JP4798402B2 - Developer supply device - Google Patents

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, an apparatus disclosed in JP 2008-70803 A is 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 a 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 conveying means forms an upstream conveying electric field (an electric field for moving the developer on the upstream conveying surface from the upstream side to the downstream side in the moving direction of the developer carrying surface). Is configured to do.

  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 conveying means forms a downstream conveying electric field (an electric field for moving the developer on the downstream conveying surface from the upstream side to the downstream side in the moving direction of the developer carrying surface). Is configured to do.

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

  Here, the developer travels from the upstream conveying surface toward the developer carrying surface (the peripheral surface of the developing roller). Thereby, the developer adheres to the developer carrying surface. That is, the developer is carried on the developer carrying surface. When a part of the developer carried on the developer carrying surface reaches the development area, a position corresponding to the electrostatic latent image on the latent image forming surface which is a peripheral surface of the latent image carrying body. Adhere to.

  Of the developer carried on the developer carrying surface, the developer that has not adhered to the latent image forming surface reaches the downstream carrying surface, and the developer is moved on the downstream carrying surface. It is conveyed from the upstream side to the downstream side in the moving direction of the carrying surface (rotating direction of the developing roller). As a result, surplus developer is recovered.

  In this type of apparatus, if the developer is not carried smoothly on the developer carrying surface and is not smoothly collected from the developer carrying surface, problems such as disturbance of the formed image occur.

  The present invention has been made to cope with such a problem. That is, an object of the present invention is to smoothly carry and collect the developer on the developer carrying surface, which is a peripheral surface of the developer carrying member.

  A developer supply apparatus that is an object of the present invention is configured to supply a charged powdery developer to a supply target. The developer supply device includes a developer carrying member, a transport substrate, and a voltage applying unit.

  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 is configured to be rotatable about an axis parallel to the main scanning direction.

  The transport substrate includes a plurality of transport electrodes arranged along a direction intersecting the main scanning direction, and is generated by an electric field generated when a traveling wave-like multiphase AC voltage is applied to the transport electrodes. The developer is transported in the developer transport direction. The transport substrate is provided such that an end portion in the developer transport direction faces the developer carrying member.

  For example, the downstream end portion of the supply transport substrate as the transport substrate in the developer transport direction is more than the developer supply position in the moving direction of the developer carrying surface due to the rotation of the developer carrying member. It can be provided at the upstream developer carrying position so as to face the developer carrying member. In this case, among the transport electrodes provided on the supply transport substrate, the most downstream one in the developer transport direction is closest to the developer carrying member, and the supply transport substrate and the A developer carrying member may be disposed.

The supply transport substrate and the developer carrying member may be arranged so that a plurality of the developer carrying positions are provided. in this case,
The length along the developer transport direction between two adjacent developer carrying positions is L,
The moving speed of the developer carrying surface due to the rotation of the developer carrying member is v,
The frequency of the traveling wave-like multiphase AC voltage applied to the transport electrode and the developer carrying member is f, the number of phases is k,
The pitch of the plurality of transport electrodes is p,
m and n are arbitrary integers,
Where L = n · k · p = [{m + (1/2)} · v] / f
The developer supply apparatus can be configured to satisfy the above.

  Further, an upstream end portion of the collection transport substrate as the transport substrate in the developer transport direction is more than the developer supply position in the moving direction of the developer carrying surface due to the rotation of the developer carrying member. It may be provided to face the developer carrying member at the developer collecting position on the downstream side. In this case, among the transport electrodes provided on the recovery transport substrate, the most upstream side in the developer transport direction is closest to the developer carrying member, and the recovery transport substrate and the A developer carrying member may be disposed.

The collection transport substrate and the developer carrying member may be arranged so that a plurality of the developer collection positions are provided. in this case,
The length along the developer transport direction between two adjacent developer recovery positions is L,
The moving speed of the developer carrying surface due to the rotation of the developer carrying member is v,
The frequency of the traveling wave-like multiphase AC voltage applied to the transport electrode and the developer carrying member is f, the number of phases is k,
The pitch of the plurality of transport electrodes is p,
m and n are arbitrary integers,
Where L = n · k · p = [{m + (1/2)} · v] / f
The developer supply apparatus can be configured to satisfy the above.

  The developer supply device is configured such that the transport speed of the developer in the developer transport direction by the transport substrate is at least twice the moving speed of the developer-carrying surface by the rotation of the developer-carrying member. Can be configured.

  A feature of the present invention resides in that the voltage application unit is configured to apply a multiphase AC voltage synchronized with the transport electrode to the developer carrying member. In this case, the developer supply device can be configured such that at least one of the plurality of transport electrodes on the transport substrate and the developer carrying member have the same potential.

  According to the developer supply apparatus of the present invention having the above-described configuration, a multiphase AC voltage synchronized with the transport electrode is applied to the developer carrying member. As a result, the developer is carried and collected on the developer carrying surface at a position facing the developer carrying member of the carrying substrate (at least the end of the carrying substrate in the developer carrying direction). Done more smoothly.

1 is a side view showing a schematic configuration of a laser printer as 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. FIG. 3 is an enlarged side cross-sectional view of the transport substrate shown in FIG. 2. It is a graph which shows an example of the output waveform of each power supply circuit shown by FIG. FIG. 3 is an enlarged side cross-sectional view of a main part of the toner supply device shown in FIG. 2. FIG. 5 is a side sectional view showing a configuration of a modification of the toner supply device shown in FIG. 2. FIG. 7 is an enlarged side cross-sectional view of a main part of the toner supply device shown in FIG. 6. FIG. 10 is a side sectional view showing a configuration of another modification of the toner supply device shown in FIG. 2. FIG. 9 is an enlarged side sectional view of a main part of the toner supply device shown in FIG. 8. FIG. 10 is a side cross-sectional view illustrating a configuration of still another modification of the toner supply device illustrated in FIG. 2.

  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. .

<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 in a direction indicated by an arrow in the drawing (counterclockwise in FIG. 1) around an axis parallel to the main scanning direction. That is, the photosensitive drum 3 is configured so that the electrostatic latent image carrying surface LS can move along the sub-scanning direction 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 that the electrostatic latent image carrying surface LS can be uniformly positively charged.

  The scanner unit 5 is configured to generate a laser beam LB modulated based on image data. That is, the scanner unit 5 is configured to generate a laser beam LB having a predetermined wavelength band in which light emission ON / OFF is controlled depending on the presence or absence of pixels.

  Further, the scanner unit 5 is configured to image (expose) the generated laser beam LB 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: counterclockwise in the drawing).

  Further, the scanner unit 5 moves (scans) the position where the laser beam LB is imaged on the electrostatic latent image carrying surface LS at a constant speed along the main scanning direction. An electrostatic latent image can be formed on the 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 be able to supply the electrostatic latent image carrying surface LS in a charged state at the developing 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 (clockwise) 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 (developer) 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. It has become.

<< 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.

  A toner box 61 that forms a casing of the toner supply device 6 is a box-shaped member that is formed in an oval shape in a side sectional view. The toner box 61 is arranged such that its longitudinal direction is parallel to the vertical direction (y-axis direction in the figure).

  The toner box 61 contains toner T as a powdery dry developer. That is, the toner T is stored in a toner storage portion 61 a 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 61 b is provided so as to open upward toward the photosensitive drum 3. In the present embodiment, the opening 61b is formed over the entire width of the space inside the toner box 61 in the depth direction (the main scanning direction and the direction perpendicular to the vertical direction: the x-axis direction in the figure). ing.

  The developing roller 62 as a developer carrying member of the present invention is a roller-like member having a toner carrying surface 62a which is a cylindrical circumferential surface parallel to the main scanning direction, and faces the photosensitive drum 3. It is provided as follows. 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. In this embodiment, the developing roller 62 has a rotation center axis parallel to the main scanning direction located inside the toner box 61 so that almost half of the toner carrying surface 62a is exposed outside the toner box 61. In the toner box 61.

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

  The bottom conveyance substrate 63a is disposed at the bottom in the space inside the toner box 61 so as to form the bottom surface of the toner storage unit 61a. The bottom transfer board 63a is a concave curved portion bent in a semi-cylindrical shape in a side sectional view at the bottom of the transfer board 63, and is smoothly connected to the lower end of the supply transfer board 63b. . The bottom conveyance substrate 63a is connected to the lower end portion so as to convey the toner T in the toner storage portion 61a toward the lower end portion of the supply conveyance substrate 63b.

  The supply transport substrate 63b is formed in a flat plate shape, and is erected so as to transport the toner T vertically upward from a lower end connected to the bottom transport substrate 63a.

  In the present embodiment, the upper end portion (the end portion on the downstream side in the toner transport direction TTD) of the supply transport substrate 63b is provided at almost the same height as the center of the developing roller 62 (slightly above the center). ing. The upper end portion is provided so as to face the cylindrical toner carrying surface 62 a of the developing roller 62.

  The upper end portion of the supply transport substrate 63b and the toner carrying surface 62a are spaced by a predetermined distance (300 μm) at the toner carrying position TCP upstream of the developing position DP in the moving direction of the toner carrying surface 62a by the rotation of the developing roller 62. Degree) is provided so as to face each other with a gap therebetween. That is, the upper end portion of the supply transport substrate 63b and the toner carrying surface 62a are provided so as to face each other while being closest to each other at the toner carrying position TCP.

  The supply transport substrate 63b is configured to transport the toner T transferred from the bottom transport substrate 63a toward the toner carrying position TCP in the toner transport direction TTD.

  The collection transport substrate 63c is formed in a flat plate shape, and is provided to face the developing roller 62 on the opposite side of the upper end portion of the supply transport substrate 63b from the development roller 62. The collection 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 (the end portion in the toner transport direction TTD) of the collection transport substrate 63c is provided at a position corresponding to the lower end of the developing roller 62.

  In the present embodiment, the upper end portion (upstream end portion in the toner transport direction TTD) of the collection transport substrate 63c is provided at almost the same height as the center of the developing roller 62 (slightly above the center). ing. The upper end portion is provided so as to face the cylindrical toner carrying surface 62 a of the developing roller 62.

  The upper end portion of the collection transport substrate 63c and the toner carrying surface 62a are separated by a predetermined distance (300 μm) at a toner collection position TRP downstream of the development position DP in the moving direction of the toner carrying surface 62a by the rotation of the developing roller 62. Degree) is provided so as to face each other with a gap therebetween. That is, the upper end portion of the collection transport substrate 63c and the toner carrying surface 62a are provided so as to face each other while being closest to each other at the toner collection position TRP.

  The collection transport substrate 63c is configured to collect the toner T that has not been consumed at the development position DP from the developing roller 62, and to transport the collected toner T toward the lower toner storage portion 61a. Yes.

  The transport substrate 63 and the developing roller 62 are electrically connected to the transport power supply circuit 64. The transport power supply circuit 64 circulates 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 supplied to the developing position DP while being temporarily carried by the developing roller 62, 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 reservoir 61a is output.

  Specifically, the carrier power supply circuit 64 is configured to output a rectangular wave AC voltage of +300 V / 0 V, 300 Hz. In this embodiment, the frequency of the output voltage from the transport power supply circuit 64 is determined by the transport speed of the toner T in the toner transport direction TTD by the transport substrate 63 (the supply transport substrate 63b and the recovery transport substrate 63c). It is set to be the same as the moving speed of the toner carrying surface 62a by the rotation of 62.

  The transport power supply circuit 64 as a voltage application unit of the present invention applies a multiphase AC voltage to a later-described transport electrode 631 provided on the transport substrate 63 and is synchronized with the transport electrode 631 with respect to the developing roller 62. The voltage (which is the same potential as a part of the large number of transport electrodes 631) is applied. Details of the electrical connection between the transport substrate 63 and the developing roller 62 and the transport power supply circuit 64 will be described later.

<<< Transport substrate >>>
FIG. 3 is an enlarged side sectional view of the transfer board 63 shown in FIG.

  Referring to FIG. 3, the transport substrate 63 is a thin plate-like member and has the same configuration as that of the flexible printed circuit board. Specifically, the 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 (that is, orthogonal to the sub-scanning direction), and is formed of a copper foil having a thickness of about several tens of μm. . 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 transport substrate 63a is hereinafter referred to as “bottom transport electrode 631a”. Similarly, the transport electrode 631 in the supply transport substrate 63b is hereinafter referred to as “supply transport electrode 631b”, and the transport electrode 631 in the recovery 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, the transport electrodes 631, the transport electrodes 631,... Connected to the power circuit VC connected to the power supply circuit VB are sequentially arranged along the toner transport path TTP (note that these are connected. The power supply circuits VA to VD are components of the carrier power supply circuit 64.)

  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 of the power supply circuits VA to VD is configured to output a drive voltage that is 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 transport substrate 63 is positively charged by applying a multi-phase AC driving voltage as described above to each transport electrode 631 and generating a traveling-wave electric field along the toner transport path TTP. 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.

  On the transport electrode coating layer 633, the transport electrode overcoating layer 634 (the transport electrode overcoating layer 634 on the bottom transport substrate 63a is the bottom overcoating layer 634a, and the transport electrode overcoating layer 634 on the supply transport substrate 63b is disposed. The vertical overcoating layer 634b and the transport electrode overcoating layer 634 on the recovery transport substrate 63c are referred to as a recovery overcoating layer 634c).

  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.

  In the present embodiment, the vertical overcoating layer 634b and the recovery overcoating layer 634c are formed of the same material (polyester). This material is a triboelectric charging material that sets the toner charge amount to an appropriate value, and the position in the triboelectric charging column is on the plus side of the material (polyimide) constituting the bottom overcoating layer 634a, that is, the toner T. Those having the same polarity as the charging polarity are used.

<<< Details of essential parts around developer carrying position and developer collecting position >>>
FIG. 5 is an enlarged side sectional view of the main part of the toner supply device 6 shown in FIG. In FIG. 5, the toner box 61 in FIG. 2 is omitted for simplification of illustration.

  Referring to FIG. 5, the supply most downstream electrode 631b1 (the most downstream electrode in the toner transport direction TTD among the plurality of supply transport electrodes 631b provided on the supply transport substrate 63b along the toner transport path TTP). However, the supply transport substrate 63b and the developing roller 62 are arranged so as to be closest to the toner carrying surface 62a. That is, the supply most downstream electrode 631b1 is provided at a position corresponding to the toner carrying position TCP where the supply transport substrate 63b and the developing roller 62 (toner carrying surface 62a) are closest to each other.

  As shown in FIG. 5, the supply transport substrate 63b is provided with supply transport electrodes 631bA, 631bB, 631bC, 631bD, 631bA,... Arranged in this order in the toner transport direction TTD. Yes. Here, the supply transport electrode 631bX refers to the supply transport electrode 631b connected to the power supply circuit VX [X is any one of A, B, C, and D] (recovery described later) The same applies to the transport electrodes 631cA, 631cB, 631cC, 631cD, 631cA.

  The supply most downstream electrode 631b1 is applied with a voltage whose phase is delayed by one phase with respect to the supply transport electrode 631b adjacent on the upstream side in the toner transport direction TTD. That is, in this embodiment, the supply transport electrode 631b (631bC) adjacent to the supply downstream electrode 631b1 on the upstream side in the toner transport direction TTD is connected to the power supply circuit VC. The supply downstream electrode 631b1 adjacent to the supply transport electrode 631bC on the downstream side in the toner transport direction TTD is connected to the power supply circuit VD.

  In the present embodiment, the developing roller 62 is applied with a voltage whose phase is delayed by one phase with respect to the most downstream electrode 631b1 for supply. That is, in the present embodiment, the developing roller 62 is connected to the power supply circuit VA.

  Furthermore, in the present embodiment, the most upstream collecting electrode 631c1 (the most upstream side electrode in the toner carrying direction TTD among the plurality of collecting carrying electrodes 631c provided on the collecting carrying substrate 63c along the toner carrying path TTP). In this case, a voltage whose phase is delayed by one phase relative to the developing roller 62 is applied. That is, in the present embodiment, the recovery most upstream electrode 631c1 is connected to the power supply circuit VB.

  The most upstream collecting electrode 631c1 is provided at a position corresponding to the toner collecting position TRP where the collecting transport substrate 63c and the developing roller 62 (toner carrying surface 62a) are closest to each other. The collection transport electrodes 631cC, 631cD, 631cA,... Are arranged in this order in the toner transport direction TTD on the downstream side in the toner transport direction TTD of the most upstream collection electrode 631c1 (collection transport electrode 631cB). Is provided.

<Description of laser printer operation>
Next, an outline of the operation of the laser printer 1 configured as described above will be described together with the operations and effects of the configuration of the embodiment 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 latent image forming 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 faces (oppositely faces) the scanner unit 5 due to the rotation of the photosensitive drum 3 in the direction indicated by the arrow (counterclockwise) in the drawing. Is moved along the sub-scanning direction to the scan position SP.

  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 is developed at a developing position DP that faces the toner supply device 6 by the rotation of the photosensitive drum 3 in the direction indicated by the arrow (counterclockwise) in the drawing. Move towards.

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

  Here, in the present embodiment, the downstream end of the bottom conveyance substrate 63a in the toner conveyance direction TTD, that is, the connection portion with the supply conveyance substrate 63b is formed in a curved shape. Accordingly, the transfer of the toner T from the bottom conveyance substrate 63a at the lower end portion of the supply conveyance substrate 63b can be performed smoothly.

  The supply transport substrate 63b transports the toner T transferred from the bottom transport substrate 63a at the lower end thereof vertically upward. At this time, the vertical overcoating layer 634b in the supply transport substrate 63b is different from the bottom overcoating layer 634a in the bottom transport substrate 63a in that the function of further positively charging the positively charged toner T being transported is low. Therefore, a change in the charged state of the developer during conveyance on the vertical conveyance substrate can be suppressed as much as possible.

  Here, the toner T delivered from the bottom conveyance substrate 63a is mixed with a toner having a poor charged state (reverse polarity, that is, negatively charged, low-charged or non-charged, etc.). Yes.

  However, in the configuration of the present embodiment, the electric field formed between the supply conveyance substrate 63b and the developing roller 62 when being conveyed vertically upward toward the toner carrying position TCP by the supply conveyance substrate 63b. When the positively charged toner T is carried on the developing roller 62 at the toner carrying position TCP, the toner T having a poor charged state deviates from the toner transport path TTP due to the action of gravity or the electric field described above, and is supplied. Drops downward from the transfer substrate 63b.

  Thereby, only the toner T having a good charged state is selectively conveyed to the toner carrying position TCP. That is, in the supply transport substrate 63b, the toner T having a good charge state and a poor charge state is well selected. The toner T that deviates from the toner transport path TTP and falls downward from the supply transport substrate 63b returns to the toner reservoir 61a. The toner T is again transported upward by the supply transport substrate 63b toward the toner carrying position TCP.

  As described above, the positively charged toner T is transported to the toner carrying position TCP by the supply transport substrate 63b. 4 and 5, the developing roller 62 is applied with a multiphase AC voltage synchronized with the supply transport electrode 631b. Specifically, a voltage whose phase is delayed by one phase is applied to the developing roller 62 connected to the power supply circuit VA from the supply most downstream electrode 631b1 connected to the power supply circuit VD.

  Then, an electric field similar to a traveling wave electric field that conveys the toner T in the toner conveyance path TTP on the supply conveyance substrate 63b in the toner conveyance direction TTD is generated at the toner carrying position TCP and the most downstream electrode 631b1 for supply and the developing roller 62. (Toner carrying surface 62a).

  Here, the voltage applied to the toner carrying position TCP does not include a large DC bias voltage for shifting the positively charged toner T to the developing roller 62 side. For this reason, the toner T smoothly moves to the developing roller 62 side by the traveling-wave electric field generated by the multiphase AC voltage output from the conveyance power supply circuit 64, which is formed at the toner carrying position TCP, and the toner carrying surface 62a. Good support on top.

  The toner T carried on the toner carrying surface 62a is moved to the developing position DP by the rotation driving of the developing roller 62, whereby the toner T is supplied to the developing position DP. The electrostatic latent image formed on the electrostatic latent image carrying surface LS is developed with the toner T in the vicinity of 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 the toner collection position TRP by the rotation of the development roller 62. Here, referring to FIGS. 4 and 5, the developing roller 62 is applied with a multiphase AC voltage synchronized with the recovery transport electrode 631c. Specifically, a voltage whose phase is advanced by one phase is applied to the developing roller 62 connected to the power supply circuit VA than the most upstream electrode 631c1 for recovery connected to the power supply circuit VB.

  Then, an electric field similar to a traveling wave electric field for transporting the toner T in the toner transport path TTP on the recovery transport substrate 63c in the toner transport direction TTD is generated at the toner recovery position TRP and the recovery most upstream electrode 631c1 and the developing roller 62. (Toner carrying surface 62a).

  Here, the voltage applied to the toner recovery position TRP is the positively charged toner T firmly attached on the toner carrying surface 62a by the mirror image force or van der Waals force from the developing roller 62 to the recovery conveyance substrate 63c side. It does not include a large DC bias voltage for shifting to.

  For this reason, the toner T smoothly moves from the developing roller 62 to the collection conveyance substrate 63c side by the traveling wave electric field formed by the multiphase AC voltage output from the conveyance power supply circuit 64, which is formed at the toner collection position TRP. To do. That is, at the toner collection position TRP, the toner T is collected from the toner carrying surface 62a by the collection transport substrate 63c. The collected toner T is favorably transported in the toner transport direction TTD without being pressed onto the recovery transport substrate 63c by the large DC bias as described above.

  Further, the voltage applied to the developing roller 62 acts as a developing bias for so-called jumping development at the developing position DP. Therefore, the developing bias can be applied satisfactorily with a simple apparatus configuration.

  The toner T is transported vertically downward at the lower end of the collection transport substrate 63c. 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 collection 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 transport substrate 63c is not provided until it reaches the toner reservoir 61a, the toner T is favorably returned to the toner reservoir 61a.

<< Transfer of toner image from latent image forming 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. By being rotated (counterclockwise), it 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.

<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.

  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 photosensitive drum 3 and the developing roller 62 may be in contact with each other.

  (3) The configuration of the transport substrate 63 is not limited to that of the above-described embodiment.

  For example, the transport electrode overcoating layer 634 can be omitted (in this case, the material selection of the transport electrode coating layer 633 is performed similarly to the material selection of the transport electrode overcoating layer 634 in the above-described embodiment). 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 supply transfer substrate 63b may be substantially erected along the vertical direction, and may be slightly inclined. Similarly, the collection transport substrate 63c may be slightly inclined.

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

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

  The bottom transfer substrate 63a, the supply transfer substrate 63b, and the recovery transfer substrate 63c may be integrated with the toner box 61. That is, for example, the transfer substrate 63 formed by integrating the bottom transfer substrate 63a, the supply transfer substrate 63b, and the recovery transfer substrate 63c is configured by a solid substrate bent in a substantially U shape in a side sectional view. May be.

  FIG. 6 is a side sectional view showing a configuration of a modified example of the toner supply device 6 shown in FIG. FIG. 7 is an enlarged side sectional view of the main part of the toner supply device 6 shown in FIG. As shown in FIGS. 6 and 7, even if a bent portion having a shape following the cylindrical shape of the developing roller 62 is formed at the uppermost end portion of the supply transfer substrate 63b or the recovery transfer substrate 63c. Good.

  In the present modification, the uppermost end portion of the supply transport substrate 63b is provided above the center of the developing roller 62, specifically, to a position reaching the opening 61b. The uppermost end is bent into a concave curved surface so as to face the cylindrical toner carrying surface 62a of the developing roller 62 with a gap of a predetermined interval (about 300 μm).

  In the present modification, the upper portion of the collection transport substrate 63c is spaced from the developing roller 62 by a fixed distance (spacing narrower than the gap between the photosensitive drum 3 and the developing roller 62 at the developing position DP: about 300 μm). It is bent into a concave curved surface so as to face each other with a gap. The lower portion of the collection transport substrate 63c is provided so as to transport the toner T vertically downward.

  That is, as shown in FIG. 7, in this modification, unlike the above-described embodiment (only the most downstream electrode for supply 631b1 is closest to the toner carrying surface 62a), the supply substrate for supply is provided. A plurality of supply transport electrodes 631b including a supply most downstream electrode 631b1 are provided in the toner carrying region TCA where the uppermost end of 63b and the toner carrying surface 62a face each other.

  Similarly, in the present modified example, unlike the above-described embodiment (only the collecting most upstream electrode 631c1 is closest to the toner carrying surface 62a), the uppermost end portion of the collecting transport substrate 63c and the toner carrying surface are used. A plurality of recovery transport electrodes 631c including a recovery most upstream electrode 631c1 are provided in the toner recovery area TRA that faces 62a.

  In this modification, the frequency of the output voltage from the transport power supply circuit 64 is determined by the transport speed of the toner T in the toner transport direction TTD by the transport substrate 63 (the supply transport substrate 63b and the recovery transport substrate 63c). It is set to be at least twice the moving speed of the toner carrying surface 62a by the rotation of 62. Thus, the toner T can be carried on the toner carrying surface 62a and the toner T can be recovered from the toner carrying surface 62a.

  FIG. 8 is a side sectional view showing a configuration of another modified example of the toner supply device 6 shown in FIG. FIG. 9 is an enlarged side sectional view of the main part of the toner supply device 6 shown in FIG. As shown in FIGS. 8 and 9, this modification is a further modification of the previous modification shown in FIGS. 6 and 7.

  That is, in the present modification, as in the above-described embodiment (see FIG. 5), only the most downstream supply electrode 631b1 among the plurality of supply transport electrodes 631b is closest to the toner carrying surface 62a. ing. Further, in the present modification, only the recovery most upstream electrode 631c1 among the plurality of recovery transport electrodes 631c is closest to the toner carrying surface 62a.

  Even with this configuration, it is possible to satisfactorily carry the toner T on the toner carrying surface 62a and collect the toner T from the toner carrying surface 62a.

  In particular, as shown in FIG. 9, in this modification, the portion of the toner carrying surface 62a that receives the supply of toner T from the supply downstream electrode 631b1 is the supply downstream electrode 631b1 in the toner transport path TTP. Is formed along the toner transport direction TTD at the position corresponding to (the tangential direction of the toner transport path TTP at the position). As a result, the toner T smoothly moves from the supply transport substrate 63b to the developing roller 62 side, and is favorably carried on the toner carrying surface 62a.

  As shown in FIG. 9, in this modification, the portion of the toner carrying surface 62a that receives the recovery operation of the toner T by the recovery most upstream electrode 631c1 is the recovery most upstream electrode in the toner transport path TTP. It is formed along the toner transport direction TTD at the position corresponding to 631c1 (the tangential direction of the toner transport path TTP at the position). As a result, the toner T smoothly moves from the developing roller 62 to the collection transport substrate 63c. Therefore, the collection of the toner T from the toner carrying surface 62a and the conveyance in the toner conveyance direction TTD by the collection conveyance substrate 63c are favorably performed.

  FIG. 10 is a side sectional view showing a configuration of still another modified example of the toner supply device 6 shown in FIG. As shown in FIG. 10, the toner supply device 6 is configured such that the toner carrying surface 62a and the transport substrate 63 are (closest) close to each other (two in the example of FIG. 10). obtain.

  That is, the supply transport substrate 63b and the developing roller 62 can be arranged so that a plurality of toner carrying positions TCP are provided. According to this configuration, the toner T can be more favorably carried on the toner carrying surface 62a. Here, in the drawing, the toner transport direction TTDc indicates the toner transport direction when the transport substrate 63 is the supply transport substrate 63b.

In this case, the following formula (1)
L = n · k · p = [{m + (1/2)} · v] / f (1)
The toner supply device 6 can be configured to satisfy the above.

Here, in the above formula (1),
L is the length along the toner transport direction TTDc between two adjacent toner carrying positions TCP (between the first opposing position CP1 and the second opposing position CP2),
v is the moving speed of the toner carrying surface 62a due to the rotation of the developing roller 62;
f is the frequency of the traveling wave-like multiphase AC voltage applied to the supply electrode 631b (see FIG. 3) and the developing roller 62,
k is the number of phases of the traveling-wave multiphase AC voltage applied to the supply electrode 631b (see FIG. 3) and the developing roller 62,
p is the pitch of the plurality of supply electrodes 631b for supply (see FIG. 3),
m and n are arbitrary integers.

  Specifically, when the multiphase AC voltage is four phases and the moving speed v of the toner carrying surface 62a is equal to the toner transport speed in the toner transport direction TTDc by the supply transport substrate 63b, the second counter position CP2 A voltage whose phase is shifted by two phases with respect to the supply transport electrode 631b at the first facing position CP1 is applied to the supply transport electrode 631b.

  According to such a configuration, the toner T can be favorably supported at the first facing position CP1 with respect to the portion of the toner bearing surface 62a where the toner T is not supported at the second facing position CP2. As a result, the toner T is more uniformly carried on the toner carrying surface 62a.

  Alternatively, the collection transport substrate 63c and the developing roller 62 may be arranged so that a plurality of toner collection positions TRP are provided. According to such a configuration, the recovery of the toner T from the toner carrying surface 62a can be performed more reliably. Here, in the drawing, the toner transport direction TTDr indicates the toner transport direction when the transport substrate 63 is the recovery transport substrate 63c.

In this case, the following formula (2)
L = n · k · p = [{m + (1/2)} · v] / f (2)
The toner supply device 6 can be configured to satisfy the above.

Here, in the above formula (2),
L is the length along the toner transport direction TTDr between two adjacent toner collection positions TRP (between the first opposing position CP1 and the second opposing position CP2).
v is the moving speed of the toner carrying surface 62a due to the rotation of the developing roller 62;
f is the frequency of the traveling wave-like multiphase AC voltage applied to the recovery transport electrode 631c (see FIG. 3) and the developing roller 62;
k is the number of phases of the traveling wave-like multiphase AC voltage applied to the recovery transport electrode 631c (see FIG. 3) and the developing roller 62;
p is the pitch of the plurality of recovery transport electrodes 631c (see FIG. 3),
m and n are arbitrary integers.

  Specifically, when the multiphase AC voltage is four phases and the moving speed v of the toner carrying surface 62a and the toner transport speed in the toner transport direction TTDc by the recovery transport substrate 63c are equal, the second counter position CP2 A voltage whose phase is shifted by two phases from the recovery transport electrode 631c at the first facing position CP1 is applied to the recovery transport electrode 631c.

  According to such a configuration, the toner T remaining on the toner carrying surface 62a without being collected at the first facing position CP1 can be favorably collected at the second facing position CP2. Thereby, the residual toner on the toner carrying surface 62a can be collected more favorably, and the occurrence of ghost in the formed image can be suppressed satisfactorily.

  (4) Referring to FIG. 4, the waveform of the voltage 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 other than 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 °.

  (7) 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 drawings) of each publication cited in the present specification may be incorporated as part of the specification.

DESCRIPTION OF SYMBOLS 1 ... Laser printer 2 ... Paper conveyance mechanism 21 ... Registration roller 22 ... Transfer roller 3 ... Photosensitive drum (supply object)
4 ... Charger 5 ... Scanner unit 6 ... Toner supply device (developer supply device)
61 ... Toner box (casing)
61a ... Toner reservoir (developer reservoir)
61b ... Opening 62 ... Developing roller (developer carrying member)
62a ... toner carrying surface (developer carrying surface)
63 ... Transport substrate 63a ... Bottom transport substrate 63b ... Supply transport substrate 63c ... Recovery transport substrate 631 ... Transport electrode 631a ... Bottom transport electrode 631b ... Supply transport electrode 631b1 ... Supply most downstream electrode 631c ... Recovery transport electrode 631c1 ... Recovery most upstream electrode 632 ... Conveying electrode support film 633 ... Conveying electrode coating layer 634 ... Conveying electrode overcoating layer 64 ... Conveying power supply circuit (voltage applying means)
CP1 ... first counter position CP2 ... second counter position DP ... development position (developer supply position)
LB ... Laser beam LS ... Electrostatic latent image carrying surface P ... Paper PP ... Paper transport path SP ... Scan position T ... Toner (developer)
TCA ... Toner carrying area (developer carrying position)
TRA ... Toner collection area (developer collection position)
TCP ... Toner carrying position (Developer carrying position)
TRP ... Toner collection position (developer collection position)
TP ... Transfer position TTD ... Toner transport direction TTDc ... Toner transport direction TTDr ... Toner transport direction TTP ... Toner transport path

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; A developer carrying member configured to be rotatable about a parallel axis;
A plurality of supply transport electrodes arranged along a direction intersecting the main scanning direction, and the developer by an electric field generated when a traveling-wave multiphase AC voltage is applied to the supply transport electrodes. In the developer transport direction, and an end on the downstream side in the developer transport direction is upstream of the developer supply position in the moving direction of the developer carrying surface due to the rotation of the developer carrying member. A transport substrate for supply provided to face the developer carrying member at the developer carrying position on the side ;
The developer carrying member is synchronized with the supply carrying electrode so that at least one of the plurality of supply carrying electrodes on the supply carrying substrate and the developer carrying member have the same potential. Voltage applying means for applying the multiphase AC voltage,
Equipped with a,
Of the supply transport electrodes provided on the supply transport substrate, the most downstream electrode for supply in the developer transport direction, so that the most downstream electrode for supply is closest to the developer carrying member, The supply transport substrate and the developer carrying member are arranged,
The developer supply apparatus, wherein the voltage application unit applies a voltage whose phase is delayed by one phase relative to the supply downstream electrode to the developer carrying member . The developer supply device according to claim 1 ,
The conveyance speed of the developer in the developer conveyance direction by the supply conveyance substrate is configured to be twice or more the movement speed of the developer carrying surface by the rotation of the developer carrying member. A developer supply device.   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; A developer carrying member configured to be rotatable about a parallel axis;
  A plurality of recovery transport electrodes arranged in a direction intersecting with the main scanning direction, and the developer by an electric field generated when a traveling wave-like multiphase AC voltage is applied to the recovery transport electrodes. In the developer transport direction, and an upstream end in the developer transport direction is downstream of the developer supply position in the moving direction of the developer carrying surface due to the rotation of the developer carrying member. A collecting transport substrate provided to face the developer carrying member at the developer collecting position on the side;
  The developer carrying member is synchronized with the collection carrying electrode so that at least one of the plurality of collecting carrying electrodes on the collecting carrying substrate and the developer carrying member have the same potential. Voltage applying means for applying the multiphase AC voltage,
  With
  Among the collection transport electrodes provided on the collection transport substrate, the most upstream collection electrode in the developer transport direction is closest to the developer carrying member. The collection transport substrate and the developer carrying member are arranged,
  The developer supply apparatus, wherein the voltage applying unit applies a voltage whose phase is advanced by one phase relative to the recovery downstream electrode to the developer carrying member.   The developer supply device according to claim 3,
  A transport speed of the developer in the developer transport direction by the recovery transport substrate is configured to be twice or more a moving speed of the developer-carrying surface by rotation of the developer-carrying member. A developer supply device.

Images