JP2023161928A - developing device - Google Patents

Abstract

To provide a developing device that prevents scattering of toner from a first scattering prevention sheet and a second scattering prevention sheet having sealing members disposed at both ends.SOLUTION: A sealing member 92 disposed between a first scattering prevention sheet 81 and a second scattering prevention sheet 82 is not fixed to the first scattering prevention sheet 81 and the second scattering prevention sheet 82. The sealing member 92 is not in contact with a photoconductor drum. Since the sealing member 92 is not fixed to the first scattering prevention sheet 81 and the second scattering prevention sheet 82, the first scattering prevention sheet 81 and the second scattering prevention sheet 82 move similarly over the entire area in a longitudinal direction. The first scattering prevention sheet 81 and the second scattering prevention sheet 82 then are not bent or turned up, which prevents generation of a gap through which air including toner passes on a contact surface over the entire area in the longitudinal direction. Consequently, scattering of toner from the first scattering prevention sheet 81 and the second scattering prevention sheet 82 can be prevented.SELECTED DRAWING: Figure 7

Description

The present invention relates to a developing device suitable for use in an image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multifunctional device.

2. Description of the Related Art Image forming apparatuses such as copying machines, printers, facsimile machines, and multifunction devices include a developing device that applies a developer to an electrostatic latent image formed on a photosensitive drum to develop it into a toner image. Two-component developers containing toner and carrier are widely used as developers. In the developing device, the amount of developer supported on the developing sleeve is regulated by a regulating member, and then, as the developing sleeve rotates, the developer is transported to a developing area facing the photosensitive drum. to develop the electrostatic latent image into a toner image. Therefore, in the developing device, toner tends to scatter as the developer is transported by the rotating developing sleeve.

Therefore, conventionally, a first anti-scattering sheet that contacts the developer spiked on the developing sleeve suppresses the toner scattering of the developer conveyed on the developing sleeve, and a second anti-scattering sheet that contacts the photosensitive drum suppresses the toner scattering of the developer conveyed on the developing sleeve. It has been proposed to use a sheet to suppress toner scattering into the machine (Patent Document 1). Further, at both ends of the developing sleeve in the longitudinal direction (rotation axis direction), a sealing member is provided between the first scattering prevention sheet and the second scattering prevention sheet to prevent toner from scattering from the ends of the developing sleeve. are arranged respectively.

Japanese Patent Application Publication No. 2006-221132

However, conventionally, the sealing member is fixed to the first and second anti-scattering sheets. Therefore, as the developing sleeve rotates, the center portion of the first anti-scattering sheet is likely to move away from the developing sleeve due to the developer, while both end portions fixed by the sealing member are difficult to move. Furthermore, while the center portion of the second anti-scattering sheet is easily movable in the rotational direction as the photosensitive drum rotates, both end portions fixed by the sealing member are difficult to move. In other words, conventionally, a difference in movement tends to occur between the center portion and both end portions in the longitudinal direction of the first and second anti-scattering sheets. In that case, the first and second anti-scattering sheets may partially bend or wave, and gaps may form on the contact surfaces of the first and second anti-scattering sheets that contact the developer and the photosensitive drum. This may cause the toner to scatter from the gap.

In view of the above problems, the present invention provides a structure in which a sealing member is disposed between a first shatterproof sheet and a second shatterproof sheet at both ends in the longitudinal direction, when the shatterproof sheets come into contact with each other. To provide a developing device capable of suppressing toner scattering from a gap formed on a surface.

A developing device according to an embodiment of the present invention is a developing device that develops an electrostatic latent image formed on an image carrier into a toner image, and is arranged opposite to the image carrier, and is arranged to face the image carrier, and is arranged to face the image carrier, and is arranged to face the image carrier. a developer carrier capable of carrying a developer; a regulating member that regulates the amount of developer to be carried on the developer carrier; and a regulating member that regulates the amount of developer carried on the developer carrier, and a flexible first sheet member extending so as to come into contact with the developer on the carrier; a first flexible sheet member extending so as to come into contact with the image carrier, the image carrier and the developer carrier; a flexible second sheet member that covers the vertically upper part of the gap formed between the first sheet member and the second sheet member; a supporting member that supports the first sheet member and the second sheet member; Arranged to be sandwiched between the first sheet member and the second sheet member at both ends in the rotation axis direction, and sealing a gap formed by the first sheet member and the second sheet member at the both ends. a sealing member, the sealing member is fixed to the support member so as not to contact the image carrier, and is not fixed to the first sheet member and the second sheet member. It is characterized by

According to the present invention, when the sealing member is disposed between the first shatterproof sheet and the second shatterproof sheet at both ends in the longitudinal direction, the sealing member is disposed between the first shatterproof sheet and the second shatterproof sheet. It is possible to suppress toner scattering by making it difficult to form gaps.

1 is a schematic diagram showing the configuration of an image forming apparatus to which a developing device according to an embodiment is applied. FIG. 1 is a cross-sectional view showing the developing device of the first embodiment. FIG. 1 is a vertical cross-sectional view showing the developing device of the first embodiment. FIG. 3 is a cross-sectional view showing the second chamber of the developing device of the first embodiment. A schematic diagram showing a developing sleeve. Schematic diagram showing a comparative example. Schematic diagram showing a first scattering prevention sheet, a second scattering prevention sheet, and a sealing member. FIG. 3 is a cross-sectional view showing the central portion in the longitudinal direction of the developing device cover. FIG. 3 is a cross-sectional view showing a longitudinal end of the developing device cover. FIG. 3 is a cross-sectional view showing a developing device having two developing screws. FIG. 3 is a cross-sectional view showing a developing device according to a second embodiment. FIG. 3 is a sectional view showing a developing device according to a third embodiment.

[First embodiment]
<Image forming device>
This embodiment will be described below. First, the configuration of an image forming apparatus to which a developing device according to the present embodiment is applied will be explained using FIG. 1. The image forming apparatus 100 shown in FIG. 1 is a tandem intermediate transfer full-color printer in which a plurality of image forming units PY, PM, PC, and PK are arranged along an intermediate transfer belt 51.

Although not shown, the image forming apparatus 100 forms an image on a recording material in response to image information from an external device such as a document reading device connected to the apparatus main body or a personal computer communicably connected to the apparatus main body. form. Examples of the recording material include various types of sheet materials such as plain paper, cardboard, rough paper, textured paper, coated paper, plastic film, cloth, and the like.

In the image forming portion PY, a yellow toner image is formed on the photosensitive drum 1Y and transferred to the intermediate transfer belt 51. In the image forming portion PM, a magenta toner image is formed on the photosensitive drum 1M and transferred to the intermediate transfer belt 51. In the image forming units PC and PK, a cyan toner image and a black toner image are formed on the photosensitive drums 1C and 1K, respectively, and transferred to the intermediate transfer belt 51. The four-color toner images transferred to the intermediate transfer belt 51 are conveyed to the secondary transfer section T2 and secondarily transferred to a recording material (sheet material such as paper, OHP sheet, etc.).

The image forming units PY, PM, PC, and PK have almost the same configuration except that the toner colors used in the developing devices 4Y, 4M, 4C, and 4K are yellow, magenta, cyan, and black. Therefore, in the following, the yellow image forming section PY will be explained as an example, and the explanation of the other image forming sections PM, PC, and PK will be omitted.

In the image forming section PY, a charger 2Y, an exposure device 3Y, a developing device 4Y, and a drum cleaning device 6Y are arranged surrounding a photosensitive drum 1Y as an image carrier. The photosensitive drum 1Y is a photosensitive member formed by applying an organic photoconductive layer to the outer peripheral surface of an aluminum cylinder, for example, and is rotated in the direction of arrow R1 by a motor (not shown). The diameter of the photosensitive drum 1Y is, for example, 80 mm. In this embodiment, the cylindrical photosensitive drum 1Y is shown as an example, but a belt-shaped photosensitive drum may be used.

The charger 2Y is, for example, a corona charging type charging device that uses non-contact charging, and charges the surface of the photosensitive drum 1Y to a uniform potential (for example, -600V) by irradiating charged particles accompanying corona discharge. The exposure device 3Y scans the surface of the charged photosensitive drum 1Y with a laser beam to form an electrostatic latent image on the surface of the photosensitive drum 1Y. The developing device 4Y supplies toner to the photosensitive drum 1Y and develops the electrostatic latent image into a toner image. Details of the developing device 4Y will be described later (see FIGS. 2 to 4).

A primary transfer roller 52Y is arranged at a position facing the photosensitive drum 1Y with the intermediate transfer belt 51 in between. The primary transfer roller 52Y forms a primary transfer portion T1Y of the toner image between the photosensitive drum 1Y and the intermediate transfer belt 51. In the primary transfer portion T1Y, the toner image is primarily transferred from the photosensitive drum 1Y to the intermediate transfer belt 51 by applying a primary transfer voltage to the primary transfer roller 52Y. The drum cleaning device 6Y rubs a cleaning blade on the photosensitive drum 1Y to collect primary transfer residual toner remaining on the photosensitive drum 1Y after the primary transfer. Further, in the drum cleaning device 6Y, the LED is turned on to reduce potential unevenness on the photosensitive drum 1Y that is generated during image formation, thereby preparing for the next image formation.

The intermediate transfer belt 51 is supported by being stretched around rollers such as a drive roller 55, a tension roller 56, and a secondary transfer inner roller 53, and is driven by the drive roller 55 to rotate in the direction of arrow R2. The toner image primarily transferred onto the intermediate transfer belt 51 is secondarily transferred onto a recording material at a secondary transfer portion T2. The secondary transfer portion T2 is a nip portion where the toner image is transferred onto the recording material, which is formed by abutting the outer secondary transfer roller 54 against the intermediate transfer belt 51 stretched around the inner secondary transfer roller 53. By applying a secondary transfer voltage to the secondary transfer outer roller 54, the toner image is secondary transferred from the intermediate transfer belt 51 to the recording material conveyed to the secondary transfer portion T2. The secondary transfer residual toner remaining on the intermediate transfer belt 51 after the secondary transfer is collected from the intermediate transfer belt 51 by the belt cleaning device 8 .

The recording material on which the toner image has been secondarily transferred is conveyed to the fixing device 7. The toner image is fixed on the recording material by applying heat and pressure to the recording material while it is being held and conveyed by the fixing device 7 . The recording material on which the toner image has been fixed by the fixing device 7 is discharged outside the image forming apparatus 100 .

<Developer>
The developing device 4Y contains a developer used for developing a toner image. In this embodiment, a two-component developer containing a non-magnetic toner and a magnetic carrier is used as the developer. The toner has a matrix made of a binder resin containing a colorant, and additives added to the matrix. In this embodiment, a negatively chargeable polyester resin is used as the binder resin. The volume average particle diameter of the toner is preferably "4 μm or more and 10 μm or less." This is because if the particle size of the toner is too small, it becomes difficult to rub against the carrier, making it difficult to control the amount of charge of the toner, and if the particle size of the toner is too large, it becomes impossible to form a fine toner image. In this embodiment, a toner having a volume average particle diameter of "7 μm" was used.

The carrier can be, for example, surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium, rare earths, alloys thereof, or oxide ferrite, and in this embodiment, the average volume particle size is A "40 μm" ferrite carrier was used. This is because if the particle size of the carrier is too small, the carrier tends to adhere to the photosensitive drum 1Y during development, and if the particle size of the carrier is too large, the carrier tends to disturb the toner image during development. Further, in this embodiment, as the initial agent in the unused developing device 4Y, 300 g of developer with a toner to carrier weight ratio of 1:9, that is, a toner concentration of 10% by weight, is stored. are doing. Further, the average charge amount of the toner is set to be 40 μC/g when the toner concentration is 10% in an environment of 23° C. 50%.

<Developing device>
Next, the developing device 4Y will be explained using FIGS. 2 to 5. The developing device 4Y shown in FIG. 2 is a vertical stirring type developing device in which a supply chamber 401 and a recovery chamber 402 are arranged above and below. The developing device 4Y includes a developing container 40 containing developer, a developing sleeve 41 as a developer carrier, a regulating blade 43 as a regulating member, a developing screw 44, a stirring screw 45, and a recovery screw 46. have.

<Developing sleeve>
The developing sleeve 41 is rotatably disposed in the developing container 40 so as to be partially exposed through the opening 40a of the developing container 40 provided at a position facing the photosensitive drum 1Y. The developing sleeve 41 has a magnet roller 42 therein, and is rotated by a motor (not shown) to convey the developer while supporting the developer due to the magnetic force of the magnet roller 42 . The developer rubs against the photosensitive drum 1Y in the development area A in the form of a magnetic brush with spikes. As a result, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1Y, and the electrostatic latent image is developed into a toner image. In this embodiment, the developing sleeve 41 is made of aluminum, and has a diameter of 20 mm. Further, the distance between the developing sleeve 41 and the photosensitive drum 1Y at the closest position is set to, for example, "400 μm".

To explain the surface properties of the developing sleeve 41 and the transportability of the developer, when the surface of the developing sleeve 41 is smooth like a mirror, the friction between the developer and the surface of the developing sleeve 41 is extremely small, so that the developing sleeve 41 is not easily developed. Even when the sleeve 41 rotates, almost no developer is transported. Therefore, by providing appropriate unevenness on the surface of the developing sleeve 41 to generate a frictional force between the surface of the developing sleeve 41 and the developer, the developer is conveyed following the rotation of the developing sleeve 41. I have to. In this embodiment, the surface of the developing sleeve 41 is subjected to a blasting process to provide irregularities with a surface roughness of about 15 μm, for example.

As shown in FIG. 5, the developing sleeve 41 includes a rotating shaft 412 and a roller portion 411 that is provided on the rotating shaft 412 and rotates together with the rotating shaft 412. The above-mentioned blasting process is a processing process in which unevenness is formed on the roller portion 411 by spraying particles such as abrasive powder or glass beads having a predetermined particle size distribution at high pressure. In this specification, in the longitudinal direction (rotation axis direction) of the roller portion 411, the blasted central portion is referred to as the developer carrying region 41a (blast region), and the unblasted end portions are referred to as the brass tube portion 41b (non-blasted region). area). Since the developing sleeve 41 carries and conveys the developer in the developer carrying area 41a, the developer carrying area 41a is provided in an area wider than the maximum area where an image can be formed. For example, if the maximum width of the recording material on which an image can be formed is "330 mm", the developer carrying area 41a is set to a length greater than "330 mm".

<Magnetic roller>
Returning to FIG. 2, the magnet roller 42 disposed inside the developing sleeve 41 is non-rotatably supported by the developing container 40. The magnet roller 42 has a developing magnetic pole S1 at a position facing the developing area A. The magnetic field of the developing magnetic pole S1 causes the developer to stand up as a magnetic brush (also called a magnetic spike), and this magnetic brush contacts the rotating photosensitive drum 1Y in the developing area A, and the charged toner is transferred to the photosensitive drum by electrostatic force. Move to 1Y. The electrostatic latent image is thus developed into a toner image.

In addition to the above-described developing magnetic pole S1, the magnet roller 42 has a total of five poles: N1 pole, N2 pole, N3 pole, and S2 pole. The role of each of these magnetic poles and the flow of developer will be explained. First, as the developer is transported by the developing screw 44, the developer is splashed up and supplied to the developing sleeve 41. Since the developer contains a magnetic carrier, the developer is constrained to the N2 pole. Next, as the developing sleeve 41 rotates, the amount of developer carried on the developing sleeve 41 is regulated to a predetermined amount by the regulating blade 43 when passing through the S2 pole facing the regulating blade 43 . The regulated developer passes through the N1 pole and is supplied to the S1 pole facing the photosensitive drum 1Y. After passing through the development area A and having been supplied with toner to the electrostatic latent image, the developer is released from the magnetic binding force by the magnetic poles between the N3 pole and the N2 pole, and is collected by the collection screw 46. The collected developer is conveyed to the recovery screw 46 and joins with the developer conveyed to the stirring screw 45. Note that omitting the N1 pole between the S2 pole and the S1 pole is not preferable because the transport of the developer may become unstable and density unevenness may occur.

<Regulation blade>
As described above, a magnetic brush of developer is formed on the surface of the developing sleeve 41. The layer thickness of the magnetic brush is adjusted by a regulating blade 43 and the magnetic brush is sent to the developing area A. The regulating blade 43 is a plate-shaped member made of a non-magnetic material such as aluminum, and extends along the longitudinal direction of the developing sleeve 41 upstream of the photosensitive drum 1Y in the rotational direction of the developing sleeve 41. . The regulating blade 43 is disposed in the developing container 40 so that the blade tip faces the rotation center of the developing sleeve 41. When the developing sleeve 41 rotates, the developer on the developing sleeve 41 passes between the tip of the regulating blade 43 and the developing sleeve 41 and is sent to the developing area A. Therefore, by adjusting the gap between the regulating blade 43 and the surface of the developing sleeve 41, the amount of developer carried on the developing sleeve 41 and conveyed to the developing area A is adjusted.

Note that if the gap between the regulating blade 43 and the developing sleeve 41 is too narrow, it is not preferable because foreign matter and toner are likely to clog the gap. Furthermore, if the amount of developer per unit area conveyed by the developing sleeve 41 is too large, the developer may become clogged near the position where the photosensitive drum 1Y and the developing sleeve 41 face each other, or carrier may adhere to the photosensitive drum 1Y. Problems such as On the other hand, if the amount of developer is too small, problems such as a decrease in image density and failure to develop a toner image with a desired density will occur. In this embodiment, after the unused developing device 4Y is installed, the regulating ^blade 43 and the developing sleeve 41 was set to 400 μm.

The developing sleeve 41 conveys the developer regulated in an appropriate amount by the regulating blade 43 to the developing area A facing the photosensitive drum 1Y. A developing voltage in which a DC voltage and an AC voltage are superimposed is applied to the developing sleeve 41 from a power source (not shown). In this embodiment, a developing voltage is applied which is a DC voltage of "-500 V" superimposed with an AC voltage having a peak-to-peak voltage of "1500 V" and a frequency of "12 kHz" in a rectangular wave. Note that the DC voltage value, AC voltage value, and AC voltage waveform are not limited to these.

In the development area A, the development sleeve 41 is rotating in the same forward direction as the rotation direction of the photosensitive drum 1Y. The peripheral speed ratio between the developing sleeve 41 and the photosensitive drum 1Y was set to "1.5 times". The larger the circumferential speed ratio is, the larger the toner supply amount will be, but if it is too large, toner scattering will occur, so it is set in the range of "1 to 2 times". In this embodiment, the circumferential speed of the photosensitive drum 1Y was set to "320 mm/s", and the circumferential speed of the developing sleeve 41 was set to "480 mm/s". In this embodiment, the toner consumption amount at the maximum density is "0.5 mg/cm ² ", and the maximum toner consumption amount for A4 size is "0.31 g".

The developer that is regulated by the regulation blade 43 and has passed through the development area A is collected into the developer container 40 at the intake section 47 . In order to do so, the amount of developer that can pass through the intake portion 47 is greater than the amount of developer after being regulated by the regulation blade 43. This is because the shape of the regulating blade 43, the distance between the regulating blade 43 and the developing sleeve 41, the magnetic force of the magnet roller 42, etc. vary for each mass-produced product, and the developer deteriorates with use. This is so that even if the amount of developer conveyed to the developing sleeve 41 increases, it can be recovered by the intake section 47. In this embodiment, when the amount of developer conveyed to the developing area A is "30 mg/cm ² ", ^the developing sleeve 4 A gap is provided between the developer container 40 and the developer container 40 .

The inside of the developer container 40 is vertically divided into a supply chamber 401 and a collection chamber 402 by a partition wall 48 that projects from the inner surface of the developer container 40 toward the developer sleeve 41 and extends in the longitudinal direction. The developer is contained in a supply chamber 401 and a recovery chamber 402. A developing screw 44 is arranged in the supply chamber 401, and a stirring screw 45 and a recovery screw 46 are arranged in the recovery chamber 402.

As shown in FIG. 3, the developing screw 44 extends in the longitudinal direction within the supply chamber 401, and is rotated by a stirring screw motor (not shown) to move the developer within the supply chamber 401 in a first direction (arrow R4). direction) and supplied to the developing sleeve 41. The stirring screw 45 extends longitudinally within the collection chamber 402 and transports the developer within the collection chamber 402 in a second direction (direction of arrow R5) opposite to the first direction.

The supply chamber 401 and the recovery chamber 402 communicate with each other through a first communication port 404 formed on the upstream side in the first direction and a second communication port 405 formed on the downstream side in the first direction. The second communication port 405 is provided for pumping the developer conveyed through the supply chamber 401 by the developing screw 44 into the recovery chamber 402 . On the other hand, the first communication port 404 allows the developer collected from the developing sleeve 41 and the developer pumped down from the supply chamber 401 to be conveyed through the collection chamber 402 by the stirring screw 45, and from the collection chamber 402 to the supply chamber 401. Provided for pumping water. As the developing screw 44 and stirring screw 45 rotate, the developer is circulated between the supply chamber 401 and the recovery chamber 402 through a first communication port 404 and a second communication port 405 provided at both ends of the partition wall 48 .

As shown in FIG. 4, the recovery chamber 402 is roughly divided into a first recovery chamber 402a in which a stirring screw 45 is disposed, and a second recovery chamber 402b in which a recovery screw 46 is disposed. The recovery screw 46 transports the developer in the second recovery chamber 402b in the opposite direction to the stirring screw 45 (in the direction of arrow R6). In the case of this embodiment, since a partition is not provided between the first recovery chamber 402a and the second recovery chamber 402b, a part of the developer conveyed by the stirring screw 45 and a part of the developer conveyed by the recovery screw 46 are separated. It may be mixed with some of the developer.

The developer transport path in this embodiment includes a first transport path that does not contribute to development: supply chamber 401 -> second communication port 405 -> collection chamber 402 -> first communication port 404 -> supply chamber 401 . Further, there is a second conveyance path that contributes to the development: supply chamber 401 -> development sleeve 41 -> recovery screw 46 -> stirring screw 45 -> first communication port 404 -> supply chamber 401 . Note that in the longitudinal direction of the collection chamber 402, the developer collected from the developing sleeve 41 is directed toward the first communication port 404 by the stirring screw 45, so the amount of developer tends to increase as it goes downstream of the collection chamber 402. The amount of developer near the first communication port 404 increases.

Note that the first communication port 404 of the developing device 4 is provided with a toner concentration sensor (not shown). The toner concentration sensor detects the magnetic permeability of the developer based on a certain volume near the sensor surface in order to detect the ratio of toner to carrier, that is, the toner concentration. A toner bottle (not shown) is connected to the developer container 40, and replenishment developer contained in the toner bottle is supplied thereto. Based on the detection result of the toner concentration sensor, the amount of developer replenished from the toner bottle is adjusted so that the toner concentration of the developer becomes the target toner concentration. That is, when the toner concentration of the developer deviates from the target toner concentration as the toner is consumed as the toner image is developed, the developer is replenished until it matches the target toner concentration. Note that since there is an appropriate range for toner concentration, upper and lower limits are usually set for the target toner concentration. The target toner density is set, for example, in a range of "6% to 12%".

<Scatter prevention sheet>
Returning to FIG. 2, the developer container 40 is provided with a developer cover 49 that covers a portion of the upper part of the developer sleeve 41. As shown in FIG. The developer container 40 and the developer cover 49 may be separate bodies or may be integrated. A first anti-scattering sheet as a first sheet member is attached to the developing unit cover 49 as a supporting member in order to prevent toner from being released when being conveyed in the section from the regulating blade 43 to the developing area A. 81 is supported on the developing sleeve 41 so as to come into contact with the developer that has formed spikes. The toner is released due to the centrifugal force when the developer is transported, and the spikes of developer (magnetic brush) that flutter following the lines of magnetic force when passing through areas with different lines of magnetic force caused by the magnet roller 42. It is possible. The first anti-scattering sheet 81 comes into contact with the spiked developer to reduce the flapping of the developer and suppress release of the toner, thereby preventing the occurrence of scattered toner. Further, the developing device cover 49 is provided with a second scattering sheet member to prevent the toner from being discharged from the opening 40a to the outside of the developing device 4Y and staining other parts even if the toner is released. The prevention sheet 82 is supported so as to come into contact with the photosensitive drum 1Y.

The liberated toner is scattered within the image forming apparatus 100 by the air flow accompanying the conveyance of the developer. The first scattering path is a path of air flowing toward the longitudinal end of the developing sleeve 41 in a first space surrounded by the first scattering prevention sheet 81, the developing sleeve 41, the developing device cover 49, and the regulating blade 43. . That is, air accumulates in the first space, and the air with nowhere to go flows to both ends of the developing sleeve 41 in the longitudinal direction, causing toner to scatter from the gaps between the ends of the developing sleeve 41. The second scattering path includes the first scattering prevention sheet 81 and the second scattering prevention sheet 82 in a second space surrounded by the first scattering prevention sheet 81, the second scattering prevention sheet 82, the developing sleeve 41, and the photosensitive drum 1Y. This is the path of air flowing between the two. That is, air tends to stay in the developing area A, which is the area where the developing sleeve 41 and the photosensitive drum 1Y face each other, and the air that has nowhere to go in the second space is transferred to the first anti-scattering sheet 81 and the second anti-scattering sheet 82. The toner flows to both ends in the longitudinal direction through the gap, thereby scattering the toner to the outside of the developing device 4Y.

In this embodiment, as will be described in detail later, by closing the space between the first scattering prevention sheet 81 and the second scattering prevention sheet 82 at both ends in the longitudinal direction with sealing members 92, the second conveyance path is This is to suppress toner scattering. Before describing this embodiment, a comparative example will be described using FIG. 6.

<Comparative example>
As shown in FIG. 6, in the comparative example, the space between the first anti-scattering sheet 81 and the second anti-scattering sheet 82 is closed by a sealing member 91 at both ends in the longitudinal direction. More specifically, a sealing member 91 is installed to seal the gap formed by the first anti-scattering sheet 81, the second anti-scattering sheet 82, and the developer cover 49 at both ends in the longitudinal direction. The sealing member 91 is made of an elastic member such as urethane foam, and is supported by the developer cover 49, and is attached to both longitudinal ends of the first shatterproof sheet 81 and the second shatterproof sheet 82 with double-sided tape. They are fixed by being pasted on each other. Further, the sealing member 91 fills the gap formed by the first scattering prevention sheet 81, the second scattering prevention sheet 82, and the developing unit cover 49, and is disposed so as to be in contact with the photosensitive drum 1Y. With this configuration, even if the toner in the developer carried by the developing sleeve 41 scatters, the sealing member 91 prevents the scattered toner from being discharged from both ends in the longitudinal direction to the outside of the developing device 4Y. Ru.

In the above comparative example, the sealing member 91 is fixed to the first anti-scattering sheet 81 and the second anti-scattering sheet 82. In the case of the comparative example, the center portion of the first anti-scattering sheet 81 easily moves away from the developing sleeve 41 due to the developer as the developing sleeve 41 rotates. On the other hand, both ends fixed by the sealing member 91 are more difficult to move than the center. Further, the center portion of the second anti-scattering sheet 82 tends to move in the rotational direction as the photosensitive drum 1Y rotates. On the other hand, both ends fixed by the sealing member 91 are more difficult to move than the center. In other words, in the case of the comparative example, the first and second anti-scattering sheets (81, 82) tend to have different movements between the center and both ends in the longitudinal direction, resulting in partial bending and waving. You can hit it. If this happens, a gap will be created between the contact surfaces of the first and second anti-scattering sheets (81, 82), and there is a possibility that the toner will scatter from the gap.

Furthermore, when the sealing member 91 is in contact with the photosensitive drum 1Y, it is difficult to allow the air flowing as the developing sleeve 41 rotates to escape, and the second scattering prevention sheet 82 is turned over by the air, and the toner is released from the turned-up gap. There was some scattering. Further, although the sealing member 91 is made of an elastic material, when it contacts and rubs against the photosensitive drum 1Y, the photosensitive drum 1Y deteriorates to the extent that it becomes difficult to uniformly charge the surface of the photosensitive drum 1Y. There was a risk that this would hasten the process.

In view of the above points, in this embodiment, the sealing member 91 that seals the gap formed by the first anti-scattering sheet 81 and the second anti-scattering sheet 82 at both ends in the longitudinal direction does not come into contact with the photosensitive drum 1Y. The developer cover 49 is fixed to the developing device cover 49 as shown in FIG. In addition, the sealing member 91 is arranged so as to be in contact with each of the first scattering prevention sheet 81 and the second scattering prevention sheet 82 without being fixed to the first scattering prevention sheet 81 and the second scattering prevention sheet 82. be done. Note that a modification may be made in which the sealing member 91 is disposed close to each of the first anti-scattering sheet 81 and the second anti-scattering sheet 82. Hereinafter, this embodiment will be described using FIGS. 7 to 9 while referring to FIG. 2.

In the case of this embodiment, as shown in FIGS. 7, 8, and 9, the first anti-scattering sheet 81 is attached to the inside of the developer cover 49, and the second anti-scattering sheet 82 is attached to the outside of the developer cover 49. The developer cover 49 is fixed to the developer cover 49 so as to be affixed to the developer cover 49 . The first anti-scattering sheet 81 is disposed so as to come into contact with the developer that has stood up on the developing sleeve 41, and the second anti-scattering sheet 82 is disposed so as to come into contact with the photosensitive drum 1Y. The first scattering prevention sheet 81 and the second scattering prevention sheet 82 are fixed to the developer cover 49 with an adhesive member 90 such as double-sided tape or adhesive.

As shown in FIG. 7, the first anti-scattering sheet 81 is longer than the developing sleeve 41 in the longitudinal direction, and is set to a length that allows it to come into contact with the entire developing sleeve 41 in the longitudinal direction. For example, the length of the first anti-scattering sheet 81 is set to "350 mm". The second anti-scattering sheet 82 is longer than the developing sleeve 41, and preferably has a length greater than the paper passing area of the photosensitive drum 1Y through which the recording material can pass. This is to prevent the toner scattered from the developing device 4Y from partially staining the charger 2Y and reducing the uniformity of charging. For example, the second anti-scattering sheet 82 is set to have a length of 370 mm, which is longer than the first anti-scattering sheet 81 and larger than the width of the paper passing area.

As described above, by providing the first anti-scattering sheet 81 on the inside of the developer cover 49 and the second anti-scattering sheet 82 on the outside of the developer cover 49, the first anti-scattering sheet 81 is placed on the developing sleeve 41. The developer that stands up can move toward the sealing member 92. On the other hand, the second anti-scattering sheet 82 is rubbed by the rotating photosensitive drum 1Y and can move toward the sealing member 92, which is downstream in the rotational direction of the photosensitive drum 1Y. At this time, in this embodiment, the first anti-scattering sheet 81 and the second anti-scattering sheet 82 can each move toward the sealing member 92 side without any difference in movement over the entire longitudinal direction. In order to make this possible, the sealing member 92 is not fixed to the first anti-scattering sheet 81 and the second anti-scattering sheet 82. The sealing member 92 simply contacts the first anti-scattering sheet 81 and the second anti-scattering sheet 82 . That is, the sealing member 92 is only supported by the developer cover 49 and is not fixed to both longitudinal ends of the first scattering prevention sheet 81 and the second scattering prevention sheet 82.

As shown in FIG. 7, the sealing member 92 is provided in a range including the brass tube portion 41b outside the developer carrying area 41a, and is in contact with the first scattering prevention sheet 81 and the second scattering prevention sheet 82. . By arranging the sealing member 92 in the range including the brass tube portion 41b, the movement of the first anti-scattering sheet 81 at both ends is not restricted as compared to the comparative example, and contact with the developer is prevented over the entire longitudinal direction. A gap through which air containing toner can escape is less likely to occur on the contact surface. Similarly, in the second anti-scattering sheet 82, the movement of the second anti-scattering sheet 82 is not restricted at both ends as compared to the comparative example, and the toner is removed from the contact surface with the photosensitive drum 1Y over the entire lengthwise direction. It becomes difficult to create gaps where the contained air can escape.

Further, the sealing member 92 includes a first sealing part 92a facing the brass tube part 41b and a second sealing part 92b contacting a part of the developer container 40. The first sealing part 92a is connected to the first anti-scattering sheet 81 and the second anti-scattering sheet in the brass tube part 41b (second area) outside the developer carrying area 41a (first area) that carries the developer in the roller part 411. The gap formed by the sheet 82 is sealed.

As shown in FIG. 9, when viewed from the longitudinal direction, between a straight line Z drawn from the tip of the first anti-scattering sheet 81 to the second anti-scattering sheet 82 at the shortest distance, and the tip 49a of the developer cover 49, The proportion of the first sealing part 92a (more specifically, the cross-sectional area) to the gap formed by the first anti-scattering sheet 81 and the second anti-scattering sheet 82 (see the shaded area) is 10% or more and 70% or less. ” is preferable. According to experiments conducted by the inventors, when the proportion occupied by the first sealing portion 92a is 10%, toner scattering from the second developer transport path is reduced by about 40%; It has been found that when the proportion occupied by the stop portion 92a is 30%, toner scattering from the second developer transport path is reduced by approximately 50%. It was also confirmed that even if the proportion occupied by the first sealing portion 92a was made larger than "30%", the toner scattering from the second developer transport path did not decrease significantly from about "50%". In order to suppress toner scattering and to suppress contact of the first sealing part 92a to the photosensitive drum 1Y in consideration of component errors, the proportion occupied by the first sealing part 92a is set to "40% or more and 60% or less". is more preferable. In this embodiment, it is set to "40%".

Returning to FIG. 7, the second sealing part 92b is continuous with the first sealing part 92a and is formed outside the end of the first anti-scattering sheet 81, and when viewed from the longitudinal direction, at least the first sealing part 92a, and is formed so as to overlap with the gap formed by the first anti-scattering sheet 81 and the second anti-scattering sheet 82. That is, the second sealing part 92b has a larger cross-sectional area than the first sealing part 92a. By having the second sealing part 92b, a part of the gap formed by the first scattering prevention sheet 81 and the second scattering prevention sheet 82 that is not sealed by the first sealing part 92a (see FIG. 9) It is possible to suppress the scattering of the

As described above, in this embodiment, the sealing member 92 disposed between the first shatterproof sheet 81 and the second shatterproof sheet 82 is It is not fixed and is arranged so as not to come into contact with the photosensitive drum 1Y. Since the sealing member 92 is not fixed to the first shatterproof sheet 81 and the second shatterproof sheet 82, the first shatterproof sheet 81 and the second shatterproof sheet 82 are similarly secured over the entire longitudinal direction. Begins to move. As a result, the first anti-scattering sheet 81 and the second anti-scattering sheet 82 are not bent or rolled up, and therefore, gaps from which air containing toner can escape are less likely to occur on the contact surfaces over the entire longitudinal direction. Become. Therefore, toner scattering from the first anti-scattering sheet 81 and the second anti-scattering sheet 82 is suppressed. Further, since the sealing member 92 does not contact and rub against the photosensitive drum 1Y, the deterioration of the photosensitive drum 1Y will not be accelerated.

Note that this embodiment can also be applied to a configuration in which the developing device 4YA includes a plurality of developing sleeves (420, 421) as shown in FIG. In FIG. 10, the same components as the above-described developing device 4Y (see FIG. 2) are given the same reference numerals.

The developing device 4YA shown in FIG. 10 includes a first developing sleeve 420 and a second developing sleeve 421 inside the developing container 40. These developing sleeves 420 and 421 each transport developer to opposing development areas, and supply the developer to the electrostatic latent image formed on the photosensitive drum 1Y (see FIG. 1) to develop the toner image. A developing voltage in which an alternating current voltage is superimposed on a direct current voltage is applied to the developing sleeves 420 and 421 from a power source (not shown). In response, the toner carried on the developing sleeves 420 and 421 is supplied to the photosensitive drum 1Y, and the electrostatic latent image on the photosensitive drum 1Y is developed in a non-contact manner. The developing sleeve 420 performs the first development on the electrostatic latent image on the photosensitive drum 1Y, and the developing sleeve 421 performs the second development on the electrostatic latent image on the photosensitive drum 1Y. In this case, the first developing sleeve 420 is provided with the above-described regulating blade 43, first anti-scattering sheet 81, second anti-scattering sheet 82, and sealing member 92. Thereby, even in the case of the developing device 4YA having a plurality of developing sleeves 420, 421, it is possible to suppress toner scattering and suppress the deterioration of the photosensitive drum 1Y.

<Second embodiment>
Next, a second embodiment will be described using FIG. 11. The second embodiment is different from the developing device 4Y of the first embodiment (see FIG. 2) described above, except that the developing device 4YB includes a sleeve cover 93 and a seal member 94, and the other configurations are the same. It is. Therefore, in the developing device 4YB shown in FIG. 11, the same components as those in the first embodiment are given the same reference numerals, and the description thereof will be simplified or omitted, and mainly the parts different from the first embodiment will be described.

Also in the developing device 4YB of the second embodiment, similarly to the developing device 4Y of the first embodiment described above, the first scattering prevention sheet 81 and the second scattering prevention sheet 82 are arranged between the first scattering prevention sheet 81 and the second scattering prevention sheet 82. 2. A sealing member 92 is provided without being fixed to the scattering prevention sheet 82. As described above, the sealing member 92 only contacts the first anti-scattering sheet 81 and the second anti-scattering sheet 82 .

On the other hand, toner attached to the brass tube portion 41b may be discharged outside the developing device 4YB as the developing sleeve 41 rotates.

Therefore, as shown in FIG. 11, in the developing device 4YB of the second embodiment, a sleeve cover 93 having flexibility as a cover member covers the brass tube portion 41b (see FIG. 5) of the developing sleeve 41 in the circumferential direction. established in A seal member 94 that is not easily charged is provided in a part of the brass tube portion 41b over the entire circumferential area. These sleeve cover 93 and seal member 94 are provided between the first scattering prevention sheet 81 and the developing sleeve 41 when viewed from the longitudinal direction, as shown in FIG.

The seal member 94, which is not easily charged, makes it difficult for toner to adhere to the brass tube portion 41b, and makes it difficult for toner to be discharged outside the developing device 4YB as the developing sleeve 41 rotates. Further, by providing the sleeve cover 93 on the developer container 40 so as to cover the brass tube portion 41b, it is possible to suppress the toner from being discharged to the outside of the developing device 4YB. Note that it is not limited to providing both the seal member 94 and the sleeve cover 93, and only one of them may be provided.

<Third embodiment>
Next, a third embodiment will be described using FIG. 12. In the developing device 4YC shown in FIG. 12, the same components as those in the first embodiment are denoted by the same reference numerals, and the explanation will be simplified or omitted, and mainly the parts different from the first embodiment will be explained. In addition, in FIG. 12, illustration of the above-mentioned sealing member 92 is omitted in order to make the explanation easier to understand.

In the developing device 4YC of the third embodiment as well, similarly to the developing device 4Y of the first embodiment described above (see FIG. 2), a first shatterproof sheet is provided between the first shatterproof sheet 81 and the second shatterproof sheet 82. A sealing member 92 is provided without being fixed to the sheet 81 and the second anti-scattering sheet 82. As described above, the sealing member 92 only contacts the first anti-scattering sheet 81 and the second anti-scattering sheet 82 .

However, in the case of the first embodiment, when the developing sleeve 41 is rotated at "double" rotational speed, for example, the first scattering prevention sheet 81 The toner may float from the developer, and the toner may scatter from the resulting gap. In addition, one reason is that the space formed by the developing sleeve 41, the photosensitive drum 1Y, the first anti-scattering sheet 81, and the second anti-scattering sheet 82 is sealed with the sealing member 92, and the second anti-scattering sheet 82 is The toner may scatter from the gap created by the toner being turned over.

Therefore, in the developing device 4YC of the third embodiment, a structure is provided that communicates with the space formed by the first anti-scattering sheet 81 and the second anti-scattering sheet 82 to discharge air from the space to the outside of the developing device 4YC. A first vent hole 95a and a second vent hole 95b are formed in the developer cover 49. The first ventilation port 95a discharges air in a first space surrounded by the first scattering prevention sheet 81, the developing sleeve 41, the developer cover 49, and the regulating blade 43, and suppresses toner scattering from the end. provided. In order to prevent the toner contained in the air discharged from the first vent 95a from scattering, a filter 96 for collecting toner in the air is provided on the developer cover 49.

The second vent 95b is formed in the developing device cover 49 on the downstream side in the rotational direction of the developing sleeve 41 with respect to the first vent 95a. The second vent 95b exhausts air in a second space surrounded by the first anti-scattering sheet 81, the second anti-scattering sheet 82, the developing sleeve 41, and the photosensitive drum 1Y, and suppresses toner scattering from the end. established for the purpose of In addition to preventing the toner contained in the air discharged from the first vent 95a from scattering, the filter 96 prevents the toner contained in the air discharged from the second vent 95b from scattering. It is provided on the cover 49.

As described above, in the third embodiment, the first anti-scattering sheet 81 can be turned over by forming the first ventilation hole 95a in the developing device cover 49 and discharging air from the first space to the outside of the developing device 4YC. can be suppressed. Further, by forming a second vent 95b in the developing device cover 49 and discharging air from the second space to the outside of the developing device 4YC, it is possible to suppress the second anti-scattering sheet 82 from being turned over. As a result, toner scattering outside the developing device 4YC can be suppressed.

<Summary of this disclosure>
The following configuration is disclosed in this disclosure.

(Configuration 1)
A developing device that develops an electrostatic latent image formed on an image carrier into a toner image,
a developer carrier disposed opposite to the image carrier and capable of carrying a developer containing toner;
a regulating member that regulates the amount of developer carried on the developer carrier;
a flexible first sheet member extending so as to come into contact with the developer on the developer carrier on the downstream side of the regulating member with respect to the rotational direction of the developer carrier;
a flexible second sheet member extending so as to come into contact with the image carrier and covering a vertically upper part of the gap formed between the image carrier and the developer carrier;
a support member that supports the first sheet member and the second sheet member;
A gap formed by the first sheet member and the second sheet member, which is disposed between the first sheet member and the second sheet member at both ends of the developer carrier in the direction of the rotational axis. A sealing member that seals at both ends,
The sealing member is fixed to the support member so as not to contact the image carrier, and is not fixed to the first sheet member and the second sheet member.
A developing device characterized by:

(Configuration 2)
The developer carrier has a rotating shaft and a roller portion that is provided on the rotating shaft and rotates together with the rotating shaft,
The sealing member is disposed outside a region of the roller portion that carries the developer in the direction of the rotational axis.
The developing device according to configuration 1, characterized in that:

(Configuration 3)
Regarding the rotational axis direction, the length of the first sheet member is longer than the roller portion, and the length of the second sheet member is greater than or equal to the length of the first sheet member.
The developing device according to configuration 2, characterized in that:

(Configuration 4)
The sealing member seals a gap formed by the first sheet member and the second sheet member in a second region outside a first region that carries developer in the roller portion with respect to the rotation axis direction. a first sealing part that seals the sheet, and a second sealing part continuous with the first sealing part and formed outside an end of the first sheet member,
When viewed from the rotational axis direction, the first sealing portion accounts for 10% or more and 70% or less of the gap formed by the first sheet member and the second sheet member.
The developing device according to configuration 2 or 3, characterized in that:

(Configuration 5)
The second sealing portion is formed in a size that overlaps at least a gap formed by the first sealing portion, the first sheet member, and the second sheet member when viewed from the rotation axis direction. There is,
The developing device according to configuration 4, characterized in that:

(Configuration 6)
a cover member that circumferentially covers an end of the developer carrier outside a developer carrying area that carries developer in the roller portion with respect to the rotational axis direction;
a sealing member provided in the circumferential direction of the developer carrier outside the developer carrying area in the direction of the rotational axis;
6. The developing device according to any one of configurations 2 to 5, characterized in that:

(Configuration 7)
The support member is formed with a vent that communicates with a space formed by the first sheet member and the second sheet member and allows air to be discharged from the space.
7. The developing device according to any one of configurations 1 to 6, characterized in that:

(Configuration 8)
A filter for collecting toner contained in air discharged from the space is disposed in the support member at the vent hole.
The developing device according to configuration 7, characterized in that:

1Y (1M to 1K)...Image carrier (photosensitive drum), 4Y (4M to 4K, 4YB, 4YC)...Developing device, 41...Developer carrier (developing sleeve), 41a...Developer carrying area (first area) ), 41b... Brass tube part (second region), 43... Regulating member (regulating blade), 49... Supporting member (developing unit cover), 81... First sheet member (first scattering prevention sheet), 82... Second sheet Member (second anti-scattering sheet), 92... Sealing member, 92a... First sealing part, 92b... Second sealing part, 93... Cover member (sleeve cover), 94... Seal member, 95a (95b)... Vent port (first vent, second vent), 96... Filter, 411... Roller part, 412... Rotating shaft

Claims (8)

A developing device that develops an electrostatic latent image formed on an image carrier into a toner image,
a developer carrier disposed opposite to the image carrier and capable of carrying a developer containing toner;
a regulating member that regulates the amount of developer carried on the developer carrier;
a flexible first sheet member extending so as to come into contact with the developer on the developer carrier on the downstream side of the regulating member with respect to the rotational direction of the developer carrier;
a flexible second sheet member that extends so as to come into contact with the image carrier and covers a vertically upper part of the gap formed between the image carrier and the developer carrier;
a support member that supports the first sheet member and the second sheet member;
A gap formed by the first sheet member and the second sheet member, which is disposed between the first sheet member and the second sheet member at both ends in the rotational axis direction of the developer carrier. A sealing member that seals at both ends,
The sealing member is fixed to the support member so as not to contact the image carrier, and is not fixed to the first sheet member and the second sheet member.
A developing device characterized by: The developer carrier has a rotating shaft and a roller portion that is provided on the rotating shaft and rotates together with the rotating shaft,
The sealing member is disposed outside a region of the roller portion that carries the developer in the direction of the rotational axis.
The developing device according to claim 1, characterized in that: Regarding the rotational axis direction, the length of the first sheet member is longer than the roller portion, and the length of the second sheet member is greater than or equal to the length of the first sheet member.
The developing device according to claim 2, characterized in that: The sealing member seals a gap formed by the first sheet member and the second sheet member in a second region outside a first region that carries developer in the roller portion with respect to the rotation axis direction. a first sealing part that seals the sheet, and a second sealing part continuous with the first sealing part and formed outside an end of the first sheet member,
When viewed from the rotational axis direction, the first sealing portion accounts for 10% or more and 70% or less of the gap formed by the first sheet member and the second sheet member.
The developing device according to claim 2 or 3, characterized in that: The second sealing portion is formed in a size that overlaps at least a gap formed by the first sealing portion, the first sheet member, and the second sheet member when viewed from the rotation axis direction. There is,
5. The developing device according to claim 4. a cover member that circumferentially covers an end of the developer carrier outside a developer carrying area that carries developer in the roller portion with respect to the rotational axis direction;
a sealing member provided in the circumferential direction of the developer carrier outside the developer carrying area in the direction of the rotational axis;
The developing device according to claim 2, characterized in that: The support member is formed with a vent that communicates with a space formed by the first sheet member and the second sheet member and allows air to be discharged from the space.
The developing device according to claim 1, characterized in that: A filter for collecting toner contained in air discharged from the space is disposed in the support member at the vent hole.
8. The developing device according to claim 7.

Images