JP2023054595A - Developing device and image forming apparatus - Google Patents

Abstract

To provide a developing device capable of suitably suppressing toner scattering compared with conventional one.SOLUTION: A developing device includes: a developer carrier 50; developing cases 58a-d with an opening for exposing a surface of the developer carrier 50; and a flexible sheet member 70 that contacts a developer carried by the developer carrier 50, passing through the opening, and entering the developing case. In the sheet member 70, an end 70a on an opening side in a developer moving direction and an end 70b opposite to the end on the opening side in a developer moving direction are supported by the developing case, and a non-contact portion which is not in contact with the developing case is formed between both ends in the developer moving direction. The non-contact portion is in contact with the developer carrier in a state where the developer is not on the developer carrier, and is apart from the developer carrier in a state where a predetermined amount of the developer adheres to the developer carrier.SELECTED DRAWING: Figure 1

Description

The present invention relates to a developing device and an image forming apparatus.

2. Description of the Related Art Conventionally, a developing device is known that includes a developer carrier and a development case having an opening that exposes the surface of the developer carrier.
For example, Japanese Patent Application Laid-Open No. 2002-300003 discloses such a developing device, in which a developing case portion is provided in contact with the developer that has entered the developing case through an opening while being carried by a developer carrier, and the developer is conveyed. It is also disclosed that the air around the developer carrying member is also sucked into the developing case. According to this, it is possible to suppress toner scattering from the development area.

Suppression of toner scattering is desired.

In order to solve the above-described problems, the present invention provides a developer carrier, a development case provided with an opening for exposing the surface of the developer carrier, and a development case carried by the developer carrier and passing through the opening. and a flexible sheet member that contacts the developer that has entered the developing case, the sheet member having an end on the side of the opening in the developer moving direction and the opening in the developer moving direction. contacting the developing case, forming a non-contact portion that is not in contact with the developing case between the two ends in the developer moving direction, and the non-contact portion is the developing The developer carrier abuts against the developer carrier when there is no developer on the developer carrier, and separates from the developer carrier when a predetermined amount of developer adheres to the developer carrier. be.

According to the present invention, it is possible to satisfactorily suppress toner scattering.

FIG. 2 is an explanatory diagram of a developing device to which the present invention can be applied; 1 is a schematic configuration diagram of a copying machine; FIG. FIG. 4 is an enlarged explanatory view of four image forming units to which the present invention can be applied; Explanatory drawing of the attachment method of a flexible sheet. Another explanatory view of the method of attaching the flexible sheet. A graph of an experiment on the effect of reducing the amount of scattering and extending the life of the filter. FIG. 11 is an enlarged view of a main portion of a developing device showing a flexible sheet of a modified example; FIG. 11 is an enlarged view of a main portion of a developing device showing an example in which a holding portion holds a downstream end portion of a flexible sheet according to a modification;

An embodiment of a tandem color copier (hereinafter referred to as copier 500) as an image forming apparatus to which the present invention can be applied will be described below. FIG. 2 is a schematic diagram of the copier 500. As shown in FIG. Copier 500 includes document reading section 4 and document conveying section 3 above printer section 100 as a main body section of the image forming apparatus, and paper feeding section 7 below printer section 100 . The document conveying section 3 conveys the document to the document reading section 4, and the document reading section 4 reads the image information of the conveyed document. The paper feed unit 7 includes a paper feed cassette 26 in which transfer paper P, which is a recording medium, is accommodated, and a paper feed roller 27 that feeds the transfer paper P in the paper feed cassette 26 toward the printer unit 100 . A dashed line in FIG. 2 indicates the transport path of the transfer paper P within the copier 500 .

Above the printer section 100 is a paper discharge tray 30 on which transfer paper P on which an output image is formed is stacked. The printer section 100 includes four image forming units 6 (Y, M, C, and K) as image forming sections that form toner images of respective colors (yellow, magenta, cyan, and black), and an intermediate transfer unit 10 . . Each image forming unit 6 (Y, M, C, K) includes a drum-shaped photoreceptor 1 (Y, M, C, K) as an image carrier on which a toner image of each color is formed, and each photoreceptor 1 A developing device 5 (Y, M, C, K) for developing the electrostatic latent image formed on the surface of (Y, M, C, K) is provided.

The intermediate transfer unit 10 includes an intermediate transfer belt 8 and primary transfer bias rollers 9 (Y, M, C, K). The intermediate transfer belt 8 is an intermediate transfer member on which the color toner images formed on the surfaces of the photoreceptors 1 (Y, M, C, K) are superimposed and transferred to form a color toner image. . A primary transfer bias roller 9 (Y, M, C, K) transfers the toner image formed on the surface of each photosensitive member 1 (Y, M, C, K) to the intermediate transfer belt 8. It is a means.

The printer section 100 includes a secondary transfer bias roller 19 for transferring the color toner image on the intermediate transfer belt 8 onto the transfer paper P. As shown in FIG. Further, a registration roller pair 28 is provided to adjust the timing of conveying the transfer paper P sent out by the paper feed roller 27 to the secondary transfer nip where the intermediate transfer belt 8 and the secondary transfer bias roller 19 face each other. Further, the printer section 100 includes a fixing device 20 that fixes the unfixed toner image on the transfer paper P above the secondary transfer nip.
Toner containers 11 (Y, M, C, K) of respective colors are arranged below the discharge tray 30 in the printer section 100 and above the intermediate transfer unit 10 . Each color toner container 11 (Y, M, C, K) accommodates each color (yellow, magenta, cyan, black) toner to be supplied to each developing device 5 (Y, M, C, K).

FIG. 3 is an enlarged explanatory view of one of four imaging units 6 (Y, M, C, K) to which the present invention can be applied. The four image forming units 6 (Y, M, C, K) have substantially the same configuration and operation, except for the different colors of toner used in the image forming process. will be omitted as appropriate. As shown in FIG. 3, the image forming unit 6 is a process cartridge that integrally supports the photoreceptor 1 and the developing device 5, and this process cartridge is detachable from the copying machine 500 main body. . In addition to the developing device 5 around the photoreceptor 1, the image forming unit 6 also includes a photoreceptor cleaning device 2, a lubricant coating device 41, a charging device 40, and the like. In the image forming unit 6 of the present embodiment, the photoreceptor cleaning device 2 is configured to perform cleaning using the cleaning blade 2a, and the charging device 40 is configured to charge using the charging roller 4a.

The operation of the copier 500 of the present embodiment during normal color image formation will be described below. First, when the start button is pressed with the document set on the document table of the document transport section 3, the document is transported from the document table by the transport rollers of the document transport section 3, and is transferred to the contact glass of the document reading section 4. placed on top. Then, the document reading section 4 optically reads the image information of the document placed on the contact glass.

Specifically, the document reading unit 4 scans the image of the document on the contact glass while irradiating light emitted from the illumination lamp. Then, the light reflected by the document forms an image on the color sensor via the mirror group and the lens. The color image information of the document is read by the color sensor for each color separation light of RGB (red, green, blue), and then converted into an electrical image signal. Further, based on the RGB color-separated image signals, the image processing unit performs color conversion processing, color correction processing, spatial frequency correction processing, and the like to obtain yellow, magenta, cyan, and black color image information.

Image information for each color of yellow, magenta, cyan, and black is sent to the writing section. Then, a laser beam L based on the image information of each color is emitted from the writing section toward the corresponding photosensitive member 1 (Y, M, C, K).

On the other hand, the four photoreceptors 1 (Y, M, C, K) rotate clockwise in FIGS. 2 and 3 (in the direction of arrow A in FIG. 3). First, the surface of the photoreceptor 1 (Y, M, C, K) is uniformly charged at the portion facing the charging roller 4a of the charging device 40 (charging step). Thus, the surface of the photoreceptor 1 (Y, M, C, K) becomes charged potential. After that, the charged surface of the photosensitive member 1 (Y, M, C, K) reaches the irradiation position of the laser light L. As shown in FIG. In the writing unit, four light sources emit laser beams L corresponding to image signals corresponding to respective colors. Each laser light L passes through a different optical path for each color component of yellow, magenta, cyan, and black, and irradiates the surface of each photoreceptor 1 (Y, M, C, K) (exposure step).

The laser beam L corresponding to the yellow component is irradiated onto the surface of the photoreceptor 1Y for yellow first from the left side of the paper surface in FIG. At this time, the yellow component laser light L is scanned in the rotation axis direction (main scanning direction) of the yellow photoreceptor 1Y by the polygon mirror rotating at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the surface of the yellow photoreceptor 1Y charged by the charging device 40 .

Similarly, the laser beam L corresponding to the magenta component is irradiated onto the surface of the magenta photoreceptor 1M, which is the second from the left on the page of FIG. 2, to form an electrostatic latent image corresponding to the magenta component. The cyan component laser beam L is applied to the surface of the cyan photoreceptor 1C, which is the third from the left on the page of FIG. 2, to form an electrostatic latent image of the cyan component. The black component laser beam L is irradiated onto the surface of the fourth black photoreceptor 1K from the left in FIG. 2 to form an electrostatic latent image of the black component.

After that, the surfaces of the photoconductors 1 (Y, M, C, K) on which the electrostatic latent images of the respective colors are formed reach positions facing the developing device 5 . Then, from the developer on the developing roller 50 of the developing device 5 (Y, M, C, K) containing the developer composed of each color toner and carrier to the surface of the photoreceptor 1 (Y, M, C, K) to develop the latent image on the photoreceptor 1 (Y, M, C, K) (developing step). The direction in which the developer is conveyed by the developing roller 50 is counterclockwise as indicated by an arrow B. As shown in FIG.

The surfaces of the photoconductors 1 (Y, M, C, K) after passing through the portion facing the developing device 5 reach the portion facing the intermediate transfer belt 8 . Here, primary transfer bias rollers 9 (Y, M, C, K) are installed so as to come into contact with the inner peripheral surface of the intermediate transfer belt 8 at their facing portions. The photoreceptor 1 (Y, M, C, K) faces the primary transfer bias roller 9 (Y, M, C, K) with the intermediate transfer belt 8 interposed therebetween to form a primary transfer nip. At this primary transfer nip, the toner images of the respective colors formed on the photoreceptors 1 (Y, M, C, K) are sequentially superimposed and transferred onto the intermediate transfer belt 8 (primary transfer step). .

After passing through the primary transfer nip, the surface of the photoreceptor 1 reaches a position facing the photoreceptor cleaning device 2 . At a position facing the photoreceptor cleaning device 2, the untransferred toner remaining on the photoreceptor 1 is scraped off by the cleaning blade 2a and collected (photoreceptor cleaning step). The surface of the photoreceptor 1, which has passed through the portion facing the photoreceptor cleaning device 2, passes through the neutralization unit to remove residual charges therefrom. Prepare.

On the other hand, the toner images of each color on the four photosensitive members 1 (Y, M, C, K) are superimposed and transferred, and the surface of the intermediate transfer belt 8 carrying the color toner images moves counterclockwise in FIG. and reaches the secondary transfer nip, which is a position facing the secondary transfer bias roller 19 . Also, the transfer paper P fed by the paper feed roller 27 from the paper feed cassette 26 containing the transfer paper P passes through the transport guide, is guided to the registration roller pair 28, hits the registration roller pair 28, and is once Stop. The transfer paper P that hits the registration roller pair 28 is conveyed toward the secondary transfer nip at the timing when the color toner image formed on the intermediate transfer belt 8 moves toward the secondary transfer nip. Then, the color toner image carried on the intermediate transfer belt 8 is transferred onto the transfer paper P at the secondary transfer nip (secondary transfer step).

After passing through the secondary transfer nip, the surface of the intermediate transfer belt 8 reaches a portion facing the intermediate transfer belt cleaning device. At this facing portion, the transfer residual toner adhering to the intermediate transfer belt 8 is collected by the intermediate transfer belt cleaning device, and a series of transfer processes on the intermediate transfer belt 8 are completed.

The untransferred toner scraped off from the surface of the photoreceptor 1 by the cleaning blade 2a passes through the collected toner conveying path and is accommodated in the waste toner container. In addition, the untransferred toner scraped off from the surface of the intermediate transfer belt 8 by the intermediate transfer belt cleaning device and the toner of the pattern image for process control are also accommodated in the waste toner container through the collected toner conveying path.

The transfer paper P onto which the color toner image has been transferred by the secondary transfer nip is guided to the fixing device 20 . In the fixing device 20, the color image is fixed on the transfer paper P by heat and pressure at the fixing nip formed by the fixing roller and the pressure roller. After passing through the fixing device 20, the transfer paper P is discharged as an output image from the printer section 100 by the paper discharge roller pair 25 and stacked on the paper discharge tray 30 to complete a series of image forming processes.

FIG. 1 is an explanatory diagram of a developing device 5 to which the present invention can be applied. FIG. 1(a) is a sectional view thereof, and FIG. 1(b) is a partially enlarged view thereof. The developing device 5 includes a developing roller 50 as a developer carrier, and a casing 58 as a developing case having an opening for exposing the surface of the developer carrier. The area where the developing roller 50 and the photoreceptor 1 face each other through the opening is the developing area. The casing 58 comprises a lower developing case 58a, an upper developing case 58b, a developing roller cover 58c and a filter cover 58d. A flexible sheet 70 is provided as a flexible sheet member that comes into contact with the developer carried by the developer carrying member and entering the developing case through the opening.

The developing device 5 includes a supply screw 53 and a recovery screw 54, which are developer conveying members. Further, a doctor blade 52 is provided as a developer regulating member for regulating the amount of developer directed toward the development area. Furthermore, a depressurization filter 60 that constitutes a depressurization mechanism is provided. Between the doctor portion where the doctor blade 52 faces the developing roller 50 and the developing area, a developing area inlet seal 57 for preventing toner scattering may be arranged. The hatched portion indicated by reference numeral 58b' in FIG. 1 is an end seal member for sealing between the peripheral surface of both ends of the developing roller 50 and the surface portion of the developing roller cover 58c facing the peripheral surface. is. The supply screw 53 and the recovery screw 54 are screw members having helical blades on their rotating shafts, and by rotating, convey the developer in opposite directions in axial directions parallel to their rotating shafts. As the developer, a two-component developer consisting of toner and carrier (including the case where an additive or the like is added) is used.

The supply screw 53 and the recovery screw 54 convey the developer in the longitudinal direction (the axial direction of the developing roller 50) to form a circulation path. Toner is replenished to a part of this circulation path, for example, one end of the recovery screw 54 through a toner replenishment port. To replenish the toner, there are a toner container containing the replenished toner, a toner hopper for replenishing the toner from the toner container, and replenishing the toner from the toner hopper to the circulation path based on the output of the toner concentration cent provided in the developing device 5. It is also equipped with a toner replenishing screw and the like.

A supply conveying path 53a in which the supply screw 53 is arranged and a recovery conveying path 54a in which the recovery screw 54 is arranged in the space in the casing of the developing device 5 are spatially partitioned by a partition plate. The replenished toner is conveyed while being agitated with the developer by the collection screw 54 . The developer sufficiently mixed with the replenishment toner is transferred to the supply screw 53 through a transfer portion formed at one end of the circulation path, and drawn up to the developing roller 50 by magnetic force from the supply transport path 53a.

The developing roller 50 includes a magnet roller 55 made of a plurality of magnets fixed inside, and a developing sleeve 51 rotating around the magnet roller 55 . The developing sleeve 51 is a cylindrical member containing a magnet roller 55 and made of a rotatable non-magnetic material. The magnet roller 55 of this embodiment has a plurality of magnetic poles, including a first magnetic pole P1 (N pole), a second magnetic pole P2 (S pole), a third magnetic pole P3 (N pole), a fourth magnetic pole P4 (N pole), And five magnetic poles of a fifth magnetic pole P5 (S pole) are provided. P1 to P5 in FIG. 1(a) show the distribution of the normal direction magnetic flux density (absolute value) on the surface of the developing sleeve 51 of the magnetic field formed by each magnetic pole. Hereinafter, each magnetic pole is referred to as a P1 pole to a P5 pole.

A specific example of the developing device 5 of this embodiment is as follows. As a two-component developer, a toner containing polyester resin as a main component (average particle size: 5.2 [μM]) and a carrier that is magnetic fine particles (average particle size: 35 [μM]) were used, and the toner concentration was 7 [WT]. 380 [G] of a two-component developer that has been uniformly mixed so as to be 380 [G]. By rotating the supply screw 53 and the recovery screw 54 arranged in parallel at 600 [RPM], the developer is transported and the new toner supplied from the toner supply port is agitated at the same time. are uniformly mixed and electrified.

The uniformly mixed developer is conveyed in the longitudinal direction by a supply screw 53 provided close to and parallel to the developing sleeve 51, and is moved by the magnetic force of the fifth magnetic pole P5 of the magnet roller 55 contained in the developing sleeve 51. delivered to the outer peripheral surface of 51; The developer transferred to the surface of the developing sleeve 51 reaches the developing area as the developing sleeve 51 rotates counterclockwise as indicated by an arrow B in FIG. 1(a). A developing electric field is formed between the developing sleeve 51 and the photoreceptor 1 in the developing region by applying a voltage from a high-voltage power supply to the developing sleeve 51 . This development electric field supplies the toner in the developer on the surface of the developing sleeve 51 to the latent image on the surface of the photoreceptor 1, and the latent image on the photoreceptor 1 is developed.

The developer on the surface of the developing sleeve 51 after passing through the developing region passes between the flexible sheet 70 and the developing sleeve 51 as the developing sleeve 51 rotates. At this time, the air caught in the developer generates an airflow in the direction indicated by the white arrow F in FIG. The sucked airflow passes through the filter 60 and is discharged outside the developing device.

The thickness of the flexible sheet 70 is preferably 0.05 mm or more and 0.3 mm, and in this embodiment, a urethane sheet with a thickness of 0.1 mm is used. If the thickness is less than 0.05 mm, the elasticity of the flexible sheet 70 is weak and it will not follow the developer on the developing sleeve. As a result, there is a portion where contact between the developer and the flexible sheet 70 cannot be ensured, and the effect of suppressing toner scattering may not be obtained. On the other hand, if the thickness exceeds 0.3 mm, the flexibility of the flexible sheet 70 is too strong to crush the developer on the developing sleeve. As a result, the developer accumulates on the developing sleeve like a dam starting from there, causing problems such as developer overflow (excessive developer accumulated on the developing sleeve falls out of the developing machine). There is a risk that it will be lost.
By setting the thickness of the flexible sheet 70 to 0.05 mm or more and 0.3 mm or less, the flexible sheet 70 has appropriate elasticity, can satisfactorily suppress toner scattering, and prevents image agent overflow (excessive developer accumulated on the developing sleeve). such as falling out of the developing machine), which is preferable.

The flexible sheet 70, which is a feature of this embodiment, will be described in detail below. FIG. 4(a) is an explanatory diagram of a method of attaching the flexible sheet 70. FIG. FIG. 4(b) is an explanatory diagram of a conventional configuration. Conventionally, the gap CG between the developing roller 50 and the developing case in the direction LP2 of the second magnetic pole P2 is set to a size that causes an airflow to be sucked in by the passage of the developer ear, thereby preventing toner scattering. rice field. When the amount of developer on the developing roller 50 (the amount of developer pumped up) decreases, the gap between the developing roller 50 and the case increases relative to the amount of developer. likely to occur. If the gap CG between the developing roller cover 58c and the developing roller 50 is set to be narrow, the developing roller cover 58c contacts the developer on the developing roller 50 to generate an intake airflow. When the amount of developer) is large, developer retention occurs in the CG portion, so the width could not be narrowed beyond a certain level. That is, the agent retention margin was small.

On the other hand, in the present embodiment, the flexible sheet 70 has an opening-side end 70a, which is the end on the opening side, and a downstream end, which is the end opposite to the opening-side end 70a in the developer moving direction. The side end 70b is supported (contacted) by a developing roller cover 58c as a developing case, and the non-contact portion between the two end portions in the developer moving direction, which is not in contact with the developing roller cover 58c, is the developer on the developing roller 50. come into contact with Specifically, the opening-side end 70a is fixed to the developing roller cover 58c by adhesion or the like, and the downstream-side end 70b is a free end that contacts the inner surface of the developing roller cover 58c. This is the so-called back contact. The portion of the flexible sheet 70 that is in contact with the backing is called a backing portion 70c. The inner surface portion of the developing roller cover 58c with which the backing portion 70c abuts corresponds to the contact portion. The portion where the developing roller cover 58c is fixed corresponds to the fixed portion. The flexible sheet 70 bends to form a non-contact portion that does not contact the developing roller cover 58c at a portion between both ends. When the flexible sheet 70 is bent and the non-contact portion between both ends is in a state where no developer adheres to the developing roller, the flexible sheet 70 is in contact with the developing roller. Depending on the amount of developer on the developing roller 50 , the non-contact portion of the flexible sheet 70 bends and separates from the developing roller 50 to come into contact with the developer on the developing roller 50 . The free end is not fixed by adhesion or the like, and means that at least the contact position can change in the rotating direction of the developing roller 50 .

A dashed line 71 in FIG. 4A shows the state of the flexible sheet 70 when the developing roller 50 is removed. The opening-side end portion 70a of the flexible sheet 70 is attached and fixed to the attachment portion 58e of 58e by adhesion using double-sided tape or the like. The portion of the flexible sheet 70 on the downstream end 70b side extends along an imaginary straight line 71 linearly extending the sticking portion 58e due to its stiffness, and extends into the space occupied by the developing roller 50. take a stance. In other words, the portion of the flexible sheet 70 on the downstream end 70 b side bites into the developing roller 50 . The attachment portion 58e is formed so as to take such a posture. A solid line indicates the state of the flexible sheet 70 when the developing roller 50 is assembled. A portion between the opening-side end 70a and the downstream end 70b of the flexible sheet 70 contacts the 50 and bends, and the downstream end 70b contacts the inner surface of the developing roller cover 58c. That is, when the developer is not adhered to the developing roller 50, the flexible sheet 70 is abutted against the developing roller 50, and the portion near the downstream end 70b is abutted against the inner wall surface of the developing roller cover 58c. be done.

5(a) and 5(b) show the case where the downstream edge 70b of the flexible sheet 70 is not backed against the developer roller cover 58c and the case where it is backed. In the case of FIG. 5A with no backing, the contact width between the developer and the flexible sheet 70 is narrow, and the strength of the contact is weak. On the other hand, in the case of backing as shown in FIG. 5(b), the width of the flexible sheet contacting the developer is widened and the contact is stronger. As a result, a very stable intake airflow can be ensured.

By using the flexible sheet 70, the sheet bends according to the amount of developer (the amount of developer pumped up) on the developing roller 50. Therefore, even if the amount of developer pumped up fluctuates due to component tolerances or deterioration of the developer over time, stable operation can be achieved. It is possible to maintain the intake airflow.

One end of the flexible sheet 70 is attached and fixed to the casing, and the other end is brought into contact with the inner wall of the developing casing. can be stabilized. As a result, the intake airflow can be stably maintained. The support at the two points may be fixed at both points or may be abutted at both points, but as will be described later, it is most preferable to be fixed at the upstream side in the moving direction of the developer and abutted at the opposite side.

The flexible sheet 70 bends and contacts the developer at a portion between the ends thereof. The developer can be strongly applied, and the blowing air current from the casing 58 of the developing device 5 can be suppressed. In addition, even if the amount of pumped-up fluctuates, the sheet bends according to (follows) the amount of pumped-up, ensuring a stable suction airflow and achieving both a room for agent retention and suppression of blow-out airflow. can.

In particular, fixing one end and abutting the other has the following advantages. That is, one side of the sheet member is in contact with the inner wall of the developing case without being adhered thereto, so that the deflection of the sheet easily follows the fluctuation of the drawing. If this part is adhered, the amount of deflection of the sheet will not easily change even if the amount of pumping changes, and the room for agent retention will become small. In addition, if the position is shifted during attachment, waviness of the sheet is likely to occur, which may reduce productivity. In addition, since one end of the flexible sheet 70 is adhered to the casing and the other end is backed to the casing, the width of contact between the developer and the flexible sheet 70 is widened and the contact is strong. , a stable airflow can be ensured. Therefore, it is preferable to leave the backing portion free to move relative to the upper case without bonding.

FIG. 5(c) is a cross-sectional view taken along line XX of FIG. 5(b) and viewed in the direction of arrow c. The gaps G1 and G2 between the developing roller cover 58c of the backing portion 70c of the flexible sheet 70 and the developing roller 50 may be uniform in the longitudinal direction, but the gap G2 is narrowed at the ends and the gap G1 is widened at the central portion. is preferred. In this embodiment, a gap difference of 0.2 mm is provided with 1.2 mm at the center (G1) in the longitudinal direction and 1.0 mm at the ends (G2). Since the end portions of the urethane sheet are weak and the developer D and the flexible sheet 70 are less likely to hit each other, narrowing the gap at the end portions ensures a uniform air flow in the longitudinal direction.

Further, as shown in FIG. 5B, the backing portion 70c of the flexible sheet 70 is positioned between the P2 pole (LP2) and the P3 pole (LP3) where the bristles of the developer D lie. is preferred. This is for the following reasons. The narrower the gap between the developing roller cover 58c and the developing roller 50 in the backing portion 70c, the stronger the contact between the flexible sheet 70 and the developer D at the P2 pole, thereby creating a stable airflow. However, if the gap is too narrow, the developer D cannot pass through the gap and stays there, causing the developer D to blow out of the machine. Such retention is likely to occur when the gap is narrowed at the part where the ears stand. Therefore, by narrowing the gap between the P2 and P3 poles where the bristles lie down and placing the backing portion 70c in the portion where the bristles lie down, the contact between the flexible sheet 70 and the developer at the P2 pole is strong. Thus, a stable suction airflow is ensured while preventing the developer D from stagnation.

Further, the flexible sheet 70 hits the bristle portion of the developer D (the portion where the magnetic force in the normal direction is strong: the portion in the LP2 direction, which is the P2 pole direction in FIG. 5(b) and FIG. 1(a)). It is preferable that Since the suction air current is generated not at the part where the ears lie down but at the standing part of the ears, a strong suction air current can be generated by pressing the flexible sheet 70 against this part.

FIG. 5D shows an example in which the flexible sheet 70 does not bite into the developing roller 50, rather than the portion of the flexible sheet 70 on the downstream end 70b side bites into the developing roller 50. FIG. If the flexible sheet 70 does not bite into the developing roller 50, the portion between the two ends does not come into contact with the developing roller when no developer adheres to the developing roller. As a result, when the developer adheres to the developing roller, the contact between the two end portions of the developing roller with respect to the developer becomes relatively weak, and the suction air flow becomes weak. However, in a state in which the developing roller 50 is not coated with the developer, a portion between both ends of the flexible sheet 70 is brought into contact with the developing roller so that the flexible sheet 70 is pushed up. A stable and strong suction airflow can be obtained.

In this embodiment, the depressurization mechanism (filter 60) is provided, but even without the filter 60, the effect of reducing the scattering amount by stabilizing the airflow can be obtained. The flexible sheet 70 of this embodiment is particularly effective in combination with the filter 60. FIG. That is, the air sucked into the developing device by the strong suction air current obtained by the flexible sheet 70 is discharged out of the machine through the filter 60 . The air before passing through the filter 60 contains toner, but since the filter 60 adsorbs the toner, only the air that does not contain toner is discharged outside the machine.

Since the toner adsorbed to the filter 60 reduces the pressure relief performance of the filter 60, the internal pressure of the developing device increases over time as the filter 60 is clogged with toner. Even if a strong suction airflow is generated, if the internal pressure inside the developing device rises, the airflow may not be fully sucked and the airflow may flow backward.

On the other hand, by pressing the flexible sheet 70 strongly against the bristles of the developer, the air current is stronger and less likely to flow back, but the amount of air involved together with the developer is also reduced. Therefore, the amount of air passing through the filter 60 is also reduced, and the amount of toner clogging the filter 60 is reduced. Therefore, the effect of greatly extending the life of the filter 60 as compared with the conventional casing can be obtained, and in particular, the combination with the depressurization filter 60 can greatly extend the life.

FIG. 6 is a graph of experimental results confirming the effect of reducing the amount of scattering and the effect of prolonging the life of the filter 60 . This is the result of an experiment in which developer that easily scatters was put into "RICOH MPC6003" (registered trademark) manufactured by Ricoh Co., Ltd., continuous printing was performed, and the amount of toner that scatters above the developing unit was measured. The horizontal axis is the number of running sheets (k sheets), and the vertical axis is the scattering amount (mg/cm ² ). The dashed line indicates the results of the conventional example without the flexible sheet 70, and the solid line indicates the results of the example provided with the flexible sheet 70 according to the specific example of FIG. 6(b). It can be seen that the flexible sheet 70 greatly reduces the amount of scattering to the outside of the developing device.

In order to eliminate clogging between the developing sleeve 51 and the doctor blade 52, there is a developing device that reversely rotates the developing sleeve 51 at a predetermined timing. During this reverse operation, the developer on the developing roller moves toward the portion of the downstream end 70b of the flexible sheet 70 that is in contact with the inner surface of the developing roller cover 58c. Since the downstream end portion 70b of the flexible sheet 70 is a free end that is not fixed to the developing roller cover 58c, the developing roller cover 58c and the flexible sheet 70 are separated from the downstream end portion 70b and the developing roller cover 58c. In some cases, the developer enters the space between the adhesive sheet 70 and the adhesive sheet 70 . In particular, when the urethane flexible sheet 70 weakens due to use over time, the contact pressure of the downstream end 70b against the developing roller cover 58c decreases, and the downstream end 70b and the developing roller cover 58c do not contact each other during reverse rotation. The developer is likely to enter from between 58c.

When the developer enters the space between the developing roller cover 58 c and the flexible sheet 70 , the developer that has entered is attracted toward the developing roller 50 by the magnetic force of the magnet roller 55 . As a result, the bending of the flexible sheet 70 according to the amount of developer pumped up is hindered, and the developer cannot pass between the flexible sheet 70 and the developing roller 50 . As a result, developer pooling occurs on the upstream side of the flexible sheet 70, and the developer may not be conveyed into the developing case.

Fixing the downstream end 70b of the flexible sheet 70 to the developing roller cover 58c in order to prevent developer from entering between the downstream end 70b and the developing roller cover 58c provides the advantages described above. will not be In other words, the advantage is that the flexible sheet 70 bends according to the amount of developer pumped up, and a stable airflow can be ensured.

In order to prevent the developer from entering the space between the developing roller cover 58c and the flexible sheet 70, the flexible sheet 70 is preferably configured as shown in FIG.
FIG. 7 is an enlarged view of a main portion of a developing device showing a flexible sheet 70 of a modified example.
As shown in FIG. 7, the flexible sheet 70 of the modified example has a backing portion 70c as a case contact portion that contacts the inner surface of the developing roller cover 58c between the opening-side end portion 70a and the downstream-side end portion 70b. was formed, and the downstream end portion 70b was fixed to the inner peripheral surface of the developing roller cover 58c with an adhesive 70d. The fixing of the downstream end portion 70b to the inner peripheral surface of the developing roller cover 58c is not limited to the adhesive, and a known method such as double-sided tape can be used.

In this modification, too, the developing roller cover 58c is backed with the flexible sheet 70 at substantially the same position as in the embodiment, and the developer on the developing roller is exposed to the developer near the opening of the casing 58 as in the embodiment. It's making me hungry.

By fixing the downstream end 70b to the developing roller cover 58c, it is possible to prevent the developer on the developing roller from entering through the gap between the downstream end 70b and the developing roller cover 58c during reverse rotation.

Further, the flexible sheet 70 of the modified example forms a backing portion 70c as a case contact portion that contacts the inner surface of the developing roller cover 58c between the opening side end portion 70a and the downstream side end portion 70b. there is As a result, the flexible sheet is supported at two points upstream and downstream in the direction of developer movement between the opening-side end 70a and the backing portion 70c. The gap can be flexed toward the developing roller so that the developer on the developing roller can be brought into contact therewith. Thus, the backing portion 70c of the modified flexible sheet 70 is not fixed to the developing roller cover 58c. Therefore, as in the embodiment, it is possible to favorably change the deflection amount of the portion between the opening-side end portion 70a and the backing portion 70c that abuts on the developer. can follow well. In addition, the width of contact between the developer and the flexible sheet 70 can be widened and the contact can be made strong, thereby ensuring a stable air flow.

Further, as shown in FIG. 7, the downstream end portion 70b of the flexible sheet 70 is fixed to the developing roller cover 58c in a posture inclined with respect to the surface of the developing roller cover 58c on which the flexible sheet 70 is to be backed. ing. As a result, the flexible sheet can be extended from the downstream end portion 70b toward the backing surface of the developing roller cover 58c, and the flexible sheet can be satisfactorily backed against the backing surface. be able to. Thereby, the backing portion 70c can be formed between the downstream end portion 70b and the opening side end portion 70a of the flexible sheet.

In FIG. 7, the downstream end 70b of the flexible sheet 70 is fixed to the developing roller cover 58c, but as shown in FIG. A holding portion 76 may be provided to hold the ink, and the downstream end may be inserted into the holding portion 76 for holding.

In the configuration shown in FIG. 8, the downstream end 70b of the flexible sheet 70 is covered with the holding portion 76. As shown in FIG. As a result, the holding portion 76 can block the movement of the developer to the contact portion of the downstream end portion 70b of the flexible sheet 70 with the developing roller cover 58c. Therefore, even if the downstream end 70b of the flexible sheet 70 is not fixed to the inner peripheral surface of the developing roller cover 58c, the developer enters between the downstream end 70b and the inner peripheral surface of the developing roller cover 58c. can be suppressed.

What has been described above is only an example, and each of the following aspects has a unique effect.
(Aspect 1)
A developing device comprising a developer carrying member such as a developing roller 50 and a developing case such as a casing 58 having an opening for exposing the surface of the developer carrying member. A flexible sheet member such as a flexible sheet 70 that contacts the developer that has passed through and entered the developing case is provided. , opening side end portion 70a) and the end portion opposite to the opening side in the developer moving direction (downstream side end portion 70b in this embodiment) are in contact with the developing case, and both end portions in the developer moving direction are in contact with each other. A non-contact portion that is not in contact with the developing case is formed at a portion between the developer case, and the non-contact portion is in contact with the developer carrier when there is no developer on the developer carrier, and the developer is placed on the developer carrier. is attached in a predetermined amount, it separates from the developer carrying member.
According to this, as described in the embodiment, it is possible to suppress the formation of a gap between the developer on the developer carrier and the sheet member, and it is possible to satisfactorily suppress the occurrence of toner scattering. .
In addition, when a predetermined amount of developer adheres to the developer carrier, the non-contact portion can be brought into strong contact with the developer, and a stable and strong suction air current can be obtained.

(Aspect 2)
In mode 1, the thickness of the sheet member such as the flexible sheet 70 is 0.05 mm or more and 0.30 mm or less.
According to this, as described in the embodiment, the sheet member such as the flexible sheet 70 has appropriate elasticity, so that the toner scattering can be satisfactorily suppressed, and the image agent overflows (excessive accumulation on the developing sleeve). It is possible to suppress problems such as the developer dropping out of the developing machine.

(Aspect 3)
In mode 1 or 2, the opening side end portion 70a of the sheet member such as the flexible sheet 70 is fixed to a developing case such as the casing 58, and both ends of the sheet member in the developer moving direction are fixed. A case contact portion such as a backing portion 70c that contacts the developing case is formed between the portions, and the sheet member is bent toward the developer carrier between the edge of the sheet member on the side of the opening and the case contact portion. A non-contact portion was formed, and the end portion of the sheet member opposite to the opening side, such as the downstream end portion 70b, was fixed to the developing case.
According to this, as described with reference to FIG. 7, the occurrence of toner scattering can be satisfactorily suppressed, and the end portion opposite to the opening side, such as the downstream end portion 70b of the sheet member, and the developing case can be separated from each other. It is possible to prevent the developer from entering from between.

(Aspect 4)
In mode 1 or 2, the opening side end portion 70a of the sheet member such as the flexible sheet 70 is fixed to a developing case such as the casing 58, and both ends of the sheet member in the developer moving direction are fixed. A case contact portion such as a backing portion 70c that contacts the developing case is formed between the portions, and the sheet member is bent toward the developer carrier between the edge of the sheet member on the side of the opening and the case contact portion. A non-contact portion is formed, and the end portion opposite to the opening side such as the downstream end portion 70b of the sheet member is inserted into and held by a holding portion 76 provided in the developing case.
According to this, as described with reference to FIG. 8, the occurrence of toner scattering can be satisfactorily suppressed, and the end portion opposite to the opening side, such as the downstream end portion 70b of the sheet member, and the developing case can be separated from each other. It is possible to prevent the developer from entering from between.

(Aspect 5)
In mode 3 or 4, the end opposite to the opening side, such as the downstream end 70b of the sheet member such as the flexible sheet 70, contacts the case such as the backing portion 70c of the developing case such as the casing 58. contacting the developing case in an inclined position with respect to the contact surface.
According to this, as described with reference to FIG. 7, the case contact portion such as the backing portion 70c can be brought into good contact with the developing case such as the casing 58. FIG.

(Aspect 6)
In mode 1 or 2, the opening side end portion 70a of the sheet member such as the flexible sheet 70 is fixed to the developing case such as the casing 58, and the downstream end portion 70b of the sheet member is fixed. The end opposite the opening is a free end that contacts the inner surface of the developer case.
According to this, as described in the embodiment, compared to the case where the end opposite to the opening, such as the downstream end 70b of the sheet member, is the fixed end, the developer carrying member such as the developing roller 50 is more likely to move. When the amount of adhered developer fluctuates, the deflection of the sheet can easily follow, and the developer retention margin can be increased.

(Aspect 7)
In mode 6, the fixed portion of the sheet member such as the flexible sheet 70 in the developing case such as the casing 58 is the space occupied by the developer carrier such as the developing roller 50 when the developer carrier is removed. The free end side of the member is formed so as to extend, and the non-contact portion abuts on the developer carrying member and bends, and the free end abuts on the contact portion on the inner surface of the developing case.
According to this, as described in the embodiment, the non-contact portion of the sheet member such as the flexible sheet 70 is abutted against the developer carrier such as the developing roller 50, and the free end such as the downstream end 70b is Can be backed to the developer case. As a result, the non-contact portion of the sheet member can be brought into strong contact with the developer on the developer carrier, and the blowing airflow from the developing case can be suppressed. In addition, even if the amount of pumped up fluctuates, the non-contact part bends according to (follows) the amount of pumped up. can be compatible.

(Aspect 8)
In mode 1, 2 or 6, the sheet member is bent to form a non-contact portion between the two ends.
According to this, as described in the embodiment, the non-contact portion can be bent so as to follow (follow) the amount of pumping up, a stable suction airflow can be secured, and the agent retention margin and blowout It is possible to achieve both airflow suppression.

(Aspect 9)
In any one of modes 1 to 8, a magnet for forming an ear of developer is provided at a predetermined position on the developer carrier such as the developing roller 50, and a predetermined amount of developer adheres to the developer carrier at the non-contact portion. It touches the ear (the part of the ear) when it is in the state of being pulled.
According to this, as described in the embodiment, a strong suction airflow can be generated.

(Mode 10)
In any one of modes 1 to 9, the development case such as casing 58 is provided with a pressure release mechanism (filter 60).
According to this, as described in the embodiment, the air sucked into the developing device can be discharged to the outside of the developing device by the strong sucking air current obtained by the sheet member such as the flexible sheet 70. internal pressure rise can be suppressed.

(Aspect 11)
An image forming apparatus includes the developing device according to any one of modes 1 to 10.
According to this, it is possible to suppress contamination of the device and disturbance of the image due to toner scattering from the developing device.

1: photoreceptor 1C: cyan photoreceptor 1K: black photoreceptor 1M: magenta photoreceptor 1Y: yellow photoreceptor 2: photoreceptor cleaning device 2a: cleaning blade 3: document transport section 4: document reading section 4a: Charging roller 5 : Developing device 6 : Image forming unit 7 : Paper feed unit 8 : Intermediate transfer belt 9 : Primary transfer bias roller 10 : Intermediate transfer unit 11 : Toner container 19 : Secondary transfer bias roller 20 : Fixing device 25 : Ejector Paper roller pair 26 : Paper feed cassette 27 : Paper feed roller 28 : Registration roller pair 30 : Paper discharge tray 35 : Average particle size 40 : Charging device 41 : Lubricant coating device 50 : Developing roller 51 : Developing sleeve 52 : Doctor blade 53 : Supply screw 53a : Supply conveying path 54 : Recovery screw 54a : Recovery conveying path 55 : Magnet roller 57 : Developing area inlet seal 58 : Casing 58a : Lower developing case 58b : Upper developing case 58b' : End sealing member 58c : Developing roller cover 58d : Filter cover 58e : Attaching portion 60 : Depressurizing filter 70 : Flexible sheet 70a : Opening side end 70b : Downstream side end 70c : Backing portion 76 : Holding portion 100 : Printer portion 500 : Copying Machine A: Arrow CG: Gap D: Developer F: Arrow G1: Gap G2: Gap G3: Gap L: Laser light LP2: Direction P: Transfer paper P1: First magnetic pole P2: Second magnetic pole P3: Third magnetic pole P4 : Fourth magnetic pole P5 : Fifth magnetic pole

JP 2016-035545 A

Claims (11)

a developer carrier;
a developing case having an opening for exposing the surface of the developer carrier;
a flexible sheet member that comes into contact with the developer that is carried by the developer carrying member and enters the developing case through the opening;
The sheet member has an end on the side of the opening in the direction of developer movement and an end on the side opposite to the side of the opening in the direction of movement of the developer, and both ends in the direction of movement of the developer are in contact with the developing case. forming a non-contact portion that is not in contact with the developing case at a location between
The non-contact portion abuts against the developer carrier when there is no developer on the developer carrier, and separates from the developer carrier when a predetermined amount of developer adheres to the developer carrier. A developing device characterized by: The developing device according to claim 1,
The developing device, wherein the sheet member has a thickness of 0.05 mm or more and 0.30 mm or less. 3. The developing device according to claim 1, wherein
an end portion of the sheet member on the opening side is fixed to the developing case;
forming a case contact portion contacting a developing case between both ends of the sheet member in the developer moving direction;
forming the non-contact portion by bending the sheet member toward the developer carrier between an end portion of the sheet member on the side of the opening and the case contact portion;
A developing device, wherein an end portion of the sheet member opposite to the opening side is fixed to the developing case. 3. The developing device according to claim 1, wherein
an end portion of the sheet member on the opening side is fixed to the developing case;
forming a case contact portion contacting a developing case between both ends of the sheet member in the developer moving direction;
forming the non-contact portion by bending the sheet member between an end of the sheet member on the side of the opening and the case contact portion;
forming the non-contact portion by bending the sheet member toward the developer carrier between an end portion of the sheet member on the side of the opening and the case contact portion;
A developing device, wherein an end portion of the sheet member opposite to the opening side is inserted into and held by a holding portion provided in the developing case. The developing device according to claim 3 or 4,
An end portion of the sheet member opposite to the opening is in contact with the developing case in an inclined posture with respect to a surface of the developing case with which the case contact portion contacts. Device. 3. The developing device according to claim 1, wherein
An end of the sheet member on the side of the opening is fixed to the developing case, and an end of the sheet member on the opposite side of the opening is a free end that contacts the inner surface of the developing case. developing device. In the developing device according to claim 6,
The fixing portion of the sheet member in the developing case is formed so that the free end side of the sheet member extends into the space occupied by the developer carrier when the developer carrier is removed,
The developing device, wherein the non-contact portion abuts against the developer carrying member and bends, and the free end abuts against the contact portion of the inner surface of the developing case. In the developing device according to claim 1, 2 or 6,
A developing device, wherein the sheet member is bent to form the non-contact portion between the two end portions. The developing device according to any one of claims 1 to 8,
a magnet for forming an ear of developer at a predetermined location on the developer carrier;
The developing device, wherein the non-contact portion is in contact with the brush when a predetermined amount of developer adheres to the developer carrier. The developing device according to any one of claims 1 to 9,
The developing device, wherein the developing case has a depressurization mechanism. An image forming apparatus comprising the developing device according to any one of claims 1 to 10.

Images