JP2005173014A - Developing apparatus, image forming apparatus and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a developing apparatus capable of increasing the electrified amount of developer held by a supply roller, and to realize an image forming apparatus and an image forming system equipped with the developing apparatus. <P>SOLUTION: The supply roller is provided with a conductive shaft part and an elastic part formed on the outer periphery of the shaft part, and regarding a contact member, a contact part contacting the elastic part has conductivity, and a potential difference generating means for generating a potential difference between the contact part and the shaft part is arranged in the developing apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

As the developing device, for example, there is a developing device having a developing roller for carrying the developer and a supply roller for holding the developer and supplying the developer to the developing roller. Further, the developing device is provided with a contact member that contacts the supply roller in order to hold the developer on the supply roller.
JP 2003-173081 A

 However, when the supply roller supplies the developer held by the contact member to the development roller, if the developer is not sufficiently held by the supply roller, the developer falls from the supply roller, and the supply roller In some cases, the amount of developer supplied to the developing roller is insufficient. Therefore, in order to reliably hold the developer on the supply roller, it is necessary to increase the charge amount of the developer held on the supply roller.

 The present invention has been made in view of such problems, and an object of the present invention is to provide a developing device capable of increasing the charge amount of the developer held by the supply roller, and such a developing device. An image forming apparatus and an image forming system.

In order to solve the above-mentioned problems, the main present invention includes a developing roller for carrying a developer, a supply roller for holding the developer and supplying the developer to the development roller, and a supply roller. A developing device having an abutting member for abutting and holding the developer on the supply roller;
The supply roller has a conductive shaft portion and an elastic portion provided radially outside the shaft portion, and the contact portion of the contact member that contacts the elastic portion is electrically conductive. And a potential difference generating means for generating a potential difference between the corresponding contact portion and the shaft portion.

 Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  According to the present invention, it is possible to provide a developing device capable of increasing the charge amount of the developer held by the supply roller, and to realize an image forming apparatus and an image forming system provided with such a developing device. Is possible.

 At least the following will be made clear by the description of the present specification and the accompanying drawings.

A developing roller for carrying the developer, a supply roller for holding the developer and supplying the developer to the developing roller, and abutting the supply roller to hold the developer on the supply roller A developing device including:
The supply roller has a conductive shaft portion and an elastic portion provided radially outside the shaft portion, and the contact portion of the contact member that contacts the elastic portion is electrically conductive. And a potential difference generating means for generating a potential difference between the corresponding contact portion and the shaft portion.
According to such a developing device, due to the potential difference generated between the contact portion and the shaft portion, the charge amount of the developer that is between the contact portion and the elastic portion and is held by the supply roller is increased. It becomes possible to make it.

In the developing device, a voltage may be applied to the shaft portion, and the contact portion may be grounded.
According to such a developing device, a potential difference can be easily generated between the contact portion and the shaft portion.

In the developing device, a voltage obtained by superimposing an AC voltage on a DC voltage may be applied to the shaft portion.
According to such a developing device, due to the potential difference generated between the contact portion and the shaft portion due to the voltage obtained by superimposing the DC voltage on the AC voltage, between the surface of the elastic portion and the surface of the contact member, When the charged developer vibrates, the charge amount of the developer held on the supply roller can be further increased.

The developing device may further include a power source for applying a voltage to the developing roller, and the power source may apply a voltage to the shaft portion.
According to such a developing device, it is possible to apply a voltage to the developing roller with a single power source and to apply a voltage to the shaft portion to generate a potential difference between the contact portion and the shaft portion. Become.

In addition, the developing device includes a charging member that contacts the developing roller and negatively charges the developer, and the latent image carried on the image carrier by the negatively charged developer carried on the developing roller. The image may be developed.
In the developing device, the developer may be negatively charged when contacting the contact portion, and the contact portion may hold the negatively charged developer on the supply roller.
According to such a developing device, due to the potential difference generated between the contact portion and the shaft portion, the negative charge amount of the developer that is between the contact portion and the elastic portion and is held by the supply roller is reduced. It can be increased.

In the developing device, the supply roller is in contact with the development roller, and the supply roller is in contact with the supply roller and the development roller from a contact position between the contact member and the supply roller. The developer may be transported to a position, and the developing roller may transport the developer from a contact position between the supply roller and the development roller to a contact position between the development roller and the charging member. Good.
When the supply roller or the development roller conveys the developer, the developer falls from the supply roller or the development roller due to the action of gravity or the like, and the amount of the developer conveyed by the supply roller or the development roller may decrease. is there. Therefore, when the negative charge amount of the developer held on the supply roller is increased due to the potential difference generated between the contact portion and the shaft portion, the developer is difficult to drop from the supply roller and the development roller. It is possible to prevent the amount of developer transported by the supply roller and the developing roller from decreasing.

In the developing device, the contact position between the contact member and the supply roller is located below the contact position between the supply roller and the development roller, and the contact between the development roller and the charging member is low. The contact position may be located below the contact position between the supply roller and the developing roller, and a gap may be provided between the contact member and the charging member.
If there is a gap between the contact member and the charging member, the developer dropped from the supply roller and the developing roller may further drop through this gap, and the developer transport amount by the supply roller and the development roller May decrease further. Therefore, when the negative charge amount of the developer held on the supply roller increases due to the potential difference generated between the contact portion and the shaft portion, the transport amount of the developer by the supply roller and the development roller decreases. The effect of preventing this is exhibited more effectively.

In such a developing device, the developer may be non-magnetic.
When the developer is non-magnetic, the amount of developer transported by the supply roller and the developing roller may be smaller than when the developer is magnetic. Therefore, when the negative charge amount of the developer held on the supply roller increases due to the potential difference generated between the contact portion and the shaft portion, the transport amount of the developer by the supply roller and the development roller decreases. The effect of preventing this is exhibited more effectively.

In the developing device, the rotation direction of the supply roller may be the same as the rotation direction of the developing roller.
When the rotation direction of the supply roller is the same as the rotation direction of the developing roller, the developer is frictionally charged when the developer held on the supply roller is supplied to be rubbed against the developing roller. Therefore, the charge amount of the developer carried on the developing roller is increased, and the developer is reliably carried on the developing roller. Therefore, it is possible to more effectively prevent a decrease in the developer carrying amount by the developing roller. Become.

In the developing device, the elastic portion may be formed of urethane foam, and the elastic portion may have conductivity.
Even in the developing device having such a configuration, the charge amount of the developer held by the supply roller is increased between the contact portion and the elastic portion due to the potential difference generated between the contact portion and the shaft portion. It becomes possible to make it.

In addition, the developing device includes a storage unit for storing the developer, and a transport member that is provided in the storage unit and transports the developer stored in the storage unit to the contact member. The contact member may store the developer transported by the transport member, and the supply roller may supply the developer stored in the contact member to the developing roller.
Even in the developing device having such a configuration, the charge amount of the developer held by the supply roller is increased between the contact portion and the elastic portion due to the potential difference generated between the contact portion and the shaft portion. It becomes possible to make it.

In the developing device, the contact member may be a member having conductivity and different from the member constituting the housing portion.
In the case where the contact member has conductivity and is a member different from the member constituting the housing portion, the contact member having conductivity can be easily manufactured.

Further, a developing roller for carrying the developer, a supply roller for holding the developer and supplying the developer to the developing roller, and abutting the supply roller to hold the developer on the supply roller A developing device having a contact member for
The supply roller has a conductive shaft portion and an elastic portion provided radially outside the shaft portion, and the contact portion of the contact member that contacts the elastic portion is electrically conductive. Provided with a potential difference generating means for generating a potential difference between the corresponding contact portion and the shaft portion,
A voltage is applied to the shaft portion, the contact portion is grounded,
A voltage obtained by superimposing an AC voltage on a DC voltage is applied to the shaft part,
A power source for applying a voltage to the developing roller; the power source applies a voltage to the shaft portion;
A charging member that contacts the developing roller and negatively charges the developer, and is carried on the image carrier by the negatively charged developer carried on the developing roller,
When the developer contacts the contact portion, the developer is negatively charged, and the contact portion holds the negatively charged developer on the supply roller,
The supply roller contacts the developing roller, and the supply roller conveys the developer from a contact position between the contact member and the supply roller to a contact position between the supply roller and the development roller. The developing roller conveys the developer from a contact position between the supply roller and the development roller to a contact position between the development roller and the charging member,
The contact position between the contact member and the supply roller is located below the contact position between the supply roller and the developing roller, and the contact position between the developing roller and the charging member is the supply roller. And a position below the contact position with the developing roller, a gap is provided between the contact member and the charging member,
The developer is non-magnetic,
The rotation direction of the supply roller is the same direction as the rotation direction of the developing roller,
The elastic part is made of urethane foam, the elastic part has conductivity,
A housing portion for housing the developer, and a transport member provided in the housing portion for transporting the developer housed in the housing portion to the contact member, wherein the contact member is The developer transported by the transport member is stored, and the supply roller supplies the developer stored in the contact member to the developing roller.
The developing device characterized in that the abutting member is conductive and is a member different from the member constituting the housing portion can be realized.

Further, the developing roller for holding the developer and the developer are held, the supply roller for supplying the developer to the developing roller and the supply roller are brought into contact with the supply roller, and the developer is held by the supply roller An image forming apparatus comprising: a developing device having a contact member;
The supply roller has a conductive shaft portion and an elastic portion provided radially outside the shaft portion, and the contact portion of the contact member that contacts the elastic portion is electrically conductive. The image forming apparatus is characterized in that potential difference generating means for generating a potential difference is provided between the corresponding contact portion and the shaft portion.
According to such an image forming apparatus, it is possible to realize an image forming apparatus superior to the conventional one by providing the developing apparatus capable of increasing the charge amount of the developer held by the supply roller. Become.

Further, a computer main body, a developing roller connected to the computer main body for carrying the developer, a supply roller for holding the developer and supplying the developer to the developing roller, and the supply roller A developing device having a contact member for holding the developer on the supply roller.
The supply roller has a conductive shaft portion and an elastic portion provided radially outside the shaft portion, and the contact portion of the contact member that contacts the elastic portion is electrically conductive. The image forming system is characterized in that a potential difference generating means for generating a potential difference between the corresponding contact portion and the shaft portion is provided.
According to such an image forming system, it is possible to realize an image forming system superior to the conventional one by including a developing device capable of increasing the charge amount of the developer held by the supply roller. Become.

=== Overview of Image Forming Apparatus (Laser Beam Printer) ===
An outline of a laser beam printer (hereinafter referred to as a printer) 1 as an example of an image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing main components constituting the printer 1. In FIG. 1, the vertical direction is indicated by arrows. For example, the paper discharge tray 5 is disposed at the top of the printer 1, and the paper feed unit 50 is disposed at the bottom of the printer 1. .

<Example of Overall Configuration of Printer 1>
As shown in FIG. 1, the printer 1 according to the present embodiment includes a housing 3, a paper discharge tray 5 formed on the upper portion of the housing 3, and a door body 7 that can be opened and closed on the front surface of the housing. Have. Further, an image forming unit 20, a transfer belt unit 30, an exposure unit 10, and a paper feed unit 50 are provided in the housing 3, and a paper transport unit 60 is provided in the door body 7.

The image forming unit 20 includes four image forming stations 21 in which four developing devices that store different color toners can be set. The four image forming stations 21 are for yellow, magenta, cyan, and black developing devices, and these are distinguished by reference numerals 21Y, 21M, 21C, and 21K in the drawing.
Each image forming station 21Y (21M, 21C, 21K) is provided around a photosensitive drum 23Y (23M, 23C, 23K), which is an example of an image carrier, and a photosensitive drum 23Y (23M, 23C, 23K). A charging unit 25Y (25M, 25C, 25K) and a developing device 100Y (100M, 100C, 100K) are included. For example, the image forming station 21Y includes a photosensitive drum 23Y, a charging unit 25Y, and a developing device 100Y.
The photosensitive drum 23Y (23M, 23C, 23K) has a cylindrical conductive substrate and a photosensitive layer formed on the outer peripheral surface thereof, and is rotatable around a central axis. In the present embodiment, It rotates clockwise as indicated by the arrow in FIG.
The charging means 25Y (25M, 25C, 25K) is a device for charging the photosensitive drum 23Y (23M, 23C, 23K).
The developing device 100Y (100M, 100C, 100K) is a device for developing the latent image formed on the photosensitive drum 23Y (23M, 23C, 23K) using toner T, which is an example of a developer. Details of the developing device 100Y (100M, 100C, 100K) will be described later.

  The transfer belt unit 30 includes an intermediate transfer belt 37, primary transfer rollers 43 </ b> Y, 43 </ b> M, 43 </ b> C, and 43 </ b> K, and a cleaning unit 41 that contacts the surface of the intermediate transfer belt 37. The transfer belt unit 30 includes a driving roller 31 that is rotationally driven by a driving source (not shown), a driven roller 33 that is provided obliquely above the driving roller 31, and a tension roller 35.

The drive roller 31 also serves as a backup roller for the secondary transfer roller 45. Further, a rubber layer having a thickness of about 3 mm and a volume resistivity of 10 ⁵ Ω · cm or less is formed on the peripheral surface of the drive roller 31, and secondary transfer is performed by grounding through a metal shaft. A conductive path of the secondary transfer bias supplied via the roller 45 is configured.
The driven roller 33 also functions as a backup roller for the cleaning means 41.
The tension roller 35 can control the tension of the intermediate transfer belt 37, the curvature of the arch, and the like by adjusting the position.
The intermediate transfer belt 37 is stretched between the driving roller 31, the driven roller 33, and the tension roller 35, and is driven to circulate in the direction X of the arrow in FIG.
The driven roller 33, the tension roller 35, and the intermediate transfer belt 37 are arranged side by side so as to incline with respect to the drive roller 31, so that when the intermediate transfer belt 37 is driven, the belt conveyance direction X is downward. The belt surface 37A is positioned on the lower side, and the belt surface 37B with the conveying direction facing upward is positioned on the upper side. The photosensitive drums 23Y, 23M, 23C, and 23K are in pressure contact with the belt surface 37A along the arched line.

In the exposure unit 10, a scanner unit 11 including a polygon mirror motor 11A and a polygon mirror 11B is vertically arranged on the bottom. In addition, a single f-θ lens 13 and a reflection mirror 15 are provided in the optical path B, and the scanning optical paths of the respective colors are not parallel to the photosensitive drums 3Y, 23M, 23C, and 23K above the reflection mirror 15, respectively. A plurality of folding mirrors 17 are provided so as to be folded. The exposure unit 10 is provided in a space obliquely below the image forming unit 20.
In the exposure unit 10, an image signal corresponding to each color is emitted from the polygon mirror 11 </ b> B with a laser beam modulated and formed based on a common data clock frequency, and passes through the f-θ lens 13, the reflection mirror 15, and the folding mirror 17. The photosensitive drums 23Y, 23M, 23C, and 23K of the image forming stations 21Y, 21M, 21C, and 21K are irradiated to form latent images.

The paper feed unit 50 includes a paper feed cassette 51 in which the media P are stacked, and a pickup roller 53 that feeds the media P from the paper feed cassette 51 one by one. The paper feed unit 50 is provided below the exposure unit 10.
The paper transport unit 60 includes a gate roller pair 61 that defines the timing of feeding the medium P to the secondary transfer unit, a secondary transfer roller 45 that is pressed against the drive roller 31 and the intermediate transfer belt 37, and a fixing unit 63. , A paper discharge roller pair 65 and a duplex printing conveyance path 67.

  The fixing means 63 includes a rotatable fixing roller pair 63A having a heating element such as a halogen heater incorporated in at least one side, and at least one roller of the fixing roller pair 63A is pressed to the other side so as to be secondary to the sheet material. Pressing means for pressing the transferred secondary image against the medium P. The secondary image secondarily transferred to the medium P is fixed to the medium P at a predetermined temperature at the nip portion formed by the fixing roller pair 63A.

  As shown in FIG. 2, the control unit 80 includes a main controller 81 and a unit controller 83. An image signal is input to the main controller 81, and the unit controller 83 responds to a command based on the image signal. The unit is controlled to form an image.

<Operation of Printer 1>
Next, the operation of the printer 1 configured as described above will be described with reference to other components.
First, when an image signal and a control signal from a host computer (not shown) are input to the main controller 81 of the printer 1 via the interface (I / F) 85, the unit controller 83 based on a command from the main controller 81 The photosensitive drums 23Y, 23M, 23C, and 23K, the developing rollers 100Y, 100M, 100C, and 100K, which will be described later, and the intermediate transfer belt 37 are rotated by the control.

The photosensitive drums 23Y, 23M, 23C, and 23K are charged by the charging units 25Y, 25M, 25C, and 25K at the charging positions while rotating. The charged areas of the photosensitive drums 23Y, 23M, 23C, and 23K reach the exposure position as the photosensitive drums 23Y, 23M, 23C, and 23K rotate, and the exposure unit 10 performs yellow Y, magenta M, cyan C, and black. A latent image corresponding to K image information is formed in the area.
The latent images formed on the photosensitive drums 23Y, 23M, 23C, and 23K reach the developing position as the photosensitive drums 23Y, 23M, 23C, and 23K rotate, and are developed by the developing devices 100Y, 100M, 100C, and 100K. . As a result, toner images are formed on the photosensitive drums 23Y, 23M, 23C, and 23K.
The toner images formed on the photosensitive drums 23Y, 23M, 23C, and 23K reach the primary transfer position as the photosensitive drums 23Y, 23M, 23C, and 23K rotate, and are transferred by the primary transfer rollers 43Y, 43M, 43C, and 43K. The image is transferred to the intermediate transfer belt 37. At this time, a primary transfer voltage having a polarity opposite to the charging polarity of the toner T is applied to the primary transfer rollers 43Y, 43M, 43C, and 43K. As a result, the four color toner images formed on the respective photosensitive drums 23Y, 23M, 23C, and 23K are transferred to overlap the intermediate transfer belt 37, and a full color toner image is formed on the intermediate transfer belt 37. .

The full color toner image formed on the intermediate transfer belt 37 reaches the secondary transfer position as the intermediate transfer belt 37 rotates, and is transferred to the medium P by the secondary transfer roller 45. The medium P is conveyed from the paper feed cassette 51 to the secondary transfer roller 45 through the pickup roller 53 and the gate roller pair 61. When performing the transfer operation, the secondary transfer roller 45 is pressed against the intermediate transfer belt 37 and a secondary transfer voltage is applied.
The full-color toner image transferred to the medium P is heated and pressed by the fixing roller pair 63A and fused to the medium. On the other hand, the toner T remaining on the intermediate transfer belt 37 after the secondary transfer is scraped off by the cleaning blade 41A.
The medium on which the full-color toner image is fused is transported to the paper discharge tray 5 via the paper discharge roller pair 65 when double-sided printing is not performed, and is transported for double-sided printing when double-sided printing is performed. It is conveyed toward the path 67.

=== Overview of Control Unit ===
Next, the configuration of the control unit 80 will be described with reference to FIG. The main controller 81 of the control unit 80 is connected to a host computer via an interface 85 and includes an image memory 87 for storing an image signal input from the host computer.
The unit controller 83 is electrically connected to each unit (image forming unit 20, transfer belt unit 30, exposure unit 10, paper feed unit 50, paper transport unit 60) of the apparatus main body, and receives signals from sensors included in them. By receiving the signal, each unit is controlled based on a signal input from the main controller 81 while detecting the state of each unit.

=== Overview of Developing Device ===
Next, the outline of the developing device will be described with reference to FIG. FIG. 3 is a cross-sectional view showing main components of the developing device 100Y.
As in FIG. 1, FIG. 3 also shows the vertical direction in FIG. 3. For example, the central axis of the developing roller 140 is above the central axis of the photosensitive drum 23 </ b> Y.

<Example of overall configuration of developing device>
The developing device 100Y (100M, 100C, 100K) is set and used in each image forming station 21Y (21M, 21C, 21K). Since the configurations of the developing devices 100Y, 100M, 100C, and 100K are basically the same, the configuration of the developing device 100Y will be described with reference to FIG.

The developing device 100Y includes a housing 110. In the housing 110, a developing roller 140, a supply roller 130, a regulating blade 150 that is an example of a charging member, a seal member 160, a toner storage unit 120 that is an example of a storage unit, and an example of a transport member An agitator 170 and a toner guide member 180 which is an example of a contact member.
In order to develop the latent image carried on the photosensitive drum 23Y with the toner T, the developing roller 140 carries the toner T and conveys it to a development position facing the photosensitive drum 23Y. The developing roller 140 is made of aluminum, stainless steel, iron, or the like, and is subjected to nickel plating, chrome plating, or the like, and sand blasting or the like on the toner carrying area as necessary.
The developing roller 140 is rotatable about the central axis, and rotates in a direction (counterclockwise in FIG. 3) opposite to the rotation direction of the photosensitive drum 23Y (clockwise in FIG. 3). The central axis is above the central axis of the photosensitive drum 23Y.

  As shown in FIG. 3, there is a gap between the developing roller 140 and the photosensitive drum 23Y. That is, the developing device 100Y develops the latent image formed on the photosensitive drum 23Y in a non-contact state. Further, a developing bias in which an AC voltage is superimposed on a DC voltage is applied to the developing roller 140 from a developing bias power source 210 (see FIG. 4). Therefore, when developing the latent image formed on the photosensitive drum 23Y, an alternating electric field is formed between the developing roller 140 and the photosensitive drum 23Y.

  The supply roller 130 supplies the developing roller 140 with the toner T stored in a temporary storage unit 189 formed between a toner guide member 180 (described later) and the supply roller 130. The supply roller 130 includes a cored bar 130A that is an example of a conductive shaft part, and an elastic part 130B that is provided on the radially outer side of the cored bar 130A.

The elastic portion 130B is formed of urethane foam and has conductivity. Further, the surface of the elastic portion 130B has 70 to 100 cells (dents) per inch and holds the toner T.
The supply roller 130 is in contact with the developing roller 140 in a state where the elastic portion 130B is elastically deformed. The amount of biting of the elastic portion 130B with respect to the developing roller 140 is 0.5 mm.
Further, the work function of the elastic portion 130B is smaller than the work function of the toner T, and when the toner T comes into contact with the elastic portion 130B, the toner T is negatively charged.
The supply roller 130 is rotatable about the central axis, and rotates in the same direction (counterclockwise in FIG. 3) as the rotation direction of the developing roller 140 (counterclockwise in FIG. 3). As a result, the toner T is frictionally charged in the vicinity of the contact position H2 between the supply roller 130 and the developing roller 140. The central axis of the supply roller 130 is above the central axis of the developing roller 140.

The regulating blade 150 regulates the layer thickness of the toner T carried on the developing roller 140 and gives a negative charge to the toner T carried on the developing roller 140. The regulating blade 150 includes a rubber part 151 that is abutted along the axial direction of the developing roller 140 and a support part 152 that supports the rubber part 151.
The rubber part 151 is made of silicon rubber, urethane rubber or the like, and the support part 152 has a function of urging the rubber part 151 toward the developing roller 140, so that it is a sheet-like thin plate having a spring property such as phosphor bronze or stainless steel. Is used. One end of the support portion 152 is fixed to the housing 110.
The end of the rubber portion 151 of the regulating blade 150 opposite to the side fixed to the housing 110, that is, the tip is not in contact with the developing roller 140, and a portion away from the tip by a predetermined distance is The developing roller 140 is in contact with the width. That is, the rubber part 151 of the regulating blade 150 is not in contact with the developing roller 140 at the edge, but is in contact with the belly.

Further, the regulating blade 150 is arranged so that the tip thereof faces the upstream side in the rotation direction of the developing roller 140, and is in a so-called counter contact. The contact position H3 between the regulating blade 150 and the developing roller 140 is below the contact position H2 between the supply roller 130 and the developing roller 140 and below the central axis of the developing roller 140.
Further, an elastic member 153 is provided on the side of the regulating blade 150 opposite to the developing roller 140 side. Due to the action of the support portion 152 and the elastic member 153, the rubber portion 151 is always pressed uniformly in the longitudinal direction of the developing roller 140, and an excess portion of the toner T adhering to the peripheral surface of the developing roller 140 is scraped off. As a result, a certain amount of toner T is carried on the peripheral surface of the developing roller 140. The toner T thus scraped off naturally falls and is mixed into the toner T in the toner storage unit 120.

  The seal member 160 has one end fixed to the housing 110 and the other end in contact with the developing roller 140. The seal member 160 collects the toner T on the developing roller 140 that has passed through the developing position without being scraped off, and prevents the toner T in the developing device 100Y from leaking out of the device. The seal member 160 is a member made of a polyethylene film or the like. The contact position at which the seal member 160 contacts the developing roller 140 is above the central axis of the developing roller 140.

The toner storage unit 120 stores toner T for developing the latent image carried on the photosensitive drum 23Y. As shown in FIG. 3, the toner storage unit 120 is formed in a cylindrical shape. In addition, the toner storage unit 120 forms a part of the housing 110 and is formed of resin or the like.
An agitator 170 is provided in the toner storage unit 120. The agitator 170 includes two arm members 173 that extend in opposite directions around a central axis 171, and each arm member 173 is set to a dimension that is slightly shorter than the diameter of a circle in the cross section of the toner storage unit 120.

From the tip of each arm member 173, a stirring fin 175 extends in the opposite direction (counterclockwise in FIG. 3) to the rotational direction of the agitator 170 (clockwise in FIG. 3). The stirring fin 175 is made of a flexible member, and the tip side thereof is in pressure contact with the inner peripheral surface of the cylindrical toner container 120 by an elastic force resulting from the flexibility.
Further, the agitator 170 rotates around the central shaft 171 in the direction (clockwise in FIG. 3) opposite to the rotation direction of the supply roller 130 (counterclockwise in FIG. 3). The central axis is below the central axis of the supply roller 130 and below the central axis of the developing roller 140.

 When the agitator 170 having such a configuration rotates, the toner T present in the region 177 between the inner peripheral surface of the toner storage unit 120 and the stirring fin 175 is scraped up by the stirring fin 175 so as to be described later. It can be conveyed onto the member 180. Further, the agitator 170 has a function of stirring the toner T stored in the toner storage unit 120 by rotating about the central shaft 171.

Note that the toner T described above is non-magnetic. Therefore, unlike magnetic toner, the toner is not held on the supply roller 130 or the like by magnetic force. In addition, non-magnetic toner is less easily charged than magnetic toner.
The toner T is a polymerization toner having a good circularity.

<Configuration of toner guide member>
The toner guide member 180 stores the toner T conveyed by the stirring fin 175, and holds the stored toner T on the supply roller 130 that is in contact therewith. The toner guide member 180 includes a scraper 181, a flat conveyance unit 183, a bending unit 184, and a contact unit 185.

The scraper 181 is provided at an end portion on the side away from the supply roller 130, and is formed at an acute angle to scrape off the toner T conveyed by the stirring fin 175. The flat conveying unit 183 is formed in a planar manner with the upper surface side inclined more than the repose angle of the toner T on the supply roller 130 side than the scraper 181.
The curved portion 184 is formed on the downstream side of the flat conveyance portion 183. Further, a primary storage portion 189 of the toner T whose cross section narrows in a wedge shape is formed between the curved portion 184 and the peripheral surface of the supply roller 130. Here, the wedge-shaped cross section means that the entrance side is relatively large and becomes narrower in the traveling direction of the toner T.
The contact portion 185 is in contact with the peripheral surface of the elastic portion 130 </ b> B of the supply roller 130 on the downstream side of the curved portion 184. The amount of biting into the contact portion 185 of the elastic portion 130B is 0.2 mm, and the biting width is 3.5 mm.

  The contact position H1 between the toner guide member 180 and the supply roller 130 is located below the contact position H2 between the supply roller 130 and the developing roller 140. Further, a gap A is provided between the toner guide member 180 and the regulating blade 150. The toner T scraped off from the developing roller 140 by the rubber part 151 passes through the gap A and is returned to the toner containing part 120.

In the toner guide member 180 having such a shape, after the toner T conveyed by the stirring fin 175 is scraped off by the scraper 181, the toner T extends along the flat conveying portion 183 in the width direction thereof and the inclination thereof. Gravity drops at a uniform speed at any point in the direction, and are temporarily stored in the toner temporary storage unit 189.
In the temporary toner storage portion 189 that narrows in a wedge shape, as the toner T advances to a narrow region, the pressure contact force against the peripheral surface of the supply roller 130 gradually increases, and therefore the toner T is applied to the peripheral surface of the supply roller 130. Is pressed, and the toner T is easily held on the peripheral surface. When the toner T is pushed out beyond the contact portion 185, the toner T passes through the gap A and falls into the toner guide space portion 192 and is guided directly or to the toner guide surface 190. The toner is returned to the toner container 120.

In addition, the toner guide member 180 has conductivity. Note that the term “conductivity” refers to a property of having resistance and conducting electricity. The toner guide member 180 includes, for example, a conductive resin, a conductive plastic sheet (polyolefin-based, polyester-based, fluorine-based), a material imparted with conductivity by adding conductive powder such as carbon black to rubber, aluminum, It is formed by SECC, SPCC + nickel plating, or the like.
Further, the toner guide member 180 is a member different from the members constituting the toner storage unit 120. Therefore, it is possible to form the toner storage unit 120 with a non-conductive member and the toner guide member 180 with a conductive member.

<About potential difference generating means>
A potential difference generating means for generating a potential difference between the contact portion 185 and the core metal 130A of the supply roller 130 will be described with reference to FIG. FIG. 4 is a schematic diagram for explaining the potential difference generating means.

As shown in FIG. 4, the developing bias power supply 210 applies a voltage to the developing roller 140 and the core metal 130 </ b> A of the supply roller 130. The developing bias power supply 210 includes a DC power supply 210A for applying a DC voltage and an AC power supply 210B for applying an AC voltage, and a voltage obtained by superimposing the AC voltage on the DC voltage on a core metal 130A. Is applied.
Further, the voltage applied from the developing bias power supply 210 to the core metal 130A is the same voltage as the developing bias applied from the developing bias power supply 210 to the developing roller 130.

On the other hand, the contact portion 185 of the toner guide member 180 is grounded (earth) 220 as shown in FIG. For this reason, when a voltage is applied from the developing bias power supply 210 to the cored bar 130A while the abutting part 185 is grounded, a potential difference is generated between the abutting part 185 and the cored bar 130A.
An electric field is formed between the contact portion 185 and the elastic portion 130B due to the potential difference generated between the contact portion 185 and the core metal 130A. For example, when the potential of the contact portion 185 is higher than the potential of the core metal 130A, an electric field is formed from the contact portion 185 side toward the elastic portion 130B side, and the negatively charged toner T and electrons are From the low elastic part 130B side to the high potential contact part 185 side.

The voltage value of the DC power supply 210A is, for example, −200V or more and −350V or less. The voltage value of AC power supply 210B is 1.1 kV or more and 1.5 kV or less, for example. Therefore, the potential of the contact portion 185 becomes higher than the potential of the cored bar 130A or the potential of the cored bar 130A becomes higher than the potential of the contacted portion 185 depending on the value of the AC voltage applied from the developing bias power supply 210. Or
However, when the voltage is applied to the cored bar 130A, the potential of the contact portion 185 is often higher than the potential of the cored bar 130A based on the value of the DC voltage and the value of the AC voltage. Therefore, the electric field from the contact part 185 side toward the elastic part 130B side is formed for a longer time than the electric field from the elastic part 130B side toward the contact part 185 side.

As described above, the potential difference generating means refers to a means for generating a potential difference between the metal core 130A and the contact portion 185. The potential difference generating means in the present embodiment includes the developing bias power source 210 and the contact portion 185. Of the earth 220. Then, when the developing bias power supply 210 applies a voltage to the cored bar 130A in a state where the contacted part 185 is grounded, a potential difference is generated between the cored bar 130A and the contacted part 185.
The potential difference generating means is not limited to this, and may be in any form other than the above as long as a potential difference is generated between the core metal 130A and the contact portion 185.

<Operation of developing device>
In the developing device 100 </ b> Y configured as described above, as the agitator 170 rotates, the agitation fins 175 transport the toner T onto the toner guide member 180 so as to scoop up the toner T present in the region 177.
The toner T conveyed onto the toner guide member 180 by the stirring fin 175 is temporarily stored in the temporary storage unit 189. The toner T stored in the temporary storage unit 189 is negatively charged when coming into contact with the elastic part 130B or the contact part 185. The negatively charged toner T is held on the supply roller 130 by the contact portion 185.

  The toner T held on the supply roller 130 is conveyed by the rotation of the supply roller 130 from the contact position H1 between the toner guide member 180 and the supply roller 130 to the contact position H2 between the supply roller 130 and the developing roller 140. Is done. Then, in the vicinity of the contact position H2, the toner T moves from the supply roller 130 to the developing roller 140, and the developing roller 140 carries the toner T. The toner T carried on the developing roller 140 is transported from the contact position H2 between the supply roller 130 and the development roller 140 to the contact position H3 between the development roller 140 and the regulating blade 150 by the rotation of the development roller 140. Is done.

  When the toner T that has reached the contact position H3 by the rotation of the developing roller 140 passes through the contact position H3, a negative charge is applied to the toner T by the restriction blade 150 and the layer thickness is restricted. The negatively charged toner T on the developing roller 140 whose layer thickness is regulated reaches the developing position facing the photosensitive drum 23Y by further rotation of the developing roller 140, and on the photosensitive drum 23Y under an alternating electric field at the developing position. The latent image formed in (1) is subjected to development.

On the other hand, the toner T scraped off by the regulating blade 150 passes through the gap A and falls into the toner guide space portion 192 and is guided directly or by the toner guide surface 190 and returned to the toner storage portion 120.
Further, by further rotation of the developing roller 140, the toner T on the developing roller 140 that has passed the developing position passes through the seal member 160 and is collected in the developing device 100Y without being scraped off.

=== About work function ===
The work function (Φ) of a substance is known as the energy required to extract electrons from the substance. The smaller the work function, the easier it is to emit electrons, and the larger the work function, the harder it is to emit electrons. Therefore, when a substance having a small work function is brought into contact with a substance having a small work function, the substance having a small work function is positively charged, and the substance having a large work function is negatively charged.

The work function is measured by the following measurement method, and is quantified as energy (eV) for extracting electrons from the material. The work function includes a toner composed of various materials and various members in the image forming apparatus. The chargeability by contact can be evaluated.
The work function (Φ) is measured using a surface analyzer (AC-2, low energy electronic counting method manufactured by Riken Keiki Co., Ltd.). In the present invention, in the apparatus, a deuterium lamp is used, the irradiation light quantity is set to 500 nW, monochromatic light is selected by a spectroscope, the irradiation area is set to 4 mm square, and the energy scanning range is 3.4 to 6. The sample is irradiated at 2 eV and at a measurement time of 10 sec / 1 place. It is obtained by detecting photoelectrons emitted from the sample surface, and the work function is measured with a repeatability (standard deviation) of 0.02 eV. In addition, as a measurement environment for ensuring data reproducibility, a 24-hour standing product is used as a measurement sample under the conditions of operating temperature and humidity of 25 ° C. and 55% RH.
The work function of the toner T measured by the surface analyzer is 5.48 eV for yellow toner, 5.52 eV for magenta toner, 5.35 eV for cyan toner, and 5.46 eV for black toner.

The work function of the contact portion 185 of the toner guide member 180 is 4.9 eV. This value is smaller than the work function of the toner T. For this reason, when the toner T comes into contact with the contact portion 185, electrons move from the contact portion 185 to the toner T, so that the toner T is negatively charged.
The work function of the elastic portion 130B is 5.1 to 5.2. This value is smaller than the work function of the above four color toners. Therefore, when the toner T comes into contact with the elastic portion 130B, electrons move from the elastic portion 130B to the toner T, so that the toner T is negatively charged.

=== Regarding the Charge Amount of Developer Held on the Supply Roller ===
When the supply roller 130 supplies the toner held by the toner guide member 180 to the developing roller 140, if the toner is not sufficiently held by the supply roller 130, the toner falls from the supply roller 130 and is supplied. The amount of toner supplied to the developing roller 140 by the roller 130 may be insufficient.

  Further, when a supply amount of toner to the developing roller 140 by the supply roller 130 is insufficient, if a solid image having a high density is continuously formed on the medium, the density of the image formed on the medium becomes a desired image density. May be lower. This is because the supply amount of the toner T that the supply roller 130 supplies to the development roller 140 is smaller than the consumption amount of the toner on the development roller 140 that is consumed when continuously forming a high-density solid image on the medium. is there.

  Accordingly, in order to solve the shortage of the supply amount of the toner T to the developing roller 140 by the supply roller 130, it is necessary to securely hold the toner T on the supply roller 130, and the toner T held on the supply roller 130. It is effective to increase the charge amount. This is because when the charge amount of the toner is increased, the toner T is reliably held on the supply roller 130 by an attractive force (for example, a mirror image force) between the supply roller 130 and the charged toner T.

  Therefore, in the present embodiment, the supply roller 130 has a conductive metal core 130A and an elastic portion 130B provided on the outer side in the radial direction of the metal core 130A. The contact portion 185 that contacts the portion 130B has conductivity, and is provided with a potential difference generating means (see FIG. 4) that generates a potential difference between the contact portion 185 and the cored bar 130A.

  In this case, the charge amount of the toner T held between the contact portion 185 and the elastic portion 130B and held by the supply roller 130 due to the potential difference generated between the contact portion 185 and the core metal 130A by the potential difference generating means. Can be increased.

 For example, the toner T charged in contact with the elastic portion 130B or the like has an electric field (an electric field formed from the contact portion 185 side toward the elastic portion 130B side, an elastic portion 130B side). It moves according to the electric field formed toward the contact part 185 side. That is, when an electric field is formed from the contact portion 185 side toward the elastic portion 130B side, the negatively charged toner T moves from the low potential elastic portion 130B side to the high potential contact portion 185 side, When an electric field is formed from the elastic portion 130B side to the contact portion 185 side, the negatively charged toner T moves from the low potential contact portion 185 side to the high potential elastic portion 130B side. For this reason, the number of times the toner T contacts the contact portion 185 and the elastic portion 130B increases, so that the charge amount of the toner T can be increased.

 Further, as described above, the electric field from the contact portion 185 side toward the elastic portion 130B side is formed for a longer time than the electric field from the elastic portion 130B side toward the contact portion 185 side. For this reason, when the toner T comes into contact with the elastic portion 130B, the electrons of the elastic portion 130B often move to the toner T in contact with the elastic portion 130B due to an electric field from the contact portion 185 side toward the elastic portion 130B side. Therefore, the charge amount of the toner T can be increased.

=== Other Embodiments ===
The image forming apparatus and the like according to the present invention have been described above based on the above embodiment. However, the above embodiment of the present invention is for facilitating understanding of the present invention and limits the present invention. is not. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

The present invention includes a developing roller (for example, developing roller 140) for carrying a developer (for example, toner T) and a supply roller (for example, developing roller 140) for holding the developer and supplying the developer to the developing roller (for example, , A supply roller 130) and a developing device (for example, developing devices 100Y and 100M) that includes a contact member (for example, a toner guide member 180) that contacts the supply roller and holds the developer on the supply roller. , 100C, 100K)
The supply roller has a conductive shaft portion (for example, a core metal 130A) and an elastic portion (for example, an elastic portion 130B) provided on the radially outer side of the shaft portion, and the contact member The abutting portion (for example, the abutting portion 185) that abuts on the elastic portion has conductivity, and generates a potential difference between the corresponding contacting portion and the shaft portion (see FIG. 4). The present invention relates to a developing device.

  In the above embodiment, an intermediate transfer type full color laser beam printer has been described as an example of the image forming apparatus. However, the present invention is not limited to the intermediate transfer type, but a full color laser beam printer, a monochrome laser beam printer, a copying machine, The present invention can be applied to various image forming apparatuses such as facsimiles.

  In the above-described embodiment, the image forming apparatus including the tandem developing devices 100Y, 100M, 100C, and 100K has been described as an example. However, the present invention is not limited to this. For example, the present invention can be applied to an image forming apparatus provided with a rotary developing device.

  In the above-described embodiment, the image carrier is described as a configuration in which a photosensitive layer is provided on the outer peripheral surface of a cylindrical conductive substrate. However, the present invention is not limited to this. For example, a so-called photosensitive belt configured by providing a photosensitive layer on the surface of a belt-like conductive substrate may be used.

  In the above-described embodiment, the toner is described as being a polymerization toner, but is not limited thereto. For example, the toner may be a pulverized toner. However, since the circularity of the polymerization toner is better, charging of the toner is advantageous.

In the embodiment described above, the regulation blade 150 having the rubber part 151 is brought into contact with the developing roller 140 formed of aluminum or the like. However, the present invention is not limited to this.
For example, as shown in FIG. 5, a regulating blade 250 made of SUS (stainless steel) may be brought into contact with the developing roller 240 whose surface is made of rubber 240B. FIG. 5 is a diagram for explaining another embodiment of the developing roller and the charging member.

Furthermore, in the above-described embodiment, a voltage is applied to the core metal 130A and the contact portion 185 is grounded (earthed). However, the present invention is not limited to this.
For example, a voltage that causes a potential difference between the contact portion 185 and the core metal 130 </ b> A may be applied to the contact portion 185.
However, when the contact portion 185 is grounded, a potential difference can be easily generated between the contact portion 185 and the core metal 130A without applying a voltage to the contact portion 185. It becomes.
Therefore, the above embodiment is more desirable.

Furthermore, in the above-described embodiment, a voltage obtained by superimposing an AC voltage on a DC voltage is applied to the core metal 130A. However, the present invention is not limited to this.
For example, only a DC voltage may be applied to the core metal 130A. Moreover, it is good also as applying only an alternating voltage to 130A of metal cores.

Furthermore, in the above embodiment, the developing bias power supply 210 for applying the developing bias to the developing roller 140 is provided, and the developing bias power supply 210 applies a voltage to the core metal 130A. However, the present invention is not limited to this. Is not to be done.
For example, the developing bias power supply 210 may not apply a voltage to the core metal 130A. That is, a voltage may be applied to the core metal 130A from a power source different from the developing bias power source 210.
However, when the developing bias power supply 210 applies a voltage to the cored bar 130A, a single power supply applies a developing bias to the developing roller 140, and the cored bar 130A is connected between the contact portion 185 and the cored bar 130A. It is possible to apply a voltage for generating a potential difference between the two.
Therefore, the above embodiment is more desirable.

Further, in the above-described embodiment, the photosensitive drums 23Y and 23M have the regulating blade 150 that contacts the developing roller 140 and negatively charges the toner T, and is negatively charged by the toner T carried on the developing roller 140. , 23C and 23K are developed as latent images, but the present invention is not limited to this.
For example, the regulating blade may positively charge the toner, and the latent image carried on the photosensitive drums 23Y, 23M, 23C, and 23K may be developed by the positively charged toner carried on the developing roller.

Furthermore, in the above-described embodiment, the toner T is non-magnetic. However, the present invention is not limited to this.
For example, the toner may have magnetism.
When the non-magnetic toner T is used, the amount of toner transported by the supply roller 130 and the developing roller 140 may be smaller than when the magnetic toner is used. Therefore, when the negative charge amount of the toner held on the supply roller 130 increases due to the potential difference generated between the contact portion 185 and the core metal 130A, the toner is easily held on the supply roller 130. Since the toner is easily carried on the developing roller 140, the effect of preventing a decrease in the amount of toner transported by the supply roller 130 and the developing roller 140 is more effectively achieved.
Therefore, the above embodiment is more desirable.

Further, in the above embodiment, the rotation direction of the supply roller 130 is the same as the rotation direction of the developing roller 140, but the present invention is not limited to this.
For example, the rotation direction of the supply roller 130 may be different from the rotation direction of the developing roller 140.
However, when the rotation direction of the supply roller 130 is the same as the rotation direction of the developing roller 140, the toner T held on the supply roller 130 is supplied while being rubbed against the developing roller 140. T is triboelectrically charged. Therefore, the charge amount of the toner T carried on the developing roller 140 increases, and the toner T is reliably carried on the developing roller 140. Therefore, it is possible to more effectively prevent a decrease in the transport amount of the toner T by the developing roller 140. Is possible.
Therefore, the above embodiment is more desirable.

Furthermore, in the above-described embodiment, the elastic portion 130B is formed of urethane foam, and the elastic portion 130B has conductivity. However, the present invention is not limited to this.
For example, the elastic part may be formed of a member other than urethane foam. The elastic part may not have conductivity.

Further, in the above-described embodiment, the toner container 120 for accommodating the toner T and the toner T provided in the toner container 120 and accommodated in the toner container 120 are conveyed to the toner guide member 180. The toner guide member 180 stores the toner T conveyed by the agitator 170, and the supply roller 130 supplies the toner T stored in the toner guide member 180 to the developing roller 140. However, the present invention is not limited to this.
For example, an agitator that is provided in the toner storage unit 120 and that transports the toner T stored in the toner storage unit 120 to the toner guide member 180 may be omitted.

Further, in the above-described embodiment, the toner guide member 180 has conductivity and is a member different from the member constituting the toner storage unit 120, but is not limited thereto.
For example, only the contact portion 185 of the toner guide member 180 may be conductive, and other portions (the scraper 181, the flat conveyance unit 183, and the curved portion 184) may not have conductivity. Further, the toner guide member 180 may be a part of a member constituting the toner storage unit 120.
However, when the toner guide member 180 has conductivity and is a member different from the member constituting the toner storage unit 120, the toner guide member 180 having conductivity can be easily manufactured. Become.
Therefore, the above embodiment is more desirable.

=== Configuration of Image Forming System etc. ===
Next, an embodiment of an image forming system which is an example of an embodiment according to the present invention will be described with reference to FIGS.

FIG. 6 is an explanatory diagram showing an external configuration of the image forming system. The image forming system 700 includes a computer 702, which is an example of a computer main body, a display device 704, a printer 1, an input device 708, and a reading device 710.
In this embodiment, the computer 702 is housed in a mini-tower type housing, but is not limited thereto. The display device 704 is generally a CRT (Cathode Ray Tube), a plasma display, a liquid crystal display device, or the like, but is not limited thereto. As the printer 1, the printer described above is used. In this embodiment, the input device 708 uses a keyboard 708A and a mouse 708B, but is not limited thereto. In this embodiment, the reading device 710 uses a flexible disk drive device 710A and a CD-ROM drive device 710B. However, the reading device 710 is not limited to this. For example, an MO (Magneto Optical) disk drive device or a DVD (Digital Versatile) is used. Disk) etc. may be used.

  FIG. 7 is a block diagram showing a configuration of the image forming system shown in FIG. An internal memory 802 such as a RAM and an external memory such as a hard disk drive unit 804 are further provided in a housing in which the computer 702 is housed.

  In the above description, the example in which the printer 1 is connected to the computer 702, the display device 704, the input device 708, and the reading device 710 to configure the image forming system has been described. However, the present invention is not limited to this. Absent. For example, the image forming system may include the computer 702 and the printer 1, and the image forming system may not include any of the display device 704, the input device 708, and the reading device 710.

  For example, the printer 1 may have a part of each function or mechanism of the computer 702, the display device 704, the input device 708, and the reading device 710. As an example, the printer 1 includes an image processing unit that performs image processing, a display unit that performs various displays, a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. It is good also as a structure to have.

  The image forming system realized in this way is a system superior to the conventional system as a whole system.

2 is a schematic cross-sectional view showing main components constituting the printer 1. FIG. 2 is a block diagram showing a control unit 80 of the printer 1. FIG. It is sectional drawing which showed the main components of the developing device 100Y. It is a schematic diagram for demonstrating an electric potential difference generation means. It is a figure for demonstrating another Example of a developing roller and a charging member. 1 is a diagram illustrating an external configuration of an image forming system 700. FIG. 7 is a block diagram illustrating a configuration of the image forming system 700 illustrated in FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer 3 Housing 5 Paper discharge tray 7 Door body 10 Exposure unit 11 Scanner part 11A Polygon mirror motor 11B Polygon mirror 13 f-theta lens 15 Reflecting mirror 17 Folding mirror 20 Image forming unit 21 Image forming station 23 Photosensitive drum 25 Charging means 30 Transfer belt unit 31 Drive roller 33 Drive roller 35 Tension roller 37 Intermediate transfer belt 37A Belt surface 37B Belt surface 41 Cleaning means 41A Cleaning blade 41B Toner transport path 43 Primary transfer roller 45 Secondary transfer roller 50 Paper feed unit 51 Paper feed cassette 53 Pickup roller 60 Paper transport unit 61 Gate roller pair 63 Fixing means 63A Fixing roller pair 65 Paper discharge roller pair 67 Double-sided print transport path 80 Control unit 81 main controller 83 unit controller 85 interface 87 image memory 89 CPU
DESCRIPTION OF SYMBOLS 100 Developing device 110 Housing 120 Toner accommodating part 130 Supply roller 130A Core metal 130B Elastic part 140 Developing roller 150 Restricting blade 151 Contact part 152 Support part 153 Elastic member 160 Seal member 170 Agitator 171 Rotating shaft 173 Arm member 175 Stirring fin 177 region 180 Toner guide member 181 Scraper 183 Flat conveying portion 184 Curved portion 185 Contact portion 189 Temporary storage portion 190 Toner guide surface 192 Toner guide space portion 210 Developing bias power source 210A DC power source 210B AC power source 220 Earth 700 Image forming system 702 Computer 704 Display Device 708 Input device 708A Keyboard 708B Mouse 710 Reading device 710A Flexible disk drive device 710B C Contact position A gap P medium T toner with -ROM drive 802 internal memory 804 as a hard disk drive unit H1 toner guide member and the contact position H2 feed roller the feed roller and the contact position H3 developing roller and the developing roller regulating blade

Claims (16)

A developing roller for carrying the developer;
A supply roller for holding the developer and supplying the developer to the development roller;
A developing device having a contact member that contacts the supply roller and holds the developer on the supply roller;
The supply roller has a conductive shaft portion, and an elastic portion provided on the radially outer side of the shaft portion,
The contact portion of the contact member that contacts the elastic portion has conductivity,
A developing device comprising a potential difference generating means for generating a potential difference between the contact portion and the shaft portion. The developing device according to claim 1,
A voltage is applied to the shaft part,
The developing device according to claim 1, wherein the contact portion is grounded. The developing device according to claim 2,
A developing device, wherein a voltage obtained by superimposing an AC voltage on a DC voltage is applied to the shaft portion. In the developing device according to claim 2 or 3,
A power source for applying a voltage to the developing roller;
The developing device, wherein the power source applies a voltage to the shaft portion. In the developing device according to any one of claims 1 to 4,
A charging member that contacts the developing roller and negatively charges the developer;
A developing apparatus for developing a latent image carried on an image carrier by a negatively charged developer carried on the developing roller. The developing device according to claim 5,
When the developer comes into contact with the contact portion, it is negatively charged,
The developing device according to claim 1, wherein the contact portion holds the negatively charged developer on the supply roller. In the developing device according to claim 5 or 6,
The supply roller is in contact with the developing roller;
The supply roller conveys developer from a contact position between the contact member and the supply roller to a contact position between the supply roller and the development roller;
The developing device transports a developer from a contact position between the supply roller and the development roller to a contact position between the development roller and the charging member. The developing device according to claim 7,
The contact position between the contact member and the supply roller is located below the contact position between the supply roller and the developing roller,
The contact position between the developing roller and the charging member is located below the contact position between the supply roller and the developing roller,
A developing device, wherein a gap is provided between the contact member and the charging member. In the developing device according to claim 7 or 8,
The developing device, wherein the developer is non-magnetic. The developing device according to any one of claims 7 to 9,
The developing device according to claim 1, wherein a rotation direction of the supply roller is the same as a rotation direction of the developing roller. In the developing device according to any one of claims 1 to 10,
The elastic portion is formed of urethane foam,
The developing device, wherein the elastic portion has conductivity. The developing device according to any one of claims 1 to 11,
An accommodating portion for accommodating the developer;
A conveying member provided in the accommodating portion, for conveying the developer accommodated in the accommodating portion to the contact member,
The contact member stores the developer transported by the transport member,
The developing device, wherein the supply roller supplies the developer stored in the contact member to the developing roller. The developing device according to claim 12, wherein
The developing device according to claim 1, wherein the contact member is conductive and is a member different from a member constituting the housing portion. A developing roller for carrying the developer, a supply roller for holding the developer and supplying the developer to the developing roller, and abutting the supply roller to hold the developer on the supply roller A developing device including:
The supply roller has a conductive shaft portion and an elastic portion provided radially outside the shaft portion, and the contact portion of the contact member that contacts the elastic portion is electrically conductive. Provided with a potential difference generating means for generating a potential difference between the corresponding contact portion and the shaft portion,
A voltage is applied to the shaft portion, the contact portion is grounded,
A voltage obtained by superimposing an AC voltage on a DC voltage is applied to the shaft part,
A power source for applying a voltage to the developing roller; the power source applies a voltage to the shaft portion;
A charging member that contacts the developing roller and negatively charges the developer, and is carried on the image carrier by the negatively charged developer carried on the developing roller,
When the developer contacts the contact portion, the developer is negatively charged, and the contact portion holds the negatively charged developer on the supply roller,
The supply roller contacts the developing roller, and the supply roller conveys the developer from a contact position between the contact member and the supply roller to a contact position between the supply roller and the development roller. The developing roller conveys the developer from a contact position between the supply roller and the development roller to a contact position between the development roller and the charging member,
The contact position between the contact member and the supply roller is located below the contact position between the supply roller and the developing roller, and the contact position between the developing roller and the charging member is the supply roller. And a position below the contact position with the developing roller, a gap is provided between the contact member and the charging member,
The developer is non-magnetic,
The rotation direction of the supply roller is the same direction as the rotation direction of the developing roller,
The elastic part is made of urethane foam, the elastic part has conductivity,
A housing portion for housing the developer, and a transport member provided in the housing portion for transporting the developer housed in the housing portion to the contact member, wherein the contact member is The developer transported by the transport member is stored, and the supply roller supplies the developer stored in the contact member to the developing roller.
The developing device according to claim 1, wherein the contact member is conductive and is a member different from a member constituting the housing portion. A developing roller for carrying the developer, a supply roller for holding the developer and supplying the developer to the developing roller, and abutting the supply roller to hold the developer on the supply roller A developing device,
In an image forming apparatus comprising:
The supply roller has a conductive shaft portion, and an elastic portion provided on the radially outer side of the shaft portion,
The contact portion of the contact member that contacts the elastic portion has conductivity,
An image forming apparatus comprising a potential difference generating means for generating a potential difference between the contact portion and the shaft portion. A computer body, and
Connected to the computer main body, a developing roller for carrying the developer, a supply roller for holding the developer and supplying the developer to the developing roller, and abutting the supply roller, the developer A developing device having a contact member for holding the supply roller;
In an image forming system comprising:
The supply roller has a conductive shaft portion, and an elastic portion provided on the radially outer side of the shaft portion,
The contact portion of the contact member that contacts the elastic portion has conductivity,
An image forming system comprising a potential difference generating means for generating a potential difference between the contact portion and the shaft portion.

Images