JP4901449B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus used for image formation by an electrostatic copying process, such as a copying machine, a facsimile machine, and a printer.

A cleaning blade is widely used as a method for cleaning the transfer residual toner, and the cleaning blade and the photoconductor are worn over time due to the contact pressure between the cleaning blade and the photoconductor. In particular, the recent toner tends to have a spherical diameter and a small particle diameter, and unless the contact pressure is further increased, the toner slips through the cleaning blade. In order to extend the life of the photoreceptor and the cleaning blade, the contact pressure must be reduced.
For this purpose, it is necessary to reduce the force of the toner to bite into the blade by reducing the charge amount of the toner and lowering the mirror image force between the toner and the photoreceptor, thereby reducing the adhesion and frictional force between the photoreceptor and the toner.

Up to now, as a technique for reducing the charge amount of the toner and reducing the mirror image force between the toner and the photoconductor, for example, in Patent Document 1, after negatively charging the photoconductive colored particles, an electric field is applied to the surface of the particle carrier. Fill in the holes. Then, when exposed from the translucent conductive layer side, hole-electron pairs are generated in the photoconductive colored particles, and 10 @ + 4 V / cm or more formed between the translucent conductive layer and the screen electrode. This hole-electron pair is dissociated by a high electric field, electrons in the negatively charged colored particles leak to the translucent conductive layer side, and the colored particles are positively charged to transmit light to the counter electrode on the back of the recording medium. Flying to the recording medium side by an electric field formed between the conductive layer and the electroconductive layer, and adheres to the recording medium to form an image. However, since even by photoconductive toner. However, in the optical bias of the present invention, a bias electric field for transfer or the like is applied and the insulating toner on the ITO electrode that is conductive changes to the charge of the toner that is charged only when light is irradiated. This is very different from what you see.

In Patent Document 2, when an intermediate transfer body having a resistivity changing layer in which volume resistivity is lowered in a state where a predetermined physical stimulus (light irradiation or the like) is applied, after passing through the static elimination region after secondary transfer, An image forming apparatus is disclosed that neutralizes an intermediate transfer member in a state where a physical stimulus is applied to the intermediate transfer member to reduce the volume resistivity of the intermediate transfer member. This is because when the primary transfer and the secondary transfer are performed using a transfer device that generates a transfer electric field, it is possible to perform transfer with less toner scattering while the volume resistivity of the intermediate transfer member is high. The charge of the intermediate transfer member generated by the transfer electric field can be easily removed.
However, it is related to the photosensitivity of the intermediate transfer member, and the toner on the ITO electrode, which is already conductive and to which a bias electric field such as transfer of optical bias of the present invention is applied, was irradiated with light. This is different from the technology that only changes toner charge.

In Patent Document 3, a non-magnetic one-component toner containing a photoconductive material whose conductivity is changed by light or a photocharge control material whose charging property is changed by light, and a toner for charging a toner of a developing machine using the toner. A light irradiation means for irradiating the toner layer with light is disposed upstream of the charging member, and the light emission amount or light emission frequency of the light irradiation mechanism is controlled. However, this is due to the photoconductive toner.
In the optical bias of the present invention, a bias electric field such as transfer is applied, and the toner charge is changed only when the insulating toner on the ITO electrode that is conductive is irradiated with light. Different.

In Patent Document 4, the toner layer thickness of the photoconductive toner applied to the transparent conductive carrier 2 is made a uniform thin layer by an elastic blade, and is negatively charged by frictional charging. A counter electrode is disposed at a predetermined distance from the carrier, and a transfer electric field is formed in the transfer region by a power source. When the exposure unit irradiates the toner, the resistance of the irradiated toner decreases, and a positive charge is injected from the carrier. The positively charged toner is transferred from the carrier to the transfer material on the counter electrode by a transfer electric field. Since the toner layer on the carrier and the recording material are not in contact with each other at the time of transfer, unlike the contact transfer method, fine adjustment of the contact pressure is unnecessary, and there is no toner fusion, fogging and the like. However, this is due to the photoconductive toner.
In the optical bias of the present invention, a bias electric field such as transfer is applied, and the toner charge is changed only when the insulating toner on the ITO electrode that is conductive is irradiated with light. Wrong.

In Patent Document 5, when a photosensitive toner layer is image-exposed to form a combination of a charge-removed toner and a charged toner, and then the charge-removed toner is removed from a conductive substrate by contact with a magnetic brush, It has a tangential magnetic flux density distribution of two peaks separated from the upstream side and the downstream side around the nip position with the substrate, and the downstream peak has a smaller value than the upstream peak. Sets the magnetic flux density distribution of the main pole at the developing sleeve. However, this is due to photosensitive toner.
In the optical bias of the present invention, a bias electric field such as transfer is applied, and the toner charge is changed only when the insulating toner on the ITO electrode that is conductive is irradiated with light. Wrong.

In Patent Document 6, an image is formed by forming a charged photosensitive toner layer on a conductive drum, exposing the photosensitive toner layer to an image, and electrostatically transferring the formed toner electrostatic image to a transfer material. Discloses that the image exposure area and the electrostatic transfer area are set so that the opening angle on the drum is within 80 degrees. However, this is due to photosensitive toner.
In the optical bias of the present invention, a bias electric field such as transfer is applied, and the toner charge is changed only when light is irradiated to the insulating toner on the already conductive ITO electrode. It ’s very different.

In Patent Document 7, the photoconductive toner supplied from the two-component developing device in the back exposure of the transparent support comprises a photoconductive substance that maintains the charge injected during development. This is because, even with a low-resistance photoconductive toner, the relaxation time of reverse charge injection becomes long, so that the toner charge is prevented from being neutralized within the transfer time. The reason for the effect of improving transferability is not described as low resistance during bias + light irradiation development and high resistance in the absence of light during transfer (dark place). It is well known that the photoconductive toner has a low resistance and changes the toner charge when irradiated with light (light bias). However, since the injection time of transfer corona negative ions having the opposite polarity to the toner charge is long, the positive charge of the toner is increased. Is transferred without being neutralized within the transfer time.
The optical bias of the present invention is greatly different from the point that a change in the toner charge is observed only when the toner on the ITO electrode, which is electrically conductive, is applied with a bias electric field such as transfer, and is irradiated with light.

In Patent Document 8, a voltage is applied between the developing machine and the transparent conductive layer. By increasing the thickness of the photoconductive layer, the electric adhesion is weakened, and the amount of toner adhering to the photoreceptor is reduced. In the exposed portion, which is an image portion, the photocarrier generated in the photoconductive layer at the time of light beam irradiation moves to the toner side, a reverse charge is induced in the toner, and the toner adheres on the photoreceptor by electrostatic attraction. However, when a light beam is irradiated by charge induction development on the conductive magnetic toner, the generated photocarrier moves to the toner side in the photoconductive layer. As a result, the toner adheres on the photoreceptor by electrostatic attraction with the reverse charge induced in the toner.
The optical bias of the present invention is greatly different from the point that a change in the toner charge is observed only when the toner on the ITO electrode, which is electrically conductive, is applied with a bias electric field such as transfer, and is irradiated with light.

In Patent Document 9, an image is exposed from the back side of a photoreceptor having a uniform toner layer, and a transfer material and a corona transfer unit are arranged in this order so as to face the image exposure unit, and the toner charge is lost by exposure. A reverse polarity charge is injected so that the toner is transferred to the transfer material. (Transfer) There is a configuration of light irradiation to toner in an electric field. The toner charge changes under the influence of light. However, the mechanism of causing the toner charge to be lost or the reverse polarity charge injection is to change the insulating property of the photoconductor as a toner support by exposure to a conductor.
The optical bias of the present invention is greatly different from the point that a change in the toner charge is observed only when the toner on the ITO electrode, which is electrically conductive, is applied with a bias electric field such as transfer, and is irradiated with light.

In patent document 10, a surface exposure development system. The configuration is such that the charged toner is transferred onto the recording paper while injecting the charge into the charged toner attached to the photosensitive member by the light irradiation means facing the transfer device. However, the low-resistance conductive toner loses electric charge when the support-based transparent photoconductor conducts.
In the optical bias of the present invention, a bias electric field such as transfer is applied, and the toner charge is changed only when the insulating toner on the ITO electrode that is conductive is irradiated with light. Wrong.

In Patent Document 10, in Japanese Patent Publication No. 06-046322, image exposure is performed from the transparent substrate side, and trap charges are formed on the photoconductive film). Then, a low-resistance charged magnetic toner is attached to the trapped charge with electrostatic force, and after the transfer, the toner is irradiated with light to remove the toner and the remaining trapped charge on the photoconductive film is removed. We weaken electrostatic force between toner and photoconductive film and collect in magnetic brush developing machine. There is a configuration of light irradiation to toner in an electric field. The toner charge on the conductive support to which a bias is applied does not change using photo-conductivity of the toner as a trigger for light irradiation. However, the low-resistance conductive toner loses electric charge when the support-based transparent photoconductor conducts.
In the optical bias of the present invention, a bias electric field such as transfer is applied, and the toner charge is changed only when the insulating toner on the ITO electrode that is conductive is irradiated with light. Wrong.

In Patent Document 11, a photoconductive toner layer is formed on a support (conductive layer-dielectric layer-conductive layer), charged and exposed to transfer the charged toner. It is disclosed that toners become conductive in response to light and lose their charge. However, the photoconductive toner light on the support is not transferred to the primary transfer body by selectively transferring the particles that retain the charge to prevent transfer of microcarriers mixed on the support. As a description that the charge changes, a conventional photoconductive property is used. There is no configuration in which toner is placed in an electric field for light irradiation. Such a phenomenon cannot be imagined with toner without photoconductivity.
The optical bias of the present invention is greatly different from the point that a change in the toner charge is observed only when the toner on the ITO electrode, which is electrically conductive, is applied with a bias electric field such as transfer, and is irradiated with light.

In Japanese Patent Laid-Open No. 2004-228867, image formation that can prevent toner contamination of the charging unit by accurately adjusting the charge amount of the toner on the image carrier and prevent defects on the print sample due to the toner contamination. Get the device. However, since the discharge current increases due to the promotion of the conduction of the photoconductor by the photostatic discharge, it can be said that the toner on the photoconductor is also affected and becomes sufficiently negatively charged.
Even in the same light irradiation environment, a bias electric field such as transfer is applied with the optical bias of the present invention, and the toner charge changes only when the toner on the ITO electrode that is conductive is irradiated with light. This is very different from what you see.

  Patent Document 13 discloses a technique for reducing the load of the cleaning means by providing a pre-cleaning static elimination mechanism to weaken the electrostatic force of the transfer residual toner with respect to the photosensitive drum. However, the photoconductor is simply neutralized by light irradiation, and the electrostatic force of the transfer residual toner to the photoconductor is weakened. In this case, it is difficult to remove the adhesion force of the toner to improve the cleaning property or to use the cleanerless method.

JP 2001-277594 A JP-A-11-305557 JP 09-006132 A JP 07-253704 A JP 04-249266 JP 04-051177 JP 03-122657 A Japanese Patent No. 2617912 JP 61-262778 A JP 06-046322 JP 61-019873 JP-A-2005-258323 JP 10-049017 A

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image forming apparatus that suppresses the image force by performing not only the charge removal of the photosensitive member but also the charge removal of the toner simultaneously by light irradiation and bias application. Is to provide.

The features of the present invention, which is a means for solving the above problems, are listed below.
In the image forming apparatus of the present invention, an electrostatic latent image forming unit (comprising a photoconductor, exposure, and a charging roller) that forms an electrostatic latent image; and a developing unit that develops the latent image to form a toner image; An image forming apparatus comprising at least one image forming unit comprising a transfer unit that transfers the toner image to an image carrier and a cleaning unit that cleans residual toner that has not been transferred to the image carrier. An electrode for contacting the transfer residual toner, and a light irradiation means for irradiating the transfer residual toner with light at the same time as bringing the electrode into contact with the transfer residual toner. A transmissive conductive member that also serves as a cleaning unit, wherein the light irradiating unit irradiates light from a side opposite to the toner contact surface of the electrode and transmits light to the toner through the electrode. .
In the image forming apparatus of the present invention, the potential applied to the electrode is positive .
In the image forming apparatus of the present invention, furthermore, the potential applied to said electrodes, you being a negative polarity.
Also, in the image forming apparatus of the present invention, further, the toner is applied is characterized by containing photoconductive materials or light charge controlling material conductive by light changes.
In the image forming apparatus of the present invention, further, the light emitting quantity of the light irradiation unit, emission wavelength, at least one of the light emitting frequency, preparative toner amount and light control to control in accordance with the amount of charge imparted to the toner It has the means.
In the image forming apparatus of the present invention, further, characterized in that it has a voltage control means for controlling the amount of charge imparted a voltage applied to the electrodes to the toner amount and toner.
In the image forming apparatus of the present invention, further, the light control means及beauty / or voltage control means, and controlling by detecting the image bearing member periphery of environmental conditions (temperature and humidity) .
In the image forming apparatus of the present invention, the toner used in the present system further has a volume average particle diameter of 4 to 10 μm, and a ratio (D4) of the volume average particle diameter (D4) to the number average particle diameter (D1). / D1) is in the range of 1.00 to 1.40.
In the image forming apparatus of the present invention, the toner used in the system further has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. And
In the image forming apparatus of the present invention, the toner used in the present system further removes fine particles having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 mg / cm ³ or more on the surface of the toner base particles. It is a toner obtained by adding.

  According to the present invention, by reducing the mirror image force between the toner and the photosensitive member, the force in the direction in which the toner bites into the blade direction is drastically reduced, so that cleaning can be performed even when the contact pressure of the cleaning blade is lowered.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 is a schematic diagram showing a configuration around a photoconductor in an embodiment of the present invention. The area around the cleaning member of the present invention will be described in detail with reference to FIG.
Untransferred toner that has not been transferred to the image carrier belt by the transfer roller 14 is sent in the direction of the cleaning member 7 as the photosensitive member 1 rotates. Cleaning member 7, the conductive particles (metal oxide such as tin oxide, ion conductive agent, etc.) and cleaning blade with urethane rubber containing dispersed, it is possible to adjust the potential. A light source 6 is disposed as a light irradiating means for irradiating the toner through the cleaning member 7. The transfer residual toner is conveyed to the cleaning member 7. Here, the untransferred toner simultaneously receives light irradiated from the light source 6 and transmitted through the cleaning member 7 which is a transparent electrode. In addition, the untransferred toner is thinned by the elastic force and made uniform at the same time when passing through the wedge-shaped portion formed between the cleaning member 7 and the photoreceptor 1. In this state, all toner receives light uniformly, and the toner resistance value decreases, so that a bias generated between the toner and the cleaning member 7 causes electrons to enter and exit between the toner and the cleaning member 7.

The potential controller of the cleaning member 7 (not shown) adjusts the moving direction of the electrons. When the potential of the cleaning member 7 is higher than the potential of the toner, electrons flow out of the toner, so that the charge amount of the toner increases, and conversely, when the potential of the cleaning member 7 is lower than the potential of the toner. The toner flows in and the charge amount of the toner decreases.
Also, a light controller (not shown) adjusts the amount of movement of electrons. The amount of toner flowing in / out per unit time can be adjusted by changing the resistance of the toner according to the light intensity, wavelength, or the like. These controls are performed according to the charge amount of the toner, the environmental conditions, the residual toner amount, and the like.
The weakly charged toner can be easily removed from the photoreceptor 1 without increasing the contact pressure between the cleaning member 7 and the photoreceptor 1 more than necessary. The removed toner passes through the conveyance path 8 and is sent to a waste toner bottle.

FIG. 2 is a diagram for explaining the force received by the toner depending on the charge amount of the toner.
As shown in FIG. 2A, when the charge amount of the toner is large, the mirror image force F1 acting between the toner and the photoreceptor 1 becomes large. This also has a Coulomb force that acts between the charge amount of the toner and the residual potential in the photoreceptor 1, but this is omitted here.
Further, the toner moves in the direction opposite to the moving direction of the photosensitive member 1 indicated by the white arrow, as indicated by the hatched arrow. For this purpose, the frictional force F31 acting between the toner and the photosensitive member 1 according to the friction coefficient between the toner and the photosensitive member 1 due to the electric force acting between the toner and the photosensitive member 1. Also grows.
Further, the toner hitting the cleaning member 7 receives a repulsive force F <b> 2 pressed from the cleaning member 7. The repulsive force F2 depends on the peripheral speed of the photosensitive member 1, the hardness of the cleaning member 7 / toner, and the like, and is a value determined regardless of the electrical properties of the toner, the charge amount, and the like. Further, there is a frictional force F32 acting between the toner and the cleaning member 7 between the toner and the cleaning member 7 according to the friction coefficient, but this value is determined regardless of the charge amount of the toner. It is.
Accordingly, when viewed largely, the difference between the repulsive force F2 and the frictional force F31 determines the force F4 acting on the toner in the toner moving direction.
Similarly, as shown in FIG. 2B, when the charge amount of the toner is small, the mirror image force F1 acting between the toner and the photoreceptor 1 is small, and the corresponding friction force F31 is also small. The repulsive force F2 that the cleaning member 7 acts on the toner has the same magnitude because it is not related to the charge amount. For this reason, the force F4 acting in the moving direction of the toner due to the difference between the repulsive force F2 and the frictional force F31 is increased, and as a result, the toner is easily cleaned.

Next, toner characteristics used in the present invention will be described.
For the photoconductive toner used in the present invention, various organic compounds such as phthalocyanine compounds used in the photoreceptor 1 and inorganic powders such as zinc oxide and amorphous silicon are appropriately melted and mixed in a resin for toner. Accordingly, it can be easily produced by adding a sensitizer and dispersing it uniformly.
Regarding the particle diameter, the volume average particle diameter of the toner is preferably 4 to 10 μm. When a small particle diameter toner having an average particle diameter of 10 μm or less can be used, the bulk density of the developer can be increased, so that the agent can be stably stirred and conveyed, and the recovery efficiency of the transfer residual toner can be improved. In addition, since the particle size distribution is sharp, the developer has good fluidity, and it is possible to perform a stable agent circulation over a long period of time, thereby improving the replenishment toner diffusibility. Further, the transparent electrode portion can be easily thinned, so that the light irradiation to the toner and the contact with the electrode become uniform, and charge injection can be performed stably. For this reason, collection / discharge with a brush and collection at a developing unit are facilitated. On the other hand, since the gap between the toners is reduced and the toner is more satisfactorily contained in the image, it is possible to reduce the required toner adhesion amount and the height (pile height) of the toner image. Regarding the reproducibility of minute dots of 600 dpi or more, the dot reproducibility is excellent in this range because the toner particles have a sufficiently small particle diameter with respect to the minute latent image dots. Increases image stability.

On the other hand, when the volume average particle diameter (D4) is less than 4 μm, phenomena such as a decrease in transfer efficiency and a decrease in recoverability with a brush tend to occur. When the volume average particle diameter (D4) exceeds 10 μm, the pile height of the image becomes large, and it becomes difficult to suppress scattering of characters and lines. At the same time, the ratio (D4 / D1) of the weight average particle diameter (D4) to the number average particle diameter (D1) is preferably in the range of 1.00 to 1.30. The closer (D4 / D1) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.
Next, a method for measuring the particle size distribution of toner particles will be described.
As an apparatus for measuring the particle size distribution of toner particles by the Coulter counter method, there are Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.
First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an aqueous electrolytic solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using first grade sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. Volume distribution and number distribution are calculated. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. FIG. 3 is a diagram schematically illustrating the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) 2 / AREA} × (100π / 4) Formula (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.
The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) 2 / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.
Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.
When the shape of the toner is close to a sphere, the contact state between the toners becomes a point contact, so that the adsorbing force between the toners is weakened.
Further, since the contact state between the toner and the photoconductor 1 is point contact, the attractive force between the toner and the photoconductor 1 is also weakened, and the transfer rate is increased, which contributes to high image quality. Further, the cleaning member 7 which is a transparent electrode can be easily thinned, and the thinning of the layer makes the irradiation of the toner with light and contact with the electrode uniform, thereby enabling stable charge injection. On the other hand, if any of the shape factors SF-1 and SF-2 exceeds 180, the fluidity is deteriorated, and the agent circulation property and the replenishment toner diffusibility are poor. Further, the transfer rate is lowered, the thinning is not stable, and the charge injection becomes unstable, which is not preferable.

In the toner of the present invention, fine particles (hereinafter, simply referred to as fine particles) having an average primary particle diameter of 50 to 500 nm and a bulk density of 0.3 mg / cm ³ or more are adhered to the toner particle surface. In addition, although silica etc. are often used for a normal fluid improvement agent, for example, the average primary particle diameter of this silica is 10-30 nm normally, and a bulk density is 0.1-0.2 mg / cm < ³ >. In the present invention, since fine particles having appropriate characteristics are present on the surface of the toner, an appropriate gap is formed between the toner particles and the object. Further, the fine particles have a very small contact area with the toner particles, the photosensitive member 1, the conveyance belt, and the like, so that the adhesion force is greatly reduced, and the toner of the unfixed image facing the conveyance belt is applied to the conveyance belt. There is little disturbance of the image because it is hard to adhere. In addition, since the development / transfer efficiency is improved and the dot reproducibility is improved, the image is stabilized and a margin is increased against disturbance during conveyance. Furthermore, since it plays the role of a roller, thinning of the transparent electrode part is facilitated and the thinning of the layer makes it possible to uniformly irradiate the toner with the light and contact with the electrode, thereby enabling stable charge injection. . In addition, since it is difficult to embed in the toner particles, or can be detached and restored even if it is slightly buried, stable characteristics can be obtained over a long period of time. Since these characteristics have an effect of reducing the share received by the toner particles, the filming effect of the toner itself due to the low rheological component contained in the toner is exhibited for high-speed fixing (low energy fixing). Further, although the details are not clear, even if the surface-treated fine particles are externally added to the toner or the carrier is contaminated, the degree of developer deterioration is small. Therefore, since the change in the fluidity and charging property of the toner is small over time, the developer circulation and the replenishment toner diffusion can be stably performed over a long period of time. Also, the stability of image quality is increased.

The average primary particle size (hereinafter referred to as the average particle size) of the fine particles is 50 to 500 nm, and particularly preferably 100 to 400 nm. If the thickness is less than 50 nm, the fine particles may be buried in the concave and convex portions on the toner surface to lower the role of the rollers. On the other hand, if the thickness is larger than 500 nm , the order of the contact area of the toner itself is on the same level, and the effect of the roller on the toner is reduced. When the bulk density is less than 0.3 mg / cm ³ , although there is a contribution to the improvement of fluidity, the scattering properties and adhesion of the toner and fine particles are increased, so that the effects and functions of the toner and roller are reduced. .
In the fine particles of the present invention, the inorganic compounds include SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , BaO, CaO, K ₂ O, Na ₂ O. , ZrO ₂ , CaO · SiO ₂ , K ₂ O (TiO ₂ ) n, Al ₂ O ₃ · 2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO _{3 and the} like, preferably , SiO ₂ , TiO ₂ , and Al ₂ O ₃ . In particular, these inorganic compounds may be hydrophobized with various coupling agents, hexamethyldisilazane, dimethyldichlorosilane, octyltrimethoxysilane, and the like.

The organic compound fine particles may be a thermoplastic resin or a thermosetting resin. For example, vinyl resin, polyurethane resin, epoxy resin, polyester resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, Examples include urea resins, aniline resins, ionomer resins, and polycarbonate resins. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.
Specific examples of vinyl resins include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid. -Acrylic ester copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, and the like.
Bulk density (g / cm ³ ) = fine particle amount (g / 100 ml) ÷ 100
The fine particles of the present invention can be externally added and adhered to the toner surface by mechanically mixing and adhering the toner base particles and fine particles using various known mixing devices, or in the liquid phase. There is a method in which the base particles and the fine particles are uniformly dispersed with a surfactant or the like, and are dried after the adhesion treatment.

Embodiments according to the present invention will be described first in detail, and operation will be described in detail later with reference to the drawings. FIG. 4 is a schematic diagram showing the configuration of the image forming apparatus according to the embodiment of the present invention.
In the image forming apparatus main body shown in FIG. 4, an image carrier unit having an image carrier belt 10 that moves endlessly in the direction of the arrow is provided. Four image forming units 1 </ b> Y, 1 </ b> C, 1 </ b> M, and 1 </ b> K are disposed on the lower tension surface of the image carrying belt 10. Y, C, M, and K along the numbers of the image forming units correspond to the colors of the toners to be handled. Y represents yellow, C represents cyan, M represents magenta, and K represents black. . 14Y, 14C, 14M, and 14K transfer rollers are provided inside the image carrying belt 10 so as to face the photoreceptor 1 that rotates with the image carrying belt 10 and is provided in the image forming unit. Note that the photoreceptors 1Y to 1K are arranged at the same interval, and at least at the time of image formation, are in contact with a part of the stretched portion with the image carrier belt 10, respectively.
In FIG. 1, during operation of the image forming apparatus, charging as a charging means is performed around a cylindrical photosensitive member 1 rotatably supported by a driving source (not shown) so as to rotate in the direction of an arrow according to an electrophotographic process. A transfer roller 14 is disposed via an image forming member such as a roller 3, a developing device 5, a cleaning member 7 that is a transparent electrode, a light source 6, and an image carrying belt 10.
The photoreceptor 1 is obtained by forming an organic photosensitive layer (OPC), which is a photoconductive substance, on an aluminum cylinder surface having a diameter of about 30 to 120 mm. A photoreceptor 1 on which an amorphous silicon (a-Si) layer is formed can also be used. A belt-like photoreceptor 1 can also be employed. The collection brush 2 collects toner remaining on the surface of the photoreceptor.

Although not shown (only arrows), the exposure apparatus scans the surface of each photoreceptor 1 that has been uniformly charged by the charging roller 3 with light corresponding to image data for each color, and forms an electrostatic latent image. . The exposure apparatus uses a laser beam and a polygon mirror, and can adopt a laser scanning method using a beam light modulated in accordance with image data to be formed, or an LED (light emitting diode) array and an imaging element method as light emitting elements.
In addition to the roller charging system, a charging system that does not contact the photoconductor 1 can also be used as the charging means.
The development in this embodiment is a development system that employs a two-component developer composed of toner and carrier. The electrostatic latent image for each color formed on the surface of each photosensitive member 1 by a laser beam with respect to the negatively charged photosensitive member 1 is developed with toner of a predetermined color having the same polarity (negative polarity) as the charged polarity of the photosensitive member. Then, reversal development that becomes a visible image is performed. A detailed description of the configuration of the developing device 5 will be omitted. An image bearing belt 10 that is supported by a plurality of rollers 11, 12, and 13 and runs in the direction of the arrow is provided on the top of the photoreceptors 1Y, 1C, 1M, and 1K. The image bearing belt 10 is endless and is stretched and arranged so that a part of each photoconductor after the developing process comes into contact. Further, primary transfer rollers 14Y, 14C, 14M, and 14K are provided on the inner peripheral portion of the image bearing belt 10 so as to face the photoreceptors 1Y, 1C, 1M, and 1K.

A cleaning device 15 is provided on the outer periphery of the image bearing belt 10 at a position facing the roller 11. The cleaning device 15 wipes off unnecessary toner remaining on the surface of the image carrying belt 10 and foreign matters such as paper dust. The members related to the image carrier belt 10 are integrally configured as an image carrier unit and can be attached to and detached from the image forming apparatus.
Further, a secondary transfer roller 16 is provided on the outer periphery of the image bearing belt 10 in the vicinity of the support roller 13. By applying a bias to the secondary transfer roller 16 while passing a recording medium (hereinafter referred to as paper P) between the image carrying belt 10 and the secondary transfer roller 16, a toner image carried by the image carrying belt 10 is applied to the paper P. Transcribed. The polarity of the transfer current applied to the transfer roller 16 is a positive polarity opposite to the polarity of the toner.

Under the image forming apparatus, a paper feeding device 20 that stores paper so as to be fed is provided, and only one sheet is reliably sent to the registration roller 22 by the conveying roller 21. Further, the sheet that has passed the transfer roller 16 is conveyed to a fixing device 23 provided downstream in the conveyance direction of the recording medium.
As the fixing device 23 having the heating means, a type having a heater inside the roller, a belt fixing device for running a heated belt, a fixing device adopting induction heating as a heating method, or the like can be adopted. The fixing device is controlled by control means (not shown) so as to control fixing conditions based on full-color and monochrome images, single-sided or double-sided, and optimal fixing conditions according to the type of paper. The paper after fixing is discharged and stacked by a paper discharge roller 24 on a paper discharge stack unit provided at the top of the image forming apparatus.
The toner cartridges 31Y, 31C, 31M, and 31K for each color in which unused toner is stored are detachably stored in the space above the additional carrier. Toner is supplied to each developing device as necessary by toner conveying means such as a mono pump or air pump (not shown). The toner cartridge 31K for black toner that is highly consumed can be set to have a particularly large capacity.

An operation for forming a full-color image in the above configuration will be described.
In the present embodiment, when the image carried on the image carrying belt 10 is transferred to a sheet due to the configuration of the image forming apparatus, even if the data to be recorded is a plurality of pages, the pages are aligned on the paper discharge stack unit. An image is formed on the lower surface of the paper.
When the image forming apparatus is operated, the photoreceptors 1Y, 1C, 1M, and 1K in the image bearing belt 10 image forming unit rotate. First, the image forming unit starts image formation. By the operation of the laser and polygon mirror driven exposure device, light corresponding to image data for yellow is irradiated onto the surface of the photoreceptor 1Y uniformly charged by the charging roller 3 to form an electrostatic latent image.
The electrostatic latent image is developed with yellow toner by the developing roller 5a, becomes a visible image, and is electrostatically primary on the image carrying belt 10 that moves in synchronization with the photoreceptor 1Y by the transfer action of the primary transfer roller 14Y. Transcribed. Such latent image formation, development, and primary transfer operations are sequentially performed in the same manner on the photosensitive members 1C, 1M, and 1K.
As a result, yellow, cyan, magenta, and black color toner images are carried on the image carrying belt 10 as sequentially overlapping full color toner images, and are moved in the direction of the arrow together with the image carrying belt 10. At the same time, the paper P used for recording is fed out from the paper feeding cassette in the paper feeding device 20 by the paper feeding roller 21 for feeding it and conveyed. The leading edge of the sheet takes the timing of the registration roller 22 and the registration roller 22 rotates to convey the sheet to the transfer area.

The full-color toner image on the image carrying belt 10 is transferred to the upper surface of the paper P conveyed in synchronization with the image carrying belt 10 by receiving a transfer action by the secondary transfer roller 16. The bias applied to the secondary transfer roller 16 has a positive polarity opposite to the charging polarity of the toner. The secondary transfer can be performed by applying a bias having the same polarity as the toner to the roller 13.
Thereafter, the surface of the image carrying belt 10 is cleaned by the belt cleaning device 15. In addition, the toner remaining on the surfaces of the photoreceptors 1Y, 1C, 1M, and 1K in the image forming unit that has finished the primary transfer is irradiated from the light source 6 through the transparent electrode and the reverse polarity bias applied from the transparent electrode 7. It is removed from the surface of each photoconductor 1 by a collection brush 2 that receives light and injects charge and is applied with a bias having a polarity opposite to that of the injected charge. The toner collected on the collection brush is discharged onto the photosensitive member 1 by applying a reverse bias to the collection to the brush at a fixed timing after the completion of image formation, and is collected on the developing device 5 through the charging roller 3. And reused. At this time, it is desirable that the charging roller 3 is separated from the photoreceptor 1.

  The paper P on which the toner image that has been superposed and carried on the image carrying belt 10 is transferred is transferred to the fixing device 23. The toners of the respective colors superimposed on the paper P are subjected to a fixing action by the heat of the fixing device 23, and are melted and mixed to completely form a color image. In some cases, the control unit optimally controls the power used by the fixing device in accordance with the image. Until the fixed toner is completely fixed on the paper, it may be rubbed against the guide member or the like on the conveyance path, and the image may be lost or distorted. Thereafter, the paper is discharged by the paper discharge roller 24 onto the paper discharge stack portion with the image surface facing downward. In the paper discharge stack unit, the recorded matter of the subsequent pages is stacked so as to be sequentially stacked on top, so that the page order is aligned.

  For the toner charge amount distribution measurement in this example, an E-Spart analyzer manufactured by Hosokawa Micron Corporation was used. The measurement principle is that the toner particles are vibrated by dropping the toner particles between two electrodes having opposite polarities for acoustic vibration, and the toner particles are moved to the electrodes by the electric field action of the electrodes. The particle diameter and charge amount of each particle are calculated by simultaneously measuring the frequency and moving distance of the toner by the laser Doppler method. According to this apparatus, it is possible to measure the charge amount distribution of particle groups in a specific particle diameter range, and to easily measure the total charge amount of these particle groups.

FIG. 3 is a schematic diagram illustrating a configuration around a photoconductor in an embodiment of the present invention. FIG. 6 is a diagram for explaining a force received by a toner depending on a charge amount of the toner. FIG. 6 is a diagram schematically illustrating the shape of a toner in order to explain the shape factor SF-1 and the shape factor SF-2. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

1 photoreceptor 3 charged low-La
5 Developing device 5a Developing roller 6 Light source 7 Cleaning member 8 Conveying screw 14 Transfer roller

Claims (10)

An electrostatic latent image forming means for forming an electrostatic latent image;
Developing means for developing the electrostatic latent image with toner to form a toner image;
Transfer means for transferring the toner image to an image carrier;
An image forming apparatus comprising at least one image forming unit comprising cleaning means for cleaning transfer residual toner remaining without being transferred to the image carrier,
An electrode for applying a voltage or grounding to contact with the transfer residual toner ;
Simultaneously with contacting the electrode to the transfer residual toner, Bei give a light irradiating means for irradiating light to the transfer residual toner,
The electrode is a conductive member capable of transmitting light at least partially, and also serves as a cleaning means,
The image forming apparatus according to claim 1, wherein the light irradiating unit irradiates light from a side opposite to a toner contact surface of the electrode and transmits the light through the electrode . The image forming apparatus according to claim 1.
The image forming apparatus, wherein the potential applied to the electrode is positive. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the potential applied to the electrode is negative. The image forming apparatus according to claim 1,
The image forming apparatus , wherein the toner contains a photoconductive material or a photocharge control material whose conductivity is changed by light . The image forming apparatus according to claim 1,
An image forming apparatus comprising: a light control unit that controls at least one of a light emission amount, a light emission wavelength, and a light emission frequency of the light irradiation unit according to a toner amount and a charge amount applied to the toner. . The image forming apparatus according to claim 1,
An image forming apparatus comprising voltage control means for controlling a voltage applied to the electrode in accordance with a toner amount and a charge amount applied to the toner . The image forming apparatus according to claim 6 .
The image forming apparatus, wherein the light control unit and / or the voltage control unit further detects and controls an environmental condition (temperature and humidity) around the image carrier . The image forming apparatus according to claim 1,
The toner has a volume average particle size of 4 to 10 μm, and a ratio (D4 / D1) of the volume average particle size (D4) to the number average particle size (D1) is in the range of 1.00 to 1.40. An image forming apparatus. The image forming apparatus according to claim 1,
The image forming apparatus , wherein the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180 . The image forming apparatus according to claim 1,
The toner is obtained by externally adding fine particles having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 mg / cm ³ or more to the surface of toner base particles. .