Developing apparatus and image forming apparatus

Abstract

To provide a developing apparatus that can suppress deformation of components. [Solution] The developing apparatus comprises a developing roller 41 that carries developer on its surface, a regulating plate 44 whose tip faces the surface of the developing roller 41 and which regulates the thickness of the developer layer passing between the developing roller 41 and its own tip, a developing housing 42 to which the regulating plate 44 is attached, and a plate cover 43 that is attached to the developing housing 42 with the regulating plate 44 in between. The developing housing 42 and the plate cover 43 are made of resin. The regulating plate 44 is made of metal and is fastened together with the plate cover 43 to the developing housing 42.

Description

Technical Field

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[0001] The present disclosure relates to a developing device and an image forming apparatus having a developer carrier that supports a developer on its surface.

Background Art

[0002] Conventionally, an electrophotographic image forming apparatus is known, and in such an image forming apparatus, a developing device having a developer carrier that supports a developer on its surface is applied. In the developing device, the layer thickness of the developer supported on the surface of the developer carrier is regulated by a developer regulating member so that an intended image can be obtained. In recent years, it has been required to regulate the developer more thinly, and the distance (doctor gap) between the developer carrier and the developer regulating member has a tendency to become narrower, and a method for stabilizing the attached developer regulating member has been proposed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] [[ID=X]] A conventional developing device includes a developer carrier that supports a developer on its surface and moves the position of the surface, and a developer regulating member that regulates the amount of developer passing between a regulating end surface facing the surface of the developer carrier and the surface of the developer carrier. The developer regulating member is composed of a magnetic plate and a non-magnetic plate, and at a location where it is fastened to the developing device main body, the magnetic plate is sandwiched and fastened between the non-magnetic plate and the developing device main body. The magnetic plate is fastened to the non-magnetic plate at a position closer to the regulating end surface of the developer regulating member than the fastening location to the developing device main body.

[0005] In conventional developing equipment, the developer regulating member consists of two components: a magnetic plate and a non-magnetic plate. However, since image forming equipment uses heat fixing, thermal expansion can occur due to changes in the environment. Furthermore, in parts composed of multiple components, the different effects of the materials may cause distortion between fastened components.

[0006] This disclosure is made to solve the above-mentioned problems and aims to provide a developing apparatus and an image forming apparatus that can suppress deformation of components by offsetting distortion due to thermal expansion. [Means for solving the problem]

[0007] The developing apparatus according to this disclosure comprises: a developer carrier that carries a developer on its surface; a layer thickness restricting member whose tip faces the surface of the developer carrier and restricts the thickness of the developer layer passing between the developer carrier and its tip; a housing to which the layer thickness restricting member is attached; and a clamping member attached to the housing with the layer thickness restricting member in between, wherein the housing and the clamping member are made of resin, and the layer thickness restricting member is made of metal and is fastened together with the clamping member to the housing.

[0008] The developing apparatus according to this disclosure may have a plurality of fastening parts at different axial positions along the rotation axis of the developer carrier, wherein the fastening parts near the ends in the axial direction fasten together the layer thickness regulating member and the clamping member to the housing, and the fastening parts near the center in the axial direction fasten only the layer thickness regulating member to the housing.

[0009] In the developing apparatus according to this disclosure, the housing and the clamping member may be made of materials with the same coefficient of thermal expansion.

[0010] In the developing apparatus according to this disclosure, the fastening points of the housing or the clamping member may be configured to have protrusions that project toward the layer thickness regulating member.

[0011] In the developing apparatus according to this disclosure, the housing has pivot supports that pivotally support both ends of the rotating shaft of the developer carrier, the developer carrier has an image forming region corresponding to image formation set in the axial direction along the rotating shaft, and the fastening point between the housing and the clamping member may be located outside the image forming region and inside the pivot supports in the axial direction.

[0012] In the developing apparatus according to this disclosure, the clamping member may have a surface-facing portion that extends longitudinally along the surface of the developer carrier.

[0013] In the developing apparatus according to this disclosure, the thickness of the clamping member may be less than or equal to the thickness of the housing at the surface where the clamping member and the housing are fastened together and overlap.

[0014] In the developing apparatus according to this disclosure, a gap extending in the axial direction along the rotation axis of the developer carrier may be provided between the layer thickness regulating member and the clamping member.

[0015] In the developing apparatus according to this disclosure, the clamping member may be configured to be partially or entirely transparent.

[0016] The image forming apparatus according to this disclosure is characterized by comprising a developing apparatus according to this disclosure. [Effects of the Invention]

[0017] According to this disclosure, by attaching the layer thickness restricting member by sandwiching it between parts of the same material, deformation of the layer thickness restricting member can be suppressed by offsetting the distortion caused by thermal expansion. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2] This is a perspective view of the developing apparatus. [Figure 3]It is an external perspective view showing a developing device with the holding member removed. [Figure 4] It is a schematic exploded view showing a state where the regulating plate, the plate cover, and the developing housing are separated. [Figure 5] It is an exploded perspective view showing a state where the regulating plate, the plate cover, and the developing housing are separated. [Figure 6] It is an enlarged cross-sectional view of the developing device at a portion corresponding to the end screw. [Figure 7] It is an enlarged cross-sectional view of the developing device at a portion corresponding to the center screw. [Figure 8] It is a perspective cross-sectional view of the developing device. [Figure 9] It is a schematic explanatory view showing deformation due to thermal expansion in the structure of the comparative example. [Figure 10] It is a schematic explanatory view showing deformation due to thermal expansion in the structure of the embodiment of the present disclosure. <已翻译内容>0000093< [Figure 11] It is a characteristic diagram showing the transition of the doctor gap in the structure of the comparative example. [Figure 12] It is a characteristic diagram showing the transition of the doctor gap in the structure of the present embodiment. [Figure 13] It is a schematic cross-sectional view showing an enlarged view of the vicinity of the end screw. [Figure 14] It is a perspective view showing a modified example of the plate cover. <已翻译内容>0000101<

Embodiments for Carrying Out the Invention

[0019] Hereinafter, an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings.

[0020] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present disclosure.

[0021] The image forming apparatus 100 is a multifunction device having copying, scanning, facsimile, and printing functions, and transmits images of originals scanned by the image reading device 130 to an external source, or forms images of originals scanned by the image reading device 130 or images received from an external source in color or monochrome on a recording medium such as paper.

[0022] An openable and closable document transport device 110 is provided above the image reading device 130. The document transport device 110 transports one or more documents one by one in sequence. The image reading device 130 generates image data by scanning the document placed on the document tray 130a using the scanning optical system 130b, or by reading the document being transported by the document transport device 110.

[0023] The image forming apparatus 100 includes a fixing device 1, a developing device 2, a photoreceptor drum 3, a drum cleaning device 4, a charger 5, an intermediate transfer belt device 7, a secondary transfer device 11, an exposure unit 12, and a paper feeding unit 18, among others.

[0024] The image forming apparatus 100 handles image data corresponding to color images using black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (for example, black). The image forming apparatus 100 is equipped with four developing devices 2, four photoreceptor drums 3, four drum cleaning devices 4, and four chargers 5 for forming four types of toner images, each corresponding to black, cyan, magenta, and yellow, forming four image stations Pa, Pb, Pc, and Pd.

[0025] The charger 5 uniformly charges the surface of the photoreceptor drum 3 to a predetermined potential. The exposure unit 12 is a light scanning device that exposes the surface of the photoreceptor drum 3 to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photoreceptor drum 3 to form a toner image on the surface of the photoreceptor drum 3. The drum cleaning device 4 removes and recovers residual toner from the surface of the photoreceptor drum 3. Through the above series of operations, toner images of each color are formed on the surface of each photoreceptor drum 3. The structure of the developing device 2 will be described in detail with reference to Figures 2 and 3 below.

[0026] The intermediate transfer belt device 7 comprises intermediate transfer rollers 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 to form four different toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photoreceptor drum 3 to the intermediate transfer belt 71, which moves circulating in the circumferential direction C.

[0027] The intermediate transfer belt 71 is stretched over the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73. In the image forming apparatus 100, the toner images of each color formed on the surface of each photoreceptor drum 3 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 71. The cleaning device 9 removes and collects waste toner that remains on the surface of the intermediate transfer belt 71 without being transferred to the paper.

[0028] The secondary transfer device 11 traps the paper that has been transported through the paper transport path 21 in the transfer nip section between the secondary transfer roller 11a and the intermediate transfer belt 71. As the paper passes through the transfer nip section, the toner image on the surface of the intermediate transfer belt 71 is transferred to the paper and it is then transported to the fuser device 1.

[0029] An image sensor 74 is provided near the intermediate transfer belt 71, facing the surface of the intermediate transfer belt 71. The image sensor 74 is positioned between one of the image stations located furthest downstream in the circumferential direction C (image station Pa in Figure 1) and the secondary transfer device 11. The image sensor 74 is an optical sensor that irradiates light onto the intermediate transfer belt 71, receives the reflected light, and detects the density of the toner image on the intermediate transfer belt 71.

[0030] The fixing device 1 includes a fixing belt 31 and a pressure roller 32 that rotate around an axis. The fixing device 1 inserts the paper on which the toner image has been transferred into the nip between the fixing belt 31 and the pressure roller 32, heats and pressurizes it, and fixes the toner image to the paper. Although not shown in Figure 1, the fixing device 1 may also have components other than the fixing belt 31 and the pressure roller 32.

[0031] The paper feeding unit 18 is equipped with a paper feeding cassette for loading recording media (paper) used for image formation and is located below the exposure unit 12. The paper is pulled out of the paper feeding unit 18 by the pickup roller 16 and transported to the paper transport path 21. The paper transported to the paper transport path 21 passes through the secondary transfer device 11 and the fixing device 1, and is then discharged to the output tray 19 by the discharge roller 17.

[0032] The paper transport path 21 is equipped with a transport roller 13, a registration roller 14, and an ejection roller 17. The transport roller 13 facilitates the transport of the paper. The registration roller 14 transports the paper at a speed equal to the process speed at which the image is formed on the paper. This registration roller 14 is located between the paper feed unit 18 and the secondary transfer device 11 and adjusts the timing of the paper transport so that the toner image is transferred to the paper by the secondary transfer device 11. For example, the registration roller 14 holds the paper transported from the paper feed unit 18 and waits (stops temporarily), then starts transporting the paper at a constant speed in synchronization with the secondary transfer device 11.

[0033] When image formation is to be performed on the back side of the paper as well as the front side, the paper transport direction is changed by the discharge roller 17 and the paper is transported to the inversion transport path 22. In the inversion transport path 22, the paper is guided to the registration roller 14 with its front and back sides reversed by the inversion transport roller 15. The image forming apparatus 100 forms an image on the back side of the paper guided to the registration roller 14 in the same way as the front side and discharges it to the output tray 19.

[0034] Next, the structure of the developing apparatus 2 will be explained with reference to Figures 2 and 3.

[0035] Figure 2 is an external perspective view of the developing apparatus, and Figure 3 is an external perspective view showing the developing apparatus with the clamping member removed.

[0036] The developing apparatus 2 has a developing housing 42 (an example of a housing) that contains a developer including toner, and a developing roller 41 (an example of a developer carrier) that carries the developer is rotatably supported in the developing housing 42. Specifically, the developing housing 42 is a roughly rectangular parallelepiped container with the axial direction W along the rotation axis of the developing roller 41 as the longitudinal direction, and the developer is contained in a cavity provided inside.

[0037] In the developing housing 42, a developing roller 41 is attached to the upper part of one side, and the developing roller 41 faces the bottom of the photoreceptor drum 3. In addition, a plate cover 43 (an example of a clamping member, a doctor cover) is attached to the developing housing 42 so as to cover the side on which the developing roller 41 is attached. As shown in Figure 3, a regulating plate 44 (an example of a layer thickness regulating member, a doctor) is sandwiched between the developing housing 42 and the plate cover 43.

[0038] The regulating plate 44 is a thin, flat plate made of metal and is attached to the developing housing 42 so that its tip faces the surface of the developing roller 41 (see, for example, Figure 6). As the developing roller 41 rotates, the developer carried on its surface passes near the tip of the regulating plate 44, and the thickness of the developer layer is regulated by the regulating plate 44.

[0039] The developing housing 42 and the plate cover 43 are made of the same resin material and have the same coefficient of thermal expansion. The regulating plate 44 has a smaller coefficient of thermal expansion than the developing housing 42 and the plate cover 43. The displacement of the developing housing 42, the plate cover 43, and the regulating plate 44 when they expand due to heat will be explained later with reference to Figures 9 and 10.

[0040] The regulating plate 44 is fastened together with the plate cover 43 to the developing housing 42. Next, the fastening points of the regulating plate 44 and the plate cover 43 to the developing housing 42 will be explained with reference to Figure 4.

[0041] Figure 4 is a schematic exploded view showing the regulating plate, plate cover, and developing housing separated, and Figure 5 is an exploded perspective view showing the regulating plate, plate cover, and developing housing separated.

[0042] In the developing apparatus 2, the regulating plate 44 and the plate cover 43 are fastened together to the developing housing 42 at both ends in the axial direction W, and only the regulating plate 44 is fastened to the developing housing 42 in the central part in the axial direction W. In this embodiment, the regulating plate 44, the plate cover 43, and the developing housing 42 are fastened together by fastening members such as screws. For the purpose of explanation below, the screws that fasten both ends in the axial direction W may be called end screws 45, and the screws that fasten the central part in the axial direction W may be called central screws 46 to distinguish them.

[0043] The developing roller 41 has an image forming region GR that corresponds to image formation, and the image forming region GR occupies almost the entire developing roller 41 except for both ends in the axial direction W. The developing housing 42 is provided with pivot supports 42c at both ends in the axial direction W, which support both ends of the rotation axis of the developing roller 41. Furthermore, the developing housing 42 is provided with housing end fastening holes 42a at both ends in the axial direction W into which end screws 45 are inserted, and a housing center fastening hole 42b at the center in the axial direction W into which a center screw 46 is inserted. The housing end fastening holes 42a are located outside the image forming region GR in the axial direction W and inside the pivot supports 42c.

[0044] The plate cover 43 is provided with cover end fastening holes 43a at both ends in the axial direction W, into which end screws 45 are inserted. When the plate cover 43 is attached to the developing housing 42, the cover end fastening holes 43a are positioned to overlap with the housing end fastening holes 42a.

[0045] The regulating plate 44 is provided with plate end fastening holes 44a at both ends in the axial direction W into which end screws 45 are inserted, and a plate center fastening hole 44b at the center in the axial direction W into which a center screw 46 is inserted. When the regulating plate 44 is attached to the developing housing 42, the plate end fastening holes 44a overlap with the housing end fastening holes 42a, and the plate center fastening hole 44b overlaps with the housing center fastening hole 42b.

[0046] First, the regulating plate 44 is attached to the developing housing 42 and temporarily fastened, and then the plate cover 43 is attached so as to cover the regulating plate 44. Specifically, the central screw 46 is inserted into the central fastening hole 44b of the plate and the central fastening hole 42b of the housing to fasten the regulating plate 44 to the developing housing 42. Then, the end screws 45 are inserted into the end fastening holes 43a of the cover, the end fastening hole 44a of the plate, and the end fastening hole 42a of the housing to fasten the plate cover 43 and the regulating plate 44 together to the developing housing 42.

[0047] In this embodiment, the fastening point is located outside the image forming region GR and near the pivot support portion 42c, so that misalignment of the developing roller 41 can be suppressed without affecting image formation.

[0048] Figure 6 is an enlarged cross-sectional view of the developing device at the end screw, Figure 7 is an enlarged cross-sectional view of the developing device at the center screw, and Figure 8 is a perspective cross-sectional view of the developing device. In Figures 6 and 7, only some components such as the developing housing 42, plate cover 43, and regulating plate 44 are hatched to make each component easier to understand. In Figure 8, a portion of the developing device 2 is shown cut away to reveal the cross-section of the central part in the axial direction W.

[0049] As shown in Figure 6, the housing end fastening hole 42a is approximately the same diameter as the end screw 45, while the cover end fastening hole 43a and the plate end fastening hole 44a are slightly larger in diameter than the end screw 45. Also, as shown in Figure 7, the housing center fastening hole 42b is approximately the same diameter as the center screw 46, while the plate center fastening hole 44b is slightly larger in diameter than the center screw 46.

[0050] The plate cover 43 has a gap between it and the regulating plate 44, and the area near the cover end fastening holes 43a is recessed to the extent that it contacts the regulating plate 44. The gap between the plate cover 43 and the regulating plate 44 exists between the cover end fastening holes 43a located at both ends in the axial direction W, and extends in the axial direction W. By providing a gap between the plate cover 43 and the regulating plate 44 in this way, warping caused by the load applied to the regulating plate 44 can be mitigated.

[0051] The plate cover 43 is provided with a surface-facing portion 43b that extends along the surface of the developing roller 41. The surface-facing portion 43b is located near the tip of the regulating plate 44 and is positioned downstream of the regulating plate 44 in the rotational direction of the developing roller 41. By providing the surface-facing portion 43b in this way, the scattering of the developer can be prevented.

[0052] The plate cover 43 is preferably partially or entirely transparent. In the developing apparatus 2, the distance (doctor gap) between the tip of the regulating plate 44 and the surface of the developing roller 41 is measured using a laser beam measurement method. Therefore, by providing a transparent portion in the plate cover 43, the laser beam used to measure the position of the regulating plate 44 can be transmitted. Modifications of the plate cover 43 will be explained later with reference to Figure 14.

[0053] Next, the deformation of the developing casing 42 due to thermal expansion will be explained with reference to Figures 9 and 10.

[0054] Figure 9 is a schematic diagram illustrating deformation due to thermal expansion in the structure of the comparative example. Note that in Figure 9, the structure of each part is shown schematically, and hatching has been omitted.

[0055] Figure 9 shows the structure of a comparative example in which only the regulating plate 44 is fastened to the developing housing 42, with the state before thermal expansion shown at the top and the state after thermal expansion shown at the bottom. In the comparative example, both ends of the regulating plate 44 are fastened to the developing housing 42 by end screws 45. When heated, the regulating plate 44 hardly expands, while the developing housing 42 expands. At this time, since the developing housing 42 is partially fixed by the end screws 45, the fixing part with the end screws 45 distorts and bends. The upper part of the end screws 45 that contacts the regulating plate 44 hardly displaces, while the lower parts that contact the developing housing 42 tilt so that the gap between them widens. As a result, the regulating plate 44 also bends due to the distortion of the developing housing 42. When the regulating plate 44 bends, the gap with the surface of the developing roller 41 varies from part to part, making it impossible to make the thickness of the developer layer uniform.

[0056] Figure 10 is a schematic diagram illustrating deformation due to thermal expansion in the structure of the embodiment of this disclosure. Note that in Figure 10, the structure of each part is shown schematically, and hatching has been omitted.

[0057] Figure 10 shows the structure of this embodiment, with the state before thermal expansion shown at the top and the state after thermal expansion shown at the bottom. As described above, in this embodiment, the plate cover 43 covers the regulating plate 44 and is fastened together with the developing housing 42. When heated, the plate cover 43 expands along with the developing housing 42. The end screws 45 are displaced so that the gap widens not only at the lower part that contacts the developing housing 42 but also at the upper part that contacts the plate cover 43, thus canceling out the distortion. In this way, by attaching the regulating plate 44 by sandwiching it with parts of the same material, the distortion due to thermal expansion can be canceled out and deformation of the regulating plate 44 can be suppressed.

[0058] Next, we will explain the experimental results of measuring the change in the doctor gap in response to temperature changes, referring to Figures 11 and 12.

[0059] Figure 11 is a characteristic diagram showing the progression of the doctor gap in the structure of the comparative example, and Figure 12 is a characteristic diagram showing the progression of the doctor gap in the structure of this embodiment.

[0060] In the experiment to measure the progression of the doctor gap, the structures of the comparative example and the embodiment were each placed in a constant temperature bath, and the doctor gap was measured as appropriate over time. The doctor gap was measured at three locations: one end in the axial direction W, the center in the axial direction W, and the other end in the axial direction W. Figure 11 shows the doctor gap of the comparative example structure, with first comparison data BR1 corresponding to one end in the axial direction W, second comparison data BR2 corresponding to the center in the axial direction W, and third comparison data BR3 corresponding to the other end in the axial direction W. Figure 12 shows the doctor gap of the embodiment, with first implementation data BT1 corresponding to one end in the axial direction W, second implementation data BT2 corresponding to the center in the axial direction W, and third implementation data BT3 corresponding to the other end in the axial direction W.

[0061] In Figures 11 and 12, the horizontal axis represents the passage of time, and the vertical axis represents the measured doctor gap value. Regarding the time at which the doctor gap was measured, "T1" corresponds to the time when the developing apparatus 2 was assembled, and the temperature at this time is assumed to be 25°C. "T2" corresponds to the state 2 hours after "T1" when the film was placed in a 50°C constant temperature bath. "T3" corresponds to the state 2 hours after the temperature was changed to 25°C at "T2". "T4" corresponds to the state 2 hours after the temperature was changed to 5°C at "T3". "T5" corresponds to the state 2 hours after the temperature was changed to 25°C at "T4". Overall, the doctor gap value increased at "T2", then showed a decreasing trend until "T4", and increased again at "T5".

[0062] As shown in Figure 11, the doctor gap in the comparative example structure fluctuates significantly with temperature changes. In particular, the second comparative data BR2 fluctuates greatly, with the magnitudes of the values ​​at the measurement points changing, suggesting that the regulating plate 44 is warped and distorted.

[0063] As shown in Figure 12, in the structure of this embodiment, the change in the doctor gap in response to temperature changes is smaller compared to the structure of the comparative example. Also, the values ​​at each measurement point change in a similar manner. From this, it can be inferred that the deformation of the regulating plate 44 is suppressed.

[0064] The developing housing 42 and the plate cover 43 are preferably made of a resin such as ABS or PS, and it is desirable that the difference in their thermal expansion coefficients be within ±30%. This ensures that the developing housing 42 and the plate cover 43 expand similarly, thereby appropriately canceling out distortion due to thermal expansion. The developing housing 42 and the plate cover 43 may be made of the same type of resin, or they may be made of different types of resin.

[0065] Furthermore, at the overlapping surfaces where the plate cover 43 and the developing housing 42 are fastened together, it is preferable that the thickness of the plate cover 43 be less than or equal to the thickness of the developing housing 42. By making the plate cover 43 the same thickness as or smaller than the developing housing 42, the regulating plate 44 can be firmly fixed while avoiding an increase in the size of the developing apparatus 2. In the developing apparatus 2, the central part is fixed to position the regulating plate 44, and the ends, which are far apart, are fastened together, thereby efficiently canceling out distortion.

[0066] Next, a modified example of the developing apparatus 2 will be described with reference to Figure 13.

[0067] Figure 13 is a schematic cross-sectional view showing a magnified view of the vicinity of the end screw. Note that in Figure 13, the structure of each part is schematically shown, and hatching has been omitted.

[0068] In the modified example, the fastening points between the developing housing 42 and the plate cover 43 are provided with protrusions (housing protrusions 42d and cover protrusions 43c) that project toward the regulating plate 44. By providing the housing protrusions 42d and cover protrusions 43c in this way, the contact area with the regulating plate 44 is reduced, preventing displacement under light loads while preventing distortion caused by sliding the regulating plate 44 under loads exceeding a certain level. However, the invention is not limited to this, and a configuration with only one of the housing protrusions 42d and cover protrusions 43c is also possible.

[0069] Figure 14 is a perspective view showing a modified version of the plate cover.

[0070] In a modified version of the plate cover 43, as indicated by arrow A, a portion of the surface-facing part 43b that faces the tip of the regulating plate 44 is made of transparent resin. By providing a transparent portion in the plate cover 43, even when the plate cover 43 is attached to cover the regulating plate 44, the laser beam can pass through the transparent portion and irradiate the area near the tip of the regulating plate 44 when measuring the doctor gap.

[0071] Furthermore, the embodiments disclosed herein are illustrative in all respects and do not constitute a limiting interpretation. Accordingly, the technical scope of this disclosure is not to be interpreted solely by the embodiments described above, but is defined based on the claims. This includes all modifications within the meaning and scope of equivalents to the claims. [Explanation of Symbols]

[0072] 2. Developing device 41. Developing roller (an example of a developer carrier) 42. Developing cabinet (an example of a cabinet) 42c axis branch 43. Plate cover (an example of a clamping member) 43b Surface facing part 44. Regulating plate (an example of a layer thickness regulating member) 45 End screws 46 Center screw 100 Image forming apparatus W axis direction

Claims

1. A developer carrier having a developer supported on its surface, A layer thickness regulating member, whose tip is positioned opposite the surface of the developer carrier, regulates the thickness of the developer layer passing between the developer carrier and its own tip. A housing to which the aforementioned layer thickness regulating member is attached, A developing apparatus comprising a clamping member attached to the housing with the layer thickness regulating member sandwiched in between, The housing and the clamping member are made of resin. The layer thickness restricting member is made of metal and is fastened together with the clamping member to the housing. A developing apparatus characterized by the following.

2. A developing apparatus according to claim 1, The developer carrier has multiple fastening parts at different axial positions along its rotation axis, The fastening portion near the end in the axial direction is fastened together with the layer thickness restricting member and the clamping member to the housing. In the fastening portion near the center in the axial direction, only the layer thickness restricting member is fastened to the housing. A developing apparatus characterized by the following.

3. A developing apparatus according to claim 1, The housing and the clamping member are made of materials with the same coefficient of thermal expansion. A developing apparatus characterized by the following.

4. A developing apparatus according to claim 1, The fastening points of the housing or the clamping member are provided with protrusions that extend toward the layer thickness regulating member. A developing apparatus characterized by the following.

5. A developing apparatus according to claim 1, The housing has pivot points that pivotally support both ends of the rotating shaft of the developer carrier, The developer carrier has an image forming region set in the axial direction along the rotation axis, corresponding to image formation. The fastening point between the housing and the clamping member is located outside the image forming region and inside the pivot point in the axial direction. A developing apparatus characterized by the following.

6. A developing apparatus according to claim 1, The clamping member has a surface-facing portion that extends longitudinally along the surface of the developer carrier. A developing apparatus characterized by the following.

7. A developing apparatus according to claim 1, In the overlapping surfaces where the clamping member and the housing are fastened together, the thickness of the clamping member is less than or equal to the thickness of the housing. A developing apparatus characterized by the following.

8. A developing apparatus according to claim 1, A gap is provided between the layer thickness restricting member and the clamping member, extending in the axial direction along the rotation axis of the developer carrier. A developing apparatus characterized by the following.

9. A developing apparatus according to claim 1, The clamping member is partially or entirely transparent. A developing apparatus characterized by the following.

10. An image forming apparatus comprising the developing apparatus described in claim 1.

Images