JP4391215B2 - Toner conveying device, developing device, and image forming apparatus - Google Patents

Description

  The present invention relates to a toner conveying device that conveys toner on the surface of an electrostatic conveying means by moving relative to the surface by electrostatic force, and a developing device and an image forming apparatus using the toner conveying device.

  Conventionally, there are known image forming apparatuses such as copying machines, facsimile machines, and printers described in Patent Document 1 and Patent Document 2. In these image forming apparatuses, toner carried on a developer carrying member such as a developing roller that moves on the surface is transported to a developing position that is opposed to the latent image carrying member such as a photosensitive member, and the toner image is transferred onto the latent image carrying member. The electrostatic latent image is developed. In such a configuration, the toner rubs between the developer carrying member whose surface moves and the latent image carrying member, and adheres to one of the surfaces, which may adversely affect the image. Further, at the development position, the toner is electrostatically moved by the potential difference between the surface of the developer carrying member and the electrostatic latent image on the latent image carrying member, but this potential difference has to be considerably increased. Prior to the start of electrostatic movement, it is necessary to give the toner a force that overcomes the adhesion force between the toner and the developer carrying member due to van der Waals force, mirror image force, etc., and to solve the adhesion state. This is because electrostatic force is required.

  On the other hand, an image forming apparatus described in Patent Document 3 is known as an image forming apparatus that transports toner to the development position and contributes to development without depending on the surface movement of the developer carrying member. The developing device of this image forming apparatus causes an EH (Electrostatic Transport & Hopping) phenomenon on the surface of the electrostatic transport substrate on which a plurality of electrodes are arranged at a predetermined pitch, and transports the toner to the development position. The EH phenomenon is a phenomenon in which the energy of the phase-shift electric field acting on the powder is converted into mechanical energy and the powder itself dynamically changes. The toner in which the EH phenomenon has occurred jumps on the surface of the electrostatic transport substrate with a component in the traveling direction due to the phase-shift electric field, and moves in the direction of the substrate surface (transport) and moves in the direction perpendicular to the substrate surface ( Hopping). By transporting the toner to the development position while hopping the toner on the electrostatic transport substrate, it is possible to realize low-potential development that cannot be realized with a configuration using a developer carrier that moves on the surface. For example, toner can be selectively attached to an electrostatic latent image having a potential difference of only a few tens [V] with respect to surrounding non-image portions.

JP-A-9-197781 JP-A-9-329947 JP 2002-341656 A

  The present inventors have a situation in which toner cannot be hopped well on an electrostatic transport substrate while various tests are performed using a tester of an image forming apparatus that transports toner by an EH phenomenon. I often encountered it. Then, after earnest research on the cause, we found the following. That is, when the environment is relatively humid, moisture adhering to the surface of the toner or the electrostatic transport substrate causes a liquid cross-linking phenomenon between them. As a result, the adhesive force between the toner and the electrostatic transfer substrate is increased, which prevents good hopping of the toner.

  The present invention has been made in view of the above background, and an object of the present invention is to provide the following toner conveying device, and a developing device and an image forming apparatus using the toner conveying device. That is, it is a toner conveying device or the like that can suppress a situation where toner hopping due to the EH phenomenon is hindered by moisture.

To achieve the above object, a first aspect of the invention, the toner conveying device having an electrostatic transfer means for transferring the toner on the surface is relatively moved relative to the surface by an electrostatic force, the electrostatic transfer means Using a base material and a surface layer laminated on the base material directly or via an intermediate layer, and heating the surface layer with a heat generating layer fixed between the base material and the surface layer. The heating means to provide is provided.
According to a second aspect of the present invention, in the toner conveying device of the first aspect, the electrostatic conveying means has a surface layer that exhibits water repellency superior to the second layer below it. It is characterized by this.
According to a third aspect of the present invention, there is provided the toner conveying apparatus according to the first aspect, wherein the electrostatic conveying means has a surface layer made of any one of a resin, an inorganic nitrogen compound, and an inorganic carbon compound. To do .
Also, the invention of claim 4 is the toner conveying device according to claim 1, 2 or 3, as the electrostatic transfer means, among the conveying direction orthogonal the toner conveying direction in the surface direction thereto, the A plurality of transport electrodes arranged so as to be aligned in the toner transport direction while extending in the transport orthogonal direction, and the transport to the combination so as to conduct in common to a predetermined combination of the transport electrodes Using one having a pair of busbar electrodes connected at both ends in the orthogonal direction, and providing a potential difference generating means for generating a potential difference between the electrodes in the busbar electrode pair, causing the combination and the busbar electrode pair to generate heat by the potential difference, It is made to function as a heat generating part of the heating means .
Also, the invention of claim 5, the toner present on the surface of the electrostatic transporting means provided in the conveying means to the position facing the latent image carrier while relatively moving with respect to the surface by an electrostatic force In the developing device that transports and develops the latent image carried on the latent image carrier, the toner transport device according to any one of claims 1 to 4 is used as the toner transport means. is there.
According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising: a latent image carrier that carries a latent image; and a developing unit that develops the latent image on the latent image carrier into a toner image. The developing device according to claim 5 is used .

In these inventions, by prompting the evaporation of moisture from the surface to heat the electrostatic conveying means, it is possible to suppress a situation hinders the moisture hopping toner by EH phenomenon.

Now, the present invention laser printer (hereinafter, simply referred to as a printer) as an image forming apparatus of the electrophotographic type described implementation form of application to. Figure 1 is a schematic configuration diagram showing a printer according to the present implementation embodiment. The printer includes a charging unit 12, an optical writing unit 7, a developing device 100, a registration roller pair 15, a transfer roller 16, a fixing device 19, a drum cleaning device 22, a discharge lamp 23, and the like around a drum-shaped photoconductor 11. It has. Further, a pair of paper discharge rollers 20 disposed at the top of the printer housing, a paper feed cassette 13 serving as a paper feed means configured to be detachable from the printer housing, and the like are also provided.

  The photoconductor 11 is rotated clockwise in the drawing by a driving means (not shown). The surface of the photoreceptor 11 that is rotationally driven in this way is uniformly charged by corona discharge or the like from the charging unit 12 when passing the position facing the charging unit 12. The optical writing unit 7 performs optical scanning with the laser light L on the surface of the uniformly charged photoreceptor 11 based on an image signal sent from a personal computer (not shown) or the like. Thereby, an electrostatic latent image is formed on the exposed portion of the photoreceptor 11. The electrostatic latent image is conveyed to a developing position that is a region facing the developing device 100 as the photoconductor 11 rotates. Then, after the toner image is developed by adhesion of toner flying from the developing device 100, the toner image is sent to a transfer nip formed by contact between the photoconductor 11 and a transfer roller 16 having at least a surface made of an elastic material. .

  On the other hand, the paper feed cassette 13 accommodates a plurality of transfer paper P as a recording medium in a state of a stack of transfer paper, and presses the paper feed roller 13a against the uppermost transfer paper P. Then, the sheet feeding roller 13a is rotated counterclockwise in the drawing at a predetermined timing, and the uppermost transfer sheet P is sent out toward the sheet feeding path. The fed transfer paper P is sandwiched between rollers of a registration roller pair 15 disposed at the end of the paper feed path. When the registration roller pair 15 sandwiches the leading end side of the transfer sheet P, the rotation of both rollers is stopped immediately. Then, both rollers are rotated again at a timing at which the transfer paper P can be superimposed on the toner image on the photoconductor 11 at the transfer nip, and the transfer paper P is fed toward the transfer nip. The transferred transfer paper P is superimposed on the toner image on the photoconductor 11.

  In the transfer nip, a transfer electric field is formed between the transfer roller 16 to which a transfer bias is applied by a power source (not shown) and the electrostatic latent image area on the photoconductor 11. The toner image on the photoconductor 11 is transferred from the surface of the photoconductor 11 to the surface of the transfer paper P under the influence of the transfer electric field and nip pressure. Then, along with the rotation of the photoconductor 11 and the transfer roller 16, it is sent together with the transfer paper P to the fixing device 19.

  The fixing device 19 moves both rollers in the same direction within the nip while forming a fixing nip by a fixing roller 19a containing a heat source such as a halogen lamp and a pressure roller 19b contacting the fixing roller 19a with a predetermined pressure. Rotate to let The transfer paper P fed into the fixing device 19 from the transfer nip is fixed to the surface of the transfer paper P by heating or pressurization while being conveyed while being sandwiched by the fixing nip. After the fixing, the transfer paper P passes between the rollers of the paper discharge roller pair 20 and is then discharged out of the apparatus and stacked.

  On the surface of the photoconductor 11 after passing through the transfer nip, untransferred toner remaining without being transferred onto the transfer paper P is adhered. The untransferred toner is mechanically scraped and removed from the drum surface by the cleaning brush when passing through a region facing the drum cleaning device 22 as the surface of the photoconductor 11 moves. The surface of the photoreceptor 11 cleaned in this way is discharged by light irradiation from the discharging lamp 23, and is then uniformly charged again by the charging means. In addition, although the example which provided the thing of the charger system by corotron etc. as the charging means 12 was demonstrated, the thing of the system by the charging roller etc. to which a charging bias is applied may be used.

  FIG. 2 is an enlarged configuration diagram showing the photoreceptor 11 and the electrostatic transfer substrate 101 of the developing device (100). In the developing device (100), toner is supplied onto the electrostatic transport substrate 101 from a toner supply unit described later in a region (not shown). The electrostatic transport substrate 101 is arranged such that a plurality of strip-shaped transport electrodes are arranged at a predetermined pitch in the longitudinal direction of the substrate (left and right in the figure) with respect to an insulating substrate 101d made of glass or the like. These transport electrodes have a width dimension (dimension in the longitudinal direction of the substrate) of 30 [μm], and are arranged in parallel via a gap of 30 [μm]. With such an arrangement, strip-like transport electrodes are arranged in stripes on the insulating substrate. Note that an insulating layer (not shown) made of an insulating material is coated on the insulating substrate 101 and each transport electrode.

  In more detail about each conveyance electrode, they are classified into three types, A group, B group, and C group, and the electrodes belonging to the same group are in an electrically connected state. On the insulating substrate 101d, the order of the A transport electrode 101a belonging to the A group, the B transport electrode 101b belonging to the B group, and the C transport electrode 101c belonging to the C group is repeated from the left side to the right side in the drawing. In addition, each transport electrode is disposed. An A-phase drive bias, a B-phase drive bias, and a C-phase drive bias are applied from the drive power supply circuit 30 to each A transport electrode 101a, each B transport electrode 101b, and each C transport electrode 101c. In the figure, the toner is negatively charged, and is conveyed on the electrostatic conveyance substrate 101 from the right side to the left side in the drawing.

  FIG. 3 is a waveform diagram showing waveforms of the above-described A-phase drive bias, B-phase drive bias, and C-phase drive bias. In each phase, DC pulse waves having a voltage of −100 [V] and a duration of 501 [μsec] are output at intervals of 501 [μsec]. Here, when paying attention to the C-phase drive bias applied to the C transport electrode (101c), it is 0 [V] at time t0. At this time, the A transport electrode (101a) adjacent to the C transport electrode (101c) on the upstream side in the toner transport direction is also 0 [V] (see C-phase drive pulse). Further, a voltage of −100 [V] is applied to the B transport electrode (101a) adjacent on the downstream side in the toner transport direction (see B-phase drive bias). In such a state, the toner on the C transport electrode (101c) at the time point t0 hardly remains moving and remains there.

  Thereafter, when 334 [μsec] elapses and the time point t1 arrives, a voltage of −100 [V] is applied to the C transport electrode (101c). Then, an electrostatic force repelling the C transport electrode (101c) acts on the negative polarity toner existing on the C transport electrode (101c). At this time, a voltage of −100 [V] is also applied to the A transport electrode (101a) adjacent to the C transport electrode on the upstream side in the toner transport direction. On the other hand, the B transport electrode (101b) adjacent on the downstream side in the toner transport direction is 0 [V]. For this reason, the negative polarity toner present on the C transport electrode (101c) is electrostatically moved toward the B transport electrode (101b).

  Thereafter, when about 334 [μsec] elapses and the time point t2 arrives, a voltage of −100 [V] is applied to the B transport electrode (101b) which has been 0 [V] until then. Then, an electrostatic force repelling the B transport electrode (101b) acts on the toner that has come to exist on the B transport electrode (101b) due to electrostatic movement from the C transport electrode (101c). . At this time, a voltage of −100 [V] is also applied to the C transport electrode (101c) adjacent to the B transport electrode (101b) on the upstream side in the toner transport direction. On the other hand, the A transport electrode (101a) adjacent on the downstream side in the toner transport direction is 0 [V]. For this reason, the toner on the B transport electrode (101b) is electrostatically moved toward the A transport electrode (101a).

  After that, when about 334 [μsec] elapses and time t3 arrives, a voltage of −100 [V] is applied to the A transport electrode (101a) that has been 0 [V] until then. Then, an electrostatic force that repels the A transport electrode acts on the toner that has been present on the A transport electrode (101a) due to electrostatic movement from the B transport electrode (101b). At this time, a voltage of −100 [V] is also applied to the B transport electrode (101b) adjacent to the A transport electrode (101a) on the upstream side in the toner transport direction. On the other hand, the C carrying electrode (101c) adjacent on the downstream side in the toner carrying direction is 0 [V]. For this reason, the toner on the A transport electrode (101a) moves electrostatically toward the C transport electrode (101c).

  By repeating the electrostatic movement as described above, in FIG. 2 shown above, the electrostatic transport substrate 101 as the electrostatic transport means moves the toner from its right side to the left side in the figure with respect to its surface by electrostatic force. Transport relative to each other. Then, the electrostatic transfer substrate 101 and the photoconductor 11 are made to enter a developing region facing each other with a predetermined gap. In this developing area, the image portion 11a of the photoreceptor 11 is 0 [V], while the non-image portion 11b is −100 [V]. Then, the toner adheres to the image portion 11a of the photoconductor 11 and develops the electrostatic latent image in the process of electrostatically moving in the developing area from the right side to the left side in the drawing.

  It should be noted that the non-image portion 11b of the photosensitive member 11 serving as a latent image carrier has a larger potential on the charging polarity side of the toner than the potential average value of the drive bias applied to each transport electrode of the electrostatic transport substrate 101. There is a need. For example, the driving bias of each phase shown in FIG. 3 is a repetition of a potential of −100 [V] with a duration of 501 [μsec] and a potential of 0 [V] with a duration of 501 [μsec]. Therefore, the potential average value becomes −50 [V]. On the other hand, the potential of the non-image portion 11b of the photoconductor 11 in FIG. 2 is −100 [V] which is larger on the negative polarity side than −50 [V]. In such a potential relationship, toner existing between the electrostatic transport substrate 101 and the non-image portion 11b of the photoconductor 11 in the development region is electrostatically moved toward the electrostatic transport substrate 101 relatively. Adhesion to the non-image part 11b is prevented. However, if the potential of the non-image portion 11b is made smaller than the average value of the drive bias potential to the negative polarity side, the toner may be electrostatically moved toward the non-image portion 11b and attached. is there. Therefore, the potential of the non-image area 11b is set larger than the potential average value of the drive bias toward the charging polarity side of the toner.

  FIG. 4 is an enlarged configuration diagram showing the developing device 100 of the printer together with the photoreceptor 11. In FIG. 1, the developing device 100 includes a toner transport device including an electrostatic transport substrate 101, a toner replenishing unit 120, a toner supply unit 140 serving as a toner supply unit, and the like.

  5, 6 and 7 are a plane sectional view, a longitudinal sectional view and a transverse sectional view showing the toner supply unit 140, respectively. The toner supply unit 140 includes a storage chamber that is a mixture storage unit that stores a mixture of toner and a friction promoting substance (not shown). The storage chamber is divided into a first storage chamber 142 and a second storage chamber 143 by a partition wall 141. It is divided into two. In the first storage chamber 142, a first transfer screw 144 that is rotationally driven by a driving unit (not shown) is provided. In the second storage chamber 143, a second transfer screw 145 that is rotationally driven by a driving unit (not shown) is provided. The first transport screw 144 and the second transport screw 145 have a structure in which spiral protrusions 144b and 145b are projected from the surfaces of the rotating shafts 144a and 145a. The screw pitch is 120 [mm] and the thickness of the spiral protrusion is 1.5 [mm], respectively. The rotating shafts 144a and 145a are rotated so that the tips of the spiral protrusions 144b and 145b are moved at a peripheral speed of 60 [mm / sec]. In each screw, the surface of a base material made of a conductive material such as aluminum is coated with a polyimide resin layer which is an insulating material having a thickness of about 1 [μm].

  In the vicinity of both ends of the storage chamber, there is a communication space where the partition wall 141 is not provided over a length L2 (for example, 25 mm), and the two storage chambers (142, 143) communicate with each other. In FIG. 5, the first conveying screw 144 stirs and conveys the mixture contained in the first accommodation chamber 142 from the left side to the right side in the drawing as it is rotationally driven by a screw drive system (not shown). . Thus, the mixture conveyed to the communication space on the right side of the first storage chamber 142 in the drawing enters the second storage chamber 143. Then, it is conveyed from the right side in the drawing to the left side by the second conveyance screw 143 that is rotationally driven by the screw drive system, and passes through the communication space on the left side in the drawing of the second accommodation chamber 143, so that the first accommodation chamber 142. Return inside. In this manner, the mixture circulates counterclockwise in the drawing while being stirred and conveyed in the storage chamber. The second storage chamber 143 is provided with a toner concentration detection unit (not shown), detects the toner concentration of the mixture in the second storage chamber 143, and outputs a toner concentration signal to a control unit (not shown). This control unit drives and controls the toner replenishing unit (120 in FIG. 4) in accordance with the toner concentration signal, thereby replenishing the first storage chamber 142 with an appropriate amount of toner. Thereby, the toner concentration of the mixture in the storage chamber is maintained within a predetermined range. The toner newly replenished in the second storage chamber 143 is taken into the mixture, and then sent to the first storage chamber 142 while being rubbed against the friction promoting material along with the agitation transport.

  As shown in FIG. 6, a mesh 146 is provided at the bottom of the first storage chamber 142. In the first storage chamber 142, the mixture passes over the mesh 146 while being stirred and transported by the first transport screw 144. The mesh 146 has a metal plate-like member made of stainless steel having a thickness of 0.08 [mm], and a plurality of holes having a major axis of 0.2 [mm] and a minor axis of 0.15 [mm] are about 50 [%]. ] So as to have an aperture ratio of Each hole is provided in such a posture that its minor axis direction is along the screw axis direction. A predetermined gap is held between the tip of the spiral protrusion 144 b of the first transport screw 144 and the mesh 146. This gap is desirably set in a range of about 1/5 to 10 times the diameter of the toner. Desirably, when the carrier diameter is about 1/3 to 2 times the carrier diameter, the mixture replacement efficiency and the mixing and stirring efficiency are improved. In the printer of this embodiment, it is set to about 0.7 to 1.0 [mm]. It is desirable to provide a predetermined gap between the tip of the spiral protrusion 144b of the first transport screw 144 and the mesh 146.

  As shown in FIG. 7, a screw power supply circuit 190 is connected to a conductive base material made of aluminum or the like of the first transport screw 144. A mesh power supply circuit 191 is connected to the mesh 146. Each of these power supply circuits generates a negative polarity potential in the screw or mesh, and the output voltage is controlled by a main control unit (not shown). When toner is supplied from the toner supply unit 140 to the above-described electrostatic transfer substrate (101 in FIG. 4) (not shown), the first transfer screw 144 and the mesh 146 have the same polarity as that of the toner by the outputs from these power supply circuits. Of potential. Specifically, the first conveying screw 144 has a larger potential on the same polarity side (minus polarity side) as the toner than the mesh 146. Further, the mesh 146 has a larger potential on the same polarity side as the toner than the average voltage value of the drive bias applied to each transport electrode of the electrostatic transport substrate (101) (not shown).

The average voltage value of the drive bias is an integrated value of the drive bias waveform per unit time. For example, in the case of a square wave with a peak-to-peak of 0 to −100 [V] and a duty of 50 [%], the average voltage value of the driving tooth chair is −50 [V]. When the duty is higher than 50 [%], that is, when the appearance time of −100 [V] is longer than the appearance time of 0 [V], the average voltage value becomes larger than −50 [V] on the negative side. . Further, when the duty becomes lower than 50 [%], that is, when the appearance time of −100 [V] becomes shorter than the appearance time of 0 [V], the average voltage value becomes smaller than −50 [V]. . According to the experiments by the present inventors, the mesh 146 has −0.05 to −3.5 [kV], preferably −0.2 to −2.5 [kV] under the following conditions. It was effective to apply a mesh voltage.
A gap between the tip of the spiral protrusion 144b of the first transport screw 144: 1 [mm]
・ Average voltage of drive bias: -50 [V]
-Potential of the first conveying screw 144: grounding

  When a positively chargeable toner is used, for example, if the average potential value of the drive bias is −50 [V], a mesh voltage having a larger value on the plus side than −50 [V] is applied to the mesh 146. That's fine. More specifically, the mesh voltage is 0 to −49 [V].

  FIG. 8 shows that the first transport screw 144 has a larger potential on the negative polarity side than the mesh 146 and the mesh 146 has a larger potential on the negative polarity side than the average voltage value of the drive bias. Such an electric field is formed. In the figure, an electric line of force extending from the tip of the screw spiral projection 144b of the screw toward the inside of the hole 146a of the mesh 146 is formed between the first conveying screw (144) and the mesh 146. In addition, electric lines of force extending from the vicinity of the exit of the hole 146a toward the substrate are formed between the mesh 146 and the electrostatic transfer substrate (101) (not shown). The toner in the mixture that is agitated and conveyed by the first conveying screw (144) is first removed from the surface of the frictionally charged particles and electrostatically moved into the hole 146 under the influence of the former lines of electric force. Next, after passing through the hole 146 under the influence of the latter lines of electric force, it is electrostatically moved toward the electrostatic transfer substrate (101). By such electrostatic movement, the toner in the mixture stirred and conveyed in the first storage chamber 142 shown in FIG. 7 is separated from the frictionally charged substance and supplied to the electrostatic conveyance substrate (101). The toner after passing through the mesh 146 is relatively moved in the toner transport direction on the substrate while being relatively electrostatically moved toward the transport electrodes on the substrate having an average voltage value smaller than the potential of the mesh 146. Electrostatic movement.

  Regarding the potential difference between the tip of the spiral protrusion 144b of the first conveying screw 144 and the mesh 146, the electric field strength between them is the same polarity as the toner and the absolute value is in the range of 0.3 to 3.5 [kV / mm]. It is desirable to set it to stay. The average value of drive pulses for each transport electrode is −50 [V]. This is because, when the electric field strength is greater than 3.5 [kV / mm], the electric lines of force extending from the spiral protrusion 144b are concentrated on the edge of the hole 146a, and the discharge from the screw to the mesh is likely to occur. On the other hand, when it becomes smaller than 0.3 [kV / mm], an electrostatic force larger than the adhesion force (image force or van der Waals force) is applied to the toner adhering to the surface of the friction promoting particles. Because it becomes impossible. When the distance between the tip of the spiral protrusion 144b and the mesh 146 is 1 [mm], the electric field strength can be kept within the above range by setting the potential difference between the two to an absolute value of 0.3 to 3.5 [kV]. be able to. A more desirable range of the electric field strength is 0.8 to 3.0 [kV] in absolute value.

  According to the experiments by the present inventors, it is preferable when the gap between the spiral protrusion 144b and the mesh 146 is 1 [mm], and the mesh 146 is grounded and a voltage is applied only to the first conveying screw 144. The screw voltage values were as follows. That is, it was -0.3 to -3.5 [kV]. Further, a more preferable screw voltage value was -0.8 to -3.0 [kV].

  Further, according to the experiments by the present inventors, when the gap is 1 [mm] and the first conveying screw 144 is grounded and a voltage is applied only to the mesh 146, the preferred mesh voltage is as follows. It was as follows. That is, it was -0.05 to -3.5 [kV]. Further, a more preferable mesh voltage value was −0.2 to −2.5 [kV].

  Further, according to the experiments by the inventors, when both the screw voltage and the mesh voltage were applied, the preferable total value of both voltages was -0.35 to 7.0 [kV]. Further, a more preferable total value was -1.0 to -5.5 [kV].

  As shown in FIG. 7, no mesh is provided at the bottom of the second storage chamber 143. Therefore, only the toner in the first storage chamber 142 out of the two storage chambers is supplied to the electrostatic transfer substrate 101.

  In FIG. 8 shown above, the electric field formed between the spiral projection 144b and the mesh 146 is E1, and the electric field formed between the mesh 146 and the electrostatic transfer substrate (101) (not shown) is E2. In this case, the relationship “E1> E2” is established. In such a relationship, as shown in FIG. 8, the electric lines of force extending from the spiral protrusion 144 b enter deep inside the hole of the mesh 146, and from the vicinity of the exit of the hole of the mesh 146 toward the electrostatic transfer substrate (not shown). The electric lines of force extend. Then, after the toner that has separated from the surface of the friction promoting particles by the electric field E1 and flew toward the mesh 146 enters the hole along the electric field line of the electric field E1, this time, the toner is electrostatically conveyed from the vicinity of the hole outlet. It goes out of the hole along the electric lines of force toward the substrate. Therefore, the toner can be efficiently separated from the friction promoting particles in the first storage chamber (142) and supplied to the electrostatic transfer substrate. On the other hand, when the electric field E1 <the electric field E2, the electric lines of force extending from the electrostatic conveyance substrate toward the mesh 146 enter the periphery of the hole entrance from the hole exit for the negative polarity toner. In this case, the toner that has separated from the frictionally charged particles and flew toward the mesh 146 cannot enter the hole, and as a result, cannot be separated from the mixture. Note that E1 and E2 have the same polarity.

  The average particle diameter (diameter) of the toner used in this printer is in the range of r = 3 to 9 [μm]. Further, the shortest diameter (diameter) of the mesh 146 used in the printer is in the range of 6r to 1 / 2R. This R is the average particle diameter (diameter) of the friction promoting particles. Specifically, the shortest diameter of the holes of the mesh 146 is about 18 to 150 [μm]. The mesh 146 has a thickness of 20 to 150 [μm]. In order for the mesh 146 to exhibit a certain degree of rigidity, the thickness is desirably 50 [μm] or more.

As specific conditions for various voltages to satisfy E1> E2, when the gap between the tip of the spiral protrusion 144b and the mesh 146 and the gap between the mesh 146 and the electrostatic transfer substrate are both 1 [mm], for example, become.
-Potential difference between the spiral protrusion 144b and the mesh 146: -1.1 to -3.5 [kV]
-Potential difference between mesh 146 and electrostatic transfer substrate (average voltage of drive bias): -0.05 to -1.0 [kV]

  In the toner supply unit 140 having such a configuration, the first storage chamber 142 and the second storage chamber 143 serve as a mixture storage unit that stores a mixture in which a frictionally charged substance that promotes frictional charging of toner is mixed. It is functioning. Moreover, the 1st conveyance screw 144 is functioning as a counter electrode which opposes the mesh 146 via a mixture in a 1st storage chamber.

  In FIG. 4 described above, the toner that has passed through the mesh 146 and is supplied to the right end portion of the electrostatic conveyance substrate 101 in the drawing is conveyed from the right side to the left side in the drawing while hopping due to the EH phenomenon. A part of the development area facing the photoconductor 11 contributes to the development of the electrostatic latent image. The remaining toner that did not contribute to the development is collected by a collection screw 102 disposed on the left side of the development region in the drawing. Then, the toner is returned to the toner supply unit 140 through a collection path (not shown) in which a rotating member such as an auger is provided. Thereby, the toner that has not contributed to the development is recycled.

  The toner supply unit 120 is detachably connected to the second storage chamber 143 of the toner supply unit 140. The toner supply unit 120 includes a storage unit 121 that stores toner for supply and a supply hopper 125 for supplying toner to the second storage chamber 143. The storage unit 121 is provided with an agitator 122 that is driven to rotate counterclockwise in the drawing by driving means (not shown), and the toner in the storage unit 121 is sent toward the replenishment unit 125 by this rotation. . The supply hopper 125 has a tapered structure with a taper, and has a supply roller 126 at the bottom. Then, the toner sent from the storage unit 121 is supplied into the second storage chamber 143 by the rotation of the supply roller 126 while being dropped toward the supply roller 126 by the taper structure.

  As described above, in the printer, the toner supply unit 140 includes the storage chambers (142, 143) that are the mixture storage unit that stores the mixture of the toner and the friction promoting substance. Moreover, it has the conveyance screw (144,145) which is a stirring member which stirs the mixture inside. Furthermore, it also has a mesh 146 provided in the first storage chamber 142. Then, the toner is rubbed with the friction promoting substance in the storage chamber and is siftered by the mesh 146 and supplied to the electrostatic transfer substrate 101 while more reliably triboelectrically charging. In such a configuration, it is possible to suppress toner conveyance failure caused by supplying toner, which is poorly charged due to insufficient friction, onto the electrostatic conveyance substrate 101.

  The mesh 146 made of a metal material can be easily manufactured by etching a metal film (plate) or electrohoming (electroforming). As a material for the mesh 146, it is desirable to use a material that exhibits flexibility and wear durability. Moreover, the shape of the hole of the mesh 146 can employ a round shape, an oval shape, a square shape, a rectangular shape, a star shape, an irregular shape, or the like.

  In this printer, the mesh hole is elliptical, the length of the hole in the longitudinal direction is the length L of the hole, and the size of the hole in the short direction is the width W of the hole. The thickness T of the mesh 146 is desirably set in the range of 20 to 150 [μm], preferably 30 to 80 [μm]. At this time, it is preferable that the relationship between the thickness T, the length L, and the width W is in a range of 500 W ≧ L and W / 5 ≦ T ≦ 3W. This is because when the length L of the hole and the width W are 500 W ≧ L, the mesh 146 has both a certain degree of rigidity and a certain degree of high aperture ratio. Further, when the relationship between the width W and the thickness T is W / 5 ≦ T ≦ 3W, it is possible to ensure flatness and curvature processing as a metal film. Thereby, the bobbin shape, the straightness of the flat plate, the contact deformation, and the shape recovery due to the rigidity of the mesh 146 can be functioned.

  The opening ratio of the mesh 146 is preferably in the range of 20 to 70 [%]. This is because, when an image to be developed is solid black, it has been confirmed by experiments that it must be within such a range in order to ensure the discharge amount without unevenness. The pores of the mesh 146 need to be larger than the average particle diameter r of the toner and smaller than the average particle diameter R of the friction promoting particles P. Further, the relationship between the toner and the friction promoting particles P is preferably 6r ≧ W and 2W ≦ R. By setting 6r ≧ W with respect to the average particle diameter r of the toner, clogging of the mesh due to the cloud-like toner is less likely to occur, and the toner can be easily supplied through the holes of the mesh. Further, by setting 2W ≦ R with respect to the average particle R of the friction promoting particles P, the particle size distribution of the friction promoting particles P, and when the friction promoting particles P are worn and reduced in size by continuous use, A margin is provided so that the mesh 146 does not pass through the holes.

  The holes of the mesh 146 may be tapered from the entrance side into which the toner enters to the exit side. With this structure, it is possible to reliably extend the lines of electric force from the metal material portion of the inner wall of the hole toward the electrostatic transfer substrate 101 on the outlet side. As a result, the toner can be easily removed from the hole.

As for the mesh 146, the surface of the base made of a metal material may be covered with an insulating protective film. In this case, the protective film is a thin film having a thickness of 0.5 to 30 [μm] so as not to cause deterioration of the electric field strength, and a material such as SiO ₂ , SiN, Ta ₂ O ₅ , or polyimide is used. In the mesh 146 having such a configuration, the surface that comes into contact with the charged toner is entirely covered with an insulating protective film, so that charge injection from the substrate to the toner can be prevented and the charge amount can be kept appropriate. . Further, since the substrate and the mixture do not come into contact with each other, the deterioration of the mixture, particularly the toner, can be reduced as compared with the case where the substrate comes into contact with the metal part.

  As for the mesh 146, a metal layer made of a metal material may be coated on the outer surface of a base made of an organic resin material by vapor deposition or electroforming. In this case, it is desirable to use a material having a relatively high toner charging capability as the organic resin material used for the substrate. The metal layer is a thin film having a thickness of 0.5 to 5 [μm], and the toner in the hole passes through the hole along electric lines of force extending from the thin film toward the electrostatic transfer substrate 101. In the mesh 146 having such a configuration, since the base is an organic resin material, it exhibits excellent flexibility and elasticity, and also exhibits shape restoring properties. And even when force is applied from the outside, the shape can be kept stable. In addition, frictional charging of the toner can be promoted by contacting the toner in the hole.

  Moreover, about the mesh 146, it is good also as what bonded the protective layer which consists of an organic resin agent amount to the screw opposing surface side in the base material which consists of metal materials. In this case, it is desirable to use an organic resin material having a relatively high toner charging capability. As for the bonding method of both materials, a method using heat bonding or a method using hot pressing can be used. The mesh 146 using an organic resin material can exhibit good flexibility, elasticity, and shape restoration.

  Further, the mesh 146 may have a tapered shape that spreads from the entrance side where the toner enters toward the exit side. You may form in a shape which has an inclination toward an outer surface and a hole diameter spreads. By forming the slope extending toward the outlet side on the inner wall of the hole, toner adhesion to the inner wall can be suppressed.

Next, a characteristic configuration of the printer will be described.
When the development operation is completed and the application of the drive pulse voltage to each transport electrode of the electrostatic transport substrate 101 is stopped, the toner that has moved toward the development area while hopping on the substrate surface until then hops. Stop and adhere to the substrate surface. In addition, when hopping is performed during the developing operation, the adhesion and separation from the substrate surface are repeated. When the toner adheres to the substrate surface in this way, an adhesion force due to Coulomb force, van der Waals force, mirror image force, gravity, or the like is generated between the toner and the substrate. As the surface material of the electrostatic transfer substrate 101, one having a volume resistivity of 10 ⁹ to 10 ¹³ [Ω · cm] is used in order to suppress the Coulomb force as much as possible. The drive pulse voltage to each transport electrode is set to a value large enough to overcome the Coulomb force and the like so that the toner can be separated from the substrate surface. However, in a humid environment, the adhesive force increases due to the liquid crosslinking phenomenon that occurs between the substrate containing moisture on the surface and the toner particles, making it difficult to remove the toner from the substrate surface. In some cases, toner conveyance due to the EH phenomenon may not be performed well.

Therefore, this printer is provided with a substrate heating means for heating the electrostatic transport substrate 101 of the developing device 100. The substrate heating means includes a heat source provided in the developing apparatus 100, a heating power supply circuit for supplying power to the heat source, and the like. The heat source, those formed integrally with the electrostatic transporting substrate 101, etc. be the name of which is fixed to the electrostatic transporting substrate 101 can be used.

  This printer includes an in-machine temperature sensor (not shown) that detects the temperature in the enclosure and outputs a detection signal to the control unit, and an in-machine humidity sensor (not shown) that detects the humidity in the enclosure and outputs the detection signal to the control unit. I have. Also provided is a substrate surface temperature sensor (not shown) that detects the surface temperature of the electrostatic transfer substrate 101 and outputs a detection signal to the control unit. Based on the signals from these sensors, the controller turns on / off the power output from the heating power supply circuit to control heating by the substrate heating means.

  In this printer having such a configuration, the electrostatic transfer substrate 101 is heated to promote the evaporation of moisture from the surface (front surface) thereof, thereby liquid bridge between the substrate surface and the toner particles in a humid environment. Suppress the phenomenon. As a result, the situation in which the toner hopping due to the EH phenomenon is hindered by moisture is suppressed.

  The water adhering to the surface of the electrostatic transfer substrate 101 due to the high humidity environment can be evaporated by heating the substrate surface to 40 to 60 [° C.]. The moisture absorbed by the substrate surface material due to the high humidity environment depends on the surface structure such as whether or not the substrate is porous, but can be removed from the surface material by heating to about 80 [° C.]. is there. Further, the moisture bonded to the surface material can be separated from the surface material by heating to about 120 [° C.] although it depends on the functional group of the material. Furthermore, crystal water such as a silicon oxide film can be separated by heating to about 180 [° C.].

  The electrostatic transfer substrate 101 may be heated by a method of heating for a relatively long time or a method of heating temporarily. In heating by blowing hot air, a method of temporarily heating from the back side of the substrate during the non-development operation is desirable so that the toner is not scattered. Further, in the method of generating heat from a heat source that is brought into contact with the electrostatic transfer substrate 101 or formed integrally, either continuous heating or temporary heating may be used. According to the experiments by the present inventors, in continuous heating, if the surface of the electrostatic transport substrate 101 is made 5 [° C.] or more higher than the in-machine temperature, good staticity can be achieved without hindering toner hopping even in a humid environment. Electric transport could be performed. Further, in the temporary heating, if the surface of the electrostatic transport substrate 101 is made 10 [° C.] or more higher than the in-machine temperature, good electrostatic transport can be performed without hindering toner hopping even in a humid environment. did it.

Figure 9 is a partial cross-sectional view showing an electrostatic transporting substrate 101 of the developing device of the printer according to the present embodiment. In the figure, an electrostatic transfer substrate 101 has the following components in addition to an insulating substrate 101d made of glass or the like, and transfer electrodes (101a, b, c) made of a conductive material such as aluminum. ing. The heat generation layer 101e, the intermediate layer 101f, the surface layer 101g, and the like, which are heat sources. These are all coated on the front surface side of the insulating substrate 101.

  The heat generating layer 101e serves as a heat generating part of a heating means for heating the electrostatic transport substrate 101, and a conductive material such as nickel chrome (NiCr) is electrostatically transported with a thickness of about 0.3 to 1 [μm]. The front surface of the substrate 101 is covered. A power supply circuit (not shown) is connected to the heat generating layer 101e via a lead wire (not shown).

  The intermediate layer 101f is a layer in which a heat-resistant insulating material is coated on the heat generating layer 101e with a thickness of 0.5 to 2 [μm], and includes the conductive heat generating layer and each conductive transport electrode. It plays the role of insulation. On the intermediate layer 101f, the respective transport electrodes and bus lines connected to these are formed.

  The surface layer 101g is a layer of about 0.5 to 2 [μm] coated on each of the transport electrodes 101a, b, c and the intermediate layer 101f region where these transport electrodes do not exist. Here, in the same figure, each of the transport electrodes 101a, b, c and the intermediate layer 101f functions as a second layer located immediately below the surface layer 101g. Even if each of the transport electrodes 101a, b, c and the intermediate layer 101f as the second layer is left exposed without providing the surface layer 101g, the electrostatic transport substrate 101 can exhibit a toner transport function. . However, if each of the transport electrodes 101101a, b, c and the intermediate layer 101f is made of a material having a relatively good hydrophilic property, even if the moisture on the substrate surface is removed, the moisture on the surface of the toner particles is improved. May hinder proper hopping. Therefore, in this printer, the surface layer 101f made of a material having better water repellency is coated on each of the transport electrodes 101101a, b, c and the intermediate layer 101f.

  In such a configuration, superior water repellency is exerted on the substrate surface as compared with the case where each of the transport electrodes 101a, b, c and the intermediate layer 101f is left exposed. As a result, the liquid cross-linking phenomenon between the toner and the substrate caused by the moisture on the surface of the toner particles can be suppressed, and the situation where the hopping of the toner due to the EH phenomenon is hindered by moisture can be more reliably suppressed. .

The material of the surface layer 101f is not particularly limited as long as it exhibits water repellency superior to that of the second layer. However, from the viewpoint of suppressing the above-mentioned Coulomb force as much as possible, it is desirable to use a material that exhibits a volume resistivity in the range of 10 ⁹ to 10 ¹³ [Ω · cm] after film formation. If the volume resistivity exceeds 10 ¹³ [Ω · cm], charges may be accumulated in the surface layer 101f, which may adversely affect the electrostatic transportability of the toner. Further, from the viewpoint of exhibiting as excellent water repellency as possible, the critical surface tension after film formation is 40 [mN / m] or less (30 mN / m or less), and the contact angle with water is 80 [°] or more ( It is desirable to use those preferably 100 ° or more. As an example of a material capable of setting the critical surface tension after film formation to 30 [mN / m] or less and the contact angle with water to 100 [°] or more, a fluororesin can be given. More specifically, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluorovinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (ethylene-fluoroethylene copolymer). , PVDF (polyvinylidene fluoride), PVF (polyvinyl fluoride), ECTFE (chlorotrifluoroethylene-ethylene copolymer) and the like. Further, an amorphous fluororesin (trade name Lumiflon, Viton, Florel, Cytop, Kalrez, etc.) containing fluorine in the side chain or main chain of the chemical structure may be used. When such an amorphous fluororesin is used, it may be formed by a sputtering film forming method or a thin film coating method.

In addition, since fluororesin has a very high resistance, when it is used as a surface material, it is desirable that the thickness of the surface layer 101g be about 0.05 to 0.3 [μm]. By doing so, a layer having a volume resistivity of 10 ¹³ [Ω · cm] or less can be obtained.

  As shown in FIG. 9, in this printer, as the substrate heating means for heating the electrostatic transport substrate 101, a heating layer 101 e serving as a heat generating portion is directly fixed to the electrostatic transport substrate 101. In such a configuration, since the surface (surface layer 101g) of the electrostatic transport substrate 101 is heated by heat conduction by contact, energy saving can be achieved as compared with the case of heating by radiation. During heating, a voltage is applied to the heat generation layer 101e located below each of the transfer substrates 101a, b, and c. When the electric field on the electrostatic transfer substrate 101 is greatly disturbed by the application of this voltage, it is desirable to heat during non-development operation so as not to disturb toner hopping during development.

  In this printer, a heating layer 101e, which is a heating part of the substrate heating means, is fixed between an insulating substrate 101d, which is a base material, and a surface layer 101g. In such a configuration, it is possible to conduct heat from the heat generating layer 101e to the surface layer 101g without passing through the insulating substrate 101d having the largest thickness among the electrostatic transfer substrates 101. Therefore, energy saving can be achieved as compared with the case where the heat generating layer 101e is fixed to the back surface side of the insulating substrate 101d and the surface layer 101g is heated by heat conduction therethrough.

FIG. 10 is a partial cross-sectional view showing the electrostatic transport substrate 101 in a modified apparatus of the printer. The electrostatic transfer substrate 101 of this modified apparatus is not provided with the heating layer (101e) shown in FIG. The transport electrodes 101a, b, and c are directly laminated on the insulating substrate 101d, and an electrode protective layer 101j and a surface layer 101g, which are intermediate layers, are sequentially laminated thereon. Each of the transport electrodes 101a, b, and c is made of a material such as aluminum or nickel chrome, and has a thickness of about 0.1 to 0.3 [μm]. The electrode protective layer 101j is made of a material such as SiO ₂ or SiON, and the thickness of the portion covering each transport electrode is about 0.5 to 2 [μm]. The surface layer 101g is made of the above-described fluororesin and has a thickness of about 0.05 to 0.3 [μm].

  FIG. 11 is a partial plan view showing the electrostatic transfer substrate 101 of the modified apparatus. In this figure, illustration of the surface layer and the electrode protective layer is omitted for convenience. In the figure, arrows y and x indicate the toner transport direction in the substrate surface direction and the transport orthogonal direction perpendicular thereto. Each of the transport electrodes 101a, b, and c is arranged so as to be aligned in the toner transport direction y while extending in the transport orthogonal direction x. Near both ends of the electrostatic conveyance substrate 101 in the conveyance orthogonal direction x, a group A bus line pair 101A, a group B bus line pair 101B, and a group C bus line pair 101C are formed so as to extend in the toner conveyance direction y. ing. Then, they are connected to the A transport electrode 101a, the B transport electrode 101b, and the C transport electrode 101c, respectively. During the developing operation (during toner conveyance), a driving power supply circuit (not shown) and a heating power supply circuit of the substrate heating unit are connected to each of the bus line pairs (101A to 101C). During the developing operation (during toner conveyance), the drive power supply circuit applies a drive pulse voltage of the same value to the right electrode in the figure and the left electrode in the figure among the two electrodes of each bus line pair. Is output. On the other hand, during the non-development operation, a heating DC voltage is output to each bus line pair by the heating power supply circuit of the substrate heating means. At this time, a potential difference is generated between the right electrode in the drawing and the left electrode in the drawing in each bus line pair. Then, a current is generated in each bus line pair and each transport electrode connected thereto, and each bus line pair and each transport electrode generate heat. The heat generation heats the surface layer (101 g). That is, in this modified apparatus, each bus line pair as a mother ship electrode and each transport electrode are also used as a heat generating portion of the substrate heating means. In such a configuration, it is possible to heat the surface layer (101g) by generating heat in each bus line and the transport electrode while avoiding an increase in cost due to the provision of the heating unit dedicated to heating in the electrostatic transport substrate 101.

Next, a printer according to an example in which a more characteristic configuration is added to the printer according to the embodiment will be described.
Figure 12 is a partial cross-sectional view showing an electrostatic transporting substrate 101 of the printer according to the present embodiment. In the figure, an electrostatic transfer substrate 101 is formed by directly covering each transfer electrode 101a, b, c on an insulating substrate 101d made of glass or the like, and having a volume resistivity of 10 ⁹ to 10. A surface layer 101 g of ¹³ [Ω · cm] is coated. Further, the back surface of the insulating substrate 101d is coated with a heat generating layer 101e made of NiCr or the like having a thickness of 0.3 to 5 [μm] (preferably 0.3 to 1 μm), and on top of that, the heat insulating property is excellent. A heat insulating layer 101h made of a material is covered.

As the material for the surface layer 101g, any one of resin, inorganic nitrogen compound, and inorganic carbon compound is used. In general, resins, inorganic nitrogen compounds, and inorganic carbon compounds are excellent in hydrophobicity. Examples of the resin having such properties include polyethylene resin, parylene resin, silicon resin, polyimide resin (Kapton, Aramid, Upilex) in addition to the above-described fluororesin. Examples of inorganic nitrogen compounds include silicon nitride (Si ₃ N ₄ ) and boron nitride (BN). Moreover, SiC etc. are mentioned as an inorganic carbon compound.

Polyimide resin, silicon resin, and parylene resin are also very high-resistance materials, but by reducing the thickness to 0.05 to 0.3 [μm], the surface layer 101 g having a volume resistivity of 10 ¹³ [μm] or less. Can be formed. Silicon nitride (Si ₃ N ₄ ) and boron nitride (BN) are very high resistance materials. However, the volume resistivity of the surface layer 101g having a thickness of about 0.1 to 2 [μm] made of these can be set to 10 ⁹ to 10 ¹³ [Ω · cm] by the following. That is, by adjusting the ratio of the introduced gas during film formation, the degree of vacuum, the substrate temperature, the plasma temperature, etc., free electrons are present in the composition.

  In the printer having such a configuration, the surface layer 101g can exhibit the following properties by using any of resin, inorganic nitrogen compound, and inorganic carbon compound as the material of the surface layer 101g. That is, the critical surface tension (γc) is 50 [mN / m] or less and the contact angle with water is 60 to 115 [°]. The surface layer 101g can exhibit excellent water repellency. Therefore, the liquid cross-linking phenomenon between the toner and the substrate due to the moisture on the surface of the toner particles can be suppressed, and the situation where the toner hopping due to the EH phenomenon is hindered by moisture can be more reliably suppressed.

  In this printer as well, as the substrate heating means for heating the electrostatic transport substrate 101, the surface of the electrostatic transport substrate 101 (surface) is used by using a heating layer 101e that is a heat generating portion directly fixed to the electrostatic transport substrate 101. The layer 101g) is heated by heat conduction by contact. Therefore, energy saving can be achieved compared to the case of heating by radiation.

  In this printer, the heat generating layer 101e is not fixed to the front surface side of the insulating substrate 101d, but is fixed to the back surface side of the insulating substrate 101d as a base material. In such a configuration, even if the heat generating layer 101e is not a film-like one that covers the entire surface of the substrate, but has a complicatedly meandering linear pattern, the surface layer 101g is oriented in the plane direction for the reason described below. It can be heated evenly. That is, the heat of the heat generating layer 101e is conducted to the surface layer 101g while diffusing in the surface direction through the thickest insulating substrate 101d.

13, an electrostatic transport substrate 101 in the modification unit of the printer according to the present real施例is an enlarged configuration view illustrating with heating portion of the substrate heating unit. In the figure, a heating unit 150 of the substrate heating means has a flat shape having substantially the same area as the electrostatic transfer substrate 101, and has a heat source such as a coil and a halogen lamp (not shown) inside. . The heating unit 150 is fixed to the back surface of the electrostatic transfer substrate 101 with a heat resistant adhesive 151.

Next, a printer according to a reference embodiment will be described. The basic configuration of a printer according to this preferred embodiment is similar to the printer according to the implementation mode, it will be described only the differences from the same printer.

Figure 14 is a schematic configuration diagram showing a printer according to this preferred embodiment. This printer includes an air intake device 200 as air heating means or air dehumidifying means that sucks air outside the housing and discharges it into the housing while heating or dehumidifying it. By this air intake device 200, heated or dehumidified air is sent into the housing to promote evaporation of moisture from the surface of the electrostatic transfer substrate (101) and toner. As a result, it is possible to suppress a situation in which toner hopping due to the EH phenomenon is hindered by moisture.

  So far, a printer that has a single developing device and forms a single color image has been described. However, the present invention can also be applied to an image forming device that forms a multicolor image by a plurality of developing devices. Further, the example in which the plate-shaped electrostatic transport substrate 101 is used as the electrostatic transport member has been described, but the present invention can also be applied to an image forming apparatus using a belt-shaped member or a drum-shaped member. is there.

As described above, in the printer of the embodiment , as the electrostatic transfer substrate 101 serving as the electrostatic transfer means, the surface layer 101g is lower than the intermediate layer 101f, which is the second lower layer, and the transfer electrodes 101a, b, c. A material that exhibits excellent water repellency is used. In such a configuration, for the reasons described above, compared to the case where the respective transport electrodes 101a, b, c and the intermediate layer 101f are left exposed or a surface layer having a lower water repellency than the second layer is formed. By suppressing the liquid cross-linking phenomenon between the toner and the substrate surface due to moisture on the surface of the toner particles, it is possible to more reliably suppress the situation where the toner hopping due to the EH phenomenon is hindered by moisture.

In the printer of the embodiment, as the electrostatic transport substrate 101, the surface layer 101g is made of any of resin, inorganic nitrogen compound, and inorganic carbon compound. In such a configuration, for the reasons described above, the excellent water repellency of the surface layer 101g suppresses the liquid crosslinking phenomenon between the toner and the substrate surface due to moisture on the surface of the toner particles, and hinders toner hopping due to the EH phenomenon due to moisture. Such a situation can be suppressed more reliably.

In the printers of the embodiments and examples , as the substrate heating unit, a heating unit whose heat generating portion is directly fixed to the electrostatic transfer substrate 101 is used. In such a configuration, since the surface (surface layer 101g) of the electrostatic transport substrate 101 is heated by heat conduction by contact, energy saving can be achieved as compared with the case of heating by radiation.

In the printer of the embodiment , the electrostatic transport substrate 101 is a substrate in which the heat generating portion of the substrate heating means is fixed between the insulating substrate 101d as a base material and the surface layer 101g. In such a configuration, energy saving can be achieved as compared with the case where the heat generating portion is fixed to the back surface side of the insulating substrate 101d and the surface layer 101g is heated by heat conduction therethrough.

In the printer of the embodiment , as the electrostatic transport substrate 101, a plurality of transport electrodes 101a, 101b, and 101c arranged in the toner transport direction y while extending in the transport orthogonal direction x, and these A, B, and C are connected to a pair of bus electrodes connected to both ends of the conveyance orthogonal direction x with respect to the combination so as to conduct in common to a predetermined combination (A group, B group, and C group) of the conveyance electrodes. A line pair 101A, B, and C is used. In addition, a heating power supply circuit is provided as a potential difference generating means for generating a potential difference between two electrodes in each bus line pair. Then, each transport electrode or bus line pair is caused to generate heat by the potential difference to function as a heating portion of the substrate heating means. In such a configuration, it is possible to heat the surface layer (101g) by generating heat in each bus line and the transport electrode while avoiding an increase in cost due to the provision of the heating unit dedicated to heating in the electrostatic transport substrate 101.

Further, in the printer of the embodiment, as the substrate heating means, a heating part in which the heat generating part is fixed to the back surface of the insulating substrate 101d is used. In such a configuration, for the reason described above, the surface layer 101g can be evenly heated in the plane direction even if a linear pattern that meanders in a complicated manner along the substrate surface is used as the heat generating portion.

Schematic diagram showing a printer according to the implementation embodiments. FIG. 2 is an enlarged configuration diagram illustrating a photoconductor of the printer and an electrostatic transfer substrate of a developing device. FIG. 4 is a waveform diagram showing waveforms of an A-phase driving bias, a B-phase driving bias, and a C-phase driving bias that are applied to a transport electrode of an electrostatic transport substrate of a printer. FIG. 2 is an enlarged configuration diagram showing the developing device together with the photoconductor. FIG. 3 is a plan sectional view showing a toner supply unit of the developing device. FIG. 3 is a longitudinal sectional view showing the toner supply unit. FIG. 3 is a cross-sectional view showing the toner supply unit. FIG. 6 is a schematic diagram illustrating an electric field formed between a first conveying screw and a mesh of the toner supply unit. FIG. 3 is a partial cross-sectional view illustrating an electrostatic transport substrate of the developing device of the printer according to the embodiment . The fragmentary sectional view which shows the electrostatic conveyance board | substrate in the modified example apparatus of the printer. The fragmentary top view which shows the electrostatic conveyance board | substrate of the modification apparatus. Partial cross-sectional view showing an electrostatic transporting substrate of the printer according to the embodiment. The enlarged block diagram which shows the electrostatic conveyance board | substrate in the modified example apparatus of the printer with the heating part of a board | substrate heating means. 1 is a schematic configuration diagram showing a printer according to a reference form.

Explanation of symbols

11 Photoconductor (latent image carrier)
100 Developing Device 101 Electrostatic Transport Substrate (Electrostatic Transport Unit)
101a A transport electrode 101b B transport electrode 101c C transport electrode 101d Surface layer 101e Heat generation layer (heat generation section)
101f Intermediate layer (second layer)
101A A bus line pair (bus electrode pair)
101B B bus line pair (bus electrode pair)
101C C bus line pair (bus electrode pair)
150 Heating unit 200 Air intake device (air heating means, air dehumidifying means)
y Toner transport direction x Transport orthogonal direction

Claims (6)

In a toner conveying apparatus having electrostatic conveying means for conveying toner on a surface by moving relative to the surface by electrostatic force,
As the electrostatic transfer means, using a substrate and a surface layer laminated on the substrate directly or via an intermediate layer,
A toner conveying device comprising a heating means for heating the surface layer by a heat generating layer fixed between the substrate and the surface layer . The toner conveying device according to claim 1.
As the electrostatic transfer means, the toner conveying device, characterized in that said surface layer with which exhibits excellent water repellency than the second layer lower than that. The toner conveying device according to claim 1.
As the electrostatic transfer means, the surface layer resin, an inorganic nitrogen compound, a toner conveying device characterized by using one made of any of inorganic carbon compounds. In the toner conveying device according to claim 1, 2, or 3 ,
As the electrostatic transport means, a plurality of transports arranged so as to be aligned in the toner transport direction while extending in the transport orthogonal direction out of the toner transport direction in the surface direction and the transport orthogonal direction orthogonal thereto. In this bus electrode pair, the electrode has a pair of bus electrodes connected to both ends of the transport orthogonal direction with respect to the combination so as to conduct in common to a predetermined combination of the transport electrodes. A toner conveying apparatus, comprising: a potential difference generating means for generating a potential difference between the electrodes, wherein the combination and the bus electrode pair are heated by the potential difference to function as a heat generating portion of the heating means . The toner present on the surface of the electrostatic transport means provided in the toner transport means is transported to a position facing the latent image carrier while being moved relative to the surface by electrostatic force, and the latent image carrier In the developing device for developing the carried latent image,
As the conveying means, a developing device which is characterized by using any of the toner conveying device according to claim 1 to 4. In an image forming apparatus comprising: a latent image carrier that carries a latent image; and a developing unit that develops the latent image on the latent image carrier into a toner image.
An image forming apparatus using the developing device according to claim 5 as the developing means .

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