JP5555429B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic printer, a copying machine, a facsimile machine, an image scanner, or a multifunction machine in which various functions thereof are integrated.

  In general, in an electrophotographic image forming apparatus, for example, as described in Patent Document 1 below, a charging process for uniformly charging a photoconductive insulating layer, and then exposing the layer, An exposure process for forming an electrostatic latent image by eliminating charges on the exposed portion, and a developer containing at least a colorant (hereinafter referred to as “toner”) attached to the latent image by a developing device. A development process for visualizing, a transfer process for transferring the obtained visible image to a transfer material such as transfer paper, and a fixing process for fixing by heating, pressure, or other suitable fixing method are executed. .

  In the developing device, toner composed of charged particles is frictionally charged from a toner supply unit (for example, a toner supply roller) to a toner carrier (for example, a development roller).

Japanese Patent Laid-Open No. 10-48940

  However, the conventional image forming apparatus has a problem that when the toner charging performance cannot be matched, the toner is excessively charged due to friction between the toner supply roller and the developing roller, and stains are generated on the image. .

An image forming apparatus according to the present invention includes a rotatable toner carrier that develops a toner composed of charged particles into an electrostatic latent image, and a rotatable toner that supplies the toner to the toner carrier. An image forming apparatus that forms a desired image by supplying the toner from the toner supply unit to the toner carrier, wherein the absolute value of the charge amount in the toner is q [μC / g ], When the peripheral speed of the toner carrier is Vdv [mm / sec] and the peripheral speed of the toner supply means is Vsp [mm / sec] ,
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
And the peripheral velocity Vsp is 100 mm / sec or more and 150 mm / sec or less.
Another image forming apparatus of the present invention includes a rotatable toner carrier that develops toner composed of charged particles into an electrostatic latent image, and a rotatable toner that supplies the toner to the toner carrier. An image forming apparatus for forming a desired image by supplying the toner from the toner supply unit to the toner carrier, and calculating an absolute value of a charge amount in the toner by q [μC / G], the peripheral speed of the toner carrier is Vdv [mm / sec], and the peripheral speed of the toner supply means is Vsp [mm / sec],
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
The filling,
The circularity of the particles in the toner is
Circularity = circumference of a circle having the same area as the particle projection area / perimeter of the particle projection image
= 0.940 to 0.960
It is characterized by being.
Another image forming apparatus of the present invention includes a rotatable toner carrier that develops toner composed of charged particles into an electrostatic latent image, and a rotatable toner that supplies the toner to the toner carrier. An image forming apparatus for forming a desired image by supplying the toner from the toner supply unit to the toner carrier, and calculating an absolute value of a charge amount in the toner by q [μC / G], the peripheral speed of the toner carrier is Vdv [mm / sec], and the peripheral speed of the toner supply means is Vsp [mm / sec],
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
The filling,
The toner carrier is a developing roller, the toner supply means is a supply roller, and the supply roller is a saddle type roller having a center portion larger than an end portion.
Still another image forming apparatus according to the present invention includes a rotatable toner carrier that develops toner composed of charged particles into an electrostatic latent image, and a rotation that supplies the toner to the toner carrier. An image forming apparatus that forms a desired image by supplying the toner from the toner supply unit to the toner carrier, and the absolute value of the charge amount of the toner is q [ μC / g], the peripheral speed of the toner carrier is Vdv [mm / sec], and the peripheral speed of the toner supply means is Vsp [mm / sec],
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
The toner carrier is a developing roller, the toner supply means is a supply roller, and further contacts the developing roller and thins the toner supplied onto the developing roller. The developing blade is a double stack of stainless plates.

According to the image forming apparatus of the present invention, the toner, the toner carrier, and the toner supply unit are set to 30 ≦ q × (Vdv ÷ Vsp) ≦ 120.
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
Since the peripheral speed Vsp is not less than 100 mm / sec and not more than 150 mm / sec, it is possible to obtain good prints without stains and improve print quality.

FIG. 1 is an enlarged view schematically showing the developing device 10 in FIG. 2 in Embodiment 1 of the present invention. FIG. 2 is a configuration diagram showing an outline of the image forming apparatus in Embodiment 1 of the present invention. FIG. 3 is a diagram showing the result of visually confirming the presence or absence of contamination on a continuous image in the image forming apparatus of Example 1 in comparison with the comparative example. FIG. 4 is a diagram illustrating a result of visually confirming the presence or absence of contamination on a continuous image in the image forming apparatus of Example 2 in comparison with the comparative example.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Constitution)
FIG. 2 is a configuration diagram showing an outline of the image forming apparatus in Embodiment 1 of the present invention.

  This image forming apparatus is, for example, an electrophotographic color printer, and has four developing devices 10 (= black (K) 10-1, yellow (Y) 10-2, magenta (M)) for four colors. 10-3, cyan (C)) 10-4), which are provided on the upper part of the printer main body. Each developing device 10 has the same structure except for the toner to be used.

  A recording paper cassette 21 for storing a printing medium (for example, recording paper) 20 is disposed at the bottom of the printer main body. (1), (e), (h), (k), and (m) (1), (e), (h), (k), and (m) a conveyance path of conveyance of the recording paper 20 from the recording paper cassette 21 via the developing device 10 ), (N), (o), (p), (q), a plurality of recording paper transport rollers 22 (= 22-1 to 22-23) are arranged. Under each developing device 10, each transfer roller 24 (= 24-1 to 24-4) is arranged via a transfer belt 23, and the transfer belt 23 is a driven roller 25-1 and a drive roller 25-. 2 to rotate.

  Movable recording paper travel guides 26-1 and 26-2 for switching the transport direction at the time of duplex printing are provided at the transport direction switching location in the transport path of the recording paper 20. In the vicinity of the driven roller 25-1, a cleaning belt 27 for cleaning the transfer belt in contact with the transfer belt 23 is disposed, and a waste developer tank 28 is provided adjacent to the cleaning blade 27. Further, a fixing device 30 for fixing the toner on the recording paper 20 with heat and pressure is disposed on the cyan (C) developing device 10-4 side.

  FIG. 1 is an enlarged view schematically showing the developing device 10 in FIG. 2 in Embodiment 1 of the present invention.

  The developing device 10 includes a toner supply unit (for example, a sponge roller that is a supply roller) 13 that carries the toner 12 that falls from the toner cartridge 11, and contacts the sponge roller 13 to supply the toner 12 supplied from the sponge roller 13. A toner carrier (for example, a developing roller) 14 that develops the electrostatic latent image, a thin layer forming unit (for example, a developing blade) 15 that is in contact with the developing roller 14, and a surface layer that is in contact with the developing roller 15 A latent image carrier (for example, a photosensitive drum as a photosensitive member) 16 that forms an electrostatic latent image on the surface, a charging roller 17 that contacts and charges the photosensitive drum 16, and the photosensitive drum 11, and is transferred. A cleaning blade 18 is used to scrape off the remaining toner 12 from the photosensitive drum 16. In addition, a light emitting diode (hereinafter referred to as “LED”) head 19 that performs exposure for forming an electrostatic latent image on the photosensitive drum 16 is disposed at a position facing the photosensitive drum 16.

  The developing device 10 is a device that forms a desired image by frictionally charging the toner 11 from the sponge roller 13 to the developing roller 14 and supplying it.

Here, the sponge roller 13 as a supply roller includes, for example, a silicone foam rubber (hardness: 45 (Asuka F)) having a cell diameter of 300 to 500 μm around the core metal, and the outer diameter thereof is a central φ15. It is a saddle type roller having a diameter of 0.5 mm and an end portion φ14.8 mm , and a central portion larger than the end portion . The average cell diameter of the sponge roller 13 is 0.2 to 0.5 mm (observed by a charge coupled device (hereinafter referred to as “CCD”)).

  The developing roller 14 includes, for example, a steel whose surface is nickel-plated steel, and an elastic layer formed of urethane rubber around the core metal, and a surface layer made of isocyanate formed on the surface of the elastic layer. The outer diameter is φ19.6 mm. The surface layer has a surface roughness of Rz 6 to 7 μm (measured with a surface roughness meter) and a hardness of 70 (JISA).

  The developing blade 15 is, for example, a stack of two stainless steel (SUS304B-TA) plates with a thickness of 0.08 mm bent at a radius of 0.275 mm, and the short side bent when viewed from the rotation direction of the developing roller 14 is upstream. On the side, the developing roller 14 is brought into contact so that the long side is on the downstream side and is bent with a certain linear pressure (about 40 to 70 gf / cm). Further, the photosensitive drum 16 has a photosensitive layer made of an organic compound on an aluminum base tube, for example, and has an outer diameter of 29.95 mm. The nip (NIP) width at the transfer portion between the photosensitive drum 16 and the transfer roller 22 is, for example, 1.00 mm.

  Although not shown in FIG. 1, gears for transmitting driving are fixed to the rollers 13, 14, 17 and the photosensitive drum 16 by press-fitting or other methods. A gear fixed to the photosensitive drum 16 is a drum gear, a gear fixed to the developing roller 14 is a developing gear, a nationally fixed gear to the sponge roller 13 is a sponge gear, a gear fixed to the charging roller 17 is a charge gear, a developing gear, The gear installed between the sponge gears is called an idle gear. Here, the peripheral speed ratio between the developing roller 14 and the sponge roller 13 is changed to 1.33, 1.50, 1.72, and 2.00 by changing the number of teeth and positions of the developing gear, the sponge gear, and the idle gear. 2.22 to be changed.

(Toner details)
The toner 12 was produced, for example, by the following method (so-called pulverization method).

  100 parts by weight of a polyester resin (number average molecular weight: 3700, Tg: 62 ° C.) as a binder resin, 1 part by weight of a salicylic acid complex as a charge control agent, 3 parts by weight of phthalocyanine blue (CI PigmentBlue 15: 3) as a colorant, A composition mixture consisting of 10 parts by weight of a release agent (Tg: 100 ° C.) was sufficiently stirred and mixed in a mixer (Henschel mixer manufactured by Mitsui Miike Chemical Co., Ltd.), and then the resulting mixture was continuously opened in a roll. After being melted and kneaded at a temperature of 100 ° C. for about 3 hours by a kneader (Mitsui Mining Co., Ltd.) and cooled to room temperature, the resulting kneaded product was subjected to a collision plate crusher using a jet stream (Nippon Pneumatic Industry) (Dispersion separator made by Co., Ltd.). Thereafter, classification was performed with a wind rotor rotating dry air classifier (micron separator manufactured by Hosokawa Micron Co., Ltd.) using centrifugal force to obtain a base toner. By changing the conditions (force, time, etc.) of this pulverization step, base toner A0 with a circularity of 0.930, base toner B0 with 0.940, base toner C0 with 0.945, 0.950. A base toner D0 was obtained.

The circularity of the toner 12 here means
The circularity = the circumference of a circle having the same area as the particle projection area / the circumference of the particle projection image. When the circularity is 1, the projection image of the toner 12 is a perfect circle. As the distance from the sphere increases (the unevenness increases), the circularity value decreases.

  The circularity was measured in the following procedure using, for example, a flow type particle image analyzer FPIA-2100 (manufactured by Sysmex Corporation).

  First, 4 to 6 drops (about 0.5%) of a neutral detergent (for example, general household kitchen dish detergent) is dropped into a 100 ml beaker, and an electrolytic solution (for example, Beckman Coulter Company's Isoton) is put therein. Add 100ml and shake a little to dissolve the dispersant. The toner is piled up with a micro spatula, and the 100 ml beaker is dispersed with an ultrasonic disperser for 60 seconds. A dispersed 100 ml beaker is set in the apparatus and measurement is started to obtain a circular bond.

  100 parts by weight of base toner, 1.0 part by weight of hydrophobic silica fine powder “R-972” (manufactured by Nippon Aerosil Co., Ltd.) and 1.5 parts by weight of hydrophobic silica fine powder “RY-50” (manufactured by Nippon Aerosil Co., Ltd.) And titanium oxide, which is a conductive fine powder powder, were mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), and then sieved to prepare a toner. At this time, toners Al, Bl-4, Cl-3, and Dl-3 having different charge amounts were prepared by changing the amount of titanium oxide.

  The charge amount of each toner 12 was measured by the following procedure using, for example, Q / M-meter (manufactured by EPPING).

First, place the cell and lid on a precision balance and perform zero correction. After about 2.5 g of toner 12 is put in the cell with a measuring spoon, the cell (with a lid) is placed on a precision balance and the weight of the toner 12 is read. In this state, zero correction of the precision balance is performed again, and then the (covered) cell is taken out and attached to the main body. Close the door of the main body and press the start button (measurement time 90 seconds, suction amount 1000 cm3 / min). After the measurement is completed, the VAC digital display value is read (VAC value). The cell (with the lid) is taken out, placed on a precision balance, and the weight (toner suction amount) is measured. Continue to measure twice, and if the difference is within ± 1.0, average it to the measured value,
Charge amount [μC / g] = (VAC value × 10) / (Toner suction amount [mg])
From this, the charge amount q of the toner 12 is obtained. The higher the charge amount q is, the easier the toner 12 is charged, and the lower the charge amount q is, the harder it is to charge. That is, the charge amount q is an index representing the ease of charging of the toner. In Example 1, since a negatively charged electrophotographic image forming apparatus was used, “high” indicates “absolute value is large on the minus side” and “low” with respect to the charge amount q. Indicates that “the absolute value is small on the minus side”. For example, when the charge amount q of the toner 12 of −20 μC / g and the toner 12 of −60 μC / g are compared, the charge amount of the toner 12 of −60 μC / g is higher, and the toner 12 of −20 μC / g However, the charge amount q is low.

  As a result of the measurement, the charge amount q of each toner 12 is Al: −22 μC / g, Bl: −13 μC / g, B2: −20 μC / g, B3: −51 μC / g, B4: −60 μC / g, Cl : -21 μC / g, C2: −48 μC / g, C3: −59 μC / g, Dl: −20 C / g, D2: −46 μC / g, D3: −60 μC / g.

  The fine powder to be mixed with the pastener includes, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite. Diatomite, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like.

  The fine silica powder is a fine powder having a Si-0-Si bond, and may be either a dry method or a wet method. In addition to anhydrous silicon dioxide, any of aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate and the like may be used. Alternatively, a silane coupling agent, a titanium coupling agent, silicon oil, silica fine powder surface-treated with silicon oil having an amine in the side chain, or the like can be used.

(Contrast between the embodiment of the presence or absence of contamination on the continuous image and the comparative example)
As shown in FIG. 3, in the image forming apparatus according to the first exemplary embodiment, the toner 12, the sponge roller 13, and the developing roller 14 are set to predetermined conditions (embodiments), and the presence or absence of contamination on a continuous image is checked. It is a figure which shows the result (The thing which has generate | occur | produced stain | pollution | contamination is (*) and the thing which has not generate | occur | produced dirt) compared with the comparative example visually confirmed.

  In FIG. 3, in Comparative Example 1, the toner A1 is used, the peripheral speed Vsp [mm / sec] of the sponge roller 13 is 150, and the ratio of the peripheral speed Vdv [mm / sec] of the developing roller 14 to the peripheral speed Vsp. An image forming apparatus having a peripheral speed ratio δ (= Vdv / Vsp) of 1.33 was used.

  In Comparative Example 2, an image forming apparatus using toner Bl, having a peripheral speed Vsp of 150 and a peripheral speed ratio δ of 2.22 was used.

  In Embodiments 1 to 3 in Example 1, toners B2 to B4 are used, the peripheral speed Vsp is fixed at 150, and the peripheral speed ratio δ is set to 1.50, 1.72, and 2.00, respectively. A device was used.

  In Comparative Example 3, an image forming apparatus using toner B4, having a peripheral speed Vsp of 150 and a peripheral speed ratio δ of 2.22 was used.

  In Comparative Example 4, an image forming apparatus using toner B2, having a peripheral speed Vsp of 175 and a peripheral speed ratio δ of 1.33 was used.

  In Embodiments 4 to 6, image forming apparatuses using toners B2 to B4, fixing the peripheral speed Vsp to 100, and changing the peripheral speed ratio δ to 1.50, 1.72, and 2.00, respectively.

  In Comparative Examples 5 and 6, an image forming apparatus was used in which the toner B4 was used, the peripheral speed Vsp was set to 100 and 80, and the peripheral speed ratio δ was fixed to 2.22.

  In the seventh to ninth embodiments, toners Cl to 3 were used, the peripheral speed Vsp was fixed at 150, and the peripheral speed ratio δ was changed to 1.50, 1.72, and 2.00, respectively.

  In Comparative Example 7, an image forming apparatus using toner C3, having a peripheral speed Vsp of 150 and a peripheral speed ratio δ of 2.22 was used.

  In Embodiments 10 to 12, an image forming apparatus using toner Cl to 3 and fixing the peripheral speed Vsp at 100 and changing the peripheral speed ratio δ to 1.50, 1.72, and 2.00, respectively was used. .

  In Comparative Example 8, an image forming apparatus using toner C3, having a peripheral speed Vsp of 100 and a peripheral speed ratio δ of 2.22 was used.

  In the thirteenth to fifteenth embodiments, the toners D1 to D3 were used, the peripheral speed Vsp was fixed at 150, and the peripheral speed ratio δ was changed to 1.50, 1.72, and 2.00, respectively.

  In Comparative Example 9, an image forming apparatus using toner D3, having a peripheral speed Vsp of 150 and a peripheral speed ratio δ of 2.22 was used.

  In the sixteenth to eighteenth to eighteenth embodiments, the image forming apparatus using toners D1 to D3, nationalizing the peripheral speed Vsp at 100, and changing the peripheral speed ratio δ to 1.50, 1.72, and 2.00, respectively.

  In Comparative Example 10, an image forming apparatus using toner D3, having a peripheral speed Vsp of 100 and a peripheral speed ratio δ of 2.22 was used.

(Overall operation of image forming apparatus)
In the image forming apparatus shown in FIGS. 1 and 2, when a printing instruction is issued from a control unit (not shown), first, a motor in a printer body (not shown) starts to rotate and is driven to a drum gear through several gears in a printer body (not shown). , And the photosensitive drum 16 in each developing device 10 rotates in the direction of the arrow in FIG. When the drive is transmitted from the drum gear to the developing gear, the developing roller 14 rotates in the direction of the arrow in FIG. 1, and when the driving is transmitted from the developing gear to the sponge gear through the idle gear, the sponge roller 13 is moved to the arrow in FIG. Further, when the drive is transmitted from the drum gear to the charge gear, the charging roller 17 rotates in the direction of the arrow in FIG. On the other hand, the rotation of the motor in the printer main body (not shown) is transmitted to the transfer process and the fixing process through several gears of another system in the printer main body (not shown).

  Almost simultaneously with the start of rotation of the motor, a predetermined voltage is applied to each member in the development, transfer, and fixing process by a power source (not shown) in the printer body.

  The surface layer of the photosensitive drum 16 is uniformly charged by the voltage applied to the charging roller 17 and its rotation. When the charged portion of the photosensitive drum 16 reaches below the LED head 19, the LED head 19 emits light in accordance with an image to be printed sent to an exposure control unit in a printer control unit (not shown), and is statically placed on the photosensitive drum 16. An electrostatic latent image is formed. When the portion where the electrostatic latent image is formed on the photosensitive drum 16 reaches the developing roller 14, it is thinned by the developing blade 15 due to a potential difference between the electrostatic latent image on the photosensitive drum 16 and the developing roller 14. The toner 12 on the developing roller 15 moves onto the photosensitive drum 16.

  The toner 12 transferred onto the recording paper 20 in the transfer process is fixed on the recording paper 20 by heat and pressure in the fixing device 30 in the fixing process. On the other hand, a part of the toner 12 remaining on the photosensitive drum 16 without being transferred is scraped off by the cleaning blade 18, and after the printing is finished, the toner 12 is disposed in the waste developer tank 28 according to a sequence determined by a printer control unit (not shown). Collected.

(Print evaluation)
In the operation of the image forming apparatus, the toner 12 is charged mainly by friction caused by the rotation of the developing roller 14 and the sponge roller 13. A good image is formed by appropriately performing the frictional charging. In the first embodiment, the product of the peripheral speed ratio δ between the developing roller 14 and the sponge roller 13 and the charge amount q of the toner 12 itself q ×. We focused on δ. Then, with the image forming apparatus in which the value of the product q × δ is changed, for example, continuous printing evaluation as in the following (1) to (3) was performed using A4 paper.

  (1) Put 300 g of toner in the toner cartridge 11.

  (2) The image forming apparatus equipped with the toner cartridge 11 of (1) is left overnight (12H or more) in a temperature-controlled room having a temperature of 10 ° C. and a humidity of 20% (hereinafter referred to as “LL environment”).

  (3) Print 2100 sheets of a 0.3% density image at 3P / J (repeated “printing 3 sheets continuously and then stopping the printer”) in a temperature-controlled room in an LL environment.

  As a result of visual confirmation of the presence or absence of contamination on the continuous images in this way (“X” indicates that “dirt” has occurred and “O” indicates that “dirt” has not occurred). It is shown in FIG.

  The term “dirt” as used herein refers to the case where the excessively charged toner 12 is transferred from the developing roller 14 to the photosensitive drum 16 regardless of the potential difference (electrostatic latent image) between the developing roller 14 and the photosensitive drum 16 in the electrophotographic system. It is a phenomenon that develops and appears in the image. The evaluation was performed in the LL environment because the LL environment is most easily contaminated. If the LL environment is not contaminated, the RT environment (temperature of about 25 ° C. and humidity of about 5%, so-called office environment). ) And HH environments (temperature 28 ° C. and humidity 80%). This is a problem of the amount of moisture in the air. If the amount of moisture is small (if it is dry), the amount of moisture adsorbed on the toner 12 is relatively reduced and the apparent resistance of the toner 12 is increased. However, if the amount of moisture is large, the amount of moisture adsorbed on the toner 12 is relatively increased and the apparent resistance of the toner 12 is lowered, so that the toner 12 is less likely to be a belt. It is.

  In FIG. 3, “−” (slash) in the “dirt” column indicates a case where a defect on the image other than the stain has occurred.

  In FIG. 3, in Comparative Example 1, since white spots occurred on the image, detailed data collection was not performed. This is considered to be because the circularity of the toner Al is too low. That is, it is considered that when the circularity of the toner 12 is too low, that is, the shape becomes indefinite, the toner 12 is not uniformly developed and transferred, so that white spots occur. Therefore, the subsequent experiment using the toner A1 was not performed.

  In Comparative Example 2, since a sufficient image density was not obtained, detailed data collection was not performed. This is considered to be because the charge amount q of the toner Bl is too low and the toner is not sufficiently charged. As described above, in the electrophotographic image forming apparatus, the toner 12 is charged mainly by friction caused by the rotation of the developing roller 14 and the sponge roller 13. That is, an image forming apparatus having a large peripheral speed ratio δ should have a higher ability to charge the toner 12, but a sufficient image density can be obtained even when the peripheral speed ratio δ is the maximum value in the first embodiment. Thus, it was found that the toner was not sufficiently charged (cannot be sufficiently charged).

  In Embodiments 1 to 3, good images without stains were obtained.

  In Comparative Example 3, contamination occurred.

  In Comparative Example 4, the image density decreased as the number of printed sheets increased. Therefore, when the developing device 10 was disassembled and observed, the toner 12 was fused to the sponge roller 13 (so-called filming). Was observed. This is presumably because the peripheral speed Vsp of the sponge roller 13 is too high. That is, it is considered that when the peripheral speed Vsp increases, the frictional heat (with the developing roller 14) increases, and the toner 12 is melted by the heat and fused to the sponge roller 13. Therefore, thereafter, the experiment at the peripheral speed Vsp = 175 was not performed.

  In Embodiments 4 to 6, good images without stains were obtained.

  In Comparative Example 5, contamination occurred.

  In Comparative Example 6, since sufficient image density was not obtained, detailed data collection was not performed. This is considered to be because the peripheral speed Vsp of the sponge roller 13 is too low and the toner B4 is not sufficiently charged. In other words, if the peripheral speed Vsp becomes too low, the chance of friction (with the developing roller 14) decreases, and it is considered that the toner 12 is not sufficiently charged by friction. Therefore, thereafter, the experiment at the peripheral speed Vsp = 80 was not performed.

  In Embodiments 7 to 9, good images without stains were obtained.

  In Comparative Example 7, contamination occurred.

  In Embodiments 10 to 12, good images with no stain were obtained.

  In Comparative Example 8, contamination occurred.

  In Embodiments 13 to 15, good images without stains were obtained.

  In Comparative Example 9, contamination occurred.

  In Embodiments 16 to 18, good images without stains were obtained.

  In Comparative Example 10, contamination occurred.

(Effect of Example 1)
As described in the print evaluation of FIG. 3, it can be seen that in Embodiments 1 to 18 in which a good image without stains was obtained, the value of the product q × δ is between 30 and 120. That is, it was found that good printing without smearing can be obtained by using an image forming apparatus in which 30 ≦ q × δ ≦ 120 and 1.50 ≦ δ ≦ 2.00 .

  If the value of the peripheral speed ratio δ is high, the toner 12 is rubbed more at the contact portion between the developing roller 14 and the sponge roller 13 (the charging opportunity increases), which is an index of the ease of charging of the toner 12. If the amount of charge q is too high, the toner 12 is excessively charged and stains occur. On the other hand, if the value of the peripheral speed ratio δ is low, the chance of charging the toner 12 is reduced. Therefore, if the charge amount q is too low, the toner 12 is not sufficiently charged, and in the worst case, the toner is transferred from the developing roller 14 to the photosensitive drum 16. 12 is not developed (image formation cannot be performed).

  That is, when the value of the peripheral speed ratio δ is high, the charge amount q is required to be low, and when the value of the peripheral speed ratio δ is low, the charge amount q is required to be high. It will be within a certain range.

(Configuration of Example 2)
The configurations of the image forming apparatus and the developing apparatus 10 in the second embodiment of the present invention are the same as those in the first embodiment. The symbol “12A” is attached to the above).

  A styrene-acrylic copolymer resin is obtained from styrene, acrylic acid, and methylmethacrylic acid in an aqueous solvent to obtain primary particles. Further, phthalocyanine blue (CI Pigmen Blue 15: 3) is used as a colorant. Further, as the wax, stearyl stearate is used as a higher fatty acid ester wax. These were mixed and agglomerated to obtain a pastener. By changing the conditions (heat, time, etc.) of this agglomeration step, pasteeners E0 having a circularity of 0.960 and pasteeners F0 having 0.970 were obtained.

  In 100 parts by weight of the pastener, 0.7 parts by weight of hydrophobic silica fine powder “R-972” (produced by Nippon Aerosil Co., Ltd.) and 1.7 parts by weight of hydrophobic silica fine powder “RY-50” (produced by Nippon Aerosil Co., Ltd.) And titanium oxide, which is a conductive fine powder powder, were mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), and then sieved to prepare a toner. At this time, by changing the amount of titanium oxide, the toner E1 with a charge amount of −20 μC / g, the toner E2 with a charge amount of −44 μC / g, the toner E3 with a charge amount of −60 μC / g, and a toner amount of −91 μC / g Toner E4 and toner Fl having a charge amount of −20 μC / g were prepared.

(Contrast between the embodiment of the presence or absence of contamination on the continuous image and the comparative example)
FIG. 4 corresponds to FIG. 3 of the first embodiment. As will be described later, in the image forming apparatus of the second embodiment, the toner 12A, the sponge roller 13, and the developing roller 14 are set under predetermined conditions (embodiment). ), And the result of visually confirming the presence or absence of dirt on the continuous image (× indicates that the dirt is generated, and ○ indicates that the dirt is not generated) in comparison with the comparative example. It is.

  4, in Embodiments 19 to 21 in Example 2, the toners El to 3 are used, the peripheral speed Vsp of the sponge roller 13 is fixed at 150, and the peripheral speed ratio δ is 1.50, 1.72, respectively. An image forming apparatus shaken at 2.00 was used.

  In Comparative Example 11, an image forming apparatus using toner E3, having a peripheral speed Vsp of 150 and a peripheral speed ratio δ of 2.22 was used.

  In the twenty-second to twenty-fourth to twenty-fourth embodiments, the image forming apparatus using toners El1 to 3, fixing the peripheral speed Vsp at 100, and changing the peripheral speed ratio δ to 1.50, 1.72, and 2.00, respectively.

  In Comparative Example 12, an image forming apparatus using toner E3, having a peripheral speed Vsp of 100 and a peripheral speed ratio δ of 2.22 was used.

  In Comparative Example 13, an image forming apparatus using toner E4, having a peripheral speed Vsp of 100 and a peripheral speed ratio δ of 1.33 was used.

  In Comparative Example 14, an image forming apparatus using toner Fl, having a peripheral speed Vsp of 100 and a peripheral speed ratio δ of 1.33 was used.

(Operation of Example 2)
With the configuration shown in FIG. 4, the same continuous printing evaluation as in Example 1 was performed. The result is shown in FIG.

  In FIG. 4, in Embodiments 19 to 21, good images without stains were obtained.

  In Comparative Example 11, contamination occurred.

  In Embodiments 22 to 24, good images without stains were obtained.

  In Comparative Examples 12 and 13, contamination occurred.

  In Comparative Example 14, a cleaning failure occurred. As described in the first embodiment, this is probably because the toner Fl is too circular and the toner 12 </ b> A remaining on the photosensitive drum 16 without being transferred cannot be scraped off by the cleaning blade 27. . Therefore, no subsequent experiment using the toner Fl was performed.

(Effect of Example 2)
As described in the print evaluation of FIG. 4, it can be seen that the values of the product q × δ are between 30 and 120 in the nineteenth to twenty-fourth embodiments in which good images without stains were obtained. That is, even when the toner 12A having a circularity of 0.960 is used, as in the first embodiment, if an image forming apparatus satisfying 30 ≦ q × δ ≦ 120 and 1.50 ≦ δ ≦ 2.00 is used, It was found that good prints without smudges can be obtained.

(Modification)
The present invention is not limited to the above-described embodiments, and various usage forms and modifications are possible. For example, the following forms (a) and (b) are used as the usage form and the modified examples.

  (A) In the image forming apparatuses according to the first and second embodiments, an example in which the present invention is applied to an electrophotographic printer has been described. However, the image forming apparatus may be changed to a configuration other than those illustrated in FIGS. The present invention is not limited to a printer, but can be applied to an electrophotographic copying machine, a facsimile machine, an image scanner, or a multifunction machine in which various functions thereof are integrated.

(B) Type and amount of raw materials (for example, binder resin, charge control agent, colorant, etc.) of the pastener mentioned in Examples 1 and 2, fine powder (for example, silica, titanium oxide) mixed with the pastener Etc.) and the amount thereof, and the materials of the sponge roller 13 and the developing roller 14 are merely examples, and even if other substances are used, 30 ≦ q × δ ≦ 120 and 1.50 ≦ δ ≦ 2. If it is 00 , the effect is not affected.

10, 10-1 to 10-4 Developing device 11 Toner cartridge 12 Toner 13 Sponge roller 14 Developing roller 16 Photosensitive drum 17 Charging roller 20 Recording paper 23 Transfer belt 24, 24-1 to 24-4 Transfer roller

Claims (19)

A rotatable developer carrying member for developing a developer composed of charged particles into an electrostatic latent image;
A rotatable developer supply means for supplying the developer to the developer carrier,
An image forming apparatus that supplies the developer from the developer supply means to the developer carrier and forms a desired image.
The absolute value of the charge amount in the developer is q [μC / g], the peripheral speed of the developer carrier is Vdv [mm / sec], and the peripheral speed of the developer supply means is Vsp [mm / sec]. When
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
Meet the,
The peripheral speed Vsp is 100 mm / sec or more and 150 mm / sec or less . The circularity of the particles in the developer is
Circularity = circumference of a circle having the same area as the particle projection area / perimeter of the particle projection image
= 0.940 to 0.960
The image forming apparatus according to claim 1, wherein: The image forming apparatus according to claim 1, wherein the developer supplying unit is configured to rotate in conjunction with the developer carrying member in contact with the developer carrying member . The image forming apparatus according to claim 1, wherein the developer supplying unit frictionally charges the developer and supplies the developer to the developer carrying member. The image forming apparatus according to claim 1, wherein the developer carrying member is a developing roller, and the developer supplying unit is a supplying roller. The image forming apparatus according to claim 5, wherein the supply roller is a saddle type roller having a central portion larger than an end portion. The image forming apparatus according to claim 5 or 6, further comprising:
An image forming apparatus comprising: a developing blade that contacts the developing roller and thins the developer supplied onto the developing roller. The image forming apparatus according to claim 7, wherein the developing blade is a double stack of stainless plates. A rotatable developer carrying member for developing a developer composed of charged particles into an electrostatic latent image;
A rotatable developer supply means for supplying the developer to the developer carrier,
An image forming apparatus that supplies the developer from the developer supply means to the developer carrier and forms a desired image.
The absolute value of the charge amount in the developer is q [μC / g], the peripheral speed of the developer carrier is Vdv [mm / sec], and the peripheral speed of the developer supply means is Vsp [mm / sec]. When
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
The filling,
The circularity of the particles in the developer is
Circularity = circumference of a circle having the same area as the particle projection area / perimeter of the particle projection image
= 0.940 to 0.960
An image forming apparatus. The image forming apparatus according to claim 9, wherein the developer supply unit is configured to rotate in conjunction with the developer carrier. 11. The image forming apparatus according to claim 9, wherein the developer supplying unit supplies the developer to the developer carrying member by friction charging. The image forming apparatus according to claim 9, wherein the developer carrying member is a developing roller, and the developer supplying unit is a supplying roller. 13. The image forming apparatus according to claim 12, wherein the supply roller is a saddle type roller having a central portion larger than an end portion. The image forming apparatus according to claim 12 or 13, further comprising:
An image forming apparatus comprising: a developing blade that contacts the developing roller and thins the developer supplied onto the developing roller. The image forming apparatus according to claim 14, wherein the developing blade is a stack of two stainless plates. A rotatable developer carrying member for developing a developer composed of charged particles into an electrostatic latent image;
A rotatable developer supply means for supplying the developer to the developer carrier,
An image forming apparatus that supplies the developer from the developer supply means to the developer carrier and forms a desired image.
The absolute value of the charge amount in the developer is q [μC / g], the peripheral speed of the developer carrier is Vdv [mm / sec], and the peripheral speed of the developer supply means is Vsp [mm / sec]. When
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
The filling,
The developer carrying member is a developing roller, and the developer supplying means is a supplying roller;
Further, the supply roller is a saddle type roller having a central portion larger than an end portion. The image forming apparatus according to claim 16, further comprising:
An image forming apparatus comprising: a developing blade that contacts the developing roller and thins the developer supplied onto the developing roller. The image forming apparatus according to claim 17, wherein the developing blade is a double stack of stainless plates. A rotatable developer carrying member for developing a developer composed of charged particles into an electrostatic latent image;
A rotatable developer supply means for supplying the developer to the developer carrier,
An image forming apparatus that supplies the developer from the developer supply means to the developer carrier and forms a desired image.
The absolute value of the charge amount in the developer is q [μC / g], the peripheral speed of the developer carrier is Vdv [mm / sec], and the peripheral speed of the developer supply means is Vsp [mm / sec]. When
30 ≦ q × (Vdv ÷ Vsp) ≦ 120
And 1.50 ≦ (Vdv ÷ Vsp) ≦ 2.00
The filling,
The developer carrying member is a developing roller, and the developer supplying means is a supplying roller;
And a developing blade that contacts the developing roller and thins the developer supplied onto the developing roller,
2. The image forming apparatus according to claim 1, wherein the developing blade is a double stack of stainless plates.

Images