JP6988408B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

Patent Document 1 describes a toner image forming unit that forms a toner image on an intermediate transfer body, a transfer body that transfers the toner image of the intermediate transfer body to a recording material at the transfer unit, and a driving force applied to the intermediate transfer body. An image based on the detection result of a driving source that applies a driving force to the transfer body independently of the intermediate transfer body driving source and a test toner image formed on the intermediate transfer body during a period when the transfer unit does not have a toner image. An execution unit that executes a correction operation to correct the deviation, a storage unit that stores the recording material conveyed to the transfer unit, and an input unit that associates the storage unit with the classification regarding the basis weight and surface property of the recording material. It is characterized by having a drive unit that drives the drive source at a speed corresponding to the classification when image formation is performed with the recording material stored in the storage unit associated with the classification. The image forming apparatus to be used is disclosed.

In Patent Document 2, an image carrier that carries a toner image on its surface and rotates, and a recording medium are conveyed by pressure contact with the image carrier at a predetermined transfer portion, and a toner image on the surface of the image carrier is recorded on the surface of the recording medium. A transfer means for transferring to the transfer portion, an upstream transport means provided on the upstream side of the transfer portion in the transport direction of the recording medium and transporting the recording medium to the transfer portion, and a transfer means provided on the downstream side of the transfer portion in the transport direction of the recording medium. In an image forming apparatus including a downstream transport means for transporting a recording medium from a transfer portion, a control means for changing the transport speed of the recording medium by the upstream transport means and / or the downstream transport means according to the type of the recording medium is provided. An image forming apparatus characterized by having is disclosed.

Japanese Unexamined Patent Publication No. 2017-40690 Japanese Unexamined Patent Publication No. 2002-215000

When a transfer voltage is applied to a recording medium sandwiched between an image holder and a transfer unit to transfer an image formed on the image holder, in order to stably transfer the image from the image holder to the recording medium. It is preferable to keep the positional relationship between the image holder and the recording medium constant, at least during transfer.

However, depending on the type of recording medium, the positional relationship between the image holder and the recording medium before and after the rear end of the recording medium is ejected from the transport section arranged upstream of the transfer section in the transport direction of the recording medium. May change and the image may not be transferred stably.

In the present invention, as compared with the case where the transport speed of the transport unit is fixed regardless of the type of the recording medium, the positions of the image holder and the recording medium before and after the rear end of the recording medium is discharged from the transport unit. It is an object of the present invention to provide an image forming apparatus capable of suppressing a change in a relationship regardless of the type of recording medium.

In order to achieve the above object, the image forming apparatus of the invention according to claim 1 has a transfer unit for transferring an image held in an image holder to a recording medium, and a transfer direction of the recording medium with respect to the transfer unit. The positional relationship between the image holder and the recording medium on the upstream side before and after the transport unit arranged on the upstream side of the recording medium and transporting the recording medium and the rear end of the recording medium are discharged from the transport unit. A control unit that controls the transport speed of the transport unit according to the type of the recording medium is provided so that the change in the recording medium is suppressed, and the period during which the first half region of the recording medium passes through the transport unit is described as described above. The transport unit is controlled so as to have a predetermined reference transport speed regardless of the type of the recording medium, and the latter half region of the recording medium passes through the transport unit, which is slower than the reference transport speed and is slower than the reference transport speed. wherein when the recording medium is thin, the recording medium is controlled to so that to slow the transport speed as compared with the case of the thick paper.

The invention according to claim 2 includes a detection unit that detects environmental information including at least one of temperature and humidity, and the control unit corrects the transport speed based on the environmental information.

The invention according to claim 3 includes a registration unit for registering a correction amount of the transport speed according to the type of the recording medium.

In the invention according to claim 4 , the registration unit transports the recording medium at the transport speed corrected by a plurality of different correction amounts to form a sample image on the recording medium, and the sample image is formed. The correction amount corresponding to the sample image selected by the user is registered.

According to the fifth aspect of the present invention, when the control unit switches the type of the recording medium to be conveyed and the transfer speed is faster than the transfer speed before the switching, the control unit transfers the recording medium after the switching. Delay the start timing.

In the invention according to claim 6, the first driving unit for driving the image holder and the second driving unit for driving the transfer unit are independent of each other, and the control unit is the first driving unit. When the second surface speed of the recording medium by the second driving unit is changed with respect to the first surface speed of the recording medium according to the above, the transport speed is changed according to the change of the second surface speed. Change.

According to the first aspect of the present invention, as compared with the case where the transport speed of the transport unit is fixed regardless of the type of the recording medium, the image holder is before and after the rear end of the recording medium is discharged from the transport unit. It has the effect that the change in the positional relationship between the image and the recording medium can be suppressed regardless of the type of the recording medium.

According to the second aspect of the present invention, as compared with the case where the transport speed is controlled without considering the environmental information, the image holder and the recording medium are provided before and after the rear end of the recording medium is discharged from the transport portion. It has the effect that the change in the positional relationship of the above can be suppressed regardless of the type of the recording medium.

According to the third aspect of the present invention, there is an effect that the transport speed can be finely adjusted.

According to the fourth aspect of the present invention, there is an effect that the user can register the correction amount of the transport speed after actually confirming the image.

According to the fifth aspect of the present invention, even when switching to a transfer speed faster than the transfer speed before switching, collision of recording media is suppressed as compared with the case where the transfer start timing of the recording medium after switching is the same. It has the effect of being able to.

According to the invention of claim 6 , the image is retained before and after the rear end of the recording medium is ejected from the transport portion, as compared with the case where the transport speed is not changed even though the second surface speed is changed. It has the effect of suppressing changes in the positional relationship between the body and the recording medium regardless of the type of recording medium.

It is a schematic side view which shows the example of the composition of the main part of the image forming apparatus which concerns on 1st Embodiment. It is a block diagram of the main part of the electric system of the image forming apparatus which concerns on 1st Embodiment. It is a flowchart of image formation processing which concerns on 1st Embodiment. It is a figure which shows an example of the table data which shows the correspondence relation between the type of a paper, and the transfer speed of a resist roll. It is a figure for demonstrating the positional relationship between a paper and a photoconductor drum. It is a figure which shows an example of a sample image. It is a figure which shows an example of the table data which shows the correspondence relation between the type of a paper, the transfer speed of a resist roll, and a correction amount. It is a schematic side view which shows the example of the composition of the main part of the image forming apparatus which concerns on 2nd Embodiment. It is a block diagram of the main part of the electric system of the image forming apparatus which concerns on 2nd Embodiment. This is an example of table data showing the correspondence between humidity and correction amount. It is a flowchart of image formation processing which concerns on 2nd Embodiment.

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

FIG. 1 is a schematic configuration diagram of an image forming apparatus 2. As shown in FIG. 1, the image forming apparatus 2 includes a photoconductor drum 10 as an example of an image holder that rotates in the direction of an arrow, and a charger 12 that charges the photoconductor drum 10.

A laser exposure device 14 (the exposure beam in the figure is indicated by the symbol Bm) for writing an electrostatic latent image on the photoconductor drum 10 and toner are housed on the downstream side of the photoconductor drum 10 in the rotation direction of the charger 12. A developer 16 that visualizes the electrostatic latent image on the photoconductor drum 10 with toner is provided.

Around the photoconductor drum 10, a pre-transfer charger 20 for charging toner on the photoconductor drum 10 prior to electrostatic transfer at the transfer position 18 of the transfer device 4 described later, and a pre-transfer charger 20 formed on the photoconductor drum 10. A transfer unit 22 for transferring the toner image to the paper P as a recording medium at the transfer position 18 is attached. The paper P is an example of a recording medium.

Further, around the photoconductor drum 10, an image density sensor 24 arranged in the vicinity of the photoconductor drum 10 on the downstream side of the transfer position 18 and an image density sensor 24 for adjusting the image density, and residual toner after electrostatic transfer are provided. A pre-cleaning charger 26 for reducing the amount of charge in the photoconductor drum 10 and a drum cleaner 28 for removing residual toner on the photoconductor drum 10 are arranged. Further, the image forming apparatus 2 includes a fixing device 60 for fixing an unfixed toner image transferred to the paper P.

The transfer unit 22 includes a drive roll 30, a transfer roll 32, and a transfer transfer belt 34 stretched by the drive roll 30 and the transfer roll 32. Then, the transfer unit 22 has a function of transferring the toner image on the photoconductor drum 10 to the paper P transported to the transfer position 18, and transports the paper P to which the toner image is transferred at the transfer position 18 to the fuser 60. It has a function to do. Further, the transfer unit 22 has a belt cleaner 38 for cleaning the transfer transfer belt 34.

Further, the image forming apparatus 2 has a paper tray 50 for accommodating a plurality of papers P as a paper transport system, a pickup roll 52 for taking out and transporting the paper P accumulated in the paper tray 50 at a predetermined timing, and a pickup. It is provided with a pair of transport rolls 54 arranged at a plurality of locations while transporting the paper P unwound by the roll 52. Although omitted in FIG. 1, a plurality of paper trays 50 and pickup rolls 52 are provided. Further, the paper transport system includes a transport chute 58 that guides the paper P transported by the transport roll 54 to the transfer device 4.

The transfer device 4 includes a transfer unit 22 provided with the transfer roll 32 described above, a pair of resist rolls 56 that feed the paper P conveyed by the transfer roll 54 to the transfer position 18 at a predetermined timing, and the paper P of the resist roll 56. The paper detection sensor 57 provided on the ejection side of the paper, the lower guide member 70 that guides the paper on the transfer roll 32 side with respect to the transport path of the paper P fed to the transfer position 18, and the paper fed to the transfer position 18. An upper guide member 72 that guides the paper P on the photoconductor drum 10 side with respect to the transport path of P is provided. The resist roll 56 is arranged on the upstream side of the transfer roll 32 in the transport direction of the paper P.

The paper transport system includes a fixing inlet guide 62 that guides the paper P to which the toner image is transferred by the transfer unit 22 to the fixing device 60. The resist roll 56 is an example of a transport unit.

Next, the basic image forming process of the image forming apparatus 2 according to the present embodiment will be described.

In the image forming apparatus 2 as shown in FIG. 1, the exposure beam Bm emitted from the laser exposure device 14 irradiates the photoconductor drum 10. In the photoconductor drum 10, after the surface is charged to a predetermined charging potential by the charging device 12, the surface is scanned and exposed by the laser exposure device 14, and an electrostatic latent image is formed.

Next, the electrostatic latent image formed on the photoconductor drum 10 is developed by the toner of the developing device 16 to obtain a toner image. Further, the toner image formed on the photoconductor drum 10 is charged by the pre-transfer charger 20 as needed, and then transferred to the transfer position 18.

On the other hand, in the paper transport system, the pickup roll 52 rotates at the timing when the toner image on the photoconductor drum 10 is transported to the transfer position 18, and the paper P of a predetermined size is supplied from the paper tray 50. The paper P supplied by the pickup roll 52 is conveyed by the transfer roll 54 and reaches the resist roll 56 via the transfer chute 58. In the resist roll 56, the paper P is temporarily stopped, and the resist roll 56 rotates in accordance with the movement timing of the photoconductor drum 10 on which the toner image is supported. As a result, the position of the paper P and the position of the toner image are aligned, and the paper P is guided by the lower guide member 70 and the upper guide member 72 and sent out to the transfer position 18.

At the transfer position 18, the paper P conveyed at the same timing is sandwiched between the photoconductor drum 10 and the transfer roll 32 via the transfer transfer belt 34 of the transfer unit 22. At that time, a voltage (transfer bias) opposite to the charging polarity of the toner is applied to the transfer roll 32, and a charge having a polarity opposite to the toner charging polarity on the photoconductor drum 10 is applied from the transfer roll 32 to the transfer transfer belt 34. Is given. As a result, the toner image supported on the photoconductor drum 10 is electrostatically transferred onto the paper P at the transfer position 18 pressed by the photoconductor drum 10 and the transfer roll 32. The residual toner adhering to the photoconductor drum 10 after transfer is statically removed by the pre-cleaning charger 26 and then removed by the drum cleaner 28.

After that, the paper P on which the toner image is electrostatically transferred is peeled off from the photoconductor drum 10 in a state of being electrostatically adsorbed on the transfer transfer belt 34 of the transfer unit 22, and is conveyed, and the sheet P is conveyed in the transfer direction of the transfer unit 22. It is sent to the fuser 60 provided on the downstream side.

At the rear end of the transfer transfer belt 34 on the fixing device 60 side, the paper P is peeled from the transfer transfer belt 34 due to the curvature when the transfer transfer belt 34 is wound around the drive roll 30 and the stiffness of the paper P. Then, the paper P is guided by the fixing inlet guide 62 and conveyed to the fixing device 60.

The unfixed toner image on the paper P conveyed to the fuser 60 is fixed on the paper P by undergoing a fixing process by heat and pressure in the fixer 60. Then, the paper P on which the fixed image is formed is conveyed to a paper ejection tray (not shown) of the image forming apparatus 2, and a series of image forming operations is completed. Further, the toner, paper dust, and the like adhering to the transfer transfer belt 34 after the paper P is conveyed are cleaned by the belt cleaner 38.

Next, with reference to FIG. 2, the configuration of a main part of the electrical system of the image forming apparatus 2 according to the present embodiment will be described. Note that FIG. 2 mainly shows the functional parts related to the transfer of the paper P from the resist roll 56 to the transfer position 18, and other configurations are omitted as appropriate.

As shown in FIG. 2, in the image forming apparatus 2 according to the present embodiment, a CPU (Central Processing Unit) 80 that controls the overall operation of the image forming apparatus 2, various programs, various parameters, and the like are stored in advance. It is equipped with a ROM (Read Only Memory) 82. Further, the image forming apparatus 2 includes a RAM (Random Access Memory) 84 used as a work area or the like when executing various programs by the CPU 80, and a non-volatile storage unit 86 such as a flash memory. The CPU 80 is an example of a control unit and a registration unit.

Further, the image forming apparatus 2 includes a communication line I / F (Interface) unit 88 that transmits / receives communication data to / from an external device. Further, the image forming apparatus 2 includes an operation display unit 90 that receives instructions from the user to the image forming apparatus 2 and displays various information regarding the operating status of the image forming apparatus 2 to the user. The operation display unit 90 is, for example, a display button that realizes reception of an operation instruction by executing a program, a display provided with a touch panel on a display surface on which various information is displayed, and a hardware key such as a numeric keypad or a start button. including.

Further, the image forming apparatus 2 includes a driving unit 92 for driving the photoconductor drum 10, a driving unit 94 for driving the transfer roll 32, a driving unit 96 for driving the resist roll 56, and a paper detection sensor 57 for detecting the paper P. I have. Then, each part of the CPU 80, ROM 82, RAM 84, storage unit 86, communication line I / F unit 88, operation display unit 90, drive unit 92, drive unit 94, drive unit 96, and paper detection sensor 57 is an address bus and a data bus. , And are connected to each other via a bus 97 such as a control bus. The drive unit 92 is an example of the first drive unit. Further, the drive unit 94 is an example of the second drive unit.

With the above configuration, the image forming apparatus 2 according to the present embodiment has access to the ROM 82, the RAM 84, and the storage unit 86 by the CPU 80, and communication with the external device via the communication line I / F unit 88. Send and receive data respectively. Further, the image forming apparatus 2 acquires various instruction information via the operation display unit 90 and displays various information to the operation display unit 90 by the CPU 80. Further, the image forming apparatus 2 controls the drive unit 92, the drive unit 94, and the drive unit 96 by the CPU 80, respectively.

Next, the image forming process executed by the CPU 80 will be described. FIG. 3 is a flowchart showing the flow of the image forming process according to the present embodiment. The image forming process shown in FIG. 3 is executed as an example in the present embodiment when image forming information is received from an external device via the communication I / F unit 88.

The image formation information includes information such as image data of an image to be formed on the paper P and image formation conditions. The image forming condition includes information such as the type of paper P specified by the thickness and size of the paper, the density of the image, and the enlargement / reduction ratio of the image. In this embodiment, it is assumed that different types of paper P have different thicknesses of paper P.

In step S100, the type of paper P is acquired. The type of paper P is obtained, for example, from the image forming conditions included in the image forming information.

In step S102, the transfer speed of the resist roll 56 corresponding to the type of paper P acquired in step S100 is set. Specifically, for example, as shown in FIG. 4, the table data TBL showing the correspondence between the type (thickness) of the paper P and the transport speed of the resist roll 56 is stored in advance in the storage unit 86. Then, with reference to the table data TBL, the transfer speed of the resist roll 56 corresponding to the type of paper P acquired in step S100 is acquired. The transport speed means the speed at which the paper P advances along the transport direction.

In the example of FIG. 4, the relationship between the thicknesses of the papers Pa, Pb, and Pc is Pa <Pb <Pc. Further, the relationship between the transport speeds Va, Vb, and Vc of the resist roll 56 is Va <Vb <Vc. That is, as the thickness of the paper becomes smaller, the conveying speed of the resist roll 56 becomes slower. Further, as the thickness of the paper increases, the transport speed of the resist roll 56 increases.

In step S104, the image forming process is executed. That is, the transfer of the paper P is started, the toner image formed on the photoconductor drum 10 is transferred to the paper P by the transfer roll 32 at the transfer position 18, and is fixed by the fixing device 60.

Here, when the paper P is sandwiched between the photoconductor drum 10 and the transfer roll 32 at the transfer position 18 and is conveyed while being sandwiched by the resist roll 56, the paper P is conveyed by the transfer speed of the resist roll 56. The way of bending is different.

For example, as the transfer speed of the resist roll 56 is increased as compared with the transfer speed of the paper P conveyed by the transfer roll 32 and the photoconductor drum 10 (hereinafter referred to as the transfer speed of the transfer roll 32), the paper P is conveyed. Pushed in the direction. Therefore, as the transport speed of the resist roll 56 increases, the amount of bending of the paper P in the direction of arrow UP in FIG. 1 increases, and the paper P is conveyed along the upper guide member 72. On the other hand, as the conveying speed of the resist roll 56 becomes slower, the amount of bending of the paper P in the direction of arrow UP in FIG. 1 becomes smaller, and the paper P is conveyed along the lower guide member 70.

By the way, in order to suppress the occurrence of wrinkles on the paper P and the misalignment of the image, the paper P may be transported in a gently bent state. However, for example, when the paper P is thin paper, if the amount of bending is too large, that is, if the transport speed of the resist roll 56 is too fast, the photoconductor drum 10 and the paper before and after the rear end of the paper P is ejected from the resist roll 56. The positional relationship with P (hereinafter, may be simply referred to as a positional relationship) changes significantly, and there is a risk that the image cannot be transferred stably.

Here, the positional relationship is not limited to these, as shown in FIG. 5, for example. Further, the approach angle θ is an angle formed by the straight line L1 connecting the transfer position 18 and the position 19 where the resist roll 56 sandwiches the paper P, and the paper P, as shown in FIG. Further, as shown in FIG. 5, the distance d is the straight line L1 from the position 21 separated from the transfer position 18 on the upstream side in the transport direction of the paper P within a predetermined range (for example, several millimeters) on the straight line L1. It is a distance from the paper P to the photoconductor drum 10 on the straight line L2 extending in the orthogonal direction.

The transfer speed of the resist roll 56 set in the table data TBL shown in FIG. 4 described above corresponds to the type of the paper P and has a positional relationship before and after the rear end of the paper P is ejected from the resist roll 56. The change is set to be suppressed. Here, suppressing the change in the positional relationship corresponds to, for example, suppressing the occurrence of wrinkles on the paper P and the occurrence of image shift of the toner image transferred to the paper P.

For example, when the paper P is thin paper (paper with a small basis weight), if it is conveyed in a state where the transfer speed is high and the amount of deflection is large, the rigidity is lower than that of thick paper (paper with a large basis weight). Before and after the rear end is ejected from the resist roll 56, the positional relationship is significantly changed as compared with the thick paper. That is, when the rear end of the paper P is ejected from the resist roll 56, the paper P is lowered by gravity, and the approach angle θ of the paper P becomes small. On the other hand, the distance d between the photoconductor drum 10 and the paper P becomes large. In the case of thick paper, the rigidity is relatively high as compared with thin paper, so that the change in the positional relationship before and after the rear end of the paper P is ejected from the resist roll 56 is smaller than that of thin paper.

In the present embodiment, as the thickness of the paper P becomes thinner, the conveying speed of the resist roll 56 is slowed down, so that the paper P is conveyed in a state where the amount of bending of the paper P is smaller than that of the thick paper. Therefore, the change in the positional relationship before and after the rear end of the paper P is ejected from the resist roll 56 is suppressed.

In the present embodiment, the case where the resist roll 56 is controlled at the transfer speed set according to the type of the paper P during the entire period during which the paper P passes through the resist roll 56 has been described. However, the paper P is the resist roll 56. The transport speed of the resist roll 56 is controlled according to the type of the paper P during the period in which a part of the region including the rear end of the paper P, for example, the latter half region of the paper P passes through the resist roll 56. You may do so.

For example, during the period in which the first half region of the paper P passes through the resist roll 56, the resist roll 56 is controlled so as to have a predetermined reference transport speed regardless of the type of the paper P, and the second half region of the paper P is the resist roll 56. In the period of passing through, the transfer speed of the resist roll 56 may be slowed down as the thickness of the paper P decreases, and the transfer speed of the resist roll 56 may be increased as the thickness of the paper P increases.

For the determination of whether or not the latter half region of the paper P passes through the resist roll 56, for example, the elapsed time from the detection of the paper P by the paper detection sensor 57 is such that the first half region of the paper P passes through the resist roll 56. It suffices to determine whether or not the time has been reached. The time for the first half region of the paper P to pass through the resist roll 56 may be calculated based on the transport speed of the paper P and the size of the paper P.

Further, the transfer speed of the transfer roll 32 may be controlled instead of the resist roll 56. For example, during the period in which the first half region of the paper P passes through the resist roll 56, the resist roll 56 is controlled so as to have a predetermined reference transfer speed regardless of the type of the paper P, and the second half region of the paper P is the resist roll 56. In the period of passing through, the transfer speed of the transfer roll 32 may be increased as the thickness of the paper P decreases, and the transfer speed of the transfer roll 32 may be decreased as the thickness of the paper P increases.

Further, when a plurality of image forming processes having different types of paper are continuously received, the type of paper P to be conveyed is switched. In this case, when switching the transport speed of the resist roll 56 to a transport speed faster than the transport speed before switching, that is, when switching from thin paper to thick paper, the thick paper transported later to the thin paper previously conveyed. May collide. In such a case, the timing of starting the transfer of the paper P after switching the type of the paper P may be delayed.

Further, depending on the density of the image to be transferred and the like, the surface speed (second surface speed) at the transfer position 18 of the transfer roll 32 is relative to the surface speed (first surface speed) at the transfer position 18 of the photoconductor drum 10. ) May change. In this case, if the transport speed of the resist roll 56 is left as it is, the positional relationship between the paper P and the photoconductor drum 10 will change. Therefore, the transfer speed of the resist roll 56 may be changed according to the change in the surface speed of the transfer roll 32. For example, when the surface speed of the transfer roll 32 is increased, the transport speed of the resist roll 56 is correspondingly increased, and when the surface speed of the transfer roll 32 is decreased, the resist roll 56 is correspondingly increased. The transport speed may also be slowed down.

Further, in the table data TBL shown in FIG. 4, since the type of paper P is predetermined, other types of paper P cannot be selected, but the user wants to use a type of paper that is not registered in the table data TBL. There is. Further, even with the type of paper registered in the table data TBL, the transport speed registered in the table data TBL may not be appropriate due to factors over time such as wear of the resist roll 56. In such a case, it is preferable that the transport speed of the resist roll 56 can be finely adjusted.

Therefore, the correction amount of the transport speed of the resist roll 56 may be registered according to the type of the paper P recording medium.

For example, when the user wants to use a new type of paper, the paper that is closest to the paper that the user wants to use is selected from the types of paper registered in the table data TBL. Then, the paper P is conveyed by the resist roll 56 at a transfer speed corrected by a plurality of different correction amounts centering on the transfer speed corresponding to the selected paper, and a plurality of sample images are formed on the paper P.

FIG. 6 shows an example of a sample image. The sample image SMP shown in FIG. 6 includes a halftone image HT for confirming image deviation and a ladder image RD for confirming magnification variation. In the present embodiment, the halftone image HT is an image having a density of 50%, but the density is not limited to this. The user confirms the halftone image HT and the ladder image RD of the plurality of sample image SMPs, selects the sample image having the least image deviation and magnification fluctuation, and operates the operation display unit 90 to specify the sample image.

Then, the correction amount corresponding to the sample image SMP selected by the user from the formed sample image SMP is registered in the table data TBL as the data of the new paper type together with the transport speed of the paper type selected by the user. do.

For example, when paper Pa is selected as the paper closest to the paper that the user wants to use, as shown in FIG. 7, the new paper is associated with the transport speed Va and the correction amount E corresponding to the sample image SMP selected by the user. Register in the table data TBL as the type Pd.

Further, when finely adjusting the transport speed of the originally set type of paper P, the resist roll 56 is used at the transport speed corrected by a plurality of different correction amounts centering on the transport speed of the type of paper P to be finely adjusted. The paper P is conveyed to form a plurality of sample image SMPs on the paper P, and the correction amount corresponding to the sample image SMP selected by the user is associated with the originally set transfer speed of the type of paper P and the table data is used. All you have to do is register with TBL.

(Second Embodiment)

Next, the second embodiment will be described. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 8 shows a schematic configuration of the image forming apparatus 2A according to the second embodiment, and FIG. 9 shows a main configuration of an electrical system of the image forming apparatus 2. As shown in FIGS. 8 and 9, the image forming apparatus 2A differs from the image forming apparatus 2 in that the image forming apparatus 2A includes a detecting unit 59 for detecting environmental information including at least one of temperature and humidity.

For example, the higher the humidity, the lower the resistance value of the paper P and the more easily it is affected by the transfer electric field. Therefore, the higher the humidity, the greater the change in the positional relationship between the photoconductor drum 10 and the paper P before and after the rear end of the paper P is ejected from the resist roll 56.

Therefore, the transport speed of the resist roll 56 may be corrected based on the environmental information detected by the detection unit 59. As the environmental information, it is preferable to use the humidity in which the influence of the transfer electric field is easily reflected, but only the temperature may be used, or both the temperature and the humidity may be used.

For example, as shown in FIG. 10, the table data TBL2 showing the correspondence relationship between the humidity and the correction amount of the transport speed is stored in the storage unit 86 in advance. Here, the correction amounts E1 to E3 are set so that the transport speed decreases as the humidity increases and the transport speed increases as the humidity decreases. That is, the higher the humidity, the smaller the amount of bending of the paper P, that is, the direction in which the entry angle θ of the paper P becomes smaller, and the lower the humidity, the larger the amount of bending of the paper P, that is, the entry of the paper P. The angle θ is corrected in the direction of increasing.

Next, the image forming process executed by the CPU 80 will be described. FIG. 11 is a flowchart showing the flow of the image forming process according to the present embodiment.

The image forming process shown in FIG. 10 is different from the image forming process of FIG. 3 in the processes of steps S101 and S102A.

In step S101, the humidity detected by the detection unit 59 is acquired.

In step S102A, the transfer speed of the resist roll 56 corresponding to the type of paper P acquired in step S100 and the humidity acquired in step S102A is set. That is, the transport speed corresponding to the type of paper P acquired in step S100 is acquired from the table data TBL, and the correction amount corresponding to the humidity acquired in step S102A is acquired from the table data TBL2. Then, the transport speed acquired from the table data TBL is corrected by the correction amount acquired from the table data TBL2. As a result, the paper P is conveyed at a transfer speed corresponding to the humidity.

Although the present invention has been described above using the embodiments, the present invention is not limited to the scope described in the embodiments. Various changes or improvements can be made to the embodiments without departing from the gist of the present invention, and the modified or improved embodiments are also included in the technical scope of the present invention.

For example, in the above embodiment, the case where the transfer speed of the resist roll 56 is controlled according to the thickness of the paper has been described, but instead of the thickness of the paper or in addition to the thickness of the paper, the basis weight and rigidity of the paper The transport speed of the resist roll 56 may be controlled according to at least one of the water content and the slipperiness of the surface of the recording medium.

2, 2A Image forming device 4 Transfer device 10 Photoreceptor drum 12 Charger 14 Laser exposure device 16 Developer 22 Transfer unit 24 Image density sensor 32 Transfer roll 56 Resist roll 57 Paper detection sensor 58 Conveyance chute 59 Detection unit 60 Fuser 70 Lower guide member 72 Upper guide member

Claims (6)

A transfer unit that transfers the image held in the image holder to a recording medium,
A transport unit arranged on the upstream side of the transfer unit in the transport direction of the recording medium and transporting the recording medium, and a transport unit
Depending on the type of the recording medium, the change in the positional relationship between the image holder and the recording medium on the upstream side is suppressed before and after the rear end of the recording medium is discharged from the transport unit. A control unit that controls the transfer speed of the transfer unit, and
Equipped with
During the period during which the first half region of the recording medium passes through the transport unit, the transport unit is controlled so as to have a predetermined reference transport speed regardless of the type of the recording medium, and the latter half region of the recording medium is the transport unit. the period for passing through the section, the slower than reference transportation speed, and the case where the recording medium is a thin paper, the image formation wherein a recording medium is controlled to so that to slow the transport speed as compared with the case of thick paper Device. It has a detector that detects environmental information including at least one of temperature and humidity.
The image forming apparatus according to claim 1, wherein the control unit corrects the transport speed based on the environmental information. The image forming apparatus according to claim 1 or 2, further comprising a registration unit for registering a correction amount of the transport speed according to the type of the recording medium. The registration unit transports the recording medium at the transport speed corrected by the plurality of different correction amounts to form a sample image on the recording medium, and the sample selected by the user from the formed sample images. The image forming apparatus according to claim 3, wherein the correction amount corresponding to the image is registered. A claim that the control unit delays the timing of transport start of the recording medium after switching when switching to the transport speed faster than the transport speed before switching when switching the type of the recording medium to be transported. The image forming apparatus according to any one of 1 to 4. The first driving unit that drives the image holder and the second driving unit that drives the transfer unit are independent of each other.
When the control unit changes the second surface speed of the recording medium by the second driving unit with respect to the first surface speed of the recording medium by the first driving unit, the second driving unit The image forming apparatus according to any one of claims 1 to 5, wherein the transport speed is changed according to a change in the surface speed.

Images