JP4470925B2 - Developer supply apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a developer electric field transport device, a developer supply device, and an image forming apparatus.

  Many mechanisms for conveying toner (developer) using a traveling wave electric field in an image forming apparatus have been conventionally known (for example, Japanese Patent Application Laid-Open Nos. 2002-99143 and 2002-351218, and Japanese Patent Application Laid-Open No. 2002-351218). 2003-15417, etc.).

  In such a mechanism, a large number of linear electrodes are arranged in a row on an insulating substrate. A wiring pattern is provided outside the substrate in the width direction perpendicular to the arrangement direction of the linear electrodes.

According to this mechanism, a multiphase AC voltage is sequentially applied to the large number of linear electrodes by the wiring pattern. Thereby, a traveling wave electric field is formed. Due to the action of the traveling wave electric field, the charged toner particles are transported in a predetermined direction.
JP 2002-99143 A JP 2002-351218 A JP 2003-15417 A

  In the mechanism capable of transporting the charged developer by the traveling wave electric field as described above (hereinafter referred to as “developer electric field transport device”), the end of the substrate in the width direction, and the line Traveling-wave electric field that can satisfactorily transport the developer in the predetermined direction in the outer region of the electrode (the outer region in the width direction of the linear electrode or the region corresponding to the wiring pattern) Is not formed. Therefore, when the developer enters the area, the developer can stay in the area for a long time. Due to the retention of the developer, the developer is likely to be fixed or scattered to the outside.

  The present invention has been made to solve such problems. That is, an object of the present invention is to provide a developer electric field transport device that can smoothly transport a developer in a predetermined direction by a traveling wave, a developer supply device including the developer electric field transport device, and an image forming apparatus. It is in.

  (1) An image forming apparatus of the present invention includes an electrostatic latent image carrier and a developer supply device.

  The electrostatic latent image carrier has a latent image forming surface. The latent image forming surface is configured such that an electrostatic latent image by a potential distribution can be formed. This latent image forming surface is formed in parallel with a predetermined main scanning direction. The electrostatic latent image carrier is configured such that the latent image forming surface can move along a sub-scanning direction orthogonal to the main scanning direction.

  The developer supply device is disposed to face the electrostatic latent image carrier. The developer supply device is configured to supply the developer to the latent image forming surface in a charged state. Specifically, the developer supply device includes a plurality of transport electrodes, a power supply wiring portion, a developer transport body, a pair of developer transport guide members, and a developer containing casing.

  The plurality of transport electrodes are arranged in a predetermined developer transport direction along the sub-scanning direction. These transport electrodes are configured to have a longitudinal direction that intersects the sub-scanning direction. Specifically, for example, the transport electrode may be configured to have a longitudinal direction parallel to the main scanning direction orthogonal to the sub-scanning direction. The developer transport direction can be set in parallel with the sub-scanning direction.

  The feed wiring portion is connected to a root portion of the transport electrode that is one end portion in the longitudinal direction. That is, a predetermined wiring pattern is formed by the transport electrode and the power supply wiring portion. And the terminal of this wiring pattern is formed by the front-end | tip part which is the edge part (the other end part on the opposite side to the said one end part in the said longitudinal direction) opposite to the said base part of the said conveyance electrode.

  The developer transport body has a developer transport surface parallel to the main scanning direction. Along the developer transport surface, the transport electrode and the power supply wiring portion are provided on the developer transport body. In other words, the predetermined wiring pattern formed by the transport electrode and the power supply wiring portion is provided on the developer transport body along the developer transport surface.

  The developer transport body is disposed such that the developer transport surface faces the electrostatic latent image carrier. The developer transport body transports the developer in the developer transport direction by a traveling wave electric field generated on the developer transport surface when a predetermined transport voltage is applied to the plurality of transport electrodes. It is configured to be able to.

  The pair of developer transport guide members are provided on the developer transport surface at both ends of the developer transport body in the width direction perpendicular to the developer transport direction. These developer transport guide members are configured to define a range in which the developer is transported in the developer transport direction on the developer transport surface.

  The developer storage casing is a box-shaped member configured to cover the developer transport body and the developer transport guide member and store the developer. An opening is formed in the developer containing casing. The opening is provided at a position where the electrostatic latent image carrier and the developer transport surface face each other.

  The feature of the present invention resides in the following points: That is, the developer transport guide member is more than the root portion of the transport electrode and the tip portion that is the end opposite to the root portion. It is provided on the inner side in the width direction so as to protrude toward the surface where the opening of the developer containing casing is formed. The developer transport guide member protrudes as described above, and is configured and arranged so that leakage of the developer to the outside in the width direction can be suppressed more than the developer transport guide member. ing.

  The image forming apparatus of the present invention having such a configuration operates as follows during image formation.

  The latent image forming surface on which the electrostatic latent image is formed moves along the sub-scanning direction. The developer supply device supplies the developer in a charged state to the latent image forming surface on which the electrostatic latent image is formed. The developer is guided by the developer transport guide member on the developer transport surface, and in a predetermined developer transport direction (a direction along the sub-scanning direction, which is an array direction of the plurality of transport electrodes). ). Thereby, the electrostatic latent image is developed (visualized) by the developer.

  As described above, the developer is transported on the developer transport surface by forming a predetermined traveling-wave electric field in the vicinity of the plurality of transport electrodes. Such an electric field is formed by applying a predetermined voltage to the plurality of transport electrodes via the power supply wiring portion.

  Here, a traveling-wave electric field along the developer transport direction is favorably formed in an inner portion (intermediate portion) of the transport electrode in the width direction with respect to the tip portion and the root portion. On the other hand, it is difficult (or is not formed) to form a good traveling-wave electric field at the distal end portion and the root portion of the transport electrode and the power supply wiring portion.

  Therefore, in the image forming apparatus of the present invention, the developer transport guide member protrudes on the inner side in the width direction from the tip portion and the root portion. That is, the developer transport guide member is erected at the outer edge portion in the width direction of the intermediate portion. As a result, leakage of the developer to a portion where a favorable traveling wave electric field is difficult to be formed is suppressed by the developer transport guide member.

  Therefore, according to the image forming apparatus of the present invention, smooth conveyance of the charged developer on the developer conveyance surface can be realized with a simple apparatus configuration. Therefore, the retention of the developer on the developer transport surface can be suppressed as much as possible by a simple apparatus configuration.

  In the image forming apparatus, the developer transport guide member is configured such that placement of the developer on a top surface that is a surface opposite to a surface facing the developer transport surface can be suppressed. May be. Specifically, for example, the developer transport guide member can be configured such that the top surface is in contact with the developer containing casing. Alternatively, for example, the top surface may be formed in a slope shape that can slide the developer toward the intermediate portion.

  According to the image forming apparatus having such a configuration, retention of the developer on the top surface of the developer transport guide member can be suppressed as much as possible.

  The image forming apparatus may further include a plurality of counter electrodes, and the developer transport guide member may be interposed between the developer transport surface and the counter electrode.

  Here, the plurality of counter electrodes are arranged along the developer transport direction. These counter electrodes are configured to have a longitudinal direction that intersects the sub-scanning direction. For example, the counter electrode may be configured to have a longitudinal direction parallel to the main scanning direction orthogonal to the sub-scanning direction. Alternatively, the counter electrode may be formed in parallel with the transport electrode. The counter electrode is disposed so as to face the developer transport surface with a predetermined gap therebetween.

  In the image forming apparatus having such a configuration, when a predetermined voltage is applied, a predetermined traveling-wave electric field is generated in the plurality of counter electrodes and the plurality of transport electrodes. Thereby, the charged developer can be transported more smoothly on the developer transport surface.

  In the image forming apparatus, the developer conveyance guide member may be made of an elastic body. For example, the developer transport guide member can be made of foaming sponge, rubber or the like.

  The developer transport guide member made of such an elastic body can be interposed in a compressed state between the both ends of the developer transport body and the developer containing casing.

  According to the image forming apparatus having such a configuration, it is possible to more effectively suppress the leakage of the developer to the portion where a favorable traveling wave electric field is difficult to be formed.

  (2) The developer supply device of the present invention is configured so that the developer can be supplied in a charged state to the developer carrying surface of the developer carrying member. Here, the developer carrying surface is a surface parallel to a predetermined main scanning direction and capable of carrying the developer.

  The developer carrying member has the developer carrying surface and is configured so that the developer carrying surface can move along a sub-scanning direction orthogonal to the main scanning direction. As the developer carrying member, for example, an electrostatic latent image carrying member having a latent image forming surface configured to be able to form an electrostatic latent image by potential distribution can be used. Alternatively, as the developer carrying member, for example, a recording medium (paper) conveyed along the sub-scanning direction can be used. Alternatively, as the developer carrier, for example, the developer can be transferred onto the recording medium or the electrostatic latent image carrier by facing the recording medium or the electrostatic latent image carrier. A roller, sleeve, or belt-shaped member (intermediate transfer belt, developing roller, developing sleeve, etc.) constructed and arranged can be used.

  The developer supply device of the present invention includes a plurality of transport electrodes, a power supply wiring portion, a developer transport body, a pair of developer transport guide members, and a developer containing casing.

  The plurality of transport electrodes are arranged in a predetermined developer transport direction along the sub-scanning direction. These transport electrodes are configured to have a longitudinal direction that intersects the sub-scanning direction.

  The power supply wiring portion is connected to a root portion that is one end portion in the longitudinal direction of the transport electrode.

  The developer transport body has a developer transport surface parallel to the main scanning direction. Along the developer transport surface, the transport electrode and the power supply wiring portion are provided on the developer transport body. The developer transport body is disposed such that the developer transport surface faces the developer carrier. The developer transport body transports the developer in the developer transport direction by a traveling wave electric field generated on the developer transport surface when a predetermined transport voltage is applied to the plurality of transport electrodes. Configured to get.

  The pair of developer transport guide members are provided on the developer transport surface at both ends of the developer transport body in the width direction perpendicular to the developer transport direction. These developer transport guide members are configured to define a range in which the developer is transported in the developer transport direction on the developer transport surface.

  The developer storage casing is a box-shaped member configured to cover the developer transport body and the developer transport guide member and store the developer. An opening is formed in the developer containing casing. The opening is provided at a position where the developer carrying member and the developer transport surface face each other.

  The feature of the present invention resides in the following points: That is, the developer transport guide member is more than the root portion of the transport electrode and the tip portion that is the end opposite to the root portion. On the inner side in the width direction, the developer containing casing is provided so as to protrude toward the surface where the opening is formed. The developer transport guide member protrudes as described above, and is configured and arranged so that leakage of the developer to the outside in the width direction can be suppressed more than the developer transport guide member. ing.

  In the developer supply apparatus of the present invention having such a configuration, the developer carrying surface (the developer carrying body) that moves along the sub-scanning direction, the developer carrying surface (the developer carrying body), and The developer is supplied in a charged state to the positions facing each other. Accordingly, the developer can be supplied to the developer carrying surface of the developer carrying body.

  At this time, the developer is guided by the developer transport guide member on the developer transport surface, and is transported in a predetermined developer along the sub-scanning direction, which is an arrangement direction of the plurality of transport electrodes. Conveyed in the direction. Such transport of the developer on the developer transport surface is performed by applying a predetermined voltage to the plurality of transport electrodes via the power supply wiring portion.

  Here, a traveling-wave electric field along the developer transport direction is favorably formed in a portion (intermediate portion) between the tip portion and the root portion of the transport electrode. On the other hand, it is difficult for a good traveling-wave electric field to be formed in the distal end portion, the root portion, and the power supply wiring portion of the transport electrode.

  However, in the developer supply device of the present invention, the developer transport guide member is erected at the outer edge portion of the intermediate portion. Therefore, leakage of the developer to a portion where a favorable traveling-wave electric field is difficult to be formed as described above can be effectively suppressed by the developer transport guide member.

  Therefore, according to the developer supply apparatus of the present invention, smooth conveyance of the charged developer on the developer conveyance surface can be realized with a simple apparatus configuration. Therefore, the retention of the developer on the developer transport surface can be suppressed as much as possible by a simple apparatus configuration.

  In the developer supply apparatus, the developer transport guide member may be restrained from placing the developer on a top surface that is a surface opposite to the surface facing the developer transport surface. It may be configured. Specifically, for example, the developer transport guide member can be configured such that the top surface is in contact with the developer containing casing.

  According to the developer supply device having such a configuration, retention of the developer on the top surface of the developer transport guide member can be suppressed as much as possible.

  The developer supply device may further include a plurality of counter electrodes, and the developer transport guide member may be interposed between the developer transport surface and the counter electrode.

  Here, the plurality of counter electrodes are arranged along the developer transport direction. These counter electrodes are configured to have a longitudinal direction that intersects the sub-scanning direction. For example, the counter electrode may be configured to have a longitudinal direction parallel to the main scanning direction orthogonal to the sub-scanning direction. Alternatively, the counter electrode may be formed in parallel with the transport electrode. The counter electrode is disposed so as to face the developer transport surface with a predetermined gap therebetween.

  In the developer supply apparatus having such a configuration, when a predetermined voltage is applied, a predetermined traveling-wave electric field is generated in the plurality of counter electrodes and the plurality of transport electrodes. Thereby, the charged developer can be transported more smoothly on the developer transport surface.

  In the developer supply device, the developer transport guide member may be formed of an elastic body. For example, the developer transport guide member can be made of foaming sponge, rubber or the like. The developer transport guide member can be interposed, for example, in a compressed state between the both ends of the developer transport body and the developer containing casing.

  According to the developer supply device having such a configuration, leakage of the developer to a portion where a favorable traveling wave electric field is difficult to be formed as described above can be more effectively suppressed.

  (3) The developer electric field transport device of the present invention is configured to transport the charged developer by an electric field. Specifically, the developer electric field transport device includes a plurality of transport electrodes, a power supply wiring portion, a developer transport body, and a pair of developer transport guide members.

  The plurality of transport electrodes are arranged in a predetermined developer transport direction along the sub-scanning direction. Here, the sub-scanning direction is a moving direction of the developer carrying member on which the developer is carried. These transport electrodes are configured to have a longitudinal direction that intersects the sub-scanning direction.

  The power supply wiring portion is connected to a root portion that is one end portion in the longitudinal direction of the transport electrode.

  The developer transport body has a developer transport surface parallel to the main scanning direction. Here, the main scanning direction is a direction orthogonal to the sub-scanning direction. Along the developer transport surface, the transport electrode and the power supply wiring portion are provided on the developer transport body. The developer transport body is disposed such that the developer transport surface faces the developer carrier. The developer transport body transports the developer in the developer transport direction by a traveling wave electric field generated on the developer transport surface when a predetermined transport voltage is applied to the plurality of transport electrodes. It is configured to be able to.

  The developer transport guide member is provided on the developer transport surface at both ends of the developer transport body in the width direction perpendicular to the developer transport direction. The pair of developer transport guide members are configured and arranged so as to define a range in which the developer is transported in the developer transport direction on the developer transport surface.

  The features of the present invention lie in the following points: the developer transport guide member is more in the width direction than the root portion of the transport electrode and the tip portion opposite to the root portion; It is arranged inside. The developer transport guide member is configured so as to suppress leakage of the developer to the outside in the width direction with respect to the developer transport guide member.

  The developer electric field transport apparatus of the present invention having such a configuration includes the developer carrying surface (the developer carrying body) that moves along the sub-scanning direction, the developer carrying surface (the developer carrying body), and The developer in a charged state is transported toward the position where the opposite faces. Accordingly, the developer is guided by the developer transport guide member on the developer transport surface, and the predetermined developer transport along the sub-scanning direction which is an arrangement direction of the plurality of transport electrodes. Conveyed in the direction. In this way, the developer is supplied to the developer carrying surface of the developer carrying body.

  As described above, the developer is transported on the developer transport surface by applying a predetermined voltage to the plurality of transport electrodes via the power supply wiring portion. At this time, a traveling-wave electric field along the developer transport direction is favorably formed in a portion (intermediate portion) between the tip portion and the root portion of the transport electrode. On the other hand, it is difficult for a good traveling-wave electric field to be formed in the distal end portion, the root portion, and the power supply wiring portion of the transport electrode.

  However, leakage of the developer to such a portion where it is difficult to form a good traveling-wave electric field causes the developer conveyance to define a range in which the developer is conveyed on the developer conveyance surface. It is effectively suppressed by the guide member.

  Therefore, according to the developer electric field transport device of the present invention, smooth transport of the charged developer on the developer transport surface can be realized with a simple device configuration. Therefore, the retention of the developer on the developer transport surface can be suppressed as much as possible by a simple apparatus configuration.

  In the developer electric field transport device, the developer transport guide member may be restrained from placing the developer on the top surface that is the surface opposite to the surface facing the developer transport surface. It may be configured.

  According to the developer electric field transport device having such a configuration, the stagnation of the developer on the top surface of the developer transport guide member can be suppressed as much as possible.

  In the developer electric field transport device, the developer transport guide member may be made of an elastic body. For example, the developer transport guide member can be made of foaming sponge, rubber or the like.

  Hereinafter, embodiments of the present invention (embodiments that the applicant considers best at the time of filing of the present application) will be described with reference to the drawings.

<Overall configuration of laser printer>
FIG. 1 is a side sectional view showing a schematic configuration of a laser printer 100 to which an embodiment of the present invention is applied.

  Here, in FIG. 1, a sheet conveyance path PP which is a conveyance path of the sheet P as a recording medium which is an image formation target is indicated by a two-dot chain line. The tangential direction of the paper transport path PP is referred to as a paper transport direction.

  Further, the x-axis direction in the figure is referred to as the front-rear direction. One end side (right side in the figure) of the laser printer 100 in the front-rear direction is referred to as “front” side. On the other hand, the other end side (left side in the figure) opposite to the one end side of the laser printer 100 is referred to as a “rear” side. Further, the height direction of the laser printer 100 (y-axis direction in the figure), the paper conveyance direction, and the direction orthogonal to the front-rear direction are defined as the paper width direction (z-axis direction in the figure) as the “width direction” in the present invention. ).

<< Main body >>
Referring to FIG. 1, a laser printer 100 as an image forming apparatus of the present invention includes a main body casing 112. The main body casing 112 is a member constituting an outer cover of the laser printer 100, and is integrally formed of a synthetic resin plate. A paper discharge port 112 a made up of a slit-shaped through hole is formed on the front side of the upper portion of the main body casing 112.

  A paper discharge tray 114 is mounted on the front side of the upper portion of the main body casing 112 at a position corresponding to the paper discharge port 112a. The paper discharge tray 114 is configured to receive the image-formed paper P discharged from the paper discharge port 112a.

<< Electrostatic latent image forming section >>
An electrostatic latent image forming unit 120 is accommodated in the main body casing 112. The electrostatic latent image forming unit 120 includes a photosensitive drum 121 as an electrostatic latent image carrier and a developer carrier of the present invention.

  The photosensitive drum 121 is a substantially cylindrical member, and is arranged so that the rotation center axis thereof is parallel to the paper width direction. The photosensitive drum 121 is configured to be driven to rotate clockwise in the drawing.

  Specifically, the photosensitive drum 121 includes a drum main body 121a and a photosensitive layer 121b.

  The drum body 121a is made of a metal tube such as an aluminum alloy. The photoconductor layer 121b is a positively chargeable photoconductive layer, and is formed on the outer periphery of the drum body 121a.

  The photosensitive drum 121 has an image carrying surface 121b1 that constitutes a latent image forming surface and a developer carrying surface of the present invention. The image carrying surface 121b1 is constituted by the peripheral surface of the photoreceptor layer 121b. The image carrying surface 121b1 is formed to be parallel to the paper width direction and the main scanning direction described later. The image carrying surface 121b1 is configured such that an electrostatic latent image can be formed by a potential distribution.

  That is, the photosensitive drum 121 is configured such that the image bearing surface 121b1 can move along a sub-scanning direction, which will be described later, orthogonal to the main scanning direction.

  The electrostatic latent image forming unit 120 includes a scanner unit 122 and a charger 123.

  The scanner unit 122 applies the laser beam LB having the predetermined wavelength modulated based on the image information at a predetermined scan position SP along a main scanning direction (z-axis direction in the drawing) parallel to the paper width direction. It is configured and arranged so that the image bearing surface 121b1 can be irradiated while scanning. The charger 123 is disposed upstream of the scan position SP in the moving direction of the image carrying surface 121b1 (the rotation direction of the photosensitive drum 121). The charger 123 is configured and arranged so that the image carrying surface 121b1 upstream in the direction from the scan position SP can be uniformly positively charged.

  The electrostatic latent image forming unit 120 irradiates the image carrying surface 121b1 uniformly positively charged by the charger 123 with the laser beam LB by the scanner unit 122, thereby static electricity due to the potential distribution (charge distribution). An electrostatic latent image can be formed on the image bearing surface 121b1. The electrostatic latent image forming unit 120 is configured to be able to move the image carrying surface 121b1 on which the electrostatic latent image is formed along the sub-scanning direction.

  Here, the “sub-scanning direction” is an arbitrary direction orthogonal to the main scanning direction. Usually, the sub-scanning direction is a direction intersecting the vertical line. That is, the sub-scanning direction is a direction along the front-rear direction (x-axis direction in the drawing) of the laser printer 100.

<< Developing device >>
Inside the main casing 112 is housed a developing device 130 constituting the developer supply device and developer electric field transport device of the present invention. The developing device 130 is disposed so as to face the photosensitive drum 121 at the development facing position DP.

  In the vicinity of the development facing position DP, the developing device 130 charges the toner T, which is a fine particle dry developer (powder developer), on the image bearing surface 121b1 on which the electrostatic latent image is formed. In order to be able to supply, it is constituted and arranged as follows. Note that the toner T in this embodiment is used for non-magnetic one-component development in an electrophotographic system.

  FIG. 2 is an enlarged side sectional view of the electrostatic latent image forming unit 120 and the developing device 130 shown in FIG.

  Referring to FIGS. 1 and 2, the developing device 130 is disposed below the photosensitive drum 121 so as to face the downstream image carrying surface 121b1 in the moving direction of the image carrying surface 121b1 with respect to the scan position SP. Yes.

<<< Development casing >>>
The developing casing 131 as the developer containing casing of the present invention is a box-like member and is configured to contain the toner T.

  A developing opening 131a2 as an opening of the present invention is formed in the developing portion facing plate 131a1, which is a rear portion of the casing upper surface cover 131a constituting the top plate of the developing casing 131. The development opening 131a2 is provided at a position facing the image carrying surface 121b1 on the development unit facing plate 131a1.

  The casing bottom plate 131b constituting the bottom plate of the developing casing 131 and the developing portion facing plate 131a1 are integrally formed at the rear end portion of the developing casing 131 so as to be smoothly connected in a substantially U shape. Yes. Both ends of the casing top cover 131a and the casing bottom plate 131b in the sheet width direction are closed by a pair of casing side plates 131c. Further, the front ends of the casing top cover 131a, the casing bottom plate 131b, and the pair of casing side plates 131c are closed by a casing front closing plate 131d.

<<< Developer Electric Field Carrier >>>
Referring to FIG. 2, a locking groove 131e is provided on the inner side surface of the casing side plate 131c (the surface facing the space in which the toner T is accommodated). The locking groove 131e is formed in an inverted U shape when viewed from the side.

  A toner electric field transport body 132 constituting the developer transport body of the present invention is accommodated inside the developing casing 131. That is, the toner electric field transport body 132 is covered with the developing casing 131.

  The toner electric field carrier 132 is disposed on the rear side in the space inside the developing casing 131 so as to face the image carrying surface 121b1 with the developing opening 131a2 interposed therebetween. That is, the toner electric field transport body 132 is provided so that the photosensitive drum 121 and the toner electric field transport body 132 are opposed to each other with the development opening 131a2 interposed therebetween.

  Both ends of the toner electric field transport body 132 are locked in the above-described locking grooves 131e provided in the pair of casing side plates 131c. In this manner, the toner electric field transport body 132 is supported in a state of being floated from the casing bottom plate 131b while facing the developing portion facing plate 131a1 with a predetermined gap.

  FIG. 3 is an enlarged side cross-sectional view of a portion near the developing opening 131a2 in the toner electric field transport body 132 shown in FIG. Referring to FIGS. 2 and 3, the toner electric field transport body 132 includes a transport wiring board 133. The transport wiring substrate 133 is disposed so as to face the image carrying surface 121b1 with the development opening 131a2 interposed therebetween.

  Referring to FIG. 3, the transport wiring board 133 is a printed wiring board, and includes a transport electrode 133a, a transport electrode support substrate 133b, and a transport electrode coating layer 133c.

  The transport electrode 133a is made of a copper foil having a thickness of about several tens of μm, and is provided on the transport electrode support substrate 133b. The transport electrode 133a is formed as a linear wiring pattern having a longitudinal direction parallel to the main scanning direction (perpendicular to the sub-scanning direction). A plurality of transport electrodes 133a are arranged in parallel to each other and arranged along a predetermined toner transport direction TTD parallel to the sub-scanning direction (x direction in the drawing).

  A plurality of transport electrodes 133a arranged in the sub-scanning direction are connected to the same power supply circuit every third. That is, the transfer electrode 133a connected to the power supply circuit VA, the transfer electrode 133a connected to the power supply circuit VB, the transfer electrode 133a connected to the power supply circuit VC, the transfer electrode 133a connected to the power supply circuit VD, and the power supply circuit VA The connected transport electrodes 133a, the transport electrodes 133a connected to the power supply circuit VB, are sequentially arranged along the sub-scanning direction.

  The transport electrode support substrate 133b is a flexible film and is made of an insulating synthetic resin such as a polyimide resin. A transport electrode coating layer 133c is provided on the surface of the transport electrode support substrate 133b on which the transport electrode 133a is formed.

  The transport electrode coating layer 133c is provided so as to form a toner transport surface 133d as a developer transport surface of the present invention on a smooth surface by covering the transport electrode support substrate 133b and the transport electrode 133a. Here, the toner transport surface 133d is a surface of the transport wiring substrate 133 that faces the image carrying surface 121b1, and is formed in parallel with the main scanning direction (z direction in the drawing). The toner conveying surface 133d and the image carrying surface 121b1 are closest to each other at the development facing position DP. A transport electrode 133a is provided along the toner transport surface 133d.

  Referring to FIGS. 2 and 3, the toner electric field transport body 132 includes a transport substrate support member 134. The transport board support member 134 is provided so as to support the transport wiring board 133 from below.

  Referring to FIG. 2, the rear end of the transport substrate support member 134 is formed to be bent downward along the casing upper surface cover 131 a in the developing casing 131. The front end portion of the transport substrate support member 134 is also formed in the same shape as the rear end portion so as to be bent downward. The part between the above-mentioned both ends of the conveyance board | substrate support member 134 is formed in substantially flat form. That is, the transport substrate support member 134 is formed in an inverted U shape in a side view that is substantially the same shape as the locking groove 131e.

  FIG. 4 is a graph showing waveforms of voltages generated by the power supply circuits VA to VD shown in FIG. As shown in FIG. 4, each of the power supply circuits VA to VD is configured to generate an AC voltage having substantially the same waveform. Here, the waveforms of the voltages generated by the power supply circuits VA to VD are different in phase by 90 °. That is, the power supply circuits VA to VD are controlled by a control circuit (not shown) so that the phase of the voltage is delayed by 90 ° in order from the power supply circuit VA to the power supply circuit VD.

  Referring to FIGS. 2 and 3, the toner electric field transport body 132 applies a transport voltage as shown in FIG. 4 to each transport electrode 133 a on the transport wiring substrate 133, and the above-described sub-scanning direction. By generating a traveling-wave electric field along the parallel toner transport direction TTD, the positively charged toner T can be transported along the toner transport direction TTD.

  Referring to FIGS. 1 and 2, a counter wiring substrate 135 is supported on the inner wall surfaces of the developing unit counter plate 131a1 and the casing bottom plate 131b. That is, the counter wiring substrate 135 is supported by the inner wall surface of the developing unit facing plate 131a1 in which the developing opening 131a2 is formed so as to face the toner transport surface 133d with a predetermined gap therebetween. In the present embodiment, the counter wiring board 135 is provided over substantially the entire length of the casing bottom plate 131b in the front-rear direction.

  The counter wiring board 135 has the same configuration as the above-described transport wiring board 133. That is, referring to FIG. 3, the counter wiring substrate 135 includes a counter electrode 135a, a counter electrode support substrate 135b, and a counter electrode coating layer 135c.

  Specifically, the counter electrode 135a is formed to have a longitudinal direction in the main scanning direction, which is a direction orthogonal to the sub-scanning direction, like the transport electrode 133a. A plurality of counter electrodes 135a are arranged in parallel to each other. Further, the plurality of counter electrodes 135a are arranged along a toner transport direction TTD parallel to the sub-scanning direction.

  Similar to the above-described transport wiring substrate 133, the counter wiring substrate 135 is applied with a predetermined voltage to the plurality of counter electrodes 135a to generate a traveling-wave electric field along the toner transport direction TTD parallel to the sub-scanning direction. Is generated so that the positively charged toner T can be transported along the toner transport direction TTD.

<<< Toner Transport Guide Member >>>
FIG. 5 is a plan view of the developing device 130 shown in FIG. FIG. 6 is an enlarged plan view showing the periphery of the end in the main scanning direction of the transport electrode 133a shown in FIG. FIG. 7 is a cross-sectional view taken along line AA in FIGS. 5 and 6. FIG. 8 is an enlarged plan view illustrating the counter electrode 135a illustrated in FIG. 3 in a state where the periphery of the end in the main scanning direction is seen through.

  Referring to FIG. 5, the developer transport according to the present invention is provided between both ends of the toner electric field transport body 132 in the sheet width direction (the main scanning direction) and the casing upper surface cover 131a (developing portion facing plate 131a1). A pair of toner conveyance guide members 136 are interposed as guide members.

  The toner conveyance guide member 136 is formed as a rod-like member having a longitudinal direction in the sub-scanning direction (vertical direction in FIG. 5) by a single foamed sponge as an elastic body. The length of the toner transport guide member 136 is set to a length that is sufficiently longer than the length of the developing opening 131a2 in the sub-scanning direction.

  The distance between the inner ends of the pair of toner conveyance guide members 136 in the paper width direction (the main scanning direction) (the width of the toner conveyance area TTA in FIG. 6) is determined by the photosensitive drum outer width Wp1 and the photosensitive drum effective. The pair of toner transport guide members 136 are arranged so as to be wider than the width Wp2. Here, the photosensitive drum outer width Wp1 is the width of the outer shape of the photosensitive drum 121 in the main scanning direction. The photosensitive drum effective width Wp2 is a width of a region on the photosensitive drum 121 where an electrostatic latent image can be formed (a width of the photosensitive layer 121b in FIG. 2 in the main scanning direction).

  Referring to FIGS. 6 and 7, the toner transport guide member 136 has both end portions on the toner electric field transport body 132 (toner transport surface 133d) in the paper width direction (the main scanning direction) perpendicular to the toner transport direction TTD. The upper casing upper surface cover 131a (provided so as to protrude toward the developing unit facing plate 131a1).

  Referring to FIG. 7, the bottom surface 136a of the toner transport guide member 136, which is the surface facing the toner transport surface 133d, is fixed on the toner transport surface 133d by adhesive or double-sided tape. Further, the top surface 136b which is the surface opposite to the bottom surface 136a of the toner conveyance guide member 136 and the counter wiring substrate 135 are in contact with each other with a predetermined pressure. That is, the toner transport guide member 136 includes both ends of the toner electric field transport body 132 (toner transport surface 133d) in the main scanning direction, and a counter wiring substrate 135 supported by the casing top cover 131a (developing unit counter plate 131a1). In between, it is interposed in a state elastically deformed by a predetermined pressure.

  Referring to FIGS. 6 and 7, the toner transport guide member 136 is provided on the inner side in the paper width direction (the main scanning direction) than the root portion 133a1 and the tip end portion 133a2 of the transport electrode 133a. A toner conveyance area TTA is formed by an area between the inner ends of the pair of toner conveyance guide members 136 in the sheet width direction.

  Here, the root portion 133a1 is one end portion in the paper width direction (the main scanning direction) which is the longitudinal direction of the transport electrode 133a. Further, the distal end portion 133a2 is an end portion on the opposite side to the one end portion (the root portion 133a1) in the longitudinal direction of the transport electrode 133a.

  That is, the toner conveyance guide member 136 protrudes toward the upper casing upper surface cover 131a (developing unit facing plate 131a1) on the inner side in the paper width direction (the main scanning direction) than the root portion 133a1 and the tip end portion 133a2. As a result, the range in which the toner T (see FIG. 3) is transported in the toner transport direction TTD on the toner transport surface 133d is defined as the above-described toner transport area TTA, and is further outward than the toner transport direction TTD. The toner T is configured and arranged so that the leakage of the toner T can be suppressed.

  The transport electrode power supply wiring section 137 as a power supply wiring section of the present invention is a wiring pattern for supplying power to the transport electrode 133a, and is made of a copper foil having a thickness of about several tens of micrometers. The transport electrode power supply wiring portion 137 is provided along the toner transport surface 133d.

  The transport electrode power supply wiring portion 137 includes a transport electrode power supply wiring pattern 137a, a through hole 137b, and a through hole power supply wiring pattern 137c.

  The transport electrode power supply wiring pattern 137a is provided along the sub-scanning direction on the same plane as the transport electrode 133a (on the upper surface of the transport electrode support substrate 133b). The transport electrode power supply wiring pattern 137a is integrally formed with the root portion 133a1 of every third transport electrode 133a in the array along the sub-scanning direction without a seam.

  A plurality of through holes 137b are arranged along the sub-scanning direction. Each through hole 137b is disposed between the transport electrodes 133a connected to the transport electrode power supply wiring pattern 137a.

  The through-hole power supply wiring pattern 137c extends along the sub-scanning direction on the back surface of the transport electrode support substrate 133b (the surface opposite to the upper surface on which the transport electrode 133a and the transport electrode power supply wiring pattern 137a are formed). Is provided. Each through-hole 137b is formed integrally with the root portion 133a1 of every third transport electrode 133a in the array along the sub-scanning direction. Each through hole 137b is connected to the through hole power supply wiring pattern 137c so as to penetrate the transport electrode support substrate 133b.

  As shown in FIGS. 6 and 7, the transport electrode power supply wiring portion 137 is provided outside the toner transport guide member 136 in the paper width direction (the main scanning direction).

  Further, the end portion of the counter electrode 135a and the counter electrode power supply wiring portion 138 for supplying power to the counter electrode 135a are also similar to the end portion of the transport electrode 133a and the transport electrode power supply wiring portion 137 described above. 136 is provided outside.

  Specifically, referring to FIG. 7 and FIG. 8, a root electrode 135a1, which is one end in the longitudinal direction of the counter electrode 135a, has a counter electrode power supply wiring pattern 138a and a through-hole 138b constituting the counter electrode power supply wiring portion 138. Is connected. The through holes 138b are electrically connected to each other by a through hole power supply wiring pattern 138c.

  The root portion 135a1 of the counter electrode 135a and the tip end portion 135a2 which is the other end portion on the opposite side, and the counter electrode power supply wiring portion 138 are formed in the paper width direction (the main scanning direction) of the toner transport guide member 136. Is provided outside.

<< Transfer section >>
Referring to FIG. 1 again, the transfer unit 140 faces the image bearing surface 121b1 at a position downstream of the photosensitive drum 121 in the rotation direction with respect to the position where the photosensitive drum 121 and the developing device 130 face each other. Is provided.

  The transfer unit 140 is a roller-like member, and includes a metal rotation center shaft 141 and a conductive rubber layer 142 provided around the rotation center shaft 141. The rotation center axis 141 is disposed in parallel with the main scanning direction (z-axis direction in the figure). A high voltage power source is connected to the rotation center shaft 141. The conductive rubber layer 142 is configured to exhibit conductivity or semiconductivity by kneading conductive fine particles such as carbon black in synthetic rubber.

  The transfer unit 140 is rotated counterclockwise in the drawing while a predetermined transfer voltage is applied to the drum body 121a of the photosensitive drum 121, whereby the toner T carried on the image carrying surface 121b1. Can be transferred onto the paper P.

<< paper cassette >>
The paper feed cassette 150 is disposed below the developing device 130. The paper feed cassette case 151 is a box-shaped member that constitutes the casing of the paper feed cassette 150 and is formed to open upward. The sheet feeding cassette case 151 is configured to accommodate a large number of sheet-like sheets P having a maximum A4 size (width 210 mm × length 297 mm) in a stacked state.

  A paper pressing plate 153 is disposed in the paper feed cassette case 151. The paper pressing plate 153 is supported by the paper feed cassette case 151 so that the rear end can swing along the vertical direction in the figure with the front end as the center. The rear end of the paper pressing plate 153 is urged upward by a spring (not shown).

<< Paper Conveying Section >>
In the main body casing 112, a paper transport unit 160 is accommodated. The paper transport unit 160 is configured to be able to supply the paper P to a transfer position TP where the transfer unit 140 and the image carrying surface 121b1 face each other in the closest state. The paper transport unit 160 includes a paper feed roller 161, a paper guide 163, and a paper transport guide roller 165.

  The paper feed roller 161 is composed of a rotation center axis parallel to the main scanning direction and a surrounding rubber layer. The paper feed roller 161 is disposed so as to face the most distal portion of the paper P placed on the paper pressing plate 153 in the paper feed cassette case 151 in the paper transport direction. The paper guide 163 and the paper transport guide roller 165 are configured to guide the paper P fed by the paper feed roller 161 to the transfer position TP.

<< Fixing part >>
A fixing unit 170 is accommodated in the main body casing 112. The fixing unit 170 is disposed at a position downstream of the transfer position TP in the paper transport direction. The fixing unit 170 can fix the image formed by the toner T formed on the paper P on the paper P by heating the paper P to which the toner T is adhered through the transfer position TP while applying pressure. It is configured. The fixing unit 170 includes a heating roller 172 and a pressure roller 173.

  The heating roller 172 includes a metal cylinder whose surface has been subjected to a mold release process, and a halogen lamp housed in the cylinder. The pressure roller 173 includes a metal rotation center shaft and a silicon rubber rubber layer provided around the rotation center shaft. The heating roller 172 and the pressure roller 173 are disposed so as to press each other with a predetermined pressure.

  The heating roller 172 and the pressure roller 173 are configured and arranged so that the paper P can be sent out toward the paper discharge port 112a while pressing and heating the paper P.

<Outline of image forming operation by laser printer>
Hereinafter, an outline of an image forming operation by the laser printer 100 having the above-described configuration will be described with reference to the drawings.

<< Paper feeding action >>
First, referring to FIG. 1, the paper P stacked on the paper pressing plate 153 is urged upward toward the paper feed roller 161 by the paper pressing plate 153. As a result, the uppermost sheet P stacked on the sheet pressing plate 153 comes into contact with the peripheral surface of the sheet feeding roller 161. The paper feed roller 161 is driven to rotate clockwise in the drawing, so that the leading edge of the paper P in the paper transport direction is sent toward the paper guide 163. Then, the paper P is fed to the transfer position TP by the paper guide 163 and the paper transport guide roller 165.

<< Carrying of toner image on image carrying surface >>
As described above, while the paper P is being conveyed toward the transfer position TP, an image of the toner T is carried on the image carrying surface 121b1 that is the circumferential surface of the photosensitive drum 121 as follows.

<<< Formation of electrostatic latent image >>>
First, the image carrying surface 121b1 of the photosensitive drum 121 is uniformly charged positively by the charger 123.

  Referring to FIG. 3, the image bearing surface 121b1 charged by the charger 123 is rotated to the scan position SP which is a position facing (directly facing) the scanner unit 122 by the clockwise rotation of the photosensitive drum 121 in the drawing. It moves along the sub-scanning direction. At the scan position SP, the laser beam LB modulated based on the image information is irradiated onto the image carrying surface 121b1 while being scanned along the main scanning direction. Depending on the modulation state of the laser beam LB, a portion where the positive charge on the image bearing surface 121b1 disappears is generated. As a result, an electrostatic latent image LI is formed on the image bearing surface 121b1 by an image-like distribution of positive charges.

  The electrostatic latent image LI formed on the image carrying surface 121b1 moves toward the development facing position DP by the clockwise rotation of the photosensitive drum 121 in the drawing.

<<< Charged toner transport >>>
Referring to FIG. 2, by applying a predetermined voltage (similar to that shown in FIG. 4) to the counter wiring substrate 135, a predetermined traveling wave electric field is formed on the counter wiring substrate 135. . Due to this electric field, the toner T accommodated in the bottom of the space in the developing casing 131 is conveyed toward the rear side (left side in the figure) on the counter wiring substrate 135 supported on the casing bottom plate 131b. The toner T is transported to the rear end in the space inside the developing casing 131 and to the position where the rear end of the transport wiring substrate 133 and the counter wiring substrate 135 face each other.

  The toner T between the transport wiring board 133 and the counter wiring board 135 is directed toward the development counter position DP by a traveling wave electric field generated on the transport wiring board 133 (toner transport surface 133d) and the counter wiring board 135. Are transported.

  The toner T transport operation by the counter wiring substrate 135 is the same as the toner T transport operation by the transport wiring substrate 133. Therefore, the toner T transporting operation by the transport wiring board 133 will be described in detail below.

  FIG. 9 is an enlarged side sectional view showing the periphery of the toner transport surface 133d in the transport wiring board 133 shown in FIG. In FIG. 3, the transport electrode 133a connected to the power supply circuit VA is shown as the transport electrode 133aA in FIG. The same applies to the transport electrodes 133aB to 133aD.

  Referring to FIGS. 4 and 9, at time t1 in FIG. 4, as shown in FIG. 9A, at the position between AB, which is the position between the transport electrode 133aA and the transport electrode 133aB. The electric field EF1 is formed in the direction opposite to the toner transport direction TTD (the direction opposite to x in FIG. 9). On the other hand, an electric field EF2 in the same direction as the toner transport direction TTD (the x direction in FIG. 9) is formed at the inter-CD position between the transport electrode 133aC and the transport electrode 133aD. Further, the position between BC, which is a position between the transport electrode 133aB and the transport electrode 133aC, and the position between DA, which is a position between the transport electrode 133aD and the transport electrode 133aA, are arranged in the direction along the toner transport direction TTD. An electric field is not formed.

  That is, at time t1, the positively charged toner T receives an electrostatic force in the direction opposite to the toner transport direction TTD at the position between AB. Further, at the position between BC and the position between DA, the positively charged toner T receives almost no electrostatic force in the direction along the toner transport direction TTD. Further, at the position between the CDs, the positively charged toner T receives an electrostatic force in the same direction as the toner transport direction TTD. Therefore, at time t1, the positively charged toner T is collected at the position between the DAs.

  Similarly, at time t2, the positively charged toner T is collected at the position between AB. Next, at time t3, the positively charged toner T is collected at the position between BC. As described above, the region where the toner T is collected moves in the toner transport direction TTD along the toner transport surface 133d as time passes.

  Referring to FIGS. 5 to 8, as described above, the traveling-wave-like transport voltage (see FIG. 4) is applied to the plurality of transport electrodes 133 a and the plurality of counter electrodes 135 a, so that the toner transport surface 133 d and A traveling wave electric field is formed on 135d. Thus, the toner T (see FIG. 9) is guided by the pair of toner transport guide members 136 into the toner transport area TTA on the toner transport surfaces 133d and 135d, and toward the development facing position DP (see FIG. 3). The toner is transported along the toner transport direction TTD.

<<< Development of electrostatic latent image >>>
Referring to FIG. 3, as described above, the positively charged toner T is supplied to the development facing position DP. In the vicinity of the development facing position DP, the toner T adheres to the portion on the image bearing surface 121b1 where the positive charge in the electrostatic latent image LI has disappeared. That is, the electrostatic latent image LI on the image bearing surface 121b1 of the photosensitive drum 121 is developed with the toner T. An image of the toner T is carried on the image carrying surface 121b1.

<< Transfer of toner image from image bearing surface to paper >>
Referring to FIG. 1, an image of toner T carried on the image carrying surface 121b1 of the photosensitive drum 121 as described above is transferred to the transfer position TP by rotating the image carrying surface 121b1 clockwise in the drawing. It is conveyed toward. At this transfer position TP, the image of the toner T is transferred onto the paper P from the image carrying surface 121b1.

<< Fixing / Ejecting >>
The paper P on which the image of the toner T is transferred at the transfer position TP is sent to the fixing unit 170 along the paper transport path PP. The paper P is heated while being pressed by being sandwiched between the heating roller 172 and the pressure roller 173. As a result, the image of the toner T is fixed on the surface of the paper P. Thereafter, the paper P is sent to the paper discharge port 112a and discharged onto the paper discharge tray 114 through the paper discharge port 112a.

<Operation / Effects of Configuration of Embodiment>
In the configuration of the present embodiment, the range in which the toner T is transported by the pair of toner transport guide members 136 is the range in which a traveling wave electric field along the toner transport direction TTD is well formed, that is, the toner transport surface. It is defined in the toner transport area TTA at 133d and 135d. The leakage of the toner T to the outside of the toner conveyance area TTA, that is, a portion where a good traveling wave electric field is difficult to be formed is suppressed by the pair of toner conveyance guide members 136.

  Therefore, according to the configuration of the present embodiment, smooth conveyance of the charged toner T along the toner conveyance direction TTD can be realized with a simple apparatus configuration. Therefore, the retention of the toner T in the toner conveyance path can be suppressed as much as possible by a simple device configuration.

  In the configuration of this embodiment, a counter wiring substrate 135 having a plurality of counter electrodes 135a is provided, and the toner transport guide member 136 is disposed between the toner transport surface 133d and the counter electrode 135a (counter wiring substrate 135). It is intervened.

  According to this configuration, the charged toner T can be transported more smoothly by applying a predetermined traveling-wave voltage to the plurality of transport electrodes 133a and the plurality of counter electrodes 135a.

  In the configuration of the present embodiment, the toner transport guide member 136 is formed of an elastic body, and the top surface 136b of the toner transport guide member 136 is opposed to the developing unit facing plate 131a1 in the casing upper surface cover 131a. It is in contact with the substrate 135.

  According to such a configuration, the placement of the toner T on the top surface 136b can be effectively suppressed. Further, the regulation of the transport range of the toner T as described above can be effectively performed. Therefore, according to such a configuration, the retention of the toner T in the toner conveyance path can be more effectively suppressed.

<Example of modification>
Note that, as described above, the above-described embodiments are merely examples of typical embodiments of the present invention that the applicant has considered to be the best at the time of filing of the present application. Therefore, the present invention is not limited to the above-described embodiment. Therefore, it goes without saying that various modifications can be made to the above-described embodiment within the scope not changing the essential part of the present invention.

  Hereinafter, some modifications will be illustrated. In the following description of modifications, members having the same configuration and function as those described in the above-described embodiment are denoted by the same reference numerals as those in the above-described embodiment. And about description of this member, the description in the above-mentioned embodiment shall be used in the range which is not technically consistent.

  Needless to say, the modifications are not limited to those listed below. In addition, a plurality of modified examples can be applied in a composite manner as appropriate within a technically consistent range.

  The present invention (especially, those expressed functionally and functionally in each component constituting the means for solving the problems of the present invention) is described in the above-described embodiments and the following modifications. On the basis of it, it should not be limited. Such a limited interpretation, while improperly harming the applicant's interests (rushing to file under an earlier application principle), improperly imitates the patent for the protection and use of the invention Contrary to the purpose of the law, it is not allowed.

  (1) The application target of the present invention is not limited to a monochromatic laser printer. For example, the present invention can be suitably applied to a so-called electrophotographic image forming apparatus such as a color laser printer or a monochromatic and color copying machine.

  Alternatively, the present invention can be suitably applied to an image forming apparatus of a system other than the above-described electrophotographic system (for example, an image forming apparatus of a toner jet system or an ion flow system that does not use a photoreceptor).

  (2) The configurations of the toner electric field transport body 132, the transport wiring board 133, and the counter wiring board 135 are not limited to those shown in the above embodiment.

  For example, the transport electrode 133a can be embedded in the transport electrode support substrate 133b so as not to protrude from the surface of the transport electrode support substrate 133b. Further, the transport electrode coating layer 133c can be omitted. Alternatively, the transport electrode 133 a can be formed directly on the transport substrate support member 134.

  For example, the counter electrode 135a may be embedded in the counter electrode support substrate 135b so as not to protrude from the surface of the counter electrode support substrate 135b. Further, the counter electrode coating layer 135c may be omitted. Alternatively, the counter electrode 135a can be formed directly on the inner wall surface of the developing casing 131.

  Further, the longitudinal direction of the transport electrode 133a and the counter electrode 135a may be parallel to the main scanning direction as in the above embodiment, or may intersect the main scanning direction. . The arrangement direction of the transport electrode 133a and the counter electrode 135a may be parallel to the sub-scanning direction in a plan view as in the above-described embodiment, or a direction intersecting the sub-scanning direction in a plan view. It may be.

  There are no particular limitations on the shape of the transport electrode 133a and the counter electrode 135a and the electrical connection configuration. For example, the transport electrode 133a and the counter electrode 135a may be formed in various shapes such as a V shape, an arc shape, a wave shape, and a jagged shape instead of the linear shape as in the above-described embodiment.

  The connection between the electrodes may be in various states such as every other one, every two, and not every three as in the above-described embodiment. In this case, the corresponding power supply circuit is not four types, and the phase shift of each voltage waveform can be appropriately changed to 180 °, 120 °, or the like. Further, various voltage waveforms such as a rectangular wave and a sine wave can be used.

  (3) The counter wiring substrate 135 may be omitted partially or entirely.

  (4) Referring to FIG. 2, FIG. 3, and FIG. 5, in the above-described embodiment, the photosensitive drum outer width Wp1 is narrower than the width of the developing opening 131a2 in the main scanning direction. The photosensitive drum 121 and the developing casing 131 are configured such that the image carrying surface 121b1 at the facing position DP enters the developing opening 131a2.

  The present invention is not limited to such a configuration at all. For example, the photosensitive drum outer width Wp1 and the photosensitive drum effective width Wp2 may be wider than the width of the developing opening 131a2 in the main scanning direction.

  However, according to the configuration of the above-described embodiment, the development gap (gap between the image carrying surface 121b1 and the toner conveyance surface 133d) at the development facing position DP is made as small as possible, so that finer development can be performed. Can be broken. Further, since the developing opening 131a2 is blocked by the photosensitive drum 121, the leakage of the toner T from the developing opening 131a2 can be suppressed as much as possible.

  (5) The top surface 136b of the toner conveyance guide member 136 may not be in contact with the counter wiring substrate 135. In this case, the toner transport guide member 136 is formed in a cross-sectional shape that prevents the toner T (see FIG. 9) from being placed on the top surface 136b of the toner transport guide member 136 during the toner transport operation. .

  FIG. 10 is a cross-sectional view showing the configuration of a modified example of the toner transport guide member 136 shown in FIG. Referring to FIG. 10, in this modification, the top surface 136 b of the toner conveyance guide member 136 and the counter wiring substrate 135 are separated from each other.

  Here, referring to FIG. 3, the height of the top surface 136b is determined by applying the traveling-wave-like carrying voltage as described above to the plurality of carrying electrodes 133a at portions other than the vicinity of the development facing position DP. It is set to a level that sufficiently exceeds the maximum value of the height at which the toner T conveyed while hopping the top flies in the height direction (y-axis direction in the figure) (for example, three times or more of the maximum value). In the vicinity of the development facing position DP, the toner T flies to a height that reaches the image carrying surface 121b1 through the development opening 131a2.

  11 and 12 are cross-sectional views showing the configuration of another modification of the toner conveyance guide member 136 shown in FIG.

  Referring to FIG. 11, in the present modification, the top surface 136b of the toner transport guide member 136 is formed in a slope shape so as to fall inward in the paper width direction.

  Referring to FIG. 12, in the present modification, the toner conveyance guide member 136 is formed in a bowl shape. In other words, the toner conveyance guide member 136 includes a base portion 136c and an overhang portion 136d.

  The base portion 136c is fixed on the toner transport surface 133d and is provided so as to protrude straight upward toward the counter wiring substrate 135. The overhang portion 136d is provided to extend obliquely upward from the upper end of the base portion 136c. Further, the overhang portion 136d is provided so as to fall down toward the toner transport area TTA (see FIG. 6).

  Also with the configurations of these modified examples, the conveyance range of the toner T (see FIG. 9) can be effectively defined, and the toner T (see FIG. 9) is placed on the top surface 136b of the toner conveyance guide member 136. Placement can be effectively suppressed.

  (6) When the counter wiring board 135 is also provided on the casing bottom plate 131b as in the above-described embodiment, the toner conveyance guide member 136 may be provided so as to correspond to the casing bottom plate 131b. That is, the toner conveyance guide member 136 can be formed in a substantially U shape so as to correspond to the casing upper surface cover 131a and the casing bottom plate 131b that are integrally formed in a substantially U shape.

  13 and 14 are diagrams showing the configuration of this modification. That is, FIG. 13 is a plan view seen through the counter wiring board 135 on the casing bottom plate 131b in the configuration of the modified example of the developing device 130 shown in FIG. That is, FIG. 13 corresponds to FIG. FIG. 14 is a cross-sectional view taken along line AA in FIG.

  Referring to FIGS. 13 and 14, in this modification, both ends (the root portion 135a1 and the tip portion 135a2) of the counter electrode 135a and the counter electrode power supply wiring in the counter wiring substrate 135 supported on the casing bottom plate 131b. A toner conveyance guide member 136 is provided inside the portion 138. A toner conveyance area TTA on the toner conveyance surface 135d is formed by an area between the pair of toner conveyance guide members 136.

  In this case, the height of the toner conveyance guide member 136 is set to such a height that the placement of the toner T (see FIG. 2) on the top surface 136b can be suppressed. Specifically, for example, the height of the toner transport guide member 136 is such that the toner T (see FIG. 2) flies upward from the toner transport surface 135d by the action of a traveling wave electric field generated by applying a voltage to the plurality of counter electrodes 135a. It can be set to 3 times or more of the maximum possible height.

  According to the configuration of such a modified example, a traveling wave shape is formed in the toner conveyance area TTA, which is an inner portion in the paper width direction (the main scanning direction) of the toner conveyance surface 135d that is the inner surface of the counter wiring substrate 135. This electric field can be formed satisfactorily. A region where the toner T (see FIG. 2) is transported on the toner transport surface 135d is defined in the toner transport region TTA by the toner transport guide member 136.

  Further, leakage of the toner T (see FIG. 2) to a portion of the toner transport surface 135d outside the toner transport area TTA in the paper width direction (the main scanning direction) is suppressed by the toner transport guide member 136. .

  Accordingly, the retention of the toner T on the casing bottom plate 131b at a specific portion can be more effectively suppressed.

  (7) The width of the toner transport area TTA on the toner transport surface 133d and the width of the toner transport area TTA on the toner transport surface 135d may be substantially the same as shown in FIGS. However, they may be different as shown in FIG. 11 and FIG.

  (8) In addition, what is expressed functionally and functionally in each element constituting the means for solving the problems of the present invention is a specific structure disclosed in the above-described embodiment or modification. In addition, any structure capable of realizing the action / function is included.

1 is a side sectional view showing a schematic configuration of a laser printer to which an embodiment of the present invention is applied. FIG. 2 is an enlarged side sectional view of an electrostatic latent image forming unit and a developing device shown in FIG. 1. FIG. 3 is an enlarged side cross-sectional view of a portion in the vicinity of a developing opening in the developer electric field carrier shown in FIG. 2. FIG. 4 is a graph showing a waveform of a voltage generated by the power supply circuit shown in FIG. 3. FIG. 3 is a plan view of the developing device shown in FIG. 2. FIG. 4 is an enlarged plan view showing a periphery of an end portion of a transport electrode shown in FIG. 3 in a main scanning direction in a transparent state. It is AA sectional drawing in FIG.5 and FIG.6. FIG. 4 is an enlarged plan view showing the periphery of the end portion of the counter electrode shown in FIG. 3 in the main scanning direction in a transparent state. FIG. 4 is an enlarged side cross-sectional view illustrating a periphery of a toner conveyance surface in the conveyance wiring board illustrated in FIG. 3. FIG. 8 is a cross-sectional view illustrating a configuration of a modified example of the toner conveyance guide member illustrated in FIG. 7. FIG. 8 is a cross-sectional view illustrating a configuration of another modified example of the toner conveyance guide member illustrated in FIG. 7. FIG. 8 is a cross-sectional view illustrating a configuration of another modified example of the toner conveyance guide member illustrated in FIG. 7. FIG. 5 is a plan view of a counter wiring substrate on a casing bottom plate seen through in the configuration of a modification of the developing device shown in FIG. 2. It is AA sectional drawing in FIG.

Explanation of symbols

100: Laser printer (image forming apparatus)
121 ... Photosensitive drum (electrostatic latent image carrier / developer carrier)
121b ... photosensitive member layer 121b1 ... image carrying surface (latent image forming surface / developer carrying surface)
130... Developing device (Developer supply device / Developer electric field transport device)
131... Development casing (developer housing casing)
131a ... casing upper surface cover 131a1 ... developing unit facing plate 131a2 ... developing opening (opening)
131b ... casing bottom plate 132 ... toner electric field carrier (developer carrier)
133 ... Transport wiring board 133a ... Transport electrode 133a1 ... Root portion 133a2 ... End portion 133b ... Transport electrode support substrate 133c ... Transport electrode coating layer 133d ... Toner transport surface (developer transport surface)
134 ... Conveying substrate support member 135 ... Counter wiring substrate 135a ... Counter electrode 135a1 ... Root portion 135a2 ... Tip portion 135d ... Toner transport surface 136 ... Toner transport guide member (developer transport guide member)
136a... Bottom surface 136b... Top surface 137... Transport electrode power supply wiring section (power supply wiring section)
138... Counter electrode power supply wiring portion DP... Development facing position LI... Electrostatic latent image P.
TTA: Toner transport area TTD: Toner transport direction

Claims (6)

A latent image forming surface that is formed in parallel with a predetermined main scanning direction and configured to form an electrostatic latent image by a potential distribution; and the latent image forming surface is a sub-surface orthogonal to the main scanning direction. An electrostatic latent image carrier configured to be movable along a scanning direction;
A developer supply device arranged to face the electrostatic latent image carrier and configured to supply the developer to the latent image forming surface in a charged state;
An image forming apparatus comprising:
The developer supply device includes:
A plurality of transport electrodes configured to have a longitudinal direction that intersects the sub-scanning direction and arranged in a predetermined developer transport direction along the sub-scanning direction;
A power supply wiring portion connected to a root portion which is one end portion in the longitudinal direction of the transport electrode;
The developer transport surface parallel to the main scanning direction is provided, the transport electrodes and the power supply wiring portion are provided along the developer transport surface, and the developer transport surface is connected to the electrostatic latent image carrier. The developer can be transported in the developer transport direction by a traveling-wave electric field generated on the developer transport surface when a predetermined transport voltage is applied to the plurality of transport electrodes. A developer carrier configured in
The developer transport body is provided on the developer transport surface at both ends in the width direction perpendicular to the developer transport direction, and the developer is on the developer transport surface. A pair of developer transport guide members configured to define a range transported in the transport direction;
A box-shaped member configured to cover the developer transport body and the developer transport guide member and accommodate the developer, wherein the electrostatic latent image carrier and the developer transport surface face each other. A developer containing casing in which an opening is formed at a position to be
With
The developer transport guide member is formed to be sufficiently longer than the length of the opening in the sub-scanning direction, and the tip of the transport electrode and the end opposite to the base section It protrudes toward the surface of the developer containing casing in which the opening is formed, on the inner side in the width direction than the portion, and on the surface opposite to the surface facing the developer transport surface. A certain top surface is configured and arranged so that leakage of the developer to the outside in the width direction can be suppressed more than the developer conveyance guide member by abutting the developer containing casing. An image forming apparatus. The image forming apparatus according to claim 1 .
A plurality of elements are arranged to have a longitudinal direction that intersects the sub-scanning direction, are arranged to face the developer conveying surface across a predetermined gap, and are arranged along the developer conveying direction. A counter electrode,
The image forming apparatus, wherein the developer transport guide member is interposed between the developer transport surface and the counter electrode. The image forming apparatus according to claim 1, wherein:
The image forming apparatus, wherein the developer transport guide member is made of an elastic body. The developer carrying surface is formed in parallel to a predetermined main scanning direction and configured to be able to carry the developer, and the developer carrying surface moves along a sub-scanning direction perpendicular to the main scanning direction. In a developer supply apparatus configured to be able to supply the developer in a charged state to a developer carrier configured to be capable of:
A plurality of transport electrodes configured to have a longitudinal direction that intersects the sub-scanning direction and arranged in a predetermined developer transport direction along the sub-scanning direction;
A power supply wiring portion connected to a root portion which is one end portion in the longitudinal direction of the transport electrode;
The developer transport surface is parallel to the main scanning direction, the transport electrode and the power supply wiring portion are provided along the developer transport surface, and the developer transport surface faces the developer carrier. Arranged so that the developer can be transported in the developer transport direction by a traveling wave-like electric field generated on the developer transport surface when a predetermined transport voltage is applied to the plurality of transport electrodes. A developer carrier,
The developer transport body is provided on the developer transport surface at both ends in the width direction perpendicular to the developer transport direction, and the developer is on the developer transport surface. A pair of developer transport guide members configured to define a range transported in the transport direction;
A box-shaped member configured to cover the developer transport body and the developer transport guide member and accommodate the developer, where the developer carrier and the developer transport surface face each other A developer containing casing in which an opening is formed;
With
The developer transport guide member is formed to be sufficiently longer than the length of the opening in the sub-scanning direction, and the tip of the transport electrode and the end opposite to the base section It is a surface on the inner side in the width direction with respect to the portion, protruding toward the surface where the opening of the developer containing casing is formed, and on the opposite side of the surface facing the developer transport surface. The top surface is in contact with the developer containing casing, and is configured and arranged so that leakage of the developer to the outside in the width direction can be suppressed from the developer transport guide member. A developer supply device. The developer supply device according to claim 4 ,
A plurality of elements are arranged to have a longitudinal direction that intersects the sub-scanning direction, are arranged to face the developer conveying surface across a predetermined gap, and are arranged along the developer conveying direction. A counter electrode,
The developer supply apparatus according to claim 1, wherein the developer transport guide member is interposed between the developer transport surface and the counter electrode. In the developer supply device according to claim 4 or 5 ,
The developer supply apparatus, wherein the developer transport guide member is made of an elastic body.

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