JP4780165B2 - Developer supply device - Google Patents

Description

  The present invention relates to a developer supply device configured to supply a charged powdery developer to a supply target while being conveyed along a predetermined developer conveyance path by an electric field.

In this type of apparatus, there is known an apparatus including two transport substrates each having a plurality of electrodes for forming a traveling wave electric field, and arranged so as to face each other (for example, Japanese Patent Laid-Open No. 2002-2002). No. 287484, JP-A No. 2002-351218, JP-A No. 2008-96905, etc.).
JP 2002-287484 A JP 2002-351218 A JP 2008-96905 A

  In the configuration described above, when the traveling wave electric field is not properly generated on one transport substrate and the other transport substrate, the developer is not properly supplied to the supply target. May occur.

  The present invention has been made to cope with such a problem. That is, an object of the present invention is to provide a developer supply device that can satisfactorily suppress the occurrence of white background fog in a formed image.

  The developer supply device of the present invention is configured to supply a charged powdery developer to a supply target while being conveyed along a predetermined developer conveyance path by an electric field. Specifically, the developer supply device includes a transport electrode substrate and a counter electrode substrate.

  The transport electrode substrate is a thin plate-like member and is disposed so as to face the supply target. The transport electrode substrate includes a plurality of transport electrodes. The plurality of transport electrodes are arranged along the developer transport path (including a supply position for supplying the developer to the supply target).

  The counter electrode substrate is a thin plate-like member, and is disposed closer to the supply object than the transport electrode substrate so as to face the transport electrode substrate with the developer transport path in between. The counter electrode substrate includes a plurality of counter electrodes. The plurality of counter electrodes are arranged along the developer transport path.

  In the developer supply device, the developer is supplied at the supply position in a direction orthogonal to the developer transfer direction at the supply position (that is, the transfer electrode substrate and the counter electrode substrate are at the supply position). It may be configured to supply to the supply target along the (opposite direction).

  A feature of the present invention is that, when viewed along the transport direction, the developer electrode path is adjacent to the supply position on the near side in the transport direction from the supply position. The phase of the carrier voltage, which is an applied multiphase alternating voltage, advances in a range less than a half wavelength than the phase of the counter voltage, which is a multiphase alternating voltage applied to the counter electrode substrate having the same wavelength as the carrier voltage. It is in that.

  Specifically, for example, the transport electrode substrate and the counter electrode substrate are configured and arranged so that the transport electrode having the same potential as the counter electrode is displaced in the transport direction from the counter electrode. obtain.

Alternatively, for example, the transport electrode substrate and the counter electrode substrate have a flat plate shape parallel to each other, and the transport electrode and the counter electrode are provided at equal intervals with the same width in the transport direction (that is, the transport Regarding the direction, the widths of the plurality of transport electrodes are approximately equal, the widths of the plurality of counter electrodes are approximately equal, the plurality of transport electrodes are provided at equal intervals, and the plurality of counter electrodes are spaced from each other between the transport electrodes. Are assumed to be equally spaced at the same interval.)
When the amount of displacement between the transport electrode and the counter electrode having the same potential is Δ,
0 <Δ <Dpp · Np / 2
(Dpp is the pitch between the electrodes in the transport direction of the transport electrode and the counter electrode, and Np is the number of voltage phases in the transport voltage and the counter voltage)
The transport electrode substrate and the counter electrode substrate may be configured and arranged so as to satisfy the above.

Alternatively, for example, the transport electrode and the counter electrode are formed at the same pitch in the transport direction, and the transport electrode substrate and the counter electrode substrate are bent in a concentric arc shape in a side sectional view, and the counter electrode substrate Is assumed to be disposed outside the transport electrode substrate,
The portion of the developer transport path adjacent to the supply position on the near side in the transport direction from the supply position is
(K−1 / 2) α <θ <kα
(Θ is the central angle of the concentric arc from the position toward the transport direction with respect to the position where the transport electrode and the counter electrode having the same potential coincide in the radial direction of the concentric arc, and α is the same potential. The central angle of the concentric arc at the position where the transport electrode and the counter electrode coincide with θ = 0 next in the radial direction of the concentric arc, k is an integer of 1 or more)
The transport electrode substrate and the counter electrode substrate can be configured and arranged so as to fall within the range of θ indicated by.

  According to the developer supply apparatus of the present invention having such a configuration, the ratio of the developer is lower in the region floating from the surface than in the vicinity of the surface of the transport electrode substrate (this is a computer simulation). Can be easily confirmed). Thereby, excessive supply of the developer to the supply target can be suppressed. Therefore, the occurrence of white background fog in the formed image can be suppressed satisfactorily.

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

  In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in.

  Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Various modifications that can be made to the present embodiment are listed together at the end, as they would interfere with the understanding of the consistent description of the embodiment if inserted during the description of the embodiment. .

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

  First, the overall configuration of the laser printer 1 will be described with reference to FIG. 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 discharge the paper P from the above-described paper feed tray and to transport the paper P along a predetermined paper transport path PP.

  An electrostatic latent image carrying surface LS is provided on the outer peripheral surface of the photosensitive drum 3 as a supply target of the present invention. The electrostatic latent image carrying surface LS is formed in a cylindrical surface parallel to the main scanning direction (z-axis direction in the figure).

  On the photosensitive drum 3, an electrostatic latent image based on a positive charge distribution is formed on the electrostatic latent image carrying surface LS, and a positively charged powdery toner (dry developer) corresponds to the electrostatic latent image. It is comprised so that it may be carry | supported by the position.

  Further, the photosensitive drum 3 is driven to rotate in a direction indicated by an arrow (clockwise in FIG. 1) around a central axis C parallel to the main scanning direction. That is, the photosensitive drum 3 is configured such that the electrostatic latent image carrying surface LS can move along a sub-scanning direction (typically, the x-axis direction in the drawing) orthogonal to the main scanning direction.

  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 as to uniformly positively charge the electrostatic latent image carrying surface LS before forming the electrostatic latent image.

  The scanner unit 5 generates a laser beam LB having a predetermined wavelength band that is modulated based on image data (the ON / OFF of light emission is controlled according to the presence or absence of pixels), and the laser beam LB is statically generated. An image is formed (exposed) at the scan position SP on the electrostatic latent image carrying surface LS. Here, the scan position SP is provided at a position downstream of the charger 4 in the rotation direction of the photosensitive drum 3 (direction indicated by the arrow in FIG. 1: clockwise in the drawing).

  Further, the scanner unit 5 moves the position where the laser beam LB is imaged at a constant speed along the main scanning direction on the electrostatic latent image carrying surface LS uniformly charged by the charger 4. By performing (scanning), an electrostatic latent image can be formed on the electrostatic latent image carrying surface LS.

  The toner supply device 6 is disposed so as to face the photosensitive drum 3. The toner supply device 6 as the developer supply device of the present invention is configured to be able to supply the electrostatic latent image carrying surface LS in a charged state at the development position DP. The detailed configuration of the toner supply device 6 will be described later.

<Configuration of each part of the laser printer>
Next, a specific configuration of each part of the laser printer 1 will be described in detail.

<< paper transport mechanism >>
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. The transfer roller 22 is configured to be rotationally driven in a direction (counterclockwise) indicated by an arrow in the drawing.

  The transfer roller 22 is connected to a bias power supply circuit (not shown). That is, a predetermined transfer bias voltage for transferring the toner attached on the electrostatic latent image carrying surface LS to the paper P is applied between the transfer roller 22 and the photosensitive drum 3.

<< Photosensitive drum >>
FIG. 2 is an enlarged side sectional view of a portion where the photosensitive drum 3 and the toner supply device 6 shown in FIG. 1 face each other.

  Referring to FIG. 2, the photosensitive drum 3 includes a drum body 31 and a photosensitive layer 32.

  The drum body 31 is a cylindrical member parallel to the z-axis in the drawing, and is made of a metal such as aluminum. The drum body 31 is electrically grounded.

  The photosensitive layer 32 is provided so as to cover the outer periphery of the drum body 31. The photosensitive layer 32 is composed of a positively chargeable photoconductive layer that exhibits electron conductivity when exposed to laser light having a predetermined wavelength.

  The electrostatic latent image carrying surface LS is constituted by the outer peripheral surface of the photosensitive layer 32. That is, after being uniformly positively charged by the charger 4 (see FIG. 1), the laser beam LB is scanned at the scan position SP, thereby forming an electrostatic latent image LI having a positive charge pattern. Thus, the electrostatic latent image carrying surface LS (photosensitive layer 32) is configured.

<< Toner Supply Device >>
As described above, the toner supply device 6 transports the charged powdery toner T along the toner transport path TTP by an electric field, and in a direction orthogonal to the toner transport path TTP at the development position DP (to the development position DP). In addition, it is configured to be supplied to the photosensitive drum 3 as a supply target by flying along a transport electrode substrate 63 and a counter electrode substrate 64 (to be described later) facing each other. The toner transport path TTP is a transport path of the toner T by a traveling wave electric field, and is substantially oval in a sectional side view including the developing position DP inside the toner box 61 that forms the casing of the toner supply device 6. It shall be formed in the shape.

  Specifically, referring to FIG. 2, the toner box 61 that forms the casing of the toner supply device 6 is a box-shaped member that can store therein toner T as a fine dry developer. It is configured. In this embodiment, it is assumed that the toner T is a positively chargeable, non-magnetic single component black toner.

  A top plate 61 a in the toner box 61 is a flat plate member having a rectangular shape in plan view, and is disposed so as to be close to the photosensitive drum 3.

  In the top plate 61a, a toner passage hole 61a1 is formed as a through hole through which the toner T can pass when moving from the inside of the toner box 61 toward the photosensitive layer 32 along the y-axis direction in the figure. The toner passage hole 61a1 has a long side having a length substantially the same as the width of the photosensitive layer 32 in the main scanning direction (z-axis direction in the drawing) in a plan view and the sub-scanning direction (x-axis direction in the drawing). ) And a rectangular shape having a short side parallel to.

  The toner passage hole 61a1 is provided in the vicinity of the position where the top plate 61a and the photosensitive layer 32 are closest to each other. Further, the toner passage hole 61a1 is formed such that the center in the sub-scanning direction (x-axis direction in the figure) is substantially coincident with the developing position DP.

  A transport electrode substrate support member 62 is provided inside the toner box 61 so as to face the top plate 61 a of the toner box 61. The above-described transport electrode substrate 63 is supported on the surface of the transport electrode substrate support member 62 on the side facing the top plate 61a. That is, the transport electrode substrate 63 is provided to face the photosensitive drum 3 with the toner transport path TTP interposed therebetween.

<<< Transport electrode substrate / counter electrode substrate >>>
FIG. 3 is an enlarged side sectional view of the transport electrode substrate 63 shown in FIG.

  Referring to FIG. 3, the transport electrode substrate 63 is a thin plate-like member and has the same configuration as the flexible printed wiring board. Specifically, the transport electrode substrate 63 includes a transport electrode 63a, a transport electrode support film 63b, a transport electrode coating layer 63c, and a transport electrode overcoating layer 63d.

  The transport electrode 63a is formed as a linear wiring pattern having a longitudinal direction parallel to the main scanning direction. Specifically, the transport electrode 63a is made of a copper foil having a thickness of about several tens of μm. The plurality of transport electrodes 63a are arranged in parallel to each other. These transport electrodes 63a are arranged along the sub-scanning direction.

  Further, the transport electrode 63a is disposed along the toner transport surface TTS that is the surface of the transport electrode substrate 63 facing the toner transport path TTP (see FIG. 2). That is, the transport electrode 63a is disposed along the toner transport path TTP (see FIG. 2) in the vicinity of the toner transport surface TTS.

  Each of the plurality of transport electrodes 63a arranged in the sub-scanning direction is connected to the same power supply circuit every third. That is, the transfer electrode 63a connected to the power supply circuit VA, the transfer electrode 63a connected to the power supply circuit VB, the transfer electrode 63a connected to the power supply circuit VC, the transfer electrode 63a connected to the power supply circuit VD, and the power supply circuit VA. The connected transport electrodes 63a, the transport electrodes 63a connected to the power supply circuit VB, the transport electrodes 63a connected to the power supply circuit VC are arranged in order along the sub-scanning direction.

  Here, each of the power supply circuits VA to VD is configured to output an alternating voltage (carrier 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 ° (1/4 wavelength) in order from the power supply circuit VA to the power supply circuit VD.

  As described above, in the transport electrode substrate 63 in the present embodiment, the above-described four-phase transport voltage is applied to each transport electrode 63a, and a traveling-wave electric field along the sub-scanning direction is generated. Thus, the positively charged toner T can be transported in the toner transport direction TTD parallel to the toner transport surface TTS.

  The plurality of transport electrodes 63a are formed on the surface of the transport electrode support film 63b. The transport electrode support film 63b is a flexible film and is made of an insulating synthetic resin such as a polyimide resin.

  The transport electrode coating layer 63c is made of an insulating synthetic resin. The transport electrode coating layer 63c is provided so as to cover the surface of the transport electrode support film 63b on which the transport electrode 63a is provided and the transport electrode 63a.

  A transport electrode overcoating layer 63d is provided on the transport electrode coating layer 63c. That is, the above-described transport electrode coating layer 63c is formed between the transport electrode overcoating layer 63d and the transport electrode 63a.

  The above-described toner transport surface TTS is made of the surface of the transport electrode overcoating layer 63d and is formed as a smooth surface with very few irregularities.

  Referring to FIG. 2 again, the above-described counter electrode substrate 64 is provided inside the toner box 61. The counter electrode substrate 64 is supported on the inner surface of the top plate 61a in the toner box 61 so as to face the toner transport path TTP. That is, the counter electrode substrate 64 is disposed on the photosensitive drum 3 side with respect to the transport electrode substrate 63 so as to face the transport electrode substrate 63 with the toner transport path TTP interposed therebetween.

  The counter electrode substrate 64 is a thin plate-like member and has the same configuration as that of the flexible printed wiring board, like the transport electrode substrate 63. Specifically, the counter electrode substrate 64 includes a plurality of counter electrodes 64a (see FIG. 6) arranged along the toner transport path TTP.

  In the present embodiment, the counter electrode substrate 64 is applied with a counter voltage, which is an alternating voltage of four phases, similar to the above-described transport electrode substrate 63, and a traveling wave electric field along the sub-scanning direction is generated. The positively charged toner T can be transported in the toner transport direction TTD parallel to the toner transport surface TTS.

  The control unit 65 is electrically connected to each unit (drive unit, power supply circuit, etc.) provided in the laser printer 1 and is configured to control its operation.

  In the present embodiment, the transport voltage at a portion adjacent to the development position DP on the front side (upstream side) in the toner transport direction TTD from the toner passage hole 61a1 (a portion on the left side of the toner passage hole 61a1 in FIG. 2). Is advanced in a range of less than a half wavelength with respect to the phase of the counter voltage (details will be described later).

  Here, the carrier voltage is a multiphase alternating voltage applied to the carrier electrode substrate 63. Further, the counter voltage is a multiphase alternating voltage applied to the counter electrode substrate 64, and in this embodiment, has the same wavelength as the carrier voltage.

<Overview 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 opposed to the scanner unit 5 (opposite) by the rotation of the photosensitive drum 3 in the direction (clockwise) indicated by the arrow in the drawing. It moves along the sub-scanning direction to a certain scanning position SP.

  Referring to FIG. 2, a laser beam LB modulated based on image information is irradiated onto the electrostatic latent image carrying surface LS at the scan position SP 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 LI having a positive charge pattern (image-like distribution) is formed on the electrostatic latent image carrying surface LS.

  The electrostatic latent image LI formed on the electrostatic latent image carrying surface LS is developed at the development position DP facing the toner supply device 6 by the rotation of the photosensitive drum 3 in the direction indicated by the arrow (clockwise) in the drawing. Move towards.

<<< Conveyance and supply of charged toner >>>
A traveling wave carrier voltage is applied to the carrier electrode substrate 63, and a traveling wave counter voltage is applied to the counter electrode substrate 64. As a result, a predetermined traveling-wave electric field is formed in the toner transport path TTP. By this traveling wave electric field, the positively charged toner T is transported in the toner transport direction TTD along the toner transport path TTP.

  FIG. 4 is a graph showing waveforms of voltages generated by the power supply circuits VA to VD shown in FIG. 5A to 5C are enlarged side sectional views showing the periphery of the toner transport surface TTS in the transport electrode substrate 63 shown in FIG. Note that the transport electrode 63a connected to the power supply circuit VA in FIG. 3 is shown as the transport electrode 63aA in FIGS. 5A to 5C. The same applies to the transport electrodes 63aB to 63aD.

  Hereinafter, how the positively charged toner T is transported in the toner transport direction TTD on the toner transport surface TTS will be described with reference to FIGS. 4 and 5A to 5C.

  As shown in FIG. 4, alternating voltages having substantially the same waveform are output from the power supply circuits VA to VD so that the phase is delayed by 90 ° in the order from the power supply circuit VA to the power supply circuit VD.

  At time t1 in FIG. 4, as shown in FIG. 5A, an electric field EF1 opposite to the toner transport direction TTD is formed at the position AB between the transport electrode 63aA and the transport electrode 63aB. Is done.

  On the other hand, an electric field EF2 having the same direction as the toner transport direction TTD is formed at the inter-CD position between the transport electrode 63aC and the transport electrode 63aD.

  Further, the position between BC, which is the position between the transport electrode 63aB and the transport electrode 63aC, and the position between DA, which is the position between the transport electrode 63aD and the transport electrode 63aA, are in the direction along the toner transport direction TTD. An electric field is not formed.

  That is, at time t1, the positively charged toner T receives an electrostatic force in the direction opposite to the toner transport direction TTD at the position between AB.

  Further, at the position between BC and the position between DA, the positively charged toner T receives almost no electrostatic force in the direction along the toner transport direction TTD.

  Further, at the position between the CDs, the positively charged toner T receives an electrostatic force in the same direction as the toner transport direction TTD.

  Therefore, at time t1, the positively charged toner T is collected at the position between the DAs.

  Similarly, at time t2, as shown in FIG. 5B, the positively charged toner T is collected at the position between AB. Next, at time t3, as shown in FIG. 5C, the positively charged toner T is collected at the position between BC.

  That is, the area where the toner T is collected moves on the toner transport surface TTS in the toner transport direction TTD with the passage of time.

  Referring to FIG. 2 again, as described above, the transfer voltage as shown in FIG. 4 is applied to the transfer electrode substrate 63, and the above-mentioned is similarly applied to the counter electrode substrate 64. Such a counter voltage is applied. As a result, a traveling-wave electric field is formed in the toner transport path TTP, and the positively charged toner T is transported in the toner transport direction TTD while hopping along a direction orthogonal to the toner transport surface TTS.

<<< Development of electrostatic latent image >>>
As described above, the positively charged toner T is supplied to the development position DP.

  The electrostatic latent image LI 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 a portion on the electrostatic latent image carrying surface LS where the positive charge in the electrostatic latent image LI 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.

<< Transfer of toner image from electrostatic latent image carrying surface to paper >>
Referring to FIG. 1 again, in the toner image carried on the electrostatic latent image carrying surface LS of the photosensitive drum 3 as described above, the electrostatic latent image carrying surface LS is indicated by an arrow in the drawing. By rotating in the direction (clockwise), the sheet 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.

<Operation / Effects of Configuration of Embodiment>
6 is an enlarged view of a portion of the transport electrode substrate 63 and the counter electrode substrate 64 shown in FIG. 2 adjacent to the developing position DP on the front side (upstream side) in the toner transport direction TTD from the toner passage hole 61a1. FIG. That is, the toner passage hole 61a1 in FIG. 2 is provided so as to be adjacent to the right edge of the counter electrode substrate 64 in FIG.

  Here, in FIG. 6, the transport electrode substrate 63 and the counter electrode substrate 64 are configured in a substantially flat plate shape, and the transport electrode 63 a and the counter electrode 64 a are provided at equal intervals with the same width in the toner transport direction TTD. It shall be. In addition, it is assumed that electrodes painted in the same color are set to the same potential.

  In FIG. 6, (i) and (iii) show a configuration in the case where the transport electrode 63a and the counter electrode 64a are provided at the same position in the toner transport direction TTD. On the other hand, (ii) and (iv) show a configuration in which the transport electrode 63a and the counter electrode 64a are provided at alternate positions in the toner transport direction TTD.

  Also, in the figure, (i) shows a case where the phase of the transport voltage and the counter voltage in the toner transport direction TTD match. On the other hand, in (ii) to (iv), the phase of the transport voltage is opposite because the transport electrode 63a having the same potential as the counter electrode 64a is displaced to the opposite side of the toner transport direction TTD from the counter electrode 64a. The case where it lags behind the phase of a voltage is shown.

  7 to 11 are diagrams showing the results of calculating the electric field corresponding to the configuration shown in FIG. 6 by the finite element method. 7 to 11, the direction and magnitude of the electric field are indicated by arrows. The white portion is a high potential portion, and the lower the potential is, the higher the concentration is.

The calculation conditions are as follows.
Distance between substrates: 0.5mm
Electrode width: 100 μm
Distance between electrodes: 100 μm
Applied voltage: Square wave voltage plus or minus 300V Frequency: 1000Hz

  7 corresponds to (i) in FIG. 6, FIG. 8 corresponds to (ii), FIG. 9 corresponds to (iii), and FIG. 10 corresponds to (iv). FIG. 11 corresponds to the case where the phase of the conveyance voltage is reversed from the phase of the counter voltage by the displacement of the conveyance electrode 63a further to the opposite side of the toner conveyance direction TTD than in (iv) in FIG.

  6 (i) and FIG. 7 show that there is no deviation between the carrier voltage and the counter voltage. FIG. 6 (ii) and FIG. 8 show that the carrier voltage is delayed by 1/8 wavelength (7/8 wavelength advance). (Iii) and FIG. 9 in FIG. 6 show that the carrier voltage is delayed by 2/8 wavelength (6/8 wavelength advances), and in FIG. 6 (iv) and FIG. FIG. 11 corresponds to the case where the carrier voltage is delayed by 4/8 wavelength (advanced by 4/8 wavelength), respectively.

  FIG. 12A is a diagram showing the behavior of the toner in the case of FIG. In FIG. 12A, it is assumed that the toner aggregate is shown as an ellipse.

  Positively charged toner collects at a position between adjacent electrodes set at the lowest potential along the toner transport direction TTD. Therefore, immediately before the time when the potential state of each electrode shown in FIG. 7 to FIG. 11 is reached, between the electrode that changes from the low potential to the high potential at that time and the electrode that is maintained at the low potential. The toner is located in the vicinity of the surfaces of the transport electrode substrate 63 and the counter electrode substrate 64 (see the broken oval shape in FIG. 12A).

  At the above time, the toner moves (flys) along the toner transport direction TTD by an electric field along the toner transport direction TTD generated between electrodes of different potentials adjacent along the toner transport direction TTD. To do.

  As shown in FIG. 7, even when there is no deviation between the transport voltage and the counter voltage, the toner travels in the toner transport direction TTD between the electrodes having different potentials along the toner transport direction TTD. At the same time, an oblique electric field is generated which also goes to the intermediate position between the transport electrode substrate 63 and the counter electrode substrate 64. Due to this electric field, the toner on the transport electrode substrate 63 moves obliquely in the upper right direction in the figure. Similarly, the toner near the surface of the counter electrode substrate 64 moves in the diagonally lower right direction in the drawing.

  In this regard, as shown in FIG. 8, when the transport voltage is delayed by 1/8 wavelength (advanced by 7/8 wavelength), the toner on the transport electrode substrate 63 moves more upward. An electric field is generated. That is, as shown in FIGS. 8 and 12A, in the direction in which the toner on the transport electrode substrate 63 moves, the counter electrode 64a to which a counter voltage that attracts the toner is applied (the black upper right in the figure). Painted). For this reason, the toner flies higher than in the case of FIG.

  On the other hand, in the direction in which the toner in the vicinity of the surface of the counter electrode substrate 64 moves, as shown in FIGS. 8 and 12A, a transport electrode 63a to which a transport voltage for spreading the toner is applied (in the figure). There is a white one in the lower right). For this reason, the degree of flying downward of the toner is more relaxed than in the case of FIG.

  Therefore, as described above, when the carrier voltage is delayed by 1/8 wavelength (advanced by 7/8 wavelength) as shown in (i) of FIG. 6 and FIG. 8, the case of FIG. In this case, the toner is located on the counter electrode substrate 64 side (that is, the upper side in the drawing).

  Further, as shown in FIG. 6 (iii) and FIG. 9, when the carrier voltage is delayed by 2/8 wavelength (advanced by 6/8 wavelength), the case of FIG. In other words, the toner is positioned closer to the counter electrode substrate 64 (that is, upward in the drawing).

  When the carrier voltage is delayed by 3/8 wavelength (advanced by 5/8 wavelength) as shown in (iv) and FIG. 10 in FIG. 6, the toner is more opposed than in the case of FIG. Although it is located on the electrode substrate 64 side (that is, the upper side in the drawing), the influence of the counter voltage that produces the toner is slightly exerted on the destination where the toner on the transport electrode substrate 63 moves. Therefore, when the carrier voltage is delayed by 3/8 wavelength (5/8 wavelength advanced), the carrier voltage is delayed by 1/8 to 2/8 wavelength (6/8 to 7/8 wavelength advanced). ), The degree to which the toner is positioned closer to the counter electrode substrate 64 is slightly relaxed.

  When the transport voltage is delayed by 4/8 wavelength (advanced by 4/8 wavelength) as shown in FIG. 11, the toner on the transport electrode substrate 63 is moved in the moving direction. The influence of the counter voltage is strongly exerted. Therefore, it becomes difficult for the toner to go upward.

  Here, as shown in FIG. 12B, the region between the transport electrode substrate 63 and the counter electrode substrate 64 (toner transport region) is a direction in which the transport electrode substrate 63 and the counter electrode substrate 64 face each other (see FIG. 12B). In the case of being divided into four equal parts (in the middle and up and down directions), the lower side in the intermediate area is Area1 and the upper side is Area2.

  FIG. 13 is a diagram illustrating a result of toner particle behavior simulation. In FIG. 13, the toner presence ratio in Area 1 and Area 2 is shown for each degree of deviation between the transport voltage and the counter voltage.

The simulation conditions are as follows in addition to the above calculation conditions.
Number of particles: 2000 (initial state: on transport electrode substrate 63)
Particle radius: 5μm
Particle charge: 5μC
Elapsed time from the initial state: 8msec

As shown in FIG. 13, when the transport voltage advances in a range less than a half wavelength than the counter voltage, that is, the development position DP on the front side (upstream side) in the toner transport direction TTD from the toner passage hole 61a1. If the amount of displacement in the toner transport direction TTD between the transport electrode 63a and the counter electrode 64a at the same potential in the portion adjacent to is
0 <Δ <Dpp · Np / 2
(Dpp is the inter-electrode pitch of the transport electrode 63a and the counter electrode 64a in the toner transport direction, and Np is the number of voltage phases at the transport voltage and the counter voltage)
When the transport electrode substrate 63 and the counter electrode substrate 64 are configured and arranged so as to satisfy the above, the toner existing ratio in the upper intermediate area Area2 is lower than that in the lower intermediate area Area1. Thereby, when the toner reaches the toner passage hole 61a1, the rising of the toner can be suppressed as much as possible. Therefore, the occurrence of white background fog in the formed image can be suppressed satisfactorily.

  FIG. 14 schematically shows a case where the transport electrode substrate 63 and the counter electrode substrate 64 are provided to be bent concentrically in a side sectional view, and the counter electrode substrate 64 is disposed outside the transport electrode substrate 63. It is a block diagram. Also in this case, it is assumed that the transport electrode 63a and the counter electrode 64a (see FIG. 6) are formed with the same width and the same pitch.

  In FIG. 14, θ is a reference (0 [rad]) when a certain position (angle) at which the phase of the applied voltage matches between the transport electrode substrate 63 and the counter electrode substrate 64 in the radial direction of the concentric arc. , The central angle [rad] of the concentric arc toward the toner transport direction TTD. Α is an angle at which the phase of the applied voltage coincides between the transport electrode substrate 63 and the counter electrode substrate 64 after θ = 0.

The length Lin of the transport electrode substrate 63 in the range of θ from 0 to θ1 is expressed as follows:
Lin = 2πRin × θ1 / 2π
It becomes.

Similarly, the length Lout of the counter electrode substrate 64 in the same range is defined as Rout.
Lout = 2πRout × θ1 / 2π
It becomes.

Therefore, the difference ΔL in length between the transport electrode substrate 63 and the counter electrode substrate 64 in the same range is
ΔL = Lout−Lin = (Rout−Rin) θ1
It becomes.

Here, the distance at which the applied voltage is one cycle in the transport electrode substrate 63 and the counter electrode substrate 64 is L. Specifically, for example, when electrode width: 100 μm, distance between electrodes: 100 μm, number of phases of carrier voltage and counter voltage: 4 phases,
L = (100 μm + 100 μm) × 4 = 800 μm
It becomes.

Since ΔL = L when θ1 = α, from the above equations,
α = L / (Rout−Rin)
It becomes.

  In the case of the configuration shown in FIG. 14, in order to obtain the same effect as the above-described flat configuration, the toner passing hole 61a1 (see FIG. 2) including the developing position DP on the front side in the toner transport direction TTD is provided. The adjacent toner transport path TTP is

(K−1 / 2) α <θ <kα
The transport electrode substrate 63 and the counter electrode substrate 64 are configured and arranged so as to be within the range of θ indicated by. That is, an edge adjacent to the toner passage hole 61a1 in the counter electrode substrate 64 is provided in the range of θ.

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

  Hereinafter, some 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.

  However, it goes without saying that 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.

  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) Referring to FIG. 3, the configurations of the transport electrode substrate 63 and the counter electrode substrate 64 are not limited to those of the above-described embodiment.

  For example, the transport electrode overcoating layer 63d can be omitted. Alternatively, both the transport electrode coating layer 63c and the transport electrode overcoating layer 63d can be omitted by embedding the transport electrode 63a in the transport electrode support film 63b.

  Further, the transport electrode 63a may be provided so as to intersect the main scanning direction at a predetermined small angle (for example, 5 to 30 degrees).

  Further, the gap between the adjacent transport electrodes 63a may be set to be equal to the electrode width as in the above-described embodiment, or may be set to be different from the electrode width. Also good.

  (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, and for example, three power supply circuits may be provided, and the phases of the voltages generated by the respective power supply circuits may be different by 120 °.

  (4) In the above-described embodiment, the phase relationship between the transport voltage and the counter voltage is adjusted by adjusting the positional relationship between the transport electrode 63a and the counter electrode 64a in the toner transport direction TTD. However, the present invention is not limited to such an embodiment.

  That is, for example, as is apparent from the correspondence relationship in FIGS. 7, 9, and 11, the transport electrode substrate 63 and the counter electrode are arranged so that the transport electrode 63a and the counter electrode 64a facing each other substantially coincide with each other in the toner transport direction TTD. Even if the substrate 64 is configured and arranged, the same operation and effect can be achieved by appropriately changing the output timing of the carrier voltage and the counter voltage.

  (5) In addition, although there is no limit, it will not be mentioned every time, but various modifications other than these can be made without departing from the gist 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.

1 is a side view showing a schematic configuration of a laser printer to which an embodiment of the present invention is applied. FIG. 2 is an enlarged side cross-sectional view of a portion where the photosensitive drum and the toner supply device shown in FIG. 1 face each other. FIG. 3 is an enlarged side sectional view of a transport electrode substrate shown in FIG. 2. FIG. 4 is a graph showing a waveform of a voltage generated by the power supply circuit shown in FIG. 3. FIG. 4 is an enlarged side sectional view showing a periphery of a toner transport surface TTS in the transport electrode substrate shown in FIG. 3. FIG. 4 is an enlarged side sectional view showing a periphery of a toner transport surface TTS in the transport electrode substrate shown in FIG. 3. FIG. 4 is an enlarged side sectional view showing a periphery of a toner transport surface TTS in the transport electrode substrate shown in FIG. 3. FIG. 3 is an enlarged cross-sectional view of a portion adjacent to the development position on the near side (upstream side) in the toner transport direction from the toner passage hole of the transport electrode substrate and the counter electrode substrate shown in FIG. 2. It is a figure which shows the result of having calculated the electric field corresponding to the structure shown by FIG. 6 by the finite element method. It is a figure which shows the result of having calculated the electric field corresponding to the structure shown by FIG. 6 by the finite element method. It is a figure which shows the result of having calculated the electric field corresponding to the structure shown by FIG. 6 by the finite element method. It is a figure which shows the result of having calculated the electric field corresponding to the structure shown by FIG. 6 by the finite element method. It is a figure which shows the result of having calculated the electric field corresponding to the structure shown by FIG. 6 by the finite element method. FIG. 9 is a diagram illustrating the behavior of toner in the case of FIG. 8. The figure which shows an upper side middle region and a lower side middle region when the toner conveyance area | region which is an area | region between a conveyance electrode board | substrate and a counter electrode board | substrate is equally divided into 4 in the direction where a conveyance electrode board | substrate and a counter electrode board | substrate oppose. It is. It is a figure which shows the result of a toner particle behavior simulation. FIG. 5 is a schematic configuration diagram in the case where the transport electrode substrate and the counter electrode substrate are provided to be bent concentrically in a side sectional view, and the counter electrode substrate is disposed outside the transport electrode substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser printer 2 ... Paper conveyance mechanism 3 ... Photosensitive drum (supply object)
4 ... Charger 5 ... Scanner unit 6 ... Toner supply device (developer supply device)
DESCRIPTION OF SYMBOLS 21 ... Registration roller 22 ... Transfer roller 31 ... Drum body 32 ... Photosensitive layer 61 ... Toner box 61a ... Top plate 61a1 ... Toner passage hole 62 ... Conveyance electrode substrate support member 63 ... Conveyance electrode substrate 63a ... Conveyance electrode 63b ... Conveyance electrode support film 63c ... Transport electrode coating layer 63d ... Transport electrode overcoating layer 64 ... Counter electrode substrate 64a ... Counter electrode 65 ... Control unit C ... Center axis DP ... Development position (supply position)
LB ... Laser beam LI ... Electrostatic latent image LS ... Electrostatic latent image carrying surface P ... Paper PP ... Paper transport path SP ... Scan position T ... Toner TP ... Transfer position TTD ... Toner transport direction TTP ... Toner transport path TTS ... Toner Transport surface

Claims (5)

In the developer supply apparatus configured to supply the charged powdery developer to the supply target while being transported along a predetermined developer transport path by an electric field.
A thin plate having a plurality of transport electrodes arranged to face the supply target and arranged along the developer transport path including a supply position for supplying the developer to the supply target A transfer electrode substrate,
A plurality of counter electrodes arranged along the developer transport path are arranged on the supply target side of the transport electrode substrate so as to face the transport electrode substrate across the developer transport path. A thin plate-like counter electrode substrate;
Equipped with a,
The transport electrode and the counter electrode are formed at the same pitch with respect to the developer transport path,
A transport voltage, which is a rectangular wave-shaped multiphase alternating voltage, is applied to the transport electrode substrate at a portion of the developer transport path adjacent to the supply position on the near side in the developer transport direction from the supply position. In this case, the potential state along the transport direction of the plurality of transport electrodes is defined as a first wave along the transport direction, and a counter voltage that is a rectangular wave-shaped multiphase alternating voltage is applied to the counter electrode substrate. When the state of the potential along the transport direction of the plurality of counter electrodes is the second wave along the transport direction, the first wave has the same wavelength as the second wave. A developer supply device, wherein the developer supply device is configured to travel in a range of less than half a wavelength. The developer supply device according to claim 1 ,
The transport electrode substrate and the counter electrode substrate are configured and arranged so that the transport electrode having the same potential as the counter electrode is displaced in the transport direction from the counter electrode. Developer supply device.   In the developer supply apparatus configured to supply the charged powdery developer to the supply target while being transported along a predetermined developer transport path by an electric field.
  A thin plate having a plurality of transport electrodes arranged to face the supply target and arranged along the developer transport path including a supply position for supplying the developer to the supply target A transfer electrode substrate,
  A plurality of counter electrodes arranged along the developer transport path are arranged on the supply target side of the transport electrode substrate so as to face the transport electrode substrate across the developer transport path. A thin plate-like counter electrode substrate;
  With
  When the transport electrode substrate and the counter electrode substrate have a flat plate shape parallel to each other, and the transport electrode and the counter electrode are provided at the same width and at equal intervals in the developer transport direction,
  The amount of displacement along the developer transport path between the transport electrode and the counter electrode having the same potential, where the transport electrode is displaced with respect to the counter electrode in the transport direction is Δ,
  0 <Δ <Dpp · Np / 2
  (Dpp is the pitch between the transport electrodes and the counter electrode in the transport direction, Np is the number of phases in the multiphase alternating voltage applied to the transport electrode and the counter electrode)
  The developer supply device, wherein the transport electrode substrate and the counter electrode substrate are configured and arranged so as to satisfy the above. In the developer supply apparatus configured to supply the charged powdery developer to the supply target while being transported along a predetermined developer transport path by an electric field.
A thin plate having a plurality of transport electrodes arranged to face the supply target and arranged along the developer transport path including a supply position for supplying the developer to the supply target A transfer electrode substrate,
A plurality of counter electrodes arranged along the developer transport path are arranged on the supply target side of the transport electrode substrate so as to face the transport electrode substrate across the developer transport path. A thin plate-like counter electrode substrate;
With
The transport electrode and the counter electrode are formed at the same pitch in the transport direction, the transport electrode substrate and the counter electrode substrate are bent in a concentric arc shape in a side sectional view, and the counter electrode substrate is the transport electrode When placed outside the board,
The portion of the developer transport path adjacent to the supply position on the near side in the transport direction from the supply position is
(K−1 / 2) α <θ <kα
(Θ is the central angle of the concentric arc from the position toward the transport direction with respect to the position where the transport electrode and the counter electrode having the same potential coincide with each other in the radial direction of the concentric arc as a reference [0 degrees], α is The central angle of the concentric arc at a position where the transport electrode and the counter electrode having the same potential coincide with θ = 0 next in the radial direction of the concentric arc, k is an integer of 1 or more)
The developer supply apparatus , wherein the transport electrode substrate and the counter electrode substrate are configured and arranged so as to be within a range of θ indicated by . A developer supply device according to any one of claims 1 to 4 ,
A developer supply apparatus configured to supply the developer to the supply target at the supply position along a direction orthogonal to the transport direction at the supply position.