Image forming apparatus

Abstract

To provide an image forming apparatus that can reduce unintended scattering of toner from a developing device.SOLUTION: A developing device comprises: a developer carrier 133 that carries developer and develops toner on an image carrier; a film thickness regulation member 135 that is arranged opposite to the developer carrier 133 and regulates the film thickness of the developer carried on the developer carrier 133; and a housing 130 that has therein the developer carrier 133 and the film thickness regulation member 135. The distance DG between an opposite surface 135c of the film thickness regulation member 135 to the developer carrier 133 and a developer carrying surface 133a of the developer carrier 133, is made different from an end on one side 135a to an end on the other side 135b in a longitudinal direction of the film thickness regulation member 135.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus including a developing device that develops toner onto an image carrier. [Background technology]

[0002] In an image forming apparatus, a developing device includes a pair of stirring members that stir the toner stored in a developing tank inside a housing with a carrier, which is a magnetic material, and a developing roller that supplies the toner stirred by the stirring members to a photosensitive drum.

[0003] The developer, which is made up of toner and carrier, is stirred by a pair of stirring members as it is circulated and transported back and forth from one side to the other and then back again, taking about 10 seconds to complete one revolution (5 seconds each way).

[0004] This stirring generates friction between the toner and the carrier, causing the toner to become negatively charged and the carrier to become positively charged.

[0005] The toner and carrier thus charged are leveled by the developer regulating member and carried in a uniform film thickness on the carrying surface of the developing roller.

[0006] Of the toner and carrier carried on the carrying surface of the developing roller, the toner is transferred to the electrostatic latent image on the photosensitive drum.

[0007] The remaining amount of toner is detected by a magnetic permeability sensor, and when it is detected that the remaining amount of toner is reduced, toner is replenished via a replenishing section.

[0008] Incidentally, inside the housing, an air current is generated when the stirring member stirs the developer. This air current flows out of the housing by weaving through the gap between the film surface of the developer carried on the surface of the developing roller and the inner surface of the housing.

[0009] Normally, the toner is sufficiently charged while being transported back and forth by the pair of stirring members, and is therefore firmly held by the carrier, so there is no risk of the toner being blown out of the developing device by the air current that flows out of the housing through the gap between the developer film surface carried on the surface of the developing roller and the inner surface of the housing.

[0010] However, the toner immediately after being replenished to the developing device does not have a sufficient charge and is not firmly held by the carrier, so the toner is carried by the air current and scattered outside the developing device, which may cause damage to the inside of the housing of the image forming device, and measures are being called for.

[0011] Patent document 1 discloses an image forming device in which a developer regulating member is attached to a developing container so that the tip side of the developer regulating member faces the surface of the sleeve along the longitudinal direction, and the longitudinal central portion of the developer regulating member is curved so as to protrude upstream in the direction of rotation of the sleeve compared to both longitudinal ends.

[0012] However, the image forming apparatus disclosed in Patent Document 1 merely reduces the variation in the amount of developer transported in the longitudinal direction of the image forming apparatus by curving the developer regulating member. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] JP 2014-178356 A Summary of the Invention [Problem to be solved by the invention]

[0014] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide an image forming apparatus capable of reducing unintended scattering of toner from a developing device. [Means for solving the problem]

[0015] In order to achieve the above-mentioned object, an image forming apparatus according to the present disclosure is an image forming apparatus including a developing device that develops toner on an image carrier, the developing device including a developer tank that stores a developer composed of the toner and a carrier, a replenishing section that replenishing the toner to the developer tank, a first conveying member that is disposed in the developer tank and receives the toner replenishing from the replenishing section, a second conveying member that cooperates with the first conveying member to reciprocate and circulate the developer, and a developing device that carries the developer received from the second conveying member and conveys the toner to the image carrier. The device comprises a developer carrier that develops an image, a film thickness regulating member that is arranged opposite the developer carrier and that regulates the film thickness of the developer carried on the developer carrier from the second transport member, and a housing that incorporates the developer tank, the first transport member, the second transport member, the developer carrier, and the film thickness regulating member, and is characterized in that the distance between the surface of the film thickness regulating member that faces the developer carrier and the developer carrying surface of the developer carrier is varied from one end to the other end in the longitudinal direction.

[0016] According to the above-mentioned configuration, the distance between the surface of the film thickness regulating member facing the developer carrier and the developer carrying surface of the developer carrier varies from one end to the other end in the longitudinal direction of the film thickness regulating member, so that the film thickness of the developer carried on the developer carrier is not uniform from the one end to the other end. As a result, although the distance of the gap between the carrying surface of the developer carrier and the inner surface of the housing is uniform, the distance of the gap between the film surface of the developer carried on the carrying surface of the developer carrier and the inner surface of the housing is not uniform.

[0017] Since the airflow preferentially passes through areas with small pressure loss, the airflow path can be controlled by varying the pressure loss in the gap between the developer film surface carried on the carrying surface of the developer carrier and the inner surface of the housing. In other words, it is possible to set a path that can suppress toner scattering, thereby reducing unintended scattering of toner from the developing device.

[0018] In order to vary the distance between the opposing surface and the carrying surface from one end to the other end in the longitudinal direction, the film thickness regulating member may be fixed at an incline such that the surface of the film thickness regulating member facing the developer carrying body has a gradient, or the surface of the film thickness regulating member facing the developer carrying body itself may have a gradient, provided that the degree of gradient is such that a difference in toner density is not noticeable in the image printed on the paper.

[0019] In the image forming apparatus according to the present disclosure, the first transport member is configured to transport the developer from the one side to the other side, the second transport member is configured to transport the developer from the other side to the one side, the supply section is provided at a position where the toner can be supplied to the one side of the first transport member, and the film thickness regulating member may be characterized in that the distance between the opposing surface and the carrying surface increases from the end of the one side to the end of the other side.

[0020] The developer, which is composed of toner and carrier, is stirred by the first and second transport members and circulated back and forth in a cycle of about 10 seconds per revolution (5 seconds each way). As a result, friction occurs between the toner and carrier, causing the toner to become negatively charged and the carrier to become positively charged.

[0021] The remaining amount of toner is detected by a magnetic permeability sensor, and when it is detected that the remaining amount of toner is low, toner is supplied from a toner bottle.

[0022] The toner supplied to one side of the first transport member via the supply section is transported from one side to the other side by the first transport member, and then carried on the developer carrier while being transported from the other side to the one side by the second transport member.

[0023] Therefore, the toner carried on the developer carrier from one side, which corresponds to the downstream side in the transport direction, has a larger charge amount than the toner carried on the developer carrier from the other side, which corresponds to the upstream side in the transport direction.

[0024] The less charged toner is, the more likely it is to be lifted off the carrier by the air current. On the other hand, the more charged toner is, the less likely it is to be lifted off the carrier by the air current. In other words, the toner is more likely to scatter on the other upstream side because the charge is insufficient, whereas the toner is less likely to scatter on the one downstream side because the charge is sufficient.

[0025] Since the distance between the opposing surface and the carrying surface of the film thickness regulating member increases from the one end to the other end, the film thickness of the developer carried on the developer carrier can be made thicker from the one end to the other end.

[0026] As a result, the gap between the developer film surface carried on the developer carrier and the inner surface of the housing narrows from one end to the other end, resulting in increased pressure loss and making it difficult for air to pass through.

[0027] Conversely, the gap between the developer film surface carried on the carrying surface of the developer carrier and the inner surface of the housing becomes wider from the other end to the one end, so that the pressure loss is smaller and air can easily pass through.

[0028] In this way, toner has a high charge, and by deliberately making it easier for air to pass through areas where there is little risk of it being lifted off the carrier by air currents, it is possible to reduce the risk of toner scattering while still allowing the internal pressure of the developing device to escape.

[0029] In other words, on the upstream side where toner is more likely to scatter, by increasing the distance between the opposing surface and the carrying surface, the thickness of the developer film carried on the developer carrier is increased, and the gap between the film surface of the developer carried on the carrying surface of the developer carrier and the inner surface of the housing is narrowed, thereby reducing the airflow and suppressing toner scattering.

[0030] On the other hand, on the downstream side where toner is less likely to scatter, the distance between the opposing surface and the carrying surface is reduced to reduce the film thickness of the developer carried on the developer carrier, and the gap between the film surface of the developer carried on the carrying surface of the developer carrier and the inner surface of the housing is widened to increase the airflow, thereby suppressing the scattering of toner while also suppressing an increase in the internal pressure of the developing device.

[0031] In the image forming apparatus according to the present disclosure, the film thickness regulating member may be attached to the housing so that the distance between the opposing surface and the supporting surface increases from the end on one side to the end on the other side.

[0032] The film thickness regulating member is attached to the housing in a positioned and rotation-stopped state, for example, by a positioning boss and a rotation-stopping boss. When attaching the film thickness regulating member to the housing, the distance between the opposing surface and the supporting surface can be increased from one end to the other end by simply tilting the film thickness regulating member. Therefore, the above-mentioned effects can be achieved using the same film thickness regulating member as conventional films, without the need for any new processing on the film thickness regulating member.

[0033] In the image forming apparatus according to the present disclosure, the carrier may be an iron powder carrier.

[0034] Since airflow is less likely to pass through areas with large pressure loss, it is easy to control the airflow by making the pressure loss large in areas where you do not want much airflow to pass, and making the pressure loss small in areas where you want the airflow to pass.

[0035] The iron powder carrier is more likely to stand along the magnetic field lines when carried on the developer carrier than, for example, a ferrite carrier, etc. In other words, the iron powder carrier is more likely to close the gap between the carrying surface and the inner surface of the housing than a ferrite carrier, etc., and is therefore preferably used because it is easier to control the airflow as described above.

[0036] In the image forming apparatus 1 of the present disclosure, the film thickness regulating member may be characterized in that the distance between the opposing surface and the supporting surface at the other end is 3% to 12% greater, preferably 4% to 9% greater, than the distance between the opposing surface and the supporting surface at the one end.

[0037] In conventional image forming devices, the distance between the developer carrier's carrying surface and the inner surface of the housing is constant at about 2.50 mm, and the distance between the surface of the film thickness regulating member facing the developer carrier and the developer carrying surface of the developer carrier is uniform at 1.30 mm from one side to the other.

[0038] As a result of intensive research, it was found that the effect of suppressing toner scattering can be achieved by setting the distance between the surface of the film thickness regulating member at one end facing the developer carrier and the developer carrying surface of the developer carrier to 130 mm, while setting the distance between the surface of the film thickness regulating member at the other end facing the developer carrier and the developer carrying surface of the developer carrier to 3% more than 1.30 mm (1.34 mm) to 12% more than 1.30 mm (1.46 mm), and preferably setting it to 4% more than 1.30 mm (1.35 mm) to 9% more than 1.30 mm (1.42 mm). Effect of the Invention

[0039] The image forming apparatus of the present disclosure has an advantage in that it is possible to suppress unintended scattering of toner from the developing device. [Brief description of the drawings]

[0040] [Figure 1] FIG. 1 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus. [Diagram 2] FIG. 2 is an explanatory diagram illustrating the developing device shown in FIG. [Diagram 3] 3 is an explanatory diagram showing a main part of the developing device shown in FIG. 2 as viewed from above. [Figure 4] 4 is a schematic side view of a main part of the developing device shown in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] (Embodiment 1) Hereinafter, a first embodiment of the present disclosure will be described with reference to the accompanying drawings. Note that the same components in the respective embodiments described below are denoted by the same reference numerals, and redundant descriptions of those components will be omitted.

[0042] In the first embodiment, the image forming apparatus 1 is an electrophotographic monochrome image forming apparatus (printer) having a printing function. The image forming apparatus 1 is connected to an external device such as a personal computer (not shown) by wire or wirelessly, and forms a black toner image on a medium, here a predetermined printing paper 2, in accordance with print image data sent from the external device. The image forming apparatus is not limited to a monochrome type, and may be a color type.

[0043] As shown in FIG. 1, the image forming apparatus 1 includes a charger 10, an exposure device 11, a photosensitive drum 12, a developing device 13, a cleaner device 14, a transfer device 15, a fixing device 16, a charge removal device 17, a paper feeder 18, a conveying means 19, and a paper output tray 20 in the main body of the apparatus.

[0044] By irradiating the surface of the photoconductor drum 12, which has been charged to a uniform potential by a charger (not shown), with a laser beam from an exposure device (not shown), the resistance value of the exposed area drops, lowering the surface potential, and an electrostatic latent image corresponding to the print image data is formed. Toner is supplied from a developing device 13 to this electrostatic latent image, and a toner image is developed. The photoconductor drum 12 is the "image carrier" in the claims.

[0045] The toner image formed on the surface of the photoconductor drum 12 is transferred to the printing paper 2 passing between the photoconductor drum 12 and the transfer device 15, and is heated and pressed in the fixing device 16. In this manner, the toner image is printed on the printing paper 2.

[0046] Any toner image remaining on the surface of the photoconductor drum 12 is scraped off by the cleaner device 14. After the surface of the photoconductor drum 12 has been cleaned by the cleaner device 14, the electrostatic latent image remaining on the surface of the photoconductor drum 12 is removed by the charge remover 17. This returns the photoconductor drum 12 to an uncharged state.

[0047] The paper feed device 18 has a tray for loading the printing paper 2 to be used for image formation, and the printing paper 2 is transported within the main body of the image forming device 1 by a transport means 19 equipped with a transport path and transport rollers, and after the toner image is transferred, it is discharged onto a paper output tray 20.

[0048] In addition to the configuration described above, the image forming apparatus 1 includes a control unit (not shown) that controls each unit of the image forming apparatus 1.

[0049] The main parts according to the present disclosure will be described below. As shown in Fig. 2, the developing device 13 includes a developing tank 131, a pair of stirring members 132a and 132b, a developing roller 133, and the like inside a housing 130. The developing device 13 further includes a supply unit 134 that supplies the toner to the developing tank 131.

[0050] The developer tank 131 is a tank for storing a developer DP composed of non-magnetic toner and a magnetic carrier (iron powder carrier) that transports the toner. Although an iron powder carrier is preferably used as the carrier, other carriers such as a ferrite carrier may also be used.

[0051] The toner particle diameter is about 5 to 10 μm, and the carrier particle diameter is about 40 μm. The mixture ratio (weight ratio) of the toner and the carrier is, for example, about 1:7. Note that in Figures 2 and 4, a round object is drawn as the developer DP, which represents a large number of toner particles adhering to the surface of one carrier.

[0052] 2 and 3, stirring member 132a and stirring member 132b are screw conveyors provided in parallel to developing tank 131, and are rotated by a driving device (not shown) to stir and transport developer DP stored in developing tank 131. Stirring member 132a is the "first transport member" in the claims, and stirring member 132b is the "second transport member" in the claims.

[0053] In the first embodiment, the stirring member 132a transports the developer DP from the front side of the image forming apparatus 1 (in this specification, the front side refers to the front side of the paper in Figs. 1 and 2, the bottom side of the paper in Fig. 3, and the left side of the paper in Fig. 4) to the rear side (in this specification, the rear side refers to the back side of the paper in Figs. 1 and 2, the top side of the paper in Fig. 3, and the right side of the paper in Fig. 4). The stirring member 132b transports the developer DP from the rear side to the front side. The developer DP stored in the developing tank 131 is circulated and transported in a reciprocating manner in the developing tank 131 clockwise in a plan view by the stirring members 132a and 132b (see Fig. 3).

[0054] As the developer DP is stirred by stirring members 132a and 132b and circulated back and forth in a cycle of about 10 seconds (5 seconds each way), friction occurs between the toner and carrier that make up the developer DP, causing the toner to become negatively charged and the carrier to become positively charged.

[0055] The agitating member 132b is disposed near the developing roller 133 and along the developing roller 133.

[0056] The developing roller 133 is rotated by a driving device (not shown) and is supplied with a predetermined developing bias.

[0057] A magnet is fixedly disposed at a predetermined position inside the developing roller 133. The developing roller 133 is the "developer carrier" described in the claims, which carries the developer DP composed of toner and carrier.

[0058] The developer DP being transported by the stirring member 132b is caused to adhere to the surface of the developing roller 133 at a position around the lower left of the developing roller 133 in Figure 2 due to the magnetism of the developing roller 133, and is separated from the surface of the developing roller 133 at a position around the upper left of the developing roller 133 in Figure 2.

[0059] As the developing roller 133 rotates, the toner charged with a negative polarity in the developer DP transported to the portion closely facing the photosensitive drum 12 is subjected to a repulsive force from a developing bias of a negative polarity supplied to the developing roller 133, and is supplied to the exposed area on the surface of the photosensitive drum 12. On the other hand, no toner is supplied to the unexposed area. In this way, the developing device 13 develops the electrostatic latent image formed on the surface of the photosensitive drum 12 with toner.

[0060] The supply unit 134 is provided above the upstream side in the direction in which the developer DP is transported by the stirring member 132a. The remaining amount of the toner being transported in a reciprocating circular manner is detected by a magnetic permeability sensor, and when it is detected that the remaining amount of toner is reduced, the toner is replenished via the supply unit 134.

[0061] 2 and 4, the developing device 13 is provided with a film thickness regulating member 135 that is disposed opposite the developing roller 133 and regulates the film thickness of the developer DP carried by the developing roller 133. Note that FIG. 4 is a schematic diagram, and the ratio of each component is different from that in FIG.

[0062] The film thickness regulating member 135 is made of stainless steel angle iron with a thickness of about 1.0 mm to 1.2 mm. The film thickness regulating member 135 is fixed to the housing 130 with a positioning boss (not shown) and a rotation stop boss (not shown) to position the film thickness regulating member 135 and to prevent rotation, and is fixed with screws.

[0063] In this case, the film thickness regulating member 135 is installed so that the distance DG between the opposing surface 135c of the film thickness regulating member 135 facing the developing roller 133 and the developer DP carrying surface 133a of the developing roller 133 becomes larger from the end 135a on one side in the longitudinal direction to the end 135b on the other side.

[0064] The distance DG between the opposing surface 135c at the end 135a on one side and the supporting surface 133a is 130 mm, and the distance DG between the opposing surface 135c at the end 135b on the other side and the supporting surface 133a is 1.45 mm. The distance HD between the inner surface 130a of the housing 130 and the supporting surface 133a of the developing roller 133 is set to be constant at about 2.50 mm.

[0065] As evidence of the validity of the numerical value relating to the distance DG, an experiment was conducted to confirm toner scattering by varying the distance DG between the opposing surface 135c of the film thickness regulating member 135 and the supporting surface 133a from the end portion 135a on one side in the longitudinal direction to the end portion 135b on the other side.

[0066] In Experimental Example 1, the distance DG on the front side was set to 1.30 mm, and the distance DG on the rear side was set to 1.45 mm. The amount of developer DP deposited on the carrying surface 133a of the developing roller 133, which was leveled by the film thickness regulating member 135 at this time, was 143 mg / cm2 on the front side, and 206 mg / cm2 on the rear side.

[0067] In Comparative Example 1, the distance DG on the front side was 1.30 mm, and the distance DG on the rear side was 1.30 mm. At this time, the amount of developer DP deposited on the carrying surface 133a of the developing roller 133, which was leveled by the film thickness regulating member 135, was 140 mg / cm2 on the front side and 143 mg / cm2 on the rear side.

[0068] In Comparative Example 2, the distance DG on the front side was 1.45 mm, and the distance DG on the rear side was 1.45 mm. The amount of developer DP deposited on the carrying surface 133a of the developing roller 133, which was leveled by the film thickness regulating member 135 at this time, was 203 mg / cm2 on the front side and 214 mg / cm2 on the rear side.

[0069] In Comparative Example 3, the distance DG on the front side was 1.40 mm, and the distance DG on the rear side was 1.35 mm. The amount of developer DP deposited on the carrying surface 133a of the developing roller 133, which was leveled by the film thickness regulating member 135 at this time, was 179 mg / cm2 on the front side, and 171 mg / cm2 on the rear side.

[0070] In Comparative Example 4, the distance DG on the front side was 1.45 mm, and the distance DG on the rear side was 1.30 mm. The amount of developer DP deposited on the carrying surface 133a of the developing roller 133, which was leveled by the film thickness regulating member 135 at this time, was 199 mg / cm2 on the front side, and 150 mg / cm2 on the rear side.

[0071] The results showed that the amount of toner scattering increased from Comparative Example 1 to Comparative Example 4. The distance DG in the conventional image forming apparatus 1 corresponds to Comparative Example 1.

[0072] The image forming apparatus 1 according to the present disclosure corresponds to Experimental Example 1, and the result that the scattering of toner in Experimental Example 1 was suppressed more than in any of Comparative Examples 1 to 4 was obtained.

[0073] Furthermore, the film thickness regulating member 135 may be installed so that the distance DG between the opposing surface 135c and the supporting surface 133a at the other end 135b is 3% to 12% larger, preferably 4% to 9% larger, than the distance DG between the opposing surface 135c and the supporting surface 133a at the one end 135a.

[0074] In other words, the distance DG between the opposing surface 135c and the supporting surface 133a at one end 135a is 130 mm, and the distance DG between the opposing surface 135c and the supporting surface 133a at the other end 135b is set to 3% more than 1.30 mm (1.34 mm) to 12% more than 1.30 mm (1.46 mm), preferably 4% more than 1.30 mm (1.35 mm) to 9% more than 1.30 mm (1.42 mm).

[0075] As described above, the toner supplied to one side of the stirring member 132a via the supply section 134 is transported from one side to the other side by the stirring member 132a, and then carried by the developing roller 133 while being transported from the other side to one side by the stirring member 132b.

[0076] Therefore, the toner carried by the developing roller 133 from one side corresponding to the downstream side in the transport direction has a larger charge amount than the toner carried by the developing roller 133 from the other side corresponding to the upstream side in the transport direction.

[0077] The less charged toner is, the more likely it is to be lifted off the carrier by the air current. On the other hand, the more charged toner is, the less likely it is to be lifted off the carrier by the air current. In other words, the toner is more likely to scatter on the other upstream side because the charge is insufficient, whereas the toner is less likely to scatter on the one downstream side because the charge is sufficient.

[0078] Since the distance DG between the opposing surface 135c and the carrying surface 133a of the film thickness regulating member 135 increases from the end 135a on one side to the end 135b on the other side, the film thickness of the developer DP carried by the developing roller 133 can be made thicker from the end 135a on one side to the end 135b on the other side.

[0079] As a result, the gap distance HG between the film surface DS of the developer DP carried on the carrying surface 133a of the developing roller 133 and the inner surface 130a of the housing 130 narrows from the end 135a on one side to the end 135b on the other side, resulting in increased pressure loss and making it difficult for air to pass through.

[0080] Conversely, the gap distance HG between the film surface DS of the developer DP carried on the carrying surface 133a of the developing roller 133 and the inner surface 130a of the housing 130 becomes wider from the other end 135b to the one end 135a, so that the pressure loss becomes smaller and air can easily pass through.

[0081] In this way, the toner has a high charge amount, and by deliberately making it easier for air to pass through areas where there is little risk of the toner being suspended from the carrier by air currents, it is possible to reduce the risk of the toner scattering while still allowing the internal pressure of the developing device 13 to escape.

[0082] In other words, on the upstream side where toner is likely to scatter, the distance DG between the opposing surface 135c and the carrying surface 133a is increased to increase the film thickness of the developer DP carried on the developing roller 133, and the gap between the film surface DS of the developer DP carried on the carrying surface 133a of the developing roller 133 and the inner surface 130a of the housing 130 is narrowed to reduce the airflow, thereby suppressing toner scattering.

[0083] On the other hand, on the downstream side where toner is less likely to scatter, the distance DG between the opposing surface 135c and the carrying surface 133a is reduced to reduce the film thickness of the developer DP carried on the developing roller 133, and the gap between the film surface DS of the developer DP carried on the carrying surface 133a of the developing roller 133 and the inner surface 130a of the housing 130 is widened to increase the airflow, thereby suppressing the increase in the internal pressure of the developing device 13 while suppressing the scattering of toner.

[0084] (Embodiment 2) Next, a second embodiment of the present disclosure will be described. In the image forming apparatus 1 according to the second embodiment, the circulating direction of the reciprocating circulating transport of the DP inside the developing tank 131 is opposite to that in the image forming apparatus 1 according to the first embodiment.

[0085] Accordingly, the position of the supply unit 134 provided in the housing 130 is also different from that in the embodiment 1. The supply unit 134 is similarly provided above the upstream side in the direction in which the developer DP is transported by the stirring member 132a.

[0086] In addition, the film thickness regulating member 135 has a distance DG between the opposing surface 135c of the film thickness regulating member 135 that faces the developing roller 133 and the developer DP carrying surface 133a of the developing roller 133 that becomes smaller from the end portion 135a on one side in the longitudinal direction to the end portion 135b on the other side, and is different from the film thickness regulating member 135 in embodiment 1 in that the inclination direction is reversed.

[0087] Even with this configuration, the same effects as those of the image forming apparatus 1 in the first embodiment can be achieved.

[0088] (Embodiment 3) Next, a description will be given of a third embodiment of the present disclosure. In the image forming apparatus 1 according to the third embodiment, a film thickness regulating member 135 is positioned and prevented from rotating by a positioning boss and a rotation preventing boss (not shown) relative to the housing 130, and is fixed thereto. However, the configuration according to the third embodiment differs from that according to the first and second embodiments in the following points.

[0089] For example, the film thickness regulating member 135 in embodiment 1 is mounted at an angle from one longitudinal end 135a to the other longitudinal end 135b so that the distance DG between the opposing surface 135c of the film thickness regulating member 135 facing the developing roller 133 and the developer DP carrying surface 133a of the developing roller 133 becomes larger, whereas the film thickness regulating member 135 in embodiment 3 is mounted without an angle, but differs in that the opposing surface 135c of the film thickness regulating member 135 is processed so that the distance DG between the opposing surface 135c of the film thickness regulating member 135 and the developer DP carrying surface 133a of the developing roller 133 becomes larger.

[0090] In any of the configurations according to the above-described embodiments, the film thickness regulating member 135 has a different distance DG between the opposing surface 135c and the carrying surface 133a from the end 135a on one side to the end 135b on the other side in the longitudinal direction, so that the film thickness of the developer DP carried on the developing roller 133 is not uniform from the end 135a on one side to the end 135b on the other side. As a result, the gap between the film surface DS of the developer DP carried on the carrying surface 133a of the developing roller 133 and the inner surface 130a of the housing 130 is not uniform.

[0091] Since the airflow preferentially passes through portions with small pressure loss, the path of the airflow can be controlled by varying the pressure loss in the gap between the film surface DS of the developer DP carried on the carrying surface 133a of the developing roller 133 and the inner surface 130a of the housing 130. In other words, it is possible to set a path that can suppress the scattering of toner, thereby reducing unintended scattering of toner from the developing device 13.

[0092] The configurations disclosed in any of the above-described embodiments may be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments of the present disclosure are not limited thereto, and may be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0093] 1: Image forming device 12: Photoconductor drum (image carrier) 13: Developing device 130: Housing 130a: Inner surface 131:Developer tank 132a: Agitation member (first conveying member) 132b: Agitating member (second conveying member) 133: Developing roller (developer carrier) 133a: Support surface 134: Supply Department 135: Film thickness control member 135a: End 135b: End 135c: Opposite surface DP: Developer DS: Membrane surface DG: Distance HG: distance HD: Distance

Claims

1. An image forming apparatus including a developing device that develops toner onto an image carrier, The developing device is a developer tank for storing a developer composed of the toner and a carrier; a replenishing section that replenishing the toner to the developing tank; a first conveying member that is disposed in the developing tank and receives the toner supplied from the supply unit, and a second conveying member that cooperates with the first conveying member to reciprocately convey the developer; a developer carrier that carries the developer received from the second transport member and develops a toner image on the image carrier; a film thickness regulating member disposed opposite to the developer carrying member and regulating a film thickness of the developer carried on the developer carrying member from the second transport member; a housing that houses the developing tank, the first transport member, the second transport member, the developer carrier, and the film thickness regulating member, an image forming apparatus, characterized in that the distance between the surface of the film thickness regulating member facing the developer carrier and the developer carrying surface of the developer carrier varies from one end of the film thickness regulating member to the other end of the film thickness regulating member in the longitudinal direction.

2. the first transport member is configured to transport the developer from the one side to the other side, the second transport member is configured to transport the developer from the other side to the one side, the replenishing unit is provided at a position where the toner can be replenished to the one side of the first conveying member, 2. The image forming apparatus according to claim 1, wherein the thickness regulating member has a distance between the opposing surface and the support surface that increases from the one end to the other end.

3. 2. The image forming apparatus according to claim 1, wherein the film thickness regulating member is attached to the housing such that the distance between the opposing surface and the supporting surface increases from the end on one side to the end on the other side.

4. 2. The image forming apparatus according to claim 1, wherein the carrier is an iron powder carrier.

5. The image forming apparatus according to claim 2, characterized in that the distance between the opposing surface and the supporting surface at the other end of the film thickness regulating member is 3% to 12% larger, preferably 4% to 9% larger, than the distance between the opposing surface and the supporting surface at the one end.

Images