JP6558038B2 - Image forming apparatus, image forming apparatus control method, and control apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, an image forming apparatus control method, and a control apparatus, and more particularly to control for maintaining the quality of a developer.

  In recent years, there has been a tendency to digitize information, and image processing apparatuses such as printers and facsimiles used for outputting digitized information and scanners used for digitizing documents have become indispensable devices. Such an image processing apparatus is often configured as a multifunction machine that can be used as a printer, a facsimile, a scanner, or a copier by providing an imaging function, an image forming function, a communication function, and the like.

  Among such image processing apparatuses, electrophotographic image forming apparatuses are widely used in image forming apparatuses used for outputting digitized documents. In an electrophotographic image forming apparatus, an electrostatic latent image is formed by exposing a photosensitive member, and the electrostatic latent image is developed using a developer such as toner to form a toner image. Paper output is performed by transferring the image to paper.

  In such an electrophotographic image forming apparatus, as described above, in the developing unit that develops the electrostatic latent image, the developer stored inside is discharged to maintain the quality. Therefore, a forced discharge operation of the developer is performed. Hereinafter, such a forced discharge operation of the developer is referred to as a refresh operation.

  Such a refresh operation is executed by forming an electrostatic latent image on the photosensitive member for discharging the developer from the developing device. In addition, when forming an electrostatic latent image on a photosensitive member for a refresh operation, it has been proposed to set the range in the main scanning direction to a predetermined range (see, for example, Patent Documents 1 and 2).

  As disclosed in Patent Documents 1 and 2, the range in the main scanning direction when an electrostatic latent image is formed on a photoreceptor for a refresh operation is, for example, the main scanning width of a sheet used for image formation output I can think of it. As a result, the toner scattered by the refresh operation is removed by passing the paper, so that it is possible to prevent the scattered toner from remaining in the apparatus and causing image quality deterioration later.

  However, as described above, when the range in the main scanning direction in which the electrostatic latent image is formed in the refresh operation is limited, if the range in the sub scanning direction for forming the electrostatic latent image is narrow, the amount of developer discharged Will be reduced and not fully refreshed. In addition, the size of the electrostatic latent image to be formed in order to perform sufficient refreshing depends on the amount of developer that has deteriorated in the developing device, that is, the frequency of image formation output and the consumption of developer in image formation output. Since it is also affected by the amount, it is difficult to decide uniformly.

  The present invention has been made in consideration of the above circumstances, and in the electrophotographic image forming apparatus, the developer in the developing device for developing the electrostatic latent image is discharged to maintain the state of the developer. It is an object to avoid the accumulation of scattered toner generated in step 1 and to secure a necessary refresh amount.

In order to solve the above-described problems, according to one aspect of the present invention, an electrostatic latent image formed on a photoreceptor is developed by a developing device and transferred to a recording medium to execute image formation output. An image forming apparatus that performs a state maintaining operation for discharging a deteriorated developer from the developing unit in order to maintain the state of the developer in the developer, and detects a width in a direction perpendicular to the conveyance direction of the recording medium. A medium width detection unit; a discharge amount determination unit that determines a discharge amount of the developer to be discharged in the state maintaining operation based on the amount of the developer consumed in the image forming output; and An electrostatic latent image adjusting unit that determines a size of an electrostatic latent image formed in the state maintaining operation based on a width in a direction perpendicular to a conveyance direction and the determined discharge amount; and the determined electrostatic latent image Electrostatic based on image size Viewed including the optical writing control unit for forming an image, and a conveying guide part that the disposed around the photosensitive member for guiding the conveyance of the recording medium in the conveyance path of the recording medium, the conveyance guide portion, the recording The electrostatic latent image adjusting unit determines a size of the electrostatic latent image formed in the state maintaining operation while avoiding a position corresponding to the convex portion, including a convex portion arranged along a medium conveyance direction. characterized in that it.

  According to the present invention, in the electrophotographic image forming apparatus, the scattered toner generated in the refresh operation for discharging the developer in the developing unit for developing the electrostatic latent image and maintaining the state of the developer is accumulated. And a necessary refresh amount can be secured.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the process cartridge periphery which concerns on embodiment of this invention. FIG. 2 is a perspective view illustrating a configuration around a photosensitive drum and a transfer roller according to an embodiment of the present invention. It is a figure which shows the relationship between the refresh image and paper size which concern on embodiment of this invention. It is a figure which shows the accumulation | storage aspect of the scattering toner which concerns on embodiment of this invention. FIG. 3 is a diagram illustrating a control configuration of the image forming apparatus according to the embodiment of the present invention. It is a figure which shows the example of the main scanning width | variety of the refresh image which concerns on embodiment of this invention. 4 is a flowchart illustrating a refresh operation according to an embodiment of the present invention. It is a figure which shows the example of the refresh image which concerns on embodiment of this invention. It is a figure which shows the example of the refresh image which concerns on embodiment of this invention. FIG. 2 is a diagram illustrating a hardware configuration that realizes a control configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the transfer guide which concerns on embodiment of this invention, and its periphery. It is a figure which shows the transfer guide which concerns on embodiment of this invention, and the surrounding charged state. It is a figure which shows the static elimination function of the paper which concerns on embodiment of this invention. FIG. 6 is a diagram illustrating a toner scattering prevention function by a transfer guide rib according to an embodiment of the present invention. It is a figure which shows the structure of the transfer guide which concerns on embodiment of this invention, and its periphery. It is a figure which shows the transfer guide which concerns on embodiment of this invention, and the surrounding charged state. It is a figure which shows the static elimination function of the paper which concerns on embodiment of this invention. It is a figure which shows the structure of the transfer guide which concerns on embodiment of this invention, and its periphery. It is a figure which shows the structure of the transfer guide which concerns on embodiment of this invention, and its periphery. It is a figure which shows the structure of the transfer guide which concerns on embodiment of this invention, and its periphery.

Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, a monochrome printer employing an electrophotographic method will be described as an example, and a developer refresh operation in a developer for developing an electrostatic latent image will be described as an example. Note that monochrome is an example, and control of the refresh operation according to the present embodiment can be similarly applied to an electrophotographic image forming apparatus that requires a developer refresh operation.

  FIG. 1 is a cross-sectional view showing the overall configuration of the image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, in the image forming apparatus 1 according to the present embodiment, a process cartridge 100, which is an electrophotographic image forming unit, is arranged in the approximate center of the apparatus housing. A photosensitive drum 105, which is a rotating body, is disposed inside the process cartridge 100, and an image developed on the photosensitive drum 105 is transferred to a sheet. A detailed configuration of the process cartridge 100 will be described later.

  A transfer roller 108 is disposed below the process cartridge 100 with a sheet conveyance path interposed therebetween, and a sheet feeding cassette 11 for stacking and storing sheets as recording media is disposed below the transfer roller 108. A high potential is applied to the transfer roller 108, thereby generating a potential difference between the photosensitive drum 105 and the transfer roller 108. The image developed on the photosensitive drum 105 by this potential difference is transferred to a recording medium passing between the photosensitive drum 105 and the transfer roller 108.

  The recording medium fed by the paper feeding device 12 passes between the transfer roller 108 and the photosensitive drum 105 and is guided to the fixing unit 103 to thermally fix the toner image on the surface. The recording medium on which the image is fixed by the fixing device 103 is discharged onto a discharge tray on the upper surface of the image forming apparatus 1 by a discharge roller 13.

  Next, the configuration of the process cartridge 100 will be described with reference to FIG. In the process cartridge 100, the photosensitive drum 105 is rotationally driven in a counterclockwise direction in the drawing by a driving unit (not shown). As the photosensitive drum 105 rotates, a portion of the surface of the photosensitive drum 105 facing the charging roller 104 is charged by the charging roller 104.

  The charged surface of the photosensitive drum 105 reaches a position facing the optical writing device 106 by the rotation of the photosensitive drum 105, and a desired electrostatic force is applied to the surface of the photosensitive drum 105 by the laser light emitted from the optical writing device 106. A latent image is formed. A black toner 101 as a developer is applied to the electrostatic latent image formed in this manner from a developing roller 107a included in the developing device 107, and is visualized as a toner image.

  The photosensitive drum 105 further rotates to reach a position (hereinafter referred to as “transfer position”) where the portion of the surface portion where the image is developed as a toner image faces the transfer roller 108. The paper 102 is conveyed to the transfer position in accordance with the timing when the image on the surface of the photosensitive drum 105 passes the transfer position, and the image is transferred onto the paper 102 by the function of the transfer roller 108.

  The toner remaining on the photosensitive drum 105 without being transferred to the paper 102 reaches the cleaning blade 110 as the photosensitive drum 105 further rotates, and is removed from the surface of the photosensitive drum 105 by the cleaning blade 110. The portion of the surface of the photosensitive drum 105 from which the residual toner has been removed is further conveyed and reaches the charging roller 104, and the same processing as described above is repeated.

  The sheet 102 conveyed from the sheet feeding cassette 11 is sent out to the transfer position at the timing as described above by the registration roller 14. A voltage having a polarity opposite to the charged polarity of the toner image developed on the surface of the photosensitive drum 105 is applied to the transfer roller 108, whereby the toner image on the surface of the photosensitive drum 105 is collectively transferred onto the sheet. The

  When the sheet having the toner image transferred thereon passes through the fixing unit 103, the toner image is fused and fixed to the sheet by heat and pressure. The sheet on which the toner image is fixed is discharged by a discharge roller 13 to a discharge tray formed on the upper surface of the apparatus main body.

  When printing on both sides of the paper, the paper 102 with the toner image fixed on one side of the paper is switched back by the reverse rotation of the paper discharge roller 13 and sent to the paper reversing unit, and the front and back sides of the paper are reversed to register rollers 14. The paper is fed again. An image is formed on the back side of the re-fed paper 102 in the same manner as described above, and is ejected to the paper ejection tray to complete double-sided printing.

  FIG. 3 is a perspective view showing the positional relationship between the photosensitive drum 105, the transfer roller 108, and the transfer guide 109. As shown in FIG. As shown in FIG. 3, the sheet 102 that has passed the transfer position, which is the facing portion between the photosensitive drum 105 and the transfer roller 108, is guided by the transfer guide 109 and conveyed to the fixing device 103. That is, the transfer guide 109 functions as a conveyance guide unit.

  Next, the refresh operation according to the present embodiment will be described. The refresh operation is a state maintaining operation for maintaining the quality of the developer inside the developing device 107 by discharging the developer that has stayed in the developing device 107 without being discharged for a long time. The refresh operation is executed in a state where the sheet 102 is not being conveyed.

  In the refresh operation, an electrostatic latent image corresponding to the amount of developer discharged from the developing device 107 is formed on the photosensitive drum 105 by the optical writing device 106. The electrostatic latent image formed for the refresh operation is developed by the developing unit 107 in the same manner as a normal image forming output, and thereby the developer inside the developing unit 107 is discharged. At this time, an image developed on the photosensitive drum 105 is set as a refresh image.

  In the refresh operation, a voltage having the same polarity as the charging polarity of the toner image is applied to the transfer roller 108. Thus, the refresh image developed on the photosensitive drum 105 is conveyed by the rotation of the photosensitive drum 105 while remaining on the photosensitive drum 105 without being attracted to the transfer roller 108 side in the refresh operation.

  The refresh image on the photosensitive drum 105 that has passed the transfer position reaches the cleaning blade 110. As a result, the refresh image on the photosensitive drum 105 is removed from the photosensitive drum 105 by the cleaning blade 110 and discarded as waste toner.

  In such a refresh operation, scattered toner may be generated when the refresh image passes through the transfer position. For example, the transfer roller 108 generally has a linear velocity difference with respect to the photosensitive drum 105. Since the transfer roller 108 is charged with the same polarity as the charging potential of the toner, a repulsive force acts between the transfer roller 108 and the toner. As a result, the toner on the photoconductive drum 105 may be scattered, which causes scattering.

  The scattered toner adheres to the transfer guide 109, for example. However, the scattered toner does not accumulate in the transfer guide 109 by adhering to the paper conveyed by the subsequent image formation output. Further, the amount of scattering by one refresh operation is very small, and the scattering toner attached to the paper does not have an influence that can be recognized by human eyes.

  However, there are cases in which image formation output is continuously performed on small-sized paper such as A5, A6, and postcard size, and the refresh operation is repeated a plurality of times during that time. In such a case, when a refresh image is formed over the entire range of the photosensitive drum 105 in the main scanning direction, depending on the position on the transfer guide 109, scattered toner may be accumulated without adhering to the paper.

  FIG. 4 is a diagram illustrating the relationship between the paper size and the width of the refresh image in the main scanning direction. In FIG. 4, the main scanning direction range of the refresh image is indicated by the hatched portion. When the toner scattered from the photosensitive drum 105 adheres to the transfer guide 109 without largely moving in the main scanning direction, the distribution of the scattered toner is distributed over the main scanning width of the refresh image.

  When the paper is transported in such a state where the scattered toner is distributed, the scattered toner within the range of the main scanning width of the paper in the scattered toner distribution range adheres to the paper and is cleaned. On the other hand, as indicated by P in FIG. 4, the scattered toner outside the range of the main scanning width of the paper is accumulated as it is without being cleaned by the paper.

  FIG. 5 is a diagram illustrating an aspect of scattered toner. As shown in FIG. 5, the transfer guide 109 is provided with transfer guide ribs 114 that are a plurality of convex portions, and gaps 113 are formed between the transfer guide ribs 114. For example, the scattered toner collects in the transfer guide rib 114 and the gap 113. When the amount of accumulated toner exceeds a certain level, it adheres to the tip of the transfer guide rib 114 and forms a toner reservoir 115 that contacts the paper.

  Therefore, after continuously using a small size paper for image formation output and then printing a larger size paper, the refresh operation is repeatedly performed while the small size paper is continuously used. The toner reservoir 115 as shown in FIG. 5 adheres to a large size sheet, and has an influence that can be recognized visually.

  In order to solve such a problem, the image forming apparatus 1 according to the present embodiment has a function of detecting the size of the paper used for the image forming output, and has a width in the main scanning direction corresponding to the detected size. A refresh image is formed. Thereby, since the width of the refresh image in the main scanning direction does not become larger than the paper size width, the above-described problem can be solved.

  In addition, in order to determine the size of the refresh image in the sub-scanning direction according to the detected size and the amount of developer used for the image forming output, an amount of developer that needs to be discharged for refreshing is discharged. Is possible.

  Here, a control configuration of the image forming apparatus 1 for realizing the function according to the gist of the present embodiment will be described with reference to FIG. As shown in FIG. 6, the image forming apparatus 1 according to the present embodiment includes an engine controller 121, an optical writing control unit 122, a medium width detection unit 123, a discharge amount determination unit 124, and an electrostatic latent image adjustment unit 125.

  The engine controller 121 receives a command from a higher-order controller, and inputs a command for forming an electrostatic latent image corresponding to the image to be imaged and output to the optical writing control unit 122. The engine controller 121 determines whether or not a refresh operation is necessary in the control of the image forming apparatus 1 and performs control for the refresh operation.

  The optical writing control unit 122 controls the optical writing device 106 based on a command input from the engine controller 121 to form an electrostatic latent image on the photosensitive drum 105. The optical writing control unit 122 controls the optical writing device 106 based on a command input from the engine controller 121 to form an electrostatic latent image for a refresh image.

  The medium width detection unit 123 acquires a detection signal of a sensor provided in the conveyance path of the sheet 102, and acquires a width in a direction perpendicular to the sheet conveyance direction used in image formation output, that is, a size in the main scanning direction. To do. The discharge amount determination unit 124 acquires necessary information from the engine controller 121 and determines the discharge amount of the developer to be discharged from the developing device 107 in the refresh operation (hereinafter referred to as “refresh amount”).

  In the image forming apparatus 1, the amount of developer to be consumed within a predetermined period (hereinafter referred to as “specified consumption”) is determined. The discharge amount determination unit 124 obtains developer consumption information from the engine controller 121 every time image formation output is executed, and determines a refresh amount by calculating a difference value from the above-described prescribed consumption amount. . In other words, the discharge amount determination unit 124 determines the refresh amount so that the sum of the developer amount consumed by the image forming output and the refresh amount becomes the specified consumption amount.

  The specified consumption amount is set as the amount of developer to be consumed within a predetermined period. For example, the surface transport distance by the rotation of the photosensitive drum 105 and the electrostatic latent image on the surface of the photosensitive drum 105 are set. It is also possible to set it as a ratio to the amount of developer corresponding to the area determined by the main scanning width of the region where can be formed. In this case, by reading the print area in the image formation output with a dot counter or the like, the amount of toner shortage can be calculated and used as the refresh amount.

  In addition to the case where the above-mentioned prescribed consumption is constant, it may be variable. For example, when a small-size sheet is continuously passed, the toner is deteriorated on the developing roller because there are many portions through which the sheet does not pass, and an abnormal image is likely to be generated due to the fixation of the toner or a decrease in chargeability. Therefore, when the detected paper size is less than the predetermined size, it is preferable to set a large prescribed consumption amount to reduce the risk of occurrence of abnormal images. However, since it becomes a barter against contamination in the apparatus, it is preferable to set an optimum refresh threshold according to the model.

  Further, the refresh operation is executed at the timing after the execution of each image formation output, that is, after the image formation output by one image formation output command, and the amount of developer consumed in the immediately preceding image formation output. The refresh amount may be determined based on this. In this case, the specified consumption amount described above is the amount of developer to be consumed in one image forming output, but the value may be a constant value or the photosensitive drum 105 in the image forming output. It may be a value according to the transport distance.

  Note that when the execution frequency of the refresh operation is set to the timing after the execution of each image formation output, the width of the recording medium detected by the medium width detection unit 123 is the main scan of the recording medium conveyed in the linear image formation output. Width.

  The electrostatic latent image adjustment unit 125 is based on the refresh amount determined by the discharge amount determination unit 124 and the main scanning direction width of the paper 102 acquired by the medium width detection unit 123, and the electrostatic latent image to be formed in the refresh operation. Determine the size of the. With reference to FIGS. 7A and 7B, an electrostatic latent image formed in the refresh operation according to the present embodiment will be described.

FIG. 7A is a diagram illustrating the size of the electrostatic latent image when the width in the main scanning direction acquired by the medium width detection unit 123 is a size corresponding to the short side of the A4 size. In order to satisfy the refresh amount determined by the discharge amount determination unit 124, it is indicated that when the short side of A4 size is set as the width in the main scanning direction, _a range of la is required in the sub scanning direction.

On the other hand, FIG. 7B is a diagram showing the size of the electrostatic latent image when the main scanning direction width acquired by the medium width detecting unit 123 is a size corresponding to the short side of the A5 size. To meet the refresh amount determined at the discharge amount determination unit 124, to the short side of A5 size as the main scanning direction width, it has been shown to require a range of l _b in the sub-scanning direction.

  Next, the refresh operation according to the present embodiment will be described with reference to FIG. The refresh operation according to the present embodiment is executed accompanying a normal image forming output. As shown in FIG. 8, the engine controller 121 executes an image formation output job based on a command input from a host controller (S801).

  In the process of S801, the engine controller 121 notifies the discharge amount determination unit 124 of the amount of developer consumed in the executed job. The discharge amount determination unit 124 that has acquired the consumption amount of the developer calculates the refresh amount based on the above-described specified consumption amount (S802). The discharge amount determination unit 124 inputs the calculated refresh amount to the electrostatic latent image adjustment unit 125.

  On the other hand, the medium width detection unit 123 acquires the width in the main scanning direction of the sheet 102 conveyed in the image forming output based on the sensor output (S803). The medium width detection unit 123 inputs the acquired main scanning width to the electrostatic latent image adjustment unit 125.

  The electrostatic latent image adjustment unit 125 that has acquired the refresh amount and the main scanning width determines the size of the electrostatic latent image as described in FIGS. 7A and 7B (S804), and the optical writing control unit 122. Notify The optical writing control unit 122 that has acquired the size of the electrostatic latent image to be formed from the electrostatic latent image adjustment unit 125 executes a refresh operation according to a command from the engine controller 121 (S805). Such a process completes the refresh operation according to the present embodiment.

  As described above, according to the refresh operation of the image forming apparatus 1 according to this embodiment, the range in the main scanning direction for forming the refresh image is determined based on the main scanning width of the paper used in the image forming output. Therefore, it is possible to avoid the accumulation of scattered toner generated in the refresh operation.

  Then, since the size of the refresh image is determined based on the amount of developer used in the image forming output, the specified consumption amount, and the width in the main scanning direction for forming the electrostatic latent image, Even when the width is limited, a necessary refresh amount can be secured.

  In the above embodiment, the case where no refresh image is formed outside the width in the main scanning direction acquired by the medium width detection unit 123 has been described as an example. However, this is only an example. For example, as shown in FIG. 9A, the refresh image formed outside the main scanning width may be narrower than the inside in the sub-scanning direction to reduce the area. .

  The width in the sub-scanning direction in the outer portion of the main scanning width of the refresh image shown in FIG. 9A can be, for example, the conveyance distance for one rotation of the photosensitive drum 105. As a result, a refresh image can be formed on at least the entire surface of the photoconductive drum 105, and a minimum refresh can be performed.

  In addition, normally, as described in FIGS. 7A and 7B, a refresh image is formed only inside the width in the main scanning direction acquired, and FIG. 9B is displayed every predetermined period or every predetermined transport distance. A small amount of refresh image may be formed as shown in FIG. According to the modes shown in FIGS. 9A and 9B, the deteriorated toner on the developing roller 107a is spread over the entire area in the main scanning direction while reducing the possibility of scattering toner accumulation as described in FIG. It becomes possible to discharge across.

  Further, in the above embodiment, as illustrated in FIGS. 7A and 7B, the case where a solid refresh image is formed within the acquired width in the main scanning direction has been described as an example. In addition, a predetermined pattern image may be used as the refresh image. For example, as shown in FIG. 10A, a mode in which a pattern is formed only in a range corresponding to the gap 113 while avoiding a position corresponding to the transfer guide rib 114 is conceivable.

  According to the embodiment shown in FIG. 10A, it is possible to reduce the possibility that scattered toner adheres to the transfer guide rib 114. Even if the scattered toner is accumulated in the transfer guide 109, the accumulated toner Can be prevented from adhering to the paper and causing image defects that are visually recognizable.

  Further, when it is possible to avoid deterioration of the image due to the accumulated toner by using the pattern as shown in FIG. 10A, as shown in FIG. 10B, outside the acquired width in the main scanning direction. A refresh image having a pattern in the range may be formed.

  The control configuration of the image forming apparatus 1 described with reference to FIG. 6 is realized by the same configuration as that of the information processing apparatus. FIG. 11 is a block diagram showing a hardware configuration for realizing the control configuration shown in FIG. As illustrated in FIG. 11, the image forming apparatus 1 according to the present embodiment includes an engine that executes image formation in addition to the same configuration as an information processing terminal such as a general server or a PC (Personal Computer).

  That is, the image forming apparatus 1 according to the present embodiment includes a CPU (Central Processing Unit) 20, a RAM (Random Access Memory) 21, a ROM (Read Only Memory) 22, an engine 23, a HDD (Hard Disk Drive) 24, and an I / O. F25 is connected via the bus 28. Further, an LCD (Liquid Crystal Display) 26 and an operation unit 27 are connected to the I / F 25.

  The CPU 20 is a calculation unit and controls the operation of the entire image forming apparatus 1. The RAM 21 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 20 processes information. The ROM 22 is a read-only nonvolatile storage medium, and stores programs such as firmware. The engine 23 is a mechanism that actually executes image formation in the image forming apparatus 1.

  The HDD 24 is a non-volatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like. The I / F 25 connects and controls the bus 28 and various hardware and networks. The LCD 26 is a visual user interface for the user to check the state of the image forming apparatus 1. The operation unit 27 is a user interface such as a touch panel or a hard key for the user to input information to the image forming apparatus 1.

  In such a hardware configuration, a program stored in a recording medium such as the ROM 22, the HDD 24, or an optical disk (not shown) is read to the RAM 21, and the CPU 20 performs an operation according to those programs, thereby configuring a software control unit. The A functional block that realizes the functions of the image forming apparatus 1 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

Embodiment 2. FIG.
In the present embodiment, a mode in which the transfer guide 109 is charged with the same polarity as the toner will be described in order to prevent scattered toner from adhering to the transfer guide 109. In addition, about the structure which attaches | subjects the code | symbol similar to Embodiment 1, it shall show the same or an equivalent part, and detailed description is abbreviate | omitted.

  FIG. 12 is a view showing the periphery of the transfer guide 109 according to this embodiment. The transfer guide 109 according to the present embodiment is configured by forming a coating portion 109a on the surface of a metal portion 109b. Further, a neutralizing needle 111 and a neutralizing needle cover 112 are provided between the transfer guide 109, the photosensitive drum 105, and the transfer roller 108.

  As shown in FIG. 3, the coating unit 109 a is formed of a material that is easily charged to the same polarity as the toner due to friction with the paper 102 when the paper 102 is conveyed. In the case of an image forming apparatus that negatively charges the toner, for example, a fluorine-based resin such as Teflon (registered trademark) can be used.

  The metal part 109b is a part serving as a base of the transfer guide 109, and is made of a conductive metal material. The metal portion 109b is configured as a component having a sufficient capacitance due to a sufficient volume.

  As shown in FIG. 3, the static elimination needle 111 has a function of removing charges charged on the paper 102 when the paper 102 is conveyed on the transfer guide 109. For this reason, a voltage having a polarity opposite to the charge charged on the sheet 102 is applied to the charge removal needle 111. The sheet 102 is given a charge having a polarity opposite to the charged charge of the toner in order to transfer the toner. Therefore, the charge applied to the charge removal needle 111 has the same polarity as the charged charge of the toner.

  The static elimination needle cover 112 is a cover provided so as to cover the static elimination needle 111 so that the paper 102 is not damaged by the static elimination needle 111. The charge elimination needle cover 112 according to the present embodiment is made of the same material as the coating portion 109a described above or a material having similar characteristics.

  FIG. 13 is a diagram illustrating the toner of the refresh image formed by the refresh operation and the charged state around the transfer guide 109. FIG. 13 shows an example in which the toner of the refresh image is negatively charged.

  As shown in FIG. 13, the coating portion 109a and the charge removal needle cover 112 are charged to the same negative polarity as the charging polarity of the toner. Further, since the sheet is charged with a positive polarity with respect to the negative polarity of the toner, a charge with a negative polarity is applied to the static elimination needle 111.

  In such a charge state, the charged charges of the parts around the transfer guide 109 have the same polarity as that of the toner of the refresh image, and therefore repulsive force acts between the two. As a result, it is possible to prevent toner from being scattered in the refresh image. Further, even if the toner scatters, it is possible to prevent the scattered toner from adhering to the transfer guide 109 and resulting in smearing of the paper.

  In the refresh operation, since the paper 102 is not conveyed, it is not always necessary to apply a bias to the static elimination needle 111 for removing the charge on the paper 102. However, by applying an electric charge as shown in FIG. 13 in the refresh operation, the effect of preventing toner scattering can be exhibited in the same manner as the coating portion 109a and the charge removal needle cover 112.

  In addition, when a bias is applied to the static elimination needle 111 to remove the electric charge of the paper 102, a predetermined voltage is applied in advance. On the other hand, in the refresh operation, as described above, a bias is applied to assist the function of preventing the toner scattering by the coating unit 109a. The applied voltage at that time may be the same as a normal applied voltage, or may be a voltage determined for preventing toner scattering. Such control is performed by the engine controller 121, for example.

  FIG. 14 is a diagram illustrating the movement of charges when the sheet 102 is conveyed in the normal image forming output, not during the refresh operation. The sheet 102 is charged with a positive polarity because the toner with a negative polarity is transferred. This charged charge is removed by the charge applied to the static elimination needle 111. In addition to the removal by the static elimination needle 111, in the transfer guide 109 according to the present embodiment, the charge is removed by the metal portion 109b.

  A coating portion 109a is formed on the entire upper surface of the metal portion 109b. Since charges are not exchanged between the coating portion 109a and the metal portion 109b, negative charge charged in the coating portion 109a does not move to the metal portion 109b in principle.

  However, the layer of the coating portion 109a is not completely formed over the entire surface of the metal portion 109b, and the thickness of the layer may vary depending on the portion. As for the portion where the layer of the coating portion 109a is very thin or the portion where the coating portion 109a is not formed, as shown in FIG. 14, the positive polarity charge of the paper 102 conveyed on the upper surface side is applied to the metal portion 109b. It will flow.

  Therefore, by forming the coating guide 109a by forming the coating portion 109a on the upper surface of the metal portion 109b, in addition to the above-described effect of preventing the scattering of the toner, the charge removal function of the paper by the charge removal needle 111 can be assisted. .

  Note that the metal portion 109b may be positively provided with a charge eliminating function in addition to the case where the metal portion 109b is configured as a component having a sufficient capacitance as described above. As such an aspect, for example, an aspect in which a bias having the same polarity as that of the toner is applied, or an aspect in which grounding is performed can be considered. As a result, the charge charged on the sheet 102 can be removed by the metal portion 109b.

  FIG. 15 is a diagram illustrating another mode in which the transfer guide 109 is charged to the same polarity as the toner. In the example of FIG. 15, it is assumed that the transfer guide rib 114 and the gap 113 are formed as in the case of FIG.

  In the case of FIG. 15, the transfer guide rib 114 is formed of the same material as the coating part 109a in FIG. As a result, when the paper 102 is conveyed on the transfer guide 109, friction is generated between the transfer guide rib 114 and the paper 102, and the transfer guide rib 114 is charged to the same polarity as the toner charging polarity.

  As a result, during the refresh operation, repulsive force is generated between the toner of the refresh image and the transfer guide rib 114, and the same effects as in FIG. 13, that is, the toner scattering prevention effect and the toner adhesion prevention effect are obtained. Is possible.

  On the other hand, a charge having a polarity opposite to that of the toner is applied to the gap 113. Therefore, the toner scattered in the refresh operation generates a repulsive force with the transfer guide rib 114, but generates an attractive force with the gap 113 and is attracted to the gap 113.

  In the example of FIG. 13, the case where repulsive force is generated between the entire upper surface of the transfer guide 109 and the toner by forming the coating portion 109 a on the upper surface of the metal portion 109 b has been described as an example. However, it is impossible to completely suppress the scattering of toner, and a certain amount of toner is scattered. On the other hand, according to the example of FIG. 15, the toner that has been scattered in this way is attracted to the gap 113.

  As described above, when the sheet 102 is conveyed on the transfer guide 109, the transfer guide rib 114 contacts the sheet 102 in the transfer guide 109, and the gap 113 does not contact the sheet 102. Therefore, according to the example of FIG. 15, the scattered toner is collected in the gap 113 so that the scattered toner adheres to other parts of the apparatus without causing the paper 102 to become dirty, causing a problem. Can be prevented.

  Note that according to the embodiment of FIG. 15, scattered toner accumulates in the gap 113 as time elapses. If the height of the toner accumulated in the gap 113 exceeds the height of the transfer guide rib 114 with respect to the gap 113, the accumulated toner comes into contact with the paper 102 conveyed on the transfer guide 109, and the paper 102 becomes dirty. Become.

  However, the height obtained by accumulating scattered toner is very small. Therefore, if the height of the transfer guide rib 114 is set to about several millimeters, the toner accumulated in the gap 113 does not exceed the height of the transfer guide rib 114.

  In FIG. 15, the case where a charge having a polarity opposite to the charging polarity of the toner is applied to the gap 113 has been described as an example. However, this is merely an example, and for example, the gap 113 may be formed of a material that is easily charged to a polarity opposite to that of the toner, and may be substituted. In addition, since it is sufficient that the gap 113 does not generate repulsive force with the scattered toner, the gap 113 may be formed of a material that is difficult to be charged.

Embodiment 3 FIG.
In the present embodiment, in order to enhance the charge removal effect of the sheet 102, the coating portion 109a is scattered on the upper surface of the metal portion 109b, or the metal portion 109b is scattered on the upper surface of the coating portion 109a. A mode in which the guide 109 is configured will be described. In addition, about the structure which attaches | subjects the code | symbol similar to Embodiment 1, 2, it shall show the same or an equivalent part, and detailed description is abbreviate | omitted.

  FIG. 16 is a view showing the periphery of the transfer guide 109 according to this embodiment. Unlike the second embodiment, the transfer guide 109 according to this embodiment is not formed with the coating portion 109a over the entire upper surface of the metal portion 109b, but is scattered so as to protrude from the upper surface of the metal portion 109b. Thus, a coating portion 109a is formed and configured. That is, the transfer guide 109 according to the present embodiment is configured such that the coating 109a is formed at a position closer to the paper transport path than the metal portion 109b.

  This is because the neutralizing effect of the paper 102 by the metal portion 109b can be obtained even if there is a gap between the metal portion 109b and the paper 102, that is, they are not in contact with each other, but the paper 102 and the coating portion 109a This is because the triboelectric charging by means that they need to be in contact with each other. With such a configuration, the transfer guide 109 according to the present embodiment realizes frictional charging with the sheet 102 by the coating unit 109a, and removes excess charge remaining on the sheet 102 by the metal unit 109b. The neutralization effect is obtained by 109b.

  Note that the metal portion 109b may be positively provided with a charge eliminating function in addition to the case where the metal portion 109b is configured as a component having a sufficient capacitance as described above. As such an aspect, for example, an aspect in which a bias having the same polarity as that of the toner is applied, or an aspect in which grounding is performed can be considered. As a result, the charge charged on the sheet 102 can be removed by the metal portion 109b. However, if an excessive bias is applied to the metal portion 109b, there is a risk of toner scattering due to the toner adhering to the surface of the paper 102.

  Therefore, it is preferable to perform control so that a bias is applied to the metal portion 109b only during the toner refresh operation. Alternatively, the control is preferably performed so that the absolute value of the bias applied to the metal portion 109b is higher during the toner refresh operation than during other operations. Alternatively, it is preferable that the absolute value of the bias applied to the metal portion 109b is controlled to be high only during the toner refresh operation. Such control is performed by the engine controller 121, for example.

  FIG. 17 is a diagram illustrating the toner of the refresh image formed by the refresh operation and the charged state around the transfer guide 109. FIG. 17 shows an example in which the toner of the refresh image is negatively charged.

  As shown in FIG. 17, the coating portion 109a and the charge removal needle cover 112 are charged to the same negative polarity as the charging polarity of the toner. Further, since the sheet is charged with a positive polarity with respect to the negative polarity of the toner, a charge with a negative polarity is applied to the static elimination needle 111.

  In such a charge state, the charged charges of the parts around the transfer guide 109 have the same polarity as that of the toner of the refresh image, and therefore repulsive force acts between the two. As a result, it is possible to prevent toner from being scattered in the refresh image. Further, even if the toner scatters, it is possible to prevent the scattered toner from adhering to the transfer guide 109 and resulting in smearing of the paper.

  FIG. 18 is a diagram illustrating the movement of charges when the sheet 102 is conveyed in the normal image forming output, not during the refresh operation. The sheet 102 is charged with a positive polarity because the toner with a negative polarity is transferred. This charged charge is removed by the charge applied to the static elimination needle 111. In addition to the removal by the static elimination needle 111, in the transfer guide 109 according to the present embodiment, the charge is removed by the metal portion 109b.

  As described above, the transfer guide 109 according to the present embodiment is configured by being scattered so as to protrude from the upper surface of the metal portion 109b and forming the coating portion 109a. Therefore, as shown in FIG. 18, in the portion where the coating portion 109a is not formed, that is, the portion where the metal portion 109b is exposed, the positive polarity charge of the paper 102 conveyed on the upper surface side is transferred to the metal portion 109b. It will flow.

  Accordingly, the transfer guide 109 is configured by being scattered so as to protrude from the upper surface of the metal portion 109b to form the transfer guide 109. In addition to the above-described toner scattering prevention effect, charging of the paper by the static elimination needle 111 is performed. The removal function can be assisted.

  As described above, the transfer guide 109 according to the present embodiment performs the charge removal by the metal portion 109b in addition to the charge removal by the charge removal needle 111, and only the charge removal by the charge removal needle 111 removes the charge of the sheet 102. This is because it may be completely removed, but is actually difficult. In view of this, the transfer guide 109 according to the present embodiment increases the charge removal effect by removing the charge by the metal portion 109b in addition to the charge removal by the charge removal needle 111, and obtains the toner scattering prevention effect. .

  FIG. 19 is a diagram illustrating another mode in which the transfer guide 109 is charged to the same polarity as the toner. In the case of FIG. 19, the transfer guide 109 is configured as a portion where the coating portion 109 a serves as a base instead of the metal portion 109 b, and has an unevenness formed on the upper surface thereof. Further, in the case of FIG. 19, the transfer guide 109 is such that the metal part 109b does not exceed the height of the convex part of the coating part 109a, that is, the coating part 109a is more than the metal part 109b. It is formed at a position close to the paper transport path.

  This is because the neutralizing effect of the paper 102 by the metal portion 109b can be obtained even if there is a gap between the metal portion 109b and the paper 102, that is, they are not in contact with each other, but the paper 102 and the coating portion 109a This is because the triboelectric charging by means that they need to be in contact with each other. With such a configuration, the transfer guide 109 according to the present embodiment realizes frictional charging with the sheet 102 by the coating unit 109a, and removes excess charge remaining on the sheet 102 by the metal unit 109b. The neutralization effect is obtained by 109b.

  FIG. 20 is a diagram illustrating another mode in which the transfer guide 109 is charged to the same polarity as the toner. In the case of FIG. 20, the transfer guide 109 is configured so that the coating portions 109a and the metal portions 109b exist alternately and uniformly in the main scanning direction and the sub-scanning direction.

  The sheet 102 immediately after the transfer is charged with a polarity opposite to that of the toner. Further, the coating portion 109a is charged with the same polarity as the toner by friction between the paper 102 and the coating portion 109a. When such a sheet 102 is conveyed to the transfer guide 109, the frictional charging effect by the coating portion 109a is canceled by the reverse polarity charge of the sheet 102 on the downstream side.

  Therefore, the transfer guide 109 according to the present embodiment is configured as shown in FIG. 20, so that the paper 102 is periodically brought close to the metal portion 109 b to neutralize the paper 102, thereby reverse polarity of the paper 102. It is avoided that the frictional charging effect by the coating portion 109a is canceled by the electric charge. As a result, the transfer guide 109 according to the present embodiment can prevent the scattered toner from adhering to the transfer guide 109 by the coating unit 109a and can obtain the effect of removing the paper 102 from the metal unit 109b.

  Note that, for the charging uniformity of the coating portion 109a, it is preferable that the coating portion 109a and the metal portion 109b are arranged so that the coating portion 109a contacts the paper at at least two places.

  In this case, “the minimum printable paper size in the main scanning direction ≧ (X + Y) × 2 and the minimum printable paper size in the sub-scanning direction ≧ (X + Y) × 2” is satisfied. In addition, the coating portion 109a and the metal portion 109b are disposed. Here, X is the diameter of the coating portion 109a, and Y is the length of the portion that passes through the metal portion 109b in the line segment that connects the centers of the coating portions 109a adjacent in the main scanning direction or the sub-scanning direction. .

  Further, the sheet 102 is the largest and is charged to the reverse polarity of the toner immediately after passing through the transfer nip. Therefore, as shown in FIG. 21, in the transfer guide 109 according to the present embodiment, the closer to the transfer nip, the larger the ratio of the metal portion 109b having the charge eliminating effect to the coating portion 109a, that is, the area of the metal portion 109b. By being configured, it may be configured to achieve uniform charging.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Paper feed cassette 12 Paper feed apparatus 13 Paper discharge roller 14 Registration roller 20 CPU
21 RAM
22 ROM
23 Engine 24 HDD
25 I / F
26 LCD
27 Operation unit 28 Bus 101 Black toner 102 Paper 103 Fixing device 104 Charging roller 105 Photosensitive drum 106 Optical writing device 107 Development device 107a Development roller 108 Transfer roller 109 Transfer guide 109a Coating unit 109b Metal unit 110 Cleaning blade 111 Static elimination needle 112 Static neutralization Needle cover 113 Clearance 114 Rib 115 Toner reservoir 121 Engine controller 122 Optical writing control unit 123 Medium width detection unit 124 Discharge amount determination unit 125 Electrostatic latent image adjustment unit 127 HSYNC oscillation unit 128 VSYNC oscillation unit 129 Signal switching unit 130 Energy saving control unit 130, 130BK, 130M, 130C, 130Y LEDA
311 Page memory 312 LEDA driver 313 CH instruction section

Japanese Patent Laid-Open No. 04-86855 Japanese Patent Laid-Open No. 04-68370

Claims (9)

The electrostatic latent image formed on the photosensitive member is developed by a developing unit and transferred to a recording medium to execute image formation output, and the developer deteriorated to maintain the state of the developer in the developing unit An image forming apparatus that performs a state maintaining operation of discharging the developer from the developing device,
A medium width detector for detecting a width in a direction perpendicular to the conveyance direction of the recording medium;
A discharge amount determination unit for determining a discharge amount of the developer to be discharged in the state maintaining operation based on the amount of the developer consumed in the image forming output;
An electrostatic latent image adjusting unit that determines the size of the electrostatic latent image formed in the state maintaining operation based on the detected width in the direction perpendicular to the conveyance direction of the recording medium and the determined discharge amount;
An optical writing control unit that forms an electrostatic latent image based on the determined size of the electrostatic latent image ;
See containing and a conveying guide part that the disposed around the photosensitive member in the conveying path of the recording medium to guide the conveyance of the recording medium,
The transport guide portion includes a convex portion arranged along the transport direction of the recording medium,
The image forming apparatus, wherein the electrostatic latent image adjusting unit determines a size of an electrostatic latent image formed in the state maintaining operation while avoiding a position corresponding to the convex portion . The state maintaining operation is executed after image formation output by one image formation output command,
The medium width detection unit detects the width of the recording medium conveyed in the image forming output executed immediately before,
The image forming apparatus according to claim 1, wherein the discharge amount determination unit determines the discharge amount of the developer based on the amount of the developer consumed in the image forming output executed immediately before. .   The discharge amount determination unit maintains the state so that the sum of the discharge amount of the developer discharged in the state maintaining operation and the amount of the developer consumed in the image forming output becomes a predetermined discharge amount. 3. The image forming apparatus according to claim 1, wherein an amount of the developer discharged in operation is determined. The discharge amount determination unit is configured such that an area of an image formed by a sum of the discharge amount of the developer discharged in the state maintaining operation and the amount of the developer consumed in the image forming output of the photoconductor . A predetermined ratio or more with respect to the area required by the width in the direction perpendicular to the rotation direction in the region where the electrostatic latent image on the surface can be formed and the distance the surface of the photoreceptor is transported in the image forming apparatus. The image forming apparatus according to claim 3, wherein a discharge amount of the developer discharged in the state maintaining operation is determined.   The electrostatic latent image adjusting unit determines the size of the electrostatic latent image formed in the state maintaining operation with a size within a width in a direction perpendicular to the detected conveyance direction of the recording medium. The image forming apparatus according to any one of claims 1 to 4.   The electrostatic latent image adjusting unit narrows the width in the transport direction of the electrostatic latent image outside the width in the direction perpendicular to the transport direction of the detected recording medium. The image forming apparatus according to claim 1.   The electrostatic latent image adjusting unit sets the width of the electrostatic latent image in the transport direction outside the detected width in the direction perpendicular to the transport direction of the recording medium to one rotation of the photoconductor as a rotating body. The image forming apparatus according to claim 6, wherein the image forming apparatus has a conveyance distance of minutes. The electrostatic latent image formed on the photosensitive member is developed by a developing unit and transferred to a recording medium to execute image formation output, and the developer deteriorated to maintain the state of the developer in the developing unit A method for controlling an image forming apparatus for performing a state maintaining operation for discharging the developer from the developing device,
Detecting a width in a direction perpendicular to the conveying direction of the recording medium;
Determining the discharge amount of the developer to be discharged in the state maintaining operation based on the amount of the developer consumed in the image forming output;
Based on the detected width in the direction perpendicular to the conveyance direction of the recording medium and the determined discharge amount, a conveyance guide is arranged around the photosensitive member in the conveyance path of the recording medium and guides the conveyance of the recording medium. Determining the size of the electrostatic latent image formed in the state maintaining operation while avoiding the position corresponding to the convex portion arranged along the conveyance direction of the recording medium included in the portion ,
A control method for an image forming apparatus, wherein an electrostatic latent image is formed based on the determined size of the electrostatic latent image. The electrostatic latent image formed on the photosensitive member is developed by a developing unit and transferred to a recording medium to execute image formation output, and the developer deteriorated to maintain the state of the developer in the developing unit A control device for an image forming apparatus that performs a state maintaining operation for discharging
A medium width detector for detecting a width in a direction perpendicular to the conveyance direction of the recording medium;
A discharge amount determination unit for determining a discharge amount of the developer to be discharged in the state maintaining operation based on the amount of the developer consumed in the image forming output;
An electrostatic latent image adjusting unit that determines the size of the electrostatic latent image formed in the state maintaining operation based on the detected width in the direction perpendicular to the conveyance direction of the recording medium and the determined discharge amount;
An optical writing control unit that forms an electrostatic latent image based on the determined size of the electrostatic latent image ;
See containing and a conveying guide part that the disposed around the photosensitive member in the conveying path of the recording medium to guide the conveyance of the recording medium,
The transport guide portion includes a convex portion arranged along the transport direction of the recording medium,
The control apparatus for an image forming apparatus, wherein the electrostatic latent image adjusting unit determines a size of an electrostatic latent image formed in the state maintaining operation while avoiding a position corresponding to the convex portion .