JP4708852B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device used in an image forming apparatus such as a laser printer, a copying machine, and a facsimile using an electrophotographic system and an electrostatic recording system, and the image forming apparatus.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, an electrostatic image (latent image) is obtained by exposing a fully charged electrophotographic photosensitive member (photosensitive member) with an optical writing unit such as a laser. Form. Thereafter, the developer carrying member in the developing device causes the electrostatic image to be visualized by attaching the developer to the electrostatic image. Then, the developer attached to the photoreceptor is transferred to a recording medium such as paper to form an output image.

  Development methods for converting an electrostatic image into a toner image are roughly classified into a one-component development method and a two-component development method. In the one-component development method, a one-component developer substantially consisting only of resin toner particles (toner) is used as a developer. On the other hand, in the two-component development method, a two-component developer mainly including resin toner particles (toner) and magnetic carrier particles (carrier) is used. In both the one-component developer and the two-component developer, an external additive (auxiliary particle) may be added to the toner particles in order to stabilize the chargeability of the toner or adjust the fluidity.

  As a one-component development method, for example, the following dry one-component contact development method has been proposed and put into practical use. This method uses a non-magnetic one-component developer as a developer. Then, an electrostatic image is developed by pressing or contacting the developer carrying member carrying the developer and transporting it to the photoconductor against the rotating photoconductor. Alternatively, there is a non-contact development method in which development is performed in a state where the developer carrying member is not in contact with the photosensitive member.

  The developing method using a non-magnetic one-component developer does not require a magnetic material for the developer, and simplification and miniaturization of the apparatus are easy. In addition, the developing method using a non-magnetic one-component developer has many advantages such as easy application to a full-color image forming apparatus because of good color.

  In a developing device using a non-magnetic one-component developer, toner cannot be supplied to the developer carrying member by magnetic force, so that other means for supplying toner to the developer carrying member is required.

  Generally, in a developing device using a non-magnetic one-component developer, toner in the developing device is provided by a supply / recovery roller as a developer supply / recovery member arranged in contact with a developing roller as a developer carrier. Is supplied to the developing roller. The toner supplied to the developing roller is made into a thin layer on the developing roller by a regulating blade as a developer amount regulating means disposed in contact with the developing roller. After the developing operation for attaching the toner to the electrostatic image on the photosensitive member from the developing roller is completed, the toner that has not been used for the development is peeled off from the developing roller by the supply and recovery roller. The toner thus peeled off is accommodated in the developing device and used again as a developer.

  In the case of the general configuration as described above, the developing roller and the supply / recovery roller are in contact with each other, and friction on the contact surface is large. Therefore, a large torque is required for rotation of the developing roller and the supply / recovery roller, and power consumption is increased. Further, since the developer rubs strongly at the contact surface between the developing roller and the supply / recovery roller, the toner easily deteriorates. Further, toner remaining on the developing roller after completion of the developing process (that is, after passing through the contact portion or the facing portion with the photosensitive member) comes into contact with the supply and recovery roller, thereby disturbing the toner layer. This causes a so-called ground fog or shading unevenness in which toner is supplied to the non-image area.

  Therefore, as a means for supplying toner to the developer carrying member, a method using a supply roller as a developer conveying member that is not in contact with the developer carrying member has been proposed (see Patent Document 1). In such a developing device, since the developer carrying member such as the developing roller and the supply roller are not in contact with each other, their driving torque is small and the toner is hardly deteriorated. In addition, since the toner layer is not disturbed, it has a certain effect on measures against ground fog and shading unevenness.

However, when a conventional developer having a low degree of sphericity and a high degree of unevenness is used, in the configuration in which the developer carrier and the supply roller are not in contact as described above, the toner is not sufficiently conveyed by the supply roller. The amount of toner supplied to the developer carrying member was not sufficient. Therefore, since the amount of toner used for development is not sufficient, when an image having a large image area is developed, the image quality may be deteriorated due to a decrease in image density, white spots, or uneven density.
JP-A-63-48576

  An object of the present invention is to provide a developing device having improved developer supply capability to a developer carrying member, and an image forming apparatus including the developing device.

  One of the more detailed objects of the present invention is that the developer carrying member and the developer conveying member for supplying the developer onto the developer carrying member are not in contact with each other, and the developer carrying member and the developer While reducing the driving torque of the conveying member, reducing the deterioration of the developer, and suppressing the disturbance of the developer to suppress image defects such as ground fog and shading unevenness, the image area An object of the present invention is to provide a developing device capable of suppressing the occurrence of image defects such as a decrease in image density, white spots, density unevenness, and the like and an image forming apparatus provided with the same even when developing an image with a large amount of image.

The above object is achieved by the developing device and the image forming apparatus according to the present invention. In summary, according to the present invention, a rotatable developer carrier and a developer carrier are arranged so as to face each other in a non-contact manner , and a surface movement direction of the developer carrier is opposite to the developer carrier. A developer transporting member rotatable so as to be in a direction opposite to the surface moving direction, and a container in which the developer carrying member and the developer transporting member are disposed and containing a non-magnetic one-component developer. Part of the developer carrier is exposed to the outside of the container through an opening provided in the container, and the developer carrier is carried on the developer carrier by rotating the developer carrier. In the developing device in which the developer is transported from the opening to the outside of the container and transported from the opening to the inside of the container ; from the closest position between the developer carrier and the developer transport member The surface of the developer carrier Upstream, installed between the developer carrier and the developer transport member, abuts against the developer carrier, and rotates the developer carrier so that the developer carrier is rotated from the opening to the inside of the container. A scraping wall member for scraping the developer transported from the developer carrying member; and a support member for supporting the scraping wall member, one of the directions along the surface moving direction of the developer carrying member The scraping wall member is attached to the end portion side, the other end portion is connected to the container, and the tip end portion on the one end side to which the scraping wall member is attached is the developer transport So that the developer scraped from the developer carrier by the scraping wall member passes upstream of the scraping wall member in the surface movement direction of the developer carrier. A hole is provided through the support member. A developer supply unit that holds the developer blocked by the scraping wall member and the support member at a facing portion between the developer carrier and the developer transport member. And the developer transport member is rotated, so that the developer is transported to the developer supply unit, pressed against the developer carrier and supplied onto the developer carrier, and the scraping is performed. The developer scraped from the developer carrier by the wall member and passed through the hole of the support member is conveyed in a direction away from the developer carrier, and the developer has a shape factor SF representing a spherical degree. The developing device is characterized in that the value of -1 is 100 to 115 and the value of the shape factor SF-2 representing the degree of unevenness is 100 to 110 .

According to another aspect of the present invention, in an image forming apparatus that forms and outputs an image of a developer on a transfer material, an image carrier on which an electrostatic image is formed, and the electrostatic image is carried on the developer carrier. An image forming apparatus comprising: the developing device of the present invention for developing with a non-magnetic one-component developer conveyed in this manner.

  According to the present invention, the developer supply capability to the developer carrier is improved. As one of the functions and effects obtained by the present invention, the developer carrying member and the developer conveying member for supplying the developer onto the developer carrying member are not in contact with each other, and the developer carrying member and the developer While reducing the driving torque of the conveying member, reducing the deterioration of the developer, and suppressing the disturbance of the developer to suppress image defects such as ground fog and shading unevenness, the image area Even when an image with a large amount of image is developed, it is possible to suppress the occurrence of image defects such as a decrease in image density, white spots, and uneven density.

  Hereinafter, the developing device and the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
[Image forming apparatus]
First, an overall configuration and operation of an image forming apparatus including a developing device configured according to the present invention will be described with reference to FIG. In this embodiment, the image forming apparatus 100 transfers using an electrophotographic method in accordance with an image information signal from a personal computer, a document reading apparatus, or the like that is communicably connected to the image forming apparatus main body (apparatus main body). This is a laser beam printer that forms and outputs an image on a material (recording paper, OHP sheet, cloth, etc.). The image forming apparatus 100 according to the present exemplary embodiment includes a developing device 1 that uses a non-magnetic one-component developer (toner).

  The image forming apparatus 100 includes a drum-type photosensitive member, that is, a photosensitive drum 21 as an image carrier. The photosensitive drum 21 is driven to rotate in the direction of arrow a. The surface of the rotating photosensitive drum 21 is charged to a predetermined polarity (negative polarity in this embodiment) and potential by a charging roller 22 as charging means. The surface of the charged photosensitive drum 21 is scanned and exposed in accordance with an image information signal by a laser scanner 23 as an exposure means (optical writing unit). Thereby, an electrostatic image is formed on the photosensitive drum 21. The electrostatic image formed on the photosensitive drum 21 is then supplied with developer toner by the developing device 1 and visualized as a visible image, that is, a toner image.

  On the other hand, in synchronism with the formation of the toner image on the photosensitive drum 21, the transfer material N from the transfer material supply unit (not shown) is transferred to the transfer unit N where the photosensitive drum 21 and the transfer roller 24 as the transfer unit face each other. The transfer material P is conveyed. The toner image on the photosensitive drum 21 is transferred onto the transfer material P by the action of the transfer roller 24. At this time, a bias having a polarity opposite to the normal charging polarity (negative polarity in this embodiment) of the toner is applied to the transfer roller 24 from a transfer bias output unit (not shown).

  The transfer material P onto which the toner image has been transferred is then conveyed to a fixing device (not shown) as fixing means. The toner on the transfer material P is fixed to the transfer material P by being heated and pressed by a fixing device. Thereafter, the transfer material P is discharged out of the apparatus main body.

  The toner remaining on the photosensitive drum 21 after the transfer of the toner image is removed by a cleaning blade 25 as a cleaning unit and collected in a waste toner container (not shown).

[Developer]
FIG. 1 shows a schematic cross section of the developing device 1 in this embodiment. In this embodiment, the developing device 1 uses a non-magnetic one-component developer, that is, toner A as a developer. The developing device 1 includes a container (developing container frame) 2. In the container 2, the space behind the developer carrier 4A described later is divided into two spaces via a partition 2d extending upward from the bottom plate of the container 2. That is, the inside of the container 2 is divided into a buffer space (development chamber) 2b located at the rear of the developer carrier 4A and a replenishment chamber 2a at the rear thereof. Developing means such as a developer carrier 4A is disposed in the buffer space 2b. In the replenishing chamber 2a, toner A to be supplied to the buffer space 2b is stored. In the replenishing chamber 2a, a stirring blade 3 as a developer stirring and conveying member is disposed. The replenishing chamber 2a and the buffer space 2b communicate with each other through a toner transport opening 2c. The stirring blade 3 is rotationally driven in the direction of the arrow d, and supplies the toner A in the replenishing chamber 2a to the buffer space 2b.

  A portion of the buffer space 2b of the container 2 facing the photosensitive drum 1 is partially open, and a belt sleeve 4A as a developer carrier is disposed so as to be partially exposed from the opening 2e. The belt sleeve 4 </ b> A is a thin-film cylindrical body having minute irregularities on the outer peripheral portion, has a circumferential length slightly longer than the circumferential length of the rotating body 10, and is externally mounted on the rotating body 10. As the belt sleeve 4A, a conductive metal belt (sleeve) such as aluminum can be suitably used. As the rotator 10, a rubber roller can be suitably used. The belt sleeve 4 </ b> A is a pressing member (not shown) located on both ends, and the opposite side of the photosensitive drum 21 is in close contact with the outer peripheral surface of the rotating body 10. As a result, the swelling of the belt sleeve 4 </ b> A formed at the portion facing the photosensitive drum 21 comes into surface contact with the outer peripheral surface of the photosensitive drum 21. The belt sleeve 4A rotates in the arrow b direction together with the rotating body 10. That is, the belt sleeve 4 </ b> A and the photosensitive drum 21 rotate so that the respective surface movement directions are in the forward direction at the contact portion.

  Furthermore, a supply roller 5, a developing blade 6, a scraping member 7, and an elastic member 8 are disposed around the belt sleeve 4A in the buffer space 2b.

  A supply roller 5 as a developer conveying member for supplying toner to the belt sleeve 4A is disposed to face the belt sleeve 4A in a non-contact manner. The supply roller 5 is rotationally driven in the direction of arrow c. That is, the belt sleeve 4 </ b> A and the supply roller 5 rotate so that the respective surface movement directions are opposite to each other at the facing portion. As the supply roller 5, a metal roller such as an aluminum rod having minute irregularities on the outer peripheral portion can be suitably used. The supply roller 5 can supply toner over a range equal to or greater than the development area in the direction intersecting the surface movement direction of the belt sleeve 4A.

  The tip of a scraping member 7 attached to a holding member 9 provided on the bottom plate of the container 2 is in pressure contact with the outer peripheral portion of the supply roller 5. As the scraping member 7, a plate-like elastic body such as a polyethylene terephthalate film can be suitably used. In this embodiment, the scraping member 7 has a free end directed upstream of the supply roller 5 in the surface movement direction, and abuts the supply roller 5 at the end. In the present embodiment, the scraping member 7 is installed in the developing device 1 and has a length that extends over substantially the entire toner carrying area on the supply roller 5 in substantially parallel to the axial direction of the supply roller 5. Have

  The elastic member 8 is located downstream of the developing region for supplying toner from the belt sleeve 4A to the photosensitive drum 21 and upstream of the closest position between the belt sleeve 4A and the supply roller 5 in the surface movement direction of the belt sleeve 4A. Arranged in contact with the sleeve 4A. The elastic member 8 is attached to a holding member 9 provided on the bottom plate of the container 2. In this embodiment, the elastic member 8 functions as a seal member so that toner does not leak from the container 2. As the elastic member 8, a foamed elastic member can be suitably used. In this example, a continuous foaming polyurethane foam having a rectangular cross section was used as the elastic member 8. The material of the elastic member 8 is not limited to urethane foam, and a material obtained by foaming general rubber such as silicone rubber or ethylene propylene diene rubber (EPDM rubber) may be used. Further, the foamed elastic member is not limited to a continuous foaming member, and an independent foaming member can also be used. The elastic member 8 has a length that extends over substantially the entire toner carrying area on the belt sleeve 4A in a direction intersecting the surface movement direction of the belt sleeve 4A in a state where it is installed in the developing device 1.

  A developing blade 6 as a developer amount regulating means for regulating the toner amount on the belt sleeve 4A is attached to a holding member 11 provided on the ceiling portion of the container 2, and one side surface is an outer peripheral portion of the belt sleeve 4A. Abuts on the surface. The developing blade 6 is in contact with the belt sleeve 4A at a position downstream of the closest position between the belt sleeve 4A and the supply roller 5 (that is, downstream of the elastic member 8) in the surface movement direction of the belt sleeve 4A. As the developing blade 6, a metal thin plate such as stainless steel or phosphor bronze, which is a plate-like elastic body, can be suitably used.

  As will be described in detail later, in this embodiment, as the developer, the value of the shape factor SF-1 representing the degree of sphericity is 100 to 135, and the value of the shape factor SF-2 representing the degree of unevenness is 100 to 120. Toner A is contained in the container 2.

  The toner A in the replenishing chamber 2a is supplied to the buffer space 2b by the rotation of the stirring blade 3 in the arrow d direction. In the buffer space 2b, the rotation of the supply roller 5 in the direction of the arrow c causes the toner A that contacts the outer peripheral surface to be charged by friction and electrostatically held on the outer peripheral surface of the supply roller 5. The toner A on the supply roller 5 is scraped off by the scraping member 7. Thereby, the toner A is a space between the supply roller 5 and the belt sleeve 4A, more specifically, a space surrounded by the supply roller 5, the belt sleeve 4A, the elastic member 8, and the scraping member 7. Are introduced and gathered in the developer supply section X, and the powder pressure of the toner A is increased. In the developer supply part X, the toner A is held between the belt sleeve 4 </ b> A and the supply roller 5. The toner A is supplied to the belt sleeve 4A by the powder pressure and the rotation of the belt sleeve 4A in the direction of arrow b. The toner A held on the belt sleeve 4A is regulated by the developing blade 6 and forms a thin layer on the belt sleeve 4A. The toner A is charged by contact with the developing blade 6.

  The toner A that has passed through the developing blade 6 moves in the direction of arrow b together with the belt sleeve 4A, and in the contact area (development area) between the photosensitive drum 21 and the belt sleeve 4A, the toner A moving in the direction of arrow a. Contact the outer peripheral surface. At this time, a developing bias voltage output by a developing bias output means (not shown) is applied to the belt sleeve 4A. By the action of this voltage, the toner A moves from the belt sleeve 4 </ b> A to the photosensitive drum 21 in accordance with the electrostatic image formed on the photosensitive drum 21. Thereby, the electrostatic image on the photosensitive drum 21 is visualized. In this embodiment, toner charged to the same polarity (negative polarity in this embodiment) as the charging polarity of the photosensitive drum 21 is attached to a portion (bright portion) where the charged charge on the photosensitive drum 21 is attenuated by exposure.

  The toner A that has not been used for developing the electrostatic image and has passed through the developing region while adhering to the belt sleeve 4A passes through the contact portion between the elastic member 8 and the belt sleeve 4A together with the belt sleeve 4A, and then the buffer space 2b. To be reused.

  Here, the sphericity of the toner will be described. The degree of sphericity of the toner can be indicated by using toner particle shape factors SF-1 and SF-2. In the present invention, 100 toner images are randomly sampled using a scanning electron microscope FE-SEM (S-800) manufactured by Hitachi, Ltd. The image information is introduced into an image analysis apparatus (Luzex 3) manufactured by Nireco through an interface, analyzed, and defined as a value obtained by calculation from the following equation.

SF-1 = {(MXLNG) ² / AREA} × (π / 4) × 100
SF-2 = {(PERI) ² / AREA} × (1 / 4π) × 100
(MXLNG: absolute maximum length, AREA: toner projection area, PERI: circumference)

  The shape factor SF-1 of the toner particles indicates the degree of sphericity. When the shape factor SF-1 is larger than 135, the shape factor SF1 gradually becomes indefinite. Further, the shape factor SF-2 of the toner particles indicates the degree of unevenness, and if it is larger than 120, the unevenness on the surface of the toner particles becomes remarkable. In a perfect sphere, SF-1 = SF-2 = 100.

  Examples of the effects of the toner shape include the following. By making the shape of the toner spherical, the fluidity of the toner is improved, the toner is smoothly supplied from the supply roller 5, and the powder in the space (developer supply part) X between the belt sleeve 4 </ b> A and the supply roller 5. The pressure can be increased. Thereby, the amount of toner supplied to the belt sleeve 4A can be sufficiently increased, and the amount of toner supplied for development increases. Therefore, even when an image having a large image area is developed, it is possible to prevent image defects such as a decrease in image density, white spots, and density unevenness.

  Hereinafter, the effects of the present embodiment will be further described with reference to more specific examples. The following specific examples are provided for purposes of illustration of the invention and are not intended to limit the invention to these examples only.

(Specific example 1)
In this specific example, the following toner A1 which is a polymerized toner is used as the toner A in the developing device 1 of the present embodiment. The production method of the toner A1 is as follows.

In order to produce a polymerized toner, first, an aqueous medium was prepared. 450 g of a 0.1 M Na ₃ PO ₄ aqueous solution was added to 710 g of ion-exchanged water, heated to 60 ° C., and then stirred at 12000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). To this, 68 g of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

Next, a polymerizable monomer composition was prepared.
Monomer: Styrene 165g
n-Butyl acrylate 35g
Colorant: C.I. I. Pigment Blue 15: 3 15g
Charge control agent: Salicylic acid metal compound 3g
Polar resin: 10g of saturated polyester
(Acid value 14, peak molecular weight: 8000)
Mold release agent: Ester wax (melting point 70 ° C.) 50 g

  The raw material by the said prescription was heated at 60 degreeC, and it melt | dissolved and disperse | distributed uniformly at 12000 rpm using TK type | mold homomixer (made by Tokushu Kika Kogyo). 10 g of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved in this to prepare a polymerizable monomer composition.

The polymerizable monomer composition is put into the obtained aqueous medium, and stirred at 10000 rpm for 10 minutes with a TK homomixer in an N ₂ atmosphere at 60 ° C. to obtain a polymerizable monomer composition. Granulated. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and reacted for 10 hours. After completion of the polymerization reaction, the residual monomer was removed under reduced pressure, and after cooling, hydrochloric acid was added to dissolve calcium phosphate. Thereafter, filtration, washing with water and drying were performed to obtain colored suspended particles (polymerized toner particles).

100 parts by weight of the obtained polymer toner particles and 2.2 parts by weight of hydrophobic silica fine powder having a specific surface area of 200 m ² / g by BET method were mixed to prepare toner A1 subjected to external addition treatment. . The obtained toner A1 had a weight average particle diameter of 6.0 μm, a shape factor SF-1 of 115, and a shape factor SF-2 of 110.

  The average particle size and particle size distribution of the toner can be measured by various methods such as a method using a Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co.). Here, the measurement was performed by a method using a Coulter Multisizer (manufactured by Coulter). A Coulter Multisizer (manufactured by Coulter Inc.) was connected to an interface (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) that output number distribution and volume distribution. As the electrolytic solution, 1% NaCl aqueous solution was prepared using first grade sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used.

  As a measurement method, 0.1 to 5 mL of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 mL of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toner particles of 2 μm or more are measured with a Coulter multisizer using a 100 μm aperture as the aperture. Distribution and number distribution are calculated. Then, the volume-based weight average particle diameter obtained from the volume distribution and the number-based length average particle diameter obtained from the number distribution can be obtained.

(Specific example 2)
In this specific example, the following toner A2 which is a polymerized toner is used as the toner A in the developing device 1 of the present embodiment. The production method of the toner A2 is as follows.

First, an aqueous medium was prepared. After adding 450 g of 0.1 M Na ₃ PO ₄ aqueous solution to 710 g of ion-exchanged water and heating to 60 ° C., the mixture was stirred at 12000 rpm using a TK homomixer (manufactured by Special Machine Industries). To this, 68 g of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

Next, a polymerizable monomer composition was prepared.
Monomer: Styrene 165g
n-Butyl acrylate 35g
Colorant: C.I. I. Pigment Blue 15: 3 15g
Charge control agent: Salicylic acid metal compound 3g
Polar resin: 10g of saturated polyester
(Acid value 14, peak molecular weight: 8000)

  The above formulation was heated to 60 ° C., and uniformly dissolved and dispersed at 12000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). Into this, 10 g of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition is put into the obtained aqueous medium, and stirred at 10000 rpm for 10 minutes using a TK homomixer at 60 ° C. in an N ₂ atmosphere. Granulated. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and reacted for 10 hours. After completion of the polymerization reaction, the residual monomer was removed under reduced pressure under the same conditions as for toner A1, and after cooling, hydrochloric acid was added to dissolve the calcium phosphate. Thereafter, filtration, washing with water, and drying were performed to obtain colored suspended particles (polymerized toner particles).

100 parts by weight of the obtained polymer toner particles and 1.5 parts by weight of hydrophobized silica fine powder having a specific surface area of 200 m ² / g by the BET method are mixed, and externally added toner A2 is obtained. Prepared. The obtained toner A2 had a weight average particle size of 5.5 μm, a shape factor SF-1 of 120, and a shape factor SF-2 of 115.

(Comparative Example 1)
As Comparative Example 1, a developing device having the same configuration as that of the developing device 1 of this embodiment except for the toner to be used was prepared. In the developing device of this comparative example, the following toner A3, which is a pulverized toner, was used as the toner A. The production method of the toner A3 is as follows.
Styrene-acrylic resin 100 parts by weight Carbon black 5 parts by weight Low molecular weight ethylene-propylene copolymer 4 parts by weight Negative charge control agent (azo dye-based metal complex) 1 part by weight

  The mixture having the above composition is melt-kneaded with a biaxial extruder heated to 140 ° C., then coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a jet mill to obtain a finely pulverized product (ground toner particles). It was.

100 parts by weight of the pulverized toner particles obtained were mixed with 1.5 parts by weight of hydrophobized silica fine powder having a specific surface area of 200 m ² / g according to the BET method. Prepared. The obtained toner A3 had a weight average particle diameter of 5.0 μm, a shape factor SF-1 of 145, and a shape factor SF-2 of 133.

  The image forming apparatus 100 of the present embodiment is mounted with the developing device 1 of the above specific example 1, the specific example 2, and the comparative example 1, the image output is performed, and the image density reduction is evaluated. The evaluation criteria are shown in Table 1.

  The evaluation results are shown in Table 2.

  The decrease in image density greatly depends on the values of SF-1 and SF-2. If the value of SF-1 is 100 to 135 and the value of SF-2 is 100 to 120, the image density is hardly decreased. Was confirmed.

  As described above, according to this embodiment, the belt sleeve 4A and the supply roller 5 are not in contact with each other. For this reason, torque required to rotate the belt sleeve 4A and the supply roller 5 can be reduced, toner deterioration can be reduced, and image defects such as ground fog and shading unevenness can be suppressed. According to this embodiment, since the toner has a high sphericity and a low unevenness, the toner is smoothly supplied from the supply roller 5 and the space between the belt sleeve 4A and the supply roller 5 (developer supply) Part) The powder pressure in X increases. As a result, the amount of toner used for development increases, so that even when developing an image with a large image area, it is possible to suppress the occurrence of image defects such as a decrease in image density, white spots, and uneven density. it can.

Example 2
Next, another embodiment of the present invention will be described. In this embodiment, the configuration of the developing means such as a developer carrier provided in the developing device is different from that of the first embodiment. Since other configurations of the developing device and the image forming apparatus are substantially the same as those of the first embodiment, elements having substantially the same or corresponding functions and configurations as those of the first embodiment are denoted by the same reference numerals. A detailed description is omitted.

  FIG. 3 shows a schematic cross section of the developing device 1 in this embodiment. The developing device 1 of the present embodiment is not provided with the belt sleeve 4A and the rotating body 10 in the developing device 1 of the first embodiment, but instead is provided with a developing roller 4B as a developer carrier. The developing roller 4B is disposed in contact with the photosensitive drum 21 so as to be partially exposed from the opening 2e of the buffer space 2b, and rotates in the direction of the arrow b in the drawing. That is, the developing roller 4 </ b> B and the photosensitive drum 21 rotate so that the respective surface movement directions are forward at the contact portion. As the developing roller 4B, an elastic roller in which an elastic layer in which minute irregularities are provided in the outer peripheral portion and an electric resistance value is adjusted is formed on the outer periphery of the core metal. As the elastic layer, general rubbers such as silicone rubber, urethane rubber, butyl rubber, epichlorohydrin rubber, nitrile butadiene rubber, and ethylene propylene diene rubber (EPDM) can be used. Further, as the developing roller 4B, the elastic layer itself may be the outermost layer, but the surface layer may be formed of a material different from that of the elastic layer in consideration of the charging property applied to the toner. When a negatively chargeable toner is used, urethane resin, polyamide resin, silicone resin, or the like can be used as the surface layer. When a positively charged toner is used, a fluorine resin or the like can be used as the surface layer.

  Further, the developing device 1 of the present embodiment is not provided with the scraping member 7 in the developing device 1 of the first embodiment, but instead is provided with an elastic member 12 that contacts the developing roller 4B and the supply roller 5. ing. That is, in this embodiment, the elastic member 12 has a first portion 12a that contacts the developing roller 4B and a second portion 12b that contacts the supply roller 5. In the present embodiment, the elastic member 12 functions as a seal and a scraping member. Thereby, the structure of the developing device 1 can be simplified. As the elastic member 12 in the present embodiment, a foamed elastic member similar to the elastic member 8 used in the first embodiment can be suitably used.

  In such a configuration, the toner A held on the supply roller 5 is scraped off by the elastic member 12. As a result, the toner A enters the developer supply section X, which is a space between the supply roller 5 and the developing roller 4B, more specifically, a space surrounded by the supply roller 5, the developing roller 4B, and the elastic member 12. As a result, the toner A powder pressure increases. In the developer supply portion X, the toner A is held between the developing roller 4B and the supply roller 5. The toner A is supplied to the developing roller 4B by the powder pressure and the rotation of the developing roller 4B. In this embodiment, the developing bias voltage output by the developing bias output means (not shown) is applied to the developing roller 4B.

  Hereinafter, the effects of the present embodiment will be further described with reference to more specific examples. The following specific examples are provided for purposes of illustration of the invention and are not intended to limit the invention to these examples only.

(Specific example 3)
In this specific example, the above-described toner A1 which is a polymerized toner is used as the toner A in the developing device 1 of the present embodiment.

(Comparative Example 2)
As Comparative Example 2, a developing device having the same configuration as that of the developing device 1 of this embodiment except for the toner to be used was prepared. In the developing device of this comparative example, the toner A3 described above, which is a pulverized toner, was used as the toner A.

  The image forming apparatus 100 of the present embodiment was equipped with the developing devices 1 of the specific example 3 and the comparative example 2, and the image was output, and the image density reduction was evaluated. Evaluation criteria are as shown in Example 1. The evaluation results are shown in Table 3.

  Also in the configuration of the present embodiment, as in the first embodiment, the image density reduction greatly depends on the values of SF-1 and SF-2, the value of SF-1 is 100 to 135, and the value of SF-2 Was 100 to 120, it was confirmed that the image density hardly decreased.

  As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained. That is, the developing roller 4B and the supply roller 5 are not in contact with each other. For this reason, torque required to rotate the developing roller 4B and the supply roller 5 can be reduced, toner deterioration can be reduced, and image defects such as ground fog and shading unevenness can be suppressed. According to this embodiment, since the toner has a high sphericity and a low unevenness, the toner is smoothly supplied from the supply roller 5, and the space between the development roller 4 </ b> B and the supply roller 5 (developer supply) Part) The powder pressure in X increases. As a result, the amount of toner used for development increases, so that even when developing an image with a large image area, it is possible to suppress the occurrence of image defects such as a decrease in image density, white spots, and uneven density. it can. Furthermore, in this embodiment, the configuration of the developing device 1 can be simplified by using the elastic member 12 that contacts both the developing roller 4B and the supply roller 5. This is advantageous in reducing the size of the apparatus and reducing the labor and cost of assembly.

Example 3
Next, another embodiment of the present invention will be described. In the present embodiment, the configuration of the developing means such as a developer carrier provided in the developing device is different from those in the first and second embodiments. Since other configurations of the developing device and the image forming apparatus are the same as those of the first and second embodiments, elements having substantially the same or corresponding functions and configurations as those of the first and second embodiments are denoted by the same reference numerals. The detailed explanation is omitted.

  FIG. 4 shows a schematic cross section of the developing device 1 in this embodiment. The developing device 1 of the present embodiment is not provided with the elastic member 12 in the developing device 1 of the second embodiment, but instead is a scraping wall disposed between the developing roller 4B and the supply roller 5. A member 13 is provided. The scraping wall member 13 is supported by the container 2 by a support member 14. The support member 14 is provided with a hole that passes through the support member 14 and allows the toner A to pass therethrough as a collection passage 15 for collecting the toner A scraped by the scraping wall member 13.

  More specifically, in the developing device 1 of the present embodiment, the development roller 4B and the supply roller 5 are more recently located downstream of the developing region in which the toner is supplied from the developing roller 4B to the photosensitive drum 21 in the surface movement direction of the developing roller 4B. A scraping wall member 13 that is provided between the developing roller 4B and the supply roller 5 and at least a part of which contacts the developing roller 4B is provided upstream of the contact position in the surface movement direction of the developing roller 4B. The scraping wall member 13 is not limited to this, but a foamed elastic member can be suitably used. In this example, a continuous foaming polyurethane foam having a rectangular cross section was used as the scraping wall member 13. The scraping wall member 13 can be compressed and disposed between the developing roller 4 </ b> B and the supply roller 5. Further, the scraping wall member 13 can be disposed so as to come into contact with the developing roller 4B at, for example, at least one corner (such as a corner on the upstream side in the surface movement direction of the developing roller 4B). The material of the scraping wall member 13 is not limited to urethane foam. As the foamed elastic member, foamed rubber obtained by foaming silicone rubber, ethylene propylene diene rubber (EPDM rubber), or the like may be used. . Further, the foamed elastic member is not limited to a continuous foaming member, and an independent foaming member can also be used. The scraping wall member 13 has a length extending over substantially the entire toner carrying area on the developing roller 4B substantially parallel to the axial direction of the developing roller 4B in a state of being installed in the developing device 1.

  The scraping wall member 13 is supported by the support member 14. The support member 14 may be a separate member from the container 2 or may be integrally formed. The support member 14 is not limited to this, but a resin film such as a polyethylene terephthalate film which is a plate-like elastic body can be suitably used. The support member 14 is arranged such that its longitudinal direction is along the axial direction of the developing roller 4B. Then, the scraping wall member 13 is attached to one end of the support member 14 in a direction along the surface movement direction of the developing roller 4B (a direction intersecting the axial direction of the developing roller 4). The end portion of the support member 14 on the side where the scraping wall member 13 is installed can be brought into contact with the supply roller 5. The other end of the support member 13 is attached to the container 2 in the direction along the surface movement direction of the developing roller 4B. The shape, size, and number of the collection passage 15 are set so that the toner peeled off from the developing roller 4B does not accumulate on the support member 14.

The toner A in the replenishing chamber 2a is supplied to the buffer space 2b by the rotation of the stirring blade 3 in the arrow d direction. In the buffer space 2b, the rotation of the supply roller 5 in the direction of the arrow c causes the toner A that contacts the outer peripheral surface to be charged by friction and electrostatically held on the outer peripheral surface of the supply roller 5. The toner A on the supply roller 5 is scraped off (blocked) by the scraping wall member 13 . Thereby, the toner A is a developer supply section that is a space between the supply roller 5 and the developing roller 4B, more specifically, a space surrounded by the supply roller 5, the developing roller 4B, and the scraping wall member 13. X gathers and the powder pressure of toner A increases. In the developer supply portion X, the toner A is held between the developing roller 4B and the supply roller 5. The toner A is supplied to the developing roller 4B by the powder pressure and the rotation of the developing roller 4B. The toner A held on the developing roller 4B is regulated by the developing blade 6 and forms a thin layer on the developing roller 4B. The toner A is charged by contact with the developing blade 6.

  The toner A that has passed through the developing blade 6 moves in the direction of the arrow b together with the developing roller 4B, and in the contact area (developing area) between the photosensitive drum 21 and the developing roller 4B, the toner A moving in the direction of the arrow a. Contact the outer peripheral surface. At this time, a developing bias voltage output by a developing bias output means (not shown) is applied to the developing roller 4B. By the action of this voltage, the toner A moves from the developing roller 4B to the photosensitive drum 21 in accordance with the electrostatic image formed on the photosensitive drum 21. Thereby, the electrostatic image on the photosensitive drum 21 is visualized.

  The toner A that has not been used for developing the electrostatic image and has passed through the developing region while adhering to the developing roller 4B moves together with the developing roller 4B and is scraped off by the scraping wall member 13. The toner A scraped off from the developing roller 4B is returned to the buffer space 2b through the collection passage 15 opened in the support member 14 and reused. According to such a configuration, the toner that has not been developed is peeled off from the developing roller 4B, passed through the collection path 15, and conveyed by the supply roller 5 in a direction away from the developing roller 4B. Then, the toner newly conveyed by the supply roller 5 and pushed into the developer supply unit X is supplied to the development roller 4B. As a result, it is possible to reduce the deterioration of the toner due to continuous and repeated use.

  Hereinafter, the effects of the present embodiment will be further described with reference to more specific examples. The following specific examples are provided for purposes of illustration of the invention and are not intended to limit the invention to these examples only.

(Specific example 4)
In this specific example, the above-described toner A1 which is a polymerized toner is used as the toner A in the developing device 1 of the present embodiment.

(Comparative Example 3)
As Comparative Example 3, a developing device having the same configuration as the developing device 1 of the present embodiment except for the toner to be used was prepared. In the developing device of this comparative example, the toner A3 described above, which is a pulverized toner, was used as the toner A.

  The image forming apparatus 100 of the present embodiment was mounted with the developing devices 1 of the specific example 4 and the comparative example 3, and the image was output, and the image density reduction was evaluated. Evaluation criteria are as shown in Example 1. The evaluation results are shown in Table 4.

  Also in the configuration of the present embodiment, as in the first and second embodiments, the image density reduction greatly depends on the values of SF-1 and SF-2, and the value of SF-1 is 100 to 135. It was confirmed that the image density hardly decreased when the value of 100 was 120 to 120.

  As described above, according to this embodiment, the same effects as those of Embodiments 1 and 2 can be obtained, and furthermore, the use of the scraping wall member 13 and the collection passage 14 can reduce the deterioration of the toner. Can be planned.

  As mentioned above, although this invention was demonstrated according to the specific Example, it should be understood that this invention is not limited to the above-mentioned embodiment. For example, in the above-described embodiment, an example in which a spherical toner is manufactured by a polymerization method is shown. When a toner is produced by a polymerization method such as a suspension polymerization method, a spherical toner having a desired shape can be obtained relatively easily without performing a special spheroidizing treatment. However, the present invention is not limited to this, and the toner produced by the pulverization method is subjected to a spheroidizing process by a method of applying a mechanical impact or a method of heating in a hot air stream, and the spherical shape of a desired shape is obtained. Toner can be obtained.

  Further, for example, in each of the above embodiments, the developing device 1 has been described as using a contact developing method in which the image carrier and the developer carrier are in contact with each other. However, the present invention is not limited to this, and can be equally applied to a developing apparatus using a non-contact developing method in which the image carrier and the developer carrier are non-contact.

  Further, the belt sleeve in the first embodiment as the developer carrying member and the developing roller in the second and third embodiments may be used interchangeably.

  In the present invention, a developing device is provided corresponding to each of a plurality of image carriers, or a plurality of developing devices are provided for a single image carrier, for example, to form a full-color image. The present invention can be equally applied to possible color image forming apparatuses. Multiple types (colors) of toner images can be directly superimposed on the image carrier, or can be directly transferred onto the transfer material by sequentially transferring onto the transfer material, or after being superimposed on the intermediate transfer member An image forming apparatus that can output a full-color image or the like by transferring the image to the image is well known in the art.

  Furthermore, the developing device according to the present invention may be a cartridge that can be attached to and detached from the image forming apparatus main body (apparatus main body). As the cartridge, there is a developing cartridge in which a developing device is detachably attached to the apparatus main body. In addition to the developing device, the cartridge includes a process cartridge in which at least the photosensitive member is integrally formed into a cartridge by a frame. The process cartridge may further include at least one of charging means and cleaning means. Such a cartridge that can be attached to and detached from the apparatus main body is detachably mounted on the apparatus main body through mounting means such as a mounting guide and a positioning member provided in the apparatus main body.

1 is a schematic cross-sectional view of an embodiment of a developing device according to the present invention. 1 is a schematic configuration diagram of a main part of an embodiment of an image forming apparatus according to the present invention. It is a schematic sectional drawing of the other Example of the image development apparatus concerning this invention. It is a schematic sectional drawing of the further another Example of the image development apparatus concerning this invention.

Explanation of symbols

1 Developing Device 2 Container (Developing Container Frame)
3 Stirring blade (developer stirring and conveying member)
4A belt sleeve (developer carrier)
4B Development roller (developer carrier)
5 Supply roller (developer transport member)
6 Development blade (developer amount regulation means)
7 Scraping member 8 Elastic member (seal member)
12 Elastic member (seal and scraping member)
13 Scraping wall member 14 Support member 15 Recovery passage 21 Photosensitive drum (image carrier)
100 Image forming apparatus

Claims (6)

The rotatable developer carrying member and the developer carrying member are arranged so as to face each other in a non-contact manner , and the surface moving direction at the portion facing the developer carrying member is opposite to the surface moving direction of the developer carrying member. a rotatable developer carrying member as the developer carrying member and said developer carrying member is disposed, comprises a container a non-magnetic one-component developing agent is accommodated, wherein the developer carrier thereof A part of the developer is exposed to the outside of the container from the opening provided in the container, and when the developer carrier rotates, the developer carried on the developer carrier is released from the opening. In the developing device conveyed outside the container and conveyed from the opening to the inside of the container ,
Installed between the developer carrying member and the developer carrying member upstream of the closest position between the developer carrying member and the developer carrying member in the surface movement direction of the developer carrying member. A scraping wall member that contacts the developer carrier and scrapes the developer transported from the opening to the inside of the container by rotating the developer carrier;
A support member for supporting the scraping wall member, wherein the scraping wall member is attached to one end side in a direction along the surface movement direction of the developer carrying member, and the other end portion is the container. The tip of the one end side to which the scraping wall member is attached is in contact with the developer conveying member, and the surface of the developer carrying member moves more than the scraping wall member A support member provided with a hole penetrating the support member so that the developer scraped from the developer carrying member by the scraping wall member passes on the upstream side in the direction;
Have
A developer supply unit configured to hold the developer blocked by the scraping wall member and the support member at a facing portion between the developer carrier and the developer transport member is configured, and the developer transport member , The developer is transported to the developer supply unit, pressed against the developer carrier and supplied onto the developer carrier, and the developer carrier by the scraping wall member. The developer scraped from and passed through the hole of the support member is conveyed in a direction away from the developer carrier,
The developing device is characterized in that the value of the shape factor SF-1 representing the degree of sphericity is 100 to 115 , and the value of the shape factor SF-2 representing the degree of unevenness is 100 to 110 . The developing device according to claim 1, wherein the support member is formed of a plate-like member . The developing device according to claim 2, wherein the support member is formed of a resin film . The scraping wall member, a developing device according to any one of claims 1 to 3, characterized in that it is formed of a foamed elastic member. The scraping wall member, the placed in compression between the developer carrying member and said developer carrying member, according to claim 4, characterized in that the contact with the developer carrying member at least one corner The developing device according to 1. In an image forming apparatus that forms and outputs an image of a developer on a transfer material, an image carrier on which an electrostatic image is formed, and a non-magnetic one component carried by the electrostatic image carried on the developer carrier an image forming apparatus, comprising a developing device according to any one of claims 1-5 for developing with a developer.

Images