.

On the other hand, when the trailing edge of the recording paper P is pulled out (discharged) from the secondary transfer position A, the load on the intermediate transfer belt 30 is rapidly reduced, so that there is a margin in the driving capability of the driving roll 20.
As shown in FIG. 3, the speed of the intermediate transfer belt 30 may increase.

  Due to the speed fluctuations of the intermediate transfer belt 30 as described above, for example, when the image is primarily transferred from the image carrier 12 to the intermediate transfer belt 30, a shift in the transfer position is caused, thereby causing a color shift or the like. As a result, image deterioration may occur in the secondary transfer of the toner image onto the recording paper P.

  Therefore, in the present invention, the other end of the registration roll unit mounted with an alignment roll and fixed at one end is configured to be rotatable, and when the recording paper is thick, it is disposed immediately before the secondary transfer position. In the registration roll unit, the recording paper is rotated while being pinched, and the recording paper is conveyed to the secondary transfer position after being inclined.

As a result, the contact length of the recording paper with respect to the nip at the secondary transfer position gradually increases, so the load at the secondary transfer position is dispersed and the speed fluctuation of the intermediate transfer belt is alleviated.
Deterioration of the image formed on the recording paper is suppressed.

  Further, the inclination angle of the recording paper may be a predetermined constant angle, but in the image forming apparatus 100 according to the present embodiment, the inclination angle is set according to the type of recording paper P, that is, the thickness. I have to. The relationship between the thickness of the recording sheet P and the inclination angle may be set in advance by an experiment using an actual machine or a simulation modeling the actual machine, and may be in the form of a LUT (Look Up Table).

  Hereinafter, the LUT indicating the relationship between the thickness of the recording paper P and the inclination angle may be referred to as an “inclination angle selection LUT”. The inclination angle selection LUT may be stored in advance in storage means such as the ROM 90B. Note that when creating the tilt angle selection LUT, the tilt angle may be given when the thickness of the recording paper P is equal to or greater than a predetermined threshold. The threshold value may be set in advance by an experiment using an actual machine or a simulation modeling an actual machine.

  With reference to FIG. 4, the inclination angle adjustment process in the registration roll unit 80 according to the present embodiment will be described in more detail. FIG. 4 is a plan view when the alignment roll 68 and the support roll 34 are viewed from the upper side to the lower side in FIG.

As will be described later, the registration roll unit 80 is rotatable about the fixed one end C, and the other end is rotatable, and the registration roll unit 80 is rotated by an angle θr as a whole with the recording paper P held between the mounted alignment rolls 68. Thus, the inclination angle θr can be given to the recording paper P. here,
The inclination angle in the present embodiment refers to an angle formed by a side parallel to the conveyance direction of the recording paper P and the conveyance direction of the recording paper P.

In the tilt angle adjustment processing according to the present embodiment, after the recording paper P to be used for printing is supplied from the paper feed cassette 60 or 61, first, the transport roll 66 is not tilted, that is, the tilt angle is 0. After being adjusted to a state of °, it is transported by the transport roll 66.
The inclination angle of the recording paper P by the conveyance roll 66 is adjusted by, for example, adjusting the leading edge of the recording paper P to the gap between the pair of the conveyance rolls 66 so that there is no inclination. At this time, the registration roll unit 80 is disposed at a reference position in contact with a positioning 210 described later, and is in a state where the inclination angle θr = 0 °.

Next, when the head of the recording paper P is detected by a detection means (not shown) arranged upstream of the registration roll unit 80, the rotation axis of the alignment roll 68 (the rotation axis 214 shown in FIG. 5A) is used. The rotation around the center is started, and the recording paper P is held between the pair of alignment rolls 68.
The registration roll 68 may be rotated after the recording paper P hits the registration roll 68.

  Next, the nipping of the recording paper P by the pair of transport rolls 66 is released (released), and then the registration roll is held with the recording paper P nipped between the pair of alignment rolls 68 as shown in FIG. The unit 80 is rotated by a predetermined angle θr. As a result, the recording sheet P is given an inclination angle θr. Here, the rotation angle θr of the registration roll unit 80 is the inclination angle θp to be applied to the recording paper P. That is, θp = θr. The specific value of θp according to the present embodiment is an angle within several degrees, for example, within 5 °.

  Subsequently, as shown in FIG. 4, the recording paper P is conveyed to the secondary transfer position A while being sandwiched between the alignment rolls 68 mounted on the registration roll unit 80. Then, the recording paper P enters the secondary transfer position A while maintaining the tilt angle θr. Then, the toner image on the intermediate transfer belt 30 is secondarily transferred to the recording paper P while being inclined by the inclination angle θr. The toner image to be secondarily transferred is inclined by the angle θr by being inclined by the inclination angle θr in advance in the exposure unit 14, and therefore the toner image is inclined on the recording paper P. It is formed normally.

  After the conveyance to the secondary transfer position A is completed, the registration roll unit 80 is returned to the reference position. The reference position in the present embodiment is a position where the inclination angle θr = 0 ° or a position determined so that the difference between θr and 0 ° is within a predetermined allowable range.

  Next, the configuration of the registration roll unit 80 according to the present embodiment will be described with reference to FIG. 5A is a plan view when the registration roll unit 80 is viewed from the upper side to the lower side in FIG. 1, and FIG. 5B is a registration roll unit in the depth direction from the front of the page in FIG. FIG.

  As shown in FIG. 5A, the registration roll unit 80 according to the present embodiment includes a pair of alignment rolls 68, a bearing 200, gears 202 and 204, a motor 206, and eccentric cams 208a and 208b (hereinafter collectively referred to as a collective roll). (Referred to as “eccentric cam 208”), positioning 210, and housing 212.

  A pair of alignment rolls 68 is mounted on the registration roll unit 80, and one end of the rotation shaft 214 of the alignment roll 68 is attached to the bearing 200 so as to be rotatable about the rotation shaft 214. In FIG. 1, a gear 202 is provided at the other end of the rotating shaft 214 of the alignment roll 68 on the upper side of the drawing, and is engaged with the gear 204 provided in the motor 206. Under the instruction from the CPU 90A, the registration roll unit control unit 96 controls the motor 206, whereby the alignment roll 68 on the upper side in FIG. 1 rotates, and the recording paper P sandwiched between the alignment rolls 68 becomes two. It is conveyed to the next transfer position A.

  On the other hand, as shown in FIG. 5A, the gears 202 and 204 and the motor 206 are housed in a housing 212, and a pair of eccentric cams 208a and 208b are arranged in contact with both sides of the housing 212. Yes. Since the alignment roll 68 is rotatable about the rotation axis 214 and is rotatable in a plane parallel to the paper surface around the point C, the entire registration roll unit 80 is in a plane parallel to the paper surface. It can be rotated.

  The eccentric cams 208a and 208b can be rotated by motors (not shown) around the rotation shafts 216a and 216b, respectively. As shown in FIG. 5 (b), the eccentric cams 208a and 208b are arranged in the same direction with respect to the rotation shafts 216a and 216b, and are rotated in the same direction in synchronism with each other to move the housing 212 in the direction of arrow D. Move to. By this movement, as shown in FIG. 5A, the registration roll unit 80 rotates around the point C to give the registration roll unit 80 an inclination angle θr.

  The positioning 210 is a terminal that determines a reference position of the registration roll unit 80, that is, a position where the inclination angle θr becomes θr = 0 °, and the registration roll unit 80 is held at the reference position when one side surface of the housing 212 abuts against the positioning 210. Is done. Further, in the tilt angle adjustment process according to the present embodiment, the registration roll unit 80 is returned to the reference position for each of the recording papers P used for printing.

  Next, with reference to FIG. 6, the inclination angle adjustment process executed in the image forming apparatus 100 according to the present embodiment will be described. FIG. 6 is a flowchart showing a processing flow of the tilt angle adjustment processing program executed by CPU 90A of image forming apparatus 100 according to the present embodiment.

  In the process shown in FIG. 6, when an instruction to start execution is given, the CPU 90A reads and executes the inclination angle adjustment process program from storage means such as the ROM 90B.

  In the present embodiment, an example will be described in which the inclination angle adjustment processing program is stored in advance in the ROM 90B or the like. However, the present invention is not limited to this, and a mode in which the tilt angle adjustment processing program is provided in a state of being stored in a computer-readable portable storage medium, a mode in which the program is distributed via wired or wireless communication means, and the like. You may apply.

  In the present embodiment, the tilt angle adjustment process is realized by a software configuration using a computer by executing a program, but the present invention is not limited to this. For example, you may implement | achieve by the hardware structure which employ | adopted ASIC (Application Specific Integrated Circuit), or the combination of a hardware structure and a software structure.

  In image forming apparatus 100 according to the present embodiment, prior to printing, the user inputs the type of recording paper P from, for example, UI panel 92 or the like. The type of the input recording paper P is temporarily stored in a storage unit such as the RAM 90C, for example, and is used when determining the inclination angle of the recording paper P in this inclination angle adjustment processing program.

  In the present embodiment, a mode in which the user inputs the type of the recording paper P and determines the thickness of the recording paper P will be described as an example. However, the present invention is not limited to this. For example, recording is performed in the image forming apparatus 100. The thickness of the recording paper P may be provided, and the thickness of the recording paper P may be measured by the thickness measuring means. In this case, a thickness measuring means such as a light reflection type paper thickness detection sensor may be provided upstream of the registration roll unit 80.

  In FIG. 6, it is assumed that the user has already instructed the image forming apparatus 100 to start printing on the recording paper P.

  Referring to FIG. 6, in step S100, the inclination angle θp of the recording paper P is determined. This determination is executed by reading the thickness of the recording paper P used in the printing process from the RAM 90C or the like, and comparing this thickness with the inclination angle selection LUT stored in the ROM 90B or the like.

  In the next step S102, the inclination angle θp determined in step S100 is sent to the image processing unit 94. Receiving the tilt angle θp, the image processing unit 94 sends image data obtained by rotating the image data to be printed by the tilt angle θp to the exposure control unit 98. The exposure control unit 98 that has received the tilt angle θp controls the exposure unit 14 so as to form an electrostatic latent image on the image carrier 12 by tilting the image to be printed by θp.

In the next step S104, as described above, the inclination angle of the recording paper P is adjusted to 0 ° in the transport roll 66 upstream of the registration roll unit 80.
In the next step S106, conveyance of the recording paper P is started by the conveyance roll 66.

In the next step S108, detection of the leading position of the recording paper P is awaited.
When the leading position of the recording paper P is detected, the pair of transport rollers 66 is released (separated) in the next step S110, and transport by the alignment rollers 68 is started.

  In the next step S112, until the recording paper P reaches the secondary transfer position A, the registration roll unit 80 is rotated by an angle θr while the recording paper P is held by the pair of alignment rolls 68. As described above, in this embodiment, θr = θp. However, the present invention is not limited to this. If necessary, the value of the inclination angle θr may be corrected by multiplying θp by a coefficient k, such as θr = k · θp.

In the next step S114, printing, that is, secondary transfer is started.
In the next step S116, the alignment roll 68 is released.
In the next step S118, the registration roll unit 80 is returned to the reference position.

In the next step S120, it is determined whether or not printing has been completed. If the determination is negative, the process returns to step S104 and printing is continued.
This inclination angle adjustment processing program is terminated. For example, the determination as to whether or not printing has been completed is as follows.
The determination may be made based on whether or not printing of the number of prints set by the user at the start of printing is completed.

  As described above in detail, according to the image forming apparatus 100 according to the present embodiment, the registration roll unit 80 immediately before the secondary transfer position A gives the inclination angle θp to the recording paper P. As compared with the case where the tilt angle is given at 60 or 61, an effect that the tilt angle θp is suppressed from being changed during the conveyance is obtained. In addition, since the inclination angle θp is given to each recording paper P, an effect is obtained that image deterioration is suppressed even if the types of the recording paper P are mixed in one unit of printing (job). Furthermore, since the inclination angle θp is given to the recording paper P by the registration roll unit 80, for example, compared to the case where the inclination angle is given by the support roll 34 and the secondary transfer roll 36, it is easier to handle double-sided printing. The effect that there is.

In the above embodiment, the present invention transfers the toner images of different colors formed on a plurality of image carriers while being superimposed on the running intermediate transfer belt, and then collectively onto the running recording paper. However, the present invention is not limited to this.
For example, the toner image formed on a single image carrier may be applied to a direct transfer method in which a toner image is directly transferred to a recording sheet without using an intermediate transfer belt.

  Further, in the above-described embodiment, the embodiment in which the present invention is applied to the electrophotographic image forming apparatus has been described as an example. However, the present invention is not limited to this, and may be applied to, for example, an inkjet image forming apparatus.

DESCRIPTION OF SYMBOLS 10 Image forming unit 12 Image holding body 13 Charger 14 Exposure part 15 Developer 16 Primary transfer roll 20 Drive roll 30 Intermediate transfer belt 32 Roll 34 Support roll 36 Secondary transfer roll 38 Conveying belt 40 Cleaning device 42 Cleaning blade 50 Fixing part 52 Heat Fixing Roll 56 Pressure Roll 60, 61 Paper Feed Cassette 64 Transport Mechanism 66, 67 Transport Roll 68 Positioning Roll 70 Reverse Transport Mechanism 72 Paper Discharge Stand 74 Transport Path 80 Regist Roll Unit 90 Controller 90A CPU
90B ROM
90C RAM
92 UI panel 94 Image processing unit 96 Registration roll unit control unit 98 Exposure control unit 100 Image forming apparatus 102 Image forming unit 104 Paper feed unit 106 Paper discharge unit 110 Paper discharge mechanism 200 Bearing 202, 204 Gear 206 Motor 208 Eccentric cam 210 Positioning 212 Housing 214, 216 Rotation axis A Secondary transfer position BUS Bus P Recording paper

Claims (9)

A rotating body on which an image is formed on the peripheral surface;
A transfer roll that rotates while holding a recording medium in a gap with the rotating body, and that transfers an image formed on the peripheral surface of the rotating body to the recording medium;
A first transport roll for transporting the recording medium to the gap;
A second transport roll for transporting the recording medium upstream of the first transport roll;
Before the recording medium enters the first conveying roll, the second conveying roll is controlled so that the angle of the recording medium with respect to the rotation axis of the rotating body is within a predetermined threshold; and a control means for the recording medium to control said first conveyor rolls so as to enter into the gap Machinery rolling axis to be inclined at a predetermined angle according to the thickness of the recording medium,
An image forming apparatus including:   A rotating body on which an image is formed on the peripheral surface;
  A transfer roll that rotates while holding a recording medium in a gap with the rotating body, and that transfers an image formed on the peripheral surface of the rotating body to the recording medium;
  One end is fixed and the other end is rotatable about the one end. The other end includes a pair of eccentric cams in contact with both sides of the recording medium in the conveyance direction, and holds the recording medium to the gap. A first transport roll that is a pair of transport rolls for transporting while
  By rotating the pair of eccentric cams synchronously, the other end of the pair of conveying rolls holding the recording medium is rotated by a predetermined angle, and the recording medium is rotated with respect to the rotation axis of the rotating body. Control means for controlling the first transport roll so that the recording medium enters the gap by inclining at the predetermined angle according to the thickness;
  An image forming apparatus including: The control means rotates the other end to the opposite side by the predetermined angle after the conveyance for each recording medium is completed, so that the first conveyance roll returns to the reference position. Control the roll
  The image forming apparatus according to claim 2. The first transport roll is a pair of transport rolls that are fixed at one end and rotatable at the other end around the one end, and transport the recording medium while holding the recording medium to the gap,
The control means rotates the other end of the pair of conveying rolls holding the recording medium by the predetermined angle, thereby tilting the recording medium in the gap. The image forming apparatus according to claim 1 , wherein the first transport roll is controlled to enter. The control means, the conveying said other end after completing the transfer of each recording medium wherein a defined angle only opposite the rotated toward the first transport roll the can back to the reference position first pre The image forming apparatus according to claim 4 , wherein the roll is controlled. The first transport roll includes a pair of eccentric cams in contact with both ends of the recording medium in the transport direction at the other end,
The control means controls the first transport roll so that the recording medium enters the gap by inclining at the predetermined angle by rotating the pair of eccentric cams synchronously. The image forming apparatus according to claim 4 or 5 . A generating unit that generates image information for forming an image on the peripheral surface of the rotating body;
Wherein, any of claims 1 to 6, wherein the image information for forming the image on the rotating body is inclined by the angle predetermined to further control the generating means so as to generate 1 The image forming apparatus described in the item. The control means controls the first transport roll so that the recording medium enters the gap by inclining at the predetermined angle when the thickness of the recording medium is equal to or greater than a predetermined threshold. The image forming apparatus according to any one of claims 1 to 7 . An image holding member for developing the electrostatic latent image formed on the peripheral surface with toner to form a toner image;
The rotating body, an image forming according to any one of claims 1 to claim 8 by transferring a toner image formed on the image carrier is a secondary transfer means for an image on the peripheral surface is formed apparatus.

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