JP4674597B2 - Developer supply apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a developer supply device and an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus that includes a mechanism (hereinafter referred to as a “developer electric field transport mechanism”) that transports a developer (toner) using a traveling wave electric field is known (for example, Japanese Patent Application Laid-Open (JP-A)). JP-A-58-220156, JP-A-59-181371, JP-A-63-58386, JP-A-2003-241503, JP-A-2004-45943, etc.).

  The developer electric field transport mechanism includes a base material made of an insulating layer and a plurality of electrodes. These electrodes are arranged on the base material at a predetermined interval.

In the developer electric field transport device, a multiphase alternating voltage is applied to the plurality of electrodes. Thereby, a traveling-wave electric field is formed. The developer is transported in a predetermined direction by this electric field.
JP 58-220156 A JP 59-181371 A JP-A 63-58386 JP 2003-241503 A Japanese Patent Application Laid-Open No. 2004-45943

  In this type of apparatus, the developer transport state may be non-uniform in the width direction perpendicular to the transport direction. When such non-uniformity occurs, density unevenness also occurs in the formed image.

  The present invention has been made to solve such problems. That is, an object of the present invention is to provide a developer supply device that can more uniformly transport and supply the developer by a traveling wave electric field. Another object of the present invention is to provide a developing device that can develop an electrostatic latent image with a developer by providing such a developer supply device. Furthermore, an object of the present invention is to provide an image forming apparatus which can form a good image by effectively suppressing the occurrence of density unevenness by including such a developer supply device.

  The developer supply device of the present invention is configured to be able to supply a predetermined supply target in a state where the developer is charged.

  The image forming apparatus of the present invention includes the developer supply device and the developer carrier as the supply target. The developer carrying member has a developer carrying surface. The developer carrying surface is a surface parallel to a predetermined main scanning direction, and is configured to carry a charged developer. The developer carrier is configured such that the developer carrying surface can move along a sub-scanning direction orthogonal to the main scanning direction. In this case, the developer supply device is configured to supply the developer to the developer carrier while moving the developer in the charged state along the sub-scanning direction.

  The developer supply device of the present invention is disposed so as to face the developer carrying member disposed inside the image forming apparatus and can be detachably attached to the image forming apparatus.

  The developing device of the present invention includes the developer supply device and an electrostatic latent image carrier as the developer carrier. The electrostatic latent image carrier has a latent image forming surface as the developer carrying surface. The latent image forming surface is configured such that an electrostatic latent image by a potential distribution can be formed.

  The developer supply device includes a developer case and a developer transport body.

  The developer case is configured to accommodate the developer.

  The developer transport body is disposed to face the supply target so that the developer can be supplied from the surface (developer transport surface) to the supply target. The developer transport surface in the image forming apparatus is a surface facing the developer in the developer case and the developer carrying surface. The developer transport body is configured to transport the developer along the developer transport surface by forming a traveling-wave electric field.

  A feature of the present invention resides in that the developer transport body is configured to move up and down according to the amount of the developer contained in the developer case. For example, in the developer supply device, the developer transport body moves up and down according to the increase / decrease of the storage amount so that the developer transport surface is always in contact with the developer in the developer case. Can be configured. Alternatively, in the developer supply device, the distance between the developer transport surface and the developer in the developer case is made constant as the developer transport body moves up and down in accordance with an increase or decrease in the storage amount. Can be configured.

  Specifically, the developer transport body can be configured as follows: the developer transport body includes a supply surface and a pickup surface. The supply surface is a portion of the developer transport surface that faces the supply target. The pickup surface is a portion of the developer transport surface that faces the developer in the developer case. The developer transport body is configured such that the pickup surface moves up and down according to the amount of the developer contained in the developer case while the supply surface faces the supply target.

  Further, the pickup surface moves up and down according to the amount of the developer in the developer case so that the upper surface of the developer pool in the developer case and the pickup surface are always in contact with each other. Can be done.

  The developer supply apparatus may be configured as follows: The developer supply apparatus further includes a flattening member provided in the developer case. The flattening member is configured to flatten the upper surface of the pool.

  In the configuration of the present invention, for example, when the image forming operation is performed, the amount of the developer contained in the developer case is gradually reduced. Then, the upper surface of the developer in the developer case gradually decreases.

  Here, according to the configuration of the present invention, the developer carrier can be moved downward as the upper surface is lowered. Thereby, the positional relationship between the upper surface and the portion (the pickup surface) facing the upper surface on the developer transport surface can be maintained as much as possible. Therefore, the amount of the developer that starts to be transported from the portion on the developer transport surface is as much as possible in the width direction of the portion (direction perpendicular to the transport direction of the developer), that is, the main scanning direction. Can be uniform.

  As described above, according to the present invention, the developer can be transported and supplied more uniformly by a traveling wave electric field. Further, the occurrence of density unevenness in the formed image is effectively suppressed, and a good image can be formed.

  In particular, according to the present invention, the developer can be transported and supplied more uniformly without performing the flattening operation (such as stirring of the developer) of the upper surface by the flattening member so vigorously. . Therefore, the durability of the developer is improved.

  The developer supply apparatus may be configured as follows: the supply target has a cylindrical portion. The developer transport body is configured to move up and down according to the amount of the developer contained in the developer case by rotating about the cylindrical central axis.

  According to this configuration, when the developer transport body moves up and down due to the change in the upper surface, the distance between the developer transport surface and the surface to be supplied (the developer carrying surface) is approximately Maintained constant. Therefore, the developer supply state and the image forming state can be satisfactorily stabilized by a simple apparatus configuration.

  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.

  It should be noted that the following description of the embodiment is specific to the extent possible in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in. Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Various modifications that can be made to the present embodiment are listed together at the end, as they would interfere with the understanding of the consistent description of the embodiment if inserted during the description of the embodiment. .

<Schematic configuration of image forming apparatus>
FIG. 1 is a side sectional view showing a schematic configuration of a laser printer 1 which is an embodiment of an image forming apparatus of the present invention.

  Referring to FIG. 1, a paper transport mechanism 2 and a developing unit 3 are provided inside the laser printer 1. The developing unit 3 includes a latent image forming unit 4 and a toner supply device 5. A fixing device 6 is provided inside the laser printer 1.

  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 includes a plurality of paper transport rollers 21 and is configured to transport the paper P along a predetermined paper transport path PP.

  The developing unit 3 as the developing device of the present invention is configured to be detachable from a main body frame (not shown) of the laser printer 1. The developing unit 3 is configured to arrange toner T as fine particle dry developer on the paper P in accordance with image information received by the laser printer 1. In the present embodiment, it is assumed that the toner T is a positively chargeable, non-magnetic one-component black toner.

  The developing unit 3 includes a transfer roller 31. The transfer roller 31 is disposed so as to face the photosensitive drum 41 in the latent image forming unit 4 with the paper transport path PP interposed therebetween. The transfer roller 31 is connected to a bias power supply circuit (not shown). That is, a predetermined transfer bias voltage for transferring the positively charged toner T onto the paper P is applied between the transfer roller 31 and the photosensitive drum 41, so that the transfer roller 31 and the photosensitive drum 41 are transferred. The toner T on the photoconductive drum 41 is transferred onto the paper P at the transfer position TRP which is the closest position.

  The fixing device 6 is provided downstream of the transfer position TRP in the paper transport direction PFD. Here, the paper transport direction PFD is a tangential direction along the moving direction of the paper P at a certain position on the paper transport path PP. The fixing device 6 is configured to fix the image of the toner T on the paper P by heating and pressurizing the paper P.

<Detailed configuration of developing device>
FIG. 2 is an enlarged side sectional view showing the periphery of the developing unit 3 shown in FIG. Hereinafter, the detailed configuration of the developing unit 3 of the present embodiment will be described with reference to FIGS. 1 and 2.

<< Latent image forming part >>
The above-mentioned photosensitive drum 41 as a supply object, developer carrier, and electrostatic latent image carrier of the present invention is composed of a drum body 41a and a photosensitive layer 41b.

  The drum body 41a is a cylindrical member having a central axis parallel to the main scanning direction (z-axis direction in the figure), and is made of a metal such as aluminum. The drum body 41a is connected to the above-described bias power supply circuit so that the above-described transfer bias voltage is applied between the drum body 41a and the transfer roller 31.

  The photoreceptor layer 41b is provided so as to cover the outer periphery of the drum body 41a. The photoreceptor layer 41b is composed of a positively chargeable photoconductive layer that exhibits electron conductivity when exposed to laser light having a predetermined wavelength.

  The latent image forming surface 41b1 as the developer carrying surface of the present invention, which is the surface of the photoreceptor layer 41b, is formed as a cylindrical surface parallel to the main scanning direction. The latent image forming surface 41b1 is configured such that an electrostatic latent image can be formed by a potential distribution. The latent image forming surface 41b1 is configured such that the charged toner T can be carried in a pattern corresponding to the electrostatic latent image.

  The photosensitive drum 41 is configured to be rotationally driven in the direction of the arrow (counterclockwise) in the figure around the axis parallel to the main scanning direction. That is, the photosensitive drum 41 is configured so that the latent image forming surface 41b1 can move in a predetermined movement direction, that is, in a sub-scanning direction orthogonal to the main scanning direction.

  The latent image forming unit 4 includes a charger 42 and a scanner unit 43 in addition to the photosensitive drum 41 described above.

  The charger 42 is arranged to face the latent image forming surface 41b1 on the downstream side of the transfer position TRP in the moving direction of the latent image forming surface 41b1. The charger 42 is a scorotron charger, and is configured so that the latent image forming surface 41b1 can be uniformly positively charged.

  The scanner unit 43 is disposed on the downstream side of the charger 42 in the moving direction of the latent image forming surface 41b1 so as to face the latent image forming surface 41b1.

  The scanner unit 43 is configured to generate a laser beam LB modulated based on image data. That is, the scanner unit 43 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.

  The scanner unit 43 is configured to form an image of the generated laser beam LB on the latent image forming surface 41b1. Further, the scanner unit 43 is configured to move (scan) the position at which the laser beam LB is formed on the latent image forming surface 41b1 at a constant speed along the main scanning direction.

  That is, the scanner unit 43 is configured to form the electrostatic latent image on the latent image forming surface 41b1 by exposing the latent image forming surface 41b1.

<< Developer supply device >>
Referring to FIGS. 1 and 2, the toner supply device 5 as the developer supply device of the present invention is disposed so as to face the photosensitive drum 41 at the development position DP. The toner supply device 5 is configured as follows so as to supply the toner T to the latent image forming surface 41b1 at the development position DP while moving the charged toner T along the sub-scanning direction. Yes.

  A toner box 51 that forms a casing of the toner supply device 5 is a box-like member, and is configured to store toner T therein. That is, a toner reservoir TP that is an aggregate of toner T is accommodated in the toner box 51 as the developer case of the present invention.

  A flattening member 52 is attached to the toner box 51. The planarizing member 52 of the present embodiment is made of a plate-like piezoelectric vibrator, and is fixed to the back side of the bottom plate of the toner box 51 (the side opposite to the side facing the space where the toner T is stored). The flattening member 52 is configured to flatten the upper surface of the toner reservoir TP (hereinafter referred to as “toner reservoir surface TPS”).

  The toner supply device 5 is provided with a toner amount sensor 53. The toner amount sensor 53 is configured to output a signal corresponding to the amount of toner T stored in the toner box 51, that is, the position of the toner reservoir surface TPS. In the present embodiment, the toner box 51 includes an optical sensor and is attached to the side surface of the toner box 51.

<<< Developer transport body >>>
The toner supply device 5 is provided with a pickup substrate 54 as a developer conveying member of the present invention. In the present embodiment, the pickup substrate 54 is formed in a cylindrical shape.

  The pickup substrate 54 is configured to be able to transport the toner T in the toner transport direction TTD on the toner transport surface 54a that is the outer surface of the cylindrical shape by forming a traveling wave electric field.

  In the present embodiment, the toner conveyance surface 54a is formed in parallel with the main scanning direction (z-axis direction in the drawing). That is, the pickup substrate 54 is configured such that the toner transport direction TTD is a direction perpendicular to the main scanning direction.

  In the present embodiment, the pickup substrate 54 is formed in an oval shape (a shape in which two opposing semicircles are connected by a straight line) having a longitudinal direction along the vertical direction in a side sectional view. Yes. A portion of the pickup substrate 54 in the longitudinal direction that is opposite to the toner reservoir TP (a lower end portion in the drawing) is disposed in the toner box 51.

  Here, the portion of the toner transport surface 54a that faces the toner reservoir surface TPS (the lower end of the toner transport surface 54a) is hereinafter referred to as “pickup surface 54a1”. Similarly, a portion of the toner transport surface 54a downstream of the pickup surface 54a1 in the toner transport direction TTD and capable of supplying the toner T from the pickup substrate 54 to another member (supply target) (development substrate described later) The portion facing 56) is hereinafter referred to as "supply surface 54a2."

  In the present embodiment, the pickup surface 54a1 is formed in a downward substantially cylindrical surface shape. Further, the supply surface 54a2 is formed in a substantially planar shape that stands vertically.

  FIG. 3 is an enlarged side sectional view of the pickup substrate 54 shown in FIG. Referring to FIG. 3, the pickup substrate 54 has the same configuration as the flexible printed circuit board. Specifically, the pickup substrate 54 includes a base layer 54b, a transport electrode 54c, and a coating layer 54d.

  The base layer 54b is a flexible film and is formed of an insulating synthetic resin such as a polyimide resin.

  The transport electrode 54c is made of a copper foil having a thickness of about several tens of μm, and is formed on the surface of the base layer 54b. The transport electrode 54c is formed as a linear wiring pattern having a longitudinal direction parallel to the main scanning direction (perpendicular to the sub-scanning direction).

  The coating layer 54d is made of an insulating synthetic resin. The coating layer 54d is provided so as to cover the surface of the base layer 54b on which the transport electrode 54c is provided and the transport electrode 54c. The above-mentioned toner transport surface 54a, which is the surface of the coating layer 54d, is formed as a smooth surface with very few irregularities.

  Here, the transport electrode 54c is disposed along the toner transport surface 54a. That is, the transport electrode 54c is disposed in the vicinity of the toner transport surface 54a.

  The plurality of transport electrodes 54c are arranged in parallel to each other. The plurality of transport electrodes 54c are arranged along the sub-scanning direction. Each of the plurality of transport electrodes 54c is connected to the same power circuit every third.

  That is, the transfer electrode 54c connected to the power supply circuit VA, the transfer electrode 54c connected to the power supply circuit VB, the transfer electrode 54c connected to the power supply circuit VC, the transfer electrode 54c connected to the power supply circuit VD, and the power supply circuit VA The transport electrodes 54c connected, the transport electrodes 54c connected to the power supply circuit VB, the transport electrodes 54c connected to the power supply circuit VC are arranged in order along the sub-scanning direction.

  FIG. 4 is a graph showing waveforms of voltages generated by the power supply circuits VA to VD shown in FIG. As shown in FIG. 4, each of the power supply circuits VA to VD is configured to output an alternating voltage (carrier voltage) having substantially the same waveform. Further, the power supply circuits VA to VD are configured so that the phases of the waveforms of the voltages generated by the power supply circuits VA to VD are different by 90 °. That is, the voltage phase is delayed by 90 ° in order from the power supply circuit VA to the power supply circuit VD.

  Referring to FIGS. 1 and 2 again, the pickup substrate 54 is supported by the movable support body 55. The movable support 55 is made of a metal such as aluminum and is connected to the bias power supply circuit. The movable support 55 is configured to move up and down in the figure by a well-known vertical movement mechanism (not shown).

  That is, the pickup substrate 54 in this embodiment is moved up and down by the movable support 55 according to the amount of toner T stored in the toner box 51 while the supply surface 54a2 faces the supply target. It is configured.

  Specifically, the toner supply device 5 according to the present embodiment is configured such that the pickup surface 54a1 is always in contact with the toner reservoir TP when the pickup substrate 54 moves up and down in accordance with the increase or decrease of the accommodation amount. . In other words, the toner supply device 5 according to the present embodiment is configured such that the distance between the pickup surface 54a1 and the toner reservoir surface TPS becomes constant as the pickup substrate 54 moves up and down in accordance with the increase or decrease of the accommodation amount. Has been.

  A developing substrate 56 is disposed between the pickup substrate 54 and the photosensitive drum 41. The development substrate 56 has the same configuration as the pickup substrate 54 described above.

  The development substrate 56 is disposed so as to face the supply surface 54a2. In the present embodiment, the development substrate 56 is supported on the peripheral surface of a cylindrical development substrate support 57. Here, the position where the pickup substrate 54 (supply surface 54a2) and the development substrate 56 face each other is hereinafter referred to as a “supply position FP”.

  The development substrate support 57 is made of metal such as aluminum and is connected to the bias power supply circuit.

  That is, a predetermined supply bias voltage for transferring the positively charged toner T from the pickup substrate 54 to the development substrate 56 is applied between the movable support 55 and the development substrate support 57. Further, a positively charged toner T is moved between the developing substrate support 57 and the drum body 41a from the developing substrate 56 onto the photosensitive layer 41b (latent image forming surface 41b1) according to the electrostatic latent image. Therefore, a predetermined developing bias voltage is applied.

<Operation of Image Forming Apparatus>
Next, the operation of the laser printer 1 configured as described above will be described with reference to the drawings as appropriate.

<< Overview of Image Forming Operation >>
First, referring to FIG. 1, the paper P stacked on a paper feed tray (not shown) is fed by the paper transport roller 21 to the transfer position TRP along the paper transport path PP. During this time, an image of the toner T is carried on the latent image forming surface 41b1 that is the peripheral surface of the photosensitive drum 41 as follows.

  First, the latent image forming surface 41b1 is uniformly charged positively by the charger 42.

  The latent image forming surface 41b1 charged by the charger 42 is rotated in the sub-scanning direction to the position facing the scanner unit 43 by the rotation of the photosensitive drum 41 in the direction indicated by the arrow (counterclockwise). Move along. At this position, the laser beam LB modulated based on the image information is irradiated onto the latent image forming surface 41b1 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 latent image forming surface 41b1 disappear is generated. As a result, the electrostatic latent image having a positive charge pattern (image-like distribution) is formed on the latent image forming surface 41b1.

  The electrostatic latent image formed on the latent image forming surface 41b1 moves toward the developing position DP by the rotation of the photosensitive drum 41 in the direction indicated by the arrow in the drawing (counterclockwise).

  Referring to FIG. 3, a traveling wave voltage as shown in FIG. 4 is applied to the plurality of transport electrodes 54c. As a result, a predetermined traveling-wave electric field is formed on the toner transport surface 54a. By this traveling wave electric field, the positively charged toner T is transported on the toner transport surface 54a along the toner transport direction TTD as follows.

  5A to 5C are enlarged side sectional views showing the periphery of the toner conveying surface 54a shown in FIG. In FIG. 3, the transport electrode 54c connected to the power supply circuit VA is shown as the transport electrode 54cA in FIGS. 5A to 5C. The same applies to the transport electrodes 54cB to 54cD.

  Hereinafter, how the positively charged toner T is transported in the toner transport direction TTD on the toner transport surface 54a will be described with reference to FIGS. 3, 4, and 5A to 5C.

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

  At time t1 in FIG. 4, as shown in FIG. 5A, an electric field EF1 opposite to the toner transport direction TTD is formed at the position AB between the transport electrode 54cA and the transport electrode 54cB. Is done.

  On the other hand, an electric field EF2 having the same direction as the toner transport direction TTD is formed at a position between CDs, which is a position between the transport electrode 54cC and the transport electrode 54cD.

  Further, the position between BC, which is the position between the transport electrode 54cB and the transport electrode 54cC, and the position between DA, which is the position between the transport electrode 54cD and the transport electrode 54cA, are in the direction along the toner transport direction TTD. An electric field is not formed.

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

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

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

  Therefore, at time t1, the positively charged toner T is collected at the position between the DAs. Similarly, at time t2, the positively charged toner T is collected at the position between AB. Next, at time t3, the positively charged toner T is collected at the position between BC.

  That is, the region where the toner T is collected moves on the toner transport surface 54a along the toner transport direction TTD with the passage of time.

  In this way, a voltage as shown in FIG. 4 is applied to each transport electrode 54c, whereby a traveling-wave electric field is formed on the toner transport surface 54a. As a result, the positively charged toner T is transported along the toner transport direction TTD while hopping in the vertical direction in the figure.

  Referring to FIG. 2, the toner reservoir TP is vibrated by the flattening member 52. As a result, the toner reservoir TP behaves like a liquid, and the toner reservoir surface TPS becomes a smooth surface such as a water surface.

  Here, the position of the pickup substrate 54 is set by the movable support 55 at a position where the lowermost end portion (the portion closest to the toner reservoir surface TPS) of the pickup surface 54a1 is in contact with the toner reservoir surface TPS. .

  Accordingly, the positively charged toner T is transported on the pickup surface 54a1 in the toner transport direction TTD with the contact portion between the toner reservoir surface TPS and the pickup surface 54a1 as a base point. The toner T runs up the pickup surface 54a1 and the supply surface 54a2, and is conveyed to the supply position FP.

  The toner T conveyed to the supply position FP by the pickup substrate 54 is transferred onto the developing substrate 56 at the supply position FP by the supply bias voltage described above. That is, the developing substrate 56 receives the toner T from the pickup substrate 54. Then, as in the case of the pickup substrate 54 described above, the developing substrate 56 conveys the toner T toward the developing position DP in the direction indicated by the arrow in the drawing.

  Then, the electrostatic latent image on the latent image forming surface 41b1 is developed by the toner T in the vicinity of the development position DP. That is, the toner T adheres to the portion on the latent image forming surface 41b1 where the positive charge in the electrostatic latent image has disappeared. As a result, an image of the toner T (hereinafter referred to as “toner image”) is carried on the latent image forming surface 41b1.

  Referring to FIG. 1, the toner image carried on the latent image forming surface 41b1 as described above is rotated in the direction indicated by the arrow (counterclockwise) in the latent image forming surface 41b1. Thus, the sheet is conveyed toward the transfer position TRP. At the transfer position TRP, the toner image is transferred onto the paper P from the latent image forming surface 41b1. The toner image transferred onto the paper P is fixed on the surface of the paper P by the fixing device 6.

<< Operation / Effects of Configuration of Embodiment >>
FIG. 6 is a side sectional view showing an operating state of the toner supply device 5 shown in FIG.

  When the amount of toner T stored in the toner box 51 decreases with the image forming operation, the toner reservoir surface TPS is lowered. The position or descending amount of the toner reservoir surface TPS is detected based on the output from the toner amount sensor 53. In this case, based on the output from the toner amount sensor 53, the movable support 55 is lowered as shown in FIG.

  On the other hand, when the toner T is replenished in the toner box 51, the toner reservoir surface TPS rises. The position or rising amount of the toner reservoir surface TPS is detected based on the output from the toner amount sensor 53. In this case, based on the output from the toner amount sensor 53, the movable support 55 is raised as shown in FIG.

  As described above, in the configuration of the present embodiment, the vertical position of the movable support 55 is adjusted based on the output from the toner amount sensor 53. Then, as shown in FIG. 2 and FIG. 6, a predetermined state of contact between the lowermost end portion of the pickup surface 54a1 and the toner reservoir surface TPS is well maintained. Therefore, the toner T within the range where the traveling wave electric field on the pickup surface 54a1 acts favorably is conveyed to the supply position FP.

  According to the configuration of the present embodiment, the supply amount of the toner T at the supply position FP is stabilized. In particular, the variation in the supply amount in the main scanning direction is suppressed as much as possible. Thereby, the supply amount of the toner T at the development position DP is also stabilized. Accordingly, the occurrence of density unevenness in the image formed on the paper P is effectively suppressed, and a good image can be formed.

  In this embodiment, the toner reservoir TP is vibrated by the flattening member 52 during the toner transport operation. As a result, the toner reservoir surface TPS is smoothed like a water surface. Therefore, the contact state between the toner reservoir surface TPS and the pickup surface 54a1 is made as uniform as possible in the main scanning direction. Therefore, the supply state of the toner T is made as uniform as possible in the main scanning direction.

  Further, in the present embodiment, the pickup surface 54a1 is formed in a substantially cylindrical shape that faces downward, and the supply surface 54a2 is formed in a substantially planar shape that stands vertically.

  According to this configuration, only the toner T that is well charged with a predetermined polarity and charge amount runs up to the pickup surface 54a1 and the supply surface 54a2 and is conveyed to the supply position FP. Only the good toner T thus “selected” is transported to the development position DP by the development substrate 56. Therefore, the occurrence of disturbance in the formed image due to the adhesion of the low-charge or reverse-charge toner T to the white background can be suppressed as much as possible.

<List of examples of modification>
Note that, as described above, the above-described embodiment is merely an example of the embodiment of the present invention considered to be the best at the time of filing of the present application by the applicant, and the present invention is not limited to the above. It should not be limited at all by the embodiment. Therefore, as a matter of course, various modifications can be made to the specific configurations shown in the above-described embodiments within the scope not changing the essential part of the present invention.

  Hereinafter, some modifications will be exemplified. Here, in the following description of the modified example, components having the same configurations and functions as the components in the above-described embodiment are given the same name and the same reference numerals in the modified example. And And about description of the said component, description in the above-mentioned embodiment shall be used suitably in the range which is not inconsistent.

  However, it goes without saying that the modified examples are not limited to the following. Limiting and interpreting the present invention based on the description of the above-described embodiment and the following modifications unfairly harm the applicant's interests (especially rushing applications under the principle of prior application), but unfairly imitators It is beneficial and not allowed.

  Further, it goes without saying that the configuration of the above-described embodiment and the configuration described in each of the following modifications can be applied in an appropriate combination within a technically consistent range.

  (1) The application target of the present invention is not limited to a so-called monochrome laser printer capable of forming a monochrome image. For example, the present invention can be suitably applied to a so-called electrophotographic image forming apparatus such as a laser printer capable of forming a multicolor (full color) image or a monochromatic and color copying machine.

  Alternatively, the present invention can be suitably applied to an image forming apparatus of a system other than the above-described electrophotographic system (for example, an image forming apparatus of a toner jet system or an ion flow system that does not use a photoreceptor).

  (2) The transfer roller 31 may be provided outside the developing unit 3.

  (3) The flattening member 52 made of a plate-like piezoelectric vibrator may be disposed inside the toner box 51 or may constitute a part of the toner box 51.

  The planarizing member 52 is not limited to a piezoelectric vibrator. For example, an agitator composed of rotating blades may be used.

  (4) The toner amount sensor 53 may be attached to the main body frame (not shown) in the laser printer 1.

  Further, the toner amount sensor 53 can be omitted.

  In this case, the pickup substrate 54 (movable support 55) is lowered according to, for example, the number of image formations and the operation time, and returned to a predetermined initial position according to the replenishment of the toner T or the replacement of the toner box 51 ( Ascending to the initial position).

  Alternatively, in this case, the pickup substrate 54 is placed on the toner reservoir surface TPS so that the pickup substrate 54 descends as the toner reservoir surface TPS descends and is pushed up by the toner reservoir surface TPS ascending. Can be done. In this configuration, the movable support 57 can be omitted.

  (5) The configurations of the pickup substrate 54 and the development substrate 56 are not limited to those shown in the above embodiment. For example, the coating layer 54d can be omitted.

  (6) The pickup substrate 54 and the development substrate 56 can be fused. That is, either one of them can be omitted.

  FIG. 7 is a side sectional view showing a configuration of one modified example of the toner supply device 5 shown in FIG. FIG. 8 is a side sectional view showing an operating state of the toner supply device 5 of the modification shown in FIG. 7 and 8, the toner amount sensor 53 (see FIGS. 2 and 6) is not shown.

  Referring to FIGS. 7 and 8, the developing substrate 56 as the developer transport body of the present invention is formed in a cylindrical shape as in the above-described embodiment.

  In the present modification, the development substrate 56 is disposed so as to face the space for storing the toner T in the toner box 51. That is, the toner transport surface 56 a that is the outer surface of the developing substrate 56 is disposed so as to face the toner reservoir TP and the photosensitive drum 41.

  A pickup surface 56a1, which is a portion facing the toner reservoir TP on the toner transport surface 56a, is formed in a substantially downward cylindrical surface. Further, the supply surface 56a2 which is a portion facing the photosensitive drum 41 in the toner transport surface 56a is formed in a substantially cylindrical surface shape facing sideways.

  Further, in the present modification, the central axis 41c of the drum body 41a is fixed to the main body frame (not shown). The central axis of the drum body 41 a and the central axis 56 c of the developing substrate support 57 are connected by a connection member 320. That is, the developing substrate support 57 is configured to rotate around a cylindrical central axis 41c of the drum body 41a as a rotation center.

  In such a configuration, the developing substrate support 57 and the developing substrate 56 supported by the developing substrate support 57 rotate about the central axis 41c in accordance with the amount of toner T stored in the toner box 51. As a result, the pickup surface 56a1 on the developing substrate 56 moves up and down with the fluctuation of the toner reservoir surface TPS.

  According to the configuration of this modification, the distance between the supply surface 56a2 and the latent image forming surface 41b1 is maintained substantially constant when the developing substrate 56 moves up and down due to the change in the toner reservoir surface TPS. Therefore, the supply state of the toner T and the image forming state can be satisfactorily stabilized with a simple apparatus configuration.

  (6) The configuration of the latent image forming unit 4 is not limited to that disclosed in the above-described embodiment.

  FIG. 9 is a side sectional view showing a configuration of a modified example of the toner supply device 5 shown in FIGS. 7 and 8 (another modified example of the toner supply device 5 shown in FIG. 2).

  Referring to FIG. 9, the photoconductor unit 41 'includes a belt support roller 41a' and a photoconductor belt 41b '. The belt support roller 41a 'corresponds to the drum body 41a in FIG. The photoreceptor belt 41b 'is formed in an endless belt shape. That is, in FIG. 9, the photoreceptor layer 41b in FIG. 7 is replaced with an endless belt-like photoreceptor belt 41b '.

  Even in such a configuration, the same operations and effects as those of the above-described embodiments and modifications are achieved.

  (7) Other modifications not specifically mentioned are naturally included in the scope of the present invention as long as they do not change 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.

1 is a side sectional view showing a schematic configuration of a laser printer which is an embodiment of an image forming apparatus of the present invention. FIG. 2 is a side cross-sectional view showing an enlargement of the periphery of the developing unit shown in FIG. 1. FIG. 3 is an enlarged side cross-sectional view of the pickup substrate shown in FIG. 2. 4 is a graph showing a waveform of a voltage generated by the power supply circuit shown in FIG. 3. FIG. 4 is an enlarged side sectional view showing a periphery of a toner conveyance surface shown in FIG. 3. FIG. 4 is an enlarged side sectional view showing a periphery of a toner conveyance surface shown in FIG. 3. FIG. 4 is an enlarged side sectional view showing a periphery of a toner conveyance surface shown in FIG. 3. FIG. 3 is a side sectional view showing an operation state of the toner supply device shown in FIG. 2. FIG. 4 is a side sectional view showing a configuration of one modified example of the toner supply device shown in FIG. 2. FIG. 8 is a side cross-sectional view illustrating an operation state of the toner supply device according to the modified example illustrated in FIG. 7. FIG. 9 is a side sectional view showing a configuration of a modified example of the toner supply device shown in FIGS. 7 and 8 or another modified example of the toner supply device shown in FIG. 2.

Explanation of symbols

1. Laser printer (image forming device)
3. Development unit (developing device)
320 ... Connecting member 4 ... Latent image forming unit 41 ... Photosensitive drum (supply object / developer carrier / electrostatic latent image carrier)
41a ... drum body 41b ... photoreceptor layer 41b1 ... latent image forming surface (developer carrying surface)
41c ... center shaft 41'photosensitive unit 41a '... belt support roller 41b' ... photosensitive belt 5 ... toner supply device (developer supply device)
51. Toner box (developer case)
52 ... Flattening member 53 ... Toner amount sensor 54 ... Pickup substrate (developer carrier)
54a ... toner transport surface (developer transport surface)
54a1 ... pickup surface 54a2 ... supply surface 54b ... base layer 54c ... transport electrode 55 ... movable support 56 ... development substrate (supply target / developer transport body)
56a ... Toner transport surface (developer transport surface)
56a1 ... pickup surface 56a2 ... supply surface 56c ... central axis 57 ... development substrate support DP ... development position FP ... supply position P ... paper PP ... paper transport path T ... toner (developer)
TP ... Toner reservoir TRP ... Transfer position TPS ... Toner reservoir surface TTD ... Toner transport direction

Claims (10)

In the developer supply apparatus configured to be able to supply a predetermined supply object in a charged state with the developer,
A developer case configured to accommodate the developer; and
By forming a traveling-wave electric field at a smooth surface developer transport surface, along the developer transport surface is configured so as to transport the developer from the developer transport surface A developer transport body arranged to face the supply target so that the developer can be supplied to the supply target;
A flattening member provided to vibrate and fluidize the developer pool in order to planarize the upper surface of the developer pool in the developer case;
With
The developer carrier is
The developer transport surface has a pickup surface that is a portion facing the developer in the developer case;
Positions of the upper surface of the developer reservoir and the pickup surface in the developer case flattened by the flattening means by moving up and down according to the amount of the developer contained in the developer case A developer supply device configured to maintain the relationship constant. The developer supply device according to claim 1,
The developer transport surface further includes a supply surface that is a portion facing the supply target,
A developer supply device configured to move up and down according to the amount of the developer contained in the developer case while the supply surface faces the supply target . The developer supply device according to claim 2,
The pickup surface moves up and down according to the amount of the developer contained in the developer case, so that the upper surface of the developer pool in the developer case and the pickup surface are always in contact with each other. A developer supply device, comprising: The developer supply device according to claim 3 ,
The developer supply device , wherein an upper surface of the developer reservoir in the developer case and a lowermost end portion of the pickup surface are always in contact with each other . The developer supply device according to any one of claims 2 to 4,
The supply object has a cylindrical portion,
The developer transport body is configured to move up and down according to the amount of the developer contained in the developer case by rotating about the central axis of the cylindrical shape. A developer supply device. The developer carrying surface is a surface parallel to a predetermined main scanning direction and capable of carrying a charged developer, and the developer carrying surface moves along a sub-scanning direction orthogonal to the main scanning direction. A developer carrier configured to be able to
A developer supply device configured to supply the developer to the developer carrier while moving the developer along the sub-scanning direction in a charged state;
In an image forming apparatus comprising:
The developer supply device includes:
A developer case configured to accommodate the developer; and
The developer in the developer case and a developer transport surface that is a smooth surface facing the developer carrying surface are provided along the developer transport surface by forming a traveling wave electric field. A developer transport body configured to transport the developer , and disposed to face the developer support body so as to supply the developer from the developer transport surface to the developer support body. When,
A flattening member provided to vibrate and fluidize the developer pool in order to planarize the upper surface of the developer pool in the developer case;
With
The developer carrier is
The developer conveying surface has a pickup surface that is a portion facing the developer in the developer case;
Positions of the upper surface of the developer reservoir in the developer case and the pickup surface that are flattened by the flattening means by moving up and down according to the amount of the developer contained in the developer case An image forming apparatus configured to maintain the relationship constant. The image forming apparatus according to claim 6,
The developer transport surface further includes a supply surface that is a portion facing the supply target,
Image forming, wherein the pickup surface moves up and down according to the amount of developer contained in the developer case while the supply surface faces the developer carrying member. apparatus. The image forming apparatus according to claim 7,
The developer carrier is
The pickup surface moves up and down according to the amount of the developer contained in the developer case, so that the upper surface of the developer pool in the developer case and the pickup surface are always in contact with each other. An image forming apparatus configured as described above. The image forming apparatus according to claim 8, wherein
An image forming apparatus , wherein an upper surface of the developer reservoir in the developer case and a lowermost end portion of the pickup surface are always in contact with each other . An image forming apparatus according to any one of claims 7 to 9,
The developer carrier has a cylindrical portion,
The developer transport body is configured to move up and down according to the amount of the developer contained in the developer case by rotating about the central axis of the cylindrical shape. An image forming apparatus.

Images