JP4911188B2 - 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 while being conveyed along a developer conveyance path by an electric field.

  As this type of apparatus, those disclosed in Japanese Patent Laid-Open Nos. 60-115962, 11-84862, 2001-209246, 2002-287495, etc. are known. Yes. Such an apparatus includes a plurality of transport electrodes arranged along the developer transport direction, and is configured to transport the developer by an electric field generated by application of a drive voltage to the plurality of transport electrodes. .

  In this type of apparatus, when the supply state of the developer becomes defective, problems such as disturbance of the formed image occur. Therefore, by appropriately supplying the developer in this type of apparatus, good image formation can be performed. The present invention has been made to cope with such a problem.

<Configuration>
The developer supply device that is the subject of the present invention is to transport a charged powdery developer along the developer transport path by an electric field (a traveling wave-shaped electric field that travels in a predetermined direction over time) It is comprised so that it may supply with respect to a supply object. The developer supply device includes a casing, a developer carrying member, and a transport substrate.

  The casing is a box-like member, has an opening that opens upward toward the supply target, and is configured to store the developer in a developer storage section at the bottom.

  The developer carrying member is a roller-like member having a cylindrical circumferential surface, and is provided to face the supply target while being accommodated inside the casing so as to face the opening. ing.

  The transport substrate is supported on the inner wall surface of the casing. The transport substrate includes a plurality of transport electrodes arranged along the developer transport path, and the developer transport path along the developer transport path is caused by an electric field generated when a voltage is applied to the transport electrodes. The developer is conveyed. In addition, the said conveyance board | substrate can have an insulating layer on the surface.

  The transport substrate may comprise an upper transport substrate. The upper transport substrate is provided so as to transport the developer upward (for example, vertically upward) toward the developer carrying member. In addition, this upper conveyance board | substrate may be comprised by flat form.

  The transfer substrate may further include a collection substrate. The recovery substrate is provided to face the upper end portion of the upper transport substrate with the developer carrying member interposed therebetween so that the developer is transported downward in order to return the developer to the developer reservoir. .

  A feature of the present invention resides in that the developer supply device further includes an interval adjusting means for adjusting an interval between the developer carrying member and the transport substrate. Specifically, for example, the interval adjusting unit may be configured to adjust an interval between the upper end portion of the upper transport substrate facing the developer carrying member and the developer carrying member. Alternatively, the interval adjusting means may be configured to adjust the interval between the recovery substrate and the developer carrying member.

<Action and effect>
In such a configuration, the developer is transported along the developer transport path by a (traveling wave-like) electric field generated in response to voltage application to the plurality of transport electrodes.

  Specifically, the developer is transported upward by the upper transport substrate from the developer reservoir to a position where the upper end portion of the upper transport substrate and the developer carrying member face each other. At this position, the developer transported by the upper transport substrate can be carried on the peripheral surface of the developer carrying member.

  When the developer is transported upward and the developer carrying member is carried on the peripheral surface, the developer having a poor charged state deviates from the position or the developer transport path and falls downward. To do. As a result, the developer having a good charge state and a poor charge state in the developer is well selected on the upper transport substrate.

  On the other hand, the developer carried on the peripheral surface is collected by the collection substrate at a position where the developer carrying member and the collection substrate face each other. The developer collected in this manner is returned to the developer storage section below by the electric field transport action of the collection substrate.

  Here, in the configuration of the present invention, the interval between the developer carrying member and the transport substrate (the upper transport substrate and / or the recovery substrate) is appropriately adjusted by the distance adjusting unit. Specifically, for example, the interval can be adjusted according to the charge amount of the developer. Or the said space | interval may be adjusted according to humidity. Alternatively, the interval may be adjusted according to the newness of the developer. Alternatively, the interval can be made as narrow as possible when the developer transport operation is not performed.

  That is, by adjusting the distance between the upper transport substrate and the developer carrying member according to operating conditions, the developer supply characteristics from the upper transport substrate to the developer carrying member (in other words, the The developer carrying characteristics on the peripheral surface of the developer carrying member can be adjusted. On the other hand, by adjusting the interval between the recovery substrate and the developer carrying member according to the operating state, the recovery characteristics of the developer by the recovery substrate can be adjusted. Furthermore, when the developer transport operation is not performed, the interval is made as narrow as possible, so that inadvertent leakage of the developer from the developer supply device can be satisfactorily suppressed.

  As described above, according to the developer supply device of the present invention, the developer can be more appropriately supplied to the supply target, and thus the image forming apparatus including the developer supply device. Good image formation is performed at.

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 a side cross-sectional view illustrating an operation state of the toner supply device illustrated in FIG. 2. FIG. 3 is a side cross-sectional view illustrating an operation state of the toner supply device illustrated in FIG. 2. FIG. 4 is a side sectional view showing a schematic configuration of a modified example of the toner supply device shown in FIG. 2. FIG. 10 is a side sectional view showing a schematic configuration of another modification of the toner supply device shown 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 (clockwise in FIG. 1) around a central axis C 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: clockwise 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 (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 (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.

  The toner box 61 forming the casing of the toner supply device 6 is a box-like member formed in an oval shape in a side sectional view, and its longitudinal direction is parallel to the vertical direction (y-axis direction in the figure). Is arranged. The toner box 61 contains toner T as a powdery dry developer. In this embodiment, the toner T is a positively chargeable, non-magnetic single component black toner.

  The toner box 61 includes a transport side panel 61a, a collection side panel 61b, a semi-cylindrical portion 61c, and a pair of side walls 61d. The toner box 61 is integrally formed of synthetic resin.

  The conveyance side panel 61a is a flat plate-like member parallel to the main scanning direction and the height direction, and is erected so as to be orthogonal to the horizontal plane. The collection side panel 61b is a flat plate-like member parallel to the transport side panel 61a, and is erected so as to be orthogonal to the horizontal plane. The transport side panel 61a and the collection side panel 61b are provided so as to face each other such that their upper end edges are parallel to the main scanning direction and have the same height. The recovery side panel 61b is formed such that the upper part has the same thickness as the transport side panel 61a and the lower part is thicker than the transport side panel 61a.

  The semi-cylindrical portion 61c is a thin-walled semi-cylindrical member having a central axis parallel to the main scanning direction, and is connected to the lower end edges of the transport side panel 61a and the collection side panel 61b. The semi-cylindrical portion 61c is formed with the same thickness as the transport side panel 61a. That is, a substantially U-shaped synthetic resin frame is formed in a side sectional view by the transport side panel 61a, the collection side panel 61b, and the semi-cylindrical portion 61c. The pair of side walls 61d are flat plate members parallel to each other, and are provided so as to close the sides of the substantially U-shaped synthetic resin frame.

  With the above-described structure, the toner storage portion 61e is formed in a substantially semi-cylindrical portion at the bottom of the space inside the toner box 61. Further, an opening 61 f is formed at the top of the toner box 61 and at a position facing the photosensitive drum 3. That is, the opening 61 f is provided so as to open upward toward the photosensitive drum 3. The opening 61f is formed over the entire width of the space inside the toner box 61 in the depth direction (the direction perpendicular to the main scanning direction and the vertical direction: the x-axis direction in the figure).

  A slide hole 61g, which is a through hole, is provided in each of the side walls 61d of the pair of toner boxes 61 facing in the main scanning direction. The slide hole 61g is disposed near the upper end of the side wall 61d, that is, in the vicinity of the opening 61f and in the center in the depth direction. The slide hole 61g is formed in an oval shape having a longitudinal direction along the depth direction.

  An operation hole 61h is provided in the thin portion at the top of the collection side panel 61b. The operation hole 61h is a substantially rectangular through hole, and is provided at the center of the recovery side panel 61b in the main scanning direction.

  The developing roller 62 as the developer carrying member of the present invention is a roller-like member having a toner carrying surface 62 a that is a cylindrical circumferential surface, and is provided so as to face the photosensitive drum 3. That is, the developing roller 62 is disposed so that the toner carrying surface 62a is opposed to the electrostatic latent image carrying surface LS on the photosensitive drum 3 at a development position DP with a gap of a predetermined interval (about 500 μm). ing. Further, the developing roller 62 is provided so that the rotation center axis parallel to the main scanning direction is located inside the toner box 61 so that almost half of the toner carrying surface 62 a is exposed to the outside of the toner box 61.

  In the present embodiment, the developing roller 62 is accommodated in the toner box 61 so as to move in the depth direction within the toner box 61. Specifically, the developing roller shaft 62b constituting the rotation center axis of the developing roller 62 is supported by the slide hole 61g so as to be rotatable and slidable in the depth direction.

  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. That is, the transport substrate 63 is supported by the inner wall surface of the toner box 61. In the present embodiment, the transport substrate 63 includes a bottom transport substrate 63a, a vertical transport substrate 63b, and a recovery substrate 63c. The details of the internal configuration of the transfer substrate 63 (the bottom transfer substrate 63a, the vertical transfer substrate 63b, and the recovery 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 constitute the bottom surface of the toner storage unit 61e. The bottom conveyance substrate 63a is a concave curved portion bent in a semi-cylindrical shape in a side sectional view of the bottom of the conveyance substrate 63, and is supported by the inner wall surface of the semi-cylindrical portion 61c in the toner box 61. Yes.

  The downstream end of the bottom transport substrate 63a in the toner transport direction TTD is smoothly connected to the lower end of the vertical transport substrate 63b. That is, the bottom conveyance substrate 63a smoothly conveys the toner T in the toner storage portion 61e toward the lower end portion of the vertical conveyance substrate 63b.

  The vertical conveyance substrate 63b is formed in a flat plate shape, and is erected so as to convey the toner T vertically upward from the lower end connected to the bottom conveyance substrate 63a. Specifically, the vertical conveyance substrate 63 b is supported by the inner wall surface of the conveyance side panel 61 a in the toner box 61. The vertical transport substrate 63b is configured to transport the toner T transferred from the bottom transport substrate 63a toward the developing roller 62 and the development position DP in the toner transport direction TTD.

  In the present embodiment, the upper end portion 63 b 1 of the vertical transport substrate 63 b is provided at substantially the same height as the center of the developing roller 62. The upper end 63b1 is provided 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).

  The collection substrate 63c is provided to face the developing roller 62 on the opposite side across the developing roller 62 from the upper end portion 63b1 of the vertical transport substrate 63b. That is, the collection substrate 63c is disposed downstream of the opening 61f of the toner box 61 in the toner transport direction TTD. In the present embodiment, the end portion of the collection substrate 63c in the toner transport direction TTD is provided at a position corresponding to the lower end of the developing roller 62.

  The collection 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 convey the collected toner T toward the lower toner storage portion 61e. Specifically, in the present embodiment, the collection substrate 63c is formed in a flat plate shape. The recovery substrate 63c is opposed to the developing roller 62 with a gap of a predetermined interval (interval narrower than the gap between the photosensitive drum 3 and the developing roller 62 at the developing position DP: about 300 μm), while the toner T Is provided so as to be conveyed vertically downward.

  In the present embodiment, the collection substrate 63c is disposed at a position corresponding to the thin portion at the top of the collection side panel 61b. Further, the collection substrate 63c is provided so as to be separated from the thin portion. That is, the lower end and the side end (end edge in the main scanning direction) of the recovery substrate 63c are supported by the recovery side panel 61b via the diaphragm 63d made of thin rubber.

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

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

  Specifically, the carrier power supply circuit 64 outputs a rectangular wave AC voltage of 400 V to 1000 V (amplitude 600 V, DC offset 700 V) and 300 Hz. Further, the recovery power supply circuit 65 outputs a rectangular waveform AC voltage of −300 V to +300 V (amplitude 600 V, DC offset 0 V) and 300 Hz. Further, the development bias power supply circuit 66 outputs a rectangular wave AC voltage of −600 V to 1400 V (amplitude 2000 V, DC offset 400 V) and 1200 Hz.

  That is, the development bias power supply circuit 66 applies an output voltage (collection bias) with a larger amplitude than the recovery power supply circuit 65 and a frequency that is an integral multiple of the frequency of the output voltage of the recovery power supply circuit 65 to the developing roller 62. It has become. Further, the recovery power supply circuit 65 applies an output voltage to the recovery substrate 63c that has an average potential (0V) lower than the potential (240V) of the exposure portion to which the toner T on the electrostatic latent image carrying surface LS is to be supplied. It is supposed to be. The outputs of the recovery power supply circuit 65 and the development bias power supply circuit 66 are set so that the electric field between the development roller 62 and the recovery substrate 63c is stronger than the electric field between the development roller 62 and the photosensitive drum 3. The voltage is set.

  In the space inside the toner box 61, a shielding plate 67 is disposed at a position below the developing roller 62 and close to the vertical conveyance substrate 63b. The shielding plate 67 prevents the toner T from adhering to the developing roller 62 when the toner T soars in the space inside the toner box 61 due to the operation of the transport substrate 63 (that is, from the soaring toner T to the developing roller). 62).

<<< Interval adjustment means >>>
The toner supply device 6 includes an interval adjusting unit 68. The interval adjusting means 68 includes an engaging portion 68a, actuators 68b and 68c, and a control circuit 68d.

  The engaging portion 68a is formed to engage with the outer peripheral surface of the developing roller shaft 62b. The actuator 68b is configured to be able to move the developing roller 62 in the depth direction by sliding the engaging portion 68a along the slide hole 61g. The actuator 68c is configured to be able to slide the collection substrate 63c in the depth direction by operating the portion exposed by the operation hole 61h in the collection substrate 63c. The control circuit 68d controls the operation of the actuators 68b and 68c.

  That is, the interval adjusting unit 68 controls the operation of the actuators 68b and 68c in accordance with the operating conditions (for example, environmental conditions) of the laser printer 1 (see FIG. 1), so that the vertical transfer substrate 63b (upper end portion 63b1). And the developing roller 62 (toner carrying surface 62a) and the developing roller 62 (toner carrying surface 62a) and the collection substrate 63c can be individually adjusted.

<<< 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 (the transport electrode 631 in the bottom transport substrate 63a is referred to as the bottom transport electrode 631a, the transport electrode 631 in the vertical transport substrate 63b is referred to as the vertical transport electrode 631b, and the transport electrode 631 in the recovery substrate 63c is referred to as the recovery electrode 631c). 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 the toner transport path TTP and are arranged in parallel to each other.

  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 transport power supply circuit 64 and the recovery power supply circuit 65 in FIG.

  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.

  In this way, the transport substrate 63 applies the drive voltage as described above to each transport electrode 631 and generates a traveling-wave electric field along the toner transport path TTP. The toner is 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 vertical transport substrate 63b is vertical. The overcoating layer 634b and the transport electrode overcoating layer 634 on the collection substrate 63c are referred to as a collection 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 makes the charge amount of the toner an appropriate value, and the position in the triboelectric charge train is on the plus side, that is, the toner T with respect to the material (polyimide) constituting the bottom overcoating layer 634a. The one having the same polarity as the charging polarity is used.

<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 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.

  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 moved to the developing position DP facing the toner supply device 6 by the rotation of the photosensitive drum 3 in the direction indicated by the arrow (clockwise) 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 transferred to the vertical transport substrate 63b. Delivered.

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

  The vertical transport substrate 63b transports the toner T delivered from the bottom transport substrate 63a at the lower end thereof vertically upward. At this time, unlike the bottom overcoating layer 634a in the bottom transport substrate 63a, the vertical overcoating layer 634b in the vertical transport substrate 63b has a low function of further positively charging the positively charged toner T being transported. 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 toner having a poor charged state (reverse polarity, that is, negatively charged or non-charged).

  However, in the configuration of the present embodiment, the positively charged toner T is transferred to the developing roller by the electric field formed between the vertical conveying substrate 63b and the developing roller 62 when being conveyed vertically upward by the vertical conveying substrate 63b. When the toner T is carried by the toner 62, the toner T in a poorly charged state is separated from the toner transport path TTP due to gravity, the action of the electric field described above, or the collision with the shielding plate 67, and falls downward from the vertical transport substrate 63b. To do.

  Thereby, only the toner T having a good charged state is selectively conveyed toward the developing roller 62 and the developing position DP. That is, on the vertical conveyance substrate 63b, the toner T having a good charge state and a poor one are well selected.

  The toner T dropped downward from the vertical transport substrate 63b reaches the downstream end of the bottom transport substrate 63a in the toner transport direction TTD. As a result, the toner T in the toner reservoir 61e, which is near the end on the downstream side in the toner transport direction TTD of the bottom transport substrate 63a, is fluidized well, and the bottom overcoating layer 634a Charges well due to friction.

  As described above, in the toner supply device 6 of the present embodiment, the toner T can be obtained without forcibly (positively) charging the toner T in the toner reservoir 61e by a mechanical action by a stirring member, a blade, or the like. Is transported well. Therefore, the deterioration of the toner T with time can be suppressed as much as possible.

  In addition, the toner T that has fallen from the vertical conveyance substrate 63b and has a poor charged state reaches the toner storage portion 61e, not the middle of the vertical conveyance substrate 63b. Accordingly, the transport of the toner T by the vertical transport substrate 63b is disturbed (for example, the toner T being transported in a well-charged state falls off from the vertical transport substrate 63b, or the vertical transport substrate of the toner T in a poorly charged state is transported. And the like are prevented as much as possible.

  As described above, the positively charged toner T is supplied to the development 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 62a that has passed through the development position DP (not consumed at the development position DP) moves to the collection substrate 63c side by the action of the collection bias described above. That is, the toner is recovered from the toner carrying surface 62a by the recovery substrate 63c.

  Here, in the present embodiment, an AC recovery bias is applied to the developing roller 62. The toner T in the vicinity of the toner carrying surface 62a of the developing roller 62 vibrates by the action of the AC component of the recovery bias. Due to this vibration, the toner T floating from the toner carrying surface 62a collides with the toner T carried (attached) on the toner carrying surface 62a. Due to such a collision, the toner T carried on the toner carrying surface 62a is likely to float from the toner carrying surface 62a.

  In the present embodiment, the average potential (0 V) of the recovery bias is set to a potential lower than the potential (240 V) of the exposed portion where the toner T is to be supplied on the electrostatic latent image carrying surface LS. Further, in the present embodiment, the electric field between the developing roller 62 and the collection substrate 63c is stronger than the electric field between the developing roller 62 and the photosensitive drum 3.

  Due to such a recovery bias, the toner T that has not been consumed from the portion of the toner carrying surface 62a that has passed through the development position DP is peeled off satisfactorily and moves toward the recovery substrate 63c. Therefore, the occurrence of ghost in the formed image is suppressed as much as possible.

  In the present embodiment, the amplitude of the recovery bias is set larger than the amplitude of the voltage applied to the recovery electrode 631c. For this reason, the recovery operation of the toner T from the toner carrying surface 62a as described above can be performed satisfactorily without increasing the voltage between the adjacent recovery electrodes 631c. Therefore, the insulation between the adjacent recovery electrodes 631c in the recovery substrate 63c can be ensured satisfactorily.

  Further, this recovery bias also serves as a bias for so-called jumping development at the development position DP. Accordingly, the recovery bias can be satisfactorily applied with a simple device configuration.

  The toner T that has moved from the toner carrying surface 62a to the collection substrate 63c is conveyed toward the lower toner reservoir 61e by an electric field generated by a voltage applied to the collection electrode 631c.

  Here, in the present embodiment, the frequency of the recovery bias is set to an integral multiple of the frequency of the voltage applied to the vertical transport electrode 631b and the recovery electrode 631c. Thereby, the recovery bias and the electric field for transporting the toner T on the recovery substrate 63c are well synchronized.

  The toner T is conveyed vertically downward at the lower end of the collection 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 substrate 63c, the toner T falls to the toner storage portion 61e by the action of gravity and inertia in the same direction as the gravity. Therefore, even if the collection substrate 63c is not provided until the toner storage portion 61e is reached, the toner T is favorably returned to the toner storage portion 61e.

<< 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 (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 Present Embodiment>
5 and 6 are side sectional views showing the operation of the toner supply device 6 shown in FIG. Hereinafter, the details of the operation of the interval adjusting means 68 will be described with reference to FIGS. 2, 5 and 6.

  During the image forming operation by the laser printer 1 (see FIG. 1) (in addition to the actual printing operation, all operations involving the transport of the toner T by the transport substrate 63 such as the standby operation and the cleaning operation of each part may be included). The operation of the actuators 68b and 68c is controlled by the control circuit 68d according to the operating conditions (cumulative number of printed sheets and the like). As a result, as shown in FIGS. 2 and 5, the positions of the developing roller 62 and the collection substrate 63c in the depth direction are adjusted.

  Specifically, for example, when the cumulative number of printed sheets is very small and it is determined that the toner T is new or similar to a new one, as shown in FIG. The interval and the interval between the developing roller 62 and the collection substrate 63c are set as wide as possible. Thereafter, as the cumulative number of printed sheets increases, as shown in FIG. 5, these intervals are gradually narrowed. Thereby, according to the characteristic (newness) of the toner T, the carrying characteristic on the toner carrying surface 62a and the collecting characteristic by the collecting substrate 63c can be appropriately set.

  Thus, in the configuration of the present embodiment, according to the operating conditions of the laser printer 1 (see FIG. 1), the distance between the vertical transport substrate 63b and the developing roller 62 and the distance between the developing roller 62 and the collection substrate 63c. The spacing is adjusted appropriately. As a result, the toner T can be supplied more appropriately to the photosensitive drum 3, and thus good image formation can be performed.

  In the non-image forming operation (that is, when the toner T is not transported by the transport substrate 63), as shown in FIG. 6, the distance between the vertical transport substrate 63b and the developing roller 62, and The distance between the developing roller 62 and the collection substrate 63c is set to be as narrow as possible. That is, the vertical conveyance substrate 63b and the toner carrying surface 62a are in contact with each other, and the toner carrying surface 62a and the collection substrate 63c are in contact with each other. Thereby, inadvertent leakage of the toner T from the toner box 61 during the non-image forming operation can be satisfactorily suppressed.

<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) 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, 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 °.

  (3) The voltage applied to the developing roller 62 may be only a direct current component (including ground).

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

  (5) 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 vertical transfer board 63b only needs to be erected substantially along the vertical direction, and may be slightly inclined. Similarly, the collection 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 portion of the vertical transfer substrate 63b.

  The end portion of the collection substrate 63c in the toner conveyance direction TTD may be connected to the bottom conveyance substrate 63a.

  (6) The interval adjusting means of the present invention is not limited to the specific configuration disclosed in the above embodiment.

  For example, instead of the mode in which the developing roller 62 and the collection substrate 63c move, the conveyance side panel 61a that supports the vertical conveyance substrate 63b and the collection side panel 61b that supports the collection substrate 63c each swing the lower end portion. You may comprise so that an upper end part may rock | fluctuate as a center. In this case, an actuator (such as a cam mechanism) for swinging the upper end portions of the transport side panel 61a and the collection side panel 61b can be provided.

  Further, the development along the toner transport path TTP depends on the characteristics (charge amount, etc.) of the toner T, the desired image formation density by the user, the density of the toner T on the toner carrying surface 62a of the developing roller 62, and the like. The positional relationship between the roller 62 and the vertical transfer substrate 63b may be adjusted (controlled).

  Specifically, as shown in FIG. 7, the distance between the vertical transport substrate 63b and the developing roller 62 and the distance between the developing roller 62 and the collection substrate 63c are controlled based on the output of the humidity sensor 68e. May be. In this case, when the humidity is high, the above-described interval is narrowed.

  Further, as shown in FIG. 8, based on the output of the charge amount sensor 68f (sensor element capable of measuring the surface potential) provided so as to face the vertical transport substrate 63b, the vertical transport substrate 63b and the development are developed. The distance between the roller 62 and the distance between the developing roller 62 and the collection substrate 63c may be controlled.

  (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 ... Transport side panel 61b ... Collection side panel 61c ... Semi-cylindrical part 61d ... Side wall 61e ... Toner storage part (developer storage part)
61f ... opening 61g ... slide hole 61h ... operation hole 62 ... developing roller (developer carrying member)
62a ... toner carrying surface 62b ... developing roller shaft 63 ... transfer board 63a ... bottom transfer board 63b ... vertical transfer board (upper transfer board)
63b1 ... upper end 63c ... recovery substrate 63d ... diaphragm 631 ... transfer electrode 631a ... bottom transfer electrode 631b ... vertical transfer electrode 631c ... recovery electrode 632 ... transfer electrode support film 633 ... transfer electrode coating layer 634 ... transfer electrode overcoating layer (insulation) layer)
634a ... bottom overcoating layer 634b ... vertical overcoating layer 634c ... recovery overcoating layer 64 ... transport power supply circuit 65 ... recovery power supply circuit 66 ... development bias power supply circuit 67 ... shielding plate 68 ... interval adjusting means 68a ... engaging portion 68b ... Actuator 68c ... Actuator 68d ... Control circuit 68e ... Humidity sensor 68f ... Charge amount sensor C ... Center axis DP ... Development position LB ... Laser beam 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 (developer transport path)

Japanese Patent Application Laid-Open No. 60-115962 Japanese Patent Laid-Open No. 11-84862 JP 2001-209246 A JP 2002-287495 A

Claims (10)

In the developer supply apparatus configured to supply the charged powdery developer to the supply target while being transported along the developer transport path by an electric field.
A box-shaped casing having an opening portion that opens upward toward the supply target and configured to store the developer in a developer storage portion at the bottom;
A roller-shaped member having a cylindrical peripheral surface, the developer carrying member provided facing the supply target while being accommodated inside the casing so as to face the opening;
A plurality of transport electrodes arranged along the developer transport path are provided, and the developer is transported along the developer transport path by an electric field generated when a voltage is applied to these transport electrodes. A transport substrate, which is configured as described above and supported by the inner wall surface of the casing;
An interval adjusting means for adjusting an interval between the developer carrying member and the transport substrate;
A developer supply apparatus comprising: The developer supply device according to claim 1,
The developer supply apparatus, wherein the transport substrate has an insulating layer on a surface thereof. The developer supply device according to claim 1 or 2,
The transport substrate includes an upper transport substrate provided to transport the developer upward toward the developer carrying member;
The developer supply device according to claim 1, wherein the distance adjusting unit is configured to adjust a distance between an upper end portion of the upper transport substrate facing the developer carrying member and the developer carrying member. The developer supply device according to claim 3,
The developer supply apparatus, wherein the upper transport substrate is provided so as to transport the developer vertically upward. The developer supply device according to claim 3 or 4, wherein
The developer supply apparatus according to claim 1, wherein the upper transport substrate is formed in a flat plate shape. A developer supply device according to any one of claims 3 to 5, comprising:
The transport substrate is provided to face the upper end portion of the upper transport substrate with the developer carrying member interposed therebetween so as to transport the developer downward to recirculate the developer to the developer reservoir. A developer supply apparatus, further comprising a recovery substrate, wherein the interval adjusting means is configured to adjust an interval between the recovery substrate and the developer carrying member. A developer supply device according to any one of claims 1 to 6,
The developer supply device according to claim 1, wherein the interval adjusting unit adjusts the interval according to a charge amount of the developer. A developer supply device according to any one of claims 1 to 7,
The developer supply apparatus according to claim 1, wherein the interval adjusting unit adjusts the interval according to humidity. A developer supply device according to any one of claims 1 to 8,
The developer supply device according to claim 1, wherein the interval adjusting unit adjusts the interval according to the newness of the developer. A developer supply device according to any one of claims 1 to 9,
The developer supplying device according to claim 1, wherein the interval adjusting means narrows the interval as much as possible when the developer conveying operation is not performed.

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