JP2013195890A - Developing device, developing method, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that avoids an increase in costs, and includes a configuration capable of controlling AC/DC bias output that prevents reverse discharge in any circumstances.SOLUTION: The developing device superimposes and applies AC voltage and DC voltage as developing bias, receives a detection result from discharge detection means 1002 that detects discharge generated between a photoreceptor and a developing roller during non-contact development, and includes a control unit that changes and controls voltage supplied from voltage supply means 1001. The control unit 1000 stops application of bias having a polarity reverse to a polarity of discharge detected in application of AC bias voltage along with the discharge detection.

Description

  The present invention relates to an image forming apparatus, and more particularly to bias control used during development.

As is well known, in an image forming apparatus such as a copying machine, a printer, or a printing machine, an electrostatic latent image formed on a photosensitive member, which is a latent image carrier, is visualized by a developer supplied from a developing device. It is processed.
The visible image-processed toner image is transferred to a transfer material, and is then fixed by heating and pressurizing with a fixing device so that the toner melts and permeates to form a copy image.

  Some image forming apparatuses are configured to form not only a single color but also a plurality of colors such as full colors. In this case, images of different colors formed in a plurality of image forming units are belted. In some cases, a superimposed image is transferred onto a recording medium such as a recording sheet (secondary transfer) after being sequentially transferred (primary transfer) to an intermediate transfer body such as the above.

On the other hand, in a developing device used for image formation, a configuration using a one-component developer not containing a carrier in addition to a two-component developer containing a carrier and a toner is known. There is a configuration using a non-magnetic toner as the agent.
As one development method using non-magnetic toner, jumping development in which the toner layer is allowed to fly to the electrostatic latent image carrier by the electrostatic latent image without directly contacting the toner layer with the electrostatic latent image carrier such as a photoconductor. And non-contact development methods such as a projection development method (for example, Patent Document 1).

In Patent Document 1 described above, a large number of projections and depressions are formed on the surface of a developer carrying member for carrying toner to improve toner transportability, while a developing bias in which an AC bias is superimposed on a DC bias is used. A configuration relating to a jumping development system that performs visible image processing of an electrostatic latent image by flying toner from a developer carrying member arranged in a non-contact state with respect to the latent image carrying member is disclosed.
The AC bias used for the developing bias generates an oscillating electric field between the latent image carrier and the developer carrier, vibrates the toner in the electric field, and electrostatically discharges the toner toward the electrostatic latent image. It is used for visible image processing of the latent image and for collecting the toner flying to the background toward the developing carrier.

As disclosed in Patent Document 1 described above, a non-magnetic developing type non-magnetic one-component developing device used in an electrophotographic image forming apparatus is provided with a minute gap between a photosensitive member and a developing roller. In the process where the supply and recovery of the toner to the photoconductor are repeated by the applied AC voltage, the toner adheres to the latent image on the surface of the photoconductor, and the latent image is visualized.
The AC voltage to be applied is used by applying a voltage equal to or lower than the discharge start voltage in the gap between the photoconductor and the developing roller. This is because if discharge occurs, discharge traces are superimposed on the latent image on the photosensitive member, resulting in an abnormal image.

However, when applying an AC voltage under the above-described conditions, it is desirable to apply an AC voltage as large as possible in order to increase the development efficiency. Therefore, although the gap is maintained by the abutting roller method, A change with time occurs that the gap becomes narrow due to wear of the rollers. Therefore, it is necessary to apply an AC voltage considering the gap, discharge variation, and wear over time.
Therefore, as a method of setting the AC voltage, gradually increasing the AC voltage, searching for the discharge start point by the discharge detection circuit, and using the voltage obtained by subtracting the discharge variation and the wear over time from the discharge start point. Is known (for example, Patent Document 2).

  In Patent Document 2, even if an error occurs in the gap between the developing roller and the photosensitive member, the developing bias voltage is set simply and appropriately so that no leakage (discharge) occurs between the developing roller and the photosensitive member. The leak detection voltage applied between the developing roller and the photoconductor is changed so that the image can be adjusted and a good image free from noise can be stably obtained. A configuration is provided in which a leak generating means for generating a leak between and a leak detecting means for determining that a leak has occurred based on a current flowing between the developing roller and the photosensitive member is disclosed.

  Further, as a method for determining whether a leak occurs in the applied voltage described above, when a leak occurs in the gap between the toner density detecting means for detecting the density of the toner adhering to the photosensitive member and the developing roller and the photosensitive member. Leakage detection voltage detection means for detecting the voltage of the toner, and by detecting the change in the toner density by the toner density detection means to detect whether or not a leak image is generated by gradually changing the bias value for the developing sleeve, a leak occurs. There has been proposed a method for detecting the applied voltage (for example, Patent Document 3).

On the other hand, the AC voltage applied to the developing roller in the non-contact developing system is used by applying a voltage equal to or lower than the discharge start voltage of the gap between the photosensitive member and the developing roller (if a discharge occurs, the latent image on the photosensitive member is This is because the discharge traces are superimposed on the image, resulting in an abnormal image). However, as described above, it is desirable to apply as large an AC voltage as possible in order to increase the development efficiency.
Although the gap between the photosensitive member and the developing roller is maintained by the abutting roller system, the gap changes with time due to roller wear.
Therefore, it is necessary to apply an AC voltage in consideration of gap + discharge variation + time wear.

  As a method of setting the AC voltage, as disclosed in Patent Document 2 described above, the AC voltage is gradually increased, the discharge detection point is searched for by the discharge detection circuit, discharge variation from the discharge start point, and wear over time A method of using a voltage with reduced voltage, or as disclosed in Patent Document 3, whether or not a leak image is generated by gradually changing the bias value with respect to the developing sleeve determines whether the toner density is detected by the toner density detecting means. A method for detecting an applied voltage when a leak occurs and a method for performing bias control in consideration of environmental fluctuations such as atmospheric pressure fluctuations are proposed (for example, Patent Documents 4 and 5). .

However, in the conventional discharge detection method, a discharge (positive discharge and positive discharge) is caused from the developing roller to the photosensitive member pole portion due to a potential difference between the positive side potential of the AC voltage and the non-image portion potential Vd (for example, −700 V) of the photosensitive member. When this occurs, the extreme portion of the photoconductor changes from Vd (−700 V) to Vl (−50 V), the potential difference decreases all at once, and the discharge to this extreme portion is completed once.
This discharge generates ozone and ions due to air discharge in the gap between the photoreceptor and the developing roller. Although the photoconductor and the developing roller are rotating, they remain in the discharge portion for a while.
In this state, when the AC voltage is inverted to become a negative voltage, the potential difference between the negative potential of the developing roller and the local portion changed to Vl (−50 V) by the discharge and the remaining ozone and ions are There is a possibility that a phenomenon of discharging (referred to as reverse discharge) from the photosensitive member to the developing roller side may occur this time.

  The conventional discharge detection circuit can obtain the optimum AC voltage by detecting the positive discharge. However, reverse discharge also occurs depending on the conditions, so if the reverse voltage is applied to the rectifier circuit and the semiconductor and the breakdown voltage is exceeded. There is a case where parts are destroyed, and in order to avoid this, there is a problem that parts having high reverse breakdown voltage characteristics, that is, parts having high costs must be selected.

In Patent Document 2, only a circuit for detecting a leak is used, and no consideration is given to the circuit configuration and component characteristics of the leak detection circuit.
When the circuit was actually designed and evaluated, the phenomenon of reverse discharge appeared, and the mechanism was understood, and the influence on the electronic circuit at the time of occurrence was gradually understood.

  The forward applied voltage to the rectifying element and the semiconductor, which is not a problem in normal discharge, is excessive when reverse discharge is applied, and may be destroyed in some cases. In order to avoid such a case, it is necessary to select a component having a large reverse withstand voltage performance by estimating a safety factor several times when designing a product. In this way, when expensive parts are used, the cost increases.

On the other hand, as disclosed in the patent document, the discharge detection is only related to the optimization of the AC voltage accompanying the gap fluctuation, the atmospheric pressure fluctuation, or the environment (temperature and humidity) fluctuation. The AC voltage adjustment is very useful because it is known that when the gap fluctuation, the atmospheric pressure fluctuation, or the environment (temperature / humidity) fluctuation changes, the behavior of the toner changes and the influence on the image quality changes greatly.
However, there has been a problem that the DC voltage may deviate from the optimum condition when the AC voltage is optimized and the AC voltage is changed and updated.

  An object of the present invention is to control AC and DC bias outputs that do not cause reverse discharge in any case without incurring a cost increase in view of the technical problems in the conventional developing device and the image forming apparatus using the same. It is an object of the present invention to provide a developing device, a developing method, and an image forming apparatus having a configuration that can be used.

  In order to achieve this object, the present invention is arranged such that a developer carrier is disposed opposite to the latent image carrier at a predetermined interval, and the nonmagnetic one component is directed from the developer carrier to the latent image carrier. A developing device having a configuration in which a direct current (DC) voltage and an alternating current (AC) voltage are superimposed and applied to the developer carrier when supplying toner, wherein an AC bias is applied to the developer carrier. A voltage supply means for applying a superimposed voltage and a DC bias voltage; a discharge detection means for detecting a discharge between the development carrier and the latent image carrier; and a detection result from the discharge detection means; A control unit for changing and controlling the supply voltage in the voltage supply means, and the control unit stops the bias application in which the polarity is reversed with respect to the polarity detected in the discharge when the AC bias voltage is applied together with the discharge detection. Features In the developing device.

  According to the present invention, when the discharge is detected, the polarity of the AC developing bias that is applied after being reversed in polarity is stopped, so that the ozone or ions generated when the AC developing bias having the polarity before the polarity is reversed is applied. The reverse discharge phenomenon at the time of applying the AC developing bias after polarity reversal due to the presence of this can be suppressed. As a result, an increase in cost can be prevented by eliminating the need for a high breakdown voltage discharge element or the like.

1 is a schematic diagram for explaining an overall configuration of an image forming apparatus using a developing device according to an embodiment of the present invention. It is a schematic diagram for demonstrating the structure of the image development apparatus concerning embodiment of this invention. FIG. 2 is a perspective view illustrating an appearance of the developing device illustrated in FIG. 1. FIG. 3 is a schematic diagram for explaining an internal structure of the developing device shown in FIG. 2. FIG. 5 is a perspective view of a doctor blade used in the developing device shown in FIG. 4. FIG. 3 is a perspective view showing one end side with a lower case used in the developing device shown in FIG. 2 omitted. FIG. 3 is a perspective view of a developing roller used in the developing device shown in FIG. 2. It is a figure for demonstrating the surface shape of the developing roller shown in FIG. FIG. 3 is a perspective view showing a developer supply roller used in the developing device shown in FIG. 2. It is a schematic diagram which shows the opposing state of the developing roller and doctor blade of the developing device which concerns on embodiment of this invention. It is a block diagram for demonstrating the discharge detection structure used for the present image development bias control. 12 is a timing chart showing a state of discharge detection when a developing bias voltage is applied by a control board used for developing bias control shown in FIG. It is the figure which expanded a part of timing chart shown in FIG. FIG. 12 is a block diagram corresponding to FIG. 11 for explaining a main configuration of the developing device according to the embodiment of the present invention. FIG. 15 is a timing chart corresponding to FIG. 12 for describing a change in the developing bias voltage set by a control unit used in the configuration of the main part shown in FIG. 14. FIG. 16 is a block diagram corresponding to FIG. 14 for describing a modification of the main configuration shown in FIG. 15. FIG. 17 is a timing chart corresponding to FIG. 15 for explaining a change in the developing bias voltage set by a control unit used in the main configuration shown in FIG. 16.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
First, an image forming apparatus using the developing device according to the embodiment of the present invention will be described as follows.

Hereinafter, an embodiment in which the present invention is applied to a copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram of a copying machine 500. The copying machine 500 includes a copying machine main body (hereinafter referred to as a printer unit 100), a paper feed table (hereinafter referred to as a paper feed unit 200), and a scanner (hereinafter referred to as a scanner unit 300) mounted on the printer unit 100.

The printer unit 100 includes a process cartridge 1 (Y, M, C, K) as four process units, an intermediate transfer member that is stretched by a plurality of stretching rollers and moves in the direction of arrow A in FIG. A transfer belt 7, an exposure device 6 as an exposure unit, a fixing device 12 as a fixing unit, and the like are provided.
The suffixes Y, M, C, and K attached to the four process cartridges 1 indicate the specifications for yellow, magenta, cyan, and black. The four process cartridges 1 (Y, M, C, and K) have substantially the same configuration except that the colors of the toners to be used are different. Therefore, the subscripts K, Y, M, and C are omitted below. I will explain.

  The process cartridge 1 is a unit that integrally supports a photosensitive member 2 as a latent image carrier, a charging member 3 as a charging unit, a developing device 4 as a developing unit, and a photosensitive member cleaning device 5 as a cleaning unit. The configuration is shaped like Each process cartridge 1 can be attached to and detached from the copying machine 500 main body by releasing a stopper (not shown).

  The photoconductor 2 rotates in the clockwise direction in the figure as indicated by the arrow in the figure. The charging member 3 is a roller-shaped charging roller, is in pressure contact with the surface of the photoconductor 2, and is rotated by the rotation of the photoconductor 2. At the time of image formation, a predetermined bias is applied to the charging member 3 by a high voltage power source (not shown) to charge the surface of the photoreceptor 2. In the process cartridge 1 of the present embodiment, the roller-shaped charging member 3 that contacts the surface of the photoreceptor 2 is used as the charging unit, but the charging unit is not limited to this, and non-contact such as corona charging. A charging method may be used.

The exposure device 6 exposes the surface of the photoconductor 2 on the surface of the photoconductor 2 based on the image information of the original image read by the scanner unit 300 or image information input from an external device such as a personal computer. An electrostatic latent image is formed. The exposure device 6 provided in the printer unit 100 uses a laser beam scanner system using a laser diode, but may have other configurations such as an exposure unit using an LED array.
The photoconductor cleaning device 5 cleans the transfer residual toner remaining on the surface of the photoconductor 2 that has passed the position facing the intermediate transfer belt 7.

  The four process cartridges 1 form toner images for the respective colors of yellow, cyan, magenta, and black on the photoreceptor 2. The four process cartridges 1 are arranged in parallel in the surface movement direction of the intermediate transfer belt 7 and transfer the toner images formed on the respective photoreceptors 2 in order to be superimposed on the intermediate transfer belt 7 in order. A visible image is formed on the belt 7.

  In FIG. 1, a primary transfer roller 8 serving as a primary transfer unit is disposed at a position facing each photoconductor 2 across the intermediate transfer belt 7. A primary transfer bias is applied to the primary transfer roller 8 by a high voltage power source (not shown) to form a primary transfer electric field with the photosensitive member 2. By forming a primary transfer electric field between the photosensitive member 2 and the primary transfer roller 8, the toner image formed on the surface of the photosensitive member 2 is transferred to the surface of the intermediate transfer belt 7. One of a plurality of stretching rollers that stretch the intermediate transfer belt 7 is rotated by a drive motor (not shown), so that the intermediate transfer belt 7 moves in the direction of arrow A in the figure. A full color image is formed on the surface of the intermediate transfer belt 7 by sequentially transferring the toner images of the respective colors on the surface of the intermediate transfer belt 7 moving on the surface.

  With respect to the position where the four process cartridges 1 are opposed to the intermediate transfer belt 7, the intermediate transfer belt 7 is located on the downstream side in the surface movement direction with respect to the secondary transfer counter roller 9 a that is one of the stretching rollers. A secondary transfer roller 9 is disposed at a position opposed to the belt 7 and forms a secondary transfer nip with the intermediate transfer belt 7. A predetermined voltage is applied between the secondary transfer roller 9 and the secondary transfer counter roller 9a to form a secondary transfer electric field. A full color formed on the surface of the intermediate transfer belt 7 when the transfer paper P, which is a transfer material fed from the paper supply unit 200 and conveyed in the direction of arrow C in FIG. 1, passes through the secondary transfer nip. The image is transferred onto the transfer paper P by a secondary transfer electric field formed between the secondary transfer roller 9 and the secondary transfer counter roller 9a.

A fixing device 12 is disposed downstream of the secondary transfer nip in the conveyance direction of the transfer paper P. The transfer paper P that has passed through the secondary transfer nip reaches the fixing device 12, the full color image transferred onto the transfer paper P is fixed by heating and pressurization in the fixing device 12, and the transfer paper P on which the image is fixed is The data is output outside the copying machine 500.
On the other hand, the toner remaining on the surface of the intermediate transfer belt 7 without being transferred to the transfer paper P at the secondary transfer nip is collected by the transfer belt cleaning device 11.

As shown in FIG. 1, above the intermediate transfer belt 7, toner bottles 400 (Y, M, C, and K) that store toner of various colors are detachably disposed with respect to the copying machine 500 main body.
The toner stored in each color toner bottle 400 is supplied to each color developing device 4 by a toner replenishing device (not shown) corresponding to each color.

FIG. 2 is a schematic diagram showing a schematic configuration of the developing device 4 according to the present embodiment, and is a cross-sectional view seen from the back side of the paper surface in FIG.
FIG. 3 is a perspective explanatory view of the developing device 4 viewed obliquely from above.
The developing device 4 according to the present embodiment uses a non-magnetic one-component toner described later, the developing roller 42 and the photoreceptor 2 are arranged in a non-contact manner, and an AC voltage (AC voltage) and a DC voltage (DC voltage) are used as a developing bias. Is a developing device of a so-called non-magnetic one-component non-contact developing method. This will be described in detail below.
The developing casing 41 that forms the outer shape of the developing device 4 is formed by combining an upper case 411, an intermediate case 412, and a lower case 413. The middle case 412 forms a toner accommodating portion 43, and the upper case 411 is formed with a toner replenishing port 55 that is a developer replenishing portion that communicates the toner accommodating portion 43 with the outside. The upper case 411 is provided with an inlet seal 47 that seals a gap between the developing roller 42 and the upper case 411.

  FIG. 4 is a cross-sectional explanatory view of the developing device 4 viewed from the same direction as FIG.

The middle case 412 is provided with a developing roller 42, a supply roller 44, a doctor blade 45, a paddle 46, a supply screw 48, a remaining toner sensor 49, and the like.
The developing device 4 is provided with an opening 56 that communicates the inside and the outside along the longitudinal direction (Y-axis direction in the figure). A cylindrical developing roller 42 is provided in the opening 56 to carry and carry the toner from the inside to the outside (developing area α facing the photoconductor).

  FIG. 6 is an enlarged perspective view of the vicinity of one end (the rear end in FIG. 2) of the developing device 4 in which the lower case 413 is not shown.

In the developing device 4, the supply roller 44 rotates and moves in the direction of arrow C in FIG. 2 (clockwise direction in FIG. 2), so that the toner T in the toner storage portion 43 faces the developing roller 42. Then, the toner is supplied to the surface of the developing roller 42. The developing roller 42 carries the supplied toner on the surface, rotates in the direction of arrow B in FIG. 2 (clockwise direction in FIG. 2), and moves on the surface, thereby removing the toner on the developing roller 42. The toner is conveyed to a portion facing the doctor blade 45 that is regulated to a predetermined amount. The toner regulated to a predetermined amount at the portion facing the doctor blade 45 reaches the developing area α which is the portion facing the photoreceptor 2 by the rotation of the developing roller 42.
In the supply nip β, the surface of the supply roller 44 moves from below to above, and the surface of the developing roller 42 moves from above to below.

In the development region α, development is performed in accordance with a development electric field formed by a potential difference between a development bias applied to the development roller 42 from a development bias power source 142 having an AC power source and a DC power source and a latent image on the surface of the photoreceptor 2. The toner T on the surface of the roller 42 moves to the surface of the photoreceptor 2, the toner adheres to the electrostatic latent image portion on the surface of the photoreceptor 2, and development is performed.
The photoreceptor 2 rotates in the direction of arrow D in FIG. 2 without contact with the developing roller 42. For this reason, in the development area α, the surface movement direction of the developing roller 42 and the surface movement direction of the photosensitive member 2 are the same direction.
The developing bias power supply 142 also includes a first voltage for directing the toner from the developing roller 42 to the photosensitive member 2 and developing roller from the photosensitive member 2 to developing the latent image with the toner conveyed to the developing region α. An alternating voltage constituting an oscillating electric field by a second voltage for directing the toner to 42 is applied.
In this embodiment, the developing bias power supply 142 having an AC power supply and a DC power supply is used. However, for example, an AC power supply and a DC power supply are provided separately, or other devices in the image forming apparatus are provided for the AC power supply or the DC power supply. For example, a power source shared with a charging device or a transfer device may be used.

Although details are shown in FIG. 10, the surface of the developing roller 42 has a regular uneven shape in which the height of the convex portion 42a and the depth of the concave portion 42b are substantially constant.
The toner T on the surface of the developing roller 42 that does not contribute to development in the developing area α and passes through the developing area α is collected by the supply roller 44 at the supply nip β, and the surface of the developing roller 42 is reset.

  The toner T carried in the concave portions 42b regularly formed on the surface of the developing roller 42 is difficult to be collected. Then, when the toner T that has passed through the developing region α passes through the supply nip β and remains carried on the developing roller 42, the toner T adheres to the developing roller 42 and toner filming occurs. When toner filming occurs, the charge amount per unit weight of the toner T on the developing roller 42 and the toner amount per unit area of the developing roller 42 become unstable, causing density unevenness during development.

  In the developing device 4 according to this embodiment, the surface movement direction of the developing roller 42 and the surface movement direction of the supply roller 44 are opposite in the supply nip β where the developing roller 42 and the supply roller 44 face each other. As a result, the linear velocity difference between the surface of the developing roller 42 and the surface of the supply roller 44 at the supply nip β is increased, and the recovery performance of the supply roller 44 at the supply nip β can be improved. Therefore, it is possible to suppress the toner from being held on the developing roller 42, to suppress the toner from adhering to the surface of the developing roller 42, and to cause the developer to adhere to the surface of the developer carrying member. Occurrence of density unevenness during development can be suppressed.

  Further, as shown in FIG. 2, in the developing device 4, the supply roller 44 is disposed above the toner storage portion 43, and at least a part of the supply roller 44 is in the toner storage portion 43 in a state where the rotation of the paddle 46 is stopped. The surface is above the surface of the toner T. An area downstream of the supply nip β with respect to the surface movement direction of the supply roller 44 (hereinafter referred to as a supply nip downstream area) is above the surface of the toner T. When the toner is filled in the downstream area of the supply nip as in the configuration described in FIG. 3 of Patent Document 3, the toner filled in the downstream area of the supply nip is replaced with new toner in the downstream area of the supply nip. This may hinder entry of toner and reduce the efficiency of collecting toner from the developing roller 42 in the supply nip β.

  On the other hand, in the developing device 4 according to the present embodiment, as shown in FIG. 2, the downstream area of the supply nip is above the surface of the toner T, and therefore the downstream area of the supply nip is filled with toner. In addition, the toner existing in the downstream area of the supply nip is not hindered from the recovery of the toner from the developing roller 42 in the supply nip β, so that the toner can be recovered efficiently and the toner is reset. Can be improved.

Further, as shown in FIG. 10, the contact state of the doctor blade 45 with the surface of the developing roller 42 allows the toner T present on the top surface of the convex portion 42a to be worn out when the tip blade is in contact. More preferable.
In the tip contact, the doctor blade 45 is brought into contact with the developing roller 42 in an edge contact state. Here, the edge contact is a state in which an edge portion forming a ridge line between the facing surface 45b and the tip surface 45a of the doctor blade 45 is in contact with the surface (convex surface) of the developing roller 42.
Here, in the edge portion forming the ridge line, the ridge line may be rounded or chamfered.

The vicinity of the place where the surface which extended the opposing surface of the doctor blade and the tip surface intersects is shown.
Specifically, the corner of the developing roller side at the free end of the flat doctor blade (which may be rounded or chamfered) should come into contact with the convex portion of the developing roller. It ’s fine.
Here, there is a method in which the blade is bent and the bent portion is brought into contact with each other. However, it is preferable that the tip on the free end side is brought into contact with the effect of scraping off the toner.

Next, the developing roller 42 will be described.
FIG. 7 is a perspective explanatory view of the developing roller 42. 8 is an explanatory view of the surface shape of the developing roller 42, FIG. 8A is a schematic view of the entire developing roller 42, and FIG. 8B is shown in FIG. 8A. 3 is an enlarged view of a part of the surface of the developing roller 42. FIG.

The developing roller 42 has a configuration in which a developing roller cylindrical portion 420 that carries toner on the surface thereof is provided on the developing roller shaft 421, and the developing roller shafts in the vicinity of both axial end portions that are axially outside the developing roller cylindrical portion 420. A spacer 422 is provided at 421.
The developing roller 42 is provided so as to be rotatable about the developing roller shaft 421, and is arranged so that the axial direction of the developing roller shaft 421 is parallel to the longitudinal direction (Y-axis direction in the drawing) of the developing device 4. Yes. Both ends of the developing roller shaft 421 in the axial direction of the developing roller 42 are rotatably attached to the side wall portion 412s of the middle case 412. A part of the surface of the developing roller 42 is exposed to the outside of the developing device 4 from the opening 56, and the developing roller 42 is moved from the lower side to the upper side to convey the toner so that the toner is conveyed in FIG. It rotates in the direction of arrow B.
Further, in the developing roller 42, the distance between the surface of the developing roller cylindrical portion 420 and the surface of the photosensitive member 2 in the developing region α is obtained by the spacers 422 provided in the vicinity of both ends in the axial direction contacting the surface of the photosensitive member 2. (Development gap) is kept constant.

The developing roller 42 is a member made of aluminum alloy, iron alloy, or the like.
As shown in FIG. 8A, the developing roller cylindrical portion 420 of the developing roller 42 is mainly divided into two portions (a groove forming portion 420a and a non-groove forming portion 420b) based on the difference in the structure of the surface thereof. .
The groove forming portion 420a is a portion including a central portion in the axial direction of the developing roller 42, and is provided with a concavo-convex process on the surface thereof in order to properly carry the toner. In the present embodiment, a so-called rolling process is used as the concavo-convex process, and the convex portion 42a is formed by being surrounded by spiral first grooves L1 and second grooves L2 having different winding directions. In the developing roller 42 of the present embodiment, the pitch width W1 in the axial direction of the convex portion 42a is 80 [μm], and the axial length W2 of the top surface of the convex portion 42a is 40 [μm]. Furthermore, the depth of the recess, which is the height from the recess 42b to the top surface of the projection 42a, is 10 [μm]. The values of the pitch width W1, the axial length W2 of the top surface, and the depth of the recess are examples, and are not limited to these values.

  The surface of the developing roller 42 is preferably made of a material that normally charges the toner. Even when a low-charged toner is produced by filming, the low-charged toner knocked out by the jumped toner T can be charged at the portions where the convex portions 42a and the concave portions 42b are not filmed. It can be reduced and the image density is stabilized.

  Further, it is desirable that the surface material of the developing roller 42 is harder than the doctor blade 45 (blade member 450). Accordingly, the convex portion 42a on the surface of the developing roller 42 is difficult to be scraped off by the doctor blade 45, so that the volume of the convex portion 42a and the concave portion 42b surrounded by the doctor blade 45 is difficult to change, and the M / A value (on the surface of the developing roller) The amount of toner carried per unit area) is stabilized.

  The height of the convex portion 42a of the developing roller 42 is desirably larger than the weight average particle diameter of the toner T to be used. Since the toner T having an average size is accommodated in the recess 42b, the selection of the particle size is difficult to occur, and the M / A value (the amount of toner carried per unit area on the surface of the developing roller) is stabilized over time. .

Next, the supply roller 44 will be described.
FIG. 9 is an explanatory perspective view of the supply roller 44. A cylindrical supply roller 44 is provided on the developing roller 42 side above the toner container 43 inside the developing device 4. The supply roller 44 has a configuration in which a cylindrical foam material is wound around a supply roller shaft 441 that is a shaft portion thereof, and the cylindrical foam material becomes a supply roller cylindrical portion 440 that carries toner on the surface thereof. .

The supply roller 44 is configured to be rotatable about a supply roller shaft 441, and the shaft is attached to the side wall portion 412 s of the middle case 412 so as to be rotatable. The supply roller 44 is disposed so that a part of the outer peripheral surface of the supply roller cylindrical portion 440 is in contact with the outer peripheral surface of the developing roller cylindrical portion 420 of the developing roller 42 at the supply nip β. As shown, the supply roller shaft 441 is disposed above the developing roller shaft 421.
Further, as described above, the supply roller 44 rotates so that the surface moves in the direction opposite to the surface movement direction of the developing roller 42 at the supply nip β that is a portion facing the developing roller 42. Further, as shown in FIG. 1, the developing device 4 is arranged such that the position of the supply nip β is located above the contact position of the doctor blade 45 with respect to the developing roller 42.

  The supply roller 44 uses a foam material for the supply roller cylindrical portion 440, and the surface layer in contact with the developing roller 42 is a sponge layer in which a large number of micropores are dispersed on the surface. By making the surface layer of the supply roller 44 into a sponge shape, the supply roller 44 can easily reach the bottom of the recess 42b, so that the resetability of the toner on the developing roller 42 is improved.

  Further, the amount of biting of the supply roller 44 with respect to the development roller 42 (“radius of the development roller 42” + “radius of the supply roller 44” − “distance between the axes of the development roller 42 and the supply roller 44”) It is set to be larger than the height of the convex portion 42a. By making the amount of biting of the supply roller 44 larger than the height of the convex portion 42a, the toner resetting property in the concave portion 42b can be improved. Note that if the amount of biting of the supply roller 44 with respect to the developing roller 42 is too large relative to the height of the convex portion 42a, the toner will be pushed into the concave portion 42b and cause aggregation, so the amount of biting will not be too large. It is necessary to set as follows.

The foam material used for the supply roller cylindrical portion 440 of the supply roller 44 is set to an electric resistance value of 10 ³ to 10 ¹⁴ [Ω].
A supply bias is applied to the supply roller 44 by a supply bias power supply 144 to assist the operation of pressing the toner preliminarily charged at the supply nip β against the developing roller 42. The supply roller 44 rotates in the clockwise direction in FIGS. 1 and 5 to apply and supply the developer adhered on the surface to the surface of the developing roller 42.

  The voltage applied to the supply roller 44 by the supply bias power supply 144 is opposite to the normal charging polarity of the toner (negative polarity in the toner T of the present embodiment) with respect to the alternating voltage applied to the developing roller 42. Apply polarity (positive polarity) DC voltage. At this time, the voltage applied to the supply roller 44 is opposite in polarity (plus polarity) to the normal charging polarity of the toner than the voltage applied to the developing roller 42. As a result, an electric field in the direction in which the toner T is attracted toward the supply roller 44 with respect to the development roller 42 is formed in the supply nip β, and the resetability of the toner on the development roller 42 can be improved. Note that the configuration including the supply bias power supply 144 requires a separate DC power supply, which increases the cost. Therefore, the supply bias power supply 144 may not be provided according to the specifications of the developing device 4.

Next, the doctor blade 45 will be described.
As shown in FIG. 4, a doctor blade 45 is provided in the middle case 412 which is below the developing roller 42 and is inside the lower case 413.
As shown in FIG. 5, the doctor blade 45 includes a blade member 450 that is a thin plate-like metal member, and a metal base portion 452 to which one end of the blade member 450 is fixed. The other end side of the blade member 450 is configured to come into contact with the developing roller 42. The contact state of the blade member 450 with respect to the developing roller 42 may be either a tip contact state in which the tip contacts or a stomach contact state in which the surface portion on the base side from the tip contacts. However, in the state where the front end of the figure is in contact, the toner present on the top surface of the convex portion 42a can be worn out, and only the toner present in the concave portion 42b is conveyed to the developing region α to be conveyed to the developing region α. This is more preferable because the toner amount is stable.

  The blade member 450 of the doctor blade 45 is fixed to the pedestal portion 452 by a plurality of rivets 451. The pedestal portion 452 is made of a metal that is thicker than the blade member 450 and functions as a substrate for fixing the blade member 450 to the main body of the developing device 4 (side surface portion of the middle case 412). A pin hole 454 is provided at the longitudinal end of the pedestal portion 452, one is a perfect circular main reference hole 454 a, and the other is an elliptical secondary reference hole having a long diameter in the direction of the main reference hole 454 a. 454b. When a pin (not shown) enters the main reference hole 454a, the position of the pedestal portion 452 with respect to the main body of the developing device 4 is determined and supported by the sub reference hole 454b. The pedestal portion 452 to which the blade member 450 is fixed is fixed to the developing device 4 main body (inner case 412) with a doctor fixing screw 455, whereby the blade member 450 is fixed to the developing device 4.

  The blade member 450 of the doctor blade 45 is made of a metal plate spring material such as SUS304CSP, SUS301CSP, or phosphor bronze, and the free end is brought into contact with the surface of the developing roller 42 with a pressing force of 10 to 100 [N / m]. Therefore, the toner passing under the pressing force is regulated to a predetermined amount and charged by frictional charging. Further, a bias is applied to the blade member 450 from a doctor bias power source 145 to assist frictional charging.

  The blade member 450 of the doctor blade 45 is desirably conductive. Since the blade member 450 is conductive, the charge amount of the toner T having a large Q / M value (charge amount per unit volume) can be lowered, and the Q / M value of the toner T can be made uniform. it can. Thereby, sticking of the toner T to the developing roller 42 can be prevented.

  The voltage applied to the doctor bias power supply 145 blade member 450 is configured such that a DC voltage can be applied in the range of ± 200 [V] with respect to the alternating voltage applied to the developing roller 42, and the DC voltage depends on the usage environment. It may be configured to control the value of. Thereby, it is possible to suppress fluctuations in the M / A value (toner carrying amount per unit area on the surface of the developing roller) due to environmental fluctuations.

Next, the paddle 46 will be described.
In the developing device 4, as shown in FIG. 4, a toner accommodating portion 43 is provided as a space for accommodating toner, and a paddle 46 is rotatable relative to the developing casing 41 in the toner accommodating portion 43. Is attached.

The paddle 46 includes a paddle shaft that is a shaft portion thereof, and paddle wings as thin wing members made of an elastic sheet material such as Mylar. The paddle shaft has two flat portions facing each other, and paddle feathers are attached to the two flat portions, respectively. The two paddle feathers are fixed to the flat portion of the paddle shaft so as to protrude in opposite directions around the paddle shaft.
The base portion of the paddle wing is provided with a plurality of holes arranged so as to be parallel to the axial direction of the paddle shaft, and the paddle shaft is provided with a plurality of convex portions arranged so as to be parallel to the axial direction of the paddle shaft. ing. Then, the paddle wing is fixed to the paddle shaft by inserting the convex portion of the paddle shaft into the hole of the paddle wing and performing heat caulking.

  The paddle 46 is disposed so that the axial direction of the paddle axis is parallel to the longitudinal direction of the developing device 4 (Y-axis direction in FIG. 6). Both ends in the axial direction of the paddle shaft are rotatably attached to the side wall portion 412s of the middle case 412.

In the paddle 46, the amount of protrusion of the paddle wing is set to such a length that the tip of the paddle wing extending from the paddle shaft comes into contact with the inner wall surface of the toner containing portion 43. As shown in FIGS. 1 and 6, the bottom surface portion 43 b of the toner accommodating portion 43 has an arc shape along the rotation direction of the paddle 46, and the paddle blades of the toner accommodating portion 43 are rubbed by the rubbing operation accompanying the rotation of the paddle 46. The bottom portion 43b is not caught.
A side wall surface portion 43s that rises perpendicularly from the bottom surface portion 43b is formed on the developing roller 42 side of the toner containing portion 43. The side wall surface portion 43s is a roller parallel to the X axis at a level that is equal to or slightly lower than the center of the paddle shaft. The step 50 is formed in a horizontal direction.

  The distance between the side wall surface portion 43s and the paddle shaft is set shorter than the distance between the bottom surface portion 43b and the paddle shaft. For this reason, the paddle feather that has rubbed the bottom surface portion 43b hits the side wall surface portion 43s and bends more greatly. Thereafter, when the leading end of the paddle wing approaches the stepped portion 50, there is nothing to hold the paddle wing, and the leading end of the paddle wing jumps upward by being released. By such movement of the paddle wing, the toner is splashed upward, stirred, transported and supplied.

  The step portion 50 is a horizontal plane parallel to the XY plane, and is formed to extend in the longitudinal direction of the developing device 4 (Y-axis direction in the drawing). In the developing device 4 according to the present embodiment, the stepped portion 50 is provided in the entire region in the width direction, but may be provided in a part of the developing device 4 as long as the paddle blades jump up.

  The supply screw 48 is a screw member that becomes a supply screw shaft 481 and a supply screw blade portion 480 which is a spiral blade portion fixed to the supply screw shaft 481. The supply screw shaft 481 is provided so as to be rotatable, and the axial direction of the supply screw shaft 481 is arranged so as to be parallel to the longitudinal direction of the developing device 4 (Y-axis direction in the drawing). Both axial ends of the supply screw shaft 481 are rotatably attached to the side wall portion 412s of the middle case 412.

  The end of the supply screw 48 in the axial direction is positioned below a toner supply port 55 formed at the end of the developing device 4 in the longitudinal direction. Then, when the supply screw 48 is rotated, the spiral supply screw blade 480 conveys the toner replenished from the toner replenishing port 55 toward the central portion of the developing device 4 in the longitudinal direction.

  A sheet member such as Mylar is attached as an inlet seal 47 along the longitudinal direction to the edge portion forming the opening 56 of the upper case 411. The inlet seal 47 is a substantially rectangular sheet, one end of which is affixed to the edge portion of the upper case 411, and the other end is a free end. The free end side of the inlet seal 47 protrudes toward the inside of the developing device 4, and is further provided so as to contact the developing roller 42. The inlet seal 47 is fixed to the upper case 411 on the upstream side in the rotational direction of the developing roller 42, and the downstream side in the rotational direction of the developing roller 42 is a free end, and the surface portion of the inlet seal 47 contacts the developing roller 42. It is arranged to do. Further, the inner side of the developing device 4 of the upper case 411 is curved so as to follow the upper shape of the supply roller 44, and the gap between the curved surface of the upper case 411 and the surface of the supply roller 44 is 1 0.0 [mm].

As shown in FIG. 6, side seals 59 are attached to a part of the middle case 412 corresponding to both ends in the longitudinal direction of the opening 56 of the developing device 4. The side seal 59 is provided on the inner side in the axial direction with respect to the spacer 422 provided in the vicinity of both ends in the axial direction of the developing roller 42, and in a region where the axial end where the doctor blade 45 contacts the developing roller 42 overlaps. ing. Such a side seal 59 prevents the toner from leaking from the end portion in the longitudinal direction of the opening 56 in the developing casing 41.
A remaining toner sensor 49 provided in the middle case 412 detects the amount of toner in the toner storage unit 43.

Next, the movement of toner in the developing device 4 will be described with reference to FIG.
The toner replenished into the developing device 4 from the toner replenishing port 55 is supplied to the toner accommodating portion 43 by the supply screw 48 and stirred by the paddle 46. Further, the paddle 46 is flipped up in the direction of the developing roller 42 and the supply roller 44 and conveyed. The toner supplied to the supply roller 44 is delivered to the surface of the developing roller 42 at a supply nip β where the supply roller 44 contacts the developing roller 42. Of the toner delivered to the surface of the developing roller 42, the amount of toner exceeding a predetermined amount conveyed to the developing area α is scraped off from the surface of the developing roller 42 by the doctor blade 45.

  The toner remaining on the surface of the developing roller 42 that has passed through the portion facing the doctor blade 45 is conveyed as it is by the surface movement method by the rotation of the developing roller 42, and reaches the developing region α facing the photoreceptor 2. The toner that has passed through the development region α without being used for development passes through a position where the inlet seal 47 contacts, and is conveyed to the supply nip β that is a position facing the supply roller 44. The toner that has reached the supply nip β by the developing roller 42 is scraped off from the surface of the developing roller 42 by the supply roller 44 and conveyed by the supply roller 44.

Next, the developer used in the copying machine 500 according to the present embodiment will be described. The developer may be composed only of toner, or an external additive may be added for the purpose of improving developability.
As the toner used in the copying machine 500, a toner having high fluidity is used so as to be compatible with high-speed toner conveyance. Specifically, a toner having an accelerated aggregation degree of 40% or less is used. The accelerated aggregation degree is an index indicating the fluidity of the toner.

A method for measuring the accelerated aggregation degree of the toner is shown below.
<Measurement device>
・ Powder tester made by Hosokawa Micron <Measurement method>
・ Leave the sample to be measured in a thermostat (35 ± 2 [° C], 24 ± 1 [h])
・ Measured with a powder tester ・ Three types of sieves with different openings (for example, 75 [μm], 44 [μm], 22 [μm])
-Calculate from the remaining amount of toner when sieving, and obtain the degree of aggregation by the following calculation.
{(Weight of toner remaining on upper screen) / (sample amount)} × 100
{(Weight of toner remaining on middle screen) / (sample amount)} × 100 × 3/5
{(Weight of toner remaining on lower screen) / (sample amount)} × 100 × 1/5
The total of the above three calculated values is defined as the heat aggregation degree [%].

  As described above, the accelerated aggregation degree of the toner is an index obtained by stacking three types of meshes having different openings in the order of increasing openings, placing particles on the uppermost stage, sieving with constant vibration, and calculating from the toner weight on each mesh. .

In this embodiment, toner having an average circularity of 0.90 or more (0.90 to 1.00 toner) is used.
In this embodiment, the value obtained from the following equation (1) is defined as the circularity a. This circularity is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere, and the circularity becomes smaller as the surface shape becomes more complicated.
Circularity a = L ₀ / L (1)
(L ₀ : circumference of a circle having the same projected area as the particle image, L: circumference of the projected image of the particle)

When the average circularity is in the range of 0.90 to 1.00, the surface of the toner particles is smooth, and the contact area between the toner particles and between the toner particles and the photoreceptor 2 is small, so that the transferability is excellent.
When the average circularity is in the range of 0.90 to 1.00, since the toner particles have no corners, the developer (toner) agitation torque in the developing device 4 is small, and the agitation drive is stabilized. Can be prevented.
In addition, since there are no angular toner particles in the toner that forms the dots, when the pressure is brought into contact with the transfer medium during transfer, the pressure is uniformly applied to the entire toner that forms the dots, and the transfer is not easily lost.
Further, since the toner particles are not angular, the abrasive power of the toner particles itself is small, and it is possible to prevent the surfaces of the photoreceptor 2 and the charging member 3 from being damaged or worn.

  Next, a method for measuring the circularity will be described. The circularity can be measured using a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics.

  As a specific measuring method, a surfactant, preferably an alkylbenzene sulfonate, is added in an amount of 0.1 to 0.5 [100] as a dispersant in 100 to 150 [ml] of water from which impure solids have been removed in advance. ml] and about 0.1 to 0.5 [g] of a measurement sample is further added. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the shape and particle size of the toner are measured with the above apparatus with the dispersion concentration being 3000 to 10,000 [pieces / μl].

  In order to reproduce minute dots of 600 [dpi] or more, the weight average particle diameter (D4) of the toner is preferably 3 to 8 [μm]. In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent. When the weight average particle diameter (D4) is less than 3 [μm], phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties tend to occur.

  When the weight average particle diameter (D4) exceeds 8 [μm], it is difficult to suppress scattering of characters and lines. Moreover, it is preferable that ratio (D4 / D1) of a weight average particle diameter (D4) and a number average particle diameter (D1) exists in the range of 1.00-1.40. The closer (D4 / D1) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

  Next, a method for measuring the particle size distribution of toner particles will be described. Examples of the measuring device for the particle size distribution of toner particles by the Coulter counter method include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.

  First, 0.1 to 5 [ml] of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 [ml] of the electrolytic aqueous solution. Here, the electrolytic solution is prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride, and for example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 [mg] of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the weight and number of toner particles or toner using a 100 [μm] aperture as the aperture. Then, the weight distribution and the number distribution are calculated. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

  As a channel, it is less than 2.00-2.52 [micrometer]; 2.52-less than 3.17 [micrometer]; 3.17-less than 4.00 [micrometer]; 4.00-5.04 [micrometer] Less than 5.04 to 6.35 [μm]; 6.35 to less than 8.00 [μm]; 8.00 to less than 10.08 [μm]; 10.08 to less than 12.70 [μm]; 12.70 to less than 16.00 [μm]; 16.00 to less than 20.20 [μm]; 20.20 to less than 25.40 [μm]; 25.40 to less than 32.00 [μm]; Using 13 channels of 00 to less than 40.30 [μm], particles having a particle size of 2.00 [μm] or more to less than 40.30 [μm] are targeted.

  The toner used in the exemplary embodiment is obtained by crosslinking a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent in an aqueous solvent. And / or a toner obtained by an extension reaction, and is called a polymerized toner. 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 polyhydric alcohol (PO) and polycarboxylic acid (PC) is heated to 150 to 280 [° C.] in the presence of a known esterification catalyst such as tetrabutoxy titanate or dibutyltin oxide, and reduced in pressure as necessary. The produced water is distilled off while obtaining 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; phenol derivatives, oximes, polyisocyanates; 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 polyisocyanate 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 is deteriorated, 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 polyhydric carboxylic acid (PC) are produced in the presence of a known esterification catalyst such as tetrabutoxy titanate and dibutyltin oxide at 150 to 280 [° C.] and, if necessary, reduced pressure. Water is distilled off to obtain a polyester having a hydroxyl group. Next, at 40 to 140 [° C.], this is reacted with polyvalent isocyanate (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. Further, this (A) is reacted with amines (B) at 0 to 140 [° C.] to obtain a urea-modified polyester.

  When reacting the polyvalent isocyanate compound (PIC) and when reacting (A) and (B), a solvent may be used as 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 Inactive to polyvalent isocyanate compounds (PIC) such as benzene (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 copying machine 500 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 the temperature 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.

<Colorant>
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 Carmine B, 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% [%], preferably 3 to 10% [%] 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 42 is increased, the developer fluidity is reduced, and the image density is reduced. Incurs a decline.

<Release agent>
As the release agent, a low melting point wax having a melting point of 50 to 120 [° C.] is more effectively used as a release agent in the dispersion with the binder resin between the fixing roller of the fixing device 12 and the toner interface. It works against high temperature offset without applying a release agent such as oil to the fixing roller. 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, 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], 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 an average particle diameter of both fine particles of 5 × 10 ⁻² [μm] or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even with the stirring and mixing in the developing device 4 performed to obtain the charge level, the fluidity imparting agent is not detached from the toner, and good image quality that does not cause firefly is obtained. Reduction is achieved.

  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 addition 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. Stable image quality can be obtained even when copying is repeated.

  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 salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, fatty acid amide derivatives, polyhydric alcohols 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).

  In addition, examples of the cationic surfactant include aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. , Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent 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 which exists on the surface of a toner base particle becomes the range of 10-90 [%]. 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 name is PB- 200H (manufactured by Kao Corporation), SGP (manufactured by Sokensha), technopolymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.) and the like.

  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, in order to make the particle size of the dispersion 2 to 20 [μm], a high-speed shearing method is preferable. When a high-speed shearing disperser is used, the number of rotations 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 between the isocyanate group structure of the polyester prepolymer (A) and 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 features of the present embodiment will be described below for the configuration as described above.
In the developing device according to the present embodiment, as shown in FIG. 2, a gap is provided between the photosensitive member 2 and the developing roller 42 in the developing region α where the photosensitive member 2 and the developing roller 42 are opposed to each other, so that no contact is made. The development method is executed.
In this embodiment, when applying AC and DC voltages superimposed on the development bias when a non-contact one-component developer is used, attention is paid to discharges with positive and negative outputs at the AC voltage. When switching from positive output to negative output due to the presence of ozone or ions generated during discharge, reverse discharge from the photoconductor side to the developing roller side occurs due to the presence of the above substances. It is characterized in that it is prevented by stopping the output.

FIG. 11 is a block diagram for explaining the discharge detection configuration used in the current development bias control. In FIG. 11, the development device provided in the image forming unit for one color is shown. The developing roller 42 is shown as an object.
The developing roller 42 is connected to an AC power source and a DC power source provided in a high voltage power supply board 1001 used as a voltage supply unit for applying a developing bias voltage, and a discharge current detection unit serving as a discharge detecting unit is connected to the developing bias application unit. A circuit 1002 is connected.
The voltage supply means and the discharge current detection circuit 1002 are configured such that the applied voltage value and detection timing are controlled by the control board 1000 used in the control unit. Specifically, the PWM signal output from the control board Is used.
The PWM signal is indicated by a positive duty value based on a 20 KHz pulse.
That is, when the duty is 0%, the output is in an off state, and the output and the duty ratio are set such that the output is set from 5% to the minimum output at which the output is turned on and set to the maximum output at 100%. Used in a proportional relationship.

The high voltage power supply board 1001 is equipped with a discharge current detection circuit 1002 so as to detect an instantaneous discharge current.
The signal from the discharge current detection circuit 1002 is used for reading on the control board 1000 by generating a feedback signal having a signal width of 30 ms using a timer.
The control board 1000 polls (samples) the feedback signal at a cycle of 10 ms, and determines that there is a discharge when the discharge detection signal is read twice. A filter function that does not erroneously detect in-flight noise is provided by using two consecutive signals for determination.

FIG. 12 is a timing chart showing a state of discharge detection when a development bias voltage is applied by the control board 1000 shown in FIG. 11. In FIG. 12, when discharge detection is started, the DC development bias is determined. In 22, −300 V is set with a duty of 60% from OFF.
After the DC bias is stabilized, the AC bias is determined, and in the case of FIG. 12, 1600 V is set at a duty of 85%.
With the above bias condition setting, the discharge detection operation becomes effective, and in FIG. 12, polling is started based on 10 ms. However, since reading on the control board 100 is not started, the feedback signal is active or inactive. There is no problem.

On the other hand, the discharge detection signal reading on the control board 1000 is executed as a detection time in which the longer period of one round of the photoreceptor or one round of the developing roller is set in the timer, and the developing roller surface potential (Vac) is changed during this period. There is no such thing. In FIG. 12, the detection time (timer) is set to 700 ms.
When there is no discharge during the detection time (700 ms), the output of the developing bias is shifted to increase one step. In FIG. 12, the shift is performed in increments of 2.5%, such as 85% to 87.5%.
In FIG. 12, when the output of the developing bias is shifted and a discharge occurs during a 90% duty, 19800V positive output, a detection signal of 1 μs or less and a feedback signal of 30 ms are generated.

In the control board 1000, when a feedback signal of 30 ms is generated, it is counted by polling at a cycle of 10 ms, and when it is counted twice, it is determined that the discharge is on the normal positive output side, the internal determination FLAG is turned on, and so-called abnormality determination It means not.
On the other hand, based on the determination result described above, the discharge limit voltage is determined to be 87.5% duty, 1650 V, and a voltage obtained by reducing the fluctuation margin voltage from 1650 V is set as the development bias voltage at the start of printing.

FIG. 13 is an enlarged view of the time point when the discharge shown in FIG. 12 occurs. In FIG. 13, at the position where the discharge occurs, the potential difference between Vac (+) and Vd = (Vac / 2) + Vb−Vd. = 900 + (− 300) − (− 700) = 1300V.
At this time, since a large current flows instantaneously, as shown in the figure, the flat portion of Vac falls instantaneously at the discharge position, but returns to the original state by the control inside the power supply.
On the other hand, on the surface of the photoconductor, charges are injected into a portion corresponding to the position where the discharge occurs, that is, the discharge local portion. Therefore, as shown by a dashed line in FIG. 23, Vd = −700V to V _L = −50V Suddenly changes. In FIG. 13, an arrow F1 indicates a state in which the voltage changes due to a discharge due to a potential difference.

Discharge traces at the discharge local portion are vertically elongated by 4 to 5 mm in the axial direction and 2 to 3 mm in the rotation direction and are horizontally long and have a developing nip where the developing roller 42 and the photosensitive member 2 face each other. In addition, ozone and ions due to discharge drift in this region, so that it flows in the downstream direction due to the airflow due to roller rotation, but immediately after the discharge, it drifts in the development nip, that is, the range where the development bias acts.
For this reason, when the developing bias voltage is inverted from the positive output to the negative output, the potential difference between the developing bias voltage (Vac (−)) and the non-image portion potential (V _L ) on the surface of the photoconductor changed in the non-image portion. It becomes remarkable and reaches about 1150V as shown in the figure.

  When ozone or ions are not present in the development nip, the discharge limit is 1300 V, whereas when molecules are present, the discharge voltage is reduced by 20 to 30%, and discharge occurs even at this level of voltage. In other words, the inventor has confirmed that discharge occurs when the bias voltage is output after polarity inversion.

  In such a current situation, since the discharge detection circuit originally considers that only the positive discharge is detected, no consideration has been given to reverse discharge, and it is considered that reverse discharge is possible. In some cases, it may be necessary to have a circuit configuration that targets both discharges, or only the positive discharge is effective and the reverse discharge is ignored. However, with respect to the former point, there is a problem that the circuit configuration is complicated, and with respect to the latter point, there is a problem that the cost is increased by using a diode having a high reverse withstand voltage.

In the present embodiment, in view of the problems in the current discharge detection described above, the problems are solved. Hereinafter, a specific configuration will be described.
The feature of this embodiment is that the reverse discharge does not occur if the development bias voltage cannot be reversed from the positive output to the negative output, and the clock (CLK) signal generating the AC bias voltage (Vac) is positive. It is characterized in that it is stopped when a discharge occurs at the output.

In FIG. 14, an AND gate is incorporated in the clock (CLK) signal, and when the feedback signal becomes active, the AND gate is closed to stop the negative output that is inverted from the positive output in the AC bias voltage. ing.
As a result, only the positive electrode output is used as the AC bias voltage.
The above-described control is effective when the photosensitive member and the developing roller are stopped, but since both of them are actually rotating, after a few ms, a new one is passed when passing through the discharge mark in the developing nip. When the surface of the photosensitive member appears, a potential difference of 1300 V is generated in the developing nip portion as shown in FIG. 23, and the discharge limit is reached. Therefore, for this control, when the feedback signal is taken in the control board 1000, it is desirable to reduce the duty of the PWM signal so that the AC bias voltage (Vac) and the DC bias voltage (Vb) are quickly reduced.

FIG. 15 is a timing chart showing a state of voltage change at the time of discharge detection by the configuration shown in FIG.
In the figure, reverse discharge is maintained by maintaining the positive output from the time when discharge occurs at the positive output (Vac (+)) of the AC bias voltage (Vac) among the development bias voltages. The occurrence of is open. At this time, as described above, the values of the AC bias voltage (Vac) and the DC bias voltage (Vb) by the PWM signal are also lowered.

FIG. 16 is a block diagram showing a modification of the main part of the configuration shown in FIG.
In the configuration shown in the figure, unlike the case shown in FIG. 14, it is assumed that the target is an AC bias voltage and a DC bias voltage.
In this case, both output signals, AC-PWM signal and DC-PWM signal, are taken into the AND gate, and the AND gate is closed when the feedback signal becomes active.

As a result, the AC bias voltage converges to zero by stopping the DC bias voltage in the developing bias. Note that the clock (CLK) signal shown in FIG. 24 may be taken into the AND gate.
If the AC bias voltage (Vac) and DC bias voltage (Vb) of the development bias voltage are reduced to 70-80% or less of the original output within several ms within which the discharge trace passes, the potential difference does not increase. There is no discharge.
FIG. 17 is a timing chart showing a state of voltage change at the time of discharge detection by the configuration shown in FIG.
In the figure, when the feedback signal is taken into the control board 1000 at the time when the discharge due to the application of the AC bias voltage (Vac (+)) occurs among the development bias voltages, both bias voltages are applied by closing the AND gate. And the AC bias voltage (Vac) starts to converge to zero.
Thereby, the discharge on the positive electrode output side and the discharge on the negative electrode output side are eliminated.

2 Photosensitive member 42 Developing roller 500 Copying machine 1000 Control unit 1001 Voltage supply source 1002 Discharge detection circuit

JP 2006-301479 A Japanese Patent No. 3815356 Japanese Patent No. 4194533 JP 2010-54740 A JP 2010-54741 A

Claims (8)

The developer carrying member is disposed opposite to the latent image carrying member at a predetermined interval, and the developer carrying member is supplied when the non-magnetic one-component toner is supplied from the developer carrying member toward the latent image carrying member. A developing device having a configuration in which a direct current (DC) voltage and an alternating current (AC) voltage are applied in a superimposed manner,
Voltage supply means for applying a superimposed voltage of an AC bias voltage and a DC bias voltage to the developer carrier;
A discharge detecting means for detecting a discharge between the developing carrier and the latent image carrier;
A detection unit from which the detection result from the discharge detection unit is input, and a control unit for changing and controlling the supply voltage in the voltage supply unit,
The control unit stops the bias application in which the polarity is reversed with respect to the polarity detected when the AC bias voltage is applied together with the discharge detection.   2. The control unit according to claim 1, wherein, together with the discharge detection, the AC bias setting voltage having a polarity opposite to the detected AC bias voltage is turned off or zero out of the AC setting voltage. Development device.   3. The developing device according to claim 1, wherein the control unit is provided with an interface in which an AND condition is incorporated in a clock (CLK) signal, and takes in a feedback signal informing the discharge detection into the AND gate condition.   The control unit sets the clock (CLK) signal to an inactive state after receiving a feedback signal informing the discharge detection, and the discharge mark passes through the developing nip portion of the latent image carrier facing the developer carrier. 3. The developing device according to claim 2, wherein the clock (CLK) signal is set to a non-active state within a predetermined time.   3. The development according to claim 2, wherein the control unit is provided with an interface in which an AND condition is incorporated in an AC bias setting signal and a DC bias setting signal, and a feedback signal for notifying discharge detection is taken into the AND gate condition. apparatus.   The control unit sets the AC bias setting signal and the DC bias setting signal to a non-active state after receiving a feedback signal for informing discharge detection, and develops the discharge mark facing the developer carrier on the latent image carrier. 3. The developing device according to claim 2, wherein the clock (CLK) signal is set to a non-active state within a time period of passing through the nip portion. The developer carrying member is disposed opposite to the latent image carrying member at a predetermined interval, and the developer carrying member is supplied when the non-magnetic one-component toner is supplied from the developer carrying member toward the latent image carrying member. A developing device having a configuration in which a direct current (DC) voltage and an alternating current (AC) voltage are applied in a superimposed manner,
Voltage supply means for applying a superimposed voltage of an AC bias voltage and a DC bias voltage to the developer carrier;
A discharge detecting means for detecting a discharge between the developing carrier and the latent image carrier;
A detection unit from which the detection result from the discharge detection unit is input, and a control unit for changing and controlling the supply voltage in the voltage supply unit,
A developing method characterized in that, in the control unit, the bias application in which the polarity is reversed with respect to the polarity detected when the AC bias voltage is applied together with the discharge detection is stopped.   An image forming apparatus using the developing device according to claim 1 or the developing method according to claim 7.

Images