JP2011064843A - Developer supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED To better collect a developer from a developer carrying member.
A developer supply device includes a developer carrying member, a developer carrying means, a collection electric field transport substrate, and a developer adhesion releasing electrode. The developer carrying member is provided to face the supply target at the developer supply position. The developer carrying means is configured to carry the developer on the developer carrying surface upstream of the developer supply position in the moving direction of the developer carrying surface. The collection electric field transport substrate is provided so as to face the developer carrying surface downstream of the developer supply position. The developer adhesion release electrode is provided between the developer carrying surface and the collection electric field transport substrate, and the developer carried on the developer carrying surface is generated by an electric field generated by voltage application. It is configured to float from the developer carrying surface.
[Selection] Figure 2

Description

  The present invention relates to a developer supply apparatus configured to supply a charged powdery developer to a supply target.

  As this type of apparatus, for example, those disclosed in Japanese Patent Laid-Open Nos. 3-12678 and 2008-70803 are known. Such an apparatus includes a developer carrying member (developing roller), an upstream developer transport unit, and a downstream developer transport unit.

  The developer carrying member is provided so as to face the electrostatic latent image carrying body (photosensitive drum) in a predetermined developing area. The developer carrying member has a developer carrying surface for carrying a charged developer.

  The upstream developer transport means has an upstream transport surface. The upstream conveying surface is disposed on the upstream side in the moving direction of the developer carrying surface with respect to the developing region so as to face the developer carrying surface with a predetermined distance. The upstream developer transport means generates an upstream transport electric field (an electric field for moving the developer on the upstream transport surface from the upstream side to the downstream side in the moving direction of the developer carrying member). It is configured to form.

  The downstream developer conveying means has a downstream conveying surface. The downstream conveying surface is disposed on the downstream side in the moving direction of the developer carrying surface with respect to the developing region so as to face the developer carrying surface with a predetermined distance. The downstream developer transport means generates a downstream transport electric field (an electric field for moving the developer on the downstream transport surface from the upstream side to the downstream side in the moving direction of the developer carrying member). It is configured to form.

  In this configuration, an electric field that moves the charged developer from the upstream side to the downstream side in the moving direction of the developer carrying surface (the rotation direction of the developing roller) is on the upstream transport surface and the It is formed in a space on the downstream conveyance surface. Accordingly, the developer moves from the upstream side to the downstream side in the movement direction of the developer carrying member on each of the upstream side conveyance surface and the downstream side conveyance surface.

  The developer conveyed by the upstream developer conveying means is directed to the developer carrying surface at a position where the upstream carrying surface and the developer carrying surface (the peripheral surface of the developing roller) face each other. . Thereby, the developer adheres to the developer carrying surface. That is, the developer is carried on the developer carrying surface.

  Part of the developer carried on the developer carrying surface is consumed in the development area by being used for developing an electrostatic latent image. That is, when a part of the developer carried on the developer carrying surface reaches the development area, the electrostatic latent image carrying surface, which is the peripheral surface of the electrostatic latent image carrying body, is electrostatically charged. It adheres to the position corresponding to the latent image.

  Of the developer carried on the developer carrying surface, the remaining portion not adhered to the electrostatic latent image carrying surface (not consumed in the developing area) is the downstream developer conveying means. And is conveyed from the upstream side to the downstream side in the moving direction of the developer carrying surface (the rotation direction of the developing roller) on the downstream conveying surface.

  In this type of apparatus, the developer remaining on the developer carrying surface without being consumed in the developing area is recovered well from the developer carrying member (the developer carrying surface). Otherwise, there is a risk of problems such as disturbance of the formed image. The present invention has been made to cope with such a problem. That is, an object of the present invention is to better collect the developer from the developer carrying member.

  The developer supply device of the present invention is configured to supply a charged powdery developer to a supply target. The developer supply apparatus includes a developer carrying member, a developer carrying means, a collection electric field transport substrate, and a developer adhesion releasing electrode.

  The developer carrying member has a developer carrying surface that is a cylindrical circumferential surface parallel to the main scanning direction, and the developer carrying surface faces the supply target at the developer supply position. Is provided. The developer carrying member rotates on an axis parallel to the main scanning direction, thereby moving the developer carrying surface in a direction perpendicular to the main scanning direction and carrying the developer carrying surface on the developer carrying surface. The developed developer is supplied to the developer supply position.

  The developer carrying means is configured to carry the developer on the developer carrying surface upstream of the developer supply position in the moving direction of the developer carrying surface.

  Specifically, for example, the supply electric field transport substrate as the developer carrying means has a longitudinal direction along the main scanning direction and a plurality of supply electric field transport substrates arranged along the direction intersecting the main scanning direction. A transport electrode is provided. The electric field transport substrate for supply is provided so that the downstream end in the developer transport direction faces the developer carrying surface. The electric field transport substrate for supply supplies the developer from the developer reservoir to the developer by an electric field generated with application of a transport bias that is a traveling-wave multiphase AC voltage to the plurality of transport electrodes for supply. It is configured to transport in the developer transport direction toward the developer carrying member.

  The recovery electric field transport substrate includes a recovery transport electrode having a longitudinal direction along the main scanning direction and a plurality of recovery transport electrodes arranged along a direction intersecting the main scanning direction. The collection electric field transport substrate is provided to face the developer carrying surface on the downstream side in the moving direction from the developer supply position. The recovery electric field transport substrate directs the developer to the developer reservoir by an electric field generated in response to the application of a recovery bias that is a traveling-wave multiphase AC voltage to the plurality of recovery transport electrodes. It is comprised so that it may convey.

  The developer adhesion releasing electrode is provided between the developer carrying surface and the collection electric field transport substrate facing each other. The developer adhesion releasing electrode is configured to float the developer carried on the developer carrying surface from the developer carrying surface by an electric field generated with voltage application. The present invention is characterized in that the developer supply device includes the developer adhesion releasing electrode having the above-described configuration.

  The developer adhesion releasing electrode may be constituted by a wire stretched along the main scanning direction. In this case, a plurality of the wires may be provided so as to be arranged along the recovery electric field transport substrate. Then, a developer adhesion release bias that is a two-phase AC voltage that causes the adjacent wires to have opposite phases can be applied to the plurality of wires.

  In the above-described configuration, the developer is carried on the developer carrying surface by the developer carrying means upstream of the developer supply position in the moving direction of the developer carrying surface. The developer is supplied to the developer supply position by reaching the developer supply position by movement of the developer carrying surface.

  The developer carrying surface that has passed through the developer supply position moves to a position facing the developer adhesion releasing electrode. Here, the developer carried on the developer carrying surface floats from the developer carrying surface due to an electric field generated in response to voltage application to the developer adhesion releasing electrode. The developer is recovered by the recovery electric field transport substrate and transported toward the developer reservoir.

  Therefore, according to the developer supply apparatus of the present invention, the recovery of the developer from the developer carrying member can be performed better.

1 is a side view showing a schematic configuration of a laser printer which is an image forming apparatus to which an embodiment of the present invention is applied. FIG. 2 is an enlarged side sectional view of the toner supply device shown in FIG. 1. It is the sectional side view to which the electric field conveyance board | substrate shown by FIG. 2 was expanded. It is a graph which shows an example of the output waveform of each power supply circuit shown by FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

<Configuration of laser printer>
FIG. 1 is a side view showing a schematic configuration of a laser printer 1 which is an image forming apparatus to which an embodiment of the present invention is applied. Referring to FIG. 1, the laser printer 1 includes a paper transport mechanism 2, a photosensitive drum 3, a charger 4, a scanner unit 5, and a toner supply device 6.

  Sheet-like paper P is stored in a stacked state in a paper feed tray (not shown) provided in the laser printer 1. The paper transport mechanism 2 is configured to transport the paper P along a predetermined paper transport path PP.

  An electrostatic latent image carrying surface LS is formed on the peripheral surface of the photosensitive drum 3 as a supply target of the present invention. The electrostatic latent image carrying surface LS is formed as a cylindrical surface parallel to the main scanning direction (z-axis direction in the figure). The electrostatic latent image carrying surface LS forms an electrostatic latent image based on a potential distribution, and carries toner T (see FIG. 2) as a developer of the present invention at a position corresponding to the electrostatic latent image. Is configured to do.

  The photosensitive drum 3 is configured to be rotationally driven around an axis parallel to the main scanning direction. That is, the photosensitive drum 3 is driven such that the electrostatic latent image carrying surface LS can be moved along a direction orthogonal to the main scanning direction by being rotationally driven about an axis parallel to the main scanning direction. Is configured.

  The charger 4 is disposed so as to face the electrostatic latent image carrying surface LS. The charger 4 is a corotron type or scorotron type charger, and is configured so that the electrostatic latent image carrying surface LS can be uniformly positively charged.

  The scanner unit 5 applies a laser beam LB of a predetermined wavelength band modulated based on image data (light emission ON / OFF is controlled depending on the presence or absence of a pixel) to a scanning position SP (charging) on the electrostatic latent image carrying surface LS. The image is formed (exposure) at a position downstream of the device 4 in the rotation direction of the photosensitive drum 3, and the image formation position is moved (scanned) along the main scanning direction at a constant speed. Thus, an electrostatic latent image can be formed on the electrostatic latent image carrying surface LS.

  The toner supply device 6 as the developer supply device of the present invention is disposed below the photosensitive drum 3 so as to face the photosensitive drum 3. The toner supply device 6 is configured to supply toner T (see FIG. 2) to the electrostatic latent image carrying surface LS in a charged state at the development position DP. Here, the development position DP is a position where the toner supply device 6 faces the electrostatic latent image carrying surface LS. The detailed configuration of the toner supply device 6 will be described later.

  Next, the specific configuration of each part of the laser printer 1 will be described in more detail.

  The sheet transport mechanism 2 includes a pair of registration rollers 21 and a transfer roller 22. The registration roller 21 is configured so that the paper P can be sent out between the photosensitive drum 3 and the transfer roller 22 at a predetermined timing. The transfer roller 22 is disposed so as to face the electrostatic latent image carrying surface LS, which is the outer peripheral surface of the photosensitive drum 3, with the sheet P interposed therebetween at the transfer position TP. Further, the transfer roller 22 is configured to be rotationally driven in a direction indicated by an arrow in the drawing.

  The transfer roller 22 is connected to a bias power supply circuit (not shown). That is, the transfer roller 22 is applied with a predetermined transfer bias voltage between the photosensitive drum 3 and the toner T (see FIG. 2) attached on the electrostatic latent image carrying surface LS to the sheet P. It is like that.

<< Toner Supply Device >>
FIG. 2 is an enlarged side cross-sectional view of the toner supply device 6 shown in FIG. Referring to FIG. 2, the toner supply device 6 is configured to supply the charged toner T to the photosensitive drum 3 while being transported along the toner transport path TTP by an electric field.

  The toner box 61 forming the casing of the toner supply device 6 is a box-like member formed in an oval shape in a side sectional view, and its longitudinal direction is parallel to the vertical direction (y-axis direction in the figure). Is arranged. The toner box 61 contains toner T as a powdery dry developer. That is, the toner T is stored in a toner storage portion 61a (corresponding to the developer storage portion of the present invention) that is a substantially semi-cylindrical portion at the bottom of the space inside the toner box 61. In this embodiment, the toner T is a positively chargeable, non-magnetic single component black toner.

  An opening 61 b is formed at the top of the toner box 61 and at a position facing the photosensitive drum 3. That is, the opening 61b opens upward toward the photosensitive drum 3, so that the photosensitive drum 3 and the developing roller 62 face each other at the development position DP (corresponding to the developer supply position of the present invention). It is provided to do.

  The developing roller 62 as the developer carrying member of the present invention has a roller-like shape having a toner carrying surface 62a (corresponding to the developer carrying surface of the present invention) which is a cylindrical circumferential surface parallel to the main scanning direction. It is a member and is provided so as to face the photosensitive drum 3. That is, the developing roller 62 is disposed so that the toner carrying surface 62a is opposed to the electrostatic latent image carrying surface LS on the photosensitive drum 3 at a development position DP with a gap of a predetermined interval (about 500 μm). ing.

  The developing roller 62 is supported at the upper end of the toner box 61 where the opening 61b is formed so as to be rotatable about an axis parallel to the main scanning direction. That is, the developing roller 62 rotates on the above-described axis, thereby moving the toner carrying surface 62a in a direction perpendicular to the main scanning direction (see the arrow in the figure) and carrying the toner carrying surface 62a on the toner carrying surface 62a. The toner T is supplied to the developing position DP.

  In the toner box 61, an electric field transport substrate 63 is provided along the toner transport path TTP. Specifically, the electric field transport substrate 63 is supported (fixed) on the inner wall surface of the toner box 61. In the present embodiment, the electric field transport substrate 63 includes a bottom electric field transport substrate 63a, a supply electric field transport substrate 63b, and a recovery electric field transport substrate 63c. The details of the internal configuration of the electric field transfer board 63 (the bottom electric field transfer board 63a, the supply electric field transfer board 63b, and the recovery electric field transfer board 63c) will be described later.

  The bottom electric field transport substrate 63a is disposed at the bottom in the space inside the toner box 61 so as to constitute the bottom surface of the toner storage portion 61a. The bottom electric field transport substrate 63a is a curved plate-like portion bent in a semi-cylindrical shape in a side sectional view at the bottom of the electric field transport substrate 63, and is smoothly connected to the lower end of the supply electric field transport substrate 63b. Yes. The bottom electric field transport substrate 63a is connected to the lower end portion so as to transport the toner T in the toner reservoir 61a toward the lower end portion of the supply electric field transport substrate 63b.

  The electric field transport substrate 63b for supplying the toner T on the toner carrying surface 62a at a position upstream of the developing position DP in the moving direction of the toner carrying surface 62a by the rotation of the developing roller 62. Is erected so as to be conveyed upward from the lower end connected to the bottom electric field transport substrate 63a toward the upper end facing the developing roller 62.

  That is, the supply electric field transport substrate 63b has an upper end (downstream end in the toner transport direction TTD) at the developing position DP in the moving direction of the toner carrying surface 62a and the toner carrying surface 62a by the rotation of the developing roller 62. It is provided so as to be opposed to each other with a gap of a predetermined interval (about 300 μm) at a position on the upstream side. The main portion of the electric field transport substrate 63b for supply (the most upstream portion in the toner transport direction TTD from the lower end connected to the bottom electric field transport substrate 63a to the upper end close to the toner carrying surface 62a) moves the toner T vertically upward. It is formed in a flat plate shape so as to be conveyed.

  The recovery electric field transport substrate 63c is provided to face the developing roller 62 on the opposite side of the upper end portion of the supply electric field transport substrate 63b with the developing roller 62 interposed therebetween. The recovery electric field transport substrate 63c is disposed downstream of the opening 61b of the toner box 61 in the toner transport direction TTD. In the present embodiment, the lower end portion (terminal portion in the toner transport direction TTD) of the collection electric field transport substrate 63c is provided at a position corresponding to the lower end of the developing roller 62.

  The upper part of the collection electric field transport substrate 63c is a gap at a predetermined interval (about 300 μm) between the toner carrying surface 62a and a position downstream of the developing position DP in the moving direction of the toner carrying surface 62a by the rotation of the developing roller 62. Is formed in a curved plate shape that is bent in a semi-cylindrical shape in a side sectional view so as to face each other. The lower portion of the recovery electric field transport substrate 63c is formed in a flat plate shape, and is arranged in parallel with the vertical direction so as to be gradually separated from the toner carrying surface 62a as it goes downward. The recovery electric field transport substrate 63c is configured to recover the toner T that has not been consumed at the development position DP from the developing roller 62 and to transport the recovered toner T toward the lower toner storage portion 61a. ing.

  The bottom electric field transfer board 63 a and the supply electric field transfer board 63 b are electrically connected to the transfer bias power supply circuit 64. The recovery electric field transport board 63c is electrically connected to the recovery bias power supply circuit 65. The developing roller 62 is electrically connected to the developing bias power supply circuit 66.

  The transport bias power circuit 64, the recovery bias power circuit 65, and the development bias power circuit 66 circulate the toner T in the toner transport direction TTD along the toner transport path TTP (the toner T in the toner storage unit 61a is developed by the developing roller 62). Is supplied to the developing position DP while being carried once, and a voltage necessary for collecting the toner T that has not been consumed at the developing position DP from the developing roller 62 and returning it to the lower toner storage portion 61a is output. It is like that.

  Specifically, the carrier bias power supply circuit 64 outputs a rectangular wave AC voltage (carrier bias) having an amplitude of 600 V and a DC offset of 700 V. Further, the recovery bias power supply circuit 65 outputs a rectangular wave AC voltage (recovery bias) having an amplitude of 600 V and a DC offset of 300 V. Further, the developing bias power supply circuit 66 outputs a rectangular wave AC voltage (developing bias) having an amplitude of 1 kV and a DC offset of 500 V.

  A shielding plate 67 is disposed in a space inside the toner box 61 below the developing roller 62 and at a position close to the supply electric field transport substrate 63b. The shielding plate 67 is provided so that the toner T does not adhere to the developing roller 62 when the toner T rises in the space inside the toner box 61 by the operation of the electric field transport substrate 63.

  A plurality of toner adhesion releasing wires 68 are arranged between the upper portion of the collection electric field transport substrate 63c and the toner carrying surface 62a facing each other. Each toner adhesion releasing wire 68 is made of metal and is stretched in parallel with the main scanning direction. A plurality of toner adhesion releasing wires 68 are arranged at predetermined intervals along the toner carrying surface 62a and the collection electric field transport substrate 63c (that is, along the toner transport path TTP).

  The plurality of toner adhesion release wires 68 are electrically connected to a toner adhesion release power supply circuit 69. The power supply circuit 69 for releasing the toner adhesion force is a developer adhesion force that is a two-phase AC voltage (rectangular wave AC voltage having an amplitude of 2 kV and a DC offset of 500 V) that causes the adjacent toner adhesion release wires 68 to have opposite phases. An opening bias is output (applied to a plurality of toner adhesion releasing wires 68).

<<< Transport substrate >>>
FIG. 3 is an enlarged side sectional view of the electric field transport substrate 63 shown in FIG. Referring to FIG. 3, the electric field transport board 63 is a thin plate-like member and has the same configuration as the flexible printed wiring board. Specifically, the electric field transport substrate 63 includes a transport electrode 631, a transport electrode support film 632, a transport electrode coating layer 633, and a transport electrode overcoating layer 634.

  The transport electrode 631 is a linear wiring pattern having a longitudinal direction parallel to the main scanning direction, and is formed of a thin film copper foil. The plurality of transport electrodes 631 are arranged along a toner transport path TTP that intersects the main scanning direction, and are arranged in parallel to each other.

  The transport electrode 631 in the bottom electric field transport substrate 63a is hereinafter referred to as “bottom transport electrode 631a”. Similarly, the transport electrode 631 in the supply electric field transport substrate 63b is hereinafter referred to as “supply transport electrode 631b”, and the transport electrode 631 in the recovery electric field transport substrate 63c is hereinafter referred to as “collection transport electrode 631c”.

  Each of the plurality of transport electrodes 631 arranged along the toner transport path TTP is connected to the same power supply circuit every third. That is, the transfer electrode 631, connected to the power supply circuit VA, the transfer electrode 631, connected to the power supply circuit VB, the transfer electrode 631, connected to the power supply circuit VC, the transfer electrode 631, connected to the power supply circuit VD, and the power supply circuit VA. The transport electrodes 631,... Connected to the power supply circuit VB are arranged in order along the toner transport path TTP (note that these power supply circuits VA to VD are transport bias power supply circuits. 64 etc.).

  Here, FIG. 4 is a graph showing an example of output waveforms of the power supply circuits VA to VD shown in FIG. In the present embodiment, as shown in FIG. 4, each power supply circuit VA to VD is configured to output an AC voltage having substantially the same waveform. Further, the power supply circuits VA to VD are configured so that the phases of the waveforms of the voltages generated by the power supply circuits VA to VD are different by 90 °. That is, the voltage phase is delayed by 90 ° in order from the power supply circuit VA to the power supply circuit VD.

  As described above, the electric field transport substrate 63 is positively charged by generating a traveling-wave electric field along the toner transport path TTP in accordance with the application of the multiphase AC driving voltage as described above to each transport electrode 631. The configured toner T can be transported in the toner transport direction TTD.

  The plurality of transport electrodes 631 are formed on the surface of the transport electrode support film 632. The transport electrode support film 632 is a flexible film and is made of an insulating synthetic resin such as a polyimide resin. The transport electrode coating layer 633 is made of an insulating synthetic resin. The transport electrode coating layer 633 is provided to cover the transport electrode 631 and the surface of the transport electrode support film 632 where the transport electrode 631 is provided.

  A transport electrode overcoating layer 634 is provided on the transport electrode coating layer 633. That is, the above-described transport electrode coating layer 633 is formed between the transport electrode overcoating layer 634 and the transport electrode 631. The surface of the transport electrode overcoating layer 634 is formed as a smooth surface with very few irregularities so that the toner T can be transported smoothly.

<Description of laser printer operation>
Next, an outline of the operation of the laser printer 1 configured as described above will be described with reference to the drawings as appropriate.

<< Paper feeding action >>
First, referring to FIG. 1, the leading edge of the paper P stacked on the paper feed tray (not shown) is sent to the registration roller 21. The registration roller 21 corrects the skew of the paper P and adjusts the conveyance timing. Thereafter, the paper P is fed to the transfer position TP.

<< Carrying of toner image on electrostatic latent 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 electrostatic latent image carrying surface LS that is the circumferential surface of the photosensitive drum 3 as follows. Is done.

<<< Formation of electrostatic latent image >>>
First, the electrostatic latent image carrying surface LS of the photosensitive drum 3 is uniformly charged to the positive polarity by the charger 4. The electrostatic latent image carrying surface LS charged by the charger 4 is a scan position SP which is a position facing (facing) the scanner unit 5 by the rotation of the photosensitive drum 3 in the direction indicated by the arrow in the drawing. Move up.

  At this scan position SP, the laser beam LB modulated based on the image information is applied to the electrostatic latent image carrying surface LS while being scanned along the main scanning direction. Depending on the modulation state of the laser beam LB, a portion where the positive charges on the electrostatic latent image carrying surface LS disappear is generated. As a result, an electrostatic latent image having a positive charge pattern (image-like distribution) is formed on the electrostatic latent image carrying surface LS. The electrostatic latent image formed on the electrostatic latent image carrying surface LS moves toward the developing position DP facing the toner supply device 6 by the rotation of the photosensitive drum 3 in the direction indicated by the arrow in the drawing. .

<<< Conveyance and supply of charged toner >>>
2 and 3, the toner T stored in the toner box 61 is charged by contact with the transport electrode overcoating layer 634 on the bottom electric field transport substrate 63a, friction, or the like. The charged toner T that is in contact with or close to the bottom electric field transport substrate 63a is transported in the toner transport direction TTD by the electric field generated in response to the transport bias applied to the plurality of bottom transport electrodes 631a, and the electric field transport for supply is performed. It is delivered to the substrate 63b.

  The supply electric field transport substrate 63b is configured such that the toner T is transferred from the bottom electric field transport substrate 63a at the lower end thereof by the electric field generated by the application of the transport bias to the plurality of supply transport electrodes 631b. It is conveyed vertically upward from 61a toward the developing roller 62. Then, at the position where the supply electric field transport substrate 63b and the toner carrying surface 62a are close to each other, the positively charged toner T is transferred to the toner by the electric field formed between the supply electric field transport substrate 63b and the developing roller 62. It is carried on the carrying surface 62a.

  Here, the toner T transferred from the bottom electric field transfer substrate 63a to the supply electric field transfer substrate 63b has a poorly charged state (a reversely charged or negatively charged one, a low charged or an uncharged one) , Etc.) are mixed.

  However, in the configuration of the present embodiment, the toner is positively charged when being conveyed vertically upward by the supply electric field transfer substrate 63b or by the electric field formed between the supply electric field transfer substrate 63b and the developing roller 62. When T is carried on the toner carrying surface 62a, the toner T in a poorly charged state deviates from the toner conveyance path TTP due to gravity or the above-described electric field action, and falls downward from the supply electric field conveyance substrate 63b. To do.

  As a result, in the electric field transport substrate 63b for supply, the toner T having a good charge state and a poor charge state are properly selected. The toner T that deviates from the toner transport path TTP and falls downward from the supply electric field transport substrate 63b returns to the toner storage portion 61a. The toner T is again transported upward by the supply electric field transport substrate 63b.

  The toner T carried on the toner carrying surface 62a as described above is supplied to the developing position DP by reaching the developing position DP by the movement of the toner carrying surface 62a by the rotation of the developing roller 62. The electrostatic latent image formed on the electrostatic latent image carrying surface LS is developed with the toner T at the development position DP. That is, the toner T adheres to the portion on the electrostatic latent image carrying surface LS where the positive charge in the electrostatic latent image has disappeared. As a result, an image of toner T (hereinafter referred to as “toner image”) is carried on the electrostatic latent image carrying surface LS.

  The toner T on the toner carrying surface 62 a that has passed through the development position DP (not consumed at the development position DP) moves to a position facing the toner adhesion release wire 68 by the rotation driving of the development roller 62. Here, the toner T adheres firmly on the toner carrying surface 62a due to the mirror image force or van der Waals force.

  In this regard, in this embodiment, a developer adhesion release bias that is a two-phase AC voltage is applied to the plurality of toner adhesion release wires 68 so that adjacent toner adhesion release wires 68 are in opposite phases. ing. Therefore, the toner T carried on the toner carrying surface 62a floats well from the toner carrying surface 62a due to the electric field generated when the developer adhesion releasing bias is applied to the plurality of toner adhesion releasing wires 68. .

  In this way, the toner T that has floated from the toner carrying surface 62a is collected by the collecting electric field transport substrate 63c. The toner T is applied to the toner storage unit 61a by the electric field generated in response to the application of the recovery bias, which is a traveling-wave multiphase AC voltage, to the plurality of recovery transport electrodes 631c in the recovery electric field transport substrate 63c. It is conveyed vertically downward.

  At this time, the inertia in the same direction as the gravity acts on the toner T. Then, below the lower end portion of the recovery electric field transport substrate 63c, the toner T falls to the toner storage portion 61a by the action of gravity and inertia in the same direction as the gravity. Therefore, even if the collection electric field transport substrate 63c is not provided until it reaches the toner storage portion 61a, the toner T is favorably returned to the toner storage portion 61a.

<< Transfer of toner image from electrostatic latent image carrying surface to paper >>
Referring to FIG. 1, the toner image carried on the electrostatic latent image carrying surface LS of the photosensitive drum 3 as described above has a direction in which the electrostatic latent image carrying surface LS is indicated by an arrow in the drawing. Is conveyed toward the transfer position TP. At the transfer position TP, the toner image is transferred onto the paper P from the electrostatic latent image carrying surface LS.

<Effect by embodiment>
As described above, in the configuration of the present embodiment, the toner T firmly adhered on the toner carrying surface 62a by the mirror image force or van der Waals force is the position where the collection electric field transport substrate 63c and the developing roller 62 face each other. Thus, the electric field generated with the application of voltage to the toner adhesion releasing wire 68 floats well from the toner carrying surface 62a. As a result, the toner T on the toner carrying surface 62a that has passed through the developing position DP (not consumed at the developing position DP) can be recovered better.

  In addition, according to the configuration of the present embodiment, the bias voltage applied to the electric field transport substrate 63 can be further reduced (when there is no toner adhesion release wire 68, the toner carrying surface 62a that has passed through the development position DP). In order to sufficiently collect the toner T on the upper side, the DC offset of the transport bias is 1200 V and the DC offset of the developing bias is 1 kV, and the DC offset in the supply electric field transport substrate 63b becomes high. ).

  Furthermore, in the configuration of the present embodiment, a two-phase AC voltage is applied to the plurality of toner adhesion releasing wires 68 so that adjacent toner adhesion releasing wires 68 are in opposite phases. For this reason, when four or more toner adhesion releasing wires 68 are provided, an electric field that causes the toner T to float from the toner carrying surface 62a is alternately generated in the gap between adjacent wires. Therefore, according to the present embodiment, the recovery of the toner T on the toner carrying surface 62a can be performed more efficiently.

<List of examples of modification>
It should be noted that the above-described embodiment is merely an example of a representative specific example of the present invention that is considered best by the applicant 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 typical modifications will be exemplified. In the following description of the modified examples, the same reference numerals as those in the above embodiment can be used for members having the same configuration and function as those described in the above 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 in terms of action and function in each component constituting the means for solving the problems of the present invention) is based on the description of the above embodiment and the following modifications. It should not be interpreted in a limited way. 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. At this time, the shape of the photosensitive member may not be a drum shape as in the above-described embodiment. For example, a flat plate shape or an endless belt shape may be used. Further, as the exposure light source, other than the laser scanner (LED, EL (electroluminescence) element, phosphor, etc.) can be suitably used.

  Alternatively, the present invention is also suitably applied to an image forming apparatus of a system other than the above-described electrophotographic system (for example, a toner jet system that does not use a photoreceptor, an ion flow system, a multi-stylus electrode system, etc.). obtain.

  (2) The configuration of the electric field transport substrate 63 is not limited to that of the above-described embodiment. For example, the transport electrode overcoating layer 634 can be omitted. Alternatively, both the transport electrode coating layer 633 and the transport electrode overcoating layer 634 can be omitted by embedding the transport electrode 631 in the transport electrode support film 632.

  The center portion of the bottom electric field transport substrate 63a may be flat. That is, the curved portion of the bottom electric field transport substrate 63a may be only the connection portion with the lower end of the supply electric field transport substrate 63b. Further, the bottom electric field transport substrate 63a may be integrated with the supply electric field transport substrate 63b or may be a separate body.

  The supply electric field transport substrate 63b may be provided substantially upright along the vertical direction, and may be slightly inclined. Similarly, the recovery electric field transport substrate 63c may be slightly inclined. Further, the upper end portion of the electric field transport substrate 63b for supply can be formed in a flat plate shape. Similarly, the upper part of the recovery electric field transport substrate 63c can also be formed in a flat plate shape. In this case, the toner adhesion releasing wire 68 is provided at a position where the collection electric field transport substrate 63c and the toner carrying surface 62a are in close proximity to each other.

  The terminal portion of the collection electric field transport substrate 63c in the toner transport direction TTD may be connected to the bottom electric field transport substrate 63a. In this case, the bottom electric field transport substrate 63a may be integrated with the collection electric field transport substrate 63c or may be a separate body.

  (3) Referring to FIG. 4, the voltage waveform generated by each of the power supply circuits VA to VD may be an arbitrary waveform such as a sine wave shape or a triangular wave shape in addition to a rectangular wave shape. In the above-described embodiment, four power supply circuits VA to VD are provided, and the phases of the voltages generated by the power supply circuits VA to VD are different by 90 °. However, the present invention is not limited to this. That is, the multiphase AC voltage in the present invention is not limited to four phases. Therefore, for example, the toner supply device 6 may include three power supply circuits VA to VC whose phases are different by 120 °.

  (4) Other modifications not specifically mentioned are naturally included in the technical scope of the present invention within the scope not changing the essential part of the present invention. In addition, in each element constituting the means for solving the problems of the present invention, elements expressed functionally and functionally include the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function. Furthermore, the contents (including the specification and the drawings) of each publication cited in this specification can be incorporated as part of this specification.

DESCRIPTION OF SYMBOLS 1 ... Laser printer 2 ... Paper conveyance mechanism 3 ... Photosensitive drum (supply object) 4 ... Charger 5 ... Scanner unit 6 ... Toner supply apparatus (developer supply apparatus)
61: Toner box 61a: Toner reservoir (developer reservoir)
62 ... Developing roller (developer carrying member) 62a ... Toner carrying surface 63 ... Electric field carrying substrate 63a ... Bottom electric field carrying substrate 63b ... Electric field carrying substrate 63c ... Collection electric field carrying substrate 631 ... Conveying electrode 631a ... Bottom carrying electrode 631b ... supply electrode 631c ... recovery electrode 64 ... transfer bias power supply circuit 65 ... recovery bias power supply circuit 66 ... development bias power supply circuit 67 ... shielding plate 68 ... toner adhesion release wire 69 ... toner adhesion release power supply circuit DP ... Development position (developer supply position) LS ... Electrostatic latent image carrying surface T ... Toner TTP ... Toner transport path

JP-A-3-12678 JP 2008-70803 A

Claims (4)

In a developer supply device configured to supply a charged powdery developer to a supply target,
A developer carrying surface which is a cylindrical circumferential surface parallel to the main scanning direction, and the developer carrying surface is provided to face the supply target at the developer supply position; The developer carried on the developer carrying surface is supplied to the developer supply position while moving the developer carrying surface in a direction perpendicular to the main scanning direction by rotating about a parallel axis. A developer carrying member configured as described above,
Developer carrying means configured to carry the developer on the developer carrying surface upstream of the developer supply position in the moving direction of the developer carrying surface;
A plurality of recovery transport electrodes having a longitudinal direction along the main scanning direction and arranged in a direction crossing the main scanning direction are provided, and traveling wave-like multiphases to the plurality of recovery transport electrodes are provided. The developer is transported toward the developer reservoir by an electric field generated in response to application of a recovery bias that is an AC voltage, and the development is performed downstream of the developer supply position in the moving direction. An electric field transport substrate for recovery provided to face the agent carrying surface;
The developer carried between the developer carrying surface and the recovery electric field transport substrate facing each other, and the developer carried on the developer carrying surface by the electric field generated upon application of a voltage. A developer adhesion release electrode configured to float from the developer carrying surface;
A developer supply apparatus comprising: The developer supply device according to claim 1,
The developer supply device according to claim 1, wherein the developer adhesion releasing electrode is made of a wire stretched along the main scanning direction. The developer supply device according to claim 2,
A plurality of the wires are provided so as to be arranged along the recovery electric field transport substrate,
A developer supply apparatus, wherein a developer adhesion release bias, which is a two-phase AC voltage that causes adjacent wires to have opposite phases, is applied to the plurality of wires. The developer supply device according to any one of claims 1 to 3,
The developer carrying means is
A plurality of supply transport electrodes having a longitudinal direction along the main scanning direction and arranged in a direction crossing the main scan direction are provided, and a traveling wave-like multiphase to the plurality of supply transport electrodes The developer is configured to be transported in the developer transport direction from the developer reservoir to the developer carrying member by an electric field generated with application of a transport bias that is an AC voltage, and the developer transport direction. A developer supply apparatus comprising a supply electric field transport substrate provided so that a downstream end thereof faces the developer carrying surface.

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