JP2008170623A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high image quality by adjusting a latent image potential difference between a vertical line and a horizontal line generated due to unevenness of a photoreceptor, unevenness of a beam spot diameter, and change of a photoreceptor linear speed. <P>SOLUTION: An image forming apparatus has a potential sensor 20 as a potential measurement means for measuring a latent image potential of an image carrier. A control means 2 detects (calculates) a ratio of the latent image potential in image-forming a one-dot vertical line and the latent image potential in image-forming a one dot horizontal line based on measured value from a potential sensor 20, and modifies an exposure condition by an exposure device 1171A according to the ratio of the detected latent image potential. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, a multifunction machine having at least one of these, a plotter, and the like, and more particularly to an image forming apparatus that performs development using a two-component developer.

In recent years, there has been a demand for higher image quality in image forming apparatuses using an electrophotographic system. One way to improve image quality is to improve the granularity of the developer, which has been greatly improved in recent years by reducing the particle size of the developer such as toner and carrier.
However, the abnormal particle image with directionality peculiar to two-component development such as 1 dot line aspect ratio deterioration (thinner is narrower than vertical), missing character leading edge region, halftone trailing edge blur, etc. cannot be solved by toner particle size. The problem largely depends on the development conditions, and is still a big problem even now.
Japanese Patent Application Laid-Open No. 2004-228561 detects a change in film thickness of a photoconductor, and controls the exposure state (beam spot diameter, exposure duty, etc.) accordingly, so that the latent image of the photoconductor is obtained even when the photoconductor deteriorates with time. It is shown that it is possible to perform image formation with good background and dot reproducibility over time without changing the distribution.

Japanese Patent Laid-Open No. 2005-266481 Japanese Patent Laid-Open No. 10-193683 Japanese Patent No. 0475379 JP 2005-189794 A Japanese Patent No. 0367961 JP 2006-030955 A

  However, in the invention described in Patent Document 1, attention is not paid to the difference between the latent image potential of the vertical line and the latent image potential of the horizontal line. The ratio fluctuation cannot be solved.

  The present invention has been made based on the above-described circumstances, and adjusts the latent image potential difference between the 1-dot vertical line and the 1-dot horizontal line, which is caused by variations in the photoreceptor, beam spot diameter, changes in the photoreceptor linear velocity, and the like. Further, an object of the present invention is to provide an image forming apparatus capable of forming a high-quality image without any deterioration in the aspect ratio of 1 dot line in any environment.

  In order to solve the above-mentioned problems, the invention described in claim 1 comprises an image carrier on which an electrostatic latent image is formed on the surface by exposure based on image information, and a two-component developer comprising a toner and a carrier. An image forming apparatus comprising: a developing device that visualizes an electrostatic latent image on an image carrier with toner; a potential measurement unit that measures a latent image potential of the image carrier; and the potential measurement unit Control means for detecting the ratio of the latent image potential at the time of 1 dot vertical line image formation to the latent image potential at the time of 1 dot horizontal line image formation based on the measured value, and changing the exposure condition according to the detected latent image potential ratio And having a feature.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus further includes a temperature / humidity detection unit for detecting temperature / humidity, and the control unit detects the ratio of the latent image potential to the detection from the temperature / humidity detection unit. The exposure condition is changed depending on the value.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image carrier has a plurality of linear velocities.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the exposure duty ratio is controlled as an exposure condition to be changed.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner used in the developing device has a volume average particle diameter of 3 to 8 μm, a volume average particle diameter (Dv) and a number average particle diameter. The ratio (Dv / Dn) to the diameter (Dn) is in the range of 1.00 to 1.40.
According to a sixth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner used in the developing device has a shape factor SF-1 in the range of 100 to 180, and a shape factor SF-2 of 100. It is characterized by being in the range of ~ 180.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner used in the developing device includes at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent. It is a toner obtained by crosslinking and / or stretching reaction of a toner material liquid in which an agent is dispersed in an organic solvent in an aqueous medium.
According to an eighth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner used in the developing device has a substantially spherical shape.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the shape of the toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (provided that r1 ≧ r2 ≧ r3). The ratio of the major axis r1 to the minor axis r2 (r2 / r1) is in the range of 0.5 to 1.0, and the ratio of the thickness r3 to the minor axis r2 (r3 / r2) is 0. It is in the range of 7 to 1.0.

According to the present invention, it is possible to adjust the latent image potential difference between the 1 dot vertical line and the 1 dot horizontal line caused by variations in the photosensitive characteristics of the photoconductor, variations in the beam spot diameter, changes in the linear velocity of the photoconductor, etc., and excellent dot reproducibility. Image formation can be performed.
Further, in any environment, it is possible to realize high image quality without deteriorating the 1 dot line aspect ratio.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
First, the overall mechanical configuration of the image forming apparatus according to the present embodiment will be described.
As shown in FIG. 1, the image forming apparatus 1000 adopts a laser printer configuration, and includes “a photoconductive photosensitive member formed in a cylindrical shape” as an image carrier 1110. Around the image carrier 1110, a charging roller 1121, a developing device 1131, a transfer roller 1141, and a cleaning device 1151 are arranged as charging means.
The developing device 1131 has a developer carrier (development sleeve) that faces the image carrier 1110 and is supported so that the circumferential surface thereof can circulate, and a two-component developer composed of toner and carrier on the developer carrier. The electrostatic latent image on the image carrier is visualized with toner by applying a developing electric field between the image carrier and the developer carrier.

As the charging means, not only the charging roller 1121 but also a corona charger, a brush, a belt, or the like may be employed. Further, an optical scanning device 1171 is disposed above the image carrier 1110, and the image carrier 1110 is exposed on the downstream side of the charging roller 1121.
When performing image formation, the photoconductive image carrier 1110 rotates clockwise, the surface thereof is uniformly charged by the charging roller 1121, and light scanning is performed as a part of the exposure apparatus (see FIG. 2) 1171A. An electrostatic latent image is formed in response to writing exposure by laser scanning of the apparatus 1171. The formed electrostatic latent image is a “negative latent image” and is formed with exposure corresponding to the image of the document. This electrostatic latent image is reversely developed by the developing device 1131 with toner having the same polarity as the charged polarity of the image carrier 1110, and a toner image is formed on the image carrier 1110.

A cassette 1181 containing a transfer member P such as paper or OHP (transparent sheet) can be attached to and detached from the main body of the image forming apparatus 1000, and in the mounted state, the uppermost sheet of the stored transfer member P is supplied. Paper is fed by a paper roller 1201. The transferred transfer paper P is fed to the registration roller pair 1191 at the leading end.
The registration roller pair 1191 sends the transfer member P to the transfer roller 1141 in time with the toner image on the image carrier 1110 moving to the transfer position. The transferred transfer member P is superimposed on the toner image at the transfer position, and the toner image is electrostatically transferred by the action of the transfer roller 1141.
The transfer member P to which the toner image has been transferred is sent to the fixing device 1161, and the fixing device 1161 receives, for example, heating and nip pressure to fix the toner image. The transfer member P after image fixing passes through the conveyance path 1211 and is discharged onto the tray 1231 by the discharge roller pair 1221.

On the other hand, the surface of the image carrier 1110 after the transfer of the toner image is cleaned by a cleaning device 1151 to remove residual toner, paper dust, and the like.
The toner image can be transferred not only by the transfer roller 1141, but also by a belt, a charger, a brush, or the like as described above, or can be transferred via an “intermediate transfer medium” such as an intermediate transfer belt. However, although an example of a monochrome image forming apparatus is shown here, a color image forming apparatus having a plurality of developing units on the image carrier 1110, a color tandem system having a plurality of image carriers and an image forming unit, or the like. Of course, it may be an image forming apparatus.

Next, the configuration of the electrical system of the image forming apparatus 1000 will be described. FIG. 2 is a block diagram illustrating a configuration of the electrical system of the image forming apparatus 1000. As shown in FIG. 2, the image forming apparatus 1000 of the present embodiment includes a controller 12 having a microcomputer configuration that controls each unit and an engine control unit 13 as basic configurations, and the controller 12 and the engine control unit 13. Thus, the control means 2 is configured.
The controller 12 includes a storage device such as an image memory 14 and a font bank 15. A host computer 16 is connected to the controller 12 via bidirectional Centronics. The controller 12 receives image information from the host computer 16 and performs processing for the printer function.

The engine control unit 13 is electrically connected to a scanner 17 that operates in response to a drive signal from the engine control unit 13. Image information read by the scanner 17 is transmitted to the controller 12. 12 performs processing for the digital copier function.
That is, the controller 12 that has received the image signal from the host computer 16 or the scanner 17 expands it in the image memory 14 and transmits control / write data to the engine control unit 13 in accordance with the drive signal from the operation panel 18. . At this time, if the image signal is text data from the host computer 16, an appropriate font is called from the font bank 15 as necessary, and image data (character data) according to the called font is developed in the image memory 14. To do.

On the other hand, the engine control unit 13 that has received control / write data transmission from the controller 12 supplies drive motors, clutches, solenoids, and the like serving as drive sources for various movable units such as a sheet feeding device and an image carrier 1110. A drive signal is applied to drive and control them, and a drive signal is applied to the high voltage power supply circuit 19 for the charging device, the exposure device 1171A, the developing device, and the like to drive and control them.
The engine control unit 13 is connected to a potential sensor 20 as potential measuring means for detecting a latent image potential on the image carrier 1110. By outputting the latent image potential values of the 1 dot vertical line and 1 dot horizontal line detected by the potential sensor 20 to the engine control unit 13, the engine control unit 13 calculates and recognizes the potential difference of 1 dot line vertical and horizontal. Let

Further, for example, a means for detecting the temperature and humidity in the apparatus in the apparatus main body (not shown) is connected. The temperature / humidity data detected by the temperature / humidity sensor 21 as temperature / humidity detection means is output to the engine control unit 13 for recognition.
The control means 2 controls the exposure state of the exposure apparatus 1171A to be the optimum exposure state based on the recognition of the potential difference and the temperature / humidity value. A memory (not shown) of the control unit 2 stores a relational data table of potential difference, temperature / humidity, and exposure conditions obtained in advance, and controls the exposure state using the table.
FIG. 3 shows the relationship between the macroscopic latent image potential difference and the 1 dot line aspect ratio when 1 dot line length and width are imaged. From the figure, it can be seen that the smaller the latent image potential between 1 dot line length and width, that is, the lower the latent image potential of the horizontal line, the better the 1 dot line aspect ratio.

Even when the potential difference between the vertical and horizontal directions of the 1 dot line changes under various conditions, it is possible to maintain a stable state without deteriorating the 1 dot line aspect ratio by adjusting the exposure conditions. As can be seen from the figure, the smaller the latent image potential difference between 1 dot line length and width, that is, the lower the latent image potential of the horizontal line, the better the 1 dot line aspect ratio. When the potential of the vertical line is adjusted by reducing the length, if the duty is lowered too much, there is a side effect that the diagonal line becomes faint and can be used only to some extent.
In FIG. 3, slanting line blurring occurs at a potential difference of −40 V or less, which is NG (not good).

Further, since the 1 dot line aspect ratio is also affected by temperature and humidity, it is possible to prevent the 1 dot line aspect ratio from changing depending on the usage environment by changing the exposure condition according to the detected temperature and humidity.
FIG. 4 shows the relationship between the relative humidity and the 1 dot line aspect ratio. From the figure, it can be seen that the higher the relative humidity, the worse the 1 dot line aspect ratio. FIG. 5 shows the relationship between the exposure duty ratio and the 1 dot line aspect ratio.
As will be described later, it can be seen that the smaller the exposure duty ratio, the better the 1 dot line aspect ratio.
4 and 5, the relationship between the exposure duty ratio (%) (relative humidity 50% RH standard) in which the relative humidity in FIG. 6 is equivalent to the 1 dot line aspect ratio is derived, and correction is performed as shown in FIG. The change of the 1 dot line aspect ratio due to the use environment can be eliminated.
As described above, the latent image potential variation is eliminated by equalizing the 1-dot line vertical and horizontal latent image potential differences caused by various variations (variation of the photoconductor, variation of the beam spot diameter, change of the linear velocity of the photoconductor, etc.). Furthermore, by changing the exposure condition according to the use environment, it is possible to suppress the change in the 1 dot line aspect ratio as much as possible.

When there are a plurality of photosensitive member linear velocities, the effect of the present invention is remarkable. As shown in FIG. 7, the vertical and horizontal potential differences of 1 dot line may differ depending on the photosensitive member linear velocity, and the higher the photosensitive member linear velocity tends to increase the vertical and horizontal potential differences of 1 dot line.
As a result, as described above, the 1-dot line aspect ratio deteriorates when the photosensitive member linear velocity is higher. Therefore, according to the present invention, even when there are a plurality of photosensitive member linear velocities, the 1 dot line aspect ratio can be maintained in a good state by adjusting the potential difference between the 1 dot line length and the horizontal direction for each line speed. .

  Next, a method for changing the exposure condition for adjusting the vertical and horizontal potential difference of 1 dot line will be described. As an exposure condition to be changed, there is an exposure duty ratio (irradiation time ratio). As shown in FIG. 8, by changing the exposure duty ratio (changing the writing time for 1 dot), the writing width (dot width) in the main scanning direction can be reduced, and vertical line writing can be performed. Along with this, the latent image potential of the vertical line becomes higher, and the potential difference between the vertical and horizontal sides of the 1 dot line becomes smaller, or the latent image potential of the horizontal line becomes smaller and the 1 dot line aspect ratio is improved. I understand.

Next, the toner suitably used in the image forming apparatus of the present invention will be described.
In order to reproduce minute dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. 9 and 10 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2.
The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-2 = {(PERI) ² / AREA} × (100π / 4) Expression (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.
Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.
When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

The toner suitably used in the image forming apparatus of the present invention includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent are dispersed in an organic solvent. A toner obtained by crosslinking and / or elongation reaction in an aqueous solvent. Hereinafter, the constituent material and the manufacturing method of the toner will be described.
(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound. Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable.
Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts.

Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use.
The trihydric or higher polyhydric alcohol (TO) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred.
Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid).
Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.
The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20.
By giving an acid value, it tends to be negatively charged, and furthermore, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.
The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.
Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.

The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.
The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.
The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like.
Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid.
Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.
The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.
The urea-modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group.

Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.
When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran).
In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.
By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition. The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.
The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.
In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

(Coloring agent)
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Lid Russian nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.
Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.

  The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used.
Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 −3 to 2 μm, and particularly preferably 5 × 10 −3 to 0.5 μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m <2> / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%.
Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle diameter of 5 × 10-2 μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed, a fluidity-imparting agent is not detached from the toner, a good image quality that does not cause fireflies and the like is obtained, and the residual toner is further reduced. .
Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large. However, when the added amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if
Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.

(Toner production method)
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferable. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.
Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.

Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).
Moreover, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a right fluoroalkyl group is used. Salt, benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries) Smoke), Megafac F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footage F-300 (Neos), and the like.

The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.).
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Bodies such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

  3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group. This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity of the isocyanate group structure of the polyester prepolymer (A) with the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.

5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner. The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

The toner according to the present invention has a substantially spherical shape and can be represented by the following shape rule.
FIG. 11 is a diagram schematically showing the shape of the toner of the present invention. In FIG. 11, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner of the present invention has a major axis and a minor axis. The ratio (r2 / r1) (see FIG. 11 (b)) is 0.5 to 1.0, and the ratio of thickness to minor axis (r3 / r2) (see FIG. 11 (b)) is 0.7 to 1.0. It is preferable to be in the range of 1.0.
When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained.
In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved.
Note that r1, r2, and r3 were measured with a scanning electron microscope (SEM) while changing the angle of field of view and taking pictures.

1 is a schematic configuration diagram of a laser printer as an image forming apparatus according to an embodiment of the present invention. It is a control block diagram of the laser printer. It is a graph which shows the relationship between 1 dot line length, a horizontal potential difference, and 1 dot line aspect ratio. It is a graph which shows the relationship between relative humidity and 1dot line aspect ratio. It is a graph which shows the relationship between exposure duty ratio and 1 dot line aspect ratio. It is a graph which shows the relationship between relative humidity and the exposure duty ratio from which 1 dot line aspect ratio becomes equivalent. It is a graph which shows the relationship between a photoreceptor linear velocity, 1 dot line length, and horizontal potential difference. It is a graph which shows the relationship between exposure duty ratio, 1 dot line vertical, and horizontal potential difference. FIG. 4 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-2. It is a figure which shows typically the shape of the toner of this invention.

Explanation of symbols

2 Control means 20 Potential sensor as potential measurement means 21 Temperature / humidity sensor as temperature / humidity detection means 1110 Photoconductor as image carrier 1131 Developing device

Claims (9)

It has an image carrier on which an electrostatic latent image is formed on the surface by exposure based on image information, and a two-component developer composed of toner and carrier. The electrostatic latent image on the image carrier is visible with toner. An image forming apparatus comprising: a developing device that forms an image;
The potential measuring means for measuring the latent image potential of the image carrier, and the latent image potential at the time of 1 dot vertical line image formation and the latent image potential at the time of 1 dot horizontal line image formation based on the measurement value from the potential measurement means. An image forming apparatus comprising: a control unit configured to detect a ratio and change an exposure condition according to the detected ratio of the latent image potential. The image forming apparatus according to claim 1.
An image forming apparatus comprising temperature / humidity detection means for detecting temperature / humidity, wherein the control means changes exposure conditions according to a ratio of the latent image potential and a detection value from the temperature / humidity detection means. The image forming apparatus according to claim 1 or 2,
An image forming apparatus having a plurality of linear velocities of the image carrier. The image forming apparatus according to claim 1 or 2,
An image forming apparatus that controls an exposure duty ratio as an exposure condition to be changed. The image forming apparatus according to claim 1 or 2,
The toner used in the developing device has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of 1.00 to 1.40. An image forming apparatus characterized by being in the range. The image forming apparatus according to claim 1 or 2,
The image forming apparatus according to claim 1, wherein the toner used in the developing device has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. The image forming apparatus according to claim 1 or 2,
The toner used in the above-described developing device is obtained by crosslinking a toner material solution in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent is dispersed in an organic solvent in an aqueous medium. And / or an image forming apparatus, wherein the toner is obtained by an extension reaction. The image forming apparatus according to claim 1 or 2,
An image forming apparatus, wherein the toner used in the developing device has a substantially spherical shape. The image forming apparatus according to claim 1 or 2,
The shape of the toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), and a ratio (r2 / r1) between the major axis r1 and the minor axis r2 is set. An image forming apparatus having a thickness in the range of 0.5 to 1.0 and a ratio (r3 / r2) of the thickness r3 to the minor axis r2 in the range of 0.7 to 1.0.

Images