JP4216040B2 - Developing apparatus and electrophotographic apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device and an electrophotographic apparatus used in electrophotographic apparatuses such as copying machines, printers, and facsimiles.
[0002]
[Prior art]
In general, in an electrophotographic apparatus (image forming apparatus) such as a copying machine, a printer, and a facsimile, toner is supplied by a developing device to a photosensitive member that carries and conveys an electrostatic latent image, and the electrostatic on the surface of the photosensitive member. The latent image is developed (visualized) with toner (developer). In the developing device, the toner is sequentially supplied to the surface of the developing roller by a supply roller that rotates in the developing tank, and the toner is supplied to the surface of the photoreceptor by the rotation of the developing roller.
[0003]
The thickness of the toner layer supplied onto the developing roller is regulated on the developing roller by a blade provided downstream of the supply roller in the rotation direction of the developing roller. At the same time, the toner is sandwiched between the blade and the developing roller and receives friction and is charged (friction charging method).
[0004]
The charged toner is carried and conveyed by a developing roller to a portion facing the photosensitive member located further downstream in the rotation direction, and electrostatically supplied to the electrostatic latent image formed on the surface of the photosensitive member. The electrostatic latent image is developed as a toner image. The visualized toner image is transferred onto the recording paper by the transfer means, and then heated and pressurized by the fixing means, and fixed on the recording paper.
[0005]
As described above, in the electrostatic charge image developing method in which the electrostatic latent image is developed with the charged toner, it is important that the charge amount is kept constant. However, the toner charge amount depends on the surrounding environmental conditions. It is easy to change with time and also changes with time. Therefore, in order to cope with such problems, for example, a method of charging the toner by irradiating the toner directly with light inside the developing device by including a photochromic compound that reacts with light of a special wavelength in the toner. Etc. are disclosed (see, for example, Patent Documents 1, 2, and 3).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-281473 (paragraph “0006”, FIG. 1)
[Patent Document 2]
Japanese Patent Laid-Open No. 7-295327 (paragraph “0013”, FIG. 2)
[Patent Document 3]
Japanese Patent Laid-Open No. 9-6132 (paragraphs “0014” to “0016”, FIG. 2)
[0007]
[Problems to be solved by the invention]
However, in the configuration of the above conventional example, as described above, the blade as the layer thickness regulating means is used to regulate the toner layer thickness and at the same time to frictionally charge the toner. That is, in the conventional triboelectric charging method using a blade, the toner is charged by friction with the blade. Therefore, in order to obtain a desired charge amount in the toner, the blade is applied with a relatively large pressure (on the developing roller). F). Therefore, there is a possibility that a large stress acts on the toner by the blade and the toner is destroyed. There is also a problem that toner is fused to the blade.
[0008]
The following points have been confirmed for the energy balance in the frictional charging method. That is, the driving energy (Ek) of the developing roller is converted into toner layer thickness regulation energy (Es) and toner charging energy (Et) by the action of the blade, but a part is consumed as heat loss energy (El). The
[0009]
Depending on the heat loss energy (E1) generated at this time, the toner is softened to promote the destruction of the toner, or the softened toner is fused to the blade surface to deteriorate the frictional charging characteristics of the toner. Problems arise.
[0010]
Further, the technique described in the above publication is for charging the toner by irradiating the toner containing a special photochromic compound with light, and a method for pouring the discharged electrons onto the toner. There is no suggestion.
[0011]
In particular, in recent years, as an energy-saving technique, a toner that reduces the softening point of the toner to reduce the fixing energy or increases the number of pigment parts of the toner to increase the coloring power (decreases the toner's resistance to destruction). Improvement is progressing. However, the conventional frictional charging method is not suitable for such a toner because the pressure and thermal load on the toner are large as described above.
[0012]
The present invention has been made in view of such a situation, and can prevent the destruction of the toner and the fusion to the blade, and can improve the development reliability, in particular, the softening point in order to reduce the fixing energy. It is an object of the present invention to provide a developing device and an electrophotographic apparatus that can be adapted to reduced toner and toner having an increased number of pigments in order to increase coloring power.
[0013]
[Means for Solving the Problems]
In the present invention, means for solving the above-described problems are configured as follows.
[0014]
  (1) A developing device that visualizes an electrostatic latent image on a photoreceptor with toner,
  A developing roller for supplying toner to the photoreceptor;
  A toner regulating blade for regulating the layer thickness of the toner layer formed on the surface of the developing roller;
  An electron emission portion that is formed on a part of the toner regulating blade and charges the toner whose layer thickness is regulated by the toner regulating blade by electrons generated by a photoelectric effect;
  An opening that is provided in the electron emission portion and allows electrons generated by the photoelectric effect to pass through;
  Irradiating means for irradiating light to the electron emitting portion, disposed on the opposite side of the developing roller across a toner regulating blade,
  A shielding member made of a light-transmitting film is provided on the regulating blade so as to cover the electron emission portion from the irradiation unit side, and prevents the toner from moving to the irradiation unit side. And
[0015]
By irradiating the photoelectron emitting member with light of a specific wavelength, photoelectrons are emitted from the photocathode and the toner is negatively charged. However, when the inside of the device is contaminated by external vibration such as installation of the device or toner that floats during operation of the device, or when the toner adheres to the light source that irradiates light on the photocathode, the appropriate amount of photoelectrons cannot be obtained due to the decrease in the light amount The toner charge amount is insufficient. As a result, the fixed specific charge amount of the toner cannot be reached, and the print image is deteriorated.
[0016]
In this configuration, since the shielding member is provided, toner scattering can be prevented and toner adhesion to the light source can be prevented, so that the light quantity can be stabilized and photoelectrons can be generated uniformly. It becomes possible.
[0017]
Further, the photoelectrons for charging the toner are the ones generated at the opening of the photocathode and transferred to the developing roller side. Therefore, the electrons emitted from the opening are not scattered by the shielding member to the light source side, and all the photoelectrons generated at the opening reflected by the shielding member can be transferred to the developing roller side. It is possible to charge well.
[0018]
In this configuration, since the toner is charged by photoelectrons, the blade only needs to be able to regulate the layer thickness of the toner and does not have to apply a large pressure, so the stress (pressure and thermal load) on the toner is greatly increased. Reduced to Therefore, toner breakage and fusion to the blade can be effectively prevented, development characteristics are stabilized, and reliability is improved.
[0019]
  (2)The electron emission portion is provided in the regulation blade such that the opening area on the irradiation means side is larger than the opening area on the surface facing the developing roller, and a mortar-like shape having a photocathode on the inner surface. With an opening,
  The shielding member is on the irradiation means side in the electron emission portion., Provided to cover the openingIt is characterized by that.
[0020]
In this configuration, since the shielding member is provided on the irradiation unit side in the electron emission portion, the passage of the toner to the irradiation unit side is prevented, so that the toner is reliably prevented from adhering to the irradiation unit. And photoelectrons can be efficiently transferred to the developing roller side.
[0021]
(3) The shielding member is a light-transmitting film that transmits light of a specific wavelength.
[0022]
In this configuration, since the shielding member can pass light of a specific wavelength without being attenuated, it is possible to prevent scattering of toner inside the apparatus and to prevent toner adhesion to the light source. Therefore, the amount of light is stabilized, photoelectrons can be generated uniformly, and the toner can be stably charged.
[0023]
(4) The light transmissive film is made of quartz glass or fluorine resin.
[0024]
In this configuration, the use of quartz glass or fluorine-based resin for the light-transmitting film allows light of a specific wavelength to pass through without being attenuated, thereby preventing toner scattering inside the apparatus. In addition, since it is possible to prevent the toner from adhering to the light source, the amount of light can be stabilized, photoelectrons can be generated uniformly, and the toner can be stably charged.
[0025]
In addition, quartz glass or fluorine-based resin is inexpensive and easy to process, so that it can be easily applied to an apparatus.
[0026]
(5) The specific wavelength light is ultraviolet light.
[0027]
In this configuration, by using ultraviolet rays, stable photoelectrons can be emitted, and the specific charge amount of the toner can be improved.
[0028]
(6) The thickness of the shielding member is set to 10 μm to 300 μm.
[0029]
In this configuration, as long as the shielding member is within the above thickness range, stable photoelectron emission can be performed without impeding the transmission of ultraviolet rays. Moreover, if it is said thickness, a material will also be cheap and a process will be easy. The thickness of the shielding member is more preferably 10 μm to 200 μm.
[0030]
(7) An electrophotographic apparatus is characterized by including the developing device according to any one of (1) to (6).
[0031]
With this configuration, it is possible to provide an electrophotographic apparatus provided with a developing device that exhibits the operational effects described in any one of (1) to (6).
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0033]
Embodiment 1
This embodiment will be described with reference to FIG. 1 and FIG. FIG. 1 shows a schematic configuration of a developing device 10. The developing device 10 is disposed so as to face the photosensitive drum 2, and develops an electrostatic latent image formed on the surface of the photosensitive drum 2. Development is performed using, for example, a one-component non-magnetic toner (developer) as an agent. The developing device 10 includes a container-like developing tank 11 that contains toner, a supply roller (developer supply means) 12, a development roller (developer carrier) 13, and a toner regulation blade (layer thickness regulation blade) 14. Yes.
[0034]
The supply roller 12 is disposed in the developing device 10, is rotatably connected to the developing roller 13 so that the outer peripheral surfaces thereof face each other, and removes toner in the developing tank 11 from the outer peripheral surface of the developing roller 13. To supply. The developing roller 13 is rotatably disposed in the developing device 10 at a position facing the photosensitive drum (latent image holding member) 2, and directs the toner supplied by the supply roller 12 toward the photosensitive drum 2. And carry it.
[0035]
The toner regulating blade 14 is disposed so as to contact the developing roller 13 on the downstream side of the supply roller 12 and the upstream side of the photosensitive drum 2 with respect to the rotation direction of the developing roller 13. The layer thickness of the toner layer to be formed is regulated. Further, the developing device 10 emits electrons provided in a part of the toner regulating blade 14 as toner charging means (developer charging means) for charging the toner supplied to the photosensitive drum 2 to a predetermined charge amount. And an ultraviolet irradiator (light irradiating means) 16 for irradiating the electron emitting portion 15 with ultraviolet rays. Details of the toner charging means will be described later.
[0036]
Here, the process part in the electrophotographic apparatus provided with the developing device 10 will be briefly described. As shown in FIG. 1, the process unit mainly includes a photosensitive drum 2, a charging roller 3, an exposure unit (not shown), a developing device 10, a transfer discharge roller 4, a cleaning unit (not shown), a static elimination unit. Means (not shown) and the fixing roller 5. In FIG. 1, P indicates a recording paper, and L indicates a light beam which is irradiated from the exposure means and writes an electrostatic latent image on the surface of the photosensitive drum 2.
[0037]
The photosensitive drum 2 is rotationally driven in a predetermined direction (arrow A direction). First, the outer peripheral surface thereof is uniformly charged by the charging roller 3. The surface of the charged photosensitive drum 2 is irradiated with a light beam L controlled according to image data from the exposure unit, and an electrostatic latent image is formed.
[0038]
The electrostatic latent image is moved to a position facing the developing device 10 by the rotation of the photosensitive drum 2, and is supplied with toner from the developing device 10 to be visualized (developed) (toner on the photosensitive drum 2). An image is formed). At this time, the developing roller 13 of the developing device 10 rotates in a predetermined direction (in the direction of arrow B shown in FIG. 1) in order to carry and carry the toner supplied to the photosensitive drum 2.
[0039]
In this embodiment, the photosensitive drum 2 is composed of an organic optical semiconductor, and is charged to −700 V (charge amount by the charging roller 3) and rotated in the A direction at a peripheral speed of 50 mm / s. Yes. The developing roller 13 is made of a cylindrical conductive rubber elastic material, and is applied with a developing bias of −400 V and is rotated in the B direction at a peripheral speed equal to that of the photosensitive drum 2. The supply roller 12 is made of a cylindrical foaming rubber elastic material, and rotates in the B direction at a peripheral speed equal to that of the photosensitive drum 2.
[0040]
The transfer discharge roller 4 transfers the toner image formed on the photosensitive drum 2 by development onto the paper P. On the downstream side of the transfer discharge roller 4 in the rotation direction of the photosensitive drum 2, a cleaning unit and a discharging unit are further arranged. The cleaning unit removes residual toner on the surface of the photosensitive drum 2 after the transfer, and the discharging unit. The means neutralizes the surface of the photosensitive drum 2.
[0041]
The sheet P after the toner image is transferred is conveyed to the fixing roller 5, and is heated and pressurized when the sheet P passes between the pair of upper and lower fixing rollers 5, so that the toner image is fixed on the sheet P. Is done.
[0042]
Next, the developing process in the developing device 10 will be described in detail. In the developing device 10, as described above, toner is sequentially supplied from the supply roller 12 to the surface of the developing roller 13, and the developing roller 13 rotates while holding the toner. As a result, the toner conveyed by the developing roller 13 is guided between the developing roller 13 and the contact area Ws of the toner regulating blade 14, and the layer thickness of the toner on the developing roller 13 is regulated. The contact area Ws is provided at the tip of the toner regulating blade 14.
[0043]
The toner whose layer thickness is regulated on the developing roller 13 by the toner regulating blade 14 is charged by the electron emission unit 15 and the ultraviolet irradiator 16 constituting the toner charging means, and is charged to a charge amount necessary for development. . That is, by irradiating the electron emitting portion 15 formed on the toner regulating blade 14 with ultraviolet rays from the ultraviolet irradiator 16, photoelectrons are induced from the electron emitting portion 15 by the photoelectric effect. The photoelectrons are emitted toward the toner on the developing roller 13, and the toner is charged to a desired charge amount.
[0044]
Note that the light emitted from the ultraviolet irradiator 16 is preferably synchronized with the rotation of the developing roller 13 to suppress unnecessary light emission that leads to an increase in power consumption. Although not shown, it is preferable that a seal be applied between the electron emission unit 15 and the ultraviolet irradiator 16 so that toner does not enter and obstruct light irradiation.
[0045]
In the toner charging means configured as described above, the electron emitting portion 15 is formed at a position different from the contact area Ws on the toner regulating blade 14 and is not in contact with the toner on the developing roller 13. Charging can be performed with no load applied to the toner.
[0046]
For this reason, in the developing device 10, it is sufficient that the toner regulating blade 14 is in pressure contact with the developing roller 13 with at least a force necessary for regulating the toner layer thickness. The pressure and thermal load can be greatly reduced as compared with the prior art.
[0047]
Further, since the formation region of the electron emission portion 15 is completely non-contact with the developing roller 13, the surface roughness does not affect the toner layer formation, and the surface roughness of the electron emission portion 15 is designed. There are no restrictions on the above.
[0048]
The toner charged to a predetermined charge amount by the toner charging means is further sent to a portion facing the photosensitive drum 2 by the rotation of the developing roller 13, and an electrostatic latent image formed on the surface of the photosensitive drum 2. The electrostatic latent image is developed (visualized) as a toner image.
[0049]
Next, a specific configuration of the toner regulating blade 14 will be described with reference to FIGS. 2 (a) and 2 (b).
The toner regulating blade 14 uses, for example, a metal material made of SUS (that is, a conductive base material) as a base material, and in the region where the electron emission portion 15 is formed, FIGS. As shown in FIG. 5, a plurality of openings 151 are provided by etching or the like. Further, in the region where the electron emission portion 15 is formed, a thin film of aluminum is stacked as the photocathode 152 by, for example, vapor deposition.
[0050]
In the description of FIG. 2A, the opening 151 has a configuration in which a large number of circular small-diameter holes are formed. However, in the present invention, the shape of the opening 151 is not particularly limited. It may be a square or triangular shape, or may be a slit-shaped opening.
[0051]
The material for forming the photocathode 152 is not limited to aluminum as described above, but any other metal such as Ta, Mg, etc., as long as the photoelectric effect occurs when irradiated with light. It may be an alloy such as -Ag, a semiconductor, or a conductive polymer. Further, the photocathode 152 does not necessarily have to be formed on both sides of the toner regulating blade 14 as shown in FIG. 2 (b), as long as it is formed on at least the side facing the ultraviolet irradiator 16. Good.
[0052]
Furthermore, the light emitted to the electron emission portion 15 is not limited to the ultraviolet rays as described above, but has a wavelength that can generate a photoelectric effect on the material forming the photocathode 152. If it exists, visible light, X-rays, etc. may be sufficient.
[0053]
In the toner regulating blade 14 configured as described above, when the photocathode 152 of the electron emission portion 15 is irradiated with ultraviolet rays, photoelectrons due to the photoelectric effect are induced on the photocathode 152. The photoelectrons are mainly generated on the ultraviolet irradiation surface side, that is, on the surface facing the ultraviolet irradiator 16, but a part of the generated photoelectrons passes through the opening 151 of the electron emission portion 15. Thus, it is emitted toward the toner from the side facing the developing roller 13 and contributes to the charging of the toner.
[0054]
Further, it can be easily understood that, in the electron emission portion 15, if the electron emission portion 15 is in an electrically floating state, the photocathode 152 of the electron emission portion 15 cannot continue to emit photoelectrons. For this reason, the electron emission unit 15 needs to be configured to be able to supply the electrons emitted from the photocathode 152 from the outside. Here, since the electron emitting portion 15 has a configuration in which an aluminum thin film is deposited as the photocathode 152 on the base material of the toner regulating blade 14 made of SUS, the base material of the toner regulating blade 14 is grounded, The configuration can be easily realized.
[0055]
As described above, the developing device 10 according to the first embodiment can significantly reduce the pressure contact force of the toner regulating blade 14 as compared with the developing device using the conventional frictional charging method. As a result, the pressure applied to the toner by the toner regulating blade 14 and the thermal load are greatly reduced, and problems such as toner destruction and toner fusion to the toner regulating blade 14 can be avoided.
[0056]
<< Embodiment 2 >>
This embodiment will be described with reference to FIGS. In the developing device 10 according to the first embodiment, photoelectrons induced from the photocathode 152 by the photoelectric effect are emitted toward the toner from the surface facing the developing roller 13 through the opening 151 of the electron emission unit 15. Is done. However, in the above configuration, photoelectrons generated on the light irradiation surface side of the toner regulating blade 14 do not necessarily pass through the opening 151, and photoelectrons that do not pass through the opening 151 do not contribute to charging of the toner. For this reason, the toner charging means of the developing device 10 does not have a very high toner charging efficiency.
[0057]
In the second embodiment, the toner charging efficiency can be improved in the developing device. As shown in FIG. 3, the developing device 100 replaces the toner regulating blade 14 with a toner regulating blade 140 in the configuration of the developing device 10 and applies an electrical bias between the toner regulating blade 140 and the developing roller 13. It is configured to do.
[0058]
Therefore, the toner regulating blade 140 is connected to the bias applying unit 19. The bias applying unit 19 can be configured to be connected to the base material of the toner regulating blade 140. Further, the bias applying means 20 on the developing roller 13 side can be used as it is as a bias applying means for applying a developing bias between the photosensitive drum 2 and the developing roller 13. Other configurations of the developing device 100 are the same as those of the developing device 10.
[0059]
A specific configuration of the toner regulating blade 140 will be described with reference to FIGS. The toner regulating blade 140 has substantially the same configuration as the toner regulating blade 14, but as shown in FIG. 4B, an insulating layer 17 and a metal layer 18 are provided in the contact area Ws with the developing roller 13. Is different. The configuration of the electron emitter 15 formed on the toner regulating blade 140 is the same as that of the toner regulating blade 14.
[0060]
In the developing device 100, since an electrical bias is applied between the toner regulating blade 140 and the developing roller 13, the conductive base material of the toner regulating blade 14 and the developing roller 13 are in direct contact with each other as in the developing device 10. If this is the case, the toner regulating blade 14 and the developing roller 13 become conductive, and the electrical bias as described above cannot be applied.
[0061]
That is, the insulating layer 17 is provided to insulate between the developing roller 13 and the base material of the toner regulating blade 140. For example, the insulating layer 17 is formed as a fluororesin layer having a thickness of 80 μm on the base material. The
[0062]
The metal layer 18 provides appropriate hardness and surface roughness on the contact surface with the developing roller 13 so that a uniform toner layer is formed on the surface of the developing roller 13. As the metal layer 18, for example, a SUS metal layer having a thickness of 20 μm is laminated.
[0063]
The structure for insulating between the developing roller and the toner regulating blade is not limited to the structure in which the insulating layer is provided on the toner regulating blade side as described above, but the outer periphery of the developing roller made of a conductive substrate. For example, the layer may be provided with an insulating layer such as rubber.
[0064]
In the developing device 100 having the above configuration, by applying an electrical bias between the toner regulating blade 140 and the developing roller 13, the charging effect can be improved by the following two actions.
[0065]
(1) As a first action, an electric field is generated between the toner regulating blade 140 and the developing roller 13 by applying the electrical bias. At this time, electric lines of force (shown by broken lines in the figure) as shown in FIG. 5 are generated in the vicinity of the opening 151 in the electron emission part 15 of the toner regulating blade 140.
[0066]
For this reason, photoelectrons generated in the vicinity of the opening 151 on the photocathode 152 of the electron emission portion 15 move along the lines of electric force, pass through the opening 151, and are attracted to the developing roller 13 side. That is, the generated photoelectrons can be efficiently used for charging the toner.
[0067]
(2) As a second action, photoelectrons drawn toward the developing roller 13 are accelerated by the action of the electric field. When the accelerated electrons collide with gas molecules, the gas molecules emit electrons and ionize. At this time, since electrons emitted from the gas molecules also have the same effect, a so-called avalanche phenomenon occurs in which the electrons in the gas increase rapidly. Since the electrons generated by the avalanche also contribute to the charging of the toner, the charging efficiency is greatly improved.
[0068]
Here, the electric bias between the developing roller 13 and the toner regulating blade 140 has an electric field strength of 0.5 to 2.5 × 10.⁶It is applied in the range of (V / m). At this time, a desired charge amount (−2.0 × 10^-2FIG. 6 shows the relationship between the electric field strength and the process speed when (μC / kg) is obtained.
[0069]
As is apparent from FIG. 6, the process speed at which a desired charge amount can be obtained is improved by increasing the electric field strength of the electric bias. When an electric bias in the above range is applied, the process speed is 50 to 200 mm. The toner can be charged up to / s.
[0070]
FIG. 7 shows the relationship between the pressure applied by the toner regulating blade 140 and the charging characteristics of the toner in the configuration of the developing device 100 according to the second embodiment. At this time, the pattern conditions of the opening 151 in the electron emission portion 15 are an opening ratio of 40% and a hole shape of the opening 151 of φ200 μm. The ultraviolet irradiator 16 irradiates ultraviolet light having a wavelength of 254 nm. The aperture ratio indicates the ratio of the area of the opening 151 to the area of the formation region of the electron emission portion 15. Further, there is a 5 × 10 between the developing roller 13 and the toner regulating blade 140.^-6An electrical bias of V / m is applied.
[0071]
From FIG. 7, it can be seen that in the conventional frictional charging method, a pressure of about 196 kPa is required to obtain a desired charge amount of the toner. On the other hand, in the charging system of the present invention, a desired charge amount can be obtained with a pressure of 1/4 that is necessary for the conventional friction charging system, that is, a pressure of about 49 kPa.
[0072]
<< Embodiment 3 >>
This embodiment will be described with reference to FIG. In the first and second embodiments, in the electron emission portion 15 of the toner regulating blade 14 or the toner regulating blade 140, the shape of the opening 151 in the blade cross section (see FIG. 2B) is a rectangular shape. That is, in the opening 151 of the electron emission portion 15 in the first and second embodiments, the opening area on the light irradiation surface side and the opening area on the surface facing the developing roller 13 are equal.
[0073]
On the other hand, in the toner regulating blade according to the third embodiment, the shape of the opening in the electron emission portion is set so that the opening area on the light irradiation surface side is larger than the opening area on the surface facing the developing roller 13. Thus, the area of the light receiving region in the electron emission portion 15 is enlarged to increase the amount of photoelectrons generated.
[0074]
An example of the toner regulating blade in the third embodiment is shown in FIGS. The toner regulating blade 21 uses, for example, a SUS metal material (that is, a conductive substrate) as a substrate, and an electron emission portion 22 is formed in a part thereof. The electron emission portion 22 is provided with a plurality of openings 221, and a thin film of aluminum is stacked as the photocathode 222 by, for example, vapor deposition.
[0075]
Here, the opening 221 has a mortar shape such that the opening diameter φ1 on the light irradiation surface side and the opening diameter φ2 on the surface facing the developing roller 13 satisfy φ1> φ2. The opening 221 having the above shape can be easily formed in the toner regulating blade 21 by, for example, single-side etching (a straight hole as shown in FIG. 2 is obtained when double-side etching is performed. ). The photocathode 222 may be formed at least on the light irradiation surface side and the inner surface of the opening 221 in the electron emission portion 22.
[0076]
In the case where the electron emitting portion 22 has such a shape, light irradiated to the electron emitting portion 22 is received by the photocathode 222 and the inner surface of the opening 221. For this reason, the area of the light receiving region in the electron emission portion 22 can be increased, and the amount of photoelectrons generated can be increased to stabilize toner charging.
[0077]
However, the shape of the opening 221 is not particularly limited as long as the relationship of (opening area on the light irradiation surface side)> (opening area on the surface facing the developing roller 13) is satisfied. Is no different from the case of the electron emitter 15 in the first and second embodiments.
[0078]
The toner regulating blade 21 may be configured not to apply an electrical bias between the toner regulating blade 21 and the developing roller 13 as in the developing device 10 according to the first embodiment. However, as in the developing device 100 according to the second embodiment, an insulating layer is provided in the contact area Ws with the developing roller 13 and an electric bias is applied between the toner regulating blade 21 and the developing roller 13. More preferably.
[0079]
<< Embodiment 4 >>
In the first embodiment, in order to stabilize the light emission amount of the ultraviolet irradiator 16, the space between the electron emission unit 15 and the ultraviolet irradiator 16 is sealed so that toner does not enter and obstruct light irradiation. Is described as being preferable. In this regard, a measure for stabilizing the toner charge amount will be described below.
[0080]
Conventionally, for example, as shown in FIG. 10, the electron emission portion 15 is not provided with a light transmission film, and a photoelectric effect is generated by the ultraviolet rays irradiated from the ultraviolet irradiator 16, and the electron emission portions 15 Photoelectrons are emitted and transferred to the developing roller side, but some of the emitted photoelectrons are emitted toward the ultraviolet irradiator 16 (see the upward arrow).
[0081]
Therefore, in this embodiment, for example, as shown in FIG. 9, a light transmissive film 23 serving as a shielding member is attached to the surface of the electron emitter 15 on the ultraviolet irradiator 16 side. That is, as shown in the figure, the toner is sealed inside the developing device 10 on the developing roller 13 side by attaching the light transmissive film 23 so as to cover the opening 151 formed in the electron emitting portion 15. Thus, the scattering of the toner to the ultraviolet irradiator 16 side can be completely prevented. Thereby, contamination of the ultraviolet irradiator 16 can be prevented, and the above-mentioned conventional difficulties can be solved.
[0082]
The light transmission film 23 may be made of, for example, quartz glass, fluororesin, or the like, which has a characteristic of allowing ultraviolet rays of a specific wavelength to pass through without being attenuated and prevents the passage of toner and foreign matters. Can do. More specifically, for example, “Aflon LM series” and “Cytop” manufactured by Asahi Glass Co., Ltd. are suitable.
[0083]
In such a configuration, as described above, since the toner is charged in a non-contact manner by photoelectrons, the blade 15 only needs to be able to regulate the layer thickness of the toner and does not need to apply a large pressing force. Stress (pressing force and thermal load) is greatly reduced. Therefore, it is possible to effectively prevent the destruction of the toner and the fusion to the blade, and the light transmission film 23 stabilizes the irradiation light quantity, so that the development characteristics are further stabilized and the good image formation is possible. It becomes.
[0084]
【The invention's effect】
As is clear from the above description, the present invention has the following effects.
[0085]
(1) Since the shielding member for preventing the movement of the toner from the electron emitting portion to the irradiation means side is provided, it is possible to prevent the toner from scattering and to prevent the toner from adhering to the light source. As a result, the amount of light is stabilized and photoelectrons can be generated uniformly. In addition, since all the photoelectrons that are reflected by the shielding member and generated in the opening portion move to the developing roller side, efficient charging is possible. Since the toner is charged by photoelectrons, the blade only needs to be able to regulate the layer thickness of the toner as in the prior art, and it is not necessary to apply a large pressure, so the stress on the toner is greatly reduced. Therefore, toner breakage and fusion to the blade can be effectively prevented, development characteristics are stabilized, and reliability is improved.
[0086]
(2) Since the shielding member is provided on the irradiation unit side in the electron emission portion, the passage of the toner to the irradiation unit side is blocked, so that the toner can be reliably prevented from adhering to the irradiation unit. In addition, photoelectrons can be efficiently transferred to the developing roller side.
[0087]
(3) Since the shielding member is a light-transmitting film that transmits light of a specific wavelength, light of a specific wavelength can be passed without being attenuated, and toner scattering inside the apparatus can be prevented. Further, since the toner can be prevented from adhering to the light source, the amount of light can be stabilized, photoelectrons can be generated uniformly, and the toner can be stably charged.
[0088]
(4) Since quartz glass or fluororesin is used for the light transmissive film, light of a specific wavelength can be transmitted without being attenuated, and toner scattering inside the apparatus can be prevented. Further, since toner can be prevented from adhering to the light source, the amount of light can be stabilized, photoelectrons can be generated uniformly, and toner can be stably charged. Quartz glass or fluorine-based resin is inexpensive and easy to process, so that it can be easily applied to an apparatus.
[0089]
(5) Since ultraviolet rays are used as the light of a specific wavelength, stable photoelectrons can be emitted, so that the specific charge amount of the toner can be improved.
[0090]
(6) Since the thickness of the shielding member is set to 10 μm to 300 μm, stable photoelectron emission can be performed without inhibiting the transmission of ultraviolet rays. Moreover, if it is said thickness, a material will also be cheap and a process will be easy.
[0091]
(7) It is possible to provide an electrophotographic apparatus provided with a developing device that exhibits the effects described in any one of (1) to (6).
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a developing device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a configuration of a toner regulating blade used in the developing device.
FIG. 3 is a cross-sectional view illustrating a schematic configuration of a developing device according to a second embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a configuration of a toner regulating blade used in the developing device.
FIG. 5 is a diagram illustrating electric lines of force generated in the vicinity of the opening of the toner regulating blade when an electrical bias is applied between the toner regulating blade and the developing roller.
FIG. 6 is a graph showing a relationship between an electric field intensity of an electric bias applied between the toner regulating blade and the developing roller and a process speed capable of forming an image.
FIG. 7 is a graph showing the relationship between the toner charge amount and the pressure applied by the toner regulating blade in the developing device.
FIG. 8 is an explanatory diagram of a toner regulating blade in the developing device according to the third embodiment of the present invention.
FIG. 9 is an explanatory diagram of a toner regulating blade in the developing device according to the fourth embodiment of the present invention.
FIG. 10 is an explanatory diagram illustrating an example of a conventional toner regulating blade.
[Explanation of symbols]
2-Photoconductor
10,100-Developing device
15-electron emission part
16-Irradiation means
23-Shielding member

Claims (7)

A developing device that visualizes an electrostatic latent image on a photoreceptor with toner,
A developing roller for supplying toner to the photoreceptor;
A toner regulating blade for regulating the layer thickness of the toner layer formed on the surface of the developing roller;
An electron emission portion that is formed on a part of the toner regulating blade and charges toner whose layer thickness is regulated by the toner regulating blade by electrons generated by a photoelectric effect;
An opening that is provided in the electron emission portion and allows electrons generated by the photoelectric effect to pass through;
An irradiating means for irradiating light to the electron emitting portion, disposed on the opposite side of the developing roller with a toner regulating blade interposed therebetween,
A shielding member made of a light-transmitting film is provided on the regulating blade so as to cover the electron emitting portion from the irradiation unit side, and prevents the toner from moving to the irradiation unit side. A developing device. The electron emission portion is provided in the regulation blade such that the opening area on the irradiation means side is larger than the opening area on the surface facing the developing roller, and a mortar-like shape having a photoelectric surface on the inner surface. With an opening,
The developing device according to claim 1, wherein the shielding member is provided on the irradiation unit side of the electron emission portion so as to cover the opening.   The developing device according to claim 1, wherein the shielding member is a light transmissive film that transmits light of a specific wavelength.   The developing device according to claim 3, wherein the light transmissive film is made of quartz glass or fluorine resin.   The developing device according to claim 3, wherein the light having the specific wavelength is ultraviolet light.   The developing device according to claim 1, wherein a thickness of the shielding member is set to 10 μm to 300 μm.   An electrophotographic apparatus comprising the developing device according to claim 1.

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